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Sample records for c-flip degradation mediates

  1. The novel Akt inhibitor API-1 induces c-FLIP degradation and synergizes with TRAIL to augment apoptosis independent of Akt inhibition.

    Science.gov (United States)

    Li, Bo; Ren, Hui; Yue, Ping; Chen, Mingwei; Khuri, Fadlo R; Sun, Shi-Yong

    2012-04-01

    API-1 (pyrido[2,3-d]pyrimidines) is a novel small-molecule inhibitor of Akt, which acts by binding to Akt and preventing its membrane translocation and has promising preclinical antitumor activity. In this study, we reveal a novel function of API-1 in regulation of cellular FLICE-inhibitory protein (c-FLIP) levels and TRAIL-induced apoptosis, independent of Akt inhibition. API-1 effectively induced apoptosis in tested cancer cell lines including activation of caspase-8 and caspase-9. It reduced the levels of c-FLIP without increasing the expression of death receptor 4 (DR4) or DR5. Accordingly, it synergized with TRAIL to induce apoptosis. Enforced expression of ectopic c-FLIP did not attenuate API-1-induced apoptosis but inhibited its ability to enhance TRAIL-induced apoptosis. These data indicate that downregulation of c-FLIP mediates enhancement of TRAIL-induced apoptosis by API-1 but is not sufficient for API-1-induced apoptosis. API-1-induced reduction of c-FLIP could be blocked by the proteasome inhibitor MG132. Moreover, API-1 increased c-FLIP ubiquitination and decreased c-FLIP stability. These data together suggest that API-1 downregulates c-FLIP by facilitating its ubiquitination and proteasome-mediated degradation. Because other Akt inhibitors including API-2 and MK2206 had minimal effects on reducing c-FLIP and enhancement of TRAIL-induced apoptosis, it is likely that API-1 reduces c-FLIP and enhances TRAIL-induced apoptosis independent of its Akt-inhibitory activity. 2012 AACR

  2. Inhibition of methyltransferases accelerates degradation of cFLIP and sensitizes B-cell lymphoma cells to TRAIL-induced apoptosis.

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    Frank K Braun

    Full Text Available Non-Hodgkin lymphomas (NHLs are characterized by specific abnormalities that alter cell cycle regulation, DNA damage response, and apoptotic signaling. It is believed that cancer cells are particularly sensitive to cell death induced by tumor necrosis factor α-related apoptosis-inducing ligand (TRAIL. However, many cancer cells show blocked TRAIL signaling due to up-regulated expression of anti-apoptotic factors, such as cFLIP. This hurdle to TRAIL's tumor cytotoxicity might be overcome by combining TRAIL-based therapy with drugs that reverse blockages of its apoptotic signaling. In this study, we investigated the impact of a pan-methyltransferase inhibitor (3-deazaneplanocin A, or DZNep on TRAIL-induced apoptosis in aggressive B-cell NHLs: mantle cell, Burkitt, and diffuse large B-cell lymphomas. We characterized TRAIL apoptosis regulation and caspase activation in several NHL-derived cell lines pre-treated with DZNep. We found that DZNep increased cancer cell sensitivity to TRAIL signaling by promoting caspase-8 processing through accelerated cFLIP degradation. No change in cFLIP mRNA level indicated independence of promoter methylation alterations in methyltransferase activity induced by DZNep profoundly affected cFLIP mRNA stability and protein stability. This appears to be in part through increased levels of cFLIP-targeting microRNAs (miR-512-3p and miR-346. However, additional microRNAs and cFLIP-regulating mechanisms appear to be involved in DZNep-mediated enhanced response to extrinsic apoptotic stimuli. The capacity of DZNep to target cFLIP expression on multiple levels underscores DZNep's potential in TRAIL-based therapies for B-cell NHLs.

  3. Combination of Nexrutine and docetaxel suppresses NFκB-mediated activation of c-FLIP.

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    Zhang, Yangang; Li, Li; Wang, Jingyu; Cheng, Wei; Zhang, Jiandong; Li, Xueting; Zhang, Zhenhua; Gong, Jingjing; Ghosh, Rita; Kumar, Addanki P; Xie, Jianping

    2017-10-01

    Lack of effective options following failure to conventional chemotherapeutic agent such as Docetaxel (DX) is a major clinical challenge in the management of prostate cancer. These observations underscore the need for deciphering the underlying mechanism of DX resistance to enable the development of effective therapeutic approaches. We observed up regulation of the anti-apoptotic protein c-FLIP and its up stream regulators including receptor tyrosine kinase RON and transcription factor NFκB (p65) in tumors obtained from metastatic prostate cancer patients. We also observed significant downregulation of these molecules in prostate tumors isolated from patients treated with DX as first line therapy. Further, we identified the over the counter anti-inflammatory agent, Nexrutine (NX) suppresses c-FLIP protein levels, and expression in androgen-independent prostate cancer cells (PC-3). Remarkably, the observed decreased levels of c-FLIP were further reduced in combination with DX. Transient expression assays coupled with electrophoretic mobility shift and DNA affinity protein assay revealed that NX and DX suppresses c-FLIP promoter activity by preventing p65 binding. Notably, NX in combination with DX abolished binding of p65 to the c-FLIP promoter sequence containing NFκB binding sites. Biologically, these alterations resulted in reduced growth of PC-3 cells. Taken together, these observations suggest the utility of RON, p65, and c-FLIP as potential markers to predict response to DX treatment. Furthermore, our results also identified NX as an agent to potentiate the therapeutic response of DX by suppressing activation of c-FLIP and its upstream regulators. © 2017 Wiley Periodicals, Inc.

  4. Metformin sensitizes human bladder cancer cells to TRAIL-induced apoptosis through mTOR/S6K1-mediated downregulation of c-FLIP.

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    Zhang, Tao; Wang, Xinyang; He, Dalin; Jin, Xunbo; Guo, Peng

    2014-09-01

    Metformin, an oral antidiabetic agent, has been reported to potentiate chemotherapeutic-induced cytotoxicity. In this study, we investigated the effects and molecular mechanisms of metformin in sensitizing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human bladder cancer cells. Metformin alone did not induce apoptosis, but markedly potentiated TRAIL-induced apoptosis in 253J and RT4 bladder cancer cells. To elucidate the underlying mechanism, we examined the modulatory effects of metformin on the key components of the TRAIL signaling pathway and found that metformin did not alter the expression levels of death receptor 4 (DR4) and death receptor 5 (DR5), but significantly reduced the cellular Fas-associated death domain (FADD)-like interleukin-1β-converting enzyme (FLICE) inhibitory protein (c-FLIP) levels, contributing toward the sensitization to TRAIL. Further experiments showed that metformin did not affect the mRNA level, proteasomal degradation, and protein stability of c-FLIPL. However, metformin inhibited the mTOR/S6K1 pathway in 253J and RT4 cells, which usually regulates protein translation; moreover, knockdown of S6K1 effectively reduced the levels of c-FLIPL, indicating that metformin downregulates c-FLIP through inhibition of the mTOR/S6K1 pathway. In addition, AMP-activated protein kinase (AMPK) inhibitor compound C did not prevent the inhibitory effects of metformin on the mTOR/S6K1 pathway and metformin-mediated sensitization to TRAIL. Taken together, our results indicate that metformin sensitizes human bladder cancer cells to TRAIL-induced apoptosis through downregulation of c-FLIP, which is mediated by the mTOR/S6K1 pathway, but independent of AMPK; furthermore, these findings provide a rationale for the combined application of metformin with TRAIL in the treatment of bladder cancer.

  5. Inhibition of Cathepsin S Induces Mitochondrial ROS That Sensitizes TRAIL-Mediated Apoptosis Through p53-Mediated Downregulation of Bcl-2 and c-FLIP.

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    Seo, Bo Ram; Min, Kyoung-Jin; Woo, Seon Min; Choe, Misun; Choi, Kyeong Sook; Lee, Young-Kyung; Yoon, Gyesoon; Kwon, Taeg Kyu

    2017-08-01

    Cathepsin S is highly expressed in various cancer cells, and it has protumoral effects, including promotion of migration, invasion, and neovascularization. In this study, we show that inhibition of cathepsin S could sensitize cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. An inhibitor of cathepsin S (Z-FL-COCHO; ZFL) markedly induced apoptosis in human renal cancer cells treated with TRAIL. In contrast, combined treatment with ZFL and TRAIL had no effect on normal cells. ZFL downregulated Bcl-2 expression at the transcriptional level in a p53-dependent manner, and overexpression of Bcl-2 also markedly blocked apoptosis induced by combined treatment with ZFL and TRAIL. In addition, ZFL induced downregulation of c-FLIP, and overexpression of c-FLIP blocked the apoptosis induced by ZFL plus TRAIL. Moreover, ZFL increased the expression of Cbl, an E3 ligase of c-FLIP, in a p53-dependent manner, and knockdown of Cbl markedly prevented c-FLIP downregulation and the apoptosis induced by ZFL plus TRAIL. Interestingly, ZFL induced p53 expression via production of mitochondrial reactive oxygen species (ROS). We also demonstrated that downregulation of cathepsin S by small interfering RNA sensitized TRAIL-mediated apoptosis in Caki cells. These results reveal the importance of cathepsin S on resistance against TRAIL, and inhibition of cathepsin S activity plays a crucial role in TRAIL-mediated cell death of cancer cells. Our results indicated that inhibition of cathepsin S stimulates TRAIL-induced apoptosis through downregulation of Bcl-2 and Cbl-mediated c-FLIP by ROS-mediated p53 expression. Antioxid. Redox Signal. 27, 215-233.

  6. Osthole enhances TRAIL-mediated apoptosis through downregulation of c-FLIP expression in renal carcinoma Caki cells.

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    Min, Kyoung-Jin; Han, Min Ae; Kim, Shin; Park, Jong-Wook; Kwon, Taeg Kyu

    2017-04-01

    Osthole, an active constituent isolated from the fruit of Cnidium monnieri (L.) Cusson, has been shown to induce various beneficial biochemical effects such as anti-inflammatory and antitumor. In the present study, we examined whether osthole could sensitize TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human renal carcinoma Caki cells. We found that osthole and TRAIL alone, had no effect on apoptosis, but combined treatment with osthole and TRAIL markedly induced apoptosis in Caki (renal carcinoma), U251MG (glioma) and MDA-MB-231 (breast carcinoma) cells. In contrast, combined treatment with osthole and TRAIL did not induce apoptosis in normal human skin fibroblast cells. Osthole induced downregulation of cellular FLICE-like inhibitory protein (c-FLIP) expression, and overexpression of c-FLIP markedly blocked apoptosis induced by the combined treatment with osthole and TRAIL. In addition, osthole markedly reduced mitochondrial membrane potential levels, and increased cytosolic cytochrome c release in combined treatment with osthole and TRAIL. Therefore, these data suggest that osthole may be an efficient TRAIL sensitizer.

  7. Targeting the Anti-Apoptotic Protein c-FLIP for Cancer Therapy

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    Safa, Ahmad R., E-mail: asafa@iupui.edu [Department of Pharmacology and Toxicology, Indiana University School of Medicine, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202 (United States); Indiana University Simon Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202 (United States); Pollok, Karen E. [Department of Pharmacology and Toxicology, Indiana University School of Medicine, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202 (United States); Indiana University Simon Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202 (United States); Herman B. Wells Center for Pediatric Research, 980 W. Walnut Street, R3-C524, Indianapolis, IN 46202 (United States)

    2011-03-29

    Cellular FLICE (FADD-like IL-1beta-converting enzyme)-inhibitory protein (c-FLIP) is a major resistance factor and critical anti-apoptotic regulator that inhibits tumor necrosis factor-alpha (TNF-alpha), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis as well as chemotherapy-triggered apoptosis in malignant cells. c-FLIP is expressed as long (c-FLIP{sub L}), short (c-FLIP{sub S}), and c-FLIP{sub R} splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 in a ligand-dependent and-independent fashion, which in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. Moreover, c-FLIP{sub L} and c-FLIP{sub S} are known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective signaling molecules. Upregulation of c-FLIP has been found in various tumor types, and its downregulation has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. For example, small interfering RNAs (siRNAs) that specifically knockdown the expression of c-FLIP{sub L} in diverse human cancer cell lines augmented TRAIL-induced DISC recruitment and increased the efficacy of chemotherapeutic agents, thereby enhancing effector caspase stimulation and apoptosis. Moreover, small molecules causing degradation of c-FLIP as well as decreasing mRNA and protein levels of c-FLIP{sub L} and c-FLIP{sub S} splice variants have been found, and efforts are underway to develop other c-FLIP-targeted cancer therapies. This review focuses on (1) the functional role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and drug resistance; (2) the molecular mechanisms that regulate c-FLIP expression; and (3) strategies to inhibit c-FLIP expression and function.

  8. Targeting the Anti-Apoptotic Protein c-FLIP for Cancer Therapy

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    Safa, Ahmad R.; Pollok, Karen E.

    2011-01-01

    Cellular FLICE (FADD-like IL-1beta-converting enzyme)-inhibitory protein (c-FLIP) is a major resistance factor and critical anti-apoptotic regulator that inhibits tumor necrosis factor-alpha (TNF-alpha), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis as well as chemotherapy-triggered apoptosis in malignant cells. c-FLIP is expressed as long (c-FLIPL), short (c-FLIPS), and c-FLIPR splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 in a ligand-dependent and-independent fashion, which in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. Moreover, c-FLIPL and c-FLIPS are known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective signaling molecules. Upregulation of c-FLIP has been found in various tumor types, and its downregulation has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. For example, small interfering RNAs (siRNAs) that specifically knockdown the expression of c-FLIPL in diverse human cancer cell lines augmented TRAIL-induced DISC recruitment and increased the efficacy of chemotherapeutic agents, thereby enhancing effector caspase stimulation and apoptosis. Moreover, small molecules causing degradation of c-FLIP as well as decreasing mRNA and protein levels of c-FLIPL and c-FLIPS splice variants have been found, and efforts are underway to develop other c-FLIP-targeted cancer therapies. This review focuses on (1) the functional role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and drug resistance; (2) the molecular mechanisms that regulate c-FLIP expression; and (3) strategies to inhibit c-FLIP expression and function. PMID:22348197

  9. FLIP the Switch: Regulation of Apoptosis and Necroptosis by cFLIP

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    Yuichi Tsuchiya

    2015-12-01

    Full Text Available cFLIP (cellular FLICE-like inhibitory protein is structurally related to caspase-8 but lacks proteolytic activity due to multiple amino acid substitutions of catalytically important residues. cFLIP protein is evolutionarily conserved and expressed as three functionally different isoforms in humans (cFLIPL, cFLIPS, and cFLIPR. cFLIP controls not only the classical death receptor-mediated extrinsic apoptosis pathway, but also the non-conventional pattern recognition receptor-dependent apoptotic pathway. In addition, cFLIP regulates the formation of the death receptor-independent apoptotic platform named the ripoptosome. Moreover, recent studies have revealed that cFLIP is also involved in a non-apoptotic cell death pathway known as programmed necrosis or necroptosis. These functions of cFLIP are strictly controlled in an isoform-, concentration- and tissue-specific manner, and the ubiquitin-proteasome system plays an important role in regulating the stability of cFLIP. In this review, we summarize the current scientific findings from biochemical analyses, cell biological studies, mathematical modeling, and gene-manipulated mice models to illustrate the critical role of cFLIP as a switch to determine the destiny of cells among survival, apoptosis, and necroptosis.

  10. ERK controls epithelial cell death receptor signalling and cellular FLICE-like inhibitory protein (c-FLIP) in ulcerative colitis

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    Seidelin, Jakob Benedict; Coskun, Mehmet; Vainer, Ben

    2013-01-01

    Intestinal epithelial cell (IEC) death signalling through the Fas receptor is impaired in active ulcerative colitis (UC). This is possibly due to the activation of cytoprotective pathways resulting in limitation of the tissue injury secondary to inflammation. We hypothesized that inflammatory...... signalling like the nuclear factor (NF)-κB or mitogen activated protein kinase (MAPK) pathways could be involved in (a) the modification of Fas mediated apoptosis responses and (b) the regulation of the Fas receptor inhibitor cellular FLICE-like inhibitory protein (c-FLIP). Phospho-ERK was upregulated...... were induced by TNF-α, IL-1β and IFN-γ, while IL-10 induced c-FLIPL expression; TNF-α also induced c-FLIPS in primary IECs. Inhibition of NF-κB, JNK and p38 pathways did not affect c-FLIP expression, whereas ERK inhibition by MEK1 RNA silencing and pharmacologic inhibitors decreased c-FLIPS expression...

  11. Protective Roles for Caspase-8 and cFLIP in Adult Homeostasis

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    Ricardo Weinlich

    2013-10-01

    Full Text Available Caspase-8 or cellular FLICE-like inhibitor protein (cFLIP deficiency leads to embryonic lethality in mice due to defects in endothelial tissues. Caspase-8−/− and receptor-interacting protein kinase-3 (RIPK3−/−, but not cFLIP−/− and RIPK3−/−, double-knockout animals develop normally, indicating that caspase-8 antagonizes the lethal effects of RIPK3 during development. Here, we show that the acute deletion of caspase-8 in the gut of adult mice induces enterocyte death, disruption of tissue homeostasis, and inflammation, resulting in sepsis and mortality. Likewise, acute deletion of caspase-8 in a focal region of the skin induces local keratinocyte death, tissue disruption, and inflammation. Strikingly, RIPK3 ablation rescues both phenotypes. However, acute loss of cFLIP in the skin produces a similar phenotype that is not rescued by RIPK3 ablation. TNF neutralization protects from either acute loss of caspase-8 or cFLIP. These results demonstrate that caspase-8-mediated suppression of RIPK3-induced death is required not only during development but also for adult homeostasis. Furthermore, RIPK3-dependent inflammation is dispensable for the skin phenotype.

  12. Expression and biological significance of c-FLIP in human hepatocellular carcinomas

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    Qiao Qing

    2009-02-01

    Full Text Available Abstract Background c-FLIP can be considered as a tumor-progression factor in regard to its anti-apoptotic functions. In the present study, we intended to investigate the expression of c-FLIP in human HCC tissues, and its relation with drug-induced cell apoptosis through the specific inhibition of c-FLIP expression by siRNA in 7721 cells. Methods c-FLIP expression was quantified immunohistochemically in HCC tissues(eighty-six cases, and corresponding noncancerous tissues (fifty-seven cases. Patients with HCC were followed up for cancer recurrence. Then, the c-FLIP gene was silenced with specific siRNA in 7721 HCC cells. c-FLIP expression was detected by RT-PCR, Western Blot and immunocytochemical staining. The cellular viability and cell apoptosis were assayed in vitro with cells treated with doxorubicin. Results Positive immunostaining was detected for c-FLIP in 83.72% (72/86 human HCC tissues, 14.81% (4/27 hepatic cirrhosis, 11.11% (2/18 hepatic hemangioma tissues, and absent in normal hepatic tissues. The overexpression(more than 50% of c-FLIP in HCC adversely affected the recurrence-free survival. Through c-FLIP gene silencing with siRNA, the expressions of c-FLIP mRNA and protein were remarkably down-regulated in 7721 HCC cells. And doxorubicin showed apparent inhibition on cell proliferations, and induced more apoptosis. Conclusion These results indicate that c-FLIP is frequently expressed in human HCCs, and its overexpression implied a lesser probability of recurrence-free survival. The specific silencing of c-FLIP gene can apparently up-regulate drug-induced HCC cell apoptosis, and may have therapeutic potential for the treatment of human HCC.

  13. Autophagy mediates degradation of nuclear lamina.

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    Dou, Zhixun; Xu, Caiyue; Donahue, Greg; Shimi, Takeshi; Pan, Ji-An; Zhu, Jiajun; Ivanov, Andrejs; Capell, Brian C; Drake, Adam M; Shah, Parisha P; Catanzaro, Joseph M; Ricketts, M Daniel; Lamark, Trond; Adam, Stephen A; Marmorstein, Ronen; Zong, Wei-Xing; Johansen, Terje; Goldman, Robert D; Adams, Peter D; Berger, Shelley L

    2015-11-05

    Macroautophagy (hereafter referred to as autophagy) is a catabolic membrane trafficking process that degrades a variety of cellular constituents and is associated with human diseases. Although extensive studies have focused on autophagic turnover of cytoplasmic materials, little is known about the role of autophagy in degrading nuclear components. Here we report that the autophagy machinery mediates degradation of nuclear lamina components in mammals. The autophagy protein LC3/Atg8, which is involved in autophagy membrane trafficking and substrate delivery, is present in the nucleus and directly interacts with the nuclear lamina protein lamin B1, and binds to lamin-associated domains on chromatin. This LC3-lamin B1 interaction does not downregulate lamin B1 during starvation, but mediates its degradation upon oncogenic insults, such as by activated RAS. Lamin B1 degradation is achieved by nucleus-to-cytoplasm transport that delivers lamin B1 to the lysosome. Inhibiting autophagy or the LC3-lamin B1 interaction prevents activated RAS-induced lamin B1 loss and attenuates oncogene-induced senescence in primary human cells. Our study suggests that this new function of autophagy acts as a guarding mechanism protecting cells from tumorigenesis.

  14. Predisposition to apoptosis in keratin 8-null liver is related to inactivation of NF-κB and SAPKs but not decreased c-Flip

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    Jongeun Lee

    2013-05-01

    Keratin 8 and 18 (K8/K18 are major intermediate filament proteins of liver hepatocytes. They provide mechanical and nonmechanical stability, thereby protecting cells from stress. Hence, K8-null mice are highly sensitive to Fas-mediated liver cell apoptosis. However, the role of c-Flip protein in K8-null related susceptibility to liver injury is controversial. Here we analyzed c-Flip protein expression in various K8 or K18 null/mutant transgenic livers and show that they are similar in all analyzed transgenic livers and that previously reported c-Flip protein changes are due to antibody cross-reaction with mouse K18. Furthermore, analysis of various apoptosis- or cell survival-related proteins demonstrated that inhibition of phosphorylation of NF-κB and various stress activated protein kinases (SAPKs, such as p38 MAPK, p44/42 MAPK and JNK1/2, is related to the higher sensitivity of K8-null hepatocytes whose nuclear NF-κB is rapidly depleted through Fas-mediated apoptosis. Notably, we found that NF-κB and the studied protein kinases are associated with the K8/K18 complex and are released upon phosphorylation. Therefore, interaction of keratins with cell survival-related protein kinases and transcription factors is another important factor for hepatocyte survival.

  15. Independent Induction of Caspase-8 and cFLIP Expression during Colorectal Carcinogenesis in Sporadic and HNPCC Adenomas and Carcinomas

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    D. M. Heijink

    2007-01-01

    Full Text Available Background: TNF-Related Apoptosis Inducing Ligand (TRAIL is a promising agent for the induction of apoptosis in neoplastic tissues. Important determinants of TRAIL sensitivity are two intracellular proteins of the TRAIL pathway, caspase-8 and its anti-apoptotic competitor cellular Flice-Like Inhibitory Protein (cFLIP. Methods: The aim of this study was to investigate basic expression of caspase-8 and cFLIP in normal colorectal epithelium (n = 20, colorectal adenomas (n = 66 and colorectal carcinomas (n = 44 using immunohistochemistry performed on both sporadic and Hereditary Non-Polyposis Colorectal Cancer (HNPCC or Lynch syndrome-associated adenomas and carcinomas. Results: Expression of both caspase-8 and cFLIP was similar in cases with sporadic and hereditary origin. Expression of caspase-8 in colorectal adenomas and carcinomas was increased when compared to normal colon tissue (P = 0.02. Nuclear, paranuclear as well as cytoplasmic localizations of caspase-8 were detected. Immunohistochemistry revealed an upregulation of cFLIP in colorectal carcinomas in comparison to normal epithelium and colorectal adenomas (P < 0.001. A large variation in the caspase-8/cFLIP ratio was observed between the individual adenomas and carcinomas. Conclusion: Caspase-8 and cFLIP are upregulated during colorectal carcinogenesis. Upregulation of caspase-8 and/or downregulation of cFLIP may be interesting approaches to maximize TRAIL sensitivity in colorectal neoplasms.

  16. [Effect on keratocyte-mediated collagen degradation by Pseudomonas aeruginosa].

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    Hao, J; Lu, Y; Jia, H; Liu, J; Xu, J; Zhang, R

    2000-01-01

    To study the pathogenesis of cornea melting (ulceration) by pseudomona (P) aeruginosa for instruction of clinical treatment. Type I collagen gels with or without suspended keratocytes were incubated for 24 hours under medium containing sterile P. aeruginosa culture broth. Native collagen fibrils were removed from the media by ultrafiltration. The ultrafiltrates were then hydrolyzed, and the amount of hydroxyproline was measured spectrophotometrically. The effect of a synthetic matrix metalloproteinase (MMP) inhibitor, Galardin, on collagen degradation was also examined. P. aeruginosa broth induced type I collagen gel degradation directly. In the presence of keratocytes, degradation by P. aeruginosa broth was enhanced. Galardin significantly reduced the amount of collagen degraded by P. aeruginosa culture broth, no matter keratocytes were present or not. P. aeruginosa culture broth directly degrades type I collagen and also increases keratocyte-mediated collagen degradation. The result is helpful to the clinical treatment of cornea melting caused by P. aeruginosa, and the mechanism should be further studied.

  17. β-Elemene piperazine derivatives induce apoptosis in human leukemia cells through downregulation of c-FLIP and generation of ROS.

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    Zhiying Yu

    Full Text Available β-Elemene is an active component of the herb medicine Curcuma Wenyujin with reported antitumor activity. To improve its antitumor ability, five novel piperazine derivatives of β-elemene, 13-(3-methyl-1-piperazinyl-β-elemene (DX1, 13-(cis-3,5-dimethyl-1-piperazinyl-β-elemene (DX2, 13-(4-ethyl-1-piperazinyl-β-elemene (DX3, 13-(4-isopropyl-1-piperazinyl-β-elemene (DX4 and 13-piperazinyl-β-elemene (DX5, were synthesized. The antiproliferative and apoptotic effects of these derivatives were determined in human leukemia HL-60, NB4, K562 and HP100-1 cells. DX1, DX2 and DX5, which contain a secondary amino moiety, were more active in inhibiting cell growth and in inducing apoptosis than DX3 and DX4. The apoptosis induction ability of DX1 was associated with the generation of hydrogen peroxide (H(2O(2, a decrease of mitochondrial membrane potential (MMP, and the activation of caspase-8. Pretreatment with the antioxidants N-acetylcysteine and catalase completely blocked DX1-induced H(2O(2 production, but only partially its activation of caspase-8 and induction of apoptosis. HL-60 cells were more sensitive than its H(2O(2-resistant subclone HP100-1 cells to DX1-induced apoptosis. The activation of caspase-8 by these compounds was correlated with the decrease in the levels of cellular FLICE-inhibitory protein (c-FLIP. The proteasome inhibitor MG-132 augmented the decrease in c-FLIP levels and apoptosis induced by these derivatives. FADD- and caspase-8-deficient Jurkat subclones have a decreased response to DX1-induced apoptosis. Our data indicate that these novel β-elemene piperazine derivatives induce apoptosis through the decrease in c-FLIP levels and the production of H(2O(2 which leads to activation of both death receptor- and mitochondrial-mediated apoptotic pathways.

  18. Nanoscale zerovalent iron-mediated degradation of DDT in soil.

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    Han, Yuling; Shi, Nan; Wang, Huifang; Pan, Xiong; Fang, Hua; Yu, Yunlong

    2016-04-01

    Nanoscale zerovalent iron (nZVI)-mediated degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) was investigated in a spiked soil under different conditions (iron sources, iron dosage, soil moisture, temperature, and soil types) and DDT-contaminated field. The degradation efficiency of p,p'-DDT by nZVI and nZVI coated with sodium oleate (SO-nZVI) was much higher than that by nZVI coated with polyimide (PI-nZVI). The rapid degradation of p,p'-DDT by nZVI only occurred in flooded soil. The degradation half-life of p,p'-DDT decreased significantly from 58.3 to 27.6 h with nZVI dosage from 0.5 to 2.0% and from 46.5 to 32.0 h with temperature from 15 to 35 °C. The degradation efficiency of p,p'-DDT by nZVI differed in Jinhua (JH), Jiaxing (JX), Xiaoshan (XS), Huajiachi (HJC), and Heilongjiang (HLJ) soils. A good correlation was found between the degradation half-life of p,p'-DDT and multiple soil properties. The probable nZVI-mediated degradation pathway of p,p'-DDT in soil was proposed as DDT → DDD/DDE → DDNS → DDOH based on the metabolites identified by GC-MS. The in situ degradation efficiency of residual DDTs in a contaminated field was profoundly enhanced by the addition of nZVI as compared to the control. It is concluded that nZVI might be an efficient agent for the remediation of DDT-contaminated soil under anaerobic environment.

  19. The Role of c-FLIP(L) in Regulating Apoptotic Pathways in Prostate Cancer

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    2008-12-01

    tumor cell death. Surgery 1999;126:399–405. 28. Gerdes MJ, Myakishev M, Frost NA, Rishi V, Moitra J, Acharya A, Levy MR, Park SW, Glick A, Yuspa SH...med- icine three-dimensional structure database. J Med Chem 2004; 47: 2430. 28. Li L, Thomas RM, Suzuki H, De Brabander JK, Wang X and Harran PG: A...Voutsinas, G., Thomas -Tsagli, E., Kapralos, P., Patsouris, E., and Saetta, A. A. (2004). c-FLIP expression in bladder urothelial carcino- mas: Its role in

  20. Degradation of AF1Q by chaperone-mediated autophagy

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    Li, Peng; Ji, Min; Lu, Fei; Zhang, Jingru [Department of Hematology, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital, Shandong University, Jinan 250012 (China); Li, Huanjie; Cui, Taixing; Li Wang, Xing [Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital, Shandong University, Jinan 250012 (China); Tang, Dongqi, E-mail: tangdq@sdu.edu.cn [Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital, Shandong University, Jinan 250012 (China); Center for Stem Cell and Regenerative Medicine, The Second Hospital of Shandong University, Jinan 250033 (China); Ji, Chunyan, E-mail: jichunyan@sdu.edu.cn [Department of Hematology, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital, Shandong University, Jinan 250012 (China)

    2014-09-10

    AF1Q, a mixed lineage leukemia gene fusion partner, is identified as a poor prognostic biomarker for pediatric acute myeloid leukemia (AML), adult AML with normal cytogenetic and adult myelodysplastic syndrome. AF1Q is highly regulated during hematopoietic progenitor differentiation and development but its regulatory mechanism has not been defined clearly. In the present study, we used pharmacological and genetic approaches to influence chaperone-mediated autophagy (CMA) and explored the degradation mechanism of AF1Q. Pharmacological inhibitors of lysosomal degradation, such as chloroquine, increased AF1Q levels, whereas activators of CMA, including 6-aminonicotinamide and nutrient starvation, decreased AF1Q levels. AF1Q interacts with HSPA8 and LAMP-2A, which are core components of the CMA machinery. Knockdown of HSPA8 or LAMP-2A increased AF1Q protein levels, whereas overexpression showed the opposite effect. Using an amino acid deletion AF1Q mutation plasmid, we identified that AF1Q had a KFERQ-like motif which was recognized by HSPA8 for CMA-dependent proteolysis. In conclusion, we demonstrate for the first time that AF1Q can be degraded in lysosomes by CMA. - Highlights: • Chaperone-mediated autophagy (CMA) is involved in the degradation of AF1Q. • Macroautophagy does not contribute to the AF1Q degradation. • AF1Q has a KFERQ-like motif that is recognized by CMA core components.

  1. Nitroglycerin degradation mediated by soil organic carbon under aerobic conditions.

    Science.gov (United States)

    Bordeleau, Geneviève; Martel, Richard; Bamba, Abraham N'Valoua; Blais, Jean-François; Ampleman, Guy; Thiboutot, Sonia

    2014-10-01

    The presence of nitroglycerin (NG) has been reported in shallow soils and pore water of several military training ranges. In this context, NG concentrations can be reduced through various natural attenuation processes, but these have not been thoroughly documented. This study aimed at investigating the role of soil organic matter (SOM) in the natural attenuation of NG, under aerobic conditions typical of shallow soils. The role of SOM in NG degradation has already been documented under anoxic conditions, and was attributed to SOM-mediated electron transfer involving different reducing agents. However, unsaturated soils are usually well-oxygenated, and it was not clear whether SOM could participate in NG degradation under these conditions. Our results from batch- and column-type experiments clearly demonstrate that in presence of dissolved organic matter (DOM) leached from a natural soil, partial NG degradation can be achieved. In presence of particulate organic matter (POM) from the same soil, complete NG degradation was achieved. Furthermore, POM caused rapid sorption of NG, which should result in NG retention in the organic matter-rich shallow horizons of the soil profile, thus promoting degradation. Based on degradation products, the reaction pathway appears to be reductive, in spite of the aerobic conditions. The relatively rapid reaction rates suggest that this process could significantly participate in the natural attenuation of NG, both on military training ranges and in contaminated soil at production facilities. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Thrombin-Mediated Degradation of Human Cardiac Troponin T.

    Science.gov (United States)

    Katrukha, Ivan A; Kogan, Alexander E; Vylegzhanina, Alexandra V; Serebryakova, Marina V; Koshkina, Ekaterina V; Bereznikova, Anastasia V; Katrukha, Alexey G

    2017-06-01

    Cardiac troponin T (cTnT) is an acknowledged biomarker of acute myocardial infarction (AMI) that is known to be prone to proteolytic degradation in serum. Such degradation is usually explained by the action of μ-calpain, although there could be other candidates for that role. In the current study, we explored the hypothesis that thrombin-mediated cTnT cleavage occurs as a result of the serum sample preparation. cTnT degradation was studied by using immunoblotting and mass spectrometry (MS) analysis. The comparison of cTnT isolated from AMI heparin plasma and serum samples showed that cTnT in the plasma samples was mainly present as the full-sized molecule (approximately 35 kDa), while in serum samples it was present as a 29-kDa fragment. The incubation of recombinant cTnT, or native ternary cardiac troponin complex with thrombin or in normal human serum (NHS), resulted in the formation of a 29-kDa product that was similar to that detected in AMI serum samples. No cTnT degradation was observed when thrombin or NHS was pretreated with hirudin, a specific inhibitor of thrombin, or during incubation of troponin in normal heparin plasma. When the products of thrombin-mediated cTnT proteolysis were analyzed by MS, 2 fragments consisting of amino acid residues (aar) 2-68 and 69-288 were identified, which suggests that thrombin cleaves cTnT between R68 and S69. The results of this study suggest that the 29-kDa fragment of cTnT in AMI serum samples mainly appears due to the cleavage by thrombin during serum sample preparation. © 2017 American Association for Clinical Chemistry.

  3. Targeting Thioredoxin-1 by dimethyl fumarate induces ripoptosome-mediated cell death.

    Science.gov (United States)

    Schroeder, Anne; Warnken, Uwe; Röth, Daniel; Klika, Karel D; Vobis, Diana; Barnert, Andrea; Bujupi, Fatmire; Oberacker, Tina; Schnölzer, Martina; Nicolay, Jan P; Krammer, Peter H; Gülow, Karsten

    2017-02-24

    Constitutively active NFκB promotes survival of many cancers, especially T-cell lymphomas and leukemias by upregulating antiapoptotic proteins such as inhibitors of apoptosis (IAPs) and FLICE-like inhibitory proteins (cFLIPs). IAPs and cFLIPs negatively regulate the ripoptosome, which mediates cell death in an apoptotic or necroptotic manner. Here, we demonstrate for the first time, that DMF antagonizes NFκB by suppressing Thioredoxin-1 (Trx1), a major regulator of NFκB transcriptional activity. DMF-mediated inhibition of NFκB causes ripoptosome formation via downregulation of IAPs and cFLIPs. In addition, DMF promotes mitochondrial Smac release and subsequent degradation of IAPs, further enhancing cell death in tumor cells displaying constitutive NFκB activity. Significantly, CTCL patients treated with DMF display substantial ripoptosome formation and caspase-3 cleavage in T-cells. DMF induces cell death predominantly in malignant or activated T-cells. Further, we show that malignant T-cells can die by both apoptosis and necroptosis, in contrast to resting T-cells, which are restricted to apoptosis upon DMF administration. In summary, our data provide new mechanistic insight in the regulation of cell death by targeting NFκB via Trx1 in cancer. Thus, interference with Trx1 activity is a novel approach for treatment of NFκB-dependent tumors.

  4. The sesquiterpene lactone eupatolide sensitizes breast cancer cells to TRAIL through down-regulation of c-FLIP expression.

    Science.gov (United States)

    Lee, Jongkyu; Hwangbo, Cheol; Lee, Jung Joon; Seo, Juhee; Lee, Jeong-Hyung

    2010-01-01

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising candidate for cancer therapeutics due to its ability to induce apoptosis selectively in cancer cells. However, sensitivity of cancer cells for induction of apoptosis by TRAIL varies considerably. Therefore, it is important to develop agents that overcome this resistance. We show, for the first time, that eupatolide, the sesquiterpene lactone isolated from the medicinal plant Inula britannica, sensitizes human breast cancer cells to TRAIL-induced apoptosis. Treatment with TRAIL in combination with subtoxic concentrations of eupatolide enhanced the TRAIL-induced cytotoxicity in MCF-7, MDA-MB-231 and MDA-MB-453 breast cancer cells, whereas each reagent alone slightly induced cell death. The combination induced sub-G1 phase DNA content and annexin V-staining in MCF-7 cells, which are major features of apoptosis. Apoptotic characteristics induced by the combined treatment were significantly inhibited by a pan-caspase inhibitor. The sensitization to TRAIL-induced apoptosis was accompanied by the activation of caspase-8 and was concomitant with Bid and poly(ADP-ribose) polymerase (PARP) cleavage. Treatment of eupatolide alone significantly down-regulated the expression of cellular FLICE inhibitory protein (c-FLIP) in MCF-7 cells. Furthermore, enforced expression of c-FLIP significantly attenuated the apoptosis induced by this combination in MCF-7 cells, suggesting a key role for c-FLIP down-regulation in these events. We also observed that euaptolide inhibited AKT phosphorylation in a dose- and time-dependent manner. Moreover, inhibition of Akt by LY294002, a specific PI3K inhibitor, down-regulated c-FLIP expression in MCF-7 cells. Taken together, these results indicate that eupatolide could augment TRAIL-induced apoptosis in human breast cancer cells by down-regulating c-FLIP expression through the inhibition of AKT phosphorylation and be a valuable compound to overcome TRAIL resistance in

  5. Deletion of c-FLIP from CD11bhiMacrophages Prevents Development of Bleomycin-induced Lung Fibrosis.

    Science.gov (United States)

    McCubbrey, Alexandra L; Barthel, Lea; Mohning, Michael P; Redente, Elizabeth F; Mould, Kara J; Thomas, Stacey M; Leach, Sonia M; Danhorn, Thomas; Gibbings, Sophie L; Jakubzick, Claudia V; Henson, Peter M; Janssen, William J

    2018-01-01

    Idiopathic pulmonary fibrosis is a progressive lung disease with complex pathophysiology and fatal prognosis. Macrophages (MΦ) contribute to the development of lung fibrosis; however, the underlying mechanisms and specific MΦ subsets involved remain unclear. During lung injury, two subsets of lung MΦ coexist: Siglec-F hi resident alveolar MΦ and a mixed population of CD11b hi MΦ that primarily mature from immigrating monocytes. Using a novel inducible transgenic system driven by a fragment of the human CD68 promoter, we targeted deletion of the antiapoptotic protein cellular FADD-like IL-1β-converting enzyme-inhibitory protein (c-FLIP) to CD11b hi MΦ. Upon loss of c-FLIP, CD11b hi MΦ became susceptible to cell death. Using this system, we were able to show that eliminating CD11b hi MΦ present 7-14 days after bleomycin injury was sufficient to protect mice from fibrosis. RNA-seq analysis of lung MΦ present during this time showed that CD11b hi MΦ, but not Siglec-F hi MΦ, expressed high levels of profibrotic chemokines and growth factors. Human MΦ from patients with idiopathic pulmonary fibrosis expressed many of the same profibrotic chemokines identified in murine CD11b hi MΦ. Elimination of monocyte-derived MΦ may help in the treatment of fibrosis. We identify c-FLIP and the associated extrinsic cell death program as a potential pathway through which these profibrotic MΦ may be pharmacologically targeted.

  6. Titanium dioxide mediated photocatalytic degradation of monochlorobenzene in aqueous phase.

    Science.gov (United States)

    Huang, Hsin-Hsu; Tseng, Dyi-Hwa; Juang, Lain-Chuen

    2008-03-01

    The reaction sequence for the photocatalytic degradation of monochlorobenzene (MCB) in UV/TiO2 process, including substrate adsorption, degradation, and mineralization, was studied. The theoretical maximum quantity of MCB that could be adsorbed onto TiO2 surface in aqueous phase was 0.18+/-0.04 micromol m(-2) of TiO2. In accordance with the upper limit of the relative surface coverage of MCB molecules to surface hydroxyls of TiO2 was around 2.2%, the water molecules as the major adjacent species near TiO2 surface would compete with MCB molecules. Increasing the initial substrate concentration to an appropriate value or enhancing the affinity between the MCB and the TiO2 surface by adjusting the solution pH would promote the photocatalytic degradation. Experimental results revealed that the neutral medium was beneficial for the degradation of MCB. In comparison, the mineralization was most improved at acidic condition. Generally, 90% of the total organic carbon (TOC) was mineralized after 240 min illumination time in the examined pH range except solution pH 11. The suppressed mineralization of MCB at solution pH 11 was ascribed to the lack of adsorption. A simplified 2-step consecutive kinetic model was used to simulate the mineralization.

  7. Factors mediating the restoration of structurally degraded soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Moldrup, Per; Schjønning, Per

    macroaggregation, decreased bulk density, and increased equivalent pore diameter and tortuosity (derived from measurements of soil-gas diffusivity and soil-air permeability) for all soils. Although aggregate friability was not affected by clay type, aggregate workability was highest for the kaolinitic soil......Soil structure is essential for sustained provision of ecosystem services such as water filtering and storage, waste disposal, carbon sequestration and many more. Structural degradation/disaggregation of soils emanating from human activities such as mining, grading and filling interferes...... with the ability of soils to perform these functions. The present study examines the roles of clay mineralogy, native organic matter, and exogenous organic material on the restoration of structurally degraded soils. Totally seven soils from Denmark and Ghana - five soils dominated by illites, one kaolinitic soil...

  8. Soybean peroxidase-mediated degradation of an azo dye– a detailed mechanistic study

    Science.gov (United States)

    2013-01-01

    Background Peroxidases are emerging as an important class of enzymes that can be used for the efficient degradation of organic pollutants. However, detailed studies identifying the various intermediates produced and the mechanisms involved in the enzyme-mediated pollutant degradation are not widely published. Results In the present study, the enzymatic degradation of an azo dye (Crystal Ponceau 6R, CP6R) was studied using commercially available soybean peroxidase (SBP) enzyme. Several operational parameters affecting the enzymatic degradation of dye were evaluated and optimized, such as initial dye concentration, H2O2 dosage, mediator amount and pH of the solution. Under optimized conditions, 40 ppm dye solution could be completely degraded in under one minute by SBP in the presence of H2O2 and a redox mediator. Dye degradation was also confirmed using HPLC and TOC analyses, which showed that most of the dye was being mineralized to CO2 in the process. Conclusions Detailed analysis of metabolites, based on LC/MS results, showed that the enzyme-based degradation of the CP6R dye proceeded in two different reaction pathways- via symmetric azo bond cleavage as well as asymmetric azo bond breakage in the dye molecule. In addition, various critical transformative and oxidative steps such as deamination, desulfonation, keto-oxidation are explained on an electronic level. Furthermore, LC/MS/MS analyses confirmed that the end products in both pathways were small chain aliphatic carboxylic acids. PMID:24308857

  9. Degradation of regulator of calcineurin 1 (RCAN1) is mediated by both chaperone-mediated autophagy and ubiquitin proteasome pathways.

    Science.gov (United States)

    Liu, Heng; Wang, Pin; Song, Weihong; Sun, Xiulian

    2009-10-01

    Regulator of calcineurin 1 (RCAN1), a gene identified from the critical region of Down syndrome, has been implied in pathogenesis of Alzheimer's disease (AD). RCAN1 expression was shown to be increased in AD brains; however, the mechanism of RCAN1 gene regulation is not well defined. The present study was designed to investigate the molecular mechanism of RCAN1 protein degradation. In addition to being degraded through the ubiquitin proteasome pathway, we found that lysosomal inhibition markedly increased RCAN1 protein expression in a time- and dosage-dependent manner. Inhibition of macroautophagy reduced RCAN1 expression, indicating that RCAN1 degradation is not through a macroautophagy pathway. However, disruption of chaperone-mediated autophagy (CMA) increased RCAN1 expression. Two CMA recognition motifs were identified in RCAN1 protein to mediate its degradation through a CMA-lysosome pathway. A promoter assay further demonstrated that inhibition of RCAN1 degradation in cells reduced calcineurin-NFAT activity. Dysfunctions of ubiquitin-proteasome and autophagy-lysosome pathways have been implicated in neurodegenerative diseases. Therefore, elucidation of RCAN1 degradation by a ubiquitin proteasome pathway and CMA-lysosome pathway in the present study may greatly advance our understanding of AD pathogenesis.

  10. Microbial surfactant mediated degradation of anthracene in aqueous phase by marine Bacillus licheniformis MTCC 5514

    Directory of Open Access Journals (Sweden)

    Sreethar Swaathy

    2014-12-01

    Full Text Available The present study emphasizes the biosurfactant mediated anthracene degradation by a marine alkaliphile Bacillus licheniformis (MTCC 5514. The isolate, MTCC 5514 degraded >95% of 300 ppm anthracene in an aqueous medium within 22 days and the degradation percentage reduced significantly when the concentration of anthracene increased to above 500 ppm. Naphthalene, naphthalene 2-methyl, phthalic acid and benzene acetic acid are the products of degradation identified based on thin layer chromatography, high performance liquid chromatography, gas chromatography and mass analyses. It has been observed that the degradation is initiated by the biosurfactant of the isolate for solubilization through micellation and then the alkali pH and intra/extra cellular degradative enzymes accomplish the degradation process. Encoding of genes responsible for biosurfactant production (licA3 as well as catabolic reactions (C23O made with suitable primers designed. The study concludes in situ production of biosurfactant mediates the degradation of anthracene by B. licheniformis.

  11. Upregulation of c-FLIP-short in response to TRAIL promotes survival of NSCLC cells, which could be suppressed by inhibition of Ca2+/calmodulin signaling

    Czech Academy of Sciences Publication Activity Database

    Kaminskyy, V.O.; Surova, O.V.; Piskunova, T.; Zborovskaya, I.B.; Tchevkina, E.M.; Anděra, Ladislav; Zhivotovsky, B.

    2013-01-01

    Roč. 4, březen 2013 (2013), e522 ISSN 2041-4889 Institutional support: RVO:68378050 Keywords : TRAIL * DR4 * c-FLIPS * calcium * calmodulin * lung adenocarcinoma Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.177, year: 2013

  12. Curcumin Quantum Dots Mediated Degradation of Bacterial Biofilms.

    Science.gov (United States)

    Singh, Ashish K; Prakash, Pradyot; Singh, Ranjana; Nandy, Nabarun; Firdaus, Zeba; Bansal, Monika; Singh, Ranjan K; Srivastava, Anchal; Roy, Jagat K; Mishra, Brahmeshwar; Singh, Rakesh K

    2017-01-01

    Bacterial biofilm has been reported to be associated with more than 80% of bacterial infections. Curcumin, a hydrophobic polyphenol compound, has anti-quorum sensing activity apart from having antimicrobial action. However, its use is limited by its poor aqueous solubility and rapid degradation. In this study, we attempted to prepare quantum dots of the drug curcumin in order to achieve enhanced solubility and stability and investigated for its antimicrobial and antibiofilm activity. We utilized a newer two-step bottom up wet milling approach to prepare Curcumin Quantum Dots (CurQDs) using acetone as a primary solvent. Minimum inhibitory concentration against select Gram-positive and Gram-negative bacteria was performed. The antibiofilm assay was performed at first using 96-well tissue culture plate and subsequently validated by Confocal Laser Scanning Microscopy. Further, biofilm matrix protein was isolated using formaldehyde sludge and TCA/Acetone precipitation method. Protein extracted was incubated with varying concentration of CurQDs for 4 h and was subjected to SDS-PAGE. Molecular docking study was performed to observe interaction between curcumin and phenol soluble modulins as well as curli proteins. The biophysical evidences obtained from TEM, SEM, UV-VIS, fluorescence, Raman spectroscopy, and zeta potential analysis confirmed the formation of curcumin quantum dots with increased stability and solubility. The MICs of curcumin quantum dots, as observed against both select gram positive and negative bacterial isolates, was observed to be significantly lower than native curcumin particles. On TCP assay, Curcumin observed to be having antibiofilm as well as biofilm degrading activity. Results of SDS-PAGE and molecular docking have shown interaction between biofilm matrix proteins and curcumin. The results indicate that aqueous solubility and stability of Curcumin can be achieved by preparing its quantum dots. The study also demonstrates that by sizing down the

  13. Processive endoglucanases mediate degradation of cellulose by Saccharophagus degradans.

    Science.gov (United States)

    Watson, Brian J; Zhang, Haitao; Longmire, Atkinson G; Moon, Young Hwan; Hutcheson, Steven W

    2009-09-01

    Bacteria and fungi are thought to degrade cellulose through the activity of either a complexed or a noncomplexed cellulolytic system composed of endoglucanases and cellobiohydrolases. The marine bacterium Saccharophagus degradans 2-40 produces a multicomponent cellulolytic system that is unusual in its abundance of GH5-containing endoglucanases. Secreted enzymes of this bacterium release high levels of cellobiose from cellulosic materials. Through cloning and purification, the predicted biochemical activities of the one annotated cellobiohydrolase Cel6A and the GH5-containing endoglucanases were evaluated. Cel6A was shown to be a classic endoglucanase, but Cel5H showed significantly higher activity on several types of cellulose, was the highest expressed, and processively released cellobiose from cellulosic substrates. Cel5G, Cel5H, and Cel5J were found to be members of a separate phylogenetic clade and were all shown to be processive. The processive endoglucanases are functionally equivalent to the endoglucanases and cellobiohydrolases required for other cellulolytic systems, thus providing a cellobiohydrolase-independent mechanism for this bacterium to convert cellulose to glucose.

  14. Ubiquitin regulates GGA3-mediated degradation of BACE1.

    Science.gov (United States)

    Kang, Eugene L; Cameron, Andrew N; Piazza, Fabrizio; Walker, Kendall R; Tesco, Giuseppina

    2010-07-30

    BACE1 (beta-site amyloid precursor protein-cleaving enzyme 1) is a membrane-tethered member of the aspartyl proteases, essential for the production of beta-amyloid, a toxic peptide that accumulates in the brain of subjects affected by Alzheimer disease. The BACE1 C-terminal fragment contains a DXXLL motif that has been shown to bind the VHS (VPS27, Hrs, and STAM) domain of GGA1-3 (Golgi-localized gamma-ear-containing ARF-binding proteins). GGAs are trafficking molecules involved in the transport of proteins containing the DXXLL signal from the Golgi complex to endosomes. Moreover, GGAs bind ubiquitin and traffic synthetic and endosomal ubiquitinated cargoes to lysosomes. We have previously shown that depletion of GGA3 results in increased BACE1 levels and activity because of impaired lysosomal degradation. Here, we report that the accumulation of BACE1 is rescued by the ectopic expression of GGA3 in H4 neuroglioma cells depleted of GGA3. Accordingly, the overexpression of GGA3 reduces the levels of BACE1 and beta-amyloid. We then established that mutations in the GGA3 VPS27, Hrs, and STAM domain (N91A) or in BACE1 di-leucine motif (L499A/L500A), able to abrogate their binding, did not affect the ability of ectopically expressed GGA3 to rescue BACE1 accumulation in cells depleted of GGA3. Instead, we found that BACE1 is ubiquitinated at lysine 501 and is mainly monoubiquitinated and Lys-63-linked polyubiquitinated. Finally, a GGA3 mutant with reduced ability to bind ubiquitin (GGA3L276A) was unable to regulate BACE1 levels both in rescue and overexpression experiments. These findings indicate that levels of GGA3 tightly and inversely regulate BACE1 levels via interaction with ubiquitin sorting machinery.

  15. Ubiquitin Regulates GGA3-mediated Degradation of BACE1*

    Science.gov (United States)

    Kang, Eugene L.; Cameron, Andrew N.; Piazza, Fabrizio; Walker, Kendall R.; Tesco, Giuseppina

    2010-01-01

    BACE1 (β-site amyloid precursor protein-cleaving enzyme 1) is a membrane-tethered member of the aspartyl proteases, essential for the production of β-amyloid, a toxic peptide that accumulates in the brain of subjects affected by Alzheimer disease. The BACE1 C-terminal fragment contains a DXXLL motif that has been shown to bind the VHS (VPS27, Hrs, and STAM) domain of GGA1–3 (Golgi-localized γ-ear-containing ARF-binding proteins). GGAs are trafficking molecules involved in the transport of proteins containing the DXXLL signal from the Golgi complex to endosomes. Moreover, GGAs bind ubiquitin and traffic synthetic and endosomal ubiquitinated cargoes to lysosomes. We have previously shown that depletion of GGA3 results in increased BACE1 levels and activity because of impaired lysosomal degradation. Here, we report that the accumulation of BACE1 is rescued by the ectopic expression of GGA3 in H4 neuroglioma cells depleted of GGA3. Accordingly, the overexpression of GGA3 reduces the levels of BACE1 and β-amyloid. We then established that mutations in the GGA3 VPS27, Hrs, and STAM domain (N91A) or in BACE1 di-leucine motif (L499A/L500A), able to abrogate their binding, did not affect the ability of ectopically expressed GGA3 to rescue BACE1 accumulation in cells depleted of GGA3. Instead, we found that BACE1 is ubiquitinated at lysine 501 and is mainly monoubiquitinated and Lys-63-linked polyubiquitinated. Finally, a GGA3 mutant with reduced ability to bind ubiquitin (GGA3L276A) was unable to regulate BACE1 levels both in rescue and overexpression experiments. These findings indicate that levels of GGA3 tightly and inversely regulate BACE1 levels via interaction with ubiquitin sorting machinery. PMID:20484053

  16. Cullin 7 mediates proteasomal and lysosomal degradations of rat Eag1 potassium channels.

    Science.gov (United States)

    Hsu, Po-Hao; Ma, Yu-Ting; Fang, Ya-Ching; Huang, Jing-Jia; Gan, Yu-Ling; Chang, Pei-Tzu; Jow, Guey-Mei; Tang, Chih-Yung; Jeng, Chung-Jiuan

    2017-01-18

    Mammalian Eag1 (Kv10.1) potassium (K+) channels are widely expressed in the brain. Several mutations in the gene encoding human Eag1 K+ channel have been associated with congenital neurodevelopmental anomalies. Currently very little is known about the molecules mediating protein synthesis and degradation of Eag1 channels. Herein we aim to ascertain the protein degradation mechanism of rat Eag1 (rEag1). We identified cullin 7 (Cul7), a member of the cullin-based E3 ubiquitin ligase family, as a novel rEag1 binding partner. Immunoprecipitation analyses confirmed the interaction between Cul7 and rEag1 in heterologous cells and neuronal tissues. Cul7 and rEag1 also exhibited significant co-localization at synaptic regions in neurons. Over-expression of Cul7 led to reduced protein level, enhanced ubiquitination, accelerated protein turn-over, and decreased current density of rEag1 channels. We provided further biochemical and morphological evidence suggesting that Cul7 targeted endoplasmic reticulum (ER)- and plasma membrane-localized rEag1 to the proteasome and the lysosome, respectively, for protein degradation. Cul7 also contributed to protein degradation of a disease-associated rEag1 mutant. Together, these results indicate that Cul7 mediates both proteasomal and lysosomal degradations of rEag1. Our findings provide a novel insight to the mechanisms underlying ER and peripheral protein quality controls of Eag1 channels.

  17. MAPKs are essential upstream signaling pathways in proteolytic cartilage degradation--divergence in pathways leading to aggrecanase and MMP-mediated articular cartilage degradation

    DEFF Research Database (Denmark)

    Sondergaard, B-C; Schultz, N; Madsen, S H

    2010-01-01

    Matrix metalloproteinases (MMPs) and aggrecanases are essential players in cartilage degradation. However, the signaling pathways that results in MMP and/or aggrecanase synthesis and activation are not well understood. We investigated the molecular events leading to MMP- and aggrecanase-mediated ......Matrix metalloproteinases (MMPs) and aggrecanases are essential players in cartilage degradation. However, the signaling pathways that results in MMP and/or aggrecanase synthesis and activation are not well understood. We investigated the molecular events leading to MMP- and aggrecanase......-mediated cartilage degradation....

  18. TAK1 MAPKKK mediates TGF-β signaling by targeting SnoN oncoprotein for degradation

    Science.gov (United States)

    Kajino, Taisuke; Omori, Emily; Ishii, Shunsuke; Matsumoto, Kunihiro; Ninomiya-Tsuji, Jun

    2007-01-01

    Transforming growth factor-β (TGF-β) regulates a variety of physiologic processes through essential intracellular mediators Smads. The SnoN oncoprotein is an inhibitor of TGF-β signaling. SnoN recruits transcriptional repressor complex to block Smad-dependent transcriptional activation of TGF-β-responsive genes. Following TGF-β stimulation, SnoN is rapidly degraded, thereby allowing the activation of TGF-β target genes. Here, we report the role of TAK1 as a SnoN protein kinase. TAK1 interacts with and phosphorylates SnoN, and this phosphorylation regulates the stability of SnoN. Inactivation of TAK1 prevents TGF-β-induced SnoN degradation, and impairs induction of the TGF-β-responsive genes. These data suggest that TAK1 modulates TGF-β dependent cellular responses by targeting SnoN for degradation. PMID:17276978

  19. Human macrophage foam cells degrade atherosclerotic plaques through cathepsin K mediated processes

    DEFF Research Database (Denmark)

    Barascuk, Natasha; Skjøt-Arkil, Helene; Register, Thomas C

    2010-01-01

    BACKGROUND: Proteolytic degradation of Type I Collagen by proteases may play an important role in remodeling of atherosclerotic plaques, contributing to increased risk of plaque rupture.The aim of the current study was to investigate whether human macrophage foam cells degrade the extracellular......-I in areas of intimal hyperplasia and in shoulder regions of advanced plaques. Treatment of human monocytes with M-CSF or M-CSF+LDL generated macrophages and foam cells producing CTX-I when cultured on type I collagen enriched matrix. Circulating levels of CTX-I were not significantly different in women...... with aortic calcifications compared to those without. CONCLUSIONS: Human macrophage foam cells degrade the atherosclerotic plaques though cathepsin K mediated processes, resulting in increase in levels of CTX-I. Serum CTX-I was not elevated in women with aortic calcification, likely due to the contribution...

  20. Mass dependent stable isotope fractionation of mercury during mer mediated microbial degradation of monomethylmercury

    Science.gov (United States)

    Kritee, K.; Barkay, Tamar; Blum, Joel D.

    2009-03-01

    Controlling bioaccumulation of toxic monomethylmercury (MMHg) in aquatic food chains requires differentiation between biotic and abiotic pathways that lead to its production and degradation. Recent mercury (Hg) stable isotope measurements of natural samples suggest that Hg isotope ratios can be a powerful proxy for tracing dominant Hg transforming pathways in aquatic ecosystems. Specifically, it has been shown that photo-degradation of MMHg causes both mass dependent (MDF) and mass independent fractionation (MIF) of Hg isotopes. Because the extent of MDF and MIF observed in natural samples (e.g., fish, soil and sediments) can potentially be used to determine the relative importance of pathways leading to MMHg accumulation, it is important to determine the potential role of microbial pathways in contributing to the fractionation, especially MIF, observed in these samples. This study reports the extent of fractionation of Hg stable isotopes during degradation of MMHg to volatile elemental Hg and methane via the microbial Hg resistance ( mer) pathway in Escherichia coli carrying a mercury resistance ( mer) genetic system on a multi-copy plasmid. During experimental microbial degradation of MMHg, MMHg remaining in reactors became progressively heavier (increasing δ202Hg) with time and underwent mass dependent Rayleigh fractionation with a fractionation factor α202/198 = 1.0004 ± 0.0002 (2SD). However, MIF was not observed in any of the microbial MMHg degradation experiments indicating that the isotopic signature left by mer mediated MMHg degradation is significantly different from fractionation observed during DOC mediated photo-degradation of MMHg. Additionally, a clear suppression of Hg isotope fractionation, both during reduction of Hg(II) and degradation of MMHg, was observed when the cell densities increased, possibly due to a reduction in substrate bioavailability. We propose a multi-step framework for understanding the extent of fractionation seen in our MMHg

  1. ROS-Mediated 15-Hydroxyprostaglandin Dehydrogenase Degradation via Cysteine Oxidation Promotes NAD+-Mediated Epithelial-Mesenchymal Transition.

    Science.gov (United States)

    Wang, Weixuan; Hu, Yadong; Wang, Xiaofei; Wang, Qingtao; Deng, Haiteng

    2017-12-27

    Nicotinamide adenine dinucleotide (NAD) levels decrease with aging as a result of aging-associated CD38 upregulation. Here, we established a cell model with decreased cellular NAD levels by overexpressing CD38 or treating cells with FK866, an inhibitor of nicotinamide phosphoribosyltransferase. We revealed that decreased NAD triggered reactive oxygen species (ROS)-mediated degradation of 15-hydroxyprostaglandin dehydrogenase (15-PGDH), which drove cells to undergo epithelial-mesenchymal transition (EMT). Moreover, we showed that oxidation of the Cys44 residue to sulfonic acid in 15-PGDH led to its degradation via non-canonical ubiquitination-proteasome and autophagy pathways. Mutation of Cys44 to alanine abolished ROS-induced 15-PGDH degradation. We demonstrated that 15-PGDH silencing promoted EMT, whereas supplementation with NAD precursors increased NAD and 15-PGDH stability, and reversed the EMT process. Taken together, these results suggest that declining NAD levels contribute to age-dependent increases in cancer incidence, and repletion of NAD precursors is beneficial for increasing 15-PGDH expression. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. CHIP-mediated degradation of transglutaminase 2 negatively regulates tumor growth and angiogenesis in renal cancer.

    Science.gov (United States)

    Min, B; Park, H; Lee, S; Li, Y; Choi, J-M; Lee, J Y; Kim, J; Choi, Y D; Kwon, Y-G; Lee, H-W; Bae, S-C; Yun, C-O; Chung, K C

    2016-07-14

    The multifunctional enzyme transglutaminase 2 (TG2) primarily catalyzes cross-linking reactions of proteins via (γ-glutamyl) lysine bonds. Several recent findings indicate that altered regulation of intracellular TG2 levels affects renal cancer. Elevated TG2 expression is observed in renal cancer. However, the molecular mechanism underlying TG2 degradation is not completely understood. Carboxyl-terminus of Hsp70-interacting protein (CHIP) functions as an ubiquitin E3 ligase. Previous studies reveal that CHIP deficiency mice displayed a reduced life span with accelerated aging in kidney tissues. Here we show that CHIP promotes polyubiquitination of TG2 and its subsequent proteasomal degradation. In addition, TG2 upregulation contributes to enhanced kidney tumorigenesis. Furthermore, CHIP-mediated TG2 downregulation is critical for the suppression of kidney tumor growth and angiogenesis. Notably, our findings are further supported by decreased CHIP expression in human renal cancer tissues and renal cancer cells. The present work reveals that CHIP-mediated TG2 ubiquitination and proteasomal degradation represent a novel regulatory mechanism that controls intracellular TG2 levels. Alterations in this pathway result in TG2 hyperexpression and consequently contribute to renal cancer.

  3. Intracellular collagen degradation mediated by uPARAP/Endo180 is a major pathway of extracellular matrix turnover during malignancy

    DEFF Research Database (Denmark)

    Curino, Alejandro C; Engelholm, Lars H; Yamada, Susan S

    2005-01-01

    We recently reported that uPARAP/Endo180 can mediate the cellular uptake and lysosomal degradation of collagen by cultured fibroblasts. Here, we show that uPARAP/Endo180 has a key role in the degradation of collagen during mammary carcinoma progression. In the normal murine mammary gland, uPARAP/...

  4. Particulate matter air pollution disrupts endothelial cell barrier via calpain-mediated tight junction protein degradation

    Directory of Open Access Journals (Sweden)

    Wang Ting

    2012-08-01

    Full Text Available Abstract Background Exposure to particulate matter (PM is a significant risk factor for increased cardiopulmonary morbidity and mortality. The mechanism of PM-mediated pathophysiology remains unknown. However, PM is proinflammatory to the endothelium and increases vascular permeability in vitro and in vivo via ROS generation. Objectives We explored the role of tight junction proteins as targets for PM-induced loss of lung endothelial cell (EC barrier integrity and enhanced cardiopulmonary dysfunction. Methods Changes in human lung EC monolayer permeability were assessed by Transendothelial Electrical Resistance (TER in response to PM challenge (collected from Ft. McHenry Tunnel, Baltimore, MD, particle size >0.1 μm. Biochemical assessment of ROS generation and Ca2+ mobilization were also measured. Results PM exposure induced tight junction protein Zona occludens-1 (ZO-1 relocation from the cell periphery, which was accompanied by significant reductions in ZO-1 protein levels but not in adherens junction proteins (VE-cadherin and β-catenin. N-acetyl-cysteine (NAC, 5 mM reduced PM-induced ROS generation in ECs, which further prevented TER decreases and atteneuated ZO-1 degradation. PM also mediated intracellular calcium mobilization via the transient receptor potential cation channel M2 (TRPM2, in a ROS-dependent manner with subsequent activation of the Ca2+-dependent protease calpain. PM-activated calpain is responsible for ZO-1 degradation and EC barrier disruption. Overexpression of ZO-1 attenuated PM-induced endothelial barrier disruption and vascular hyperpermeability in vivo and in vitro. Conclusions These results demonstrate that PM induces marked increases in vascular permeability via ROS-mediated calcium leakage via activated TRPM2, and via ZO-1 degradation by activated calpain. These findings support a novel mechanism for PM-induced lung damage and adverse cardiovascular outcomes.

  5. Particulate matter air pollution disrupts endothelial cell barrier via calpain-mediated tight junction protein degradation.

    Science.gov (United States)

    Wang, Ting; Wang, Lichun; Moreno-Vinasco, Liliana; Lang, Gabriel D; Siegler, Jessica H; Mathew, Biji; Usatyuk, Peter V; Samet, Jonathan M; Geyh, Alison S; Breysse, Patrick N; Natarajan, Viswanathan; Garcia, Joe G N

    2012-08-29

    Exposure to particulate matter (PM) is a significant risk factor for increased cardiopulmonary morbidity and mortality. The mechanism of PM-mediated pathophysiology remains unknown. However, PM is proinflammatory to the endothelium and increases vascular permeability in vitro and in vivo via ROS generation. We explored the role of tight junction proteins as targets for PM-induced loss of lung endothelial cell (EC) barrier integrity and enhanced cardiopulmonary dysfunction. Changes in human lung EC monolayer permeability were assessed by Transendothelial Electrical Resistance (TER) in response to PM challenge (collected from Ft. McHenry Tunnel, Baltimore, MD, particle size >0.1 μm). Biochemical assessment of ROS generation and Ca2+ mobilization were also measured. PM exposure induced tight junction protein Zona occludens-1 (ZO-1) relocation from the cell periphery, which was accompanied by significant reductions in ZO-1 protein levels but not in adherens junction proteins (VE-cadherin and β-catenin). N-acetyl-cysteine (NAC, 5 mM) reduced PM-induced ROS generation in ECs, which further prevented TER decreases and atteneuated ZO-1 degradation. PM also mediated intracellular calcium mobilization via the transient receptor potential cation channel M2 (TRPM2), in a ROS-dependent manner with subsequent activation of the Ca2+-dependent protease calpain. PM-activated calpain is responsible for ZO-1 degradation and EC barrier disruption. Overexpression of ZO-1 attenuated PM-induced endothelial barrier disruption and vascular hyperpermeability in vivo and in vitro. These results demonstrate that PM induces marked increases in vascular permeability via ROS-mediated calcium leakage via activated TRPM2, and via ZO-1 degradation by activated calpain. These findings support a novel mechanism for PM-induced lung damage and adverse cardiovascular outcomes.

  6. Effect of budesonide on fibroblast-mediated collagen gel contraction and degradation

    Directory of Open Access Journals (Sweden)

    Fang Q

    2013-02-01

    Full Text Available Qiuhong Fang,1,2 Nancy A Schulte,3 Huijung Kim,4 Tetsu Kobayashi,5 Xingqi Wang,2 Anna Miller-Larsson,6 Elisabet Wieslander,6 Myron L Toews,3 Xiangde Liu,2 Stephen I Rennard21Pulmonary and Critical Care Department, Beijing Shijitan Hospital, Capital Medical University, Beijing, People's Republic of China; 2Pulmonary, Critical Care, Sleep and Allergy Division, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; 3Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA; 4Pulmonary and Critical Care Division, WonKwang University, Kunpo Medical Center, Seoul, Republic of Korea; 5Mie University Graduate School of Medicine, Tsu City, Japan; 6AstraZeneca R&D Molndal, Molndal, SwedenBackground: The balance between production and degradation of extracellular matrix is crucial in maintaining normal tissue structure. This study was designed to investigate the effect of budesonide on fibroblast-mediated tissue repair and remodeling.Methods: Using human fetal lung fibroblasts in a three-dimensional collagen gel culture system, we investigated the effect of budesonide (1–1000 nM on collagen gel contraction and degradation in the presence or absence of inflammatory cytokines (interleukin-1β and tumor necrosis factor α; 5 ng/mL each and, in order to activate latent proteases, serine protease trypsin 0.25 µg/mL. The effects of budesonide on metalloproteinase production and activation were also investigated.Results: Inflammatory cytokines significantly inhibited collagen gel contraction mediated by lung fibroblasts. Budesonide counteracted the effect of cytokines in a concentration-dependent manner (to 50%, P < 0.01. Budesonide 100 nM almost completely inhibited the release and mRNA expression of metalloproteinase-1, metalloproteinase-3, and metalloproteinase-9 induced by the cytokines (P < 0.05. Exposure to the cytokines plus trypsin increased collagen degradation and

  7. M2-like macrophages are responsible for collagen degradation through a mannose receptor-mediated pathway

    DEFF Research Database (Denmark)

    Madsen, Daniel H; Leonard, Daniel; Masedunskas, Andrius

    2013-01-01

    Tissue remodeling processes critically depend on the timely removal and remodeling of preexisting collagen scaffolds. Nevertheless, many aspects related to the turnover of this abundant extracellular matrix component in vivo are still incompletely understood. We therefore took advantage of recent...... of the collagen receptors mannose receptor (Mrc1) and urokinase plasminogen activator receptor-associated protein (Endo180 and Mrc2) impaired this intracellular collagen degradation pathway. This study demonstrates the importance of receptor-mediated cellular uptake to collagen turnover in vivo and identifies...

  8. Collagen-binding peptidoglycans inhibit MMP mediated collagen degradation and reduce dermal scarring.

    Directory of Open Access Journals (Sweden)

    Kate Stuart

    Full Text Available Scarring of the skin is a large unmet clinical problem that is of high patient concern and impact. Wound healing is complex and involves numerous pathways that are highly orchestrated, leaving the skin sealed, but with abnormal organization and composition of tissue components, namely collagen and proteoglycans, that are then remodeled over time. To improve healing and reduce or eliminate scarring, more rapid restoration of healthy tissue composition and organization offers a unique approach for development of new therapeutics. A synthetic collagen-binding peptidoglycan has been developed that inhibits matrix metalloproteinase-1 and 13 (MMP-1 and MMP-13 mediated collagen degradation. We investigated the synthetic peptidoglycan in a rat incisional model in which a single dose was delivered in a hyaluronic acid (HA vehicle at the time of surgery prior to wound closure. The peptidoglycan treatment resulted in a significant reduction in scar tissue at 21 days as measured by histology and visual analysis. Improved collagen architecture of the treated wounds was demonstrated by increased tensile strength and transmission electron microscopy (TEM analysis of collagen fibril diameters compared to untreated and HA controls. The peptidoglycan's mechanism of action includes masking existing collagen and inhibiting MMP-mediated collagen degradation while modulating collagen organization. The peptidoglycan can be synthesized at low cost with unique design control, and together with demonstrated preclinical efficacy in reducing scarring, warrants further investigation for dermal wound healing.

  9. DDB1-Mediated CRY1 Degradation Promotes FOXO1-Driven Gluconeogenesis in Liver.

    Science.gov (United States)

    Tong, Xin; Zhang, Deqiang; Charney, Nicholas; Jin, Ethan; VanDommelen, Kyle; Stamper, Kenneth; Gupta, Neil; Saldate, Johnny; Yin, Lei

    2017-10-01

    Targeted protein degradation through ubiquitination is an important step in the regulation of glucose metabolism. Here, we present evidence that the DDB1-CUL4A ubiquitin E3 ligase functions as a novel metabolic regulator that promotes FOXO1-driven hepatic gluconeogenesis. In vivo, hepatocyte-specific Ddb1 deletion leads to impaired hepatic gluconeogenesis in the mouse liver but protects mice from high-fat diet-induced hyperglycemia. Lack of Ddb1 downregulates FOXO1 protein expression and impairs FOXO1-driven gluconeogenic response. Mechanistically, we discovered that DDB1 enhances FOXO1 protein stability via degrading the circadian protein cryptochrome 1 (CRY1), a known target of DDB1 E3 ligase. In the Cry1 depletion condition, insulin fails to reduce the nuclear FOXO1 abundance and suppress gluconeogenic gene expression. Chronic depletion of Cry1 in the mouse liver not only increases FOXO1 protein but also enhances hepatic gluconeogenesis. Thus, we have identified the DDB1-mediated CRY1 degradation as an important target of insulin action on glucose homeostasis. © 2017 by the American Diabetes Association.

  10. Effect of matrix metalloproteinase-mediated matrix degradation on glioblastoma cell behavior in 3D PEG-based hydrogels.

    Science.gov (United States)

    Wang, Christine; Tong, Xinming; Jiang, Xinyi; Yang, Fan

    2017-03-01

    Glioblastoma (GBM) is the most common and aggressive form of primary brain tumor with median survival of 12 months. To improve clinical outcomes, it is critical to develop in vitro models that support GBM proliferation and invasion for deciphering tumor progression and screening drug candidates. A key hallmark of GBM cells is their extreme invasiveness, a process mediated by matrix metalloproteinase (MMP)-mediated degradation of the extracellular matrix. We recently reported the development of a MMP-degradable, poly(ethylene-glycol)-based hydrogel platform for culturing GBM cells. In the present study, we modulated the percentage of MMP-degradable crosslinks in 3D hydrogels to analyze the effects of MMP-degradability on GBM fates. Using an immortalized GBM cell line (U87) as a model cell type, our results showed that MMP-degradability was not required for supporting GBM proliferation. All hydrogel formulations supported robust GBM proliferation, up to 10 fold after 14 days. However, MMP-degradability was essential for facilitating tumor spreading, and 50% MMP-degradable hydrogels were sufficient to enable both robust tumor cell proliferation and spreading in 3D. The findings of this study highlight the importance of modulating MMP-degradability in engineering 3D in vitro brain cancer models and may be applied for engineering in vitro models for other cancer types. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 770-778, 2017. © 2016 Wiley Periodicals, Inc.

  11. Photocatalytic degradation of wastewater pollutants: titanium dioxide mediated degradation of methyl orange and beta-naphthol orange.

    Science.gov (United States)

    Antharjanam, Sudhadevi; Philip, Robert; Suresh, Das

    2003-01-01

    The photocatalytic degradation of azo dyes such as methyl orange and beta-naphthol orange in aqueous suspensions of TiO2 has been investigated under a variety of conditions. The kinetics of degradation was studied under different conditions such as reaction pH, substrate and catalyst concentration, and types of titanium dioxide used and in the presence of electron acceptors and electron donors. The degradation rates of the dyes have been found to be strongly influenced by all the above parameters. Carbon dioxide yield measurements indicate that only partial mineralization occurs in the initial phase of oxidation.

