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Sample records for abnormal autophagy ubiquitination

  1. Ubiquitin and Autophagy%泛素与自噬

    Institute of Scientific and Technical Information of China (English)

    冯梅; 王莉新; 王易

    2011-01-01

    Protein degradation mediated by ubiquitin and autophagy are the basic mechanisms involved in cellular self-regulation. Ubiquitin may be involved in the process of autophagy by serving as a umversal recognition signal. Induction of autophagy can promote ubiquitination, thereby enhancing the degradation of substrate. This paper mainly focuses on the relation and the potential mutual regulation between ubiquitination and autophagy, as well as the phenomenon of programmed cell death that is associated with both ubiquitination and autophagy processes.%泛素调节的蛋白质降解过程和细胞的自噬现象都是细胞自我调节的基本机制.其中,泛素可能作为一种普遍的识别信号参与了自噬过程;而自噬的诱导又能促进泛素化作用,从而增强对底物的降解.本文着重探讨这两者间的关系及可能存在的相互调节作用,并兼及两者共同涉及的细胞程序性死亡现象.

  2. NBR1-mediated selective autophagy targets insoluble ubiquitinated protein aggregates in plant stress responses.

    Directory of Open Access Journals (Sweden)

    Jie Zhou

    Full Text Available Plant autophagy plays an important role in delaying senescence, nutrient recycling, and stress responses. Functional analysis of plant autophagy has almost exclusively focused on the proteins required for the core process of autophagosome assembly, but little is known about the proteins involved in other important processes of autophagy, including autophagy cargo recognition and sequestration. In this study, we report functional genetic analysis of Arabidopsis NBR1, a homolog of mammalian autophagy cargo adaptors P62 and NBR1. We isolated two nbr1 knockout mutants and discovered that they displayed some but not all of the phenotypes of autophagy-deficient atg5 and atg7 mutants. Like ATG5 and ATG7, NBR1 is important for plant tolerance to heat, oxidative, salt, and drought stresses. The role of NBR1 in plant tolerance to these abiotic stresses is dependent on its interaction with ATG8. Unlike ATG5 and ATG7, however, NBR1 is dispensable in age- and darkness-induced senescence and in resistance to a necrotrophic pathogen. A selective role of NBR1 in plant responses to specific abiotic stresses suggest that plant autophagy in diverse biological processes operates through multiple cargo recognition and delivery systems. The compromised heat tolerance of atg5, atg7, and nbr1 mutants was associated with increased accumulation of insoluble, detergent-resistant proteins that were highly ubiquitinated under heat stress. NBR1, which contains an ubiquitin-binding domain, also accumulated to high levels with an increasing enrichment in the insoluble protein fraction in the autophagy-deficient mutants under heat stress. These results suggest that NBR1-mediated autophagy targets ubiquitinated protein aggregates most likely derived from denatured or otherwise damaged nonnative proteins generated under stress conditions.

  3. Formation of distinct inclusion bodies by inhibition of ubiquitin-proteasome and autophagy-lysosome pathways

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    Lee, Junho; Yang, Kyu-Hwan; Joe, Cheol O. [Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejon 305-701 (Korea, Republic of); Kang, Seok-Seong, E-mail: sskang@ivi.int [Laboratory Sciences Division, International Vaccine Institute, Seoul 151-919 (Korea, Republic of)

    2011-01-14

    Research highlights: {yields} Distinct inclusion bodies are developed by inhibition of UPP and ALP. {yields} The inclusion bodies differ in morphology, localization and formation process. {yields} The inclusion bodies are distinguishable by the localization of TSC2. {yields} Inhibition of both UPP and ALP simultaneously induces those inclusion bodies. -- Abstract: Accumulation of misfolded proteins is caused by the impairment of protein quality control systems, such as ubiquitin-proteasome pathway (UPP) and autophagy-lysosome pathway (ALP). In this study, the formation of inclusion bodies was examined after the blockade of UPP and/or ALP in A549 cells. UPP inhibition induced a single and large inclusion body localized in microtubule-organizing center. Interestingly, however, ALP inhibition generated dispersed small inclusion bodies in the cytoplasm. Tuberous sclerosis complex 2 was selectively accumulated in the inclusion bodies of UPP-inhibited cells, but not those of ALP-inhibited cells. Blockade of transcription and translation entirely inhibited the formation of inclusion body induced by UPP inhibition, but partially by ALP inhibition. Moreover, the simultaneous inhibition of two protein catabolic pathways independently developed two distinct inclusion bodies within a single cell. These findings clearly demonstrated that dysfunction of each catabolic pathway induced formation and accumulation of unique inclusion bodies on the basis of morphology, localization and formation process in A549 cells.

  4. Autophagy facilitates TLR4- and TLR3-triggered migration and invasion of lung cancer cells through the promotion of TRAF6 ubiquitination.

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    Zhan, Zhenzhen; Xie, Xuefeng; Cao, Hao; Zhou, Xiaohui; Zhang, Xu Dong; Fan, Huimin; Liu, Zhongmin

    2014-02-01

    Autophagy contributes to the pathogenesis of cancer, whereas toll-like receptors (TLRs) also play an important role in cancer development and immune escape. However, little is known about the potential interaction between TLR signaling and autophagy in cancer cells. Here we show that autophagy induced by TLR4 or TLR3 activation enhances various cytokine productions through promoting TRAF6 (TNF receptor-associated factor 6, E3 ubiquitin protein ligase) ubiquitination and thus facilitates migration and invasion of lung cancer cells. Stimulation of TLR4 and TLR3 with lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid [poly(I:C)] respectively triggered autophagy in lung cancer cells. This was mediated by the adaptor protein, toll-like receptor adaptor molecule 1 (TICAM1/TRIF), and was required for TLR4- and TLR3-induced increases in the production of IL6, CCL2/MCP-1 [chemokine (C-C motif) ligand 2], CCL20/MIP-3α [chemokine (C-C motif) ligand 20], VEGFA (vascular endothelial growth factor A), and MMP2 [matrix metallopeptidase 2 (gelatinase A, 72 kDa gelatinase, 72 kDa type IV collagenase)]. These cytokines appeared to be necessary for enhanced migration and invasion of lung cancer cells upon TLR activation. Remarkably, inhibition of autophagy by chemical or genetic approaches blocked TLR4- or TLR3-induced Lys63 (K63)-linked ubiquitination of TRAF6 that was essential for activation of MAPK and NFKB (nuclear factor of kappa light polypeptide gene enhancer in B-cells) pathways, both of which were involved in the increased production of the cytokines. Collectively, these results identify induction of autophagy by TLR4 and TLR3 as an important mechanism that drives lung cancer progression, and indicate that inhibition of autophagy may be a useful strategy in the treatment of lung cancer.

  5. Ubiquitin

    DEFF Research Database (Denmark)

    Vinther-Jensen, T.; Simonsen, A. H.; Budtz-Jorgensen, E.;

    2015-01-01

    , as well as aid in identifying an optimal time point for initiating a potential therapeutic intervention. METHODS: This explorative proteomics study evaluated cerebrospinal fluid from 94 Huntington's disease gene-expansion carriers (39 premanifest and 55 manifest) and 27 Huntington's disease gene......-expansion negative individuals using surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry. Differences in peak intensity from SELDI-TOF spectra were evaluated. RESULTS: Levels of 10 peaks were statistically significantly different between manifest gene-expansion carriers......-expansion carriers. CONCLUSIONS AND RELEVANCE: Multiple studies have shown that the ubiquitin-proteasome system is involved in Huntington's disease pathogenesis and understanding of this involvement may have therapeutic potential in humans. This is the first study on cerebrospinal fluid to confirm the involvement...

  6. E3 Ubiquitin Ligase Nedd4 Promotes Japanese Encephalitis Virus Replication by Suppressing Autophagy in Human Neuroblastoma Cells

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    Xu, Qingqiang; Zhu, Naiwei; Chen, Shenglin; Zhao, Ping; Ren, Hao; Zhu, Shiying; Tang, Hailin; Zhu, Yongzhe; Qi, Zhongtian

    2017-01-01

    Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that causes the most prevalent viral encephalitis in Asia. Since JEV is a neurotropic virus, it is important to identify key molecules that mediate JEV infection in neuronal cells and to investigate their underlying mechanisms. In this study, the critical role of Nedd4, an E3 ubiquitin ligase that is highly expressed in the central nervous system, was examined in JEV propagation. In SK-N-SH neuroblastoma cells, Nedd4 was up-regulated in response to JEV infection. Moreover, down-regulation of Nedd4 resulted in a significant decrease in JEV replication without alterations in virus attachment and internalization or in JEV pseudotyped virus infection, suggesting that Nedd4 participates in the replication but not in the entry stage of JEV infection. Further functional analysis showed that Nedd4 attenuated JEV-induced autophagy, which negatively regulates virus replication during infection. These results suggest that Nedd4 facilitates the replication of JEV by suppressing virus-induced autophagy. Taken together, our results indicate that Nedd4 plays a crucial role in JEV infection of neuronal cells, which provides a potential target for the development of novel treatment to combat JEV infection. PMID:28349961

  7. Regulation of autophagy and the ubiquitin-proteasome system by the FoxO transcriptional network during muscle atrophy.

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    Milan, Giulia; Romanello, Vanina; Pescatore, Francesca; Armani, Andrea; Paik, Ji-Hye; Frasson, Laura; Seydel, Anke; Zhao, Jinghui; Abraham, Reimar; Goldberg, Alfred L; Blaauw, Bert; DePinho, Ronald A; Sandri, Marco

    2015-04-10

    Stresses like low nutrients, systemic inflammation, cancer or infections provoke a catabolic state characterized by enhanced muscle proteolysis and amino acid release to sustain liver gluconeogenesis and tissue protein synthesis. These conditions activate the family of Forkhead Box (Fox) O transcription factors. Here we report that muscle-specific deletion of FoxO members protects from muscle loss as a result of the role of FoxOs in the induction of autophagy-lysosome and ubiquitin-proteasome systems. Notably, in the setting of low nutrient signalling, we demonstrate that FoxOs are required for Akt activity but not for mTOR signalling. FoxOs control several stress-response pathways such as the unfolded protein response, ROS detoxification, DNA repair and translation. Finally, we identify FoxO-dependent ubiquitin ligases including MUSA1 and a previously uncharacterised ligase termed SMART (Specific of Muscle Atrophy and Regulated by Transcription). Our findings underscore the central function of FoxOs in coordinating a variety of stress-response genes during catabolic conditions.

  8. Abnormal Glucose Metabolism in Alzheimer’s Disease: Relation to Autophagy/Mitophagy and Therapeutic Approaches

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    Banerjee, Kalpita; Munshi, Soumyabrata; Frank, David E.; Gibson, Gary E.

    2015-01-01

    Diminished glucose metabolism accompanies many neurodegenerative diseases including Alzheimer’s disease. An understanding of the relation of these metabolic changes to the disease will enable development of novel therapeutic strategies. Following a metabolic challenge, cells generally conserve energy to preserve viability. This requires activation of many cellular repair/regenerative processes such as mitophagy/autophagy and fusion/fission. These responses may diminish cell function in the long term. Prolonged fission induces mitophagy/autophagy which promotes repair but if prolonged progresses to mitochondrial degradation. Abnormal glucose metabolism alters protein signaling including the release of proteins from the mitochondria or migration of proteins from the cytosol to the mitochondria or nucleus. This overview provides an insight into the different mechanisms of autophagy/mitophagy and mitochondrial dynamics in response to the diminished metabolism that occurs with diseases, especially neurodegenerative diseases such as Alzheimer's disease. The review discusses multiple aspects of mitochondrial responses including different signaling proteins and pathways of mitophagy and mitochondrial biogenesis. Improving cellular bioenergetics and mitochondrial dynamics will alter protein signaling and improve cellular/mitochondrial repair and regeneration. An understanding of these changes will suggest new therapeutic strategies. PMID:26077923

  9. Emerging role of autophagy in pediatric neurodegenerative and neurometabolic diseases.

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    Ebrahimi-Fakhari, Darius; Wahlster, Lara; Hoffmann, Georg F; Kölker, Stefan

    2014-01-01

    Pediatric neurodegenerative diseases are a heterogeneous group of diseases that result from specific genetic and biochemical defects. In recent years, studies have revealed a wide spectrum of abnormal cellular functions that include impaired proteolysis, abnormal lipid trafficking, accumulation of lysosomal content, and mitochondrial dysfunction. Within neurons, elaborated degradation pathways such as the ubiquitin-proteasome system and the autophagy-lysosomal pathway are critical for maintaining homeostasis and normal cell function. Recent evidence suggests a pivotal role for autophagy in major adult and pediatric neurodegenerative diseases. We herein review genetic, pathological, and molecular evidence for the emerging link between autophagy dysfunction and lysosomal storage disorders such as Niemann-Pick type C, progressive myoclonic epilepsies such as Lafora disease, and leukodystrophies such as Alexander disease. We also discuss the recent discovery of genetically deranged autophagy in Vici syndrome, a multisystem disorder, and the implications for the role of autophagy in development and disease. Deciphering the exact mechanism by which autophagy contributes to disease pathology may open novel therapeutic avenues to treat neurodegeneration. To this end, an outlook on novel therapeutic approaches targeting autophagy concludes this review.

  10. Abnormal integrity of the nucleolus associated with cell cycle arrest owing to the temperature-sensitive ubiquitin-activating enzyme E1.

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    Sudha, T; Tsuji, H; Sameshima, M; Matsuda, Y; Kaneda, S; Nagai, Y; Yamao, F; Seno, T

    1995-03-01

    A mouse cell mutant, ts85, containing the temperature-sensitive ubiquitin-activating enzyme was arrested in G2 phase at the non-permissive temperature. In the arrested cells, azure C, a nucleolus-specific stain, revealed a U-shaped or ring-shaped arrangement of nucleolar lobes with an unstained region in the center. Silver staining of the nucleolar organizer region (NOR) and fluorescence in situ hybridization (FISH) with rDNA both gave signals in azure C-positive regions. Electron microscopic examination revealed a cloud of unidentified electron-dense particles (diameter approximately 70 nm) in the azure C-negative center space. When the arrested cells were released into M-phase, we observed the association of NOR-bearing chromosomes with a pulverization-like abnormality. FISH with rDNA and NOR silver staining demonstrated that the pulverization-like abnormality was restricted to NORs. The frequent occurrence of persistent nucleolar material in prophase and prometaphase of the stressed cells after release indicated a delayed dissociation of the nucleolus that brought about the abnormal chromosomes in M-phase. ts85 cells transfected with the mouse E1 cDNA recovered growth at the non-permissive temperature and no longer showed abnormal nucleolar morphology. It seems that the ubiquitin system plays a role in the dissolution of the nucleolus, possibly involving the NOR-bearing chromosomes.

  11. Regulation of Mitochondrial Genome Inheritance by Autophagy and Ubiquitin-Proteasome System: Implications for Health, Fitness, and Fertility

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    Won-Hee Song

    2014-01-01

    Full Text Available Mitochondria, the energy-generating organelles, play a role in numerous cellular functions including adenosine triphosphate (ATP production, cellular homeostasis, and apoptosis. Maternal inheritance of mitochondria and mitochondrial DNA (mtDNA is universally observed in humans and most animals. In general, high levels of mitochondrial heteroplasmy might contribute to a detrimental effect on fitness and disease resistance. Therefore, a disposal of the sperm-derived mitochondria inside fertilized oocytes assures normal preimplantation embryo development. Here we summarize the current research and knowledge concerning the role of autophagic pathway and ubiquitin-proteasome-dependent proteolysis in sperm mitophagy in mammals, including humans. Current data indicate that sperm mitophagy inside the fertilized oocyte could occur along multiple degradation routes converging on autophagic clearance of paternal mitochondria. The influence of assisted reproductive therapies (ART such as intracytoplasmic sperm injection (ICSI, mitochondrial replacement (MR, and assisted fertilization of oocytes from patients of advanced reproductive age on mitochondrial function, inheritance, and fitness and for the development and health of ART babies will be of particular interest to clinical audiences. Altogether, the study of sperm mitophagy after fertilization has implications in the timing of evolution and developmental and reproductive biology and in human health, fitness, and management of mitochondrial disease.

  12. Regulation of mitochondrial genome inheritance by autophagy and ubiquitin-proteasome system: implications for health, fitness, and fertility.

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    Song, Won-Hee; Ballard, John William Oman; Yi, Young-Joo; Sutovsky, Peter

    2014-01-01

    Mitochondria, the energy-generating organelles, play a role in numerous cellular functions including adenosine triphosphate (ATP) production, cellular homeostasis, and apoptosis. Maternal inheritance of mitochondria and mitochondrial DNA (mtDNA) is universally observed in humans and most animals. In general, high levels of mitochondrial heteroplasmy might contribute to a detrimental effect on fitness and disease resistance. Therefore, a disposal of the sperm-derived mitochondria inside fertilized oocytes assures normal preimplantation embryo development. Here we summarize the current research and knowledge concerning the role of autophagic pathway and ubiquitin-proteasome-dependent proteolysis in sperm mitophagy in mammals, including humans. Current data indicate that sperm mitophagy inside the fertilized oocyte could occur along multiple degradation routes converging on autophagic clearance of paternal mitochondria. The influence of assisted reproductive therapies (ART) such as intracytoplasmic sperm injection (ICSI), mitochondrial replacement (MR), and assisted fertilization of oocytes from patients of advanced reproductive age on mitochondrial function, inheritance, and fitness and for the development and health of ART babies will be of particular interest to clinical audiences. Altogether, the study of sperm mitophagy after fertilization has implications in the timing of evolution and developmental and reproductive biology and in human health, fitness, and management of mitochondrial disease.

  13. Ubiquitin at the crossroad of cell death and survival

    Institute of Scientific and Technical Information of China (English)

    Yu-Shan Chen; Xiao-Bo Qiu

    2013-01-01

    Ubiquitination is crucial for cellular processes, such as protein degradation, apoptosis, autophagy, and cell cycle progression. Dysregulation of the ubiquitination network accounts for the development of numerous diseases, including cancer. Thus, targeting ubiquitination is a promising strategy in cancer therapy. Both apoptosis and autophagy are involved in tumorigenesis and response to cancer therapy. Although both are categorized as types of celldeath, autophagy is general y considered to have protective functions, including protecting cells from apoptosis under certain cellular stress conditions. This review highlights recent advances in understanding the regulation of apoptosis and autophagy by ubiquitination.

  14. [Progress in ubiquitin, ubiquitin chain and protein ubiquitination].

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    Lan, Qiuyan; Gao, Yuan; Li, Yanchang; Hong, Xuechuan; Xu, Ping

    2016-01-01

    Protein ubiquitination is one of the most important and widely exist protein post-translational modifications in eukaryotic cells, which takes the ubiquitin and ubiquitin chains as signal molecules to covalently modify other protein substrates. It plays an important roles in the control of almost all of the life processes, including gene transcription and translation, signal transduction and cell-cycle progression, besides classical 26S protesome degradation pathway. Varied modification sites in the same substrates as well as different types of ubiquitin linkages in the same modification sites contain different structural information, which conduct different signal or even determine the fate of the protein substrates in the cell. Any abnormalities in ubiquitin chain formation or its modification process may cause severe problem in maintaining the balance of intracellular environment and finally result in serious health problem of human being. In this review, we discussed the discovery, genetic characteristics and the crystal structure of the ubiquitin. We also emphasized the recent progresses of the assembly processes, structure and their biological function of ubiquitin chains. The relationship between the disregulation and related human diseases has also been discussed. These progress will shed light on the complexity of proteome, which may also provide tools in the new drug research and development processes.

  15. Dysfunction of the Ubiquitin Proteasome and Ubiquitin-Like Systems in Schizophrenia

    OpenAIRE

    Rubio, María D; Wood, Krista; Haroutunian, Vahram; Meador-Woodruff, James H

    2013-01-01

    Protein expression abnormalities have been implicated in the pathophysiology of schizophrenia, but the underlying cause of these changes is not known. We sought to investigate ubiquitin and ubiquitin-like (UBL) systems (SUMOylation, NEDD8ylation, and Ufmylation) as putative mechanisms underlying protein expression abnormalities seen in schizophrenia. For this, we performed western blot analysis of total ubiquitination, free ubiquitin, K48- and K63-linked ubiquitination, and E1 activases, E2 c...

  16. Ubiquitin modifications

    OpenAIRE

    Swatek, Kirby N.; Komander, David

    2016-01-01

    Protein ubiquitination is a dynamic multifaceted post-translational modification involved in nearly all aspects of eukaryotic biology. Once attached to a substrate, the 76-amino acid protein ubiquitin is subjected to further modifications, creating a multitude of distinct signals with distinct cellular outcomes, referred to as the 'ubiquitin code'. Ubiquitin can be ubiquitinated on seven lysine (Lys) residues or on the N-terminus, leading to polyubiquitin chains that can encompass complex top...

  17. Contribution of the autophagy-lysosomal and ubiquitin-proteasomal proteolytic systems to total proteolysis in rainbow trout (Oncorhynchus mykiss) myotubes

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    Two major proteolytic systems are thought to (co-) operate in the skeletal muscle of vertebrates, the ubiquitin-proteasomal system (UPS) and the autophagic/lysosomal system (ALS). While their relative contribution to muscle loss has been already well documented in mammals, little is known in fish sp...

  18. Non-canonical NF-κB activation and abnormal B cell accumulation in mice expressing ubiquitin protein ligase-inactive c-IAP2.

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    Dietrich B Conze

    Full Text Available Chromosomal translocations between loci encoding MALT1 and c-IAP2 are common in MALT lymphomas. The resulting fusion proteins lack the c-IAP2 RING domain, the region responsible for its ubiquitin protein ligase (E3 activity. Ectopic expression of the fusion protein activates the canonical NF-κB signaling cascade, but how it does so is controversial and how it promotes MALT lymphoma is unknown. Considering recent reports implicating c-IAP1 and c-IAP2 E3 activity in repression of non-canonical NF-κB signaling, we asked if the c-IAP2/MALT fusion protein can initiate non-canonical NF-κB activation. Here we show that in addition to canonical activation, the fusion protein stabilizes NIK and activates non-canonical NF-κB. Canonical but not non-canonical activation depended on MALT1 paracaspase activity, and expression of E3-inactive c-IAP2 activated non-canonical NF-κB. Mice in which endogenous c-IAP2 was replaced with an E3-inactive mutant accumulated abnormal B cells with elevated non-canonical NF-κB and had increased numbers of B cells with a marginal zone phenotype, gut-associated lymphoid hyperplasia, and other features of MALT lymphoma. Thus, the c-IAP2/MALT1 fusion protein activates NF-κB by two distinct mechanisms, and loss of c-IAP2 E3 activity in vivo is sufficient to induce abnormalities common to MALT lymphoma.

  19. Phosphorylation of the autophagy receptor optineurin restricts Salmonella growth

    DEFF Research Database (Denmark)

    Wild, Philipp; Farhan, Hesso; McEwan, David G;

    2011-01-01

    Selective autophagy can be mediated via receptor molecules that link specific cargoes to the autophagosomal membranes decorated by ubiquitin-like microtubule-associated protein light chain 3 (LC3) modifiers. Although several autophagy receptors have been identified, little is known about mechanisms...... be a general mechanism for regulation of cargo-selective autophagy....

  20. Autophagy in Hepatic Fibrosis

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    Yang Song

    2014-01-01

    Full Text Available Hepatic fibrosis is a leading cause of morbidity and mortality worldwide. Hepatic fibrosis is usually associated with chronic liver diseases caused by infection, drugs, metabolic disorders, or autoimmune imbalances. Effective clinical therapies are still lacking. Autophagy is a cellular process that degrades damaged organelles or protein aggregation, which participates in many pathological processes including liver diseases. Autophagy participates in hepatic fibrosis by activating hepatic stellate cells and may participate as well through influencing other fibrogenic cells. Besides that, autophagy can induce some liver diseases to develop while it may play a protective role in hepatocellular abnormal aggregates related liver diseases and reduces fibrosis. With a better understanding of the potential effects of autophagy on hepatic fibrosis, targeting autophagy might be a novel therapeutic strategy for hepatic fibrosis in the near future.

  1. Abnormal Regulation of Ubiquitin-Proteasome Pathway in Chronic Alcoholism%慢性酒精中毒性疾病与泛素-蛋白酶体途径异常调节的研究

    Institute of Scientific and Technical Information of China (English)

    杨海玉(综述); 刘勇(审校)

    2014-01-01

    Ubiquitin-proteasome pathway is the main way for intracellular protein degradation and plays an important role in a variety of cellular processes.Studies have confirmed that chronic alcoholism leads to abnormal regulation of ubiquitin-proteasome pathway involving alterations of proteasome activity,ubiquitin synthesis and related protein expression.Moreover,the abnormal regulation of ubiquitin-proteasome pathway is correlated with the pathogenesis of chronic alcohol-ic diseases,including alcoholic liver disease,alcoholic encephalopathy and alcoholic myopathy. These findings provide an important research direction for further revealing the molecular mecha-nisms of alcohol-induced tissue inj uries and developing new drugs for the treatment of chronic al-coholic diseases.%泛素-蛋白酶体途径是细胞内蛋白质降解的主要途径,在多种细胞生命过程中发挥重要作用。目前研究证实慢性酒精中毒可导致泛素-蛋白酶体途径异常调节,主要涉及蛋白酶体活性、泛素分子合成以及相关蛋白分子表达改变等,并且与一些慢性酒精中毒性疾病的发生有关,包括酒精中毒性肝病、酒精中毒性脑病和酒精中毒性肌病。这些发现为进一步揭示酒精诱导损伤的分子机制以及研发治疗慢性酒精中毒性疾病的新型药物提供了重要的研究方向。

  2. Autophagy in mammalian cells

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    Kadija; Abounit; Tiziano; M; Scarabelli; Roy; B; McCauley

    2012-01-01

    Autophagy is a regulated process for the degradation of cellular components that has been well conserved in eukaryotic cells. The discovery of autophagy-regulating proteins in yeast has been important in understanding this process. Although many parallels exist between fungi and mammals in the regulation and execution of autophagy, there are some important differences. The preautophagosomal structure found in yeast has not been identified in mammals, and it seems that there may be multiple origins for autophagosomes, including endoplasmic reticulum, plasma membrane and mitochondrial outer membrane. The maturation of the phagophore is largely dependent on 5’-AMP activated protein kinase and other factors that lead to the dephosphorylation of mammalian target of rapamycin. Once the process is initiated, the mammalian phagophore elongates and matures into an autophagosome by processes that are similar to those in yeast. Cargo selection is dependent on the ubiquitin conjugation of protein aggregates and organelles and recognition of these conjugates by autophagosomal receptors. Lysosomal degradation of cargo produces metabolites that can be recycled during stress. Autophagy is an impor-tant cellular safeguard during starvation in all eukaryotes; however, it may have more complicated, tissue specific roles in mammals. With certain exceptions, autophagy seems to be cytoprotective, and defects in the process have been associated with human disease.

  3. Targeting autophagy in neurodegenerative diseases.

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    Vidal, René L; Matus, Soledad; Bargsted, Leslie; Hetz, Claudio

    2014-11-01

    The most prevalent neurodegenerative disorders involve protein misfolding and the aggregation of specific proteins. Autophagy is becoming an attractive target to treat neurodegenerative disorders through the selective degradation of abnormally folded proteins by the lysosomal pathway. However, accumulating evidence indicates that autophagy impairment at different regulatory steps may contribute to the neurodegenerative process. Thus, a complex scenario is emerging where autophagy may play a dual role in neurodegenerative diseases by causing the downstream effect of promoting the degradation of misfolded proteins and an upstream effect where its deregulation perturbs global proteostasis, contributing to disease progression. Challenges in the future development of therapeutic strategies to target the autophagy pathway are discussed.

  4. Development and characterization of a new Parkinson disease model resulting from impaired autophagy

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    Ahmed, Ishrat; Liang, Yideng; Schools, Sabitha; Dawson, Valina L.; Dawson, Ted M.; Savitt, Joseph M

    2012-01-01

    Parkinson’s disease (PD) is a progressive neurodegenerative disease caused by the interaction of genetic and environmental factors. However, the etiology of PD remains largely unknown. Macroautophagy is known to play an essential role in the degradation of abnormal proteins and organelles. Furthermore, the loss of autophagy-related (Atg) genes results in neurodegeneration and abnormal protein accumulation. Since these are also pathologic features of Parkinson disease, the conditional impairment of autophagy may lead to improved animal models for the study of PD. Using transgenic mice expressing Cre recombinase under the control of either the dopamine transporter or the engrailed-1 promoters, we generated mice with the conditional deletion of Atg7 in the dopamine neurons of the substantia nigra pars compacta, other regions of the midbrain, and also the hindbrain. This conditional impairment of autophagy results in the age-related loss of dopaminergic neurons and corresponding loss of striatal dopamine, the accumulation of low molecular weight α-synuclein, and the presence of ubiquitinated protein aggregates, recapitulating many of the pathologic features of PD. These conditional knockout animals provide insight into the process of autophagy in Parkinson disease pathology. PMID:23152632

  5. Types of Ubiquitin Ligases.

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    Morreale, Francesca Ester; Walden, Helen

    2016-03-24

    Ubiquitination is a post-translational modification of proteins involved in a variety of cellular processes. Ubiquitination requires the sequential action of three enzymes: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-conjugating enzymes), and E3 (ubiquitin ligases). This SnapShot highlights the main types of E3 ubiquitin ligases, which can be classified in three families depending on the presence of characteristic domains and on the mechanism of ubiquitin transfer to the substrate protein.

  6. Regulation of autophagy by cytoplasmic p53.

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    Tasdemir, Ezgi; Maiuri, M Chiara; Galluzzi, Lorenzo; Vitale, Ilio; Djavaheri-Mergny, Mojgan; D'Amelio, Marcello; Criollo, Alfredo; Morselli, Eugenia; Zhu, Changlian; Harper, Francis; Nannmark, Ulf; Samara, Chrysanthi; Pinton, Paolo; Vicencio, José Miguel; Carnuccio, Rosa; Moll, Ute M; Madeo, Frank; Paterlini-Brechot, Patrizia; Rizzuto, Rosario; Szabadkai, Gyorgy; Pierron, Gérard; Blomgren, Klas; Tavernarakis, Nektarios; Codogno, Patrice; Cecconi, Francesco; Kroemer, Guido

    2008-06-01

    Multiple cellular stressors, including activation of the tumour suppressor p53, can stimulate autophagy. Here we show that deletion, depletion or inhibition of p53 can induce autophagy in human, mouse and nematode cells subjected to knockout, knockdown or pharmacological inhibition of p53. Enhanced autophagy improved the survival of p53-deficient cancer cells under conditions of hypoxia and nutrient depletion, allowing them to maintain high ATP levels. Inhibition of p53 led to autophagy in enucleated cells, and cytoplasmic, not nuclear, p53 was able to repress the enhanced autophagy of p53(-/-) cells. Many different inducers of autophagy (for example, starvation, rapamycin and toxins affecting the endoplasmic reticulum) stimulated proteasome-mediated degradation of p53 through a pathway relying on the E3 ubiquitin ligase HDM2. Inhibition of p53 degradation prevented the activation of autophagy in several cell lines, in response to several distinct stimuli. These results provide evidence of a key signalling pathway that links autophagy to the cancer-associated dysregulation of p53.

  7. Inducing autophagy

    DEFF Research Database (Denmark)

    Harder, Lea M; Bunkenborg, Jakob; Andersen, Jens S.

    2014-01-01

    catabolism, which has recently been found to induce autophagy in an MTOR independent way and support cancer cell survival. In this study, quantitative phosphoproteomics was applied to investigate the initial signaling events linking ammonia to the induction of autophagy. The MTOR inhibitor rapamycin was used...

  8. Autophagy impairment in a mouse model of neuropathic pain

    Directory of Open Access Journals (Sweden)

    Berliocchi Laura

    2011-10-01

    Full Text Available Abstract Autophagy is an intracellular membrane trafficking pathway controlling the delivery of cytoplasmic material to the lysosomes for degradation. It plays an important role in cell homeostasis in both normal settings and abnormal, stressful conditions. It is now recognised that an imbalance in the autophagic process can impact basal cell functions and this has recently been implicated in several human diseases, including neurodegeneration and cancer. Here, we investigated the consequences of nerve injury on the autophagic process in a commonly used model of neuropathic pain. The expression and modulation of the main autophagic marker, the microtubule-associated protein 1 light chain 3 (LC3, was evaluated in the L4-L5 cord segment seven days after spinal nerve ligation (SNL. Levels of LC3-II, the autophagosome-associated LC3 form, were markedly higher in the spinal cord ipsilateral to the ligation side, appeared to correlate with the upregulation of the calcium channel subunit α2δ-1 and were not present in mice that underwent sham surgery. However, LC3-I and Beclin 1 expression were only slightly increased. On the contrary, SNL promoted the accumulation of the ubiquitin- and LC3-binding protein p62, which inversely correlates with autophagic activity, thus pointing to a block of autophagosome turnover. Our data showed for the first time that basal autophagy is disrupted in a model of neuropathic pain.

  9. Autophagy contributes to regulation of nuclear dynamics during vegetative growth and hyphal fusion in Fusarium oxysporum.

    Science.gov (United States)

    Corral-Ramos, Cristina; Roca, M Gabriela; Di Pietro, Antonio; Roncero, M Isabel G; Ruiz-Roldán, Carmen

    2015-01-01

    In the fungal pathogen Fusarium oxysporum, vegetative hyphal fusion triggers nuclear mitotic division in the invading hypha followed by migration of a nucleus into the receptor hypha and degradation of the resident nucleus. Here we examined the role of autophagy in fusion-induced nuclear degradation. A search of the F. oxysporum genome database for autophagy pathway components identified putative orthologs of 16 core autophagy-related (ATG) genes in yeast, including the ubiquitin-like protein Atg8, which is required for the formation of autophagosomal membranes. F. oxysporum Foatg8Δ mutants were generated in a strain harboring H1-cherry fluorescent protein (ChFP)-labeled nuclei to facilitate analysis of nuclear dynamics. The Foatg8Δ mutants did not show MDC-positive staining in contrast to the wild type and the FoATG8-complemented (cFoATG8) strain, suggesting that FoAtg8 is required for autophagy in F. oxysporum. The Foatg8Δ strains displayed reduced rates of hyphal growth, conidiation, and fusion, and were significantly attenuated in virulence on tomato plants and in the nonvertebrate animal host Galleria mellonella. In contrast to wild-type hyphae, which are almost exclusively composed of uninucleated hyphal compartments, the hyphae of the Foatg8Δ mutants contained a significant fraction of hyphal compartments with 2 or more nuclei. The increase in the number of nuclei per hyphal compartment was particularly evident after hyphal fusion events. Time-lapse microscopy analyses revealed abnormal mitotic patterns during vegetative growth in the Foatg8Δ mutants. Our results suggest that autophagy mediates nuclear degradation after hyphal fusion and has a general function in the control of nuclear distribution in F. oxysporum.

  10. Autophagy selectivity through receptor clustering

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    Rutenberg, Andrew; Brown, Aidan

    Substrate selectivity in autophagy requires an all-or-none cellular response. We focus on peroxisomes, for which autophagy receptor proteins NBR1 and p62 are well characterized. Using computational models, we explore the hypothesis that physical clustering of autophagy receptor proteins on the peroxisome surface provides an appropriate all-or-none response. We find that larger peroxisomes nucleate NBR1 clusters first, and lose them due to competitive coarsening last, resulting in significant size-selectivity. We then consider a secondary hypothesis that p62 inhibits NBR1 cluster formation. We find that p62 inhibition enhances size-selectivity enough that, even if there is no change of the pexophagy rate, the volume of remaining peroxisomes can significantly decrease. We find that enhanced ubiquitin levels suppress size-selectivity, and that this effect is more pronounced for individual peroxisomes. Sufficient ubiquitin allows receptor clusters to form on even the smallest peroxisomes. We conclude that NBR1 cluster formation provides a viable physical mechanism for all-or-none substrate selectivity in pexophagy. We predict that cluster formation is associated with significant size-selectivity. Now at Simon Fraser University.

  11. Coordination of autophagy with other cellular activities

    Institute of Scientific and Technical Information of China (English)

    Yan WANG; Zheng-hong QIN

    2013-01-01

    The cell biological phenomenon of autophagy has attracted increasing attention in recent years,partly as a consequence of the discovery of key components of its cellular machinery.Autophagy plays a crucial role in a myriad of cellular functions.Autophagy has its own regulatory mechanisms,but this process is not isolated.Autophagy is coordinated with other cellular activities to maintain cell homeostasis.Autophagy is critical for a range of human physiological processes.The multifunctional roles of autophagy are explained by its ability to interact with several key components of various cell pathways.In this review,we focus on the coordination between autophagy and other physiological processes,including the ubiquitin-proteasome system (UPS),energy homeostasis,aging,programmed cell death,the immune responses,microbial invasion and inflammation.The insights gained from investigating autophagic networks should increase our understanding of their roles in human diseases and their potential as targets for therapeutic intervention.

  12. Dysregulation of the Autophagy-Endolysosomal System in Amyotrophic Lateral Sclerosis and Related Motor Neuron Diseases

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    Asako Otomo

    2012-01-01

    Full Text Available Amyotrophic lateral sclerosis (ALS is a heterogeneous group of incurable motor neuron diseases (MNDs characterized by a selective loss of upper and lower motor neurons in the brain and spinal cord. Most cases of ALS are sporadic, while approximately 5–10% cases are familial. More than 16 causative genes for ALS/MNDs have been identified and their underlying pathogenesis, including oxidative stress, endoplasmic reticulum stress, excitotoxicity, mitochondrial dysfunction, neural inflammation, protein misfolding and accumulation, dysfunctional intracellular trafficking, abnormal RNA processing, and noncell-autonomous damage, has begun to emerge. It is currently believed that a complex interplay of multiple toxicity pathways is implicated in disease onset and progression. Among such mechanisms, ones that are associated with disturbances of protein homeostasis, the ubiquitin-proteasome system and autophagy, have recently been highlighted. Although it remains to be determined whether disease-associated protein aggregates have a toxic or protective role in the pathogenesis, the formation of them results from the imbalance between generation and degradation of misfolded proteins within neuronal cells. In this paper, we focus on the autophagy-lysosomal and endocytic degradation systems and implication of their dysfunction to the pathogenesis of ALS/MNDs. The autophagy-endolysosomal pathway could be a major target for the development of therapeutic agents for ALS/MNDs.

  13. Autophagy in DNA Damage Response

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    Piotr Czarny

    2015-01-01

    Full Text Available DNA damage response (DDR involves DNA repair, cell cycle regulation and apoptosis, but autophagy is also suggested to play a role in DDR. Autophagy can be activated in response to DNA-damaging agents, but the exact mechanism underlying this activation is not fully understood, although it is suggested that it involves the inhibition of mammalian target of rapamycin complex 1 (mTORC1. mTORC1 represses autophagy via phosphorylation of the ULK1/2–Atg13–FIP200 complex thus preventing maturation of pre-autophagosomal structures. When DNA damage occurs, it is recognized by some proteins or their complexes, such as poly(ADPribose polymerase 1 (PARP-1, Mre11–Rad50–Nbs1 (MRN complex or FOXO3, which activate repressors of mTORC1. SQSTM1/p62 is one of the proteins whose levels are regulated via autophagic degradation. Inhibition of autophagy by knockout of FIP200 results in upregulation of SQSTM1/p62, enhanced DNA damage and less efficient damage repair. Mitophagy, one form of autophagy involved in the selective degradation of mitochondria, may also play role in DDR. It degrades abnormal mitochondria and can either repress or activate apoptosis, but the exact mechanism remains unknown. There is a need to clarify the role of autophagy in DDR, as this process may possess several important biomedical applications, involving also cancer therapy.

  14. High throughput screening for drug discovery of autophagy modulators.

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    Shu, Chih-Wen; Liu, Pei-Feng; Huang, Chun-Ming

    2012-11-01

    Autophagy is an evolutionally conserved process in cells for cleaning abnormal proteins and organelles in a lysosome dependent manner. Growing studies have shown that defects or induced autophagy contributes to many diseases including aging, neurodegeneration, pathogen infection, and cancer. However, the precise involvement of autophagy in health and disease remains controversial because the theories are built on limited assays and chemical modulators, indicating that the role of autophagy in diseases may require further verification. Many food and drug administration (FDA) approved drugs modulate autophagy signaling, suggesting that modulation of autophagy with pharmacological agonists or antagonists provides a potential therapy for autophagy-related diseases. This suggestion raises an attractive issue on drug discovery for exploring chemical modulators of autophagy. High throughput screening (HTS) is becoming a powerful tool for drug discovery that may accelerate screening specific autophagy modulators to clarify the role of autophagy in diseases. Herein, this review lays out current autophagy assays to specifically measure autophagy components such as LC3 (mammalian homologue of yeast Atg8) and Atg4. These assays are feasible or successful for HTS with certain chemical libraries, which might be informative for this intensively growing field as research tools and hopefully developing new drugs for autophagy-related diseases.

  15. Autophagy and its neuroprotection in neurodegenerative diseases

    Institute of Scientific and Technical Information of China (English)

    Ping Gu; Avaneesh Jakkoju; Mingwei Wang; Weidong Le

    2011-01-01

    It has been suggested that protein misfolding and aggregation contribute significantly to the development of neurodegenerative diseases. Misfolded and aggregated proteins are cleared by ubiquitin proteasomal system (UPS) and by both Micro and Macro autophagy lysosomal pathway (ALP). Autophagosomal dysfunction has been implicated in an increasing number of diseases including neurodegenerative diseases. Autophagy is a cellular self-eating process that plays an important role in neuroprotection as well as neuronal injury and death. While a decrease in autophagic activity interferes with protein degradation and possibly organelle turnover, increased autophagy has been shown to facilitate the clearance of aggregation-prone proteins and promote neuronal survival in a number of disease models. On the other hand, too much autophagic activity can be detrimental, suggesting the regulation of autophagy is critical in dictating cell fate. In this review paper, we will discuss various aspects of ALP biology and its dual functions in neuronal cell death and survival. We will also evaluate the role of autophagy in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis. Finally, we will explore the therapeutic potential of autophagy modifiers in several neurodegenerative diseases.

  16. Analysis of autophagy genes in microalgae: Chlorella as a potential model to study mechanism of autophagy.

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    Qiao Jiang

    Full Text Available BACKGROUND: Microalgae, with the ability to mitigate CO(2 emission and produce carbohydrates and lipids, are considered one of the most promising resources for producing bioenergy. Recently, we discovered that autophagy plays a critical role in the metabolism of photosynthetic system and lipids production. So far, more than 30-autophagy related (ATG genes in all subtypes of autophagy have been identified. However, compared with yeast and mammals, in silico and experimental research of autophagy pathways in microalgae remained limited and fragmentary. PRINCIPAL FINDINGS: In this article, we performed a genome-wide analysis of ATG genes in 7 microalgae species and explored their distributions, domain structures and evolution. Eighteen "core autophagy machinery" proteins, four mammalian-specific ATG proteins and more than 30 additional proteins (including "receptor-adaptor" complexes in all subtypes of autophagy were analyzed. Data revealed that receptor proteins in cytoplasm-to-vacuole targeting and mitophagy seem to be absent in microalgae. However, most of the "core autophagy machinery" and mammalian-specific proteins are conserved among microalgae, except for the ATG9-cycling system in Chlamydomonas reinhardtii and the second ubiquitin-like protein conjugation complex in several algal species. The catalytic and binding residues in ATG3, ATG5, ATG7, ATG8, ATG10 and ATG12 are also conserved and the phylogenetic tree of ATG8 coincides well with the phylogenies. Chlorella contains the entire set of the core autophagy machinery. In addition, RT-PCR analysis verified that all crucial ATG genes tested are expressed during autophagy in both Chlorella and Chlamydomonas reinhardtii. Finally, we discovered that addition of 3-Methyladenine (a PI3K specific inhibitor could suppress the formation of autophagic vacuoles in Chlorella. CONCLUSIONS: Taken together, Chlorella may represent a potential model organism to investigate autophagy pathways in

  17. Autophagy is essential for cardiac morphogenesis during vertebrate development.

    Science.gov (United States)

    Lee, Eunmyong; Koo, Yeon; Ng, Aylwin; Wei, Yongjie; Luby-Phelps, Kate; Juraszek, Amy; Xavier, Ramnik J; Cleaver, Ondine; Levine, Beth; Amatruda, James F

    2014-04-01

    Genetic analyses indicate that autophagy, an evolutionarily conserved lysosomal degradation pathway, is essential for eukaryotic differentiation and development. However, little is known about whether autophagy contributes to morphogenesis during embryogenesis. To address this question, we examined the role of autophagy in the early development of zebrafish, a model organism for studying vertebrate tissue and organ morphogenesis. Using zebrafish that transgenically express the fluorescent autophagy reporter protein, GFP-LC3, we found that autophagy is active in multiple tissues, including the heart, during the embryonic period. Inhibition of autophagy by morpholino knockdown of essential autophagy genes (including atg5, atg7, and becn1) resulted in defects in morphogenesis, increased numbers of dead cells, abnormal heart structure, and reduced organismal survival. Further analyses of cardiac development in autophagy-deficient zebrafish revealed defects in cardiac looping, abnormal chamber morphology, aberrant valve development, and ectopic expression of critical transcription factors including foxn4, tbx5, and tbx2. Consistent with these results, Atg5-deficient mice displayed abnormal Tbx2 expression and defects in valve development and chamber septation. Thus, autophagy plays an essential, conserved role in cardiac morphogenesis during vertebrate development.

  18. Species-specific impact of the autophagy machinery on Chikungunya virus infection.

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    Judith, Delphine; Mostowy, Serge; Bourai, Mehdi; Gangneux, Nicolas; Lelek, Mickaël; Lucas-Hourani, Marianne; Cayet, Nadège; Jacob, Yves; Prévost, Marie-Christine; Pierre, Philippe; Tangy, Frédéric; Zimmer, Christophe; Vidalain, Pierre-Olivier; Couderc, Thérèse; Lecuit, Marc

    2013-06-01

    Chikungunya virus (CHIKV) is a recently re-emerged arbovirus that triggers autophagy. Here, we show that CHIKV interacts with components of the autophagy machinery during its replication cycle, inducing a cytoprotective effect. The autophagy receptor p62 protects cells from death by binding ubiquitinated capsid and targeting it to autophagolysosomes. By contrast, the human autophagy receptor NDP52--but not its mouse orthologue--interacts with the non-structural protein nsP2, thereby promoting viral replication. These results highlight the distinct roles of p62 and NDP52 in viral infection, and identify NDP52 as a cellular factor that accounts for CHIKV species specificity.

  19. P62/Ubiquitin IHC expression in gastrointestinal carcinomas

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    Amr eMohamed

    2015-03-01

    Full Text Available P62 and ubiquitin are small regulatory proteins demonstrated to have implications in the prognosis and survival of various malignancies including: hepatocellular, breast, ovarian, and some gastrointestinal carcinomas. Several trials studied the link of their activity to the extrinsic apoptosis pathway and showed that their autophagy modification has a critical stand point in tumorigenesis. These findings explain their vital role in controlling the process of cell death and survival. It has been shown recently that p62 and ubiquitin overexpression in different types of cancers, such as triple negative breast and ovarian cancers, have directly correlated with incidence of distant metastases. We aim to evaluate p62/ubiquitin expression in gastrointestinal carcinomas of gastric, colonic and pancreatic origin. In gastric carcinoma (45, positive p62 nuclear expression was noted in 53% and cytoplasmic in 57%, while positive ubiquitin was nuclear expressed in 80%, and cytoplasmic in 24%. In colon carcinoma (70, positive p62 nuclear expression was noted in 41% and cytoplasmic in 68.5%, while positive ubiquitin was nuclear in 57% and cytoplasmic in 42%. In pancreatic cancer, positive p62 nuclear expression was noted in 86% and cytoplasmic in 60%, while positive ubiquitin was nuclear in 100% and cytoplasmic in 80%. Normal gastric (6, colon (4 and pancreatic (4 tissues were negative for both P62 and ubiquitin (nuclear and cytoplasmic staining <20%. The results suggest that p62 and ubiquitin are highly expressed in nuclei and cytoplasm of gastric, colonic and pancreatic carcinomas. More studies are needed to correlate IHC expression of p62/ubiquitin with clinicopathologic parameters and overall survival in GI carcinomas.

  20. Autophagy modulation as a target for anticancer drug discovery

    Institute of Scientific and Technical Information of China (English)

    Xin LI; Huai-long XU; Yong-xi LIU; Na AN; Si ZHAO; Jin-ku BAO

    2013-01-01

    Autophagy,an evolutionarily conserved catabolic process involving the engulfment and degradation of non-essential or abnormal cellular organelles and proteins,is crucial for homeostatic maintenance in living cells.This highly regulated,multi-step process has been implicated in diverse diseases including cancer.Autophagy can function as either a promoter or a suppressor of cancer,which makes it a promising and challenging therapeutic target.Herein,we overview the regulatory mechanisms and dual roles of autophagy in cancer.We also describe some of the representative agents that exert their anticancer effects by regulating autophagy.Additionally,some emerging strategies aimed at modulating autophagy are discussed as having the potential for future anticancer drug discovery.In summary,these findings will provide valuable information to better utilize autophagy in the future development of anticancer therapeutics that meet clinical requirements.

  1. Ubiquitination in apoptosis signaling

    NARCIS (Netherlands)

    van de Kooij, L.W.

    2014-01-01

    The work described in this thesis focuses on ubiquitination and protein degradation, with an emphasis on how these processes regulate apoptosis signaling. More specifically, our aims were: 1. To increase the understanding of ubiquitin-mediated regulation of apoptosis signaling. 2. To identify the E3

  2. Serine 403 phosphorylation of p62/SQSTM1 regulates selective autophagic clearance of ubiquitinated proteins.

    Science.gov (United States)

    Matsumoto, Gen; Wada, Koji; Okuno, Misako; Kurosawa, Masaru; Nukina, Nobuyuki

    2011-10-21

    Selective macroautophagy (autophagy) of ubiquitinated protein is implicated as a compensatory mechanism of the ubiquitin-proteasome system. p62/SQSTM1 is a key molecule managing autophagic clearance of polyubiquitinated proteins. However, little is known about mechanisms controlling autophagic degradation of polyubiquitinated proteins. Here, we show that the specific phosphorylation of p62 at serine 403 (S403) in its ubiquitin-associated (UBA) domain increases the affinity between UBA and polyubiquitin chain, resulting in efficiently targeting polyubiquitinated proteins in "sequestosomes" and stabilizing sequestosome structure as a cargo of ubiquitinated proteins for autophagosome entry. Casein kinase 2 (CK2) phosphorylates S403 of p62 directly. Furthermore, CK2 overexpression or phosphatase inhibition reduces the formation of inclusion bodies of the polyglutamine-expanded huntingtin exon1 fragment in a p62-dependent manner. We propose that phosphorylation of p62 at S403 regulates autophagic clearance of ubiquitinated proteins and protein aggregates that are poorly degraded by proteasomes.

  3. Autophagy, Metabolism, and Cancer.

    Science.gov (United States)

    White, Eileen; Mehnert, Janice M; Chan, Chang S

    2015-11-15

    Macroautophagy (autophagy hereafter) captures intracellular proteins and organelles and degrades them in lysosomes. The degradation breakdown products are released from lysosomes and recycled into metabolic and biosynthetic pathways. Basal autophagy provides protein and organelle quality control by eliminating damaged cellular components. Starvation-induced autophagy recycles intracellular components into metabolic pathways to sustain mitochondrial metabolic function and energy homeostasis. Recycling by autophagy is essential for yeast and mammals to survive starvation through intracellular nutrient scavenging. Autophagy suppresses degenerative diseases and has a context-dependent role in cancer. In some models, cancer initiation is suppressed by autophagy. By preventing the toxic accumulation of damaged protein and organelles, particularly mitochondria, autophagy limits oxidative stress, chronic tissue damage, and oncogenic signaling, which suppresses cancer initiation. This suggests a role for autophagy stimulation in cancer prevention, although the role of autophagy in the suppression of human cancer is unclear. In contrast, some cancers induce autophagy and are dependent on autophagy for survival. Much in the way that autophagy promotes survival in starvation, cancers can use autophagy-mediated recycling to maintain mitochondrial function and energy homeostasis to meet the elevated metabolic demand of growth and proliferation. Thus, autophagy inhibition may be beneficial for cancer therapy. Moreover, tumors are more autophagy-dependent than normal tissues, suggesting that there is a therapeutic window. Despite these insights, many important unanswered questions remain about the exact mechanisms of autophagy-mediated cancer suppression and promotion, how relevant these observations are to humans, and whether the autophagy pathway can be modulated therapeutically in cancer. See all articles in this CCR Focus section, "Cell Death and Cancer Therapy."

  4. The Selective Autophagy Receptor p62 Forms a Flexible Filamentous Helical Scaffold

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    Rodolfo Ciuffa

    2015-05-01

    Full Text Available The scaffold protein p62/SQSTM1 is involved in protein turnover and signaling and is commonly found in dense protein bodies in eukaryotic cells. In autophagy, p62 acts as a selective autophagy receptor that recognizes and shuttles ubiquitinated proteins to the autophagosome for degradation. The structural organization of p62 in cellular bodies and the interplay of these assemblies with ubiquitin and the autophagic marker LC3 remain to be elucidated. Here, we present a cryo-EM structural analysis of p62. Together with structures of assemblies from the PB1 domain, we show that p62 is organized in flexible polymers with the PB1 domain constituting a helical scaffold. Filamentous p62 is capable of binding LC3 and addition of long ubiquitin chains induces disassembly and shortening of filaments. These studies explain how p62 assemblies provide a large molecular scaffold for the nascent autophagosome and reveal how they can bind ubiquitinated cargo.

  5. A dual role of p53 in the control of autophagy.

    Science.gov (United States)

    Tasdemir, Ezgi; Chiara Maiuri, M; Morselli, Eugenia; Criollo, Alfredo; D'Amelio, Marcello; Djavaheri-Mergny, Mojgan; Cecconi, Francesco; Tavernarakis, Nektarios; Kroemer, Guido

    2008-08-01

    Genotoxic stress can induce autophagy in a p53-dependent fashion and p53 can transactivate autophagy-inducing genes. We have observed recently that inactivation of p53 by deletion, depletion or inhibition can trigger autophagy. Thus, human and mouse cells subjected to knockout, knockdown or pharmacological inhibition of p53 manifest signs of autophagy such as depletion of p62/SQSTM1, LC3 lipidation, redistribution of GFP-LC3 in cytoplasmic puncta, and accumulation of autophagosomes and autolysosomes, both in vitro and in vivo. Inhibition of p53 causes autophagy in enucleated cells, indicating that the cytoplasmic, non-nuclear pool of p53 can regulate autophagy. Accordingly, retransfection of p53(-/-) cells with wild-type p53 as well as a p53 mutant that is excluded from the nucleus (due to the deletion of the nuclear localization sequence) can inhibit autophagy, whereas retransfection with a nucleus-restricted p53 mutant (in which the nuclear localization sequence has been deleted) does not inhibit autophagy. Several distinct autophagy inducers (e.g., starvation, rapamycin, lithium, tunicamycin and thapsigargin) stimulate the rapid degradation of p53. In these conditions, inhibition of the p53-specific E3 ubiquitin ligase HDM2 can avoid p53 depletion and simultaneously prevent the activation of autophagy. Moreover, a p53 mutant that lacks the HDM2 ubiquitinylation site and hence is more stable than wild-type p53 is particularly efficient in suppressing autophagy. In conclusion, p53 plays a dual role in the control of autophagy. On the one hand, nuclear p53 can induce autophagy through transcriptional effects. On the other hand, cytoplasmic p53 may act as a master repressor of autophagy.

  6. Autophagy in Tuberculosis

    Science.gov (United States)

    Deretic, Vojo

    2014-01-01

    Autophagy as an immune mechanism controls inflammation and acts as a cell-autonomous defense against intracellular microbes including Mycobacterium tuberculosis. An equally significant role of autophagy is its anti-inflammatory and tissue-sparing function. This combination of antimicrobial and anti-inflammatory actions prevents active disease in animal models. In human populations, genetic links between autophagy, inflammatory bowel disease, and susceptibility to tuberculosis provide further support to these combined roles of autophagy. The autophagic control of M. tuberculosis and prevention of progressive disease provide novel insights into physiological and immune control of tuberculosis. It also offers host-based therapeutic opportunities because autophagy can be pharmacologically modulated. PMID:25167980

  7. Autophagy in Inflammatory Diseases

    Directory of Open Access Journals (Sweden)

    Alexander J. S. Choi

    2011-01-01

    Full Text Available Autophagy provides a mechanism for the turnover of cellular organelles and proteins through a lysosome-dependent degradation pathway. During starvation, autophagy exerts a homeostatic function that promotes cell survival by recycling metabolic precursors. Additionally, autophagy can interact with other vital processes such as programmed cell death, inflammation, and adaptive immune mechanisms, and thereby potentially influence disease pathogenesis. Macrophages deficient in autophagic proteins display enhanced caspase-1-dependent proinflammatory cytokine production and the activation of the inflammasome. Autophagy provides a functional role in infectious diseases and sepsis by promoting intracellular bacterial clearance. Mutations in autophagy-related genes, leading to loss of autophagic function, have been implicated in the pathogenesis of Crohn's disease. Furthermore, autophagy-dependent mechanisms have been proposed in the pathogenesis of several pulmonary diseases that involve inflammation, including cystic fibrosis and pulmonary hypertension. Strategies aimed at modulating autophagy may lead to therapeutic interventions for diseases associated with inflammation.

  8. Distinct temporal requirements for autophagy and the proteasome in yeast meiosis.

    Science.gov (United States)

    Wen, Fu-ping; Guo, Yue-shuai; Hu, Yang; Liu, Wei-xiao; Wang, Qian; Wang, Yuan-ting; Yu, Hai-Yan; Tang, Chao-ming; Yang, Jun; Zhou, Tao; Xie, Zhi-ping; Sha, Jia-hao; Guo, Xuejiang; Li, Wei

    2016-01-01

    Meiosis is a special type of cellular renovation that involves 2 successive cell divisions and a single round of DNA replication. Two major degradation systems, the autophagy-lysosome and the ubiquitin-proteasome, are involved in meiosis, but their roles have yet to be elucidated. Here we show that autophagy mainly affects the initiation of meiosis but not the nuclear division. Autophagy works not only by serving as a dynamic recycling system but also by eliminating some negative meiotic regulators such as Ego4 (Ynr034w-a). In a quantitative proteomics study, the proteasome was found to be significantly upregulated during meiotic divisions. We found that proteasomal activity is essential to the 2 successive meiotic nuclear divisions but not for the initiation of meiosis. Our study defines the roles of autophagy and the proteasome in meiosis: Autophagy mainly affects the initiation of meiosis, whereas the proteasome mainly affects the 2 successive meiotic divisions.

  9. Reciprocal regulation of cilia and autophagy via the MTOR and proteasome pathways.

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    Wang, Shixuan; Livingston, Man J; Su, Yunchao; Dong, Zheng

    2015-04-01

    Primary cilium is an organelle that plays significant roles in a number of cellular functions ranging from cell mechanosensation, proliferation, and differentiation to apoptosis. Autophagy is an evolutionarily conserved cellular function in biology and indispensable for cellular homeostasis. Both cilia and autophagy have been linked to different types of genetic and acquired human diseases. Their interaction has been suggested very recently, but the underlying mechanisms are still not fully understood. We examined autophagy in cells with suppressed cilia and measured cilium length in autophagy-activated or -suppressed cells. It was found that autophagy was repressed in cells with short cilia. Further investigation showed that MTOR activation was enhanced in cilia-suppressed cells and the MTOR inhibitor rapamycin could largely reverse autophagy suppression. In human kidney proximal tubular cells (HK2), autophagy induction was associated with cilium elongation. Conversely, autophagy inhibition by 3-methyladenine (3-MA) and chloroquine (CQ) as well as bafilomycin A1 (Baf) led to short cilia. Cilia were also shorter in cultured atg5-knockout (KO) cells and in atg7-KO kidney proximal tubular cells in mice. MG132, an inhibitor of the proteasome, could significantly restore cilium length in atg5-KO cells, being concomitant with the proteasome activity. Together, the results suggest that cilia and autophagy regulate reciprocally through the MTOR signaling pathway and ubiquitin-proteasome system.

  10. The ubiquitin proteasomal system: a potential target for the management of Alzheimer's disease.

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    Gadhave, Kundlik; Bolshette, Nityanand; Ahire, Ashutosh; Pardeshi, Rohit; Thakur, Krishan; Trandafir, Cristiana; Istrate, Alexandru; Ahmed, Sahabuddin; Lahkar, Mangala; Muresanu, Dafin F; Balea, Maria

    2016-07-01

    The cellular quality control system degrades abnormal or misfolded proteins and consists of three different mechanisms: the ubiquitin proteasomal system (UPS), autophagy and molecular chaperones. Any disturbance in this system causes proteins to accumulate, resulting in neurodegenerative diseases such as amyotrophic lateral sclerosis, Alzheimer's disease (AD), Parkinson's disease, Huntington's disease and prion or polyglutamine diseases. Alzheimer's disease is currently one of the most common age-related neurodegenerative diseases. However, its exact cause and pathogenesis are unknown. Currently approved medications for AD provide symptomatic relief; however, they fail to influence disease progression. Moreover, the components of the cellular quality control system represent an important focus for the development of targeted and potent therapies for managing AD. This review aims to evaluate whether existing evidence supports the hypothesis that UPS impairment causes the early pathogenesis of neurodegenerative disorders. The first part presents basic information about the UPS and its molecular components. The next part explains how the UPS is involved in neurodegenerative disorders. Finally, we emphasize how the UPS influences the management of AD. This review may help in the design of future UPS-related therapies for AD.

  11. ATG8 Expansion: A Driver of Selective Autophagy Diversification?

    Science.gov (United States)

    Kellner, Ronny; De la Concepcion, Juan Carlos; Maqbool, Abbas; Kamoun, Sophien; Dagdas, Yasin F

    2017-03-01

    Selective autophagy is a conserved homeostatic pathway that involves engulfment of specific cargo molecules into specialized organelles called autophagosomes. The ubiquitin-like protein ATG8 is a central player of the autophagy network that decorates autophagosomes and binds to numerous cargo receptors. Although highly conserved across eukaryotes, ATG8 diversified from a single protein in algae to multiple isoforms in higher plants. We present a phylogenetic overview of 376 ATG8 proteins across the green plant lineage that revealed family-specific ATG8 clades. Because these clades differ in fixed amino acid polymorphisms, they provide a mechanistic framework to test whether distinct ATG8 clades are functionally specialized. We propose that ATG8 expansion may have contributed to the diversification of selective autophagy pathways in plants.