  12. Exonuclease-mediated degradation of nascent RNA silences genes linked to severe malaria

    DEFF Research Database (Denmark)

    Zhang, Qingfeng; Siegel, T Nicolai; Martins, Rafael M

    2014-01-01

    malaria. The mechanism determining upsA activation remains unknown. Here we show that an entirely new type of gene silencing mechanism involving an exonuclease-mediated degradation of nascent RNA controls the silencing of genes linked to severe malaria. We identify a novel chromatin......RNase II and upsA-type var genes in parasites from severe malaria patients, implying a crucial role of PfRNase II in severe malaria. Our results uncover a previously unknown type of post-transcriptional gene silencing mechanism in malaria parasites with repercussions for other organisms. Additionally......, the identification of RNase II as a parasite protein controlling the expression of virulence genes involved in pathogenesis in patients with severe malaria may provide new strategies for reducing malaria mortality....

  13. BRK targets Dok1 for ubiquitin-mediated proteasomal degradation to promote cell proliferation and migration.

    Directory of Open Access Journals (Sweden)

    Sayem Miah

    Full Text Available Breast tumor kinase (BRK, also known as protein tyrosine kinase 6 (PTK6, is a non-receptor tyrosine kinase overexpressed in more that 60% of human breast carcinomas. The overexpression of BRK has been shown to sensitize mammary epithelial cells to mitogenic signaling and to promote cell proliferation and tumor formation. The molecular mechanisms of BRK have been unveiled by the identification and characterization of BRK target proteins. Downstream of tyrosine kinases 1 or Dok1 is a scaffolding protein and a substrate of several tyrosine kinases. Herein we show that BRK interacts with and phosphorylates Dok1 specifically on Y362. We demonstrate that this phosphorylation by BRK significantly downregulates Dok1 in a ubiquitin-proteasome-mediated mechanism. Together, these results suggest a novel mechanism of action of BRK in the promotion of tumor formation, which involves the targeting of tumor suppressor Dok1 for degradation through the ubiquitin proteasomal pathway.

  14. AKT1-mediated Lamin A/C degradation is required for nuclear degradation and normal epidermal terminal differentiation

    OpenAIRE

    Naeem, A S; Zhu, Y.; Di, W L; Marmiroli, S.; O Shaughnessy, R. F. L.

    2015-01-01

    Nuclear degradation is a key stage in keratinocyte terminal differentiation and the formation of the cornified envelope that comprises the majority of epidermal barrier function. Parakeratosis, the retention of nuclear material in the cornified layer of the epidermis, is a common histological observation in many skin diseases, notably in atopic dermatitis and psoriasis. Keratinocyte nuclear degradation is not well characterised, and it is unclear whether the retained nuclei contribute to the ...

  15. Fbxl12 triggers G1 arrest by mediating degradation of calmodulin kinase I.

    Science.gov (United States)

    Mallampalli, Rama K; Kaercher, Leah; Snavely, Courtney; Pulijala, Roopa; Chen, Bill B; Coon, Tiffany; Zhao, Jing; Agassandian, Marianna

    2013-10-01

    Cell cycle progression through its regulatory control by changes in intracellular Ca(2+) levels at the G1/S transition mediates cellular proliferation and viability. Ca(2+)/CaM-dependent kinase 1 (CaMKI) appears critical in regulating the assembly of the cyclin D1/cdk4 complex essential for G1 progression, but how this occurs is unknown. Cyclin D1/cdk4 assembly in the early G1 phase is also regulated via binding to p27. Here, we show that a ubiquitin E3 ligase component, F-box protein Fbxl12, mediates CaMKI degradation via a proteasome-directed pathway leading to disruption of cyclin D1/cdk4 complex assembly and resultant G1 arrest in lung epithelia. We also demonstrate that i) CaMKI phosphorylates p27 at Thr(157) and Thr(198) in human cells and at Thr(170) and Thr(197) in mouse cells to modulate its subcellular localization; ii) Fbxl12-induced CaMKI degradation attenuates p27 phosphorylation at these sites in early G1 and iii) activation of CaMKI during G1 transition followed by p27 phosphorylation appears to be upstream to other p27 phosphorylation events, an effect abrogated by Fbxl12 overexpression. Lastly, known inducers of G1 arrest significantly increase Fbxl12 levels in cells. Thus, Fbxl12 may be a previously uncharacterized, functional growth inhibitor regulating cell cycle progression that might be used for mechanism-based therapy. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  16. M2-like macrophages are responsible for collagen degradation through a mannose receptor–mediated pathway

    Science.gov (United States)

    Madsen, Daniel H.; Leonard, Daniel; Masedunskas, Andrius; Moyer, Amanda; Jürgensen, Henrik Jessen; Peters, Diane E.; Amornphimoltham, Panomwat; Selvaraj, Arul; Yamada, Susan S.; Brenner, David A.; Burgdorf, Sven; Engelholm, Lars H.; Behrendt, Niels; Holmbeck, Kenn; Weigert, Roberto

    2013-01-01

    Tissue remodeling processes critically depend on the timely removal and remodeling of preexisting collagen scaffolds. Nevertheless, many aspects related to the turnover of this abundant extracellular matrix component in vivo are still incompletely understood. We therefore took advantage of recent advances in optical imaging to develop an assay to visualize collagen turnover in situ and identify cell types and molecules involved in this process. Collagen introduced into the dermis of mice underwent cellular endocytosis in a partially matrix metalloproteinase–dependent manner and was subsequently routed to lysosomes for complete degradation. Collagen uptake was predominantly executed by a quantitatively minor population of M2-like macrophages, whereas more abundant Col1a1-expressing fibroblasts and Cx3cr1-expressing macrophages internalized collagen at lower levels. Genetic ablation of the collagen receptors mannose receptor (Mrc1) and urokinase plasminogen activator receptor–associated protein (Endo180 and Mrc2) impaired this intracellular collagen degradation pathway. This study demonstrates the importance of receptor-mediated cellular uptake to collagen turnover in vivo and identifies a key role of M2-like macrophages in this process. PMID:24019537

  17. ATM regulates Mre11-dependent DNA end-degradation and microhomology-mediated end joining.

    Science.gov (United States)

    Rahal, Elias A; Henricksen, Leigh A; Li, Yuling; Williams, R Scott; Tainer, John A; Dixon, Kathleen

    2010-07-15

    The human disorder ataxia telangiectasia (AT), which is characterized by genetic instability and neurodegeneration, results from mutation of the ataxia telangiectasia mutated (ATM) kinase. The loss of ATM leads to cell cycle checkpoint deficiencies and other DNA damage signaling defects that do not fully explain all pathologies associated with A-T including neuronal loss. In addressing this enigma, we find here that ATM suppresses DNA double-strand break (DSB) repair by microhomology-mediated end joining (MMEJ). We show that ATM repression of DNA end-degradation is dependent on its kinase activities and that Mre11 is the major nuclease behind increased DNA end-degradation and MMEJ repair in A-T. Assessment of MMEJ by an in vivo reporter assay system reveals decreased levels of MMEJ repair in Mre11-knockdown cells and in cells treated with Mre11-nuclease inhibitor mirin. Structure-based modeling of Mre11 dimer engaging DNA ends suggests the 5' ends of a bridged DSB are juxtaposed such that DNA unwinding and 3'-5' exonuclease activities may collaborate to facilitate simultaneous pairing of extended 5' termini and exonucleolytic degradation of the 3' ends in MMEJ. Together our results provide an integrated understanding of ATM and Mre11 in MMEJ: ATM has a critical regulatory function in controlling DNA end-stability and error-prone DSB repair and Mre11 nuclease plays a major role in initiating MMEJ in mammalian cells. These functions of ATM and Mre11 could be particularly important in neuronal cells, which are post-mitotic and therefore depend on mechanisms other than homologous recombination between sister chromatids to repair DSBs.

  18. PCSK9-mediated degradation of the LDL receptor generates a 17 kDa C-terminal LDL receptor fragment.

    Science.gov (United States)

    Tveten, Kristian; Strøm, Thea Bismo; Berge, Knut Erik; Leren, Trond P

    2013-06-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the LDL receptor (LDLR) at the cell surface and reroutes the internalized LDLR to intracellular degradation. In this study, we have shown that PCSK9-mediated degradation of the full-length 160 kDa LDLR generates a 17 kDa C-terminal LDLR fragment. This fragment was not generated from mutant LDLRs resistant to PCSK9-mediated degradation or when degradation was prevented by chemicals such as ammonium chloride or the cysteine cathepsin inhibitor E64d. The observation that the 17 kDa fragment was only detected when the cells were cultured in the presence of the γ-secretase inhibitor DAPT indicates that this 17 kDa fragment undergoes γ-secretase cleavage within the transmembrane domain. The failure to detect the complementary 143 kDa ectodomain fragment is likely to be due to its rapid degradation in the endosomal lumen. The 17 kDa C-terminal LDLR fragment was also generated from a Class 5 mutant LDLR undergoing intracellular degradation. Thus, one may speculate that an LDLR with bound PCSK9 and a Class 5 LDLR with bound LDL are degraded by a similar mechanism that could involve ectodomain cleavage in the endosome.

  19. A covalently bound inhibitor triggers EZH2 degradation through CHIP-mediated ubiquitination.

    Science.gov (United States)

    Wang, Xu; Cao, Wei; Zhang, Jianjun; Yan, Ming; Xu, Qin; Wu, Xiangbing; Wan, Lixin; Zhang, Zhiyuan; Zhang, Chenping; Qin, Xing; Xiao, Meng; Ye, Dongxia; Liu, Yuyang; Han, Zeguang; Wang, Shaomeng; Mao, Li; Wei, Wenyi; Chen, Wantao

    2017-05-02

    Enhancer of zeste homolog 2 (EZH2) has been characterized as a critical oncogene and a promising drug target in human malignant tumors. The current EZH2 inhibitors strongly suppress the enhanced enzymatic function of mutant EZH2 in some lymphomas. However, the recent identification of a PRC2- and methyltransferase-independent role of EZH2 indicates that a complete suppression of all oncogenic functions of EZH2 is needed. Here, we report a unique EZH2-targeting strategy by identifying a gambogenic acid (GNA) derivative as a novel agent that specifically and covalently bound to Cys668 within the EZH2-SET domain, triggering EZH2 degradation through COOH terminus of Hsp70-interacting protein (CHIP)-mediated ubiquitination. This class of inhibitors significantly suppressed H3K27Me3 and effectively reactivated polycomb repressor complex 2 (PRC2)-silenced tumor suppressor genes. Moreover, the novel inhibitors significantly suppressed tumor growth in an EZH2-dependent manner, and tumors bearing a non-GNA-interacting C668S-EZH2 mutation exhibited resistance to the inhibitors. Together, our results identify the inhibition of the signaling pathway that governs GNA-mediated destruction of EZH2 as a promising anti-cancer strategy. © 2017 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

  20. Endothelial SIRT1 prevents adverse arterial remodeling by facilitating HERC2-mediated degradation of acetylated LKB1

    DEFF Research Database (Denmark)

    Bai, Bo; Man, Andy W C; Yang, Kangmin

    2016-01-01

    Aims-SIRT1 exerts potent activity against cellular senescence and vascular ageing. By decreasing LKB1 protein levels, it promotes the survival and regeneration of endothelial cells. The present study aims to investigate the molecular mechanisms underlying SIRT1-mediated LKB1 degradation for the p...

  1. Polyclonal HER2-specific antibodies induced by vaccination mediate receptor internalization and degradation in tumor cells

    Science.gov (United States)

    2012-01-01

    Introduction Sustained HER2 signaling at the cell surface is an oncogenic mechanism in a significant proportion of breast cancers. While clinically effective therapies targeting HER2 such as mAbs and tyrosine kinase inhibitors exist, tumors overexpressing HER2 eventually progress despite treatment. Thus, abrogation of persistent HER2 expression at the plasma membrane to synergize with current approaches may represent a novel therapeutic strategy. Methods We generated polyclonal anti-HER2 antibodies (HER2-VIA) by vaccinating mice with an adenovirus expressing human HER2, and assessed their signaling effects in vitro and anti-tumor effects in a xenograft model. In addition, we studied the signaling effects of human HER2-specific antibodies induced by vaccinating breast cancer patients with a HER2 protein vaccine. Results HER2-VIA bound HER2 at the plasma membrane, initially activating the downstream kinases extracellular signal-regulated protein kinase 1/2 and Akt, but subsequently inducing receptor internalization in clathrin-coated pits in a HER2 kinase-independent manner, followed by ubiquitination and degradation of HER2 into a 130 kDa fragment phosphorylated at tyrosine residues 1,221/1,222 and 1,248. Following vaccination of breast cancer patients with the HER2 protein vaccine, HER2-specific antibodies were detectable and these antibodies bound to cell surface-expressed HER2 and inhibited HER2 signaling through blocking tyrosine 877 phosphorylation of HER2. In contrast to the murine antibodies, human anti-HER2 antibodies induced by protein vaccination did not mediate receptor internalization and degradation. Conclusion These data provide new insight into HER2 trafficking at the plasma membrane and the changes induced by polyclonal HER2-specific antibodies. The reduction of HER2 membrane expression and HER2 signaling by polyclonal antibodies induced by adenoviral HER2 vaccines supports human clinical trials with this strategy for those breast cancer patients

  2. Semiconductor-mediated photocatalysed degradation of two selected azo dye derivatives, amaranth and bismarck brown in aqueous suspension.

    Science.gov (United States)

    Tariq, M Abu; Faisal, M; Muneer, M

    2005-12-09

    Semiconductor-mediated photocatalysed degradation of two selected azo dye derivatives such as amaranth (1) and bismarck brown (2) has been investigated in aqueous suspension by monitoring the change in substrate concentration employing UV spectroscopic analysis technique as a function of irradiation time. The degradation was studied under different conditions such as types of TiO(2), pH, substrate concentration, catalyst concentration, and in the presence of electron acceptors such as hydrogen peroxide (H(2)O(2)), potassium bromate (KBrO(3)) and ammonium persulphate (NH(4))(2)S(2)O(8) besides air. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 showed comparatively highest photocatalytic activity. The dye derivative, bismarck brown (2) was found to degrade faster than amaranth dye (1).

  3. Xilei San Ameliorates Experimental Colitis in Rats by Selectively Degrading Proinflammatory Mediators and Promoting Mucosal Repair

    Directory of Open Access Journals (Sweden)

    Yongbiao Hao

    2014-01-01

    Full Text Available Xilei san (XLS, a herbal preparation widely used in China for erosive and ulcerative diseases, has been shown to be effective in ulcerative colitis (UC. The present experiments were conducted to assess its efficacy and determine its mechanism of action in a rat model that resembles human UC. The model was induced by adding 4% dextran sulfate sodium (DSS to the rats’ drinking water for 7 days. XLS was administered daily by retention enema from day 2 to day 7; the rats were sacrificed on day 8. The colon tissues were obtained for further experiments. A histological damage score and the activity of tissue myeloperoxidase were used to evaluate the severity of the colitis. The colonic cytokine levels were detected in a suspension array, and epithelial proliferation was assessed using Ki-67 immunohistochemistry. Intrarectal administration of XLS attenuated the DSS-induced colitis, as evidenced by a reduction in both the histological damage score and myeloperoxidase activity. It also decreased the levels of proinflammatory cytokines, but increased the mucosal repair-related cytokines. In addition, the epithelial Ki-67 expression was upregulated by XLS. These results suggest that XLS attenuates DSS-induced colitis by degrading proinflammatory mediators and promoting mucosal repair. XLS could be a potential topical treatment for human UC.

  4. Hypolipidemic activity of okra is mediated through inhibition of lipogenesis and upregulation of cholesterol degradation.

    Science.gov (United States)

    Wang, Hong; Chen, Gu; Ren, Dandan; Yang, Shang-Tian

    2014-02-01

    Little is known about the hypolipidemic activity of okra; therefore, we investigated the hypolipidemic activity of okra and its interaction with gene expression of several key components involved in lipid homeostasis. Male C57BL/6 mice were randomly divided into three groups and fed with hyperlipidemic diet or two hyperlipidemic diets supplemented with 1% or 2% okra powder for eight weeks. Results demonstrated that okra dose-dependently decreased serum and hepatic total cholesterol and triglyceride, and enhanced fecal excretion of bile acids. Gene expression analysis revealed that okra upregulated cholesterol 7α-hydroxylase (CYP7A1) expression, downregulated expression of sterol regulatory element-binding protein 1c (SREBP1c) and fatty acid synthase (FAS), with no effect on sterol regulatory element-binding protein 2 (SREBP2), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), low-density lipoprotein receptor (LDLR) and carnitine palmitoyltransferase-1A (CPT1A). It was suggested that hypolipidemic activity of okra was mediated most likely by upregulation of cholesterol degradation through CYP7A1 and by inhibition of lipogenesis through SREBP1c and FAS. Okra raw and fractionated polysaccharide showed strong bile acid binding capacity in vitro, which may contribute to the hypolipidemic activity observed. In conclusion, okra has potential application in the management of hyperlipidemia and its associated metabolic disorders. Copyright © 2013 John Wiley & Sons, Ltd.

  5. Memory formation for trace fear conditioning requires ubiquitin-proteasome mediated protein degradation in the prefrontal cortex.

    Directory of Open Access Journals (Sweden)

    David S Reis

    2013-10-01

    Full Text Available The cellular mechanisms supporting plasticity during memory consolidation have been a subject of considerable interest. De novo protein and mRNA synthesis in several brain areas are critical, and more recently protein degradation, mediated by the ubiquitin-proteasome system (UPS, has been shown to be important. Previous work clearly establishes a relationship between protein synthesis and protein degradation in the amygdala, but it is unclear whether cortical mechanisms of memory consolidation are similar to those in the amygdala. Recent work demonstrating a critical role for prefrontal cortex (PFC in the acquisition and consolidation of fear memory allows us to address this question. Here we use a PFC-dependent fear conditioning protocol to determine whether UPS mediated protein degradation is necessary for memory consolidation in PFC. Groups of rats were trained with auditory delay or trace fear conditioning and sacrificed 60 min after training. PFC tissue was then analyzed to quantify the amount of polyubiquinated protein. Other animals were trained with similar procedures but were infused with either a proteasome inhibitor (clasto-lactacystin β-lactone or a translation inhibitor (anisomycin in the PFC immediately after training. Our results show increased UPS-mediated protein degradation in the PFC following trace but not delay fear conditioning. Additionally, post-training proteasome or translation inhibition significantly impaired trace but not delay fear memory when tested the next day. Our results further support the idea that the PFC is critical for trace but not delay fear conditioning highlight the role of UPS-mediated degradation as critical for synaptic plasticity.

  6. IDOL stimulates clathrin-independent endocytosis and multivesicular body-mediated lysosomal degradation of the low-density lipoprotein receptor.

    Science.gov (United States)

    Scotti, Elena; Calamai, Martino; Goulbourne, Chris N; Zhang, Li; Hong, Cynthia; Lin, Ron R; Choi, Jinkuk; Pilch, Paul F; Fong, Loren G; Zou, Peng; Ting, Alice Y; Pavone, Francesco S; Young, Stephen G; Tontonoz, Peter

    2013-04-01

    The low-density lipoprotein receptor (LDLR) is a critical determinant of plasma cholesterol levels that internalizes lipoprotein cargo via clathrin-mediated endocytosis. Here, we show that the E3 ubiquitin ligase IDOL stimulates a previously unrecognized, clathrin-independent pathway for LDLR internalization. Real-time single-particle tracking and electron microscopy reveal that IDOL is recruited to the plasma membrane by LDLR, promotes LDLR internalization in the absence of clathrin or caveolae, and facilitates LDLR degradation by shuttling it into the multivesicular body (MVB) protein-sorting pathway. The IDOL-dependent degradation pathway is distinct from that mediated by PCSK9 as only IDOL employs ESCRT (endosomal-sorting complex required for transport) complexes to recognize and traffic LDLR to lysosomes. Small interfering RNA (siRNA)-mediated knockdown of ESCRT-0 (HGS) or ESCRT-I (TSG101) components prevents IDOL-mediated LDLR degradation. We further show that USP8 acts downstream of IDOL to deubiquitinate LDLR and that USP8 is required for LDLR entry into the MVB pathway. These results provide key mechanistic insights into an evolutionarily conserved pathway for the control of lipoprotein receptor expression and cellular lipid uptake.

  7. Induction of increased cAMP levels in articular chondrocytes blocks matrix metalloproteinase-mediated cartilage degradation, but not aggrecanase-mediated cartilage degradation

    DEFF Research Database (Denmark)

    Karsdal, Morten Asser; Sumer, Eren Ufuk; Wulf, Helle

    2007-01-01

    -dependently inhibited by forskolin and IBMX. The highest concentration of IBMX lowered cytokine-induced release of sGAG by 72%. CONCLUSION: Levels of cAMP in chondrocytes play a key role in controlling catabolic activity. Increased cAMP levels in chondrocytes inhibited MMP expression and activity and consequently......OBJECTIVE: Calcitonin has been suggested to have chondroprotective effects. One signaling pathway of calcitonin is via the second messenger cAMP. We undertook this study to investigate whether increased cAMP levels in chondrocytes would be chondroprotective. METHODS: Cartilage degradation...... was induced in bovine articular cartilage explants by 10 ng/ml oncostatin M (OSM) and 20 ng/ml tumor necrosis factor (TNF). In these cultures, cAMP levels were augmented by treatment with either forskolin (4, 16, or 64 microM) or 3-isobutyl-1-methyl xanthine (IBMX; 4, 16, or 64 microM). Cartilage degradation...

  8. Predicting effects on oxaliplatin clearance: in vitro, kinetic and clinical studies of calcium- and magnesium-mediated oxaliplatin degradation.

    Science.gov (United States)

    Han, Catherine H; Khwaounjoo, Prashannata; Hill, Andrew G; Miskelly, Gordon M; McKeage, Mark J

    2017-06-22

    This study evaluated the impact of calcium and magnesium on the in vitro degradation and in vivo clearance of oxaliplatin. Intact oxaliplatin and Pt(DACH)Cl2 were measured in incubation solutions by HPLC-UV. A clinical study determined changes in plasma concentrations of calcium and magnesium in cancer patients and their impact on oxaliplatin clearance. Kinetic analyses modelled oxaliplatin degradation reactions in vitro and contributions to oxaliplatin clearance in vivo. Calcium and magnesium accelerated oxaliplatin degradation to Pt(DACH)Cl2 in chloride-containing solutions in vitro. Kinetic models based on calcium and magnesium binding to a monochloro-monooxalato ring-opened anionic oxaliplatin intermediate fitted the in vitro degradation time-course data. In cancer patients, calcium and magnesium plasma concentrations varied and were increased by giving calcium gluconate and magnesium sulfate infusions, but did not alter or correlate with oxaliplatin clearance. The intrinsic in vitro clearance of oxaliplatin attributed to chloride-, calcium- and magnesium-mediated degradation predicted contributions of vitro degradation of oxaliplatin by binding to a monochloro-monooxalato ring-opened anionic intermediate. Kinetic analysis of in vitro oxaliplatin stability data can be used for in vitro prediction of potential effects on oxaliplatin clearance in vivo.

  9. CasA mediates Cas3-catalyzed target degradation during CRISPR RNA-guided interference.

    Science.gov (United States)

    Hochstrasser, Megan L; Taylor, David W; Bhat, Prashant; Guegler, Chantal K; Sternberg, Samuel H; Nogales, Eva; Doudna, Jennifer A

    2014-05-06

    In bacteria, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) DNA-targeting complex Cascade (CRISPR-associated complex for antiviral defense) uses CRISPR RNA (crRNA) guides to bind complementary DNA targets at sites adjacent to a trinucleotide signature sequence called the protospacer adjacent motif (PAM). The Cascade complex then recruits Cas3, a nuclease-helicase that catalyzes unwinding and cleavage of foreign double-stranded DNA (dsDNA) bearing a sequence matching that of the crRNA. Cascade comprises the CasA-E proteins and one crRNA, forming a structure that binds and unwinds dsDNA to form an R loop in which the target strand of the DNA base pairs with the 32-nt RNA guide sequence. Single-particle electron microscopy reconstructions of dsDNA-bound Cascade with and without Cas3 reveal that Cascade positions the PAM-proximal end of the DNA duplex at the CasA subunit and near the site of Cas3 association. The finding that the DNA target and Cas3 colocalize with CasA implicates this subunit in a key target-validation step during DNA interference. We show biochemically that base pairing of the PAM region is unnecessary for target binding but critical for Cas3-mediated degradation. In addition, the L1 loop of CasA, previously implicated in PAM recognition, is essential for Cas3 activation following target binding by Cascade. Together, these data show that the CasA subunit of Cascade functions as an essential partner of Cas3 by recognizing DNA target sites and positioning Cas3 adjacent to the PAM to ensure cleavage.

  10. FYVE1/FREE1 Interacts with the PYL4 ABA Receptor and Mediates its Delivery to the Vacuolar Degradation Pathway.

    Science.gov (United States)

    Belda-Palazon, Borja; Rodriguez, Lesia; Fernandez, Maria A; Castillo, Mari-Cruz; Anderson, Erin A; Gao, Caiji; González-Guzmán, Miguel; Peirats-Llobet, Marta; Zhao, Qiong; De Winne, Nancy; Gevaert, Kris; De Jaeger, Geert; Jiang, Liwen; Leon, Jose; Mullen, Robert T; Rodriguez, Pedro L

    2016-08-05

    Recently, we described the ubiquitylation of PYL4 and PYR1 by the RING E3 ubiquitin ligase RSL1 at the plasma membrane of Arabidopsis thaliana. This suggested that ubiquitylated ABA receptors might be targeted to the vacuolar degradation pathway because such ubiquitylation is usually an internalization signal for the endocytic route. Here, we show that FYVE1 (previously termed FREE1), a recently described component of the endosomal sorting complex required for transport (ESCRT) machinery, interacted with RSL1-receptor complexes and recruited PYL4 to endosomal compartments. Although the ESCRT pathway has been assumed to be reserved for integral membrane proteins, we show the involvement of this pathway in the degradation of ABA receptors, which can be associated with membranes but are not integral membrane proteins. Knock-down fyve1 alleles are hypersensitive to ABA, illustrating the biological relevance of the ESCRT pathway for the modulation of ABA signaling. In addition, fyve1 mutants are impaired in the targeting of ABA receptors for vacuolar degradation, leading to increased accumulation of PYL4 and an enhanced response to ABA. Pharmacological and genetic approaches revealed a dynamic turnover of ABA receptors from the plasma membrane to the endosomal/vacuolar degradation pathway, which was mediated by FYVE1 and was dependent on RSL1. This process involves clathrin-mediated endocytosis and trafficking of PYL4 through the ESCRT pathway, which helps to regulate the turnover of ABA receptors and attenuate ABA signaling. © 2016 American Society of Plant Biologists. All rights reserved.

  11. The abiotic degradation of methyl parathion in anoxic sulfur-containing system mediated by natural organic matter.

    Science.gov (United States)

    Liao, Xiaoping; Zhang, Caixiang; Wang, Yanxin; Tang, Mi

    2017-06-01

    Although the kinetics and transformation of methyl parathion have been investigated extensively, its abiotic degradation mechanism in anoxic sulfur-containing groundwater system is still not clear. In this work, the abiotic degradation of methyl parathion in anoxic sulfur-containing system mediated by natural organic matter (NOM) was investigated in batch experiments. It was found that the removal of methyl parathion (up to 80.7%) was greatly improved in sulfide containing NOM compared to those in sulfide alone (with 15.5%) and in NOM alone (almost negligible). Various sulfur species presented significant differences in behaviors methyl parathion degradation, but followed by the pseudo-first-order model well. No facilitated degradation of methyl parathion was observed in sulfite (SO32-) or thiosulfate (S2O32-) containing NOM such as anthraquinone. Although elemental sulfur (S0) and cysteine could further improve the degradation rate of methyl parahtion, their impacts was very limited. The removal efficiency of methyl parathion in anoxic sulfur-containing system were related remarkably with NOM concentration and solution pH. Based on the transformation products identified by gas chromatography-mass spectrometer (GC/MS) and liquid chromatography high resolution mass spectrometer (LC/HRMS), both the nitro group reduction and hydrolysis (SN@C) processes by sulfide (HS-) were further proved to be two predominant reaction mechanisms for the abiotic degradation of methyl parathion in anoxic sulfur-containing system. The results of this study help to understand the natural attenuation of methyl parathion under anoxic sulfide-containing groundwater system mediated by NOM. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Reduced miR-512 and the Elevated Expression of Its Targets cFLIP and MCL1 Localize to Neurons With Hyperphosphorylated Tau Protein in Alzheimer Disease.

    Science.gov (United States)

    Mezache, Louisa; Mikhail, Madison; Garofalo, Michela; Nuovo, Gerard J

    2015-10-01

    The cause for the neurofibrillary tangles and plaques in Alzheimer disease likely relates to an abnormal accumulation of their key components, which include β-amyloid and hyperphosphorylated tau protein. We segregated Alzheimer brain sections from people with end-stage disease into those with abundant hyperphosphorylated tau protein and those without and compared each to normal brains for global microRNA patterns. A significant reduced expression of several microRNAs, including miR-512, was evident in the Alzheimer brain sections with abundant hyperphosphorylated tau. Immunohistochemistry documented that 2 known targets of microRNA-512, cFLIP and MCL1, were significantly over expressed and each colocalized to neurons with the abnormal tau protein. Analysis for apoptosis including activated caspase-3, increased caspase-4 and caspase-8, apoptosis initiating factor, APAF-1 activity, and the TUNEL assay was negative in the areas where neurons showed hyperphosphorylated tau. MCM2 expression, a marker of neuroprogenitor cells, was significantly reduced in the Alzheimer sections that contained the hyperphosphorylated tau. These results suggest that a basic defect in Alzheimer disease may be the reduced microRNA-driven increased expression of proteins that may alter the apoptotic/antiapoptotic balance of neurons. This, in turn, could lead to the accumulation of key Alzheimer proteins such as hyperphosphorylated tau that ultimately prevent normal neuronal function and lead to disease symptomatology.

  13. Lysosome biogenesis mediated by vps-18 affects apoptotic cell degradation in Caenorhabditis elegans.

    Science.gov (United States)

    Xiao, Hui; Chen, Didi; Fang, Zhou; Xu, Jing; Sun, Xiaojuan; Song, Song; Liu, Jiajia; Yang, Chonglin

    2009-01-01

    Appropriate clearance of apoptotic cells (cell corpses) is an important step of programmed cell death. Although genetic and biochemical studies have identified several genes that regulate the engulfment of cell corpses, how these are degraded after being internalized in engulfing cell remains elusive. Here, we show that VPS-18, the Caenorhabditis elegans homologue of yeast Vps18p, is critical to cell corpse degradation. VPS-18 is expressed and functions in engulfing cells. Deletion of vps-18 leads to significant accumulation of cell corpses that are not degraded properly. Furthermore, vps-18 mutation causes strong defects in the biogenesis of endosomes and lysosomes, thus affecting endosomal/lysosomal protein degradation. Importantly, we demonstrate that phagosomes containing internalized cell corpses are unable to fuse with lysosomes in vps-18 mutants. Our findings thus provide direct evidence for the important role of endosomal/lysosomal degradation in proper clearance of apoptotic cells during programmed cell death.

  14. Iron-mediated stabilization of soil carbon amplifies the benefits of ecological restoration in degraded lands.

    Science.gov (United States)

    Silva, Lucas C R; Doane, Timothy A; Corrêa, Rodrigo S; Valverde, Vinicius; Pereira, Engil I P; Horwath, William R

    2015-07-01

    unsuccessful attempts to restore mined areas through nutrient application alone, iron-mediated stabilization of vegetation inputs favored the regeneration of a barren stable state that had persisted for over five decades since disturbance. The effectiveness of coupled organic matter and iron "fertilization," combined with management of invasive species, has the possibility to enhance terrestrial carbon sequestration and accelerate the restoration of degraded lands, while addressing important challenges associated with urban waste disposal.

  15. Titanium Dioxide-Mediated Photcatalysed Degradation of Two Herbicide Derivatives Chloridazon and Metribuzin in Aqueous Suspensions

    Directory of Open Access Journals (Sweden)

    A. Khan

    2012-01-01

    Full Text Available The aim of this paper is to find out the optimal degradation condition for two potential environmental pollutants, chloridazon and metribuzin (herbicide derivatives, employing advanced oxidation process using TiO2 photocatalyst in aqueous suspensions. The degradation/mineralization of the herbicide was monitored by measuring the change in pollutant concentration and depletion in TOC content as a function of time. A detailed degradation kinetics was studied under different conditions such as types of TiO2 (anatase/anatase-rutile mixture, catalyst concentration, herbicide concentration, initial reaction pH, and in the presence of electron acceptors (hydrogen peroxide, ammonium persulphate, potassium persulphate in addition to atmospheric oxygen. The photocatalyst, Degussa P25, was found to be more efficient catalyst for the degradation of both herbicides as compared with two other commercially available TiO2 powders like Hombikat UV100 and PC500. Chloridazon (CHL was found to degrade more efficiently under acidic condition, whereas metribuzin (MET degraded faster under alkaline medium. All three electron acceptors tested in this study were found to enhance the degradation rate of both herbicides.

  16. Urokinase receptor mediates doxorubicin-induced vascular smooth muscle cell senescence via proteasomal degradation of TRF2.

    Science.gov (United States)

    Hodjat, Mahshid; Haller, Hermann; Dumler, Inna; Kiyan, Yulia

    2013-01-01

    The anthracycline doxorubicin is a widely used effective anti-cancer drug. However, its application and dosage are severely limited due to its cardiotoxicity. The exact mechanisms of doxorubicin-induced cardiotoxic side effects remain poorly understood. Even less is known about the impact of doxorubicin treatment on vascular damage. We found that low doses of doxorubicin induced a senescent response in human primary vascular smooth muscle cells (VSMC). We observed that expression of urokinase receptor (uPAR) was upregulated in response to doxorubicin. Furthermore, the level of uPAR expression played a decisive role in developing doxorubicin-induced senescence. uPAR silencing in human VSMC by means of RNA interference as well as uPAR knockout in mouse VSMC resulted in abrogation of doxorubicin-induced cellular senescence. On the contrary, uPAR overexpression promoted VSMC senescence. We further found that proteasomal degradation of telomeric repeat binding factor 2 (TRF2) mediates doxorubicin-induced VSMC senescence. Our results demonstrate that uPAR controls the ubiquitin-proteasome system in VSMC and regulates doxorubicin-induced TRF2 ubiquitination and proteasomal degradation via this mechanism. Therefore, VSMC senescence induced by low doses of doxorubicin may contribute to vascular damage upon doxorubicin treatment. uPAR-mediated TRF2 ubiquitination and proteasomal degradation are further identified as a molecular mechanism underlying this process. Copyright © 2012 S. Karger AG, Basel.

  17. Singlet oxygen mediated DNA degradation by copper nanoparticles: potential towards cytotoxic effect on cancer cells

    Science.gov (United States)

    2011-01-01

    The DNA degradation potential and anti-cancer activities of copper nanoparticles of 4-5 nm size are reported. A dose dependent degradation of isolated DNA molecules by copper nanoparticles through generation of singlet oxygen was observed. Singlet oxygen scavengers such as sodium azide and Tris [hydroxyl methyl] amino methane were able to prevent the DNA degradation action of copper nanoparticles confirming the involvement of activated oxygen species in the degradation process. Additionally, it was observed that the copper nanoparticles are able to exert cytotoxic effect towards U937 and Hela cells of human histiocytic lymphoma and human cervical cancer origins, respectively by inducing apoptosis. The growth characteristics of U937 and Hela cells were studied applying various concentrations of the copper nanoparticles. PMID:21439072

  18. Cytokinin inhibits the proteasome-mediated degradation of carbonylated proteins in Arabidopsis leaves

    Science.gov (United States)

    Under normal conditions, plants contain numerous carbonylated proteins, which are thought to be indicative of oxidative stress damage. Conditions that promote formation of reactive oxygen species (ROS) enhance protein carbonylation, and protein degradation is required to reverse the damage. However,...

  19. CRM 1-mediated degradation and agonist-induced down-regulation of beta-adrenergic receptor mRNAs.

    Science.gov (United States)

    Bai, Ying; Lu, Huafei; Machida, Curtis A

    2006-10-01

    The beta1-adrenergic receptor (beta1-AR) mRNAs are post-transcriptionally regulated at the level of mRNA stability and undergo accelerated agonist-mediated degradation via interaction of its 3' untranslated region (UTR) with RNA binding proteins, including the HuR nuclear protein. In a previous report [Kirigiti et al. (2001). Mol. Pharmacol. 60:1308-1324], we examined the agonist-mediated down-regulation of the rat beta1-AR mRNAs, endogenously expressed in the rat C6 cell line and ectopically expressed in transfectant hamster DDT1MF2 and rat L6 cells. In this report, we determined that isoproterenol treatment of neonatal rat cortical neurons, an important cell type expressing beta1-ARs in the brain, results in significant decreases in beta1-AR mRNA stability, while treatment with leptomycin B, an inhibitor of the nuclear export receptor CRM 1, results in significant increases in beta1-AR mRNA stability and nuclear retention. UV-crosslinking/immunoprecipitation and glycerol gradient fractionation analyses indicate that the beta1-AR 3' UTR recognize complexes composed of HuR and multiple proteins, including CRM 1. Cell-permeable peptides containing the leucine-rich nuclear export signal (NES) were used as inhibitors of CRM 1-mediated nuclear export. When DDT1MF2 transfectants were treated with isoproterenol and peptide inhibitors, only the co-addition of the NES inhibitor reversed the isoproterenol-induced reduction of beta1-AR mRNA levels. Our results suggest that CRM 1-dependent NES-mediated mechanisms influence the degradation and agonist-mediated down-regulation of the beta1-AR mRNAs.

  20. Trypsin-mediated enzymatic degradation of type II collagen in the human vitreous

    Science.gov (United States)

    van Deemter, Mariëlle; Kuijer, Roel; Harm Pas, Hendri; Jacoba van der Worp, Roelofje; Hooymans, Johanna Martina Maria

    2013-01-01

    Purpose Aging of the vitreous body can result in sight-threatening pathology. One aspect of vitreous aging is liquefaction, which results from the vanishing of collagen fibrils. We investigated the possibility that trypsins are involved in vitreous type II collagen degradation. Methods Immunohistochemistry and western blotting were used for detecting and locating trypsin isoforms in the vitreous and retina of human donor eyes. The capability of the retina to produce these trypsins was analyzed with polymerase chain reaction. Whether the different trypsins degraded type II collagen was tested in vitro. The sizes of the in vitro induced type II collagen degradation products were compared to those present in the vitreous of human eyes of different ages. Results Trypsin-1 and trypsin-2 were detected in the vitreous. In the retina, messenger ribonucleic acid (mRNA) coding for trypsin-2, -3, and -4 was present. Using immunohistochemistry, trypsin-2 was detected in microglial cells located in the vitreous and the retina. All trypsin isoforms degraded type II collagen and produced degradation products of similar sizes as those present in the vitreous. Conclusions Trypsin-1 and trypsin-2 appear to have a function in the degradation of vitreous type II collagen. They could therefore have a role in the development of vitreous liquefaction. PMID:23882137

  1. A novel role for ATM in regulating proteasome-mediated protein degradation through suppression of the ISG15 conjugation pathway.

    Directory of Open Access Journals (Sweden)

    Laurence M Wood

    2011-01-01

    Full Text Available Ataxia Telangiectasia (A-T is an inherited immunodeficiency disorder wherein mutation of the ATM kinase is responsible for the A-T pathogenesis. Although the precise role of ATM in A-T pathogenesis is still unclear, its function in responding to DNA damage has been well established. Here we demonstrate that in addition to its role in DNA repair, ATM also regulates proteasome-mediated protein turnover through suppression of the ISG15 pathway. This conclusion is based on three major pieces of evidence: First, we demonstrate that proteasome-mediated protein degradation is impaired in A-T cells. Second, we show that the reduced protein turnover is causally linked to the elevated expression of the ubiquitin-like protein ISG15 in A-T cells. Third, we show that expression of the ISG15 is elevated in A-T cells derived from various A-T patients, as well as in brain tissues derived from the ATM knockout mice and A-T patients, suggesting that ATM negatively regulates the ISG15 pathway. Our current findings suggest for the first time that proteasome-mediated protein degradation is impaired in A-T cells due to elevated expression of the ISG15 conjugation pathway, which could contribute to progressive neurodegeneration in A-T patients.

  2. Solar photolysis versus TiO2-mediated solar photocatalysis: a kinetic study of the degradation of naproxen and diclofenac in various water matrices.

    Science.gov (United States)

    Kanakaraju, Devagi; Motti, Cherie A; Glass, Beverley D; Oelgemöller, Michael

    2016-09-01

    Given that drugs and their degradation products are likely to occur as concoctions in wastewater, the degradation of a mixture of two nonsteroidal anti-inflammatory drugs (NSAIDs), diclofenac (DCF) and naproxen (NPX), was investigated by solar photolysis and titanium dioxide (TiO2)-mediated solar photocatalysis using an immersion-well photoreactor. An equimolar ratio (1:1) of both NSAIDs in distilled water, drinking water, and river water was subjected to solar degradation. Solar photolysis of the DCF and NPX mixture was competitive particularly in drinking water and river water, as both drugs have the ability to undergo photolysis. However, the addition of TiO2 in the mixture significantly enhanced the degradation rate of both APIs compared to solar photolysis alone. Mineralization, as measured by chemical oxygen demand (COD), was incomplete under all conditions investigated. TiO2-mediated solar photocatalytic degradation of DCF and NPX mixtures produced 15 identifiable degradants corresponding to degradation of the individual NSAIDs, while two degradation products with much higher molecular weight than the parent NSAIDs were identified by liquid chromatography mass spectrometry (LC-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). This study showed that the solar light intensity and the water matrix appear to be the main factors influencing the overall performance of the solar photolysis and TiO2-mediated solar photocatalysis for degradation of DCF and NPX mixtures.

  3. PLAA Mutations Cause a Lethal Infantile Epileptic Encephalopathy by Disrupting Ubiquitin-Mediated Endolysosomal Degradation of Synaptic Proteins.

    Science.gov (United States)

    Hall, Emma A; Nahorski, Michael S; Murray, Lyndsay M; Shaheen, Ranad; Perkins, Emma; Dissanayake, Kosala N; Kristaryanto, Yosua; Jones, Ross A; Vogt, Julie; Rivagorda, Manon; Handley, Mark T; Mali, Girish R; Quidwai, Tooba; Soares, Dinesh C; Keighren, Margaret A; McKie, Lisa; Mort, Richard L; Gammoh, Noor; Garcia-Munoz, Amaya; Davey, Tracey; Vermeren, Matthieu; Walsh, Diana; Budd, Peter; Aligianis, Irene A; Faqeih, Eissa; Quigley, Alan J; Jackson, Ian J; Kulathu, Yogesh; Jackson, Mandy; Ribchester, Richard R; von Kriegsheim, Alex; Alkuraya, Fowzan S; Woods, C Geoffrey; Maher, Eamonn R; Mill, Pleasantine

    2017-05-04

    During neurotransmission, synaptic vesicles undergo multiple rounds of exo-endocytosis, involving recycling and/or degradation of synaptic proteins. While ubiquitin signaling at synapses is essential for neural function, it has been assumed that synaptic proteostasis requires the ubiquitin-proteasome system (UPS). We demonstrate here that turnover of synaptic membrane proteins via the endolysosomal pathway is essential for synaptic function. In both human and mouse, hypomorphic mutations in the ubiquitin adaptor protein PLAA cause an infantile-lethal neurodysfunction syndrome with seizures. Resulting from perturbed endolysosomal degradation, Plaa mutant neurons accumulate K63-polyubiquitylated proteins and synaptic membrane proteins, disrupting synaptic vesicle recycling and neurotransmission. Through characterization of this neurological intracellular trafficking disorder, we establish the importance of ubiquitin-mediated endolysosomal trafficking at the synapse. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  4. Excess free histone H3 localizes to centrosomes for proteasome-mediated degradation during mitosis in metazoans.

    Science.gov (United States)

    Wike, Candice L; Graves, Hillary K; Wason, Arpit; Hawkins, Reva; Gopalakrishnan, Jay; Schumacher, Jill; Tyler, Jessica K

    2016-08-17

    The cell tightly controls histone protein levels in order to achieve proper packaging of the genome into chromatin, while avoiding the deleterious consequences of excess free histones. Our accompanying study has shown that a histone modification that loosens the intrinsic structure of the nucleosome, phosphorylation of histone H3 on threonine 118 (H3 T118ph), exists on centromeres and chromosome arms during mitosis. Here, we show that H3 T118ph localizes to centrosomes in humans, flies, and worms during all stages of mitosis. H3 abundance at the centrosome increased upon proteasome inhibition, suggesting that excess free histone H3 localizes to centrosomes for degradation during mitosis. In agreement, we find ubiquitinated H3 specifically during mitosis and within purified centrosomes. These results suggest that targeting of histone H3 to the centrosome for proteasome-mediated degradation is a novel pathway for controlling histone supply, specifically during mitosis.

  5. Oncogenic human papillomavirus E6 proteins target the discs large tumour suppressor for proteasome-mediated degradation.

    Science.gov (United States)

    Gardiol, D; Kühne, C; Glaunsinger, B; Lee, S S; Javier, R; Banks, L

    1999-09-30

    Previous studies have shown that the oncogenic HPV E6 proteins form a complex with the human homologue of the Drosophila tumour suppressor protein, discs large (Dlg). This is mediated by the carboxy terminus of the E6 proteins and involves recognition of at least one PDZ domain of Dlg. This region of E6 is not conserved amongst E6 proteins from the low risk papillomavirus types and, hence, binding of HPV E6 proteins to Dlg correlates with the oncogenic potential of these viruses. We have performed studies to investigate the consequences of the interaction between E6 and Dlg. Mutational analysis of both the HPV18 E6 and Dlg proteins has further defined the regions of E6 and Dlg necessary for complex formation. Strikingly, co-expression of wild type HPV18 E6 with Dlg in vitro or in vivo results in a dramatic decrease in the amount of Dlg protein, whereas mutants of E6 which fail to complex with Dlg have minimal effect on Dlg protein levels. The oncogenic HPV16 E6 also decreased the Dlg levels, but this was not observed with the low risk HPV11 E6 protein. Moreover, a region within the first 544 amino acids of Dlg containing the three PDZ domains confers susceptibility to E6 mediated degradation. Finally, treatment of cells with a proteasome inhibitor overrides the capacity of E6 to degrade Dlg. These results demonstrate that Dlg is targeted by high risk HPV E6 proteins for proteasome mediated degradation.

  6. Mathematical modeling of diffusion-mediated release from bulk degrading matrices.

    Science.gov (United States)

    Tzafriri, A R

    2000-01-03

    The release of active agent from a bulk degrading matrix is formulated as a linear reaction diffusion problem. Two pools of active agent are assumed to contribute to the release: a pool of mobile active agent which readily diffuses out of the matrix upon immersion in an aqueous medium and a pool of immobilized active agent which can diffuse only after matrix degradation. Due to the linearity of our model, the dynamics of the two pools of active agent can be considered separately, for any mode of bulk degradation kinetics. For definiteness, we consider the case of first order degradation kinetics and a rectangular parallelepiped shaped matrix. A closed form solution is obtained for the release under perfect sink conditions which is then used to describe the in vitro release of the PerioChip¿trade mark omitted¿. This solution can explain the bi-phasic release profile characteristic of many hydrolytically degradable matrices. The case of mass transfer boundary conditions is solved numerically using the finite element method (FEM). This analysis indicates that under ordinary mixing conditions the diffusion layer is not rate limiting and the release is very well approximated by the analytical result for perfect sink conditions.

  7. Specific cell components of Bacteroides gingivalis mediate binding and degradation of human fibrinogen

    Energy Technology Data Exchange (ETDEWEB)

    Lantz, M.S.; Allen, R.D.; Vail, T.A.; Switalski, L.M.; Hook, M. (Univ. of Alabama at Birmingham (USA))

    1991-01-01

    Bacteroides (Porphyromonas) gingivalis, which has been implicated as an etiologic agent in human periodontal diseases, has been shown to bind and degrade human fibrinogen. B. gingivalis strains bind fibrinogen reversibly and with high affinity and bind to a specific region of the fibrinogen molecule that appears to be located between the D and E domains. The authors now report that human fibrinogen is bound and then degraded by specific B. gingivalis components that appear to be localized at the cell surface. Fibrinogen binding to bacterial cells occurred at 4, 22, and 37{degree}C. A functional fibrinogen-binding component (M{sub r}, 150 000) was identified when sodium dodecyl sulfate-solubilized bacteria were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to nitrocellulose membranes, and probed with {sup 125}I-fibrinogen. Fibrinogen degradation did not occur at 4{degree}C but did occur at 22 and 37{degree}C. When bacteria and iodinated fibrinogen were incubated at 37{degree}C, two major fibrinogen fragments (M{sub r}, 97 000 and 50 000) accumulated in incubation mixture supernatant fractions. Two major fibrinogen-degrading components (M{sub r}, 120 000 and 150 000) have been identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in substrate-containing gels. Fibrinogen degradation by the M{sub r}-120 000 and -150 000 proteases was enhanced by reducing agents, completely inhibited by N-{alpha}-p-tosyl-L-lysyl chloromethyl ketone, and partially inhibited by n-ethyl maleimide, suggesting that these enzymes are thiol-dependent proteases with trypsinlike substrate specificity. The fibrinogen-binding component could be separated from the fibrinogen-degrading components by selective solubilization of bacteria in sodium deoxycholate.

  8. Receptor-mediated endocytosis and degradative processing of growth hormone by rat adipocytes in primary culture.

    Science.gov (United States)

    Roupas, P; Herington, A C

    1987-05-01

    At 37 degrees C, cultured rat adipocytes bound [125I]human GH ([125I]hGH) rapidly, with binding being detectable within 1 min of incubation. The bound [125I]hGH was then internalized (within 10 min) and accumulated in the cell interior until a steady state was reached (by 60 min). At this time, where the rates of GH internalization, processing, and release are equivalent, 55% of total cell-associated [125I]hGH was intracellular. Internalization of [125I]hGH by acutely isolated (noncultured) adipocytes was preceded by a 20-min lag phase indicative of a temporary postbinding defect. The lag phase was not seen with cultured adipocytes. After preloading of [125I]hGH into the cell interior, cultured cells rapidly released [125I]hGH (t1/2 = 20-30 min) into the extracellular medium as both intact (25%) and degraded (75%) GH. The release of intact vs. degraded GH was distinguishable on the basis of kinetics and temperature dependence. In order to determine when internalized [125I]hGH entered a catabolic compartment, cultured adipocytes were incubated with [125I]hGH and the composition of intracellular GH was determined as a function of time. All [125I]hGH internalized during the first 20 min was intact. Between 20 and 30 min some of the internalized [125I]hGH entered a catabolic compartment and degradation products began accumulating within the adipocytes. Release of degraded [125I]hGH from cultured adipocytes began at 60 min. The processing of GH through the complete degradative pathway (binding, internalization, degradation, release) required a period of 1 h at 37 degrees C.

  9. Trypsin-mediated enzymatic degradation of type II collagen in the human vitreous

    NARCIS (Netherlands)

    van Deemter, Marielle; Kuijer, Roel; Pas, Hendri Harm; van der Worp, Roelofje Jacoba; Hooymans, Johanna Martina Maria; Los, Leonoor Inge

    2013-01-01

    Purpose: Aging of the vitreous body can result in sight-threatening pathology. One aspect of vitreous aging is liquefaction, which results from the vanishing of collagen fibrils. We investigated the possibility that trypsins are involved in vitreous type II collagen degradation. Methods:

  10. Wnt5a controls Notch1 signaling through CaMKII-mediated degradation of the SMRT corepressor protein.

    Science.gov (United States)

    Ann, Eun-Jung; Kim, Hwa-Young; Seo, Mi-Sun; Mo, Jung-Soon; Kim, Mi-Yeon; Yoon, Ji-Hye; Ahn, Ji-Seon; Park, Hee-Sae

    2012-10-26

    Serine-threonine Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is the key component in noncanonical Wnt5a signaling and has been shown to regulate its signaling. In this study, we found that CaMKII induced by Wnt5a remarkably reduced the protein stability of the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT), a co-repressor of Notch signaling, through proteasomal degradation. Wnt5a was found to enhance Notch1 intracellular domain (Notch1-IC) transcription activity, which could be inhibited by treatment with KN93, a CaMKII inhibitor. The kinase activity of CaMKII was essential for the activation of Notch signaling. We also determined that CaMKII could enhance the association between Notch1-IC and RBP-Jk. Furthermore, the physical association between RBP-Jk and SMRT was substantially suppressed by CaMKII. We demonstrated that CaMKII directly bound and phosphorylated SMRT at Ser-1407, thereby facilitating SMRT translocation from the nucleus to the cytoplasm and proteasome-dependent degradation. These results suggest that CaMKII down-regulated the protein stability of SMRT through proteasomal degradation.

  11. Wnt5a Controls Notch1 Signaling through CaMKII-mediated Degradation of the SMRT Corepressor Protein*

    Science.gov (United States)

    Ann, Eun-Jung; Kim, Hwa-Young; Seo, Mi-Sun; Mo, Jung-Soon; Kim, Mi-Yeon; Yoon, Ji-Hye; Ahn, Ji-Seon; Park, Hee-Sae

    2012-01-01

    Serine-threonine Ca2+/calmodulin-dependent protein kinase II (CaMKII) is the key component in noncanonical Wnt5a signaling and has been shown to regulate its signaling. In this study, we found that CaMKII induced by Wnt5a remarkably reduced the protein stability of the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT), a co-repressor of Notch signaling, through proteasomal degradation. Wnt5a was found to enhance Notch1 intracellular domain (Notch1-IC) transcription activity, which could be inhibited by treatment with KN93, a CaMKII inhibitor. The kinase activity of CaMKII was essential for the activation of Notch signaling. We also determined that CaMKII could enhance the association between Notch1-IC and RBP-Jk. Furthermore, the physical association between RBP-Jk and SMRT was substantially suppressed by CaMKII. We demonstrated that CaMKII directly bound and phosphorylated SMRT at Ser-1407, thereby facilitating SMRT translocation from the nucleus to the cytoplasm and proteasome-dependent degradation. These results suggest that CaMKII down-regulated the protein stability of SMRT through proteasomal degradation. PMID:22888005

  12. Binding of human IgG to single-walled carbon nanotubes accelerated myeloperoxidase-mediated degradation in activated neutrophils.

    Science.gov (United States)

    Ding, Yun; Tian, Rong; Yang, Zhen; Chen, Jianfa; Lu, Naihao

    2016-11-01

    The binding of protein to carboxylated single-walled carbon nanotubes (SWCNTs) was believed to play an important role in the biological effects of nanotubes. However, the effects of protein-SWCNTs interactions on the oxidative degradation of nanotubes were not stressed enough. Here, we investigated the binding of human immunoglobulin G (IgG) to SWCNTs, and found that the preferred binding site was located in the Fc region of IgG. The hydrophobic and electrostatic interactions might be the crucial factors in stabilizing the binding of SWCNTs with IgG. Through the competitive binding of IgG and myeloperoxidase (MPO) to nanotube surfaces, the binding of IgG could impair MPO-induced SWCNTs biodegradation in vitro. However, both SWCNTs and IgG-SWCNTs were significantly degraded in zymosan-stimulated neutrophils, and the degradation degree was more for IgG-SWCNTs. These results suggest that the binding of IgG may be an important determinant for MPO-mediated SWCNTs biodegradation in activated human inflammatory cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Tetrathiomolybdate mediates cisplatin-induced p38 signaling and EGFR degradation and enhances response to cisplatin therapy in gynecologic cancers

    Science.gov (United States)

    Kim, Kyu Kwang; Han, Alex; Yano, Naohiro; Ribeiro, Jennifer R.; Lokich, Elizabeth; Singh, Rakesh K.; Moore, Richard G.

    2015-01-01

    Cisplatin and its analogs are among the most widely used chemotherapeutic agents against various types of cancer. It is known that cisplatin can activate epidermal growth factor receptor (EGFR), which may provide a survival benefit in cancers. Tetrathiomolybdate (TM) is a potent anti-cancer and anti-angiogenic agent and has been investigated in a number of clinical trials for cancer. In this study, we explore the therapeutic potential of TM on cisplatin-mediated EGFR regulation. Our study shows that TM is not cytotoxic, but exerts an anti-proliferative effect in ECC-1 cells. However, TM treatment prior to cisplatin markedly improves cisplatin-induced cytotoxicity. TM suppressed cisplatin-induced activation of EGFR while potentiating activation of p38; the activation of p38 signaling appeared to promote cisplatin-induced EGFR degradation. These results are in contrast to what we saw when cells were co-treated with cisplatin plus an EGFR tyrosine kinase inhibitor, where receptor activation was inhibited but receptor degradation was also blocked. Our current study is in agreement with previous findings that TM may have a therapeutic benefit by inhibiting EGFR activation. We furthermore provide evidence that TM may provide an additional benefit by potentiating p38 activation following cisplatin treatment, which may in turn promote receptor degradation by cisplatin. PMID:26568478

  14. Degradation of Epidermal Growth Factor Receptor Mediates Dasatinib-Induced Apoptosis in Head and Neck Squamous Cell Carcinoma Cells

    Directory of Open Access Journals (Sweden)

    Yu-Chin Lin

    2012-06-01

    Full Text Available Epidermal growth factor receptor (EGFR is an important oncoprotein that promotes cell growth and proliferation. Dasatinib, a bcr-abl inhibitor, has been approved clinically for the treatment of chronic myeloid leukemia and demonstrated to be effective against solid tumors in vitro through Src inhibition. Here, we disclose that EGFR degradation mediated dasatinib-induced apoptosis in head and neck squamous cell carcinoma (HNSCC cells. HNSCC cells, including Ca9-22, FaDu, HSC3, SAS, SCC-25, and UMSCC1, were treated with dasatinib, and cell viability, apoptosis, and underlying signal transduction were evaluated. Dasatinib exhibited differential sensitivities against HNSCC cells. Growth inhibition and apoptosis were correlated with its inhibition on Akt, Erk, and Bcl-2, irrespective of Src inhibition. Accordingly, we found that down-regulation of EGFR was a determinant of dasatinib sensitivity. Lysosome inhibitor reversed dasatinib-induced EGFR down-regulation, and c-cbl activity was increased by dasatinib, indicating that dasatinib-induced EGFR down-regulation might be through c-cbl-mediated lysosome degradation. Increased EGFR activation by ligand administration rescued cells from dasatinib-induced apoptosis, whereas inhibition of EGFR enhanced its apoptotic effect. Estrogen receptor α (ERα was demonstrated to play a role in Bcl-2 expression, and dasatinib inhibited ERα at the pretranslational level. ERα was associated with EGFR in dasatinib-treated HNSCC cells. Furthermore, the xenograft model showed that dasatinib inhibited HSC3 tumor growth through in vivo down-regulation of EGFR and ERα. In conclusion, degradation of EGFR is a novel mechanism responsible for dasatinib-induced apoptosis in HNSCC cells.

  15. Copper-mediated oxidative degradation of catecholamines and oxidative damage of protein

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, P.R.; Harria, M.I.N.; Felix, J.M.; Hoffmann, M.E. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Biologia

    1997-12-31

    Full text. Degradative oxidation of catecholamines has been a matter of large interest in recent years due to the evidences associating their autoxidation with the etiology of neurotoxic and cardiotoxic processes. In this work we present data on the degradative oxidation of catecholamines of physiological importance: isoproterenol (IP), epinephrine (EP), norepinephrine (NEP), deoxyepinephrine (DEP) and dopamine (DA). The degradative oxidation of the catecholamines was followed by measurement of spectral changes and oxygen consumption by neutral aqueous solutions. The data show that Cu{sup 2+} strongly accelerated the rate of catecholamine oxidation, following the decreasing order; EP>DEP>IP>NEP>DA. The production of superoxide anion radical during catecholamine oxidation was very slow, even in the presence of Cu{sup 2+}. The ability of IP to induce damages on bovine serum albumin (BSA) was determined by measuring the formation of carbonyl-groups in the protein, detected by reduction with tritiated Na BH{sub 4}. The incubation of BSA with IP (50-500{mu}M), in the presence of 100{mu}M Cu{sup 2+} leaded to an increased and dose dependent {sup 3} H-incorporation by the oxidized protein. The production of oxidative damage by IP/Cu{sup 2+} was accompanied by marked BSA fragmentation, detected by SDS-polyacrylamide gel dependent (25-400{mu}M IP) des appearance of the original BSA band and appearance of smaller fragments spread in the gel, when incubation has been done in the presence of 100{mu}M Cu{sup 2+}. These results suggest that copper-catalysed oxidative degradation of proteins induced by catecholamines might be critically involved in the toxic action of these molecules

  16. The IDOL-UBE2D complex mediates sterol-dependent degradation of the LDL receptor.

    Science.gov (United States)

    Zhang, Li; Fairall, Louise; Goult, Benjamin T; Calkin, Anna C; Hong, Cynthia; Millard, Christopher J; Tontonoz, Peter; Schwabe, John W R

    2011-06-15

    We previously identified the E3 ubiquitin ligase IDOL as a sterol-dependent regulator of the LDL receptor (LDLR). The molecular pathway underlying IDOL action, however, remains to be determined. Here we report the identification and biochemical and structural characterization of an E2-E3 ubiquitin ligase complex for LDLR degradation. We identified the UBE2D family (UBE2D1-4) as E2 partners for IDOL that support both autoubiquitination and IDOL-dependent ubiquitination of the LDLR in a cell-free system. NMR chemical shift mapping and a 2.1 Å crystal structure of the IDOL RING domain-UBE2D1 complex revealed key interactions between the dimeric IDOL protein and the E2 enzyme. Analysis of the IDOL-UBE2D1 interface also defined the stereochemical basis for the selectivity of IDOL for UBE2Ds over other E2 ligases. Structure-based mutations that inhibit IDOL dimerization or IDOL-UBE2D interaction block IDOL-dependent LDLR ubiquitination and degradation. Furthermore, expression of a dominant-negative UBE2D enzyme inhibits the ability of IDOL to degrade the LDLR in cells. These results identify the IDOL-UBE2D complex as an important determinant of LDLR activity, and provide insight into molecular mechanisms underlying the regulation of cholesterol uptake.

  17. The IDOL–UBE2D complex mediates sterol-dependent degradation of the LDL receptor

    Science.gov (United States)

    Zhang, Li; Fairall, Louise; Goult, Benjamin T.; Calkin, Anna C.; Hong, Cynthia; Millard, Christopher J.; Tontonoz, Peter; Schwabe, John W.R.

    2011-01-01

    We previously identified the E3 ubiquitin ligase IDOL as a sterol-dependent regulator of the LDL receptor (LDLR). The molecular pathway underlying IDOL action, however, remains to be determined. Here we report the identification and biochemical and structural characterization of an E2–E3 ubiquitin ligase complex for LDLR degradation. We identified the UBE2D family (UBE2D1–4) as E2 partners for IDOL that support both autoubiquitination and IDOL-dependent ubiquitination of the LDLR in a cell-free system. NMR chemical shift mapping and a 2.1 Å crystal structure of the IDOL RING domain–UBE2D1 complex revealed key interactions between the dimeric IDOL protein and the E2 enzyme. Analysis of the IDOL–UBE2D1 interface also defined the stereochemical basis for the selectivity of IDOL for UBE2Ds over other E2 ligases. Structure-based mutations that inhibit IDOL dimerization or IDOL–UBE2D interaction block IDOL-dependent LDLR ubiquitination and degradation. Furthermore, expression of a dominant-negative UBE2D enzyme inhibits the ability of IDOL to degrade the LDLR in cells. These results identify the IDOL–UBE2D complex as an important determinant of LDLR activity, and provide insight into molecular mechanisms underlying the regulation of cholesterol uptake. PMID:21685362

  18. Phospholamban Is Downregulated by pVHL-Mediated Degradation through Oxidative Stress in Failing Heart

    Directory of Open Access Journals (Sweden)

    Shunichi Yokoe

    2017-10-01

    Full Text Available The E3 ubiquitin ligase, von Hippel–Lindau (VHL, regulates protein expression by polyubiquitination. Although the protein VHL (pVHL was reported to be involved in the heart function, the underlying mechanism is unclear. Here, we show that pVHL was upregulated in hearts from two types of genetically dilated cardiomyopathy (DCM mice models. In comparison with the wild-type mouse, both DCM mice models showed a significant reduction in the expression of phospholamban (PLN, a potent inhibitor of sarco(endoplasmic reticulum Ca2+-ATPase, and enhanced interaction between pVHL and PLN. To clarify whether pVHL is involved in PLN degradation in failing hearts, we used carbonylcyanide m-chlorophenylhydrazone (CCCP, a mitochondrial membrane potential (MMP-lowering reagent, to mimic the heart failure condition in PLN-expressing HEK293 cells and found that CCCP treatment resulted in PLN degradation and increased interaction between PLN and pVHL. However, these effects were reversed with the addition of N-acetyl-l-cysteine. Furthermore, the co-transfection of VHL and PLN in HEK293 cells decreased PLN expression under oxidative stress, whereas knockdown of VHL increased PLN expression both under normal and oxidative stress conditions. Together, we propose that oxidative stress upregulates pVHL expression to induce PLN degradation in failing hearts.

  19. Chaperone-Mediated Autophagy Targets IFNAR1 for Lysosomal Degradation in Free Fatty Acid Treated HCV Cell Culture.

    Directory of Open Access Journals (Sweden)

    Ramazan Kurt

    Full Text Available Hepatic steatosis is a risk factor for both liver disease progression and an impaired response to interferon alpha (IFN-α-based combination therapy in chronic hepatitis C virus (HCV infection. Previously, we reported that free fatty acid (FFA-treated HCV cell culture induces hepatocellular steatosis and impairs the expression of interferon alpha receptor-1 (IFNAR1, which is why the antiviral activity of IFN-α against HCV is impaired.To investigate the molecular mechanism by which IFNAR1 expression is impaired in HCV cell culture with or without free fatty acid-treatment.HCV-infected Huh 7.5 cells were cultured with or without a mixture of saturated (palmitate and unsaturated (oleate long-chain free fatty acids (FFA. Intracytoplasmic fat accumulation in HCV-infected culture was visualized by oil red staining. Clearance of HCV in FFA cell culture treated with type I IFN (IFN-α and Type III IFN (IFN-λ was determined by Renilla luciferase activity, and the expression of HCV core was determined by immunostaining. Activation of Jak-Stat signaling in the FFA-treated HCV culture by IFN-α alone and IFN-λ alone was examined by Western blot analysis and confocal microscopy. Lysosomal degradation of IFNAR1 by chaperone-mediated autophagy (CMA in the FFA-treated HCV cell culture model was investigated.FFA treatment induced dose-dependent hepatocellular steatosis and lipid droplet accumulation in HCV-infected Huh-7.5 cells. FFA treatment of infected culture increased HCV replication in a concentration-dependent manner. Intracellular lipid accumulation led to reduced Stat phosphorylation and nuclear translocation, causing an impaired IFN-α antiviral response and HCV clearance. Type III IFN (IFN-λ, which binds to a separate receptor, induces Stat phosphorylation, and nuclear translocation as well as antiviral clearance in FFA-treated HCV cell culture. We show here that the HCV-induced autophagy response is increased in FFA-treated cell culture

  20. Chaperone-Mediated Autophagy Targets IFNAR1 for Lysosomal Degradation in Free Fatty Acid Treated HCV Cell Culture.

    Science.gov (United States)

    Kurt, Ramazan; Chandra, Partha K; Aboulnasr, Fatma; Panigrahi, Rajesh; Ferraris, Pauline; Aydin, Yucel; Reiss, Krzysztof; Wu, Tong; Balart, Luis A; Dash, Srikanta

    2015-01-01

    Hepatic steatosis is a risk factor for both liver disease progression and an impaired response to interferon alpha (IFN-α)-based combination therapy in chronic hepatitis C virus (HCV) infection. Previously, we reported that free fatty acid (FFA)-treated HCV cell culture induces hepatocellular steatosis and impairs the expression of interferon alpha receptor-1 (IFNAR1), which is why the antiviral activity of IFN-α against HCV is impaired. To investigate the molecular mechanism by which IFNAR1 expression is impaired in HCV cell culture with or without free fatty acid-treatment. HCV-infected Huh 7.5 cells were cultured with or without a mixture of saturated (palmitate) and unsaturated (oleate) long-chain free fatty acids (FFA). Intracytoplasmic fat accumulation in HCV-infected culture was visualized by oil red staining. Clearance of HCV in FFA cell culture treated with type I IFN (IFN-α) and Type III IFN (IFN-λ) was determined by Renilla luciferase activity, and the expression of HCV core was determined by immunostaining. Activation of Jak-Stat signaling in the FFA-treated HCV culture by IFN-α alone and IFN-λ alone was examined by Western blot analysis and confocal microscopy. Lysosomal degradation of IFNAR1 by chaperone-mediated autophagy (CMA) in the FFA-treated HCV cell culture model was investigated. FFA treatment induced dose-dependent hepatocellular steatosis and lipid droplet accumulation in HCV-infected Huh-7.5 cells. FFA treatment of infected culture increased HCV replication in a concentration-dependent manner. Intracellular lipid accumulation led to reduced Stat phosphorylation and nuclear translocation, causing an impaired IFN-α antiviral response and HCV clearance. Type III IFN (IFN-λ), which binds to a separate receptor, induces Stat phosphorylation, and nuclear translocation as well as antiviral clearance in FFA-treated HCV cell culture. We show here that the HCV-induced autophagy response is increased in FFA-treated cell culture

  1. MCUR1-mediated mitochondrial calcium signaling facilitates cell survival of hepatocellular carcinoma via ROS-dependent P53 degradation.

    Science.gov (United States)

    Xing, Jinliang; Ren, Tingting; Wang, Jiaojiao; Zhang, Hui; Yuan, Peng; Zhu, Jianjun; Wu, Yousheng; Huang, Qichao; Guo, Xu; Zhang, Jing; Ji, Lele; Li, Jibin; Zhang, Hongxin; Yang, Hushan

    2017-09-22

    Levels of the Mitochondrial Calcium uniporter regulator 1 (MCUR1) increases during development of hepatocellular carcinoma (HCC). However, mechanistic understanding of how mitochondrial Ca2+ homeostasis is remodeled and its functional roles remains limited in cancers, especially in HCC. MCUR1 was frequently upregulated in HCC cells to enhance the Ca2+ uptake into mitochondria in a MCU-dependent manner, which significantly facilitated cell survival by promoting cell proliferation and inhibiting mitochondria-dependent intrinsic apoptosis, and thus contributed to poor prognosis of HCC patients. In vivo assay confirmed these results, indicating that forced expression of MCUR1 significantly increased the fraction of Ki67-positive cells and reduced the positive TUNEL staining in xenograft tumors, while decreased MCUR1 expression was associated with impaired growth capacity of HCC cells in nude mice. The survival advantage conferred by MCUR1-mediated mitochondrial Ca2+ uptake was majorly caused by elevated mitochondrial ROS production and subsequent AKT/MDM2- mediated P53 degradation, which regulated the expression of apoptosis-related molecules BAX and BCL-2 and cell cycle-related molecules P21, Cyclin D1 and Cyclin E. Treatment with mitochondrial Ca2+-buffering protein parvalbumin significantly suppressed the growth of HCC cells. Conclusions & Innovation: Our study provides evidence supporting a possible tumor-promoting role for MCUR1-mediated mitochondrial Ca2+ uptake and uncovers a mechanism that links remodeling of mitochondrial Ca2+ homeostasis to cancer cell survival, which suggests a potential novel therapeutic target for HCC.

  2. Development and validation of an enzyme-linked immunosorbent assay for the quantification of a specific MMP-9 mediated degradation fragment of type III collagen--A novel biomarker of atherosclerotic plaque remodeling

    DEFF Research Database (Denmark)

    Barascuk, Natasha; Vassiliadis, Efstathios; Larsen, Lise

    2011-01-01

    Degradation of collagen in the arterial wall by matrix metalloproteinases is the hallmark of atherosclerosis. We have developed an ELISA for the quantification of type III collagen degradation mediated by MMP-9 in urine....

  3. Different Stability and Proteasome-Mediated Degradation Rate of SMN Protein Isoforms.

    Directory of Open Access Journals (Sweden)

    Denise Locatelli

    Full Text Available The key pathogenic steps leading to spinal muscular atrophy (SMA, a genetic disease characterized by selective motor neuron degeneration, are not fully clarified. The full-length SMN protein (FL-SMN, the main protein product of the disease gene SMN1, plays an established role in the cytoplasm in snRNP biogenesis ultimately leading to mRNA splicing within the nucleus. It is also involved in the mRNA axonal transport. However, to what extent the impairment of these two SMN functions contributes to SMA pathogenesis remains unknown. A shorter SMN isoform, axonal-SMN or a-SMN, with more specific axonal localization, has been discovered, but whether it might act in concert with FL-SMN in SMA pathogenesis is not known. As a first step in defining common or divergent intracellular roles of FL-SMN vs a-SMN proteins, we here characterized the turn-over of both proteins and investigated which pathway contributed to a-SMN degradation. We performed real time western blot and confocal immunofluorescence analysis in easily controllable in vitro settings. We analyzed co-transfected NSC34 and HeLa cells and cell clones stably expressing both a-SMN and FL-SMN proteins after specific blocking of transcript or protein synthesis and inhibition of known intracellular degradation pathways. Our data indicated that whereas the stability of both FL-SMN and a-SMN transcripts was comparable, the a-SMN protein was characterized by a much shorter half-life than FL-SMN. In addition, as already demonstrated for FL-SMN, the Ub/proteasome pathway played a major role in the a-SMN protein degradation. We hypothesize that the faster degradation rate of a-SMN vs FL-SMN is related to the protection provided by the protein complex in which FL-SMN is assembled. The diverse a-SMN vs FL-SMN C-terminus may dictate different protein interactions and complex formation explaining the different localization and role in the neuronal compartment, and the lower expression and stability of a-SMN.

  4. Anti-diabetic activity of insulin-degrading enzyme inhibitors mediated by multiple hormones.

    Science.gov (United States)

    Maianti, Juan Pablo; McFedries, Amanda; Foda, Zachariah H; Kleiner, Ralph E; Du, Xiu Quan; Leissring, Malcolm A; Tang, Wei-Jen; Charron, Maureen J; Seeliger, Markus A; Saghatelian, Alan; Liu, David R

    2014-07-03

    Despite decades of speculation that inhibiting endogenous insulin degradation might treat type-2 diabetes, and the identification of IDE (insulin-degrading enzyme) as a diabetes susceptibility gene, the relationship between the activity of the zinc metalloprotein IDE and glucose homeostasis remains unclear. Although Ide(-/-) mice have elevated insulin levels, they exhibit impaired, rather than improved, glucose tolerance that may arise from compensatory insulin signalling dysfunction. IDE inhibitors that are active in vivo are therefore needed to elucidate IDE's physiological roles and to determine its potential to serve as a target for the treatment of diabetes. Here we report the discovery of a physiologically active IDE inhibitor identified from a DNA-templated macrocycle library. An X-ray structure of the macrocycle bound to IDE reveals that it engages a binding pocket away from the catalytic site, which explains its remarkable selectivity. Treatment of lean and obese mice with this inhibitor shows that IDE regulates the abundance and signalling of glucagon and amylin, in addition to that of insulin. Under physiological conditions that augment insulin and amylin levels, such as oral glucose administration, acute IDE inhibition leads to substantially improved glucose tolerance and slower gastric emptying. These findings demonstrate the feasibility of modulating IDE activity as a new therapeutic strategy to treat type-2 diabetes and expand our understanding of the roles of IDE in glucose and hormone regulation.