  12. Role of alpha-synuclein in autophagy modulation of primary human T lymphocytes.

    Science.gov (United States)

    Colasanti, T; Vomero, M; Alessandri, C; Barbati, C; Maselli, A; Camperio, C; Conti, F; Tinari, A; Carlo-Stella, C; Tuosto, L; Benincasa, D; Valesini, G; Malorni, W; Pierdominici, M; Ortona, E

    2014-05-29

    It has been demonstrated that α-synuclein can aggregate and contribute to the pathogenesis of some neurodegenerative diseases and it is capable of hindering autophagy in neuronal cells. Here, we investigated the implication of α-synuclein in the autophagy process in primary human T lymphocytes. We provide evidence that: (i) knocking down of the α-synuclein gene resulted in increased autophagy, (ii) autophagy induction by energy deprivation was associated with a significant decrease of α-synuclein levels, (iii) autophagy inhibition by 3-methyladenine or by ATG5 knocking down led to a significant increase of α-synuclein levels, and (iv) autophagy impairment, constitutive in T lymphocytes from patients with systemic lupus erythematosus, was associated with abnormal accumulation of α-synuclein aggregates. These results suggest that α-synuclein could be considered as an autophagy-related marker of peripheral blood lymphocytes, potentially suitable for use in the clinical practice.

  13. Interplay between Leucine-Rich Repeat Kinase 2 (LRRK2) and p62/SQSTM-1 in Selective Autophagy

    Science.gov (United States)

    Park, Sangwook; Han, Seulki; Choi, Insup; Kim, Beomsue; Park, Seung Pyo; Joe, Eun-Hye; Suh, Young Ho

    2016-01-01

    The deposit of polyubiquitinated aggregates has been implicated in the pathophysiology of Parkinson’s disease (PD), and growing evidence indicates that selective autophagy plays a critical role in the clearance of ubiquitin-positive protein aggregates by autophagosomes. The selective autophagic receptor p62/SQSTM-1, which associates directly with both ubiquitin and LC3, transports ubiquitin conjugates to autophagosomes for degradation. Leucine-rich repeat kinase 2 (LRRK2), a PD-associated protein kinase, is tightly controlled by autophagy-lysosome degradation as well as by the ubiquitin-proteasome pathway. However, little is known about the degradation of ubiquitinated LRRK2 via selective autophagy. In the present study, we found that p62/SQSTM-1 physically interacts with LRRK2 as a selective autophagic receptor. The overexpression of p62 leads to the robust degradation of LRRK2 through the autophagy-lysosome pathway. In addition, LRRK2 indirectly regulates Ser351 and Ser403 phosphorylation of p62. Of particular interest, the interaction between phosphorylated p62 and Keap1 is reduced by LRRK2 overexpression. Therefore, we propose that the interplay between LRRK2 and p62 may contribute to the pathophysiological function and homeostasis of LRRK2 protein. PMID:27631370

  14. The inhibition of lung cancer cell migration by AhR-regulated autophagy

    Science.gov (United States)

    Tsai, Chi-Hao; Li, Ching-Hao; Cheng, Yu-Wen; Lee, Chen-Chen; Liao, Po-Lin; Lin, Cheng-Hui; Huang, Shih-Hsuan; Kang, Jaw-Jou

    2017-01-01

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is highly expressed in multiple organs and tissues. Whereas AhR mediates the metabolism of xenobiotic and endogenous compounds, its novel function in cancer epithelial-mesenchymal transition (EMT) remains controversial. Autophagy also participates in tumour progression through its functions in cell homeostasis and facilitates adaptation to EMT progression. In the present study, we found that AhR-regulated autophagy positively modulates EMT in non-small cell lung cancer cells. The motility of A549, H1299, and CL1-5 cells were correlated with different AhR expression levels. Invasive potential and cell morphology also changed when AhR protein expression was altered. Moreover, AhR levels exerted a contrasting effect on autophagy potential. Autophagy was higher in CL1-5 and H1299 cells with lower AhR levels than in A549 cells. Both AhR overexpression and autophagy inhibition decreased CL1-5 metastasis in vivo. Furthermore, AhR promoted BNIP3 ubiquitination for proteasomal degradation. AhR silencing in A549 cells also reduced BNIP3 ubiquitination. Taken together, these results provide a novel insight into the cross-linking between AhR and autophagy, we addressed the mechanistic BNIP3 modulation by endogenous AhR, which affect cancer cell EMT progression. PMID:28195146

  15. A design principle underlying the paradoxical roles of E3 ubiquitin ligases

    Science.gov (United States)

    Lee, Daewon; Kim, Minjin; Cho, Kwang-Hyun

    2014-07-01

    E3 ubiquitin ligases are important cellular components that determine the specificity of proteolysis in the ubiquitin-proteasome system. However, an increasing number of studies have indicated that E3 ubiquitin ligases also participate in transcription. Intrigued by the apparently paradoxical functions of E3 ubiquitin ligases in both proteolysis and transcriptional activation, we investigated the underlying design principles using mathematical modeling. We found that the antagonistic functions integrated in E3 ubiquitin ligases can prevent any undesirable sustained activation of downstream genes when E3 ubiquitin ligases are destabilized by unexpected perturbations. Interestingly, this design principle of the system is similar to the operational principle of a safety interlock device in engineering systems, which prevents a system from abnormal operation unless stability is guaranteed.

  16. Autophagy and cancer

    Institute of Scientific and Technical Information of China (English)

    Si-Zhao; Lu; Duygu; Dee; Harrison-Findik

    2013-01-01

    Autophagy is a homeostatic and evolutionarily conserved mechanism of self-digestion by which the cells degrade and recycle long-lived proteins and excess or damaged organelles.Autophagy is activated in response to both physiological and pathological stimuli including growth factor depletion,energy deficiency or the upregulation of Bcl-2 protein expression.A novel role of autophagy in various cancers has been proposed.Interestingly,evidence that supports both a positive and negative role of autophagy in the pathogenesis of cancer has been reported.As a tumor suppression mechanism,autophagy maintains genome stability,induces senescence and possibly autophagic cell death.On the other hand,autophagy participates in tumor growth and maintenance by supplying metabolic substrate,limiting oxidative stress,and maintaining cancer stem cell population.It has been proposed that the differential roles of autophagy in cancer are disease type and stage specific.In addition,substrate selectivity might be involved in carrying out the specific effect of autophagy in cancer,and represents one of the potential directions for future studies.

  17. Autophagy and apoptosis act as partners to induce germ cell death after heat stress in mice.

    Directory of Open Access Journals (Sweden)

    Mianqiu Zhang

    Full Text Available Testicular heating suppresses spermatogenesis which is marked by germ cell loss via apoptotic pathways. Recently, it is reported that autophagy also can be induced by heat treatment in somatic cells. In this study, the status of autophagy in germ cells after heat treatment, as well as the partnership between autophagy and apoptosis in these cells was investigated. The results demonstrated that besides initiating apoptotic pathways, heat also induced autophagic pathways in germ cells. Exposure of germ cells to hyperthermia resulted in several specific features of the autophagic process, including autophagosome formation and the conversion of LC3-I to LC3-II. Furthermore, the ubiquitin-like protein conjugation system was implicated as being likely responsible for heat-induced autophagy in germ cells since all genes involving this system were found to be expressed in the testes. In addition, the upstream protein in this system, Atg7 (Autophagy-related gene 7, was found to be expressed in all types of spermatogenic cells, and its expression level was positively correlated with the level of autophagy in germ cells. As a result, Atg7 was selected as the investigative target to further analyze the role of autophagy in heat-induced germ cell death. It was shown that down expression of Atg7 protein resulted in the notable decrease in the level of autophagy in heat-treated germ cells, and this down-regulation of autophagy caused by Atg7 knockdown further reduced the apoptotic rate of germ cells. These results suggest that autophagy plays a positive role in the process of germ cell apoptosis after heat treatment. In conclusion, this study demonstrates that heat triggers autophagy and apoptosis in germ cells. These two mechanisms might act as partners, not antagonist, to induce cell death and lead to eventual destruction of spermatogenesis.

  18. Autophagy and ethanol neurotoxicity.

    Science.gov (United States)

    Luo, Jia

    2014-01-01

    Excessive ethanol exposure is detrimental to the brain. The developing brain is particularly vulnerable to ethanol such that prenatal ethanol exposure causes fetal alcohol spectrum disorders (FASD). Neuronal loss in the brain is the most devastating consequence and is associated with mental retardation and other behavioral deficits observed in FASD. Since alcohol consumption during pregnancy has not declined, it is imperative to elucidate the underlying mechanisms and develop effective therapeutic strategies. One cellular mechanism that acts as a protective response for the central nervous system (CNS) is autophagy. Autophagy regulates lysosomal turnover of organelles and proteins within cells, and is involved in cell differentiation, survival, metabolism, and immunity. We have recently shown that ethanol activates autophagy in the developing brain. The autophagic preconditioning alleviates ethanol-induced neuron apoptosis, whereas inhibition of autophagy potentiates ethanol-stimulated reactive oxygen species (ROS) and exacerbates ethanol-induced neuroapoptosis. The expression of genes encoding proteins required for autophagy in the CNS is developmentally regulated; their levels are much lower during an ethanol-sensitive period than during an ethanol-resistant period. Ethanol may stimulate autophagy through multiple mechanisms; these include induction of oxidative stress and endoplasmic reticulum stress, modulation of MTOR and AMPK signaling, alterations in BCL2 family proteins, and disruption of intracellular calcium (Ca2+) homeostasis. This review discusses the most recent evidence regarding the involvement of autophagy in ethanol-mediated neurotoxicity as well as the potential therapeutic approach of targeting autophagic pathways.

  19. Calcium-permeable ion channels in control of autophagy and cancer.

    Science.gov (United States)

    Kondratskyi, Artem; Yassine, Maya; Kondratska, Kateryna; Skryma, Roman; Slomianny, Christian; Prevarskaya, Natalia

    2013-01-01

    Autophagy, or cellular self-eating, is a tightly regulated cellular pathway the main purpose of which is lysosomal degradation and subsequent recycling of cytoplasmic material to maintain normal cellular homeostasis. Defects in autophagy are linked to a variety of pathological states, including cancer. Cancer is the disease associated with abnormal tissue growth following an alteration in such fundamental cellular processes as apoptosis, proliferation, differentiation, migration and autophagy. The role of autophagy in cancer is complex, as it can promote both tumor prevention and survival/treatment resistance. It's now clear that modulation of autophagy has a great potential in cancer diagnosis and treatment. Recent findings identified intracellular calcium as an important regulator of both basal and induced autophagy. Calcium is a ubiquitous secondary messenger which regulates plethora of physiological and pathological processes such as aging, neurodegeneration and cancer. The role of calcium and calcium-permeable channels in cancer is well-established, whereas the information about molecular nature of channels regulating autophagy and the mechanisms of this regulation is still limited. Here we review existing mechanisms of autophagy regulation by calcium and calcium-permeable ion channels. Furthermore, we will also discuss some calcium-permeable channels as the potential new candidates for autophagy regulation. Finally we will propose the possible link between calcium permeable channels, autophagy and cancer progression and therapeutic response.

  20. SLC9A3R1 stimulates autophagy via BECN1 stabilization in breast cancer cells.

    Science.gov (United States)

    Liu, Hong; Ma, Yan; He, Hong-Wei; Wang, Jia-Ping; Jiang, Jian-Dong; Shao, Rong-Guang

    2015-01-01

    Autophagy, a self-catabolic process, has been found to be involved in abrogating the proliferation and metastasis of breast cancer. SLC9A3R1 (solute carrier family 9, subfamily A [NHE3, cation proton antiporter 3], member 3 regulator 1), a multifunctional scaffold protein, is involved in suppressing breast cancer cells proliferation and the SLC9A3R1-related signaling pathway regulates the activation of autophagy processes. However, the precise regulatory mechanism and signaling pathway of SLC9A3R1 in the regulation of autophagy processes in breast cancer cells remains unknown. Here, we report that the stability of BECN1, the major component of the autophagic core lipid kinase complex, is augmented in SLC9A3R1-overexpressing breast cancer MDA-MB-231 cells, subsequently stimulating autophagy by attenuating the interaction between BECN1 and BCL2. Initially, we found that SLC9A3R1 partially stimulated autophagy through the PTEN-PI3K-AKT1 signaling cascade in MDA-MB-231 cells. SLC9A3R1 then attenuated the interaction between BECN1 and BCL2 to stimulate the autophagic core lipid kinase complex. Further findings revealed that SLC9A3R1 bound to BECN1 and subsequently blocked ubiquitin-dependent BECN1 degradation. And the deletion of the C-terminal domain of SLC9A3R1 resulted in significantly reduced binding to BECN1. Moreover, the lack of C-terminal of SLC9A3R1 neither reduced the ubiquitination of BECN1 nor induced autophagy in breast cancer cells. The decrease in BECN1 degradation induced by SLC9A3R1 resulted in the activity of autophagy stimulation in breast cancer cells. These findings indicate that the SLC9A3R1-BECN1 signaling pathway participates in the activation of autophagy processes in breast cancer cells.

  1. TNFAIP3 promotes survival of CD4 T cells by restricting MTOR and promoting autophagy.

    Science.gov (United States)

    Matsuzawa, Yu; Oshima, Shigeru; Takahara, Masahiro; Maeyashiki, Chiaki; Nemoto, Yasuhiro; Kobayashi, Masanori; Nibe, Yoichi; Nozaki, Kengo; Nagaishi, Takashi; Okamoto, Ryuichi; Tsuchiya, Kiichiro; Nakamura, Tetsuya; Ma, Averil; Watanabe, Mamoru

    2015-01-01

    Autophagy plays important roles in metabolism, differentiation, and survival in T cells. TNFAIP3/A20 is a ubiquitin-editing enzyme that is thought to be a negative regulator of autophagy in cell lines. However, the role of TNFAIP3 in autophagy remains unclear. To determine whether TNFAIP3 regulates autophagy in CD4 T cells, we first analyzed Tnfaip3-deficient naïve CD4 T cells in vitro. We demonstrated that Tnfaip3-deficient CD4 T cells exhibited reduced MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3) puncta formation, increased mitochondrial content, and exaggerated reactive oxygen species (ROS) production. These results indicate that TNFAIP3 promotes autophagy after T cell receptor (TCR) stimulation in CD4 T cells. We then investigated the mechanism by which TNFAIP3 promotes autophagy signaling. We found that TNFAIP3 bound to the MTOR (mechanistic target of rapamycin) complex and that Tnfaip3-deficient cells displayed enhanced ubiquitination of the MTOR complex and MTOR activity. To confirm the effects of enhanced MTOR activity in Tnfaip3-deficient cells, we analyzed cell survival following treatment with Torin1, an MTOR inhibitor. Tnfaip3-deficient CD4 T cells exhibited fewer cell numbers than the control cells in vitro and in vivo. In addition, the impaired survival of Tnfaip3-deficient cells was ameliorated with Torin1 treatment in vitro and in vivo. The effect of Torin1 was abolished by Atg5 deficiency. Thus, enhanced MTOR activity regulates the survival of Tnfaip3-deficient CD4 T cells. Taken together, our findings illustrate that TNFAIP3 restricts MTOR signaling and promotes autophagy, providing new insight into the manner in which MTOR and autophagy regulate survival in CD4 T cells.

  2. Restarting stalled autophagy a potential therapeutic approach for the lipid storage disorder, Niemann-Pick type C1 disease.

    Science.gov (United States)

    Sarkar, Sovan; Maetzel, Dorothea; Korolchuk, Viktor I; Jaenisch, Rudolf

    2014-06-01

    Autophagy is essential for cellular homeostasis and its dysfunction in human diseases has been implicated in the accumulation of misfolded protein and in cellular toxicity. We have recently shown impairment in autophagic flux in the lipid storage disorder, Niemann-Pick type C1 (NPC1) disease associated with abnormal cholesterol sequestration, where maturation of autophagosomes is impaired due to defective amphisome formation caused by failure in SNARE machinery. Abrogation of autophagy also causes cholesterol accumulation, suggesting that defective autophagic flux in NPC1 disease may act as a primary causative factor not only by imparting its deleterious effects, but also by increasing cholesterol load. However, cholesterol depletion treatment with HP-β-cyclodextrin impedes autophagy, whereas pharmacologically stimulating autophagy restores its function independent of amphisome formation. Of potential therapeutic relevance is that a low dose of HP-β-cyclodextrin that does not perturb autophagy, coupled with an autophagy inducer, may rescue both the cholesterol and autophagy defects in NPC1 disease.

  3. Lysosome dysfunction enhances oxidative stress-induced apoptosis through ubiquitinated protein accumulation in Hela cells.

    Science.gov (United States)

    Yu, Chunyan; Huang, Xiaowei; Xu, Ye; Li, Hongyan; Su, Jing; Zhong, Jiateng; Kang, Jinsong; Liu, Yuhe; Sun, Liankun

    2013-01-01

    The role of lysosomal system in oxidative stress-induced apoptosis in cancer cells is not fully understood. Menadione is frequently used as oxidative stress model. It is indicated that menadione could induce autophagy in Hela cells. In the present study, we examined whether the lysosomal inhibitor, ammonium chloride (NH(4)Cl) could prevent the autophagy flux by inhibiting the fusion of autophagosomes with lysosomes and enhance apoptosis induced by menadione via mitochondrial pathway. The results demonstrated generation and accumulation of reactive oxygen species and increased levels of ubiquitinated proteins and GRP78 in cells treated with both menadione and NH(4)Cl. Our data indicates that lysosomal system through autophagy plays an important role in preventing menadione-induced apoptosis in Hela cells by clearing misfolded proteins, which alleviates endoplasmic reticulum stress.

  4. Inhibition of autophagy induced by proteasome inhibition increases cell death in human SHG-44 glioma cells

    Institute of Scientific and Technical Information of China (English)

    Peng-fei GE; Ji-zhou ZHANG; Xiao-fei WANG; Fan-kai MENG; Wen-chen LI; Yong-xin LUAN; Feng LING; Yi-nan LUO

    2009-01-01

    Aim:The ubiquitin-proteasome system (UPS) and lysosome-dependent macroautophagy (autophagy) are two major intracellular pathways for protein degradation.Recent studies suggest that proteasome inhibitors may reduce tumor growth and activate autophagy.Due to the dual roles of autophagy in tumor cell survival and death,the effect of autophagy on the destiny of glioma cells remains unclear.In this study,we sought to investigate whether inhibition of the proteasome can induce autophagy and the effects of autophagy on the fate of human SHG-44 glioma cells.Methods:The proteasome inhibitor MG-132 was used to induce autophagy in SHG-44 glioma cells,and the effect of autophagy on the survival of SHG-44 glioma cells was investigated using an autophagy inhibitor 3-MA.Cell viability was measured by MTT assay.Apoptosis and cell cycle were detected by flow cytometry.The expression of autophagy related proteins was determined by Western blot.Results:MG-132 inhibited cell proliferation,induced cell death and cell cycle arrest at G~JM phase,and activated autophagy in SHG-44 glioma cells.The expression of autophagy-related Beclin-1 and LC3-1 was significantly up-regulated and part of LC3-1 was converted into LC3-11.However,when SHG-44 glioma cells were co-treated with MG-132 and 3-MA,the cells became less viable,but cell death and cell numbers at G2/M phase increased.Moreover,the accumulation of acidic vesicular organelles was decreased,the expression of Beclin-1 and LC3 was significantly down-regulated and the conversion of LC3-11 from LC3-1 was also inhibited.Conclusion:Inhibition of the proteasome can induce autophagy in human SHG-44 glioma cells,and inhibition of autophagy increases cell death.This discovery may shed new light on the effect of autophagy on modulating the fate of SHG-44 glioma cells.

  5. The Role of Ubiquitine Proteasome Pathway in Carcinogenesis

    Directory of Open Access Journals (Sweden)

    N.Ceren Sumer Turanligil

    2010-02-01

    Full Text Available Ubiquitin works as a marker protein which targets misfolded or injured proteins to cellular degradation. It brings the abnormal proteins to a subcellular organelle named proteasome and it maintains the degradation of proteins in limited lenghts of peptides by leaving the process withuout being changed. Mistakes in ubiquitin-dependent proteolysis in various steps of carcinogenesis is known. In this review, we dealed with the effects of ubiquitin-proteasome pathway (UPP on carcinogenesis via intercellular signaling molecules like Ras, transcription factors like NF-kB, cytokines like TNF-alfa Tumor necrosis factor, protooncogenes like p53 and MDM2(murine double minute 2, components of cell cycle and DNA repair proteins like BRCA1. We also focused on the relationship of UPP on antigen presentation which is active in immune response and its place in the aetiology of colon cancer to provide a specific example. [Archives Medical Review Journal 2010; 19(1.000: 36-55

  6. Chemical Inhibition of Autophagy

    DEFF Research Database (Denmark)

    Baek, Eric; Lin Kim, Che; Gyeom Kim, Mi;

    2016-01-01

    Chinese hamster ovary (CHO) cells activate and undergo apoptosis and autophagy for various environmental stresses. Unlike apoptosis, studies on increasing the production of therapeutic proteins in CHO cells by targeting the autophagy pathway are limited. In order to identify the effects of chemical...... autophagy inhibitors on the specific productivity (qp), nine chemical inhibitors that had been reported to target three different phases of autophagy (metformin, dorsomorphin, resveratrol, and SP600125 against initiation and nucleation; 3-MA, wortmannin, and LY294002 against elongation, and chloroquine...... and bafilomycin A1 against autophagosome fusion) were used to treat three recombinant CHO (rCHO) cell lines: the Fc-fusion protein-producing DG44 (DG44-Fc) and DUKX-B11 (DUKX-Fc) and antibody-producing DG44 (DG44-Ab) cell lines. Among the nine chemical inhibitors tested, 3-MA, dorsomorphin, and SP600125...

  7. Autophagy and cytokines.

    Science.gov (United States)

    Harris, James

    2011-11-01

    Autophagy is a highly conserved homoeostatic mechanism for the lysosomal degradation of cytosolic constituents, including long-lived macromolecules, organelles and intracellular pathogens. Autophagosomes are formed in response to a number of environmental stimuli, including amino acid deprivation, but also by both host- and pathogen-derived molecules, including toll-like receptor ligands and cytokines. In particular, IFN-γ, TNF-α, IL-1, IL-2, IL-6 and TGF-β have been shown to induce autophagy, while IL-4, IL-10 and IL-13 are inhibitory. Moreover, autophagy can itself regulate the production and secretion of cytokines, including IL-1, IL-18, TNF-α, and Type I IFN. This review discusses the potentially pivotal roles of autophagy in the regulation of inflammation and the coordination of innate and adaptive immune responses.

  8. Ubiquitin domain proteins in disease

    DEFF Research Database (Denmark)

    Klausen, Louise Kjær; Schulze, Andrea; Seeger, Michael;

    2007-01-01

    The human genome encodes several ubiquitin-like (UBL) domain proteins (UDPs). Members of this protein family are involved in a variety of cellular functions and many are connected to the ubiquitin proteasome system, an essential pathway for protein degradation in eukaryotic cells. Despite...... and cancer. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com)....

  9. Autophagy in Trypanosomatids

    Directory of Open Access Journals (Sweden)

    Paul A. M. Michels

    2012-07-01

    Full Text Available Autophagy is a ubiquitous eukaryotic process that also occurs in trypanosomatid parasites, protist organisms belonging to the supergroup Excavata, distinct from the supergroup Opistokontha that includes mammals and fungi. Half of the known yeast and mammalian AuTophaGy (ATG proteins were detected in trypanosomatids, although with low sequence conservation. Trypanosomatids such as Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp. are responsible for serious tropical diseases in humans. The parasites are transmitted by insects and, consequently, have a complicated life cycle during which they undergo dramatic morphological and metabolic transformations to adapt to the different environments. Autophagy plays a major role during these transformations. Since inhibition of autophagy affects the transformation, survival and/or virulence of the parasites, the ATGs offer promise for development of drugs against tropical diseases. Furthermore, various trypanocidal drugs have been shown to trigger autophagy-like processes in the parasites. It is inferred that autophagy is used by the parasites in an—not always successful—attempt to cope with the stress caused by the toxic compounds.

  10. Role of autophagy in COPD skeletal muscle dysfunction.

    Science.gov (United States)

    Hussain, Sabah N A; Sandri, Marco

    2013-05-01

    Chronic obstructive pulmonary disease (COPD) is a debilitating disease caused by parenchymal damage and irreversible airflow limitation. In addition to lung dysfunction, patients with COPD develop weight loss, malnutrition, poor exercise performance, and skeletal muscle atrophy. The latter has been attributed to an imbalance between muscle protein synthesis and protein degradation. Several reports have confirmed that enhanced protein degradation and atrophy of limb muscles of COPD patient is mediated in part through activation of the ubiquitin-proteasome pathway and that this activation is triggered by enhanced production of reactive oxygen species. Until recently, the importance of the autophagy-lysosome pathway in protein degradation of skeletal muscles has been largely ignored, however, recent evidence suggests that this pathway is actively involved in recycling of cytosolic proteins, organelles, and protein aggregates in normal skeletal muscles. The protective role of autophagy in the regulation of muscle mass has recently been uncovered in mice with muscle-specific suppression of autophagy. These mice develop severe muscle weakness, atrophy, and decreased muscle contractility. No information is yet available about the involvement of the autophagy in the regulation of skeletal muscle mass in COPD patients. Pilot experiments on vastus lateralis muscle samples suggest that the autophagy-lysosome system is induced in COPD patients compared with control subjects. In this review, we summarize recent progress related to molecular structure, regulation, and roles of the autophagy-lysosome pathway in normal and diseased skeletal muscles. We also speculate about regulation and functional importance of this system in skeletal muscle dysfunction in COPD patients.

  11. Phospho-ubiquitin: upending the PINK-Parkin-ubiquitin cascade.

    Science.gov (United States)

    Matsuda, Noriyuki

    2016-04-01

    Mitochondria with decreased membrane potential are characterized by defects in protein import into the matrix and impairments in high-efficiency synthesis of ATP. These low-quality mitochondria are marked with ubiquitin for selective degradation. Key factors in this mechanism are PTEN-induced putative kinase 1 (PINK1, a mitochondrial kinase) and Parkin (a ubiquitin ligase), disruption of which has been implicated in predisposition to Parkinson's disease. Previously, the clearance of damaged mitochondria had been thought to be the end result of a simple cascading reaction of PINK1-Parkin-ubiquitin. However, in the past year, several research groups including ours unexpectedly revealed that Parkin regulation is mediated by PINK1-dependent phosphorylation of ubiquitin. These results overturned the simple hierarchy that posited PINK1 and ubiquitin as the upstream and downstream factors of Parkin, respectively. Although ubiquitylation is well-known as a post-translational modification, it has recently become clear that ubiquitin itself can be modified, and that this modification unexpectedly converts ubiquitin to a factor that functions in retrograde signalling.

  12. The ubiquitin-proteasome system in spongiform degenerative disorders.

    Science.gov (United States)

    Whatley, Brandi R; Li, Lian; Chin, Lih-Shen

    2008-12-01

    Spongiform degeneration is characterized by vacuolation in nervous tissue accompanied by neuronal death and gliosis. Although spongiform degeneration is a hallmark of prion diseases, this pathology is also present in the brains of patients suffering from Alzheimer's disease, diffuse Lewy body disease, human immunodeficiency virus (HIV) infection, and Canavan's spongiform leukodystrophy. The shared outcome of spongiform degeneration in these diverse diseases suggests that common cellular mechanisms must underlie the processes of spongiform change and neurodegeneration in the central nervous system. Immunohistochemical analysis of brain tissues reveals increased ubiquitin immunoreactivity in and around areas of spongiform change, suggesting the involvement of ubiquitin-proteasome system dysfunction in the pathogenesis of spongiform neurodegeneration. The link between aberrant ubiquitination and spongiform neurodegeneration has been strengthened by the discovery that a null mutation in the E3 ubiquitin-protein ligase mahogunin ring finger-1 (Mgrn1) causes an autosomal recessively inherited form of spongiform neurodegeneration in animals. Recent studies have begun to suggest that abnormal ubiquitination may alter intracellular signaling and cell functions via proteasome-dependent and proteasome-independent mechanisms, leading to spongiform degeneration and neuronal cell death. Further elucidation of the pathogenic pathways involved in spongiform neurodegeneration should facilitate the development of novel rational therapies for treating prion diseases, HIV infection, and other spongiform degenerative disorders.

  13. Retinoid receptor signaling and autophagy in acute promyelocytic leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Orfali, Nina [Cork Cancer Research Center, University College Cork, Cork (Ireland); Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA. (United States); McKenna, Sharon L. [Cork Cancer Research Center, University College Cork, Cork (Ireland); Cahill, Mary R. [Department of Hematology, Cork University Hospital, Cork (Ireland); Gudas, Lorraine J., E-mail: ljgudas@med.cornell.edu [Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA. (United States); Mongan, Nigel P., E-mail: nigel.mongan@nottingham.ac.uk [Faculty of Medicine and Health Science, School of Veterinary Medicine and Science, University of Nottingham, LE12 5RD (United Kingdom); Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA. (United States)

    2014-05-15

    Retinoids are a family of signaling molecules derived from vitamin A with well established roles in cellular differentiation. Physiologically active retinoids mediate transcriptional effects on cells through interactions with retinoic acid (RARs) and retinoid-X (RXR) receptors. Chromosomal translocations involving the RARα gene, which lead to impaired retinoid signaling, are implicated in acute promyelocytic leukemia (APL). All-trans-retinoic acid (ATRA), alone and in combination with arsenic trioxide (ATO), restores differentiation in APL cells and promotes degradation of the abnormal oncogenic fusion protein through several proteolytic mechanisms. RARα fusion-protein elimination is emerging as critical to obtaining sustained remission and long-term cure in APL. Autophagy is a degradative cellular pathway involved in protein turnover. Both ATRA and ATO also induce autophagy in APL cells. Enhancing autophagy may therefore be of therapeutic benefit in resistant APL and could broaden the application of differentiation therapy to other cancers. Here we discuss retinoid signaling in hematopoiesis, leukemogenesis, and APL treatment. We highlight autophagy as a potential important regulator in anti-leukemic strategies. - Highlights: • Normal and aberrant retinoid signaling in hematopoiesis and leukemia is reviewed. • We suggest a novel role for RARα in the development of X-RARα gene fusions in APL. • ATRA therapy in APL activates transcription and promotes onco-protein degradation. • Autophagy may be involved in both onco-protein degradation and differentiation. • Pharmacologic autophagy induction may potentiate ATRA's therapeutic effects.

  14. Autophagy research: Lessons from metabolism

    NARCIS (Netherlands)

    A.J. Meijer

    2009-01-01

    Autophagy research continues to expand exponentially. Clearly autophagy and metabolism are intimately connected; however, the rapid expansion of research into this topic inevitably brings the risk that important basic knowledge of metabolism will be overlooked when considering experimental data. Unf

  15. Boosting autophagy in the diabetic heart: a translational perspective.

    Science.gov (United States)

    Sciarretta, Sebastiano; Boppana, V Subbarao; Umapathi, Mahaa; Frati, Giacomo; Sadoshima, Junichi

    2015-10-01

    Diabetes, obesity, and dyslipidemia are main risk factors that promote the development of cardiovascular diseases. These metabolic abnormalities are frequently found to be associated together in a highly morbid clinical condition called metabolic syndrome. Metabolic derangements promote endothelial dysfunction, atherosclerotic plaque formation and rupture, cardiac remodeling and dysfunction. This evidence strongly encourages the elucidation of the mechanisms through which obesity, diabetes, and metabolic syndrome induce cellular abnormalities and dysfunction in order to discover new therapeutic targets and strategies for their prevention and treatment. Numerous studies employing both dietary and genetic animal models of obesity and diabetes have demonstrated that autophagy, an intracellular system for protein degradation, is impaired in the heart under these conditions. This suggests that autophagy reactivation may represent a future potential therapeutic intervention to reduce cardiac maladaptive alterations in patients with metabolic derangements. In fact, autophagy is a critical mechanism to preserve cellular homeostasis and survival. In addition, the physiological activation of autophagy protects the heart during stress, such as acute ischemia, starvation, chronic myocardial infarction, pressure overload, and proteotoxic stress. All these aspects will be discussed in our review article together with the potential ways to reactivate autophagy in the context of obesity, metabolic syndrome, and diabetes.

  16. Proteasome inhibition promotes Parkin-Ubc13 interaction and lysine 63-linked ubiquitination.

    Directory of Open Access Journals (Sweden)

    Grace G Y Lim

    Full Text Available Disruption of the ubiquitin-proteasome system, which normally identifies and degrades unwanted intracellular proteins, is thought to underlie neurodegeneration. Supporting this, mutations of Parkin, a ubiquitin ligase, are associated with autosomal recessive parkinsonism. Remarkably, Parkin can protect neurons against a wide spectrum of stress, including those that promote proteasome dysfunction. Although the mechanism underlying the preservation of proteasome function by Parkin is hitherto unclear, we have previously proposed that Parkin-mediated K63-linked ubiquitination (which is usually uncoupled from the proteasome may serve to mitigate proteasomal stress by diverting the substrate load away from the machinery. By means of linkage-specific antibodies, we demonstrated here that proteasome inhibition indeed promotes K63-linked ubiquitination of proteins especially in Parkin-expressing cells. Importantly, we further demonstrated that the recruitment of Ubc13 (an E2 that mediates K63-linked polyubiquitin chain formation exclusively by Parkin is selectively enhanced under conditions of proteasomal stress, thus identifying a mechanism by which Parkin could promote K63-linked ubiquitin modification in cells undergoing proteolytic stress. This mode of ubiquitination appears to facilitate the subsequent clearance of Parkin substrates via autophagy. Consistent with the proposed protective role of K63-linked ubiquitination in times of proteolytic stress, we found that Ubc13-deficient cells are significantly more susceptible to cell death induced by proteasome inhibitors compared to their wild type counterparts. Taken together, our study suggests a role for Parkin-mediated K63 ubiquitination in maintaining cellular protein homeostasis, especially during periods when the proteasome is burdened or impaired.

  17. Impaired macrophage autophagy increases the immune response in obese mice by promoting proinflammatory macrophage polarization.

    Science.gov (United States)

    Liu, Kun; Zhao, Enpeng; Ilyas, Ghulam; Lalazar, Gadi; Lin, Yu; Haseeb, Muhammad; Tanaka, Kathryn E; Czaja, Mark J

    2015-01-01

    Recent evidence that excessive lipid accumulation can decrease cellular levels of autophagy and that autophagy regulates immune responsiveness suggested that impaired macrophage autophagy may promote the increased innate immune activation that underlies obesity. Primary bone marrow-derived macrophages (BMDM) and peritoneal macrophages from high-fat diet (HFD)-fed mice had decreased levels of autophagic flux indicating a generalized impairment of macrophage autophagy in obese mice. To assess the effects of decreased macrophage autophagy on inflammation, mice with a Lyz2-Cre-mediated knockout of Atg5 in macrophages were fed a HFD and treated with low-dose lipopolysaccharide (LPS). Knockout mice developed systemic and hepatic inflammation with HFD feeding and LPS. This effect was liver specific as knockout mice did not have increased adipose tissue inflammation. The mechanism by which the loss of autophagy promoted inflammation was through the regulation of macrophage polarization. BMDM and Kupffer cells from knockout mice exhibited abnormalities in polarization with both increased proinflammatory M1 and decreased anti-inflammatory M2 polarization as determined by measures of genes and proteins. The heightened hepatic inflammatory response in HFD-fed, LPS-treated knockout mice led to liver injury without affecting steatosis. These findings demonstrate that autophagy has a critical regulatory function in macrophage polarization that downregulates inflammation. Defects in macrophage autophagy may underlie inflammatory disease states such as the decrease in macrophage autophagy with obesity that leads to hepatic inflammation and the progression to liver injury.

  18. The ubiquitin-proteasome system

    Indian Academy of Sciences (India)

    Dipankar Nandi; Pankaj Tahiliani; Anujith Kumar; Dilip Chandu

    2006-03-01

    The 2004 Nobel Prize in chemistry for the discovery of protein ubiquitination has led to the recognition of cellular proteolysis as a central area of research in biology. Eukaryotic proteins targeted for degradation by this pathway are first ‘tagged’ by multimers of a protein known as ubiquitin and are later proteolyzed by a giant enzyme known as the proteasome. This article recounts the key observations that led to the discovery of ubiquitin-proteasome system (UPS). In addition, different aspects of proteasome biology are highlighted. Finally, some key roles of the UPS in different areas of biology and the use of inhibitors of this pathway as possible drug targets are discussed.

  19. Ubiquitin in the immune system

    OpenAIRE

    Julia Zinngrebe; Antonella Montinaro; Nieves Peltzer; Henning Walczak

    2013-01-01

    Ubiquitination is a post-translational modification process that has been implicated in the regulation of innate and adaptive immune responses. There is increasing evidence that both ubiquitination and its reversal, deubiquitination, play crucial roles not only during the development of the immune system but also in the orchestration of an immune response by ensuring the proper functioning of the different cell types that constitute the immune system. Here, we provide an overview of the lates...

  20. Selective autophagy of non-ubiquitylated targets in plants: looking for cognate receptor/adaptor proteins

    Directory of Open Access Journals (Sweden)

    Vasko eVeljanovski

    2014-06-01

    Full Text Available Cellular homeostasis is essential for the physiology of eukaryotic cells. Eukaryotic cells, including plant cells, utilize two main pathways to adjust the level of cytoplasmic components, namely the proteasomal and the lysosomal/vacuolar pathways. Macroautophagy is a lysosomal/vacuolar pathway which, until recently, was thought to be non-specific and a bulk degradation process. However, selective autophagy which can be activated in the cell under various physiological conditions, involves the specific degradation of defined macromolecules or organelles by a conserved molecular mechanism. For this process to be efficient, the mechanisms underlying the recognition and selection of the cargo to be engulfed by the double-membrane autophagosome are critical, and not yet well understood. Ubiquitin (poly-ubiquitin conjugation to the target appears to be a conserved ligand mechanism in many types of selective autophagy, and defined receptors/adaptors recognizing and regulating the autophagosomal capture of the ubiquitylated target have been characterized. However, non-proteinaceous and non-ubiquitylated cargoes are also selectively degraded by this pathway. This ubiquitin-independent selective autophagic pathway also involves receptor and/or adaptor proteins linking the cargo to the autophagic machinery. Some of these receptor/adaptor proteins including accessory autophagy-related (Atg and non-Atg proteins have been described in yeast and animal cells but not yet in plants. In this review we discuss the ubiquitin-independent cargo selection mechanisms in selective autophagy degradation of organelles and macromolecules and speculate on potential plant receptor/adaptor proteins.

  1. Mechanism of action of the tuberculosis and Crohn disease risk factor IRGM in autophagy

    Science.gov (United States)

    Chauhan, Santosh; Mandell, Michael A.; Deretic, Vojo

    2016-01-01

    ABSTRACT Polymorphisms in the IRGM gene, associated with Crohn disease (CD) and tuberculosis, are among the earliest identified examples documenting the role of autophagy in human disease. Functional studies have shown that IRGM protects against these diseases by modulating autophagy, yet the exact molecular mechanism of IRGM's activity has remained unknown. We have recently elucidated IRGM's mechanism of action. IRGM functions as a platform for assembling, stabilizing, and activating the core autophagic machinery, while at the same time physically coupling it to conventional innate immunity receptors. Exposure to microbial products or bacterial invasion increases IRGM expression, which leads to stabilization of AMPK. Specific protein-protein interactions and post-translational modifications such as ubiquitination of IRGM, lead to a co-assembly with IRGM of the key autophagy regulators ULK1 and BECN1 in their activated forms. IRGM physically interacts with 2 other CD risk factors, ATG16L1 and NOD2, placing these 3 principal players in CD within the same molecular complex. This explains how polymorphisms altering expression or function of any of the 3 factors individually can affect the same process—autophagy. Furthermore, IRGM's interaction with NOD2, and additional pattern recognition receptors such as NOD1, RIG-I, and select TLRs, transduces microbial signals to the core autophagy apparatus. This work solves the long-standing enigma of how IRGM controls autophagy. PMID:26313894

  2. The Nobel Prize for understanding autophagy, a cellular mechanism of waste disposal that keeps us healthy

    Indian Academy of Sciences (India)

    MEGHA BANSAL; GHANSHYAM SWARUP

    2016-12-01

    The Nobel Prize in Physiology or Medicine, 2016, was awarded to Prof Yoshinori Ohsumi from TokyoInstitute of Technology, Yokohoma, Japan, for his work that helped in understanding the molecularmechanisms of autophagy, a process used by most eukaryotic cells to degrade a portion of cytoplasmincluding damaged organelles, large protein complexes and aggregated proteins in lysosomes. This processof autophagy (self-eating) maintains cellular homeostasis and helps the cell and the organism to surviveduring periods of stress, such as starvation, by recycling the cellular components to generate amino acidsand nutrients needed for producing energy. Autophagy and ubiquitin-proteasome system are the two majorprotein degradation systems in the cell.The lysosome was identified by Christian de Duve in the 1950s as a membrane bound organelle in thecell that contains degradative enzymes such as proteases, lipases, acid phosphatases, etc. (de Duve, 2005).The term autophagy was coined by Christian de Duve in 1963. Autophagy generally occurs at low level, butit increases under conditions such as stress and differentiation/remodelling of tissues. Autophagy wasprimarily studied by electron microscopy for decades because no molecular markers were available for itsmolecular analysis.

  3. Autophagy promotes oligodendrocyte survival and function following dysmyelination in a long-lived myelin mutant.

    Science.gov (United States)

    Smith, Chelsey M; Mayer, Joshua A; Duncan, Ian D

    2013-05-01

    The Long-Evans shaker (les) rat has a mutation in myelin basic protein that results in severe CNS dysmyelination and subsequent demyelination during development. During this time, les oligodendrocytes accumulate cytoplasmic vesicles, including lysosomes and membrane-bound organelles. However, the mechanism and functional relevance behind these oligodendrocyte abnormalities in les have not been investigated. Using high-magnification electron microscopy, we identified the accumulations in les oligodendrocytes as early and late autophagosomes. Additionally, immunohistochemistry and Western blots showed an increase in autophagy markers in les. However, autophagy did not precede the death of les oligodendrocytes. Instead, upregulating autophagy promoted membrane extensions in les oligodendrocytes in vitro. Furthermore, upregulating autophagy in les rats via intermittent fasting increased the proportion of myelinated axons as well as myelin sheath thickness in les and control rats. Overall, this study provides insight into the abnormalities described in les as well as identifying a novel mechanism that promotes the survival and function of oligodendrocytes.

  4. Oxidative stress, redox signaling pathways, and autophagy in cachectic muscles of male patients with advanced COPD and lung cancer.

    Science.gov (United States)

    Puig-Vilanova, Ester; Rodriguez, Diego A; Lloreta, Josep; Ausin, Pilar; Pascual-Guardia, Sergio; Broquetas, Joan; Roca, Josep; Gea, Joaquim; Barreiro, Esther

    2015-02-01

    Muscle dysfunction and wasting are predictors of mortality in advanced COPD and malignancies. Redox imbalance and enhanced protein catabolism are underlying mechanisms in COPD. We hypothesized that the expression profile of several biological markers share similarities in patients with cachexia associated with either COPD or lung cancer (LC). In vastus lateralis of cachectic patients with either LC (n=10) or advanced COPD (n=16) and healthy controls (n=10), markers of redox balance, inflammation, proteolysis, autophagy, signaling pathways, mitochondrial function, muscle structure, and sarcomere damage were measured using laboratory and light and electron microscopy techniques. Systemic redox balance and inflammation were also determined. All subjects were clinically evaluated. Compared to controls, in both cachectic groups of patients, a similar expression profile of different biological markers was observed in their muscles: increased levels of muscle protein oxidation and ubiquitination (pmuscle structural abnormalities and sarcomere disruptions were significantly greater (pmuscles of both cachectic patient groups than in controls (pmuscles of cachectic COPD patients (pmuscle wasting and sarcomere disruption in patients with respiratory cachexia: LC and COPD.

  5. The role of Smad Ubiquitin Regulatory Factor-1: SMURF1 in the differentiation 3T3-L1

    OpenAIRE

    Muñiz Diego, María del Carmen

    2013-01-01

    The Smad Ubiquitin Regulatory Factor-1: SMURF1 is an E3 ligase. This E3 ligase has been linked to several important biological pathways, including the bone morphogenetic protein pathway, the non-canonical Wnt pathway and the mitogen-activated protein kinase pathway. Multiple functions of Smurf1 have been discovered in cell growth and morphogenesis, cell migration, cell polarity and autophagy. Previous studies, in 2003, have demonstrated that overexpression of Smurf1 induces proteasomal degrad...

  6. Dopamine Oxidation and Autophagy

    Directory of Open Access Journals (Sweden)

    Patricia Muñoz

    2012-01-01

    Full Text Available The molecular mechanisms involved in the neurodegenerative process of Parkinson's disease remain unclear. Currently, there is a general agreement that mitochondrial dysfunction, α-synuclein aggregation, oxidative stress, neuroinflammation, and impaired protein degradation are involved in the neurodegeneration of dopaminergic neurons containing neuromelanin in Parkinson's disease. Aminochrome has been proposed to play an essential role in the degeneration of dopaminergic neurons containing neuromelanin by inducing mitochondrial dysfunction, oxidative stress, the formation of neurotoxic α-synuclein protofibrils, and impaired protein degradation. Here, we discuss the relationship between the oxidation of dopamine to aminochrome, the precursor of neuromelanin, autophagy dysfunction in dopaminergic neurons containing neuromelanin, and the role of dopamine oxidation to aminochrome in autophagy dysfunction in dopaminergic neurons. Aminochrome induces the following: (i the formation of α-synuclein protofibrils that inactivate chaperone-mediated autophagy; (ii the formation of adducts with α- and β-tubulin, which induce the aggregation of the microtubules required for the fusion of autophagy vacuoles and lysosomes.

  7. DNA damage and autophagy

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Rocha, Humberto; Garcia-Garcia, Aracely [Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583 (United States); Panayiotidis, Mihalis I. [School of Community Health Sciences, University of Nevada, Reno, NV 89557 (United States); Franco, Rodrigo, E-mail: rfrancocruz2@unl.edu [Redox Biology Center and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583 (United States)

    2011-06-03

    Both exogenous and endogenous agents are a threat to DNA integrity. Exogenous environmental agents such as ultraviolet (UV) and ionizing radiation, genotoxic chemicals and endogenous byproducts of metabolism including reactive oxygen species can cause alterations in DNA structure (DNA damage). Unrepaired DNA damage has been linked to a variety of human disorders including cancer and neurodegenerative disease. Thus, efficient mechanisms to detect DNA lesions, signal their presence and promote their repair have been evolved in cells. If DNA is effectively repaired, DNA damage response is inactivated and normal cell functioning resumes. In contrast, when DNA lesions cannot be removed, chronic DNA damage triggers specific cell responses such as cell death and senescence. Recently, DNA damage has been shown to induce autophagy, a cellular catabolic process that maintains a balance between synthesis, degradation, and recycling of cellular components. But the exact mechanisms by which DNA damage triggers autophagy are unclear. More importantly, the role of autophagy in the DNA damage response and cellular fate is unknown. In this review we analyze evidence that supports a role for autophagy as an integral part of the DNA damage response.

  8. The Autophagy Receptor TAX1BP1 and the Molecular Motor Myosin VI Are Required for Clearance of Salmonella Typhimurium by Autophagy.

    Directory of Open Access Journals (Sweden)

    David A Tumbarello

    2015-10-01

    Full Text Available Autophagy plays a key role during Salmonella infection, by eliminating these pathogens following escape into the cytosol. In this process, selective autophagy receptors, including the myosin VI adaptor proteins optineurin and NDP52, have been shown to recognize cytosolic pathogens. Here, we demonstrate that myosin VI and TAX1BP1 are recruited to ubiquitylated Salmonella and play a key role in xenophagy. The absence of TAX1BP1 causes an accumulation of ubiquitin-positive Salmonella, whereas loss of myosin VI leads to an increase in ubiquitylated and LC3-positive bacteria. Our structural studies demonstrate that the ubiquitin-binding site of TAX1BP1 overlaps with the myosin VI binding site and point mutations in the TAX1BP1 zinc finger domains that affect ubiquitin binding also ablate binding to myosin VI. This mutually exclusive binding and the association of TAX1BP1 with LC3 on the outer limiting membrane of autophagosomes may suggest a molecular mechanism for recruitment of this motor to autophagosomes. The predominant role of TAX1BP1, a paralogue of NDP52, in xenophagy is supported by our evolutionary analysis, which demonstrates that functionally intact NDP52 is missing in Xenopus and mice, whereas TAX1BP1 is expressed in all vertebrates analysed. In summary, this work highlights the importance of TAX1BP1 as a novel autophagy receptor in myosin VI-mediated xenophagy. Our study identifies essential new machinery for the autophagy-dependent clearance of Salmonella typhimurium and suggests modulation of myosin VI motor activity as a potential therapeutic target in cellular immunity.

  9. The role of autophagy in epileptogenesis and in epilepsy-induced neuronal alterations.

    Science.gov (United States)

    Giorgi, Filippo Sean; Biagioni, Francesca; Lenzi, Paola; Frati, Alessandro; Fornai, Francesco

    2015-06-01

    Recent evidence suggests that autophagy alterations are present in a variety of neurological disorders. These range from neurodegenerative diseases to acute neurological insults. Thus, despite a role of autophagy was investigated in a variety of neurological diseases, only recently these studies included epilepsy. This was fostered by the evidence that rapamycin, a powerful autophagy inducer, strongly modulates a variety of seizure models and epilepsies. These findings were originally interpreted as the results of the inhibition exerted by rapamycin on the molecular complex named "mammalian Target of Rapamycin" (mTOR). Recently, an increasing number of papers demonstrated that mTOR inhibition produces a strong activation of the autophagy machinery. In this way, it is now increasingly recognized that what was once defined as mTORpathy in epileptogenesis may be partially explained by abnormalities in the autophagy machinery. The present review features a brief introductory statement about the autophagy machinery and discusses the involvement of autophagy in seizures and epilepsies. An emphasis is posed on evidence addressing both pros and cons making it sometime puzzling and sometime evident, the role of autophagy in the epileptic brain.

  10. Mutant alpha-synuclein and autophagy in PC12 cells

    Institute of Scientific and Technical Information of China (English)

    Kangyong Liu; Chunfeng Liu; Chuancheng Ren; Yaping Yang; Liwei Shen; Xuezhong Li; Fen Wang; Zhenghong Qin

    2011-01-01

    Several studies have demonstrated that overexpression of mutant α-synuclein in PC12 cells is related to occurrence of autophagy.The present study established mutant a-synuclein (A30P)-transfected PC12 cells and treated them with the autophagy inducer rapamycin and autophagy inhibitor wortmannin, respectively.Results demonstrated that mutant o-synuclein resulted in cell death via autophagy and involved α-synuclein accumulation, membrane lipid oxidation, and loss of plasma membrane integrity.Mutant α-synuclein (A30P) also mediated toxicity of1-methyl-4-phenylpyridinium ion.Moreover, rapamycin inhibited a-synuclein aggregation, while wortmannin promoted o-synuclein aggregation and cell death.To further determine the role of autophagy due to mutant a-synuclein, the present study measured expression of microtubule-associated protein light chain 3.Results revealed that wortmannin and 1-methyl-4-phenylpyridinium ion inhibited expression of microtubule-associated protein light chain 3,while rapamycin promoted its expression.These findings suggested that abnormal aggregation of a-synuclein induced autophagic programmed cell death in PC12 cells.

  11. A novel strategy to isolate ubiquitin conjugates reveals wide role for ubiquitination during neural development.

    Science.gov (United States)

    Franco, Maribel; Seyfried, Nicholas T; Brand, Andrea H; Peng, Junmin; Mayor, Ugo

    2011-05-01

    Ubiquitination has essential roles in neuronal development and function. Ubiquitin proteomics studies on yeast and HeLa cells have proven very informative, but there still is a gap regarding neuronal tissue-specific ubiquitination. In an organism context, direct evidence for the ubiquitination of neuronal proteins is even scarcer. Here, we report a novel proteomics strategy based on the in vivo biotinylation of ubiquitin to isolate ubiquitin conjugates from the neurons of Drosophila melanogaster embryos. We confidently identified 48 neuronal ubiquitin substrates, none of which was yet known to be ubiquitinated. Earlier proteomics and biochemical studies in non-neuronal cell types had identified orthologs to some of those but not to others. The identification here of novel ubiquitin substrates, those with no known ubiquitinated ortholog, suggests that proteomics studies must be performed on neuronal cells to identify ubiquitination pathways not shared by other cell types. Importantly, several of those newly found neuronal ubiquitin substrates are key players in synaptogenesis. Mass spectrometry results were validated by Western blotting to confirm that those proteins are indeed ubiquitinated in the Drosophila embryonic nervous system and to elucidate whether they are mono- or polyubiquitinated. In addition to the ubiquitin substrates, we also identified the ubiquitin carriers that are active during synaptogenesis. Identifying endogenously ubiquitinated proteins in specific cell types, at specific developmental stages, and within the context of a living organism will allow understanding how the tissue-specific function of those proteins is regulated by the ubiquitin system.

  12. Nutritional Status and Cardiac Autophagy

    Directory of Open Access Journals (Sweden)

    Jihyun Ahn

    2013-02-01

    Full Text Available Autophagy is necessary for the degradation of long-lasting proteins and nonfunctional organelles, and is activated to promote cellular survival. However, overactivation of autophagy may deplete essential molecules and organelles responsible for cellular survival. Lifelong calorie restriction by 40% has been shown to increase the cardiac expression of autophagic markers, which suggests that it may have a cardioprotective effect by decreasing oxidative damage brought on by aging and cardiovascular diseases. Although cardiac autophagy is critical to regulating protein quality and maintaining cellular function and survival, increased or excessive autophagy may have deleterious effects on the heart under some circumstances, including pressure overload-induced heart failure. The importance of autophagy has been shown in nutrient supply and preservation of energy in times of limitation, such as ischemia. Some studies have suggested that a transition from obesity to metabolic syndrome may involve progressive changes in myocardial inflammation, mitochondrial dysfunction, fibrosis, apoptosis, and myocardial autophagy.

  13. Meiotic abnormalities

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    Chapter 19, describes meiotic abnormalities. These include nondisjunction of autosomes and sex chromosomes, genetic and environmental causes of nondisjunction, misdivision of the centromere, chromosomally abnormal human sperm, male infertility, parental age, and origin of diploid gametes. 57 refs., 2 figs., 1 tab.

  14. Posttranslational modification of autophagy-related proteins in macroautophagy.

    Science.gov (United States)

    Xie, Yangchun; Kang, Rui; Sun, Xiaofang; Zhong, Meizuo; Huang, Jin; Klionsky, Daniel J; Tang, Daolin

    2015-01-01

    Macroautophagy is an intracellular catabolic process involved in the formation of multiple membrane structures ranging from phagophores to autophagosomes and autolysosomes. Dysfunction of macroautophagy is implicated in both physiological and pathological conditions. To date, 38 autophagy-related (ATG) genes have been identified as controlling these complicated membrane dynamics during macroautophagy in yeast; approximately half of these genes are clearly conserved up to human, and there are additional genes whose products function in autophagy in higher eukaryotes that are not found in yeast. The function of the ATG proteins, in particular their ability to interact with a number of macroautophagic regulators, is modulated by posttranslational modifications (PTMs) such as phosphorylation, glycosylation, ubiquitination, acetylation, lipidation, and proteolysis. In this review, we summarize our current knowledge of the role of ATG protein PTMs and their functional relevance in macroautophagy. Unraveling how these PTMs regulate ATG protein function during macroautophagy will not only reveal fundamental mechanistic insights into the regulatory process, but also provide new therapeutic targets for the treatment of autophagy-associated diseases.

  15. Multiple sclerosis autoantigen myelin basic protein escapes control by ubiquitination during proteasomal degradation.

    Science.gov (United States)

    Belogurov, Alexey; Kudriaeva, Anna; Kuzina, Ekaterina; Smirnov, Ivan; Bobik, Tatyana; Ponomarenko, Natalia; Kravtsova-Ivantsiv, Yelena; Ciechanover, Aaron; Gabibov, Alexander

    2014-06-20

    The vast majority of cellular proteins are degraded by the 26S proteasome after their ubiquitination. Here, we report that the major component of the myelin multilayered membrane sheath, myelin basic protein (MBP), is hydrolyzed by the 26S proteasome in a ubiquitin-independent manner both in vitro and in mammalian cells. As a proteasomal substrate, MBP reveals a distinct and physiologically relevant concentration range for ubiquitin-independent proteolysis. Enzymatic deimination prevents hydrolysis of MBP by the proteasome, suggesting that an abnormally basic charge contributes to its susceptibility toward proteasome-mediated degradation. To our knowledge, our data reveal the first case of a pathophysiologically important autoantigen as a ubiquitin-independent substrate of the 26S proteasome.

  16. Autophagy in colorectal cancer:An important switch from physiology to pathology

    Institute of Scientific and Technical Information of China (English)

    Florin; Burada; Elena; Raluca; Nicoli; Marius; Eugen; Ciurea; Daniel; Constantin; Uscatu; Mihai; Ioana; Dan; Ionut; Gheonea

    2015-01-01

    Colorectal cancer(CRC) remains a leading cause of cancer death in both men and women worldwide.Among the factors and mechanisms that are involved in the multifactorial etiology of CRC,autophagy is an important transformational switch that occurs when a cell shifts from normal to malignant.In recent years,multiple hypotheses have been considered regarding the autophagy mechanisms that are involved in cancer.The currently accepted hypothesis is that autophagy has dual and contradictory roles in carcinogenesis,but the precise mechanisms leading to autophagy in cancer are not yet fully defined and seem to be context dependent.Autophagy is a surveillance mechanism used by normal cells that protects them from the transformation to malignancy by removing damaged organelles and aggregated proteins and by reducing reactive oxygen species,mitochondrial abnormalities and DNA damage.However,autophagy also supports tumor formation by promoting access to nutrients that are critical to the metabolism and growth of tumor cells and by inhibiting cellular death and increasing drug resistance.Autophagy studies in CRC have focused on several molecules,mainly microtubule-associated protein 1 light chain 3,beclin 1,and autophagy related 5,with conflicting results.Beneficial effects were observed for some agents that modulate autophagy in CRC either alone or,more often,in combination with other agents.More extensive studies are needed in the future to clarify the roles of autophagy-related genes and modulators in colorectal carcinogenesis,and to develop potential beneficial agents for the prognosis and treatment of CRC.

  17. Age-related dysfunctions of the autophagy lysosomal pathway in hippocampal pyramidal neurons under proteasome stress.

    Science.gov (United States)

    Gavilán, Elena; Pintado, Cristina; Gavilan, Maria P; Daza, Paula; Sánchez-Aguayo, Inmaculada; Castaño, Angélica; Ruano, Diego

    2015-05-01

    Autophagy plays a key role in the maintenance of cellular homeostasis, and autophagy deregulation gives rise to severe disorders. Many of the signaling pathways regulating autophagy under stress conditions are still poorly understood. Using a model of proteasome stress in rat hippocampus, we have characterized the functional crosstalk between the ubiquitin proteasome system and the autophagy-lysosome pathway, identifying also age-related modifications in the crosstalk between both proteolytic systems. Under proteasome inhibition, both autophagy activation and resolution were efficiently induced in young but not in aged rats, leading to restoration of protein homeostasis only in young pyramidal neurons. Importantly, proteasome stress inhibited glycogen synthase kinase-3β in young but activated in aged rats. This age-related difference could be because of a dysfunction in the signaling pathway of the insulin growth factor-1 under stress situations. Present data highlight the potential role of glycogen synthase kinase-3β in the coordination of both proteolytic systems under stress situation, representing a key molecular target to sort out this deleterious effect.

  18. Bcl-2-dependent upregulation of autophagy by sequestosome 1/p62 in vitro

    Institute of Scientific and Technical Information of China (English)

    Liang ZHOU; Hong-feng WANG; Hai-gang REN; Dong CHEN; Feng GAO; Qing-song HU; Chen FU

    2013-01-01

    To investigate whether sequestosome 1/p62 (p62),a key cargo adaptor protein involved in both the ubiquitin-proteasome system and the autophagy-lysosome system,could directly regulate autophagy in vitro.Methods:HEK 293 cells or HeLa cells were transfected with p62-expressing plasmids or siRNA targeting p62.The cells or the cell lysates were subsequently subjected to immunofluorescence assay,immunoprecipitation assay,or immunoblot analysis.In vitro pulldown assay was used to study the interaction of p62 with Bcl-2.Results:Overexpression of p62 significantly increased the basal level of autophagy in both HEK 293 cells and HeLa cells,whereas knockdown of p62 significantly decreased the basal level of autophagy.In vitro pulldown assay showed that p62 directly interacted with Bcl-2.It was observed in HeLa cells that p62 co-localized with Bcl-2.Furthermore,knockdown of p62 in HEK 293 cells significantly increased the amount of Beclin 1 that co-immunoprecipitated with Bcl-2.Conclusion:p62 induces autophagy by disrupting the association between Bcl-2 and Beclin 1.

  19. Relationship between autophagy and aging%细胞自噬与衰老

    Institute of Scientific and Technical Information of China (English)

    席兴字

    2011-01-01

    Aging is an intrinsic property of organism, which is characterized by the accumulation of damaged protein aggregates in cells and tissues. Clearance of protein aggregates mainly relies on ubiquitin-proteasome system and lysosome-dependent autophagy pathway.In recent years, some autophagy genes have been reported to play an important role in aging in models organisms, and these findings motivate interests in developing anti-aging drugs. This paper summarized the mechanisms of autophagy, and discussed the connections between aging and autophagy.%衰老是生物体内在的性质,细胞中损伤蛋白质积累是生物体衰老的一个重要特征.蛋门质聚集体的清除主要依赖于泛素-蛋白酶体途径和依赖溶酶体的细胞自噬(autophagy)途径.近年来,研究人员在许多模式生物中发现一些细胞自噬基因在衰老中起重要作用,这些研究激发人们利用细胞自噬开发抗衰老药物的兴趣.本文就细胞自噬的机理、衰老与自噬之间的联系等进行综述.

  20. Dynamic survey of mitochondria by ubiquitin.

    Science.gov (United States)

    Escobar-Henriques, Mafalda; Langer, Thomas

    2014-03-01

    Ubiquitin is a post-translational modifier with proteolytic and non-proteolytic roles in many biological processes. At mitochondria, it performs regulatory homeostatic functions and contributes to mitochondrial quality control. Ubiquitin is essential for mitochondrial fusion, regulates mitochondria-ER contacts, and participates in maternal mtDNA inheritance. Under stress, mitochondrial dysfunction induces ubiquitin-dependent responses that involve mitochondrial proteome remodeling and culminate in organelle removal by mitophagy. In addition, many ubiquitin-dependent mechanisms have been shown to regulate innate immune responses and xenophagy. Here, we review the emerging roles of ubiquitin at mitochondria.

  1. Autophagy: Regulation by Energy Sensing

    NARCIS (Netherlands)

    A.J. Meijer; P. Codogno

    2011-01-01

    Autophagy is inhibited by the mTOR signaling pathway, which is stimulated by increased amino acid levels. When cellular energy production is compromised, AMP-activated protein kinase is activated, mTOR is inhibited and autophagy is stimulated. Two recent studies have shed light on the molecular mech

  2. Regulation of Autophagy by Kinases

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, Savitha; Jain, Kirti; Basu, Alakananda, E-mail: alakananda.basu@unthsc.edu [Department of Molecular Biology and Immunology, Institute for Cancer Research, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States)

    2011-06-09

    Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated protein kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK) and protein kinase C that are often deregulated in cancer and are important therapeutic targets.

  3. Neuronal autophagy in cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    Feng Xu; Jin-Hua Gu; Zheng-Hong Qin

    2012-01-01

    Autophagy has evolved as a conserved process for the bulk degradation and recycling of cytosolic components,such as long-lived proteins and organelles.In neurons,autophagy is important for homeostasis and protein quality control and is maintained at relatively low levels under normal conditions,while it is upregulated in response to pathophysiological conditions,such as cerebral ischemic injury.However,the role of autophagy is more complex.It depends on age or brain maturity,region,severity of insult,and the stage of ischemia.Whether autophagy plays a beneficial or a detrimental role in cerebral ischemia depends on various pathological conditions.In this review,we elucidate the role of neuronal autophagy in cerebral ischemia.

  4. Role and regulation of autophagy in heat stress responses of tomato plants.

    Science.gov (United States)

    Zhou, Jie; Wang, Jian; Yu, Jing-Quan; Chen, Zhixiang

    2014-01-01

    As sessile organisms, plants are constantly exposed to a wide spectrum of stress conditions such as high temperature, which causes protein misfolding. Misfolded proteins are highly toxic and must be efficiently removed to reduce cellular proteotoxic stress if restoration of native conformations is unsuccessful. Although selective autophagy is known to function in protein quality control by targeting degradation of misfolded and potentially toxic proteins, its role and regulation in heat stress responses have not been analyzed in crop plants. In the present study, we found that heat stress induced expression of autophagy-related (ATG) genes and accumulation of autophagosomes in tomato plants. Virus-induced gene silencing (VIGS) of tomato ATG5 and ATG7 genes resulted in increased sensitivity of tomato plants to heat stress based on both increased development of heat stress symptoms and compromised photosynthetic parameters of heat-stressed leaf tissues. Silencing of tomato homologs for the selective autophagy receptor NBR1, which targets ubiquitinated protein aggregates, also compromised tomato heat tolerance. To better understand the regulation of heat-induced autophagy, we found that silencing of tomato ATG5, ATG7, or NBR1 compromised heat-induced expression of not only the targeted genes but also other autophagy-related genes. Furthermore, we identified two tomato genes encoding proteins highly homologous to Arabidopsis WRKY33 transcription factor, which has been previously shown to interact physically with an autophagy protein. Silencing of tomato WRKY33 genes compromised tomato heat tolerance and reduced heat-induced ATG gene expression and autophagosome accumulation. Based on these results, we propose that heat-induced autophagy in tomato is subject to cooperative regulation by both WRKY33 and ATG proteins and plays a critical role in tomato heat tolerance, mostly likely through selective removal of heat-induced protein aggregates.

  5. Systematic cloning and analysis of autophagy-related genes from the silkworm Bombyx mori

    Directory of Open Access Journals (Sweden)

    Cao Yang

    2009-05-01

    Full Text Available Abstract Background Through the whole life of eukaryotes, autophagy plays an important role in various biological events including development, differentiation and determination of lifespan. A full set of genes and their encoded proteins of this evolutionarily conserved pathway have been identified in many eukaryotic organisms from yeast to mammals. However, this pathway in the insect model organism, the silkworm Bombyx mori, remains poorly investigated. Results Based on the autophagy pathway in several model organisms and a series of bioinformatic analyses, we have found more than 20 autophagy-related genes from the current database of the silkworm Bombyx mori. These genes could be further classified into the signal transduction pathway and two ubiquitin-like pathways. Using the mRNA extracted from the silkgland, we cloned the full length cDNA fragments of some key genes via reverse transcription PCR and 3' rapid amplification of cDNA ends (RACE. In addition, we found that the transcription levels of two indicator genes BmATG8 and BmATG12 in the silkgland tend to be increased from 1st to 8th day of the fifth instar larvae. Conclusion Bioinformatics in combination with RT-PCR enable us to remodel a preliminary pathway of autophagy in the silkworm. Amplification and cloning of most autophagy-related genes from the silkgland indicated autophagy is indeed an activated process. Furthermore, the time-course transcriptional profiles of BmATG8 and BmATG12 revealed that both genes are up-regulated along the maturation of the silkgland during the fifth instar. These findings suggest that the autophagy should play an important role in Bombyx mori silkgland.

  6. Role and Regulation of Autophagy in Heat Stress Responses of Tomato Plants

    Directory of Open Access Journals (Sweden)

    Jie eZhou

    2014-04-01

    Full Text Available As sessile organisms, plants are constantly exposed to a wide spectrum of stress conditions such as high temperature, which causes protein misfolding. Misfolded proteins are highly toxic and must be efficiently removed to reduce cellular proteotoxic stress if restoration of native conformations is unsuccessful. Although selective autophagy is known to function in protein quality control by targeting degradation of misfolded and potentially toxic proteins, its role and regulation in heat stress responses have not been analyzed in crop plants. In the present study, we found that heat stress induced expression of autophagy-related (ATG genes and accumulation of autophagosomes in tomato plants. Virus-induced gene silencing of tomato ATG5 and ATG7 genes resulted in increased sensitivity of tomato plants to heat stress based on both increased development of heat stress symptoms and compromised photosynthetic parameters of heat-stressed leaf tissues. Silencing of tomato homologs for the selective autophagy receptor NBR1, which targets ubiquitinated protein aggregates, also compromised tomato heat tolerance. To better understand the regulation of heat-induced autophagy, we found that silencing of tomato ATG5, ATG7 or NBR1 compromised heat-induced expression of not only the targeted genes but also other autophagy-related genes. Furthermore, we identified two tomato genes encoding proteins highly homologous to Arabidopsis WRKY33 transcription factor, which has been previously shown to interact physically with an autophagy protein. Silencing of tomato WRKY33 genes compromised tomato heat tolerance and reduced heat-induced ATG gene expression and autophagosome accumulation. Based on these results, we propose that heat-induced autophagy in tomato is subject to cooperative regulation by both WRKY33 and ATG proteins and plays a critical role in tomato heat tolerance, mostly likely through selective removal of heat-induced protein aggregates.

  7. Simultaneous activation of mitophagy and autophagy by staurosporine protects against dopaminergic neuronal cell death.

    Science.gov (United States)

    Ha, Ji-Young; Kim, Ji-Soo; Kim, Seo-Eun; Son, Jin H

    2014-02-21

    Abnormal autophagy is frequently observed during dopaminergic neurodegeneration in Parkinson's disease (PD). However, it is not yet firmly established whether active autophagy is beneficial or pathogenic with respect to dopaminergic cell loss. Staurosporine, a common inducer of apoptosis, is often used in mechanistic studies of dopaminergic cell death. Here we report that staurosporine activates both autophagy and mitophagy simultaneously during dopaminergic neuronal cell death, and evaluate the physiological significance of these processes during cell death. First, staurosporine treatment resulted in induction of autophagy in more than 75% of apoptotic cells. Pharmacological inhibition of autophagy by bafilomycin A1 decreased significantly cell viability. In addition, staurosporine treatment resulted in activation of the PINK1-Parkin mitophagy pathway, of which deficit underlies some familial cases of PD, in the dopaminergic neuronal cell line, SN4741. The genetic blockade of this pathway by PINK1 null mutation also dramatically increased staurosporine-induced cell death. Taken together, our data suggest that staurosporine induces both mitophagy and autophagy, and that these pathways exert a significant neuroprotective effect, rather than a contribution to autophagic cell death. This model system may therefore be useful for elucidating the mechanisms underlying crosstalk between autophagy, mitophagy, and cell death in dopaminergic neurons.

  8. K63-Linked Ubiquitination Targets Toxoplasma gondii for Endo-lysosomal Destruction in IFNγ-Stimulated Human Cells

    Science.gov (United States)

    Clough, Barbara; Wright, Joseph D.; Pereira, Pedro M.; Johnston, Ashleigh C.; Frickel, Eva-Maria

    2016-01-01

    Toxoplasma gondii is the most common protozoan parasitic infection in man. Gamma interferon (IFNγ) activates haematopoietic and non-haematopoietic cells to kill the parasite and mediate host resistance. IFNγ-driven host resistance pathways and parasitic virulence factors are well described in mice, but a detailed understanding of pathways that kill Toxoplasma in human cells is lacking. Here we show, that contrary to the widely held belief that the Toxoplasma vacuole is non-fusogenic, in an immune-stimulated environment, the vacuole of type II Toxoplasma in human cells is able to fuse with the host endo-lysosomal machinery leading to parasite death by acidification. Similar to murine cells, we find that type II, but not type I Toxoplasma vacuoles are targeted by K63-linked ubiquitin in an IFNγ-dependent manner in non-haematopoetic primary-like human endothelial cells. Host defence proteins p62 and NDP52 are subsequently recruited to the type II vacuole in distinct, overlapping microdomains with a loss of IFNγ-dependent restriction in p62 knocked down cells. Autophagy proteins Atg16L1, GABARAP and LC3B are recruited to <10% of parasite vacuoles and show no parasite strain preference, which is consistent with inhibition and enhancement of autophagy showing no effect on parasite replication. We demonstrate that this differs from HeLa human epithelial cells, where type II Toxoplasma are restricted by non-canonical autophagy leading to growth stunting that is independent of lysosomal acidification. In contrast to mouse cells, human vacuoles do not break. In HUVEC, the ubiquitinated vacuoles are targeted for destruction in acidified LAMP1-positive endo-lysosomal compartments. Consequently, parasite death can be prevented by inhibiting host ubiquitination and endosomal acidification. Thus, K63-linked ubiquitin recognition leading to vacuolar endo-lysosomal fusion and acidification is an important, novel virulence-driven Toxoplasma human host defence pathway. PMID

  9. Mouse Sirt3 promotes autophagy in AngII-induced myocardial hypertrophy through the deacetylation of FoxO1

    Science.gov (United States)

    Li, Jingyuan; Chen, Tongshuai; Xiao, Ming; Li, Na; Wang, Shujian; Su, Hongyan; Guo, Xiaobin; Liu, Hui; Yan, Fangying; Yang, Yi; Zhang, Yun; Bu, Peili

    2016-01-01

    Sirt3, a mitochondrial NAD+-dependent histone deacetylase, is the only member proven to promote longevity in mammalian Sirtuin family. The processed short form of Sirt3 has been demonstrated to target many mediators of energy metabolism and mitochondrial stress adaptive program. Autophagy serves as a dynamic recycling mechanism and provides energy or metabolic substrates. Among the mechanisms triggered by cardiac stress, opinions vary as to whether autophagy is a protective or detrimental response. Here, by inducing the Sirt3-knockout mice to myocardial hypertrophy with chronic angiotensin II infusion for four weeks, we determined the role of Sirt3 in myocardial hypertrophy and autophagy. In this study, the Sirt3-knockout mice developed deteriorated cardiac function and impaired autophagy compared to wild-type mice. What's more, the overexpression of Sirt3 by lentivirus transfection attenuated cardiomyocytes hypertrophy by promoting autophagy. We further demonstrated that Sirt3 could bind to FoxO1 and activate its deacetylation. Sequentially, deacetylated FoxO1 translocates to the nucleus where it facilitates downstream E3 ubiquitin ligases such as Muscle RING Finger 1 (MuRF1) and muscle atrophy F-box (MAFbx, Atrogin1). Altogether, these results revealed that Sirt3 activation is essential to improve autophagy flux by reducing the acetylation modification on FoxO1, which in turn alleviates myocardial hypertrophy. PMID:27880725

  10. Autophagy and neurodegenerative disorders

    Institute of Scientific and Technical Information of China (English)

    Evangelia Kesidou; Roza Lagoudaki; Olga Touloumi; Kyriaki-Nefeli Poulatsidou; Constantina Simeonidou

    2013-01-01

    Accumulation of aberrant proteins and inclusion bodies are hallmarks in most neurodegenerative diseases. Consequently, these aggregates within neurons lead to toxic effects, overproduction of reactive oxygen species and oxidative stress. Autophagy is a significant intracel ular mechanism that removes damaged organelles and misfolded proteins in order to maintain cel homeostasis. Excessive or insufficient autophagic activity in neurons leads to altered homeostasis and influences their survival rate, causing neurodegeneration. The review article provides an update of the role of autophagic process in representative chronic and acute neurodegenerative disorders.

  11. Allosteric regulation of deubiquitylase activity through ubiquitination

    Directory of Open Access Journals (Sweden)

    Serena eFaggiano

    2015-02-01

    Full Text Available Ataxin-3, the protein responsible for spinocerebellar ataxia type-3, is a cysteine protease that specifically cleaves poly-ubiquitin chains and participates in the ubiquitin proteasome pathway. The enzymatic activity resides in the N-terminal Josephin domain. An unusual feature of ataxin-3 is its low enzymatic activity especially for mono-ubiquitinated substrates and short ubiquitin chains. However, specific ubiquitination at lysine 117 in the Josephin domain activates ataxin-3 through an unknown mechanism. Here, we investigate the effects of K117 ubiquitination on the structure and enzymatic activity of the protein. We show that covalently linked ubiquitin rests on the Josephin domain, forming a compact globular moiety and occupying a ubiquitin binding site previously thought to be essential for substrate recognition. In doing so, ubiquitination enhances enzymatic activity by locking the enzyme in an activated state. Our results indicate that ubiquitin functions both as a substrate and as an allosteric regulatory factor. We provide a novel example in which a conformational switch controls the activity of an enzyme that mediates deubiquitination.

  12. Autophagy regulates chlorpyrifos-induced apoptosis in SH-SY5Y cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Hyeon [Department of Pharmacology, College of Medicine, Hanyang University (Korea, Republic of); Hanyang Biomedical Research Institute, Seoul (Korea, Republic of); Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul (Korea, Republic of); Lee, Jeong Eun [Department of Pharmacology, College of Medicine, Hanyang University (Korea, Republic of); Hanyang Biomedical Research Institute, Seoul (Korea, Republic of); Shin, In Chul [Department of Pharmacology, College of Medicine, Hanyang University (Korea, Republic of); Koh, Hyun Chul, E-mail: hckoh@hanyang.ac.kr [Department of Pharmacology, College of Medicine, Hanyang University (Korea, Republic of); Hanyang Biomedical Research Institute, Seoul (Korea, Republic of); Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul (Korea, Republic of)

    2013-04-01

    Recent studies have shown that up-regulation of autophagy may be a tractable therapeutic intervention for clearing disease-causing proteins, including α-synuclein, ubiquitin, and other misfolded or aggregated proteins in pesticide-induced neurodegeneration. In a previous study, we reported that chlorpyrifos (CPF)-induced mitochondria-dependent apoptosis is mediated through reactive oxygen species in SH-SY5Y cells. In this study, we explored a novel pharmacotherapeutic approach to prevent CPF neurotoxicity involving the regulation of autophagy. We investigated the modulation of CPF-induced apoptosis according to autophagy regulation. We found that CPF induced apoptosis in SH-SY5Y cells, as demonstrated by the activation of caspase-3 and nuclear condensation. In addition, we observed that cells treated with CPF underwent autophagic cell death by monitoring the expression of LC3-II and p62. Pretreatment with the autophagy inducer rapamycin significantly enhanced the cell viability of CPF-exposed cells, and the enhancement of cell viability was partially due to alleviation of CPF-induced apoptosis via a decrease in levels of cleaved caspase-3. Specifically, rapamycin pretreatment decreased Bax and increased Bcl-2 expression in mitochondria. In addition, rapamycin significantly decreased cytochrome c release in from mitochondria into the cytosol. However, pretreatment of cells with the autophagy inhibitor, 3-methyladenine (3MA), remarkably increased CPF toxicity in these cells; this with correlated with increased expression of Bax and decreased expression of Bcl-2 in mitochondria. Our results suggest that CPF-induced cytotoxicity is modified by autophagy regulation and that rapamycin protects against CPF-induced apoptosis by enhancing autophagy. Pharmacologic induction of autophagy by rapamycin may be a useful treatment strategy in neurodegenerative disorders. - Highlights: ► Chlorpyrifos (CPF) is cytotoxic to SH-SY5Y cells ► CPF-induced cytotoxicity is mediated by

  13. Non-degradative Ubiquitination of Protein Kinases.

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    K Aurelia Ball

    2016-06-01

    Full Text Available Growing evidence supports other regulatory roles for protein ubiquitination in addition to serving as a tag for proteasomal degradation. In contrast to other common post-translational modifications, such as phosphorylation, little is known about how non-degradative ubiquitination modulates protein structure, dynamics, and function. Due to the wealth of knowledge concerning protein kinase structure and regulation, we examined kinase ubiquitination using ubiquitin remnant immunoaffinity enrichment and quantitative mass spectrometry to identify ubiquitinated kinases and the sites of ubiquitination in Jurkat and HEK293 cells. We find that, unlike phosphorylation, ubiquitination most commonly occurs in structured domains, and on the kinase domain, ubiquitination is concentrated in regions known to be important for regulating activity. We hypothesized that ubiquitination, like other post-translational modifications, may alter the conformational equilibrium of the modified protein. We chose one human kinase, ZAP-70, to simulate using molecular dynamics with and without a monoubiquitin modification. In Jurkat cells, ZAP-70 is ubiquitinated at several sites that are not sensitive to proteasome inhibition and thus may have other regulatory roles. Our simulations show that ubiquitination influences the conformational ensemble of ZAP-70 in a site-dependent manner. When monoubiquitinated at K377, near the C-helix, the active conformation of the ZAP-70 C-helix is disrupted. In contrast, when monoubiquitinated at K476, near the kinase hinge region, an active-like ZAP-70 C-helix conformation is stabilized. These results lead to testable hypotheses that ubiquitination directly modulates kinase activity, and that ubiquitination is likely to alter structure, dynamics, and function in other protein classes as well.

  14. Non-degradative Ubiquitination of Protein Kinases.

    Science.gov (United States)

    Ball, K Aurelia; Johnson, Jeffrey R; Lewinski, Mary K; Guatelli, John; Verschueren, Erik; Krogan, Nevan J; Jacobson, Matthew P

    2016-06-01

    Growing evidence supports other regulatory roles for protein ubiquitination in addition to serving as a tag for proteasomal degradation. In contrast to other common post-translational modifications, such as phosphorylation, little is known about how non-degradative ubiquitination modulates protein structure, dynamics, and function. Due to the wealth of knowledge concerning protein kinase structure and regulation, we examined kinase ubiquitination using ubiquitin remnant immunoaffinity enrichment and quantitative mass spectrometry to identify ubiquitinated kinases and the sites of ubiquitination in Jurkat and HEK293 cells. We find that, unlike phosphorylation, ubiquitination most commonly occurs in structured domains, and on the kinase domain, ubiquitination is concentrated in regions known to be important for regulating activity. We hypothesized that ubiquitination, like other post-translational modifications, may alter the conformational equilibrium of the modified protein. We chose one human kinase, ZAP-70, to simulate using molecular dynamics with and without a monoubiquitin modification. In Jurkat cells, ZAP-70 is ubiquitinated at several sites that are not sensitive to proteasome inhibition and thus may have other regulatory roles. Our simulations show that ubiquitination influences the conformational ensemble of ZAP-70 in a site-dependent manner. When monoubiquitinated at K377, near the C-helix, the active conformation of the ZAP-70 C-helix is disrupted. In contrast, when monoubiquitinated at K476, near the kinase hinge region, an active-like ZAP-70 C-helix conformation is stabilized. These results lead to testable hypotheses that ubiquitination directly modulates kinase activity, and that ubiquitination is likely to alter structure, dynamics, and function in other protein classes as well.

  15. Retinoid receptor signaling and autophagy in acute promyelocytic leukemia.

    LENUS (Irish Health Repository)

    Orfali, Nina

    2014-05-15

    Retinoids are a family of signaling molecules derived from vitamin A with well established roles in cellular differentiation. Physiologically active retinoids mediate transcriptional effects on cells through interactions with retinoic acid (RARs) and retinoid-X (RXR) receptors. Chromosomal translocations involving the RARα gene, which lead to impaired retinoid signaling, are implicated in acute promyelocytic leukemia (APL). All-trans-retinoic acid (ATRA), alone and in combination with arsenic trioxide (ATO), restores differentiation in APL cells and promotes degradation of the abnormal oncogenic fusion protein through several proteolytic mechanisms. RARα fusion-protein elimination is emerging as critical to obtaining sustained remission and long-term cure in APL. Autophagy is a degradative cellular pathway involved in protein turnover. Both ATRA and ATO also induce autophagy in APL cells. Enhancing autophagy may therefore be of therapeutic benefit in resistant APL and could broaden the application of differentiation therapy to other cancers. Here we discuss retinoid signaling in hematopoiesis, leukemogenesis, and APL treatment. We highlight autophagy as a potential important regulator in anti-leukemic strategies.

  16. Ciliary/Flagellar Protein Ubiquitination

    OpenAIRE

    Huan Long; Qiyu Wang; Kaiyao Huang

    2015-01-01

    Cilia/flagella are conserved eukaryotic organelles that play an important role in the control of cell motility and detection of environmental cues. However, the molecular mechanisms underlying ciliary/flagellar assembly, maintenance, disassembly, and signal transduction are not yet completely understood. Recent studies demonstrated that post-translational modifications (PTMs) such as phosphorylation, methylation, glutamylation, and ubiquitination are involved in these processes. In this mini ...

  17. Leukocyte abnormalities.

    Science.gov (United States)

    Gabig, T G

    1980-07-01

    Certain qualitative abnormalities in neutrophils and blood monocytes are associated with frequent, severe, and recurrent bacterial infections leading to fatal sepsis, while other qualitative defects demonstrated in vitro may have few or no clinical sequelae. These qualitative defects are discussed in terms of the specific functions of locomotion, phagocytosis, degranulation, and bacterial killing.

  18. Induction of autophagy by Imatinib sequesters Bcr-Abl in autophagosomes and down-regulates Bcr-Abl protein.

    LENUS (Irish Health Repository)

    Elzinga, Baukje M

    2013-06-01

    Chronic Myeloid Leukemia (CML) is a disease of hematopoietic stem cells which harbor the chimeric gene Bcr-Abl. Expression levels of this constitutively active tyrosine kinase are critical for response to tyrosine kinase inhibitor treatment and also disease progression, yet the regulation of protein stability is poorly understood. We have previously demonstrated that imatinib can induce autophagy in Bcr-Abl expressing cells. Autophagy has been associated with the clearance of large macromolecular signaling complexes and abnormal proteins, however, the contribution of autophagy to the turnover of Bcr-Abl protein in imatinib treated cells is unknown. In this study, we show that following imatinib treatment, Bcr-Abl is sequestered into vesicular structures that co-localize with the autophagy marker LC3 or GABARAP. This association is inhibited by siRNA mediated knockdown of autophagy regulators (Beclin 1\\/ATG7). Pharmacological inhibition of autophagy also reduced Bcr-Abl\\/LC3 co-localization in both K562 and CML patient cells. Bcr-Abl protein expression was reduced with imatinib treatment. Inhibition of both autophagy and proteasome activity in imatinib treated cells was required to restore Bcr-Abl protein levels to those of untreated cells. This ability to down-regulate Bcr-Abl protein levels through the induction of autophagy may be an additional and important feature of the activity of imatinib.

  19. Defective Autophagy Initiates Malignant Transformation.

    Science.gov (United States)

    Galluzzi, Lorenzo; Bravo-San Pedro, José Manuel; Kroemer, Guido

    2016-05-19

    In this issue of Molecular Cell, Park et al. (2016) elegantly demonstrate that a partial defect in autophagy supports malignant transformation as it favors the production of genotoxic reactive oxygen species by mitochondria.

  20. Rapamycin and chloroquine: the in vitro and in vivo effects of autophagy-modifying drugs show promising results in valosin containing protein multisystem proteinopathy.

    Directory of Open Access Journals (Sweden)

    Angèle Nalbandian

    Full Text Available Mutations in the valosin containing protein (VCP gene cause hereditary Inclusion body myopathy (hIBM associated with Paget disease of bone (PDB, frontotemporal dementia (FTD, more recently termed multisystem proteinopathy (MSP. Affected individuals exhibit scapular winging and die from progressive muscle weakness, and cardiac and respiratory failure, typically in their 40s to 50s. Histologically, patients show the presence of rimmed vacuoles and TAR DNA-binding protein 43 (TDP-43-positive large ubiquitinated inclusion bodies in the muscles. We have generated a VCPR155H/+ mouse model which recapitulates the disease phenotype and impaired autophagy typically observed in patients with VCP disease. Autophagy-modifying agents, such as rapamycin and chloroquine, at pharmacological doses have previously shown to alter the autophagic flux. Herein, we report results of administration of rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR signaling pathway, and chloroquine, a lysosomal inhibitor which reverses autophagy by accumulating in lysosomes, responsible for blocking autophagy in 20-month old VCPR155H/+ mice. Rapamycin-treated mice demonstrated significant improvement in muscle performance, quadriceps histological analysis, and rescue of ubiquitin, and TDP-43 pathology and defective autophagy as indicated by decreased protein expression levels of LC3-I/II, p62/SQSTM1, optineurin and inhibiting the mTORC1 substrates. Conversely, chloroquine-treated VCPR155H/+ mice revealed progressive muscle weakness, cytoplasmic accumulation of TDP-43, ubiquitin-positive inclusion bodies and increased LC3-I/II, p62/SQSTM1, and optineurin expression levels. Our in vitro patient myoblasts studies treated with rapamycin demonstrated an overall improvement in the autophagy markers. Targeting the mTOR pathway ameliorates an increasing list of disorders, and these findings suggest that VCP disease and related neurodegenerative multisystem

  1. Pompe Disease and Autophagy : Partners in Crime, or Cause and Consequence?

    NARCIS (Netherlands)

    Rodriguez-Arribas, M.; Bravo-San Pedro, J. M.; Gomez-Sanchez, R.; Yakhine-Diop, S. M. S.; Martinez-Chacon, G.; Uribe-Carretero, E.; Pinheiro De Castro, D. C. J.; Casado-Naranjo, I.; Lopez de Munain, A.; Niso-Santano, M.; Fuentes, J. M.; Gonzalez-Polo, R. A.

    2016-01-01

    Pompe disease or glycogen storage disease type II (OMIM: 232300) is a lysosomal storage disorder resulting from a partial or total lack of acid alphaglucosidase, which may produce muscle weakness, gait abnormalities, or even death by respiratory failure. In the last decade, autophagy has been propos

  2. Macrophage Autophagy in Atherosclerosis

    Directory of Open Access Journals (Sweden)

    Maria Chiara Maiuri

    2013-01-01

    Full Text Available Macrophages play crucial roles in atherosclerotic immune responses. Recent investigation into macrophage autophagy (AP in atherosclerosis has demonstrated a novel pathway through which these cells contribute to vascular inflammation. AP is a cellular catabolic process involving the delivery of cytoplasmic contents to the lysosomal machinery for ultimate degradation and recycling. Basal levels of macrophage AP play an essential role in atheroprotection during early atherosclerosis. However, AP becomes dysfunctional in the more advanced stages of the pathology and its deficiency promotes vascular inflammation, oxidative stress, and plaque necrosis. In this paper, we will discuss the role of macrophages and AP in atherosclerosis and the emerging evidence demonstrating the contribution of macrophage AP to vascular pathology. Finally, we will discuss how AP could be targeted for therapeutic utility.

  3. The autophagy gene Wdr45/Wipi4 regulates learning and memory function and axonal homeostasis.

    Science.gov (United States)

    Zhao, Yan G; Sun, Le; Miao, Guangyan; Ji, Cuicui; Zhao, Hongyu; Sun, Huayu; Miao, Lin; Yoshii, Saori R; Mizushima, Noboru; Wang, Xiaoqun; Zhang, Hong

    2015-01-01

    WDR45/WIPI4, encoding a WD40 repeat-containing PtdIns(3)P binding protein, is essential for the basal autophagy pathway. Mutations in WDR45 cause the neurodegenerative disease β-propeller protein-associated neurodegeneration (BPAN), a subtype of NBIA. We generated CNS-specific Wdr45 knockout mice, which exhibit poor motor coordination, greatly impaired learning and memory, and extensive axon swelling with numerous axon spheroids. Autophagic flux is defective and SQSTM1 (sequestosome-1)/p62 and ubiquitin-positive protein aggregates accumulate in neurons and swollen axons. Nes-Wdr45(fl/Y) mice recapitulate some hallmarks of BPAN, including cognitive impairment and defective axonal homeostasis, providing a model for revealing the disease pathogenesis of BPAN and also for investigating the possible role of autophagy in axon maintenance.

  4. Induction of genomic instability and activation of autophagy in artificial human aneuploid cells

    Energy Technology Data Exchange (ETDEWEB)

    Ariyoshi, Kentaro [Hirosaki University, Institute of Radiation Emergency Medicine, 66-1 Hon-cho, Hirosaki 036-8564 (Japan); Miura, Tomisato; Kasai, Kosuke; Fujishima, Yohei [Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki 036-8564 (Japan); Oshimura, Mitsuo [Chromosome Engineering Research Center (CERC), Tottori University, Nishicho 86, Yonago, Tottori 683-8503 (Japan); Yoshida, Mitsuaki A., E-mail: ariyoshi@hirosaki-u.ac.jp [Hirosaki University, Institute of Radiation Emergency Medicine, 66-1 Hon-cho, Hirosaki 036-8564 (Japan)

    2016-08-15

    Highlights: • Clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. • Increased autophagy was observed in the artificially aneuploid clones. • Inhibition of autophagy resulted in increased genomic instability and DNA damage. • Intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones. - Abstract: Chromosome missegregation can lead to a change in chromosome number known as aneuploidy. Although aneuploidy is a known hallmark of cancer cells, the various mechanisms by which altered gene and/or DNA copy number facilitate tumorigenesis remain unclear. To understand the effect of aneuploidy occurring in non-tumorigenic human breast epithelial cells, we generated clones harboring artificial aneuploidy using microcell-mediated chromosome transfer. Our results demonstrate that clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. Also, the increased autophagy was observed in the artificially aneuploidy clones, and inhibition of autophagy resulted in increased genomic instability and DNA damage. In addition, the intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones, and inhibition of autophagy further increased the production of reactive oxygen species. Together, these results suggest that even a single extraneous chromosome can induce genomic instability, and that autophagy triggered by aneuploidy-induced stress is a mechanism to protect cells bearing abnormal chromosome number.

  5. Fluorescence microscopy: A tool to study autophagy

    Science.gov (United States)

    Rai, Shashank; Manjithaya, Ravi

    2015-08-01

    Autophagy is a cellular recycling process through which a cell degrades old and damaged cellular components such as organelles and proteins and the degradation products are reused to provide energy and building blocks. Dysfunctional autophagy is reported in several pathological situations. Hence, autophagy plays an important role in both cellular homeostasis and diseased conditions. Autophagy can be studied through various techniques including fluorescence based microscopy. With the advancements of newer technologies in fluorescence microscopy, several novel processes of autophagy have been discovered which makes it an essential tool for autophagy research. Moreover, ability to tag fluorescent proteins with sub cellular targets has enabled us to evaluate autophagy processes in real time under fluorescent microscope. In this article, we demonstrate different aspects of autophagy in two different model organisms i.e. yeast and mammalian cells, with the help of fluorescence microscopy.

  6. Interactions between Autophagy and Inhibitory Cytokines.

    Science.gov (United States)

    Wu, Tian-Tian; Li, Wei-Min; Yao, Yong-Ming

    2016-01-01

    Autophagy is a degradative pathway that plays an essential role in maintaining cellular homeostasis. Most early studies of autophagy focused on its involvement in age-associated degeneration and nutrient deprivation. However, the immunological functions of autophagy have become more widely studied in recent years. Autophagy has been shown to be an intrinsic cellular defense mechanism in the innate and adaptive immune responses. Cytokines belong to a broad and loose category of proteins and are crucial for innate and adaptive immunity. Inhibitory cytokines have evolved to permit tolerance to self while also contributing to the eradication of invading pathogens. Interactions between inhibitory cytokines and autophagy have recently been reported, revealing a novel mechanism by which autophagy controls the immune response. In this review, we discuss interactions between autophagy and the regulatory cytokines IL-10, transforming growth factor-β, and IL-27. We also mention possible interactions between two newly discovered cytokines, IL-35 and IL-37, and autophagy.

  7. Autophagy and apoptosis: rivals or mates?

    Institute of Scientific and Technical Information of China (English)

    Yan Cheng; Jin-Ming Yang

    2013-01-01

    Autophagy,a cellular process of "self-eating" by which intracellular components are degraded within the lysosome,is an evolutionarily conserved response to various stresses.Autophagy is associated with numerous patho-physiological conditions,and dysregulation of autophagy contributes to the pathogenesis of a variety of human diseases including cancer.Depending on context,activation of autophagy may promote either cell survival or death,two major events that determine pathological process of many illnesses.Importantly,the activity of autophagy is often associated with apoptosis,another critical cellular process determining cellular fate.A better understanding of biology of autophagy and its implication in human health and disorder,as well as the relationship between autophagy and apoptosis,has the potential of facilitating the development of autophagy-based therapeutic interventions for human diseases such as cancer.

  8. Interactions between Autophagy and Inhibitory Cytokines

    Science.gov (United States)

    Wu, Tian-tian; Li, Wei-Min; Yao, Yong-Ming

    2016-01-01

    Autophagy is a degradative pathway that plays an essential role in maintaining cellular homeostasis. Most early studies of autophagy focused on its involvement in age-associated degeneration and nutrient deprivation. However, the immunological functions of autophagy have become more widely studied in recent years. Autophagy has been shown to be an intrinsic cellular defense mechanism in the innate and adaptive immune responses. Cytokines belong to a broad and loose category of proteins and are crucial for innate and adaptive immunity. Inhibitory cytokines have evolved to permit tolerance to self while also contributing to the eradication of invading pathogens. Interactions between inhibitory cytokines and autophagy have recently been reported, revealing a novel mechanism by which autophagy controls the immune response. In this review, we discuss interactions between autophagy and the regulatory cytokines IL-10, transforming growth factor-β, and IL-27. We also mention possible interactions between two newly discovered cytokines, IL-35 and IL-37, and autophagy. PMID:27313501

  9. Histone deacetylases 1 and 2 regulate autophagy flux and skeletal muscle homeostasis in mice

    Science.gov (United States)

    Moresi, Viviana; Carrer, Michele; Grueter, Chad E.; Rifki, Oktay F.; Shelton, John M.; Richardson, James A.; Bassel-Duby, Rhonda; Olson, Eric N.

    2012-01-01

    Maintenance of skeletal muscle structure and function requires efficient and precise metabolic control. Autophagy plays a key role in metabolic homeostasis of diverse tissues by recycling cellular constituents, particularly under conditions of caloric restriction, thereby normalizing cellular metabolism. Here we show that histone deacetylases (HDACs) 1 and 2 control skeletal muscle homeostasis and autophagy flux in mice. Skeletal muscle-specific deletion of both HDAC1 and HDAC2 results in perinatal lethality of a subset of mice, accompanied by mitochondrial abnormalities and sarcomere degeneration. Mutant mice that survive the first day of life develop a progressive myopathy characterized by muscle degeneration and regeneration, and abnormal metabolism resulting from a blockade to autophagy. HDAC1 and HDAC2 regulate skeletal muscle autophagy by mediating the induction of autophagic gene expression and the formation of autophagosomes, such that myofibers of mice lacking these HDACs accumulate toxic autophagic intermediates. Strikingly, feeding HDAC1/2 mutant mice a high-fat diet from the weaning age releases the block in autophagy and prevents myopathy in adult mice. These findings reveal an unprecedented and essential role for HDAC1 and HDAC2 in maintenance of skeletal muscle structure and function and show that, at least in some pathological conditions, myopathy may be mitigated by dietary modifications. PMID:22307625

  10. Adaptive changes in autophagy after UPS impairment in Parkinson's disease

    Institute of Scientific and Technical Information of China (English)

    Yu-fei SHEN; Yu TANG; Xiao-jie ZHANG; Kai-xing HUANG; Wei-dong LE

    2013-01-01

    Ubiquitin-proteasome system (UPS) and autophagosome-lysosome pathway (ALP) are the most important machineries responsible for protein degradation in Parkinson's disease (PD).The aim of this study is to investigate the adaptive alterations in autophagy upon proteasome inhibition in dopaminergic neurons in vitro and in vivo.Methods:Human dopaminergic neuroblastoma SH-SY5Y cells were treated with the proteasome inhibitor lactacystin (5 pmol/L) for 5,12,or 24 h.The expression of autophagy-related proteins in the cells was detected with immunoblotting.UPS-impaired mouse model of PD was established by microinjection of lactacystin (2 pg) into the left hemisphere of C57BL/6 mice that were sacrificed 2 or 4weeks later.The midbrain tissues were dissected to assess alterations in autophagy using immunofluorescence,immunoblotting and electron microscopy assays.Results:Both in SH-SY5Y cells and in the midbrain of UPS-impaired mouse model of PD,treatment with lactacystin significantly increased the expression levels of LC3-Ⅰ/Ⅱ and Beclin 1,and reduced the levels of p-mTOR,mTOR and p62/SQSTM1.Furthermore,lactacystin treatment in UPS-impaired mouse model of PD caused significant loss of TH-positive neurons in the substantia nigra,and dramatically increased the number of autophagosomes in the left TH-positive neurons.Conclusion:Inhibition of UPS by lactacystin in dopaminergic neurons activates another protein degradation system,the ALP,which includes both the mTOR signaling pathway and Beclin 1-associated pathway.

  11. Autophagy and mitophagy in cellular damage control

    Directory of Open Access Journals (Sweden)

    Jianhua Zhang

    2013-01-01

    Full Text Available Autophagy and mitophagy are important cellular processes that are responsible for breaking down cellular contents, preserving energy and safeguarding against accumulation of damaged and aggregated biomolecules. This graphic review gives a broad summary of autophagy and discusses examples where autophagy is important in controlling protein degradation. In addition we highlight how autophagy and mitophagy are involved in the cellular responses to reactive species and mitochondrial dysfunction. The key signaling pathways for mitophagy are described in the context of bioenergetic dysfunction.

  12. Crystal Structure of Oxidative Stress Sensor Keap1 in Complex with Selective Autophagy Substrate p62

    Science.gov (United States)

    Kurokawa, Hirofumi

    Keap1, an adaptor protein of cullin-RING ubiquitin ligase complex, represses cytoprotective transcription factor Nrf2 in an oxidative stress-dependent manner. The accumulation of selective autophagy substrate p62 also activates Nrf2 target genes, but the detailed mechanism has not been elucidated. Crystal structure of Keap1-p62 complex revealed the structural basis for the Nrf2 activation in which Keap1 is inactivated by p62. The accumulation of p62 is observed in hepatocellular carcinoma. The activation of Nrf2 target genes, including detoxifying enzymes and efflux transporters, by p62 may protect the cancer cells from anti-cancer drugs.

  13. Regulation of nucleotide excision repair through ubiquitination

    Institute of Scientific and Technical Information of China (English)

    Jia Li; Audesh Bhat; Wei Xiao

    2011-01-01

    Nucleotide excision repair (NER) is the most versatile DNA-repair pathway in all organisms.While bacteria require only three proteins to complete the incision step of NER,eukaryotes employ about 30 proteins to complete the same step.Here we summarize recent studies demonstrating that ubiquitination,a post-translational modification,plays critical roles in regulating the NER activity either dependent on or independent of ubiquitin-proteolysis.Several NER components have been shown as targets of ubiquitination while others are actively involved in the ubiquitination process.We argue through this analysis that ubiquitination serves to coordinate various steps of NER and meanwhile connect NER with other related pathways to achieve the efficient global DNA-damage response.

  14. Egr-1 regulates autophagy in cigarette smoke-induced chronic obstructive pulmonary disease.

    Directory of Open Access Journals (Sweden)

    Zhi-Hua Chen

    Full Text Available BACKGROUND: Chronic obstructive pulmonary disease (COPD is a progressive lung disease characterized by abnormal cellular responses to cigarette smoke, resulting in tissue destruction and airflow limitation. Autophagy is a degradative process involving lysosomal turnover of cellular components, though its role in human diseases remains unclear. METHODOLOGY AND PRINCIPAL FINDINGS: Increased autophagy was observed in lung tissue from COPD patients, as indicated by electron microscopic analysis, as well as by increased activation of autophagic proteins (microtubule-associated protein-1 light chain-3B, LC3B, Atg4, Atg5/12, Atg7. Cigarette smoke extract (CSE is an established model for studying the effects of cigarette smoke exposure in vitro. In human pulmonary epithelial cells, exposure to CSE or histone deacetylase (HDAC inhibitor rapidly induced autophagy. CSE decreased HDAC activity, resulting in increased binding of early growth response-1 (Egr-1 and E2F factors to the autophagy gene LC3B promoter, and increased LC3B expression. Knockdown of E2F-4 or Egr-1 inhibited CSE-induced LC3B expression. Knockdown of Egr-1 also inhibited the expression of Atg4B, a critical factor for LC3B conversion. Inhibition of autophagy by LC3B-knockdown protected epithelial cells from CSE-induced apoptosis. Egr-1(-/- mice, which displayed basal airspace enlargement, resisted cigarette-smoke induced autophagy, apoptosis, and emphysema. CONCLUSIONS: We demonstrate a critical role for Egr-1 in promoting autophagy and apoptosis in response to cigarette smoke exposure in vitro and in vivo. The induction of autophagy at early stages of COPD progression suggests novel therapeutic targets for the treatment of cigarette smoke induced lung injury.

  15. Precision autophagy: Will the next wave of selective autophagy markers and specific autophagy inhibitors feed clinical pipelines?

    Science.gov (United States)

    Lebovitz, Chandra B; DeVorkin, Lindsay; Bosc, Damien; Rothe, Katharina; Singh, Jagbir; Bally, Marcel; Jiang, Xiaoyan; Young, Robert N; Lum, Julian J; Gorski, Sharon M

    2015-01-01

    Research presented at the Vancouver Autophagy Symposium (VAS) 2014 suggests that autophagy's influence on health and disease depends on tight regulation and precision targeting of substrates. Discussions recognized a pressing need for robust biomarkers that accurately assess the clinical utility of modulating autophagy in disease contexts. Biomarker discovery could flow from investigations of context-dependent triggers, sensors, and adaptors that tailor the autophagy machinery to achieve target specificity. In his keynote address, Dr. Vojo Deretic (University of New Mexico) described the discovery of a cargo receptor family that utilizes peptide motif-based cargo recognition, a mechanism that may be more precise than generic substrate tagging. The keynote by Dr. Alec Kimmelman (Harvard Medical School) emphasized that unbiased screens for novel selective autophagy factors may accelerate the development of autophagy-based therapies. Using a quantitative proteomics screen for de novo identification of autophagosome substrates in pancreatic cancer, Kimmelman's group discovered a new type of selective autophagy that regulates bioavailable iron. Additional presentations revealed novel autophagy regulators and receptors in metabolic diseases, proteinopathies, and cancer, and outlined the development of specific autophagy inhibitors and treatment regimens that combine autophagy modulation with anticancer therapies. VAS 2014 stimulated interdisciplinary discussions focused on the development of biomarkers, drugs, and preclinical models to facilitate clinical translation of key autophagy discoveries.

  16. Anti-tumor immunity, autophagy and chemotherapy

    Institute of Scientific and Technical Information of China (English)

    Gy(o)rgyi Müzes; Ferenc Sipos

    2012-01-01

    Autophagy or self-digestion of cells is activated upon various stressful stimuli and has been found to be a survival and drug resistance pathway in cancer.However,genetic studies support that autophagy can act as a tumor suppressor.Furthermore,defective autophagy is implicated in tumorigenesis,as well.The precise impact of autophagy on malignant transformation has not yet been clarified,but recent data suggest that this complex process is mainly directed by cell types,phases,genetic background and microenvironment.Relation of autophagy to anticancer immune responses may indicate a novel aspect in cancer chemotherapy.

  17. The cellular decision between apoptosis and autophagy

    Institute of Scientific and Technical Information of China (English)

    Yong-Jun Fan; Wei-Xing Zong

    2013-01-01

    Apoptosis and autophagy are important molecular processes that maintain organismal and cellular homeostasis,respectively.While apoptosis fulfills its role through dismantling damaged or unwanted cells,autophagy maintains cellular homeostasis through recycling selective intracellular organelles and molecules.Yet in some conditions,autophagy can lead to cell death.Apoptosis and autophagy can be stimulated by the same stresses.Emerging evidence indicates an interplay between the core proteins in both pathways,which underlies the molecular mechanism of the crosstalk between apoptosis and autophagy.This review summarizes recent literature on molecules that regulate both the apoptotic and autophagic processes.

  18. AUTOPHAGY AND IL-1 FAMILY CYTOKINES

    Directory of Open Access Journals (Sweden)

    James Harris

    2013-01-01

    Full Text Available Autophagy is an important intracellular homeostatic mechanism for the targeting of cytosolic constituents, including organelles, for lysosomal degradation. Autophagy plays roles in numerous physiological processes, include immune cell responses to endogenous and exogenous pathogenic stimuli. Moreover, autophagy has a potentially pivotal role in the regulation of inflammatory responses. In particular, autophagy regulates endogenous inflammasome activators, as well as inflammasome components and pro-IL-1β. This review focuses specifically on the role autophagy plays in regulating the production, processing and secretion of IL-1 family cytokines.

  19. Autophagy in sepsis: Degradation into exhaustion?

    Science.gov (United States)

    Ho, Jeffery; Yu, Jun; Wong, Sunny H; Zhang, Lin; Liu, Xiaodong; Wong, Wai T; Leung, Czarina C H; Choi, Gordon; Wang, Maggie H T; Gin, Tony; Chan, Matthew T V; Wu, William K K

    2016-07-01

    Autophagy is one of the innate immune defense mechanisms against microbial challenges. Previous in vitro and in vivo models of sepsis demonstrated that autophagy was activated initially in sepsis, followed by a subsequent phase of impairment. Autophagy modulation appears to be protective against multiple organ injuries in these murine sepsis models. This is achieved in part by preventing apoptosis, maintaining a balance between the productions of pro- and anti-inflammatory cytokines, and preserving mitochondrial functions. This article aims to discuss the role of autophagy in sepsis and the therapeutic potential of autophagy enhancers.

  20. Autophagy in cancer: good, bad, or both?

    Science.gov (United States)

    Hippert, Melanie M; O'Toole, Patrick S; Thorburn, Andrew

    2006-10-01

    Autophagy has been recognized as an important cellular process for at least 50 years; however, it is only with the recent identification of key regulators of autophagy (Atg genes) that we have begun a mechanistic exploration of its importance in cancer. Recent studies suggest that autophagy may be important in the regulation of cancer development and progression and in determining the response of tumor cells to anticancer therapy. However, the role of autophagy in these processes is complicated and may, depending on the circumstances, have diametrically opposite consequences for the tumor. In this article, we discuss recent discoveries regarding autophagy in cancer.

  1. The Role of Histone Ubiquitination during Spermatogenesis

    Directory of Open Access Journals (Sweden)

    Kai Sheng

    2014-01-01

    Full Text Available Protein ubiquitin-proteasome (ubiquitin-proteasome system is the major mechanism responsible for protein degradation in eukaryotic cell. During spermatogenesis, the replacement of histone by protamine is vital for normal sperm formation, which is involved in ubiquitination enzymes expressed in testis. Recently, histone ubiquitin ligases have been shown to play critical roles in several aspects of spermatogenesis, such as meiotic sex chromosome inactivation (MSCI, DNA damage response, and spermiogenesis. In this review, we highlight recent progress in the discovery of several histone ubiquitin ligases and elaborate mechanisms of how these enzymes are involved in these processes through knockout mouse model. Using Huwe1, UBR2, and RNF8 as examples, we emphasized the diverse functions for each enzyme and the broad involvement of these enzymes in every stage, from spermatogonia differentiation and meiotic division to spermiogenesis; thus histone ubiquitin ligases represent a class of enzymes, which play important roles in spermatogenesis through targeting histone for ubiquitination and therefore are involved in transcription regulation, epigenetic modification, and other processes essential for normal gametes formation.

  2. The role of histone ubiquitination during spermatogenesis.

    Science.gov (United States)

    Sheng, Kai; Liang, Xiaotong; Huang, Sizhou; Xu, Wenming

    2014-01-01

    Protein ubiquitin-proteasome (ubiquitin-proteasome) system is the major mechanism responsible for protein degradation in eukaryotic cell. During spermatogenesis, the replacement of histone by protamine is vital for normal sperm formation, which is involved in ubiquitination enzymes expressed in testis. Recently, histone ubiquitin ligases have been shown to play critical roles in several aspects of spermatogenesis, such as meiotic sex chromosome inactivation (MSCI), DNA damage response, and spermiogenesis. In this review, we highlight recent progress in the discovery of several histone ubiquitin ligases and elaborate mechanisms of how these enzymes are involved in these processes through knockout mouse model. Using Huwe1, UBR2, and RNF8 as examples, we emphasized the diverse functions for each enzyme and the broad involvement of these enzymes in every stage, from spermatogonia differentiation and meiotic division to spermiogenesis; thus histone ubiquitin ligases represent a class of enzymes, which play important roles in spermatogenesis through targeting histone for ubiquitination and therefore are involved in transcription regulation, epigenetic modification, and other processes essential for normal gametes formation.

  3. Cardiac-specific catalase overexpression rescues anthrax lethal toxin-induced cardiac contractile dysfunction: role of oxidative stress and autophagy

    Directory of Open Access Journals (Sweden)

    Kandadi Machender R

    2012-11-01

    Full Text Available Abstract Background Lethal and edema toxins secreted by Bacillus anthracis during anthrax infection were found to incite serious cardiovascular complications. However, the underlying mechanisms in anthrax lethal toxin-induced cardiac anomalies remain unknown. This study was designed to evaluate the impact of antioxidant enzyme catalase in anthrax lethal toxin-induced cardiomyocyte contractile dysfunction. Methods Wild type (WT and cardiac-specific catalase overexpression mice were challenged with lethal toxin (2 μg/g, intraperotineally (i.p.. Cardiomyocyte contractile and intracellular Ca2+ properties were assessed 18 h later using an IonOptix edge-detection system. Proteasome function was assessed using chymotrypsin-like and caspase-like activities. GFP-LC3 puncta and Western blot analysis were used to evaluate autophagy and protein ubiquitination. Results Lethal toxin exposure suppressed cardiomyocyte contractile function (suppressed peak shortening, maximal velocity of shortening/re-lengthening, prolonged duration of shortening/re-lengthening, and impaired intracellular Ca2+ handling, the effects of which were alleviated by catalase. In addition, lethal toxin triggered autophagy, mitochondrial and ubiquitin-proteasome defects, the effects of which were mitigated by catalase. Pretreatment of cardiomyocytes from catalase mice with the autophagy inducer rapamycin significantly attenuated or ablated catalase-offered protection against lethal toxin-induced cardiomyocyte dysfunction. On the other hand, the autophagy inhibitor 3-MA ablated or significantly attenuated lethal toxin-induced cardiomyocyte contractile anomalies. Conclusions Our results suggest that catalase is protective against anthrax lethal toxin-induced cardiomyocyte contractile and intracellular Ca2+ anomalies, possibly through regulation of autophagy and mitochondrial function.

  4. The role of STAT3 in autophagy.

    Science.gov (United States)

    You, Liangkun; Wang, Zhanggui; Li, Hongsen; Shou, Jiawei; Jing, Zhao; Xie, Jiansheng; Sui, Xinbing; Pan, Hongming; Han, Weidong

    2015-01-01

    Autophagy is an evolutionarily conserved process in eukaryotes that eliminates harmful components and maintains cellular homeostasis in response to a series of extracellular insults. However, these insults may trigger the downstream signaling of another prominent stress responsive pathway, the STAT3 signaling pathway, which has been implicated in multiple aspects of the autophagic process. Recent reports further indicate that different subcellular localization patterns of STAT3 affect autophagy in various ways. For example, nuclear STAT3 fine-tunes autophagy via the transcriptional regulation of several autophagy-related genes such as BCL2 family members, BECN1, PIK3C3, CTSB, CTSL, PIK3R1, HIF1A, BNIP3, and microRNAs with targets of autophagy modulators. Cytoplasmic STAT3 constitutively inhibits autophagy by sequestering EIF2AK2 as well as by interacting with other autophagy-related signaling molecules such as FOXO1 and FOXO3. Additionally, the mitochondrial translocation of STAT3 suppresses autophagy induced by oxidative stress and may effectively preserve mitochondria from being degraded by mitophagy. Understanding the role of STAT3 signaling in the regulation of autophagy may provide insight into the classic autophagy model and also into cancer therapy, especially for the emerging targeted therapy, because a series of targeted agents execute antitumor activities via blocking STAT3 signaling, which inevitably affects the autophagy pathway. Here, we review several of the representative studies and the current understanding in this particular field.

  5. The symphony of autophagy and calcium signaling.

    Science.gov (United States)

    Yao, Zhiyuan; Klionsky, Daniel J

    2015-01-01

    Posttranslational regulation of macroautophagy (hereafter autophagy), including phosphorylating and dephosphorylating components of the autophagy-related (Atg) core machinery and the corresponding upstream transcriptional factors, is important for the precise modulation of autophagy levels. Several kinases that are involved in phosphorylating autophagy-related proteins have been identified in both yeast and mammalian cells. However, there has been much less research published with regard to the identification of the complementary phosphatases that function in autophagy. A recent study identified PPP3/calcineurin, a calcium-dependent phosphatase, as a regulator of autophagy, and demonstrated that one of the key targets of PPP3/calcineurin is TFEB, a master transcriptional factor that controls autophagy and lysosomal function in mammalian cells.

  6. Autophagy: An Exposing Therapeutic Target in Atherosclerosis.

    Science.gov (United States)

    Luo, Yun; Lu, Shan; Zhou, Ping; Ai, Qi-Di; Sun, Gui-Bo; Sun, Xiao-Bo

    2016-03-01

    Autophagy is an evolutionarily conserved catabolic process whereby the cytoplasmic contents of a cell are sequestered within autophagosomes through a lysosome-dependent pathway. Increasing evidence shows that this process is of great importance in a wide range of diseases, including atherosclerosis (AS). Autophagy can be modulated in advanced AS plaques by cytokines, reactive lipids, lipopolysaccharides, advanced glycation end products, and microRNAs. Autophagy exerts both protective and detrimental functions in vascular disorders. However, despite an increasing interest in autophagy, it remains an underestimated and overlooked phenomenon in AS. Therefore, the precise role of autophagy and its relationship with apoptosis need to be described. This review highlights recent findings on the autophagy activities and signaling pathways in endothelial cells, macrophages, and smooth muscle cells that are accompanied by apoptosis in AS. We conclude with recent studies on autophagy modulation as a new therapeutic approach to treat AS.

  7. Modulation of pathogen recognition by autophagy

    Directory of Open Access Journals (Sweden)

    Ji Eun eOh

    2012-03-01

    Full Text Available Autophagy is an ancient biological process for maintaining cellular homeostasis by degradation of long-lived cytosolic proteins and organelles. Recent studies demonstrated that autophagy is availed by immune cells to regulate innate immunity. On the one hand, cells exert direct effector function by degrading intracellular pathogens; on the other hand, autophagy modulates pathogen recognition and downstream signaling for innate immune responses. Pathogen recognition via pattern recognition receptors induces autophagy. The function of phagocytic cells is enhanced by recruitment of autophagy-related proteins. Moreover, autophagy acts as a delivery system for viral replication complexes to migrate to the endosomal compartments where virus sensing occurs. In another case, key molecules of the autophagic pathway have been found to negatively regulate immune signaling, thus preventing aberrant activation of cytokine production and consequent immune responses. In this review, we focus on the recent advances in the role of autophagy in pathogen recognition and modulation of innate immune responses.

  8. Conditional Expression of Parkinson's Disease-Related R1441C LRRK2 in Midbrain Dopaminergic Neurons of Mice Causes Nuclear Abnormalities without Neurodegeneration

    Science.gov (United States)

    Tsika, Elpida; Kannan, Meghna; Foo, Caroline Shi-Yan; Dikeman, Dustin; Glauser, Liliane; Gellhaar, Sandra; Galter, Dagmar; Knott, Graham W.; Dawson, Ted M.; Dawson, Valina L.; Moore, Darren J.

    2015-01-01

    Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene cause late-onset, autosomal dominant Parkinson's disease (PD). The clinical and neurochemical features of LRRK2-linked PD are similar to idiopathic disease although neuropathology is somewhat heterogeneous. Dominant mutations in LRRK2 precipitate neurodegeneration through a toxic gain-of-function mechanism which can be modeled in transgenic mice overexpressing human LRRK2 variants. A number of LRRK2 transgenic mouse models have been developed that display abnormalities in dopaminergic neurotransmission and alterations in tau metabolism yet without consistently inducing dopaminergic neurodegeneration. To directly explore the impact of mutant LRRK2 on the nigrostriatal dopaminergic pathway, we developed conditional transgenic mice that selectively express human R1441C LRRK2 in dopaminergic neurons from the endogenous murine ROSA26 promoter. The expression of R1441C LRRK2 does not induce the degeneration of substantia nigra dopaminergic neurons or striatal dopamine deficits in mice up to 2 years of age, and fails to precipitate abnormal protein inclusions containing alpha-synuclein, tau, ubiquitin or autophagy markers (LC3 and p62). Furthermore, mice expressing R1441C LRRK2 exhibit normal motor activity and olfactory function with increasing age. Intriguingly, the expression of R1441C LRRK2 induces age-dependent abnormalities of the nuclear envelope in nigral dopaminergic neurons including reduced nuclear circularity and increased invaginations of the nuclear envelope. In addition, R1441C LRRK2 mice display increased neurite complexity of cultured midbrain dopaminergic neurons. Collectively, these novel R1441C LRRK2 conditional transgenic mice reveal altered dopaminergic neuronal morphology with advancing age, and provide a useful tool for exploring the pathogenic mechanisms underlying the R1441C LRRK2 mutation in PD. PMID:25174890

  9. Interplay between HDAC6 and its interacting partners: essential roles in the aggresome-autophagy pathway and neurodegenerative diseases.

    Science.gov (United States)

    Yan, Jin

    2014-09-01

    Cytoplasmic localization and possession of two deacetylase domains and a ubiquitin-binding domain make histone deacetylase 6 (HDAC6) a unique histone deacetylase. HDAC6 interacts with a number of proteins in the cytoplasm. Some of these proteins can be deacetylated by HDAC6 deacetylase activity. Others can affect HDAC6 functions by modulating its catalytic activity or ubiquitin-binding capability. Over the last decade, HDAC6 has been shown to play important roles in the aggresome-autophagy pathway, which selectively targets on protein aggregates or damaged organelles for their accumulation and clearance in cells. HDAC6-interacting partners are integral components in this pathway with regard to their regulatory roles through interaction with HDAC6. The aggresome-autophagy pathway appears to be an attractive therapeutic target for the treatment of neurodegenerative diseases as accumulation of protein aggregates are hallmarks in these diseases. In the current review, I discuss the molecular details of how HDAC6 and its interacting partners regulate each individual step in the aggresome-autophagy pathway and also provide perspectives of how HDAC6 can be targeted in treating neurodegenerative diseases.

  10. The natural history of ubiquitin and ubiquitin-related domains.

    Science.gov (United States)

    Burroughs, Alexander Maxwell; Iyer, Lakshminarayan M; Aravind, L

    2012-01-01

    The ubiquitin (Ub) system is centered on conjugation and deconjugation of Ub and Ub-like (Ubls) proteins by a system of ligases and peptidases, respectively. Ub/Ubls contain the beta-grasp fold, also found in numerous proteins with biochemically distinct roles unrelated to the conventional Ub-system. The beta-GF underwent an early radiation spawning at least seven clades prior to the divergence of extant organisms from their last universal common ancestor, first emerging in the context of translation-related RNA-interactions and subsequently exploding to occupy various functional niches. Most beta-GF diversification occurred in prokaryotes, with the Ubl clade showing dramatic expansion in the eukaryotes. Diversification of Ubl families in eukaryotes played a major role in emergence of characteristic eukaryotic cellular sub-structures and systems. Recent comparative genomics studies indicate precursors of the eukaryotic Ub-system emerged in prokaryotes. The simplest of these combine an Ubl and an E1-like enzyme in metabolic pathways. Sampylation in archaea and Urmylation in eukaryotes appear to represent recruitment of such systems as simple protein-tagging apparatuses. However, other prokaryotic systems incorporated further components and mirror the eukaryotic condition in possessing an E2, a RING-type E3 or both of these components. Additionally, prokaryotes have evolved conjugation systems independent of Ub ligases, such as the Pup system.

  11. Role of ubiquitination in meiotic recombination repair

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Programmed and unprogrammed double-strand breaks (DSBs) often arise from such physiological requirements as meiotic recombination, and exogenous insults, such as ionizing radiation (IR). Due to deleterious impacts on genome stability, DSBs must be appropriately processed and repaired in a regulatory manner. Recent investigations have indicated that ubiquitination is a critical factor in DNA damage response and meiotic recombination repair. This review summarizes the effects of proteins and complexes associated with ubiquitination with regard to homologous recombination (HR)-dependent DSB repair.

  12. Ordered bulk degradation via autophagy

    DEFF Research Database (Denmark)

    Dengjel, Jörn; Kristensen, Anders Riis; Andersen, Jens S

    2008-01-01

    at proteasomal and lysosomal degradation ample cross-talk between the two degradation pathways became evident. Degradation via autophagy appeared to be ordered and regulated at the protein complex/organelle level. This raises several important questions such as: can macroautophagy itself be specific and what...

  13. Epigallocatechin-gallate (EGCG) regulates autophagy in human retinal pigment epithelial cells: A potential role for reducing UVB light-induced retinal damage

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chao-Peng; Yao, Jin; Tao, Zhi-Fu; Li, Xiu-Miao; Jiang, Qin, E-mail: jqin710@vip.sina.com; Yan, Biao, E-mail: yanbiao1982@hotmail.com

    2013-09-06

    Highlights: •UVB irradiation induces RPE autophagy. •EGCG treatment represses UVB-mediated autophagy. •EGCG regulates UVB-mediated autophagy through mTOR signaling pathway. •EGCG sensitizes RPE cells to UVB-induced damage in an autophagy-dependent manner. -- Abstract: Autophagy is an intracellular catabolic process involved in protein and organelle degradation via the lysosomal pathway that has been linked in the pathogenesis of age-related macular degeneration (AMD). UVB irradiation-mediated degeneration of the macular retinal pigment epithelial (RPE) cells is an important hallmark of AMD, which is along with the change in RPE autophagy. Thus, pharmacological manipulation of RPE autophagy may offer an alternative therapeutic target in AMD. Here, we found that epigallocatechin-3-gallate (EGCG), a polyphenolic compound from green tea, plays a regulatory role in UVB irradiation-induced autophagy in RPE cells. UVB irradiation results in a marked increase in the amount of LC3-II protein in a dose-dependent manner. EGCG administration leads to a significant reduction in the formation of LC3-II and autophagosomes. mTOR signaling activation is required for EGCG-induced LC3-II formation, as evidenced by the fact that EGCG-induced LC3-II formation is significantly impaired by rapamycin administration. Moreover, EGCG significantly alleviates the toxic effects of UVB irradiation on RPE cells in an autophagy-dependent manner. Collectively, our study reveals a novel role of EGCG in RPE autophagy. EGCG may be exploited as a potential therapeutic reagent for the treatment of pathological conditions associated with abnormal autophagy.