  5. CDK11{sup p58} represses vitamin D receptor-mediated transcriptional activation through promoting its ubiquitin-proteasome degradation

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Yayun; Hong, Yi; Zong, Hongliang; Wang, Yanlin; Zou, Weiying; Yang, Junwu; Kong, Xiangfei; Yun, Xiaojing [Gene Research Center, Shanghai Medical College and Institutes of Biomedical, Shanghai 200032 (China); Gu, Jianxin, E-mail: jxgu@shmu.edu.cn [Gene Research Center, Shanghai Medical College and Institutes of Biomedical, Shanghai 200032 (China)

    2009-08-28

    Vitamin D receptor (VDR) is a member of the nuclear receptor superfamily and regulates transcription of target genes. In this study, we identified CDK11{sup p58} as a novel protein involved in the regulation of VDR. CDK11{sup p58}, a member of the large family of p34cdc2-related kinases, is associated with cell cycle progression, tumorigenesis, and apoptotic signaling. Our study demonstrated that CDK11{sup p58} interacted with VDR and repressed VDR-dependent transcriptional activation. Furthermore, overexpression of CDK11{sup p58} decreased the stability of VDR through promoting its ubiquitin-proteasome-mediated degradation. Taken together, these results suggest that CDK11{sup p58} is involved in the negative regulation of VDR.

  6. PIAS1-mediated sumoylation promotes STUbL-dependent proteasomal degradation of the human telomeric protein TRF2.

    Science.gov (United States)

    Her, Joonyoung; Jeong, Yu Young; Chung, In Kwon

    2015-10-24

    The human telomeric protein TRF2 protects chromosome ends by facilitating their organization into the protective capping structure. Here we show that the stability of TRF2 is regulated via modification by the small ubiquitin-like modifiers (SUMO). TRF2 specifically interacts with and is sumoylated by PIAS1 in mammalian cells. The proteasome inhibitor stabilizes SUMO-conjugated TRF2 without affecting the level of unmodified TRF2, suggesting that SUMO conjugation is required for proteasomal degradation of TRF2. We also show that RNF4, a mammalian SUMO-targeted ubiquitin ligase, interacts with TRF2 in a SUMO-dependent manner and preferentially targets SUMO-conjugated TRF2 for ubiquitination. Collectively, our data demonstrate that the PIAS1-mediated sumoylation status of TRF2 serves as a molecular switch that controls the level of TRF2 at telomeres. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  7. Autophagy mediates the degradation of synaptic vesicles: A potential mechanism of synaptic plasticity injury induced by microwave exposure in rats.

    Science.gov (United States)

    Hao, Yanhui; Li, Wenchao; Wang, Hui; Zhang, Jing; Yu, Chao; Tan, Shengzhi; Wang, Haoyu; Xu, Xinping; Dong, Ji; Yao, Binwei; Zhou, Hongmei; Zhao, Li; Peng, Ruiyun

    2018-02-03

    To explore how autophagy changes and whether autophagy is involved in the pathophysiological process of synaptic plasticity injury caused by microwave radiation, we established a 30 mW/cm 2 microwave-exposure in vivo model, which caused reversible injuries in rat neurons. Microwave radiation induced cognitive impairment in rats and synaptic plasticity injury in rat hippocampal neurons. Autophagy in rat hippocampal neurons was activated following microwave exposure. Additionally, we observed that synaptic vesicles were encapsulated by autophagosomes, a phenomenon more evident in the microwave-exposed group. Colocation of autophagosomes and synaptic vesicles in rat hippocampal neurons increased following microwave exposure. microwave exposure led to the activation of autophagy in rat hippocampal neurons, and excessive activation of autophagy might damage synaptic plasticity by mediating synaptic vesicle degradation. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Reduction of azo dyes by redox mediators originating in the naphthalenesulfonic acid degradation pathway of Sphingomonas sp. strain BN6.

    Science.gov (United States)

    Keck, A; Klein, J; Kudlich, M; Stolz, A; Knackmuss, H J; Mattes, R

    1997-01-01

    The anaerobic reduction of azo dyes by Sphingomonas sp. strain BN6 was analyzed. Aerobic conversion of 2-naphthalenesulfonate (2NS) by cells of strain BN6 stimulated the subsequent anaerobic reduction of the sulfonated azo dye amaranth at least 10-fold. In contrast, in crude extracts, the azo reductase activity was not stimulated. A mutant of strain BN6 which was not able to metabolize 2NS showed increased amaranth reduction rates only when the cells were resuspended in the culture supernatant of 2NS-grown BN6 wild-type cells. The same increase could be observed with different bacterial strains. This suggested the presence of an extracellular factor which was formed during the degradation of 2NS by strain BN6. The addition of 1,2-dihydroxynaphthalene, the first intermediate of the degradation pathway of 2NS, or its decomposition products to cell suspensions of the mutant of strain BN6 (2NS-) increased the activity of amaranth reduction. The presence of bacterial cells was needed to maintain the reduction process. Thus, the decomposition products of 1,2-dihydroxynaphthalene are suggested to act as redox mediators which are able to anaerobically shuttle reduction equivalents from the cells to the extracellular azo dye. PMID:9293019

  9. TRAF4-SMURF2-mediated DAZAP2 degradation is critical for IL-25 signaling and allergic airway inflammation

    Science.gov (United States)

    Zepp, Jarod A.; Wu, Ling; Qian, Wen; Ouyang, Wenjun; Aronica, Mark; Erzurum, Serpil; Li, Xiaoxia

    2015-01-01

    Interleukin-25 (IL-25) promotes Type-2 immunity by inducing the expression of Th2-associated cytokines. While it is known that the IL-25R (IL-17RB) recruits the adaptor protein ACT1, the IL-25R signaling mechanism remains poorly understood. While screening for IL-25R components, we found that IL-25 responses were impaired in Traf4 –/– cells. Administering IL-25 to Traf4 –/– mice resulted in blunted airway eosinophilia and Th2 cytokine production. Notably, IL-25R recruitment of TRAF4 was required for the ACT1/IL-25R interaction. Mechanistically, TRAF4 recruited the E3-ligase SMURF2, to degrade the IL-25R-inhibitory molecule DAZAP2. Silencing Dazap2 increased ACT1/IL-25R interaction and IL-25 responsiveness. Moreover a tyrosine within the IL-25R elicited DAZAP2 interference. This study indicates that TRAF4-SMURF2-mediated DAZAP2 degradation is a crucial initiating event for the IL-25 response. PMID:25681341

  10. Measurement of matrix metalloproteinase 9-mediated Collagen type III degradation fragment as a marker of skin fibrosis

    Directory of Open Access Journals (Sweden)

    Larsen Lise

    2011-03-01

    Full Text Available Abstract Background The current study utilized a Bleomycin-induced model of skin fibrosis to investigate the neo-epitope CO3-610 (KNGETGPQGP, a fragment of collagen III released during matrix metalloproteinase-9 (MMP9 degradation of the protein, we have previously described as a novel biomarker for liver fibrosis. The aim was to investigate CO3-610 levels in another well characterised model of fibrosis, to better describe the biomarker in relation to additional fibrotic pathologies. Methods Skin fibrosis was induced by daily injections of Bleomycin to a total of 52 female C3 H mice, while control mice (n = 28 were treated with phosphate buffered saline (PBS, for 2, 4, 6 or 8 weeks. Skin fibrosis was evaluated using Visiopharm software on Sirius-red stained skin sections. Urine ELISA assays and creatinine corrections were performed to measure CO3-610 levels. Results CO3-610 levels were significantly higher in Bleomycin-treated vs. PBS-treated mice at each time point of termination. The mean increases were: 59.2%, P Conclusion Increased levels in mouse urine of the MMP-9 mediated collagen III degradation fragment CO3-610 were correlated with skin fibrosis progression, suggesting that CO3-610 may be a potential positive biomarker to study the pathogenesis of skin fibrosis in mice.

  11. iNOS-Derived Nitric Oxide Induces Integrin-Linked Kinase Endocytic Lysosome-Mediated Degradation in the Vascular Endothelium.

    Science.gov (United States)

    Reventun, Paula; Alique, Matilde; Cuadrado, Irene; Márquez, Susana; Toro, Rocío; Zaragoza, Carlos; Saura, Marta

    2017-07-01

    ILK (integrin-linked kinase) plays a key role in controlling vasomotor tone and is decreased in atherosclerosis. The objective of this study is to test whether nitric oxide (NO) regulates ILK in vascular remodeling. We found a striking correlation between increased levels of inducible nitric oxide and decreased ILK levels in human atherosclerosis and in a mouse model of vascular remodeling (carotid artery ligation) comparing with iNOS (inducible NO synthase) knockout mice. iNOS induction produced the same result in mouse aortic endothelial cells, and these effects were mimicked by an NO donor in a time-dependent manner. We found that NO decreased ILK protein stability by promoting the dissociation of the complex ILK/Hsp90 (heat shock protein 90)/eNOS (endothelial NO synthase), leading to eNOS uncoupling. NO also destabilized ILK signaling platform and lead to decreased levels of paxillin and α-parvin. ILK phosphorylation of its downstream target GSK3-β (glycogen synthase kinase 3 beta) was decreased by NO. Mechanistically, NO increased ILK ubiquitination mediated by the E3 ubiquitin ligase CHIP (C terminus of HSC70-interacting protein), but ILK ubiquitination was not followed by proteasome degradation. Alternatively, NO drove ILK to degradation through the endocytic-lysosomal pathway. ILK colocalized with the lysosome marker LAMP-1 (lysosomal-associated membrane protein 1) in endothelial cells, and inhibition of lysosome activity with chloroquine reversed the effect of NO. Likewise, ILK colocalized with the early endosome marker EEA1 (early endosome antigen 1). ILK endocytosis proceeded via dynamin because a specific inhibitor of dynamin (Dyngo 4a) was able to reverse ILK endocytosis and its lysosome degradation. Endocytosis regulates ILK signaling in vascular remodeling where there is an overload of inducible NO, and thus its inhibition may represent a novel target to fight atherosclerotic disease. © 2017 American Heart Association, Inc.

  12. Angiotensin II Facilitates Matrix Metalloproteinase-9-Mediated Myosin Light Chain Kinase Degradation in Pressure Overload-Induced Cardiac Hypertrophy

    Directory of Open Access Journals (Sweden)

    Shun Wang

    2017-12-01

    Full Text Available Background/Aims: Angiotensin II (Ang II has been shown to promote cardiac remodeling during the process of hypertrophy. Myosin light chain kinase (MLCK, a specific kinase for the phosphorylation of myosin light chain 2 (MLC2, plays an important role in regulating cardiac muscle contraction and hypertrophy. However, whether Ang II could facilitate cardiac hypertrophy by altering the expression of MLCK remains unclear. This study aimed to investigate this effect and the underlying mechanisms. Methods: Cardiac hypertrophy was induced via pressure overload in rats, which were then evaluated via histological and biochemical measurements and echocardiography. Angiotensin-converting enzyme inhibitor (ACEI was used to inhibit Ang II. Neonatal rat cardiomyocytes were stimulated with Ang II to induce hypertrophy and were treated with a matrix metalloproteinase 9 (MMP9 inhibitor. Myocyte hypertrophy was evaluated using immunofluorescence and qRT-PCR. Degradation of recombinant human MLCK by recombinant human MMP9 was tested using a cleavage assay. The expression levels of MLCK, MLC2, phospho-myosin light chain 2 (p-MLC2, myosin phosphatase 2 (MYPT2, and calmodulin (CaM were measured using western blotting. Results: ACEI improved cardiac function and remodeling and increased the levels of MLCK and p-MLC2 as well as reduced the expression of MMP9 in pressure overload-induced cardiac hypertrophy. Moreover, the MMP9 inhibitor alleviated myocyte hypertrophy and upregulated the levels of MLCK and p-MLC2 in Ang II-induced cardiomyocyte hypertrophy. Recombinant human MLCK was concentration- and time-dependently degraded by recombinant human MMP9 in vitro, and this process was prevented by the MMP9 inhibitor. Conclusion: Our results suggest that Ang II is involved in the degradation of MLCK in pressure overload-induced cardiac hypertrophy and that this process was mediated by MMP9.

  13. Calpain-2-mediated PTEN degradation contributes to BDNF-induced stimulation of dendritic protein synthesis

    Science.gov (United States)

    Briz, Victor; Hsu, Yu-Tien; Li, Yi; Lee, Erin; Bi, Xiaoning; Baudry, Michel

    2013-01-01

    Memory consolidation has been suggested to be protein synthesis-dependent. Recent data indicate that BDNF-induced dendritic protein synthesis is a key event in memory formation through activation of the mammalian target of rapamycin (mTOR) pathway. BDNF also activates calpain, a calcium-dependent cysteine protease, which has been shown to play a critical role in learning and memory. This study was therefore directed at testing the hypothesis that calpain activity is required for BDNF-stimulated local protein synthesis, and at identifying the underlying molecular mechanism. In rat hippocampal slices, cortical synaptoneurosomes, and cultured neurons, BDNF-induced mTOR pathway activation and protein translation were blocked by calpain inhibition. BDNF treatment rapidly reduced levels of hamartin and tuberin, negative regulators of mTOR, in a calpain-dependent manner. Treatment of brain homogenates with purified calpain-1 and calpain-2 truncated both proteins. BDNF treatment increased phosphorylation of both Akt and ERK, but only the effect on Akt was blocked by calpain inhibition. Levels of PTEN (phosphatase and tensin homolog deleted on chromosome ten), a phosphatase that inactivates Akt, were decreased following BDNF treatment, and calpain inhibition reversed this effect. Calpain-2 but not calpain-1 treatment of brain homogenates resulted in PTEN degradation. In cultured cortical neurons, knock-down of calpain-2 but not calpain-1 by siRNA completely suppressed the effect of BDNF on mTOR activation. Our results reveal a critical role for calpain-2 in BDNF-induced mTOR signaling and dendritic protein synthesis via PTEN, hamartin and tuberin degradation. This mechanism therefore provides a link between proteolysis and protein synthesis that might contribute to synaptic plasticity. PMID:23467348

  14. Sap transporter mediated import and subsequent degradation of antimicrobial peptides in Haemophilus.

    Directory of Open Access Journals (Sweden)

    Catherine L Shelton

    2011-11-01

    Full Text Available Antimicrobial peptides (AMPs contribute to host innate immune defense and are a critical component to control bacterial infection. Nontypeable Haemophilus influenzae (NTHI is a commensal inhabitant of the human nasopharyngeal mucosa, yet is commonly associated with opportunistic infections of the upper and lower respiratory tracts. An important aspect of NTHI virulence is the ability to avert bactericidal effects of host-derived antimicrobial peptides (AMPs. The Sap (sensitivity to antimicrobial peptides ABC transporter equips NTHI to resist AMPs, although the mechanism of this resistance has remained undefined. We previously determined that the periplasmic binding protein SapA bound AMPs and was required for NTHI virulence in vivo. We now demonstrate, by antibody-mediated neutralization of AMP in vivo, that SapA functions to directly counter AMP lethality during NTHI infection. We hypothesized that SapA would deliver AMPs to the Sap inner membrane complex for transport into the bacterial cytoplasm. We observed that AMPs localize to the bacterial cytoplasm of the parental NTHI strain and were susceptible to cytoplasmic peptidase activity. In striking contrast, AMPs accumulated in the periplasm of bacteria lacking a functional Sap permease complex. These data support a mechanism of Sap mediated import of AMPs, a novel strategy to reduce periplasmic and inner membrane accumulation of these host defense peptides.

  15. Human Neutrophil Elastase Mediates Fibrinolysis Shutdown Through Competitive Degradation of Plasminogen and Generation of Angiostatin.

    Science.gov (United States)

    Barrett, Christopher D; Moore, Hunter B; Banerjee, Anirban; Silliman, Christopher C; Moore, Ernest E; Yaffe, Michael B

    2017-08-23

    A subset of trauma patients undergo fibrinolysis shutdown rather than pathologic hyperfibrinolysis, contributing to organ failure. The molecular basis for fibrinolysis shutdown in trauma is incompletely understood. Elastase released from primed/activated human neutrophils (HNE) has historically been described as fibrin(ogen)olytic. However, HNE can also degrade plasminogen (PLG) to angiostatin (ANG), retaining the Kringle domains but not the proteolytic function, and could thereby compete for generation of active plasmin by tPA. We hypothesized that HNE can drive fibrinolysis shutdown rather than fibrinolysis. Turbidometry was performed using light scatter (λ=620nm) in a purified fibrinogen + PLG system and in healthy citrate plasma clotted with Ca/thrombin -/+tPA, -/+HNE, and -/+ANG to evaluate HNE effects on fibrinolysis, quantified by time to transition midpoint (Tm). ΔTm from control is reported as percent of control ±95%CI. Purified HNE coincubated with PLG or tPA was analysed by western blot to identify cleavage products. Exogenous HNE was mixed ex-vivo with healthy volunteer blood (n=7) and used in TEG -/+tPA to evaluate effects on fibrinolysis. HNE did not cause measurable fibrinolysis on fibrin clots, clotted plasma, or whole blood as assessed by turbidometry or TEG in the absence of tPA. Upon tPA treatment, all 3 methods of evaluating fibrinolysis showed delays and decreases in fibrinolysis due to HNE relative to control: fibrin clot turbidometry ΔTm =110.7% (CI 105.0%-116.5%), clotted citrate plasma (n=6 healthy volunteers) ΔTm =126.1% (CI 110.4%-141.8%), and whole blood native TEG (n=7 healthy volunteers) with ΔLY30=28% (p=0.043). Western blot analysis of HNE-PLG co-incubation confirmed that HNE generates angiostatin K1-3, and plasma turbidity assays treated with angiostatin K1-3 delayed fibrinolysis. HNE degrades PLG and generates angiostatin K1-3, which predominates over HNE cleavage of fibrin(ogen). These findings suggest that neutrophil

  16. Agrobacterium tumefaciens mediated transient expression of plant cell wall-degrading enzymes in detached sunflower leaves.

    Science.gov (United States)

    Jung, Sang-Kyu; Lindenmuth, Benjamin E; McDonald, Karen A; Hwang, Hwang; Bui, Mai Q Nguyen; Falk, Bryce W; Uratsu, Sandra L; Phu, My L; Dandekar, Abhaya M

    2014-01-01

    For biofuel applications, synthetic endoglucanase E1 and xylanase (Xyn10A) derived from Acidothermus cellulolyticus were transiently expressed in detached whole sunflower (Helianthus annuus L.) leaves using vacuum infiltration. Three different expression systems were tested, including the constitutive CaMV 35S-driven, CMVar (Cucumber mosaic virus advanced replicating), and TRBO (Tobacco mosaic virus RNA-Based Overexpression Vector) systems. For 6-day leaf incubations, codon-optimized E1 and xylanase driven by the CaMV 35S promoter were successfully expressed in sunflower leaves. The two viral expression vectors, CMVar and TRBO, were not successful although we found high expression in Nicotiana benthamiana leaves previously for other recombinant proteins. To further enhance transient expression, we demonstrated two novel methods: using the plant hormone methyl jasmonic acid in the agroinfiltration buffer and two-phase optimization of the leaf incubation temperature. When methyl jasmonic acid was added to Agrobacterium tumefaciens cell suspensions and infiltrated into plant leaves, the functional enzyme production increased 4.6-fold. Production also increased up to 4.2-fold when the leaf incubation temperature was elevated above the typical temperature, 20C, to 30C in the late incubation phase, presumably due to enhanced rate of protein synthesis in plant cells. Finally, we demonstrated co-expression of E1 and xylanase in detached sunflower leaves. To our knowledge, this is the first report of (co)expression of heterologous plant cell wall-degrading enzymes in sunflower.

  17. A toolkit for GFP-mediated tissue-specific protein degradation in C. elegans.

    Science.gov (United States)

    Wang, Shaohe; Tang, Ngang Heok; Lara-Gonzalez, Pablo; Zhao, Zhiling; Cheerambathur, Dhanya K; Prevo, Bram; Chisholm, Andrew D; Desai, Arshad; Oegema, Karen

    2017-07-15

    Proteins that are essential for embryo production, cell division and early embryonic events are frequently reused later in embryogenesis, during organismal development or in the adult. Examining protein function across these different biological contexts requires tissue-specific perturbation. Here, we describe a method that uses expression of a fusion between a GFP-targeting nanobody and a SOCS-box containing ubiquitin ligase adaptor to target GFP-tagged proteins for degradation. When combined with endogenous locus GFP tagging by CRISPR-Cas9 or with rescue of a null mutant with a GFP fusion, this approach enables routine and efficient tissue-specific protein ablation. We show that this approach works in multiple tissues - the epidermis, intestine, body wall muscle, ciliated sensory neurons and touch receptor neurons - where it recapitulates expected loss-of-function mutant phenotypes. The transgene toolkit and the strain set described here will complement existing approaches to enable routine analysis of the tissue-specific roles of C. elegans proteins. © 2017. Published by The Company of Biologists Ltd.

  18. Highly efficient visible light mediated azo dye degradation through barium titanate decorated reduced graphene oxide sheets

    Science.gov (United States)

    Rastogi, Monisha; Kushwaha, H. S.; Vaish, Rahul

    2016-03-01

    This study investigates BaTiO3 decorated reduced graphene oxide sheets as a potential visible light active catalyst for dye degradation (Rhodamine B). The composites were prepared through conventional hydrothermal synthesis technique using hydrazine as a reducing agent. A number of techniques have been employed to affirm the morphology, composition and photocatalytic properties of the composites; these include UV-visible spectrophotoscopy that assisted in quantifying the concentration difference of Rhodamine B. The phase homogeneity of the composites was examined through x-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) was employed to confirm the orientation of the BaTiO3 particles over the reduced graphene oxide sheets. Photoluminescence (PL) emission spectra assisted in determining the surface structure and excited state of the catalyst. Fourier transformed-infrared (FTIR) spectra investigated the vibrations and adsorption peak of the composites, thereby ascertaining the formation of reduced graphene oxide. In addition, diffuse reflectance spectroscopy (DRS) demonstrated an enhanced absorption in the visible region. The experimental investigations revealed that graphene oxide acted as charge collector and simultaneously facilitated surface adsorption and photo-sensitization. It could be deduced that BaTiO3-reduced graphene oxide composites are of significant interest the field of water purification through solar photocatalysis. [Figure not available: see fulltext.

  19. Hesperidin, A Popular Antioxidant Inhibits Melanogenesis via Erk1/2 Mediated MITF Degradation

    Directory of Open Access Journals (Sweden)

    Heun Joo Lee

    2015-08-01

    Full Text Available Regulation of melanogenesis has been the focus of treatment for hyperpigmentary skin disorders. Although hesperidin is one of the most well-known, naturally occurring flavonoids with antioxidant and anti-inflammatory effect, its anti-melanogenic effect is not known. The present study aims to determine the anti-melanogenic effect of hespiridin as well as its underlying molecular mechanisms. Melanin contents were measured in normal human melanocytes and B16F10 melanoma cells. Protein and mRNA levels of tyrosinase, microphthalmia-associated transcription factor (MITF, tyrosinase related protein-1 (TRP-1 and TRP-2 were determined. Melanogenesis-regulating signals were examined. In results, hesperidin strongly inhibited melanin synthesis and tyrosinase activity. Hesperidin decreased tyrosinase, TRP-1, and TRP-2 protein expression but increased phospho-extracellular signal-regulated kinase 1/2 (p-Erk1/2 expression. Specific inhibitor of Erk1/2 or proteasome inhibitor reversed the inhibition of melanogenesis induced by hesperidin. Taken together, hesperidin, a popular antioxidant, stimulated Erk1/2 phosphorylation which subsequently degraded MITF which resulted in suppression of melanogenic enzymes and melanin synthesis.

  20. Hesperidin, A Popular Antioxidant Inhibits Melanogenesis via Erk1/2 Mediated MITF Degradation.

    Science.gov (United States)

    Lee, Heun Joo; Lee, Woo Jin; Chang, Sung Eun; Lee, Ga-Young

    2015-08-07

    Regulation of melanogenesis has been the focus of treatment for hyperpigmentary skin disorders. Although hesperidin is one of the most well-known, naturally occurring flavonoids with antioxidant and anti-inflammatory effect, its anti-melanogenic effect is not known. The present study aims to determine the anti-melanogenic effect of hespiridin as well as its underlying molecular mechanisms. Melanin contents were measured in normal human melanocytes and B16F10 melanoma cells. Protein and mRNA levels of tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase related protein-1 (TRP-1) and TRP-2 were determined. Melanogenesis-regulating signals were examined. In results, hesperidin strongly inhibited melanin synthesis and tyrosinase activity. Hesperidin decreased tyrosinase, TRP-1, and TRP-2 protein expression but increased phospho-extracellular signal-regulated kinase 1/2 (p-Erk1/2) expression. Specific inhibitor of Erk1/2 or proteasome inhibitor reversed the inhibition of melanogenesis induced by hesperidin. Taken together, hesperidin, a popular antioxidant, stimulated Erk1/2 phosphorylation which subsequently degraded MITF which resulted in suppression of melanogenic enzymes and melanin synthesis.

  1. SUMOylation of GTF2IRD1 regulates protein partner interactions and ubiquitin-mediated degradation.

    Directory of Open Access Journals (Sweden)

    Jocelyn Widagdo

    Full Text Available GTF2IRD1 is one of the genes implicated in Williams-Beuren syndrome, a disease caused by haploinsufficiency of certain dosage-sensitive genes within a hemizygous microdeletion of chromosome 7. GTF2IRD1 is a prime candidate for some of the major features of the disease, presumably caused by abnormally reduced abundance of this putative transcriptional repressor protein. GTF2IRD1 has been shown to interact with the E3 SUMO ligase PIASxβ, but the significance of this relationship is largely unexplored. Here, we demonstrate that GTF2IRD1 can be SUMOylated by the SUMO E2 ligase UBC9 and the level of SUMOylation is enhanced by PIASxβ. A major SUMOylation site was mapped to lysine 495 within a conserved SUMO consensus motif. SUMOylation of GTF2IRD1 alters the affinity of the protein for binding partners that contain SUMO-interacting motifs, including a novel family member of the HDAC repressor complex, ZMYM5, and PIASxβ itself. In addition, we show that GTF2IRD1 is targeted for ubiquitination and proteasomal degradation. Cross regulation by SUMOylation modulates this process, thus potentially regulating the level of GTF2IRD1 protein in the cell. These findings, concerning post-translational control over the activity and stability of GTF2IRD1, together with previous work showing how GTF2IRD1 directly regulates its own transcription levels suggest an evolutionary requirement for fine control over GTF2IRD1 activity in the cell.

  2. Regulation of plasminogen activation, matrix metalloproteinases and urokinase-type plasminogen activator-mediated extracellular matrix degradation in human osteosarcoma cell line MG63 by interleukin-1 alpha

    NARCIS (Netherlands)

    Bart, A.C.W. de; Quax, P.H.A.; Löwik, C.W.G.M.; Verheijen, J.H.

    1995-01-01

    Plasmin-mediated extracellular proteolysis has been implicated in the degradation of bone in normal and pathological conditions. Normal and malignant osteoblasts can produce both tissue-type plasminogen activator (t- PA) and urokinase-type plasminogen activator (u-PA). We have used the osteosarcoma

  3. Feedback Inhibition of Starch Degradation in Arabidopsis Leaves Mediated by Trehalose 6-Phosphate1[W][OPEN

    Science.gov (United States)

    Martins, Marina Camara Mattos; Hejazi, Mahdi; Fettke, Joerg; Steup, Martin; Feil, Regina; Krause, Ursula; Arrivault, Stéphanie; Vosloh, Daniel; Figueroa, Carlos María; Ivakov, Alexander; Yadav, Umesh Prasad; Piques, Maria; Metzner, Daniela; Stitt, Mark; Lunn, John Edward

    2013-01-01

    Many plants accumulate substantial starch reserves in their leaves during the day and remobilize them at night to provide carbon and energy for maintenance and growth. In this paper, we explore the role of a sugar-signaling metabolite, trehalose-6-phosphate (Tre6P), in regulating the accumulation and turnover of transitory starch in Arabidopsis (Arabidopsis thaliana) leaves. Ethanol-induced overexpression of trehalose-phosphate synthase during the day increased Tre6P levels up to 11-fold. There was a transient increase in the rate of starch accumulation in the middle of the day, but this was not linked to reductive activation of ADP-glucose pyrophosphorylase. A 2- to 3-fold increase in Tre6P during the night led to significant inhibition of starch degradation. Maltose and maltotriose did not accumulate, suggesting that Tre6P affects an early step in the pathway of starch degradation in the chloroplasts. Starch granules isolated from induced plants had a higher orthophosphate content than granules from noninduced control plants, consistent either with disruption of the phosphorylation-dephosphorylation cycle that is essential for efficient starch breakdown or with inhibition of starch hydrolysis by β-amylase. Nonaqueous fractionation of leaves showed that Tre6P is predominantly located in the cytosol, with estimated in vivo Tre6P concentrations of 4 to 7 µm in the cytosol, 0.2 to 0.5 µm in the chloroplasts, and 0.05 µm in the vacuole. It is proposed that Tre6P is a component in a signaling pathway that mediates the feedback regulation of starch breakdown by sucrose, potentially linking starch turnover to demand for sucrose by growing sink organs at night. PMID:24043444

  4. CHIP stabilizes amyloid precursor protein via proteasomal degradation and p53-mediated trans-repression of β-secretase

    Science.gov (United States)

    Singh, Amir Kumar; Pati, Uttam

    2015-01-01

    In patient with Alzheimer’s disease (AD), deposition of amyloid-beta Aβ, a proteolytic cleavage of amyloid precursor protein (APP) by β-secretase/BACE1, forms senile plaque in the brain. BACE1 activation is caused due to oxidative stresses and dysfunction of ubiquitin–proteasome system (UPS), which is linked to p53 inactivation. As partial suppression of BACE1 attenuates Aβ generation and AD-related pathology, it might be an ideal target for AD treatment. We have shown that both in neurons and in HEK-APP cells, BACE1 is a new substrate of E3-ligase CHIP and an inverse relation exists between CHIP and BACE1 level. CHIP inhibits ectopic BACE1 level by promoting its ubiquitination and proteasomal degradation, thus reducing APP processing; it stabilizes APP in neurons, thus reducing Aβ. CHIPUbox domain physically interacts with BACE1; however, both U-box and TPR domain are essential for ubiquitination and degradation of BACE1. Further, BACE1 is a downstream target of p53 and overexpression of p53 decreases BACE1 level. In HEK-APP cells, CHIP is shown to negatively regulate BACE1 promoter through stabilization of p53’s DNA-binding conformation and its binding upon 5′ UTR element (+127 to +150). We have thus discovered that CHIP regulates p53-mediated trans-repression of BACE1 at both transcriptional and post-translational level. We propose that a CHIP–BACE1–p53 feedback loop might control APP stabilization, which could further be utilized for new therapeutic intervention in AD. PMID:25773675

  5. Dysregulation of protein degradation pathways may mediate the liver injury and phospholipidosis associated with a cationic amphiphilic antibiotic drug

    Energy Technology Data Exchange (ETDEWEB)

    Mosedale, Merrie [Hamner-University of North Carolina Institute for Drug Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Wu, Hong [Drug Safety Research and Development, Pfizer Global Research and Development, Groton, CT06340 (United States); Kurtz, C. Lisa [Hamner-University of North Carolina Institute for Drug Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Schmidt, Stephen P. [Drug Safety Research and Development, Pfizer Global Research and Development, Groton, CT06340 (United States); Adkins, Karissa, E-mail: Karissa.Adkins@pfizer.com [Drug Safety Research and Development, Pfizer Global Research and Development, Groton, CT06340 (United States); Harrill, Alison H. [Hamner-University of North Carolina Institute for Drug Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); University of Arkansas for Medical Sciences, Little Rock, AR72205 (United States)

    2014-10-01

    A large number of antibiotics are known to cause drug-induced liver injury in the clinic; however, interpreting clinical risk is not straightforward owing to a lack of predictivity of the toxicity by standard preclinical species and a poor understanding of the mechanisms of toxicity. An example is PF-04287881, a novel ketolide antibiotic that caused elevations in liver function tests in Phase I clinical studies. In this study, a mouse diversity panel (MDP), comprised of 34 genetically diverse, inbred mouse strains, was utilized to model the toxicity observed with PF-04287881 treatment and investigate potential mechanisms that may mediate the liver response. Significant elevations in serum alanine aminotransferase (ALT) levels in PF-04287881-treated animals relative to vehicle-treated controls were observed in the majority (88%) of strains tested following a seven day exposure. The average fold elevation in ALT varied by genetic background and correlated with microscopic findings of hepatocellular hypertrophy, hepatocellular single cell necrosis, and Kupffer cell vacuolation (confirmed as phospholipidosis) in the liver. Global liver mRNA expression was evaluated in a subset of four strains to identify transcript and pathway differences that distinguish susceptible mice from resistant mice in the context of PF-04287881 treatment. The protein ubiquitination pathway was highly enriched among genes associated with PF-04287881-induced hepatocellular necrosis. Expression changes associated with PF-04287881-induced phospholipidosis included genes involved in drug transport, phospholipid metabolism, and lysosomal function. The findings suggest that perturbations in genes involved in protein degradation leading to accumulation of oxidized proteins may mediate the liver injury induced by this drug. - Highlights: • Identified susceptible and resistant mouse strains to liver injury induced by a CAD • Liver injury characterized by single cell necrosis, and phospholipidosis

  6. Sunlight mediated diesel degradation under saline conditions using ionic silver coated sand via nanoreduction: use of impregnated form of thiourea modified chitosan membranes for ex situ application.

    Science.gov (United States)

    Das, Devlina; Das, Nilanjana

    2014-08-15

    The present research investigates the use of ionic silver coated sand dust (ISSD) for the sunlight mediated degradation of diesel under saline conditions. Sand dust was used as a template for reduction of silver ions by effective removal of chloride ions. Diesel degradation was estimated in terms of degradation (%), chloride removal, volume reduction and nanoparticle synthesis, respectively. The process was optimized using a 7-level Box-Behnken design. Among several factors, time (B), Tween 80 (C), ISSD dosage (D) and silver(I) concentration (F) were found to be most significant. Maximum diesel degradation 99.8% was obtained in a period of 14 h which was analyzed by gas chromatography. XPS analysis confirmed silver reduction as the underlying phenomena. TEM analysis and albeit first approximation method confirmed that enhanced degradation occurred due to physical contact between diesel components and ISSD. First order kinetic model exhibited the best fit. Light microscopy results showed the various stages in diesel degradation by a reduction in bubble size. Ex situ application was carried out using ISSD impregnated thiourea modified chitosan/PVA membranes by surface floatation technique for the remediation of diesel contaminated sea water. Complete diesel degradation was noted after 48 h of sunlight exposure. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Red Light-Mediated Degradation of CONSTANS by the E3 Ubiquitin Ligase HOS1 Regulates Photoperiodic Flowering in Arabidopsis.

    Science.gov (United States)

    Lazaro, Ana; Mouriz, Alfonso; Piñeiro, Manuel; Jarillo, José A

    2015-09-01

    The regulation of CONSTANS (CO) gene expression is crucial to accurately measure changes in daylength, which influences flowering time in Arabidopsis thaliana. CO expression is under both transcriptional and posttranslational control mechanisms. We previously showed that the E3 ubiquitin ligase HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES1 (HOS1) physically interacts with CO in Arabidopsis. This interaction is required to precisely modulate the timing of CO accumulation and, consequently, to maintain low levels of FLOWERING LOCUS T expression during the first part of the day. The data presented here demonstrate that HOS1 is involved in the red light-mediated degradation of CO that takes place in the early stages of the daylight period. Our results show that phytochrome B (phyB) is able to regulate flowering time, acting in the phloem companion cells, as previously described for CO and HOS1. Moreover, we reveal that phyB physically interacts with HOS1 and CO, indicating that the three proteins may be present in a complex in planta that is required to coordinate a correct photoperiodic response in Arabidopsis. © 2015 American Society of Plant Biologists. All rights reserved.

  8. BCL11B is frequently downregulated in HTLV-1-infected T-cells through Tax-mediated proteasomal degradation.

    Science.gov (United States)

    Permatasari, Happy Kurnia; Nakahata, Shingo; Ichikawa, Tomonaga; Morishita, Kazuhiro

    2017-08-26

    Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia-lymphoma (ATLL). The HTLV-1-encoded protein Tax plays important roles in the proliferation of HTLV-1-infected T-cells by affecting cellular proteins. In this study, we showed that Tax transcriptionally and post-transcriptionally downregulates the expression of the tumor suppressor gene B-cell leukemia/lymphoma 11B (BCL11B), which encodes a lymphoid-related transcription factor. BCL11B expression was downregulated in HTLV-1-infected T-cell lines at the mRNA and protein levels, and forced expression of BCL11B suppressed the proliferation of these cells. The proteasomal inhibitor MG132 increased BCL11B expression in HTLV-1-infected cell lines, and colocalization of Tax with BCL11B was detected in the cytoplasm of HTLV-1-infected T-cells following MG132 treatment. shRNA knock-down of Tax expression also increased the expression of BCL11B in HTLV-1-infected cells. Moreover, we found that Tax physically binds to BCL11B protein and induces the polyubiquitination of BCL11B and proteasome-dependent degradation of BCL11B. Thus, inactivation of BCL11B by Tax protein may play an important role in the Tax-mediated leukemogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Degradation of antibiotic norfloxacin in aqueous solution by visible-light-mediated C-TiO2 photocatalysis.

    Science.gov (United States)

    Chen, Meijuan; Chu, W

    2012-06-15

    A visible-light-mediated C-TiO(2) photocatalytic process (Vis/C-TiO(2)) was employed to degrade antibiotic norfloxacin. The influences of catalyst dosage, initial probe compound concentration and solution pH levels on the decay performance and reaction kinetics were investigated and optimized. Based on the experimental results, an equation was established to predict the observed rate constant under neutral pH. In addition, the decay rate was accelerated under weak alkali in the presence of moderate OH(-) anions. Hydroxyl radical was confirmed to play a major role in the Vis/TiO(2) process, where in the presence of OH quencher and electron acceptor, retardation and improvement were found respectively. Furthermore, an original schematic diagram describing the surface property of C-TiO(2) was built and further verified, in which, NH(4)(+) cations normally served as hole scavengers showed a negligible effect because the adsorbed OH(-) formed a barrier for NH(4)(+) ions to approach the holes, and the F(-) anions presented a significant suppression on norfloxacin decay due to the formation of hydrogen bond (OH⋯F) around the C-TiO(2) surface. Besides, the recycling and sedimentation tests justified that the Vis/C-TiO(2) process is a cost-effective and feasible way for wastewater treatment. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Caspase-10 Negatively Regulates Caspase-8-Mediated Cell Death, Switching the Response to CD95L in Favor of NF-κB Activation and Cell Survival

    Directory of Open Access Journals (Sweden)

    Sebastian Horn

    2017-04-01

    Full Text Available Formation of the death-inducing signaling complex (DISC initiates extrinsic apoptosis. Caspase-8 and its regulator cFLIP control death signaling by binding to death-receptor-bound FADD. By elucidating the function of the caspase-8 homolog, caspase-10, we discover that caspase-10 negatively regulates caspase-8-mediated cell death. Significantly, we reveal that caspase-10 reduces DISC association and activation of caspase-8. Furthermore, we extend our co-operative/hierarchical binding model of caspase-8/cFLIP and show that caspase-10 does not compete with caspase-8 for binding to FADD. Utilizing caspase-8-knockout cells, we demonstrate that caspase-8 is required upstream of both cFLIP and caspase-10 and that DISC formation critically depends on the scaffold function of caspase-8. We establish that caspase-10 rewires DISC signaling to NF-κB activation/cell survival and demonstrate that the catalytic activity of caspase-10, and caspase-8, is redundant in gene induction. Thus, our data are consistent with a model in which both caspase-10 and cFLIP coordinately regulate CD95L-mediated signaling for death or survival.

  11. Degradation of antibiotic norfloxacin in aqueous solution by visible-light-mediated C-TiO{sub 2} photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Meijuan [Department of Civil and Structural Engineering, Research Centre for Environmental Technology and Management, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Chu, W., E-mail: cechu@polyu.edu.hk [Department of Civil and Structural Engineering, Research Centre for Environmental Technology and Management, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Vis/C-TiO{sub 2} process was employed to degrade norfloxacin for the first time. Black-Right-Pointing-Pointer An original schematic diagram for deciphering the catalyst surface property was proposed. Black-Right-Pointing-Pointer OH{center_dot} radicals are verified to play a major role in the norfloxacin decomposition. Black-Right-Pointing-Pointer Hole scavenger of ammonium did not show negative influence. Black-Right-Pointing-Pointer Fluoride presented a unique restriction in the norfloxacin decay. - Abstract: A visible-light-mediated C-TiO{sub 2} photocatalytic process (Vis/C-TiO{sub 2}) was employed to degrade antibiotic norfloxacin. The influences of catalyst dosage, initial probe compound concentration and solution pH levels on the decay performance and reaction kinetics were investigated and optimized. Based on the experimental results, an equation was established to predict the observed rate constant under neutral pH. In addition, the decay rate was accelerated under weak alkali in the presence of moderate OH{sup -} anions. Hydroxyl radical was confirmed to play a major role in the Vis/TiO{sub 2} process, where in the presence of {center_dot}OH quencher and electron acceptor, retardation and improvement were found respectively. Furthermore, an original schematic diagram describing the surface property of C-TiO{sub 2} was built and further verified, in which, NH{sub 4}{sup +} cations normally served as hole scavengers showed a negligible effect because the adsorbed OH{sup -} formed a barrier for NH{sub 4}{sup +} ions to approach the holes, and the F{sup -} anions presented a significant suppression on norfloxacin decay due to the formation of hydrogen bond (O-H Midline-Horizontal-Ellipsis F) around the C-TiO{sub 2} surface. Besides, the recycling and sedimentation tests justified that the Vis/C-TiO{sub 2} process is a cost-effective and feasible way for wastewater treatment.

  12. Maximizing the concentrations of wheat grain fructans in bread by exploring strategies to prevent their yeast ( Saccharomyces cerevisiae )-mediated degradation.

    Science.gov (United States)

    Verspreet, Joran; Hemdane, Sami; Dornez, Emmie; Cuyvers, Sven; Delcour, Jan A; Courtin, Christophe M

    2013-02-13

    The degradation of endogenous wheat grain fructans, oligosaccharides with possible health-promoting potential, during wheat whole meal bread making was investigated, and several strategies to prevent their degradation were evaluated. Up to 78.4 ± 5.2% of the fructans initially present in wheat whole meal were degraded during bread making by the action of yeast ( Saccharomyces cerevisiae ) invertase. The addition of sucrose to dough delayed fructan degradation but had no effect on final fructan concentrations. However, yeast growth conditions and yeast genotype did have a clear impact. A 3-fold reduction of fructan degradation could be achieved when the commercial bread yeast strain was replaced by yeast strains with lower sucrose degradation activity. Finally, fructan degradation during bread making could be prevented completely by the use of a yeast strain lacking invertase. These results show that the nutritional profile of bread can be enhanced through appropriate yeast technology.

  13. SEL-10 is an inhibitor of notch signaling that targets notch for ubiquitin-mediated protein degradation.

    Science.gov (United States)

    Wu, G; Lyapina, S; Das, I; Li, J; Gurney, M; Pauley, A; Chui, I; Deshaies, R J; Kitajewski, J

    2001-11-01

    Notch receptors and their ligands play important roles in both normal animal development and pathogenesis. We show here that the F-box/WD40 repeat protein SEL-10 negatively regulates Notch receptor activity by targeting the intracellular domain of Notch receptors for ubiquitin-mediated protein degradation. Blocking of endogenous SEL-10 activity was done by expression of a dominant-negative form containing only the WD40 repeats. In the case of Notch1, this block leads to an increase in Notch signaling stimulated by either an activated form of the Notch1 receptor or Jagged1-induced signaling through Notch1. Expression of dominant-negative SEL-10 leads to stabilization of the intracellular domain of Notch1. The Notch4 intracellular domain bound to SEL-10, but its activity was not increased as a result of dominant-negative SEL-10 expression. SEL-10 bound Notch4 via the WD40 repeats and bound preferentially to a phosphorylated form of Notch4 in cells. We mapped the region of Notch4 essential for SEL-10 binding to the C-terminal region downstream of the ankyrin repeats. When this C-terminal fragment of Notch4 was expressed in cells, it was highly labile but could be stabilized by the expression of dominant-negative SEL-10. Ubiquitination of Notch1 and Notch4 intracellular domains in vitro was dependent on SEL-10. Although SEL-10 interacts with the intracellular domains of both Notch1 and Notch4, these proteins respond differently to interference with SEL-10 function. Thus, SEL-10 functions to promote the ubiquitination of Notch proteins; however, the fates of these proteins may differ.

  14. Mediatization

    DEFF Research Database (Denmark)

    Hjarvard, Stig

    2017-01-01

    Mediatization research shares media effects studies' ambition of answering the difficult questions with regard to whether and how media matter and influence contemporary culture and society. The two approaches nevertheless differ fundamentally in that mediatization research seeks answers...... to these general questions by distinguishing between two concepts: mediation and mediatization. The media effects tradition generally considers the effects of the media to be a result of individuals being exposed to media content, i.e. effects are seen as an outcome of mediated communication. Mediatization....... From the perspective of mediatization research, the most important effect of the media stems from their embeddedness in culture and society....

  15. CaMKII-mediated Beclin 1 phosphorylation regulates autophagy that promotes degradation of Id and neuroblastoma cell differentiation.

    Science.gov (United States)

    Li, Xuan; Wu, Xiao-Qi; Deng, Rong; Li, Dan-Dan; Tang, Jun; Chen, Wen-Dan; Chen, Jing-Hong; Ji, Jiao; Jiao, Lin; Jiang, Shan; Yang, Fen; Feng, Gong-Kan; Senthilkumar, Ravichandran; Yue, Fei; Zhang, Hai-Liang; Wu, Rui-Yan; Yu, Yan; Xu, Xue-Lian; Mai, Jia; Li, Zhi-Ling; Peng, Xiao-Dan; Huang, Yun; Huang, Xiang; Ma, Ning-Fang; Tao, Qian; Zeng, Yi-Xin; Zhu, Xiao-Feng

    2017-10-27

    Autophagy is a degradative pathway that delivers cellular components to the lysosome for degradation. The role of autophagy in cell differentiation is poorly understood. Here we show that CaMKII can directly phosphorylate Beclin 1 at Ser90 to promote K63-linked ubiquitination of Beclin 1 and activation of autophagy. Meanwhile, CaMKII can also promote K63-linked ubiquitination of inhibitor of differentiation 1/2 (Id-1/2) by catalyzing phosphorylation of Id proteins and recruiting TRAF-6. Ubiquitinated Id-1/Id-2 can then bind to p62 and be transported to autolysosomes for degradation. Id degradation promotes the differentiation of neuroblastoma cells and reduces the proportion of stem-like cells. Our study proposes a mechanism by which autophagic degradation of Id proteins can regulate cell differentiation. This suggests that targeting of CaMKII and the regulation of autophagic degradation of Id may be an effective therapeutic strategy to induce cell differentiation in neuroblastoma.

  16. Casein kinase 1α mediates degradation of receptors for type I and type II interferons caused by hemagglutinin of influenza A virus.

    Science.gov (United States)

    Xia, Chuan; Wolf, Jennifer J; Vijayan, Madhuvanthi; Studstill, Caleb J; Ma, Wenjun; Hahm, Bumsuk

    2018-01-17

    Although influenza A virus (IAV) evades cellular defense systems to effectively propagate in the host, the viral immune evasive mechanisms are incompletely understood. Our recent data showed that hemagglutinin (HA) of IAV induces degradation of type I IFN receptor 1 (IFNAR1). Here, we demonstrate that IAV HA induces degradation of type II IFN (IFN-γ) receptor 1 (IFNGR1) as well as IFNAR1 via casein kinase 1α (CK1α), resulting in the impairment of cellular responsiveness to both type I and II IFNs. IAV infection or transient HA expression induced degradation of both IFNGR1 and IFNAR1, whereas HA gene-deficient IAV failed to downregulate the receptors. IAV HA caused the phosphorylation and ubiquitination of IFNGR1, leading to the lysosome-dependent degradation of IFNGR1. Influenza viral HA strongly decreased cellular sensitivity to type II IFNs, as it suppressed the activation of STAT1 and the induction of IFN-γ-stimulated genes in response to exogenously supplied recombinant IFN-γ. Importantly, CK1α, but not p38 MAP kinase or protein kinase D2, was proven to be critical for HA-induced degradation of both IFNGR1 and IFNAR1. Pharmacologic inhibition of CK1α or siRNA-based knockdown of CK1α repressed the degradation process of both IFNGR1 and IFNAR1 triggered by IAV infection. Further, CK1α was shown to be pivotal for proficient replication of IAV. Collectively, the results suggest that IAV HA induces degradation of IFN receptors via CK1α, creating a condition favorable for viral propagation. Therefore, the study uncovers a new immune evasive pathway of influenza virus.IMPORTANCE Influenza A virus (IAV) remains a grave threat to humans by causing seasonal and pandemic influenza. Upon infection, the innate and adaptive immunity such as the interferon (IFN) response is induced to protect hosts against IAV infection. However, IAV seems to be equipped with tactics to evade the IFN-mediated antiviral responses. Yet, the detailed mechanisms need to be elucidated

  17. Release of GTP Exchange Factor Mediated Down-Regulation of Abscisic Acid Signal Transduction through ABA-Induced Rapid Degradation of RopGEFs

    Science.gov (United States)

    Waadt, Rainer; Schroeder, Julian I.

    2016-01-01

    The phytohormone abscisic acid (ABA) is critical to plant development and stress responses. Abiotic stress triggers an ABA signal transduction cascade, which is comprised of the core components PYL/RCAR ABA receptors, PP2C-type protein phosphatases, and protein kinases. Small GTPases of the ROP/RAC family act as negative regulators of ABA signal transduction. However, the mechanisms by which ABA controls the behavior of ROP/RACs have remained unclear. Here, we show that an Arabidopsis guanine nucleotide exchange factor protein RopGEF1 is rapidly sequestered to intracellular particles in response to ABA. GFP-RopGEF1 is sequestered via the endosome-prevacuolar compartment pathway and is degraded. RopGEF1 directly interacts with several clade A PP2C protein phosphatases, including ABI1. Interestingly, RopGEF1 undergoes constitutive degradation in pp2c quadruple abi1/abi2/hab1/pp2ca mutant plants, revealing that active PP2C protein phosphatases protect and stabilize RopGEF1 from ABA-mediated degradation. Interestingly, ABA-mediated degradation of RopGEF1 also plays an important role in ABA-mediated inhibition of lateral root growth. The presented findings point to a PP2C-RopGEF-ROP/RAC control loop model that is proposed to aid in shutting off ABA signal transduction, to counteract leaky ABA signal transduction caused by “monomeric” PYL/RCAR ABA receptors in the absence of stress, and facilitate signaling in response to ABA. PMID:27192441

  18. Noncanonical role ofArabidopsisCOP1/SPA complex in repressing BIN2-mediated PIF3 phosphorylation and degradation in darkness.

    Science.gov (United States)

    Ling, Jun-Jie; Li, Jian; Zhu, Danmeng; Deng, Xing Wang

    2017-03-28

    The E3 ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) has been known to mediate key signaling factors for degradation via the ubiquitin/26S proteasome pathway in both plants and animals. Here, we report a noncanonical function of Arabidopsis COP1, the central repressor of photomorphogenesis, in the form of a COP1/ SUPPRESSOR of phyA-105 (SPA) complex. We show that the COP1/SPA complex associates with and stabilizes PHYTOCHROME INTERACTING FACTOR 3 (PIF3) to repress photomorphogenesis in the dark. We identify the GSK3-like kinase BRASSINOSTEROID-INSENSITIVE 2 (BIN2) as a kinase of PIF3, which induces PIF3 degradation via 26S proteasome during skotomorphogenesis. Mutations on two typical BIN2 phosphorylation motifs of PIF3 lead to a strong stabilization of the protein in the dark. We further show that the COP1/SPA complex promotes PIF3 stability by repressing BIN2 activity. Intriguingly, without affecting BIN2 expression, the COP1/SPA complex modulates BIN2 activity through interfering with BIN2-PIF3 interaction, thereby inhibiting BIN2-mediated PIF3 phosphorylation and degradation. Taken together, our results suggest another paradigm for COP1/SPA complex action in the precise control of skotomorphogenesis.

  19. Inhibition of FOXO3 tumor suppressor function by betaTrCP1 through ubiquitin-mediated degradation in a tumor mouse model.

    Directory of Open Access Journals (Sweden)

    Wen-Bin Tsai

    2010-07-01

    Full Text Available The ubiquitin-proteasome system is the primary proteolysis machine for controlling protein stability of the majority of regulatory proteins including those that are critical for cancer development. The forkhead box transcription factor FOXO3 plays a key role in regulating tumor suppression; however, the control of FOXO3 protein stability remains to be established. It is crucial to elucidate the molecular mechanisms underlying the ubiquitin-mediated degradation of FOXO3 tumor suppressor.Here we show that betaTrCP1 oncogenic ubiquitin E3-ligase interacts with FOXO3 and induces its ubiquitin-dependent degradation in an IkappaB kinase-beta phosphorylation dependent manner. Silencing betaTrCP1 augments FOXO3 protein level, resulting in promoting cellular apoptosis in cancer cells. In animal models, increasing FOXO3 protein level by silencing betaTrCP1 suppresses tumorigenesis, whereas decreasing FOXO3 by over-expressing betaTrCP1 promotes tumorigenesis and tumor growth in vivo.This is a unique demonstration that the betaTrCP1-mediated FOXO3 degradation plays a crucial role in tumorigenesis. These findings significantly contribute to understanding of the control of FOXO3 stability in cancer cells and may provide opportunities for developing innovative anticancer therapeutic modalities.

  20. New role for an old rule: N-end rule-mediated degradation of ethylene responsive factor proteins governs low oxygen response in plants(F).

    Science.gov (United States)

    Licausi, Francesco; Pucciariello, Chiara; Perata, Pierdomenico

    2013-01-01

    The N-end rule pathway regulates protein degradation, which depends on exposed N-terminal sequences in prokaryotes and eukaryotes. In plants, conserved and specific enzymes stimulate selective proteolysis. Although a number of developmental and growth phenotypes have been reported for mutants in the N-end rule, its function has remained unrelated to specific physiological pathways. The first report of the direct involvement of the N-end rule in stress responses focused on hypoxic signaling and how the oxygen-dependent oxidation of cystein promotes the N-end rule-mediated degradation of ethylene responsive factor (ERF)-VII proteins, the master regulators of anaerobic responses. It has been suggested that plants have evolved specific mechanisms to tune ERF-VII availability in the nucleus. In this review, we speculate that ERF-VII proteins are reversibly protected from degradation via membrane sequestration. The oxidative response in plants subjected to anoxic conditions suggests that reactive oxygen and nitrogen species (reactive oxygen species and reactive nitrogen species) may interact or interfere with the N-end rule pathway-mediated response to hypoxia. © 2013 Institute of Botany, Chinese Academy of Sciences.

  1. Ubiquitin ligase RNF123 mediates degradation of heterochromatin protein 1α and β in lamin A/C knock-down cells.

    Directory of Open Access Journals (Sweden)

    Pankaj Chaturvedi

    Full Text Available The nuclear lamina is a key determinant of nuclear architecture, integrity and functionality in metazoan nuclei. Mutations in the human lamin A gene lead to highly debilitating genetic diseases termed as laminopathies. Expression of lamin A mutations or reduction in levels of endogenous A-type lamins leads to nuclear defects such as abnormal nuclear morphology and disorganization of heterochromatin. This is accompanied by increased proteasomal degradation of certain nuclear proteins such as emerin, nesprin-1α, retinoblastoma protein and heterochromatin protein 1 (HP1. However, the pathways of proteasomal degradation have not been well characterized.To investigate the mechanisms underlying the degradation of HP1 proteins upon lamin misexpression, we analyzed the effects of shRNA-mediated knock-down of lamins A and C in HeLa cells. Cells with reduced levels of expression of lamins A and C exhibited proteasomal degradation of HP1α and HP1β but not HP1γ. Since specific ubiquitin ligases are upregulated in lamin A/C knock-down cells, further studies were carried out with one of these ligases, RNF123, which has a putative HP1-binding motif. Ectopic expression of GFP-tagged RNF123 directly resulted in degradation of HP1α and HP1β. Mutational analysis showed that the canonical HP1-binding pentapeptide motif PXVXL in the N-terminus of RNF123 was required for binding to HP1 proteins and targeting them for degradation. The role of endogenous RNF123 in the degradation of HP1 isoforms was confirmed by RNF123 RNAi experiments. Furthermore, FRAP analysis suggested that HP1β was displaced from chromatin in laminopathic cells.Our data support a role for RNF123 ubiquitin ligase in the degradation of HP1α and HP1β upon lamin A/C knock-down. Hence lamin misexpression can cause degradation of mislocalized proteins involved in key nuclear processes by induction of specific components of the ubiquitin-proteasome system.

  2. Evolution of a Chlorobenzene Degradative Pathway Among Bacteria in a Contaminated Groundwater Mediated by a Genomic Island in Ralstonia

    Science.gov (United States)

    2003-01-01

    1 Swiss Federal Institute for Environmental Science and Technology (EAWAG), Ueberlandstrasse 133, CH-8600 Dubendorl, Switzerland . 2 Air Force...i- Hooyberghs. L, Ravatn. R. eta!. (2002) Community shifts in a seeded 3-chlorobenzoate degrading membrane biofilm reactor: indications for

  3. Structural insights into 2,2'-azino-Bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)-mediated degradation of reactive blue 21 by engineered Cyathus bulleri Laccase and characterization of degradation products.

    Science.gov (United States)

    Kenzom, T; Srivastava, P; Mishra, S

    2014-12-01

    Advanced oxidation processes are currently used for the treatment of different reactive dyes which involve use of toxic catalysts. Peroxidases are reported to be effective on such dyes and require hydrogen peroxide and/or metal ions. Cyathus bulleri laccase, expressed in Pichia pastoris, catalyzes efficient degradation (78 to 85%) of reactive azo dyes (reactive black 5, reactive orange 16, and reactive red 198) in the presence of synthetic mediator ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)]. This laccase was engineered to degrade effectively reactive blue 21 (RB21), a phthalocyanine dye reported to be decolorized only by peroxidases. The 816-bp segment (toward the C terminus) of the lcc gene was subjected to random mutagenesis and enzyme variants (Lcc35, Lcc61, and Lcc62) were selected based on increased ABTS oxidizing ability. Around 78 to 95% decolorization of RB21 was observed with the ABTS-supplemented Lcc variants in 30 min. Analysis of the degradation products by mass spectrometry indicated the formation of several low-molecular-weight compounds. Mapping the mutations on the modeled structure implicated residues both near and far from the T1 Cu site that affected the catalytic efficiency of the mutant enzymes on ABTS and, in turn, the rate of oxidation of RB21. Several inactive clones were also mapped. The importance of geometry as well as electronic changes on the reactivity of laccases was indicated. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  4. The F-box Protein KIB1 Mediates Brassinosteroid-Induced Inactivation and Degradation of GSK3-like Kinases in Arabidopsis.

    Science.gov (United States)

    Zhu, Jia-Ying; Li, Yuyao; Cao, Dong-Mei; Yang, Hongjuan; Oh, Eunkyoo; Bi, Yang; Zhu, Shengwei; Wang, Zhi-Yong

    2017-06-01

    The glycogen synthase kinase-3 (GSK3) family kinases are central cellular regulators highly conserved in all eukaryotes. In Arabidopsis, the GSK3-like kinase BIN2 phosphorylates a range of proteins to control broad developmental processes, and BIN2 is degraded through unknown mechanism upon receptor kinase-mediated brassinosteroid (BR) signaling. Here we identify KIB1 as an F-box E3 ubiquitin ligase that promotes the degradation of BIN2 while blocking its substrate access. Loss-of-function mutations of KIB1 and its homologs abolished BR-induced BIN2 degradation and caused severe BR-insensitive phenotypes. KIB1 directly interacted with BIN2 in a BR-dependent manner and promoted BIN2 ubiquitination in vitro. Expression of an F-box-truncated KIB1 caused BIN2 accumulation but dephosphorylation of its substrate BZR1 and activation of BR responses because KIB1 blocked BIN2 binding to BZR1. Our study demonstrates that KIB1 plays an essential role in BR signaling by inhibiting BIN2 through dual mechanisms of blocking substrate access and promoting degradation. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Iron(III)-Mediated Oxidative Degradation on the Benzylic Carbon of Drug Molecules in the Absence of Initiating Peroxides.

    Science.gov (United States)

    Nanda, Kausik K; Blincoe, William D; Allain, Leonardo R; Wuelfing, W Peter; Harmon, Paul A

    2017-05-01

    Metal ions play an important role in oxidative drug degradation. One of the most ubiquitous metal ion impurities in excipients and buffers is Fe(III). In the field of oxidative drug degradation chemistry, the role of Fe(III) has been primarily discussed in terms of its effect in reaction with trace hydroperoxide impurities. However, the role of Fe(III) acting as a direct oxidant of drug molecules, which could operate in the absence of any hydroperoxide impurities, is less common. This work focuses on Fe(III)-induced oxidation of some aromatic drug molecules/drug fragments containing benzylic C-H bonds in the absence of initiating peroxides. Alcohol and ketone degradates are formed at the benzylic carbon atom. The formation of a π-stabilized cation radical is postulated as the key intermediate for the downstream oxidation. Implications are briefly discussed. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  6. An Intracellular Laccase Is Responsible for Epicatechin-Mediated Anthocyanin Degradation in Litchi Fruit Pericarp1[OPEN

    Science.gov (United States)

    Fang, Fang; Zhang, Xue-lian; Gong, Yi-hui; Li, Wen-jun; Shi, Zhao-wan; He, Quan; Wu, Qing; Li, Lu; Jiang, Lin-lin; Cai, Zhi-gao; Oren-Shamir, Michal; Zhang, Zhao-qi

    2015-01-01

    In contrast to the detailed molecular knowledge available on anthocyanin synthesis, little is known about its catabolism in plants. Litchi (Litchi chinensis) fruit lose their attractive red color soon after harvest. The mechanism leading to quick degradation of anthocyanins in the pericarp is not well understood. An anthocyanin degradation enzyme (ADE) was purified to homogeneity by sequential column chromatography, using partially purified anthocyanins from litchi pericarp as a substrate. The purified ADE, of 116 kD by urea SDS-PAGE, was identified as a laccase (ADE/LAC). The full-length complementary DNA encoding ADE/LAC was obtained, and a polyclonal antibody raised against a deduced peptide of the gene recognized the ADE protein. The anthocyanin degradation function of the gene was confirmed by its transient expression in tobacco (Nicotiana benthamiana) leaves. The highest ADE/LAC transcript abundance was in the pericarp in comparison with other tissues, and was about 1,000-fold higher than the polyphenol oxidase gene in the pericarp. Epicatechin was found to be the favorable substrate for the ADE/LAC. The dependence of anthocyanin degradation by the enzyme on the presence of epicatechin suggests an ADE/LAC epicatechin-coupled oxidation model. This model was supported by a dramatic decrease in epicatechin content in the pericarp parallel to anthocyanin degradation. Immunogold labeling transmission electron microscopy suggested that ADE/LAC is located mainly in the vacuole, with essential phenolic substances. ADE/LAC vacuolar localization, high expression levels in the pericarp, and high epicatechin-dependent anthocyanin degradation support its central role in pigment breakdown during pericarp browning. PMID:26514808

  7. Evaluating the effectiveness of marine actinobacterial extract and its mediated titanium dioxide nanoparticles in the degradation of azo dyes.

    Science.gov (United States)

    Priyaragini, S; Veena, S; Swetha, D; Karthik, L; Kumar, G; Bhaskara Rao, K V

    2014-04-01

    Aim of the present study was to synthesize titanium dioxide nanoparticles (TiO2 NPs) from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates were isolated from Chennai marine sediments, Tamilnadu, India and analyzed for the synthesis of TiO2 NPs using titanium hydroxide. Among these, the isolate PSV 3 showed positive results for the synthesis of TiO2 NPs, which was confirmed by UV analysis. Further characterization of the synthesized TiO2 NPs was done using XRD, AFM and FT-IR analysis. Actinobacterial crude extract and synthesized TiO2 NPs was found efficient in degrading azo dye such as Acid Red 79 (AR-79) and Acid Red 80 (AR-80). Degradation percentage was found to be 81% for AR-79, 83% for AR-80 using actinobacterial crude extract and 84% for AR-79, 85% for AR-80 using TiO2 NPs. Immobilized actinobacterial cells showed 88% for AR-79 and 81% for AR-80, dye degrading capacity. Degraded components were characterized by FT-IR and GC-MS analysis. The phytotoxicity test with 500 μg/mL of untreated dye showed remarkable phenotypic as well as cellular damage to Tagetes erecta plant. Comparatively no such damage was observed on plants by degraded dye components. In biotoxicity assay, treated dyes showed less toxic effect as compared to the untreated dyes. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  8. Cytokinin Antagonizes Abscisic Acid-Mediated Inhibition of Cotyledon Greening by Promoting the Degradation of ABSCISIC ACID INSENSITIVE5 Protein in Arabidopsis1[C][W

    Science.gov (United States)

    Guan, Chunmei; Wang, Xingchun; Feng, Jian; Hong, Sulei; Liang, Yan; Ren, Bo; Zuo, Jianru

    2014-01-01

    In higher plants, seed germination is followed by postgerminative growth. One of the key developmental events during postgerminative growth is cotyledon greening, which enables a seedling to establish photosynthetic capacity. The plant phytohormone abscisic acid (ABA) plays a vital role by inhibiting seed germination and postgerminative growth in response to dynamically changing internal and environmental cues. It has been shown that ABSCISIC ACID INSENSITIVE5 (ABI5), a basic leucine zipper transcription factor, is an important factor in the regulation of the ABA-mediated inhibitory effect on seed germination and postgerminative growth. Conversely, the phytohormone cytokinin has been proposed to promote seed germination by antagonizing the ABA-mediated inhibitory effect. However, the underpinning molecular mechanism of cytokinin-repressed ABA signaling is largely unknown. Here, we show that cytokinin specifically antagonizes ABA-mediated inhibition of cotyledon greening with minimal effects on seed germination in Arabidopsis (Arabidopsis thaliana). We found that the cytokinin-antagonized ABA effect is dependent on a functional cytokinin signaling pathway, mainly involved in the cytokinin receptor gene CYTOKININ RESPONSE1/ARABIDOPSIS HISTIDINE KINASE4, downstream histidine phosphotransfer protein genes AHP2, AHP3, and AHP5, and a type B response regulator gene, ARR12, which genetically acts upstream of ABI5 to regulate cotyledon greening. Cytokinin has no apparent effect on the transcription of ABI5. However, cytokinin efficiently promotes the proteasomal degradation of ABI5 in a cytokinin signaling-dependent manner. These results define a genetic pathway through which cytokinin specifically induces the degradation of ABI5 protein, thereby antagonizing ABA-mediated inhibition of postgerminative growth. PMID:24443524

  9. Substrate recognition in ER-associated degradation mediated by Eps1, a member of the protein disulfide isomerase family

    OpenAIRE

    Wang, Qiongqing; Chang, Amy

    2003-01-01

    Pma1-D378N is a misfolded plasma membrane protein in yeast that is prevented from delivery to the cell surface and targeted instead for ER-associated degradation (ERAD). Degradation of Pma1-D378N is dependent on the ubiquitin ligase Doa10 and the ubiquitin chaperone Cdc48. Recognition of Pma1-D378N by the ERAD pathway is dependent on Eps1, a transmembrane member of the protein disulfide isomerase (PDI) oxidoreductase family. Eps1 has two thioredoxin-like domains containing a CPHC and a CDKC a...

  10. The presence of C/EBPα and its degradation are both required for TRIB2-mediated leukaemia

    NARCIS (Netherlands)

    O'Connor, C; Lohan, F; Campos, J; Ohlsson, E; Salomè, M; Forde, C; Artschwager, R; Liskamp, R M; Cahill, M R; Kiely, P A; Porse, B; Keeshan, K

    2016-01-01

    C/EBPα (p42 and p30 isoforms) is commonly dysregulated in cancer via the action of oncogenes, and specifically in acute myeloid leukaemia (AML) by mutation. Elevated TRIB2 leads to the degradation of C/EBPα p42, leaving p30 intact in AML. Whether this relationship is a cooperative event in AML

  11. Isolation and characterization of a tomato non-specific lipid transfer protein involved in polygalacturonase-mediated pectin degradation

    NARCIS (Netherlands)

    Tomassen, M.M.M.; Barrett, D.M.; Valk, van der H.C.P.M.; Woltering, E.J.

    2007-01-01

    An important aspect of the ripening process of tomato fruit is softening. Softening is accompanied by hydrolysis of the pectin in the cell wall by pectinases, causing loss of cell adhesion in the middle lamella. One of the most significant pectin-degrading enzymes is polygalacturonase (PG). Previous

  12. Efficient degradation of carbamazepine by easily recyclable microscaled CuFeO{sub 2} mediated heterogeneous activation of peroxymonosulfate

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yaobin, E-mail: yaobinding@mail.scuec.edu.cn [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074 (China); Tang, Hebin [College of Pharmacy, South-Central University for Nationalities, Wuhan 430074 (China); Zhang, Shenghua; Wang, Songbo [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074 (China); Tang, Heqing, E-mail: tangheqing@mail.scuec.edu.cn [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074 (China)

    2016-11-05

    Highlights: • CuFeO{sub 2} microparticles were prepared by a microwave-assisted hydrothermal method. • CuFeO{sub 2} microparticles efficiently catalyzed the activation of peroxymonosulfate. • Quenching experiments confirmed sulfate radicals as the major reactive radicals. • Carbamazepine was rapidly degraded by micro-CuFeO{sub 2}/peroxymonosulfate. • Feasibility of CuFeO{sub 2}/peroxymonosulfate was tested for treatment of actual water. - Abstract: Microscaled CuFeO{sub 2} particles (micro-CuFeO{sub 2}) were rapidly prepared via a microwave-assisted hydrothermal method and characterized by scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy. It was found that the micro-CuFeO{sub 2} was of pure phase and a rhombohedral structure with size in the range of 2.8 ± 0.6 μm. The micro-CuFeO{sub 2} efficiently catalyzed the activation of peroxymonosulfate (PMS) to generate sulfate radicals (SO{sub 4}·−), causing the fast degradation of carbamazepine (CBZ). The catalytic activity of micro-CuFeO{sub 2} was observed to be 6.9 and 25.3 times that of micro-Cu{sub 2}O and micro-Fe{sub 2}O{sub 3}, respectively. The enhanced activity of micro-CuFeO{sub 2} for the activation of PMS was confirmed to be attributed to synergistic effect of surface bonded Cu(I) and Fe(III). Sulfate radical was the primary radical species responsible for the CBZ degradation. As a microscaled catalyst, micro-CuFeO{sub 2} can be easily recovered by gravity settlement and exhibited improved catalytic stability compared with micro-Cu{sub 2}O during five successive degradation cycles. Oxidative degradation of CBZ by the couple of PMS/CuFeO{sub 2} was effective in the studied actual aqueous environmental systems.

  13. Ku70 acetylation and modulation of c-Myc/ATF4/CHOP signaling axis by SIRT1 inhibition lead to sensitization of HepG2 cells to TRAIL through induction of DR5 and down-regulation of c-FLIP

    DEFF Research Database (Denmark)

    Kim, Mi-Ju; Hong, Kyung-Soo; Kim, Hak-Bong

    2013-01-01

    In this study, we investigated the role of c-Myc/ATF4/CHOP signaling pathway in sensitization of human hepatoma HepG2 cells to TRAIL. Knockdown of SIRT1 or treatment with SIRT1 inhibitor caused the up-regulation of DR5 and down-regulation of c-FLIP through modulation of c-Myc/ATF4/CHOP pathway, a...

  14. KRAS Protein Stability Is Regulated through SMURF2: UBCH5 Complex-Mediated β-TrCP1 Degradation

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    Shirish Shukla

    2014-02-01

    Full Text Available Attempts to target mutant KRAS have been unsuccessful. Here, we report the identification of Smad ubiquitination regulatory factor 2 (SMURF2 and UBCH5 as a critical E3:E2 complex maintaining KRAS protein stability. Loss of SMURF2 either by small interfering RNA/short hairpin RNA (siRNA/shRNA or by overexpression of a catalytically inactive mutant causes KRAS degradation, whereas overexpression of wild-type SMURF2 enhances KRAS stability. Importantly, mutant KRAS is more susceptible to SMURF2 loss where protein half-life decreases from >12 hours in control siRNA-treated cells to <3 hours on Smurf2 silencing, whereas only marginal differences were noted for wild-type protein. This loss of mutant KRAS could be rescued by overexpressing a siRNA-resistant wild-type SMURF2. Our data further show that SMURF2 monoubiquitinates UBCH5 at lysine 144 to form an active complex required for efficient degradation of a RAS-family E3, β-transducing repeat containing protein 1 (β-TrCP1. Conversely, β-TrCP1 is accumulated on SMURF2 loss, leading to increased KRAS degradation. Therefore, as expected, β-TrCP1 knockdown following Smurf2 siRNA treatment rescues mutant KRAS loss. Further, we identify two conserved proline (P residues in UBCH5 critical for SMURF2 interaction; mutation of either of these P to alanine also destabilizes KRAS. As a proof of principle, we demonstrate that Smurf2 silencing reduces the clonogenic survival in vitro and prolongs tumor latency in vivo in cancer cells including mutant KRAS-driven tumors. Taken together, we show that SMURF2:UBCH5 complex is critical in maintaining KRAS protein stability and propose that targeting such complex may be a unique strategy to degrade mutant KRAS to kill cancer cells.

  15. Copper tolerance mediated by polyphosphate degradation and low-affinity inorganic phosphate transport system in Escherichia coli.

    Science.gov (United States)

    Grillo-Puertas, Mariana; Schurig-Briccio, Lici Ariane; Rodríguez-Montelongo, Luisa; Rintoul, María Regina; Rapisarda, Viviana Andrea

    2014-03-19

    Metal tolerance in bacteria has been related to polyP in a model in which heavy metals stimulate the polymer hydrolysis, forming metal-phosphate complexes that are exported. As previously described in our laboratory, Escherichia coli cells grown in media containing a phosphate concentration >37 mM maintained an unusually high polyphosphate (polyP) level in stationary phase. The aim of the present work was to evaluate the influence of polyP levels as the involvement of low-affinity inorganic phosphate transport (Pit) system in E. coli copper tolerance. PolyP levels were modulated by the media phosphate concentration and/or using mutants in polyP metabolism. Stationary phase wild-type cells grown in high phosphate medium were significantly more tolerant to copper than those grown in sufficient phosphate medium. Copper addition to tolerant cells induced polyP degradation by PPX (an exopolyphosphatase), phosphate efflux and membrane polarization. ppk-ppx- (unable to synthesize/degrade polyP), ppx- (unable to degrade polyP) and Pit system mutants were highly sensitive to metal even in high phosphate media. In exponential phase, CopA and polyP-Pit system would act simultaneously to detoxify the metal or one could be sufficient to safeguard the absence of the other. Our results support a mechanism for copper detoxification in exponential and stationary phases of E. coli, involving Pit system and degradation of polyP. Data reflect the importance of the environmental phosphate concentration in the regulation of the microbial physiological state.

  16. Dietary apigenin potentiates the inhibitory effect of interferon-α on cancer cell viability through inhibition of 26S proteasome-mediated interferon receptor degradation.

    Science.gov (United States)

    Li, Sheng; Yang, Li-Juan; Wang, Ping; He, Yu-Jiao; Huang, Jun-Mei; Liu, Han-Wei; Shen, Xiao-Fei; Wang, Fei

    2016-01-01

    Type I interferons (IFN-α/β) have broad and potent immunoregulatory and antiproliferative activities. However, it is still known whether the dietary flavonoids exhibit their antiviral and anticancer properties by modulating the function of type I IFNs. This study aimed at determining the role of apigenin, a dietary plant flavonoid abundant in common fruits and vegetables, on the type I IFN-mediated inhibition of cancer cell viability. Inhibitory effect of apigenin on human 26S proteasome, a known negative regulator of type I IFN signaling, was evaluated in vitro. Molecular docking was conducted to know the interaction between apigenin and subunits of 26S proteasome. Effects of apigenin on JAK/STAT pathway, 26S proteasome-mediated interferon receptor stability, and cancer cells viability were also investigated. Apigenin was identified to be a potent inhibitor of human 26S proteasome in a cell-based assay. Apigenin inhibited the chymotrypsin-like, caspase-like, and trypsin-like activities of the human 26S proteasome and increased the ubiquitination of endogenous proteins in cells. Results from computational modeling of the potential interactions of apigenin with the chymotrypsin site (β5 subunit), caspase site (β1 subunit), and trypsin site (β2 subunit) of the proteasome were consistent with the observed proteasome inhibitory activity. Apigenin enhanced the phosphorylation of signal transducer and activator of transcription proteins (STAT1 and STAT2) and promoted the endogenous IFN-α-regulated gene expression. Apigenin inhibited the IFN-α-stimulated ubiquitination and degradation of type I interferon receptor 1 (IFNAR1). Apigenin also sensitized the inhibitory effect of IFN-α on viability of cervical carcinoma HeLa cells. These results suggest that apigenin potentiates the inhibitory effect of IFN-α on cancer cell viability by activating JAK/STAT signaling pathway through inhibition of 26S proteasome-mediated IFNAR1 degradation. This may provide a novel

  17. Modulation of defect-mediated energy transfer from ZnO nanoparticles for the photocatalytic degradation of bilirubin

    Directory of Open Access Journals (Sweden)

    Tanujjal Bora

    2013-11-01

    Full Text Available In recent years, nanotechnology has gained significant interest for applications in the medical field. In this regard, a utilization of the ZnO nanoparticles for the efficient degradation of bilirubin (BR through photocatalysis was explored. BR is a water insoluble byproduct of the heme catabolism that can cause jaundice when its excretion is impaired. The photocatalytic degradation of BR activated by ZnO nanoparticles through a non-radiative energy transfer pathway can be influenced by the surface defect-states (mainly the oxygen vacancies of the catalyst nanoparticles. These were modulated by applying a simple annealing in an oxygen-rich atmosphere. The mechanism of the energy transfer process between the ZnO nanoparticles and the BR molecules adsorbed at the surface was studied by using steady-state and picosecond-resolved fluorescence spectroscopy. A correlation of photocatalytic degradation and time-correlated single photon counting studies revealed that the defect-engineered ZnO nanoparticles that were obtained through post-annealing treatments led to an efficient decomposition of BR molecules that was enabled by Förster resonance energy transfer.

  18. FLASH knockdown sensitizes cells to Fas-mediated apoptosis via down-regulation of the anti-apoptotic proteins, MCL-1 and Cflip short.

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    Song Chen

    Full Text Available FLASH (FLICE-associated huge protein or CASP8AP2 is a large multifunctional protein that is involved in many cellular processes associated with cell death and survival. It has been reported to promote apoptosis, but we show here that depletion of FLASH in HT1080 cells by siRNA interference can also accelerate the process. As shown previously, depletion of FLASH halts growth by down-regulating histone biosynthesis and arrests the cell cycle in S-phase. FLASH knockdown followed by stimulating the cells with Fas ligand or anti-Fas antibodies was found to be associated with a more rapid cleavage of PARP, accelerated activation of caspase-8 and the executioner caspase-3 and rapid progression to cellular disintegration. As is the case for most anti-apoptotic proteins, FLASH was degraded soon after the onset of apoptosis. Depletion of FLASH also resulted in the reduced intracellular levels of the anti-apoptotic proteins, MCL-1 and the short isoform of cFLIP. FLASH knockdown in HT1080 mutant cells defective in p53 did not significantly accelerate Fas mediated apoptosis indicating that the effect was dependent on functional p53. Collectively, these results suggest that under some circumstances, FLASH suppresses apoptosis.

  19. Metabolic Stress Induces Caspase-3 Mediated Degradation and Inactivation of Farnesyl and Geranylgeranyl Transferase Activities in Pancreatic β-Cells

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    Rajakrishnan Veluthakal

    2016-11-01

    Full Text Available Background/Aims: At least 300 prenylated proteins are identified in the human genome; the majority of which partake in a variety of cellular processes including growth, differentiation, cytoskeletal organization/dynamics and vesicle trafficking. Aberrant prenylation of proteins is implicated in human pathologies including cancer; neurodegenerative diseases, retinitis pigmentosa, and premature ageing syndromes. Original observations from our laboratory have demonstrated that prenylation of proteins [small G-proteins and γ-subunits of trimeric G-proteins] is requisite for physiological insulin secretion. Herein, we assessed the impact of metabolic stress [gluco-, lipotoxicity and ER-stress] on the functional status of protein prenylation pathway in pancreatic β-cells. Methods: Farnesyltransferase [FTase] and geranylgeranyltransferase [GGTase] activities were quantified by radioisotopic methods. Caspase-3 activation and FTase/GGTase-α subunit degradation were determined by Western blotting. Results: We observed that metabolic stress activates caspase-3 and induces degradation of the common α-subunit of FTase and GGTase-I in INS-1 832/13 cells, normal rodent islets and human islets leading to functional defects [inactivation] in FTase and GGTase activities. Caspase-3 activation and FTase/GGTase-α degradation were also seen in islets from the Zucker diabetic fatty [ZDF] rat, a model for Type 2 diabetes. Consequential to defects in FTase/GGTase-α signaling, we observed significant accumulation of unprenylated proteins [Rap1] in β-cells exposed to glucotoxic conditions. These findings were replicated in β-cells following pharmacological inhibition of generation of prenylpyrophosphate substrates [Simvastatin] or catalytic activity of prenylating enzymes [GGTI-2147]. Conclusions: Our findings provide the first evidence to suggest that metabolic stress induced dysfunction of the islet β-cell may, in part, be due to defective protein prenylation

  20. Lesions of entorhinal cortex produce a calpain-mediated degradation of brain spectrin in dentate gyrus. I. Biochemical studies.

    Science.gov (United States)

    Seubert, P; Ivy, G; Larson, J; Lee, J; Shahi, K; Baudry, M; Lynch, G

    1988-09-06

    Lesions of the rat entorhinal cortex cause extensive synaptic restructuring and perturbation of calcium regulation in the dentate gyrus of hippocampus. Calpain is a calcium-activated protease which has been implicated in degenerative phenomena in muscles and in peripheral nerves. In addition, calpain degrades several major structural neuronal proteins and has been proposed to play a critical role in the morphological changes observed following deafferentation. In this report we present evidence that lesions of the entorhinal cortex produce a marked increase in the breakdown of brain spectrin, a substrate for calpain, in the dentate gyrus. Two lines of evidence indicate that this effect is due to calpain activation: (i) the spectrin breakdown products observed following the lesion are indistinguishable from calpain-generated spectrin fragments in vitro; and (ii) their appearance can be reduced by prior intraventricular in fusion of leupeptin, a calpain inhibitor. Levels of spectrin breakdown products are increased as early as 4 h post-lesion, reach maximal values at 2 days, and remain above normal to some degree for at least 27 days. In addition, a small but significant increase in spectrin proteolysis is also observed in the hippocampus contralateral to the lesioned side in the first week postlesion. At 2 days postlesion the total spectrin immunoreactivity (native polypeptide plus breakdown products) increases by 40%, suggesting that denervation of the dentate gyrus produces not only an increased rate of spectrin degradation but also an increased rate of spectrin synthesis. These results indicate that calpain activation and spectrin degradation are early biochemical events following deafferentation and might well participate in the remodelling of postsynaptic structures. Finally, the magnitude of the observed effects as well as the stable nature of the breakdown products provide a sensitive assay for neuronal pathology.

  1. Prefoldins Negatively Regulate Cold Acclimation in Arabidopsis thaliana by Promoting Nuclear Proteasome-Mediated HY5 Degradation.

    Science.gov (United States)

    Perea-Resa, Carlos; Rodríguez-Milla, Miguel A; Iniesto, Elisa; Rubio, Vicente; Salinas, Julio

    2017-06-05

    The process of cold acclimation is an important adaptive response whereby many plants from temperate regions increase their freezing tolerance after being exposed to low non-freezing temperatures. The correct development of this response relies on proper accumulation of a number of transcription factors that regulate expression patterns of cold-responsive genes. Multiple studies have revealed a variety of molecular mechanisms involved in promoting the accumulation of these transcription factors. Interestingly, however, the mechanisms implicated in controlling such accumulation to ensure their adequate levels remain largely unknown. In this work, we demonstrate that prefoldins (PFDs) control the levels of HY5, an Arabidopsis transcription factor with a key role in cold acclimation by activating anthocyanin biosynthesis, in response to low temperature. Our results show that, under cold conditions, PFDs accumulate into the nucleus through a DELLA-dependent mechanism, where they interact with HY5, triggering its ubiquitination and subsequent degradation. The degradation of HY5 would result, in turn, in anthocyanin biosynthesis attenuation, ensuring the accurate development of cold acclimation. These findings uncover an unanticipated nuclear function for PFDs in plant responses to abiotic stresses. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

  2. Could growth factor-mediated extracellular matrix deposition and degradation offer the ground for directed pharmacological targeting in fibrosarcoma?

    Science.gov (United States)

    Nikitovic, D; Berdiaki, A; Banos, A; Tsatsakis, A; Karamanos, N K; Tzanakakis, G N

    2013-01-01

    The specific organization of the tumor extracellular matrix (ECM) is an intrinsic and basic step in the convoluted pathways of tumorigenesis. Fibrosarcoma is a rare, lethal, malignant tumor originating from fibroblasts, characterized by the formation of an abundant ECM. Fibroblastoid cells undergoing malignant transformation specifically alter composition and organization of their ECM to facilitate growth, survival and invasion. Fibrosarcoma cells were shown to have a high content and turnover of ECM components including hyaluronan, proteoglycans, collagens, fibronectin and laminin. Cell signaling by endogenous growth factors, such as TGFβ, EGF, FGF2, VEGF and IFG-I, is directly correlated to ECM remodeling, stroma formation and fibrosarcoma progression. In this regard, growth factors affect the expression of matrix macromolecules, such as secreted and cell-associated proteoglycans, hyaluronan and its receptors CD44 and RHAMM, as well as the expression and activity of matrix- degrading metalloproteinases, which are of critical importance in tissue remodeling and fibrosarcoma progression. Therefore, therapeutic approaches considering growth factors and their receptors as well as downstream signaling in human cancers may well be pharmacological targets being currently explored. In this article, we focus on growth factor signaling regulating fibrosarcoma cell ECM organization at the level of deposition and degradation of ECM macromolecules, the relation of ECM remodeling with fibrosarcoma cell malignant behaviour as well as the putative strategies for its therapeutic intervention.

  3. Human Cytomegalovirus IE2 86 kDa Protein Induces STING Degradation and Inhibits cGAMP-Mediated IFN-β Induction

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    Jung-Eun Kim

    2017-09-01

    Full Text Available Stimulator of interferon genes (STING is a critical signaling molecule in the innate immune response against DNA viruses by either directly sensing intracellular DNA or functioning as an adaptor molecule to activate the type I interferon (IFN signaling pathway. We determined the functional interaction between STING and human cytomegalovirus (HCMV. A cDNA library containing 133 HCMV ORFs was screened to identify viral genes that inhibit STING-induced IFN-β promoter activation. Among the screened ORFs, UL122, which encodes the immediate-early 2 86 kDa (IE86 protein, strongly abolished STING-induced IFN-β promoter activation. Interestingly, IE86 protein facilitated the proteasome-dependent degradation of STING and inhibited 2′3′-cGAMP-mediated induction of IFNB1 and CXCL10. Taken together, this study demonstrates the existence of a post-translational regulation of STING by HCMV IE86 protein.

  4. Bifunctional anti-huntingtin proteasome-directed intrabodies mediate efficient degradation of mutant huntingtin exon 1 protein fragments.

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    David C Butler

    Full Text Available Huntington's disease (HD is a fatal autosomal dominant neurodegenerative disorder caused by a trinucleotide (CAG(n repeat expansion in the coding sequence of the huntingtin gene, and an expanded polyglutamine (>37Q tract in the protein. This results in misfolding and accumulation of huntingtin protein (htt, formation of neuronal intranuclear and cytoplasmic inclusions, and neuronal dysfunction/degeneration. Single-chain Fv antibodies (scFvs, expressed as intrabodies that bind htt and prevent aggregation, show promise as immunotherapeutics for HD. Intrastriatal delivery of anti-N-terminal htt scFv-C4 using an adeno-associated virus vector (AAV2/1 significantly reduces the size and number of aggregates in HDR6/1 transgenic mice; however, this protective effect diminishes with age and time after injection. We therefore explored enhancing intrabody efficacy via fusions to heterologous functional domains. Proteins containing a PEST motif are often targeted for proteasomal degradation and generally have a short half life. In ST14A cells, fusion of the C-terminal PEST region of mouse ornithine decarboxylase (mODC to scFv-C4 reduces htt exon 1 protein fragments with 72 glutamine repeats (httex1-72Q by ~80-90% when compared to scFv-C4 alone. Proteasomal targeting was verified by either scrambling the mODC-PEST motif, or via proteasomal inhibition with epoxomicin. For these constructs, the proteasomal degradation of the scFv intrabody proteins themselves was reduced<25% by the addition of the mODC-PEST motif, with or without antigens. The remaining intrabody levels were amply sufficient to target N-terminal httex1-72Q protein fragment turnover. Critically, scFv-C4-PEST prevents aggregation and toxicity of httex1-72Q fragments at significantly lower doses than scFv-C4. Fusion of the mODC-PEST motif to intrabodies is a valuable general approach to specifically target toxic antigens to the proteasome for degradation.

  5. APC/C-mediated degradation of dsRNA-binding protein 4 (DRB4 involved in RNA silencing.

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    Katia Marrocco

    Full Text Available Selective protein degradation via the ubiquitin-26S proteasome is a major mechanism underlying DNA replication and cell division in all Eukaryotes. In particular, the APC/C (Anaphase Promoting Complex or Cyclosome is a master ubiquitin protein ligase (E3 that targets regulatory proteins for degradation allowing sister chromatid separation and exit from mitosis. Interestingly, recent work also indicates that the APC/C remains active in differentiated animal and plant cells. However, its role in post-mitotic cells remains elusive and only a few substrates have been characterized.In order to identify novel APC/C substrates, we performed a yeast two-hybrid screen using as the bait Arabidopsis APC10/DOC1, one core subunit of the APC/C, which is required for substrate recruitment. This screen identified DRB4, a double-stranded RNA binding protein involved in the biogenesis of different classes of small RNA (sRNA. This protein interaction was further confirmed in vitro and in plant cells. Moreover, APC10 interacts with DRB4 through the second dsRNA binding motif (dsRBD2 of DRB4, which is also required for its homodimerization and binding to its Dicer partner DCL4. We further showed that DRB4 protein accumulates when the proteasome is inactivated and, most importantly, we found that DRB4 stability depends on APC/C activity. Hence, depletion of Arabidopsis APC/C activity by RNAi leads to a strong accumulation of endogenous DRB4, far beyond its normal level of accumulation. However, we could not detect any defects in sRNA production in lines where DRB4 was overexpressed.Our work identified a first plant substrate of the APC/C, which is not a regulator of the cell cycle. Though we cannot exclude that APC/C-dependent degradation of DRB4 has some regulatory roles under specific growth conditions, our work rather points to a housekeeping function of APC/C in maintaining precise cellular-protein concentrations and homeostasis of DRB4.

  6. Calreticulin-mutant proteins induce megakaryocytic signaling to transform hematopoietic cells and undergo accelerated degradation and Golgi-mediated secretion

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    Lijuan Han

    2016-05-01

    Full Text Available Abstract Background Somatic calreticulin (CALR, Janus kinase 2 (JAK2, and thrombopoietin receptor (MPL mutations essentially show mutual exclusion in myeloproliferative neoplasms (MPN, suggesting that they activate common oncogenic pathways. Recent data have shown that MPL function is essential for CALR mutant-driven MPN. However, the exact role and the mechanisms of action of CALR mutants have not been fully elucidated. Methods The murine myeloid cell line 32D and human HL60 cells overexpressing the most frequent CALR type 1 and type 2 frameshift mutants were generated to analyze the first steps of cellular transformation, in the presence and absence of MPL expression. Furthermore, mutant CALR protein stability and secretion were examined using brefeldin A, MG132, spautin-1, and tunicamycin treatment. Results The present study demonstrates that the expression of endogenous Mpl, CD41, and the key megakaryocytic transcription factor NF-E2 is stimulated by type 1 and type 2 CALR mutants, even in the absence of exogenous MPL. Mutant CALR expressing 32D cells spontaneously acquired cytokine independence, and this was associated with increased Mpl mRNA expression, CD41, and NF-E2 protein as well as constitutive activation of downstream signaling and response to JAK inhibitor treatment. Exogenous expression of MPL led to constitutive activation of STAT3 and 5, ERK1/2, and AKT, cytokine-independent growth, and reduction of apoptosis similar to the effects seen in the spontaneously outgrown cells. We observed low CALR-mutant protein amounts in cellular lysates of stably transduced cells, and this was due to accelerated protein degradation that occurred independently from the ubiquitin-proteasome system as well as autophagy. CALR-mutant degradation was attenuated by MPL expression. Interestingly, we found high levels of mutated CALR and loss of downstream signaling after blockage of the secretory pathway and protein glycosylation. Conclusions These

  7. The RING-CH ligase K5 antagonizes restriction of KSHV and HIV-1 particle release by mediating ubiquitin-dependent endosomal degradation of tetherin.

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    Claire Pardieu

    2010-04-01

    Full Text Available Tetherin (CD317/BST2 is an interferon-induced membrane protein that inhibits the release of diverse enveloped viral particles. Several mammalian viruses have evolved countermeasures that inactivate tetherin, with the prototype being the HIV-1 Vpu protein. Here we show that the human herpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV is sensitive to tetherin restriction and its activity is counteracted by the KSHV encoded RING-CH E3 ubiquitin ligase K5. Tetherin expression in KSHV-infected cells inhibits viral particle release, as does depletion of K5 protein using RNA interference. K5 induces a species-specific downregulation of human tetherin from the cell surface followed by its endosomal degradation. We show that K5 targets a single lysine (K18 in the cytoplasmic tail of tetherin for ubiquitination, leading to relocalization of tetherin to CD63-positive endosomal compartments. Tetherin degradation is dependent on ESCRT-mediated endosomal sorting, but does not require a tyrosine-based sorting signal in the tetherin cytoplasmic tail. Importantly, we also show that the ability of K5 to substitute for Vpu in HIV-1 release is entirely dependent on K18 and the RING-CH domain of K5. By contrast, while Vpu induces ubiquitination of tetherin cytoplasmic tail lysine residues, mutation of these positions has no effect on its antagonism of tetherin function, and residual tetherin is associated with the trans-Golgi network (TGN in Vpu-expressing cells. Taken together our results demonstrate that K5 is a mechanistically distinct viral countermeasure to tetherin-mediated restriction, and that herpesvirus particle release is sensitive to this mode of antiviral inhibition.

  8. Neurofibromatosis type 2 tumor suppressor protein, NF2, induces proteasome-mediated degradation of JC virus T-antigen in human glioblastoma.

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    Sarah Beltrami

    Full Text Available Neurofibromatosis type 2 protein (NF2 has been shown to act as tumor suppressor primarily through its functions as a cytoskeletal scaffold. However, NF2 can also be found in the nucleus, where its role is less clear. Previously, our group has identified JC virus (JCV tumor antigen (T-antigen as a nuclear binding partner for NF2 in tumors derived from JCV T-antigen transgenic mice. The association of NF2 with T-antigen in neuronal origin tumors suggests a potential role for NF2 in regulating the expression of the JCV T-antigen. Here, we report that NF2 suppresses T-antigen protein expression in U-87 MG human glioblastoma cells, which subsequently reduces T-antigen-mediated regulation of the JCV promoter. When T-antigen mRNA was quantified, it was determined that increasing expression of NF2 correlated with an accumulation of T-antigen mRNA; however, a decrease in T-antigen at the protein level was observed. NF2 was found to promote degradation of ubiquitin bound T-antigen protein via a proteasome dependent pathway concomitant with the accumulation of the JCV early mRNA encoding T-antigen. The interaction between T-antigen and NF2 maps to the FERM domain of NF2, which has been shown previously to be responsible for its tumor suppressor activity. Co-immunoprecipitation assays revealed a ternary complex among NF2, T-antigen, and the tumor suppressor protein, p53 within a glioblastoma cell line. Further, these proteins were detected in various degrees in patient tumor tissue, suggesting that these associations may occur in vivo. Collectively, these results demonstrate that NF2 negatively regulates JCV T-antigen expression by proteasome-mediated degradation, and suggest a novel role for NF2 as a suppressor of JCV T-antigen-induced cell cycle regulation.

  9. Nitric Oxide-Mediated Regulation of Gamma Interferon-Induced Bacteriostasis: Inhibition and Degradation of Human Indoleamine 2,3-Dioxygenase

    Science.gov (United States)

    Hucke, Christian; MacKenzie, Colin R.; Adjogble, Koku D. Z.; Takikawa, Osamu; Däubener, Walter

    2004-01-01

    Tryptophan depletion resulting from indoleamine 2,3-dioxygenase (IDO) activity within the kynurenine pathway is one of the most prominent gamma interferon (IFN-γ)-inducible antimicrobial effector mechanisms in human cells. On the other hand, nitric oxide (NO) produced by the inducible isoform of NO synthase (iNOS) serves a more immunoregulatory role in human cells and thereby interacts with tryptophan depletion in a number of ways. We investigated the effects of NO on IDO gene transcription, protein synthesis, and enzyme activity as well as on IDO-mediated bacteriostasis in the human epithelial cell line RT4. IFN-γ-stimulated RT4 cells were able to inhibit the growth of Staphylococcus aureus in an IDO-mediated fashion, and this bacteriostatic effect was abolished by endogenously produced NO. These findings were supported by experiments which showed that IDO activity in extracts of IFN-γ-stimulated cells is inhibited by the chemical NO donors diethylenetriamine diazeniumdiolate, S-nitroso-l-cysteine, and S-nitroso-N-acetyl-d,l-penicillamine. Furthermore, we found that both endogenous and exogenous NO strongly reduced the level of IDO protein content in RT4 cells. This effect was not due to a decrease in IDO gene transcription or mRNA stability. By using inhibitors of proteasomal proteolytic activity, we showed that NO production led to an accelerated degradation of IDO protein in the proteasome. This is the first report, to our knowledge, that demonstrates that the IDO is degraded by the proteasome and that NO has an effect on IDO protein stability. PMID:15102781

  10. Matrix metalloproteinase-9-mediated type III collagen degradation as a novel serological biochemical marker for liver fibrogenesis

    DEFF Research Database (Denmark)

    Veidal, Sanne S; Vassiliadis, Efstathios; Barascuk, Natasha

    2010-01-01

    During fibrogenesis in the liver, in which excessive remodelling of the extracellular matrix (ECM) occurs, both the quantity of type III collagen (CO3) and levels of matrix metalloproteinases (MMPs), including MMP-9, increase significantly. MMPs play major roles in ECM remodelling, via their acti......During fibrogenesis in the liver, in which excessive remodelling of the extracellular matrix (ECM) occurs, both the quantity of type III collagen (CO3) and levels of matrix metalloproteinases (MMPs), including MMP-9, increase significantly. MMPs play major roles in ECM remodelling, via...... their activity in the proteolytic degradation of extracellular macromolecules such as collagens, resulting in the generation of specific cleavage fragments. These neo-epitopes may be used as markers of fibrosis....

  11. The presence of C/EBPα and its degradation are both required for TRIB2-mediated leukaemia

    DEFF Research Database (Denmark)

    O'Connor, C; Lohan, F; Campos, J

    2016-01-01

    transformation is not known and the molecular mechanism involved remains elusive. Using mouse genetics, our data reveal that in the complete absence of C/EBPα, TRIB2 was unable to induce AML. Only in the presence of C/EBPα p42 and p30, were TRIB2 and p30 able to cooperate to decrease the latency of disease. We...... lysine residue on C/EBPα. We show effective targeting of this pathway pharmacologically using proteasome inhibitors in TRIB2-positive AML cells. Together, our data show that excess p30 cooperated with TRIB2 only in the presence of p42 to accelerate AML, and the direct interaction and degradation of C...

  12. Degradation of cytokinins by maize cytokinin dehydrogenase is mediated by free radicals generated by enzymatic oxidation of natural benzoxazinones.

    Science.gov (United States)

    Frébortová, Jitka; Novák, Ondrej; Frébort, Ivo; Jorda, Radek

    2010-02-01

    Hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-one (DIMBOA) was isolated from maize phloem sap as a compound enhancing the degradation of isopentenyl adenine by maize cytokinin dehydrogenase (CKX), after oxidative conversion by either laccase or peroxidase. Laccase and peroxidase catalyze oxidative cleavage of DIMBOA to 4-nitrosoresorcinol-1-monomethyl ether (coniferron), which serves as a weak electron acceptor of CKX. The oxidation of DIMBOA and coniferron generates transitional free radicals that are used by CKX as effective electron acceptors. The function of free radicals in the CKX-catalyzed reaction was also verified with a stable free radical of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid. Application of exogenous cytokinin to maize seedlings resulted in an enhanced benzoxazinoid content in maize phloem sap. The results indicate a new function for DIMBOA in the metabolism of the cytokinin group of plant hormones.

  13. [6]-Shogaol Inhibits α-MSH-Induced Melanogenesis through the Acceleration of ERK and PI3K/Akt-Mediated MITF Degradation

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    Huey-Chun Huang

    2014-01-01

    Full Text Available [6]-Shogaol is the main biologically active component of ginger. Previous reports showed that [6]-shogaol has several pharmacological characteristics, such as antioxidative, anti-inflammatory, antimicrobial, and anticarcinogenic properties. However, the effects of [6]-shogaol on melanogenesis remain to be elucidated. The study aimed to evaluate the potential skin whitening mechanisms of [6]-shogaol. The effects of [6]-shogaol on cell viability, melanin content, tyrosinase activity, and the expression of the tyrosinase and microphthalmia-associated transcription factor (MITF were measured. The results revealed that [6]-shogaol effectively suppresses tyrosinase activity and the amount of melanin and that those effects are more pronounced than those of arbutin. It was also found that [6]-shogaol decreased the protein expression levels of tyrosinase-related protein 1 (TRP-1 and microphthalmia-associated transcriptional factor (MITF. In addition, the MITF mRNA levels were also effectively decreased in the presence of 20 μM [6]-shogaol. The degradation of MITF protein was inhibited by the MEK 1-inhibitor (U0126 or phosphatidylinositol-3-kinase inhibitor (PI3K inhibitor (LY294002. Further immunofluorescence staining assay implied the involvement of the proteasome in the downregulation of MITF by [6]-shogaol. Our confocal assay results also confirmed that [6]-shogaol inhibited α-melanocyte stimulating hormone- (α-MSH- induced melanogenesis through the acceleration of extracellular responsive kinase (ERK and phosphatidylinositol-3-kinase- (PI3K/Akt- mediated MITF degradation.

  14. Autophagy and ubiquitin-mediated proteolysis may not be involved in the degradation of spermatozoon mitochondria in mouse and porcine early embryos.

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    Jin, Yong-Xun; Zheng, Zhong; Yu, Xian-Feng; Zhang, Jia-Bao; Namgoong, Suk; Cui, Xiang-Shun; Hyun, Sang-Hwan; Kim, Nam-Hyung

    2016-02-01

    The mitochondrial genome is maternally inherited in animals, despite the fact that paternal mitochondria enter oocytes during fertilization. Autophagy and ubiquitin-mediated degradation are responsible for the elimination of paternal mitochondria in Caenorhabditis elegans; however, the involvement of these two processes in the degradation of paternal mitochondria in mammals is not well understood. We investigated the localization patterns of light chain 3 (LC3) and ubiquitin in mouse and porcine embryos during preimplantation development. We found that LC3 and ubiquitin localized to the spermatozoon midpiece at 3 h post-fertilization, and that both proteins were colocalized with paternal mitochondria and removed upon fertilization during the 4-cell stage in mouse and the zygote stage in porcine embryos. Sporadic paternal mitochondria were present beyond the morula stage in the mouse, and paternal mitochondria were restricted to one blastomere of 4-cell embryos. An autophagy inhibitor, 3-methyladenine (3-MA), did not affect the distribution of paternal mitochondria compared with the positive control, while an autophagy inducer, rapamycin, accelerated the removal of paternal mitochondria compared with the control. After the intracytoplasmic injection of intact spermatozoon into mouse oocytes, LC3 and ubiquitin localized to the spermatozoon midpiece, but remnants of undegraded paternal mitochondria were retained until the blastocyst stage. Our results show that paternal mitochondria colocalize with autophagy receptors and ubiquitin and are removed after in vitro fertilization, but some remnants of sperm mitochondrial sheath may persist up to morula stage after intracytoplasmic spermatozoon injection (ICSI).

  15. PKCε promotes HuD-mediated neprilysin mRNA stability and enhances neprilysin-induced Aβ degradation in brain neurons.

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    Chol Seung Lim

    Full Text Available Amyloid-beta (Aβ peptide accumulation in the brain is a pathological hallmark of all forms of Alzheimer's disease. An imbalance between Aβ production and clearance from the brain may contribute to accumulation of neurotoxic Aβ and subsequent synaptic loss, which is the strongest correlate of the extent of memory loss in AD. The activity of neprilysin (NEP, a potent Aβ-degrading enzyme, is decreased in the AD brain. Expression of HuD, an mRNA-binding protein important for synaptogenesis and neuronal plasticity, is also decreased in the AD brain. HuD is regulated by protein kinase Cε (PKCε, and we previously demonstrated that PKCε activation decreases Aβ levels. We hypothesized that PKCε acts through HuD to stabilize NEP mRNA, modulate its localization, and support NEP activity. Conversely, loss of PKCε-activated HuD in AD leads to decreased NEP activity and accumulation of Aβ. Here we show that HuD is associated with NEP mRNA in cultures of human SK-N-SH cells. Treatment with bryostatin, a PKCε-selective activator, enhanced NEP association with HuD and increased NEP mRNA stability. Activation of PKCε also increased NEP protein levels, increased NEP phosphorylation, and induced cell surface expression. In addition, specific PKCε activation directly stimulated NEP activity, leading to degradation of a monomeric form of Aβ peptide and decreased Aβ neuronal toxicity, as measured by cell viability. Bryostatin treatment also rescued Aβ-mediated inhibition of HuD-NEP mRNA binding, NEP protein expression, and NEP cell membrane translocation. These results suggest that PKCε activation reduces Aβ by up-regulating, via the mRNA-binding protein HuD, Aβ-degrading enzymes such as NEP. Thus, PKCε activation may have therapeutic efficacy for AD by reducing neurotoxic Aβ accumulation as well as having direct anti-apoptotic and synaptogenic effects.

  16. Topotecan triggers apoptosis in p53-deficient cells by forcing degradation of XIAP and survivin thereby activating caspase-3-mediated Bid cleavage.

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    Tomicic, Maja T; Christmann, Markus; Kaina, Bernd

    2010-01-01

    The topoisomerase I inhibitor topotecan (TPT) is used in the therapy of different tumors including high-grade gliomas. We previously showed that TPT-induced apoptosis depends on p53 with p53 wild-type (wt) cells being more resistant because of p53-controlled degradation of topoisomerase I. Here, we show that p53-deficient (p53(-/-)) fibroblasts undergo excessive mitochondrial apoptosis featuring H2AX phosphorylation, Bcl-x(L) decline, cytochrome c release, caspase-9/-3/-2 activation, and cleavage of Bid. In wt and apaf-1(-/-) cells, caspase-2 did not become activated and Bid was not cleaved. In addition, p53(-/-) cells cotreated with TPT and caspase-3 inhibitor showed neither caspase-2 activation nor Bid cleavage, implying that caspase-2 is processed downstream of the apoptosome by caspase-3. Although processing of caspase-9/-3 was similar in wt and p53(-/-) cells, only p53(-/-) cells displayed active caspase-3. This was due to the proteasomal degradation of X-chromosome-linked inhibitor of apoptosis (XIAP) and survivin that inhibits caspase-3 activity. Accordingly, TPT-induced apoptosis in wt cells was increased after XIAP/survivin knockdown. Silencing of Bid led to reduction of TPT-triggered apoptosis. Data obtained with mouse fibroblasts could be extended to human glioma cells. In U87MG (p53wt) cells cotreated with TPT and pifithrin-alpha, or transfected with p53-siRNA, caspase-2 and Bid were significantly cleaved and XIAP/survivin was degraded. Furthermore, the knockdown of XIAP and survivin led to increased TPT-triggered apoptosis. Overall, the data show that p53-deficient/depleted cells are hypersensitive to TPT because they down-regulate XIAP and survivin, and thus amplify the intrinsic apoptotic pathway via caspase-3-mediated Bid cleavage. Therefore, in gliomas harboring wild-type p53, TPT-based therapy might be improved by targeted down-regulation of XIAP and survivin.

  17. CD82 suppresses CD44 alternative splicing-dependent melanoma metastasis by mediating U2AF2 ubiquitination and degradation.

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    Zhang, Pu; Feng, Shan; Liu, Gentao; Wang, Heyong; Fu, Ailing; Zhu, Huifeng; Ren, Qiao; Wang, Bochu; Xu, Xingran; Bai, Huiyuan; Dong, Cheng

    2016-09-22

    Melanoma is one of the most lethal forms of skin cancer because of its early metastatic spread. The variant form of CD44 (CD44v), a cell surface glycoprotein, is highly expressed on metastatic melanoma. The mechanisms of regulation of CD44 alternative splicing in melanoma and its pathogenic contributions are so far poorly understood. Here, we investigated the expression level of CD44 in a large set of melanocytic lesions at different stages. We found that the expression of CD44v8-10 and a splicing factor, U2AF2, is significantly increased during melanoma progression, whereas CD82/KAI1, a tetraspanin family of tumor suppressor, is reduced in metastatic melanoma. CD44v8-10 and U2AF2 expression levels, which are negatively correlated with CD82 levels, are markedly elevated in primary melanoma compared with dysplastic nevi and further increased in metastatic melanoma. We also showed that patients with higher CD44v8-10 and U2AF2 expression levels tended to have shorter survival. By using both in vivo and in vitro assays, we demonstrated that CD82 inhibits the production of CD44v8-10 on melanoma. Mechanistically, U2AF2 is a downstream target of CD82 and in malignant melanoma facilitates CD44v8-10 alternative splicing. U2AF2-mediated CD44 isoform switch is required for melanoma migration in vitro and lung and liver metastasis in vivo. Notably, overexpression of CD82 suppresses U2AF2 activity by inducing U2AF2 ubiquitination. In addition, our data suggested that enhancement of melanoma migration by U2AF2-dependent CD44v8-10 splicing is mediated by Src/focal adhesion kinase/RhoA activation and formation of stress fibers, as well as CD44-E-selectin binding reinforcement. These findings uncovered a hitherto unappreciated function of CD82 in severing the linkage between U2AF2-mediated CD44 alternative splicing and cancer aggressiveness, with potential prognostic and therapeutic implications in melanoma.

  18. Dietary apigenin potentiates the inhibitory effect of interferon-α on cancer cell viability through inhibition of 26S proteasome-mediated interferon receptor degradation

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    Sheng Li

    2016-06-01

    Full Text Available Background: Type I interferons (IFN-α/β have broad and potent immunoregulatory and antiproliferative activities. However, it is still known whether the dietary flavonoids exhibit their antiviral and anticancer properties by modulating the function of type I IFNs. Objective: This study aimed at determining the role of apigenin, a dietary plant flavonoid abundant in common fruits and vegetables, on the type I IFN-mediated inhibition of cancer cell viability. Design: Inhibitory effect of apigenin on human 26S proteasome, a known negative regulator of type I IFN signaling, was evaluated in vitro. Molecular docking was conducted to know the interaction between apigenin and subunits of 26S proteasome. Effects of apigenin on JAK/STAT pathway, 26S proteasome-mediated interferon receptor stability, and cancer cells viability were also investigated. Results: Apigenin was identified to be a potent inhibitor of human 26S proteasome in a cell-based assay. Apigenin inhibited the chymotrypsin-like, caspase-like, and trypsin-like activities of the human 26S proteasome and increased the ubiquitination of endogenous proteins in cells. Results from computational modeling of the potential interactions of apigenin with the chymotrypsin site (β5 subunit, caspase site (β1 subunit, and trypsin site (β2 subunit of the proteasome were consistent with the observed proteasome inhibitory activity. Apigenin enhanced the phosphorylation of signal transducer and activator of transcription proteins (STAT1 and STAT2 and promoted the endogenous IFN-α-regulated gene expression. Apigenin inhibited the IFN-α-stimulated ubiquitination and degradation of type I interferon receptor 1 (IFNAR1. Apigenin also sensitized the inhibitory effect of IFN-α on viability of cervical carcinoma HeLa cells. Conclusion: These results suggest that apigenin potentiates the inhibitory effect of IFN-α on cancer cell viability by activating JAK/STAT signaling pathway through inhibition of 26S

  19. SCFSLF-mediated cytosolic degradation of S-RNase is required for cross-pollen compatibility in S-RNase-based self-incompatibility in Petunia hybrida

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    Yongbiao eXue

    2014-07-01

    Full Text Available Many flowering plants adopt self-incompatibility (SI to maintain their genetic diversity. In species of Solanaceae, Plantaginaceae and Rosaceae, SI is genetically controlled by a single S-locus with multiple haplotypes. The S-locus has been shown to encode S-RNases expressed in pistil and multiple SLF (S-locus F-box proteins in pollen controlling the female and male specificity of SI, respectively. S-RNases appear to function as a cytotoxin to reject self-pollen. In addition, SLFs have been shown to form SCF (SKP1/Cullin1/F-box complexes to serve as putative E3 ubiquitin ligase to interact with S-RNases. Previously, two different mechanisms, the S-RNase degradation and the S-RNase compartmentalization, have been proposed as the restriction mechanisms of S-RNase cytotoxicity allowing compatible pollination. In this study, we have provided several lines of evidence in support of the S-RNase degradation mechanism by a combination of cellular, biochemical and molecular biology approaches. First, both immunogold labeling and subcellular fractionation assays showed that two key pollen SI factors, PhSLF-S3L and PhSSK1 (SLF-interacting SKP1-like1 from Petunia hybrida, a Solanaceous species, are co-localized in cytosols of both pollen grains and tubes. Second, PhS3L-RNases are mainly detected in the cytosols of both self and non-self pollen tubes after pollination. Third, we found that both PhS3-RNases and PhS3L-RNases directly interact with PhSLF-S3L by yeast two-hybrid and co-immunoprecipitation assays. Fourth, S-RNases are specifically degraded in compatible pollen tubes by non-self SLF action. Taken together, our results demonstrate that SCFSLF-mediated non-self S-RNase degradation occurs in the cytosol of pollen tube through the ubiquitin/26S proteasome system serving as the major mechanism to neutralize S-RNase cytotoxicity during compatible pollination in P. hybrida.

  20. Necdin enhances myoblasts survival by facilitating the degradation of the mediator of apoptosis CCAR1/CARP1.

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    Stephanie François

    Full Text Available Regeneration of muscle fibers, lost during pathological muscle degeneration or after injuries, is sustained by the production of new myofibers by means of the satellite cells. Survival of the satellite cells is a critical requirement for efficient muscle reconstitution. Necdin, a member of the MAGE proteins family, is expressed in satellite cell-derived myogenic precursors during perinatal growth and in the adult upon activation during muscle regeneration, where it plays an important role both in myoblast differentiation and survival. We show here that necdin exerts its pro-survival activity by counteracting the action of the pro-apoptotic protein Cell Cycle Apoptosis Regulatory Protein (CCAR1/CARP1 that we have identified as a new molecular interactor of necdin by two-hybrid screening. Necdin is responsible for the maintenance of CCAR1 protein levels, by implementing its ubiquitination and degradation through the proteasome. Taken together, these data shed new light on the molecular mechanism of necdin anti-apoptotic activity in myogenesis.

  1. Cathepsin B is up-regulated and mediates extracellular matrix degradation in trabecular meshwork cells following phagocytic challenge.

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    Kristine Porter

    Full Text Available Cells in the trabecular meshwork (TM, a tissue responsible for draining aqueous humor out of the eye, are known to be highly phagocytic. Phagocytic activity in TM cells is thought to play an important role in outflow pathway physiology. However, the molecular mechanisms triggered by phagocytosis in TM cells are unknown. Here we investigated the effects of chronic phagocytic stress on lysosomal function using different phagocytic ligands (E. coli, carboxylated beads, collagen I-coated beads, and pigment. Lysotracker red co-localization and electron micrographs showed the maturation of E. coli- and collagen I-coated beads-containing phagosomes into phagolysosomes. Maturation of phagosomes into phagolysosomes was not observed with carboxylated beads or pigment particles. In addition, phagocytosis of E. coli and collagen I-coated beads led to increased lysosomal mass, and the specific up-regulation and activity of cathepsin B (CTSB. Higher levels of membrane-bound and secreted CTSB were also detected. Moreover, in vivo zymography showed the intralysosomal degradation of ECM components associated with active CTSB, as well as an overall increased gelatinolytic activity in phagocytically challenged TM cells. This increased gelatinolytic activity with phagocytosis was partially blocked with an intracellular CTSB inhibitor. Altogether, these results suggest a potential role of phagocytosis in outflow pathway tissue homeostasis through the up-regulation and/or proteolytic activation of extracellular matrix remodeling genes.

  2. β-Transducin Repeat-containing Protein 1 (β-TrCP1)-mediated Silencing Mediator of Retinoic Acid and Thyroid Hormone Receptor (SMRT) Protein Degradation Promotes Tumor Necrosis Factor α (TNFα)-induced Inflammatory Gene Expression*

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    Hsu, Kuo-Sheng; Kao, Hung-Ying

    2013-01-01

    Cytokine modulation of the endothelium is considered an important contributor to the inflammation response. TNFα is an early response gene during the initiation of inflammation. However, the detailed mechanism by which TNFα induces proinflammatory gene expression is not completely understood. In this report, we demonstrate that silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) represses the expression of a subset of TNFα target genes in human umbilical vein endothelial cells. Upon TNFα stimulation, we observed an increase in the E3 ubiquitin ligase β-TrCP1 and a decrease in SMRT protein levels. We show that β-TrCP1 interacts with SMRT in a phosphorylation-independent manner and cooperates with the E2 ubiquitin-conjugating enzyme E2D2 to promote ubiquitination-dependent SMRT degradation. Knockdown of β-TrCP1 increases SMRT protein accumulation, increases SMRT association with its targeted promoters, and decreases SMRT target gene expression. Taken together, our results support a model in which TNFα-induced β-TrCP1 accumulation promotes SMRT degradation and the subsequent induction of proinflammatory gene expression. PMID:23861398

  3. β-Transducin repeat-containing protein 1 (β-TrCP1)-mediated silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) protein degradation promotes tumor necrosis factor α (TNFα)-induced inflammatory gene expression.

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    Hsu, Kuo-Sheng; Kao, Hung-Ying

    2013-08-30

    Cytokine modulation of the endothelium is considered an important contributor to the inflammation response. TNFα is an early response gene during the initiation of inflammation. However, the detailed mechanism by which TNFα induces proinflammatory gene expression is not completely understood. In this report, we demonstrate that silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) represses the expression of a subset of TNFα target genes in human umbilical vein endothelial cells. Upon TNFα stimulation, we observed an increase in the E3 ubiquitin ligase β-TrCP1 and a decrease in SMRT protein levels. We show that β-TrCP1 interacts with SMRT in a phosphorylation-independent manner and cooperates with the E2 ubiquitin-conjugating enzyme E2D2 to promote ubiquitination-dependent SMRT degradation. Knockdown of β-TrCP1 increases SMRT protein accumulation, increases SMRT association with its targeted promoters, and decreases SMRT target gene expression. Taken together, our results support a model in which TNFα-induced β-TrCP1 accumulation promotes SMRT degradation and the subsequent induction of proinflammatory gene expression.

  4. The degradation of airway tight junction protein under acidic conditions is probably mediated by transient receptor potential vanilloid 1 receptor

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    Xu, Rui; Li, Qi; Zhou, Jia; Zhou, Xiang-dong; Perelman, Juliy M.; Kolosov, Victor P.

    2013-01-01

    Acidic airway microenvironment is one of the representative pathophysiological features of chronic inflammatory respiratory diseases. Epithelial barrier function is maintained by TJs (tight junctions), which act as the first physical barrier against the inhaled substances and pathogens of airway. As previous studies described, acid stress caused impaired epithelial barriers and led the hyperpermeability of epithelium. However, the specific mechanism is still unclear. We have showed previously the existence of TRPV (transient receptor potential vanilloid) 1 channel in airway epithelium, as well as its activation by acidic stress in 16HBE cells. In this study, we explored the acidic stress on airway barrier function and TJ proteins in vitro with 16HBE cell lines. Airway epithelial barrier function was determined by measuring by TER (trans-epithelial electrical resistance). TJ-related protein [claudin-1, claudin-3, claudin-4, claudin-5, claudin-7 and ZO-1 (zonula occluden 1)] expression was examined by western blotting of insoluble fractions of cell extraction. The localization of TJ proteins were visualized by immunofluorescent staining. Interestingly, stimulation by pH 6.0 for 8 h slightly increased the epithelial resistance in 16HBE cells insignificantly. However, higher concentration of hydrochloric acid (lower than pH 5.0) did reduce the airway epithelial TER of 16HBE cells. The decline of epithelial barrier function induced by acidic stress exhibited a TRPV1-[Ca2+]i-dependent pathway. Of the TJ proteins, claudin-3 and claudin-4 seemed to be sensitive to acidic stress. The degradation of claudin-3 and claudin-4 induced by acidic stress could be attenuated by the specific TRPV1 blocker or intracellular Ca2+ chelator BAPTA/AM [1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid tetrakis(acetoxymethyl ester)]. PMID:24073800

  5. Effect of reaction conditions on methyl red degradation mediated by boron and nitrogen doped TiO2

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    Galenda, A.; Crociani, L.; Habra, N. El; Favaro, M.; Natile, M. M.; Rossetto, G.

    2014-09-01

    Nowadays the employment of renewable and sustainable energy sources, and solar light as main option, becomes an urgent need. Photocatalytic processes received great attention in wastewater treatment due to their cheapness, environmental compatibility and optimal performances. Despite the general low selectivity of the photocatalysts, an accurate optimisation of the operational parameters needs to be carried out in order to maximise the process yield. Because of this reason, the present contribution aims to deepen either the knowledge in boron and/or nitrogen doped TiO2-based systems and their employment in methyl red removal from aqueous solutions. The samples were obtained by coprecipitation and characterised by XRD, SEM, BET specific surface area, UV-vis and XPS techniques. The catalytic activity was for the first time carefully evaluated with respect to methyl red photodegradation in different conditions as a function of working pH, counter-ions and pre-adsorption time. An ad-hoc study was performed on the importance of the pre-adsorption of the dye, suggesting that an extended adsorption is useless for the catalyst photoactivity, while a partial coverage is preferable. The photocatalytic tests demonstrate the positive influence of boron doping in photo-activated reactions and the great importance of the operational parameters with respect to the simple methyl red bleaching rather than the overall pollutant mineralisation. It is proved, indeed, that different working pH, acidifying means and substrate pre-adsorption time can enhance or limit the catalyst performances with respect to the complete pollutant degradation rather than its partial breakage.

  6. Steviol reduces MDCK Cyst formation and growth by inhibiting CFTR channel activity and promoting proteasome-mediated CFTR degradation.

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    Chaowalit Yuajit

    Full Text Available Cyst enlargement in polycystic kidney disease (PKD involves cAMP-activated proliferation of cyst-lining epithelial cells and transepithelial fluid secretion into the cyst lumen via cystic fibrosis transmembrane conductance regulator (CFTR chloride channel. This study aimed to investigate an inhibitory effect and detailed mechanisms of steviol and its derivatives on cyst growth using a cyst model in Madin-Darby canine kidney (MDCK cells. Among 4 steviol-related compounds tested, steviol was found to be the most potent at inhibiting MDCK cyst growth. Steviol inhibition of cyst growth was dose-dependent; steviol (100 microM reversibly inhibited cyst formation and cyst growth by 72.53.6% and 38.2±8.5%, respectively. Steviol at doses up to 200 microM had no effect on MDCK cell viability, proliferation and apoptosis. However, steviol acutely inhibited forskolin-stimulated apical chloride current in MDCK epithelia, measured with the Ussing chamber technique, in a dose-dependent manner. Prolonged treatment (24 h with steviol (100 microM also strongly inhibited forskolin-stimulated apical chloride current, in part by reducing CFTR protein expression in MDCK cells. Interestingly, proteasome inhibitor, MG-132, abolished the effect of steviol on CFTR protein expression. Immunofluorescence studies demonstrated that prolonged treatment (24 h with steviol (100 microM markedly reduced CFTR expression at the plasma membrane. Taken together, the data suggest that steviol retards MDCK cyst progression in two ways: first by directly inhibiting CFTR chloride channel activity and second by reducing CFTR expression, in part, by promoting proteasomal degradation of CFTR. Steviol and related compounds therefore represent drug candidates for treatment of polycystic kidney disease.

  7. Enhanced reductive degradation of methyl orange in a microbial fuel cell through cathode modification with redox mediators.

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    Liu, Rong-Hua; Sheng, Guo-Ping; Sun, Min; Zang, Guo-Long; Li, Wen-Wei; Tong, Zhong-Hua; Dong, Fang; Lam, Michael Hon-Wah; Yu, Han-Qing

    2011-01-01

    A model azo dye, methyl orange (MO), was reduced through in situ utilization of the electrons derived from the anaerobic conversion of organics in a microbial fuel cell (MFC). The MO reduction process could be described by a pseudo first-order kinetic model with a rate constant of 1.29 day(-1). Electrochemical impedance spectroscopic analysis shows that the cathode had a high polarization resistance, which could decrease the reaction rate and limit the electron transfer. To improve the MO reduction efficiency, the cathode was modified with redox mediators to enhance the electron transfer. After modification with thionine, the polarization resistance significantly decreased by over 50%. As a consequence, the MO decolorization rate increased by over 20%, and the power density was enhanced by over three times. Compared with thionine, anthraquinone-2, 6-disulfonate modified cathode has less positive effect on the MFC performance. These results indicate that the electrode modification with thionine is a useful approach to accelerate the electrochemical reactions. This work provides useful information about the key factors limiting the azo dye reduction in the MFC and how to improve such a process.

  8. The CCR4-NOT complex mediates deadenylation and degradation of stem cell mRNAs and promotes planarian stem cell differentiation.

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    Jordi Solana

    Full Text Available Post-transcriptional regulatory mechanisms are of fundamental importance to form robust genetic networks, but their roles in stem cell pluripotency remain poorly understood. Here, we use freshwater planarians as a model system to investigate this and uncover a role for CCR4-NOT mediated deadenylation of mRNAs in stem cell differentiation. Planarian adult stem cells, the so-called neoblasts, drive the almost unlimited regenerative capabilities of planarians and allow their ongoing homeostatic tissue turnover. While many genes have been demonstrated to be required for these processes, currently almost no mechanistic insight is available into their regulation. We show that knockdown of planarian Not1, the CCR4-NOT deadenylating complex scaffolding subunit, abrogates regeneration and normal homeostasis. This abrogation is primarily due to severe impairment of their differentiation potential. We describe a stem cell specific increase in the mRNA levels of key neoblast genes after Smed-not1 knock down, consistent with a role of the CCR4-NOT complex in degradation of neoblast mRNAs upon the onset of differentiation. We also observe a stem cell specific increase in the frequency of longer poly(A tails in these same mRNAs, showing that stem cells after Smed-not1 knock down fail to differentiate as they accumulate populations of transcripts with longer poly(A tails. As other transcripts are unaffected our data hint at a targeted regulation of these key stem cell mRNAs by post-transcriptional regulators such as RNA-binding proteins or microRNAs. Together, our results show that the CCR4-NOT complex is crucial for stem cell differentiation and controls stem cell-specific degradation of mRNAs, thus providing clear mechanistic insight into this aspect of neoblast biology.

  9. BPM-CUL3 E3 ligase modulates thermotolerance by facilitating negative regulatory domain-mediated degradation of DREB2A in Arabidopsis.

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    Morimoto, Kyoko; Ohama, Naohiko; Kidokoro, Satoshi; Mizoi, Junya; Takahashi, Fuminori; Todaka, Daisuke; Mogami, Junro; Sato, Hikaru; Qin, Feng; Kim, June-Sik; Fukao, Yoichiro; Fujiwara, Masayuki; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2017-10-03

    DEHYDRATION-RESPONSIVE ELEMENT BINDING PROTEIN 2A (DREB2A) acts as a key transcription factor in both drought and heat stress tolerance in Arabidopsis and induces the expression of many drought- and heat stress-inducible genes. Although DREB2A expression itself is induced by stress, the posttranslational regulation of DREB2A, including protein stabilization, is required for its transcriptional activity. The deletion of a 30-aa central region of DREB2A known as the negative regulatory domain (NRD) transforms DREB2A into a stable and constitutively active form referred to as DREB2A CA. However, the molecular basis of this stabilization and activation has remained unknown for a decade. Here we identified BTB/POZ AND MATH DOMAIN proteins (BPMs), substrate adaptors of the Cullin3 (CUL3)-based E3 ligase, as DREB2A-interacting proteins. We observed that DREB2A and BPMs interact in the nuclei, and that the NRD of DREB2A is sufficient for its interaction with BPMs. BPM-knockdown plants exhibited increased DREB2A accumulation and induction of DREB2A target genes under heat and drought stress conditions. Genetic analysis indicated that the depletion of BPM expression conferred enhanced thermotolerance via DREB2A stabilization. Thus, the BPM-CUL3 E3 ligase is likely the long-sought factor responsible for NRD-dependent DREB2A degradation. Through the negative regulation of DREB2A stability, BPMs modulate the heat stress response and prevent an adverse effect of excess DREB2A on plant growth. Furthermore, we found the BPM recognition motif in various transcription factors, implying a general contribution of BPM-mediated proteolysis to divergent cellular responses via an accelerated turnover of transcription factors.

  10. CeO2-TiO2 Photocatalyst: Ionic Liquid-Mediated Synthesis, Characterization, and Performance for Diisopropanolamine Visible Light Degradation

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    Jagath Retchahan Sivalingam

    2018-01-01

    Full Text Available CeO2-TiO2 photocatalyst with Ce:Ti molar ratio of 1:9 was synthesized via co-precipitation method in the presence of 1-ethyl-3-methyl imidazolium octylsulfate, [EMIM][OctSO4] (CeO2-TiO2-IL. The ionic liquid acts as a templating agent for particle growth. The CeO2-TiO2 and TiO2 photocatalysts were also synthesized without any ionic liquid for comparison. Calcination was conducted on the as-synthesized materials at 400˚C for 2 h. The photocatalysts were characterized using diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis, field emission scanning electron microscopy (FESEM, X-ray powder diffraction (XRD, and surface area and pore size analyzer (SAP. The presence of CeO2 has changed the optical property of TiO2. It has extended the absorption edge of TiO2 from UV to visible region. The calculated band gap energy decreased from 2.82 eV (TiO2 to 2.30 eV (CeO2-TiO2-IL. The FESEM morphology showed that samples forms aggregates and the surface smoothens when ionic liquid was added. The average crystallite size of TiO2, CeO2-TiO2, and CeO2-TiO2-IL were 20.8 nm, 5.5 nm, and 4 nm. In terms of performance, photodegradation of 1000 ppm of diisopropanolamine (DIPA was conducted in the presence of hydrogen peroxide (H2O2 and visible light irradiation which was provided by a 500 W halogen lamp. The best performance was displayed by CeO2-TiO2-IL calcined at 400˚C. It was able to remove 82.0% DIPA and 54.8% COD after 6 h reaction.  Copyright © 2018 BCREC Group. All rights reserved Received: 26th July 2017; Revised: 22nd October 2017; Accepted: 29th October 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Sivalingam, J.R., Kait, C.F., Wilfred, C.D. (2018. CeO2-TiO2 Photocatalyst: Ionic Liquid-Mediated Synthesis, Characterization, and Performance for Diisopropanolamine Visible Light Degradation. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1: 170-178 (doi:10.9767/bcrec.13.1.1396.170-178

  11. Detoxification of azinophos methyl using gamma radiation mediated advance oxidation process and investigation of degradation products by HPLC and GC-MS

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Sadiq Sadaf; Riaz Muhammad [Chromatography Lab., Islamabad (Pakistan). Chemistry Division, PINSTECH, P.P. Nilore

    2014-10-01

    Gamma radiolytic degradation of azinophos-methyl was studied in water and methanol separately, using {sup 60}Co as a radiation source under varied experimental conditions. Solution of azinophos-methyl was prepared in pure methanol at concentration of 50 μg ml{sup -1}, irradiated at gamma dose of 1 to 7 kGy and high performance liquid chromatography (HPLC) coupled with diode array detector was used to monitor the extent of degradation along with numbers of degradation products. At dose of 7 kGy ≥ 99% of azinophos-methyl was degraded. The degradation occurred by interaction of CH{sub 3}O {sup x} and H {sup x} radicals generated by the radiolysis of high purity methanol while in water by {sup x} OH radical. The degradation in water was increased by 30% than in methanol due the high oxidation potential of {sup x} OH while keeping the gamma ray dose constant at 3 kGy. The generated degradation products were identified using GC-MS and their possible transformation pathways are proposed. It is suggested that use of ionization radiations can be an effective and efficient tool for the removal of organophosphate pesticides in waste water.

  12. Poly(3-Hydroxybutyrate) Degradation in Ralstonia eutropha H16 Is Mediated Stereoselectively to (S)-3-Hydroxybutyryl Coenzyme A (CoA) via Crotonyl-CoA

    Science.gov (United States)

    Eggers, Jessica

    2013-01-01

    Degradation of poly(3-hydroxybutyrate) (PHB) by the thiolytic activity of the PHB depolymerase PhaZ1 from Ralstonia eutropha H16 was analyzed in the presence of different phasins. An Escherichia coli strain was constructed that harbored the genes for PHB synthesis (phaCAB), the phasin PhaP1, and the PHB depolymerase PhaZ1. PHB was isolated in the native form (nPHB) from this recombinant E. coli strain, and the in vitro degradation of the polyester was examined. Degradation resulted in the formation of the expected 3-hydroxybutyryl coenzyme A (3HB-CoA) and in the formation of a second product, which occurred in significantly higher concentrations than 3HB-CoA. This second product was identified by liquid chromatography mass spectrometry (LC-MS) as crotonyl-CoA. Replacement of PhaP1 by PhaP2 or PhaP4 resulted in a lower degradation rate, whereas the absence of the phasins prevented the degradation of nPHB by the PHB depolymerase PhaZ1 almost completely. In addition, the in vitro degradation of nPHB granules isolated from R. eutropha H16 (wild type) and from the R. eutropha ΔphaP1 and ΔphaP1-4 deletion mutants was examined. In contrast to the results obtained with nPHB granules isolated from E. coli, degradation of nPHB granules isolated from the wild type of R. eutropha yielded high concentrations of 3HB-CoA and low concentrations of crotonyl-CoA. The degradation of nPHB granules isolated from the ΔphaP1 and ΔphaP1-4 deletion mutants of R. eutropha was significantly reduced in comparison to that of nPHB granules isolated from wild-type R. eutropha. Stereochemical analyses of 3HB-CoA revealed that the (R) stereoisomer was collected after degradation of granules isolated from E. coli, whereas the (S) stereoisomer was collected after degradation of granules isolated from R. eutropha. Based on these results, a newly observed mechanism in the degradation pathway for PHB in R. eutropha is proposed which is connected by crotonyl-CoA to the β-oxidation cycle. According

  13. Complementary roles of intracellular and pericellular collagen degradation pathways in vivo

    DEFF Research Database (Denmark)

    Wagenaar-Miller, Rebecca A; Engelholm, Lars H; Gavard, Julie

    2007-01-01

    Collagen degradation is essential for cell migration, proliferation, and differentiation. Two key turnover pathways have been described for collagen: intracellular cathepsin-mediated degradation and pericellular collagenase-mediated degradation. However, the functional relationship between these ...

  14. Local IL-13 gene transfer prior to immune-complex arthritis inhibits chondrocyte death and matrix-metalloproteinase-mediated cartilage matrix degradation despite enhanced joint inflammation.

    NARCIS (Netherlands)

    Nabbe, K.C.A.M.; Lent, P.L.E.M. van; Holthuysen, A.E.M.; Sloetjes, A.W.; Koch, A.E.; Radstake, T.R.D.J.; Berg, W.B. van den

    2005-01-01

    During immune-complex-mediated arthritis (ICA), severe cartilage destruction is mediated by Fcgamma receptors (FcgammaRs) (mainly FcgammaRI), cytokines (e.g. IL-1), and enzymes (matrix metalloproteinases (MMPs)). IL-13, a T helper 2 (Th2) cytokine abundantly found in synovial fluid of patients with

  15. Ethylene-Induced Stabilization of ETHYLENE INSENSITIVE3 and EIN3-LIKE1 Is Mediated by Proteasomal Degradation of EIN3 Binding F-Box 1 and 2 That Requires EIN2 in Arabidopsis[C][W

    Science.gov (United States)

    An, Fengying; Zhao, Qiong; Ji, Yusi; Li, Wenyang; Jiang, Zhiqiang; Yu, Xiangchun; Zhang, Chen; Han, Ying; He, Wenrong; Liu, Yidong; Zhang, Shuqun; Ecker, Joseph R.; Guo, Hongwei

    2010-01-01

    Plant responses to ethylene are mediated by regulation of EBF1/2-dependent degradation of the ETHYLENE INSENSITIVE3 (EIN3) transcription factor. Here, we report that the level of EIL1 protein is upregulated by ethylene through an EBF1/2-dependent pathway. Genetic analysis revealed that EIL1 and EIN3 cooperatively but differentially regulate a wide array of ethylene responses, with EIL1 mainly inhibiting leaf expansion and stem elongation in adult plants and EIN3 largely regulating a multitude of ethylene responses in seedlings. When EBF1 and EBF2 are disrupted, EIL1 and EIN3 constitutively accumulate in the nucleus and remain unresponsive to exogenous ethylene application. Further study revealed that the levels of EBF1 and EBF2 proteins are downregulated by ethylene and upregulated by silver ion and MG132, suggesting that ethylene stabilizes EIN3/EIL1 by promoting EBF1 and EBF2 proteasomal degradation. Also, we found that EIN2 is indispensable for mediating ethylene-induced EIN3/EIL1 accumulation and EBF1/2 degradation, whereas MKK9 is not required for ethylene signal transduction, contrary to a previous report. Together, our studies demonstrate that ethylene similarly regulates EIN3 and EIL1, the two master transcription factors coordinating myriad ethylene responses, and clarify that EIN2 but not MKK9 is required for ethylene-induced EIN3/EIL1 stabilization. Our results also reveal that EBF1 and EBF2 act as essential ethylene signal transducers that by themselves are subject to proteasomal degradation. PMID:20647342

  16. Thiomersal photo-degradation with visible light mediated by graphene quantum dots: Indirect quantification using optical multipath mercury cold-vapor absorption spectrophotometry

    Science.gov (United States)

    Miranda-Andrades, Jarol R.; Khan, Sarzamin; Toloza, Carlos A. T.; Romani, Eric C.; Freire Júnior, Fernando L.; Aucelio, Ricardo Q.

    2017-12-01

    Thiomersal is employed as preservative in vaccines, cosmetic and pharmaceutical products due to its capacity to inhibit bacterial growth. Thiomersal contains 49.55% of mercury in its composition and its highly toxic ethylmercury degradation product has been linked to neurological disorders. The photo-degradation of thiomersal has been achieved by visible light using graphene quantum dots as catalysts. The generated mercury cold vapor (using adjusted experimental conditions) was detected by multipath atomic absorption spectrometry allowing the quantification of thiomersal at values as low as 20 ng L- 1 even in complex samples as aqueous effluents of pharmaceutical industry and urine. A kinetic study (pseudo-first order with k = 0.11 min- 1) and insights on the photo-degradation process are presented.

  17. Novel function of the endoplasmic reticulum degradation-enhancing α-mannosidase-like proteins in the human hepatitis B virus life cycle, mediated by the middle envelope protein.

    Science.gov (United States)

    Lazar, Catalin; Uta, Mihaela; Petrescu, Stefana Maria; Branza-Nichita, Norica

    2017-02-01

    Cells replicating the human hepatitis B virus (HBV) express high levels of degradation-enhancing α-mannosidase-like proteins (EDEMs), a family of proteins involved in the endoplasmic reticulum associated degradation, one of the pathways activated during the unfolded protein response. Owing to their α-1,2 mannosidase activity, the EDEM1-3 proteins are able to process the N-linked glycans of misfolded or incompletely folded proteins, providing the recognition signal for their subsequent degradation. The HBV small (S), medium (M), and large (L) surface proteins bear an N-linked glycosylation site in the common S domain that is partially occupied in all proteins. The M protein contains an additional site in its preS2 domain, which is always functional. Here, we report that these oligosaccharides are processed by EDEMs, more efficiently by EDEM3, which induces degradation of L and S proteins, accompanied by a reduction of subviral particles production. In striking contrast, M not only is spared from degradation but its trafficking is also accelerated leading to an improved secretion. This unusual behavior of the M protein requires strictly the mannose trimming of the preS2 N-linked glycan. Furthermore, we show that HBV secretion is significantly inhibited under strong endoplasmic reticulum stress conditions when M expression is prevented by mutagenesis of the viral genome. These observations unfold unique properties of the M protein in the HBV life cycle during unfolded protein response and point to alternative mechanisms employed by EDEMs to alleviate this stress in case of necessity by promoting glycoprotein trafficking rather than degradation. © 2016 John Wiley & Sons Ltd.

  18. Hydrothermal Carbon-Mediated Fenton-Like Reaction Mechanism in the Degradation of Alachlor: Direct Electron Transfer from Hydrothermal Carbon to Fe(III).

    Science.gov (United States)

    Qin, Yaxin; Zhang, Lizhi; An, Taicheng

    2017-05-24

    As Fenton systems suffer from the undesirable Fe(III)/Fe(II) cycle, great efforts were made to realize the effective reduction of Fe(III) to Fe(II). The effects of hydrothermal carbon (HTC) on the Fe(III)/H2O2 Fenton-like reaction and the subsequent degradation of alachlor in water was systematically investigated, and the results indicated that HTC could enhance alachlor degradation in Fe(III)/H2O2 by promoting the Fe(III)/Fe(II) cycle via electron transfer from HTC to Fe(III) ions. The apparent alachlor degradation rate constant in the HTC-G/Fe(III)/H2O2 system (7.02 × 10(-2) min(-1)) was about 3 times higher than that in the Fe(III)/H2O2 system (2.25 × 10(-2) min(-1)). The electron spin resonance spectra analysis revealed that HTC consists of abundant carbon-centered persistent free radicals to act as the electron donor. Meanwhile, the hydroxyl groups on the surface of HTC also played an important role in the enhanced alachlor degradation because the decrease in the surface hydroxyl groups on HTC significantly decreased the degradation of alachlor. On the basis of these results, an Fe(III) complex with surface hydroxyl groups on HTC was proposed to favor the electron transfer from the hydroxyl groups to Fe(III), and then, the simultaneously produced Fe(II) could accelerate the catalytic decomposition of H2O2 to facilitate alachlor degradation. These findings shed new light on the possible roles of carbon materials in a natural aquatic environment and provide a new pathway for environmental pollutant control and remediation of organic contaminants by HTC.

  19. Degradation of tissue-type plasminogen activator by human monocyte- derived macrophages is mediated by the mannose receptor and by the low- density lipoprotein receptor-related protein

    NARCIS (Netherlands)

    Noorman, F.; Braat, E.A.M.; Rijken, D.C.

    1995-01-01

    The balance of tissue-type plasminogen activator (t-PA) production and degradation determines its concentration in blood and tissues. Disturbance of this balance may result in either increased or decreased proteolysis. In the present study, we identified the receptor systems involved in the

  20. The novel complement inhibitor human CUB and Sushi multiple domains 1 (CSMD1) protein promotes factor I-mediated degradation of C4b and C3b and inhibits the membrane attack complex assembly.

    Science.gov (United States)

    Escudero-Esparza, Astrid; Kalchishkova, Nikolina; Kurbasic, Emila; Jiang, Wen G; Blom, Anna M

    2013-12-01

    CUB and Sushi multiple domains 1 (CSMD1) is a transmembrane protein containing 15 consecutive complement control protein (CCP) domains, which are characteristic for complement inhibitors. We expressed a membrane-bound fragment of human CSMD1 composed of the 15 C-terminal CCP domains and demonstrated that it inhibits deposition of C3b by the classical pathway on the surface of Chinese hamster ovary cells by 70% at 6% serum and of C9 (component of membrane attack complex) by 90% at 1.25% serum. Furthermore, this fragment of CSMD1 served as a cofactor to factor I-mediated degradation of C3b. In all functional assays performed, well-characterized complement inhibitors were used as positive controls, whereas Coxsackie adenovirus receptor, a protein with no effect on complement, was a negative control. Moreover, attenuation of expression in human T47 breast cancer cells that express endogenous CSMD1 significantly increased C3b deposition on these cells by 45% at 8% serum compared with that for the controls. Furthermore, by expressing a soluble 17-21 CCP fragment of CSMD1, we found that CSMD1 inhibits complement by promoting factor I-mediated C4b/C3b degradation and inhibition of MAC assembly at the level of C7. Our results revealed a novel complement inhibitor for the classical and lectin pathways.

  1. AtSKIP18 and AtSKIP31, F-box subunits of the SCF E3 ubiquitin ligase complex, mediate the degradation of 14-3-3 proteins in Arabidopsis.

    Science.gov (United States)

    Hong, Jong-Pil; Adams, Eri; Yanagawa, Yuki; Matsui, Minami; Shin, Ryoung

    2017-03-25

    14-3-3 proteins regulate numerous cellular processes through interaction with their target proteins in a phosphorylation dependent manner. Although proteins that are regulated by 14-3-3s have been studied, the regulatory mechanism of 14-3-3s is poorly understood. In the present study, F-box proteins, a component of Skp1-Cullin-F-box E3 ubiquitin ligase, were identified as 14-3-3 targets using yeast two-hybrid screening. Among them, AtSKIP18 and AtSKIP31, were shown to mediate the degradation of Arabidopsis 14-3-3s. Mutational analyses of AtSKIP18 and AtSKIP31 indicated that the phosphorylation of AtSKIPs is critical for interaction and degradation of 14-3-3s. The loss-of-function mutation in AtSKIP31 resulted in enhanced primary root growth under nitrogen deficient conditions. These findings suggest that AtSKIP31 regulates the primary root growth in nitrogen deficiency via degrading 14-3-3s. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Cathepsin H-Mediated Degradation of HDAC4 for Matrix Metalloproteinase Expression in Hepatic Stellate Cells: Implications of Epigenetic Suppression of Matrix Metalloproteinases in Fibrosis through Stabilization of Class IIa Histone Deacetylases.

    Science.gov (United States)

    Yang, Zemin; Liu, Yu; Qin, Lan; Wu, Pengfei; Xia, Zanxian; Luo, Mei; Zeng, Yilan; Tsukamoto, Hidekazu; Ju, Zongyun; Su, Danmei; Kang, Han; Xiao, Zhixiong; Zheng, Sujun; Duan, Zhongping; Hu, Richard; Wang, Qiang; Pandol, Stephen J; Han, Yuan-Ping

    2017-04-01

    In three-dimensional extracellular matrix, mesenchymal cells including hepatic stellate cells (HSCs) gain the ability to express matrix metalloproteinases (MMPs) on injury signals. In contrast, in myofibroblastic HSCs in fibrotic liver, many MMP genes are silenced into an epigenetically nonpermissive state. The mechanism by which the three-dimensional extracellular matrix confers the MMP genes into an epigenetically permissive state has not been well characterized. In continuation of previous work, we show here that the up-regulation of MMP genes is mediated through degradation of class IIa histone deacetylases (HDACs) by certain cysteine cathepsins (Cts). In three-dimensional extracellular matrix culture, CtsH, among other cysteine cathepsins, was up-regulated and localized as puncta in the nuclear and cytoplasmic compartments in a complex with HDAC4 for its degradation. Conversely, along with HSC trans-differentiation, CtsH and CtsL were progressively down-regulated, whereas HDAC4 was concurrently stabilized. The inhibition of cysteine cathepsins by specific proteinase inhibitors or chloroquine, which raises cellular pH, restored HDAC4. Recombinant CtsH could break down HDAC4 in the transfected cells and in vitro at acidic pH. In human cirrhotic liver, activated HSCs express high levels of class IIa HDACs but little CtsH. We propose that cysteine cathepsin-mediated degradation of class IIa HDACs plays a key role in the modulation of MMP expression/suppression and HSC functions in tissue injury and fibrosis. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  3. Tissue-nonspecific alkaline phosphatase with an Asp(289)-->Val mutation fails to reach the cell surface and undergoes proteasome-mediated degradation.

    Science.gov (United States)

    Ishida, Yoko; Komaru, Keiichi; Ito, Masahiro; Amaya, Yoshihiro; Kohno, Shoji; Oda, Kimimitsu

    2003-07-01

    A missense mutation in the gene of tissue-nonspecific alkaline phosphatase, which replaces aspartic acid at position 289 with valine [TNSALP (D289V)], was reported in a lethal hypophosphatasia patient [Taillandier, A. et al. (1999) Hum. Mut. 13, 171-172]. To define the molecular defects of TNSALP (D289V), this mutant protein in transiently transfected COS-1 cells was analyzed biochemically and morphologically. TNSALP (D289V) exhibited no alkaline phosphatase activity and mainly formed a disulfide-linked high molecular mass aggregate. Cell-surface biotinylation, digestion with phosphatidylinositol-specific phospholipase C and an immunofluorescence study showed that the mutant protein failed to appear on the cell surface and was accumulated intracellularly. In agreement with this, pulse/chase experiments demonstrated that TNSALP (D289V) remained endo-beta-N-acetyl- glucosaminidase H-sensitive throughout the chase and was eventually degraded, indicating that the mutant protein is unable to reach the medial-Golgi. Proteasome inhibitors strongly blocked the degradation of TNSALP (D289V), and furthermore the mutant protein was found to be ubiquitinated. Besides, another naturally occurring TNSALP with a Glu(218)-->Gly mutation was also found to be polyubiquitinated and degraded in the proteasome. Since the acidic amino acids at positions 218 and 289 of TNSALP are thought to be directly involved in the Ca(2+) coordination, these results suggest the critical importance of calcium binding in post-translational folding and assembly of the TNSALP molecule.

  4. Effects of different omega-3 sources, fish oil, krill oil, and green-lipped mussel against cytokine-mediated canine cartilage degradation.

    Science.gov (United States)

    Buddhachat, Kittisak; Siengdee, Puntita; Chomdej, Siriwadee; Soontornvipart, Kumpanart; Nganvongpanit, Korakot

    2017-05-01

    Our purpose was to evaluate the protective effect of three marine omega-3 sources, fish oil (FO), krill oil (KO), and green-lipped mussel (GLM) against cartilage degradation. Canine cartilage explants were stimulated with either 10 ng/mL interleukin-1β (IL-1β) or IL-1β/oncostatin M (10 ng/mL each) and then treated with various concentrations of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA; 3 and 30 μg/mL), FO, KO, or GLM (250, 500, and 1000 μg/mL) for 28 days. Gene expression was then investigated in primary canine chondrocytes. Our results showed that DHA and EPA as well as omega-3 sources could suppress matrix degradation in cytokine-induced cartilage explants by significantly reducing the increase of sulfated glycosaminoglycans (s-GAGs) and preserving uronic acid and hydroxyproline content (except GLM). These agents were not able to reduce IL-1β-induced IL1B and TNFA expression but were able to down-regulate the expression of the catabolic genes MMP1, MMP3, and MMP13 and up-regulate the anabolic genes AGG and COL2A1; FO and KO were especially effective. Our findings indicated that FO and KO were superior to GLM for their protective effect against proteoglycan and collagen degradation. Hence, FO and KO could serve as promising sources of chondroprotective agents.