  14. Sucrose induces vesicle accumulation and autophagy.

    Science.gov (United States)

    Higuchi, Takahiro; Nishikawa, Jun; Inoue, Hiroko

    2015-04-01

    It has been shown that the treatment of mammalian cells with sucrose leads to vacuole accumulation associated with lysosomes and upregulation of lysosomal enzyme expression and activity. Autophagy is an evolutionarily conserved homeostatic process by which cells deliver cytoplasmic material for degradation into lysosomes, thus it is probable that sucrose affects the autophagic activity. The role of sucrose in autophagy is unknown; however, another disaccharide, trehalose has been shown to induce autophagy. In the current study, we used mouse embryonic fibroblasts to investigate whether sucrose induces autophagy and whether vesicle formation is associated with autophagy. The results showed that sucrose induces autophagy while being accumulated within the endosomes/lysosomes. These vesicles were swollen and packed within the cytoplasm. Furthermore, trehalose and the trisaccharide raffinose, which are not hydrolyzed in mammalian cells, increased the rate of vesicles accumulation and LC3-II level (a protein marker of autophagy). However, fructose and maltose did not show the same effects. The correlation between the two processes, vesicle accumulation and autophagy induction, was confirmed by treatment of cells with sucrose plus invertase, or maltose plus acarbose-the α-glucosidase inhibitor-and by sucrose deprivation. Results also showed that vesicle accumulation was not affected by autophagy inhibition. Therefore, the data suggest that sucrose-induced autophagy through accumulation of sucrose-containing vesicles is caused by the absence of hydrolysis enzymes.

  15. Carbamazepine suppresses calpain-mediated autophagy impairment after ischemia/reperfusion in mouse livers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-Sung, E-mail: Jae.Kim@surgery.ufl.edu; Wang, Jin-Hee, E-mail: jin-hee.wang@surgery.ufl.edu; Biel, Thomas G., E-mail: Thomas.Biel@surgery.ufl.edu; Kim, Do-Sung, E-mail: do-sung.kim@surgery.med.ufl.edu; Flores-Toro, Joseph A., E-mail: Joseph.Flores-Toro@surgery.ufl.edu; Vijayvargiya, Richa, E-mail: rvijayvargiya@ufl.edu; Zendejas, Ivan, E-mail: ivan.zendejas@surgery.ufl.edu; Behrns, Kevin E., E-mail: Kevin.Behrns@surgery.ufl.edu

    2013-12-15

    Onset of the mitochondrial permeability transition (MPT) plays a causative role in ischemia/reperfusion (I/R) injury. Current therapeutic strategies for reducing reperfusion injury remain disappointing. Autophagy is a lysosome-mediated, catabolic process that timely eliminates abnormal or damaged cellular constituents and organelles such as dysfunctional mitochondria. I/R induces calcium overloading and calpain activation, leading to degradation of key autophagy-related proteins (Atg). Carbamazepine (CBZ), an FDA-approved anticonvulsant drug, has recently been reported to increase autophagy. We investigated the effects of CBZ on hepatic I/R injury. Hepatocytes and livers from male C57BL/6 mice were subjected to simulated in vitro, as well as in vivo I/R, respectively. Cell death, intracellular calcium, calpain activity, changes in autophagy-related proteins (Atg), autophagic flux, MPT and mitochondrial membrane potential after I/R were analyzed in the presence and absence of 20 μM CBZ. CBZ significantly increased hepatocyte viability after reperfusion. Confocal microscopy revealed that CBZ prevented calcium overloading, the onset of the MPT and mitochondrial depolarization. Immunoblotting and fluorometric analysis showed that CBZ blocked calpain activation, depletion of Atg7 and Beclin-1 and loss of autophagic flux after reperfusion. Intravital multiphoton imaging of anesthetized mice demonstrated that CBZ substantially reversed autophagic defects and mitochondrial dysfunction after I/R in vivo. In conclusion, CBZ prevents calcium overloading and calpain activation, which, in turn, suppresses Atg7 and Beclin-1 depletion, defective autophagy, onset of the MPT and cell death after I/R. - Highlights: • A mechanism of carbamazepine (CBZ)-induced cytoprotection in livers is proposed. • Impaired autophagy is a key event contributing to lethal reperfusion injury. • The importance of autophagy is extended and confirmed in an in vivo model. • CBZ is a potential

  16. Inhibition of autophagy induces retinal pigment epithelial cell damage by the lipofuscin fluorophore A2E

    Directory of Open Access Journals (Sweden)

    Khandakar A.S.M. Saadat

    2014-01-01

    Full Text Available In this study, we show augmented autophagy in the retinal pigment epithelial cell line ARPE-19 when cultured in the presence of the lipofuscin pigment A2E. A2E alone does not induce RPE cell death, but cell death was induced in the presence of A2E with the autophagy inhibitor 3-methyladenine (3MA, with a concomitant increase in the generation of mitochondrial reactive oxygen species. On the other hand, the ATP production capacity of mitochondria was decreased in the presence of A2E, and pharmacological inhibition of autophagy had no additional effects. The altered mRNA expression level of mitochondrial function markers was confirmed by real-time polymerase chain reaction, which showed that the antioxidant enzymes SOD1 and SOD2 were not reduced in the presence of A2E alone, but significantly suppressed with the addition of 3MA. Furthermore, transmission electron micrography revealed autophagic vacuole formation in the presence of A2E, and inhibition of autophagy resulted in the accumulation of abnormal mitochondria with loss of cristae. Spheroid culture of human RPE cells demonstrated debris accumulation in the presence of A2E, and this accumulation was accelerated in the presence of 3MA. These results indicate that autophagy in RPE cells is a vital cytoprotective process that prevents the accumulation of damaged cellular molecules.

  17. HUWE1 and TRIP12 Collaborate in Degradation of Ubiquitin-Fusion Proteins and Misframed Ubiquitin

    DEFF Research Database (Denmark)

    Poulsen, Esben G; Steinhauer, Cornelia; Lees, Michael

    2012-01-01

    In eukaryotic cells an uncleavable ubiquitin moiety conjugated to the N-terminus of a protein signals the degradation of the fusion protein via the proteasome-dependent ubiquitin fusion degradation (UFD) pathway. In yeast the molecular mechanism of the UFD pathway has been well characterized. Rec...

  18. Feedback regulation between autophagy and PKA.

    Science.gov (United States)

    Torres-Quiroz, Francisco; Filteau, Marie; Landry, Christian R

    2015-01-01

    Protein kinase A (PKA) controls diverse cellular processes and homeostasis in eukaryotic cells. Many processes and substrates of PKA have been described and among them are direct regulators of autophagy. The mechanisms of PKA regulation and how they relate to autophagy remain to be fully understood. We constructed a reporter of PKA activity in yeast to identify genes affecting PKA regulation. The assay systematically measures relative protein-protein interactions between the regulatory and catalytic subunits of the PKA complex in a systematic set of genetic backgrounds. The candidate PKA regulators we identified span multiple processes and molecular functions (autophagy, methionine biosynthesis, TORC signaling, protein acetylation, and DNA repair), which themselves include processes regulated by PKA. These observations suggest the presence of many feedback loops acting through this key regulator. Many of the candidate regulators include genes involved in autophagy, suggesting that not only does PKA regulate autophagy but that autophagy also sends signals back to PKA.

  19. Autophagy and IL-1 family cytokines

    Directory of Open Access Journals (Sweden)

    James eHarris

    2013-04-01

    Full Text Available Autophagy is an important intracellular homeostatic mechanism for the targeting of cytosolic constituents, including organelles, for lysosomal degradation. Autophagy plays roles in numerous physiological processes, including immune cell responses to endogenous and exogenous pathogenic stimuli. Moreover, autophagy has a potentially pivotal role to play in the regulation of inflammatory responses. In particular, autophagy regulates endogenous inflammasome activators, as well as inflammasome components and pro-IL-1β. As a result, autophagy acts a key modulator of IL-1β and IL-18, as well as IL-1α, release. This review focuses specifically on the role autophagy plays in regulating the production, processing and secretion of IL-1 and IL-18 and the consequences of this important function.

  20. Autophagy and IL-1 Family Cytokines.

    Science.gov (United States)

    Harris, James

    2013-01-01

    Autophagy is an important intracellular homeostatic mechanism for the targeting of cytosolic constituents, including organelles, for lysosomal degradation. Autophagy plays roles in numerous physiological processes, including immune cell responses to endogenous and exogenous pathogenic stimuli. Moreover, autophagy has a potentially pivotal role to play in the regulation of inflammatory responses. In particular, autophagy regulates endogenous inflammasome activators, as well as inflammasome components and pro-IL-1β. As a result, autophagy acts a key modulator of IL-1β and IL-18, as well as IL-1α, release. This review focuses specifically on the role autophagy plays in regulating the production, processing, and secretion of IL-1 and IL-18 and the consequences of this important function.

  1. Feedback regulation between autophagy and PKA

    Science.gov (United States)

    Torres-Quiroz, Francisco; Filteau, Marie; Landry, Christian R

    2015-01-01

    Protein kinase A (PKA) controls diverse cellular processes and homeostasis in eukaryotic cells. Many processes and substrates of PKA have been described and among them are direct regulators of autophagy. The mechanisms of PKA regulation and how they relate to autophagy remain to be fully understood. We constructed a reporter of PKA activity in yeast to identify genes affecting PKA regulation. The assay systematically measures relative protein-protein interactions between the regulatory and catalytic subunits of the PKA complex in a systematic set of genetic backgrounds. The candidate PKA regulators we identified span multiple processes and molecular functions (autophagy, methionine biosynthesis, TORC signaling, protein acetylation, and DNA repair), which themselves include processes regulated by PKA. These observations suggest the presence of many feedback loops acting through this key regulator. Many of the candidate regulators include genes involved in autophagy, suggesting that not only does PKA regulate autophagy but that autophagy also sends signals back to PKA. PMID:26046386

  2. Molecular mechanism and regulation of autophagy

    Institute of Scientific and Technical Information of China (English)

    Ya-ping YANG; Zhong-qin LIANG; Zhen-lun GU; Zheng-hong QIN

    2005-01-01

    Autophagy is a major cellular pathway for the degradation of long-lived proteins and cytoplasmic organelles in eukaryotic cells. A large number of intracellular/extracellular stimuli, including amino acid starvation and invasion of microorganisms, are able to induce the autophagic response in cells. The discovery of the ATG genes in yeast has greatly advanced our understanding of the molecular mechanisms participating in autophagy and the genes involved in regulating the autophagic pathway. Many yeast genes have mammalian homologs,suggesting that the basic machinery for autophagy has been evolutionarily conserved along the eukaryotic phylum. The regulation of autophagy is a very complex process. Many signaling pathways, including target of rapamycin (TOR) or mammalian target of rapamycin (mTOR), phosphatidylinositol 3-kinase-I (PI3K-I)/PKB, GTPases, calcium and protein synthesis all play important roles in regulating autophagy. The molecular mechanisms and regulation of autophagy are discussed in this review.

  3. Autophagy gets in on the regulatory act

    Institute of Scientific and Technical Information of China (English)

    Steven K. Backues; Daniel J. Klionsky

    2011-01-01

    Autophagy down-regulates the Wnt signal transduction pathway via targeted degradation of a key signaling protein. This may provide an explanation for autophagy's role in tumor suppression.%@@ The eukaryotic cell has at its disposal two primary methods for getting rid of unwanted proteins: the proteasome and autophagy.The proteasome is a large protein complex comprising regulatory and proteolytic subunits whose core function is the degradation of damaged or misfolded proteins.

  4. Autophagy and apoptosis: where do they meet?

    Science.gov (United States)

    Mukhopadhyay, Subhadip; Panda, Prashanta Kumar; Sinha, Niharika; Das, Durgesh Nandini; Bhutia, Sujit Kumar

    2014-04-01

    Autophagy and apoptosis are two important cellular processes with complex and intersecting protein networks; as such, they have been the subjects of intense investigation. Recent advances have elucidated the key players and their molecular circuitry. For instance, the discovery of Beclin-1's interacting partners has resulted in the identification of Bcl-2 as a central regulator of autophagy and apoptosis, which functions by interacting with both Beclin-1 and Bax/Bak respectively. When localized to the endoplasmic reticulum and mitochondria, Bcl-2 inhibits autophagy. Cellular stress causes the displacement of Bcl-2 from Beclin-1 and Bax, thereby triggering autophagy and apoptosis, respectively. The induction of autophagy or apoptosis results in disruption of complexes by BH3-only proteins and through post-translational modification. The mechanisms linking autophagy and apoptosis are not fully defined; however, recent discoveries have revealed that several apoptotic proteins (e.g., PUMA, Noxa, Nix, Bax, XIAP, and Bim) modulate autophagy. Moreover, autophagic proteins that control nucleation and elongation regulate intrinsic apoptosis through calpain- and caspase-mediated cleavage of autophagy-related proteins, which switches the cellular program from autophagy to apoptosis. Similarly, several autophagic proteins are implicated in extrinsic apoptosis. This highlights a dual cellular role for autophagy. On one hand, autophagy degrades damaged mitochondria and caspases, and on the other hand, it provides a membrane-based intracellular platform for caspase processing in the regulation of apoptosis. In this review, we highlight the crucial factors governing the crosstalk between autophagy and apoptosis and describe the mechanisms controlling cell survival and cell death.

  5. The role of autophagy in Parkinson's disease

    Institute of Scientific and Technical Information of China (English)

    Lei Zhang; Yaru Dong; Xiaoheng Xu; Zhong Xu

    2012-01-01

    Although Parkinson's disease is the most common neurodegenerative movement disorder, the mechanisms of pathogenesis remain poorly understood. Recent findings have shown that deregulation of the autophagy-lysosome pathway is involved in the pathogenesis of Parkinson's disease. This review summarizes the most recent findings and discusses the unique role of the autophagy-lysosome pathway in Parkinson's disease to highlight the possibility of Parkinson's disease treatment strategies that incorporate autophagy-lysosome pathway modulation.

  6. The dynamic nature of autophagy in cancer.

    Science.gov (United States)

    Kimmelman, Alec C

    2011-10-01

    Macroautophagy (referred to hereafter as autophagy) is a highly regulated cellular process that serves to remove damaged proteins and organelles from the cell. Autophagy contributes to an array of normal and pathological processes, and has recently emerged as a key regulator of multiple aspects of cancer biology. The role of autophagy in cancer is complex and is likely dependent on tumor type, stage, and genetic context. This complexity is illustrated by the identification of settings where autophagy acts potently to either promote or inhibit tumorigenesis. In this review, I discuss the underlying basis for these opposing functions and propose a model suggesting a dynamic role for autophagy in malignancy. Collectively, the data point to autophagy as serving as a barrier to limit tumor initiation. Once neoplastic lesions are established, it appears that adaptive changes occur that now result in positive roles for autophagy in malignant progression and in subsequent tumor maintenance. Remarkably, constitutive activation of autophagy is critical for continued growth of some tumors, serving to both reduce oxidative stress and provide key intermediates to sustain cell metabolism. Autophagy is also induced in response to cancer therapies where it can function as a survival mechanism that limits drug efficacy. These findings have inspired significant interest in applying anti-autophagy therapies as an entirely new approach to cancer treatment. It is now apparent that aberrant control of autophagy is among the key hallmarks of cancer. While much needs to be learned about the regulation and context-dependent biological functions of autophagy, it seems clear that modulation of this process will be an attractive avenue for future cancer therapeutic approaches.

  7. Investigating regulatory signatures of human autophagy related gene 5 (ATG5 through functional in silico analysis

    Directory of Open Access Journals (Sweden)

    Avni Vij

    2016-09-01

    Full Text Available Autophagy is an essential, homeostatic process which removes damaged cellular proteins and organelles for cellular renewal. ATG5, a part of E3 ubiquitin ligase-like complex (Atg12-Atg5/Atg16L1, is a key regulator involved in autophagosome formation - a crucial phase of autophagy. In this study, we used different in silico methods for comprehensive analysis of ATG5 to investigate its less explored regulatory activity. We have predicted various physico-chemical parameters and two possible transmembrane models that helped in exposing its functional regions. Twenty four PTM sites and 44 TFBS were identified which could be targeted to modulate the autophagy pathway. Furthermore, LD analysis identified 3 blocks of genotyped SNPs and 2 deleterious nsSNPs that may have damaging impact on protein function and thus could be employed for carrying genome-wide association studies. In conclusion, the information obtained in this study could be helpful for better understanding of regulatory roles of ATG5 and provides a base for its implication in population-based studies.

  8. Involvement of Autophagy in Coronavirus Replication

    Directory of Open Access Journals (Sweden)

    Paul Britton

    2012-11-01

    Full Text Available Coronaviruses are single stranded, positive sense RNA viruses, which induce the rearrangement of cellular membranes upon infection of a host cell. This provides the virus with a platform for the assembly of viral replication complexes, improving efficiency of RNA synthesis. The membranes observed in coronavirus infected cells include double membrane vesicles. By nature of their double membrane, these vesicles resemble cellular autophagosomes, generated during the cellular autophagy pathway. In addition, coronavirus infection has been demonstrated to induce autophagy. Here we review current knowledge of coronavirus induced membrane rearrangements and the involvement of autophagy or autophagy protein microtubule associated protein 1B light chain 3 (LC3 in coronavirus replication.

  9. Regulation of cardiomyocyte autophagy by calcium.

    Science.gov (United States)

    Shaikh, Soni; Troncoso, Rodrigo; Criollo, Alfredo; Bravo-Sagua, Roberto; García, Lorena; Morselli, Eugenia; Cifuentes, Mariana; Quest, Andrew F G; Hill, Joseph A; Lavandero, Sergio

    2016-04-15

    Calcium signaling plays a crucial role in a multitude of events within the cardiomyocyte, including cell cycle control, growth, apoptosis, and autophagy. With respect to calcium-dependent regulation of autophagy, ion channels and exchangers, receptors, and intracellular mediators play fundamental roles. In this review, we discuss calcium-dependent regulation of cardiomyocyte autophagy, a lysosomal mechanism that is often cytoprotective, serving to defend against disease-related stress and nutrient insufficiency. We also highlight the importance of the subcellular distribution of calcium and related proteins, interorganelle communication, and other key signaling events that govern cardiomyocyte autophagy.

  10. Autophagy in term normal human placentas.

    Science.gov (United States)

    Signorelli, P; Avagliano, L; Virgili, E; Gagliostro, V; Doi, P; Braidotti, P; Bulfamante, G P; Ghidoni, R; Marconi, A M

    2011-06-01

    Autophagy is an inducible catabolic process that responds to environment and is essential for cell survival during stress, starvation and hypoxia. Its function in the human placenta it is not yet understood. We collected 14 placentas: 7 at vaginal delivery and 7 at elective caesarean section after uneventful term pregnancies. The presence of autophagy was assessed in different placental areas by immunoblotting, immunohistochemistry and electron microscopy. We found that autophagy is significantly higher in placentas obtained from cesarean section than in those from vaginal delivery. Moreover there is a significant inverse relationship between autophagy and umbilical arterial glucose concentration.

  11. Autophagy : Moving Benchside Promises to Patient Bedsides.

    Science.gov (United States)

    Belaid, Amine; Ndiaye, Papa Diogop; Filippakis, Harilaos; Roux, Jérémie; Röttinger, Éric; Graba, Yacine; Brest, Patrick; Hofman, Paul; Mograbi, Baharia

    2015-01-01

    Survival rates of patients with metastatic or recurrent cancers have remained virtually unchanged during the past 30 years. This fact makes the need for new therapeutic options even more urgent. An attractive option would be to target autophagy, an essential quality control process that degrades toxic aggregates, damaged organelles, and signaling proteins, and acts as a tumor suppressor pathway of tumor initiation. Conversely, other fascinating observations suggest that autophagy supports cancer progression, relapse, metastasis, dormancy and resistance to therapy. This review provides an overview of the contradictory roles that autophagy plays in cancer initiation and progression and discusses the promises and challenges of current strategies that target autophagy for cancer therapy.

  12. Autophagy and the nutritional signaling pathway

    Directory of Open Access Journals (Sweden)

    Long HE,Shabnam ESLAMFAM,Xi MA,Defa LI

    2016-09-01

    Full Text Available During their growth and development, animals adapt to tremendous changes in order to survive. These include responses to both environmental and physiological changes and autophagy is one of most important adaptive and regulatory mechanisms. Autophagy is defined as an autolytic process to clear damaged cellular organelles and recycle the nutrients via lysosomic degradation. The process of autophagy responds to special conditions such as nutrient withdrawal. Once autophagy is induced, phagophores form and then elongate and curve to form autophagosomes. Autophagosomes then engulf cargo, fuse with endosomes, and finally fuse with lysosomes for maturation. During the initiation process, the ATG1/ULK1 (unc-51-like kinase 1 and VPS34 (which encodes a class III phosphatidylinositol (PtdIns 3-kinase complexes are critical in recruitment and assembly of other complexes required for autophagy. The process of autophagy is regulated by autophagy related genes (ATGs. Amino acid and energy starvation mediate autophagy by activating mTORC1 (mammalian target of rapamycin and AMP-activated protein kinase (AMPK. AMPK is the energy status sensor, the core nutrient signaling component and the metabolic kinase of cells. This review mainly focuses on the mechanism of autophagy regulated by nutrient signaling especially for the two important complexes, ULK1 and VPS34.

  13. Modulating autophagy: a strategy for cancer therapy

    Institute of Scientific and Technical Information of China (English)

    Jun-Lin Li; Shao-Liang Han; Xia Fan

    2011-01-01

    Autophagy is a process in which long-lived proteins,damaged cell organelles,and other cellular particles are sequestered and degraded.This process is important for maintaining the cellular microenvironment when the cell is under stress.Many studies have shown that autophagy plays a complex role in human diseases,especially in cancer,where it is known to have paradoxical effects.Namely,autophagy provides the energy for metabolism and tumor growth and leads to cell death that promotes tumor suppression.The link between autophagy and cancer is also evident in that some of the genes that regulate carcinogenesis,oncogenes and tumor suppressor genes,participate in or impact the autophagy process.Therefore,modulating autophagy will be a valuable topic for cancer therapy.Many studies have shown that autophagy can inhibit the tumor growth when autophagy modulators are combined with radiotherapy and/or chemotherapy.These findings suggest that autophagy may be a potent target for cancer therapy.

  14. mRNA and protein dataset of autophagy markers (LC3 and p62 in several cell lines

    Directory of Open Access Journals (Sweden)

    Rubén Gómez-Sánchez

    2016-06-01

    Full Text Available We characterized the dynamics of autophagy in vitro using four different cell systems and analyzing markers widely used in this field, i.e. LC3 (microtubule-associated protein 1 light chain 3; protein recruited from the cytosol (LC3-I to the autophagosomal membrane where it is lipidated (LC3-II and p62/SQSTM1 (adaptor protein that serves as a link between LC3 and ubiquitinated substrates, (Klionsky et al., 2016 [1]. Data provided include analyses of protein levels of LC3 and p62 by Western-blotting and endogenous immunofluorescence experiments, but also p62 mRNA levels obtained by quantitative PCR (qPCR. To monitor the turnover of these autophagy markers and, thus, measure the flux of this pathway, cells were under starvation conditions and/or treated with bafilomycin A1 (Baf. A1 to block fusion of autophagosomes with lysosomes.

  15. mRNA and protein dataset of autophagy markers (LC3 and p62) in several cell lines

    Science.gov (United States)

    Gómez-Sánchez, Rubén; Yakhine-Diop, Sokhna M.S.; Rodríguez-Arribas, Mario; Bravo-San Pedro, José M.; Martínez-Chacón, Guadalupe; Uribe-Carretero, Elisabet; Pinheiro de Castro, Diana C.J.; Pizarro-Estrella, Elisa; Fuentes, José M.; González-Polo, Rosa A.

    2016-01-01

    We characterized the dynamics of autophagy in vitro using four different cell systems and analyzing markers widely used in this field, i.e. LC3 (microtubule-associated protein 1 light chain 3; protein recruited from the cytosol (LC3-I) to the autophagosomal membrane where it is lipidated (LC3-II)) and p62/SQSTM1 (adaptor protein that serves as a link between LC3 and ubiquitinated substrates), (Klionsky et al., 2016) [1]. Data provided include analyses of protein levels of LC3 and p62 by Western-blotting and endogenous immunofluorescence experiments, but also p62 mRNA levels obtained by quantitative PCR (qPCR). To monitor the turnover of these autophagy markers and, thus, measure the flux of this pathway, cells were under starvation conditions and/or treated with bafilomycin A1 (Baf. A1) to block fusion of autophagosomes with lysosomes. PMID:27054171

  16. Integrated Genomics of Crohn’s Disease Risk Variant Identifies a Role for CLEC12A in Antibacterial Autophagy

    Directory of Open Access Journals (Sweden)

    Jakob Begun

    2015-06-01

    Full Text Available The polymorphism ATG16L1 T300A, associated with increased risk of Crohn’s disease, impairs pathogen defense mechanisms including selective autophagy, but specific pathway interactions altered by the risk allele remain unknown. Here, we use perturbational profiling of human peripheral blood cells to reveal that CLEC12A is regulated in an ATG16L1-T300A-dependent manner. Antibacterial autophagy is impaired in CLEC12A-deficient cells, and this effect is exacerbated in the presence of the ATG16L1∗300A risk allele. Clec12a−/− mice are more susceptible to Salmonella infection, supporting a role for CLEC12A in antibacterial defense pathways in vivo. CLEC12A is recruited to sites of bacterial entry, bacteria-autophagosome complexes, and sites of sterile membrane damage. Integrated genomics identified a functional interaction between CLEC12A and an E3-ubiquitin ligase complex that functions in antibacterial autophagy. These data identify CLEC12A as early adaptor molecule for antibacterial autophagy and highlight perturbational profiling as a method to elucidate defense pathways in complex genetic disease.

  17. Molecular Mechanisms of Autophagy in Plants: Role of ATG8 Proteins in Formation and Functioning of Autophagosomes.

    Science.gov (United States)

    Ryabovol, V V; Minibayeva, F V

    2016-04-01

    Autophagy is an efficient way of degradation and removal of unwanted or damaged intracellular components in plant cells. It plays an important role in recycling of intracellular structures (during starvation, removal of cell components formed during plant development or damaged by various stress factors) and in programmed cell death. Morphologically, autophagy is characterized by the formation of double-membrane vesicles called autophagosomes, which are essential for the isolation and degradation of cytoplasmic components. Among autophagic (ATG) proteins, ATG8 from the ubiquitin-like protein family plays a key role in autophagosome formation. ATG8 is also involved in selective autophagy, fusion of autophagosome with the vacuole, and some other intracellular processes not associated with autophagy. In contrast to yeasts that carry a single ATG8 gene, plants have multigene ATG8 families. The reason for such great ATG8 diversity in plants remains unclear. It is also unknown whether all members of the ATG8 family are involved in the formation and functioning of autophagosomes. To answer these questions, the identification of the structure and the possible functions of plant proteins from ATG8 family is required. In this review, we analyze the structures of ATG8 proteins from plants and their homologs from yeast and animal cells, interactions of ATG8 proteins with functional ligands, and involvement of ATG8 proteins in different metabolic processes in eukaryotes.

  18. Carboxyl terminus of Hsp70-interacting protein (CHIP) is required to modulate cardiac hypertrophy and attenuate autophagy during exercise.

    Science.gov (United States)

    Willis, Monte S; Min, Jin-Na; Wang, Shaobin; McDonough, Holly; Lockyer, Pamela; Wadosky, Kristine M; Patterson, Cam

    2013-12-01

    The carboxyl terminus of Hsp70-interacting protein (CHIP) is a ubiquitin ligase/cochaperone critical for the maintenance of cardiac function. Mice lacking CHIP (CHIP-/-) suffer decreased survival, enhanced myocardial injury and increased arrhythmias compared with wild-type controls following challenge with cardiac ischaemia reperfusion injury. Recent evidence implicates a role for CHIP in chaperone-assisted selective autophagy, a process that is associated with exercise-induced cardioprotection. To determine whether CHIP is involved in cardiac autophagy, we challenged CHIP-/- mice with voluntary exercise. CHIP-/- mice respond to exercise with an enhanced autophagic response that is associated with an exaggerated cardiac hypertrophy phenotype. No impairment of function was identified in the CHIP-/- mice by serial echocardiography over the 5 weeks of running, indicating that the cardiac hypertrophy was physiologic not pathologic in nature. It was further determined that CHIP plays a role in inhibiting Akt signalling and autophagy determined by autophagic flux in cardiomyocytes and in the intact heart. Taken together, cardiac CHIP appears to play a role in regulating autophagy during the development of cardiac hypertrophy, possibly by its role in supporting Akt signalling, induced by voluntary running in vivo.

  19. RNF146 Inhibits Excessive Autophagy by Modulating the Wnt-β-Catenin Pathway in Glutamate Excitotoxicity Injury

    Science.gov (United States)

    Yang, Yuefan; Luo, Peng; Xu, Haoxiang; Dai, Shuhui; Rao, Wei; Peng, Cheng; Ma, Wenke; Wang, Jiu; Xu, Hongyu; Zhang, Lei; Zhang, Sai; Fei, Zhou

    2017-01-01

    Glutamate induced excitotoxicity is common in diverse neurological disorders. RNF146 as an E3 ubiquitin ligase protects neurons against excitotoxicity via interfering with Poly (ADP-ribose) (PAR) polymer-induced cell death (parthanatos). However, the neuroprotective role of RNF146 has not been fully understood. We aimed to investigate the role of RNF146 in modulating autophagy in HT22 cells under glutamate excitotoxicity injury. Here we found that induction of RNF146 decreased the cellular damage and excitotoxicity induced by glutamate. RNF146 also suppressed the excessive autophagy, which is detrimental to HT22 cells survival, induced by glutamate or rapamycin treatment. In addition, we find that Wnt/β-catenin was a negative regulation factor for autophagy in glutamate excitotoxicity. Over-expression of RNF146 promoted Wnt/β-catenin signaling, which was related to destabilization of β-catenin destruction complex. These results indicated that RNF146 acted as a neuroprotective agent against glutamate-induced excitatory damage, and this neuroprotection might be at least partly dependent on the inhibition of excessive autophagy by regulating Wnt/β-catenin signaling.

  20. Cytosolic chloride ion is a key factor in lysosomal acidification and function of autophagy in human gastric cancer cell.

    Science.gov (United States)

    Hosogi, Shigekuni; Kusuzaki, Katsuyuki; Inui, Toshio; Wang, Xiangdong; Marunaka, Yoshinori

    2014-06-01

    The purpose of the present study was to clarify roles of cytosolic chloride ion (Cl(-) ) in regulation of lysosomal acidification [intra-lysosomal pH (pHlys )] and autophagy function in human gastric cancer cell line (MKN28). The MKN28 cells cultured under a low Cl(-) condition elevated pHlys and reduced the intra-lysosomal Cl(-) concentration ([Cl(-) ]lys ) via reduction of cytosolic Cl(-) concentration ([Cl(-) ]c ), showing abnormal accumulation of LC3II and p62 participating in autophagy function (dysfunction of autophagy) accompanied by inhibition of cell proliferation via G0 /G1 arrest without induction of apoptosis. We also studied effects of direct modification of H(+) transport on lysosomal acidification and autophagy. Application of bafilomycin A1 (an inhibitor of V-type H(+) -ATPase) or ethyl isopropyl amiloride [EIPA; an inhibitor of Na(+) /H(+) exchanger (NHE)] elevated pHlys and decreased [Cl(-) ]lys associated with inhibition of cell proliferation via induction of G0 /G1 arrest similar to the culture under a low Cl(-) condition. However, unlike low Cl(-) condition, application of the compound, bafilomycin A1 or EIPA, induced apoptosis associated with increases in caspase 3 and 9 without large reduction in [Cl(-) ]c compared with low Cl(-) condition. These observations suggest that the lowered [Cl(-) ]c primarily causes dysfunction of autophagy without apoptosis via dysfunction of lysosome induced by disturbance of intra-lysosomal acidification. This is the first study showing that cytosolic Cl(-) is a key factor of lysosome acidification and autophagy.

  1. Myotubularin family phosphatase ceMTM3 is required for muscle maintenance by preventing excessive autophagy in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Yu Xiaokun

    2012-10-01

    Full Text Available Abstract Background Autophagy is a ubiquitous cellular process responsible for the bulk degradation of cytoplasmic components through the autophagosomal-lysosomal pathway. In skeletal muscle, autophagy has been regarded as a key regulator for muscle mass maintenance, and its imbalance leads to sarcopenia. However, the underlying mechanism is poorly understood. Results In this study, we demonstrate that ceMTM3, a FYVE-domain containing myotubalarin family phosphatase, is required for the maintenance of muscle fibers by preventing excessive autophagy in Caenorhabditis elegans. Knockdown of ceMTM3 by using feeding-based RNA interference caused loss of muscle fibers accompanied by shortening of muscle cell and body size in aged C. elegans worms. This was preceded by the occurrence of excessive autophagy in the muscle and other tissues, which subsequently resulted in increased lysosomal activity and necrotic cell death. However, knockdown of ceMTM3 did not aggravate the abnormalities of muscle wasting in autophagy-deficient atg-18 mutant worms. Conclusions Our data suggest an important role of ceMTM3 in regulating autophagy and maintaining muscle fibers. This study may have clinical implications for prevention and treatment of sarcopenia.

  2. Cellular contractility requires ubiquitin mediated proteolysis.

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    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.

  3. Dengue Virus Genome Uncoating Requires Ubiquitination

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    Laura A. Byk

    2016-06-01

    Full Text Available The process of genome release or uncoating after viral entry is one of the least-studied steps in the flavivirus life cycle. Flaviviruses are mainly arthropod-borne viruses, including emerging and reemerging pathogens such as dengue, Zika, and West Nile viruses. Currently, dengue virus is one of the most significant human viral pathogens transmitted by mosquitoes and is responsible for about 390 million infections every year around the world. Here, we examined for the first time molecular aspects of dengue virus genome uncoating. We followed the fate of the capsid protein and RNA genome early during infection and found that capsid is degraded after viral internalization by the host ubiquitin-proteasome system. However, proteasome activity and capsid degradation were not necessary to free the genome for initial viral translation. Unexpectedly, genome uncoating was blocked by inhibiting ubiquitination. Using different assays to bypass entry and evaluate the first rounds of viral translation, a narrow window of time during infection that requires ubiquitination but not proteasome activity was identified. In this regard, ubiquitin E1-activating enzyme inhibition was sufficient to stabilize the incoming viral genome in the cytoplasm of infected cells, causing its retention in either endosomes or nucleocapsids. Our data support a model in which dengue virus genome uncoating requires a nondegradative ubiquitination step, providing new insights into this crucial but understudied viral process.

  4. Ubiquitination of specific mitochondrial matrix proteins.

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    Lehmann, Gilad; Ziv, Tamar; Braten, Ori; Admon, Arie; Udasin, Ronald G; Ciechanover, Aaron

    2016-06-17

    Several protein quality control systems in bacteria and/or mitochondrial matrix from lower eukaryotes are absent in higher eukaryotes. These are transfer-messenger RNA (tmRNA), The N-end rule ATP-dependent protease ClpAP, and two more ATP-dependent proteases, HslUV and ClpXP (in yeast). The lost proteases resemble the 26S proteasome and the role of tmRNA and the N-end rule in eukaryotic cytosol is performed by the ubiquitin proteasome system (UPS). Therefore, we hypothesized that the UPS might have substituted these systems - at least partially - in the mitochondrial matrix of higher eukaryotes. Using three independent experimental approaches, we demonstrated the presence of ubiquitinated proteins in the matrix of isolated yeast mitochondria. First, we show that isolated mitochondria contain ubiquitin (Ub) conjugates, which remained intact after trypsin digestion. Second, we demonstrate that the mitochondrial soluble fraction contains Ub-conjugates, several of which were identified by mass spectrometry and are localized to the matrix. Third, using immunoaffinity enrichment by specific antibodies recognizing digested ubiquitinated peptides, we identified a group of Ub-modified matrix proteins. The modification was further substantiated by separation on SDS-PAGE and immunoblots. Last, we attempted to identify the ubiquitin ligase(s) involved, and identified Dma1p as a trypsin-resistant protein in our mitochondrial preparations. Taken together, these data suggest a yet undefined role for the UPS in regulation of the mitochondrial matrix proteins.

  5. A C9ORF72/SMCR8-containing complex regulates ULK1 and plays a dual role in autophagy

    Science.gov (United States)

    Yang, Mei; Liang, Chen; Swaminathan, Kunchithapadam; Herrlinger, Stephanie; Lai, Fan; Shiekhattar, Ramin; Chen, Jian-Fu

    2016-01-01

    The intronic GGGGCC hexanucleotide repeat expansion in chromosome 9 open reading frame 72 (C9ORF72) is a prevalent genetic abnormality identified in both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Smith-Magenis syndrome chromosomal region candidate gene 8 (SMCR8) is a protein with unclear functions. We report that C9ORF72 is a component of a multiprotein complex containing SMCR8, WDR41, and ATG101 (an important regulator of autophagy). The C9ORF72 complex displays guanosine triphosphatase (GTPase) activity and acts as a guanosine diphosphate–guanosine 5′-triphosphate (GDP-GTP) exchange factor (GEF) for RAB39B. We created Smcr8 knockout mice and found that Smcr8 mutant cells exhibit impaired autophagy induction, which is similarly observed in C9orf72 knockdown cells. Mechanistically, SMCR8/C9ORF72 interacts with the key autophagy initiation ULK1 complex and regulates expression and activity of ULK1. The complex has an additional role in regulating later stages of autophagy. Whereas autophagic flux is enhanced in C9orf72 knockdown cells, depletion of Smcr8 results in a reduced flux with an abnormal expression of lysosomal enzymes. Thus, C9ORF72 and SMCR8 have similar functions in modulating autophagy induction by regulating ULK1 and play distinct roles in regulating autophagic flux. PMID:27617292

  6. Nanomaterials, Autophagy, and Lupus Disease.

    Science.gov (United States)

    Bianco, Alberto; Muller, Sylviane

    2016-01-19

    Nanoscale materials hold great promise in the therapeutic field. In particular, as carriers or vectors, they help bioactive molecules reach their primary targets. Furthermore, by themselves, certain nanomaterials-regarded as protective-can modulate particular metabolic pathways that are deregulated in pathological situations. They can also synergistically improve the effects of a payload drug. These properties are the basis of their appeal. However, nanoscale materials can also have intrinsic properties that limit their use, and this is the case for certain types of nanomaterials that influence autophagy. This property can be beneficial in some pathological settings, but in others, if the autophagic flux is already accelerated, it can be deleterious. This is notably the case for systemic lupus erythematosus (SLE) and other chronic inflammatory diseases, including certain neurological diseases. The nanomaterial-autophagy interaction therefore must be treated with caution for therapeutic molecules and peptides that require vectorization for their administration.

  7. HERC 1 Ubiquitin Ligase Mutation Affects Neocortical, CA3 Hippocampal and Spinal Cord Projection Neurons: An Ultrastructural Study.

    Science.gov (United States)

    Ruiz, Rocío; Pérez-Villegas, Eva María; Bachiller, Sara; Rosa, José Luis; Armengol, José Angel

    2016-01-01

    The spontaneous mutation tambaleante is caused by the Gly483Glu substitution in the highly conserved N terminal RCC1-like domain of the HERC1 protein, which leads to the increase of mutated protein levels responsible for cerebellar Purkinje cell death by autophagy. Until now, Purkinje cells have been the only central nervous neurons reported as being targeted by the mutation, and their degeneration elicits an ataxic syndrome in adult mutant mice. However, the ultrastructural analysis performed here demonstrates that signs of autophagy, such as autophagosomes, lysosomes, and altered mitochondria, are present in neocortical pyramidal, CA3 hippocampal pyramidal, and spinal cord motor neurons. The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells. Interestingly, signs of autophagy are absent in both interneurons and neuroglia cells. Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity. Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity.

  8. HERC 1 ubiquitin ligase mutation affects neocortical, CA3 hippocampal and spinal cord projection neurons. An ultrastructural study

    Directory of Open Access Journals (Sweden)

    Rocío eRuiz

    2016-04-01

    Full Text Available The spontaneous mutation tambaleante is caused by the Gly483Glu substitution in the highly conserved N terminal RCC1-like domain of the HERC1 protein, which leads to the increase of mutated protein levels responsible for cerebellar Purkinje cell death by autophagy. Until now, Purkinje cells have been the only central nervous neurons reported as being targeted by the mutation, and their degeneration elicits an ataxic syndrome in adult mutant mice. However, the ultrastructural analysis performed here demonstrates that signs of autophagy, such as autophagosomes, lysosomes, and altered mitochondria, are present in neocortical pyramidal, CA3 hippocampal pyramidal, and spinal cord motor neurons. The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells. Interestingly, signs of autophagy are absent in both interneurons and neuroglia cells. Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity. Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and, hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity.

  9. Ubiquitin Accumulation on Disease Associated Protein Aggregates Is Correlated with Nuclear Ubiquitin Depletion, Histone De-Ubiquitination and Impaired DNA Damage Response

    Science.gov (United States)

    Ben Yehuda, Adi; Risheq, Marwa; Novoplansky, Ofra; Bersuker, Kirill; Kopito, Ron R.; Goldberg, Michal; Brandeis, Michael

    2017-01-01

    Deposition of ubiquitin conjugates on inclusion bodies composed of protein aggregates is a definitive cytopathological hallmark of neurodegenerative diseases. We show that accumulation of ubiquitin on polyQ IB, associated with Huntington’s disease, is correlated with extensive depletion of nuclear ubiquitin and histone de-ubiquitination. Histone ubiquitination plays major roles in chromatin regulation and DNA repair. Accordingly, we observe that cells expressing IB fail to respond to radiomimetic DNA damage, to induce gamma-H2AX phosphorylation and to recruit 53BP1 to damaged foci. Interestingly ubiquitin depletion, histone de-ubiquitination and impaired DNA damage response are not restricted to PolyQ aggregates and are associated with artificial aggregating luciferase mutants. The longevity of brain neurons depends on their capacity to respond to and repair extensive ongoing DNA damage. Impaired DNA damage response, even modest one, could thus lead to premature neuron aging and mortality. PMID:28052107

  10. Coffee induces autophagy in vivo

    Science.gov (United States)

    Pietrocola, Federico; Malik, Shoaib Ahmad; Mariño, Guillermo; Vacchelli, Erika; Senovilla, Laura; Chaba, Kariman; Niso-Santano, Mireia; Maiuri, Maria Chiara; Madeo, Frank; Kroemer, Guido

    2014-01-01

    Epidemiological studies and clinical trials revealed that chronic consumption coffee is associated with the inhibition of several metabolic diseases as well as reduction in overall and cause-specific mortality. We show that both natural and decaffeinated brands of coffee similarly rapidly trigger autophagy in mice. One to 4 h after coffee consumption, we observed an increase in autophagic flux in all investigated organs (liver, muscle, heart) in vivo, as indicated by the increased lipidation of LC3B and the reduction of the abundance of the autophagic substrate sequestosome 1 (p62/SQSTM1). These changes were accompanied by the inhibition of the enzymatic activity of mammalian target of rapamycin complex 1 (mTORC1), leading to the reduced phosphorylation of p70S6K, as well as by the global deacetylation of cellular proteins detectable by immunoblot. Immunohistochemical analyses of transgenic mice expressing a GFP–LC3B fusion protein confirmed the coffee-induced relocation of LC3B to autophagosomes, as well as general protein deacetylation. Altogether, these results indicate that coffee triggers 2 phenomena that are also induced by nutrient depletion, namely a reduction of protein acetylation coupled to an increase in autophagy. We speculate that polyphenols contained in coffee promote health by stimulating autophagy. PMID:24769862

  11. Coffee induces autophagy in vivo.

    Science.gov (United States)

    Pietrocola, Federico; Malik, Shoaib Ahmad; Mariño, Guillermo; Vacchelli, Erika; Senovilla, Laura; Chaba, Kariman; Niso-Santano, Mireia; Maiuri, Maria Chiara; Madeo, Frank; Kroemer, Guido

    2014-01-01

    Epidemiological studies and clinical trials revealed that chronic consumption coffee is associated with the inhibition of several metabolic diseases as well as reduction in overall and cause-specific mortality. We show that both natural and decaffeinated brands of coffee similarly rapidly trigger autophagy in mice. One to 4 h after coffee consumption, we observed an increase in autophagic flux in all investigated organs (liver, muscle, heart) in vivo, as indicated by the increased lipidation of LC3B and the reduction of the abundance of the autophagic substrate sequestosome 1 (p62/SQSTM1). These changes were accompanied by the inhibition of the enzymatic activity of mammalian target of rapamycin complex 1 (mTORC1), leading to the reduced phosphorylation of p70(S6K), as well as by the global deacetylation of cellular proteins detectable by immunoblot. Immunohistochemical analyses of transgenic mice expressing a GFP-LC3B fusion protein confirmed the coffee-induced relocation of LC3B to autophagosomes, as well as general protein deacetylation. Altogether, these results indicate that coffee triggers 2 phenomena that are also induced by nutrient depletion, namely a reduction of protein acetylation coupled to an increase in autophagy. We speculate that polyphenols contained in coffee promote health by stimulating autophagy.

  12. Mechanistically linking age-related diseases and dietary carbohydrate via autophagy and the ubiquitin proteolytic systems

    Science.gov (United States)

    Epidemiological data indicate that consuming diets that deliver sugar to the blood rapidly (called high glycemic index, GI) is associated with enhanced risk for age-related diseases such as cardiovascular disease, type 2 diabetes, cataract and age-related macular degeneration (AMD). These debilities...

  13. Characterization of the autophagy marker protein Atg8 reveals atypical features of autophagy in Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Rahul Navale

    Full Text Available Conventional autophagy is a lysosome-dependent degradation process that has crucial homeostatic and regulatory functions in eukaryotic organisms. As malaria parasites must dispose a number of self and host cellular contents, we investigated if autophagy in malaria parasites is similar to the conventional autophagy. Genome wide analysis revealed a partial autophagy repertoire in Plasmodium, as homologs for only 15 of the 33 yeast autophagy proteins could be identified, including the autophagy marker Atg8. To gain insights into autophagy in malaria parasites, we investigated Plasmodium falciparum Atg8 (PfAtg8 employing techniques and conditions that are routinely used to study autophagy. Atg8 was similarly expressed and showed punctate localization throughout the parasite in both asexual and sexual stages; it was exclusively found in the pellet fraction as an integral membrane protein, which is in contrast to the yeast or mammalian Atg8 that is distributed among cytosolic and membrane fractions, and suggests for a constitutive autophagy. Starvation, the best known autophagy inducer, decreased PfAtg8 level by almost 3-fold compared to the normally growing parasites. Neither the Atg8-associated puncta nor the Atg8 expression level was significantly altered by treatment of parasites with routinely used autophagy inhibitors (cysteine (E64 and aspartic (pepstatin protease inhibitors, the kinase inhibitor 3-methyladenine, and the lysosomotropic agent chloroquine, indicating an atypical feature of autophagy. Furthermore, prolonged inhibition of the major food vacuole protease activity by E64 and pepstatin did not cause accumulation of the Atg8-associated puncta in the food vacuole, suggesting that autophagy is primarily not meant for degradative function in malaria parasites. Atg8 showed partial colocalization with the apicoplast; doxycycline treatment, which disrupts apicoplast, did not affect Atg8 localization, suggesting a role, but not exclusive, in

  14. Ubiquitin Signaling: Extreme Conservation as a Source of Diversity

    Directory of Open Access Journals (Sweden)

    Alice Zuin

    2014-07-01

    Full Text Available Around 2 × 103–2.5 × 103 million years ago, a unicellular organism with radically novel features, ancestor of all eukaryotes, dwelt the earth. This organism, commonly referred as the last eukaryotic common ancestor, contained in its proteome the same functionally capable ubiquitin molecule that all eukaryotic species contain today. The fact that ubiquitin protein has virtually not changed during all eukaryotic evolution contrasts with the high expansion of the ubiquitin system, constituted by hundreds of enzymes, ubiquitin-interacting proteins, protein complexes, and cofactors. Interestingly, the simplest genetic arrangement encoding a fully-equipped ubiquitin signaling system is constituted by five genes organized in an operon-like cluster, and is found in archaea. How did ubiquitin achieve the status of central element in eukaryotic physiology? We analyze here the features of the ubiquitin molecule and the network that it conforms, and propose notions to explain the complexity of the ubiquitin signaling system in eukaryotic cells.

  15. Regulation of DNA double-strand break repair by ubiquitin and ubiquitin-like modifiers

    DEFF Research Database (Denmark)

    Schwertman, Petra; Bekker-Jensen, Simon; Mailand, Niels

    2016-01-01

    DNA double-strand breaks (DSBs) are highly cytotoxic DNA lesions. The swift recognition and faithful repair of such damage is crucial for the maintenance of genomic stability, as well as for cell and organismal fitness. Signalling by ubiquitin, SUMO and other ubiquitin-like modifiers (UBLs......) orchestrates and regulates cellular responses to DSBs at multiple levels, often involving extensive crosstalk between these modifications. Recent findings have revealed compelling insights into the complex mechanisms by which ubiquitin and UBLs regulate protein interactions with DSB sites to promote accurate...

  16. Ubiquitin in signaling and protein quality control

    DEFF Research Database (Denmark)

    Al-Saoudi, Sofie Vincents

    Protein ubiquitylation is an important post-translational modification that holds a variety of cellular functions. This Ph.D. thesis is comprised of two studies, of which one focused on ubiquitylation related to inflammatory signaling, and the other on the role of the ubiquitin-proteasome system......-terminal methionine (M1), and recently, the deubiquitylating enzyme, OTULIN, was discovered to counter LUBAC activity by exclusively cleaving M1-linked ubiquitin chains. We provide the molecular detail of the interaction between the LUBAC subunit, HOIP, and OTULIN. The interaction was mapped to the PUB-domain of HOIP...

  17. Ubiquitination as an efficient molecular strategy employed in salmonella infection.

    Science.gov (United States)

    Narayanan, Lakshmi A; Edelmann, Mariola J

    2014-01-01

    The ubiquitin modification has various functions in the host innate immune system in response to the bacterial infection. To counteract the host immunity, Salmonella can specifically target ubiquitin pathways by its effector proteins. In this review, we describe the multiple facets of ubiquitin function during infection with Salmonella enterica Typhimurium and hypothesize how these studies on the host-pathogen interactions can help to understand the general function of the ubiquitination pathway in the host cell.

  18. Ubiquitination as an efficient molecular strategy employed in Salmonella infection

    Directory of Open Access Journals (Sweden)

    Lakshmi A Narayanan

    2014-11-01

    Full Text Available The protein modification with ubiquitin has various functions in the host innate immune system in response to the bacterial infection. To counteract the host immunity, Salmonella can specifically target ubiquitinating or deubiquitinating enzymes by its effector proteins. In this review we describe the multiple facets of ubiquitin function during infection with Salmonella enterica Typhimurium and hypothesize how these studies on the host-pathogen interactions can help to understand the general function of the ubiquitination pathway in the host cell.

  19. Keeping autophagy in cheCK1

    Science.gov (United States)

    Cheong, Jit Kong; Virshup, David M.

    2016-01-01

    Abstract Mutant RAS-driven cancer cells cope with proliferative stress by increasing basal autophagy to maintain protein/organelle and energy homeostasis. We recently demonstrated that casein kinase 1 alpha (CK1α), a therapeutically tractable enzyme, is critical for fine-tuning the transcriptional regulation of mutant RAS-induced autophagy and the development of mutant RAS-driven cancers. PMID:27314070

  20. Autophagy- An emerging target for melanoma therapy

    Science.gov (United States)

    Ndoye, Abibatou; Weeraratna, Ashani T.

    2016-01-01

    Melanoma accounts for only 5% of all cancers but is the leading cause of skin cancer death due to its high metastatic potential. Patients with metastatic melanoma have a 10-year survival rate of less than 10%. While the clinical landscape for melanoma is evolving rapidly, lack of response to therapies, as well as resistance to therapy remain critical obstacles for treatment of this disease. In recent years, a myriad of therapy resistance mechanisms have been unravelled, one of which is autophagy, the focus of this review. In advanced stages of malignancy, melanoma cells hijack the autophagy machinery in order to alleviate drug-induced and metabolic stress in the tumor microenvironment, thereby promoting resistance to multiple therapies, tumor cell survival, and progression.  Autophagy is an essential cellular process that maintains cellular homeostasis through the recycling of intracellular constituents. Early studies on the role of autophagy in cancer generated controversy as to whether autophagy was pro- or anti-tumorigenic. Currently, there is a consensus that autophagy is tumor-suppressive in the early stages of cancer and tumor-promoting in established tumors.  This review aims to highlight current understandings on the role of autophagy in melanoma malignancy, and specifically therapy resistance; as well as to evaluate recent strategies for therapeutic autophagy modulation. PMID:27583134

  1. Tumor Suppression and Promotion by Autophagy

    Directory of Open Access Journals (Sweden)

    Yenniffer Ávalos

    2014-01-01

    Full Text Available Autophagy is a highly regulated catabolic process that involves lysosomal degradation of proteins and organelles, mostly mitochondria, for the maintenance of cellular homeostasis and reduction of metabolic stress. Problems in the execution of this process are linked to different pathological conditions, such as neurodegeneration, aging, and cancer. Many of the proteins that regulate autophagy are either oncogenes or tumor suppressor proteins. Specifically, tumor suppressor genes that negatively regulate mTOR, such as PTEN, AMPK, LKB1, and TSC1/2 stimulate autophagy while, conversely, oncogenes that activate mTOR, such as class I PI3K, Ras, Rheb, and AKT, inhibit autophagy, suggesting that autophagy is a tumor suppressor mechanism. Consistent with this hypothesis, the inhibition of autophagy promotes oxidative stress, genomic instability, and tumorigenesis. Nevertheless, autophagy also functions as a cytoprotective mechanism under stress conditions, including hypoxia and nutrient starvation, that promotes tumor growth and resistance to chemotherapy in established tumors. Here, in this brief review, we will focus the discussion on this ambiguous role of autophagy in the development and progression of cancer.

  2. Tumor suppression and promotion by autophagy.

    Science.gov (United States)

    Ávalos, Yenniffer; Canales, Jimena; Bravo-Sagua, Roberto; Criollo, Alfredo; Lavandero, Sergio; Quest, Andrew F G

    2014-01-01

    Autophagy is a highly regulated catabolic process that involves lysosomal degradation of proteins and organelles, mostly mitochondria, for the maintenance of cellular homeostasis and reduction of metabolic stress. Problems in the execution of this process are linked to different pathological conditions, such as neurodegeneration, aging, and cancer. Many of the proteins that regulate autophagy are either oncogenes or tumor suppressor proteins. Specifically, tumor suppressor genes that negatively regulate mTOR, such as PTEN, AMPK, LKB1, and TSC1/2 stimulate autophagy while, conversely, oncogenes that activate mTOR, such as class I PI3K, Ras, Rheb, and AKT, inhibit autophagy, suggesting that autophagy is a tumor suppressor mechanism. Consistent with this hypothesis, the inhibition of autophagy promotes oxidative stress, genomic instability, and tumorigenesis. Nevertheless, autophagy also functions as a cytoprotective mechanism under stress conditions, including hypoxia and nutrient starvation, that promotes tumor growth and resistance to chemotherapy in established tumors. Here, in this brief review, we will focus the discussion on this ambiguous role of autophagy in the development and progression of cancer.

  3. Autophagy facilitates secretion and protects against degeneration of the Harderian gland.

    Science.gov (United States)

    Koenig, Ulrich; Fobker, Manfred; Lengauer, Barbara; Brandstetter, Marlene; Resch, Guenter P; Gröger, Marion; Plenz, Gabriele; Pammer, Johannes; Barresi, Caterina; Hartmann, Christine; Rossiter, Heidemarie

    2015-01-01

    The epithelial derived Harderian gland consists of 2 types of secretory cells. The more numerous type A cells are responsible for the secretion of lipid droplets, while type B cells produce dark granules of multilamellar bodies. The process of autophagy is constitutively active in the Harderian gland, as confirmed by our analysis of LC3 processing in GFP-LC3 transgenic mice. This process is compromised by epithelial deletion of Atg7. Morphologically, the Atg7 mutant glands are hypotrophic and degenerated, with highly vacuolated cells and pyknotic nuclei. The mutant glands accumulate lipid droplets coated with PLIN2 (perilipin 2) and contain deposits of cholesterol, ubiquitinated proteins, SQSTM1/p62 (sequestosome 1) positive aggregates and other metabolic products such as porphyrin. Immunofluorescence stainings show that distinct cells strongly aggregate both proteins and lipids. Electron microscopy of the Harderian glands reveals that its organized structure is compromised, and the presence of large intracellular lipid droplets and heterologous aggregates. We attribute the occurrence of large vacuoles to a malfunction in the formation of multilamellar bodies found in the less abundant type B Harderian gland cells. This defect causes the formation of large tertiary lysosomes of heterologous content and is accompanied by the generation of tight lamellar stacks of endoplasmic reticulum in a pseudo-crystalline form. To test the hypothesis that lipid and protein accumulation is the cause for the degeneration in autophagy-deficient Harderian glands, epithelial cells were treated with a combination of the proteasome inhibitor and free fatty acids, to induce aggregation of misfolded proteins and lipid accumulation, respectively. The results show that lipid accumulation indeed enhanced the toxicity of misfolded proteins and that this was even more pronounced in autophagy-deficient cells. Thus, we conclude autophagy controls protein and lipid catabolism and anabolism to

  4. Ubiquitination as an efficient molecular strategy employed in salmonella infection

    Science.gov (United States)

    The ubiquitin modification has various functions in the host innate immune system in response to the bacterial infection. To counteract the host immunity, Salmonella can specifically target ubiquitin pathways by its effector proteins. In this review, we describe the multiple facets of ubiquitin func...

  5. Principles of ubiquitin and SUMO modifications in DNA repair

    NARCIS (Netherlands)

    Bergink, Steven; Jentsch, Stefan

    2009-01-01

    With the discovery in the late 1980s that the DNA-repair gene RAD6 encodes a ubiquitin-conjugating enzyme, it became clear that protein modification by ubiquitin conjugation has a much broader significance than had previously been assumed. Now, two decades later, ubiquitin and its cousin SUMO are im

  6. Mechanisms of mitochondria and autophagy crosstalk.

    Science.gov (United States)

    Rambold, Angelika S; Lippincott-Schwartz, Jennifer

    2011-12-01

    Autophagy is a cellular survival pathway that recycles intracellular components to compensate for nutrient depletion and ensures the appropriate degradation of organelles. Mitochondrial number and health are regulated by mitophagy, a process by which excessive or damaged mitochondria are subjected to autophagic degradation. Autophagy is thus a key determinant for mitochondrial health and proper cell function. Mitophagic malfunction has been recently proposed to contribute to progressive neuronal loss in Parkinson's disease. In addition to autophagy's significance in mitochondrial integrity, several lines of evidence suggest that mitochondria can also substantially influence the autophagic process. The mitochondria's ability to influence and be influenced by autophagy places both elements (mitochondria and autophagy) in a unique position where defects in one or the other system could increase the risk to various metabolic and autophagic related diseases.

  7. Stress management by autophagy: Implications for chemoresistance.

    Science.gov (United States)

    Huang, Zhao; Zhou, Li; Chen, Zhibin; Nice, Edouard C; Huang, Canhua

    2016-07-01

    Development of chemoresistance, which limits the efficiency of anticancer agents, has long been a major problem in cancer therapy and urgently needs to be solved to improve clinical outcomes. Factors contributing to chemoresistance are various, but a key factor is the cell's capability for stress management. Autophagy, a favored survival strategy that organisms employ to get over many kinds of stress, is emerging as a crucial player in drug resistance. It has been shown that autophagy facilitates the resistance of tumor cells to anticancer agents, and abrogation of autophagy could be therapeutically beneficial in some cases, suggesting autophagy could be a promising target for cancer treatments. Thus, defining the roles of autophagy in chemoresistance, and the mechanisms involved, will be critical to enhance the efficiency of chemotherapy and develop novel anticancer strategy interventions.

  8. Emerging connections between RNA and autophagy

    DEFF Research Database (Denmark)

    Frankel, Lisa B; Lubas, Michal; Lund, Anders H

    2016-01-01

    Macroautophagy/autophagy is a key catabolic process, essential for maintaining cellular homeostasis and survival through the removal and recycling of unwanted cellular material. Emerging evidence has revealed intricate connections between the RNA and autophagy research fields. While a majority...... of studies have focused on protein, lipid and carbohydrate catabolism via autophagy, accumulating data supports the view that several types of RNA and associated ribonucleoprotein complexes are specifically recruited to phagophores (precursors to autophagosomes) and subsequently degraded in the lysosome....../vacuole. Moreover, recent studies have revealed a substantial number of novel autophagy regulators with RNA-related functions, indicating roles for RNA and associated proteins not only as cargo, but also as regulators of this process. In this review, we discuss widespread evidence of RNA catabolism via autophagy...

  9. Dichloroacetate induces protective autophagy in LoVo cells: involvement of cathepsin D/thioredoxin-like protein 1 and Akt-mTOR-mediated signaling.

    Science.gov (United States)

    Gong, F; Peng, X; Sang, Y; Qiu, M; Luo, C; He, Z; Zhao, X; Tong, A

    2013-11-07

    Dichloroacetate (DCA) is an inhibitor of pyruvate dehydrogenase kinase (PDK), and recently it has been shown as a promising nontoxic antineoplastic agent. In this study, we demonstrated that DCA could induce autophagy in LoVo cells, which were confirmed by the formation of autophagosomes, appearance of punctate patterns of LC3 immunoreactivity and activation of autophagy associated proteins. Moreover, autophagy inhibition by 3-methyladenine (3-MA) or Atg7 siRNA treatment can significantly enhance DCA-induced apoptosis. To determine the underlying mechanism of DCA-induced autophagy, target identification using drug affinity responsive target stability (DARTS) coupled with ESI-Q-TOF MS/MS analysis were utilized to profile differentially expressed proteins between control and DCA-treated LoVo cells. As a result, Cathepsin D (CTSD) and thioredoxin-like protein 1 (TXNL1) were identified with significant alterations compared with control. Further study indicated that DCA treatment significantly promoted abnormal reactive oxygen species (ROS) production. On the other hand, DCA-triggered autophagy could be attenuated by N-acetyl cysteine (NAC), a ROS inhibitor. Finally, we demonstrated that the Akt-mTOR signaling pathway, a major negative regulator of autophagy, was suppressed by DCA treatment. To our knowledge, it was the first study to show that DCA induced protective autophagy in LoVo cells, and the potential mechanisms were involved in ROS imbalance and Akt-mTOR signaling pathway suppression.