  5. Parallel Regulation of von Hippel-Lindau Disease by pVHL-Mediated Degradation of B-Myb and Hypoxia-Inducible Factor α

    Science.gov (United States)

    Uematsu, Keiji; Byrne, Stuart D.; Hirano, Mie; Joo-Okumura, Akiko; Nishikimi, Akihiko; Shuin, Taro; Fukui, Yoshinori; Nakatsukasa, Kunio

    2016-01-01

    pVHL, the protein product of the von Hippel-Lindau (VHL) tumor suppressor gene, is a ubiquitin ligase that targets hypoxia-inducible factor α (HIF-α) for proteasomal degradation. Although HIF-α activation is necessary for VHL disease pathogenesis, constitutive activation of HIF-α alone did not induce renal clear cell carcinomas and pheochromocytomas in mice, suggesting the involvement of an HIF-α-independent pathway in VHL pathogenesis. Here, we show that the transcription factor B-Myb is a pVHL substrate that is degraded via the ubiquitin-proteasome pathway and that vascular endothelial growth factor (VEGF)- and/or platelet-derived growth factor (PDGF)-dependent tyrosine 15 phosphorylation of B-Myb prevents its degradation. Mice injected with B-Myb knockdown 786-O cells developed dramatically larger tumors than those bearing control cell tumors. Microarray screening of B-Myb-regulated genes showed that the expression of HIF-α-dependent genes was not affected by B-Myb knockdown, indicating that B-Myb prevents HIF-α-dependent tumorigenesis through an HIF-α-independent pathway. These data indicate that the regulation of B-Myb by pVHL plays a critical role in VHL disease. PMID:27090638

  6. NADPH-oxidase-driven oxygen radical production determines chondrocyte death and partly regulates metalloproteinase-mediated cartilage matrix degradation during interferon-gamma-stimulated immune complex arthritis.

    NARCIS (Netherlands)

    Lent, P.L.E.M. van; Nabbe, K.C.A.M.; Blom, A.B.; Sloetjes, A.W.; Holthuysen, A.E.M.; Kolls, J.; Loo, F.A.J. van de; Holland, S.M.; Berg, W.B. van den

    2005-01-01

    In previous studies we have found that FcgammaRI determines chondrocyte death and matrix metalloproteinase (MMP)-mediated cartilage destruction during IFN-gamma-regulated immune complex arthritis (ICA). Binding of immune complexes (ICs) to FcgammaRI leads to the prominent production of oxygen

  7. CD81 Promotes Both the Degradation of Transferrin Receptor 2 (TfR2) and the Tfr2-mediated Maintenance of Hepcidin Expression*

    Science.gov (United States)

    Chen, Juxing; Enns, Caroline A.

    2015-01-01

    Mutations in transferrin receptor 2 (TfR2) cause a rare form of the hereditary hemochromatosis, resulting in iron overload predominantly in the liver. TfR2 is primarily expressed in hepatocytes and is hypothesized to sense iron levels in the blood to positively regulate the expression of hepcidin through activation of the BMP signaling pathway. Hepcidin is a peptide hormone that negatively regulates iron egress from cells and thus limits intestinal iron uptake. In this study, a yeast two-hybrid approach using the cytoplasmic domain of TfR2 identified CD81 as an interacting protein. CD81 is an abundant tetraspanin in the liver. Co-precipitations of CD81 with different TfR2 constructs demonstrated that both the cytoplasmic and ecto-transmembrane domains of TfR2 interact with CD81. Knockdown of CD81 using siRNA significantly increased TfR2 levels by increasing the half-life of TfR2, indicating that CD81 promotes degradation of TfR2. Previous studies showed that CD81 is targeted for degradation by GRAIL, an ubiquitin E3 ligase. Knockdown of GRAIL in Hep3B-TfR2 cells increased TfR2 levels, consistent with inhibition of CD81 ubiquitination. These results suggest that down-regulation of CD81 by GRAIL targets TfR2 for degradation. Surprisingly, knockdown of CD81 decreased hepcidin expression, implying that the TfR2/CD81 complex is involved in the maintenance of hepcidin mRNA. Moreover, knockdown of CD81 did not affect the stimulation of hepcidin expression by BMP6 but increased both the expression of ID1 and SMAD7, direct targets of BMP signaling pathway, and the phosphorylation of ERK1/2, indicating that the CD81 regulates hepcidin expression differently from the BMP and ERK1/2 signaling pathways. PMID:25635054

  8. Dopamine 5 receptor mediates Ang II type 1 receptor degradation via a ubiquitin-proteasome pathway in mice and human cells

    Science.gov (United States)

    Li, Hewang; Armando, Ines; Yu, Peiying; Escano, Crisanto; Mueller, Susette C.; Asico, Laureano; Pascua, Annabelle; Lu, Quansheng; Wang, Xiaoyan; Villar, Van Anthony M.; Jones, John E.; Wang, Zheng; Periasamy, Ammasi; Lau, Yuen-Sum; Soares-da-Silva, Patricio; Creswell, Karen; Guillemette, Gaétan; Sibley, David R.; Eisner, Gilbert; Felder, Robin A.; Jose, Pedro A.

    2008-01-01

    Hypertension is a multigenic disorder in which abnormal counterregulation between dopamine and Ang II plays a role. Recent studies suggest that this counterregulation results, at least in part, from regulation of the expression of both the antihypertensive dopamine 5 receptor (D5R) and the prohypertensive Ang II type 1 receptor (AT1R). In this report, we investigated the in vivo and in vitro interaction between these GPCRs. Disruption of the gene encoding D5R in mice increased both blood pressure and AT1R protein expression, and the increase in blood pressure was reversed by AT1R blockade. Activation of D5R increased the degradation of glycosylated AT1R in proteasomes in HEK cells and human renal proximal tubule cells heterologously and endogenously expressing human AT1R and D5R. Confocal microscopy, Förster/fluorescence resonance energy transfer microscopy, and fluorescence lifetime imaging microscopy revealed that activation of D5R initiated ubiquitination of the glycosylated AT1R at the plasma membrane. The regulated degradation of AT1R via a ubiquitin/proteasome pathway by activation of D5R provides what we believe to be a novel mechanism whereby blood pressure can be regulated by the interaction of 2 counterregulatory GPCRs. Our results therefore suggest that treatments for hypertension might be optimized by designing compounds that can target the AT1R and the D5R. PMID:18464932

  9. Inhibition of melanogenesis by jineol from Scolopendra subspinipes mutilans via MAP-Kinase mediated MITF downregulation and the proteasomal degradation of tyrosinase.

    Science.gov (United States)

    Alam, Md Badrul; Bajpai, Vivek K; Lee, JungIn; Zhao, Peijun; Byeon, Jung-Hee; Ra, Jeong-Sic; Majumder, Rajib; Lee, Jong Sung; Yoon, Jung-In; Rather, Irfan A; Park, Yong-Ha; Kim, Kangmin; Na, MinKyun; Lee, Sang-Han

    2017-04-10

    In this study, the authors investigated the anti-melanogenic effects of 3,8-dihydroxyquinoline (jineol) isolated from Scolopendra subspinipes mutilans, the mechanisms responsible for its inhibition of melanogenesis in melan-a cells, and its antioxidant efficacy. Mushroom tyrosinase activities and melanin contents were determined in melan-a cells, and the protein and mRNA levels of MITF, tyrosinase, TYRP-1, and TYRP-2 were assessed. Jineol exhibited significant, concentration-dependent antioxidant effects as determined by DPPH, ABTS, CUPRAC, and FRAP assays. Jineol significantly inhibited mushroom tyrosinase activity by functioning as an uncompetitive inhibitor, and markedly inhibited melanin production and intracellular tyrosinase activity in melan-a cells. In addition, jineol abolished the expressions of tyrosinase, TYRP-1, TYRP-2, and MITF, thereby blocking melanin production and interfering with the phosphorylations of ERK1/2 and p38. Furthermore, specific inhibitors of ERK1/2 and p38 prevented melanogenesis inhibition by jineol, and the proteasome inhibitor (MG-132) prevented jineol-induced reductions in cellular tyrosinase levels. Taken together, jineol was found to stimulate MAP-kinase (ERK1/2 and p38) phosphorylation and the proteolytic degradation pathway, which led to the degradations of MITF and tyrosinase, and to suppress the productions of melanin.

  10. Regulation of cysteine dioxygenase degradation is mediated by intracellular cysteine levels and the ubiquitin-26 S proteasome system in the living rat.

    Science.gov (United States)

    Dominy, John E; Hirschberger, Lawrence L; Coloso, Relicardo M; Stipanuk, Martha H

    2006-02-15

    Mammalian metabolism of ingested cysteine is conducted principally within the liver. The liver tightly regulates its intracellular cysteine pool to keep levels high enough to meet the many catabolic and anabolic pathways for which cysteine is needed, but low enough to prevent toxicity. One of the enzymes the liver uses to regulate cysteine levels is CDO (cysteine dioxygenase). Catalysing the irreversible oxidation of cysteine, CDO protein is up-regulated in the liver in response to the dietary intake of cysteine. In the present study, we have evaluated the contribution of the ubiquitin-26 S proteasome pathway to the diet-induced changes in CDO half-life. In the living rat, inhibition of the proteasome with PS1 (proteasome inhibitor 1) dramatically stabilized CDO in the liver under dietary conditions that normally favour its degradation. Ubiquitinated CDO intermediates were also seen to accumulate in the liver. Metabolic analyses showed that PS1 had a significant effect on sulphoxidation flux secondary to the stabilization of CDO but no significant effect on the intracellular cysteine pool. Finally, by a combination of in vitro hepatocyte culture and in vivo whole animal studies, we were able to attribute the changes in CDO stability specifically to cysteine rather than the metabolite 2-mercaptoethylamine (cysteamine). The present study represents the first demonstration of regulated ubiquitination and degradation of a protein in a living mammal, inhibition of which had dramatic effects on cysteine catabolism.

  11. Regulation of cysteine dioxygenase degradation is mediated by intracellular cysteine levels and the ubiquitin–26 S proteasome system in the living rat

    Science.gov (United States)

    Dominy, John E.; Hirschberger, Lawrence L.; Coloso, Relicardo M.; Stipanuk, Martha H.

    2005-01-01

    Mammalian metabolism of ingested cysteine is conducted principally within the liver. The liver tightly regulates its intracellular cysteine pool to keep levels high enough to meet the many catabolic and anabolic pathways for which cysteine is needed, but low enough to prevent toxicity. One of the enzymes the liver uses to regulate cysteine levels is CDO (cysteine dioxygenase). Catalysing the irreversible oxidation of cysteine, CDO protein is up-regulated in the liver in response to the dietary intake of cysteine. In the present study, we have evaluated the contribution of the ubiquitin–26 S proteasome pathway to the diet-induced changes in CDO half-life. In the living rat, inhibition of the proteasome with PS1 (proteasome inhibitor 1) dramatically stabilized CDO in the liver under dietary conditions that normally favour its degradation. Ubiquitinated CDO intermediates were also seen to accumulate in the liver. Metabolic analyses showed that PS1 had a significant effect on sulphoxidation flux secondary to the stabilization of CDO but no significant effect on the intracellular cysteine pool. Finally, by a combination of in vitro hepatocyte culture and in vivo whole animal studies, we were able to attribute the changes in CDO stability specifically to cysteine rather than the metabolite 2-mercaptoethylamine (cysteamine). The present study represents the first demonstration of regulated ubiquitination and degradation of a protein in a living mammal, inhibition of which had dramatic effects on cysteine catabolism. PMID:16262602

  12. CD81 promotes both the degradation of transferrin receptor 2 (TfR2) and the Tfr2-mediated maintenance of hepcidin expression.

    Science.gov (United States)

    Chen, Juxing; Enns, Caroline A

    2015-03-20

    Mutations in transferrin receptor 2 (TfR2) cause a rare form of the hereditary hemochromatosis, resulting in iron overload predominantly in the liver. TfR2 is primarily expressed in hepatocytes and is hypothesized to sense iron levels in the blood to positively regulate the expression of hepcidin through activation of the BMP signaling pathway. Hepcidin is a peptide hormone that negatively regulates iron egress from cells and thus limits intestinal iron uptake. In this study, a yeast two-hybrid approach using the cytoplasmic domain of TfR2 identified CD81 as an interacting protein. CD81 is an abundant tetraspanin in the liver. Co-precipitations of CD81 with different TfR2 constructs demonstrated that both the cytoplasmic and ecto-transmembrane domains of TfR2 interact with CD81. Knockdown of CD81 using siRNA significantly increased TfR2 levels by increasing the half-life of TfR2, indicating that CD81 promotes degradation of TfR2. Previous studies showed that CD81 is targeted for degradation by GRAIL, an ubiquitin E3 ligase. Knockdown of GRAIL in Hep3B-TfR2 cells increased TfR2 levels, consistent with inhibition of CD81 ubiquitination. These results suggest that down-regulation of CD81 by GRAIL targets TfR2 for degradation. Surprisingly, knockdown of CD81 decreased hepcidin expression, implying that the TfR2/CD81 complex is involved in the maintenance of hepcidin mRNA. Moreover, knockdown of CD81 did not affect the stimulation of hepcidin expression by BMP6 but increased both the expression of ID1 and SMAD7, direct targets of BMP signaling pathway, and the phosphorylation of ERK1/2, indicating that the CD81 regulates hepcidin expression differently from the BMP and ERK1/2 signaling pathways. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. MMP Mediated Degradation of Type VI Collagen Is Highly Associated with Liver Fibrosis - Identification and Validation of a Novel Biochemical Marker Assay

    DEFF Research Database (Denmark)

    Veidal, Sanne Skovgard; Karsdal, Morten Asser; Vassiliadis, Efstathios

    2011-01-01

    fragments, so-called neo-epitopes, may be specific biochemical marker of liver fibrosis. The aim of this study was to develop an ELISA detecting a fragment of type VI collagen generated by MMP-2 and MMP-9, and evaluate this assay in two preclinical models of liver fibrosis. Methods: Mass spectrometric...... analysis of cleaved type VI collagen revealed a large number of protease-generated neo-epitopes. A fragment unique to type VI collagen generated by MMP-2 and MMP-9 was selected for ELISA development. The CO6-MMP assay was evaluated in two rat models of liver fibrosis: bile duct ligation (BDL) and carbon......Background and Aims: During fibrogenesis, in which excessive remodeling of the extracellular matrix occurs, both the quantity of type VI collagen and levels of matrix metalloproteinases, including MMP-2 and MMP-9, increase significantly. Proteolytic degradation of type VI collagen into small...

  14. The E3 ubiquitin ligases β-TrCP and FBXW7 cooperatively mediates GSK3-dependent Mcl-1 degradation induced by the Akt inhibitor API-1, resulting in apoptosis.

    Science.gov (United States)

    Ren, Hui; Koo, Junghui; Guan, Baoxiang; Yue, Ping; Deng, Xingming; Chen, Mingwei; Khuri, Fadlo R; Sun, Shi-Yong

    2013-11-22

    The novel Akt inhibitor, API-1, induces apoptosis through undefined mechanisms. The current study focuses on revealing the mechanisms by which API-1 induces apoptosis. API-1 rapidly and potently reduced the levels of Mcl-1 primarily in API-1-senstive lung cancer cell lines. Ectopic expression of Mcl-1 protected cells from induction of apoptosis by API-1. API-1 treatment decreased the half-life of Mcl-1, whereas inhibition of the proteasome with MG132 rescued Mcl-1 reduction induced by API-1. API-1 decreased Mcl-1 levels accompanied with a rapid increase in Mcl-1 phosphorylation (S159/T163). Moreover, inhibition of GSK3 inhibited Mcl-1 phosphorylation and reduction induced by API-1 and antagonized the effect of API-1 on induction of apoptosis. Knockdown of either FBXW7 or β-TrCP alone, both of which are E3 ubiquitin ligases involved in Mcl-1 degradation, only partially rescued Mcl-1 reduction induced by API-1. However, double knockdown of both E3 ubiquitin ligases enhanced the rescue of API-1-induced Mcl-1 reduction. API-1 induces GSK3-dependent, β-TrCP- and FBXW7-mediated Mcl-1 degradation, resulting in induction of apoptosis.

  15. Phosphodiesterase inhibition mediates matrix metalloproteinase activity and the level of collagen degradation fragments in a liver fibrosis ex vivo rat model

    Directory of Open Access Journals (Sweden)

    Veidal Sanne Skovgård

    2012-12-01

    Full Text Available Abstract Background Accumulation of extracellular matrix (ECM and increased matrix metalloproteinase (MMP activity are hallmarks of liver fibrosis. The aim of the present study was to develop a model of liver fibrosis combining ex vivo tissue culture of livers from CCl4 treated animals with an ELISA detecting a fragment of type III collagen generated in vitro by MMP-9 (C3M, known to be associated with liver fibrosis and to investigate cAMP modulation of MMP activity and liver tissue turnover in this model. Findings In vivo: Rats were treated for 8 weeks with CCl4/Intralipid. Liver slices were cultured for 48 hours. Levels of C3M were determined in the supernatants of slices cultured without treatment, treated with GM6001 (positive control or treated with IBMX (phosphodiesterase inhibitor. Enzymatic activity of MMP-2 and MMP-9 were studied by gelatin zymography. Ex vivo: The levels of serum C3M increased 77% in the CCl4-treated rats at week 8 (p 4-treated animals had highly increased MMP-9, but not MMP-2 activity, compared to slices derived from control animals. Conclusions We have combined an ex vivo model of liver fibrosis with measurement of a biochemical marker of collagen degradation in the condition medium. This technology may be used to evaluate the molecular process leading to structural fibrotic changes, as collagen species are the predominant structural part of fibrosis. These data suggest that modulation of cAMP may play a role in regulation of collagen degradation associated with liver fibrosis.

  16. Conditioned Media from Adipose-Tissue-Derived Mesenchymal Stem Cells Downregulate Degradative Mediators Induced by Interleukin-1β in Osteoarthritic Chondrocytes

    Directory of Open Access Journals (Sweden)

    Julia Platas

    2013-01-01

    Full Text Available Osteoarthritis (OA is the most frequent joint disorder and an important cause of disability. Recent studies have shown the potential of adipose-tissue-derived mesenchymal stem cells (AD-MSC for cartilage repair. We have investigated whether conditioned medium from AD-MSC (CM may regulate in OA chondrocytes a number of key mediators involved in cartilage degeneration. CM enhanced type II collagen expression in OA chondrocytes while decreasing matrix metalloproteinase (MMP activity in cell supernatants as well as the levels of MMP-3 and MMP-13 proteins and mRNA in OA chondrocytes stimulated with interleukin- (IL- 1β. In addition, CM increased IL-10 levels and counteracted the stimulating effects of IL-1β on the production of tumor necrosis factor-α, IL-6, prostaglandin E2, and NO measured as nitrite and the mRNA expression of these cytokines, CCL-2, CCL-3, CCL-4, CCL-5, CCL-8, CCL-19, CCL-20, CXCL-1, CXCL-2, CXCL-3, CXCL-5, CXCL-8, cyclooxygenase-2, microsomal prostaglandin E synthase-1, and inducible NO synthase. These effects may be dependent on the inhibition of nuclear factor-κB activation by CM. Our data demonstrate the chondroprotective actions of CM and provide support for further studies of this approach in joint disease.

  17. Two functions of the C-terminal domain of Escherichia coli Rob: mediating "sequestration-dispersal" as a novel off-on switch for regulating Rob's activity as a transcription activator and preventing degradation of Rob by Lon protease.

    Science.gov (United States)

    Griffith, Kevin L; Fitzpatrick, M Megan; Keen, Edward F; Wolf, Richard E

    2009-05-08

    In Escherichia coli, Rob activates transcription of the SoxRS/MarA/Rob regulon. Previous work revealed that Rob resides in three to four immunostainable foci, that dipyridyl and bile salts are inducers of its activity, and that inducers bind to Rob's C-terminal domain (CTD). We propose that sequestration inactivates Rob by blocking its access to the transcriptional machinery and that inducers activate Rob by mediating its dispersal, allowing interaction with RNA polymerase. To test "sequestration-dispersal" as a new mechanism for regulating the activity of transcriptional activators, we fused Rob's CTD to SoxS and used indirect immunofluorescence microscopy to determine the effect of inducers on SoxS-Rob's cellular localization. Unlike native SoxS, which is uniformly distributed throughout the cell, SoxS-Rob is sequestered without an inducer, but is rapidly dispersed when cells are treated with an inducer. In this manner, Rob's CTD serves as an anti-sigma factor in regulating the co-sigma-factor-like activity of SoxS when fused to it. Rob's CTD also protects its N-terminus from Lon protease, since Lon's normally rapid degradation of SoxS is blocked in the chimera. Accordingly, Rob's CTD has novel regulatory properties that can be bestowed on another E. coli protein.

  18. Crystallization-mediated amorphous CuxO (x = 1, 2)/crystalline CuI p-p type heterojunctions with visible light enhanced and ultraviolet light restrained photocatalytic dye degradation performance

    Science.gov (United States)

    Wang, Hongli; Cai, Yun; Zhou, Jian; Fang, Jun; Yang, Yang

    2017-04-01

    We report simple and cost-effective fabrication of amorphous CuxO (x = 1, 2)/crystalline CuI p-p type heterojunctions based on crystallization-mediated approaches including antisolvent crystallization and crystal reconstruction. Starting from CuI acetonitrile solution, large crystals in commercial CuI can be easily converted to aggregates consisting of small particles by the crystallization processes while the spontaneous oxidation of CuI by atmospheric/dissolved oxygen can induce the formation of trace CuxO on CuI surface. As a proof of concept, the as-fabricated CuxO/CuI heterojunctions exhibit effective photocatalytic activity towards the degradation of methyl blue and other organic pollutants under visible light irradiation, although the wide band-gap semiconductor CuI is insensible to visible light. Unexpectedly, the CuxO/CuI heterojunctions exhibit restrained photocatalytic activity when ultraviolet light is applied in addition to the visible. It is suggested that the CuxO/CuI interface can enhance the spatial separation of the electron-hole pairs with the excitation of CuxO under visible light and prolong the lifetime of photogenerated charges with high redox ability. The present work represents a critically important step in advancing the crystallization technique for potential mass production of semiconductor heterojunctions in a mild manner.

  19. Protease-degradable electrospun fibrous hydrogels

    Science.gov (United States)

    Wade, Ryan J.; Bassin, Ethan J.; Rodell, Christopher B.; Burdick, Jason A.

    2015-03-01

    Electrospun nanofibres are promising in biomedical applications to replicate features of the natural extracellular matrix (ECM). However, nearly all electrospun scaffolds are either non-degradable or degrade hydrolytically, whereas natural ECM degrades proteolytically, often through matrix metalloproteinases. Here we synthesize reactive macromers that contain protease-cleavable and fluorescent peptides and are able to form both isotropic hydrogels and electrospun fibrous hydrogels through a photoinitiated polymerization. These biomimetic scaffolds are susceptible to protease-mediated cleavage in vitro in a protease dose-dependent manner and in vivo in a subcutaneous mouse model using transdermal fluorescent imaging to monitor degradation. Importantly, materials containing an alternate and non-protease-cleavable peptide sequence are stable in both in vitro and in vivo settings. To illustrate the specificity in degradation, scaffolds with mixed fibre populations support selective fibre degradation based on individual fibre degradability. Overall, this represents a novel biomimetic approach to generate protease-sensitive fibrous scaffolds for biomedical applications.

  20. Escape of HIV-1-infected dendritic cells from TRAIL-mediated NK cell cytotoxicity during NK-DC cross-talk--a pivotal role of HMGB1.

    Directory of Open Access Journals (Sweden)

    Marie-Thérèse Melki

    2010-04-01

    Full Text Available Early stages of Human Immunodeficiency Virus-1 (HIV-1 infection are associated with local recruitment and activation of important effectors of innate immunity, i.e. natural killer (NK cells and dendritic cells (DCs. Immature DCs (iDCs capture HIV-1 through specific receptors and can disseminate the infection to lymphoid tissues following their migration, which is associated to a maturation process. This process is dependent on NK cells, whose role is to keep in check the quality and the quantity of DCs undergoing maturation. If DC maturation is inappropriate, NK cells will kill them ("editing process" at sites of tissue inflammation, thus optimizing the adaptive immunity. In the context of a viral infection, NK-dependent killing of infected-DCs is a crucial event required for early elimination of infected target cells. Here, we report that NK-mediated editing of iDCs is impaired if DCs are infected with HIV-1. We first addressed the question of the mechanisms involved in iDC editing, and we show that cognate NK-iDC interaction triggers apoptosis via the TNF-related apoptosis-inducing ligand (TRAIL-Death Receptor 4 (DR4 pathway and not via the perforin pathway. Nevertheless, once infected with HIV-1, DC(HIV become resistant to NK-induced TRAIL-mediated apoptosis. This resistance occurs despite normal amounts of TRAIL released by NK cells and comparable DR4 expression on DC(HIV. The escape of DC(HIV from NK killing is due to the upregulation of two anti-apoptotic molecules, the cellular-Flice like inhibitory protein (c-FLIP and the cellular inhibitor of apoptosis 2 (c-IAP2, induced by NK-DC(HIV cognate interaction. High-mobility group box 1 (HMGB1, an alarmin and a key mediator of NK-DC cross-talk, was found to play a pivotal role in NK-dependent upregulation of c-FLIP and c-IAP2 in DC(HIV. Finally, we demonstrate that restoration of DC(HIV susceptibility to NK-induced TRAIL killing can be obtained either by silencing c-FLIP and c-IAP2 by specific

  1. Phytohormone and Light Regulation of Chlorophyll Degradation

    Directory of Open Access Journals (Sweden)

    Xiaoyu Zhu

    2017-11-01

    Full Text Available Degreening, due to the net loss of chlorophyll (Chl, is the most prominent symptom during the processes of leaf senescence, fruit ripening, and seed maturation. Over the last decade or so, extensive identifications of Chl catabolic genes (CCGs have led to the revelation of the biochemical pathway of Chl degradation. As such, exploration of the regulatory mechanism of the degreening process is greatly facilitated. During the past few years, substantial progress has been made in elucidating the regulation of Chl degradation, particularly via the mediation of major phytohormones' signaling. Intriguingly, ethylene and abscisic acid's signaling have been demonstrated to interweave with light signaling in mediating the regulation of Chl degradation. In this review, we briefly summarize this progress, with an effort on providing a framework for further investigation of multifaceted and hierarchical regulations of Chl degradation.

  2. Phytohormone and Light Regulation of Chlorophyll Degradation

    Science.gov (United States)

    Zhu, Xiaoyu; Chen, Junyi; Qiu, Kai; Kuai, Benke

    2017-01-01

    Degreening, due to the net loss of chlorophyll (Chl), is the most prominent symptom during the processes of leaf senescence, fruit ripening, and seed maturation. Over the last decade or so, extensive identifications of Chl catabolic genes (CCGs) have led to the revelation of the biochemical pathway of Chl degradation. As such, exploration of the regulatory mechanism of the degreening process is greatly facilitated. During the past few years, substantial progress has been made in elucidating the regulation of Chl degradation, particularly via the mediation of major phytohormones' signaling. Intriguingly, ethylene and abscisic acid's signaling have been demonstrated to interweave with light signaling in mediating the regulation of Chl degradation. In this review, we briefly summarize this progress, with an effort on providing a framework for further investigation of multifaceted and hierarchical regulations of Chl degradation. PMID:29163624

  3. Roles of protein ubiquitination and degradation kinetics in biological oscillations.

    Directory of Open Access Journals (Sweden)

    Lida Xu

    Full Text Available Protein ubiquitination and degradation play important roles in many biological functions and are associated with many human diseases. It is well known that for biochemical oscillations to occur, proper degradation rates of the participating proteins are needed. In most mathematical models of biochemical reactions, linear degradation kinetics has been used. However, the degradation kinetics in real systems may be nonlinear, and how nonlinear degradation kinetics affects biological oscillations are not well understood. In this study, we first develop a biochemical reaction model of protein ubiquitination and degradation and calculate the degradation rate against the concentration of the free substrate. We show that the protein degradation kinetics mainly follows the Michaelis-Menten formulation with a time delay caused by ubiquitination and deubiquitination. We then study analytically how the Michaelis-Menten degradation kinetics affects the instabilities that lead to oscillations using three generic oscillation models: 1 a positive feedback mediated oscillator; 2 a positive-plus-negative feedback mediated oscillator; and 3 a negative feedback mediated oscillator. In all three cases, nonlinear degradation kinetics promotes oscillations, especially for the negative feedback mediated oscillator, resulting in much larger oscillation amplitudes and slower frequencies than those observed with linear kinetics. However, the time delay due to protein ubiquitination and deubiquitination generally suppresses oscillations, reducing the amplitude and increasing the frequency of the oscillations. These theoretical analyses provide mechanistic insights into the effects of specific proteins in the ubiquitination-proteasome system on biological oscillations.

  4. cAMP-Induced Desensitization of Surface cAMP Receptors in Dictyostelium : Different Second Messengers Mediate Receptor Phosphorylation, Loss of Ligand Binding, Degradation of Receptor, and Reduction of Receptor mRNA Levels

    NARCIS (Netherlands)

    Haastert, Peter J.M. van; Wang, Mei; Bominaar, Anthony A.; Devreotes, Peter N.; Schaap, Pauline

    Surface cAMP receptors on Dictyostelium cells are linked to several second messenger systems and mediate multiple physiological responses, including chemotaxis and differentiation. Activation of the receptor also triggers events which desensitize signal transduction. These events include the

  5. PEM fuel cell degradation

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

    2010-01-01

    The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. While significant progress has been made in understanding degradation mechanisms and improving materials, further improvements in durability are required to meet commercialization targets. Catalyst and electrode durability remains a primary degradation mode, with much work reported on understanding how the catalyst and electrode structure degrades. Accelerated Stress Tests (ASTs) are used to rapidly evaluate component degradation, however the results are sometimes easy, and other times difficult to correlate. Tests that were developed to accelerate degradation of single components are shown to also affect other component's degradation modes. Non-ideal examples of this include ASTs examining catalyst degradation performances losses due to catalyst degradation do not always well correlate with catalyst surface area and also lead to losses in mass transport.

  6. Mechanistic study of a diazo dye degradation by Soybean Peroxidase

    OpenAIRE

    Kalsoom, Umme; Ashraf, Syed Salman; Meetani, Mohammed A; Rauf, Muhammad A; Bhatti, Haq Nawaz

    2013-01-01

    Background Enzyme based remediation of wastewater is emerging as a novel, efficient and environmentally-friendlier approach. However, studies showing detailed mechanisms of enzyme mediated degradation of organic pollutants are not widely published. Results The present report describes a detailed study on the use of Soybean Peroxidase to efficiently degrade Trypan Blue, a diazo dye. In addition to examining various parameters that can affect the dye degradation ability of the enzyme, such as e...

  7. Pressure-induced endocytic degradation of the Saccharomyces cerevisiae low-affinity tryptophan permease Tat1 is mediated by Rsp5 ubiquitin ligase and functionally redundant PPxY motif proteins.

    Science.gov (United States)

    Suzuki, Asaha; Mochizuki, Takahiro; Uemura, Satoshi; Hiraki, Toshiki; Abe, Fumiyoshi

    2013-07-01

    Cells of Saccharomyces cerevisiae express two tryptophan permeases, Tat1 and Tat2, which have different characteristics in terms of their affinity for tryptophan and intracellular localization. Although the high-affinity permease Tat2 has been well documented in terms of its ubiquitin-dependent degradation, the low-affinity permease Tat1 has not yet been characterized fully. Here we show that a high hydrostatic pressure of 25 MPa triggers a degradation of Tat1 which depends on Rsp5 ubiquitin ligase and the EH domain-containing protein End3. Tat1 was resistant to a 3-h cycloheximide treatment, suggesting that it is highly stable under normal growth conditions. The ubiquitination of Tat1 most likely occurs at N-terminal lysines 29 and 31. Simultaneous substitution of arginine for the two lysines prevented Tat1 degradation, but substitution of either of them alone did not, indicating that the roles of lysines 29 and 31 are redundant. When cells were exposed to high pressure, Tat1-GFP was completely lost from the plasma membrane, while substantial amounts of Tat1(K29R-K31R)-GFP remained. The HPG1-1 (Rsp5(P514T)) and rsp5-ww3 mutations stabilized Tat1 under high pressure, but any one of the rsp5-ww1, rsp5-ww2, and bul1Δ bul2Δ mutations or single deletions of genes encoding arrestin-related trafficking adaptors did not. However, simultaneous loss of 9-arrestins and Bul1/Bul2 prevented Tat1 degradation at 25 MPa. The results suggest that multiple PPxY motif proteins share some essential roles in regulating Tat1 ubiquitination in response to high hydrostatic pressure.

  8. Facile fabrication of mediator-free Z-scheme photocatalyst of phosphorous-doped ultrathin graphitic carbon nitride nanosheets and bismuth vanadate composites with enhanced tetracycline degradation under visible light.

    Science.gov (United States)

    Deng, Yaocheng; Tang, Lin; Zeng, Guangming; Wang, Jiajia; Zhou, Yaoyu; Wang, Jingjing; Tang, Jing; Wang, Longlu; Feng, Chengyang

    2018-01-01

    To realize the sustainable employment of solar energy in contaminant degradation and environmental recovery, design and development of an efficient photocatalyst is urgently needed. Herein, a novel direct Z-scheme composite photocatalysts consist of phosphorous-doped ultrathin g-C3N4 nanosheets (PCNS) and bismuth vanadate (BiVO4) are developed via a one-pot impregnated precipitation method. The as-prepared hybrid nanocomposite was utilized for the degradation tetracycline (TC) under visible light irradiation. Among the composites with various PCNS/BiVO4 ratios, the prepared PCNS/BVO-400 photocatalyst presents the best performance, showing a TC (10mg/L) removal efficiency of 96.95% within 60min, more than double that of pristine BiVO4 (41.45%) and higher than that of pure PCNS (71.78%) under the same conditions. The effects of initial TC concentration, catalyst dosage, pH value and different water sources have been studied in detail. The improved photocatalytic performance of the as-prepared PCNS/BiVO4 nanocomposites could be attributed to the promoted separation efficiency of the photogenerated electrons and the enhanced charge carrier lifetime (1.65ns) owing to the synergistic effect between the PCNS and BiVO4. The degradation intermediates and decomposition pathway of TC were also analyzed and proposed. Additionally, radical trapping experiments and ESR measurement indicated that the photogenerated holes (h+), superoxide radical (O2-) and hydroxyl radical (OH) all participated in the TC removal procedure in the reaction system. The high performance of PCNS/BVO-400 in real wastewater indicated the potential of the prepared composite in practical application. This work provides an efficient and promising approach for the formation of high performance Z-scheme photocatalyst and study the possibility for real wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Bacterial IgA protease-mediated degradation of agIgA1 and agIgA1 immune complexes as a potential therapy for IgA Nephropathy

    OpenAIRE

    Li Wang; Xueying Li; Hongchun Shen; Nan Mao; Honglian Wang; Luke Cui; Yuan Cheng; Junming Fan

    2016-01-01

    Mesangial deposition of aberrantly glycosylated IgA1 (agIgA1) and its immune complexes is a key pathogenic mechanism of IgA nephropathy (IgAN). However, treatment of IgAN remains ineffective. We report here that bacteria-derived IgA proteases are capable of degrading these pathogenic agIgA1 and derived immune complexes in vitro and in vivo. By screening 14 different bacterial strains (6 species), we found that 4 bacterial IgA proteases from H. influenzae, N. gonorrhoeae and N. meningitidis ex...

  10. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    . Bioaugmentation i.e. addition of specific degrader organisms, has been suggested as an environmentally friendly and economically competitive strategy for cleaning polluted sites. Several organisms have been isolated, capable of degrading different compounds. However the capacity to degrade the desired compound...... SRS2, Variovorax SRS16 and Arthrobacter globiformis D47. The degradation capacity of each strain individually as well as two- and three-member consortia was studied in a sand column set up. Glass beads were added to the set up to create a dry patch, separating the organisms and the diuron-spiked sand...

  11. Trastuzumab-induced recruitment of Csk-homologous kinase (CHK) to ErbB2 receptor is associated with ErbB2-Y1248 phosphorylation and ErbB2 degradation to mediate cell growth inhibition

    Science.gov (United States)

    Dokmanovic, Milos; Wu, Yun; Shen, Yi; Chen, Jieqing; Hirsch, Dianne S; Wu, Wen Jin

    2014-01-01

    The inhibitory effect of trastuzumab, a humanized monoclonal antibody directed against the extracellular domain of ErbB2, is associated with its ability to induce ErbB2-Y1248 phosphorylation, and the status of phosphorylated ErbB2-Y1248 (ErbB2-pY1248) may correlate with the sensitivity of breast cancers to trastuzumab. The mechanisms of which remain unclear. Here, we show that binding of trastuzumab to ErbB2 activates ErbB2 kinase activity and enhances ErbB2-Y1248 phosphorylation in trastuzumab-sensitive breast cancer cells. This in turn increases the interaction between ErbB2 and non-receptor Csk-homologous kinase (CHK), leading to growth inhibition of breast cancer cells. Overexpression of CHK mimics trastuzumab treatment to mediate ErbB2-Y1248 phosphorylation, Akt downregulation, and growth inhibition of trastuzumab-sensitive breast cancer cells. CHK overexpression combined with trastuzumab exerts an additive effect on cell growth inhibition. We further demonstrate that positive ErbB2-pY1248 staining in ErbB2-positive breast cancer biopsies correlates with the increased trastuzumab response in trastuzumab neoadjuvant settings. Collectively, this study highlights an important role for ErbB2-pY1248 in mediating trastuzumab-induced growth inhibition and trastuzumab-induced interactions between CHK and ErbB2-pY1248 is identified as a novel mechanism of action that mediates the growth inhibition of breast cancer cells. The novel mechanistic insights into trastuzumab action revealed by this study may impact the design of next generation of therapeutic monoclonal antibodies targeting receptor tyrosine kinases, as well as open new avenues to identify novel targets for the treatment of ErbB2-positive cancers. PMID:24835103

  12. [Microbial degradation of glyphosate herbicides (review)].

    Science.gov (United States)

    Sviridov, A V; Shushkova, T V; Ermakova, I T; Ivanova, E V; Epiktetov, D O; Leont'evskii, A A

    2015-01-01

    This review analyzes the issues associated with biodegradation of glyphosate (N-(phosphonomethyl)glycine), one of the most widespread herbicides. Glyphosate can accumulate in natural environments and can be toxic not only for plants but also for animals and bacteria. Microbial transformation and mineralization ofglyphosate, as the only means of its rapid degradation, are discussed in detail. The different pathways of glyphosate catabolism employed by the known destructing bacteria representing different taxonomic groups are described. The potential existence of alternative glyphosate degradation pathways, apart from those mediated by C-P lyase and glyphosate oxidoreductase, is considered. Since the problem of purifying glyphosate-contaminated soils and water bodies is a topical issue, the possibilities of applying glyphosate-degrading bacteria for their bioremediation are discussed.

  13. Emdogain stimulates matrix degradation by osteoblasts.

    Science.gov (United States)

    Goda, S; Inoue, H; Kaneshita, Y; Nagano, Y; Ikeo, T; Ikeo, Y T; Iida, J; Domae, N

    2008-08-01

    Emdogain has been used clinically for periodontal regeneration, although the underlying molecular mechanisms are not clear at present. In this study, we hypothesized that Emdogain stimulated degradation of type I collagen via osteoblasts. We showed that Emdogain enhanced cell-mediated degradation of type I collagen in an MMP-dependent manner. Although MG-63 cells spontaneously produced a zymogen form of MMP-1, treatment with Emdogain significantly induced the generation of the active form of this enzyme. We demonstrated that MMP-3 was produced from MG63 cells in response to Emdogain in a MEK1/2-dependent manner. Concomitantly, blocking of MEK1/2 activation by U0126 significantly inhibited the generation of the active form of MMP-1 without affecting the total production of this collagenase. These results suggest that Emdogain facilitates tissue regeneration through the activation of the collagenase, MMP-1, that degrades matrix proteins in bone tissue microenvironments.

  14. Intermittent degradation and schizotypy

    Directory of Open Access Journals (Sweden)

    Matthew W. Roché

    2015-06-01

    Full Text Available Intermittent degradation refers to transient detrimental disruptions in task performance. This phenomenon has been repeatedly observed in the performance data of patients with schizophrenia. Whether intermittent degradation is a feature of the liability for schizophrenia (i.e., schizotypy is an open question. Further, the specificity of intermittent degradation to schizotypy has yet to be investigated. To address these questions, 92 undergraduate participants completed a battery of self-report questionnaires assessing schizotypy and psychological state variables (e.g., anxiety, depression, and their reaction times were recorded as they did so. Intermittent degradation was defined as the number of times a subject’s reaction time for questionnaire items met or exceeded three standard deviations from his or her mean reaction time after controlling for each item’s information processing load. Intermittent degradation scores were correlated with questionnaire scores. Our results indicate that intermittent degradation is associated with total scores on measures of positive and disorganized schizotypy, but unrelated to total scores on measures of negative schizotypy and psychological state variables. Intermittent degradation is interpreted as potentially derivative of schizotypy and a candidate endophenotypic marker worthy of continued research.

  15. Neo-Epitopes—Fragments of Cartilage and Connective Tissue Degradation in Early Rheumatoid Arthritis and Unclassified Arthritis

    DEFF Research Database (Denmark)

    Maijer, Karen I; Gudmann, Natasja Stæhr; Karsdal, Morten Asser

    2016-01-01

    Objective: Tissue destruction in rheumatoid arthritis (RA) is predominantly mediated by matrix metalloproteinases (MMPs), thereby generating protein fragments. Previous studies have revealed that these fragments include MMP-mediated collagen type I, II, and III degradation, citrullinated and MMP...

  16. Degradation of implant materials

    CERN Document Server

    Eliaz, Noam

    2012-01-01

    This book surveys the degradation of implant materials, reviewing in detail such failure mechanisms as corrosion, fatigue and wear, along with monitoring techniques. Surveys common implant biomaterials, as well as procedures for implant retrieval and analysis.

  17. Bacterial Degradation of Pesticides

    DEFF Research Database (Denmark)

    Knudsen, Berith Elkær

    This PhD project was carried out as part of the Microbial Remediation of Contaminated Soil and Water Resources (MIRESOWA) project, funded by the Danish Council for Strategic Research (grant number 2104-08-0012). The environment is contaminated with various xenobiotic compounds e.g. pesticides....... Bioaugmentation i.e. addition of specific degrader organisms, has been suggested as an environmentally friendly and economically competitive strategy for cleaning polluted sites. Several organisms have been isolated, capable of degrading different compounds. However the capacity to degrade the desired compound...... is just one requirement for successful bioaugmentation. There are several challenges that need to be overcome in order for bioaugmentation to be sufficiently efficient. The purpose of this PhD project was to study the degradative abilities of different bacteria, and, in collaboration with a fellow Ph...

  18. Thraustochytrid protists degrade hydrocarbons

    Digital Repository Service at National Institute of Oceanography (India)

    Raikar, M.T.; Raghukumar, S.; Vani, V.; David, J.J.; Chandramohan, D.

    that thraustochytrids have the capability to utilize a wide range of organic nitrogen and carbon compounds for their nutrition. However, the capability of these protists to degrade hydrocarbons has not been examined so far. Hydrocarbons occur in seawater either... chromatography. (1) Gravimetry: Tarballs were extracted from experimental flasks with 10 ml of carbon tetrachloride, the extract transferred to pre- weighed Petri dish and the solvent allowed to RAIKAR et al.: THRAUSTOCHYTRID PROTISTS DEGRADE HYDROCARBONS...

  19. Abeta-degrading enzymes in Alzheimer's disease.

    Science.gov (United States)

    Miners, James Scott; Baig, Shabnam; Palmer, Jennifer; Palmer, Laura E; Kehoe, Patrick G; Love, Seth

    2008-04-01

    In Alzheimer's disease (AD) Abeta accumulates because of imbalance between the production of Abeta and its removal from the brain. There is increasing evidence that in most sporadic forms of AD, the accumulation of Abeta is partly, if not in some cases solely, because of defects in its removal--mediated through a combination of diffusion along perivascular extracellular matrix, transport across vessel walls into the blood stream and enzymatic degradation. Multiple enzymes within the central nervous system (CNS) are capable of degrading Abeta. Most are produced by neurons or glia, but some are expressed in the cerebral vasculature, where reduced Abeta-degrading activity may contribute to the development of cerebral amyloid angiopathy (CAA). Neprilysin and insulin-degrading enzyme (IDE), which have been most extensively studied, are expressed both neuronally and within the vasculature. The levels of both of these enzymes are reduced in AD although the correlation with enzyme activity is still not entirely clear. Other enzymes shown capable of degrading Abetain vitro or in animal studies include plasmin; endothelin-converting enzymes ECE-1 and -2; matrix metalloproteinases MMP-2, -3 and -9; and angiotensin-converting enzyme (ACE). The levels of plasmin and plasminogen activators (uPA and tPA) and ECE-2 are reported to be reduced in AD. Reductions in neprilysin, IDE and plasmin in AD have been associated with possession of APOEepsilon4. We found no change in the level or activity of MMP-2, -3 or -9 in AD. The level and activity of ACE are increased, the level being directly related to Abeta plaque load. Up-regulation of some Abeta-degrading enzymes may initially compensate for declining activity of others, but as age, genetic factors and diseases such as hypertension and diabetes diminish the effectiveness of other Abeta-clearance pathways, reductions in the activity of particular Abeta-degrading enzymes may become critical, leading to the development of AD and CAA.

  20. DDE remediation and degradation.

    Science.gov (United States)

    Thomas, John E; Ou, Li-Tse; All-Agely, Abid

    2008-01-01

    DDT and its metabolites, DDD and DDE, have been shown to be recalcitrant to degradation. The parent compound, DDT, was used extensively worldwide starting in 1939 and was banned in the United States in 1973. The daughter compound, DDE, may result from aerobic degradation, abiotic dehydrochlorination, or photochemical decomposition. DDE has also occurred as a contaminant in commercial-grade DDT. The p,p'-DDE isomer is more biologically active than the o,p-DDE, with a reported half-life of -5.7 years. However, when DDT was repeatedly applied to the soil, the DDE concentration may remain unchanged for more than 20 yr. Remediation of DDE-contaminated soil and water may be done by several techniques. Phytoremediation involves translocating DDT, DDD, and DDE from the soil into the plant, although some aquatic species (duckweed > elodea > parrot feather) can transform DDT into predominantly DDD with some DDE being formed. Of all the plants that can uptake DDE, Cucurbita pepo has been the most extensively studied, with translocation values approaching "hyperaccumulation" levels. Soil moisture, temperature, and plant density have all been documented as important factors in the uptake of DDE by Cucurbita pepo. Uptake may also be influenced positively by amendments such as biosurfactants, mycorrhizal inoculants, and low molecular weight organic acids (e.g., citric and oxalic acids). DDE microbial degradation by dehalogenases, dioxygenases, and hydrolases occurs under the proper conditions. Although several aerobic degradation pathways have been proposed, none has been fully verified. Very few aerobic pure cultures are capable of fully degrading DDE to CO2. Cometabolism of DDE by Pseudomonas sp., Alicaligens sp., and Terrabacter sp. grown on biphenyl has been reported; however, not all bacterial species that produce biphenyl dioxygenase degraded DDE. Arsenic and copper inhibit DDE degradation by aerobic microorganisms. Similarly, metal chelates such as EDTA inhibit the

  1. The Proteasome Inhibitor Bortezomib Sensitizes AML with Myelomonocytic Differentiation to TRAIL Mediated Apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Dijk, Marianne van; Murphy, Eoin [Apoptosis Research Center, National University of Ireland, University Road, Galway (Ireland); School of Natural Sciences, National University of Ireland, University Road, Galway (Ireland); Morrell, Ruth [Apoptosis Research Center, National University of Ireland, University Road, Galway (Ireland); School of Natural Sciences, National University of Ireland, University Road, Galway (Ireland); School of Medicine, National University of Ireland, University Road, Galway (Ireland); Knapper, Steven [Department of Haematology, School of Medicine, Cardiff University, Heath Park, CF14 4XN Cardiff (United Kingdom); O' Dwyer, Michael [Apoptosis Research Center, National University of Ireland, University Road, Galway (Ireland); School of Medicine, National University of Ireland, University Road, Galway (Ireland); Samali, Afshin; Szegezdi, Eva, E-mail: eva.szegezdi@nuigalway.ie [Apoptosis Research Center, National University of Ireland, University Road, Galway (Ireland); School of Natural Sciences, National University of Ireland, University Road, Galway (Ireland)

    2011-03-15

    Acute myeloid leukemia (AML) is an aggressive stem cell malignancy that is difficult to treat. There are limitations to the current treatment regimes especially after disease relapse, and therefore new therapeutic agents are urgently required which can overcome drug resistance whilst avoiding unnecessary toxicity. Among newer targeted agents, both tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and proteasome inhibitors show particular promise. In this report we show that a combination of the proteasome inhibitor bortezomib and TRAIL is effective against AML cell lines, in particular, AML cell lines displaying myelomonocytic/monocytic phenotype (M4/M5 AML based on FAB classification), which account for 20-30% of AML cases. We show that the underlying mechanism of sensitization is at least in part due to bortezomib mediated downregulation of c-FLIP and XIAP, which is likely to be regulated by NF-κB. Blockage of NF-κB activation with BMS-345541 equally sensitized myelomonocytic AML cell lines and primary AML blasts to TRAIL.

  2. The Proteasome Inhibitor Bortezomib Sensitizes AML with Myelomonocytic Differentiation to TRAIL Mediated Apoptosis

    Directory of Open Access Journals (Sweden)

    Eva Szegezdi

    2011-03-01

    Full Text Available Acute myeloid leukemia (AML is an aggressive stem cell malignancy that is difficult to treat. There are limitations to the current treatment regimes especially after disease relapse, and therefore new therapeutic agents are urgently required which can overcome drug resistance whilst avoiding unnecessary toxicity. Among newer targeted agents, both tumor necrosis factor (TNF-related apoptosis-inducing ligand (TRAIL and proteasome inhibitors show particular promise. In this report we show that a combination of the proteasome inhibitor bortezomib and TRAIL is effective against AML cell lines, in particular, AML cell lines displaying myelomonocytic/monocytic phenotype (M4/M5 AML based on FAB classification, which account for 20-30% of AML cases. We show that the underlying mechanism of sensitization is at least in part due to bortezomib mediated downregulation of c-FLIP and XIAP, which is likely to be regulated by NF-κB. Blockage of NF-κB activation with BMS-345541 equally sensitized myelomonocytic AML cell lines and primary AML blasts to TRAIL.

  3. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  4. Susceptibility of anthocyanins to ex vivo degradation in human saliva

    Science.gov (United States)

    Kamonpatana, Kom; Giusti, M. Mónica; Chitchumroonchokchai, Chureeporn; MorenoCruz, Maria; Riedl, Ken M.; Kumar, Purnima; Failla, Mark L.

    2013-01-01

    Some fruits and their anthocyanin-rich extracts have been reported to exhibit chemopreventive activity in the oral cavity. Insights regarding oral metabolism of anthocyanins remain limited. Anthocyanin-rich extracts from blueberry, chokeberry, black raspberry, red grape, and strawberry were incubated ex vivo with human saliva from 14 healthy subjects. All anthocyanins were partially degraded in saliva. Degradation of chokeberry anthocyanins in saliva was temperature dependent and decreased by heating saliva to 80 °C and after removal of cells. Glycosides of delphinidin and petunidin were more susceptible to degradation than those of cyanidin, pelargonidin, peonidin and malvidin in both intact and artificial saliva. Stability of di- and tri-saccharide conjugates of anthocyanidins slightly, but significantly, exceeded that of monosaccharide compounds. Ex vivo degradation of anthocyanins in saliva was significantly decreased after oral rinsing with antibacterial chlorhexidine. These results suggest that anthocyanin degradation in the mouth is structure-dependent and largely mediated by oral microbiota. PMID:22868153

  5. ECM degradation assays for analyzing local cell invasion.

    Science.gov (United States)

    Artym, Vira V; Yamada, Kenneth M; Mueller, Susette C

    2009-01-01

    Proteolytic degradation of extracellular matrix (ECM) is a critical step during cell invasion and tissue transmigration that is required for many physiological and pathological processes. Cellular structures that mediate cell adhesion to, degradation of, and invasion into ECM are invadopodia of transformed and tumor cells and podosomes of normal monocytic, endothelial, and smooth muscle cells. Detecting the ability of the cell to form invadopodia and podosomes and to degrade ECM is required for studying the invasive capability of the cell. We have developed approximately 50 nm thick fluorescent gelatin matrices that provide a rapid, sensitive, and reliable in vitro system for detection of invadopodia and podosomes, and measurements of the extent of ECM degradation. In this chapter, we provide a detailed protocol for preparation of thin fluorescent gelatin matrices and for evaluation of the results from this degradation assay.

  6. Motor degradation prediction methods

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-12-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

  7. REGULATION OF COAL POLYMER DEGRADATION BY FUNGI

    Energy Technology Data Exchange (ETDEWEB)

    John A. Bumpus

    1998-11-30

    A variety of lignin degrading fungi mediate solubilization and subsequent biodegradation of coal macromolecules (a.k.a. coal polymer) from highly oxidized low rank coals such as leonardites. It appears that oxalate or possibly other metal chelators (i.e., certain Krebs Cycle intermediates) mediate solubilization of low rank coals while extracellular oxidases have a role in subsequent oxidation of solubilized coal macromolecule. These processes are under nutritional control. For example, in the case of P. chrysosporium, solubilization of leonardite occurred when the fungi were cultured on most but not all nutrient agars tested and subsequent biodegradation occurred only in nutrient nitrogen limited cultures. Lignin peroxidases mediate oxidation of coal macromolecule in a reaction that is dependent on the presence of veratryl alcohol and hydrogen peroxide. Kinetic evidence suggests that veratryl alcohol is oxidized to the veratryl alcohol cation radical which then mediates oxidation of the coal macromolecule. Results by others suggest that Mn peroxidases mediate formation of reactive Mn{sup 3+} complexes which also mediate oxidation of coal macromolecule. A biomimetic approach was used to study solubilization of a North Dakota leonardite. It was found that a concentration {approximately}75 mM sodium oxalate was optimal for solubilization of this low rank coal. This is important because this is well above the concentration of oxalate produced by fungi in liquid culture. Higher local concentrations probably occur in solid agar cultures and thus may account for the observation that greater solubilization occurs in agar media relative to liquid media. The characteristics of biomimetically solubilized leonardite were similar to those of biologically solubilized leonardite. Perhaps our most interesting observation was that in addition to oxalate, other common Lewis bases (phosphate/hydrogen phosphate/dihydrogen phosphate and bicarbonate/carbonate ions) are able to mediate

  8. Characterization of Methane Degradation and Methane-Degrading Microbes in Alaska Coastal Water

    Energy Technology Data Exchange (ETDEWEB)

    Kirchman, David L. [Univ. of Delaware, Lewes, DE (United States)

    2012-03-29

    The net flux of methane from methane hydrates and other sources to the atmosphere depends on methane degradation as well as methane production and release from geological sources. The goal of this project was to examine methane-degrading archaea and organic carbon oxidizing bacteria in methane-rich and methane-poor sediments of the Beaufort Sea, Alaska. The Beaufort Sea system was sampled as part of a multi-disciplinary expedition (Methane in the Arctic Shelf or MIDAS) in September 2009. Microbial communities were examined by quantitative PCR analyses of 16S rRNA genes and key methane degradation genes (pmoA and mcrA involved in aerobic and anaerobic methane degradation, respectively), tag pyrosequencing of 16S rRNA genes to determine the taxonomic make up of microbes in these sediments, and sequencing of all microbial genes (metagenomes ). The taxonomic and functional make-up of the microbial communities varied with methane concentrations, with some data suggesting higher abundances of potential methane-oxidizing archaea in methane-rich sediments. Sequence analysis of PCR amplicons revealed that most of the mcrA genes were from the ANME-2 group of methane oxidizers. According to metagenomic data, genes involved in methane degradation and other degradation pathways changed with sediment depth along with sulfate and methane concentrations. Most importantly, sulfate reduction genes decreased with depth while the anaerobic methane degradation gene (mcrA) increased along with methane concentrations. The number of potential methane degradation genes (mcrA) was low and inconsistent with other data indicating the large impact of methane on these sediments. The data can be reconciled if a small number of potential methane-oxidizing archaea mediates a large flux of carbon in these sediments. Our study is the first to report metagenomic data from sediments dominated by ANME-2 archaea and is one of the few to examine the entire microbial assemblage potentially involved in

  9. Photovoltaic Degradation Risk: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Kurtz, S. R.

    2012-04-01

    The ability to accurately predict power delivery over the course of time is of vital importance to the growth of the photovoltaic (PV) industry. Important cost drivers include the efficiency with which sunlight is converted into power, how this relationship changes over time, and the uncertainty in this prediction. An accurate quantification of power decline over time, also known as degradation rate, is essential to all stakeholders - utility companies, integrators, investors, and researchers alike. In this paper we use a statistical approach based on historical data to quantify degradation rates, discern trends and quantify risks related to measurement uncertainties, number of measurements and methodologies.

  10. Antifoam degradation testing

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Zamecnik, J. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Newell, D. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)

    2015-08-20

    This report describes the results of testing to quantify the degradation products resulting from the dilution and storage of Antifoam 747. Antifoam degradation is of concern to the Defense Waste Processing Facility (DWPF) due to flammable decomposition products in the vapor phase of the Chemical Process Cell vessels, as well as the collection of flammable and organic species in the offgas condensate. The discovery that hexamethyldisiloxane is formed from the antifoam decomposition was the basis for a Potential Inadequacy in the Safety Analysis declaration by the DWPF.

  11. In vitro study on the degradation of lithium-doped hydroxyapatite for bone tissue engineering scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaping; Yang, Xu; Gu, Zhipeng; Qin, Huanhuan [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Li, Li [Department of Oncology, The 452 Hospital of Chinese PLA, Chengdu, Sichuan Province 610021 (China); Liu, Jingwang [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Yu, Xixun, E-mail: yuxixun@163.com [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2016-09-01

    Li-doped hydroxyapatite (LiHA) which is prepared through introducing low dose of Li into hydroxyapatite (HA) has been increasingly studied as a bone tissue-engineered scaffold. The degradation properties play a crucial role in the success of long-term implantation of a bone tissue-engineered construct. Herein, the in vitro degradation behaviors of LiHA scaffolds via two approaches were investigated in this study: solution-mediated degradation and osteoblast-mediated degradation. In solution-mediated degradation, after being immersed in simulated body fluid (SBF) for some time, some characteristics of these scaffolds (such as release of ionized lithium and phosphate, pH change, mechanical properties, cytocompatibility and SEM surface characterization) were systematically tested. A similar procedure was also employed to research the degradation behaviors of LiHA scaffolds in osteoblast-mediated degradation. The results suggested that the degradation in SBF and degradation in culture medium with cell existed distinguishing mechanisms. LiHA scaffolds were degraded via a hydrolytic mechanism when they were soaked in SBF. Upon degradation, an apatite precipitation (layer) was formed on the surfaces of scaffolds. While a biological mechanism was presented for the degradation of scaffolds in cell-mediated degradation. Compared with pure HA, LiHA scaffolds had a better effect on the growth of osteoblast cells, meanwhile, the release amount of PO{sub 4}{sup 3−} in a degradation medium indicated that osteoblasts could accelerate the degradation of LiHA due to the more physiological activities of osteoblast. According to the results from compressive strength test, doping Li into HA could enhance the strength of HA. Moreover, the results from MTT assay and SEM observation showed that the degradation products of LiHA scaffolds were beneficial to the proliferation of osteoblasts. The results of this research can provide the theoretical basis for the clinical application of Li

  12. Epithelial EZH2 serves as an epigenetic determinant in experimental colitis by inhibiting TNFα-mediated inflammation and apoptosis.

    Science.gov (United States)

    Liu, Yongfeng; Peng, Junjie; Sun, Tongyu; Li, Ni; Zhang, Le; Ren, Jiale; Yuan, Huairui; Kan, Shan; Pan, Qiang; Li, Xiang; Ding, Yufeng; Jiang, Min; Cong, Xiaoji; Tan, Minjia; Ma, Yushui; Fu, Da; Cai, Sanjun; Xiao, Yichuan; Wang, Xiaoming; Qin, Jun

    2017-05-09

    Epithelial barrier disruption is a major cause of inflammatory bowel disease (IBD); however, the mechanism through which epigenetic regulation modulates intestinal epithelial integrity remains largely undefined. Here we show that EZH2, the catalytic subunit of polycomb repressive complex (PRC2), is indispensable for maintaining epithelial cell barrier integrity and homeostasis under inflammatory conditions. In accordance with reduced EZH2 expression in patients, the inactivation of EZH2 in IECs sensitizes mice to DSS- and TNBS-induced experimental colitis. Conversely, EZH2 overexpression in the intestinal epithelium renders mice more resistant to colitis. Mechanistically, the genes encoding TRAF2/5 are held in a finely tuned bivalent status under inflammatory conditions. EZH2 deficiency potentiates the expression of these genes to enhance TNFα-induced NF-κB signaling, thereby leading to uncontrolled inflammation. More importantly, we show that EZH2 depletion compromises the protective role of NF-κB signaling in cell survival by directly up-regulating ITCH, a well-known E3 ligase that degrades the c-FLIP protein. Thus, our findings highlight an epigenetic mechanism by which EZH2 integrates the multifaceted effects of TNFα signaling to promote the inflammatory response and apoptosis in colitis.

  13. Different enantioselective degradation of pyraclofos in soils.

    Science.gov (United States)

    Xu, Yuxin; Zhang, Hu; Zhuang, Shulin; Yu, Man; Xiao, Hua; Qian, Mingrong

    2012-05-02

    This study investigated the enantioselective degradation behavior of pyraclofos in three soils (NC, HZ, and ZZ) under native and sterilized conditions. The absolute configuration of pyraclofos enantiomers has been determined by the combination of experimental and calculated electronic circular dichroism spectra. S-(+)- and R-(-)-Pyraclofos were separated and determined on a cellulose tri-(4-chloro-3-methylphenylcarbamate) (Lux Cellulose-4) chiral column by reversed-phase high-performance liquid chromatography-tandem mass spectrometry. Pyraclofos enantiomers were configurationally stable in three soils and no interconversion was observed during the incubation of enantiopure S-(+)- or R-(-)-pyraclofos under native conditions. The enantioselective degradation behavior of chiral pyraclofos was dramatically different in three soils under native conditions, with half-lives (t(1/2)) of pyraclofos in NC, HZ, and ZZ soils of 2.6, 13.4, and 7.8 days for S-(+)-pyraclofos and 9.2, 9.3, and 8.2 days for R-(-)-pyraclofos. Compared to the half-lives (t(1/2)) of rac-pyraclofos of 21.5, 55.9, and 14.4 days in sterilized NC, HZ and ZZ soils, the degradation velocity was greatly improved in native soils, indicating that degradation was greatly attributed to microbially mediated processes in agricultural cultivating soils.

  14. Endocytic collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H.; Jürgensen, Henrik J.; Ingvarsen, Signe Ziir

    2012-01-01

    it crucially important to understand both the collagen synthesis and turnover mechanisms in this condition. Here we show that the endocytic collagen receptor, uPARAP/Endo180, is a major determinant in governing the balance between collagen deposition and degradation. Cirrhotic human livers displayed a marked...

  15. Degradation of fluorotelomer alcohols

    DEFF Research Database (Denmark)

    Ellis, David A; Martin, Jonathan W; De Silva, Amila O

    2004-01-01

    . The significance of the gas-phase peroxy radical cross reactions that produce PFCAs has not been recognized previously. Such reactions are expected to occur during the atmospheric degradation of all polyfluorinated materials, necessitating a reexamination of the environmental fate and impact of this important...... class of industrial chemicals....

  16. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  17. Mediatized Humanitarianism

    DEFF Research Database (Denmark)

    Vestergaard, Anne

    2014-01-01

    The article investigates the implications of mediatization for the legitimation strategies of humanitarian organizations. Based on a (full population) corpus of ~400 pages of brochure material from 1970 to 2007, the micro-textual processes involved in humanitarian organizations' efforts to legiti......The article investigates the implications of mediatization for the legitimation strategies of humanitarian organizations. Based on a (full population) corpus of ~400 pages of brochure material from 1970 to 2007, the micro-textual processes involved in humanitarian organizations' efforts...... legitimation by accountancy, legitimation by institutionalization, and legitimation by compensation. The analysis relates these changes to a problem of trust associated with mediatization through processes of mediation....

  18. North American Soil Degradation: Processes, Practices, and Mitigating Strategies

    Directory of Open Access Journals (Sweden)

    R. L. Baumhardt

    2015-03-01

    Full Text Available Soil can be degraded by several natural or human-mediated processes, including wind, water, or tillage erosion, and formation of undesirable physical, chemical, or biological properties due to industrialization or use of inappropriate farming practices. Soil degradation occurs whenever these processes supersede natural soil regeneration and, generally, reflects unsustainable resource management that is global in scope and compromises world food security. In North America, soil degradation preceded the catastrophic wind erosion associated with the dust bowl during the 1930s, but that event provided the impetus to improve management of soils degraded by both wind and water erosion. Chemical degradation due to site specific industrial processing and mine spoil contamination began to be addressed during the latter half of the 20th century primarily through point-source water quality concerns, but soil chemical degradation and contamination of surface and subsurface water due to on-farm non-point pesticide and nutrient management practices generally remains unresolved. Remediation or prevention of soil degradation requires integrated management solutions that, for agricultural soils, include using cover crops or crop residue management to reduce raindrop impact, maintain higher infiltration rates, increase soil water storage, and ultimately increase crop production. By increasing plant biomass, and potentially soil organic carbon (SOC concentrations, soil degradation can be mitigated by stabilizing soil aggregates, improving soil structure, enhancing air and water exchange, increasing nutrient cycling, and promoting greater soil biological activity.

  19. Determining potential for microbial atrazine degradation in agricultural drainage ditches.

    Science.gov (United States)

    Tyler, Heather L; Khalid, Sheza; Jackson, Colin R; Moore, Matthew T

    2013-01-01

    Passage of agricultural runoff through vegetated drainage ditches has been shown to reduce the amount of pesticides, such as atrazine, exiting out of agricultural watersheds. Previous studies have found that microbial communities in soil from fields treated with atrazine display enhanced rates of atrazine degradation. However, no studies have examined the potential for atrazine degradation in ditches used to drain these lands. The purpose of the current study was to determine the potential of the drainage ditch soil microbial community for atrazine degradation. Soil samples were collected from fields and adjacent drainage ditches and from nonagricultural land with no previous exposure to atrazine. Polymerase chain reaction analysis indicated widespread presence of atrazine degradation genes in fields and ditches. Potential for degradation was determined by following the decrease of atrazine in spiked soil samples over a 28-d incubation period. Greater than 95% of atrazine was degraded in field and ditch soils, whereas only 68.5 ± 1.3% was degraded in the nonagricultural control. Comparison with autoclaved soil samples indicated the primary mechanism of atrazine degradation in agricultural soils was microbially mediated, whereas its breakdown in nonagricultural soil appeared to be the byproduct of abiotic processes. Therefore, microbial communities in drainage ditch sediments have the potential to play a role in atrazine removal from agricultural runoff by breaking down atrazine deposited in sediments and limiting the amount of this herbicide carried into downstream ecosystems. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  20. A ZnO-doped adhesive reduced collagen degradation favouring dentine remineralization

    National Research Council Canada - National Science Library

    Toledano, Manuel; Yamauti, Monica; Ruiz-Requena, María Estrella; Osorio, Raquel

    2012-01-01

    The objective of the study was to determine the efficacy of a ZnO-doped etch and rinse adhesive in decreasing MMPs-mediated collagen degradation at the resin-dentine hybrid layer, and increasing bonding stability...

  1. Peasant livelihoods and land degradation: Evidence from a ...

    African Journals Online (AJOL)

    Based on the later approach results showed that all wealth groups experienced land degradation on their fields, reflecting the type of land investments made and mediated by levels of access to resources and opportunities. Being poor reduced the ability of most people to invest in land improvement, but being rich did not ...

  2. Sediment transfer-storage relations for degrading alluvial reservoirs

    Science.gov (United States)

    Thomas E. Lisle; Michael Church

    2001-01-01

    The routing of sediment through a drainage system is mediated by transfer-storage relations that are particular to each alluvial reservoir, which contains a channel and floodplain. We propose that sediment transfer rate for a given annual distribution of streamflow is a positive function of sediment storage and examine these relations for degrading reservoirs in which...

  3. Photocatalytic degradation of rhodamine B dye using hydrothermally ...

    Indian Academy of Sciences (India)

    The sunlight mediated photocatalytic degradation of rhodamine B (RB) dye was studied using hydrothermally prepared ZnO ( = 150°C and ∼ 20–30 bars). Zinc chloride was used as the starting material along with sodium hydroxide as a solvent in the hydrothermal synthesis of ZnO. Different durations were tried to ...

  4. Flavopiridol induces cellular FLICE-inhibitory protein degradation by the proteasome and promotes TRAIL-induced early signaling and apoptosis in breast tumor cells.

    Science.gov (United States)

    Palacios, Carmen; Yerbes, Rosario; López-Rivas, Abelardo

    2006-09-01

    The cyclin-dependent kinase inhibitor flavopiridol is undergoing clinical trials as an antitumor drug. We show here that pretreatment of different human breast cancer cell lines with flavopiridol facilitates tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. In breast tumor cells, apoptosis induction by TRAIL is blocked at the level of apical caspase-8 activation. Flavopiridol treatment enhances TRAIL-induced formation of death-inducing signaling complex and early processing of procaspase-8. Subsequently, a TRAIL-induced, mitochondria-operated pathway of apoptosis is activated in cells treated with flavopiridol. Down-regulation of cellular FLICE-inhibitory proteins (c-FLIP; c-FLIP(L) and c-FLIP(S)) is observed on flavopiridol treatment. c-FLIP loss and apoptosis sensitization by flavopiridol are both prevented in cells treated with an inhibitor of the ubiquitin-proteasome system. Furthermore, targeting c-FLIP directly with small interfering RNA oligonucleotides also sensitizes various human breast tumor cell lines to TRAIL-induced apoptosis. Our results indicate that flavopiridol sensitizes breast cancer cells to TRAIL-induced apoptosis by facilitating early events in the apoptotic pathway, and this combination treatment could be regarded as a potential therapeutic tool against breast tumors.

  5. TALSPEAK Solvent Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Leigh R. Martin; Bruce J. Mincher

    2009-09-01

    Understanding the radiolytic degradation behavior of organic molecules involved in new or existing schemes for the recycle of used nuclear fuels is of significant interest for sustaining a closed nuclear fuel cycle. Here we have conducted several lines of investigation to begin understanding the effects of radiolysis on the aqueous phase of the TALSPEAK process for the separation of the trivalent lanthanides from the trivalent actinides. Using the 60-Co irradiator at the INL, we have begun to quantify the effects of radiation on the aqueous phase complexants used in this separation technique, and how this will affect the actinide lanthanide separation factor. In addition we have started to develop methodologies for stable product identification, a key element in determining the degradation pathways. We have also introduced a methodology to investigate the effects of alpha radiolysis that has previously received limited attention.

  6. Nylon separators. [thermal degradation

    Science.gov (United States)

    Lim, H. S.

    1977-01-01

    A nylon separator was placed in a flooded condition in K0H solution and heated at various high temperatures ranging from 60 C to 110 C. The weight decrease was measured and the molecular weight and decomposition product were analyzed to determine: (1) the effect of K0H concentration on the hydrolysis rate; (2) the effect of K0H concentration on nylon degradation; (3) the activation energy at different K0H concentrations; and (4) the effect of oxygen on nylon degradation. The nylon hydrolysis rate is shown to increase as K0H concentration is decreased 34%, giving a maximum rate at about 16%. Separator hydrolysis is confirmed by molecular weight decrease in age of the batteries, and the reaction of nylon with molecular oxygen is probably negligible, compared to hydrolysis. The extrapolated rate value from the high temperature experiment correlates well with experimental values at 35 degrees.

  7. Complex Mediation

    DEFF Research Database (Denmark)

    Bødker, Susanne; Andersen, Peter Bøgh

    2005-01-01

    This article has its starting point in a large number of empirical findings regarding computer-mediated work. These empirical findings have challenged our understanding of the role of mediation in such work; on the one hand as an aspect of communication and cooperation at work and on the other hand...... as an aspect of human engagement with instruments of work. On the basis of previous work in activity-theoretical and semiotic human—computer interaction, we propose a model to encompass both of these aspects. In a dialogue with our empirical findings we move on to propose a number of types of mediation...... that have helped to enrich our understanding of mediated work and the design of computer mediation for such work....

  8. Cysteine cathepsins and extracellular matrix degradation.

    Science.gov (United States)

    Fonović, Marko; Turk, Boris

    2014-08-01

    Cysteine cathepsins are normally found in the lysosomes where they are involved in intracellular protein turnover. Their ability to degrade the components of the extracellular matrix in vitro was first reported more than 25years ago. However, cathepsins were for a long time not considered to be among the major players in ECM degradation in vivo. During the last decade it has, however, become evident that abundant secretion of cysteine cathepsins into extracellular milieu is accompanying numerous physiological and disease conditions, enabling the cathepsins to degrade extracellular proteins. In this review we will focus on cysteine cathepsins and their extracellular functions linked with ECM degradation, including regulation of their activity, which is often enhanced by acidification of the extracellular microenvironment, such as found in the bone resorption lacunae or tumor microenvironment. We will further discuss the ECM substrates of cathepsins with a focus on collagen and elastin, including the importance of that for pathologies. Finally, we will overview the current status of cathepsin inhibitors in clinical development for treatment of ECM-linked diseases, in particular osteoporosis. Cysteine cathepsins are among the major proteases involved in ECM remodeling, and their role is not limited to degradation only. Deregulation of their activity is linked with numerous ECM-linked diseases and they are now validated targets in a number of them. Cathepsins S and K are the most attractive targets, especially cathepsin K as a major therapeutic target for osteoporosis with drugs targeting it in advanced clinical trials. Due to their major role in ECM remodeling cysteine cathepsins have emerged as an important group of therapeutic targets for a number of ECM-related diseases, including, osteoporosis, cancer and cardiovascular diseases. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties. Copyright © 2014 Elsevier B.V. All

  9. Biogeochemical Cycles in Degraded Lands

    Science.gov (United States)

    Davidson, Eric A.; Vieira, Ima Celia G.; ReisdeCarvalho, Claudio Jose; DeanedeAbreuSa, Tatiana; deSouzaMoutinho, Paulo R.; Figueiredo, Ricardo O.; Stone, Thomas A.

    2004-01-01

    The objectives of this project were to define and describe the types of landscapes that fall under the broad category of "degraded lands" and to study biogeochemical cycles across this range of degradation found in secondary forests. We define degraded land as that which has lost part of its capacity of renovation of a productive ecosystem, either in the context of agroecosystems or as native communities of vegetation. This definition of degradation permits evaluation of biogeochemical constraints to future land uses.

  10. Enhanced sonochemical degradation of bisphenol-A by bicarbonate ions.

    Science.gov (United States)

    Pétrier, Christian; Torres-Palma, Ricardo; Combet, Evelyne; Sarantakos, Georgios; Baup, Stéphane; Pulgarin, César

    2010-01-01

    Sonochemical elimination of organic pollutants can take place through two degradation pathways. Molecules with relatively large Henry's law constants will be incinerated inside the cavitation bubble, while nonvolatile molecules with low Henry's law constants will be oxidised by the OH(*) ejected from the bubble of cavitation. Taking bisphenol-A as a model pollutant, this study points out an alternate degradation route, mediated by bicarbonate ions, which is significant for the elimination of micro-pollutants at concentrations present in natural waters. In this process, OH(*) radicals react with bicarbonate ions to produce the carbonate radical, which, unlike the OH(*) radical, can migrate towards the bulk of the solution and therefore induce the degradation of the micro-pollutants present in the bulk solution. As a consequence, initial degradation rate is increased by a factor 3.2 at low concentration of bisphenol-A (0.022 micromol l(-1)) in presence of bicarbonate in water.

  11. L–Carnitine ameliorates the iron mediated DNA degradation in ...

    African Journals Online (AJOL)

    Background: Iron overload is a common complication in β-thalassemia that induces intracellular oxidative stress producing lesions in the DNA including double strand breaks. Objectives: The aim of this study was to evaluate DNA damage in peripheral leukocytes of β -thalassemic children and to investigate its association ...

  12. Statistical modeling for degradation data

    CERN Document Server

    Lio, Yuhlong; Ng, Hon; Tsai, Tzong-Ru

    2017-01-01

    This book focuses on the statistical aspects of the analysis of degradation data. In recent years, degradation data analysis has come to play an increasingly important role in different disciplines such as reliability, public health sciences, and finance. For example, information on products’ reliability can be obtained by analyzing degradation data. In addition, statistical modeling and inference techniques have been developed on the basis of different degradation measures. The book brings together experts engaged in statistical modeling and inference, presenting and discussing important recent advances in degradation data analysis and related applications. The topics covered are timely and have considerable potential to impact both statistics and reliability engineering.

  13. Protein degradation systems in platelets.

    Science.gov (United States)

    Kraemer, B F; Weyrich, A S; Lindemann, S

    2013-11-01

    Protein synthesis and degradation are essential processes that allow cells to survive and adapt to their surrounding milieu. In nucleated cells, the degradation and/or cleavage of proteins is required to eliminate aberrant proteins. Cells also degrade proteins as a mechanism for cell signalling and complex cellular functions. Although the last decade has convincingly shown that platelets synthesise proteins, the roles of protein degradation in these anucleate cytoplasts are less clear. Here we review what is known about protein degradation in platelets placing particular emphasis on the proteasome and the cysteine protease calpain.

  14. Degradation of amyloid beta protein by purified myelin basic protein.

    Science.gov (United States)

    Liao, Mei-Chen; Ahmed, Mahiuddin; Smith, Steven O; Van Nostrand, William E

    2009-10-16

    The progressive accumulation of beta-amyloid (Abeta) in senile plaques and in the cerebral vasculature is the hallmark of Alzheimer disease and related disorders. Impaired clearance of Abeta from the brain likely contributes to the prevalent sporadic form of Alzheimer disease. Several major pathways for Abeta clearance include receptor-mediated cellular uptake, blood-brain barrier transport, and direct proteolytic degradation. Myelin basic protein (MBP) is the major structural protein component of myelin and plays a functional role in the formation and maintenance of the myelin sheath. MBP possesses endogenous serine proteinase activity and can undergo autocatalytic cleavage liberating distinct fragments. Recently, we showed that MBP binds Abeta and inhibits Abeta fibril formation (Hoos, M. D., Ahmed, M., Smith, S. O., and Van Nostrand, W. E. (2007) J. Biol. Chem. 282, 9952-9961; Hoos, M. D., Ahmed, M., Smith, S. O., and Van Nostrand, W. E. (2009) Biochemistry 48, 4720-4727). Here we show that Abeta40 and Abeta42 peptides are degraded by purified human brain MBP and recombinant human MBP, but not an MBP fragment that lacks autolytic activity. MBP-mediated Abeta degradation is inhibited by serine proteinase inhibitors. Similarly, Cos-1 cells expressing MBP degrade exogenous Abeta40 and Abeta42. In addition, we demonstrate that purified MBP also degrades assembled fibrillar Abeta in vitro. Mass spectrometry analysis identified distinct degradation products generated from Abeta digestion by MBP. Lastly, we demonstrate in situ that purified MBP can degrade parenchymal amyloid plaques as well as cerebral vascular amyloid that form in brain tissue of Abeta precursor protein transgenic mice. Together, these findings indicate that purified MBP possesses Abeta degrading activity in vitro.

  15. Tebuconazole photocatalytic degradation kinetics

    OpenAIRE

    Prestes, Thiago de Hermann; Gibbon, Danielle de Oliveira; Lansarin, Marla Azário; Moro, Celso Camilo

    2010-01-01

    The tebuconazole photocatalytic degradation kinetics was studied in a batch reactor using TiO2 (P25-Degussa) as catalyst and a high pressure mercury lamp. The photolysis, adsorption and irradiation effects in the reaction rate were evaluated. Afterward, the suspension catalyst concentration and initial pH to the maximum reaction rate was determined. It was observed that the reaction rate can be approached by a pseudo-first order, with a maximum kinetics constant at 260 mg L-1catalyst concentr...

  16. Outdoor PV Degradation Comparison

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Smith, R. M.; Osterwald, C. R.; Gelak, E.; Kurtz, S. R.

    2011-02-01

    As photovoltaic (PV) penetration of the power grid increases, it becomes vital to know how decreased power output; may affect cost over time. In order to predict power delivery, the decline or degradation rates must be determined; accurately. At the Performance and Energy Rating Testbed (PERT) at the Outdoor Test Facility (OTF) at the; National Renewable Energy Laboratory (NREL) more than 40 modules from more than 10 different manufacturers; were compared for their long-term outdoor stability. Because it can accommodate a large variety of modules in a; limited footprint the PERT system is ideally suited to compare modules side-by-side under the same conditions.

  17. Thermal battery degradation mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Diffuse reflectance IR spectroscopy (DRIFTS) was used to investigate the effect of accelerated aging on LiSi based anodes in simulated MC3816 batteries. DRIFTS spectra showed that the oxygen, carbonate, hydroxide and sulfur content of the anodes changes with aging times and temperatures, but not in a monotonic fashion that could be correlated to phase evolution. Bands associated with sulfur species were only observed in anodes taken from batteries aged in wet environments, providing further evidence for a reaction pathway facilitated by H2S transport from the cathode, through the separator, to the anode. Loss of battery capacity with accelerated aging in wet environments was correlated to loss of FeS2 in the catholyte pellets, suggesting that the major contribution to battery performance degradation results from loss of active cathode material.

  18. Environmental degradation in biocomposites

    CSIR Research Space (South Africa)

    John, Maya J

    2017-06-01

    Full Text Available properties which occurs due to degradation of fibres and matrix. In the case of biocomposites, both natural fibres and the polymer matrix absorb the ultraviolet rays from the sun- light. This leads to changes in the chemical structure of the polymers via... a S ta ge : P ro of C ha pt er N o. : 7 T itl e N am e: R ay P ag e N um be r: 1 D at e: 0 2/ 02 /2 01 7 T im e: 0 1: 14 :0 4 B978-0-08-100793-8.00007-7, 00007 Ray, 978-0-08-100793-8 AUTHOR QUERY FORM Book: Biocomposites for High...

  19. Mediatized play

    DEFF Research Database (Denmark)

    Johansen, Stine Liv

    Children’s play must nowadays be understood as a mediatized field in society and culture. Media – understood in a very broad sense - holds severe explanatory power in describing and understanding the practice of play, since play happens both with, through and inspired by media of different sorts........ In this presentation the case of ‘playing soccer’ will be outlined through its different mediated manifestations, including soccer games and programs on TV, computer games, magazines, books, YouTube videos and soccer trading cards....

  20. Mediating Business

    DEFF Research Database (Denmark)

    and globally. The book explores the history of key innovations and innovators in the business press. It analyzes changes in the discourse of business journalism associated with the growth in business news and the development of new ways of framing business issues and events. Finally, it examines......"Mediating Business" is a study of the expansion of business journalism. Building on evidence from Denmark, Finland, Norway and Sweden, "Mediating Business" is a comparative and multidisciplinary study of one of the major transformations of the mass media and the realm of business - nationally...... the organizational implications of the increased media visibility of business and, in particular, the development of corporate governance and media relations....

  1. Do feather-degrading bacteria affect sexually selected plumage color?

    Science.gov (United States)

    Shawkey, Matthew D.; Pillai, Shreekumar R.; Hill, Geoffrey E.

    2009-01-01

    Models of parasite-mediated sexual selection propose that males with more elaborate sexual traits will have fewer parasites. These models have generally been tested using metazoan or protozoan parasites of the blood, gut, or integument. Fewer studies have examined sexual ornaments in relation to bacterial infections. While most surface bacteria are harmless or beneficial, feather-degrading bacteria may have detrimental effects. In this study, we examined the relationships between overall bacterial load, feather-degrading bacterial load, and sexually selected carotenoid-based plumage color in a wild population of house finches ( Carpodacus mexicanus). We found that males with the redder plumage preferred by females had similar overall bacterial loads, but lower feather-degrading bacterial loads, than males with less red plumage. These data suggest that plumage color can signal abundance of feather-degrading bacteria to potential mates. It remains unclear whether feather-degrading bacteria directly or indirectly affect plumage color, but the observed correlations suggest that feather-degrading bacteria may play some role in sexual selection.

  2. Design of multimodal degradable hydrogels for controlled therapeutic delivery

    Science.gov (United States)

    Kharkar, Prathamesh Madhav

    Hydrogels are of growing interest for the delivery of therapeutics to specific sites in the body. For localized drug delivery, hydrophilic polymeric precursors often are laden with bioactive moieties and then directly injected to the site of interest for in situ gel formation. The release of physically entrapped cargo is dictated by Fickian diffusion, degradation of the drug carrier, or a combination of both. The goal of this work was to design and characterize degradable hydrogel formulations that are responsive to multiple biologically relevant stimuli for degradation-mediated delivery of cargo molecules such as therapeutic proteins, growth factors, and immunomodulatory agents. We began by demonstrating the use of cleavable click linkages formed by Michael-type addition reactions in conjunction with hydrolytically cleavable functionalities for the degradation of injectable hydrogels by endogenous stimuli for controlled protein release. Specifically, the reaction between maleimides and thiols was utilized for hydrogel formation, where thiol selection dictates the degradability of the resulting linkage under thiol-rich reducing conditions. Relevant microenvironments where degradation would occur in vivo include those rich in glutathione (GSH), a tripeptide that is found at elevated concentrations in carcinoma tissues. Degradation of the hydrogels was monitored with rheometry and volumetric swelling measurements. Arylthiol-based thioether succinimide linkages underwent degradation via click cleavage and thiol exchange reaction in the presence of GSH and via ester hydrolysis, whereas alkylthiol-based thioether succinimide linkages only undergo degradation by only ester hydrolysis. The resulting control over the degradation rate within a reducing microenvironment resulted in 2.5 fold differences in the release profile of the model protein, a fluorescently-labeled bovine serum albumin, from dually degradable hydrogels compared to non-degradable hydrogels, where the

  3. Degradation of copepod fecal pellets

    DEFF Research Database (Denmark)

    Poulsen, Louise K.; Iversen, Morten

    2008-01-01

    amount of fecal pellets. The total degradation rate of pellets by the natural plankton community of Oresund followed the phytoplankton biomass, with maximum degradation rate during the spring bloom (2.5 +/- 0.49 d(-1)) and minimum (0.52 +/- 0.14 d(-1)) during late winter. Total pellet removal rate ranged...

  4. Degradation of industrial surfactants by photocatalysis combined with ozonation.

    Science.gov (United States)

    Zsilák, Zoltán; Fónagy, Orsolya; Szabó-Bárdos, Erzsébet; Horváth, Ottó; Horváth, Krisztián; Hajós, Péter

    2014-10-01

    The efficiency of titanium dioxide-mediated photocatalytic degradation of pollutants can be enhanced by combination with another advanced oxidation procedure such as ozonation. Mineralization of hydroxy- and dihydroxybenzenesulfonate based on these methods, both individually and combined, was investigated by monitoring the total organic carbon content, sulfate concentration, pH, high-performance liquid chromatography as well as the absorption spectral changes. The mineralization efficiency of the combined procedure significantly exceeded the sum of those of the individual techniques. The comparison of the disappearance of the starting material and the formation of the sulfate ions indicates that desulfonation is not the primary step of the degradation. Moreover, in the case of the combined method, ring cleavage, and thus, partial mineralization can occur without desulfonation. Efficient degradation of other, widely used industrial surfactants, such as alkylbenzene sulfonates and alkyl ether sulfates, was also achieved by heterogeneous photocatalysis combined with ozonation, offering an applicable method for the removal of these pollutants.

  5. (PAHs) degradation by laccase from a tropical white rot fungus ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... acenapthene, acenaphthylene and benzo[a]anthracene up to 100.0, 98.6, 95.4, 90.1 and 85.3 %, respectively, when the mediator was ... water (Baldrian, 2006), including degradation of lignin and related compounds (Xu, ... buffer (pH 5.0), PAH solution and water with or without the presence of HOBT as the ...

  6. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dwayne C. Kicker

    2001-09-28

    A statistical description of the probable block sizes formed by fractures around the emplacement drifts has been developed for each of the lithologic units of the repository host horizon. A range of drift orientations with the drift azimuth varied in 15{sup o} increments has been considered in the static analysis. For the quasi-static seismic analysis, and the time-dependent and thermal effects analysis, two drift orientations have been considered: a drift azimuth of 105{sup o} and the current emplacement drift azimuth of 75{sup o}. The change in drift profile resulting from progressive deterioration of the emplacement drifts has been assessed both with and without backfill. Drift profiles have been determined for four different time increments, including static (i.e., upon excavation), 200 years, 2,000 years, and 10,000 years. The effect of seismic events on rock fall has been analyzed. Block size distributions and drift profiles have been determined for three seismic levels, including a 1,000-year event, a 5,000-year event, and a 10,000-year event. Data developed in this modeling and analysis activity have been entered into the TDMS (DTN: MO0109RDDAAMRR.003). The following conclusions have resulted from this drift degradation analysis: (1) The available fracture data are suitable for supporting a detailed key block analysis of the repository host horizon rock mass. The available data from the north-south Main Drift and the east-west Cross Drift provide a sufficient representative fracture sample of the repository emplacement drift horizon. However, the Tptpln fracture data are only available from a relatively small section of the Cross Drift, resulting in a smaller fracture sample size compared to the other lithologic units. This results in a lower degree of confidence that the key block data based on the Tptpln data set is actually representative of the overall Tptpln key block population. (2) The seismic effect on the rock fall size distribution for all events

  7. Enhancement of Cellulose Degradation by Cattle Saliva

    Science.gov (United States)

    Seki, Yasutaka; Kikuchi, Yukiko; Kimura, Yoshihiro; Yoshimoto, Ryo; Takahashi, Masatoshi; Aburai, Kenichi; Kanai, Yoshihiro; Ruike, Tatsushi; Iwabata, Kazuki; Sugawara, Fumio; Sakai, Hideki; Abe, Masahiko; Sakaguchi, Kengo

    2015-01-01

    Saccharification of cellulose is a promising technique for producing alternative source of energy. However, the efficiency of conversion of cellulose into soluble sugar using any currently available methodology is too low for industrial application. Many additives, such as surfactants, have been shown to enhance the efficiency of cellulose-to-sugar conversion. In this study, we have examined first whether cattle saliva, as an additive, would enhance the cellulase-catalyzed hydrolysis of cellulose, and subsequently elucidated the mechanism by which cattle saliva enhanced this conversion. Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose. Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva. We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect. Third, the mechanism of cattle saliva mediated enhancement of cellulase activity was probably similar to that of the canonical surfactants. Cattle saliva is available in large amounts easily and cheaply, and it can be used without further purification. Thus, cattle saliva could be a promising additive for efficient saccharification of cellulose on an industrial scale. PMID:26402242

  8. Anaerobic benzene degradation by bacteria

    Science.gov (United States)

    Vogt, Carsten; Kleinsteuber, Sabine; Richnow, Hans‐Hermann

    2011-01-01

    Summary Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen‐dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene‐degrading cultures have been enriched under varying electron acceptor conditions in laboratories around the world, and organisms involved in anaerobic benzene degradation have been identified, indicating that anaerobic benzene degradation is a relevant environmental process. However, only a few benzene degraders have been isolated in pure culture so far, and they all use nitrate as an electron acceptor. In some highly enriched strictly anaerobic cultures, benzene has been described to be mineralized cooperatively by two or more different organisms. Despite great efforts, the biochemical mechanism by which the aromatic ring of benzene is activated in the absence of oxygen is still not fully elucidated; methylation, hydroxylation and carboxylation are discussed as likely reactions. This review summarizes the current knowledge about the ‘key players’ of anaerobic benzene degradation under different electron acceptor conditions and the possible pathway(s) of anaerobic benzene degradation. PMID:21450012

  9. Ascorbic acid induced atrazine degradation.

    Science.gov (United States)

    Hou, Xiaojing; Huang, Xiaopeng; Ai, Zhihui; Zhao, Jincai; Zhang, Lizhi

    2017-04-05

    In this study, we systematically investigated the degradation efficiency and the degradation mechanism of atrazine in the presence of ascorbic acid at different pH values. Although atrazine could be degraded by ascorbic acid in a wide pH range from 4 to 12, its degradation under either acidic (pH≤4) or alkaline (pH≥12) condition was more efficient than under neutral condition (pH=7). This pH dependent atrazine degradation was related to the reactive characteristic of atrazine and the reductive activity of ascorbic acid. The ascorbic acid induced atrazine degradation pathways at different pH were investigated by comparing the atrazine degradation intermediates with liquid chromatography-mass spectrometry, high performance liquid chromatography and ion chromatography. It was found that more products were detected in presence of ascorbic acid at alkaline condition. The appearance of chloride ions confirmed the dechlorination of atrazine by ascorbic acid in the absence of molecular oxygen, while its dechlorination efficiency reached highest at pH 12. These results can shed light on the application of AA for the organic pollutant remediation. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Performance Degradation of LSCF Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Alinger, Matthew

    2013-09-30

    This final report summarizes the progress made during the October 1, 2008 - September 30, 2013 period under Cooperative Agreement DE-NT0004109 for the U. S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled “Performance Degradation of LSCF Cathodes”. The primary objective of this program is to develop a performance degradation mitigation path for high performing, cost-effective solid oxide fuel cells (SOFCs). Strategies to mitigate performance degradation are developed and implemented. In addition, thermal spray manufacturing of SOFCs is explored. Combined, this work establishes a basis for cost-effective SOFC cells.

  11. A porous tissue engineering scaffold selectively degraded by cell-generated reactive oxygen species.

    Science.gov (United States)

    Martin, John R; Gupta, Mukesh K; Page, Jonathan M; Yu, Fang; Davidson, Jeffrey M; Guelcher, Scott A; Duvall, Craig L

    2014-04-01

    Biodegradable tissue engineering scaffolds are commonly fabricated from poly(lactide-co-glycolide) (PLGA) or similar polyesters that degrade by hydrolysis. PLGA hydrolysis generates acidic breakdown products that trigger an accelerated, autocatalytic degradation mechanism that can create mismatched rates of biomaterial breakdown and tissue formation. Reactive oxygen species (ROS) are key mediators of cell function in both health and disease, especially at sites of inflammation and tissue healing, and induction of inflammation and ROS are natural components of the in vivo response to biomaterial implantation. Thus, polymeric biomaterials that are selectively degraded by cell-generated ROS may have potential for creating tissue engineering scaffolds with better matched rates of tissue in-growth and cell-mediated scaffold biodegradation. To explore this approach, a series of poly(thioketal) (PTK) urethane (PTK-UR) biomaterial scaffolds were synthesized that degrade specifically by an ROS-dependent mechanism. PTK-UR scaffolds had significantly higher compressive moduli than analogous poly(ester urethane) (PEUR) scaffolds formed from hydrolytically-degradable ester-based diols (p PEUR scaffolds, the PTK-UR scaffolds were stable under aqueous conditions out to 25 weeks but were selectively degraded by ROS, indicating that their biodegradation would be exclusively cell-mediated. The in vitro oxidative degradation rates of the PTK-URs followed first-order degradation kinetics, were significantly dependent on PTK composition (p PEUR scaffolds. These combined results indicate that ROS-degradable PTK-UR tissue engineering scaffolds have significant advantages over analogous polyester-based biomaterials and provide a robust, cell-degradable substrate for guiding new tissue formation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Chitin Degradation In Marine Bacteria

    DEFF Research Database (Denmark)

    Paulsen, Sara; Machado, Henrique; Gram, Lone

    2015-01-01

    Introduction: Chitin is the most abundant polymer in the marine environment and the second most abundant in nature. Chitin does not accumulate on the ocean floor, because of microbial breakdown. Chitin degrading bacteria could have potential in the utilization of chitin as a renewable carbon...... and nitrogen source in the fermentation industry.Methods: Here, whole genome sequenced marine bacteria were screened for chitin degradation using phenotypic and in silico analyses.Results: The in silico analyses revealed the presence of three to nine chitinases in each strain, however the number of chitinases...... chitin regulatory system.Conclusions: This study has provided insight into the ecology of chitin degradation in marine bacteria. It also served as a basis for choosing a more efficient chitin degrading production strain e.g. for the use of chitin waste for large-scale fermentations....

  13. Plant biomass degradation by fungi.

    Science.gov (United States)

    Mäkelä, Miia R; Donofrio, Nicole; de Vries, Ronald P

    2014-11-01

    Plant biomass degradation by fungi has implications for several fields of science. The enzyme systems employed by fungi for this are broadly used in various industrial sectors such as food & feed, pulp & paper, detergents, textile, wine, and more recently biofuels and biochemicals. In addition, the topic is highly relevant in the field of plant pathogenic fungi as they degrade plant biomass to either gain access to the plant or as carbon source, resulting in significant crop losses. Finally, fungi are the main degraders of plant biomass in nature and as such have an essential role in the global carbon cycle and ecology in general. In this review we provide a global view on the development of this research topic in saprobic ascomycetes and basidiomycetes and in plant pathogenic fungi and link this to the other papers of this special issue on plant biomass degradation by fungi. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Susceptibility of anthocyanins to ex vivo degradation in human saliva.

    Science.gov (United States)

    Kamonpatana, Kom; Giusti, M Mónica; Chitchumroonchokchai, Chureeporn; MorenoCruz, Maria; Riedl, Ken M; Kumar, Purnima; Failla, Mark L

    2012-11-15

    Some fruits and their anthocyanin-rich extracts have been reported to exhibit chemopreventive activity in the oral cavity. Insights regarding oral metabolism of anthocyanins remain limited. Anthocyanin-rich extracts from blueberry, chokeberry, black raspberry, red grape, and strawberry were incubated ex vivo with human saliva from 14 healthy subjects. All anthocyanins were partially degraded in saliva. Degradation of chokeberry anthocyanins in saliva was temperature dependent and decreased by heating saliva to 80 °C and after removal of cells. Glycosides of delphinidin and petunidin were more susceptible to degradation than those of cyanidin, pelargonidin, peonidin and malvidin in both intact and artificial saliva. Stability of di- and tri-saccharide conjugates of anthocyanidins slightly, but significantly, exceeded that of monosaccharide compounds. Ex vivo degradation of anthocyanins in saliva was significantly decreased after oral rinsing with antibacterial chlorhexidine. These results suggest that anthocyanin degradation in the mouth is structure-dependent and largely mediated by oral microbiota. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Degradation of CIGS solar cells

    OpenAIRE

    Theelen, M.J.

    2015-01-01

    Large scale commercial introduction of CIGS photovoltaics (PV) requires modules with low costs, high efficiencies and long and predictable lifetimes. Unfortunately,knowledge about the lifetime of CIGS PV is limited, which is reflected in the results of field studies: degradation rates varying from 0% to about 4% per year have been observed. Since warrantees are given out that the modules will still yield 80% of their initial power after 20 years of field exposure, degradation rates are often ...

  16. Some Misconceptions About Plastic Degradation

    OpenAIRE

    Raouf, Mohamed Imad N. Raouf

    1999-01-01

    In consistence with the importance of implementing best utilization of human resources towards maintaining suitable healthy environment for our next generations, concepts and fundamentals upon which most researches on degradation of plastics are based, as a solution of solid waste reduction, will be discussed. Proper understanding of plastic figures would better utilize human efforts toward useful tasks to control solid waste. Unfortunately, when plastics are made more degradable, they becom...

  17. Anaerobic Degradation of Phenolic Compounds

    OpenAIRE

    Schink, Bernhard; Philipp, Bodo; Jochen A Müller

    2000-01-01

    Mononuclear aromatic compounds are degraded anaerobically through three main pathways, the benzoyl-CoA pathway, the resorcinol pathway, and the phloroglucinol pathway. Various modification reactions channel a broad variety of mononuclear aromatics including aromatic hydrocarbons into either one of these three pathways. Recently, a further pathway was discovered with hydroxyhydroquinone as central intermediate through which especially nitrate-reducing bacteria degrade phenolic compounds and so...

  18. Working session 1: Tubing degradation

    Energy Technology Data Exchange (ETDEWEB)

    Kharshafdjian, G. [Atomic Energy of Canada, Mississauga, Ontario (Canada); Turluer, G. [IPSN, Fontenay-aux-Roses (France)

    1997-02-01

    A general introductory overview of the purpose of the group and the general subject area of SG tubing degradation was given by the facilitator. The purpose of the session was described as to {open_quotes}develop conclusions and proposals on regulatory and technical needs required to deal with the issues of SG tubing degradation.{close_quotes} Types, locations and characteristics of tubing degradation in steam generators were briefly reviewed. The well-known synergistic effects of materials, environment, and stress and strain/strain rate, subsequently referred to by the acronym {open_quotes}MESS{close_quotes} by some of the group members, were noted. The element of time (i.e., evolution of these variables with time) was emphasized. It was also suggested that the group might want to consider the related topics of inspection capabilities, operational variables, degradation remedies, and validity of test data, and some background information in these areas was provided. The presentation given by Peter Millet during the Plenary Session was reviewed; Specifically, the chemical aspects and the degradation from the secondary side of the steam generator were noted. The main issues discussed during the October 1995 EPRI meeting on secondary side corrosion were reported, and a listing of the potential SG tube degradations was provided and discussed.

  19. TAK1 inhibition subverts the osteoclastogenic action of TRAIL while potentiating its antimyeloma effects.

    Science.gov (United States)

    Tenshin, Hirofumi; Teramachi, Jumpei; Oda, Asuka; Amachi, Ryota; Hiasa, Masahiro; Bat-Erdene, Ariunzaya; Watanabe, Keiichiro; Iwasa, Masami; Harada, Takeshi; Fujii, Shiro; Kagawa, Kumiko; Sogabe, Kimiko; Nakamura, Shingen; Miki, Hirokazu; Kurahashi, Kiyoe; Yoshida, Sumiko; Aihara, Kenichi; Endo, Itsuro; Tanaka, Eiji; Matsumoto, Toshio; Abe, Masahiro

    2017-11-14

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) agonists induce tumor-specific apoptosis indicating that they may be an attractive therapeutic strategy against cancers, including multiple myeloma (MM). Osteoclastogenesis is highly induced in MM, which in turn enhances MM growth, thereby forming a vicious cycle between MM tumor expansion and bone destruction. However, the effects of TRAIL on MM-enhanced osteoclastogenesis remain largely unknown. Here, we show that TRAIL induced apoptosis in MM cells, but not in osteoclasts (OCs), and that it rather facilitated receptor activator of NF-κB ligand-induced osteoclastogenesis along with upregulation of cellular FLICE inhibitory protein (c-FLIP). TRAIL did not induce death-inducing signaling complex formation in OCs, but formed secondary complex (complex II) with the phosphorylation of transforming growth factor β-activated kinase-1 (TAK1), and thus activated NF-κB signaling. c-FLIP knockdown abolished complex II formation, thus permitting TRAIL induction of OC cell death. The TAK1 inhibitor LLZ1640-2 abrogated the TRAIL-induced c-FLIP upregulation and NF-κB activation, and triggered TRAIL-induced caspase-8 activation and cell death in OCs. Interestingly, the TRAIL-induced caspase-8 activation caused enzymatic degradation of the transcription factor Sp1 to noticeably reduce c-FLIP expression, which further sensitized OCs to TRAIL-induced apoptosis. Furthermore, the TAK1 inhibition induced antiosteoclastogenic activity by TRAIL even in cocultures with MM cells while potentiating TRAIL's anti-MM effects. These results demonstrated that osteoclastic lineage cells use TRAIL for their differentiation and activation through tilting caspase-8-dependent apoptosis toward NF-κB activation, and that TAK1 inhibition subverts TRAIL-mediated NF-κB activation to resume TRAIL-induced apoptosis in OCs while further enhancing MM cell death in combination with TRAIL.

  20. Redox regulation of insulin degradation by insulin-degrading enzyme.

    Directory of Open Access Journals (Sweden)

    Crystal M Cordes

    Full Text Available Insulin-degrading enzyme (IDE is a thiol sensitive peptidase that degrades insulin and amyloid β, and has been linked to type 2 diabetes mellitus and Alzheimer's disease. We examined the thiol sensitivity of IDE using S-nitrosoglutathione, reduced glutathione, and oxidized glutathione to distinguish the effects of nitric oxide from that of the redox state. The in vitro activity of IDE was studied using either partially purified cytosolic enzyme from male Sprague-Dawley rats, or purified rat recombinant enzyme. We confirm that nitric oxide inhibits the degrading activity of IDE, and that it affects proteasome activity through this interaction with IDE, but does not affect the proteasome directly. Oxidized glutathione inhibits IDE through glutathionylation, which was reversible by dithiothreitol but not by ascorbic acid. Reduced glutathione had no effect on IDE, but reacted with partially degraded insulin to disrupt its disulfide bonds and accelerate its breakdown to trichloroacetic acid soluble fragments. Our results demonstrate the sensitivity of insulin degradation by IDE to the redox environment and suggest another mechanism by which the cell's oxidation state may contribute to the development of, and the link between, type 2 diabetes and Alzheimer's disease.

  1. Cysteine-Accelerated Methanogenic Propionate Degradation in Paddy Soil Enrichment.

    Science.gov (United States)

    Zhuang, Li; Ma, Jinlian; Tang, Jia; Tang, Ziyang; Zhou, Shungui

    2017-05-01

    Propionate degradation is a critical step during the conversion of complex organic matter under methanogenic conditions, and it requires a syntrophic cooperation between propionate-oxidizing bacteria and methanogenic archaea. Increasing evidences suggest that interspecies electron transfer for syntrophic metabolism is not limited to the reducing equivalents of hydrogen and formate. This study tested the ability of an electron shuttle to mediate interspecies electron transfer in syntrophic methanogenesis. We found that cysteine supplementation (100, 400, and 800 μM) accelerated CH 4 production from propionate in paddy soil enrichments. Of the concentrations tested, 100 μM cysteine was the most effective at enhancing propionate degradation to CH 4 , and the rates of CH 4 production and propionate degradation were increased by 109 and 79%, respectively, compared with the cysteine-free control incubations. We eliminated the possibility that the stimulatory effect of cysteine on methanogenesis was attributable to the function of cysteine as a methanogenic substrate in the presence of propionate. The potential catalytic effect involved cysteine serving as an electron carrier to mediate interspecies electron transfer in syntrophic propionate oxidization. The redox potential of cystine/cysteine, which is dependent on the concentration, might be more suitable to facilitate interspecies electron transfer between syntrophic partners at a concentration of 100 μM. Pelotomaculum, obligately syntrophic, propionate-oxidizing bacteria, and hydrogenotrophic methanogens of the family Methanobacteriaceae are predominant in cysteine-mediated methanogenic propionate degradation. The stimulatory effect of cysteine on syntrophic methanogenesis offers remarkable potential for improving the performance of anaerobic digestion and conceptually broaden strategies for interspecies electron transfer in syntrophic metabolism.

  2. HD domain of SAMHD1 influences Vpx-induced degradation at a post-interaction step

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jian; Hou, Jingwei; Zhao, Ke; Yu, Xiao-Fang; Du, Juan, E-mail: jdu@jlu.edu.cn

    2016-02-12

    Primate SAMHD1 proteins are potent inhibitors of viruses, including retroviruses such as HIV-1, HIV-2, and SIV. Vpx, a distinctive viral protein expressed by HIV-2 and some SIVs, induces SAMHD1 degradation by forming a Vpx-DCAF1-based ubiquitin ligase complex. Either the N- or the C-terminus of SAMHD1 is critical for Vpx-induced degradation, depending on the types of SAMHD1 and Vpx proteins. However, it was not fully understood whether other regions of SAMHD1 also contribute to its depletion by Vpx. In the present study, we report that SAMHD1 from chicken (SAMHD1{sub GG}) was not degraded by SIVmac Vpx, in contrast with results for human SAMHD1 (SAMHD1{sub HS}). Results regarding to SAMHD1{sub HS} and SAMHD1{sub GG} fusion proteins supported previous findings that the C-terminus of SAMHD1{sub HS} is essential for Vpx-induced degradation. Internal domain substitution, however, revealed that the HD domain also contributes to Vpx-mediated SAMHD1 degradation. Interestingly, the HD domain influenced Vpx-mediated SAMHD1 degradation without affecting Vpx-SAMHD1 interaction. Therefore, our findings revealed that factors in addition to Vpx-SAMHD1 binding influence the efficiency of Vpx-mediated SAMHD1 degradation. - Highlights: • SAMHD1{sub GG} from chicken could not be depleted by SIVmac Vpx. • The C-terminus of human SAMHD1{sub HS} is critical for its degradation by Vpx. • The HD domain is essential for Vpx-induced degradation of SAMHD1{sub HS}. • Altering the HD domain does not affect Vpx-SAMHD1 interaction.

  3. The co-chaperone p23 is degraded by caspases and the proteasome during apoptosis

    DEFF Research Database (Denmark)

    Mollerup, Jens; Berchtold, Martin Werner

    2005-01-01

    The heat shock protein 90 co-chaperone p23 has recently been shown to be up-regulated in cancer cells and down-regulated in atheroschlerotic plaques. We found that p23 is degraded during apoptosis induced by several stimuli, including Fas and TNFa-receptor activation as well as staurosporine...... treatment. Caspase inhibition protected p23 from degradation in several cell lines. In addition, recombinant caspase-3 and 8 cleaved p23 at Asp 142 generating a degradation product of 18 kDa as seen in apoptotic cells. Truncated p23 is further degraded in a proteasome dependent process during apoptosis....... Furthermore, we found that the anti-aggregating activity of truncated p23 was reduced compared to full length p23 indicating that caspase mediated p23 degradation contributes to protein destabilisation in apoptosis....

  4. Radiation degradation of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Pewlong, W.; Sudatis, B. [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

  5. The Science of Battery Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, John P. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; El Gabaly Marquez, Farid [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; McCarty, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Sugar, Joshua Daniel [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Talin, Alec A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Physics; Fenton, Kyle R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Nagasubramanian, Ganesan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Design and Development; Harris, Charles Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Jungjohann, Katherine Leigh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanosystems Synthesis/Analysis; Hayden, Carl C. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Kliewer, Christopher Jesse [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Combustion Chemistry Dept.; Hudak, Nicholas S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Power Sources Research and Development; Leung, Kevin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanostructure Physics; McDaniel, Anthony H. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Hydrogen and Combustion Technology; Tenney, Craig M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Chemical and Biological Systems; Zavadil, Kevin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Materials Lab.

    2015-01-01

    This report documents work that was performed under the Laboratory Directed Research and Development project, Science of Battery Degradation. The focus of this work was on the creation of new experimental and theoretical approaches to understand atomistic mechanisms of degradation in battery electrodes that result in loss of electrical energy storage capacity. Several unique approaches were developed during the course of the project, including the invention of a technique based on ultramicrotoming to cross-section commercial scale battery electrodes, the demonstration of scanning transmission x-ray microscopy (STXM) to probe lithium transport mechanisms within Li-ion battery electrodes, the creation of in-situ liquid cells to observe electrochemical reactions in real-time using both transmission electron microscopy (TEM) and STXM, the creation of an in-situ optical cell utilizing Raman spectroscopy and the application of the cell for analyzing redox flow batteries, the invention of an approach for performing ab initio simulation of electrochemical reactions under potential control and its application for the study of electrolyte degradation, and the development of an electrochemical entropy technique combined with x-ray based structural measurements for understanding origins of battery degradation. These approaches led to a number of scientific discoveries. Using STXM we learned that lithium iron phosphate battery cathodes display unexpected behavior during lithiation wherein lithium transport is controlled by nucleation of a lithiated phase, leading to high heterogeneity in lithium content at each particle and a surprising invariance of local current density with the overall electrode charging current. We discovered using in-situ transmission electron microscopy that there is a size limit to lithiation of silicon anode particles above which particle fracture controls electrode degradation. From electrochemical entropy measurements, we discovered that entropy

  6. Sterile Inflammation and Degradation Systems in Heart Failure.

    Science.gov (United States)

    Nishida, Kazuhiko; Otsu, Kinya

    2017-04-25

    In most patients with chronic heart failure (HF), levels of circulating cytokines are elevated and the elevated cytokine levels correlate with the severity of HF and prognosis. Various stresses induce subcellular component abnormalities, such as mitochondrial damage. Damaged mitochondria induce accumulation of reactive oxygen species and apoptogenic proteins, and subcellular inflammation. The vicious cycle of subcellular component abnormalities, inflammatory cell infiltration and neurohumoral activation induces cardiomyocyte injury and death, and cardiac fibrosis, resulting in cardiac dysfunction and HF. Quality control mechanisms at both the protein and organelle levels, such as elimination of apoptogenic proteins and damaged mitochondria, maintain cellular homeostasis. An imbalance between protein synthesis and degradation is likely to result in cellular dysfunction and disease. Three major protein degradation systems have been identified, namely the cysteine protease system, autophagy, and the ubiquitin proteasome system. Autophagy was initially believed to be a non-selective process. However, recent studies have described the process of selective mitochondrial autophagy, known as mitophagy. Elimination of damaged mitochondria by autophagy is important for maintenance of cellular homeostasis. DNA and RNA degradation systems also play a critical role in regulating inflammation and maintaining cellular homeostasis mediated by damaged DNA clearance and post-transcriptional regulation, respectively. This review discusses some recent advances in understanding the role of sterile inflammation and degradation systems in HF.

  7. Air pollutants degrade floral scents and increase insect foraging times

    Science.gov (United States)

    Fuentes, Jose D.; Chamecki, Marcelo; Roulston, T.'ai; Chen, Bicheng; Pratt, Kenneth R.

    2016-09-01

    Flowers emit mixtures of scents that mediate plant-insect interactions such as attracting insect pollinators. Because of their volatile nature, however, floral scents readily react with ozone, nitrate radical, and hydroxyl radical. The result of such reactions is the degradation and the chemical modification of scent plumes downwind of floral sources. Large Eddy Simulations (LES) are developed to investigate dispersion and chemical degradation and modification of floral scents due to reactions with ozone, hydroxyl radical, and nitrate radical within the atmospheric surface layer. Impacts on foraging insects are investigated by utilizing a random walk model to simulate insect search behavior. Results indicate that even moderate air pollutant levels (e.g., ozone mixing ratios greater than 60 parts per billion on a per volume basis, ppbv) substantially degrade floral volatiles and alter the chemical composition of released floral scents. As a result, insect success rates of locating plumes of floral scents were reduced and foraging times increased in polluted air masses due to considerable degradation and changes in the composition of floral scents. Results also indicate that plant-pollinator interactions could be sensitive to changes in floral scent composition, especially if insects are unable to adapt to the modified scentscape. The increase in foraging time could have severe cascading and pernicious impacts on the fitness of foraging insects by reducing the time devoted to other necessary tasks.

  8. Polymeric Materials - introduction and degradation

    DEFF Research Database (Denmark)

    Kontogeorgis, Georgios

    1999-01-01

    These notes support the polymer part of the courses 91742 and 91762 (Materials and Corrosion/degradation of materials) taught in IFAKthey contain a short introduction on group contribution methods for estimating properties of polymers, polymer thermodynamics, viscoelasticity models as well...

  9. Degradation of CIGS solar cells

    NARCIS (Netherlands)

    Theelen, M.J.

    2015-01-01

    Large scale commercial introduction of CIGS photovoltaics (PV) requires modules with low costs, high efficiencies and long and predictable lifetimes. Unfortunately,knowledge about the lifetime of CIGS PV is limited, which is reflected in the results of field studies: degradation rates varying from

  10. Abiotic degradation of antibiotic ionophores

    DEFF Research Database (Denmark)

    Bohn, Pernille; Bak, Søren A; Björklund, Erland

    2013-01-01

    Hydrolytic and photolytic degradation were investigated for the ionophore antibiotics lasalocid, monensin, salinomycin, and narasin. The hydrolysis study was carried out by dissolving the ionophores in solutions of pH 4, 7, and 9, followed by incubation at three temperatures of 6, 22, and 28 °C f...... because they absorb light of environmentally irrelevant wavelengths....

  11. Degradable polyethylene: fantasy or reality.

    Science.gov (United States)

    Roy, Prasun K; Hakkarainen, Minna; Varma, Indra K; Albertsson, Ann-Christine

    2011-05-15

    Plastic waste disposal is one of the serious environmental issues being tackled by our society today. Polyethylene, particularly in packaging films, has received criticism as it tends to accumulate over a period of time, leaving behind an undesirable visual footprint. Degradable polyethylene, which would enter the eco-cycle harmlessly through biodegradation would be a desirable solution to this problem. However, the "degradable polyethylene" which is presently being promoted as an environmentally friendly alternative to the nondegradable counterpart, does not seem to meet this criterion. This article reviews the state of the art on the aspect of degradability of polyethylene containing pro-oxidants, and more importantly the effect these polymers could have on the environment in the long run. On exposure to heat, light, and oxygen, these polymers disintegrate into small fragments, thereby reducing or increasing the visual presence. However, these fragments can remain in the environment for prolonged time periods. This article also outlines important questions, particularly in terms of time scale of complete degradation, environmental fate of the polymer residues, and possible accumulation of toxins, the answers to which need to be established prior to accepting these polymers as environmentally benign alternatives to their nondegradable equivalents. It appears from the existing literature that our search for biodegradable polyethylene has not yet been realized.

  12. Methods of degrading napalm B

    Science.gov (United States)

    Tyndall, R.L.; Vass, A.

    1995-09-12

    Methods of degrading napalm and/or trinitrotoluene involve contacting the waste with specific intra-amoebic isolates of ATCC 40908 and/or dispersants derived therefrom. Useful isolates are deposited as ATCC 77529, NAP-1 deposited as ATCC 77526 and 13 deposited as ATCC 77527.

  13. Environmental degradation of structured nanocomposites

    Science.gov (United States)

    2017-03-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release. Distribution is unlimited. ENVIRONMENTAL ...Master’s thesis 4. TITLE AND SUBTITLE ENVIRONMENTAL DEGRADATION OF STRUCTURED NANOCOMPOSITES 5. FUNDING NUMBERS 6. AUTHOR(S) Stephanie M...This study aims to characterize the change in properties as result of environmental factors by examining the effects suffered by epoxy resins

  14. Plant biomass degradation by fungi

    NARCIS (Netherlands)

    Mäkelä, Miia R; Donofrio, Nicole; de Vries, Ronald P; van den Brink, J.

    2014-01-01

    Plant biomass degradation by fungi has implications for several fields of science. The enzyme systems employed by fungi for this are broadly used in various industrial sectors such as food & feed, pulp & paper, detergents, textile, wine, and more recently biofuels and biochemicals. In addition, the

  15. Genetic construction of PCB degraders.

    Science.gov (United States)

    Brenner, V; Arensdorf, J J; Focht, D D

    1994-12-01

    Genetic construction of recombinant strains with expanded degradative abilities may be useful for bioremedation of recalcitrant compounds, such as polychlorinated biphenyls (PCBs). Some degradative genes have been found either on conjugative plasmids or on transposons, which would facilitate their genetic transfer. The catabolic pathway for the total degradation of PCBs is encoded by two different sets of genes that are not normally found in the same organism. The bphABCD genes normally reside on the chromosome and encode for the four enzymes involved in the production of benzoate and chlorobenzoates from the respective catabolism of biphenyl and chlorobiphenyls. The genes encoding for chlorobenzoate catabolism have been found on both plasmids and the chromosome, often in association with transposable elements. Ring fission of chlorobiphenyls and chlorobenzoates involves the meta-fission pathway (3-phenylcatechol 2,3-dioxygenase) and the ortho-fission pathway (chlorocatechol 1,2-dioxygenase), respectively. As the catecholic intermediates of both pathways are frequently inhibitory to each other, incompatibilities result. Presently, all hybrid strains constructed by in vivo matings metabolize simple chlorobiphenyls through complementary pathways by comprising the bph, benzoate, and chlorocatechol genes of parental strains. No strains have yet been verified which are able to utilize PCBs having at least one chlorine on each ring as growth substrates. The possible incompatibilities of hybrid pathways are evaluated with respect to product toxicity, and the efficiency of both in vivo and in vitro genetic methods for the construction of recombinant strains able to degrade PCBs is discussed.

  16. Peasant Livelihoods and Land Degradation

    African Journals Online (AJOL)

    J. A. Yaro

    institutional dynamics, resource diversity, environmental variability and macro level influences on local socio-politico- economic ... the consensus on the link between poverty and environmental degradation. Others have ... Globalisation or interconnectedness of the community to other places through markets, information ...

  17. Competitive interaction degrades target selection: an ERP study.

    Science.gov (United States)

    Hilimire, Matthew R; Mounts, Jeffrey R W; Parks, Nathan A; Corballis, Paul M

    2009-09-01

    Localized attentional interference (LAI) occurs when attending to a visual object degrades processing of nearby objects. Competitive interaction accounts of LAI explain the phenomenon as the result of competition among objects for representation in extrastriate cortex. Here, we examined the N2pc component of the event-related potential (ERP) as a likely neural correlate of LAI. In Experiment 1, participants responded to the orientation of a target while ignoring a nearby decoy. At small target-decoy separations, N2pc amplitude was attenuated whereas the amplitude of a later, positive component (Ptc) was potentiated. Experiment 2 ruled out sensory explanations of these effects. The N2pc results are consistent with the idea that spatially mediated competition for representation in extrastriate cortex degrades target selection. Moreover, the Ptc may reflect a bias signal needed to resolve the competition at smaller target-decoy separations.

  18. CREB activates proteasomal degradation of DSCR1/RCAN1.

    Science.gov (United States)

    Seo, Su Ryeon; Chung, Kwang Chul

    2008-06-11

    The cyclic AMP response element-binding protein (CREB) is involved in the development and function of the nervous system. Here, we find that CREB decreases the protein level of Regulator of Calcineurin Activity 1 (RCAN1/DSCR1/MCIP1), which is overexpressed in the brain of Down Syndrome (DS) patients. Decrease of RCAN1 by CREB was blocked by proteasome inhibitors, indicating that this decrease is mediated by the ubiquitin-proteasome pathway. Furthermore, we found that the ability of CREB to activate the degradation of RCAN1 depends on its transcriptional activation. Consistently, CREB-enhanced the ubiquitination and turnover rate of RCAN1. Our results reveal a new regulatory role for CREB in DS pathology through the proteasomal degradation of RCAN1.

  19. The dual regulation of substance P-mediated inflammation via human synovial mast cells in rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Yuki Okamura

    2017-09-01

    Conclusions: Activated synovial MCs may rapidly degrade SP, which may downregulate the SP-mediated activation of synoviocytes in RA. On the other hand, SP activates MCs to induce inflammatory mediators, suggesting the dual regulation of SP-mediated inflammation by MCs in RA.

  20. Characterization of the degradation mechanisms of lysine-derived aliphatic poly(ester urethane) scaffolds.

    Science.gov (United States)

    Hafeman, Andrea E; Zienkiewicz, Katarzyna J; Zachman, Angela L; Sung, Hak-Joon; Nanney, Lillian B; Davidson, Jeffrey M; Guelcher, Scott A

    2011-01-01

    Characterization of the degradation mechanism of polymeric scaffolds and delivery systems for regenerative medicine is essential to assess their clinical applicability. Key performance criteria include induction of a minimal, transient inflammatory response and controlled degradation to soluble non-cytotoxic breakdown products that are cleared from the body by physiological processes. Scaffolds fabricated from biodegradable poly(ester urethane)s (PEURs) undergo controlled degradation to non-cytotoxic breakdown products and support the ingrowth of new tissue in preclinical models of tissue regeneration. While previous studies have shown that PEUR scaffolds prepared from lysine-derived polyisocyanates degrade faster under in vivo compared to in vitro conditions, the degradation mechanism is not well understood. In this study, we have shown that PEUR scaffolds prepared from lysine triisocyanate (LTI) or a trimer of hexamethylene diisocyanate (HDIt) undergo hydrolytic, esterolytic, and oxidative degradation. Hydrolysis of ester bonds to yield α-hydroxy acids is the dominant mechanism in buffer, and esterolytic media modestly increase the degradation rate. While HDIt scaffolds show a modest (PEUR scaffolds and delivery systems for tissue regeneration, this promising class of biomaterials has a limited regulatory history. Elucidation of the macrophage-mediated oxidative mechanism by which LTI scaffolds degrade in vivo provides key insights into the ultimate fate of these materials when injected into the body. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Combined Biological and Chemical Mechanisms for Degradation of Insensitive Munitions in the Presence of Alternate Explosives

    Science.gov (United States)

    2017-06-21

    research was to quantify the rate and extent to which IM can be transformed by combined biological and chemical reactions with iron and Fe(III...in battle conditions. The objective of this research was to quantify the rate and extent to which IM can be transformed by combined biological and...MATERIALS AND METHODS ................................................................. 10 III. IRON AND ELECTRON SHUTTLE MEDIATED DEGRADATION OF

  2. Context Memory Formation Requires Activity-Dependent Protein Degradation in the Hippocampus

    Science.gov (United States)

    Cullen, Patrick K.; Ferrara, Nicole C.; Pullins, Shane E.; Helmstetter, Fred J.

    2017-01-01

    Numerous studies have indicated that the consolidation of contextual fear memories supported by an aversive outcome like footshock requires de novo protein synthesis as well as protein degradation mediated by the ubiquitin-proteasome system (UPS). Context memory formed in the absence of an aversive stimulus by simple exposure to a novel…

  3. Metalloproteinases in corneal diseases: degradation and processing.

    Science.gov (United States)

    Sakimoto, Tohru; Sawa, Mitsuru

    2012-11-01

    Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases with the potential to degrade all types of extracellular matrix. The ADAM (a disintegrin and metalloproteinase) family of peptidases was recently identified as cleaving the extracellular domain of transmembrane proteins. This was termed ectodomain shedding. We investigated the MMP expression in patients with corneal diseases and the potential role of ADAMs in corneal pathophysiology. We detected upregulation of the active form of MMP-2 and MMP-9 in the tear fluid from patients with corneal melting or recurrent corneal erosion. Using human corneal epithelial cells, we observed ADAM17-dependent ectodomain shedding of soluble tumor necrosis factor receptor 1 and soluble interleukin-6 (IL-6) receptor (sIL-6R). The production of sIL-6R was also induced by messenger RNA splicing in the human corneal epithelial cells. IL-6/sIL-6R-induced signal transducer and activator of transcription 3 phosphorylation was observed in cultured human corneal fibroblasts, suggesting that IL-6 trans-signaling induced inflammatory cellular signaling in the human corneal fibroblasts. We demonstrated that MMPs are significantly upregulated in collagen-destructive disorders of the cornea. Additionally, we observed that ectodomain shedding by ADAMs in corneal epithelial cells mediated the production of soluble cytokine receptors. Trans-signaling of IL-6 can induce an inflammatory response in corneal stroma, indicating the significance of IL-6 trans-signaling in ocular surface inflammation. Thus, MMPs and ADAMs play an important role in the pathophysiology of corneal diseases.

  4. Bacterial degradation of recalcitrant PAHs: metabolic studies and application to pyrene degradation in a freshwater sediment

    Energy Technology Data Exchange (ETDEWEB)

    Jouanneau, Y.; Demaneche, S.; Meyer, Ch.; Willison, J.C. [CEA-Grenoble, UMR 5092 CNRS-CEA-UJF, 38 - Grenoble (France)

    2005-07-01

    Cost-effective bio-remediation strategies have been proposed to remove toxic chemicals, including polycyclic aromatic hydrocarbons (PAHs), from contaminated sites. However, the efficiency of these strategies is often limited, due to the resistance of certain chemicals to microbial degradation. Our studies deal with the biodegradation of four-ring PAHs using two recently isolated bacteria, Mycobacterium strain 6PY1, which can mineralize pyrene and phenanthrene, and Sphingomonas strain CHY-1, which mineralizes chrysene and various three-ring PAHs. The metabolic pathways for the biodegradation of PAHs have been investigated using GC-MS to identify and assay metabolites. Also, several enzymes involved in PAH catabolism have been identified by a combination of proteomic and genetic approaches. In Mycobacterium 6PY1, two ring-hydroxylating di-oxygenases which catalyze the initial attack of PAHs have been overproduced in E. coli, isolated and characterized. The selectivity of the two enzymes showed marked differences, since one di-oxygenase preferentially oxidized 2- or 3- ring PAHs whereas the other attacked pyrene and 3-ring PAHs exclusively. In Sphingomonas CHY-1, a single di-oxygenase, called PhnI, was found to convert seven PAHs, including chrysene, to the corresponding dihydro-diols. It is the first enzyme to be described which is able to attack the four-ring PAHs chrysene and benz[a]anthracene.. The fate of pyrene was examined in a sediment taken from a freshwater lake of the French Alps. Experiments were carried out in microcosms containing a layer of sediment which was spiked with {sup 14}C-pyrene. Pyrene mineralization was monitored over 61 days by measuring the {sup 14}CO{sub 2} evolved from the microcosms. Some microcosms were planted with young reeds (Phragmites australis), while other were inoculated with Mycobacterium 6PY1. P. australis reeds promoted a significant increase of pyrene degradation, which most likely resulted from a root-mediated increase of

  5. Radiation degradation of silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Wachiraporn Pewlong; Boonya Sudatis [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-09-01

    Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated in the dose range up to 2500 kGy using an electron beam accelerator to apply the radiation degradation technique as a means to solubilize fibroin. The tensile strength of irradiated fibroin fiber decreased with increasing dose and the presence of oxygen in the irradiation atmosphere enhanced the degradation. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: calcium chloride solution (CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O = 1 : 2 : 8 in mole ratio), hydrochloric acid (0.5N) and distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water-soluble protein was extracted by distilled water. (author)

  6. Degradation studies of SMRM teflon

    Science.gov (United States)

    Liang, Ranty H.; Oda, Keri L.; Chung, Shirley Y.; Gupta, Amitava

    1986-01-01

    Teflon samples returned from the Solar Max Satellite (SMS) suffered noticeable damage such as cracking and yellowing. This is in contrast to teflon exposed aboard STS-5 and STS-8 which showed no detectable changes. Selected teflon tape samples from SMS were studied to evaluate the extent and mechanism of degradation. ESCA studies revealed that these teflon samples contain hydrocarbon segments which were susceptible to oxygen atom degradation. Mechanical measurements also showed bulk property changes as a result of LEO exposure. A molecular model of material and energetic oxygen atom interaction was proposed. SMS data and the importance of developing correlation between accelerated exposure data from STS and ground-based testing and real time data will be presented.

  7. Degradable Polymers for Gene Delivery

    Science.gov (United States)

    Sunshine, Joel; Bhise, Nupura; Green, Jordan J.

    2014-01-01

    Degradable polymers were synthesized that self-assemble with DNA to form particles that are effective for gene delivery. Small changes to polymer synthesis conditions, particle formulation conditions, and polymer structure led to significant changes to efficacy in a cell-type dependent manner. Polymers presented here are more effective than Lipofectamine 2000 or polyethylenimine for gene delivery to cancerous fibroblasts or human primary fibroblasts. These materials may be useful for cancer therapeutics and regenerative medicine. PMID:19964958

  8. Thermal degradation of injectable epinephrine.

    Science.gov (United States)

    Church, W H; Hu, S S; Henry, A J

    1994-05-01

    The degradation of epinephrine in USP injectable cartridges was investigated under different heating conditions. Epinephrine (EPI) and EPI sulfonic acid (EPI-SA) levels in 1:10,000 (0.1 mg/mL) EPI injectable solutions subjected to either cyclical (65 degrees C for 8 hr/d for 4 to 12 weeks) or constant (65 degrees C for 7 days) heating were determined using high-pressure liquid chromatography with diode array and electrochemical detection. Constant (169 total hours of heat exposure) heating resulted in complete degradation of both compounds and dark brown discoloration of the solution. Cyclical heating (672 total hours of heat exposure) resulted in a 31% reduction in EPI concentration and a 225% increase in EPI-SA concentration with no discoloration of the solution. In laboratory-prepared solutions, the degradation of EPI and the formation of EPI-SA was found to be dependent on sodium metabisulfite concentration and the duration of cyclical heating. These results indicate that the thermal stability of EPI and the formation of EPI-SA depends on the method of heat exposure and the amount of bisulfite present in the solution.

  9. Fracture Fluid Additive and Formation Degradations

    Science.gov (United States)

    This presentation is on reactions that describe the degradation of fracturing fluids & formations during the hydraulic fracturing process & the clean‐up period. It contains a description of primary chemical reaction controls, & common degradation reactions

  10. Isolation and characterization of two malathion- degrading ...

    African Journals Online (AJOL)

    Jane Erike-Etchie

    2016-08-03

    Aug 3, 2016 ... degrade malathion, diazinon and chlorpyrifos completely and no significant degradation for chlorpyrifos. .... Cycle Sequencing Kit with AmpliTaq DNA polymerase, following the protocols ...... Forensic Sci. Int. 36:97-100.

  11. Soil Degradation: A North American perspective

    Science.gov (United States)

    Soil can be degraded through erosion and formation of undesirable physical, chemical, or biological properties due to industrialization or use of inappropriate farming practices that supersede natural regeneration. Soil degradation reflects unsustainable resource management that is global in scope a...

  12. TMEM129 is a Derlin-1 associated ERAD E3 ligase essential for virus-induced degradation of MHC-I

    DEFF Research Database (Denmark)

    van den Boomen, Dick J H; Timms, Richard T; Grice, Guinevere L

    2014-01-01

    The US11 gene product of human cytomegalovirus promotes viral immune evasion by hijacking the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway. US11 initiates dislocation of newly translocated MHC I from the ER to the cytosol for proteasome-mediated degradation. Despite the critic...

  13. Degradation analysis of thin film photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Radue, C., E-mail: chantelle.radue@nmmu.ac.z [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Dyk, E.E. van [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2009-12-01

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P{sub MAX}) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 approx30% and a total degradation of approx42%. For Si-2 the initial P{sub MAX} was 7.93 W, with initial light-induced degradation of approx10% and a total degradation of approx17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  14. Microbial degradation of textile industrial effluents | Palamthodi ...

    African Journals Online (AJOL)

    In this work, the in situ degradation of textile industrial effluent was carried out. The degradation of two different dyes, blue and green colour has ... The degradation of dye was confirmed via the decolourisation assay and by the measurement of COD and BOD values. A trickling bed reactor was designed and the treatment of ...

  15. Nylon biodegradation by lignin-degrading fungi.

    OpenAIRE

    Deguchi, T; Kakezawa, M; T. Nishida

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively.

  16. Nylon biodegradation by lignin-degrading fungi.

    Science.gov (United States)

    Deguchi, T; Kakezawa, M; Nishida, T

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degraded nylon-66 membrane under ligninolytic conditions. Nuclear magnetic resonance analysis showed that four end groups, CHO, NHCHO, CH3, and CONH2, were formed in the biodegraded nylon-66 membranes, suggesting that nylon-66 was degraded oxidatively. PMID:8979361

  17. Brucella infection inhibits macrophages apoptosis via Nedd4-dependent degradation of calpain2.

    Science.gov (United States)

    Cui, Guimei; Wei, Pan; Zhao, Yuxi; Guan, Zhenhong; Yang, Li; Sun, Wanchun; Wang, Shuangxi; Peng, Qisheng

    2014-11-07

    The calcium-dependent protease calpain2 is involved in macrophages apoptosis. Brucella infection-induced up-regulation of intracellular calcium level is an essential factor for the intracellular survival of Brucella within macrophages. Here, we hypothesize that calcium-dependent E3 ubiquitin ligase Nedd4 ubiquitinates calpain2 and inhibits Brucella infection-induced macrophage apoptosis via degradation of calpain2.Our results reveal that Brucella infection induces increases in Nedd4 activity in an intracellular calcium dependent manner. Furthermore, Brucella infection-induced degradation of calpain2 is mediated by Nedd4 ubiquitination of calpain2. Brucella infection-induced calpain2 degradation inhibited macrophages apoptosis. Treatment of Brucella infected macrophages with calcium chelator BAPTA or Nedd4 knock-down decreased Nedd4 activity, prevented calpain2 degradation, and resulted in macrophages apoptosis. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Insights into lignin degradation and its potential industrial applications.

    Science.gov (United States)

    Abdel-Hamid, Ahmed M; Solbiati, Jose O; Cann, Isaac K O

    2013-01-01

    Lignocellulose is an abundant biomass that provides an alternative source for the production of renewable fuels and chemicals. The depolymerization of the carbohydrate polymers in lignocellulosic biomass is hindered by lignin, which is recalcitrant to chemical and biological degradation due to its complex chemical structure and linkage heterogeneity. The role of fungi in delignification due to the production of extracellular oxidative enzymes has been studied more extensively than that of bacteria. The two major groups of enzymes that are involved in lignin degradation are heme peroxidases and laccases. Lignin-degrading peroxidases include lignin peroxidase (LiP), manganese peroxidase (MnP), versatile peroxidase (VP), and dye-decolorizing peroxidase (DyP). LiP, MnP, and VP are class II extracellular fungal peroxidases that belong to the plant and microbial peroxidases superfamily. LiPs are strong oxidants with high-redox potential that oxidize the major non-phenolic structures of lignin. MnP is an Mn-dependent enzyme that catalyzes the oxidation of various phenolic substrates but is not capable of oxidizing the more recalcitrant non-phenolic lignin. VP enzymes combine the catalytic activities of both MnP and LiP and are able to oxidize Mn(2+) like MnP, and non-phenolic compounds like LiP. DyPs occur in both fungi and bacteria and are members of a new superfamily of heme peroxidases called DyPs. DyP enzymes oxidize high-redox potential anthraquinone dyes and were recently reported to oxidize lignin model compounds. The second major group of lignin-degrading enzymes, laccases, are found in plants, fungi, and bacteria and belong to the multicopper oxidase superfamily. They catalyze a one-electron oxidation with the concomitant four-electron reduction of molecular oxygen to water. Fungal laccases can oxidize phenolic lignin model compounds and have higher redox potential than bacterial laccases. In the presence of redox mediators, fungal laccases can oxidize non

  19. An enzyme immunoassay for polymorphonuclear leucocyte-mediated fibrinogenolysis

    NARCIS (Netherlands)

    Bos, R.; Leuven, C.J.M. van; Stolk, J.; Hiemstra, P.S.; Ronday, H.K.; Nieuwenhuizen, W.

    1997-01-01

    Upon stimulation, polymorphonuclear leucocytes (PMNs) release potent serine proteases, i.e. elastase, cathepsin C and proteinase 3, which contribute to the degradation of tissue and plasma components. Here, we describe the development of a plasma test to assess PMN-mediated fibrinogenolysis as a

  20. Auxin-dependent compositional change in Mediator in ARF7- and ARF19-mediated transcription.

    Science.gov (United States)

    Ito, Jun; Fukaki, Hidehiro; Onoda, Makoto; Li, Lin; Li, Chuanyou; Tasaka, Masao; Furutani, Masahiko

    2016-06-07

    Mediator is a multiprotein complex that integrates the signals from transcription factors binding to the promoter and transmits them to achieve gene transcription. The subunits of Mediator complex reside in four modules: the head, middle, tail, and dissociable CDK8 kinase module (CKM). The head, middle, and tail modules form the core Mediator complex, and the association of CKM can modify the function of Mediator in transcription. Here, we show genetic and biochemical evidence that CKM-associated Mediator transmits auxin-dependent transcriptional repression in lateral root (LR) formation. The AUXIN/INDOLE 3-ACETIC ACID 14 (Aux/IAA14) transcriptional repressor inhibits the transcriptional activity of its binding partners AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19 by making a complex with the CKM-associated Mediator. In addition, TOPLESS (TPL), a transcriptional corepressor, forms a bridge between IAA14 and the CKM component MED13 through the physical interaction. ChIP assays show that auxin induces the dissociation of MED13 but not the tail module component MED25 from the ARF7 binding region upstream of its target gene. These findings indicate that auxin-induced degradation of IAA14 changes the module composition of Mediator interacting with ARF7 and ARF19 in the upstream region of their target genes involved in LR formation. We suggest that this regulation leads to a quick switch of signal transmission from ARFs to target gene expression in response to auxin.

  1. Advanced oxidation kinetics and mechanism of preservative propylparaben degradation in aqueous suspension of TiO2 and risk assessment of its degradation products.

    Science.gov (United States)

    Fang, Hansun; Gao, Yanpeng; Li, Guiying; An, Jibin; Wong, Po-Keung; Fu, Haiying; Yao, Side; Nie, Xiangping; An, Taicheng

    2013-03-19

    The absolute kinetic rate constants of propylparaben (PPB) in water with different free radicals were investigated, and it was found that both hydroxyl radicals (HO(•)) and hydrated electrons could rapidly react with PPB. The advanced oxidation kinetics and mechanisms of PPB were investigated using photocatalytic process as a model technology, and the degradation was found to be a pseudo-first-order model. Oxidative species, particularly HO(•), were the most important reactive oxygen species mediating photocatalytic degradation of PPB, and PPB degradation was found to be significantly affected by pH because it was controlled by the radical reaction mechanism and was postulated to occur primarily via HO(•)-addition or H-abstraction reactions on the basis of pulse radiolysis measurements and observed reaction products. To investigate potential risk of PPB to humans and aqueous organisms, the estrogenic assays and bioassays were performed using 100 μM PPB solution degraded by photocatalysis at specific intervals. The estrogenic activity decreased as PPB was degraded, while the acute toxicity at three trophic levels first increased slowly and then decreased rapidly as the total organic carbon decreased during photocatalytic degradation.

  2. The T7-related Pseudomonas putida phage φ15 displays virion-associated biofilm degradation properties.

    Directory of Open Access Journals (Sweden)

    Anneleen Cornelissen

    Full Text Available Formation of a protected biofilm environment is recognized as one of the major causes of the increasing antibiotic resistance development and emphasizes the need to develop alternative antibacterial strategies, like phage therapy. This study investigates the in vitro degradation of single-species Pseudomonas putida biofilms, PpG1 and RD5PR2, by the novel phage ϕ15, a 'T7-like virus' with a virion-associated exopolysaccharide (EPS depolymerase. Phage ϕ15 forms plaques surrounded by growing opaque halo zones, indicative for EPS degradation, on seven out of 53 P. putida strains. The absence of haloes on infection resistant strains suggests that the EPS probably act as a primary bacterial receptor for phage infection. Independent of bacterial strain or biofilm age, a time and dose dependent response of ϕ15-mediated biofilm degradation was observed with generally a maximum biofilm degradation 8 h after addition of the higher phage doses (10(4 and 10(6 pfu and resistance development after 24 h. Biofilm age, an in vivo very variable parameter, reduced markedly phage-mediated degradation of PpG1 biofilms, while degradation of RD5PR2 biofilms and ϕ15 amplification were unaffected. Killing of the planktonic culture occurred in parallel with but was always more pronounced than biofilm degradation, accentuating the need for evaluating phages for therapeutic purposes in biofilm conditions. EPS degrading activity of recombinantly expressed viral tail spike was confirmed by capsule staining. These data suggests that the addition of high initial titers of specifically selected phages with a proper EPS depolymerase are crucial criteria in the development of phage therapy.

  3. Enzymatic degradation of polycaprolactone-gelatin blend

    Science.gov (United States)

    Banerjee, Aditi; Chatterjee, Kaushik; Madras, Giridhar

    2015-04-01

    Blends of polycaprolactone (PCL), a synthetic polymer and gelatin, natural polymer offer a optimal combination of strength, water wettability and cytocompatibility for use as a resorbable biomaterial. The enzymatic degradation of PCL, gelatin and PCL-gelatin blended films was studied in the presence of lipase (Novozym 435, immobilized) and lysozyme. Novozym 435 degraded the PCL films whereas lysozyme degraded the gelatin. Though Novozym 435 and lysozyme individually could degrade PCL-gelatin blended films, the combination of these enzymes showed the highest degradation of these blended films. Moreover, the enzymatic degradation was much faster when fresh enzymes were added at regular intervals. The changes in physico-chemical properties of polymer films due to degradation were studied by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. These results have important implications for designing resorbable biomedical implants.

  4. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS.

    Energy Technology Data Exchange (ETDEWEB)

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-03-22

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits.

  5. Using microorganisms to aid in hydrocarbon degradation

    Energy Technology Data Exchange (ETDEWEB)

    Black, W.; Zamora, J. (Middle Tennessee State Univ., Murfreesboro (United States))

    1993-04-01

    Aliphatic hydrocarbons are threatening the potable water supply and the aquatic ecosystem. Given the right microbial inhabitant(s), a large portion of these aliphatic hydrocarbons could be biodegraded before reaching the water supply. The authors' purpose is to isolate possible oil-degrading organisms. Soil samples were taken from hydrocarbon-laden soils at petroleum terminals, a petroleum refinery waste-treatment facility, a sewage-treatment plant grease collector, a site of previous bioremediation, and various other places. Some isolates known to be good degraders were obtained from culture collection services. These samples were plated on a 10w-30 multigrade motor oil solid medium to screen for aliphatic hydrocarbon degraders. The degrading organisms were isolated, identified, and tested (CO[sub 2] evolution, BOD, and COD) to determine the most efficient degrader(s). Thirty-seven organisms were tested, and the most efficient degraders were Serratia marcescens, Escherichia coli, and Enterobacter agglomerans.

  6. Polycyclic aromatic hydrocarbons (PAHs) enrich their degrading genera and genes in human-impacted aquatic environments.

    Science.gov (United States)

    Yuan, Ke; Chen, Baowei; Qing, Qing; Zou, Shichun; Wang, Xiaowei; Luan, Tiangang

    2017-11-01

    Bacterial degradation is an important clearance pathway for organic contaminants from highly human-impacted environments. However, it is not fully understood how organic contaminants are selected for degradation by bacteria and genes in aquatic environments. In this study, PAH degrading bacterial genera and PAH-degradation-related genes (PAHDGs) in sediments collected from the Pearl River (PR), the Pearl River Estuary (PRE) and the South China Sea (SCS), among which there were distinct differences in anthropogenic impact, were analyzed using metagenomic approaches. The diversity and abundance of PAH degrading genera and PAHDGs in the PR were substantially higher than those in the PRE and the SCS and were significantly correlated with the total PAH concentration. PAHDGs involved with the three key processes of PAH degradation (ring cleavage, side chain and central aromatic processes) were significantly correlated with each other in the sediments. In particular, plasmid-related PAHDGs were abundant in the PR sediments, indicating plasmid-mediated horizontal transfer of these genes between bacteria or the overgrowth of the bacteria containing these plasmids under the stresses of PAHs. Our results suggest that PAH degrading bacteria and genes were rich in PAH-polluted aquatic environments, which could facilitate the removal of PAHs by bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Degradation and inactivation of Shiga toxins by nitrogen gas plasma.

    Science.gov (United States)

    Sakudo, Akikazu; Imanishi, Yuichiro

    2017-12-01

    Shiga toxin (Stx)-producing Escherichia coli (STEC) leads to food poisoning by causing hemorrhagic colitis and hemolytic uremic syndrome. Some STEC produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2), a relatively stable protein toxin, necessitating the development of an efficient inactivation method. Here we applied a nitrogen gas plasma apparatus to the inactivation of Stx. Samples of Stx1 and Stx2 were treated with a nitrogen gas plasma generated by a plasma device using a short high-voltage pulse applied by a static induction thyristor power supply at 1.5 kpps (kilo pulse per second). The recovered Stx samples were then analyzed for immunological and biological activities. Immunochromatography demonstrated that Stx1 and Stx2 were degraded by the gas plasma. Quantification by enzyme-linked immunosorbent assay (ELISA) showed that both toxins were efficiently degraded to less than 1/10th of their original concentration within 5 min of treatment. Western blotting further showed the gas plasma treatment degraded the A subunit, which mediates the toxicity of Stx. Moreover, an assay using HEp-2 cells as an index of cytotoxicity showed that gas plasma treatment reduced the toxic activity of Stx. Therefore, nitrogen gas plasma might be an efficient method for the inactivation of Stx.

  8. Light-induced protein degradation in human-derived cells.

    Science.gov (United States)

    Sun, Wansheng; Zhang, Wenyao; Zhang, Chao; Mao, Miaowei; Zhao, Yuzheng; Chen, Xianjun; Yang, Yi

    2017-05-27

    Controlling protein degradation can be a valuable tool for posttranslational regulation of protein abundance to study complex biological systems. In the present study, we designed a light-switchable degron consisting of a light oxygen voltage (LOV) domain of Avena sativa phototropin 1 (AsLOV2) and a C-terminal degron. Our results showed that the light-switchable degron could be used for rapid and specific induction of protein degradation in HEK293 cells by light in a proteasome-dependent manner. Further studies showed that the light-switchable degron could also be utilized to mediate the degradation of secreted Gaussia princeps luciferase (GLuc), demonstrating the adaptability of the light-switchable degron in different types of protein. We suggest that the light-switchable degron offers a robust tool to control protein levels and may serves as a new and significant method for gene- and cell-based therapies. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. New insights into endocannabinoid degradation and its therapeutic potential.

    Science.gov (United States)

    Bari, M; Battista, N; Fezza, F; Gasperi, V; Maccarrone, M

    2006-03-01

    Endocannabinoids are amides, esters and ethers of long chain polyunsaturated fatty acids, which act as new lipidic mediators. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol (2-AG) are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of (-)-Delta9-tetrahydrocannabinol (THC), the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA and 2-AG at their receptors is limited by cellular uptake through an anandamide membrane transporter (AMT), followed by intracellular degradation. A fatty acid amide hydrolase (FAAH) is the main AEA hydrolase, whereas a monoacylglycerol lipase (MAGL) is critical in degrading 2-AG. Here, we will review growing evidence that demonstrates that these hydrolases are pivotal regulators of the endogenous levels of AEA and 2-AG in vivo, overall suggesting that specific inhibitors of AMT, FAAH or MAGL may serve as attractive therapeutic targets for the treatment of human disorders. Recently, the N-acylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD), which synthesizes AEA from N-arachidonoylphosphatidylethanolamine (NArPE), and the diacylglycerol lipase (DAGL), which generates 2-AG from diacylglycerol (DAG) substrates, have been characterized. The role of these synthetic routes in maintaining the endocannabinoid tone in vivo will be discussed. Finally, the effects of inhibitors of endocannabinoid degradation in animal models of human disease will be reviewed, with an emphasis on their ongoing applications in anxiety, cancer and neurodegenerative disorders.

  10. Neutral endopeptidase 24.11 is important for the degradation of both endogenous and exogenous glucagon in anesthetized pigs

    DEFF Research Database (Denmark)

    Trebbien, Ramona; Klarskov, Letty; Olesen, Mette

    2004-01-01

    Glucagon has a short plasma t(1/2) in vivo, with renal extraction playing a major role in its elimination. Glucagon is degraded by neutral endopeptidase (NEP) 24.11 in vitro, but the physiological relevance of NEP 24.11 in glucagon metabolism is unknown. Therefore, the influence of candoxatril, a......-RIA). This study provides evidence that NEP 24.11 is an important mediator of the degradation of both endogenous and exogenous glucagon in vivo....

  11. The CXC Chemokine-degrading Protease SpyCep of Streptococcus pyogenes Promotes Its Uptake into Endothelial Cells*

    Science.gov (United States)

    Kaur, Simran Jeet; Nerlich, Andreas; Bergmann, Simone; Rohde, Manfred; Fulde, Marcus; Zähner, Dorothea; Hanski, Emanuel; Zinkernagel, Annelies; Nizet, Victor; Chhatwal, Gursharan S.; Talay, Susanne R.