  10. Endosome-lysosomes, ubiquitin and neurodegeneration.

    Science.gov (United States)

    Mayer, R J; Tipler, C; Arnold, J; Laszlo, L; Al-Khedhairy, A; Lowe, J; Landon, M

    1996-01-01

    Before the advent of ubiquitin immunochemistry and immunogold electron microscopy, there was no known intracellular molecular commonality between neurodegenerative diseases. The application of antibodies which primarily detect ubiquitin protein conjugates has shown that all of the human and animal idiopathic and transmissible chronic neurodegenerative diseases, (including Alzheimer's disease (AD), Lewy body disease (LBD), amyotrophic lateral sclerosis (ALS), Creutzfeldt-Jakob disease (CJD) and scrapie) are related by some form of intraneuronal inclusion which contains ubiquitin protein conjugates. In addition, disorders such as Alzheimer's disease, CJD and sheep scrapie, are characterised by deposits of amyloid, arising through incomplete breakdown of membrane proteins which may be associated with cytoskeletal reorganisation. Although our knowledge about these diseases is increasing, they remain largely untreatable. Recently, attention has focused on the mechanisms of production of different types of amyloid and the likely involvement within cells of the endosome-lysosome system, organelles which are immuno-positive for ubiquitin protein conjugates. These organelles may be 'bioreactor' sites for the unfolding and partial degradation of membrane proteins to generate the amyloid materials or their precursors which subsequently become expelled from the cell, or are released from dead cells, and accumulate as pathological entities. Such common features of the disease processes give new direction to therapeutic intervention.

  11. A novel effect of thalidomide and its analogs: suppression of cereblon ubiquitination enhances ubiquitin ligase function

    OpenAIRE

    Liu, Yaobin; Huang, Xiangao; He, Xian; Zhou, Yanqing; Jiang, Xiaogang; Chen-Kiang, Selina; Jaffrey, Samie R.; Xu, Guoqiang

    2015-01-01

    The immunomodulatory drug (IMiD) thalidomide and its structural analogs lenalidomide and pomalidomide are highly effective in treating clinical indications. Thalidomide binds to cereblon (CRBN), a substrate receptor of the cullin-4 really interesting new gene (RING) E3 ligase complex. Here, we examine the effect of thalidomide and its analogs on CRBN ubiquitination and its functions in human cell lines. We find that the ubiquitin modification of CRBN includes K48-linked polyubiquitin chains a...

  12. Cytochrome P450 3A Conjugation to Ubiquitin in a Process Distinct from Classical Ubiquitination Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Zangar, Richard C.(BATTELLE (PACIFIC NW LAB)); Kimzey, Amy L.(ASSOC WESTERN UNIVERSITY); Okita, Janice R.(Washington State University); Wunschel, David S.(BATTELLE (PACIFIC NW LAB)); Edwards, Robert J.(Imperial College School of Medical, Hammersmith Campus); Kim, Hyesook (Wayne State University); Okita, Richard T.(Washington State University)

    2001-12-01

    We characterize a novel microsome system that forms high-molecular-mass (HMM) CYP3A, CYP2E1, and ubiquitin conjugates, but does not alter CYP4A or most other microsomal proteins. The formation of the HMM bands was observed in hepatic microsomes isolated from rats treated 1 week or more with high doses (50 mg/kg/day) of nicardipine, clotrimazole, or pregnenolone 16alpha-carbonitrile, but not microsomes from control, dexamethasone-, nifedipine-, or diltiazem-treated rats. Extensive washing of the microsomes to remove loosely attached proteins or cytosolic contaminants did not prevent the conjugation reaction. In contrast to prototypical ubiquitination pathways, this reaction did not require addition of ubiquitin, ATP, Mg(2+), or cytosol. Addition of cytosol did result in the degradation of the HMM CYP3A bands in a process that was not blocked by proteasome inhibitors. Immunoprecipitated CYP3A contained HMM ubiquitin. Even so, mass spectrometric analysis of tryptic peptides indicated that the HMM CYP3A was in molar excess to ubiquitin, suggesting that the formation of the HMM CYP3A may have resulted from conjugation to itself or a diffuse pool of ubiquitinated proteins already present in the microsomes. Addition of CYP3A substrates inhibited the formation of the HMM CYP3A and the cytosol-dependent degradation of HMM CYP3A. These results suggest that after extended periods of elevated CYP3A expression, microsomal factors are induced that catalyze the formation of HMM CYP3A conjugates that contain ubiquitin. This conjugation reaction, however, seems to be distinct from the classical ubiquitination pathway but may be related to the substrate-dependent stabilization of CYP3A observed in vivo.

  13. Copper-triggered aggregation of ubiquitin.

    Science.gov (United States)

    Arnesano, Fabio; Scintilla, Simone; Calò, Vincenza; Bonfrate, Elena; Ingrosso, Chiara; Losacco, Maurizio; Pellegrino, Teresa; Rizzarelli, Enrico; Natile, Giovanni

    2009-09-16

    Neurodegenerative disorders share common features comprising aggregation of misfolded proteins, failure of the ubiquitin-proteasome system, and increased levels of metal ions in the brain. Protein aggregates within affected cells often contain ubiquitin, however no report has focused on the aggregation propensity of this protein. Recently it was shown that copper, differently from zinc, nickel, aluminum, or cadmium, compromises ubiquitin stability and binds to the N-terminus with 0.1 micromolar affinity. This paper addresses the role of copper upon ubiquitin aggregation. In water, incubation with Cu(II) leads to formation of spherical particles that can progress from dimers to larger conglomerates. These spherical oligomers are SDS-resistant and are destroyed upon Cu(II) chelation or reduction to Cu(I). In water/trifluoroethanol (80:20, v/v), a mimic of the local decrease in dielectric constant experienced in proximity to a membrane surface, ubiquitin incubation with Cu(II) causes time-dependent changes in circular dichroism and Fourier-transform infrared spectra, indicative of increasing beta-sheet content. Analysis by atomic force and transmission electron microscopy reveals, in the given order, formation of spherical particles consistent with the size of early oligomers detected by gel electrophoresis, clustering of these particles in straight and curved chains, formation of ring structures, growth of trigonal branches from the rings, coalescence of the trigonal branched structures in a network. Notably, none of these ubiquitin aggregates was positive to tests for amyloid and Cu(II) chelation or reduction produced aggregate disassembly. The early formed Cu(II)-stabilized spherical oligomers, when reconstituted in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes and in POPC planar bilayers, form annular and pore-like structures, respectively, which are common to several neurodegenerative disorders including Parkinson's, Alzheimer's, amyotrophic

  14. Copper-triggered aggregation of ubiquitin.

    Directory of Open Access Journals (Sweden)

    Fabio Arnesano

    Full Text Available Neurodegenerative disorders share common features comprising aggregation of misfolded proteins, failure of the ubiquitin-proteasome system, and increased levels of metal ions in the brain. Protein aggregates within affected cells often contain ubiquitin, however no report has focused on the aggregation propensity of this protein. Recently it was shown that copper, differently from zinc, nickel, aluminum, or cadmium, compromises ubiquitin stability and binds to the N-terminus with 0.1 micromolar affinity. This paper addresses the role of copper upon ubiquitin aggregation. In water, incubation with Cu(II leads to formation of spherical particles that can progress from dimers to larger conglomerates. These spherical oligomers are SDS-resistant and are destroyed upon Cu(II chelation or reduction to Cu(I. In water/trifluoroethanol (80:20, v/v, a mimic of the local decrease in dielectric constant experienced in proximity to a membrane surface, ubiquitin incubation with Cu(II causes time-dependent changes in circular dichroism and Fourier-transform infrared spectra, indicative of increasing beta-sheet content. Analysis by atomic force and transmission electron microscopy reveals, in the given order, formation of spherical particles consistent with the size of early oligomers detected by gel electrophoresis, clustering of these particles in straight and curved chains, formation of ring structures, growth of trigonal branches from the rings, coalescence of the trigonal branched structures in a network. Notably, none of these ubiquitin aggregates was positive to tests for amyloid and Cu(II chelation or reduction produced aggregate disassembly. The early formed Cu(II-stabilized spherical oligomers, when reconstituted in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC liposomes and in POPC planar bilayers, form annular and pore-like structures, respectively, which are common to several neurodegenerative disorders including Parkinson's, Alzheimer

  15. Wwp2, an E3 Ubiquitin Ligase That Targets Transcription Factor Oct-4 for Ubiquitination

    Institute of Scientific and Technical Information of China (English)

    HuiMingXu; BingLiao; QianJunZhang; BeiBeiWang; Hui,Li; XiaoMinZhong; HuiZhenSheng; YingXinZhao; YingMingZhao; YingJin

    2005-01-01

    The POU transcription factor Oct-4 is a master regulator affecting the fate of pluripotent embryonic stem cells. However, the precise mechanisms by which the activation and expression of Oct-4 are regulated still remain to be elucidated. We describe here a novel murine ubiquitin ligase, Wwp2, that specifically interacts with Oct-4 and promotes its ubiquitination both in vivo and in vitro. Remarkably, the expression of a catalytically inactive point mutant of Wwp2 abolishes Oct-4 ubiquitination. Moreover, Wwp2 promotes Oct-4 degradation in the presence of overexpressed ubiquitin. The degradation is blocked by treatment with proteasome inhibitor. Fusion of a single ubiquitin to Oct-4 inactivates its transcriptional activity in a heterologous Oct-4-driven reporter system. Furthermore, overexpression of Wwp2 in embryonic stem cells significantly reduces the Oct-4-transcriptional activities. Collectively, we demonstrate for the first time that Oct-4 can be posttranslationatly modified by ubiquitination and that this modification dramatically suppresses its transcriptional activity. These results reveal that the functional status of Oct-4, in addition to its expression level, dictates its transcriptional activity, and the results open up a new avenue to understand how Oct-4 defines the fate of embryonic stem cells.

  16. MDM2 E3 ubiquitin ligase mediates UT-A1 urea transporter ubiquitination and degradation.

    Science.gov (United States)

    Chen, Guangping; Huang, Haidong; Fröhlich, Otto; Yang, Yuan; Klein, Janet D; Price, S Russ; Sands, Jeff M

    2008-11-01

    UT-A1 is the primary urea transporter in the apical plasma membrane responsible for urea reabsorption in the inner medullary collecting duct. Although the physiological function of UT-A1 has been well established, the molecular mechanisms that regulate its activity are less well understood. Analysis of the UT-A1 amino acid sequence revealed a potential MDM2 E3 ubiquitin ligase-binding motif in the large intracellular loop of UT-A1, suggesting that UT-A1 urea transporter protein may be regulated by the ubiquitin-proteasome pathway. Here, we report that UT-A1 is ubiquitinated and degraded by the proteasome but not the lysosome proteolytic pathway. Inhibition of proteasome activity causes UT-A1 cell surface accumulation and concomitantly increases urea transport activity. UT-A1 interacts directly with MDM2; the binding site is located in the NH2-terminal p53-binding region of MDM2. MDM2 mediates UT-A1 ubiquitination both in vivo and in vitro. Overexpression of MDM2 promotes UT-A1 degradation. The mechanism is likely to be physiologically important as UT-A1 ubiquitination was identified in kidney inner medullary tissue. The ubiquitin-proteasome degradation pathway provides an important novel mechanism for UT-A1 regulation.

  17. Functional constraints on adaptive evolution of protein ubiquitination sites

    Science.gov (United States)

    Lu, Liang; Li, Yang; Liu, Zhongyang; Liang, Fengji; Guo, Feifei; Yang, Shuai; Wang, Dan; He, Yangzhige; Xiong, Jianghui; Li, Dong; He, Fuchu

    2017-01-01

    It is still unclear whether there exist functional constraints on the evolution of protein ubiquitination sites, because most previous studies regarded all protein ubiquitination sites as a whole or only focused on limited structural properties. We tried to clarify the relation between functional constraints and ubiquitination sites evolution. We investigated the evolutionary conservation of human ubiquitination sites in a broad evolutionary scale from G. gorilla to S. pombe, and we found that in organisms originated after the divergence of vertebrate, ubiquitination sites are more conserved than their flanking regions, while the opposite tendency is observed before this divergence time. By grouping the ubiquitination proteins into different functional categories, we confirm that many functional constraints like certain molecular functions, protein tissue expression specificity and protein connectivity in protein-protein interaction network enhance the evolutionary conservation of ubiquitination sites. Furthermore, by analyzing the gains of ubiquitination sites at different divergence time and their functional characters, we validate that the emergences of ubiquitination sites at different evolutionary time were also affected by the uncovered functional constraints. The above results suggest that functional constraints on the adaptive evolution of ubiquitination sites increase the opportunity for ubiquitination to synthetically regulate various cellular and developmental processes during evolution. PMID:28054638

  18. Cooperativity of the SUMO and Ubiquitin Pathways in Genome Stability

    Directory of Open Access Journals (Sweden)

    Minghua Nie

    2016-02-01

    Full Text Available Covalent attachment of ubiquitin (Ub or SUMO to DNA repair proteins plays critical roles in maintaining genome stability. These structurally related polypeptides can be viewed as distinct road signs, with each being read by specific protein interaction motifs. Therefore, via their interactions with selective readers in the proteome, ubiquitin and SUMO can elicit distinct cellular responses, such as directing DNA lesions into different repair pathways. On the other hand, through the action of the SUMO-targeted ubiquitin ligase (STUbL family proteins, ubiquitin and SUMO can cooperate in the form of a hybrid signal. These mixed SUMO-ubiquitin chains recruit “effector” proteins such as the AAA+ ATPase Cdc48/p97-Ufd1-Npl4 complex that contain both ubiquitin and SUMO interaction motifs. This review will summarize recent key findings on collaborative and distinct roles that ubiquitin and SUMO play in orchestrating DNA damage responses.

  19. Autophagy is induced through the ROS-TP53-DRAM1 pathway in response to mitochondrial protein synthesis inhibition.

    Science.gov (United States)

    Xie, Xiaolei; Le, Li; Fan, Yanxin; Lv, Lin; Zhang, Junjie

    2012-07-01

    Mitoribosome in mammalian cells is responsible for synthesis of 13 mtDNA-encoded proteins, which are integral parts of four mitochondrial respiratory chain complexes (I, III, IV and V). ERAL1 is a nuclear-encoded GTPase important for the formation of the 28S small mitoribosomal subunit. Here, we demonstrate that knockdown of ERAL1 by RNA interference inhibits mitochondrial protein synthesis and promotes reactive oxygen species (ROS) generation, leading to autophagic vacuolization in HeLa cells. Cells that lack ERAL1 expression showed a significant conversion of LC3-I to LC3-II and an enhanced accumulation of autophagic vacuoles carrying the LC3 marker, all of which were blocked by the autophagy inhibitor 3-MA as well as by the ROS scavenger NAC. Inhibition of mitochondrial protein synthesis either by ERAL1 siRNA or chloramphenicol (CAP), a specific inhibitor of mitoribosomes, induced autophagy in HTC-116 TP53 (+/+) cells, but not in HTC-116 TP53 (-/-) cells, indicating that tumor protein 53 (TP53) is essential for the autophagy induction. The ROS elevation resulting from mitochondrial protein synthesis inhibition induced TP53 expression at transcriptional levels by enhancing TP53 promoter activity, and increased TP53 protein stability by suppressing TP53 ubiquitination through MAPK14/p38 MAPK-mediated TP53 phosphorylation. Upregulation of TP53 and its downstream target gene DRAM1, but not CDKN1A/p21, was required for the autophagy induction in ERAL1 siRNA or CAP-treated cells. Altogether, these data indicate that autophagy is induced through the ROS-TP53-DRAM1 pathway in response to mitochondrial protein synthesis inhibition.

  20. Organ-specific quality control of plant peroxisomes is mediated by autophagy.

    Science.gov (United States)

    Yoshimoto, Kohki; Shibata, Michitaro; Kondo, Maki; Oikawa, Kazusato; Sato, Mayuko; Toyooka, Kiminori; Shirasu, Ken; Nishimura, Mikio; Ohsumi, Yoshinori

    2014-03-15

    Peroxisomes are essential organelles that are characterized by the possession of enzymes that produce hydrogen peroxide (H2O2) as part of their normal catalytic cycle. During the metabolic process, peroxisomal proteins are inevitably damaged by H2O2 and the integrity of the peroxisomes is impaired. Here, we show that autophagy, an intracellular process for vacuolar degradation, selectively degrades dysfunctional peroxisomes. Marked accumulation of peroxisomes was observed in the leaves but not roots of autophagy-related (ATG)-knockout Arabidopsis thaliana mutants. The peroxisomes in leaf cells contained markedly increased levels of catalase in an insoluble and inactive aggregate form. The chemically inducible complementation system in ATG5-knockout Arabidopsis provided the evidence that these accumulated peroxisomes were delivered to vacuoles for degradation by autophagy. Interestingly, autophagosomal membrane structures specifically recognized the abnormal peroxisomes at the site of the aggregates. Thus, autophagy is essential for the quality control of peroxisomes in leaves and for proper plant development under natural growth conditions.

  1. Autophagy Protects against Colitis by the Maintenance of Normal Gut Microflora and Secretion of Mucus.

    Science.gov (United States)

    Tsuboi, Koichiro; Nishitani, Mayo; Takakura, Atsushi; Imai, Yasuyuki; Komatsu, Masaaki; Kawashima, Hiroto

    2015-08-14

    Genome-wide association studies of inflammatory bowel diseases identified susceptible loci containing an autophagy-related gene. However, the role of autophagy in the colon, a major affected area in inflammatory bowel diseases, is not clear. Here, we show that colonic epithelial cell-specific autophagy-related gene 7 (Atg7) conditional knock-out (cKO) mice showed exacerbation of experimental colitis with more abundant bacterial invasion into the colonic epithelium. Quantitative PCR analysis revealed that cKO mice had abnormal microflora with an increase of some genera. Consistently, expression of antimicrobial or antiparasitic peptides such as angiogenin-4, Relmβ, intelectin-1, and intelectin-2 as well as that of their inducer cytokines was significantly reduced in the cKO mice. Furthermore, secretion of colonic mucins that function as a mucosal barrier against bacterial invasion was also significantly diminished in cKO mice. Taken together, our results indicate that autophagy in colonic epithelial cells protects against colitis by the maintenance of normal gut microflora and secretion of mucus.

  2. Autophagy in human embryonic stem cells.

    Directory of Open Access Journals (Sweden)

    Thien Tra

    Full Text Available Autophagy (macroautophagy is a degradative process that involves the sequestration of cytosolic material including organelles into double membrane vesicles termed autophagosomes for delivery to the lysosome. Autophagy is essential for preimplantation development of mouse embryos and cavitation of embryoid bodies. The precise roles of autophagy during early human embryonic development, remain however largely uncharacterized. Since human embryonic stem cells constitute a unique model system to study early human embryogenesis we investigated the occurrence of autophagy in human embryonic stem cells. We have, using lentiviral transduction, established multiple human embryonic stem cell lines that stably express GFP-LC3, a fluorescent marker for the autophagosome. Each cell line displays both a normal karyotype and pluripotency as indicated by the presence of cell types representative of the three germlayers in derived teratomas. GFP expression and labelling of autophagosomes is retained after differentiation. Baseline levels of autophagy detected in cultured undifferentiated hESC were increased or decreased in the presence of rapamycin and wortmannin, respectively. Interestingly, autophagy was upregulated in hESCs induced to undergo differentiation by treatment with type I TGF-beta receptor inhibitor SB431542 or removal of MEF secreted maintenance factors. In conclusion we have established hESCs capable of reporting macroautophagy and identify a novel link between autophagy and early differentiation events in hESC.

  3. Autophagy in granular corneal dystrophy type 2.

    Science.gov (United States)

    Choi, Seung-Il; Kim, Eung Kweon

    2016-03-01

    Autophagy is a lysosomal degradative process that is essential for cellular homeostasis and metabolic stress adaptation. Defective autophagy is involved in the pathogenesis of many diseases including granular corneal dystrophy type 2 (GCD2). GCD2 is an autosomal dominant disorder caused by substitution of histidine for arginine at codon 124 (R124H) in the transforming growth factor β-induced gene (TGFBI) on chromosome 5q31. Transforming growth factor β-induced protein (TGFBIp) is degraded by autophagy, but mutant-TGFBIp accumulates in autophagosomes and/or lysosomes, despite significant activation of basal autophagy, in GCD2 corneal fibroblasts. Furthermore, inhibition of autophagy induces cell death of GCD2 corneal fibroblasts through active caspase-3. As there is currently no pharmacological treatment for GCD2, development of novel therapies is required. A potential strategy for preventing cytoplasmic accumulation of mutant-TGFBIp in GCD2 corneal fibroblasts is to enhance mutant-TGFBIp degradation. This could be achieved by activation of the autophagic pathway. Here, we will consider the role and the potential therapeutic benefits of autophagy in GCD2, with focus on TGFBIp degradation, in light of the recently established role of autophagy in protein degradation.

  4. Guidelines for monitoring autophagy in Caenorhabditis elegans.

    Science.gov (United States)

    Zhang, Hong; Chang, Jessica T; Guo, Bin; Hansen, Malene; Jia, Kailiang; Kovács, Attila L; Kumsta, Caroline; Lapierre, Louis R; Legouis, Renaud; Lin, Long; Lu, Qun; Meléndez, Alicia; O'Rourke, Eyleen J; Sato, Ken; Sato, Miyuki; Wang, Xiaochen; Wu, Fan

    2015-01-01

    The cellular recycling process of autophagy has been extensively characterized with standard assays in yeast and mammalian cell lines. In multicellular organisms, numerous external and internal factors differentially affect autophagy activity in specific cell types throughout the stages of organismal ontogeny, adding complexity to the analysis of autophagy in these metazoans. Here we summarize currently available assays for monitoring the autophagic process in the nematode C. elegans. A combination of measuring levels of the lipidated Atg8 ortholog LGG-1, degradation of well-characterized autophagic substrates such as germline P granule components and the SQSTM1/p62 ortholog SQST-1, expression of autophagic genes and electron microscopy analysis of autophagic structures are presently the most informative, yet steady-state, approaches available to assess autophagy levels in C. elegans. We also review how altered autophagy activity affects a variety of biological processes in C. elegans such as L1 survival under starvation conditions, dauer formation, aging, and cell death, as well as neuronal cell specification. Taken together, C. elegans is emerging as a powerful model organism to monitor autophagy while evaluating important physiological roles for autophagy in key developmental events as well as during adulthood.

  5. Autophagy in lung disease pathogenesis and therapeutics

    Directory of Open Access Journals (Sweden)

    Stefan W. Ryter

    2015-04-01

    Full Text Available Autophagy, a cellular pathway for the degradation of damaged organelles and proteins, has gained increasing importance in human pulmonary diseases, both as a modulator of pathogenesis and as a potential therapeutic target. In this pathway, cytosolic cargos are sequestered into autophagosomes, which are delivered to the lysosomes where they are enzymatically degraded and then recycled as metabolic precursors. Autophagy exerts an important effector function in the regulation of inflammation, and immune system functions. Selective pathways for autophagic degradation of cargoes may have variable significance in disease pathogenesis. Among these, the autophagic clearance of bacteria (xenophagy may represent a crucial host defense mechanism in the pathogenesis of sepsis and inflammatory diseases. Our recent studies indicate that the autophagic clearance of mitochondria, a potentially protective program, may aggravate the pathogenesis of chronic obstructive pulmonary disease by activating cell death programs. We report similar findings with respect to the autophagic clearance of cilia components, which can contribute to airways dysfunction in chronic lung disease. In certain diseases such as pulmonary hypertension, autophagy may confer protection by modulating proliferation and cell death. In other disorders, such as idiopathic pulmonary fibrosis and cystic fibrosis, impaired autophagy may contribute to pathogenesis. In lung cancer, autophagy has multiple consequences by limiting carcinogenesis, modulating therapeutic effectiveness, and promoting tumor cell survival. In this review we highlight the multiple functions of autophagy and its selective autophagy subtypes that may be of significance to the pathogenesis of human disease, with an emphasis on lung disease and therapeutics.

  6. Autophagy in Mycobacterium tuberculosis and HIV infections

    Directory of Open Access Journals (Sweden)

    Lucile eEspert

    2015-06-01

    Full Text Available Human Immunodeficiency Virus (HIV and Mycobacterium tuberculosis (M.tb are among the most lethal human pathogens worldwide, each being responsible for around 1.5 million deaths annually. Moreover, synergy between acquired immune deficiency syndrome (AIDS and tuberculosis (TB has turned HIV/M.tb co-infection into a major public health threat in developing countries. In the past decade, autophagy, a lysosomal catabolic process, has emerged as a major host immune defense mechanism against infectious agents like M.tb and HIV. Nevertheless, in some instances, autophagy machinery appears to be instrumental for HIV infection. Finally, there is mounting evidence that both pathogens deploy various countermeasures to thwart autophagy. This mini-review proposes an overview of the roles and regulations of autophagy in HIV and M.tb infections with an emphasis on microbial factors. We also discuss the role of autophagy manipulation in the context of HIV/M.tb co-infection. In future, a comprehensive understanding of autophagy interaction with these pathogens will be critical for development of autophagy-based prophylactic and therapeutic interventions for AIDS and TB.

  7. Autophagy: for better or for worse

    Institute of Scientific and Technical Information of China (English)

    Ellen Wirawan; Tom Vanden Berghe; Saskia Lippens; Patrizia Agostinis; Peter Vandenabeele

    2012-01-01

    Autophagy is a lysosomal degradation pathway that degrades damaged or superfluous cell components into basic biomolecules,which are then recycled back into the cytosol.In this respect,autophagy drives a flow of biomolecules in a continuous degradation-regeneration cycle.Autophagy is generally considered a pro-survival mechanism protecting cells under stress or poor nutrient conditions.Current research clearly shows that autophagy fulfills numerous functions in vital biological processes.It is implicated in development,differentiation,innate and adaptive immunity,ageing and cell death.In addition,accumulating evidence demonstrates interesting links between autophagy and several human diseases and tumor development.Therefore,autophagy seems to be an important player in the life and death of cells and organisms.Despite the mounting knowledge about autophagy,the mechanisms through which the autophagic machinery regulates these diverse processes are not entirely understood.In this review,we give a comprehensive overview of the autophagic signaling pathway,its role in general cellular processes and its connection to cell death.In addition,we present a brief overview of the possible contribution of defective autophagic signaling to disease.

  8. Inhibition of hsp70 by methylene blue affects signaling protein function and ubiquitination and modulates polyglutamine protein degradation.

    Science.gov (United States)

    Wang, Adrienne M; Morishima, Yoshihiro; Clapp, Kelly M; Peng, Hwei-Ming; Pratt, William B; Gestwicki, Jason E; Osawa, Yoichi; Lieberman, Andrew P

    2010-05-21

    The Hsp90/Hsp70-based chaperone machinery regulates the activity and degradation of many signaling proteins. Cycling with Hsp90 stabilizes client proteins, whereas Hsp70 interacts with chaperone-dependent E3 ubiquitin ligases to promote protein degradation. To probe these actions, small molecule inhibitors of Hsp70 would be extremely useful; however, few have been identified. Here we test the effects of methylene blue, a recently described inhibitor of Hsp70 ATPase activity, in three well established systems of increasing complexity. First, we demonstrate that methylene blue inhibits the ability of the purified Hsp90/Hsp70-based chaperone machinery to enable ligand binding by the glucocorticoid receptor and show that this effect is due to specific inhibition of Hsp70. Next, we establish that ubiquitination of neuronal nitric-oxide synthase by the native ubiquitinating system of reticulocyte lysate is dependent upon both Hsp70 and the E3 ubiquitin ligase CHIP and is blocked by methylene blue. Finally, we demonstrate that methylene blue impairs degradation of the polyglutamine expanded androgen receptor, an Hsp90 client mutated in spinal and bulbar muscular atrophy. In contrast, degradation of an amino-terminal fragment of the receptor, which lacks the ligand binding domain and, therefore, is not a client of the Hsp90/Hsp70-based chaperone machinery, is enhanced through homeostatic induction of autophagy that occurs when Hsp70-dependent proteasomal degradation is inhibited by methylene blue. Our data demonstrate the utility of methylene blue in defining Hsp70-dependent functions and reveal divergent effects on polyglutamine protein degradation depending on whether the substrate is an Hsp90 client.

  9. Intrinsically disordered regions in autophagy proteins.

    Science.gov (United States)

    Mei, Yang; Su, Minfei; Soni, Gaurav; Salem, Saeed; Colbert, Christopher L; Sinha, Sangita C

    2014-04-01

    Autophagy is an essential eukaryotic pathway required for cellular homeostasis. Numerous key autophagy effectors and regulators have been identified, but the mechanism by which they carry out their function in autophagy is not fully understood. Our rigorous bioinformatic analysis shows that the majority of key human autophagy proteins include intrinsically disordered regions (IDRs), which are sequences lacking stable secondary and tertiary structure; suggesting that IDRs play an important, yet hitherto uninvestigated, role in autophagy. Available crystal structures corroborate the absence of structure in some of these predicted IDRs. Regions of orthologs equivalent to the IDRs predicted in the human autophagy proteins are poorly conserved, indicating that these regions may have diverse functions in different homologs. We also show that IDRs predicted in human proteins contain several regions predicted to facilitate protein-protein interactions, and delineate the network of proteins that interact with each predicted IDR-containing autophagy protein, suggesting that many of these interactions may involve IDRs. Lastly, we experimentally show that a BCL2 homology 3 domain (BH3D), within the key autophagy effector BECN1 is an IDR. This BH3D undergoes a dramatic conformational change from coil to α-helix upon binding to BCL2s, with the C-terminal half of this BH3D constituting a binding motif, which serves to anchor the interaction of the BH3D to BCL2s. The information presented here will help inform future in-depth investigations of the biological role and mechanism of IDRs in autophagy proteins.

  10. The dual role of autophagy under hypoxia-involvement of interaction between autophagy and apoptosis.

    Science.gov (United States)

    Li, Mengmeng; Tan, Jin; Miao, Yuyang; Lei, Ping; Zhang, Qiang

    2015-06-01

    Hypoxia is one of severe cellular stress and it is well known to be associated with a worse outcome since a lack of oxygen accelerates the induction of apoptosis. Autophagy, an important and evolutionarily conserved mechanism for maintaining cellular homeostasis, is closely related to the apoptosis caused by hypoxia. Generally autophagy blocks the induction of apoptosis and inhibits the activation of apoptosis-associated caspase which could reduce cellular injury. However, in special cases, autophagy or autophagy-relevant proteins may help to induce apoptosis, which could aggravate cell damage under hypoxia condition. In addition, the activation of apoptosis-related proteins-caspase can also degrade autophagy-related proteins, such as Atg3, Atg4, Beclin1 protein, inhibiting autophagy. Although the relationship between autophagy and apoptosis has been known for rather complex for more than a decade, the underlying regulatory mechanisms have not been clearly understood. This short review discusses and summarizes the dual role of autophagy and the interaction and molecular regulatory mechanisms between autophagy and apoptosis under hypoxia.

  11. Effect of Autophagy Over Liver Diseases

    Institute of Scientific and Technical Information of China (English)

    Dong-qian Yi; Xue-feng Yang; Duan-fang Liao; Qing Wu; Nian Fu; Yang Hu; Ting Cao

    2016-01-01

    Abstract In recent years, increasingly evidences show that autophagy plays an important role in the pathogenesis and development of liver diseases, and the relationship between them has increasingly become a focus of concern. Autophagy refers to the process through which the impaired organelles, misfolded protein, and intruding microorganisms is degraded by lysosomes to maintain stability inside cells. This article states the effect of autophagy on liver diseases (hepatic fibrosis, fatty liver, viral hepatitis, and liver cancer), which aims to provide a new direction for the treatment of liver diseases.

  12. Urine - abnormal color

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003139.htm Urine - abnormal color To use the sharing features on this page, please enable JavaScript. The usual color of urine is straw-yellow. Abnormally colored urine ...

  13. Autophagy mitigates metabolic stress and genome damage in mammary tumorigenesis

    Science.gov (United States)

    Karantza-Wadsworth, Vassiliki; Patel, Shyam; Kravchuk, Olga; Chen, Guanghua; Mathew, Robin; Jin, Shengkan; White, Eileen

    2007-01-01

    Autophagy is a catabolic process involving self-digestion of cellular organelles during starvation as a means of cell survival; however, if it proceeds to completion, autophagy can lead to cell death. Autophagy is also a haploinsufficient tumor suppressor mechanism for mammary tumorigenesis, as the essential autophagy regulator beclin1 is monoallelically deleted in breast carcinomas. However, the mechanism by which autophagy suppresses breast cancer remains elusive. Here we show that allelic loss of beclin1 and defective autophagy sensitized mammary epithelial cells to metabolic stress and accelerated lumen formation in mammary acini. Autophagy defects also activated the DNA damage response in vitro and in mammary tumors in vivo, promoted gene amplification, and synergized with defective apoptosis to promote mammary tumorigenesis. Therefore, we propose that autophagy limits metabolic stress to protect the genome, and that defective autophagy increases DNA damage and genomic instability that ultimately facilitate breast cancer progression. PMID:17606641

  14. Oxidative stress-induced autophagy: Role in pulmonary toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Malaviya, Rama [Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854 (United States); Laskin, Jeffrey D. [Department of Environmental and Occupational Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854 (United States); Laskin, Debra L., E-mail: laskin@eohsi.rutgers.edu [Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854 (United States)

    2014-03-01

    Autophagy is an evolutionarily conserved catabolic process important in regulating the turnover of essential proteins and in elimination of damaged organelles and protein aggregates. Autophagy is observed in the lung in response to oxidative stress generated as a consequence of exposure to environmental toxicants. Whether autophagy plays role in promoting cell survival or cytotoxicity is unclear. In this article recent findings on oxidative stress-induced autophagy in the lung are reviewed; potential mechanisms initiating autophagy are also discussed. A better understanding of autophagy and its role in pulmonary toxicity may lead to the development of new strategies to treat lung injury associated with oxidative stress. - Highlights: • Exposure to pulmonary toxicants is associated with oxidative stress. • Oxidative stress is known to induce autophagy. • Autophagy is upregulated in the lung following exposure to pulmonary toxicants. • Autophagy may be protective or pathogenic.

  15. The Parkinson's disease-associated genes ATP13A2 and SYT11 regulate autophagy via a common pathway.

    Science.gov (United States)

    Bento, Carla F; Ashkenazi, Avraham; Jimenez-Sanchez, Maria; Rubinsztein, David C

    2016-06-09

    Forms of Parkinson's disease (PD) are associated with lysosomal and autophagic dysfunction. ATP13A2, which is mutated in some types of early-onset Parkinsonism, has been suggested as a regulator of the autophagy-lysosome pathway. However, little is known about the ATP13A2 effectors and how they regulate this pathway. Here we show that ATP13A2 depletion negatively regulates another PD-associated gene (SYT11) at both transcriptional and post-translational levels. Decreased SYT11 transcription is controlled by a mechanism dependent on MYCBP2-induced ubiquitination of TSC2, which leads to mTORC1 activation and decreased TFEB-mediated transcription of SYT11, while increased protein turnover is regulated by SYT11 ubiquitination and degradation. Both mechanisms account for a decrease in the levels of SYT11, which, in turn, induces lysosomal dysfunction and impaired degradation of autophagosomes. Thus, we propose that ATP13A2 and SYT11 form a new functional network in the regulation of the autophagy-lysosome pathway, which is likely to contribute to forms of PD-associated neurodegeneration.

  16. Ubiquitin reference technique and its use in ubiquitin-lacking prokaryotes.

    Directory of Open Access Journals (Sweden)

    Konstantin Piatkov

    Full Text Available In a pulse-chase assay, the in vivo degradation of a protein is measured through a brief labeling of cells with, for example, a radioactive amino acid, followed by cessation of labeling and analysis of cell extracts prepared at different times afterward ("chase", using immunoprecipitation, electrophoresis and autoradiography of a labeled protein of interest. A conventional pulse-chase assay is fraught with sources of data scatter, as the efficacy of labeling and immunoprecipitation can vary, and sample volumes can vary as well. The ubiquitin reference technique (URT, introduced in 1996, addresses these problems. In eukaryotes, a DNA-encoded linear fusion of ubiquitin to another protein is cleaved by deubiquitylases at the ubiquitin-protein junction. A URT assay uses a fusion in which the ubiquitin moiety is located between a downstream polypeptide (test protein and an upstream polypeptide (a long-lived reference protein. The cotranslational cleavage of a URT fusion by deubiquitylases after the last residue of ubiquitin produces, at the initially equimolar ratio, a test protein with a desired N-terminal residue and a reference protein containing C-terminal ubiquitin moiety. In addition to being more accurate than pulse-chases without a reference, URT makes it possible to detect and measure the degradation of a test protein during the pulse (before the chase. Because prokaryotes, including Gram-negative bacteria such as, for example, Escherichia coli and Vibrio vulnificus, lack the ubiquitin system, the use of URT in such cells requires ectopic expression of a deubiquitylase. We describe designs and applications of plasmid vectors that coexpress, in bacteria, both a URT-type fusion and Ubp1, a deubiquitylase of the yeast Saccharomyces cerevisiae. This single-plasmid approach extends the accuracy-enhancing URT assay to studies of protein degradation in prokaryotes.

  17. Autophagy as a Stress Response Pathway in the Immune System.

    Science.gov (United States)

    Bhattacharya, Abhisek; Eissa, N Tony

    2015-01-01

    Macroautophagy, hereafter, referred to as autophagy, has long been regarded as a housekeeping pathway involved in intracellular degradation and energy recycling. These housekeeping and homeostatic functions are especially important during cellular stress, such as periods of nutrient deprivation. However, importance of autophagy extends far beyond its degradative functions. Recent evidence shows that autophagy plays an essential role in development, organization and functions of the immune system, and defects in autophagy lead to several diseases, including cancer and autoimmunity. In the immune system, autophagy is important in regulation of the innate and adaptive immune responses. This review focuses on the roles of autophagy in the adaptive immune system. We first introduce the autophagy pathway and provide a brief description of the major molecular players involved in autophagy. We then discuss the importance of autophagy as a stress integrator mechanism and provide relevant examples of this role of autophagy in adaptive immune cells. Then we proceed to describe how autophagy regulates development, activation and functions of different adaptive immune cells. In these contexts, we mention both degradative and non-degradative roles of autophagy, and illustrate their importance. We also discuss role of autophagy in antigen presenting cells, which play critical roles in the activation of adaptive immune cells. Further, we describe how autophagy regulates functions of different adaptive immune cells during infection, inflammation and autoimmunity.

  18. Genetic background alters the severity and onset of neuromuscular disease caused by the loss of ubiquitin-specific protease 14 (usp14.

    Directory of Open Access Journals (Sweden)

    Andrea G Marshall

    Full Text Available In this study, we identified and characterized an N-ethyl-N-nitrosourea (ENU induced mutation in Usp14 (nmf375 that leads to adult-onset neurological disease. The nmf375 mutation causes aberrant splicing of Usp14 mRNA, resulting in a 95% reduction in USP14. We previously showed that loss of USP14 in ataxia (ax (J mice results in reduced ubiquitin levels, motor endplate disease, Purkinje cell axonal dystrophy and decreased hippocampal paired pulse facilitation (PPF during the first 4-6 weeks of life, and early postnatal lethality by two months of age. Although the loss of USP14 is comparable between the nmf375 and ax (J mice, the nmf375 mice did not exhibit these ax (J developmental abnormalities. However, by 12 weeks of age the nmf375 mutants present with ubiquitin depletion and motor endplate disease, indicating a continual role for USP14-mediated regulation of ubiquitin pools and neuromuscular junction (NMJ structure in adult mice. The observation that motor endplate disease was only seen after ubiquitin depletion suggests that the preservation of NMJ structure requires the stable maintenance of synaptic ubiquitin pools. Differences in genetic background were shown to affect ubiquitin expression and dramatically alter the phenotypes caused by USP14 deficiency.

  19. Nanomaterial-modulated autophagy: underlying mechanisms and functional consequences.

    Science.gov (United States)

    Zheng, Wei; Wei, Min; Li, Song; Le, Weidong

    2016-06-01

    Autophagy is an essential lysosome-dependent process that controls the quality of the cytoplasm and maintains cellular homeostasis, and dysfunction of this protein degradation system is correlated with various disorders. A growing body of evidence suggests that nanomaterials (NMs) have autophagy-modulating effects, thus predicting a valuable and promising application potential of NMs in the diagnosis and treatment of autophagy-related diseases. NMs exhibit unique physical, chemical and biofunctional properties, which may endow NMs with capabilities to modulate autophagy via various mechanisms. The present review highlights the impacts of various NMs on autophagy and their functional consequences. The possible underlying mechanisms for NM-modulated autophagy are also discussed.

  20. A novel effect of thalidomide and its analogs: suppression of cereblon ubiquitination enhances ubiquitin ligase function.

    Science.gov (United States)

    Liu, Yaobin; Huang, Xiangao; He, Xian; Zhou, Yanqing; Jiang, Xiaogang; Chen-Kiang, Selina; Jaffrey, Samie R; Xu, Guoqiang

    2015-12-01

    The immunomodulatory drug (IMiD) thalidomide and its structural analogs lenalidomide and pomalidomide are highly effective in treating clinical indications. Thalidomide binds to cereblon (CRBN), a substrate receptor of the cullin-4 really interesting new gene (RING) E3 ligase complex. Here, we examine the effect of thalidomide and its analogs on CRBN ubiquitination and its functions in human cell lines. We find that the ubiquitin modification of CRBN includes K48-linked polyubiquitin chains and that thalidomide blocks the formation of CRBN-ubiquitin conjugates. Furthermore, we show that ubiquitinated CRBN is targeted for proteasomal degradation. Treatment of human myeloma cell lines such as MM1.S, OPM2, and U266 with thalidomide (100 μM) and its structural analog lenalidomide (10 μM) results in stabilization of CRBN and elevation of CRBN protein levels. This in turn leads to the reduced level of CRBN target proteins and enhances the sensitivity of human multiple myeloma cells to IMiDs. Our results reveal a novel mechanism by which thalidomide and its analogs modulate the CRBN function in cells. Through inhibition of CRBN ubiquitination, thalidomide and its analogs allow CRBN to accumulate, leading to the increased cullin-4 RING E3 ligase-mediated degradation of target proteins.

  1. Mammalian Autophagy: How Does It Work?

    Science.gov (United States)

    Bento, Carla F; Renna, Maurizio; Ghislat, Ghita; Puri, Claudia; Ashkenazi, Avraham; Vicinanza, Mariella; Menzies, Fiona M; Rubinsztein, David C

    2016-06-02

    Autophagy is a conserved intracellular pathway that delivers cytoplasmic contents to lysosomes for degradation via double-membrane autophagosomes. Autophagy substrates include organelles such as mitochondria, aggregate-prone proteins that cause neurodegeneration and various pathogens. Thus, this pathway appears to be relevant to the pathogenesis of diverse diseases, and its modulation may have therapeutic value. Here, we focus on the cell and molecular biology of mammalian autophagy and review the key proteins that regulate the process by discussing their roles and how these may be modulated by posttranslational modifications. We consider the membrane-trafficking events that impact autophagy and the questions relating to the sources of autophagosome membrane(s). Finally, we discuss data from structural studies and some of the insights these have provided.

  2. Cereblon is recruited to aggresome and shows cytoprotective effect against ubiquitin-proteasome system dysfunction.

    Science.gov (United States)

    Sawamura, Naoya; Wakabayashi, Satoru; Matsumoto, Kodai; Yamada, Haruka; Asahi, Toru

    2015-09-04

    Cereblon (CRBN) is encoded by a candidate gene for autosomal recessive nonsyndromic intellectual disability (ID). The nonsense mutation, R419X, causes deletion of 24 amino acids at the C-terminus of CRBN, leading to mild ID. Although abnormal CRBN function may be associated with ID disease onset, its cellular mechanism is still unclear. Here, we examine the role of CRBN in aggresome formation and cytoprotection. In the presence of a proteasome inhibitor, exogenous CRBN formed perinuclear inclusions and co-localized with aggresome markers. Endogenous CRBN also formed perinuclear inclusions under the same condition. Treatment with a microtubule destabilizer or an inhibitor of the E3 ubiquitin ligase activity of CRBN blocked formation of CRBN inclusions. Biochemical analysis showed CRBN containing inclusions were high-molecular weight, ubiquitin-positive. CRBN overexpression in cultured cells suppressed cell death induced by proteasome inhibitor. Furthermore, knockdown of endogenous CRBN in cultured cells increased cell death induced by proteasome inhibitor, compared with control cells. Our results show CRBN is recruited to aggresome and has functional roles in cytoprotection against ubiquitin-proteasome system impaired condition.

  3. Mechanisms of mitochondria and autophagy crosstalk

    OpenAIRE

    Rambold, Angelika S; Lippincott-Schwartz, Jennifer

    2011-01-01

    Autophagy is a cellular survival pathway that recycles intracellular components to compensate for nutrient depletion and ensures the appropriate degradation of organelles. Mitochondrial number and health are regulated by mitophagy, a process by which excessive or damaged mitochondria are subjected to autophagic degradation. Autophagy is thus a key determinant for mitochondrial health and proper cell function. Mitophagic malfunction has been recently proposed to contribute to progressive neuro...

  4. RUFY4: Immunity piggybacking on autophagy?

    Science.gov (United States)

    Terawaki, Seigo; Camosseto, Voahirana; Pierre, Philippe; Gatti, Evelina

    2016-01-01

    Although autophagy is a highly conserved mechanism among species and cell types, few are the molecules involved with the autophagic process that display cell- or tissue- specific expression. We have unraveled the positive regulatory role on autophagy of RUFY4 (RUN and FYVE domain containing 4), which is expressed in subsets of immune cells, including dendritic cells (DCs). DCs orchestrate the eradication of pathogens by coordinating the action of the different cell types involved in microbe recognition and destruction during the immune response. To fulfill this function, DC display particular regulation of their endocytic and autophagy pathways in response to the immune environment. Autophagy flux is downmodulated in DCs upon microbe sensing, but is remarkably augmented, when cells are differentiated in the presence of the pleiotropic cytokine IL4 (interleukin 4). From gene expression studies aimed at comparing the impact of IL4 on DC differentiation, we identified RUFY4, as a novel regulator that augments autophagy flux and, when overexpressed, induces drastic membrane redistribution and strongly tethers lysosomes. RUFY4 is therefore one of the few known positive regulators of autophagy that is expressed in a cell-specific manner or under specific immunological conditions associated with IL4 expression such as allergic asthma.

  5. Extracellular Vesicles and Autophagy in Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Tianyang Gao

    2016-01-01

    Full Text Available Osteoarthritis (OA is a type of chronic joint disease that is characterized by the degeneration and loss of articular cartilage and hyperplasia of the synovium and subchondral bone. There is reasonable knowledge about articular cartilage physiology, biochemistry, and chondrocyte metabolism. However, the etiology and pathogenesis of OA remain unclear and need urgent clarification to guide the early diagnosis and treatment of OA. Extracellular vesicles (EVs are small membrane-linking particles that are released from cells. In recent decades, several special biological properties have been found in EV, especially in terms of cartilage. Autophagy plays a critical role in the regulation of cellular homeostasis. Likewise, more and more research has gradually focused on the effect of autophagy on chondrocyte proliferation and function in OA. The synthesis and release of EV are closely associated with autophagy. At the same time, both EV and autophagy play a role in OA development. Based on the mechanism of EV and autophagy in OA development, EV may be beneficial in the early diagnosis of OA; on the other hand, the combination of EV and autophagy-related regulatory drugs may provide insight into possible OA therapeutic strategies.

  6. Autophagy in stem and progenitor cells.

    Science.gov (United States)

    Rodolfo, Carlo; Di Bartolomeo, Sabrina; Cecconi, Francesco

    2016-02-01

    Autophagy is a highly conserved cellular process, responsible for the degradation and recycling of damaged and/or outlived proteins and organelles. This is the major cellular pathway, acting throughout the formation of cytosolic vesicles, called autophagosomes, for the delivering to lysosome. Recycling of cellular components through autophagy is a crucial step for cell homeostasis as well as for tissue remodelling during development. Impairment of this process has been related to the pathogenesis of various diseases, such as cancer and neurodegeneration, to the response to bacterial and viral infections, and to ageing. The ability of stem cells to self-renew and differentiate into the mature cells of the body renders this unique type of cell highly crucial to development and tissue renewal, not least in various diseases. During the last two decades, extensive knowledge about autophagy roles and regulation in somatic cells has been acquired; however, the picture about the role and the regulation of autophagy in the different types of stem cells is still largely unknown. Autophagy is a major player in the quality control and maintenance of cellular homeostasis, both crucial factors for stem cells during an organism's life. In this review, we have highlighted the most significant advances in the comprehension of autophagy regulation in embryonic and tissue stem cells, as well as in cancer stem cells and induced pluripotent cells.

  7. Control of autophagy by oncogenes and tumor suppressor genes.

    Science.gov (United States)

    Maiuri, M C; Tasdemir, E; Criollo, A; Morselli, E; Vicencio, J M; Carnuccio, R; Kroemer, G

    2009-01-01

    Multiple oncogenes (in particular phosphatidylinositol 3-kinase, PI3K; activated Akt1; antiapoptotic proteins from the Bcl-2 family) inhibit autophagy. Similarly, several tumor suppressor proteins (such as BH3-only proteins; death-associated protein kinase-1, DAPK1; the phosphatase that antagonizes PI3K, PTEN; tuberous sclerosic complex 1 and 2, TSC1 and TSC2; as well as LKB1/STK11) induce autophagy, meaning that their loss reduces autophagy. Beclin-1, which is required for autophagy induction acts as a haploinsufficient tumor suppressor protein, and other essential autophagy mediators (such as Atg4c, UVRAG and Bif-1) are bona fide oncosuppressors. One of the central tumor suppressor proteins, p53 exerts an ambiguous function in the regulation of autophagy. Within the nucleus, p53 can act as an autophagy-inducing transcription factor. Within the cytoplasm, p53 exerts a tonic autophagy-inhibitory function, and its degradation is actually required for the induction of autophagy. The role of autophagy in oncogenesis and anticancer therapy is contradictory. Chronic suppression of autophagy may stimulate oncogenesis. However, once a tumor is formed, autophagy inhibition may be a therapeutic goal for radiosensitization and chemosensitization. Altogether, the current state-of-the art suggests a complex relationship between cancer and deregulated autophagy that must be disentangled by further in-depth investigation.

  8. Triptolide Promotes the Clearance of α-Synuclein by Enhancing Autophagy in Neuronal Cells.

    Science.gov (United States)

    Hu, Guanzheng; Gong, Xiaoli; Wang, Le; Liu, Mengru; Liu, Yang; Fu, Xia; Wang, Wei; Zhang, Ting; Wang, Xiaomin

    2016-03-09

    Parkinson's disease (PD) is an aging-associated neurodegenerative disease with a characteristic feature of α-synuclein accumulation. Point mutations (A53T, A30P) that increase the aggregation propensity of α-synuclein result in familial early onset PD. The abnormal metabolism of α-synuclein results in aberrant level changes of α-synuclein in PD. In pathological conditions, α-synuclein is degraded mainly by the autophagy-lysosome pathway. Triptolide (T10) is a monomeric compound isolated from a traditional Chinese herb. Our group demonstrated for the first time that T10 possesses potent neuroprotective properties both in vitro and in vivo PD models. In the present study, we reported T10 as a potent autophagy inducer in neuronal cells, which helped to promote the clearance of various forms of α-synuclein in neuronal cells. We transfected neuronal cells with A53T mutant (A53T) or wild-type (WT) α-synuclein plasmids and found T10 attenuated the cytotoxicity induced by pathogenic A53T α-synuclein overexpression. We observed that T10 significantly reduced both A53T and WT α-synuclein level in neuronal cell line, as well as in primary cultured cortical neurons. Excluding the changes of syntheses, secretion, and aggregation of α-synuclein, we further added autophagy inhibitor or proteasome inhibitor with T10, and we noticed that T10 promoted the clearance of α-synuclein mainly by the autophagic pathway. Lastly, we observed increased autophagy marker LC3-II expression and autophagosomes by GFP-LC3-II accumulation and ultrastructural characterization. However, the lysosome activity and cell viability were not modulated by T10. Our study revealed that T10 could induce autophagy and promote the clearance of both WT and A53T α-synuclein in neurons. These results provide evidence of T10 as a promising mean to treat PD and other neurodegenerative diseases by reducing pathogenic proteins in neurons.

  9. Ubiquitination as an Efficient Molecular Strategy Employed in Salmonella Infection

    OpenAIRE

    Narayanan, Lakshmi A.; Edelmann, Mariola J.

    2014-01-01

    The protein modification with ubiquitin has various functions in the host innate immune system in response to the bacterial infection. To counteract the host immunity, Salmonella can specifically target ubiquitinating or deubiquitinating enzymes by its effector proteins. In this review we describe the multiple facets of ubiquitin function during infection with Salmonella enterica Typhimurium and hypothesize how these studies on the host-pathogen interactions can help to understand the general...

  10. Assessing ubiquitination of viral proteins: lessons from flavivirus NS5

    OpenAIRE

    Taylor, R. Travis; Best, Sonja M.

    2011-01-01

    Ubiquitin (Ub) conjugation to a substrate protein is a widely used cellular mechanism for control of protein stability and function, modulation of signal transduction pathways and antiviral responses. Identification and characterization of ubiquitinated viral proteins is an important step in understanding novel mechanisms of viral protein regulation as well as elucidating cellular antiviral strategies. Here we describe a protocol to easily detect and characterize the ubiquitination status of ...

  11. The protein ATG16L1 suppresses inflammatory cytokines induced by the intracellular sensors Nod1 and Nod2 in an autophagy-independent manner.

    Science.gov (United States)

    Sorbara, Matthew T; Ellison, Lisa K; Ramjeet, Mahendrasingh; Travassos, Leonardo H; Jones, Nicola L; Girardin, Stephen E; Philpott, Dana J

    2013-11-14

    The peptidoglycan sensor Nod2 and the autophagy protein ATG16L1 have been linked to Crohn's disease (CD). Although Nod2 and the related sensor, Nod1, direct ATG16L1 to initiate anti-bacterial autophagy, whether ATG16L1 affects Nod-driven inflammation has not been examined. Here, we uncover an unanticipated autophagy-independent role for ATG16L1 in negatively regulating Nod-driven inflammatory responses. Knockdown of ATG16L1 expression, but not that of ATG5 or ATG9a, specifically enhanced Nod-driven cytokine production. In addition, autophagy-incompetent truncated forms of ATG16L1 regulated Nod-driven cytokine responses. Mechanistically, we demonstrated that ATG16L1 interfered with poly-ubiquitination of the Rip2 adaptor and recruitment of Rip2 into large signaling complexes. The CD-associated allele of ATG16L1 was impaired in its ability to regulate Nod-driven inflammatory responses. Overall, these results suggest that ATG16L1 is critical for Nod-dependent regulation of cytokine responses and that disruption of this Nod1- or Nod2-ATG16L1 signaling axis could contribute to the chronic inflammation associated with CD.

  12. Brucella Melitensis 16M Regulates the Effect of AIR Domain on Inflammatory Factors, Autophagy, and Apoptosis in Mouse Macrophage through the ROS Signaling Pathway

    Science.gov (United States)

    Li, Tiansen; Xu, Yafang; Liu, Laizhen; Huang, Meiling; Wang, Zhen; Tong, Zhixia; Zhang, Hui; Guo, Fei; Chen, Chuangfu

    2016-01-01

    Brucellosis is a highly contagious zoonosis caused by Brucella. Brucella can invade and persist inside host cells, which results in chronic infection. We constructed AIR interference and overexpression lentiviruses to acquire AIR interference, overexpression, and rescue stable expression cell lines. We also established a Brucella melitensis 16M-infected macrophage model, which was treated with either the vehicle control or NAC (ROS scavenger N-acetylcysteine (NAC) for 0, 3, 6, 12, and 24 h. Confocal laser microscopy, transmission electron microscopy, fluorescence quantitative PCR, flow cytometry, ELISA, and Western blot were used to detect inflammation, cell autophagy and apoptosis-related protein expression levels, ROS levels, and the distribution of mitochondria. It was found that after interference and overexpression of AIR, ROS release was significantly changed, and mitochondria became abnormally aggregated. B. melitensis 16M activated the NLRP3/AIM2 inflammatory complex, and induced RAW264.7 cells to secrete IL-1β and IL-18 through the ROS pathway. B. melitensis 16M also altered autophagy-related gene expression, increased autophagy activity, and induced cell apoptosis through the ROS pathway. The results showed that after B. melitensis 16M infection, ROS induced apoptosis, inflammation, and autophagy while AIR inhibited autophagosome maturation and autophagy initiation. Autophagy negatively regulated the activation of inflammasomes and prevented inflammation from occurring. In addition, mitophagy could promote cell apoptosis. PMID:27907115

  13. Modulation of inflammation by autophagy: consequences for Crohn's disease.

    NARCIS (Netherlands)

    Plantinga, T.S.; Joosten, L.A.B.; Meer, J.W.M. van der; Netea, M.G.

    2012-01-01

    Autophagy, the cellular machinery for targeting intracellular components for lysosomal degradation, is critically involved in the host defence to pathogenic microorganisms. Recent studies have unveiled several aspects of the immune response that are regulated by autophagy, including antigen presenta

  14. Autophagy in acute brain injury: feast, famine, or folly?

    Science.gov (United States)

    Smith, Craig M; Chen, Yaming; Sullivan, Mara L; Kochanek, Patrick M; Clark, Robert S B

    2011-07-01

    In the central nervous system, increased autophagy has now been reported after traumatic brain and spinal cord injury, cerebral ischemia, intracerebral hemorrhage, and seizures. This increase in autophagy could be physiologic, converting damaged or dysfunctional proteins, lipids, and/or organelles to their amino acid and fatty acid components for recycling. On the other hand, this increase in autophagy could be supraphysiologic, perhaps consuming and eliminating functional proteins, lipids, and/or organelles as well. Whether an increase in autophagy is beneficial (feast) or detrimental (famine) in brain likely depends on both the burden of intracellular substrate targeted for autophagy and the capacity of the cell's autophagic machinery. Of course, increased autophagy observed after brain injury could also simply be an epiphenomenon (folly). These divergent possibilities have clear ramifications for designing therapeutic strategies targeting autophagy after acute brain injury and are the subject of this review. This article is part of a Special Issue entitled "Autophagy and protein degradation in neurological diseases."

  15. Ubiquitin chain conformation regulates recognition and activity of interacting proteins.

    Science.gov (United States)

    Ye, Yu; Blaser, Georg; Horrocks, Mathew H; Ruedas-Rama, Maria J; Ibrahim, Shehu; Zhukov, Alexander A; Orte, Angel; Klenerman, David; Jackson, Sophie E; Komander, David

    2012-12-13

    Mechanisms of protein recognition have been extensively studied for single-domain proteins, but are less well characterized for dynamic multidomain systems. Ubiquitin chains represent a biologically important multidomain system that requires recognition by structurally diverse ubiquitin-interacting proteins. Ubiquitin chain conformations in isolation are often different from conformations observed in ubiquitin-interacting protein complexes, indicating either great dynamic flexibility or extensive chain remodelling upon binding. Using single-molecule fluorescence resonance energy transfer, we show that Lys 63-, Lys 48- and Met 1-linked diubiquitin exist in several distinct conformational states in solution. Lys 63- and Met 1-linked diubiquitin adopt extended 'open' and more compact 'closed' conformations, and ubiquitin-binding domains and deubiquitinases (DUBs) select pre-existing conformations. By contrast, Lys 48-linked diubiquitin adopts predominantly compact conformations. DUBs directly recognize existing conformations, but may also remodel ubiquitin chains to hydrolyse the isopeptide bond. Disruption of the Lys 48-diubiquitin interface changes conformational dynamics and affects DUB activity. Hence, conformational equilibria in ubiquitin chains provide an additional layer of regulation in the ubiquitin system, and distinct conformations observed in differently linked polyubiquitin may contribute to the specificity of ubiquitin-interacting proteins.

  16. The human otubain2-ubiquitin structure provides insights into the cleavage specificity of poly-ubiquitin-linkages.

    Directory of Open Access Journals (Sweden)

    Mikael Altun

    Full Text Available Ovarian tumor domain containing proteases cleave ubiquitin (Ub and ubiquitin-like polypeptides from proteins. Here we report the crystal structure of human otubain 2 (OTUB2 in complex with a ubiquitin-based covalent inhibitor, Ub-Br2. The ubiquitin binding mode is oriented differently to how viral otubains (vOTUs bind ubiquitin/ISG15, and more similar to yeast and mammalian OTUs. In contrast to OTUB1 which has exclusive specificity towards Lys48 poly-ubiquitin chains, OTUB2 cleaves different poly-Ub linked chains. N-terminal tail swapping experiments between OTUB1 and OTUB2 revealed how the N-terminal structural motifs in OTUB1 contribute to modulating enzyme activity and Ub-chain selectivity, a trait not observed in OTUB2, supporting the notion that OTUB2 may affect a different spectrum of substrates in Ub-dependent pathways.

  17. The DUB-ious lack of ALIS in Salmonella infection: a Salmonella deubiquitinase regulates the autophagy of protein aggregates.

    Science.gov (United States)

    Thomas, Mair; Mesquita, Francisco S; Holden, David W

    2012-12-01

    Ubiquitinated aggregates are formed in eukaryotic cells in response to several external stimuli, including exposure to bacterial lipopolysaccharide (LPS). Although Salmonella enterica serovar Typhimurium (S. Typhimurium) LPS has been shown to induce aggresome-like induced structures (ALIS) in macrophages, these have not been described in S. Typhimurium-infected macrophages. Given that LPS is present in infection, this suggests that S. Typhimurium might suppress the formation of ALIS. We found that S. Typhimurium induces the formation of ubiquitinated aggregates in epithelial cells and macrophages, but that their presence is masked by the deubiquitinase (DUB) activity of the S. Typhimurium virulence protein, SseL. SseL deubiquitinates SQSTM1/p62-bound proteins found in S. Typhimurium-induced aggregates and ALIS, and reduces the recruitment of autophagic components. While the functions of ALIS and other ubiquitinated aggregates remain unclear, they serve to sequester cytosolic proteins under a variety of stress conditions and are suggested to be involved in host immune defense. During infection, the deubiquitinase activity of SseL reduces autophagic flux in infected cells and favors bacterial replication. This is a new example of how a bacterial pathogen counteracts the autophagy pathway through the action of a translocated virulence protein.