    2010-01-01

    Streptococcus pyogenes expresses the LPXTG motif-containing cell envelope serine protease SpyCep (also called ScpC, PrtS) that degrades and inactivates the major chemoattractant interleukin 8 (IL-8), thereby impairing host neutrophil recruitment. In this study, we identified a novel function of SpyCep: the ability to mediate uptake into primary human endothelial cells. SpyCep triggered its uptake into endothelial cells but not into human epithelial cells originating from pharynx or lung, indicating an endothelial cell-specific uptake mechanism. SpyCep mediated cellular invasion by an endosomal/lysosomal pathway distinct from the caveolae-mediated invasion pathway of S. pyogenes. Recombinant expression and purification of proteolytically active SpyCep and a series of subfragments allowed functional dissection of the domains responsible for endothelial cell invasion and IL-8 degradation. The N-terminal PR domain was sufficient to mediate endothelial cell invasion, whereas for IL-8-degrading activity, the protease domain and the flanking A domain were required. A polyclonal rabbit serum raised against the recombinant protease efficiently blocked the invasion-mediating activity of SpyCep but not its proteolytic function, further indicating that SpyCep-mediated internalization is independent from its enzymatic activity. SpyCep may thus specifically mediate its own uptake as secreted protein into human endothelial cells. PMID:20562101

  12. The CXC chemokine-degrading protease SpyCep of Streptococcus pyogenes promotes its uptake into endothelial cells.

    Science.gov (United States)

    Kaur, Simran Jeet; Nerlich, Andreas; Bergmann, Simone; Rohde, Manfred; Fulde, Marcus; Zähner, Dorothea; Hanski, Emanuel; Zinkernagel, Annelies; Nizet, Victor; Chhatwal, Gursharan S; Talay, Susanne R

    2010-09-03

    Streptococcus pyogenes expresses the LPXTG motif-containing cell envelope serine protease SpyCep (also called ScpC, PrtS) that degrades and inactivates the major chemoattractant interleukin 8 (IL-8), thereby impairing host neutrophil recruitment. In this study, we identified a novel function of SpyCep: the ability to mediate uptake into primary human endothelial cells. SpyCep triggered its uptake into endothelial cells but not into human epithelial cells originating from pharynx or lung, indicating an endothelial cell-specific uptake mechanism. SpyCep mediated cellular invasion by an endosomal/lysosomal pathway distinct from the caveolae-mediated invasion pathway of S. pyogenes. Recombinant expression and purification of proteolytically active SpyCep and a series of subfragments allowed functional dissection of the domains responsible for endothelial cell invasion and IL-8 degradation. The N-terminal PR domain was sufficient to mediate endothelial cell invasion, whereas for IL-8-degrading activity, the protease domain and the flanking A domain were required. A polyclonal rabbit serum raised against the recombinant protease efficiently blocked the invasion-mediating activity of SpyCep but not its proteolytic function, further indicating that SpyCep-mediated internalization is independent from its enzymatic activity. SpyCep may thus specifically mediate its own uptake as secreted protein into human endothelial cells.

  13. Environmental Degradation: Causes and Consequences

    Directory of Open Access Journals (Sweden)

    Swati Tyagi

    2014-08-01

    Full Text Available The subject of environmental economics is at the forefront of the green debate: the environment can no longer be viewed as an entity separate from the economy. Environmental degradation is of many types and have many consequences. To address this challenge a number of studies have been conducted in both developing and developed countries applying different methods to capture health benefits from improved environmental quality. Minimizing exposure to environmental risk factors by enhancing air quality and access to improved sources of drinking and bathing water, sanitation and clean energy is found to be associated with significant health benefits and can contribute significantly to the achievement of the Millennium Development Goals of environmental sustainability, health and development. In this paper, I describe the national and global causes and consequences of environmental degradation and social injustice. This paper provides a review of the literature on studies associated with reduced environmental risk and in particular focusing on reduced air pollution, enhanced water quality and climate change mitigation.

  14. Abiotic degradation of antibiotic ionophores.

    Science.gov (United States)

    Bohn, Pernille; Bak, Søren A; Björklund, Erland; Krogh, Kristine A; Hansen, Martin

    2013-11-01

    Hydrolytic and photolytic degradation were investigated for the ionophore antibiotics lasalocid, monensin, salinomycin, and narasin. The hydrolysis study was carried out by dissolving the ionophores in solutions of pH 4, 7, and 9, followed by incubation at three temperatures of 6, 22, and 28 °C for maximum 34 days. Using LC-MS/MS for chemical analysis, lasalocid was not found to hydrolyse in any of the tested environments. Monensin, salinomycin, and narasin were all stable in neutral or alkaline solution but hydrolysed in the solution with a pH of 4. Half-lives at 25 °C were calculated to be 13, 0.6, and 0.7 days for monensin, salinomycin, and narasin, respectively. Absorbance spectra from each compound indicated that only lasalocid is degraded by photolysis (half-life below 1 h) due to an absorbance maximum around 303 nm, and monensin, salinomycin, and narasin are resistant to direct photolysis because they absorb light of environmentally irrelevant wavelengths. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Microbial Enzymatic Degradation of Biodegradable Plastics.

    Science.gov (United States)

    Roohi; Bano, Kulsoom; Kuddus, Mohammed; Zaheer, Mohammed R; Zia, Qamar; Khan, Mohammed F; Ashraf, Ghulam Md; Gupta, Anamika; Aliev, Gjumrakch

    2017-01-01

    The renewable feedstock derived biodegradable plastics are important in various industries such as packaging, agricultural, paper coating, garbage bags and biomedical implants. The increasing water and waste pollution due to the available decomposition methods of plastic degradation have led to the emergence of biodegradable plastics and biological degradation with microbial (bacteria and fungi) extracellular enzymes. The microbes utilize biodegradable polymers as the substrate under starvation and in unavailability of microbial nutrients. Microbial enzymatic degradation is suitable from bioremediation point of view as no waste accumulation occurs. It is important to understand the microbial interaction and mechanism involved in the enzymatic degradation of biodegradable plastics under the influence of several environmental factors such as applied pH, thermo-stability, substrate molecular weight and/or complexity. To study the surface erosion of polymer film is another approach for hydrolytic degradation characteristion. The degradation of biopolymer is associated with the production of low molecular weight monomer and generation of carbon dioxide, methane and water molecule. This review reported the degradation study of various existing biodegradable plastics along with the potent degrading microbes (bacteria and fungi). Patents available on plastic biodegradation with biotechnological significance is also summarized in this paper. This paper assesses that new disposal technique should be adopted for the degradation of polymers and further research is required for the economical production of biodegradable plastics along with their enzymatic degradation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. mediation: R Package for Causal Mediation Analysis

    Directory of Open Access Journals (Sweden)

    Dustin Tingley

    2014-09-01

    Full Text Available In this paper, we describe the R package mediation for conducting causal mediation analysis in applied empirical research. In many scientific disciplines, the goal of researchers is not only estimating causal effects of a treatment but also understanding the process in which the treatment causally affects the outcome. Causal mediation analysis is frequently used to assess potential causal mechanisms. The mediation package implements a comprehensive suite of statistical tools for conducting such an analysis. The package is organized into two distinct approaches. Using the model-based approach, researchers can estimate causal mediation effects and conduct sensitivity analysis under the standard research design. Furthermore, the design-based approach provides several analysis tools that are applicable under different experimental designs. This approach requires weaker assumptions than the model-based approach. We also implement a statistical method for dealing with multiple (causally dependent mediators, which are often encountered in practice. Finally, the package also offers a methodology for assessing causal mediation in the presence of treatment noncompliance, a common problem in randomized trials.

  17. MEDIATION AGREEMENTS LEGAL MODEL

    Directory of Open Access Journals (Sweden)

    Alexander Ponomarev

    2015-07-01

    Full Text Available This article focuses on the legal model of mediation agreements in Russian and international legislation. The authors consider the main provisions of the mediation agreements in civil matters, in particular, is defined by such features of the legal model as the requirements for this type of agreements. In addition, the article discusses the problematic issues of implementation of mediation agreements.

  18. The LXR-IDOL axis defines a clathrin-, caveolae-, and dynamin-independent endocytic route for LDLR internalization and lysosomal degradation[S

    Science.gov (United States)

    Sorrentino, Vincenzo; Nelson, Jessica K.; Maspero, Elena; Marques, André R. A.; Scheer, Lilith; Polo, Simona; Zelcer, Noam

    2013-01-01

    Low density lipoprotein (LDL) cholesterol is taken up into cells via clathrin-mediated endocytosis of the LDL receptor (LDLR). Following dissociation of the LDLR-LDL complex, LDL is directed to lysosomes whereas the LDLR recycles to the plasma membrane. Activation of the sterol-sensing nuclear receptors liver X receptors (LXRs) enhances degradation of the LDLR. This depends on the LXR target gene inducible degrader of the LDLR (IDOL), an E3-ubiquitin ligase that promotes ubiquitylation and lysosomal degradation of the LDLR. How ubiquitylation of the LDLR by IDOL controls its endocytic trafficking is currently unknown. Using genetic- and pharmacological-based approaches coupled to functional assessment of LDL uptake, we show that the LXR-IDOL axis targets a LDLR pool present in lipid rafts. IDOL-dependent internalization of the LDLR is independent of clathrin, caveolin, macroautophagy, and dynamin. Rather, it depends on the endocytic protein epsin. Consistent with LDLR ubiquitylation acting as a sorting signal, degradation of the receptor can be blocked by perturbing the endosomal sorting complex required for transport (ESCRT) or by USP8, a deubiquitylase implicated in sorting ubiquitylated cargo to multivesicular bodies. In summary, we provide evidence for the existence of an LXR-IDOL-mediated internalization pathway for the LDLR that is distinct from that used for lipoprotein uptake. PMID:23733886

  19. atz gene expressions during atrazine degradation in the soil drilosphere.

    Science.gov (United States)

    Monard, C; Martin-Laurent, F; Devers-Lamrani, M; Lima, O; Vandenkoornhuyse, P; Binet, F

    2010-02-01

    One of the various ecosystemic services sustained by soil is pollutant degradation mediated by adapted soil bacteria. The pathways of atrazine biodegradation have been elucidated but in situ expression of the genes involved in atrazine degradation has yet to be demonstrated in soil. Expression of the atzA and atzD genes involved in atrazine dechlorination and s-triazine ring cleavage, respectively, was investigated during in situ degradation of atrazine in the soil drilosphere and bulked samples from two agricultural soils that differed in their ability to mineralize atrazine. Interestingly, expression of the atzA gene, although present in both soils, was not detected. Atrazine mineralization was greatest in Epoisses soil, where a larger pool of atzD mRNA was consistently measured 7 days after atrazine treatment, compared with Vezin soil (146 vs. 49 mRNA per 10(6)16S rRNA, respectively). Expression of the atzD gene varied along the degradation time course and was profoundly modified in soil bioturbated by earthworms. The atzD mRNA pool was the highest in the soil drilosphere (casts and burrow-linings) and it was significantly different in burrow-linings compared with bulk soil (e.g. 363 vs. 146 mRNA per 10(6)16S rRNA, 7 days after atrazine treatment in Epoisses soil). Thus, consistent differences in atrazine mineralization were demonstrated between the soil drilosphere and bulk soil. However, the impact of bioturbation on atrazine mineralization depended on soil type. Mineralization was enhanced in casts, compared with bulk soil, from Epoisses soil but in burrow-linings from Vezin soil. This study is the first to report the effects of soil bioturbation by earthworms on s-triazine ring cleavage and its spatial variability in soil.

  20. The Tissue Response and Degradation of Electrospun Poly(ε-caprolactone/Poly(trimethylene-carbonate Scaffold in Subcutaneous Space of Mice

    Directory of Open Access Journals (Sweden)

    Tao Jiang

    2014-01-01

    Full Text Available Due to the advantage of controllability on the mechanical property and the degradation rates, electrospun PCL/PTMC nanofibrous scaffold could be appropriate for vascular tissue engineering. However, the tissue response and degradation of electrospun PCL/PTMC scaffold in vivo have never been evaluated in detail. So, electrospun PCL/PTMC scaffolds with different blend ratios were prepared in this study. Mice subcutaneous implantation showed that the continuous degradation of PCL/PTMC scaffolds induced a lasted macrophage-mediated foreign body reaction, which could be in favor of the tissue regeneration in graft.

  1. Changes in Structural-Mechanical Properties and Degradability of Collagen during Aging-associated Modifications.

    Science.gov (United States)

    Panwar, Preety; Lamour, Guillaume; Mackenzie, Neil C W; Yang, Heejae; Ko, Frank; Li, Hongbin; Brömme, Dieter

    2015-09-18

    During aging, changes occur in the collagen network that contribute to various pathological phenotypes in the skeletal, vascular, and pulmonary systems. The aim of this study was to investigate the consequences of age-related modifications on the mechanical stability and in vitro proteolytic degradation of type I collagen. Analyzing mouse tail and bovine bone collagen, we found that collagen at both fibril and fiber levels varies in rigidity and Young's modulus due to different physiological changes, which correlate with changes in cathepsin K (CatK)-mediated degradation. A decreased susceptibility to CatK-mediated hydrolysis of fibrillar collagen was observed following mineralization and advanced glycation end product-associated modification. However, aging of bone increased CatK-mediated osteoclastic resorption by ∼27%, and negligible resorption was observed when osteoclasts were cultured on mineral-deficient bone. We observed significant differences in the excavations generated by osteoclasts and C-terminal telopeptide release during bone resorption under distinct conditions. Our data indicate that modification of collagen compromises its biomechanical integrity and affects CatK-mediated degradation both in bone and tissue, thus contributing to our understanding of extracellular matrix aging. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Native and aspirin-triggered lipoxins control innate immunity by inducing proteasomal degradation of TRAF6.

    Science.gov (United States)

    Machado, Fabiana S; Esper, Lísia; Dias, Alexandra; Madan, Rajat; Gu, YuanYuan; Hildeman, David; Serhan, Charles N; Karp, Christopher L; Aliberti, Júlio

    2008-05-12

    Innate immune signaling is critical for the development of protective immunity. Such signaling is, perforce, tightly controlled. Lipoxins (LXs) are eicosanoid mediators that play key counterregulatory roles during infection. The molecular mechanisms underlying LX-mediated control of innate immune signaling are of interest. In this study, we show that LX and aspirin (ASA)-triggered LX (ATL) inhibit innate immune signaling by inducing suppressor of cytokine signaling (SOCS) 2-dependent ubiquitinylation and proteasome-mediated degradation of TNF receptor-associated factor (TRAF) 2 and TRAF6, which are adaptor molecules that couple TNF and interleukin-1 receptor/Toll-like receptor family members to intracellular signaling events. LX-mediated degradation of TRAF6 inhibits proinflammatory cytokine production by dendritic cells. This restraint of innate immune signaling can be ablated by inhibition of proteasome function. In vivo, this leads to dysregulated immune responses, accompanied by increased mortality during infection. Proteasomal degradation of TRAF6 is a central mechanism underlying LX-driven immune counterregulation, and a hitherto unappreciated mechanism of action of ASA. These findings suggest a new molecular target for drug development for diseases marked by dysregulated inflammatory responses.

  3. Changes in Structural-Mechanical Properties and Degradability of Collagen during Aging-associated Modifications*

    Science.gov (United States)

    Panwar, Preety; Lamour, Guillaume; Mackenzie, Neil C. W.; Yang, Heejae; Ko, Frank; Li, Hongbin; Brömme, Dieter

    2015-01-01

    During aging, changes occur in the collagen network that contribute to various pathological phenotypes in the skeletal, vascular, and pulmonary systems. The aim of this study was to investigate the consequences of age-related modifications on the mechanical stability and in vitro proteolytic degradation of type I collagen. Analyzing mouse tail and bovine bone collagen, we found that collagen at both fibril and fiber levels varies in rigidity and Young's modulus due to different physiological changes, which correlate with changes in cathepsin K (CatK)-mediated degradation. A decreased susceptibility to CatK-mediated hydrolysis of fibrillar collagen was observed following mineralization and advanced glycation end product-associated modification. However, aging of bone increased CatK-mediated osteoclastic resorption by ∼27%, and negligible resorption was observed when osteoclasts were cultured on mineral-deficient bone. We observed significant differences in the excavations generated by osteoclasts and C-terminal telopeptide release during bone resorption under distinct conditions. Our data indicate that modification of collagen compromises its biomechanical integrity and affects CatK-mediated degradation both in bone and tissue, thus contributing to our understanding of extracellular matrix aging. PMID:26224630

  4. Estimating fractional rate of NDF degradation from in vivo digestibility

    DEFF Research Database (Denmark)

    Weisbjerg, Martin Riis; Søegaard, Karen; Lund, Peter

    2007-01-01

    Fractional rate of degradation (kd) of potential degradable NDF (dNDF) was estimated based on in situ degradation profiles.......Fractional rate of degradation (kd) of potential degradable NDF (dNDF) was estimated based on in situ degradation profiles....

  5. Microbial degradation of petroleum hydrocarbons.

    Science.gov (United States)

    Varjani, Sunita J

    2017-01-01

    Petroleum hydrocarbon pollutants are recalcitrant compounds and are classified as priority pollutants. Cleaning up of these pollutants from environment is a real world problem. Bioremediation has become a major method employed in restoration of petroleum hydrocarbon polluted environments that makes use of natural microbial biodegradation activity. Petroleum hydrocarbons utilizing microorganisms are ubiquitously distributed in environment. They naturally biodegrade pollutants and thereby remove them from the environment. Removal of petroleum hydrocarbon pollutants from environment by applying oleophilic microorganisms (individual isolate/consortium of microorganisms) is ecofriendly and economic. Microbial biodegradation of petroleum hydrocarbon pollutants employs the enzyme catalytic activities of microorganisms to enhance the rate of pollutants degradation. This article provides an overview about bioremediation for petroleum hydrocarbon pollutants. It also includes explanation about hydrocarbon metabolism in microorganisms with a special focus on new insights obtained during past couple of years. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. CELLULOSE DEGRADATION BY OXIDATIVE ENZYMES

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

    Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

  7. Cellulose degradation by oxidative enzymes

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

    Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

  8. Permafrost degradation in West Greenland

    DEFF Research Database (Denmark)

    Foged, Niels Nielsen; Ingeman-Nielsen, Thomas

    2012-01-01

    Important aspects of civil engineering in West Greenland relate to the presence of permafrost and mapping of the annual and future changes in the active layer due to the ongoing climatically changes in the Arctic. The Arctic Technology Centre (ARTEK) has worked more than 10 years on this topic...... and the first author has been involved since 1970 in engineering geology, geotechnical engineering and permafrost related studies for foundation construction and infrastructures in towns and communities mainly in West Greenland. We have since 2006 together with the Danish Meteorological Institute, Greenland...... by HIRHAM climate projections for Greenland up to 2075. The engineering modelling is based on a risk assessment methodology based on a flow diagram which classify the risk of permafrost degradation causing settlement and stability problems for buildings and infrastructures based on relatively simple...

  9. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

  10. Soil physical land degradation processes

    Science.gov (United States)

    Horn, Rainer

    2017-04-01

    According to the European Soil Framework Directive (2006) soil compaction is besides water and wind erosion one of the main physical reasons and threats of soil degradation. It is estimated, that 32% of the subsoils in Europe are highly degraded and 18% moderately vulnerable to compaction. The problem is not limited to crop land or forest areas (especially because of non-site adjusted harvesting machines) but is also prevalent in rangelands and grassland, and even in so called natural non-disturbed systems. The main reasons for an intense increase in compacted agricultural or forested regions are the still increasing masses of the machines as well the increased frequency of wheeling under non favorable site conditions. Shear and vibration induced soil deformation enhances the deterioration of soil properties especially if the soil water content is very high and the internal soil strength very low. The same is true for animal trampling in combination with overgrazing of moist to wet pastures which subsequently causes a denser (i.e. reduced proportion of coarse pores with smaller continuity) but still structured soil horizons and will finally end in a compacted platy structure. In combination with high water content and shearing due to trampling therefore results in a complete muddy homogeneous soil with no structure at all. (Krümmelbein et al. 2013) Site managements of arable, forestry or horticulture soils requires a sufficiently rigid pore system which guarantees water, gas and heat exchange, nutrient transport and adsorption as well as an optimal rootability in order to avoid subsoil compaction. Such pore system also guarantees a sufficient microbial activity and composition in order to also decompose the plant etc. debris. It is therefore essential that well structured horizons dominate in soils with at best subangular blocky structure or in the top A- horizons a crumbly structure due to biological activity. In contrast defines the formation of a platy

  11. Oils degradation in agricultural machinery

    Directory of Open Access Journals (Sweden)

    Vojtěch Kumbár

    2013-01-01

    Full Text Available Evaluating of oils condition in agricultural machinery is very important. With monitoring and evaluating we can prevent technical and economic losses. In this paper there were monitored the liquid lubricants taken from mobile thresher New Holland CX 860. Chemical and viscosity degradation of the lubricants were evaluated. Temperature dependence dynamic viscosity was observed in the range of temperature from −10 °C to 80 °C (for all oils. Considerable temperature dependence dynamic viscosity was found and demonstrated in case of all samples, which is in accordance with theoretical assumptions and literature data. Mathematical models were developed and tested. Temperature dependence dynamic viscosity was modeled using a polynomial 6th degree. The proposed models can be used for prediction of flow behavior of oils.

  12. Operationalizing measurement of forest degradation

    DEFF Research Database (Denmark)

    Dons, Klaus; Smith-Hall, Carsten; Meilby, Henrik

    2015-01-01

    . In Tanzania, charcoal production is considered a major cause of forest degradation, but is challenging to quantify due to sub-canopy biomass loss, remote production sites and illegal trade. We studied two charcoal production sites in dry Miombo woodland representing open woodland conditions near human...... settlements and remote forest with nearly closed canopies. Supervised classification and adaptive thresholding were applied on a pansharpened QuickBird (QB) image to detect kiln burn marks (KBMs). Supervised classification showed reasonable detection accuracy in the remote forest site only, while adaptive...... resulted in R2s of 0.86–0.88 with cross-validation RMSE ranging from 2.22 to 2.29 Mg charcoal per kiln. This study demonstrates, how locally calibrated remote sensing techniques may be used to identify and delineate charcoal production sites for estimation of charcoal production and associated extraction...

  13. Robust PV Degradation Methodology and Application

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Deline, Christopher A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kurtz, Sarah [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kimball, Greg [SunPower; Anderson, Mike [SunPower

    2017-11-15

    The degradation rate plays an important role in predicting and assessing the long-term energy generation of PV systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this manuscript, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year (YOY) rate calculation. We show the method to provide reliable degradation rate estimates even in the case of sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.

  14. Robust PV Degradation Methodology and Application

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Deline, Christopher A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kurtz, Sarah [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kimball, Gregory M. [SunPower Corporation; Anderson, Mike [SunPower Corporation

    2017-12-21

    The degradation rate plays an important role in predicting and assessing the long-term energy generation of photovoltaics (PV) systems. Many methods have been proposed for extracting the degradation rate from operational data of PV systems, but most of the published approaches are susceptible to bias due to inverter clipping, module soiling, temporary outages, seasonality, and sensor degradation. In this paper, we propose a methodology for determining PV degradation leveraging available modeled clear-sky irradiance data rather than site sensor data, and a robust year-over-year rate calculation. We show the method to provide reliable degradation rate estimates even in the case of sensor drift, data shifts, and soiling. Compared with alternate methods, we demonstrate that the proposed method delivers the lowest uncertainty in degradation rate estimates for a fleet of 486 PV systems.

  15. Recovering of images degraded by atmosphere

    Science.gov (United States)

    Lin, Guang; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

    2017-08-01

    Remote sensing images are seriously degraded by multiple scattering and bad weather. Through the analysis of the radiative transfer procedure in atmosphere, an image atmospheric degradation model considering the influence of atmospheric absorption multiple scattering and non-uniform distribution is proposed in this paper. Based on the proposed model, a novel recovering method is presented to eliminate atmospheric degradation. Mean-shift image segmentation and block-wise deconvolution are used to reduce time cost, retaining a good result. The recovering results indicate that the proposed method can significantly remove atmospheric degradation and effectively improve contrast compared with other removal methods. The results also illustrate that our method is suitable for various degraded remote sensing, including images with large field of view (FOV), images taken in side-glance situations, image degraded by atmospheric non-uniform distribution and images with various forms of clouds.

  16. Nanoparticles from Degradation of Biodegradable Plastic Mulch

    Science.gov (United States)

    Flury, Markus; Sintim, Henry; Bary, Andy; English, Marie; Schaefer, Sean

    2017-04-01

    Plastic mulch films are commonly used in crop production. They provide multiple benefits, including control of weeds and insects, increase of soil and air temperature, reduction of evaporation, and prevention of soil erosion. The use of plastic mulch film in agriculture has great potential to increase food production and security. Plastic mulch films must be retrieved and disposed after usage. Biodegradable plastic mulch films, who can be tilled into the soil after usage offer great benefits as alternative to conventional polyethylene plastic. However, it has to be shown that the degradation of these mulches is complete and no micro- and nanoparticles are released during degradation. We conducted a field experiment with biodegradable mulches and tested mulch degradation. Mulch was removed from the field after the growing season and composted to facilitate degradation. We found that micro- and nanoparticles were released during degradation of the mulch films in compost. This raises concerns about degradation in soils as well.

  17. Enhanced aerobic degradation of 4-chlorophenol with iron-nickel nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Wenjuan; Mu, Yi; Wang, Bingning; Ai, Zhihui, E-mail: jennifer.ai@mail.ccnu.edu.cn; Zhang, Lizhi

    2017-01-30

    Highlights: • Bimetallic iron-nickel nanoparticles possessed an enhanced performance on aerobic degradation of 4-CP. • Hydroxyl radicals were the major active species contributed to aerobic 4-CP degradation with nZVI. • Superoxide radicals predominated the 4-CP degradation in the nZVIN/Air process. • The 4-CP degradation pathways were dependent on the generated superoxide radicals in the nZVIN/Air process. - Abstract: In this study, we demonstrate that the bimetallic iron-nickel nanoparticles (nZVIN) possessed an enhanced performance in comparison with nanoscale zero-valent iron (nZVI) on aerobic degradation of 4-chlorophenol (4-CP). The 4-CP degradation rate constant in the aerobic nZVIN process (nZVIN/Air) was 5 times that in the classic nZVI counterpart system (nZVI/Air). Both reactive oxygen species measurement and inhibition experimental results suggested that hydroxyl radicals were the major active species contributed to aerobic 4-CP degradation with nZVI, on contrast, superoxide radicals predominated the 4-CP degradation in the nZVIN/Air process. High performance liquid chromatography and gas chromatography-mass spectrometer analysis indicated the intermediates of the nZVI/Air system were p-benzoquinone and hydroquinone, which were resulted from the bond cleavage between the chlorine and carbon atom in the benzene ring by hydroxyl radicals. However, the primary intermediates of 4-CP found in the nZVIN/Air system were phenol via the direct dechlorination by superoxide radicals, accompanying with the formation of chloride ions. On the base of experimental results, a superoxide radicals mediated enhancing mechanism was proposed for the aerobic degradation of 4-CP in the nZVIN/Air system. This study provides new insight into the role of bimetallic nickel on enhancing removal of organic pollutants with nZVI.

  18. Durability Improvements Through Degradation Mechanism Studies

    Energy Technology Data Exchange (ETDEWEB)

    Borup, Rodney L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mukundan, Rangachary [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Spernjak, Dusan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baker, Andrew M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lujan, Roger W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Langlois, David Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ahluwalia, Rajesh [Argonne National Lab. (ANL), Argonne, IL (United States); Papadia, D. D. [Argonne National Lab. (ANL), Argonne, IL (United States); Weber, Adam Z. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kusoglu, Ahmet [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shi, Shouwnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); More, K. L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Grot, Steve [Ion Power, New Castle, DE (United States)

    2015-08-03

    The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. By investigating cell component degradation modes and defining the fundamental degradation mechanisms of components and component interactions, new materials can be designed to improve durability. To achieve a deeper understanding of PEM fuel cell durability and component degradation mechanisms, we utilize a multi-institutional and multi-disciplinary team with significant experience investigating these phenomena.

  19. Degradation products of rubusoside under acidic conditions.

    Science.gov (United States)

    Prakash, Indra; Bunders, Cynthia; Devkota, Krishna P; Charan, Romila D; Hartz, Rachael M; Sears, Tracy L; Snyder, Tara M; Ramirez, Catherine

    2015-04-01

    A natural sweetener, Rubusoside (1), subjected to extreme pH and temperature conditions, resulted in the isolation and structural elucidation of one novel rubusoside degradant (7), together with seven known degradants (2-6 and 8-9). ID and 2D NMR spectroscopy (1H, 13C, COSY, HSQC-DEPT, HMBC, and NOESY) and mass spectral data were used to fully characterize the degradant 7.

  20. The soils of Serbia and their degradation

    OpenAIRE

    Ličina Vlado; Nešić Ljiljana; Belić Milivoj; Hadžić Vladimir; Sekulić Petar; Vasin Jovica; Ninkov Jordana

    2011-01-01

    In view of the topicality of the subject of soil protection from degradation, the paper discusses some basic considerations concerning soil genesis, pedogenetic processes, and soil degradation caused by human activity in Serbia. It can be said that at present the main processes connected with soil loss and soil degradation in Serbia are as follows: 1) change in the intended use of the soil (soil loss and damage due to industrial, mining, and power-producing activities) 2) loss of soil organic...

  1. Temporal changes in soil bacterial diversity and humic substances degradation in subarctic tundra soil.

    Science.gov (United States)

    Park, Ha Ju; Chae, Namyi; Sul, Woo Jun; Lee, Bang Yong; Lee, Yoo Kyung; Kim, Dockyu

    2015-04-01

    Humic substances (HS), primarily humic acids (HA) and fulvic acids (FA), are the largest constituent of soil organic matter. In microcosm systems with subarctic HS-rich tundra soil (site AK 1-75; approximately 5.6 °C during the thawing period) from Council, Alaska, the HA content significantly decreased to 48% after a 99-day incubation at 5 °C as part of a biologically mediated process. Accordingly, levels of FA, a putative byproduct of HA degradation, consistently increased to 172% during an identical incubation process. Culture-independent microbial community analysis showed that during the microcosm experiments, the relative abundance of phyla Proteobacteria (bacteria) and Euryarchaeota (archaea) largely increased, indicating their involvement in HS degradation. When the indigenous bacteria in AK 1-75 were enriched in an artificial mineral medium spiked with HA, the changes in relative abundance were most conspicuous in Proteobacteria (from 60.2 to 79.0%), specifically Betaproteobacteria-related bacteria. One hundred twenty-two HA-degrading bacterial strains, primarily from the genera Paenibacillus (phylum Firmicutes) and Pseudomonas (class Gammaproteobacteria), were cultivated from AK 1-75 and nearby sites. Through culture-dependent analysis with these bacterial isolates, we observed increasing HS-degradation rates in parallel with rising temperatures in a range of 0 °C to 20 °C, with the most notable increase occurring at 8 °C compared to 6 °C. Our results indicate that, although microbial-mediated HS degradation occurs at temperature as low as 5 °C in tundra ecosystems, increasing soil temperature caused by global climate change could enhance HS degradation rates. Extending the thawing period could also increase degradation activity, thereby directly affecting nearby microbial communities and rhizosphere environments.

  2. XRN2 is required for the degradation of target RNAs by RNase H1-dependent antisense oligonucleotides

    Energy Technology Data Exchange (ETDEWEB)

    Hori, Shin-Ichiro; Yamamoto, Tsuyoshi; Obika, Satoshi, E-mail: obika@phs.osaka-u.ac.jp

    2015-08-21

    Antisense oligonucleotides (ASOs) can suppress the expression of a target gene by cleaving pre-mRNA and/or mature mRNA via RNase H1. Following the initial endonucleolytic cleavage by RNase H1, the target RNAs are degraded by a mechanism that is poorly understood. To better understand this degradation pathway, we depleted the expression of two major 5′ to 3′ exoribonucleases (XRNs), named XRN1 and XRN2, and analyzed the levels of 3′ fragments of the target RNAs in vitro. We found that the 3′ fragments of target pre-mRNA generated by ASO were almost completely degraded from their 5′ ends by nuclear XRN2 after RNase H1-mediated cleavage, whereas the 3′ fragments of mature mRNA were partially degraded by XRN2. In contrast to ASO, small interference RNA (siRNA) could reduce the expression level of only mature mRNA, and the 3′ fragment was degraded by cytoplasmic XRN1. Our findings indicate that the RNAs targeted by RNase H1-dependent ASO are rapidly degraded in the nucleus, contrary to the cytoplasmic degradation pathway mediated by siRNA. - Highlights: • We compared the degradation mechanism of the transcript targeted by ASO and siRNA. • We focused on two 5′ to 3′ exoribonucleases, cytoplasmic XRN1, and nuclear XRN2. • The 3′ fragment of target pre-mRNA generated by ASO was degraded by XRN2. • The 3′ fragment of target mRNA generated by ASO was partially degraded by XRN2. • XRN1 depletion promoted accumulation of the 3′ fragment of mRNA generated by siRNA.

  3. Degradation of chlorpyrifos in humid tropical soils.

    Science.gov (United States)

    Chai, Lian-Kuet; Wong, Mee-Hua; Bruun Hansen, Hans Christian

    2013-08-15

    The insecticide chlorpyrifos is extensively used in the humid tropics for insect control on crops and soils. Chlorpyrifos degradation and mineralization was studied under laboratory conditions to characterize the critical factors controlling the degradation and mineralization in three humid tropical soils from Malaysia. The degradation was fastest in moist soils (t1/2 53.3-77.0 days), compared to dry (t1/2 49.5-120 days) and wet soils (t1/2 63.0-124 days). Degradation increased markedly with temperature with activation energies of 29.0-76.5 kJ mol(-1). Abiotic degradation which is important for chlorpyrifos degradation in sub-soils containing less soil microbial populations resulted in t½ of 173-257 days. Higher chlorpyrifos dosages (5-fold) which are often applied in the tropics due to severe insects infestations caused degradation and mineralization rates to decrease by 2-fold. The mineralization rates were more sensitive to the chlorpyrifos application rates reflecting that degradation of metabolites is rate limiting and the toxic effects of some of the metabolites produced. Despite that chlorpyrifos is frequently used and often in larger amounts on tropical soils compared with temperate soils, higher temperature, moderate moisture and high activity of soil microorganisms will stimulate degradation and mineralization. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Handbook of environmental degradation of materials

    National Research Council Canada - National Science Library

    Kutz, Myer

    2012-01-01

    Divided into sections which deal with analysis, types of degradation, protection and surface engineering respectively, the reader is introduced to the wide variety of environmental effects and what...

  5. Metal peroxide- polymer composites for dye degradation

    Science.gov (United States)

    Anshu, Ashwini; Vijayaraghavan, R.

    2017-11-01

    Semiconductor metal oxides/its composites with polymers have been explored for dye degradation through photocatalytic mechanism; these require UV or visible light for activation. Hence, there is need to develop (photo) catalyst that work in absence/presence of light. Towards this objective we are exploring metal peroxides and its composites for dye degradation. Here, we report our work on magnesium peroxide and its composites for dye degradation by photochemical pathways. The nanocomposites are synthesized from monomers and peroxides. The synthesized composites have been characterized by IR, DRS and powder XRD. The composites did not degrade dyes in dark.

  6. Photovoltaic Degradation Rates -- An Analytical Review

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D. C.; Kurtz, S. R.

    2012-06-01

    As photovoltaic penetration of the power grid increases, accurate predictions of return on investment require accurate prediction of decreased power output over time. Degradation rates must be known in order to predict power delivery. This article reviews degradation rates of flat-plate terrestrial modules and systems reported in published literature from field testing throughout the last 40 years. Nearly 2000 degradation rates, measured on individual modules or entire systems, have been assembled from the literature, showing a median value of 0.5%/year. The review consists of three parts: a brief historical outline, an analytical summary of degradation rates, and a detailed bibliography partitioned by technology.

  7. Simulating Degradation Data for Prognostic Algorithm Development

    Data.gov (United States)

    National Aeronautics and Space Administration — PHM08 Challenge Dataset is now publicly available at the NASA Prognostics Respository + Download INTRODUCTION - WHY SIMULATE DEGRADATION DATA? Of various challenges...

  8. Plasmid-Mediated Bioaugmentation for the Bioremediation of Contaminated Soils.

    Science.gov (United States)

    Garbisu, Carlos; Garaiyurrebaso, Olatz; Epelde, Lur; Grohmann, Elisabeth; Alkorta, Itziar

    2017-01-01

    Bioaugmentation, or the inoculation of microorganisms (e.g., bacteria harboring the required catabolic genes) into soil to enhance the rate of contaminant degradation, has great potential for the bioremediation of soils contaminated with organic compounds. Regrettably, cell bioaugmentation frequently turns into an unsuccessful initiative, owing to the rapid decrease of bacterial viability and abundance after inoculation, as well as the limited dispersal of the inoculated bacteria in the soil matrix. Genes that encode the degradation of organic compounds are often located on plasmids and, consequently, they can be spread by horizontal gene transfer into well-established, ecologically competitive, indigenous bacterial populations. Plasmid-mediated bioaugmentation aims to stimulate the spread of contaminant degradation genes among indigenous soil bacteria by the introduction of plasmids, located in donor cells, harboring such genes. But the acquisition of plasmids by recipient cells can affect the host's fitness, a crucial aspect for the success of plasmid-mediated bioaugmentation. Besides, environmental factors (e.g., soil moisture, temperature, organic matter content) can play important roles for the transfer efficiency of catabolic plasmids, the expression of horizontally acquired genes and, finally, the contaminant degradation activity. For plasmid-mediated bioaugmentation to be reproducible, much more research is needed for a better selection of donor bacterial strains and accompanying plasmids, together with an in-depth understanding of indigenous soil bacterial populations and the environmental conditions that affect plasmid acquisition and the expression and functioning of the catabolic genes of interest.

  9. Plasmid-Mediated Bioaugmentation for the Bioremediation of Contaminated Soils

    Directory of Open Access Journals (Sweden)

    Carlos Garbisu

    2017-10-01

    Full Text Available Bioaugmentation, or the inoculation of microorganisms (e.g., bacteria harboring the required catabolic genes into soil to enhance the rate of contaminant degradation, has great potential for the bioremediation of soils contaminated with organic compounds. Regrettably, cell bioaugmentation frequently turns into an unsuccessful initiative, owing to the rapid decrease of bacterial viability and abundance after inoculation, as well as the limited dispersal of the inoculated bacteria in the soil matrix. Genes that encode the degradation of organic compounds are often located on plasmids and, consequently, they can be spread by horizontal gene transfer into well-established, ecologically competitive, indigenous bacterial populations. Plasmid-mediated bioaugmentation aims to stimulate the spread of contaminant degradation genes among indigenous soil bacteria by the introduction of plasmids, located in donor cells, harboring such genes. But the acquisition of plasmids by recipient cells can affect the host’s fitness, a crucial aspect for the success of plasmid-mediated bioaugmentation. Besides, environmental factors (e.g., soil moisture, temperature, organic matter content can play important roles for the transfer efficiency of catabolic plasmids, the expression of horizontally acquired genes and, finally, the contaminant degradation activity. For plasmid-mediated bioaugmentation to be reproducible, much more research is needed for a better selection of donor bacterial strains and accompanying plasmids, together with an in-depth understanding of indigenous soil bacterial populations and the environmental conditions that affect plasmid acquisition and the expression and functioning of the catabolic genes of interest.

  10. Mechanisms of humic substances degradation by fungi

    Science.gov (United States)

    Chen, Y.; Hadar, Y.; Grinhut, T.

    2012-04-01

    Humic substances (HS) are formed by secondary synthesis reactions (humification) during the decay process and transformation of biomolecules originating from plants and other dead organisms. In nature, HS are extremely resistant to biological degradation. Thus, these substances are major components in the C cycle and in the biosphere and therefore, the understanding of the process leading to their formation and transformation and degradation is vital. Fungi active in the decomposition process of HS include mainly ascomycetes and basidiomycetes that are common in the upper layer of forest and grassland soils. Many basidiomycetes belong to the white-rot fungi (WRF) and litter-decomposing fungi (LDF). These fungi are considered to be the most efficient lignin degraders due to their nonspecific oxidizing enzymes: manganese peroxidase (MnP), lignin peroxidase (LiP) and laccase. Although bacteria dominate compost and participate in the turnover of HS, their ability to degrade stable macromolecules such as lignin and HS is limited. The overall objectives of this research were to corroborate biodegradation processes of HS by WRF. The specific objectives were: (i) To isolate, identify and characterize HS degrading WRF from biosolids (BS) compost; (ii) To study the biodegradation process of three types of HS, which differ in their structure, by WRF isolated from BS compost; and (iii) To investigate the mechanisms of HA degradation by WRF using two main approaches: (a) Study the physical and chemical analyses of the organic compounds obtained from direct fungal degradation of HA as well as elucidation of the relevant enzymatic reactions; and (b) Study the enzymatic and biochemical mechanisms involved during HA degradation. In order to study the capability of fungi to degrade HS, seventy fungal strains were isolated from biosolids (BS) compost. Two of the most active fungal species were identified based on rDNA sequences and designated Trametes sp. M23 and Phanerochaetesp., Y6

  11. Chitin degradation and electricity generation by Aeromonas hydrophila in microbial fuel cells.

    Science.gov (United States)

    Li, Shan-Wei; He, Hui; Zeng, Raymond J; Sheng, Guo-Ping

    2017-02-01

    Chitin is one of the most abundant biopolymers in nature and the main composition of shrimp and crab shells (usually as food wastes). Thus it is essential to investigate the potential of degrading chitin for energy recovery. This study investigated the anaerobic degradation of chitin by Aeromonas hydrophila, a chitinolytic and popular electroactive bacterium, in both fermentation and microbial fuel cell (MFC) systems. The primary chitin metabolites produced in MFC were succinate, lactate, acetate, formate, and ethanol. The total metabolite concentration from chitin degradation increased seven-fold in MFC compared to the fermentation system, as well as additional electricity generation. Moreover, A. hydrophila degraded GlcNAc (the intermediate of chitin hydrolysis) significantly faster (0.97 and 0.94 mM C/d/mM-GlcNAc) than chitin (0.13 and 0.03 mM C/d/mM-GlcNAc) in MFC and fermentation systems, indicating that extracellular hydrolysis of chitin was the rate-limiting step and this step could be accelerated in MFC. Furthermore, more chemicals produced by the addition of exogenous mediators in MFC. This study proves that the chitin could be degraded effectively by an electroactive bacterium in MFC, and our results suggest that this bioelectrochemical system might be useful for the degradation of recalcitrant biomass to recover energy. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Endoplasmic reticulum stress contributes to acetylcholine receptor degradation by promoting endocytosis in skeletal muscle cells.

    Science.gov (United States)

    Du, Ailian; Huang, Shiqian; Zhao, Xiaonan; Zhang, Yun; Zhu, Lixun; Ding, Ji; Xu, Congfeng

    2016-01-15

    After binding by acetylcholine released from a motor neuron, a nicotinic acetylcholine receptor at the neuromuscular junction produces a localized end-plate potential, which leads to muscle contraction. Improper turnover and renewal of acetylcholine receptors contributes to the pathogenesis of myasthenia gravis. In the present study, we demonstrate that endoplasmic reticulum (ER) stress contributes to acetylcholine receptor degradation in C2C12 myocytes. We further show that ER stress promotes acetylcholine receptor endocytosis and lysosomal degradation, which was dampened by blocking endocytosis or treating with lysosome inhibitor. Knockdown of ER stress proteins inhibited acetylcholine receptor endocytosis and degradation, while rescue assay restored its endocytosis and degradation, confirming the effects of ER stress on promoting endocytosis-mediated degradation of junction acetylcholine receptors. Thus, our studies identify ER stress as a factor promoting acetylcholine receptor degradation through accelerating endocytosis in muscle cells. Blocking ER stress and/or endocytosis might provide a novel therapeutic approach for myasthenia gravis. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Planktonic versus biofilm catabolic communities: importance of the biofilm for species selection and pesticide degradation.

    Science.gov (United States)

    Verhagen, Pieter; De Gelder, Leen; Hoefman, Sven; De Vos, Paul; Boon, Nico

    2011-07-01

    Chloropropham-degrading cultures were obtained from sludge and soil samples by using two different enrichment techniques: (i) planktonic enrichments in shaken liquid medium and (ii) biofilm enrichments on two types of solid matrixes (plastic chips and gravel). Denaturing gradient gel electrophoresis fingerprinting showed that planktonic and biofilm cultures had a different community composition depending on the presence and type of added solid matrix during enrichment. This was reflected in the unique chloropropham-degrading species that could be isolated from the different cultures. Planktonic and biofilm cultures also differed in chloropropham-degrading activity. With biofilm cultures, slower chloropropham removal was observed, but with less build-up of the toxic intermediate 3-chloroaniline. Disruption of the biofilm architecture resulted in degradation characteristics shifting toward those of the free suspensions, indicating the importance of a well-established biofilm structure for good performance. These results show that biofilm-mediated enrichment techniques can be used to select for pollutant-degrading microorganisms that like to proliferate in a biofilm and that cannot be isolated using conventional shaken-liquid procedures. Furthermore, the influence of the biofilm architecture on the pesticide degradation characteristics suggests that for bioaugmentation the use of biofilm catabolic communities might be a proficient alternative to using planktonic freely suspended cultures.

  14. Aflatoxin B₁ degradation by a Pseudomonas strain.

    Science.gov (United States)

    Sangare, Lancine; Zhao, Yueju; Folly, Yawa Minnie Elodie; Chang, Jinghua; Li, Jinhan; Selvaraj, Jonathan Nimal; Xing, Fuguo; Zhou, Lu; Wang, Yan; Liu, Yang

    2014-10-23

    Aflatoxin B1 (AFB1), one of the most potent naturally occurring mutagens and carcinogens, causes significant threats to the food industry and animal production. In this study, 25 bacteria isolates were collected from grain kernels and soils displaying AFB1 reduction activity. Based on its degradation effectiveness, isolate N17-1 was selected for further characterization and identified as Pseudomonas aeruginosa. P. aeruginosa N17-1 could degrade AFB₁, AFB₂ and AFM₁ by 82.8%, 46.8% and 31.9% after incubation in Nutrient Broth (NB) medium at 37 °C for 72 h, respectively. The culture supernatant of isolate N17-1 degraded AFB₁ effectively, whereas the viable cells and intra cell extracts were far less effective. Factors influencing AFB1 degradation by the culture supernatant were investigated. Maximum degradation was observed at 55 °C. Ions Mn²⁺ and Cu²⁺ were activators for AFB1 degradation, however, ions Mg²⁺, Li⁺, Zn²⁺, Se²⁺, Fe³⁺ were strong inhibitors. Treatments with proteinase K and proteinase K plus SDS significantly reduced the degradation activity of the culture supernatant. No degradation products were observed based on preliminary LC-QTOF/MS analysis, indicating AFB₁ was metabolized to degradation products with chemical properties different from that of AFB₁. The results indicated that the degradation of AFB₁ by P. aeruginosa N17-1 was enzymatic and could have a great potential in industrial applications. This is the first report indicating that the isolate of P. aeruginosa possesses the ability to degrade aflatoxin.

  15. Current state of knowledge in microbial degradation of polycyclic aromatic hydrocarbons (PAHs: a review

    Directory of Open Access Journals (Sweden)

    Debajyoti Ghosal

    2016-08-01

    Full Text Available Polycyclic aromatic hydrocarbons (PAHs include a group of organic priority pollutants of critical environmental and public health concern due to their toxic, genotoxic, mutagenic and/or carcinogenic properties and their ubiquitous occurrence as well as recalcitrance. The increased awareness of their various adverse effects on ecosystem and human health has led to a dramatic increase in research aimed towards removing PAHs from the environment. PAHs may undergo adsorption, volatilization, photolysis, and chemical oxidation, although transformation by microorganisms is the major neutralization process of PAH-contaminated sites in an ecologically accepted manner. Microbial degradation of PAHs depends on various environmental conditions, such as nutrients, number and kind of the microorganisms, nature as well as chemical property of the PAH being degraded. A wide variety of bacterial, fungal and algal species have the potential to degrade/transform PAHs, among which bacteria and fungi mediated degradation has been studied most extensively. In last few decades microbial community analysis, biochemical pathway for PAHs degradation, gene organization, enzyme system, genetic regulation for PAH degradation have been explored in great detail. Although, xenobiotic-degrading microorganisms have incredible potential to restore contaminated environments inexpensively yet effectively, but new advancements are required to make such microbes effective and more powerful in removing those compounds, which were once thought to be recalcitrant. Recent analytical chemistry and genetic engineering tools might help to improve the efficiency of degradation of PAHs by microorganisms, and minimize uncertainties of successful bioremediation. However, appropriate implementation of the potential of naturally occurring microorganisms for field bioremediation could be considerably enhanced by optimizing certain factors such as bioavailability, adsorption and mass transfer of

  16. Current State of Knowledge in Microbial Degradation of Polycyclic Aromatic Hydrocarbons (PAHs): A Review

    Science.gov (United States)

    Ghosal, Debajyoti; Ghosh, Shreya; Dutta, Tapan K.; Ahn, Youngho

    2016-01-01

    Polycyclic aromatic hydrocarbons (PAHs) include a group of organic priority pollutants of critical environmental and public health concern due to their toxic, genotoxic, mutagenic and/or carcinogenic properties and their ubiquitous occurrence as well as recalcitrance. The increased awareness of their various adverse effects on ecosystem and human health has led to a dramatic increase in research aimed toward removing PAHs from the environment. PAHs may undergo adsorption, volatilization, photolysis, and chemical oxidation, although transformation by microorganisms is the major neutralization process of PAH-contaminated sites in an ecologically accepted manner. Microbial degradation of PAHs depends on various environmental conditions, such as nutrients, number and kind of the microorganisms, nature as well as chemical property of the PAH being degraded. A wide variety of bacterial, fungal and algal species have the potential to degrade/transform PAHs, among which bacteria and fungi mediated degradation has been studied most extensively. In last few decades microbial community analysis, biochemical pathway for PAHs degradation, gene organization, enzyme system, genetic regulation for PAH degradation have been explored in great detail. Although, xenobiotic-degrading microorganisms have incredible potential to restore contaminated environments inexpensively yet effectively, but new advancements are required to make such microbes effective and more powerful in removing those compounds, which were once thought to be recalcitrant. Recent analytical chemistry and genetic engineering tools might help to improve the efficiency of degradation of PAHs by microorganisms, and minimize uncertainties of successful bioremediation. However, appropriate implementation of the potential of naturally occurring microorganisms for field bioremediation could be considerably enhanced by optimizing certain factors such as bioavailability, adsorption and mass transfer of PAHs. The main

  17. Degrading and non-degrading sex in popular music: a content analysis.

    Science.gov (United States)

    Primack, Brian A; Gold, Melanie A; Schwarz, Eleanor B; Dalton, Madeline A

    2008-01-01

    Those exposed to more degrading sexual references in popular music are more likely to initiate intercourse at a younger age. The purpose of this study was to perform a content analysis of contemporary popular music with particular attention paid to the prevalence of degrading and non-degrading sexual references. We also aimed to determine if sexual references of each subtype were associated with other song characteristics and/or content. We used Billboard magazine to identify the top popular songs in 2005. Two independent coders each analyzed all of these songs (n = 279) for degrading and non-degrading sexual references. As measured with Cohen's kappa scores, inter-rater agreement on degrading vs. non-degrading sex was substantial. Mentions of substance use, violence, and weapon carrying were also coded. Of the 279 songs identified, 103 (36.9%) contained references to sexual activity. Songs with references to degrading sex were more common than songs with references to non-degrading sex (67 [65.0%] vs. 36 [35.0%], p popular music, and degrading sexual references are more prevalent than non-degrading references. References to degrading sex also frequently appear with references to other risky behaviors.

  18. Degradation mechanisms in organic photovoltaic devices

    NARCIS (Netherlands)

    Grossiord, N.; Kroon, J.M.; Andriessen, H.A.J.M.; Blom, P.W.M.

    2012-01-01

    In the present review, the main degradation mechanisms occurring in the different layer stacking (i.e. photoactive layer, electrode, encapsulation film, interconnection) of polymeric organic solar cells and modules are discussed. Bulk and interfacial, as well as chemical and physical degradation

  19. Hexadecane degradation by bacterial strains isolated from ...

    African Journals Online (AJOL)

    A study was undertaken to detect and monitor the degradation of hexadecane by three potential degrading bacteria (Pseudomonas putida, Rhodococcus erythroplolis and Bacillus thermoleovorans) isolated from contaminated soils in Riyadh, Saudi Arabia. The extraction of the bacterial populations from these polluted soils ...

  20. 1 Evaluating Biophysical Attributes of Environmentally Degraded ...

    African Journals Online (AJOL)

    `123456789jkl''''#

    2 Department of Plant and Horticultural Sciences College of Agriculture, Hawassa University, P.O.Box 5 Hawassa, Ethiopia. 1. Evaluating ... Biophysical attributes of environmentally degraded landscapes in Adwa district, northern Ethiopia, were evaluated using ...... famine and environmental degradation in. Ethiopian ...

  1. VISIBLE LIGHT INDUCED PHOTOCATALYTIC DEGRADATION OF ...

    African Journals Online (AJOL)

    a

    Photocatalytic degradation of eosin and erythrosin-B (xanthene dyes) has been carried out using anthracene semiconductor ... KEY WORDS: Photocatalytic, Degradation, Xanthene dyes, Immobilized anthracene ... light intensity was measured with the help of a solarimeter (Surya Mapi Model CEL 201, India). The progress ...

  2. Pt/C Fuel Cell Catalyst Degradation

    DEFF Research Database (Denmark)

    Zana, Alessandro

    This thesis investigates the degradation behavior of Pt/C catalysts under simulated automotive conditions. By using the “tool box” synthesis method the Pt loading has been changed from low to high Pt loadings, therefore permitting to study the role of Pt on the degradation of high surface area (H...

  3. Single gene retrieval from thermally degraded DNA

    Indian Academy of Sciences (India)

    Unknown

    To simulate single gene retrieval from ancient DNA, several related factors have been investigated. By monitoring a. 889 bp polymerase chain reaction (PCR) product and genomic DNA degradation, we find that heat and oxygen. (especially heat) are both crucial factors influencing DNA degradation. The heat influence ...

  4. Single gene retrieval from thermally degraded DNA

    Indian Academy of Sciences (India)

    To simulate single gene retrieval from ancient DNA, several related factors have been investigated. By monitoring a 889 bp polymerase chain reaction (PCR) product and genomic DNA degradation, we find that heat and oxygen (especially heat) are both crucial factors influencing DNA degradation. The heat influence ...

  5. Geodiversity and land degradation in Hungary

    Science.gov (United States)

    Őrsi, Anna

    2014-05-01

    Geodiversity represents a variety of natural values, but they are threatened by a series of anthropogenic activities and land degradation processes. Their effect depends on the intensity of the processes and the sensitivity of the area in question. As a consequence of land degradation processes not only biodiversity but also geodiversity can be damaged and deteriorated. The appearance of the natural landscape changes and natural processes may not have a decisive role in landscape development any more. Some of the damages are irreversible because fundamental changes happen in the landscape, or the processes having created the original forms are no longer in operation. Small scale land degradation processes may be reversible if nature is still capable of reproducing the original state. The most important land degradation processes are desertification and soil erosion. Mining, waste disposal, urbanisation and construction activities, agriculture, inaccurate forest and water management, tourism, unsuitable land use can also lead to severe land degradation problems. The objective of the paper is to show Hungarian examples to all land degradation processes that threaten geodiversity. The results will be shown on a series of maps showing land degradation processes endangering geodiversity in Hungary. A detailed analysis of smaller study sites will be provided to show the effects of certain land degradation processes on landform development and on the changes of geodiversity. This research is supported by the Hungarian Scientific Research Fund (OTKA), project Nr. 10875.

  6. Photocatalytic degradation of explosives contaminated water.

    Science.gov (United States)

    Lee, S J; Son, H S; Lee, H K; Zoh, K D

    2002-01-01

    This study was undertaken to examine the degradation of TNT, RDX and HMX in a circular photocatalytic reactor with TiO2 as a photocatalyst. We examined the impact of parameters such as the initial concentration, initial pH of solution on rates of photocatalized transformation, and the mineralization. The results showed that photocatalysis is an effective process for the degradation of TNT, RDX and HMX. They could be comoletely degraded in 150 min with 1.0 g/L TiO2 at pH 7. An increase in the photocatalytic degradation of HMX was noticed with decreasing initial HMX. The rates of RDX and HMX degradation were greater in neutral pH than in acidic and alkaline conditions. In case of TNT degradation, the rate of degradation was the fastest at pH 11. Approximately 82% TOC decrease in the TNT degradation was achieved after 150 min, whereas TOC decrease in RDX and HMX was 24% and 59%, respectively. Nitrate, nitrite, and ammonium ions were detected as the nitrogen byproducts from the photocatalysis, and more than 50% of the total nitrogen was recovered as nitrate ion in every explosives.

  7. Evaluating Biophysical Attributes of Environmentally Degraded ...

    African Journals Online (AJOL)

    Forests and woodlands were dominant on high mountains, steep slopes and depressions, while degraded shrublands and scrublands were prominent on Leptosols and on dissected uplands and hills. On the ... Keywords: Land cover, land degradation, soil erosion, land rehabilitation, deforestation, Ethiopian highlands ...

  8. Thermal degradation of glucosinolates in red cabbage

    NARCIS (Netherlands)

    Oerlemans, K.; Barrett, D.M.; Bosch Suades, C.; Verkerk, R.; Dekker, M.

    2006-01-01

    Thermal degradation of individual glucosinolates within the plant matrix was studied. Red cabbage samples were heated at different temperatures for various times. To rule out the influence of enzymatic breakdown and to focus entirely on the thermal degradation of glucosinolates, myrosinase was

  9. Polycyclic aromatic hydrocarbons (PAHs) degradation by laccase ...

    African Journals Online (AJOL)

    Laccase enzyme was produced from an isolate of the white rot fungus, Ganoderma lucidum Chaaim-001 BCU. The enzyme was subsequently evaluated for its degradative ability towards sixteen types of polycyclic aromatic hydrocarbons (PAHs). The G. lucidum laccase degraded antracene completely with or without a ...

  10. Human-induced Soil Degradation Activities

    NARCIS (Netherlands)

    Baren, van J.H.V.; Oldeman, L.R.

    1998-01-01

    Soil degradation is occurring over vast areas. The GLASOD and ASSOD projects reflect the present status of human-induced soil degradation and its impact on food productivity related to productivity changes observed in the recent past. However, there is a great need for well-documented, reliable soil

  11. Soil degradation, land use and sustainability

    Science.gov (United States)

    Soil degradation is a complex process and directly affects the physical, chemical and biological processes within the soil profile. Degradation processes can be linked to changes in the physical structure of the soil directly affecting the infiltration of water and movement of gases, while the chemi...

  12. A longer, closer, look at land degradation

    NARCIS (Netherlands)

    Bai, Z.G.; Dent, D.L.; Olsson, L.; Tengberg, A.; Tucker, C.; Yengoh, G.

    2015-01-01

    Arresting land degradation, not to mention remediation, requires long-term investment. Budgetary constraints mean that we have to prioritise, so decision makers need know exactly where and how severe is the degradation, and they need early warning to act in good time. The first global assessment

  13. Photocatalytic degradation of geosmin: Reaction pathway analysis ...

    African Journals Online (AJOL)

    The presence of geosmin in drinking water imparts a musty odour which leads to consumer complaints. Geosmin and other unwanted organics can be treated using photocatalysis. However, the intermediates formed during the photocatalytic degradation process and their degradation pathways have not previously been ...

  14. Degradable borate glass polyalkenoate cements.

    Science.gov (United States)

    Shen, L; Coughlan, A; Towler, M; Hall, M

    2014-04-01

    Glass polyalkenoate cements (GPCs) containing aluminum-free borate glasses having the general composition Ag2O-Na2O-CaO-SrO-ZnO-TiO2-B2O3 were evaluated in this work. An initial screening study of sixteen compositions was used to identify regions of glass formation and cement compositions with promising rheological properties. The results of the screening study were used to develop four model borate glass compositions for further study. A second round of rheological experiments was used to identify a preferred GPC formulation for each model glass composition. The model borate glasses containing higher levels of TiO2 (7.5 mol %) tended to have longer working times and shorter setting times. Dissolution behavior of the four model GPC formulations was evaluated by measuring ion release profiles as a function of time. All four GPC formulations showed evidence of incongruent dissolution behavior when considering the relative release profiles of sodium and boron, although the exact dissolution profile of the glass was presumably obscured by the polymeric cement matrix. Compression testing was undertaken to evaluate cement strength over time during immersion in water. The cements containing the borate glass with 7.5 mol % TiO2 had the highest initial compressive strength, ranging between 20 and 30 MPa. No beneficial aging effect was observed-instead, the strength of all four model GPC formulations was found to degrade with time.

  15. Technology-Use Mediation

    DEFF Research Database (Denmark)

    Bansler, Jørgen P.; Havn, Erling C.

    2003-01-01

    This study analyzes how a group of ‘mediators’ in a large, multinational company adapted a computer-mediated communication technology (a ‘virtual workspace’) to the organizational context (and vice versa) by modifying features of the technology, providing ongoing support for users, and promoting...... of technology-use mediation is more complex and indeterminate than earlier literature suggests. In particular, we want to draw attention to the fact that advanced computer-mediated communication technologies are equivocal and that technology-use mediation consequently requires ongoing sensemaking (Weick 1995)....... appropriate conventions of use. Our findings corroborate earlier research on technology-use mediation, which suggests that such mediators can exert considerable influence on how a particular technology will be established and used in an organization. However, this study also indicates that the process...

  16. OXIDATIVE DEGRADATION OF 2-CHLOROPHENOL BY PERSULFATE

    Directory of Open Access Journals (Sweden)

    Krzysztof Kuśmierek

    2015-06-01

    Full Text Available The degradation of 2-chlorophenol (2-CP by persulfate was investigated. The kinetics of persulfate oxidation of 2-chlorophenol in aqueous solutions at various pH, oxidant concentration, temperature, Fe2+ and Cu2+ ions content was studied. Maximum of 2-CP degradation occurred at pH 8. The oxidation rate of 2-CP increased with increasing the persulfate molar excess. The degradation process was significantly influenced by temperature – the higher temperature results in a faster degradation of 2-CP. The activation of persulfate by ferrous and copper ions was also studied. Results showed that persulfate is activated more effectively by iron(II than copper(II ions. A comparison of different persulfate activation methods revealed that heat-activation was the most effective. Under optimal conditions, in the presence of ferrous ions at 50 °C, complete degradation of 2-chlorophenol was achieved after about 30 minutes.

  17. Degradation of ochratoxin a by Brevibacterium species.

    Science.gov (United States)

    Rodriguez, Hector; Reveron, Ines; Doria, Francesca; Costantini, Antonella; De Las Rivas, Blanca; Muňoz, Rosario; Garcia-Moruno, Emilia

    2011-10-12

    The ability to degrade ochratoxin A was studied in different bacteria with a well-known capacity to transform aromatic compounds. Strains belonging to Rhodococcus, Pseudomonas, and Brevibacterium genera were grown in liquid synthetic culture medium containing ochratoxin A. Brevibacterium spp. strains showed 100% degradation of ochratoxin A. Ochratoxin α was detected and identified by high-performance liquid chromatography-mass spectrometry (HPLC-MS) as a degradation product in the cell-free supernatants. The degradation of ochratoxin A is of public concern for food and environmental safety, because it could contribute to the development of new biological ochratoxin A detoxification systems in foodstuffs. In this study, the degradation of ochratoxin A by bacteria belonging to the food chain was demonstrated for the first time.

  18. Mitofusin 1 is degraded at G2/M phase through ubiquitylation by MARCH5

    Directory of Open Access Journals (Sweden)

    Park Yong-Yea

    2012-12-01

    Full Text Available Abstract Background Mitochondria exhibit a dynamic morphology in cells and their biogenesis and function are integrated with the nuclear cell cycle. In mitotic cells, the filamentous network structure of mitochondria takes on a fragmented form. To date, however, whether mitochondrial fusion activity is regulated in mitosis has yet to be elucidated. Findings Here, we report that mitochondria were found to be fragmented in G2 phase prior to mitotic entry. Mitofusin 1 (Mfn1, a mitochondrial fusion protein, interacted with cyclin B1, and their interactions became stronger in G2/M phase. In addition, MARCH5, a mitochondrial E3 ubiquitin ligase, reduced Mfn1 levels and the MARCH5-mediated Mfn1 ubiquitylation were enhanced in G2/M phase. Conclusions Mfn1 is degraded through the MARCH5-mediated ubiquitylation in G2/M phase and the cell cycle-dependent degradation of Mfn1 could be facilitated by interaction with cyclin B1/Cdk1 complexes.

  19. Recent land degradation and improvement in China.

    Science.gov (United States)

    Bai, Zhanguo; Dent, David

    2009-05-01

    Land degradation is a global development and environment issue that afflicts China more than most countries in terms of the extent, economic impact, and number of people affected. Up-to-date, quantitative information is needed to support policy and action for food and water security, economic development, and environmental integrity. Data for a defined, recent period enable us to distinguish the legacy of historical land degradation from what is happening now. We define land degradation as long-term decline in ecosystem function and productivity and measure it by remote sensing of the normalized difference vegetation index (NDVI), the greenness index. NDVI may be translated to net primary productivity (NPP). Deviation from the norm serves as a proxy assessment of land degradation and improvement-if other factors that may be responsible are taken into account. These other factors include climate, which may be assessed by rain-use efficiency and energy-use efficiency. Analysis of the 23-year Global Inventory Modeling and Mapping Studies (GIMMS) NDVI data reveals that, in China over the period 1981-2003, NPP increased overall, but areas of declining climate-adjusted NPP comprise 23% of the country, mainly in south China. About 35% of China's population (457 million out of 1317 million) depend on the degrading land. Degrading areas suffered a loss of NPP of 12 kgC ha(-1) y(-1), amounting to almost 60 million tC not fixed from the atmosphere; loss of soil organic carbon from these areas is likely to be orders of magnitude greater. There is no correlation between land degradation and dry lands; it is more of an issue in cropland and forest: 21% of degrading land is cropland and 40% is forest, 24% of the arable and 44% of the forest, respectively. There is no simple statistical relationship between land degradation and rural population density or poverty. Most identified land degradation is in the south and east, driven by unprecedented land-use change.

  20. The Endosome-associated Deubiquitinating Enzyme USP8 Regulates BACE1 Enzyme Ubiquitination and Degradation.

    Science.gov (United States)

    Yeates, Eniola Funmilayo Aduke; Tesco, Giuseppina

    2016-07-22

    The β-site amyloid precursor protein-cleaving enzyme (BACE1) is the rate-limiting enzyme in the production of amyloid-β, the toxic peptide that accumulates in the brain of subjects affected by Alzheimer disease. Our previous studies have shown that BACE1 is degraded via the lysosomal pathway and that that depletion of the trafficking molecule Golgi-localized γ-ear-containing ARF-binding protein 3 (GGA3) results in increased BACE1 levels and activity because of impaired lysosomal degradation. We also determined that GGA3 regulation of BACE1 levels requires its ability to bind ubiquitin. Accordingly, we reported that BACE1 is ubiquitinated at lysine 501 and that lack of ubiquitination at lysine 501 produces BACE1 stabilization. Ubiquitin conjugation is a reversible process mediated by deubiquitinating enzymes. The ubiquitin-specific peptidase 8 (USP8), an endosome-associated deubiquitinating enzyme, regulates the ubiquitination, trafficking, and lysosomal degradation of several plasma membrane proteins. Here, we report that RNAi-mediated depletion of USP8 reduced levels of both ectopically expressed and endogenous BACE1 in H4 human neuroglioma cells. Moreover, USP8 depletion increased BACE1 ubiquitination, promoted BACE1 accumulation in the early endosomes and late endosomes/lysosomes, and decreased levels of BACE1 in the recycling endosomes. We also found that decreased BACE1 protein levels were accompanied by a decrease in BACE1-mediated amyloid precursor protein cleavage and amyloid-β levels. Our findings demonstrate that USP8 plays a key role in the trafficking and degradation of BACE1 by deubiquitinating lysine 501. These studies suggest that therapies able to accelerate BACE1 degradation (e.g. by increasing BACE1 ubiquitination) may represent a potential treatment for Alzheimer disease. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. The Endosome-associated Deubiquitinating Enzyme USP8 Regulates BACE1 Enzyme Ubiquitination and Degradation*

    Science.gov (United States)

    Yeates, Eniola Funmilayo Aduke; Tesco, Giuseppina

    2016-01-01

    The β-site amyloid precursor protein-cleaving enzyme (BACE1) is the rate-limiting enzyme in the production of amyloid-β, the toxic peptide that accumulates in the brain of subjects affected by Alzheimer disease. Our previous studies have shown that BACE1 is degraded via the lysosomal pathway and that that depletion of the trafficking molecule Golgi-localized γ-ear-containing ARF-binding protein 3 (GGA3) results in increased BACE1 levels and activity because of impaired lysosomal degradation. We also determined that GGA3 regulation of BACE1 levels requires its ability to bind ubiquitin. Accordingly, we reported that BACE1 is ubiquitinated at lysine 501 and that lack of ubiquitination at lysine 501 produces BACE1 stabilization. Ubiquitin conjugation is a reversible process mediated by deubiquitinating enzymes. The ubiquitin-specific peptidase 8 (USP8), an endosome-associated deubiquitinating enzyme, regulates the ubiquitination, trafficking, and lysosomal degradation of several plasma membrane proteins. Here, we report that RNAi-mediated depletion of USP8 reduced levels of both ectopically expressed and endogenous BACE1 in H4 human neuroglioma cells. Moreover, USP8 depletion increased BACE1 ubiquitination, promoted BACE1 accumulation in the early endosomes and late endosomes/lysosomes, and decreased levels of BACE1 in the recycling endosomes. We also found that decreased BACE1 protein levels were accompanied by a decrease in BACE1-mediated amyloid precursor protein cleavage and amyloid-β levels. Our findings demonstrate that USP8 plays a key role in the trafficking and degradation of BACE1 by deubiquitinating lysine 501. These studies suggest that therapies able to accelerate BACE1 degradation (e.g. by increasing BACE1 ubiquitination) may represent a potential treatment for Alzheimer disease. PMID:27302062

  2. Carbon capture and sequestration: an exploratory inhalation toxicity assessment of amine-trapping solvents and their degradation products.

    Science.gov (United States)

    McDonald, Jacob D; Kracko, Dean; Doyle-Eisele, Melanie; Garner, C Edwin; Wegerski, Chris; Senft, Al; Knipping, Eladio; Shaw, Stephanie; Rohr, Annette

    2014-09-16

    Carbon dioxide (CO2) absorption with aqueous amine solvents is a method of carbon capture and sequestration (CCS) from flue gases. One concern is the possible release of amine solvents and degradation products into the atmosphere, warranting evaluation of potential pulmonary effects from inhalation. The CCS amines monoethanolamine (MEA), methyldiethanolamine (MDEA), and piperazine (PIP) underwent oxidative and CO2-mediated degradation for 75 days. C57bl/6N mice were exposed for 7 days by inhalation of 25 ppm neat amine or equivalant concentration in the degraded mixture. The aqueous solutions were nebulized to create the inhalation atmospheres. Pulmonary response was measured by changes in inflammatory cells in bronchoalveolar lavage fluid and cytokine expression in lung tissue. Ames mutagenicity and CHO-K1 micronucleus assays were applied to assess genotoxicity. Chemical analysis of the test atmosphere and liquid revealed complex mixtures, including acids, aldehydes, and other compounds. Exposure to oxidatively degraded MEA increased (p < 0.05) total cells, neutrophils, and lymphocytes compared to control mice and caused inflammatory cytokine expression (statistical increase at p < 0.05). MEA and CO2-degraded MEA were the only atmospheres to show statistical (p < 0.05) increase in oxidative stress. CO2 degradation resulted in a different composition, less degradation, and lower observed toxicity (less magnitude and number of effects) with no genotoxicity. Overall, oxidative degradation of the amines studied resulted in enhanced toxicity (increased magnitude and number of effects) compared to the neat chemicals.

  3. The VTLISFG motif in the BH1 domain plays a significant role in regulating the degradation of Mcl-1.

    Science.gov (United States)

    Xiao, Kang; Chen, Pengxuan; Chang, Donald Choy

    2014-01-01

    Mcl-1 is a member of the Bcl-2 family protein; its degradation is required for the initiation of apoptosis. The mechanism, however, is not yet clearly known. Previously, it was reported that Mcl-1 is degraded through the ubiquitination-mediated pathway and the PEST domain is the motif responsible for promoting this degradation. We found evidence that this may not be true. We generated several Mcl-1 deletion mutants and examined their effects on protein stability. Deletion of the PEST domain did not prevent the degradation of Mcl-1 during apoptosis. The BH1 domain, but not the PEST, BH3 or BH2 domain, exhibited a short half-life. A peptide named "F3" (VTLISFG) in the C-terminus of the BH1 domain appears to be critical for the rapid turnover of Mcl-1. Deletion of F3 from GFP-Mcl-1-ΔPEST retarded the degradation of this mutant. F3 appeared to be the minimum functional sequence of the degradation motif, since deletion of a single residue was sufficient to abrogate its short half-life. Fusion of F3 with p32 resulted in the degradation of p32 during UV-induced apoptosis, while wild type p32 was not affected. Taken together, these findings suggest that F3 (VTLISFG), instead of PEST, is the major motif responsible for the degradation of Mcl-1 during apoptosis.

  4. Degradation of polycyclic aromatic hydrocarbons by crude extracts from spent mushroom substrate and its possible mechanisms.

    Science.gov (United States)

    Li, Xuanzhen; Lin, Xiangui; Zhang, Jing; Wu, Yucheng; Yin, Rui; Feng, Youzhi; Wang, Yong

    2010-05-01

    Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by pure laccase has been reported, but the high cost limited its application in environmental bioremediation. Here, we reported a study about PAHs degradation by crude extracts (CEs) containing laccase, which were obtained by extracting four spent mushroom (Agaricus bisporus, Pleurotus eryngii, Pleurotus ostreatus, and Coprinus comatus) substrates. The results showed that anthracene, benzo[a]pyrene, and benzo[a]anthracene were top three degradable PAHs by CEs while naphthalene was most recalcitrant. The PAHs oxidation was enhanced in the presence of 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Laccase included in CE might play a major role in PAHs degradation. The maximum degradation rate of anthracene and benzo[a]pyrene was observed by using crude extracts from P. eryngii while the highest laccase activities were found in crude extracts from A. bisporus, moreover, crude extracts from P. eryngii, which contained less laccase activities, degraded more anthracene and benzo[a]pyrene than pure laccase with higher laccase activities. The lack of correlation between laccase activity and PAHs degradation rate indicated that other factors might also influence the PAHs degradation. Boiled CEs were added to determine the effect on PAHs degradation by laccase. The results showed that all four boiled CEs had improved the PAHs oxidation. The maximum improvement was observed by adding CEs from P. eryngii. It suggested that some mediators indeed existed in CEs and CEs from P. eryngii contained most. As a result, CEs from P. eryngii has the most application potential in PAHs bioremediation.

  5. Photo-degradation of high efficiency fullerene-free polymer solar cells.

    Science.gov (United States)

    Upama, Mushfika Baishakhi; Wright, Matthew; Mahmud, Md Arafat; Elumalai, Naveen Kumar; Mahboubi Soufiani, Arman; Wang, Dian; Xu, Cheng; Uddin, Ashraf

    2017-12-07

    Polymer solar cells are a promising technology for the commercialization of low cost, large scale organic solar cells. With the evolution of high efficiency (>13%) non-fullerene polymer solar cells, the stability of the cells has become a crucial parameter to be considered. Among the several degradation mechanisms of polymer solar cells, burn-in photo-degradation is relatively less studied. Herein, we present the first systematic study of photo-degradation of novel PBDB-T:ITIC fullerene-free polymer solar cells. The thermally treated and as-prepared PBDB-T:ITIC solar cells were exposed to continuous 1 sun illumination for 5 hours. The aged devices exhibited rapid losses in the short-circuit current density and fill factor. The severe short-circuit current and fill factor burn in losses were attributed to trap mediated charge recombination, as evidenced by an increase in Urbach energy for aged devices.