  18. The Ca{sup 2+} channel TRPML3 specifically interacts with the mammalian ATG8 homologue GATE16 to regulate autophagy

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Suzy; Kim, Hyun Jin, E-mail: kimhyunjin@skku.edu

    2014-01-03

    Highlights: •Split-ubiquitin MY2H screen identified GATE16 as an interacting protein of TRPML3. •TRPML3 specifically binds to a mammalian ATG8 homologue GATE16, not to LC3B. •The interaction of TRPML3 with GATE16 facilitates autophagosome formation. •GATE16 is expressed in both autophagosome and extra-autophagosomal compartments. -- Abstract: TRPML3 is a Ca{sup 2+} permeable cation channel expressed in multiple intracellular compartments. Although TRPML3 is implicated in autophagy, how TRPML3 can regulate autophagy is not understood. To search interacting proteins with TRPML3 in autophagy, we performed split-ubiquitin membrane yeast two-hybrid (MY2H) screening with TRPML3-loop as a bait and identified GATE16, a mammalian ATG8 homologue. GST pull-down assay revealed that TRPML3 and TRPML3-loop specifically bind to GATE16, not to LC3B. Co-immunoprecipitation (co-IP) experiments showed that TRPML3 and TRPML3-loop pull down only the lipidated form of GATE16, indicating that the interaction occurs exclusively at the organellar membrane. The interaction of TRPML3 with GATE16 and GATE16-positive vesicle formation were increased in starvation induced autophagy, suggesting that the interaction facilitates the function of GATE16 in autophagosome formation. However, GATE16 was not required for TRPML3 trafficking to autophagosomes. Experiments using dominant-negative (DN) TRPML3(D458K) showed that GATE16 is localized not only in autophagosomes but also in extra-autophagosomal compartments, by contrast with LC3B. Since GATE16 acts at a later stage of the autophagosome biogenesis, our results suggest that TRPML3 plays a role in autophagosome maturation through the interaction with GATE16, by providing Ca{sup 2+} in the fusion process.

  19. Berberine attenuates autophagy in adipocytes by targeting BECN1

    OpenAIRE

    Deng, Yujie; Xu, Jun; Zhang, Xiaoyan; Yang, Jian; Zhang, Di; Huang, Jian; Lv, Pengfei; Shen, Weili; Yang, Ying

    2014-01-01

    The lysosomal degradation pathway, autophagy, is essential for the maintenance of cellular homeostasis. Recently, autophagy has been demonstrated to be required in the process of adipocyte conversion. However, its role in mature adipocytes under physiological and pathological conditions remains unclear. Here, we report a major function of BECN1 in the regulation of basal autophagy in mature adipocytes. We also show that berberine, a natural plant alkaloid, inhibits basal autophagy in adipocyt...

  20. From the urea cycle to autophagy: Alfred J. Meijer

    NARCIS (Netherlands)

    D.J. Klionsky; A.J. Meijer

    2011-01-01

    Now that many of the components of the autophagy machinery have been identified, in particular the autophagy-related (Atg) proteins, increasing focus is being directed toward the role of autophagy in health and disease. Accordingly, it is of ever-greater importance to understand the central role of

  1. Autophagy modulates the Mycobacterium tuberculosis-induced cytokine response

    NARCIS (Netherlands)

    Kleinnijenhuis, J.; Oosting, M.; Plantinga, T.S.; Meer, J.W.M. van der; Joosten, L.A.B.; Crevel, R. van; Netea, M.G.

    2011-01-01

    Both autophagy and pro-inflammatory cytokines are involved in the host defence against mycobacteria, but little is known regarding the effect of autophagy on Mycobacterium tuberculosis (MTB)-induced cytokine production. In the present study, we assessed the effect of autophagy on production of monoc

  2. Autophagy and Retromer Components in Plant Innate Immunity

    DEFF Research Database (Denmark)

    Munch, David

    -hormone salicylic acid. Here, I present data that make it clear that NPR1 does not directly regulate autophagy, but instead control stress responses that indirectly activate autophagy. The observations presented will also clarify why autophagy has been described as being both a pro-death and pro-life pathway under...

  3. Regulation of the Tumor-Suppressor Function of the Class III Phosphatidylinositol 3-Kinase Complex by Ubiquitin and SUMO

    Energy Technology Data Exchange (ETDEWEB)

    Reidick, Christina [Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Bochum 44801 (Germany); El Magraoui, Fouzi; Meyer, Helmut E. [Biomedical Research, Human Brain Proteomics II, Leibniz-Institut für Analytische Wissenschaften-ISAS, Dortmund 44139 (Germany); Stenmark, Harald [Department of Biochemistry, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo 0310 (Norway); Platta, Harald W., E-mail: harald.platta@rub.de [Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Bochum 44801 (Germany)

    2014-12-23

    The occurrence of cancer is often associated with a dysfunction in one of the three central membrane-involution processes—autophagy, endocytosis or cytokinesis. Interestingly, all three pathways are controlled by the same central signaling module: the class III phosphatidylinositol 3-kinase (PI3K-III) complex and its catalytic product, the phosphorylated lipid phosphatidylinositol 3-phosphate (PtdIns3P). The activity of the catalytic subunit of the PI3K-III complex, the lipid-kinase VPS34, requires the presence of the membrane-targeting factor VPS15 as well as the adaptor protein Beclin 1. Furthermore, a growing list of regulatory proteins associates with VPS34 via Beclin 1. These accessory factors define distinct subunit compositions and thereby guide the PI3K-III complex to its different cellular and physiological roles. Here we discuss the regulation of the PI3K-III complex components by ubiquitination and SUMOylation. Especially Beclin 1 has emerged as a highly regulated protein, which can be modified with Lys11-, Lys48- or Lys63-linked polyubiquitin chains catalyzed by distinct E3 ligases from the RING-, HECT-, RBR- or Cullin-type. We also point out other cross-links of these ligases with autophagy in order to discuss how these data might be merged into a general concept.

  4. The ubiquitin proteasome system in Huntington's disease and the spinocerebellar ataxias

    Directory of Open Access Journals (Sweden)

    Rubinsztein David C

    2007-11-01

    Full Text Available Abstract Huntington's disease and several of the spinocerebellar ataxias are caused by the abnormal expansion of a CAG repeat within the coding region of the disease gene. This results in the production of a mutant protein with an abnormally expanded polyglutamine tract. Although these disorders have a clear monogenic cause, each polyglutamine expansion mutation is likely to cause the dysfunction of many pathways and processes within the cell. It has been proposed that the ubiquitin proteasome system is impaired in polyglutamine expansion disorders and that this contributes to pathology. However, this is controversial with some groups demonstrating decreased proteasome activity in polyglutamine expansion disorders, some showing no change in activity and others demonstrating an increase in proteasome activity. It remains unknown whether the ubiquitin proteasome system is a feasible therapeutic target in these disorders. Here we review the conflicting results obtained from different assays performed in a variety of different systems. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com.

  5. Origin and diversification of TRIM ubiquitin ligases.

    Directory of Open Access Journals (Sweden)

    Ignacio Marín

    Full Text Available Most proteins of the TRIM family (also known as RBCC family are ubiquitin ligases that share a peculiar protein structure, characterized by including an N-terminal RING finger domain closely followed by one or two B-boxes. Additional protein domains found at their C termini have been used to classify TRIM proteins into classes. TRIMs are involved in multiple cellular processes and many of them are essential components of the innate immunity system of animal species. In humans, it has been shown that mutations in several TRIM-encoding genes lead to diverse genetic diseases and contribute to several types of cancer. They had been hitherto detected only in animals. In this work, by comprehensively analyzing the available diversity of TRIM and TRIM-like protein sequences and evaluating their evolutionary patterns, an improved classification of the TRIM family is obtained. Members of one of the TRIM subfamilies defined, called Subfamily A, turn to be present not only in animals, but also in many other eukaryotes, such as fungi, apusozoans, alveolates, excavates and plants. The rest of subfamilies are animal-specific and several of them originated only recently. Subfamily A proteins are characterized by containing a MATH domain, suggesting a potential evolutionary connection between TRIM proteins and a different type of ubiquitin ligases, known as TRAFs, which contain quite similar MATH domains. These results indicate that the TRIM family emerged much earlier than so far thought and contribute to our understanding of its origin and diversification. The structural and evolutionary links with the TRAF family of ubiquitin ligases can be experimentally explored to determine whether functional connections also exist.

  6. Ubiquitin proteasome system research in gastrointestinal cancer.

    Science.gov (United States)

    Zhong, Jia-Ling; Huang, Chang-Zhi

    2016-02-15

    The ubiquitin proteasome system (UPS) is important for the degradation of proteins in eukaryotic cells. It is involved in nearly every cellular process and plays an important role in maintaining body homeostasis. An increasing body of evidence has linked alterations in the UPS to gastrointestinal malignancies, including esophageal, gastric and colorectal cancers. Here, we summarize the current literature detailing the involvement of the UPS in gastrointestinal cancer, highlighting its role in tumor occurrence and development, providing information for therapeutic targets research and anti-gastrointestinal tumor drug design.

  7. Hereditary urea cycle abnormality

    Science.gov (United States)

    ... vitro so the specific genetic cause is known. Teamwork between parents, the affected child, and doctors can help prevent severe illness. Alternative Names Abnormality of the urea cycle - hereditary; Urea cycle - hereditary abnormality Images Male urinary system Urea cycle References Lichter-Konecki ...

  8. A molecular view of autophagy in Lepidoptera.

    Science.gov (United States)

    Romanelli, Davide; Casati, Barbara; Franzetti, Eleonora; Tettamanti, Gianluca

    2014-01-01

    Metamorphosis represents a critical phase in the development of holometabolous insects, during which the larval body is completely reorganized: in fact, most of the larval organs undergo remodeling or completely degenerate before the final structure of the adult insect is rebuilt. In the past, increasing evidence emerged concerning the intervention of autophagy and apoptosis in the cell death processes that occur in larval organs of Lepidoptera during metamorphosis, but a molecular characterization of these pathways was undertaken only in recent years. In addition to developmentally programmed autophagy, there is growing interest in starvation-induced autophagy. Therefore we are now entering a new era of research on autophagy that foreshadows clarification of the role and regulatory mechanisms underlying this self-digesting process in Lepidoptera. Given that some of the most important lepidopteran species of high economic importance, such as the silkworm, Bombyx mori, belong to this insect order, we expect that this information on autophagy will be fully exploited not only in basic research but also for practical applications.

  9. Autophagy and Liver Ischemia-Reperfusion Injury

    Directory of Open Access Journals (Sweden)

    Raffaele Cursio

    2015-01-01

    Full Text Available Liver ischemia-reperfusion (I-R injury occurs during liver resection, liver transplantation, and hemorrhagic shock. The main mode of liver cell death after warm and/or cold liver I-R is necrosis, but other modes of cell death, as apoptosis and autophagy, are also involved. Autophagy is an intracellular self-digesting pathway responsible for removal of long-lived proteins, damaged organelles, and malformed proteins during biosynthesis by lysosomes. Autophagy is found in normal and diseased liver. Although depending on the type of ischemia, warm and/or cold, the dynamic process of liver I-R results mainly in adenosine triphosphate depletion and in production of reactive oxygen species (ROS, leads to both, a local ischemic insult and an acute inflammatory-mediated reperfusion injury, and results finally in cell death. This process can induce liver dysfunction and can increase patient morbidity and mortality after liver surgery and hemorrhagic shock. Whether autophagy protects from or promotes liver injury following warm and/or cold I-R remains to be elucidated. The present review aims to summarize the current knowledge in liver I-R injury focusing on both the beneficial and the detrimental effects of liver autophagy following warm and/or cold liver I-R.

  10. c-Ski inhibits autophagy of vascular smooth muscle cells induced by oxLDL and PDGF.

    Science.gov (United States)

    Li, Jun; Zhao, Li; Yang, Ting; Zeng, Yi-Jun; Yang, Kang

    2014-01-01

    Autophagy is increasingly being recognized as a critical determinant of vascular smooth muscle cell (VSMC) biology. Previously, we have demonstrated that c-Ski inhibits VSMC proliferation stimulated by transforming growth factor β (TGF-β), but it is not clear whether c-Ski has the similar protective role against other vascular injury factors and whether regulation of autophagy is involved in its protective effects on VSMC. Accordingly, in this study, rat aortic A10 VSMCs were treated with 40 µg/ml oxidized low-density lipoprotein (oxLDL) or 20 ng/ml platelet-derived growth factor (PDGF), both of which were autophagy inducers and closely related to the abnormal proliferation of VSMCs. Overexpression of c-Ski in A10 cells significantly suppressed the oxLDL- and PDGF- induced autophagy. This action of c-Ski resulted in inhibiting the cell proliferation, the decrease of contractile phenotype marker α-SMA expression while the increase of synthetic phenotype marker osteopontin expression stimulated by oxLDL or PDGF. Inversely, knockdown of c-Ski by RNAi enhanced the stimulatory effects of oxLDL or PDGF on A10 cell growth and phenotype transition. And further investigation found that inhibition of AKT phosphorylation to downregulate proliferating cell nuclear antigen (PCNA) expression, was involved in the regulation of autophagy and associated functions by c-Ski in the oxLDL- and PDGF-stimulated VSMCs. Collectively, c-Ski may play an important role in inhibiting autophagy to protect VSMCs against some harsh stress including oxLDL and PDGF.

  11. c-Ski inhibits autophagy of vascular smooth muscle cells induced by oxLDL and PDGF.

    Directory of Open Access Journals (Sweden)

    Jun Li

    Full Text Available Autophagy is increasingly being recognized as a critical determinant of vascular smooth muscle cell (VSMC biology. Previously, we have demonstrated that c-Ski inhibits VSMC proliferation stimulated by transforming growth factor β (TGF-β, but it is not clear whether c-Ski has the similar protective role against other vascular injury factors and whether regulation of autophagy is involved in its protective effects on VSMC. Accordingly, in this study, rat aortic A10 VSMCs were treated with 40 µg/ml oxidized low-density lipoprotein (oxLDL or 20 ng/ml platelet-derived growth factor (PDGF, both of which were autophagy inducers and closely related to the abnormal proliferation of VSMCs. Overexpression of c-Ski in A10 cells significantly suppressed the oxLDL- and PDGF- induced autophagy. This action of c-Ski resulted in inhibiting the cell proliferation, the decrease of contractile phenotype marker α-SMA expression while the increase of synthetic phenotype marker osteopontin expression stimulated by oxLDL or PDGF. Inversely, knockdown of c-Ski by RNAi enhanced the stimulatory effects of oxLDL or PDGF on A10 cell growth and phenotype transition. And further investigation found that inhibition of AKT phosphorylation to downregulate proliferating cell nuclear antigen (PCNA expression, was involved in the regulation of autophagy and associated functions by c-Ski in the oxLDL- and PDGF-stimulated VSMCs. Collectively, c-Ski may play an important role in inhibiting autophagy to protect VSMCs against some harsh stress including oxLDL and PDGF.

  12. Ubiquitination-dependent mechanisms regulate synaptic growth and function.

    Science.gov (United States)

    DiAntonio, A; Haghighi, A P; Portman, S L; Lee, J D; Amaranto, A M; Goodman, C S

    2001-07-26

    The covalent attachment of ubiquitin to cellular proteins is a powerful mechanism for controlling protein activity and localization. Ubiquitination is a reversible modification promoted by ubiquitin ligases and antagonized by deubiquitinating proteases. Ubiquitin-dependent mechanisms regulate many important processes including cell-cycle progression, apoptosis and transcriptional regulation. Here we show that ubiquitin-dependent mechanisms regulate synaptic development at the Drosophila neuromuscular junction (NMJ). Neuronal overexpression of the deubiquitinating protease fat facets leads to a profound disruption of synaptic growth control; there is a large increase in the number of synaptic boutons, an elaboration of the synaptic branching pattern, and a disruption of synaptic function. Antagonizing the ubiquitination pathway in neurons by expression of the yeast deubiquitinating protease UBP2 (ref. 5) also produces synaptic overgrowth and dysfunction. Genetic interactions between fat facets and highwire, a negative regulator of synaptic growth that has structural homology to a family of ubiquitin ligases, suggest that synaptic development may be controlled by the balance between positive and negative regulators of ubiquitination.

  13. Lysine Ubiquitination and Acetylation of Human Cardiac 20S Proteasomes

    Science.gov (United States)

    Lau, Edward; Choi, Howard JH; Ng, Dominic CM; Meyer, David; Fang, Caiyun; Li, Haomin; Wang, Ding; Zelaya, Ivette M; Yates, John R; Lam, Maggie PY

    2016-01-01

    Purpose Altered proteasome functions are associated with multiple cardiomyopathies. While the proteasome targets poly-ubiquitinated proteins for destruction, it itself is modifiable by ubiquitination. We aim to identify the exact ubiquitination sites on cardiac proteasomes and examine whether they are also subject to acetylations. Experimental design Assembled cardiac 20S proteasome complexes were purified from five human hearts with ischemic cardiomyopathy, then analyzed by high-resolution MS to identify ubiquitination and acetylation sites. We developed a library search strategy that may be used to complement database search in identifying PTM in different samples. Results We identified 63 ubiquitinated lysines from intact human cardiac 20S proteasomes. In parallel, 65 acetylated residues were also discovered, 39 of which shared with ubiquitination sites. Conclusion and clinical relevance This is the most comprehensive characterization of cardiac proteasome ubiquitination to-date. There are significant overlaps between the discovered ubiquitination and acetylation sites, permitting potential crosstalk in regulating proteasome functions. The information presented here will aid future therapeutic strategies aimed at regulating the functions of cardiac proteasomes. PMID:24957502

  14. Promoters active in interphase are bookmarked during mitosis by ubiquitination.

    Science.gov (United States)

    Arora, Mansi; Zhang, Jie; Heine, George F; Ozer, Gulcin; Liu, Hui-wen; Huang, Kun; Parvin, Jeffrey D

    2012-11-01

    We analyzed modification of chromatin by ubiquitination in human cells and whether this mark changes through the cell cycle. HeLa cells were synchronized at different stages and regions of the genome with ubiquitinated chromatin were identified by affinity purification coupled with next-generation sequencing. During interphase, ubiquitin marked the chromatin on the transcribed regions of ∼70% of highly active genes and deposition of this mark was sensitive to transcriptional inhibition. Promoters of nearly half of the active genes were highly ubiquitinated specifically during mitosis. The ubiquitination at the coding regions in interphase but not at promoters during mitosis was enriched for ubH2B and dependent on the presence of RNF20. Ubiquitin labeling of both promoters during mitosis and transcribed regions during interphase, correlated with active histone marks H3K4me3 and H3K36me3 but not a repressive histone modification, H3K27me3. The high level of ubiquitination at the promoter chromatin during mitosis was transient and was removed within 2 h after the cells exited mitosis and entered the next cell cycle. These results reveal that the ubiquitination of promoter chromatin during mitosis is a bookmark identifying active genes during chromosomal condensation in mitosis, and we suggest that this process facilitates transcriptional reactivation post-mitosis.

  15. The molecular mechanism and significance of autophagy in immune response to mycobacterium tuberculosis%结核病免疫应答中自噬现象的分子机制和意义

    Institute of Scientific and Technical Information of China (English)

    黄丹丹; 鲍朗

    2012-01-01

    A growing body of evidence shows that autophagy is an essential component in the immune response to Mycobacterium tuberculosis (Mtb).Autophagy,a direct mechanism of killing intracellular Mycobacterium tuberculosis,acts as a modulator of proinflammatory cytokine secretion and plays a key role in antigen presentation.Autophagy coordinate with other host immune strategies against mycobacteria,including vitamin D-mediated innate immunity,ubiquitin-and intlammasome-involved pathways.On the other hand,Mtb has its strategies to modulate the autophagy in macrophage.Autophagy offers an attractive therapeutic target.Autophagy-promoting agents could have a clinical application as adjunctive treatment for drug-resistant tuberculosis.Moreover,vaccines which effectively induce autophagy could be more successful in providing better immune protection.%越来越多的证据表明,自噬是结核免疫反应的重要组成部分.自噬可以杀灭结核分枝杆菌、调节促炎细胞因子的分泌、增加抗原递呈功能.自噬与其他抗菌途径如维生素D3、炎性体、泛素系统存在协同作用.另一方面,结核分枝杆菌可以调控巨噬细胞的自噬.目前,自噬已成为临床重要的诊疗靶点.其能诱导自噬的药物,可以作为佐剂治疗耐药性结核;能有效诱导自噬的疫苗,可能提供更好的免疫保护作用.

  16. High Fat Diet-Induced Skeletal Muscle Wasting Is Decreased by Mesenchymal Stem Cells Administration: Implications on Oxidative Stress, Ubiquitin Proteasome Pathway Activation, and Myonuclear Apoptosis

    Directory of Open Access Journals (Sweden)

    Johanna Abrigo

    2016-01-01

    Full Text Available Obesity can lead to skeletal muscle atrophy, a pathological condition characterized by the loss of strength and muscle mass. A feature of muscle atrophy is a decrease of myofibrillar proteins as a result of ubiquitin proteasome pathway overactivation, as evidenced by increased expression of the muscle-specific ubiquitin ligases atrogin-1 and MuRF-1. Additionally, other mechanisms are related to muscle wasting, including oxidative stress, myonuclear apoptosis, and autophagy. Stem cells are an emerging therapy in the treatment of chronic diseases such as high fat diet-induced obesity. Mesenchymal stem cells (MSCs are a population of self-renewable and undifferentiated cells present in the bone marrow and other mesenchymal tissues of adult individuals. The present study is the first to analyze the effects of systemic MSC administration on high fat diet-induced skeletal muscle atrophy in the tibialis anterior of mice. Treatment with MSCs reduced losses of muscle strength and mass, decreases of fiber diameter and myosin heavy chain protein levels, and fiber type transitions. Underlying these antiatrophic effects, MSC administration also decreased ubiquitin proteasome pathway activation, oxidative stress, and myonuclear apoptosis. These results are the first to indicate that systemically administered MSCs could prevent muscle wasting associated with high fat diet-induced obesity and diabetes.

  17. High Fat Diet-Induced Skeletal Muscle Wasting Is Decreased by Mesenchymal Stem Cells Administration: Implications on Oxidative Stress, Ubiquitin Proteasome Pathway Activation, and Myonuclear Apoptosis

    Science.gov (United States)

    Aravena, Javier; Cabrera, Daniel; Simon, Felipe; Ezquer, Fernando

    2016-01-01

    Obesity can lead to skeletal muscle atrophy, a pathological condition characterized by the loss of strength and muscle mass. A feature of muscle atrophy is a decrease of myofibrillar proteins as a result of ubiquitin proteasome pathway overactivation, as evidenced by increased expression of the muscle-specific ubiquitin ligases atrogin-1 and MuRF-1. Additionally, other mechanisms are related to muscle wasting, including oxidative stress, myonuclear apoptosis, and autophagy. Stem cells are an emerging therapy in the treatment of chronic diseases such as high fat diet-induced obesity. Mesenchymal stem cells (MSCs) are a population of self-renewable and undifferentiated cells present in the bone marrow and other mesenchymal tissues of adult individuals. The present study is the first to analyze the effects of systemic MSC administration on high fat diet-induced skeletal muscle atrophy in the tibialis anterior of mice. Treatment with MSCs reduced losses of muscle strength and mass, decreases of fiber diameter and myosin heavy chain protein levels, and fiber type transitions. Underlying these antiatrophic effects, MSC administration also decreased ubiquitin proteasome pathway activation, oxidative stress, and myonuclear apoptosis. These results are the first to indicate that systemically administered MSCs could prevent muscle wasting associated with high fat diet-induced obesity and diabetes. PMID:27579157

  18. Ubiquitin-positive inclusions in ependymal cells.

    Science.gov (United States)

    Kawanishi, Ryuta; Mizutani, Tomohiko; Yamada, Hiroshi; Minami, Masayuki; Kakimi, Shigeo; Yamada, Tsutomu; Hatori, Tsutomu; Akima, Michio

    2003-08-01

    Ubiquitin-positive inclusions (UbIs) have not been well studied in ependymal cells. Since we detected such UbIs in the central canals of the medulla and spinal cord while investigating UbIs in neurodegenerative diseases, we studied UbIs in the entire ependymal system of 42 patients with various neurological diseases and of 10 non-neurological controls. UbIs were located in the cytoplasm of the ependymal cells, and were round to oval in shape, measuring 4-11 microm in diameter. The UbIs were non-argyrophilic and undetectable by hematoxylin and eosin staining, but mildly reactive to periodic acid-Schiff staining with and without digestion. The UbIs were variably immunoreactive for anti-epithelial membrane antigen (EMA) antibody, but did not react with several other antibodies. The co-existence of ubiquitin and EMA was confirmed by confocal laser microscopy. Throughout the ependymal system, UbIs were variably found in ependymal cells as well as in subependymal cells. There was no significant difference in the overall incidence of either ependymal or subependymal UbIs between the patients with neurological diseases and controls. However, ependymal UbIs in the central canal were more frequent in the neurological disease patients than in controls, although there was no disease specificity. This is the first comprehensive report to show common occurrence of UbIs in the ependymal cells of adult human brains.

  19. COMMD1-mediated ubiquitination regulates CFTR trafficking.

    Directory of Open Access Journals (Sweden)

    Loïc Drévillon

    Full Text Available The CFTR (cystic fibrosis transmembrane conductance regulator protein is a large polytopic protein whose biogenesis is inefficient. To better understand the regulation of CFTR processing and trafficking, we conducted a genetic screen that identified COMMD1 as a new CFTR partner. COMMD1 is a protein associated with multiple cellular pathways, including the regulation of hepatic copper excretion, sodium uptake through interaction with ENaC (epithelial sodium channel and NF-kappaB signaling. In this study, we show that COMMD1 interacts with CFTR in cells expressing both proteins endogenously. This interaction promotes CFTR cell surface expression as assessed by biotinylation experiments in heterologously expressing cells through regulation of CFTR ubiquitination. In summary, our data demonstrate that CFTR is protected from ubiquitination by COMMD1, which sustains CFTR expression at the plasma membrane. Thus, increasing COMMD1 expression may provide an approach to simultaneously inhibit ENaC absorption and enhance CFTR trafficking, two major issues in cystic fibrosis.

  20. KF-1 ubiquitin ligase: an anxiety suppressor

    Directory of Open Access Journals (Sweden)

    Tamotsu Hashimoto-Gotoh

    2009-05-01

    Full Text Available Anxiety is an instinct that may have developed to promote adaptive survival by evading unnecessary danger. However, excessive anxiety is disruptive and can be a basic disorder of other psychiatric diseases such as depression. The KF-1, a ubiquitin ligase located to the endoplasmic reticulum (ER, may prevent excessive anxiety; kf-1−/− mice exhibit selectively elevated anxiety-like behavior against light or heights. Thus, KF-1 may degrade some target proteins, responsible for promoting anxiety, through the ER-associated degradation pathway, similar to Parkin in Parkinson's disease (PD. Parkin, another ER-ubiquitin ligase, prevents the degeneration of dopaminergic neurons by degrading the target proteins responsible for PD. Molecular phylogenetic studies have revealed that the prototype of kf-1 appeared in the very early phase of animal evolution but was lost, unlike parkin, in the lineage leading up to Drosophila. Therefore, kf-1−/− mice, be a powerful tool for elucidating the molecular mechanisms involved in emotional regulation, and for screening novel anxiolytic/antidepressant compounds.

  1. Chaperones, but not oxidized proteins, are ubiquitinated after oxidative stress

    DEFF Research Database (Denmark)

    Kästle, Marc; Reeg, Sandra; Rogowska-Wrzesinska, Adelina;

    2012-01-01

    After oxidative stress proteins which are oxidatively modified are degraded by the 20S proteasome. However, several studies documented an enhanced ubiquitination of yet unknown proteins. Since ubiqutination is a prerequisite for degradation by the 26S proteasome in an ATP-dependent manner......, we were able to confirm an increase of ubiquitinated proteins 16h upon oxidative stress. Therefore, we isolated ubiquitinated proteins from hydrogen peroxide treated cells, as well as from control and lactacystin, an irreversible proteasome inhibitor, treated cells, and identified some......, ubiquitinated proteins confirm the thesis that ubiquitination upon oxidative stress is no random process to degrade the mass of oxidized proteins, but concerns a special group of functional proteins....

  2. Induction of autophagy by spermidine promotes longevity.

    Science.gov (United States)

    Eisenberg, Tobias; Knauer, Heide; Schauer, Alexandra; Büttner, Sabrina; Ruckenstuhl, Christoph; Carmona-Gutierrez, Didac; Ring, Julia; Schroeder, Sabrina; Magnes, Christoph; Antonacci, Lucia; Fussi, Heike; Deszcz, Luiza; Hartl, Regina; Schraml, Elisabeth; Criollo, Alfredo; Megalou, Evgenia; Weiskopf, Daniela; Laun, Peter; Heeren, Gino; Breitenbach, Michael; Grubeck-Loebenstein, Beatrix; Herker, Eva; Fahrenkrog, Birthe; Fröhlich, Kai-Uwe; Sinner, Frank; Tavernarakis, Nektarios; Minois, Nadege; Kroemer, Guido; Madeo, Frank

    2009-11-01

    Ageing results from complex genetically and epigenetically programmed processes that are elicited in part by noxious or stressful events that cause programmed cell death. Here, we report that administration of spermidine, a natural polyamine whose intracellular concentration declines during human ageing, markedly extended the lifespan of yeast, flies and worms, and human immune cells. In addition, spermidine administration potently inhibited oxidative stress in ageing mice. In ageing yeast, spermidine treatment triggered epigenetic deacetylation of histone H3 through inhibition of histone acetyltransferases (HAT), suppressing oxidative stress and necrosis. Conversely, depletion of endogenous polyamines led to hyperacetylation, generation of reactive oxygen species, early necrotic death and decreased lifespan. The altered acetylation status of the chromatin led to significant upregulation of various autophagy-related transcripts, triggering autophagy in yeast, flies, worms and human cells. Finally, we found that enhanced autophagy is crucial for polyamine-induced suppression of necrosis and enhanced longevity.

  3. IKK connects autophagy to major stress pathways.

    Science.gov (United States)

    Criollo, Alfredo; Senovilla, Laura; Authier, Hélène; Maiuri, Maria Chiara; Morselli, Eugenia; Vitale, Ilio; Kepp, Oliver; Tasdemir, Ezgi; Galluzzi, Lorenzo; Shen, Shensi; Tailler, Maximilien; Delahaye, Nicolas; Tesniere, Antoine; De Stefano, Daniela; Younes, Aména Ben; Harper, Francis; Pierron, Gérard; Lavandero, Sergio; Zitvogel, Laurence; Israel, Alain; Baud, Véronique; Kroemer, Guido

    2010-01-01

    Cells respond to stress by activating cytoplasmic mechanisms as well as transcriptional programs that can lead to adaptation or death. Autophagy represents an important cytoprotective response that is regulated by both transcriptional and transcription-independent pathways. NFkappaB is perhaps the transcription factor most frequently activated by stress and has been ascribed with either pro- or anti-autophagic functions, depending on the cellular context. Our results demonstrate that activation of the IKK (IkappaB kinase) complex, which is critical for the stress-elicited activation of NFkappaB, is sufficient to promote autophagy independent of NFkappaB, and that IKK is required for the optimal induction of autophagy by both physiological and pharmacological autophagic triggers.

  4. Autophagy is an inflammation-related defensive mechanism against disease.

    Science.gov (United States)

    Joven, Jorge; Guirro, Maria; Mariné-Casadó, Roger; Rodríguez-Gallego, Esther; Menéndez, Javier A

    2014-01-01

    The inflammatory response is an energy-intensive process. Consequently, metabolism is closely associated with immune function. The autophagy machinery plays a role in metabolism by providing energy but may also be used to attack invading pathogens (xenophagy). The autophagy machinery may function to protect against not only the threats of infection but also the threats of the host's own response acting on the central immunological tolerance and the negative regulation of innate and inflammatory signaling. The balance between too little and too much autophagy is critical for the survival of immune cells because autophagy is linked to type 2-cell death programmed necrosis and apoptosis. Changes in inflammatory cells are driven by extracellular signals; however, the mechanisms by which cytokines mediate autophagy regulation and govern immune cell function remain unknown. Certain cytokines increase autophagy, whereas others inhibit autophagy. The relationship between autophagy and inflammation is also important in the pathogenesis of metabolic, non-communicable diseases. Inflammation per se is not the cause of obesity-associated diseases, but it is secondary to both the positive energy balance and the specific cellular responses. In metabolic tissues, the suppression of autophagy increases inflammation with the overexpression of cytokines, resulting in an activation of autophagy. The physiological role of these apparently contradictory findings remains uncertain but exemplifies future challenges in the therapeutic modulation of autophagy in the management of disease.

  5. What to Eat: Evidence for Selective Autophagy in Plants

    Institute of Scientific and Technical Information of China (English)

    Brice E.Floyd; Stephanie C.Morriss; Gustavo C.Maclntosh; Diane C.Bassham

    2012-01-01

    Autophagy is a macromolecular degradation pathway by which cells recycle their contents as a developmental process,house-keeping mechanism,and response to environmental stress.In plants,autophagy involves the sequestration of cargo to be degraded,transport to the cell vacuole in a double-membrane bound autophagosome,and subsequent degradation by lytic enzymes.Autophagy has generally been considered to be a non-selective mechanism of degradation.However,studies in yeast and animals have found numerous examples of selective autophagy,with cargo including proteins,protein aggregates,and organelles.Recent work has also provided evidence for several types of selective autophagy in plants.The degradation of protein aggregates was the first selective autophagy described in plants,and,more recently,a hybrid protein of the mammalian selective autophagy adaptors p62 and NBR1,which interacts with the autophagy machinery and may function in autophagy of protein aggregates,was described in plants.Other intracellular components have been suggested to be selectively targeted by autophagy in plants,but the current evidence is limited.Here,we discuss recent findings regarding the selective targeting of cell components by autophagy in plants.

  6. Regulation of autophagy by the inositol trisphosphate receptor.

    Science.gov (United States)

    Criollo, A; Maiuri, M C; Tasdemir, E; Vitale, I; Fiebig, A A; Andrews, D; Molgó, J; Díaz, J; Lavandero, S; Harper, F; Pierron, G; di Stefano, D; Rizzuto, R; Szabadkai, G; Kroemer, G

    2007-05-01

    The reduction of intracellular 1,4,5-inositol trisphosphate (IP(3)) levels stimulates autophagy, whereas the enhancement of IP(3) levels inhibits autophagy induced by nutrient depletion. Here, we show that knockdown of the IP(3) receptor (IP(3)R) with small interfering RNAs and pharmacological IP(3)R blockade is a strong stimulus for the induction of autophagy. The IP(3)R is known to reside in the membranes of the endoplasmic reticulum (ER) as well as within ER-mitochondrial contact sites, and IP(3)R blockade triggered the autophagy of both ER and mitochondria, as exactly observed in starvation-induced autophagy. ER stressors such as tunicamycin and thapsigargin also induced autophagy of ER and, to less extent, of mitochondria. Autophagy triggered by starvation or IP(3)R blockade was inhibited by Bcl-2 and Bcl-X(L) specifically targeted to ER but not Bcl-2 or Bcl-X(L) proteins targeted to mitochondria. In contrast, ER stress-induced autophagy was not inhibited by Bcl-2 and Bcl-X(L). Autophagy promoted by IP(3)R inhibition could not be attributed to a modulation of steady-state Ca(2+) levels in the ER or in the cytosol, yet involved the obligate contribution of Beclin-1, autophagy-related gene (Atg)5, Atg10, Atg12 and hVps34. Altogether, these results strongly suggest that IP(3)R exerts a major role in the physiological control of autophagy.

  7. Emerging role of mammalian autophagy in ketogenesis to overcome starvation.

    Science.gov (United States)

    Takagi, Ayano; Kume, Shinji; Maegawa, Hiroshi; Uzu, Takashi

    2016-01-01

    Autophagy is essential for the survival of lower organisms under conditions of nutrient depletion. However, whether autophagy plays a physiological role in mammals experiencing starvation is unknown. Ketogenesis is critical for overcoming starvation in mammals. We recently revealed that hepatic and renal autophagy are involved in starvation-induced ketogenesis, by utilizing tissue-specific autophagy-deficient mouse models. The liver is the principal organ to regulate ketogenesis, and a deficiency of liver-specific autophagy partially but significantly attenuates starvation-induced ketogenesis. While deficiency of renal-specific autophagy does not affect starvation-induced ketogenesis, mice with deficiency of both liver and kidney autophagy have even lower blood ketone levels and physical activity under starvation conditions than those lacking autophagy in the liver alone. These results suggest that the kidney can compensate for impaired hepatic ketogenesis. Since ketone bodies are catabolized from fatty acids, the uptake of fatty acids, the formation of intracellular lipid droplets, and fatty acid oxidation are critical for ketogenesis. We found that starvation-induced lipid droplet formation is impaired in autophagy-deficient organs. Thus, hepatic and renal autophagy are required for starvation-induced ketogenesis. This process is essential for maintaining systemic energy homeostasis and physical activity during starvation. Our findings provide a novel insight into mammalian autophagy and the physiology of starvation.

  8. Role of the Crosstalk between Autophagy and Apoptosis in Cancer

    Directory of Open Access Journals (Sweden)

    Minfei Su

    2013-01-01

    Full Text Available Autophagy and apoptosis are catabolic pathways essential for organismal homeostasis. Autophagy is normally a cell-survival pathway involving the degradation and recycling of obsolete, damaged, or harmful macromolecular assemblies; however, excess autophagy has been implicated in type II cell death. Apoptosis is the canonical programmed cell death pathway. Autophagy and apoptosis have now been shown to be interconnected by several molecular nodes of crosstalk, enabling the coordinate regulation of degradation by these pathways. Normally, autophagy and apoptosis are both tumor suppressor pathways. Autophagy fulfils this role as it facilitates the degradation of oncogenic molecules, preventing development of cancers, while apoptosis prevents the survival of cancer cells. Consequently, defective or inadequate levels of either autophagy or apoptosis can lead to cancer. However, autophagy appears to have a dual role in cancer, as it has now been shown that autophagy also facilitates the survival of tumor cells in stress conditions such as hypoxic or low-nutrition environments. Here we review the multiple molecular mechanisms of coordination of autophagy and apoptosis and the role of the proteins involved in this crosstalk in cancer. A comprehensive understanding of the interconnectivity of autophagy and apoptosis is essential for the development of effective cancer therapeutics.

  9. HIV-1 differentially modulates autophagy in neurons and astrocytes.

    Science.gov (United States)

    Mehla, Rajeev; Chauhan, Ashok

    2015-08-15

    Autophagy, a lysosomal degradative pathway that maintains cellular homeostasis, has emerged as an innate immune defense against pathogens. The role of autophagy in the deregulated HIV-infected central nervous system (CNS) is unclear. We have found that HIV-1-induced neuro-glial (neurons and astrocytes) damage involves modulation of the autophagy pathway. Neuro-glial stress induced by HIV-1 led to biochemical and morphological dysfunctions. X4 HIV-1 produced neuro-glial toxicity coupled with suppression of autophagy, while R5 HIV-1-induced toxicity was restricted to neurons. Rapamycin, a specific mTOR inhibitor (autophagy inducer) relieved the blockage of the autophagy pathway caused by HIV-1 and resulted in neuro-glial protection. Further understanding of the regulation of autophagy by cytokines and chemokines or other signaling events may lead to recognition of therapeutic targets for neurodegenerative diseases.

  10. Porcine Epidemic Diarrhea Virus Induces Autophagy to Benefit Its Replication

    Directory of Open Access Journals (Sweden)

    Xiaozhen Guo

    2017-03-01

    Full Text Available The new porcine epidemic diarrhea (PED has caused devastating economic losses to the swine industry worldwide. Despite extensive research on the relationship between autophagy and virus infection, the concrete role of autophagy in porcine epidemic diarrhea virus (PEDV infection has not been reported. In this study, autophagy was demonstrated to be triggered by the effective replication of PEDV through transmission electron microscopy, confocal microscopy, and Western blot analysis. Moreover, autophagy was confirmed to benefit PEDV replication by using autophagy regulators and RNA interference. Furthermore, autophagy might be associated with the expression of inflammatory cytokines and have a positive feedback loop with the NF-κB signaling pathway during PEDV infection. This work is the first attempt to explore the complex interplay between autophagy and PEDV infection. Our findings might accelerate our understanding of the pathogenesis of PEDV infection and provide new insights into the development of effective therapeutic strategies.

  11. Autophagy-associated immune responses and cancer immunotherapy.

    Science.gov (United States)

    Pan, Hongming; Chen, Liuxi; Xu, Yinghua; Han, Weidong; Lou, Fang; Fei, Weiqiang; Liu, Shuiping; Jing, Zhao; Sui, Xinbing

    2016-04-19

    Autophagy is an evolutionarily conserved catabolic process by which cellular components are sequestered into a double-membrane vesicle and delivered to the lysosome for terminal degradation and recycling. Accumulating evidence suggests that autophagy plays a critical role in cell survival, senescence and homeostasis, and its dysregulation is associated with a variety of diseases including cancer, cardiovascular disease, neurodegeneration. Recent studies show that autophagy is also an important regulator of cell immune response. However, the mechanism by which autophagy regulates tumor immune responses remains elusive. In this review, we will describe the role of autophagy in immune regulation and summarize the possible molecular mechanisms that are currently well documented in the ability of autophagy to control cell immune response. In addition, the scientific and clinical hurdles regarding the potential role of autophagy in cancer immunotherapy will be discussed.

  12. PKC-Dependent GlyT1 Ubiquitination Occurs Independent of Phosphorylation: Inespecificity in Lysine Selection for Ubiquitination.

    Directory of Open Access Journals (Sweden)

    Susana P Barrera

    Full Text Available Neurotransmitter transporter ubiquitination is emerging as the main mechanism for endocytosis and sorting of cargo into lysosomes. In this study, we demonstrate PKC-dependent ubiquitination of three different isoforms of the glycine transporter 1 (GlyT1. Incubation of cells expressing transporter with the PKC activator phorbol ester induced a dramatic, time-dependent increase in GlyT1 ubiquitination, followed by accumulation of GlyT1 in EEA1 positive early endosomes. This occurred via a mechanism that was abolished by inhibition of PKC. GlyT1 endocytosis was confirmed in both retinal sections and primary cultures of mouse amacrine neurons. Replacement of only all lysines in the N-and C-termini to arginines prevented ubiquitination and endocytosis, displaying redundancy in the mechanism of ubiquitination. Interestingly, a 40-50% reduction in glycine uptake was detected in phorbol-ester stimulated cells expressing the WT-GlyT1, whereas no significant change was for the mutant protein, demonstrating that endocytosis participates in the reduction of uptake. Consistent with previous findings for the dopamine transporter DAT, ubiquitination of GlyT1 tails functions as sorting signal to deliver transporter into the lysosome and removal of ubiquitination sites dramatically attenuated the rate of GlyT1 degradation. Finally, we showed for the first time that PKC-dependent GlyT1 phosphorylation was not affected by removal of ubiquitination sites, suggesting separate PKC-dependent signaling events for these posttranslational modifications.

  13. Lipid raft-dependent FcepsilonRI ubiquitination regulates receptor endocytosis through the action of ubiquitin binding adaptors.

    Directory of Open Access Journals (Sweden)

    Rosa Molfetta

    Full Text Available The best characterized role for ubiquitination of membrane receptors is to negatively regulate signaling by targeting receptors for lysosomal degradation. The high affinity receptor for IgE (FcepsilonRI expressed on mast cells and basophils is rapidly ubiquitinated upon antigen stimulation. However, the nature and the role of this covalent modification are still largelly unknown. Here, we show that FcepsilonRI subunits are preferentially ubiquitinated at multiple sites upon stimulation, and provide evidence for a role of ubiquitin as an internalization signal: under conditions of impaired receptor ubiquitination a decrease of receptor entry is observed by FACS analysis and fluorescence microscopy. We also used biochemical approaches combined with fluorescence microscopy, to demonstrate that receptor endocytosis requires the integrity of specific membrane domains, namely lipid rafts. Additionally, by RNA interference we demonstrate the involvement of ubiquitin-binding endocytic adaptors in FcepsilonRI internalization and sorting. Notably, the triple depletion of Eps15, Eps15R and Epsin1 negatively affects the early steps of Ag-induced receptor endocytosis, whereas Hrs depletion retains ubiquitinated receptors into early endosomes and partially prevents their sorting into lysosomes for degradation. Our results are compatible with a scenario in which the accumulation of engaged receptor subunits into lipid rafts is required for receptor ubiquitination, a prerequisite for efficient receptor internalization, sorting and delivery to a lysosomal compartment.

  14. Mechanistic studies on activation of ubiquitin and di-ubiquitin-like protein, FAT10, by ubiquitin-like modifier activating enzyme 6, Uba6.

    Science.gov (United States)

    Gavin, James M; Chen, Jesse J; Liao, Hua; Rollins, Neil; Yang, Xiaofeng; Xu, Qing; Ma, Jingya; Loke, Huay-Keng; Lingaraj, Trupti; Brownell, James E; Mallender, William D; Gould, Alexandra E; Amidon, Benjamin S; Dick, Lawrence R

    2012-05-01

    Uba6 is a homolog of the ubiquitin-activating enzyme, Uba1, and activates two ubiquitin-like proteins (UBLs), ubiquitin and FAT10. In this study, biochemical and biophysical experiments were performed to understand the mechanisms of how Uba6 recognizes two distinct UBLs and catalyzes their activation and transfer. Uba6 is shown to undergo a three-step activation process and form a ternary complex with both UBLs, similar to what has been observed for Uba1. The catalytic mechanism of Uba6 is further supported by inhibition studies using a mechanism-based E1 inhibitor, Compound 1, which forms covalent adducts with both ubiquitin and FAT10. In addition, pre-steady state kinetic analysis revealed that the rates of UBL-adenylate (step 1) and thioester (step 2) formation are similar between ubiquitin and FAT10. However, distinct kinetic behaviors were also observed for ubiquitin and FAT10. FAT10 binds Uba6 with much higher affinity than ubiquitin while demonstrating lower catalytic activity in both ATP-PP(i) exchange and E1-E2 transthiolation assays. Also, Compound 1 is less potent with FAT10 as the UBL compared with ubiquitin in ATP-PP(i) exchange assays, and both a slow rate of covalent adduct formation and weak adduct binding to Uba6 contribute to the diminished potency observed for FAT10. Together with expression level analysis in IM-9 cells, this study sheds light on the potential role of cytokine-induced FAT10 expression in regulating Uba6 pathways.

  15. Autophagy in the light of sphingolipid metabolism

    DEFF Research Database (Denmark)

    Harvald, Eva Bang; Olsen, Anne Sofie Braun; Færgeman, Nils J.

    2015-01-01

    , has over the past decade been recognized as an essential part of metabolism. Autophagy not only rids the cell of excessive or damaged organelles, misfolded proteins, and invading microorganisms, it also provides nutrients to maintain crucial cellular functions. Besides serving as essential structural......Maintenance of cellular homeostasis requires tight and coordinated control of numerous metabolic pathways, which are governed by interconnected networks of signaling pathways and energy-sensing regulators. Autophagy, a lysosomal degradation pathway by which the cell self-digests its own components...

  16. Autophagy and proteins involved in vesicular trafficking.

    Science.gov (United States)

    Amaya, Celina; Fader, Claudio Marcelo; Colombo, María Isabel

    2015-11-14

    Autophagy is an intracellular degradation system that, as a basic mechanism it delivers cytoplasmic components to the lysosomes in order to maintain adequate energy levels and cellular homeostasis. This complex cellular process is activated by low cellular nutrient levels and other stress situations such as low ATP levels, the accumulation of damaged proteins or organelles, or pathogen invasion. Autophagy as a multistep process involves vesicular transport events leading to tethering and fusion of autophagic vesicles with several intracellular compartments. This review summarizes our current understanding of the autophagic pathway with emphasis in the trafficking machinery (i.e. Rabs GTPases and SNAP receptors (SNAREs)) involved in specific steps of the pathway.

  17. Neuroprotective effects of mesenchymal stem cells through autophagy modulation in a parkinsonian model.

    Science.gov (United States)

    Park, Hyun Jung; Shin, Jin Young; Kim, Ha Na; Oh, Se Hee; Lee, Phil Hyu

    2014-08-01

    Autophagy is a major degradation pathway for abnormal aggregated proteins and organelles that cause various neurodegenerative diseases. Current evidence suggests a central role for autophagy in pathogenesis of Parkinson's disease, and that dysfunction in the autophagic system may lead to α-synuclein accumulation. In the present study, we investigated whether mesenchymal stem cells (MSCs) would enhance autophagy and thus exert a neuroprotective effect through the modulation of α-synuclein in parkinsonian models. In MPP(+)-treated neuronal cells, coculture with MSCs increased cellular viability, attenuated expression of α-synuclein, and enhanced the number of LC3-II-positive autophagosomes compared with cells treated with MPP(+) only. In an MPTP-treated animal model of Parkinson's disease, MSC administration significantly increased final maturation of late autophagic vacuoles, fusion with lysosomes. Moreover, MSC administration significantly reduced the level of α-synuclein in dopaminergic neurons, which was elevated in MPTP-treated mice. These results suggest that MSC treatment significantly enhances autophagolysosome formation and may modulate α-synuclein expression in parkinsonian models, which may lead to increased neuronal survival in the presence of neurotoxins.

  18. Mst1 inhibits CMECs autophagy and participates in the development of diabetic coronary microvascular dysfunction

    Science.gov (United States)

    Lin, Jie; Zhang, Lei; Zhang, Mingming; Hu, Jianqiang; Wang, Tingting; Duan, Yu; Man, Wanrong; Wu, Bin; Feng, Jiaxu; Sun, Lei; Li, Congye; Zhang, Rongqing; Wang, Haichang; Sun, Dongdong

    2016-01-01

    Cardiovascular complications account for a substantial proportion of morbidity and mortality in diabetic patients. Abnormalities of cardiac microvascular endothelial cells (CMECs) lead to impaired cardiac microvascular vessel integrity and subsequent cardiac dysfunction, underlining the importance of coronary microvascular dysfunction. In this study, experimental diabetes models were constructed using Mst1 transgenic, Mst1 knockout and sirt1 knockout mice. Diabetic Mst1 transgenic mice exhibited impaired cardiac microvessel integrity and decreased cardiac function. Mst1 overexpression deceased CMECs autophagy as evidenced by decreased LC3 expression and enhanced protein aggregation when subjected to high glucose culture. Mst1 knockout improved cardiac microvessel integrity and enhanced cardiac functions in diabetic mice. Mst1 knockdown up-regulated autophagy as indicated by more typical autophagosomes and increased LC3 expression in CMECs subjected to high glucose cultures. Mst1 knockdown also promoted autophagic flux in the presence of bafilomycin A1. Mst1 overexpression increased CMECs apoptosis, whereas Mst1 knockout decreased CMECs apoptosis. Sirt1 knockout abolished the effects of Mst1 overexpression in cardiac microvascular injury and cardiac dysfunction. In conclusion, Mst1 knockout preserved cardiac microvessel integrity and improved cardiac functions in diabetic mice. Mst1 decreased sirt1 activity, inhibited autophagy and enhanced apoptosis in CMECs, thus participating in the pathogenesis of diabetic coronary microvascular dysfunction. PMID:27680548

  19. "Jeopardy" in Abnormal Psychology.

    Science.gov (United States)

    Keutzer, Carolin S.

    1993-01-01

    Describes the use of the board game, Jeopardy, in a college level abnormal psychology course. Finds increased student interaction and improved application of information. Reports generally favorable student evaluation of the technique. (CFR)

  20. Chromosomal Abnormalities in ADHD

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2002-07-01

    Full Text Available The prevalence of fragile X syndrome, velocardiofacial syndrome (VCFS, and other cytogenetic abnormalities among 100 children (64 boys with combined type ADHD and normal intelligence was assessed at the NIMH and Georgetown University Medical Center.

  1. Abnormal menstrual periods (image)

    Science.gov (United States)

    ... may have a variety of causes, such as endometrial hyperplasia, endometrial polyps, uterine fibroids, and abnormal thyroid or ... the endometrium becomes unusually thick it is called endometrial ... Hyperplasia may cause profuse or extended menstrual bleeding.

  2. Chromosomal abnormalities and autism

    Directory of Open Access Journals (Sweden)

    Farida El-Baz

    2016-01-01

    Conclusion: Chromosomal abnormalities were not detected in the studied autistic children, and so the relation between the genetics and autism still needs further work up with different study methods and techniques.

  3. Effect of inhibition of the Ubiquitin-Proteasome System and Hsp90 on growth and survival of Rhabdomyosarcoma cells in vitro

    Directory of Open Access Journals (Sweden)

    Peron Marica

    2012-06-01

    Full Text Available Abstract Background The ubiquitin-proteasome system (UPS and the heat shock response (HSR are two critical regulators of cell homeostasis, as their inhibition affects growth and survival of normal cells, as well as stress response and invasiveness of cancer cells. We evaluated the effects of the proteasome inhibitor Bortezomib and of 17-DMAG, a competitive inhibitor of Hsp90, in rhabdomyosarcoma (RMS cells, and analyzed the efficacy of single-agent exposures with combination treatments. Methods To assess cytotoxicity induced by Bortezomib and 17-DMAG in RMS cells, viability was measured by MTT assay after 24, 48 and 72 hours. Western blotting and immunofluorescence analyses were carried out to elucidate the mechanisms of action. Apoptosis was measured by FACS with Annexin-V-FITC and Propidium Iodide. Results Bortezomib and 17-DMAG, when combined at single low-toxic concentrations, enhanced growth inhibition of RMS cells, with signs of autophagy that included intensive cytoplasmic vacuolization and conversion of cytosolic LC3-I protein to its autophagosome-associated form. Treatment with lysosomal inhibitor chloroquine facilitates apoptosis, whereas stimulation of autophagy by rapamycin prevents LC3-I conversion and cell death, suggesting that autophagy is a resistance mechanism in RMS cells exposed to proteotoxic drugs. However, combination treatment also causes caspase-dependent apoptosis, PARP cleavage and Annexin V staining, as simultaneous inhibition of both UPS and HSR systems limits cytoprotective autophagy, exacerbating stress resulting from accumulation of misfolded proteins. Conclusion The combination of proteasome inhibitor Bortezomib with Hsp90 inhibitor 17-DMAG, appears to have important therapeutic advantages in the treatment of RMS cells compared with single-agent exposure, because compensatory survival mechanisms that occur as side effects of treatment may be prevented.

  4. LC3B is indispensable for selective autophagy of p62 but not basal autophagy

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yoko [Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506 (Japan); Department of Pediatrics, School of Medicine, Keio University, Tokyo 160-8582 (Japan); Sou, Yu-Shin; Kageyama, Shun [Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506 (Japan); Takahashi, Takao [Department of Pediatrics, School of Medicine, Keio University, Tokyo 160-8582 (Japan); Ueno, Takashi [Division of Proteomics and Biomolecular Science, Center for Biomedical Research Resources, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Tanaka, Keiji [Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506 (Japan); Komatsu, Masaaki, E-mail: komatsu-ms@igakuken.or.jp [Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506 (Japan); Department of Biochemistry, School of Medicine, Niigata University, Niigata 951-8510 (Japan); Ichimura, Yoshinobu, E-mail: ichimura-ys@igakuken.or.jp [Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506 (Japan)

    2014-03-28

    Highlights: • Knockdown of LC3 or GABARAP families did not affect the basal autophagy. • LC3B has a higher affinity for the autophagy-specific substrate, p62, than GABARAPs. • siRNA-mediated knockdown of LC3B, but not that of GABARAPs, resulted in significant accumulation of p62. - Abstract: Autophagy is a unique intracellular protein degradation system accompanied by autophagosome formation. Besides its important role through bulk degradation in supplying nutrients, this system has an ability to degrade certain proteins, organelles, and invading bacteria selectively to maintain cellular homeostasis. In yeasts, Atg8p plays key roles in both autophagosome formation and selective autophagy based on its membrane fusion property and interaction with autophagy adaptors/specific substrates. In contrast to the single Atg8p in yeast, mammals have 6 homologs of Atg8p comprising LC3 and GABARAP families. However, it is not clear these two families have different or similar functions. The aim of this study was to determine the separate roles of LC3 and GABARAP families in basal/constitutive and/or selective autophagy. While the combined knockdown of LC3 and GABARAP families caused a defect in long-lived protein degradation through lysosomes, knockdown of each had no effect on the degradation. Meanwhile, knockdown of LC3B but not GABARAPs resulted in significant accumulation of p62/Sqstm1, one of the selective substrate for autophagy. Our results suggest that while mammalian Atg8 homologs are functionally redundant with regard to autophagosome formation, selective autophagy is regulated by specific Atg8 homologs.

  5. Cloning of PaAtg8 and roles of autophagy in adaptation to starvation with respect to the fat body and midgut of the Americana cockroach, Periplaneta americana.

    Science.gov (United States)

    Park, Moon Soo; Takeda, Makio

    2014-05-01

    Starvation, in particular amino acid deprivation, induces autophagy in trophocytes (adipocytes), the major component of the fat body cell types, in the larvae of Drosophila melanogaster. However, the fat body of cockroach has two additional cell types: urocytes depositing uric acid in urate vacuoles as a nitrogen resource and mycetocytes harboring an endosymbiont, Blattabacterium cuenoti, which can synthesize amino acids from the metabolites of the stored uric acid. These cells might complement the roles of autophagy in recycling amino acids in the fat body or other organs of cockroaches under starvation. We investigate the presence of autophagy in tissues such as the fat body and midgut of the American cockroach, Periplaneta americana, under starvation by immunoblotting with antibody against Atg8, a ubiquitin-like protein required for the formation of autophagosomes and by electron microscopy. Corresponding changes in acid phosphatase activity were also investigated as representing lysosome activity. Starvation increased the level of an autophagic marker, Atg8-II, in both the tissues, extensively stimulating the formation of autophagic compartments in trophocytes of the fat body and columnar cells of the midgut for over 2 weeks. Acid phosphatase showed no significant increase in the fat body of the starved cockroaches but was higher in the midgut of the continuously fed animals. Thus, a distinct autophagic mechanism operates in these tissues under starvation of 2 weeks and longer. The late induction of autophagy implies exhaustion of the stored uric acid in the fat body. High activity of acid phosphatase in the midgut of the fed cockroaches might represent enhanced assimilation and not an autophagy-related function.

  6. The autophagy-related genes BbATG1 and BbATG8 have different functions in differentiation, stress resistance and virulence of mycopathogen Beauveria bassiana.

    Science.gov (United States)

    Ying, Sheng-Hua; Liu, Jing; Chu, Xin-Ling; Xie, Xue-Qin; Feng, Ming-Guang

    2016-05-20

    Autophagy-related proteins play significantly different roles in eukaryotes. In the entomopathogenic fungus Beauveria bassiana, autophagy is associated with fungal growth and development. BbATG1 (a serine/threonine protein kinase) and BbATG8 (a ubiquitin-like protein) have similar roles in autophagy, but different roles in other processes. Disruption mutants of BbATG1 and BbATG8 had impaired conidial germination under starvation stress. The mutant ΔBbATG8 exhibited enhanced sensitivity to oxidative stress, while a ΔBbATG1 mutant did not. BbATG1 and BbATG8 showed different roles in spore differentiation. The blastospore yield was reduced by 70% and 92% in ΔBbATG1 and ΔBbATG8 mutants, respectively, and the double mutant had a reduction of 95%. Conidial yield was reduced by approximately 90% and 50% in ΔBbATG1 and ΔBbATG8 mutants, respectively. A double mutant had a reduction similar to ΔBbATG1. Additionally, both BbATG1 and BbATG8 affected the levels of conidial protein BbCP15p required for conidiation. The virulence of each autophagy-deficient mutant was considerably weakened as indicated in topical and intrahemocoel injection assays, and showed a greater reduction in topical infection. However, BbATG1 and BbATG8 had different effects on fungal virulence. Our data indicate that these autophagy-related proteins have different functions in fungal stress response, asexual development and virulence.

  7. Abnormal protein aggregationand neurodegenerativediseases

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Abnormal protein aggregation or amyloid is the major cause ofmany neurodegenerative disorders. The present review focuses on the correlation between sequence and structure features of proteins related to the diseases and abnormal protein aggregation. Recent progress has improved our knowledge on understand-ing the mechanism of amyloid formation. We suggest a nucleation model for ordered protein aggregation, which can also explain pathogenesis mechanisms of these neurodegenerative diseases in vivo.

  8. The Molecular Basis for Ubiquitin and Ubiquitin-like Specificities in Bacterial Effector Proteases

    OpenAIRE

    Pruneda, Jonathan N.; Durkin, Charlotte H.; Geurink, Paul P.; Ovaa, Huib; Santhanam, Balaji; Holden, David W.; Komander, David

    2016-01-01

    Summary Pathogenic bacteria rely on secreted effector proteins to manipulate host signaling pathways, often in creative ways. CE clan proteases, specific hydrolases for ubiquitin-like modifications (SUMO and NEDD8) in eukaryotes, reportedly serve as bacterial effector proteins with deSUMOylase, deubiquitinase, or, even, acetyltransferase activities. Here, we characterize bacterial CE protease activities, revealing K63-linkage-specific deubiquitinases in human pathogens, such as Salmonella, Es...

  9. Mcl-1 Ubiquitination: Unique Regulation of an Essential Survival Protein

    Directory of Open Access Journals (Sweden)

    Barbara Mojsa

    2014-05-01

    Full Text Available Mcl-1 is an anti-apoptotic protein of the Bcl-2 family that is essential for the survival of multiple cell lineages and that is highly amplified in human cancer. Under physiological conditions, Mcl-1 expression is tightly regulated at multiple levels, involving transcriptional, post-transcriptional and post-translational processes. Ubiquitination of Mcl-1, that targets it for proteasomal degradation, allows for rapid elimination of the protein and triggering of cell death, in response to various cellular events. In the last decade, a number of studies have elucidated different pathways controlling Mcl-1 ubiquitination and degradation. Four different E3 ubiquitin-ligases (e.g., Mule, SCFβ-TrCP, SCFFbw7 and Trim17 and one deubiquitinase (e.g., USP9X, that respectively mediate and oppose Mcl-1 ubiquitination, have been formerly identified. The interaction between Mule and Mcl-1 can be modulated by other Bcl-2 family proteins, while recognition of Mcl-1 by the other E3 ubiquitin-ligases and deubiquitinase is influenced by phosphorylation of specific residues in Mcl-1. The protein kinases and E3 ubiquitin-ligases that are involved in the regulation of Mcl-1 stability vary depending on the cellular context, highlighting the complexity and pivotal role of Mcl-1 regulation. In this review, we attempt to recapitulate progress in understanding Mcl-1 regulation by the ubiquitin-proteasome system.

  10. Enhanced Detection of Ubiquitin Isopeptides Using Reductive Methylation

    Science.gov (United States)

    Chicooree, Navin; Connolly, Yvonne; Tan, Chong-Teik; Malliri, Angeliki; Li, Yaoyong; Smith, Duncan L.; Griffiths, John R.

    2013-03-01

    Identification of ubiquitination (Ub) sites is of great interest due to the critical roles that the modification plays in cellular regulation. Current methods using mass spectrometry rely upon tryptic isopeptide diglycine tag generation followed by database searching. We present a novel approach to ubiquitin detection based upon the dimethyl labeling of isopeptide N-termini glycines. Ubiquitinated proteins were digested with trypsin and the resulting peptide mixture was derivatized using formaldehyde-D2 solution and sodium cyanoborohydride. The dimethylated peptide mixtures were next separated by liquid chromatography and analyzed on a quadrupole-TOF based mass spectrometer. Diagnostic b2' and a1' ions released from the isopeptide N-terminus upon collision-induced dissociation (CID) were used to spectrally improve the identification of ubiquitinated isopeptides. Proof of principle was established by application to a ubiquitinated protein tryptic digest spiked into a six-protein mix digest background. Extracted ion chromatograms of the a1' and b2' diagnostic product ions from the diglycine tag resulted in a significant reduction in signal complexity and demonstrated a selectivity towards the identification of diglycine branched isopeptides. The method was further shown to be capable of identifying diglycine isopeptides resulting from in-gel tryptic digests of ubiquitin enriched material from a His-Ub transfected cell line. We envisage that these ions may be utilized in global ubiquitination studies with post-acquisition MS/MS (or MSe) data interrogation on high resolution hybrid mass spectrometers.

  11. Structural Basis of Dimerization-dependent Ubiquitination by the SCFFbx4 Ubiquitin Ligase

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.; Hao, B

    2010-01-01

    The F-box proteins are the substrate recognition subunits of the SCF (Skp1-Cul1-Rbx1-F-box protein) ubiquitin ligase complexes that control the stability of numerous regulators in eukaryotic cells. Here we show that dimerization of the F-box protein Fbx4 is essential for SCF{sup Fbx4} (the superscript denotes the F-box protein) ubiquitination activity toward the telomere regulator Pin2 (also known as TRF1). The crystal structure of Fbx4 in complex with an adaptor protein Skp1 reveals an antiparallel dimer configuration in which the linker domain of Fbx4 interacts with the C-terminal substrate-binding domain of the other protomer, whereas the C-terminal domain of the protein adopts a compact {alpha}/{beta} fold distinct from those of known F-box proteins. Biochemical studies indicate that both the N-terminal domain and a loop connecting the linker and C-terminal domain of Fbx4 are critical for the dimerization and activation of the protein. Our findings provide a framework for understanding the role of F-box dimerization in the SCF-mediated ubiquitination reaction.

  12. Disruption of sphingolipid metabolism augments ceramide-induced autophagy in preeclampsia.

    Science.gov (United States)

    Melland-Smith, Megan; Ermini, Leonardo; Chauvin, Sarah; Craig-Barnes, Hayley; Tagliaferro, Andrea; Todros, Tullia; Post, Martin; Caniggia, Isabella

    2015-04-01

    Bioactive sphingolipids including ceramides are involved in a variety of pathophysiological processes by regulating cell death and survival. The objective of the current study was to examine ceramide metabolism in preeclampsia, a serious disorder of pregnancy characterized by oxidative stress, and increased trophoblast cell death and autophagy. Maternal circulating and placental ceramide levels quantified by tandem mass spectrometry were elevated in pregnancies complicated by preeclampsia. Placental ceramides were elevated due to greater de novo synthesis via high serine palmitoyltransferase activity and reduced lysosomal breakdown via diminished ASAH1 expression caused by TGFB3-induced E2F4 transcriptional repression. SMPD1 activity was reduced; hence, sphingomyelin degradation by SMPD1 did not contribute to elevated ceramide levels in preeclampsia. Oxidative stress triggered similar changes in ceramide levels and acid hydrolase expression in villous explants and trophoblast cells. MALDI-imaging mass spectrometry localized the ceramide increases to the trophophoblast layers and syncytial knots of placentae from pregnancies complicated by preeclampsia. ASAH1 inhibition or ceramide treatment induced autophagy in human trophoblast cells via a shift of the BOK-MCL1 rheostat toward prodeath BOK. Pharmacological inhibition of ASAH1 activity in pregnant mice resulted in increased placental ceramide content, abnormal placentation, reduced fetal growth, and increased autophagy via a similar shift in the BOK-MCL1 system. Our results reveal that oxidative stress-induced reduction of lysosomal hydrolase activities in combination with elevated de novo synthesis leads to ceramide overload, resulting in increased trophoblast cell autophagy, and typifies preeclampsia as a sphingolipid storage disorder.

  13. 自噬与神经退行性疾病%Autophagy and neurodegeneration.

    Institute of Scientific and Technical Information of China (English)

    杨志

    2011-01-01

    基础水平的自噬在清除异常积聚的蛋白质、长寿命蛋白以及受损细胞器、维持细胞内稳态和细胞生存中扮演重要角色.自噬过程受到一系列复杂信号分子的调控,使胞内物质被双层膜结构的自噬小体包裹,自噬小体与溶酶体融合而降解.自噬功能的缺陷与神经退行性疾病如阿尔茨海默病、帕金森病、亨廷顿病等有重要联系,这些疾病的明显特点就是大脑神经元内蛋白的异常积聚.因神经元为不可再生细胞,所以通过自噬清除神经元内蛋白的异常积聚、维持神经元正常功能就显得格外重要.%Basal autophagy plays an important role in cellular homeostasis that is via the degradation of aggregate-prone protein, long-lived protein and damaged organelles. The processes of autophagy is controlled by complex signaling pathways. Cytoplasmic components are enclosed by double-membrane autophagosomes, which subsequently fuse with lysosomes for degradation. Autophagy dysfunction contributes to the pathology of various neurodegenerafive disorders, such as Alzheimer' s disease, Parkinson disease, Huntington disease. These diseases have abnormal protein accumulation. Neurons cannot get rid of their wastes through cell division. Autophagy maintenance of neuronal function is particularly important.

  14. Ubiquitin in the peroxisomal protein import pathway.

    Science.gov (United States)

    Francisco, Tânia; Rodrigues, Tony A; Pinto, Manuel P; Carvalho, Andreia F; Azevedo, Jorge E; Grou, Cláudia P

    2014-03-01

    PEX5 is the shuttling receptor for newly synthesized peroxisomal matrix proteins. Alone, or with the help of an adaptor protein, this receptor binds peroxisomal matrix proteins in the cytosol and transports them to the peroxisomal membrane docking/translocation module (DTM). The interaction between cargo-loaded PEX5 and the DTM ultimately results in its insertion into the DTM with the concomitant translocation of the cargo protein across the organelle membrane. PEX5 is not consumed in this event; rather it is dislocated back into the cytosol so that it can promote additional rounds of protein transportation. Remarkably, the data collected in recent years indicate that dislocation is preceded by monoubiquitination of PEX5 at a conserved cysteine residue. This mandatory modification is not the only type of ubiquitination occurring at the DTM. Indeed, several findings suggest that defective receptors jamming the DTM are polyubiquitinated and targeted to the proteasome for degradation.

  15. 细胞自噬与肿瘤的研究进展%Research progress of autophagy and tumor

    Institute of Scientific and Technical Information of China (English)

    徐俊杰; 王志莲; 郝敏

    2016-01-01

    细胞自噬是细胞在某些刺激因素下,细胞内膜性结构包绕损伤的蛋白或细胞器,并通过溶酶体融合降解损伤的蛋白质或细胞器的过程;生理状况下的自噬,对于维持细胞稳态有积极作用;肿瘤形成以后,细胞自噬反为癌细胞提供更多的营养,起到促进肿瘤发展的功能。自噬主要有三种方式,即分子伴侣介导的自噬、微自噬和巨自噬,均通过两个泛素化途径实现。细胞自噬可以通过影响 DNA 损伤修复、细胞应激反应、肿瘤基因表达、凋亡及病毒感染反应等诸多过程参与细胞癌变,也可能在肿瘤治疗过程中降低了对于化疗和放疗的敏感性,但是在肿瘤进展的不同时期,不同肿瘤之间自噬活性的变化不一。自噬过程中的重要中间产物或关键酶可能成为抗肿瘤药物的靶标,拓展了肿瘤防治思路。%Cell autophagy is one of the important process of the material flow in the cell in the process of some of the damaged proteins and organelles by double membrane structure of autophagy vesicles package, then, to the lysosome degradation and recycling. Autophagy has a positive role for the maintenance of cell homeostasis. After tumor formation, cell autophagy provides more nutrition for cancer cells, which plays a role in promoting tumor. There are three main ways of autophagy, that are, the molecular chaperone mediated autophagy, microautophagy and macroautophagy, which are achieved by the two ubiquitin pathways. Autophagy may be involved in the cellular carcinogenesis by affecting the DNA damage repair, cell stress response, tumor gene expression, apoptosis, and viral infection. But in different stages of the tumor, autophagy may also reduce the sensitivity of chemotherapy and radiotherapy in the treatment of cancer, the changes of the activity of the different tumors are different from each other. Important intermediate products or key enzymes in the process of

  16. Trehalose Accumulation Triggers Autophagy during Plant Desiccation.

    Directory of Open Access Journals (Sweden)

    Brett Williams

    2015-12-01

    Full Text Available Global climate change, increasingly erratic weather and a burgeoning global population are significant threats to the sustainability of future crop production. There is an urgent need for the development of robust measures that enable crops to withstand the uncertainty of climate change whilst still producing maximum yields. Resurrection plants possess the unique ability to withstand desiccation for prolonged periods, can be restored upon watering and represent great potential for the development of stress tolerant crops. Here, we describe the remarkable stress characteristics of Tripogon loliiformis, an uncharacterised resurrection grass and close relative of the economically important cereals, rice, sorghum, and maize. We show that T. loliiformis survives extreme environmental stress by implementing autophagy to prevent Programmed Cell Death. Notably, we identified a novel role for trehalose in the regulation of autophagy in T.loliiformis. Transcriptome, Gas Chromatography Mass Spectrometry, immunoblotting and confocal microscopy analyses directly linked the accumulation of trehalose with the onset of autophagy in dehydrating and desiccated T. loliiformis shoots. These results were supported in vitro with the observation of autophagosomes in trehalose treated T. loliiformis leaves; autophagosomes were not detected in untreated samples. Presumably, once induced, autophagy promotes desiccation tolerance in T.loliiformis, by removal of cellular toxins to suppress programmed cell death and the recycling of nutrients to delay the onset of senescence. These findings illustrate how resurrection plants manipulate sugar metabolism to promote desiccation tolerance and may provide candidate genes that are potentially useful for the development of stress tolerant crops.

  17. Avermectin induced autophagy in pigeon spleen tissues.

    Science.gov (United States)

    Liu, Ci; Zhao, Yanbing; Chen, Lijie; Zhang, Ziwei; Li, Ming; Li, Shu

    2015-12-05

    The level of autophagy is considered as an indicator for monitoring the toxic impact of pesticide exposure. Avermectin (AVM), a widely used insecticide, has immunotoxic effects on the pigeon spleen. The aim of this study was to investigate the status of autophagy and the expression levels of microtubule-associated protein1 light chain 3 (LC3), beclin-1, dynein, autophagy associated gene (Atg) 4B, Atg5, target of rapamycin complex 1 (TORC1) and target of rapamycin complex 2 (TORC2) in AVM-treated pigeon spleens. Eighty two-month-old pigeons were randomly divided into four groups: a control group, a low-dose group, a medium-dose group and a high-dose group, which were fed a basal diet spiked with 0, 20, 40 and 60 mg AVM/kg diet, respectively. Microscopic cellular morphology revealed a significant increase in autophagic structures in the AVM-treated groups. The expression of LC3, beclin-1, dynein, Atg4B and Atg5 increased, while mRNA levels of TORC1 and TORC2 were decreased in the AVM-treated groups relative to the control groups at 30, 60 and 90 days in the pigeon spleen. These results indicated that AVM exposure could up-regulate the level of autophagy in a dose-time-dependent manner in the pigeon spleen.

  18. Spermidine and resveratrol induce autophagy by distinct pathways converging on the acetylproteome

    DEFF Research Database (Denmark)

    Morselli, Eugenia; Mariño, Guillermo; Bennetzen, Martin V

    2011-01-01

    Autophagy protects organelles, cells, and organisms against several stress conditions. Induction of autophagy by resveratrol requires the nicotinamide adenine dinucleotide-dependent deacetylase sirtuin 1 (SIRT1). In this paper, we show that the acetylase inhibitor spermidine stimulates autophagy ...

  19. The Impact of Autophagy on Cell Death Modalities

    Directory of Open Access Journals (Sweden)

    Stefan W. Ryter

    2014-01-01

    Full Text Available Autophagy represents a homeostatic cellular mechanism for the turnover of organelles and proteins, through a lysosome-dependent degradation pathway. During starvation, autophagy facilitates cell survival through the recycling of metabolic precursors. Additionally, autophagy can modulate other vital processes such as programmed cell death (e.g., apoptosis, inflammation, and adaptive immune mechanisms and thereby influence disease pathogenesis. Selective pathways can target distinct cargoes (e.g., mitochondria and proteins for autophagic degradation. At present, the causal relationship between autophagy and various forms of regulated or nonregulated cell death remains unclear. Autophagy can occur in association with necrosis-like cell death triggered by caspase inhibition. Autophagy and apoptosis have been shown to be coincident or antagonistic, depending on experimental context, and share cross-talk between signal transduction elements. Autophagy may modulate the outcome of other regulated forms of cell death such as necroptosis. Recent advances suggest that autophagy can dampen inflammatory responses, including inflammasome-dependent caspase-1 activation and maturation of proinflammatory cytokines. Autophagy may also act as regulator of caspase-1 dependent cell death (pyroptosis. Strategies aimed at modulating autophagy may lead to therapeutic interventions for diseases in which apoptosis or other forms of regulated cell death may play a cardinal role.

  20. Mutant p53 protein localized in the cytoplasm inhibits autophagy.

    Science.gov (United States)

    Morselli, Eugenia; Tasdemir, Ezgi; Maiuri, Maria Chiara; Galluzzi, Lorenzo; Kepp, Oliver; Criollo, Alfredo; Vicencio, José Miguel; Soussi, Thierry; Kroemer, Guido

    2008-10-01

    The knockout, knockdown or chemical inhibition of p53 stimulates autophagy. Moreover, autophagy-inducing stimuli such as nutrient depletion, rapamycin or lithium cause the depletion of cytoplasmic p53, which in turn is required for the induction of autophagy. Here, we show that retransfection of p53(-/-) HCT 116 colon carcinoma cells with wild type p53 decreases autophagy down to baseline levels. Surprisingly, one third among a panel of 22 cancer-associated p53 single amino acid mutants also inhibited autophagy when transfected into p53(-/-) cells. Those variants of p53 that preferentially localize to the cytoplasm effectively repressed autophagy, whereas p53 mutants that display a prominently nuclear distribution failed to inhibit autophagy. The investigation of a series of deletion mutants revealed that removal of the DNA-binding domain from p53 fails to interfere with its role in the regulation of autophagy. Altogether, these results identify the cytoplasmic localization of p53 as the most important feature for p53-mediated autophagy inhibition. Moreover, the structural requirements for the two biological activities of extranuclear p53, namely induction of apoptosis and inhibition of autophagy, are manifestly different.

  1. Autophagy modulates articular cartilage vesicle formation in primary articular chondrocytes.

    Science.gov (United States)

    Rosenthal, Ann K; Gohr, Claudia M; Mitton-Fitzgerald, Elizabeth; Grewal, Rupinder; Ninomiya, James; Coyne, Carolyn B; Jackson, William T

    2015-05-22

    Chondrocyte-derived extracellular organelles known as articular cartilage vesicles (ACVs) participate in non-classical protein secretion, intercellular communication, and pathologic calcification. Factors affecting ACV formation and release remain poorly characterized; although in some cell types, the generation of extracellular vesicles is associated with up-regulation of autophagy. We sought to determine the role of autophagy in ACV production by primary articular chondrocytes. Using an innovative dynamic model with a light scatter nanoparticle counting apparatus, we determined the effects of autophagy modulators on ACV number and content in conditioned medium from normal adult porcine and human osteoarthritic chondrocytes. Healthy articular chondrocytes release ACVs into conditioned medium and show significant levels of ongoing autophagy. Rapamycin, which promotes autophagy, increased ACV numbers in a dose- and time-dependent manner associated with increased levels of autophagy markers and autophagosome formation. These effects were suppressed by pharmacologic autophagy inhibitors and short interfering RNA for ATG5. Caspase-3 inhibition and a Rho/ROCK inhibitor prevented rapamycin-induced increases in ACV number. Osteoarthritic chondrocytes, which are deficient in autophagy, did not increase ACV number in response to rapamycin. SMER28, which induces autophagy via an mTOR-independent mechanism, also increased ACV number. ACVs induced under all conditions had similar ecto-enzyme specific activities and types of RNA, and all ACVs contained LC3, an autophagosome-resident protein. These findings identify autophagy as a critical participant in ACV formation, and augment our understanding of ACVs in cartilage disease and repair.

  2. Crosstalk of clock gene expression and autophagy in aging

    Science.gov (United States)

    Kalfalah, Faiza; Janke, Linda; Schiavi, Alfonso; Tigges, Julia; Ix, Alexander; Ventura, Natascia; Boege, Fritz; Reinke, Hans

    2016-01-01

    Autophagy and the circadian clock counteract tissue degeneration and support longevity in many organisms. Accumulating evidence indicates that aging compromises both the circadian clock and autophagy but the mechanisms involved are unknown. Here we show that the expression levels of transcriptional repressor components of the circadian oscillator, most prominently the human Period homologue PER2, are strongly reduced in primary dermal fibroblasts from aged humans, while raising the expression of PER2 in the same cells partially restores diminished autophagy levels. The link between clock gene expression and autophagy is corroborated by the finding that the circadian clock drives cell-autonomous, rhythmic autophagy levels in immortalized murine fibroblasts, and that siRNA-mediated downregulation of PER2 decreases autophagy levels while leaving core clock oscillations intact. Moreover, the Period homologue lin-42 regulates autophagy and life span in the nematode Caenorhabditis elegans, suggesting an evolutionarily conserved role for Period proteins in autophagy control and aging. Taken together, this study identifies circadian clock proteins as set-point regulators of autophagy and puts forward a model, in which age-related changes of clock gene expression promote declining autophagy levels. PMID:27574892

  3. Combined therapy with m-TOR-dependent and -independent autophagy inducers causes neurotoxicity in a mouse model of Machado-Joseph disease.

    Science.gov (United States)

    Duarte-Silva, S; Silva-Fernandes, A; Neves-Carvalho, A; Soares-Cunha, C; Teixeira-Castro, A; Maciel, P

    2016-01-28

    A major pathological hallmark in several neurodegenerative disorders, like polyglutamine disorders (polyQ), including Machado-Joseph disease (MJD), is the formation of protein aggregates. MJD is caused by a CAG repeat expansion in the ATXN3 gene, resulting in an abnormal protein, which is prone to misfolding and forms cytoplasmic and nuclear aggregates within neurons, ultimately inducing neurodegeneration. Treatment of proteinopathies with drugs that up-regulate autophagy has shown promising results in models of polyQ diseases. Temsirolimus (CCI-779) inhibits the mammalian target of rapamycin (m-TOR), while lithium chloride (LiCl) acts by inhibiting inositol monophosphatase, both being able to induce autophagy. We have previously shown that chronic treatment with LiCl (10.4 mg/kg) had limited effects in a transgenic MJD mouse model. Also, others have shown that CCI-779 had mild positive effects in a different mouse model of the disease. It has been suggested that the combination of mTOR-dependent and -independent autophagy inducers could be a more effective therapeutic approach. To further explore this avenue toward therapy, we treated CMVMJD135 transgenic mice with a conjugation of CCI-779 and LiCl, both at concentrations known to induce autophagy and not to be toxic. Surprisingly, this combined treatment proved to be deleterious to both wild-type (wt) and transgenic animals, failing to rescue their neurological symptoms and actually exerting neurotoxic effects. These results highlight the possible dangers of manipulating autophagy in the nervous system and suggest that a better understanding of the potential disruption in the autophagy pathway in MJD is required before successful long-term autophagy modulating therapies can be developed.

  4. Induction of cytoprotective autophagy in PC-12 cells by cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiwen [College of Veterinary Medicine, Yangzhou University, Yangzhou 225009 (China); Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009 (China); Bijie Pilot Area Research Institute of Bijie University, Bijie 551700 (China); Zhu, Jiaqiao; Zhang, Kangbao; Jiang, Chenyang; Wang, Yi; Yuan, Yan; Bian, Jianchun; Liu, Xuezhong; Gu, Jianhong [College of Veterinary Medicine, Yangzhou University, Yangzhou 225009 (China); Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009 (China); Liu, Zongping, E-mail: liuzongping@yzu.edu.cn [College of Veterinary Medicine, Yangzhou University, Yangzhou 225009 (China); Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009 (China)

    2013-08-16

    Highlights: •Cadmium can promote early upregulation of autophagy in PC-12 cells. •Autophagy precedes apoptosis in cadmium-treated PC-12 cells. •Cadmium-induced autophagy is cytoprotective in PC-12 cells. •Class III PI3K/beclin-1/Bcl-2 signaling pathway plays a positive role in cadmium-triggered autophagy. -- Abstract: Laboratory data have demonstrated that cadmium (Cd) may induce neuronal apoptosis. However, little is known about the role of autophagy in neurons. In this study, cell viability decreased in a dose- and time-dependent manner after treatment with Cd in PC-12 cells. As cells were exposed to Cd, the levels of LC3-II proteins became elevated, specific punctate distribution of endogenous LC3-II increased, and numerous autophagosomes appeared, which suggest that Cd induced a high level of autophagy. In the late stages of autophagy, an increase in the apoptosis ratio was observed. Likewise, pre-treatment with chloroquine (an autophagic inhibitor) and rapamycin (an autophagic inducer) resulted in an increased and decreased percentage of apoptosis in contrast to other Cd-treated groups, respectively. The results indicate that autophagy delayed apoptosis in Cd-treated PC-12 cells. Furthermore, co-treatment of cells with chloroquine reduced autophagy and cell activity. However, rapamycin had an opposite effect on autophagy and cell activity. Moreover, class III PI3 K/beclin-1/Bcl-2 signaling pathways served a function in Cd-induced autophagy. The findings suggest that Cd can induce cytoprotective autophagy by activating class III PI3 K/beclin-1/Bcl-2 signaling pathways. In sum, this study strongly suggests that autophagy may serve a positive function in the reduction of Cd-induced cytotoxicity.

  5. Autophagy-related prognostic signature for breast cancer.

    Science.gov (United States)

    Gu, Yunyan; Li, Pengfei; Peng, Fuduan; Zhang, Mengmeng; Zhang, Yuanyuan; Liang, Haihai; Zhao, Wenyuan; Qi, Lishuang; Wang, Hongwei; Wang, Chenguang; Guo, Zheng

    2016-03-01

    Autophagy is a process that degrades intracellular constituents, such as long-lived or damaged proteins and organelles, to buffer metabolic stress under starvation conditions. Deregulation of autophagy is involved in the progression of cancer. However, the predictive value of autophagy for breast cancer prognosis remains unclear. First, based on gene expression profiling, we found that autophagy genes were implicated in breast cancer. Then, using the Cox proportional hazard regression model, we detected autophagy prognostic signature for breast cancer in a training dataset. We identified a set of eight autophagy genes (BCL2, BIRC5, EIF4EBP1, ERO1L, FOS, GAPDH, ITPR1 and VEGFA) that were significantly associated with overall survival in breast cancer. The eight autophagy genes were assigned as a autophagy-related prognostic signature for breast cancer. Based on the autophagy-related signature, the training dataset GSE21653 could be classified into high-risk and low-risk subgroups with significantly different survival times (HR = 2.72, 95% CI = (1.91, 3.87); P = 1.37 × 10(-5)). Inactivation of autophagy was associated with shortened survival of breast cancer patients. The prognostic value of the autophagy-related signature was confirmed in the testing dataset GSE3494 (HR = 2.12, 95% CI = (1.48, 3.03); P = 1.65 × 10(-3)) and GSE7390 (HR = 1.76, 95% CI = (1.22, 2.54); P = 9.95 × 10(-4)). Further analysis revealed that the prognostic value of the autophagy signature was independent of known clinical prognostic factors, including age, tumor size, grade, estrogen receptor status, progesterone receptor status, ERBB2 status, lymph node status and TP53 mutation status. Finally, we demonstrated that the autophagy signature could also predict distant metastasis-free survival for breast cancer.

  6. Autophagy facilitates Salmonella replication in HeLa cells.

    Science.gov (United States)

    Yu, Hong B; Croxen, Matthew A; Marchiando, Amanda M; Ferreira, Rosana B R; Cadwell, Ken; Foster, Leonard J; Finlay, B Brett

    2014-03-11

    Autophagy is a process whereby a double-membrane structure (autophagosome) engulfs unnecessary cytosolic proteins, organelles, and invading pathogens and delivers them to the lysosome for degradation. We examined the fate of cytosolic Salmonella targeted by autophagy and found that autophagy-targeted Salmonella present in the cytosol of HeLa cells correlates with intracellular bacterial replication. Real-time analyses revealed that a subset of cytosolic Salmonella extensively associates with autophagy components p62 and/or LC3 and replicates quickly, whereas intravacuolar Salmonella shows no or very limited association with p62 or LC3 and replicates much more slowly. Replication of cytosolic Salmonella in HeLa cells is significantly decreased when autophagy components are depleted. Eventually, hyperreplication of cytosolic Salmonella potentiates cell detachment, facilitating the dissemination of Salmonella to neighboring cells. We propose that Salmonella benefits from autophagy for its cytosolic replication in HeLa cells. IMPORTANCE As a host defense system, autophagy is known to target a population of Salmonella for degradation and hence restricting Salmonella replication. In contrast to this concept, a recent report showed that knockdown of Rab1, a GTPase required for autophagy of Salmonella, decreases Salmonella replication in HeLa cells. Here, we have reexamined the fate of Salmonella targeted by autophagy by various cell biology-based assays. We found that the association of autophagy components with cytosolic Salmonella increases shortly after initiation of intracellular bacterial replication. Furthermore, through a live-cell imaging method, a subset of cytosolic Salmonella was found to be extensively associated with autophagy components p62 and/or LC3, and they replicated quickly. Most importantly, depletion of autophagy components significantly reduced the replication of cytosolic Salmonella in HeLa cells. Hence, in contrast to previous reports, we propose

  7. Water Evaporation and Conformational Changes from Partially Solvated Ubiquitin

    Directory of Open Access Journals (Sweden)

    Saravana Prakash Thirumuruganandham

    2010-01-01

    Full Text Available Using molecular dynamics simulation, we study the evaporation of water molecules off partially solvated ubiquitin. The evaporation and cooling rates are determined for a molecule at the initial temperature of 300 K. The cooling rate is found to be around 3 K/ns, and decreases with water temperature in the course of the evaporation. The conformation changes are monitored by studying a variety of intermediate partially solvated ubiquitin structures. We find that ubiquitin shrinks with decreasing hydration shell and exposes more of its hydrophilic surface area to the surrounding.

  8. FONCTIONS UBIQUITINE-DEPENDANTES DE LA DEACETYLASE HDAC6

    OpenAIRE

    Boyault, Cyril

    2006-01-01

    At the start of my Ph.D., the lab had discovered and characterized HDAC6, an unusual deacetylase that possesses two deacetylase domains and directly binds to ubiquitin. Moreover, the lab had found that HDAC6 interacts with UFD3/PLAP, a regulator of ubiquitin turnover, and VCP, a mouse homologue of the chaperone Cdc48. However, nothing was known about HDAC6 biological function, especially its role in the ubiquitination pathway. We first observed that HDAC6 over-expression slows down the degrad...

  9. The multiple levels of regulation by p53 ubiquitination

    OpenAIRE

    Lee, JT; Gu, W

    2010-01-01

    p53 is a central integrator of a plethora of signals and outputs these signals in the form of tumor suppression. It is well accepted that ubiquitination plays a major part in p53 regulation. Nonetheless, the molecular mechanisms by which p53 activity is controlled by ubiquitination are complex. Mdm2, a RING oncoprotein, was once thought to be the sole E3 ubiquitin ligase for p53, however recent studies have shown that p53 is stabilized but still degraded in the cells of Mdm2-null mice. Althou...

  10. Altered gene expression and repressed markers of autophagy in skeletal muscle of insulin resistant patients with type 2 diabetes

    Science.gov (United States)

    Møller, Andreas Buch; Kampmann, Ulla; Hedegaard, Jakob; Thorsen, Kasper; Nordentoft, Iver; Vendelbo, Mikkel Holm; Møller, Niels; Jessen, Niels

    2017-01-01

    This case-control study was designed to investigate the gene expression profile in skeletal muscle from severely insulin resistant patients with long-standing type 2 diabetes (T2D), and to determine associated signaling pathways. Gene expression profiles were examined by whole transcriptome, strand-specific RNA-sequencing and associated signaling was determined by western blot. We identified 117 differentially expressed gene transcripts. Ingenuity Pathway Analysis related these differences to abnormal muscle morphology and mitochondrial dysfunction. Despite a ~5-fold difference in plasma insulin, we did not observe any difference in phosphorylation of AKT or AS160, although other insulin-sensitive cascades, as mTOR/4EBP1, had retained their sensitivity. Autophagy-related gene (ATG14, RB1CC1/FIP200, GABARAPL1, SQSTM1/p62, and WIPI1) and protein (LC3BII, SQSTM1/p62 and ATG5) expression were decreased in skeletal muscle from the patients, and this was associated with a trend to increased phosphorylation of the insulin-sensitive regulatory transcription factor FOXO3a. These data show that gene expression is highly altered and related to mitochondrial dysfunction and abnormal morphology in skeletal muscle from severely insulin resistant patients with T2D, and that this is associated with decreased expression of autophagy-related genes and proteins. We speculate that prolonged treatment with high doses of insulin may suppress autophagy thereby generating a vicious cycle maintaining insulin resistance. PMID:28252104

  11. A role for PCNA ubiquitination in immunoglobulin hypermutation.

    Directory of Open Access Journals (Sweden)

    Hiroshi Arakawa

    2006-11-01

    Full Text Available Proliferating cell nuclear antigen (PCNA is a DNA polymerase cofactor and regulator of replication-linked functions. Upon DNA damage, yeast and vertebrate PCNA is modified at the conserved lysine K164 by ubiquitin, which mediates error-prone replication across lesions via translesion polymerases. We investigated the role of PCNA ubiquitination in variants of the DT40 B cell line that are mutant in K164 of PCNA or in Rad18, which is involved in PCNA ubiquitination. Remarkably, the PCNA(K164R mutation not only renders cells sensitive to DNA-damaging agents, but also strongly reduces activation induced deaminase-dependent single-nucleotide substitutions in the immunoglobulin light-chain locus. This is the first evidence, to our knowledge, that vertebrates exploit the PCNA-ubiquitin pathway for immunoglobulin hypermutation, most likely through the recruitment of error-prone DNA polymerases.

  12. Autophagy - Adaptive Molecular Mechanisms in Condition of Starvation

    Directory of Open Access Journals (Sweden)

    Pedrycz Agnieszka

    2015-09-01

    Full Text Available Autophagy is an extremely old process during which long-lived proteins and cellular organelles are removed by means of lysosomes. Autophagy may be caused by cellular stress mechanisms. Research has proven that autophagy plays a key role in obtaining nutrients and adapting to the conditions of starvation. Owing to this, it takes part in maintaining homeostasis in cytoplasm and cell nucleus. This objective may be achieved through a number of ways. Depending on the manner in which a substrate connects with the lysosome, we can talk about macroautophagy and microautophagy. Additionally, some authors also distinguish a chaperone-mediated autophagy. The article presented below describes molecular mechanisms of each type of autophagy and focuses particularly on macroautophagy, which is the best understood of all the autophagy types.

  13. Autophagy as a Therapeutic Target in Diabetic Nephropathy

    Directory of Open Access Journals (Sweden)

    Yuki Tanaka

    2012-01-01

    Full Text Available Diabetic nephropathy is a serious complication of diabetes mellitus, and its prevalence has been increasing worldwide. Therefore, there is an urgent need to identify a new therapeutic target to prevent diabetic nephropathy. Autophagy is a major catabolic pathway involved in degrading and recycling macromolecules and damaged organelles to maintain intracellular homeostasis. The study of autophagy in mammalian systems is advancing rapidly and has revealed that it is involved in the pathogenesis of various metabolic or age-related diseases. The functional role of autophagy in the kidneys is also currently under intense investigation although, until recently, evidence showing the involvement of autophagy in the pathogenesis of diabetic nephropathy has been limited. We provide a systematic review of autophagy and discuss the therapeutic potential of autophagy in diabetic nephropathy to help future investigations in this field.

  14. Suppression of autophagy exacerbates Mefloquine-mediated cell death.

    Science.gov (United States)

    Shin, Ji Hyun; Park, So Jung; Jo, Yoon Kyung; Kim, Eun Sung; Kang, Hee; Park, Ji-Ho; Lee, Eunjoo H; Cho, Dong-Hyung

    2012-05-02

    Mefloquine is an effective treatment drug for malaria. However, it can cause several adverse side effects, and the precise mechanism associated with the adverse neurological effects of Mefloquine is not clearly understood. In this study, we investigated the effect of Mefloquine on autophagy in neuroblastoma cells. Mefloquine treatment highly induced the formation of autophagosomes and the conversion of LC3I into LC3II. Moreover, Mefloquine-induced autophagy was efficiently suppressed by an autophagy inhibitor and by down regulation of ATG6. The autophagy was also completely blocked in ATG5 deficient mouse embryonic fibroblast cells. Moreover, suppression of autophagy significantly intensified Mefloquine-mediated cytotoxicity in SH-SY5Y cells. Our findings suggest that suppression of autophagy may exacerbate Mefloquine toxicity in neuroblastoma cells.

  15. Epigenetic modifications as regulatory elements of autophagy in cancer.

    Science.gov (United States)

    Sui, Xinbing; Zhu, Jing; Zhou, Jichun; Wang, Xian; Li, Da; Han, Weidong; Fang, Yong; Pan, Hongming

    2015-05-01

    Epigenetic modifications have been considered as hallmarks of cancer and play an important role in tumor initiation and development. Epigenetic mechanisms, including DNA methylation, histone modifications, and microRNAs, may regulate cell cycle and apoptosis, as well as macroautophagy (hereafter referred to as autophagy). Autophagy, as a crucial cellular homeostatic mechanism, performs a dual role, having pro-survival or pro-death properties. A variety of signaling pathways including epigenetic control have been implicated in the upregulation or downregulation of autophagy. However, the role of epigenetic regulation in autophagy is still less well acknowledged. Recent studies have linked epigenetic control to the autophagic process. Some epigenetic modifiers are also involved in the regulation of autophagy and potentiate the efficacy of traditional therapeutics. Thus, understanding the novel functions of epigenetic control in autophagy may allow us to develop potential therapeutic approaches for cancer treatment.

  16. Research Progression of Cellular Autophagy in Liver System Diseases

    Directory of Open Access Journals (Sweden)

    Chunyun Liu

    2013-09-01

    Full Text Available Autophagy is a basic biological phenomenon widely existed in eukaryotic cells and an important mechanism for cells to adjust to the surrounding environment, prevent invasion of pathogenic micro-organisms and maintain homeostasis, whose activity changes evidently in multiple liver system diseases, suggesting that there is close association between autophagy and the generation and development of liver system diseases. It is also reported that autophagy develops and exerts an important function in many liver-related diseases, such as hepatic carcinoma, non-alcoholic fatty liver disease, alcoholic liver disease, viral liver disease and acute liver injury. Therefore, this study aimed to summarize the relationship between autophagy and multiple liver diseases, hoping to explore the effect of autophagy in liver system diseases and further study the regulative effect of autophagy so as to provide new thoughts for their treatment.

  17. Forms, Crosstalks, and the Role of Phospholipid Biosynthesis in Autophagy

    Directory of Open Access Journals (Sweden)

    Leanne Pereira

    2012-01-01

    Full Text Available Autophagy is a highly conserved cellular process occurring during periods of stress to ensure a cell's survival by recycling cytosolic constituents and making products that can be used in energy generation and other essential processes. Three major forms of autophagy exist according to the specific mechanism through which cytoplasmic material is transported to a lysosome. Chaperone-mediated autophagy is a highly selective form of autophagy that delivers specific proteins for lysosomal degradation. Microautophagy is a less selective form of autophagy that occurs through lysosomal membrane invaginations, forming tubes and directly engulfing cytoplasm. Finally, macroautophagy involves formation of new membrane bilayers (autophagosomes that engulf cytosolic material and deliver it to lysosomes. This review provides new insights on the crosstalks between different forms of autophagy and the significance of bilayer-forming phospholipid synthesis in autophagosomal membrane formation.

  18. Methods for assessing autophagy and autophagic cell death.

    Science.gov (United States)

    Tasdemir, Ezgi; Galluzzi, Lorenzo; Maiuri, M Chiara; Criollo, Alfredo; Vitale, Ilio; Hangen, Emilie; Modjtahedi, Nazanine; Kroemer, Guido

    2008-01-01

    Autophagic (or type 2) cell death is characterized by the massive accumulation of autophagic vacuoles (autophagosomes) in the cytoplasm of cells that lack signs of apoptosis (type 1 cell death). Here we detail and critically assess a series of methods to promote and inhibit autophagy via pharmacological and genetic manipulations. We also review the techniques currently available to detect autophagy, including transmission electron microscopy, half-life assessments of long-lived proteins, detection of LC3 maturation/aggregation, fluorescence microscopy, and colocalization of mitochondrion- or endoplasmic reticulum-specific markers with lysosomal proteins. Massive autophagic vacuolization may cause cellular stress and represent a frustrated attempt of adaptation. In this case, cell death occurs with (or in spite of) autophagy. When cell death occurs through autophagy, on the contrary, the inhibition of the autophagic process should prevent cellular demise. Accordingly, we describe a strategy for discriminating cell death with autophagy from cell death through autophagy.

  19. Research Progression of Cellular Autophagy in Liver System Diseases

    Institute of Scientific and Technical Information of China (English)

    Liu Chunyun; Gong Xiangwen; Xiao Xinfa; Yuan Xiangying

    2013-01-01

    Autophagy is a basic biological phenomenon widely existed in eukaryotic cells and an important mechanism for cells to adjust to the surrounding environment, prevent invasion of pathogenic micro-organisms and maintain homeostasis, whose activity changes evidently in multiple liver system diseases, suggesting that there is close association between autophagy and the generation and development of liver system diseases. It is also reported that autophagy develops and exerts an important function in many liver-related diseases, such as hepatic carcinoma, non-alcoholic fatty liver disease, alcoholic liver disease, viral liver disease and acute liver injury. Therefore, this study aimed to summarize the relationship between autophagy and multiple liver diseases, hoping to explore the effect of autophagy in liver system diseases and further study the regulative effect of autophagy so as to provide new thoughts for their treatment.

  20. [Hair shaft abnormalities].

    Science.gov (United States)

    Itin, P H; Düggelin, M

    2002-05-01

    Hair shaft disorders may lead to brittleness and uncombable hair. In general the hair feels dry and lusterless. Hair shaft abnormalities may occur as localized or generalized disorders. Genetic predisposition or exogenous factors are able to produce and maintain hair shaft abnormalities. In addition to an extensive history and physical examination the most important diagnostic examination to analyze a hair shaft problem is light microscopy. Therapy of hair shaft disorders should focus to the cause. In addition, minimizing traumatic influences to hair shafts, such as dry hair with an electric dryer, permanent waves and dyes is important. A short hair style is more suitable for such patients with hair shaft disorders.

  1. Autophagy and mitochondrial dysfunction in adjuvant-arthritis rats treatment with resveratrol

    Science.gov (United States)

    Zhang, Junqiang; Song, Xianbin; Cao, Wei; Lu, Jinseng; Wang, Xiaoqing; Wang, Gaoyuan; Wang, Zhicheng; Chen, Xiaoyu

    2016-01-01

    Resveratrol is a polyphenol derivatives which exhibits a pro-apoptotic effect in a variety of human cancers by triggering mitochondria apoptosis pathway and autophagy. However, there are scarcely reports on its apoptosis-promoting effect in abnormal proliferation fibroblast-like synoviocytes (FLSs). In this study, we investigated the underlying mechanism and apoptosis-inducing effects of resveratrol on the abnormal proliferation of FLSs in adjuvant-arthritis (AA) rats. Since using resveratrol for 12 days resulted in a significant decreasing the swelling degree of the paw, reducing malondialdehyde (MDA) content and enhancing superoxide dismutase (SOD) activity, antioxidant capacity, glutathione peroxidase and glutathione reductase ratio in AA rats. Moreover, we found that 5 μMH2O2 could increase cells viability, Beclin1, LC3A/B, MnSOD, SIRT3 protein expression in FLSs. But, resveratrol could reverse these effects by changing mitochondrial membrane potential (Δψm) to promote mitochondrial reactive oxygen species (mtROS) generation in 5 μMH2O2-treatment FLSs. These results suggest that oxidative stress existed in AA rats. Resveratrol could suppress oxidative stress in AA rats and increase mtROS production by reducing autophagy protein Beclin1, LC3A/B and oxidative stress protein MnSOD to promoted the apoptosis of FLSs. Thus, targeting of mtROS may be a crucial mechanism of resveratrol confers patients with rheumatoid arthritis. PMID:27611176

  2. Targeting the ER-autophagy system in the trabecular meshwork to treat glaucoma.

    Science.gov (United States)

    Stothert, Andrew R; Fontaine, Sarah N; Sabbagh, Jonathan J; Dickey, Chad A

    2016-03-01

    A major drainage network involved in aqueous humor dynamics is the conventional outflow pathway, which is gated by the trabecular meshwork (TM). The TM acts as a molecular sieve, providing resistance to aqueous outflow, which is responsible for regulating intraocular pressure (IOP). If the TM is damaged, aqueous outflow is impaired, IOP increases and glaucoma can manifest. Mutations in the MYOC gene cause hereditary primary open-angle glaucoma (POAG) by promoting the abnormal amyloidosis of the myocilin protein in the endoplasmic reticulum (ER), leading to ER stress-induced TM cell death. Myocilin accumulation is observed in approximately 70-80% of all glaucoma cases suggesting that environmental or other genetic factors may also promote myocilin toxicity. For example, simply preventing myocilin glycosylation is sufficient to promote its abnormal accretion. These myocilin amyloids are unique as there are no other known pathogenic proteins that accumulate within the ER of TM cells and cause toxicity. Moreover, this pathogenic accumulation only kills TM cells, despite expression of this protein in other cell types, suggesting that another modifier exclusive to the TM participates in the proteotoxicity of myocilin. ER autophagy (reticulophagy) is one of the pathways essential for myocilin clearance that can be impacted dramatically by aging and other environmental factors such as nutrition. This review will discuss the link between myocilin and autophagy, evaluating the role of this degradation pathway in glaucoma as well as its potential as a therapeutic target.

  3. Integrated analysis of microarray data of atherosclerotic plaques: modulation of the ubiquitin-proteasome system.

    Directory of Open Access Journals (Sweden)

    Zhe Wang

    Full Text Available Atherosclerosis is a typical complex multi-factorial disease and many molecules at different levels and pathways were involved in its development. Some studies have investigated the dysregulation in atherosclerosis at mRNA, miRNA or DNA methylation level, respectively. However, to our knowledge, the studies that integrated these data and revealed the abnormal networks of atherosclerosis have not been reported. Using microarray technology, we analyzed the omics data in atherosclerosis at mRNA, miRNA and DNA methylation levels. Our results demonstrated that the global DNA methylation and expression of miRNA/mRNA were significantly decreased in atherosclerotic plaque than in normal vascular tissue. The interaction network constructed using the integrative data revealed many genes, cellular processes and signaling pathways which were widely considered to play crucial roles in atherosclerosis and also revealed some genes, miRNAs or signaling pathways which have not been investigated in atherosclerosis until now (e.g. miR-519d and SNTB2. Moreover, the overall protein ubiquitination in atherosclerotic plaque was significantly increased. The proteasome activity was increased early but decreased in advanced atherosclerosis. Our study revealed many classic and novel genes and miRNAs involved in atherosclerosis and indicated the effects of ubiquitin-proteasome system on atherosclerosis might be closely related to the course of atherosclerosis. However, the efficacy of proteasome inhibitors in the treatment of atherosclerosis still needs more research.

  4. Ubiquitination profiling identifies sensitivity factors for IAP antagonist treatment.

    Science.gov (United States)

    Varfolomeev, Eugene; Izrael-Tomasevic, Anita; Yu, Kebing; Bustos, Daisy; Goncharov, Tatiana; Belmont, Lisa D; Masselot, Alexandre; Bakalarski, Corey E; Kirkpatrick, Donald S; Vucic, Domagoj

    2015-02-15

    Evasion of cell death is one crucial capability acquired by tumour cells to ward-off anti-tumour therapies and represents a fundamental challenge to sustaining clinical efficacy for currently available agents. Inhibitor of apoptosis (IAP) proteins use their ubiquitin E3 ligase activity to promote cancer cell survival by mediating proliferative signalling and blocking cell death in response to diverse stimuli. Using immunoaffinity enrichment and MS, ubiquitination sites on thousands of proteins were profiled upon initiation of cell death by IAP antagonists in IAP antagonist-sensitive and -resistant breast cancer cell lines. Our analyses identified hundreds of proteins with elevated levels of ubiquitin-remnant [K-GG (Lys-Gly-Gly)] peptides upon activation of cell death by the IAP antagonist BV6. The majority of these were observed in BV6-sensitive, but not-resistant, cells. Among these were known pro-apoptotic regulators, including CYC (cytochrome c), RIP1 (receptor-interacting protein 1) and a selection of proteins known to reside in the mitochondria or regulate NF-κB (nuclear factor κB) signalling. Analysis of early time-points revealed that IAP antagonist treatment stimulated rapid ubiquitination of NF-κB signalling proteins, including TRAF2 [TNF (tumour necrosis factor) receptor-associated factor 2], HOIL-1 (haem-oxidized iron-regulatory protein 2 ubiquitin ligase-1), NEMO (NF-κB essential modifier), as well as c-IAP1 (cellular IAP1) auto-ubiquitination. Knockdown of several NF-κB pathway members reduced BV6-induced cell death and TNF production in sensitive cell lines. Importantly, RIP1 was found to be constitutively ubiquitinated in sensitive breast-cancer cell lines at higher basal level than in resistant cell lines. Together, these data show the diverse and temporally defined roles of protein ubiquitination following IAP-antagonist treatment and provide critical insights into predictive diagnostics that may enhance clinical efficacy.

  5. Targeting Pediatric Glioma with Apoptosis and Autophagy Manipulation

    Science.gov (United States)

    2014-10-01

    shRNA against RAB7. We chose this because RAB7 similar to chloroquine, effects late stage autophagy with lysosomal fusion to the autophagosome. Thus...hypothesis that late stage autophagosome fusion with the lysosome and degradation of the components and recycling of the macronutrients is critical to...of autophagy, Rab7 and Lamp 2. We are now introducing siRNA against Rab7 and Lamp2 to reiterate the effects of Chloroquine inhibition of autophagy

  6. Characterization of early autophagy signaling by quantitative phosphoproteomics

    DEFF Research Database (Denmark)

    Rigbolt, Kristoffer Tg; Zarei, Mostafa; Sprenger, Adrian;

    2014-01-01

    Under conditions of nutrient shortage autophagy is the primary cellular mechanism ensuring availability of substrates for continuous biosynthesis. Subjecting cells to starvation or rapamycin efficiently induces autophagy by inhibiting the MTOR signaling pathway triggering increased autophagic flux....... To elucidate the regulation of early signaling events upon autophagy induction, we applied quantitative phosphoproteomics characterizing the temporal phosphorylation dynamics after starvation and rapamycin treatment. We obtained a comprehensive atlas of phosphorylation kinetics within the first 30 min upon...

  7. Beclin 1 complex in autophagy and Alzheimer disease.

    Science.gov (United States)

    Jaeger, Philipp A; Wyss-Coray, Tony

    2010-10-01

    Beclin 1 is a protein involved in the regulation of autophagy and has been shown to be reduced in patients with Alzheimer disease. This review summarizes the current research data that link disturbances in autophagy, a cellular degradation and maintenance pathway, to the development of Alzheimer disease and related neurodegenerative diseases. It also provides a brief overview of the existing pharmacological interventions available to modulate autophagy activity in mammalian cells.

  8. Hsp90 regulates processing of NF-κB2 p100 involving protection of NF-κB-inducing kinase (NIK) from autophagy-mediated degradation

    Institute of Scientific and Technical Information of China (English)

    Guoliang Qing; Pengrong Yan; Zhaoxia Qu; Hudan Liu; Gutian Xiao

    2007-01-01

    NF-κB-inducing kinase (NIK) is required for NF-κB activation based on the processing of NF-κB2 p100. Here we report a novel mechanism of NIK regulation involving the chaperone 90 kDa heat shock protein (Hsp90) and autophagy.Functional inhibition of lisp90 by the anti-tumor agent geldanamycin (GA) efficiently disrupts its interaction with NIK,resulting in NIK degradation and subsequent blockage of p100 processing. Surprisingly, GA-induced NIK degradation is mediated by autophagy, but largely independent of the ubiquitin-proteasome system. Hsp90 seems to be specifically involved in the folding/stabilization of NIK protein, because GA inhibition does not affect NIK mRNA transcription and translation. Furthermore, Hsp90 is not required for NIK-mediated recruitment of the α subunit of IκB kinase to p100, a key step in induction of p100 processing. These findings define an alternative mechanism for Hsp90 client degradation and identify a novel function of autophagy in NF-κB regulation. These findings also suggest a new therapeutic strategy for diseases associated with p100 processing.

  9. Detection of ubiquitinated huntingtin species in intracellular aggregates

    Directory of Open Access Journals (Sweden)

    Katrin eJuenemann

    2015-01-01

    Full Text Available Protein conformation diseases, including polyglutamine diseases, result from the accumulation and aggregation of misfolded proteins. Huntington’s disease is one of nine diseases caused by an expanded polyglutamine repeat within the affected protein and is hallmarked by intracellular inclusion bodies composed of aggregated N-terminal huntingtin fragments and other sequestered proteins. Fluorescence microscopy and filter trap assay are conventional methods to study protein aggregates, but cannot be used to analyze the presence and levels of post-translational modifications of aggregated huntingtin such as ubiquitination. Ubiquitination of proteins can be a signal for degradation and intracellular localization, but also affects protein activity and protein-protein interactions. The function of ubiquitination relies on its mono- and polymeric isoforms attached to protein substrates. Studying the ubiquitination pattern of aggregated huntingtin fragments offers an important possibility to understand huntingtin degradation and aggregation processes within the cell. For the identification of aggregated huntingtin and its ubiquitinated species, solubilization of the cellular aggregates is mandatory. Here we describe methods to identify post-translational modifications such as ubiquitination of aggregated mutant huntingtin. This approach is specifically described for use with mammalian cell culture and is suitable to study other disease-related proteins prone to aggregate.

  10. Ancient origin of animal U-box ubiquitin ligases

    Directory of Open Access Journals (Sweden)

    Marín Ignacio

    2010-10-01

    Full Text Available Abstract Background The patterns of emergence and diversification of the families of ubiquitin ligases provide insights about the evolution of the eukaryotic ubiquitination system. U-box ubiquitin ligases (UULs are proteins characterized by containing a peculiar protein domain known as U box. In this study, the origin of the animal UUL genes is described. Results Phylogenetic and structural data indicate that six of the seven main UUL-encoding genes found in humans (UBE4A, UBE4B, UIP5, PRP19, CHIP and CYC4 were already present in the ancestor of all current metazoans and the seventh (WDSUB1 is found in placozoans, cnidarians and bilaterians. The fact that only 4 - 5 genes orthologous to the human ones are present in the choanoflagellate Monosiga brevicollis suggests that several animal-specific cooptions of the U box to generate new genes occurred. Significantly, Monosiga contains five additional UUL genes that are not present in animals. One of them is also present in distantly-related protozoans. Along animal evolution, losses of UUL-encoding genes are rare, except in nematodes, which lack three of them. These general patterns are highly congruent with those found for other two families (RBR, HECT of ubiquitin ligases. Conclusions Finding that the patterns of emergence, diversification and loss of three unrelated families of ubiquitin ligases (RBR, HECT and U-box are parallel indicates that there are underlying, linage-specific evolutionary forces shaping the complexity of the animal ubiquitin system.

  11. Picosecond to Millisecond Structural Dynamics in Human Ubiquitin.

    Science.gov (United States)

    Lindorff-Larsen, Kresten; Maragakis, Paul; Piana, Stefano; Shaw, David E

    2016-08-25

    Human ubiquitin has been extensively characterized using a variety of experimental and computational methods and has become an important model for studying protein dynamics. Nevertheless, it has proven difficult to characterize the microsecond time scale dynamics of this protein with atomistic resolution. Here we use an unbiased computer simulation to describe the structural dynamics of ubiquitin on the picosecond to millisecond time scale. In the simulation, ubiquitin interconverts between a small number of distinct states on the microsecond to millisecond time scale. We find that the conformations visited by free ubiquitin in solution are very similar to those found various crystal structures of ubiquitin in complex with other proteins, a finding in line with previous experimental studies. We also observe weak but statistically significant correlated motions throughout the protein, including long-range concerted movement across the entire β sheet, consistent with recent experimental observations. We expect that the detailed atomistic description of ubiquitin dynamics provided by this unbiased simulation may be useful in interpreting current and future experiments on this protein.

  12. Absence of the Autophagy Adaptor SQSTM1/p62 Causes Childhood-Onset Neurodegeneration with Ataxia, Dystonia, and Gaze Palsy.

    Science.gov (United States)

    Haack, Tobias B; Ignatius, Erika; Calvo-Garrido, Javier; Iuso, Arcangela; Isohanni, Pirjo; Maffezzini, Camilla; Lönnqvist, Tuula; Suomalainen, Anu; Gorza, Matteo; Kremer, Laura S; Graf, Elisabeth; Hartig, Monika; Berutti, Riccardo; Paucar, Martin; Svenningsson, Per; Stranneheim, Henrik; Brandberg, Göran; Wedell, Anna; Kurian, Manju A; Hayflick, Susan A; Venco, Paola; Tiranti, Valeria; Strom, Tim M; Dichgans, Martin; Horvath, Rita; Holinski-Feder, Elke; Freyer, Christoph; Meitinger, Thomas; Prokisch, Holger; Senderek, Jan; Wredenberg, Anna; Carroll, Christopher J; Klopstock, Thomas

    2016-09-01

    SQSTM1 (sequestosome 1; also known as p62) encodes a multidomain scaffolding protein involved in various key cellular processes, including the removal of damaged mitochondria by its function as a selective autophagy receptor. Heterozygous variants in SQSTM1 have been associated with Paget disease of the bone and might contribute to neurodegeneration in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Using exome sequencing, we identified three different biallelic loss-of-function variants in SQSTM1 in nine affected individuals from four families with a childhood- or adolescence-onset neurodegenerative disorder characterized by gait abnormalities, ataxia, dysarthria, dystonia, vertical gaze palsy, and cognitive decline. We confirmed absence of the SQSTM1/p62 protein in affected individuals' fibroblasts and found evidence of a defect in the early response to mitochondrial depolarization and autophagosome formation. Our findings expand the SQSTM1-associated phenotypic spectrum and lend further support to the concept of disturbed selective autophagy pathways in neurodegenerative diseases.

  13. 4th International Symposium on Autophagy: exploiting the frontiers of autophagy research.

    Science.gov (United States)

    Eskelinen, Eeva-Liisa; Deretic, Vojo; Neufeld, Thomas; Levine, Beth; Cuervo, Ana Maria

    2007-01-01

    The 4th International Symposium on Autophagy was held in Mishima, a small town between Tokyo and Kyoto, October 1-5, 2006 (http://isa4th.umin.jp/). The meeting was organized by the group of Eiki Kominami. Approximately 150 participants took part in this well-organized meeting in the spacious and comfortable Toray Conference Hall (Fig. 1). The social program offered opportunities for informal discussions, Japanese culture (from karaoke singing to traditional drumming; Fig. 2), history and nature (a visit to a steaming volcano; Fig. 3), as well as delicious Japanese food. The scientific program started with two plenary lectures on Sunday evening. Daniel Klionsky gave an overview of Atg9 cycling in yeast and Shigekazu Nagata talked about apoptosis and engulfment of dead cells by macrophages. The meeting consisted of five oral sessions and two poster sessions covering a wide range of autophagy-related topics. Exciting unpublished results were presented in all sessions, showing how quickly autophagy research is progressing. Two themes were discussed in many sessions during the symposium: the role of autophagy in the degradation of aggregate-prone proteins and protein aggregates, and the possible role of p62 in autophagy.

  14. Does autophagy take a front seat in lifespan extension?

    OpenAIRE

    Petrovski, Goran; Das, Dipak K

    2010-01-01

    Abstract This review focuses on the interrelationship between ageing and autophagy. There is a striking similarity between the signalling aspects of these two processes. Both ageing and autophagy involve several of the signalling components such as insulin/IGF-1, AMPK, Ras-cAMP-PKA, Sch9 and mTOR. Ageing and ageing-mediated defective autophagy involve accumulation of lipofuscin. Components of anti-ageing and autophagy include SirTs and FoxOs. Nutritional deprivation or calorie restriction as ...

  15. Autophagy and bacterial infection: an evolving arms race.

    Science.gov (United States)

    Choy, Augustine; Roy, Craig R

    2013-09-01

    Autophagy is an important membrane transport pathway that is conserved among eukaryotic cells. Although first described as an intracellular catabolic pathway used to break down self-components, autophagy has been found to play an important role in the elimination of intracellular pathogens. A variety of host mechanisms exist for recognizing and targeting intracellular bacteria to autophagosomes. Several intracellular bacteria have evolved ways to manipulate, inhibit, or avoid autophagy in order to survive in the cell. Thus, the autophagy pathway can be viewed as an evolutionarily conserved host response to infection.

  16. DNA damage response and Autophagy: a meaningful partnership

    Directory of Open Access Journals (Sweden)

    ARISTIDES G ELIOPOULOS

    2016-11-01

    Full Text Available Autophagy and the DNA damage response (DDR are biological processes essential for cellular and organismal homeostasis. Herein we summarize and discuss emerging evidence linking DDR to autophagy. We highlight published data suggesting that autophagy is activated by DNA damage and is required for several functional outcomes of DDR signaling, including repair of DNA lesions, senescence, cell death, and cytokine secretion. Uncovering the mechanisms by which autophagy and DDR are intertwined provides novel insight into the pathobiology of conditions associated with accumulation of DNA damage, including cancer and aging, and novel concepts for the development of improved therapeutic strategies against these pathologies.

  17. Autophagy is required for IL-2-mediated fibroblast growth

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Rui [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 (United States); Tang, Daolin, E-mail: tangd2@upmc.edu [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 (United States); Lotze, Michael T., E-mail: lotzemt@upcm.edu [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 (United States); Zeh III, Herbert J., E-mail: zehh@upmc.edu [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15219 (United States)

    2013-02-15

    Autophagy is an evolutionarily conserved pathway responsible for delivery of cytoplasmic material into the lysosomal degradation pathway to enable vesicular exocytosis. Interleukin (IL)-2 is produced by T-cells and its activity is important for immunoregulation. Fibroblasts are an immune competent cell type, playing a critical role in wound healing, chronic inflammation, and tumor development. Although autophagy plays an important role in each of these processes, whether it regulates IL-2 activity in fibroblasts is unknown. Here, we show that autophagy is required for IL-2-induced cell growth in fibroblasts. IL-2 significantly induced autophagy in mouse embryonic fibroblasts (MEFs) and primary lung fibroblasts. Autophagy inhibitors (e.g., 3-methylamphetamine and bafilomycin A1) or knockdown of ATG5 and beclin 1 blocked clinical grade IL-2-induced autophagy. Moreover, IL-2 induced HMGB1 cytoplasmic translocation in MEFs and promoted interaction between HMGB1 and beclin1, which is required for autophagy induction. Pharmacological and genetic inhibition of autophagy inhibited IL-2-induced cell proliferation and enhanced IL-2-induced apoptosis. These findings suggest that autophagy is an important pro-survival regulator for IL-2-induced cell growth in fibroblasts.

  18. Autophagy and the Cell Cycle: A Complex Landscape

    Science.gov (United States)

    Mathiassen, Søs Grønbæk; De Zio, Daniela; Cecconi, Francesco

    2017-01-01

    Autophagy is a self-degradation pathway, in which cytoplasmic material is sequestered in double-membrane vesicles and delivered to the lysosome for degradation. Under basal conditions, autophagy plays a homeostatic function. However, in response to various stresses, the pathway can be further induced to mediate cytoprotection. Defective autophagy has been linked to a number of human pathologies, including neoplastic transformation, even though autophagy can also sustain the growth of tumor cells in certain contexts. In recent years, a considerable correlation has emerged between autophagy induction and stress-related cell-cycle responses, as well as unexpected roles for autophagy factors and selective autophagic degradation in the process of cell division. These advances have obvious implications for our understanding of the intricate relationship between autophagy and cancer. In this review, we will discuss our current knowledge of the reciprocal regulation connecting the autophagy pathway and cell-cycle progression. Furthermore, key findings involving nonautophagic functions for autophagy-related factors in cell-cycle regulation will be addressed.

  19. Application and interpretation of current autophagy inhibitors and activators

    Institute of Scientific and Technical Information of China (English)

    Ya-ping YANG; Li-fang HU; Hui-fen ZHENG; Cheng-jie MAO; Wei-dong HU; Kang-ping XIONG; Fen WANG

    2013-01-01

    Aut ophagy is the major intracellular degradation system,by which cytoplasmic materials are delivered to and degraded in the lysosome.As a quality control mechanism for cytoplasmic proteins and organelles,autophagy plays important roles in a variety of human diseases,including neurodegenerative diseases,cancer,cardiovascular disease,diabetes and infectious and inflammatory diseases.The discovery of ATG genes and the dissection of the signaling pathways involved in regulating autophagy have greatly enriched our knowledge on the occurrence and development of this lysosomal degradation pathway.In addition to its role in degradation,autophagy may also promote a type of programmed cell death that is different from apoptosis,termed type II programmed cell death.Owing to the dual roles of autophagy in cell death and the specificity of diseases,the exact mechanisms of autophagy in various diseases require more investigation.The application of autophagy inhibitors and activators will help us understand the regulation of autophagy in human diseases,and provide insight into the use of autophagy-targeted drugs.In this review,we summarize the latest research on autophagy inhibitors and activators and discuss the possibility of their application in human disease therapy.