  6. Adherens junction turnover: regulating adhesion through cadherin endocytosis, degradation, and recycling

    Science.gov (United States)

    Nanes, Benjamin A.; Kowalczyk, Andrew P.

    2014-01-01

    Adherens junctions are important mediators of intercellular adhesion, but they are not static structures. They are regularly formed, broken, and rearranged in a variety of situations, requiring changes in the amount of cadherins, the main adhesion molecule in adherens junctions, present at the cell surface. Thus, endocytosis, degradation, and recycling of cadherins are crucial for dynamic regulation of adherens junctions and control of intercellular adhesion. In this chapter, we review the involvement of cadherin endocytosis in development and disease. We discuss the various endocytic pathways available to cadherins, the adaptors involved, and the sorting of internalized cadherin for recycling or lysosomal degradation. In addition, we review the regulatory pathways controlling cadherin endocytosis and degradation, including regulation of cadherin endocytosis by catenins, cadherin ubiquitination, and growth factor receptor signaling pathways. Lastly, we discuss the proteolytic cleavage of cadherins at the plasma membrane. PMID:22674073

  7. Coral reef fish predator maintains olfactory acuity in degraded coral habitats.

    Directory of Open Access Journals (Sweden)

    Michael Natt

    Full Text Available Coral reefs around the world are rapidly degrading due to a range of environmental stressors. Habitat degradation modifies the sensory landscape within which predator-prey interactions occur, with implications for olfactory-mediated behaviours. Predator naïve settlement-stage damselfish rely on conspecific damage-released odours (i.e., alarm odours to inform risk assessments. Yet, species such as the Ambon damselfish, Pomacentrus amboinensis, become unable to respond appropriately to these cues when living in dead-degraded coral habitats, leading to increased mortality through loss of vigilance. Reef fish predators also rely on odours from damaged prey to locate, assess prey quality and engage in prey-stealing, but it is unknown whether their responses are also modified by the change to dead-degraded coral habitats. Implications for prey clearly depend on how their predatory counterparts are affected, therefore the present study tested whether olfactory-mediated foraging responses in the dusky dottyback, Pseudochromis fuscus, a common predator of P. amboinensis, were similarly affected by coral degradation. A y-maze was used to measure the ability of Ps. fuscus to detect and move towards odours, against different background water sources. Ps. fuscus were exposed to damage-released odours from juvenile P. amboinensis, or a control cue of seawater, against a background of seawater treated with either healthy or dead-degraded hard coral. Predators exhibited an increased time allocation to the chambers of y-mazes injected with damage-released odours, with comparable levels of response in both healthy and dead-degraded coral treated waters. In control treatments, where damage-released odours were replaced with a control seawater cue, fish showed no increased preference for either chamber of the y-maze. Our results suggest that olfactory-mediated foraging behaviours may persist in Ps. fuscus within dead-degraded coral habitats. Ps. fuscus may

  8. Development of tailored indigenous marine consortia for the degradation of naturally weathered polyethylene films

    OpenAIRE

    Syranidou, Evdokia; Karkanorachaki, Katerina; Amorotti, Filippo; Repouskou, Eftychia; Kroll, Kevin; Kolvenbach, Boris; Corvini, Philippe F-X; Fava, Fabio; Kalogerakis, Nicolas

    2017-01-01

    This study investigated the potential of bacterial-mediated polyethylene (PE) degradation in a two-phase microcosm experiment. During phase I, naturally weathered PE films were incubated for 6 months with the indigenous marine community alone as well as bioaugmented with strains able to grow in minimal medium with linear low-density polyethylene (LLDPE) as the sole carbon source. At the end of phase I the developed biofilm was harvested and re-inoculated with naturally weathered PE films. Bac...

  9. Simultaneous Cellulose Degradation and Electricity Production by Enterobacter cloacae in a Microbial Fuel Cell▿

    OpenAIRE

    Rezaei, Farzaneh; Xing, Defeng; Wagner, Rachel; Regan, John M.; Richard, Tom L.; Logan, Bruce E.

    2009-01-01

    Electricity can be directly generated by bacteria in microbial fuel cells (MFCs) from many different biodegradable substrates. When cellulose is used as the substrate, electricity generation requires a microbial community with both cellulolytic and exoelectrogenic activities. Cellulose degradation with electricity production by a pure culture has not been previously demonstrated without addition of an exogenous mediator. Using a specially designed U-tube MFC, we enriched a consortium of exoel...

  10. Fenofibrate activates Nrf2 through p62-dependent Keap1 degradation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong Su [Severance Biomedical Science Institute (Korea, Republic of); Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Kang, Dong Hoon [Department of Life Science and Ewha Research Center for Systems Biology (Korea, Republic of); The Research Center for Cell Homeostasis, Ewha Womans University, Seoul 127-750 (Korea, Republic of); Lee, Da Hyun [Severance Biomedical Science Institute (Korea, Republic of); Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Bae, Soo Han, E-mail: soohanbae@yuhs.ac [Severance Biomedical Science Institute (Korea, Republic of); Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of)

    2015-09-25

    Peroxisome proliferator-activated receptor α (PPARα) activates the β-oxidation of fatty acids in the liver. Fenofibrate is a potent agonist of PPARα and is used in the treatment of hyperlipidemia. Fenofibrate treatment often induces the production of intracellular reactive oxygen species (ROS), leading to cell death. The nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway is an essential component of the defense mechanism against oxidative stress. However, the molecular mechanism underlying the regulation of the Nrf2-Keap1 pathway in fenofibrate-induced cell death is not known. In this study, we demonstrated that fenofibrate induces Keap1 degradation and Nrf2 activation. This fenofibrate-mediated Keap1 degradation is partly dependent on autophagy. Furthermore, fenofibrate-induced Keap1 degradation followed by Nrf2 activation is mainly mediated by p62, which functions as an adaptor protein in the autophagic pathway. Consistent with these findings, ablation of p62 increased fenofibrate-mediated apoptotic cell death associated with ROS accumulation. These results strongly suggest that p62 plays a crucial role in preventing fenofibrate-induced cell death. - Highlights: • Fenofibrate induces cell death by increasing ROS production. • The underlying defense mechanism against this effect is unknown. • Fenofibrate induces autophagy-dependent Keap1 degradation and Nrf2 activation. • This process is p62-dependent; lack of p62 enhanced fenofibrate-mediated apoptosis. • p62 plays a crucial role in preventing fenofibrate-induced cell death.

  11. Latitudinal gradients in degradation of marine dissolved organic carbon

    DEFF Research Database (Denmark)

    Arnosti, Carol; Steen, Andrew; Ziervogel, Kai

    2011-01-01

    Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC). The specific means by which these communities mediate the transformations of organic carbon are largely...... unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars). Genomic investigations provide information...... about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76 ºS to 79 ºN to hydrolyze a range of high...

  12. Smad3 recruits the anaphase-promoting complex for ubiquitination and degradation of SnoN

    Energy Technology Data Exchange (ETDEWEB)

    Stroschein, Shannon L.; Bonni, Shirin; Wrana, Jeffrey L.; Luo, Kunxin

    2001-09-11

    Smad proteins mediate transforming growth factor-b signaling to regulate cell growth and differentiation. SnoN is an important negative regulator of TGFb signaling that functions to maintain the repressed state of TGFb target genes in the absence of ligand. Upon TGFb stimulation, Smad3 and Smad2 translocate into the nucleus and induce a rapid degradation of SnoN, allowing activation of TGFb target genes. Here we show that Smad2- or Smad3-induced degradation of SnoN requires the ubiquitin-dependent proteasome and can be mediated by the anaphase promoting complex (APC) and the UbcH5 family of ubiquitin conjugating enzymes. Smad3 and to a lesser extent, Smad2, interact with both the APC and SnoN, resulting in the recruitment of the APC to SnoN and subsequent ubiquitination of SnoN in a destruction box-dependent manner. In addition to the destruction box, efficient degradation of SnoN also requires the Smad3 binding site in SnoN as well as key lysine residues necessary for ubiquitin attachment. Mutation of either the Smad3 binding site or lysine residues results in stabilization of SnoN and in enhanced antagonism of TGFb signaling. Our studies elucidate an important pathway for the degradation of SnoN and reveal a novel role of the APC in regulation of TGFb signaling.

  13. Strain-Dependent Effect of Macroautophagy on Abnormally Folded Prion Protein Degradation in Infected Neuronal Cells.

    Directory of Open Access Journals (Sweden)

    Daisuke Ishibashi

    Full Text Available Prion diseases are neurodegenerative disorders caused by the accumulation of abnormal prion protein (PrPSc in the central nervous system. With the aim of elucidating the mechanism underlying the accumulation and degradation of PrPSc, we investigated the role of autophagy in its degradation, using cultured cells stably infected with distinct prion strains. The effects of pharmacological compounds that inhibit or stimulate the cellular signal transduction pathways that mediate autophagy during PrPSc degradation were evaluated. The accumulation of PrPSc in cells persistently infected with the prion strain Fukuoka-1 (FK, derived from a patient with Gerstmann-Sträussler-Scheinker syndrome, was significantly increased in cultures treated with the macroautophagy inhibitor 3-methyladenine (3MA but substantially reduced in those treated with the macroautophagy inducer rapamycin. The decrease in FK-derived PrPSc levels was mediated, at least in part, by the phosphatidylinositol 3-kinase/MEK signalling pathway. By contrast, neither rapamycin nor 3MA had any apparently effect on PrPSc from either the 22L or the Chandler strain, indicating that the degradation of PrPSc in host cells might be strain-dependent.

  14. Aging-associated modifications of collagen affect its degradation by matrix metalloproteinases.

    Science.gov (United States)

    Panwar, Preety; Butler, Georgina S; Jamroz, Andrew; Azizi, Pouya; Overall, Christopher M; Brömme, Dieter

    2017-06-17

    The natural aging process and various pathologies correlate with alterations in the composition and the structural and mechanical integrity of the connective tissue. Collagens represent the most abundant matrix proteins and provide for the overall stiffness and resilience of tissues. The structural changes of collagens and their susceptibility to degradation are associated with skin wrinkling, bone and cartilage deterioration, as well as cardiovascular and respiratory malfunctions. Here, matrix metalloproteinases (MMPs) are major contributors to tissue remodeling and collagen degradation. During aging, collagens are modified by mineralization, accumulation of advanced glycation end-products (AGEs), and the depletion of glycosaminoglycans (GAGs), which affect fiber stability and their susceptibility to MMP-mediated degradation. We found a reduced collagenolysis in mineralized and AGE-modified collagen fibers when compared to native fibrillar collagen. GAGs had no effect on MMP-mediated degradation of collagen. In general, MMP digestion led to a reduction in the mechanical strength of native and modified collagen fibers. Successive fiber degradation with MMPs and the cysteine-dependent collagenase, cathepsin K (CatK), resulted in their complete degradation. In contrast, MMP-generated fragments were not or only poorly cleaved by non-collagenolytic cathepsins such as cathepsin V (CatV). In conclusion, our data indicate that aging and disease-associated collagen modifications reduce tissue remodeling by MMPs and decrease the structural and mechanic integrity of collagen fibers, which both may exacerbate extracellular matrix pathology. Copyright © 2017 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.

  15. Growth Arrest on Inhibition of Nonsense-Mediated Decay Is Mediated by Noncoding RNA GAS5

    Directory of Open Access Journals (Sweden)

    Mirna Mourtada-Maarabouni

    2013-01-01

    Full Text Available Nonsense-mediated decay is a key RNA surveillance mechanism responsible for the rapid degradation of mRNAs containing premature termination codons and hence prevents the synthesis of truncated proteins. More recently, it has been shown that nonsense-mediated decay also has broader significance in controlling the expression of a significant proportion of the transcriptome. The importance of this mechanism to the mammalian cell is demonstrated by the observation that its inhibition causes growth arrest. The noncoding RNA growth arrest specific transcript 5 (GAS5 has recently been shown to play a key role in growth arrest induced by several mechanisms, including serum withdrawal and treatment with the mTOR inhibitor rapamycin. Here we show that inhibition of nonsense-mediated decay in several human lymphocyte cell lines causes growth arrest, and siRNA-mediated downregulation of GAS5 in these cells significantly alleviates the inhibitory effects observed. These observations hold true for inhibition of nonsense-mediated decay both through RNA interference and through pharmacological inhibition by aminoglycoside antibiotics gentamycin and G418. These studies have important implications for ototoxicity and nephrotoxicity caused by gentamycin and for the proposed use of NMD inhibition in treating genetic disease. This report further demonstrates the critical role played by GAS5 in the growth arrest of mammalian cells.

  16. Growth Arrest on Inhibition of Nonsense-Mediated Decay Is Mediated by Noncoding RNA GAS5

    Science.gov (United States)

    Mourtada-Maarabouni, Mirna; Williams, Gwyn T.

    2013-01-01

    Nonsense-mediated decay is a key RNA surveillance mechanism responsible for the rapid degradation of mRNAs containing premature termination codons and hence prevents the synthesis of truncated proteins. More recently, it has been shown that nonsense-mediated decay also has broader significance in controlling the expression of a significant proportion of the transcriptome. The importance of this mechanism to the mammalian cell is demonstrated by the observation that its inhibition causes growth arrest. The noncoding RNA growth arrest specific transcript 5 (GAS5) has recently been shown to play a key role in growth arrest induced by several mechanisms, including serum withdrawal and treatment with the mTOR inhibitor rapamycin. Here we show that inhibition of nonsense-mediated decay in several human lymphocyte cell lines causes growth arrest, and siRNA-mediated downregulation of GAS5 in these cells significantly alleviates the inhibitory effects observed. These observations hold true for inhibition of nonsense-mediated decay both through RNA interference and through pharmacological inhibition by aminoglycoside antibiotics gentamycin and G418. These studies have important implications for ototoxicity and nephrotoxicity caused by gentamycin and for the proposed use of NMD inhibition in treating genetic disease. This report further demonstrates the critical role played by GAS5 in the growth arrest of mammalian cells. PMID:24319682

  17. The novel E3 ubiquitin ligase Tiul1 associates with TGIF to target Smad2 for degradation

    Science.gov (United States)

    Seo, Su Ryeon; Lallemand, François; Ferrand, Nathalie; Pessah, Marcia; L'Hoste, Sébastien; Camonis, Jacques; Atfi, Azeddine

    2004-01-01

    Ubiquitin-dependent degradation plays an important role in the negative regulation of TGF-β signaling. Here, we identify Tiul1 (for TGIF interacting ubiquitin ligase 1), a novel E3 ubiquitin ligase that inhibits TGF-β signaling by targeting both the activated receptor and Smad2 for degradation. Tiul1 associates constitutively with Smad7 and induces degradation of the activated type I receptor without affecting the expression levels of Smad7. Tiul1 can also interact with Smad2 and the nuclear corepressor TGIF upon activation of TGF-β signaling. Like Smad7, the steady-state levels of TGIF are not affected by Tiul1, but the interaction of Tiul1 with TGIF allows this ubiquitin ligase to target Smad2 for degradation. Consistent with this, overexpression of Tiul1 suppressed TGF-β-induced growth arrest and transcriptional responses. In addition, silencing of Tiul1 or TGIF genes by siRNA resulted in suppression of the TGF-β-dependent degradation of Smad2 and an enhancement of TGF-β-mediated gene expression. These results reveal a new role for TGIF as a component of a ubiquitin ligase complex that mediates the degradation of Smad2 in response to TGF-β signaling. PMID:15359284

  18. Degradation of Endrin, Aldrin, and DDT by Soil Microorganisms 1

    Science.gov (United States)

    Patil, K. C.; Matsumura, F.; Boush, G. M.

    1970-01-01

    Twenty microbial cultures which had been shown to degrade dieldrin were tested to determine their ability to degrade endrin, aldrin, DDT, gamma isomers of benzenehexachloride (γ-BHC), and Baygon. All isolates were able to degrade DDT and endrin, whereas 13 degraded aldrin. However, none of them was able to degrade Baygon or γ-BHC. PMID:4192889

  19. Latitudinal gradients in degradation of marine dissolved organic carbon.

    Directory of Open Access Journals (Sweden)

    Carol Arnosti

    Full Text Available Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC. The specific means by which these communities mediate the transformations of organic carbon are largely unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars. Genomic investigations provide information about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76°S to 79°N to hydrolyze a range of high molecular weight organic substrates and thereby initiate organic matter degradation. These data demonstrate the existence of a latitudinal gradient in the range of complex substrates available to heterotrophic microbial communities, paralleling the global gradient in bacterial species richness. As changing climate increasingly affects the marine environment, changes in the spectrum of substrates accessible by microbial communities may lead to shifts in the location and rate at which marine DOC is respired. Since the inventory of DOC in the ocean is comparable in magnitude to the atmospheric CO(2 reservoir, such a change could profoundly affect the global carbon cycle.

  20. Degradation of azo dyes by environmental microorganisms and helminths

    Energy Technology Data Exchange (ETDEWEB)

    Kingthom Chung; Stevens, S.E. Jr. (Memphis State Univ., TN (United States). Dept. of Biology)

    1993-11-01

    The degradation of azo dyes by environmental microorganisms, fungi, and helminths is reviewed. Azo dyes are used in a wide variety of products and can be found in the effluent of most sewage treatment facilities. Substantial quantities of these dyes have been deposited in the environment, particularly in streams and rivers. Azo dyes were shown to affect microbial activities and microbial population sizes in the sediments and in the water columns of aquatic habitats. Only a few aerobic bacteria have been found to reduce azo dyes under aerobic conditions, and little is known about the process. A substantial number of anaerobic bacteria capable of azo dye reduction have been reported. The enzyme responsible for azo dye reduction has been partially purified, and characterization of the enzyme is proceeding. The nematode Ascaris lumbricoides and the cestode Moniezia expanza have been reported to reduce azo dyes anaerobically. Recently the fungus Phanerochaete chrysoporium was reported to mineralize azo dyes via a peroxidation-mediated pathway. A possible degradation pathway for the mineralization of azo dye is proposed and future research needs are discussed.

  1. FEM1 proteins are ancient regulators of SLBP degradation.

    Science.gov (United States)

    Dankert, John F; Pagan, Julia K; Starostina, Natalia G; Kipreos, Edward T; Pagano, Michele

    2017-03-19

    FEM1A, FEM1B, and FEM1C are evolutionarily-conserved VHL-box proteins, the substrate recognition subunits of CUL2-RING E3 ubiquitin ligase complexes. Here, we report that FEM1 proteins are ancient regulators of Stem-Loop Binding Protein (SLBP), a conserved protein that interacts with the stem loop structure located in the 3' end of canonical histone mRNAs and functions in mRNA cleavage, translation and degradation. SLBP levels are highest during S-phase coinciding with histone synthesis. The ubiquitin ligase complex SCF(cyclin F) targets SLBP for degradation in G2 phase; however, the regulation of SLBP during other stages of the cell cycle is poorly understood. We provide evidence that FEM1A, FEM1B, and FEM1C interact with and mediate the degradation of SLBP. Cyclin F, FEM1A, FEM1B and FEM1C all interact with a region in SLBP's N-terminus using distinct degrons. An SLBP mutant that is unable to interact with all 4 ligases is expressed at higher levels than wild type SLBP and does not oscillate during the cell cycle. We demonstrate that orthologues of SLBP and FEM1 proteins interact in C. elegans and D. melanogaster, suggesting that the pathway is evolutionarily conserved. Furthermore, we show that FEM1 depletion in C. elegans results in the upregulation of SLBP ortholog CDL-1 in oocytes. Notably, cyclin F is absent in flies and worms, suggesting that FEM1 proteins play an important role in SLBP targeting in lower eukaryotes.

  2. CHIP Regulates Osteoclast Formation through Promoting TRAF6 Protein Degradation

    Science.gov (United States)

    Li, Shan; Shu, Bing; Zhang, Yanquan; Li, Jia; Guo, Junwei; Wang, Yinyin; Ren, Fangli; Xiao, Guozhi; Chang, Zhijie; Chen, Di

    2014-01-01

    Objective Carboxyl terminus of Hsp70-interacting protein (CHIP or STUB1) is an E3 ligase and regulates the stability of several proteins which are involved in tumor growth and metastasis. However, the role of CHIP in bone growth and bone remodeling in vivo has not been reported. The objective of this study is to investigate the role and mechanism of CHIP in regulation of bone mass and bone remodeling. Methods The bone phenotype of Chip−/− mice was examined by histology, histomorphometry and micro-CT analyses. The regulatory mechanism of CHIP on the degradation of TRAF6 and the inhibition of NF-κB signaling was examined by immunoprecipitation (IP), western blotting and luciferase reporter assays. Results In this study, we found that deletion of the Chip gene leads to osteopenic phenotype and increased osteoclast formation. We further found that TRAF6, as a novel substrate of CHIP, is up-regulated in Chip−/− osteoclasts. TRAF6 is critical for RANKL-induced osteoclastogenesis. TRAF6 is an adaptor protein which functions as an E3 ligase to regulate the activation of TAK1 and the I-κB kinase (IKK) and is a key regulator of NF-κB signaling. CHIP interacts with TRAF6 to promote TRAF6 ubiquitination and proteasome degradation. CHIP inhibits p65 nuclear translocation, leading to the repression of the TRAF6-mediated NF-κB transcription. Conclusion CHIP inhibits NF-κB signaling via promoting TRAF6 degradation and plays an important role in osteoclastogenesis and bone remodeling, suggesting that it may be a novel therapeutic target for the treatment of bone loss associated diseases. PMID:24578159

  3. Thermolytic Degradation of Synthetic Cannabinoids: Chemical Exposures and Pharmacological Consequences.

    Science.gov (United States)

    Thomas, Brian F; Lefever, Timothy W; Cortes, Ricardo A; Grabenauer, Megan; Kovach, Alexander L; Cox, Anderson O; Patel, Purvi R; Pollard, Gerald T; Marusich, Julie A; Kevin, Richard C; Gamage, Thomas F; Wiley, Jenny L

    2017-04-01

    Synthetic cannabinoids are manufactured clandestinely with little quality control and are distributed as herbal "spice" for smoking or as bulk compound for mixing with a solvent and inhalation via electronic vaporizers. Intoxication with synthetic cannabinoids has been associated with seizure, excited delirium, coma, kidney damage, and other disorders. The chemical alterations produced by heating these structurally novel compounds for consumption are largely unknown. Here, we show that heating synthetic cannabinoids containing tetramethylcyclopropyl-ring substituents produced thermal degradants with pharmacological activity that varied considerably from their parent compounds. Moreover, these degradants were formed under conditions simulating smoking. Some products of combustion retained high affinity at the cannabinoid 1 (CB1) and CB2 receptors, were more efficacious than (-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol (CP55,940) in stimulating CB1 receptor-mediated guanosine 5'-O-(3-thiotriphosphate) (GTPγS) binding, and were potent in producing Δ9-tetrahydrocannabinol-like effects in laboratory animals, whereas other compounds had low affinity and efficacy and were devoid of cannabimimetic activity. Degradants that retained affinity and efficacy also substituted in drug discrimination tests for the prototypical synthetic cannabinoid 1-pentyl-3-(1-naphthoyl)indole (JWH-018), and are likely to produce psychotropic effects in humans. Hence, it is important to take into consideration the actual chemical exposures that occur during use of synthetic cannabinoid formulations to better comprehend the relationships between dose and effect. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

  4. Mycotoxin-degradation profile of Rhodococcus strains.

    Science.gov (United States)

    Cserháti, M; Kriszt, B; Krifaton, Cs; Szoboszlay, S; Háhn, J; Tóth, Sz; Nagy, I; Kukolya, J

    2013-08-16

    Mycotoxins are secondary fungal metabolites that may have mutagenic, carcinogenic, cytotoxic and endocrine disrupting effects. These substances frequently contaminate agricultural commodities despite efforts to prevent them, so successful detoxification tools are needed. The application of microorganisms to biodegrade mycotoxins is a novel strategy that shows potential for application in food and feed processing. In this study we investigated the mycotoxin degradation ability of thirty-two Rhodococcus strains on economically important mycotoxins: aflatoxin B1, zearalenone, fumonisin B1, T2 toxin and ochratoxin A, and monitored the safety of aflatoxin B1 and zearalenone degradation processes and degradation products using previously developed toxicity profiling methods. Moreover, experiments were performed to analyse multi-mycotoxin-degrading ability of the best toxin degrader/detoxifier strains on aflatoxin B1, zearalenone and T2 toxin mixtures. This enabled the safest and the most effective Rhodococcus strains to be selected, even for multi-mycotoxin degradation. We concluded that several Rhodococcus species are effective in the degradation of aromatic mycotoxins and their application in mycotoxin biodetoxification processes is a promising field of biotechnology. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Heterogeneous photocatalytic degradation of monochlorobenzene in water.

    Science.gov (United States)

    Huang, Hsin-Hsu; Tseng, Dyi-Hwa; Juang, Lain-Chuen

    2008-08-15

    This investigation evaluated the photocatalytic degradation of monochlorobenzene (MCB) in an aqueous TiO(2) suspension. In accordance with the experimental results, the degradation of MCB was a function of the initial substrate concentration, incident light intensity, and TiO(2) dosage. However, the solution pH had insignificant effect on the degradation efficiency. The heterogeneous photocatalytic degradation of MCB followed the Langmuir-Hinshelwood kinetics. The adsorption coefficient of MCB (K) and the observed degradation rate constant (k) were calculated as 13.4 mM(-1) and 0.0054 mM min(-1), respectively. In addition, a 0.255 dependency of the initial degradation rate on the light intensity revealed the considerable adverse effect of e(-)-h(+) pair recombination. Both mineralization and dechlorination occurred during the photocatalytic degradation of MCB. Under the operating condition of initial MCB concentration of 0.1mM, light intensity of 5.68 microEinsteins(-1), TiO(2) dosage of 1.0 g L(-1), and solution pH of 7, about 93.7% of MCB was mineralized after 240 min of irradiation. Nevertheless, 64.3% of the stoichiometric amount of Cl(-) ions was released into the bulk solution. The simulation results derived from the X-ray photoelectron spectroscopy (XPS) analysis was suggested that the interaction between Cl(-) ions and TiO(2) surface tended to lower the released amount of Cl(-) ions.

  6. DDT degradation potential of cattle manure compost.

    Science.gov (United States)

    Purnomo, Adi Setyo; Koyama, Futoshi; Mori, Toshio; Kondo, Ryuichiro

    2010-07-01

    The purpose of this study was to investigate the ability of cattle manure compost (CMC) to degrade 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT). DDT was degraded during composting and 1,1-dichloro-2,2-bis (4-chlorophenyl) ethane (DDD) was detected as a metabolic product. Degradation of DDT at 60 degrees C was the most effective of all the stages of composting. Fourteen strains of fungi were isolated and identified from CMC, and most of them were closely related to Mucor circinelloides and Galactomyces geotrichum. These fungi demonstrated a high ability to degrade DDT both at 30 and 60 degrees C in potato dextrose broth (PDB) medium. DDD and 4,4-dichlorobenzophenone (DBP) were detected as metabolic products. Degradation of DDT-contaminated soil was also investigated. Composting materials in the mesophilic stage exhibited the highest ability to degrade DDT in un-sterilized (USL) contaminated soil during a 28d incubation period. The isolated fungi possessed the ability to degrade DDT in sterilized (SL) and un-sterilized (USL) soils. These results indicated that CMC contains fungi that can be potentially used for bioremediation in DDT-contaminated environments. 2010 Elsevier Ltd. All rights reserved.

  7. Cellular contractility requires ubiquitin mediated proteolysis.

    Directory of Open Access Journals (Sweden)

    Yuval Cinnamon

    Full Text Available BACKGROUND: Cellular contractility, essential for cell movement and proliferation, is regulated by microtubules, RhoA and actomyosin. The RhoA dependent kinase ROCK ensures the phosphorylation of the regulatory Myosin II Light Chain (MLC Ser19, thereby activating actomyosin contractions. Microtubules are upstream inhibitors of contractility and their depolymerization or depletion cause cells to contract by activating RhoA. How microtubule dynamics regulates RhoA remains, a major missing link in understanding contractility. PRINCIPAL FINDINGS: We observed that contractility is inhibited by microtubules not only, as previously reported, in adherent cells, but also in non-adhering interphase and mitotic cells. Strikingly we observed that contractility requires ubiquitin mediated proteolysis by a Cullin-RING ubiquitin ligase. Inhibition of proteolysis, ubiquitination and neddylation all led to complete cessation of contractility and considerably reduced MLC Ser19 phosphorylation. CONCLUSIONS: Our results imply that cells express a contractility inhibitor that is degraded by ubiquitin mediated proteolysis, either constitutively or in response to microtubule depolymerization. This degradation seems to depend on a Cullin-RING ubiquitin ligase and is required for cellular contractions.

  8. Applied mediation analyses

    DEFF Research Database (Denmark)

    Lange, Theis; Hansen, Kim Wadt; Sørensen, Rikke

    2017-01-01

    In recent years, mediation analysis has emerged as a powerful tool to disentangle causal pathways from an exposure/treatment to clinically relevant outcomes. Mediation analysis has been applied in scientific fields as diverse as labour market relations and randomized clinical trials of heart...

  9. Targeted Degradation of Proteins Localized in Subcellular Compartments by Hybrid Small Molecules.

    Science.gov (United States)

    Okuhira, Keiichiro; Shoda, Takuji; Omura, Risa; Ohoka, Nobumichi; Hattori, Takayuki; Shibata, Norihito; Demizu, Yosuke; Sugihara, Ryo; Ichino, Asato; Kawahara, Haruka; Itoh, Yukihiro; Ishikawa, Minoru; Hashimoto, Yuichi; Kurihara, Masaaki; Itoh, Susumu; Saito, Hiroyuki; Naito, Mikihiko

    2017-03-01

    Development of novel small molecules that selectively degrade pathogenic proteins would provide an important advance in targeted therapy. Recently, we have devised a series of hybrid small molecules named SNIPER (specific and nongenetic IAP-dependent protein ERaser) that induces the degradation of target proteins via the ubiquitin-proteasome system. To understand the localization of proteins that can be targeted by this protein knockdown technology, we examined whether SNIPER molecules are able to induce degradation of cellular retinoic acid binding protein II (CRABP-II) proteins localized in subcellular compartments of cells. CRABP-II is genetically fused with subcellular localization signals, and they are expressed in the cells. SNIPER(CRABP) with different IAP-ligands, SNIPER(CRABP)-4 with bestatin and SNIPER(CRABP)-11 with MV1 compound, induce the proteasomal degradation of wild-type (WT), cytosolic, nuclear, and membrane-localized CRABP-II proteins, whereas only SNIPER(CRABP)-11 displayed degradation activity toward the mitochondrial CRABP-II protein. The small interfering RNA-mediated silencing of cIAP1 expression attenuated the knockdown activity of SNIPER(CRABP) against WT and cytosolic CRABP-II proteins, indicating that cIAP1 is the E3 ligase responsible for degradation of these proteins. Against membrane-localized CRABP-II protein, cIAP1 is also a primary E3 ligase in the cells, but another E3 ligase distinct from cIAP2 and X-linked inhibitor of apoptosis protein (XIAP) could also be involved in the SNIPER(CRABP)-11-induced degradation. However, for the degradation of nuclear and mitochondrial CRABP-II proteins, E3 ligases other than cIAP1, cIAP2, and XIAP play a role in the SNIPER-mediated protein knockdown. These results indicate that SNIPER can target cytosolic, nuclear, membrane-localized, and mitochondrial proteins for degradation, but the responsible E3 ligase is different, depending on the localization of the target protein. Copyright © 2017 by

  10. Fungal degradation of nitrocellulose under aerobic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, A.; Sundaram, S.T.; Zhang, Y.Z. [Geo-Centers, Inc., Lake Hopatcong, NJ (United States); Brodman, B.W. [Armaments Research Development and Engineering Center, Picatinny Arsenal, NJ (United States)

    1995-12-31

    Mycelial fungi were screened alone or in combinations for their ability to degrade nitrocellulose (3 g/L) in liquid medium. All of the fungi tested used nitrocellulose to a varying extent, but a combination of Sclerotium rolfsii ATCC 24459 and Fusarium solani IFO 31093 was found to be the best because it significantly degraded nitrocellulose. About 38% of the nitrocellulose was degraded by these fungi in a 7-day period when the culture medium was buffered at pH 6.0 with morphilino ethane sulfonic acid.

  11. Microbial degradation of the organophosphate pesticide, Ethion.

    Science.gov (United States)

    Foster, L John R; Kwan, Bia H; Vancov, Tony

    2004-11-01

    The organophosphate pesticide, Ethion, remains a major environmental contaminant in rural Australia and poses a significant threat to environmental and public health. The aerobic degradation of Ethion by mesophilic bacteria isolated from contaminated soils surrounding disused cattle dip sites was investigated. Two isolates, identified as Pseudomonas and Azospirillum species, were capable of biodegrading Ethion when cultivated in minimal salts medium. The abiotic hydrolytic degradation products of Ethion such as Ethion Dioxon and O,O-diethylthiosphosphate were not detected. The data suggest the rapid degradation of Ethion to support microbial growth. The results have implications for the development of a bioremediation strategy.

  12. Restoration of degraded images using genetic programming

    Science.gov (United States)

    Hernández-Beltrán, José Enrique; Díaz-Ramírez, Víctor H.; Trujillo, Leonardo; Legrand, Pierrick

    2016-09-01

    In image restoration problems it is commonly assumed that image degradations are linear. In real-life this assumption is not always satisfied causing linear restoration methods fail. In this work, we present the design of an image restoration filtering based on genetic programming. The proposed filtering is given by a secuence of basic mathematical operators that allows to retrieve an undegraded image from an image degraded with noise. Computer simulations results obtained with the proposed algorithm in terms of objective metrics are analyzed and discussed by processing images degraded with noise. The obtained results are compared with those obtained with existing linear filters.

  13. Autonomous valve for detection of biopolymer degradation

    DEFF Research Database (Denmark)

    Keller, Stephan Urs; Noeth, Nadine-Nicole; Fetz, Stefanie

    2009-01-01

    We present a polymer microvalve that allows the detection of biopolymer degradation without the need of external energy. The valve is based on a polymer container filled with a colored marker solution and closed by a thin lid. This structure is covered by a film of poly(L-lactide) and degradation...... of the biopolymer triggers the release of the color which is detected visually. The autonomous valve has potential for the fast testing of biopolymer degradation under various environmental conditions or by specific enzymes....

  14. Music, radio and mediatization

    DEFF Research Database (Denmark)

    Michelsen, Morten; Krogh, Mads

    2016-01-01

    Mediatization has become a key concept for understanding the relations between media and other cultural and social fields. Contributing to the discussions related to the concept of mediatization, this article discusses how practices of radio and music(al life) influence each other. We follow Deacon......’s and Stanyer’s advice to supplement the concept of mediatization with ‘a series of additional concepts at lower levels of abstraction’ and suggest, in this respect, the notion of heterogeneous milieus of music–radio. Hereby, we turn away from the all-encompassing perspectives related to the concept...... of mediatization where media as such seem to be ascribed agency. Instead, we consider historical accounts of music–radio in order to address the complex nonlinearity of concrete processes of mediatization as they take place in the multiple meetings between a decentred notion of radio and musical life....

  15. Proteasomal degradation of p53 by human papillomavirus E6 oncoprotein relies on the structural integrity of p53 core domain.

    Directory of Open Access Journals (Sweden)

    Xavier Bernard

    Full Text Available The E6 oncoprotein produced by high-risk mucosal HPV stimulates ubiquitinylation and proteasome-dependent degradation of the tumour suppressor p53 via formation of a trimeric complex comprising E6, p53, and E6-AP. p53 is also degraded by its main cellular regulator MDM2. The main binding site of p53 to MDM2 is situated in the natively unfolded N-terminal region of p53. By contrast, the regions of p53 implicated in the degradation by viral E6 are not fully identified to date. Here we generated a series of mutations (Y103G, Y107G, T155A, T155V, T155D, L264A, L265A targeting the central folded core domain of p53 within a region opposite to its DNA-binding site. We analysed by in vitro and in vivo assays the impact of these mutations on p53 degradation mediated by viral E6 oncoprotein. Whereas all mutants remained susceptible to MDM2-mediated degradation, several of them (Y103G, Y107G, T155D, L265A became resistant to E6-mediated degradation, confirming previous works that pointed to the core domain as an essential region for the degradation of p53. In parallel, we systematically checked the impact of the mutations on the transactivation activity of p53 as well as on the conformation of p53, analysed by Nuclear Magnetic Resonance (NMR, circular dichroism (CD, and antibody probing. These measurements suggested that the conformational integrity of the core domain is an essential parameter for the degradation of p53 by E6, while it is not essential for the degradation of p53 by MDM2. Thus, the intracellular stability of a protein may or may not rely on its biophysical stability depending on the degradation pathway taken into consideration.

  16. Rising population and environmental degradation.

    Science.gov (United States)

    Mitra, A

    Environmental degradation is becoming an increasingly ominous threat to the well-being of India's population, and excessive population growth is the primary cause of environmental deterioration. Population growth increases the need to produce consumer products and this need, in turn, intensifies the trend to over-exploit and misuse environmental resources. Efforts to control population growth through contraceptive technology and the expansion of family planning services and to control environmental deterioration via technology and management will meet with little success. A prerequisite for controlling these dual problems is the improvement of living conditions for the masses. Only when individuals acquire a sense of security and have the prospect of acquiring a share in the resources of the country will they be willing to conserve and renew resources and to limit their fertility. Viewed from this prospective, various factors and trends in India can be assessed as either negative or positive. Positive factors, i.e., those which enhance economic oppotunities and security for the general population, include the recent achievement of economic grothw in the country's agricultural and industrial sectors, the growth in technological knowledge, and the expansion of the rural and urban infrastructure. Negative factors include 1) the increase in income inequality, 2) the refusal to grant distributive justice to the masses, 3) the lack of education which impedes public understanding and awareness of environmental issues and promotes under utilization of community and social services, 4) the high unemployment rate which prevents individuals from developing a sense of responsibility and self respect; and 5) the refusal of the government to establish fuel policies to halt the growing problem of deforestation. Major environmental problems include pollution and congestion associated with the geographical concentration of industry; the destruction of the forests which leads to

  17. Degradation-by-design: Surface modification with functional substrates that enhance the enzymatic degradation of carbon nanotubes.

    Science.gov (United States)

    Sureshbabu, Adukamparai Rajukrishnan; Kurapati, Rajendra; Russier, Julie; Ménard-Moyon, Cécilia; Bartolini, Isacco; Meneghetti, Moreno; Kostarelos, Kostas; Bianco, Alberto

    2015-12-01

    Biodegradation of carbon-based nanomaterials has been pursued intensively in the last few years, as one of the most crucial issues for the design of safe, clinically relevant conjugates for biomedical applications. In this paper it is demonstrated that specific functional molecules can enhance the catalytic activity of horseradish peroxidase (HRP) and xanthine oxidase (XO) for the degradation of carbon nanotubes. Two different azido coumarins and one cathecol derivative are linked to multi-walled carbon nanotubes (MWCNTs). These molecules are good reducing substrates and strong redox mediators to enhance the catalytic activity of HRP. XO, known to metabolize various molecules mainly in the mammalian liver, including human, was instead used to test the biodegradability of MWCNTs modified with an azido purine. The products of the biodegradation process are characterized by transmission electron microscopy and Raman spectroscopy. The results indicate that coumarin and catechol moieties have enhanced the biodegradation of MWCNTs compared to oxidized nanotubes, likely due to the capacity of these substrates to better interact with and activate HRP. Although azido purine-MWCNTs are degraded less effectively by XO than oxidized nanotubes, the data uncover the importance of XO in the biodegradation of carbon-nanomaterials leading to their better surface engineering for biomedical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. TRAIL sensitize MDR cells to MDR-related drugs by down-regulation of P-glycoprotein through inhibition of DNA-PKcs/Akt/GSK-3β pathway and activation of caspases

    Science.gov (United States)

    2010-01-01

    Background The development of new modulator possessing high efficacy, low toxicity and high selectivity is a pivotal approach to overcome P-glycoprotein (P-gp) mediated multidrug resistance (MDR) in cancer treatment. In this study, we suggest a new molecular mechanism that TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) down-regulates P-glycoprotein (P-gp) through inhibition of DNA-PKcs/Akt/GSK-3β pathway and activation of caspases and thereby sensitize MDR cells to MDR-related drugs. Results MDR variants, CEM/VLB10-2, CEM/VLB55-8 and CEM/VLB100 cells, with gradually increased levels of P-gp derived from human lymphoblastic leukemia CEM cells, were gradually more susceptible to TRAIL-induced apoptosis and cytotoxicity than parental CEM cells. The P-gp level of MDR variants was positively correlated with the levels of DNA-PKcs, pAkt, pGSK-3β and c-Myc as well as DR5 and negatively correlated with the level of c-FLIPs. Hypersensitivity of CEM/VLB100 cells to TRAIL was accompanied by the activation of mitochondrial apoptotic pathway as well as the activation of initiator caspases. In addition, TRAIL-induced down-regulation of DNA-PKcs/Akt/GSK-3β pathway and c-FLIP and up-regulation of cell surface expression of death receptors were associated with the increased susceptibility to TRAIL of MDR cells. Moreover, TRAIL inhibited P-gp efflux function via caspase-3-dependent degradation of P-gp as well as DNA-PKcs and subsequently sensitized MDR cells to MDR-related drugs such as vinblastine and doxorubicin. We also found that suppression of DNA-PKcs by siRNA enhanced the susceptibility of MDR cells to vincristine as well as TRAIL via down-regulation of c-FLIP and P-gp expression and up-regulation of DR5. Conclusion This study showed for the first time that the MDR variant of CEM cells was hypersensitive to TRAIL due to up-regulation of DR5 and concomitant down-regulation of c-FLIP, and degradation of P-gp and DNA-PKcs by activation of caspase-3 might be

  19. TMEM129 is a Derlin-1 associated ERAD E3 ligase essential for virus-induced degradation of MHC-I.

    Science.gov (United States)

    van den Boomen, Dick J H; Timms, Richard T; Grice, Guinevere L; Stagg, Helen R; Skødt, Karsten; Dougan, Gordon; Nathan, James A; Lehner, Paul J

    2014-08-05

    The US11 gene product of human cytomegalovirus promotes viral immune evasion by hijacking the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway. US11 initiates dislocation of newly translocated MHC I from the ER to the cytosol for proteasome-mediated degradation. Despite the critical role for ubiquitin in this degradation pathway, the responsible E3 ligase is unknown. In a forward genetic screen for host ERAD components hijacked by US11 in near-haploid KBM7 cells, we identified TMEM129, an uncharacterized polytopic membrane protein. TMEM129 is essential and rate-limiting for US11-mediated MHC-I degradation and acts as a novel ER resident E3 ubiquitin ligase. TMEM129 contains an unusual cysteine-only RING with intrinsic E3 ligase activity and is recruited to US11 via Derlin-1. Together with its E2 conjugase Ube2J2, TMEM129 is responsible for the ubiquitination, dislocation, and subsequent degradation of US11-associated MHC-I. US11 engages two degradation pathways: a Derlin-1/TMEM129-dependent pathway required for MHC-I degradation and a SEL1L/HRD1-dependent pathway required for "free" US11 degradation. Our data show that TMEM129 is a novel ERAD E3 ligase and the central component of a novel mammalian ERAD complex.

  20. Constitutive and ligand-induced TCR degradation

    DEFF Research Database (Denmark)

    von Essen, Marina; Bonefeld, Charlotte Menné; Siersma, Volkert

    2004-01-01

    divergent models for TCR down-regulation and degradation have been suggested. The aims of this study were to determine the rate constants for constitutive and ligand-induced TCR degradation and to determine whether the TCR subunits segregate or are processed as an intact unit during TCR down...... to the lysosomes. Similar results were obtained in studies of primary human Vbeta8+ T cells stimulated with superantigen. Based on these results, the simplest model for TCR internalization, sorting, and degradation is proposed.......Modulation of TCR expression levels is a central event during T cell development and activation, and it probably plays an important role in adjusting T cell responsiveness. Conflicting data have been published on down-regulation and degradation rates of the individual TCR subunits, and several...

  1. Degradation Behavior of Thermal Stabilized Polyacrylonitrile Fibers

    Directory of Open Access Journals (Sweden)

    LEI Shuai

    2017-05-01

    Full Text Available In the temperature range of 300-800℃, 40%-50% of the mass lost during the processing of polyacrylonitrile based carbon fiber (PANCF. Understanding the degradation behavior will be valuable in understanding the formation mechanism of pseudo-graphite structure, and providing theoretic basis for producing high performance carbon fiber and increasing the carbonization yield. The simulation of the degradation progress was carried out on the thermogravimetric analyzer (TGA, the results show that there are two degradation steps for PAN fiber stabilized in air, and controlled by cyclization coefficient and oxygen content. The cyclization coefficient and oxygen content are effective to the density of carbon fiber by influencing the degradation behavior, which cause defects in the fiber. The higher cyclization coefficient leads to form less structural defects and higher density of the fiber; on the contrary, the higher oxygen content leads to form more structural defects and lower density of the fiber.

  2. Lignin degradation in wood-feeding insects.

    Science.gov (United States)

    Geib, Scott M; Filley, Timothy R; Hatcher, Patrick G; Hoover, Kelli; Carlson, John E; Jimenez-Gasco, Maria del Mar; Nakagawa-Izumi, Akiko; Sleighter, Rachel L; Tien, Ming

    2008-09-02

    The aromatic polymer lignin protects plants from most forms of microbial attack. Despite the fact that a significant fraction of all lignocellulose degraded passes through arthropod guts, the fate of lignin in these systems is not known. Using tetramethylammonium hydroxide thermochemolysis, we show lignin degradation by two insect species, the Asian longhorned beetle (Anoplophora glabripennis) and the Pacific dampwood termite (Zootermopsis angusticollis). In both the beetle and termite, significant levels of propyl side-chain oxidation (depolymerization) and demethylation of ring methoxyl groups is detected; for the termite, ring hydroxylation is also observed. In addition, culture-independent fungal gut community analysis of A. glabripennis identified a single species of fungus in the Fusarium solani/Nectria haematococca species complex. This is a soft-rot fungus that may be contributing to wood degradation. These results transform our understanding of lignin degradation by wood-feeding insects.

  3. Degradation of magnetite nanoparticles in biomimetic media

    Energy Technology Data Exchange (ETDEWEB)

    Briceño, Sarah; Hernandez, Ana C.; Sojo, Juan [Instituto Venezolano de Investigaciones Científicas (IVIC), Laboratorio de Materiales, Centro de Ingeniería de Materiales y Nanotecnología (Venezuela, Bolivarian Republic of); Lascano, Luis [Dpto. Física, Escuela Politécnica Nacional (Ecuador); Gonzalez, Gema, E-mail: gemagonz@ivic.gob.ve, E-mail: gema.gonzalez@epn.edu.ec [Escuela Nacional Politécnica (Ecuador)

    2017-04-15

    Magnetic nanoparticles (NPs) of magnetite Fe{sub 3}O{sub 4} obtained by coprecipitation (COP), thermal decomposition (DT), and commercial sample (CM) have been degraded in similar conditions to physiological medium at pH 4.7 and in simulated body fluid (SBF) at pH 7.4. The formation of the nanoparticles was confirmed by FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In view of medical and environmental applications, the stability of the particles was measured with dynamic light scattering. The degradation processes were followed with atomic absorption spectroscopy (EAA) and TEM. Magnetic measurements were carried out using vibrating sample magnetometry (VSM). Our results revealed that the structural and magnetic properties of the remaining nanoparticles after the degradation process were significantly different to those of the initial suspension. The degradation kinetics is affected by the pH, the coating, and the average particle size of the nanoparticles.

  4. Pt/C Fuel Cell Catalyst Degradation

    DEFF Research Database (Denmark)

    Zana, Alessandro

    This thesis investigates the degradation behavior of Pt/C catalysts under simulated automotive conditions. By using the “tool box” synthesis method the Pt loading has been changed from low to high Pt loadings, therefore permitting to study the role of Pt on the degradation of high surface area (HSA......) Pt/C catalyst. Diverse degradation mechanisms have been found to be responsible for the electrochemical surface area loss (ECSA). The different degradation mechanisms have been found to be dependent from the diverse potential windows applied during the stress test. Furthermore the synthesis approach......, i.e. Vulcan XC72R and Ketjenblack EC-300J. The ECSA loss measured for Vulcan XC72R was significantly higher after start/stop than for Ketjenblack EC-300J. To this concern the Pt loaded Vulcan XC72R and Ketjenblack EC- 300J has been studied by Raman spectroscopy. The Raman spectra of the catalysts...

  5. Plant Wall Degradative Compounds and Systems

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The present invention relates to cell wall degradative systems, in particular to systems containing enzymes that bind to and/or depolymerize cellulose. These systems...

  6. Bacterial degradation of monocyclic aromatic amines

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar Arora

    2015-08-01

    Full Text Available Aromatic amines are an important group of industrial chemicals, which are widely used for manufacturing of dyes, pesticides, drugs, pigments, and other industrial products. These compounds have been considered highly toxic to human beings due to their carcinogenic nature. Three groups of aromatic amines have been recognized: monocyclic, polycyclic and heterocyclic aromatic amines. Bacterial degradation of several monocyclic aromatic compounds has been studied in a variety of bacteria, which utilizes monocyclic aromatic amines as their sole source of carbon and energy. Several degradation pathways have been proposed and the related enzymes and genes have also been characterized. Many reviews have been reviewed toxicity of monocyclic aromatic amines; however, there is lack of review on biodegradation of monocyclic aromatic amines. The aim of this review is to summarize bacterial degradation of monocyclic aromatic amines. This review will increase our current understanding of biochemical and molecular basis of bacterial degradation of monocyclic aromatic amines.

  7. Enzymatic degradation of multiwalled carbon nanotubes.

    Science.gov (United States)

    Zhao, Yong; Allen, Brett L; Star, Alexander

    2011-09-01

    Because of their unique properties, carbon nanotubes and, in particular, multiwalled carbon nanotubes (MWNTs) have been used for the development of advanced composite and catalyst materials. Despite their growing commercial applications and increased production, the potential environmental and toxicological impacts of MWNTs are not fully understood; however, many reports suggest that they may be toxic. Therefore, a need exists to develop protocols for effective and safe degradation of MWNTs. In this article, we investigated the effect of chemical functionalization of MWNTs on their enzymatic degradation with horseradish peroxidase (HRP) and hydrogen peroxide (H(2)O(2)). We investigated HRP/H(2)O(2) degradation of purified, oxidized, and nitrogen-doped MWNTs and proposed a layer-by-layer degradation mechanism of nanotubes facilitated by side wall defects. These results provide a better understanding of the interaction between HRP and carbon nanotubes and suggest an eco-friendly way of mitigating the environmental impact of nanotubes. © 2011 American Chemical Society

  8. Identification and genetic characterization of phenol- degrading ...

    African Journals Online (AJOL)

    SAURABH

    2013-02-20

    . E-mail: rita@igib.res.in, anilk@nii.ac.in. #These authors contributed equally to this work. Abbreviations: MSM, Minimal salts medium; HPLC, high- performance liquid chromatography. been made to remove/degrade phenol ...

  9. Degradation characteristics of waste polyurethane by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Seok; Ahn, Sung Jun; Gwon Hui Jeong; Jeong, Sung In; Nho, Young Chang; Lim, Youn Mook [Research Division for Industry and Environment, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2017-06-15

    Polyurethane (PU) is a very popular polymer that is used in a variety of applications due to its good mechanical, thermal, and chemical properties. However, waste PU recycling has received significant attention due to environmental issues. The aim of this work was to investigate the degradation characteristics of waste PU to recycle. Degradation of waste PU was carried out using a radiation techniques. Waste PUs were exposed to a gamma {sup 60}Co sources. To verify degradation, the irradiated PUs were characterized using FT-IR, gel permeation chromatography (GPC), and their thermal/mechanical properties are reported. When the radiation dose was 500 kGy, the molecular weight of the waste PU drastically decreased. Also, the mechanical properties of waste PU were approximately 4 times lower than those of non-irradiated PU. This study has confirmed the possibility of making fine particle of waste PU for recycling through radiation degradation techniques.

  10. Protein Repair and Degradation during Aging

    Directory of Open Access Journals (Sweden)

    Bertrand Friguet

    2002-01-01

    Full Text Available Cellular aging is characterized by a build-up of oxidatively modified proteins. The steady-state level of oxidized proteins depends on the balance between the rate of protein oxidative damage and the rates of protein degradation and repair. Therefore, the accumulation of oxidized protein with age can be due to increased protein damage, decreased oxidized protein degradation and repair, or the combination of both mechanisms. The proteasomal system is the major intracellular proteolytic pathway implicated in the degradation of oxidized protein, and the peptide methionine sulfoxide reductase catalyzes the reduction of methionine sulfoxide (i.e., oxidized methionine to methionine within proteins. A short summary on protein oxidative damage and oxidized protein degradation is given, and evidence for a decline of proteasome function with age is presented. Arguments for the implication of peptide methionine sulfoxide reductase in the age-related accumulation of oxidized protein are also discussed.

  11. Photocatalytic Degradation of Organic Contaminants in Water

    Science.gov (United States)

    Photocatalytic treatment of organics, including regulated and contaminants of emerging concern, has been an important area of this field. Details are provided on the mechanism of degradation, reaction intermediates, kinetics, and nanointerfacial adsorption phenomena. The degradat...

  12. Phyllosphere bacterial communities associated with the degradation ...

    African Journals Online (AJOL)

    Phyllosphere bacterial communities associated with the degradation of acetamiprid in Phaseolus vulgaris. ... at the proper concentration, however, phyllomicobes biodegradation capability was inhibited by high concentration of the pesticide and phyllomicrobes' community was also destroyed at the same conditions.

  13. Method of degrading pollutants in soil

    Science.gov (United States)

    Hazen, Terry C.; Lopez-De-Victoria, Geralyne

    1994-01-01

    A method and system for enhancing the motility of microorganisms by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant.

  14. Restoring Soil Quality to Mitigate Soil Degradation

    National Research Council Canada - National Science Library

    Rattan Lal

    2015-01-01

    ...% between 2005 and 2050. Soil degradation, characterized by decline in quality and decrease in ecosystem goods and services, is a major constraint to achieving the required increase in agricultural production...

  15. Hot carrier degradation in semiconductor devices

    CERN Document Server

    2015-01-01

    This book provides readers with a variety of tools to address the challenges posed by hot carrier degradation, one of today’s most complicated reliability issues in semiconductor devices.  Coverage includes an explanation of carrier transport within devices and book-keeping of how they acquire energy (“become hot”), interaction of an ensemble of colder and hotter carriers with defect precursors, which eventually leads to the creation of a defect, and a description of how these defects interact with the device, degrading its performance. • Describes the intricacies of hot carrier degradation in modern semiconductor technologies; • Covers the entire hot carrier degradation phenomenon, including topics such as characterization, carrier transport, carrier-defect interaction, technological impact, circuit impact, etc.; • Enables detailed understanding of carrier transport, interaction of the carrier ensemble with the defect precursors, and an accurate assessment of how the newly created defects imp...

  16. Degradation of magnetite nanoparticles in biomimetic media

    Science.gov (United States)

    Briceño, Sarah; Hernandez, Ana C.; Sojo, Juan; Lascano, Luis; Gonzalez, Gema

    2017-04-01

    Magnetic nanoparticles (NPs) of magnetite Fe3O4 obtained by coprecipitation (COP), thermal decomposition (DT), and commercial sample (CM) have been degraded in similar conditions to physiological medium at pH 4.7 and in simulated body fluid (SBF) at pH 7.4. The formation of the nanoparticles was confirmed by FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In view of medical and environmental applications, the stability of the particles was measured with dynamic light scattering. The degradation processes were followed with atomic absorption spectroscopy (EAA) and TEM. Magnetic measurements were carried out using vibrating sample magnetometry (VSM). Our results revealed that the structural and magnetic properties of the remaining nanoparticles after the degradation process were significantly different to those of the initial suspension. The degradation kinetics is affected by the pH, the coating, and the average particle size of the nanoparticles.

  17. Arkadia, a Novel SUMO-Targeted Ubiquitin Ligase Involved in PML Degradation

    Science.gov (United States)

    Erker, Yigit; Neyret-Kahn, Helene; Seeler, Jacob S.; Dejean, Anne; Atfi, Azeddine

    2013-01-01

    Arkadia is a RING domain E3 ubiquitin ligase that activates the transforming growth factor β (TGF-β) pathway by inducing degradation of the inhibitor SnoN/Ski. Here we show that Arkadia contains three successive SUMO-interacting motifs (SIMs) that mediate noncovalent interaction with poly-SUMO2. We identify the third SIM (VVDL) of Arkadia to be the most relevant one in this interaction. Furthermore, we provide evidence that Arkadia can function as a SUMO-targeted ubiquitin ligase (STUBL) by ubiquitinating SUMO chains. While the SIMs of Arkadia are not essential for SnoN/Ski degradation in response to TGF-β, we show that they are necessary for the interaction of Arkadia with polysumoylated PML in response to arsenic and its concomitant accumulation into PML nuclear bodies. Moreover, Arkadia depletion leads to accumulation of polysumoylated PML in response to arsenic, highlighting a requirement of Arkadia for arsenic-induced degradation of polysumoylated PML. Interestingly, Arkadia homodimerizes but does not heterodimerize with RNF4, the other STUBL involved in PML degradation, suggesting that these two E3 ligases do not act synergistically but most probably act independently during this process. Altogether, these results identify Arkadia to be a novel STUBL that can trigger degradation of signal-induced polysumoylated proteins. PMID:23530056

  18. Effect of Biochar Amendment and Ageing on Adsorption and Degradation of Two Herbicides.

    Science.gov (United States)

    Zhelezova, Alena; Cederlund, Harald; Stenström, John

    2017-01-01

    Biochar amendment can alter soil properties, for instance, the ability to adsorb and degrade different chemicals. However, ageing of the biochar, due to processes occurring in the soil over time, can influence such biochar-mediated effects. This study examined how biochar affected adsorption and degradation of two herbicides, glyphosate (N-(phosphonomethyl)-glycine) and diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) in soil and how these effects were modulated by ageing of the biochar. One sandy and one clayey soil that had been freshly amended with a wood-based biochar (0, 1, 10, 20 and 30% w/w) were studied. An ageing experiment, in which the soil-biochar mixtures were aged for 3.5 months in the laboratory, was also performed. Adsorption and degradation were studied in these soil and soil-biochar mixtures, and compared to results from a soil historically enriched with charcoal. Biochar amendment increased the pH in both soils and increased the water-holding capacity of the sandy soil. Adsorption of diuron was enhanced by biochar amendment in both soils, while glyphosate adsorption was decreased in the sandy soil. Ageing of soil-biochar mixtures decreased adsorption of both herbicides in comparison with freshly biochar-amended soil. Herbicide degradation rates were not consistently affected by biochar amendment or ageing in any of the soils. However, glyphosate half-lives correlated with the Freundlich Kf values in the clayey soil, indicating that degradation was limited by availability there.

  19. Carbon Nanotube Degradation in Macrophages: Live Nanoscale Monitoring and Understanding of Biological Pathway.

    Science.gov (United States)

    Elgrabli, Dan; Dachraoui, Walid; Ménard-Moyon, Cécilia; Liu, Xiao Jie; Bégin, Dominique; Bégin-Colin, Sylvie; Bianco, Alberto; Gazeau, Florence; Alloyeau, Damien

    2015-10-27

    Despite numerous applications, the cellular-clearance mechanism of multiwalled carbon nanotubes (MWCNTs) has not been clearly established yet. Previous in vitro studies showed the ability of oxidative enzymes to induce nanotube degradation. Interestingly, these enzymes have the common capacity to produce reactive oxygen species (ROS). Here, we combined material and life science approaches for revealing an intracellular way taken by macrophages to degrade carbon nanotubes. We report the in situ monitoring of ROS-mediated MWCNT degradation by liquid-cell transmission electron microscopy. Two degradation mechanisms induced by hydroxyl radicals were extracted from these unseen dynamic nanoscale investigations: a non-site-specific thinning process of the walls and a site-specific transversal drilling process on pre-existing defects of nanotubes. Remarkably, similar ROS-induced structural injuries were observed on MWCNTs after aging into macrophages from 1 to 7 days. Beside unraveling oxidative transformations of MWCNT structure, we elucidated an important, albeit not exclusive, biological pathway for MWCNT degradation in macrophages, involving NOX2 complex activation, superoxide production, and hydroxyl radical attack, which highlights the critical role of oxidative stress in cellular processing of MWCNTs.

  20. Ferristatin II promotes degradation of transferrin receptor-1 in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Shaina L Byrne

    Full Text Available Previous studies have shown that the small molecule iron transport inhibitor ferristatin (NSC30611 acts by down-regulating transferrin receptor-1 (TfR1 via receptor degradation. In this investigation, we show that another small molecule, ferristatin II (NSC8679, acts in a similar manner to degrade the receptor through a nystatin-sensitive lipid raft pathway. Structural domains of the receptor necessary for interactions with the clathrin pathway do not appear to be necessary for ferristatin II induced degradation of TfR1. While TfR1 constitutively traffics through clathrin-mediated endocytosis, with or without ligand, the presence of Tf blocked ferristatin II induced degradation of TfR1. This effect of Tf was lost in a ligand binding receptor mutant G647A TfR1, suggesting that Tf binding to its receptor interferes with the drug's activity. Rats treated with ferristatin II have lower TfR1 in liver. These effects are associated with reduced intestinal (59Fe uptake, lower serum iron and transferrin saturation, but no change in liver non-heme iron stores. The observed hypoferremia promoted by degradation of TfR1 by ferristatin II appears to be due to induced hepcidin gene expression.

  1. Genetic and Hormonal Regulation of Chlorophyll Degradation during Maturation of Seeds with Green Embryos

    Directory of Open Access Journals (Sweden)

    Galina Smolikova

    2017-09-01

    Full Text Available The embryos of some angiosperms (usually referred to as chloroembryos contain chlorophylls during the whole period of embryogenesis. Developing embryos have photochemically active chloroplasts and are able to produce assimilates, further converted in reserve biopolymers, whereas at the late steps of embryogenesis, seeds undergo dehydration, degradation of chlorophylls, transformation of chloroplast in storage plastids, and enter the dormancy period. However, in some seeds, the process of chlorophyll degradation remains incomplete. These residual chlorophylls compromise the quality of seed material in terms of viability, nutritional value, and shelf life, and represent a serious challenge for breeders and farmers. The mechanisms of chlorophyll degradation during seed maturation are still not completely understood, and only during the recent decades the main pathways and corresponding enzymes could be characterized. Among the identified players, the enzymes of pheophorbide a oxygenase pathway and the proteins encoded by STAY GREEN (SGR genes are the principle ones. On the biochemical level, abscisic acid (ABA is the main regulator of seed chlorophyll degradation, mediating activity of corresponding catabolic enzymes on the transcriptional level. In general, a deep insight in the mechanisms of chlorophyll degradation is required to develop the approaches for production of chlorophyll-free high quality seeds.

  2. Genetic and Hormonal Regulation of Chlorophyll Degradation during Maturation of Seeds with Green Embryos.

    Science.gov (United States)

    Smolikova, Galina; Dolgikh, Elena; Vikhnina, Maria; Frolov, Andrej; Medvedev, Sergei

    2017-09-16

    The embryos of some angiosperms (usually referred to as chloroembryos) contain chlorophylls during the whole period of embryogenesis. Developing embryos have photochemically active chloroplasts and are able to produce assimilates, further converted in reserve biopolymers, whereas at the late steps of embryogenesis, seeds undergo dehydration, degradation of chlorophylls, transformation of chloroplast in storage plastids, and enter the dormancy period. However, in some seeds, the process of chlorophyll degradation remains incomplete. These residual chlorophylls compromise the quality of seed material in terms of viability, nutritional value, and shelf life, and represent a serious challenge for breeders and farmers. The mechanisms of chlorophyll degradation during seed maturation are still not completely understood, and only during the recent decades the main pathways and corresponding enzymes could be characterized. Among the identified players, the enzymes of pheophorbide a oxygenase pathway and the proteins encoded by STAY GREEN (SGR) genes are the principle ones. On the biochemical level, abscisic acid (ABA) is the main regulator of seed chlorophyll degradation, mediating activity of corresponding catabolic enzymes on the transcriptional level. In general, a deep insight in the mechanisms of chlorophyll degradation is required to develop the approaches for production of chlorophyll-free high quality seeds.

  3. Pathogenic prion protein is degraded by a manganese oxide mineral found in soils

    Science.gov (United States)

    Russo, F.; Johnson, C.J.; McKenzie, D.; Aiken, Judd M.; Pedersen, J.A.

    2009-01-01

    Prions, the aetiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. Here, we report the abiotic degradation of pathogenic prion protein (PrPTSE) by a synthetic analogue of naturally occurring birnessite minerals. Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as a solution's pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg MnO2 ml-1 (PrPTSE:MnO2=1 : 110) decreased PrPTSE levels by ???4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals. ?? 2009 SGM.

  4. Thermal degradation process of polysulfone aramid fiber

    OpenAIRE

    Zhu Fang-Long; Feng Qian-Qian; Xin Qun; Zhou Yu

    2014-01-01

    Polysulfone aramid fiber is one kind of high temperature fibers. In the paper, thermal degradation behavior and kinetics of polysulfone aramid fiber were investigated by thermogravimetric analysis and differential thermogravimetric at different heating rates under nitrogen and air, respectively. The experimental results show that its initial degradation temperature is 375°C in nitrogen and 410°C in air at heating rate of 10 K/min. When temperature went to 8...

  5. A Theoretical Model for Metal Corrosion Degradation

    OpenAIRE

    David V. Svintradze; Pidaparti, Ramana M.

    2010-01-01

    Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitt...

  6. Colourful parrot feathers resist bacterial degradation

    Science.gov (United States)

    Burtt, Edward H.; Schroeder, Max R.; Smith, Lauren A.; Sroka, Jenna E.; McGraw, Kevin J.

    2011-01-01

    The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage. PMID:20926430

  7. Degradation of cellulose by basidiomycetous fungi.

    Science.gov (United States)

    Baldrian, Petr; Valásková, Vendula

    2008-05-01

    Cellulose is the main polymeric component of the plant cell wall, the most abundant polysaccharide on Earth, and an important renewable resource. Basidiomycetous fungi belong to its most potent degraders because many species grow on dead wood or litter, in environment rich in cellulose. Fungal cellulolytic systems differ from the complex cellulolytic systems of bacteria. For the degradation of cellulose, basidiomycetes utilize a set of hydrolytic enzymes typically composed of endoglucanase, cellobiohydrolase and beta-glucosidase. In some species, the absence of cellobiohydrolase is substituted by the production of processive endoglucanases combining the properties of both of these enzymes. In addition, systems producing hydroxyl radicals based on cellobiose dehydrogenase, quinone redox cycling or glycopeptide-based Fenton reaction are involved in the degradation of several plant cell wall components, including cellulose. The complete cellulolytic complex used by a single fungal species is typically composed of more than one of the above mechanisms that contribute to the utilization of cellulose as a source of carbon or energy or degrade it to ensure fast substrate colonization. The efficiency and regulation of cellulose degradation differs among wood-rotting, litter-decomposing, mycorrhizal or plant pathogenic fungi and yeasts due to the different roles of cellulose degradation in the physiology and ecology of the individual groups.

  8. Soil Degradation: Will Humankind Ever Learn?

    Directory of Open Access Journals (Sweden)

    Douglas L. Karlen

    2015-09-01

    Full Text Available Soil degradation is a global problem caused by many factors including excessive tillage, inappropriate crop rotations, excessive grazing or crop residue removal, deforestation, mining, construction and urban sprawl. To meet the needs of an expanding global population, it is essential for humankind to recognize and understand that improving soil health by adopting sustainable agricultural and land management practices is the best solution for mitigating and reversing current soil degradation trends. This research editorial is intended to provide an overview for this Special Issue of Sustainability that examines the global problem of soil degradation through reviews and recent research studies addressing soil health in Africa, Australia, China, Europe, India, North and South America, and Russia. Two common factors—soil erosion and depletion of soil organic matter (SOM—emerge as consistent indicators of how “the thin layer covering the planet that stands between us and starvation” is being degraded. Soil degradation is not a new problem but failing to acknowledge, mitigate, and remediate the multiple factors leading to it is no longer a viable option for humankind. We optimistically conclude that the most promising strategies to mitigate soil degradation are to select appropriate land uses and improve soil management practices so that SOM is increased, soil biology is enhanced, and all forms of erosion are reduced. Collectively, these actions will enable humankind to “take care of the soil so it can take care of us”.

  9. Ubiquitination of inducible nitric oxide synthase is required for its degradation

    Science.gov (United States)

    Kolodziejski, Pawel J.; Musial, Aleksandra; Koo, Ja-Seok; Eissa, N. Tony

    2002-01-01

    Inducible nitric oxide synthase (iNOS) is responsible for nitric oxide (NO) synthesis from l-arginine in response to inflammatory mediators. We have previously shown that iNOS is degraded through the 26S proteasome. Targeting of proteins for proteasomal degradation may or may not require their covalent linkage to multiubiquitin chains (ubiquitination). In addition, ubiquitination of a protein can serve functions other than signaling proteolysis. In this context, it is not known whether iNOS is subject to ubiquitination or whether ubiquitination is required for its degradation. In this study, we show that iNOS, expressed in HEK293 cells or induced in primary bronchial epithelial cells, A549 cells, or murine macrophages, is subject to ubiquitination. To investigate whether iNOS ubiquitination is required for its degradation, HEK293T cells were cotransfected with plasmids containing cDNAs of human iNOS and of the dominant negative ubiquitin mutant K48R. Disruption of ubiquitination by K48R ubiquitin resulted in inhibition of iNOS degradation. ts20 is a mutant cell line that contains a thermolabile ubiquitin-activating enzyme (E1) that is inactivated at elevated temperature, preventing ubiquitination. Incubation of ts20 cells, stably expressing human iNOS, at the nonpermissive temperature (40°C) resulted in inhibition of iNOS degradation and marked accumulation of iNOS. These studies indicate that iNOS is subject to ubiquitination and that ubiquitination is required for its degradation. PMID:12221289

  10. Protein degradation and protein synthesis in long-term memory formation

    Directory of Open Access Journals (Sweden)

    Timothy J Jarome

    2014-06-01

    Full Text Available Long-term memory (LTM formation requires transient changes in the activity of intracellular signaling cascades that are thought to regulate new gene transcription and de novo protein synthesis in the brain. Consistent with this, protein synthesis inhibitors impair LTM for a variety of behavioral tasks when infused into the brain around the time of training or following memory retrieval, suggesting that protein synthesis is a critical step in LTM storage in the brain. However, evidence suggests that protein degradation mediated by the ubiquitin-proteasome system may also be a critical regulator of LTM formation and stability following retrieval. This requirement for increased protein degradation has been shown in the same brain regions in which protein synthesis is required for LTM storage. Additionally, increases in the phosphorylation of proteins involved in translational control parallel increases in protein polyubiquitination and the increased demand for protein degradation is regulated by intracellular signaling molecules thought to regulate protein synthesis during LTM formation. In some cases inhibiting proteasome activity can rescue memory impairments that result from pharmacological blockade of protein synthesis, suggesting that protein degradation may control the requirement for protein synthesis during the memory storage process. Results such as these suggest that protein degradation and synthesis are both critical for LTM formation and may interact to properly consolidate and store memories in the brain. Here, we review the evidence implicating protein synthesis and degradation in LTM storage and highlight the areas of overlap between these two opposing processes. We also discuss evidence suggesting these two processes may interact to properly form and store memories. LTM storage likely requires a coordinated regulation between protein degradation and synthesis at multiple sites in the mammalian brain.

  11. Identification and analysis of the RNA degrading complexes and machinery of Giardia lamblia using an in silico approach.

    Science.gov (United States)

    Williams, Christopher W; Elmendorf, Heidi G

    2011-11-29

    RNA degradation is critical to the survival of all cells. With increasing evidence for pervasive transcription in cells, RNA degradation has gained recognition as a means of regulating gene expression. Yet, RNA degradation machinery has been studied extensively in only a few eukaryotic organisms, including Saccharomyces cerevisiae and humans. Giardia lamblia is a parasitic protist with unusual genomic traits: it is binucleated and tetraploid, has a very compact genome, displays a theme of genomic minimalism with cellular machinery commonly comprised of a reduced number of protein components, and has a remarkably large population of long, stable, noncoding, antisense RNAs. Here we use in silico approaches to investigate the major RNA degradation machinery in Giardia lamblia and compare it to a broad array of other parasitic protists. We have found key constituents of the deadenylation and decapping machinery and of the 5'-3' RNA degradation pathway. We have similarly found that all of the major 3'-5' RNA degradation pathways are present in Giardia, including both exosome-dependent and exosome-independent machinery. However, we observe significant loss of RNA degradation machinery genes that will result in important differences in the protein composition, and potentially functionality, of the various RNA degradation pathways. This is most apparent in the exosome, the central mediator of 3'-5' degradation, which apparently contains an altered core configuration in both Giardia and Plasmodium, with only four, instead of the canonical six, distinct subunits. Additionally the exosome in Giardia is missing both the Rrp6, Nab3, and Nrd1 proteins, known to be key regulators of noncoding transcript stability in other cells. These findings suggest that although the full complement of the major RNA degradation mechanisms were present - and likely functional - early in eukaryotic evolution, the composition and function of the complexes is more variable than previously

  12. Identification and analysis of the RNA degrading complexes and machinery of Giardia lamblia using an in silico approach

    Science.gov (United States)

    2011-01-01

    Background RNA degradation is critical to the survival of all cells. With increasing evidence for pervasive transcription in cells, RNA degradation has gained recognition as a means of regulating gene expression. Yet, RNA degradation machinery has been studied extensively in only a few eukaryotic organisms, including Saccharomyces cerevisiae and humans. Giardia lamblia is a parasitic protist with unusual genomic traits: it is binucleated and tetraploid, has a very compact genome, displays a theme of genomic minimalism with cellular machinery commonly comprised of a reduced number of protein components, and has a remarkably large population of long, stable, noncoding, antisense RNAs. Results Here we use in silico approaches to investigate the major RNA degradation machinery in Giardia lamblia and compare it to a broad array of other parasitic protists. We have found key constituents of the deadenylation and decapping machinery and of the 5'-3' RNA degradation pathway. We have similarly found that all of the major 3'-5' RNA degradation pathways are present in Giardia, including both exosome-dependent and exosome-independent machinery. However, we observe significant loss of RNA degradation machinery genes that will result in important differences in the protein composition, and potentially functionality, of the various RNA degradation pathways. This is most apparent in the exosome, the central mediator of 3'-5' degradation, which apparently contains an altered core configuration in both Giardia and Plasmodium, with only four, instead of the canonical six, distinct subunits. Additionally the exosome in Giardia is missing both the Rrp6, Nab3, and Nrd1 proteins, known to be key regulators of noncoding transcript stability in other cells. Conclusions These findings suggest that although the full complement of the major RNA degradation mechanisms were present - and likely functional - early in eukaryotic evolution, the composition and function of the complexes is more

  13. Polyarene mediators for mediated redox flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.; Ingersoll, David; Liang, Chengdu

    2018-01-02

    The fundamental charge storage mechanisms in a number of currently studied high energy redox couples are based on intercalation, conversion, or displacement reactions. With exception to certain metal-air chemistries, most often the active redox materials are stored physically in the electrochemical cell stack thereby lowering the practical gravimetric and volumetric energy density as a tradeoff to achieve reasonable power density. In a general embodiment, a mediated redox flow battery includes a se