  20. Abnormalities of gonadal differentiation.

    Science.gov (United States)

    Berkovitz, G D; Seeherunvong, T

    1998-04-01

    Gonadal differentiation involves a complex interplay of developmental pathways. The sex determining region Y (SRY) gene plays a key role in testis determination, but its interaction with other genes is less well understood. Abnormalities of gonadal differentiation result in a range of clinical problems. 46,XY complete gonadal dysgenesis is defined by an absence of testis determination. Subjects have female external genitalia and come to clinical attention because of delayed puberty. Individuals with 46,XY partial gonadal dysgenesis usually present in the newborn period for the valuation of ambiguous genitalia. Gonadal histology always shows an abnormality of seminiferous tubule formation. A diagnosis of 46,XY true hermaphroditism is made if the gonads contain well-formed testicular and ovarian elements. Despite the pivotal role of the SRY gene in testis development, mutations of SRY are unusual in subjects with a 46,XY karyotype and abnormal gonadal development. 46,XX maleness is defined by testis determination in an individual with a 46,XX karyotype. Most affected individuals have a phenotype similar to that of Klinefelter syndrome. In contrast, subjects with 46,XX true hermaphroditism usually present with ambiguous genitalia. The majority of subjects with 46,XX maleness have Y sequences including SRY in genomic DNA. However, only rare subjects with 46,XX true hermaphroditism have translocated sequences encoding SRY. Mosaicism and chimaerism involving the Y chromosome can also be associated with abnormal gonadal development. However, the vast majority of subjects with 45,X/46,XY mosaicism have normal testes and normal male external genitalia.

  1. Cortical Abnormalities in ADHD

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2003-12-01

    Full Text Available Grey-matter abnormalities at the cortical surface and regional brain size were mapped by high-resolution MRI and surface-based, computational image analytical techniques in a group of 27 children and adolescents with attention deficit hyperactivity disorder (ADHD and 46 controls, matched by age and sex, at the University of California at Los Angeles.

  2. Neurological abnormalities predict disability

    DEFF Research Database (Denmark)

    Poggesi, Anna; Gouw, Alida; van der Flier, Wiesje

    2014-01-01

    To investigate the role of neurological abnormalities and magnetic resonance imaging (MRI) lesions in predicting global functional decline in a cohort of initially independent-living elderly subjects. The Leukoaraiosis And DISability (LADIS) Study, involving 11 European centres, was primarily aimed...

  3. Lacrimal system abnormalities.

    Science.gov (United States)

    Moore, B D

    1994-03-01

    This report outlines several of the more important abnormalities of the lacrimal system in infants and young children. Although rare, alacrima can be a very difficult clinical problem to treat. The most common cause of alacrima is the Riley-Day syndrome. Nasolacrimal duct obstruction is a very common anomaly in children. The clinical appearance and treatment of this disorder are discussed.

  4. The regulation of DNA damage tolerance by Ubiquitin and Ubiquitin-like modifiers

    Directory of Open Access Journals (Sweden)

    Lina Cipolla

    2016-06-01

    Full Text Available DNA replication is an extremely complex process that needs to be executed in a highly accurate manner in order to propagate the genome. This task requires the coordination of a number of enzymatic activities and it is incredibly fragile and prone to arrest after DNA damage. DNA damage tolerance provides a last line of defense that allows completion of DNA replication in presence of an unrepaired template. One of such mechanisms is called Post Replication Repair (PRR and it is used by the cells to bypass highly distorted templates caused by damaged bases. PRR is extremely important for the cellular life and performs the bypass of the damage both in an error free and in an error prone manner. In light of these two possible outcomes, PRR needs to be tightly regulated and controlled in order to prevent accumulation of mutations leading ultimately to genome instability. Post-translational modifications provide the framework for this regulation and Ubiquitylation and SUMOylation of PRR proteins play a pivotal role in choosing which pathway to activate, controlling the different outcomes of damage bypass. PCNA (Proliferating Cell Nuclear Antigen, the DNA clamp for replicative polymerases, plays a central role in the regulation of damage tolerance and its modification by Ubiquitin and SUMO controls both the error free and error prone branches of PRR. Furthermore, a significant number of polymerases involved in the bypass of DNA damage possess domains that can bind post-translational modifications and they are themselves target for ubiquitylation. In this review, we will focus on how Ubiquitin and Ubiquitin-like modifications can regulate the DNA damage tolerance systems and how they are capable of controlling the recruitment of different proteins to the replication fork.

  5. Regulation of amino acid transporter trafficking by mTORC1 in primary human trophoblast cells is mediated by the ubiquitin ligase Nedd4-2.

    Science.gov (United States)

    Rosario, Fredrick J; Dimasuay, Kris Genelyn; Kanai, Yoshikatsu; Powell, Theresa L; Jansson, Thomas

    2016-04-01

    Changes in placental amino acid transfer directly contribute to altered fetal growth, which increases the risk for perinatal complications and predisposes for the development of obesity, diabetes and cardiovascular disease later in life. Placental amino acid transfer is critically dependent on the expression of specific transporters in the plasma membrane of the trophoblast, the transporting epithelium of the human placenta. However, the molecular mechanisms regulating this process are largely unknown. Nedd4-2 is an ubiquitin ligase that catalyses the ubiquitination of proteins, resulting in proteasomal degradation. We hypothesized that inhibition of mechanistic target of rapamycin complex 1 (mTORC1) decreases amino acid uptake in primary human trophoblast (PHT) cells by activation of Nedd4-2, which increases transporter ubiquitination resulting in decreased transporter expression in the plasma membrane. mTORC 1 inhibition increased the expression of Nedd4-2, promoted ubiquitination and decreased the plasma membrane expression of SNAT2 (an isoform of the System A amino acid transporter) and LAT1 (a System L amino acid transporter isoform), resulting in decreased cellular amino acid uptake. Nedd4-2 silencing markedly increased the trafficking of SNAT2 and LAT1 to the plasma membrane, which stimulated cellular amino acid uptake. mTORC1 inhibition by silencing of raptor failed to decrease amino acid transport following Nedd4-2 silencing. In conclusion, we have identified a novel link between mTORC1 signalling and ubiquitination, a common posttranslational modification. Because placental mTORC1 is inhibited in fetal growth restriction and activated in fetal overgrowth, we propose that regulation of placental amino acid transporter ubiquitination by mTORC1 and Nedd4-2 constitutes a molecular mechanisms underlying abnormal fetal growth.

  6. Autophagy Regulatory Network - a systems-level bioinformatics resource for studying the mechanism and regulation of autophagy.

    Science.gov (United States)

    Türei, Dénes; Földvári-Nagy, László; Fazekas, Dávid; Módos, Dezső; Kubisch, János; Kadlecsik, Tamás; Demeter, Amanda; Lenti, Katalin; Csermely, Péter; Vellai, Tibor; Korcsmáros, Tamás

    2015-01-01

    Autophagy is a complex cellular process having multiple roles, depending on tissue, physiological, or pathological conditions. Major post-translational regulators of autophagy are well known, however, they have not yet been collected comprehensively. The precise and context-dependent regulation of autophagy necessitates additional regulators, including transcriptional and post-transcriptional components that are listed in various datasets. Prompted by the lack of systems-level autophagy-related information, we manually collected the literature and integrated external resources to gain a high coverage autophagy database. We developed an online resource, Autophagy Regulatory Network (ARN; http://autophagy-regulation.org), to provide an integrated and systems-level database for autophagy research. ARN contains manually curated, imported, and predicted interactions of autophagy components (1,485 proteins with 4,013 interactions) in humans. We listed 413 transcription factors and 386 miRNAs that could regulate autophagy components or their protein regulators. We also connected the above-mentioned autophagy components and regulators with signaling pathways from the SignaLink 2 resource. The user-friendly website of ARN allows researchers without computational background to search, browse, and download the database. The database can be downloaded in SQL, CSV, BioPAX, SBML, PSI-MI, and in a Cytoscape CYS file formats. ARN has the potential to facilitate the experimental validation of novel autophagy components and regulators. In addition, ARN helps the investigation of transcription factors, miRNAs and signaling pathways implicated in the control of the autophagic pathway. The list of such known and predicted regulators could be important in pharmacological attempts against cancer and neurodegenerative diseases.

  7. Therapeutic effects of remediating autophagy failure in a mouse model of Alzheimer disease by enhancing lysosomal proteolysis.

    Science.gov (United States)

    Yang, Dun-Sheng; Stavrides, Philip; Mohan, Panaiyur S; Kaushik, Susmita; Kumar, Asok; Ohno, Masuo; Schmidt, Stephen D; Wesson, Daniel W; Bandyopadhyay, Urmi; Jiang, Ying; Pawlik, Monika; Peterhoff, Corrinne M; Yang, Austin J; Wilson, Donald A; St George-Hyslop, Peter; Westaway, David; Mathews, Paul M; Levy, Efrat; Cuervo, Ana M; Nixon, Ralph A

    2011-07-01

    The extensive autophagic-lysosomal pathology in Alzheimer disease (AD) brain has revealed a major defect: in the proteolytic clearance of autophagy substrates. Autophagy failure contributes on several levels to AD pathogenesis and has become an important therapeutic target for AD and other neurodegenerative diseases. We recently observed broad therapeutic effects of stimulating autophagic-lysosomal proteolysis in the TgCRND8 mouse model of AD that exhibits defective proteolytic clearance of autophagic substrates, robust intralysosomal amyloid-β peptide (Aβ) accumulation, extracellular β-amyloid deposition and cognitive deficits. By genetically deleting the lysosomal cysteine protease inhibitor, cystatin B (CstB), to selectively restore depressed cathepsin activities, we substantially cleared Aβ, ubiquitinated proteins and other autophagic substrates from autolysosomes/lysosomes and rescued autophagic-lysosomal pathology, as well as reduced total Aβ40/42 levels and extracellular amyloid deposition, highlighting the underappreciated importance of the lysosomal system for Aβ clearance. Most importantly, lysosomal remediation prevented the marked learning and memory deficits in TgCRND8 mice. Our findings underscore the pathogenic significance of autophagic-lysosomal dysfunction in AD and demonstrate the value of reversing this dysfunction as an innovative therapeautic strategy for AD.

  8. Inclusion body myopathy, Paget's disease of the bone and fronto-temporal dementia: a disorder of autophagy.

    Science.gov (United States)

    Ju, Jeong-Sun; Weihl, Conrad C

    2010-04-15

    Inclusion body myopathy associated with Paget's disease of the bone and fronto-temporal dementia (IBMPFD) is a progressive autosomal dominant disorder caused by mutations in p97/VCP (valosin-containing protein). p97/VCP is a member of the AAA+ (ATPase associated with a variety of activities) protein family and participates in multiple cellular processes. One particularly important role for p97/VCP is facilitating intracellular protein degradation. p97/VCP has traditionally been thought to mediate the ubiquitin-proteasome degradation of proteins; however, recent studies challenge this dogma. p97/VCP clearly participates in the degradation of aggregate-prone proteins, a process principally mediated by autophagy. In addition, IBMPFD mutations in p97/VCP lead to accumulation of autophagic structures in patient and transgenic animal tissue. This is likely due to a defect in p97/VCP-mediated autophagosome maturation. The following review will discuss the evidence for p97/VCP in autophagy and how a disruption in this process contributes to IBMPFD pathogenesis.

  9. Significant role of PB1 and UBA domains in multimerization of Joka2, a selective autophagy cargo receptor from tobacco

    Directory of Open Access Journals (Sweden)

    Katarzyna eZientara-Rytter

    2014-01-01

    Full Text Available Tobacco Joka2 protein is a hybrid homolog of two mammalian selective autophagy cargo receptors, p62 and NBR1. These proteins can directly interact with the members of ATG8 family and the polyubiquitinated cargoes designed for degradation. Function of the selective autophagy cargo receptors relies on their ability to form protein aggregates. It has been shown that the N-terminal PB1 domain of p62 is involved in formation of aggregates, while the UBA domains of p62 and NBR1 have been associated mainly with cargo binding. Here we focus on roles of PB1 and UBA domains in localization and aggregation of Joka2 in plant cells. We show that Joka2 can homodimerize not only through its N-terminal PB1-PB1 interactions but also via interaction between N-terminal PB1 and C-terminal UBA domains. We also demonstrate that Joka2 co-localizes with recombinant ubiquitin and sequestrates it into aggregates and that C-terminal part (containing UBA domains is sufficient for this effect. Our results indicate that Joka2 accumulates in cytoplasmic aggregates and suggest that in addition to these multimeric forms it also exists in the nucleus and cytoplasm in a monomeric form.

  10. Characterization of the Arabidopsis thaliana E3 ubiquitin-ligase AtSINAL7 and identification of the ubiquitination sites.

    Directory of Open Access Journals (Sweden)

    Diego A Peralta

    Full Text Available Protein ubiquitination leading to degradation by the proteasome is an important mechanism in regulating key cellular functions. Protein ubiquitination is carried out by a three step process involving ubiquitin (Ub activation by a E1 enzyme, the transfer of Ub to a protein E2, finally an ubiquitin ligase E3 catalyzes the transfer of the Ub peptide to an acceptor protein. The E3 component is responsible for the specific recognition of the target, making the unveiling of E3 components essential to understand the mechanisms regulating fundamental cell processes through the protein degradation pathways. The Arabidopsis thaliana seven in absentia-like 7 (AtSINAL7 gene encodes for a protein with characteristics from a C3HC4-type E3 ubiquitin ligase. We demonstrate here that AtSINAL7 protein is indeed an E3 protein ligase based on the self-ubiquitination in vitro assay. This activity is dependent of the presence of a Lys residue in position 124. We also found that higher AtSINAL7 transcript levels are present in tissues undergoing active cell division during floral development. An interesting observation is the circadian expression pattern of AtSINAL7 mRNA in floral buds. Furthermore, UV-B irradiation induces the expression of this transcript indicating that AtSINAL7 may be involved in a wide range of different cell processes.

  11. MicroRNA regulation of Autophagy

    DEFF Research Database (Denmark)

    Frankel, Lisa B; Lund, Anders H

    2012-01-01

    recently contributed to our understanding of the molecular mechanisms of the autophagy machinery, yet several gaps remain in our knowledge of this process. The discovery of microRNAs (miRNAs) established a new paradigm of post-transcriptional gene regulation and during the past decade these small non......-coding RNAs have been closely linked to virtually all known fundamental biological pathways. Deregulation of miRNAs can contribute to the development of human diseases, including cancer, where they can function as bona fide oncogenes or tumor suppressors.In this review, we highlight recent advances linking miRNAs...... perspective, but also from a therapeutic view, where miRNAs can be harnessed experimentally to alter autophagy levels in human tumors, affecting parameters such as tumor survival and treatment sensitivity....

  12. Autophagy and Cancer Treatment%细胞自噬与肿瘤发生

    Institute of Scientific and Technical Information of China (English)

    相建峰; 林盛明; 相燕洁; 张闽光

    2012-01-01

    Autophagy is widely exist in eukaryotic cells, the phenomenon of life, is an important body defense and protection mechanisms. Cells can through the autophagy and the lysosome, eliminate,degradation,digestivedamage,degeneration,aging and lose function of cells,organelles,denatured protein and nucleic acid and biological macromolecules,for the reconstruction of the cells, regeneration and repair provide the necessary raw materials, achieve cell recycling and reuse. Autophagy abnormalities and tumors development is closely related to the tumor process involving multiple levels of influence,including oncogenes,cell cycle, angiogenesis and lysosome changes,etc. Therefore,through the study of effects of autophagy,not only to further reveals tumor occurrence and development of potential mechanism, but also may provide cancer prevention and treatment of new ideas.%细胞自噬(autophagy)是广泛存在于真核细胞中的生命现象,是机体一种重要的防御和保护机制.细胞可以通过自噬和溶酶体,消除、降解、消化受损、变性、衰老和失去功能的细胞、细胞器、变性蛋白质与核酸等生物大分子,为细胞的重建、再生和修复提供必须原料,实现细胞的再循环和再利用.自噬异常与肿瘤的发生、发展密切相关,涉及影响肿瘤进程的多个层面,包括肿瘤基因,细胞周期,血管生成及溶酶体变化等.因此,通过对自噬作用的研究,既进一步揭示肿瘤发生、发展的潜在机制,也可能为肿瘤的预防和治疗提供新的思路.

  13. Associations of autophagy with lung diffusion capacity and oxygen saturation in severe COPD: effects of particulate air pollution.

    Science.gov (United States)

    Lee, Kang-Yun; Chiang, Ling-Ling; Ho, Shu-Chuan; Liu, Wen-Te; Chen, Tzu-Tao; Feng, Po-Hao; Su, Chien-Ling; Chuang, Kai-Jen; Chang, Chih-Cheng; Chuang, Hsiao-Chi

    2016-01-01

    Although traffic exposure has been associated with the development of COPD, the role of particulate matter diffusion capacity of the lung for carbon monoxide levels (r=-0.914, P=0.029), changes in the pulse oxygen saturation (ΔSaO2; r=-0.973, P=0.005), receptor for advanced glycation end-products (r=-0.881, P=0.048), interleukin-6 (r=0.986, P=0.002), ubiquitin (r=0.940, P=0.017), and beclin 1 (r=0.923, P=0.025) in COPD. Next, we observed that ubiquitin was correlated with ΔSaO2 (r=-0.374, P=0.019). Beclin 1 was associated with diffusion capacity of the lung for carbon monoxide (r=-0.362, P=0.028), ΔSaO2 (r=-0.354, P=0.032), and receptor for advanced glycation end-products (r=-0.471, P=0.004). Autophagy may be an important regulator of the PM10-related pathogenesis of COPD, which could cause deterioration in the lung diffusion capacity and oxygen saturation.

  14. Autophagy and the (Pro)renin Receptor.

    Science.gov (United States)

    Binger, Katrina J; Muller, Dominik N

    2013-10-21

    The (pro)renin receptor (PRR) is a newly reported member of the renin-angiotensin system (RAS); a hormonal cascade responsible for regulating blood pressure. Originally, identification of PRR was heralded as the next drug target of the RAS, of which such therapies would have increased benefits against target-organ damage and hypertension. However, in the years since its discovery, several conditional knockout mouse models of PRR have demonstrated an essential role for this receptor unrelated to the RAS and blood pressure. Specific deletion of PRR in podocytes or cardiomyocytes resulted in the rapid onset of organ failure and subsequently animal mortality after only a matter of weeks. In both cell types, loss of PRR resulted in the intracellular accumulation of autophagosomes and misfolded proteins, indicating a disturbance in autophagy. In light of the fact that the majority of PRR is located intracellularly, this molecular function appears to be more relevant than its ability to bind to high, non-physiological concentrations of (pro)renin. This review will focus on the role of PRR in autophagy and its importance in maintaining cellular homeostasis. Understanding the link between PRR, autophagy and how its loss results in cell death will be essential for deciphering its role in physiology and pathology.

  15. Autophagy and ethanol-induced liver injury

    Institute of Scientific and Technical Information of China (English)

    Terrence M Donohue Jr

    2009-01-01

    The majority of ethanol metabolism occurs in the liver. Consequently, this organ sustains the greatest damage from ethanol abuse. Ethanol consumption disturbs the delicate balance of protein homeostasis in the liver, causing intracellular protein accumulation due to a disruption of hepatic protein catabolism.Evidence indicates that ethanol or its metabolism impairs trafficking events in the liver, including the process of macroautophagy, which is the engulfment and degradation of cytoplasmic constituents by the lysosomal system. Autophagy is an essential, ongoing cellular process that is highly regulated by nutrients,endocrine factors and signaling pathways. A great number of the genes and gene products that govern the autophagic response have been characterized and the major metabolic and signaling pathways that activate or suppress autophagy have been identified. This review describes the process of autophagy, its regulation and the possible mechanisms by which ethanol disrupts the process of autophagic degradation. The implications of autophagic suppression are discussed in relation to the pathogenesis of alcohol-induced liver injury.

  16. Regulation of autophagy by nucleoporin Tpr.

    Science.gov (United States)

    Funasaka, Tatsuyoshi; Tsuka, Eriko; Wong, Richard W

    2012-01-01

    The nuclear pore complex (NPC) consists of a conserved set of ~30 different proteins, termed nucleoporins, and serves as a gateway for the exchange of materials between the cytoplasm and nucleus. Tpr (translocated promoter region) is a component of NPC that presumably localizes at intranuclear filaments. Here, we show that Tpr knockdown caused a severe reduction in the number of nuclear pores. Furthermore, our electron microscopy studies indicated a significant reduction in the number of inner nuclear filaments. In addition, Tpr siRNA treatment impaired cell growth and proliferation compared to control siRNA-treated cells. In Tpr-depleted cells, the levels of p53 and p21 proteins were enhanced. Surprisingly, Tpr depletion increased p53 nuclear accumulation and facilitated autophagy. Our study demonstrates for the first time that Tpr plays a role in autophagy through controlling HSP70 and HSF1 mRNA export, p53 trafficking with karyopherin CRM1, and potentially through direct transcriptional regulation of autophagy factors.

  17. Nitrofurantoin and congenital abnormalities

    DEFF Research Database (Denmark)

    Czeizel, A.E.; Rockenbauer, M.; Sørensen, Henrik Toft;

    2001-01-01

    Objective: To study human teratogenic potential of oral nitrofurantoin treatment during pregnancy. Materials and Methods: Pair analysis of cases with congenital abnormalities and matched population controls in the population-based dataset of the Hungarian Case-Control Surveillance of Congenital...... or fetuses with Down’s syndrome (patient controls), 23 (2.8%) pregnant women were treated with nitrofurantoin. The above differences between population controls and cases may be connected with recall bias, because the case-control pair analysis did not indicate a teratogenic potential of nitrofurantoin use...... during the second and the third months of gestation, i.e. in the critical period for major congenital abnormalities. Conclusion: Treatment with nitrofurantoin during pregnancy does not present detectable teratogenic risk to the fetus....

  18. Autophagy-associated atrophy and metabolic remodeling of the mouse diaphragm after short-term intermittent hypoxia.

    Directory of Open Access Journals (Sweden)

    Christian Giordano

    Full Text Available Short-term intermittent hypoxia (IH is common in patients with acute respiratory disorders. Although prolonged exposure to hypoxia induces atrophy and increased fatigability of skeletal muscle, the response to short-term IH is less well known. We hypothesized that the diaphragm and limb muscles would adapt differently to short-term IH given that hypoxia stimulates ventilation and triggers a superimposed exercise stimulus in the diaphragm.We determined the structural, metabolic, and contractile properties of the mouse diaphragm after 4 days of IH (8 hours per day, 30 episodes per hour to a FiO2 nadir=6%, and compared responses in the diaphragm to a commonly studied reference limb muscle, the tibialis anterior. Outcome measures included muscle fiber size, assays of muscle proteolysis (calpain, ubiquitin-proteasome, and autophagy pathways, markers of oxidative stress and mitochondrial function, quantification of intramyocellular lipid and lipid metabolism genes, type I myosin heavy chain (MyHC expression, and in vitro contractile properties.After 4 days of IH, the diaphragm alone demonstrated significant atrophy (30% decrease of myofiber size together with increased LC3B-II protein (2.4-fold and mRNA markers of the autophagy pathway (LC3B, Gabarapl1, Bnip3, whereas active calpain and E3 ubiquitin ligases (MuRF1, atrogin-1 were unaffected in both muscles. Succinate dehydrogenase activity was significantly reduced by IH in both muscles. However, only the diaphragm exhibited increased intramyocellular lipid droplets (2.5-fold after IH, along with upregulation of genes linked to activated lipid metabolism. In addition, although the diaphragm showed evidence for acute fatigue immediately following IH, it underwent an adaptive fiber type switch toward slow type I MyHC-expressing fibers, associated with greater intrinsic endurance of the muscle during repetitive stimulation in vitro.Short-term IH induces preferential atrophy in the mouse diaphragm

  19. Autophagy in the human placenta throughout gestation.

    Directory of Open Access Journals (Sweden)

    Tai-Ho Hung

    Full Text Available BACKGROUND: Autophagy has been reported to be essential for pre-implantation development and embryo survival. However, its role in placental development and regulation of autophagy during pregnancy remain unclear. The aims of this study were to (1 study autophagy by characterizing changes in levels of beclin-1, DRAM, and LC3B in human placenta throughout gestation; (2 determine whether autophagy is involved in regulation of trophoblast invasion in JEG-3 cells (a choriocarcinoma cell line; (3 examine the effects of reduced oxygen and glucose on the autophagic changes; and (4 investigate the effect of reoxygenation and supplementation of glucose after oxygen-glucose deprivation (OGD on the autophagic changes in primary cytotrophoblasts obtained from normal term pregnancy. METHODOLOGY/PRINCIPAL FINDINGS: An analysis of 40 placental samples representing different gestational stages showed (1 no significant differences in beclin-1, DRAM, and LC3B-II levels in placentas between early and mid-gestation, and late gestation with vaginal delivery; (2 placentas from late gestation with cesarean section had lower levels of LC3B-II compared to early and mid-gestation, and late gestation with vaginal delivery; levels of DRAM were also lower compared to placentas from early and mid-gestation; and (3 using explant cultures, villous tissues from early and late gestation had similar rates of autophagic flux under physiological oxygen concentrations. Knockdown of BECN1, DRAM, and LC3B had no effects on viability and invasion activity of JEG-3 cells. On the other hand, OGD caused a significant increase in the levels of LC3B-II in primary cytotrophoblasts, while re-supplementation of oxygen and glucose reduced these changes. Furthermore, there were differential changes in levels of beclin-1, DRAM, and LC3B-II in response to changes in oxygen and glucose levels. CONCLUSIONS/SIGNIFICANCE: Our results indicate that autophagy is involved in development of the human

  20. [Molecular abnormalities in lymphomas].

    Science.gov (United States)

    Delsol, G

    2010-11-01

    Numerous molecular abnormalities have been described in lymphomas. They are of diagnostic and prognostic value and are taken into account for the WHO classification of these tumors. They also shed some light on the underlying molecular mechanisms involved in lymphomas. Overall, four types of molecular abnormalities are involved: mutations, translocations, amplifications and deletions of tumor suppressor genes. Several techniques are available to detect these molecular anomalies: conventional cytogenetic analysis, multicolor FISH, CGH array or gene expression profiling using DNA microarrays. In some lymphomas, genetic abnormalities are responsible for the expression of an abnormal protein (e.g. tyrosine-kinase, transcription factor) detectable by immunohistochemistry. In the present review, molecular abnormalities observed in the most frequent B, T or NK cell lymphomas are discussed. In the broad spectrum of diffuse large B-cell lymphomas microarray analysis shows mostly two subgroups of tumors, one with gene expression signature corresponding to germinal center B-cell-like (GCB: CD10+, BCL6 [B-Cell Lymphoma 6]+, centerine+, MUM1-) and a subgroup expressing an activated B-cell-like signature (ABC: CD10-, BCL6-, centerine-, MUM1+). Among other B-cell lymphomas with well characterized molecular abnormalies are follicular lymphoma (BCL2 deregulation), MALT lymphoma (Mucosa Associated Lymphoid Tissue) [API2-MALT1 (mucosa-associated-lymphoid-tissue-lymphoma-translocation-gene1) fusion protein or deregulation BCL10, MALT1, FOXP1. MALT1 transcription factors], mantle cell lymphoma (cycline D1 [CCND1] overexpression) and Burkitt lymphoma (c-Myc expression). Except for ALK (anaplastic lymphoma kinase)-positive anaplastic large cell lymphoma, well characterized molecular anomalies are rare in lymphomas developed from T or NK cells. Peripheral T cell lymphomas not otherwise specified are a heterogeneous group of tumors with frequent but not recurrent molecular abnormalities

  1. Autophagy: A double-edged sword in Alzheimer's disease

    Indian Academy of Sciences (India)

    Ying-Tsen Tung; Bo-Jeng Wang; Ming-Kuan Hu; Wen-Ming Hsu; Hsinyu Lee; Wei-Pang Huang; Yung-Feng Liao

    2012-03-01

    Autophagy is a major protein degradation pathway that is essential for stress-induced and constitutive protein turnover. Accumulated evidence has demonstrated that amyloid- (A) protein can be generated in autophagic vacuoles, promoting its extracellular deposition in neuritic plaques as the pathological hallmark of Alzheimer’s disease (AD). The molecular machinery for A generation, including APP, APP-C99 and -/-secretases, are all enriched in autophagic vacuoles. The induction of autophagy can be vividly observed in the brain at early stages of sporadic AD and in an AD transgenic mouse model. Accumulated evidence has also demonstrated a neuroprotective role of autophagy in mediating the degradation of aggregated proteins that are causative of various neurodegenerative diseases. Autophagy is thus widely regarded as an intracellular hub for the removal of the detrimental A peptides and Tau aggregates. Nonetheless, compelling data also reveal an unfavorable function of autophagy in facilitating the production of intracellular A. The two faces of autophagy on the homeostasis of A place it in a very unique and intriguing position in ADpathogenesis. This article briefly summarizes seminal discoveries that are shedding new light on the critical and unique roles of autophagy in AD and potential therapeutic approaches against autophagy-elicited AD.

  2. Role of autophagy in the pathogenesis of multiple sclerosis.

    Science.gov (United States)

    Liang, Peizhou; Le, Weidong

    2015-08-01

    Autophagy plays an important role in maintaining the cellular homeostasis. One of its functions is to degrade unnecessary organelles and proteins for energy recycling or amino-acids for cell survival. Ablation of autophagy leads to neurodegeneration. Multiple sclerosis (MS), a permanent neurological impairment typical of chronic inflammatory demyelinating disorder, is an auto-immune disease of the central nervous system (CNS). Autophagy is tightly linked to the innate and adaptive immune systems during the autoimmune process, and several studies have shown that autophagy directly participates in the progress of MS or experimental autoimmune encephalomyelitis (EAE, a mouse model of MS). Dysfunction of mitochondria that intensively influences the autophagy pathway is one of the important factors in the pathogenesis of MS. Autophagy-related gene (ATG) 5 and immune-related GTPase M (IRGM) 1 are increased, while ATG16L2 is decreased, in T-cells in EAE and active relapsing-remitting MS brains. Administration of rapamycin, an inhibitor of mammalian target of rapamycin ( mTOR), ameliorates relapsing-remitting EAE. Inflammation and oxidative stress are increased in MS lesions and EAE, but Lamp2 and the LC3-II/LC3-I ratio are decreased. Furthermore, autophagy in various glial cells plays important roles in regulating neuro-inflammation in the CNS, implying potential roles in MS. In this review, we discuss the role of autophagy in the peripheral immune system and the CNS in neuroinflammation associated with the pathogenesis of MS.

  3. Autophagy in ageing and ageing-associated diseases

    Institute of Scientific and Technical Information of China (English)

    Li-qiang HE; Jia-hong LU; Zhen-yu YUE

    2013-01-01

    Autophagy is a cell self-digestion process via lysosomes that clears "cellular waste",including aberrantly modified proteins or protein aggregates and damaged organelles.Therefore,autophagy is considered a protein and organelle quality control mechanism that maintains normal cellular homeostasis.Dysfunctional autophagy has been observed in ageing tissues and several ageing-associated diseases.Lifespan of model organisms such as yeast,worms,flies,and mice can be extended through promoting autophagy,either by genetic manipulations such as over-expression of Sirtuin 1,or by administrations of rapamycin,resveratrol or spermidine.The evidence supports that autophagy may play an important role in delaying ageing or extending lifespan.In this review,we summarize the current knowledge about autophagy and its regulation,outline recent developments ie the genetic and pharmacological manipulations of autophagy that affects the lifespan,and discuss the role of autophagy in the ageing-related diseases.ow in Center for Neurodegenerative and Neuroimmunologic Diseases,Department of Neurology,University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School,Piscataway,NJ 08854,USA

  4. Exercise induces autophagy in peripheral tissues and in the brain.

    Science.gov (United States)

    He, Congcong; Sumpter, Rhea; Levine, Beth

    2012-10-01

    We recently identified physical exercise as a newly defined inducer of autophagy in vivo. Exercise induced autophagy in multiple organs involved in metabolic regulation, such as muscle, liver, pancreas and adipose tissue. To study the physiological role of exercise-induced autophagy, we generated mice with a knock-in nonphosphorylatable mutation in BCL2 (Thr69Ala, Ser70Ala and Ser84Ala) (BCL2 AAA) that are defective in exercise- and starvation-induced autophagy but not in basal autophagy. We found that BCL2 AAA mice could not run on a treadmill as long as wild-type mice, and did not undergo exercise-mediated increases in skeletal glucose muscle uptake. Unlike wild-type mice, the BCL2 AAA mice failed to reverse high-fat diet-induced glucose intolerance after 8 weeks of exercise training, possibly due to defects in signaling pathways that regulate muscle glucose uptake and metabolism during exercise. Together, these findings suggested a hitherto unknown important role of autophagy in mediating exercise-induced metabolic benefits. In the present addendum, we show that treadmill exercise also induces autophagy in the cerebral cortex of adult mice. This observation raises the intriguing question of whether autophagy may in part mediate the beneficial effects of exercise in neurodegeneration, adult neurogenesis and improved cognitive function.

  5. Autophagy: A Potential Link between Obesity and Insulin Resistance

    NARCIS (Netherlands)

    P. Codogno; A.J. Meijer

    2010-01-01

    Dysregulation of autophagy contributes to aging and to diseases such as neurodegeneration, cardiomyopathy, and cancer. The paper by Yang et al. (2010) in this issue of Cell Metabolism indicates that defective autophagy may also underlie impaired insulin sensitivity in obesity and that upregulating a

  6. Altered autophagy in human adipose tissues in obesity

    Science.gov (United States)

    Context: Autophagy is a housekeeping mechanism, involved in metabolic regulation and stress response, shown recently to regulate lipid droplets biogenesis/breakdown and adipose tissue phenotype. Objective: We hypothesized that in human obesity autophagy may be altered in adipose tissue in a fat d...

  7. Polymorphisms in autophagy genes and susceptibility to tuberculosis.

    NARCIS (Netherlands)

    Songane, M.; Kleinnijenhuis, J.; Alisjahbana, B.; Sahiratmadja, E.; Parwati, I.; Oosting, M.; Plantinga, T.S.; Joosten, L.A.B.; Netea, M.G.; Ottenhoff, T.H.; Vosse, E. van de; Crevel, R. van

    2012-01-01

    Recent data suggest that autophagy is important for intracellular killing of Mycobacterium tuberculosis, and polymorphisms in the autophagy gene IRGM have been linked with susceptibility to tuberculosis (TB) among African-Americans, and with TB caused by particular M. tuberculosis genotypes in Ghana

  8. Autophagy Is Associated with Pathogenesis of Haemophilus parasuis

    Science.gov (United States)

    Zhang, Yaning; Li, Yufeng; Yuan, Wentao; Xia, Yuting; Shen, Yijuan

    2016-01-01

    Haemophilus parasuis (H. parasuis) is a common commensal Gram-negative extracellular bacterium in the upper respiratory tract of swine, which can cause Glässer's disease in stress conditions. Research on the pathogenicity of H. parasuis has mainly focused on immune evasion and bacterial virulence factors, while few studies have examined the interactions of H. parasuis and its host. Autophagy is associated with the replication and proliferation of many pathogenic bacteria, but whether it plays a role during infection by H. parasuis is unknown. In this study, an adenovirus construct expressing GFP, RFP, and LC3 was used to infect H. parasuis. Western blotting, laser confocal microscopy, and electron microscopy showed that Hps5 infection induced obvious autophagy in PK-15 cells. In cells infected with strains of H. parasuis differing in invasiveness, the levels of autophagy were positively correlated with the presence of alive bacteria in PK-15 cells. In addition, autophagy inhibited the invasion of Hps5 in PK-15 cells. Autophagy related genes Beclin, Atg5 and Atg7 were silenced with RNA interference, the results showed that autophagy induced by H. parasuis infection is a classical pathway. Our observations demonstrate that H. parasuis can induce autophagy and that the levels of autophagy are associated with the presence of alive bacteria in cells, which opened novel avenues to further our understanding of H. parasuis-host interplay and pathogenesis. PMID:27703447

  9. Role of Autophagy in the Control of Body Metabolism

    Directory of Open Access Journals (Sweden)

    Wenying Quan

    2013-03-01

    Full Text Available Autophagy plays a crucial role in the maintenance of cellular nutrient balance and the function of organelles such as mitochondria or the endoplasmic reticulum, which are important in intracellular metabolism, insulin release, and insulin sensitivity. In the insulin-producing pancreatic β-cells, autophagy is important in the maintenance of β-cell mass, structure, and function. Mice with deficiencies in β-cell-specific autophagy show reduced β-cell mass and defects in insulin secretion that lead to hypoinsulinemia and hyperglycemia but not diabetes. However, these mice developed diabetes when bred with ob/ob mice, suggesting that autophagy-deficient β-cells have defects in dealing with the increased metabolic stress imposed by obesity. These results also imply that autophagy deficiency in β-cells could be a factor in the progression from obesity to diabetes. Another important function of autophagy is in hypothalamic neurons for the central control of energy expenditure, appetite, and body weight. In addition, mice with autophagy deficiencies in the target tissues of insulin have yielded diverse phenotypes. Taken together, these results suggest that autophagy is important in the control of whole body energy and nutrient homeostasis, and its dysregulation could play a role in the development of metabolic disorders and diabetes.

  10. Autophagy suppresses host adaptive immune responses toward Borrelia burgdorferi

    NARCIS (Netherlands)

    Buffen, Kathrin; Oosting, Marije; Li, Yang; Kanneganti, Thirumala-Devi; Netea, Mihai G.; Joosten, Leo A. B.

    2016-01-01

    Inhibition of autophagy increases the severity of murine Lyme arthritis and human adaptive immune responses against B. burgdorferi. We have previously demonstrated that inhibition of autophagy increased the Borrelia burgdorferi induced innate cytokine production in vitro, but little is known regardi

  11. Autophagy mediates pharmacological lifespan extension by spermidine and resveratrol.

    Science.gov (United States)

    Morselli, Eugenia; Galluzzi, Lorenzo; Kepp, Oliver; Criollo, Alfredo; Maiuri, Maria Chiara; Tavernarakis, Nektarios; Madeo, Frank; Kroemer, Guido

    2009-12-23

    Although autophagy has widely been conceived as a self-destructive mechanism that causes cell death, accumulating evidence suggests that autophagy usually mediates cytoprotection, thereby avoiding the apoptotic or necrotic demise of stressed cells. Recent evidence produced by our groups demonstrates that autophagy is also involved in pharmacological manipulations that increase longevity. Exogenous supply of the polyamine spermidine can prolong the lifespan of (while inducing autophagy in) yeast, nematodes and flies. Similarly, resveratrol can trigger autophagy in cells from different organisms, extend lifespan in nematodes, and ameliorate the fitness of human cells undergoing metabolic stress. These beneficial effects are lost when essential autophagy modulators are genetically or pharmacologically inactivated, indicating that autophagy is required for the cytoprotective and/or anti-aging effects of spermidine and resveratrol. Genetic and functional studies indicate that spermidine inhibits histone acetylases, while resveratrol activates the histone deacetylase Sirtuin 1 to confer cytoprotection/longevity. Although it remains elusive whether the same histones (or perhaps other nuclear or cytoplasmic proteins) act as the downstream targets of spermidine and resveratrol, these results point to an essential role of protein hypoacetylation in autophagy control and in the regulation of longevity.

  12. Anti- and pro-tumor functions of autophagy.

    Science.gov (United States)

    Morselli, Eugenia; Galluzzi, Lorenzo; Kepp, Oliver; Vicencio, José-Miguel; Criollo, Alfredo; Maiuri, Maria Chiara; Kroemer, Guido

    2009-09-01

    Autophagy constitutes one of the major responses to stress in eukaryotic cells, and is regulated by a complex network of signaling cascades. Not surprisingly, autophagy is implicated in multiple pathological processes, including infection by pathogens, inflammatory bowel disease, neurodegeneration and cancer. Both oncogenesis and tumor survival are influenced by perturbations of the molecular machinery that controls autophagy. Numerous oncoproteins, including phosphatidylinositol 3-kinase, Akt1 and anti-apoptotic members of the Bcl-2 family suppress autophagy. Conversely, several tumor suppressor proteins (e.g., Atg4c; beclin 1; Bif-1; BH3-only proteins; death-associated protein kinase 1; LKB1/STK11; PTEN; UVRAG) promote the autophagic pathway. This does not entirely apply to p53, one of the most important tumor suppressor proteins, which regulates autophagy in an ambiguous fashion, depending on its subcellular localization. Irrespective of the controversial role of p53, basal levels of autophagy appear to inhibit tumor development. On the contrary, chemotherapy- and metabolic stress-induced activation of the autophagic pathway reportedly contribute to the survival of formed tumors, thereby favoring resistance. In this context, autophagy inhibition would represent a major therapeutic target for chemosensitization. Here, we will review the current knowledge on the dual role of autophagy as an anti- and pro-tumor mechanism.

  13. DMPD: Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16982211 Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. Wullaer...vg) (.html) (.csml) Show Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. PubmedID 16982211 Title Ubiquitin: tool

  14. Regulation of Mitochondrial Genome Inheritance by Autophagy and Ubiquitin-Proteasome System: Implications for Health, Fitness, and Fertility

    OpenAIRE

    Won-Hee Song; John William Oman Ballard; Young-Joo Yi; Peter Sutovsky

    2014-01-01

    Mitochondria, the energy-generating organelles, play a role in numerous cellular functions including adenosine triphosphate (ATP) production, cellular homeostasis, and apoptosis. Maternal inheritance of mitochondria and mitochondrial DNA (mtDNA) is universally observed in humans and most animals. In general, high levels of mitochondrial heteroplasmy might contribute to a detrimental effect on fitness and disease resistance. Therefore, a disposal of the sperm-derived mitochondria inside fertil...

  15. 自噬蛋白NDP52与细菌感染的研究进展%Research Advances in Autophagy Protein NDP52 and Bacterial Infection

    Institute of Scientific and Technical Information of China (English)

    王芬芬; 张吉翔

    2012-01-01

    自噬(autophagy)是哺乳动物清除入侵细菌的主要途径,可保卫宿主细胞免受细菌的损伤.核点蛋白52(nuclear dot protein 52,NDP52)——核点家族成员之一,是除p62/SQSTM1和NBR1 等之外最新发现的自噬关键蛋白.它连接自噬体表面的微管相关蛋白1轻链3(microtubule associated protein l light chain 3,LC3),将披上“泛素大衣”的病原菌(如沙门氏菌和化脓性链球菌)递送至自噬体内加以清除.这一发现有助于人们深入了解自噬抵抗病原微生物感染的具体分子机制,为预防和治疗细菌感染提供了新靶点.%Autophagy is an important pathway to eliminate intracellular bacteria in mammals and defend the host cell from bacteria damage. In addition to p62/SQSTMl and NBR1, NDP52 (nuclear dot protein 52)—one of the members of nuclear dots, is a novel autophagy related protein has been found. NDP52 is an adaptor protein that binds to both ubiquitinated bacteria (such as Salmonella and Streptococcus pyogenes) and LC3 (microtubule associated protein 1 light chain 3), and then delivers these invaders into autophagosomes. This finding helps further understand the specific molecular mechanism of autophagy resisting pathogens infection, and provides a new target for the prevention and treatment of bacteria infection.

  16. FBW7-mediated ubiquitination and degradation of KLF5

    Institute of Scientific and Technical Information of China (English)

    Yi; Luan; Ping; Wang

    2014-01-01

    Krüppel-like factor(KLF) family proteins are transcription factors that regulate numerous cellular functions, such as cell proliferation, differentiation, and cell death. Posttranslational modification of KLF proteins is important for their transcriptional activities and biological functions. One KLF family member with important roles in cell proliferation and tumorigenesis is KLF5. The function of KLF5 is tightly controlled by post-translational modifications, including SUMOylation, phosphorylation, and ubiquitination. Recent studies from our lab and others’ have demonstrated that the tumor suppressor FBW7 is an essential E3 ubiquitin ligase that targets KLF5 for ubiquitination and degradation. KLF5 contains functional Cdc4 phospho-degrons(CPDs), which are required for its interaction with FBW7. Mutation of CPDs in KLF5 blocks the ubiquitination and degradation of KLF5 by FBW7. The protein kinase Glycogen synthase kinase 3β is involved in the phosphorylation of KLF5 CPDs. In both cancer cell lines and mousemodels, it has been shown that FBW7 regulates the expression of KLF5 target genes through the modulation of KLF5 stability. In this review, we summarize the current progress on delineating FBW7-mediated KLF5 ubiquitination and degradation.

  17. Class III PI3K-mediated prolonged activation of autophagy plays a critical role in the transition of cardiac hypertrophy to heart failure.

    Science.gov (United States)

    Yu, Peng; Zhang, Yangyang; Li, Chuanfu; Li, Yuehua; Jiang, Surong; Zhang, Xiaojin; Ding, Zhengnian; Tu, Fei; Wu, Jun; Gao, Xiang; Li, Liu

    2015-07-01

    Pathological cardiac hypertrophy often leads to heart failure. Activation of autophagy has been shown in pathological hypertrophic hearts. Autophagy is regulated positively by Class III phosphoinositide 3-kinase (PI3K). However, it is unknown whether Class III PI3K plays a role in the transition of cardiac hypertrophy to heart failure. To address this question, we employed a previously established cardiac hypertrophy model in heat shock protein 27 transgenic mice which shares common features with several types of human cardiomyopathy. Age-matched wild-type mice served as control. Firstly, a prolonged activation of autophagy, as reflected by autophagosome accumulation, increased LC3 conversion and decreased p62 protein levels, was detected in hypertrophic hearts from adaptive stage to maladaptive stage. Moreover, morphological abnormalities in myofilaments and mitochondria were presented in the areas accumulated with autophagosomes. Secondly, activation of Class III PI3K Vacuolar protein sorting 34 (Vps34), as demonstrated by upregulation of Vps34 expression, increased interaction of Vps34 with Beclin-1, and deceased Bcl-2 expression, was demonstrated in hypertrophic hearts from adaptive stage to maladaptive stage. Finally, administration with Wortmaninn, a widely used autophagy inhibitor by suppressing Class III PI3K activity, significantly decreased autophagy activity, improved morphologies of intracellular apartments, and most importantly, prevented progressive cardiac dysfunction in hypertrophic hearts. Collectively, we demonstrated that Class III PI3K plays a central role in the transition of cardiac hypertrophy to heart failure via a prolonged activation of autophagy in current study. Class III PI3K may serve as a potential target for the treatment and management of maladaptive cardiac hypertrophy.

  18. Disrupted cell cycle arrest and reduced proliferation in corneal fibroblasts from GCD2 patients: A potential role for altered autophagy flux

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seung-il; Dadakhujaev, Shorafidinkhuja; Maeng, Yong-Sun; Ahn, So-yeon; Kim, Tae-im [Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kim, Eung Kweon, E-mail: eungkkim@yuhs.ac [Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul (Korea, Republic of); BK21 Plus Project for Medical Science and Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2015-01-02

    Highlights: • Reduced cell proliferation in granular corneal dystrophy type 2. • Abnormal cell cycle arrest by defective autophagy. • Decreased Cyclin A1, B1, and D1 in Atg7 gene knockout cells. • Increase in p16 and p27 expressions were observed in Atg7 gene knockout cells. - Abstract: This study investigates the role of impaired proliferation, altered cell cycle arrest, and defective autophagy flux of corneal fibroblasts in granular corneal dystrophy type 2 (GCD2) pathogenesis. The proliferation rates of homozygous (HO) GCD2 corneal fibroblasts at 72 h, 96 h, and 120 h were significantly lower (1.102 ± 0.027, 1.397 ± 0.039, and 1.527 ± 0.056, respectively) than those observed for the wild-type (WT) controls (1.441 ± 0.029, 1.758 ± 0.043, and 2.003 ± 0.046, respectively). Flow cytometry indicated a decreased G{sub 1} cell cycle progression and the accumulation of cells in the S and G{sub 2}/M phases in GCD2 cells. These accumulations were associated with decreased levels of Cyclin A1, B1, and E1, and increased expression of p16 and p27. p21 and p53 expression was also significantly lower in GCD2 cells compared to the WT. Interestingly, treatment with the autophagy flux inhibitor, bafilomycin A{sub 1}, resulted in similarly decreased Cyclin A1, B1, D1, and p53 expression in WT fibroblasts. Furthermore, similar findings, including a decrease in Cyclin A1, B1, and D1 and an increase in p16 and p27 expression were observed in autophagy-related 7 (Atg7; known to be essential for autophagy) gene knockout cells. These data provide new insight concerning the role of autophagy in cell cycle arrest and cellular proliferation, uncovering a number of novel therapeutic possibilities for GCD2 treatment.

  19. Multi-Strain Probiotics Inhibit Cardiac Myopathies and Autophagy to Prevent Heart Injury in High-Fat Diet-Fed Rats.

    Science.gov (United States)

    Lai, Chao-Hung; Tsai, Cheng-Chih; Kuo, Wei-Wen; Ho, Tsung-Jung; Day, Cecilia-Hsuan; Pai, Pei-ying; Chung, Li-Chin; Huang, Chun-Chih; Wang, Hsueh-Fang; Liao, Po-Hsiang; Huang, Chih-Yang

    2016-01-01

    High-fat diets induce obesity, leading to cardiomyocyte fibrosis and autophagy imbalance. In addition, no previous studies have indicated that probiotics have potential health effects associated with cardiac fibrosis and autophagy in obese rats. This study investigates the effects of probiotics on high-fat (HF) diet-induced obesity and cardiac fibrosis and autophagy in rat hearts. Eight-week-old male Wistar rats were separated randomly into five equally sized experimental groups: Normal diet (control) and high-fat (HF) diet groups and groups fed a high-fat diet supplemented with low (HL), medium (HM) or high (HH) doses of multi-strain probiotic powders. These experiments were designed for an 8-week trial period. The myocardial architecture of the left ventricle was evaluated using Masson's trichrome staining and immunohistochemistry staining. Key probiotics-related pathway molecules were analyzed using western blotting. Abnormal myocardial architecture and enlarged interstitial spaces were observed in HF hearts. These interstitial spaces were significantly decreased in groups provided with multi-strain probiotics compared with HF hearts. Western blot analysis demonstrated that key components of the TGF/MMP2/MMP9 fibrosis pathways and ERK5/uPA/ANP cardiac hypertrophy pathways were significantly suppressed in probiotic groups compared to the HF group. Autophagy balance is very important in cardiomyocytes. In this study, we observed that the beclin-1/LC3B/Atg7 autophagy pathway in HF was increased after probiotic supplementation was significantly decreased. Together, these results suggest that oral administration of probiotics may attenuate cardiomyocyte fibrosis and cardiac hypertrophy and the autophagy-signaling pathway in obese rats.

  20. Ubiquitin regulates caspase recruitment domain-mediated signaling by nucleotide-binding oligomerization domain-containing proteins NOD1 and NOD2.

    Science.gov (United States)

    Ver Heul, Aaron M; Fowler, C Andrew; Ramaswamy, S; Piper, Robert C

    2013-03-08

    NOD1 and NOD2 (nucleotide-binding oligomerization domain-containing proteins) are intracellular pattern recognition receptors that activate inflammation and autophagy. These pathways rely on the caspase recruitment domains (CARDs) within the receptors, which serve as protein interaction platforms that coordinately regulate immune signaling. We show that NOD1 CARD binds ubiquitin (Ub), in addition to directly binding its downstream targets receptor-interacting protein kinase 2 (RIP2) and autophagy-related protein 16-1 (ATG16L1). NMR spectroscopy and structure-guided mutagenesis identified a small hydrophobic surface of NOD1 CARD that binds Ub. In vitro, Ub competes with RIP2 for association with NOD1 CARD. In vivo, we found that the ligand-stimulated activity of NOD1 with a mutant CARD lacking Ub binding but retaining ATG16L1 and RIP2 binding is increased relative to wild-type NOD1. Likewise, point mutations in the tandem NOD2 CARDs at positions analogous to the surface residues defining the Ub interface on NOD1 resulted in loss of Ub binding and increased ligand-stimulated NOD2 signaling. These data suggest that Ub binding provides a negative feedback loop upon NOD-dependent activation of RIP2.

  1. Feeling Abnormal: Simulation of Deviancy in Abnormal and Exceptionality Courses.

    Science.gov (United States)

    Fernald, Charles D.

    1980-01-01

    Describes activity in which student in abnormal psychology and psychology of exceptional children classes personally experience being judged abnormal. The experience allows the students to remember relevant research, become sensitized to the feelings of individuals classified as deviant, and use caution in classifying individuals as abnormal.…

  2. Dynamics of ubiquitin-mediated signalling: insights from mathematical modelling and experimental studies.

    Science.gov (United States)

    Nguyen, Lan K

    2016-05-01

    Post-translational modification of cellular proteins by ubiquitin is a pivotal regulatory event that controls not only protein degradation, but also a variety of non-proteolytic functions. Ubiquitination is involved in a broad array of physiological processes, and its dysregulation has been associated with many human diseases, including neuronal disorders and cancers. Ubiquitin-mediated signalling has thus come to the forefront of biomedical research. It is increasingly apparent that ubiquitination is a highly complex and dynamic process, evidenced by a myriad of ways of ubiquitin chain formation, tightly regulatory mechanisms involving E3 ligases and deubiquitinating enzymes and extensive crosstalk with other post-translational modifications. To unravel the complexity of ubiquitination and understand the dynamic properties of ubiquitin-mediated signalling are challenging, but critical topics in ubiquitin research, which will undoubtedly benefit our effort in developing strategies that could target ubiquitin signalling for therapeutics. Computational modelling and model-based approaches are emerging as promising tools that help tackle the complexity and provide useful frameworks for quantitative and dynamical analysis of ubiquitin signalling. In this article, I will discuss recent advances in our understanding of the dynamic behaviour of ubiquitination from both theoretical and experimental studies, and aspects of ubiquitin signalling that may have major dynamical consequences. It is expected the discussed issues will be of relevant interest to both the ubiquitin and systems biology fields.

  3. Modulation of Autophagy-Like Processes by Tumor Viruses

    Directory of Open Access Journals (Sweden)

    Karl Munger

    2012-06-01

    Full Text Available Autophagy is an intracellular degradation pathway for long-lived proteins and organelles. This process is activated above basal levels upon cell intrinsic or environmental stress and dysregulation of autophagy has been linked to various human diseases, including those caused by viral infection. Many viruses have evolved strategies to directly interfere with autophagy, presumably to facilitate their replication or to escape immune detection. However, in some cases, modulation of autophagy appears to be a consequence of the virus disturbing the cell’s metabolic signaling networks. Here, we summarize recent advances in research at the interface of autophagy and viral infection, paying special attention to strategies that human tumor viruses have evolved.

  4. Host Cell Autophagy in Immune Response to Zoonotic Infections

    Directory of Open Access Journals (Sweden)

    Panagiotis Skendros

    2012-01-01

    Full Text Available Autophagy is a fundamental homeostatic process in which cytoplasmic targets are sequestered within double-membraned autophagosomes and subsequently delivered to lysosomes for degradation. Accumulating evidence supports the pivotal role of autophagy in host defense against intracellular pathogens implicating both innate and adaptive immunity. Many of these pathogens cause common zoonotic infections worldwide. The induction of the autophagic machinery by innate immune receptors signaling, such as TLRs, NOD1/2, and p62/SQSTM1 in antigen-presenting cells results in inhibition of survival and elimination of invading pathogens. Furthermore, Th1 cytokines induce the autophagic process, whereas autophagy also contributes to antigen processing and MHC class II presentation, linking innate to adaptive immunity. However, several pathogens have developed strategies to avoid autophagy or exploit autophagic machinery to their advantage. This paper focuses on the role of host cell autophagy in the regulation of immune response against intracellular pathogens, emphasizing on selected bacterial and protozoan zoonoses.

  5. Autophagy process is associated with anti-neoplastic function

    Institute of Scientific and Technical Information of China (English)

    Chong Wang; Yachen Wang; Michael A. McNutt; Wei-Guo Zhu

    2011-01-01

    Autophagy is a highly conserved process of cellular degradation, which is present in yeast, plants, and mammals.Under normal physiological conditions, autophagy acts to maintain cellular homeostasis and regulate the turnover of organelles.In response to cellular stresses, autophagy prevents the accumulation of impaired proteins and organelles, which serves to inhibit carcinogenesis.On this basis,it is widely accepted that most tumor suppressors, such as beclin 1 associated proteins, forkhead box class O (FoxO)family proteins, multiple mammalian target of Rapamycin (mTOR) inactivators, and nuclear p53 play a role in indu cing autophagy.Here, we focus on how the process of autophagy is associated with anti-neoplastic function.

  6. Autophagy in Plants--What's New on the Menu?

    Science.gov (United States)

    Michaeli, Simon; Galili, Gad; Genschik, Pascal; Fernie, Alisdair R; Avin-Wittenberg, Tamar

    2016-02-01

    Autophagy is a major cellular degradation pathway in eukaryotes. Recent studies have revealed the importance of autophagy in many aspects of plant life, including seedling establishment, plant development, stress resistance, metabolism, and reproduction. This is manifested by the dual ability of autophagy to execute bulk degradation under severe environmental conditions, while simultaneously to be highly selective in targeting specific compartments and protein complexes to regulate key cellular processes, even during favorable growth conditions. Delivery of cellular components to the vacuole enables their recycling, affecting the plant metabolome, especially under stress. Recent research in Arabidopsis has further unveiled fundamental mechanistic aspects in autophagy which may have relevance in non-plant systems. We review the most recent discoveries concerning autophagy in plants, touching upon all these aspects.

  7. Targeting autophagy to sensitive glioma to temozolomide treatment.

    Science.gov (United States)

    Yan, Yuanliang; Xu, Zhijie; Dai, Shuang; Qian, Long; Sun, Lunquan; Gong, Zhicheng

    2016-02-02

    Temozolomide (TMZ), an alkylating agent, is widely used for treating primary and recurrent high-grade gliomas. However, the efficacy of TMZ is often limited by the development of resistance. Recently, studies have found that TMZ treatment could induce autophagy, which contributes to therapy resistance in glioma. To enhance the benefit of TMZ in the treatment of glioblastomas, effective combination strategies are needed to sensitize glioblastoma cells to TMZ. In this regard, as autophagy could promote cell survival or autophagic cell death, modulating autophagy using a pharmacological inhibitor, such as chloroquine, or an inducer, such as rapamycin, has received considerably more attention. To understand the effectiveness of regulating autophagy in glioblastoma treatment, this review summarizes reports on glioblastoma treatments with TMZ and autophagic modulators from in vitro and in vivo studies, as well as clinical trials. Additionally, we discuss the possibility of using autophagy regulatory compounds that can sensitive TMZ treatment as a chemotherapy for glioma treatment.

  8. Berberine attenuates autophagy in adipocytes by targeting BECN1.

    Science.gov (United States)

    Deng, Yujie; Xu, Jun; Zhang, Xiaoyan; Yang, Jian; Zhang, Di; Huang, Jian; Lv, Pengfei; Shen, Weili; Yang, Ying

    2014-10-01

    The lysosomal degradation pathway, autophagy, is essential for the maintenance of cellular homeostasis. Recently, autophagy has been demonstrated to be required in the process of adipocyte conversion. However, its role in mature adipocytes under physiological and pathological conditions remains unclear. Here, we report a major function of BECN1 in the regulation of basal autophagy in mature adipocytes. We also show that berberine, a natural plant alkaloid, inhibits basal autophagy in adipocytes and adipose tissue of mice fed a high-fat diet via downregulation of BECN1 expression. We further demonstrate that berberine has a pronounced effect on the stability of Becn 1 mRNA through the Mir30 family. These findings explore the potential of BECN1 as a key molecule and a drug target for regulating autophagy in mature adipocytes.

  9. Redox regulation of autophagy in healthy brain and neurodegeneration.

    Science.gov (United States)

    Hensley, Kenneth; Harris-White, Marni E

    2015-12-01

    Autophagy and redox biochemistry are two major sub disciplines of cell biology which are both coming to be appreciated for their paramount importance in the etiology of neurodegenerative diseases including Alzheimer's disease (AD). Thus far, however, there has been relatively little exploration of the interface between autophagy and redox biology. Autophagy normally recycles macro-molecular aggregates produced through oxidative-stress mediated pathways, and also may reduce the mitochondrial production of reactive oxygen species through recycling of old and damaged mitochondria. Conversely, dysfunction in autophagy initiation, progression or clearance is evidenced to increase aggregation-prone proteins in neural and extraneural tissues. Redox mechanisms of autophagy regulation have been documented at the level of cross-talk between the Nrf2/Keap1 oxidant and electrophilic defense pathway and p62/sequestosome-1 (SQSTM1)-associated autophagy, at least in extraneural tissue; but other mechanisms of redox autophagy regulation doubtless remain to be discovered and the relevance of such processes to maintenance of neural homeostasis remains to be determined. This review summarizes current knowledge regarding the relationship of redox signaling, autophagy control, and oxidative stress as these phenomena relate to neurodegenerative disease. AD is specifically addressed as an example of the theme and as a promising indication for new therapies that act through engagement of autophagy pathways. To exemplify one such novel therapeutic entity, data is presented that the antioxidant and neurotrophic agent lanthionine ketimine-ethyl ester (LKE) affects autophagy pathway proteins including beclin-1 in the 3xTg-AD model of Alzheimer's disease where the compound has been shown to reduce pathological features and cognitive dysfunction.

  10. Russia: An Abnormal Country

    Directory of Open Access Journals (Sweden)

    Steven Rosefielde

    2005-06-01

    Full Text Available Andrei Shleifer and Daniel Treisman recently rendered a summary verdict on the post Soviet Russian transition experience finding that the Federation had become a normal country with the west's assistance, and predicting that it would liberalize and develop further like other successful nations of its type. This essay demonstrates that they are mistaken on the first count, and are likely to be wrong on the second too. It shows factually, and on the norms elaborated by Pareto, Arrow and Bergson that Russia is an abnormal political economy unlikely to democratize, westernize or embrace free enterprise any time soon

  11. Abnormal ionization in sonoluminescence

    Science.gov (United States)

    Zhang, Wen-Juan; An, Yu

    2015-04-01

    Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%-70% as the bubble flashes, which is difficult to explain by using previous models. Project supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120002110031) and the National Natural Science Foundation of China (Grant No. 11334005).

  12. Ataxia, Dementia, and Hypogonadotropism Caused by Disordered Ubiquitination

    DEFF Research Database (Denmark)

    Margolin, David H.; Kousi, Maria; Chan, Yee-Ming

    2013-01-01

    affected patients. Neurologic and reproductive endocrine phenotypes were characterized in detail. The effects of sequence variants and the presence of an epistatic interaction were tested in a zebrafish model. RESULTS Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase...... in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions. Defects were detected at the hypothalamic and pituitary levels of the reproductive endocrine axis. CONCLUSIONS The syndrome of hypogonadotropic hypogonadism, ataxia, and dementia...... can be caused by inactivating mutations in RNF216 or by the combination of mutations in RNF216 and OTUD4. These findings link disordered ubiquitination to neurodegeneration and reproductive dysfunction and highlight the power of whole-exome sequencing in combination with functional studies to unveil...

  13. Structure of a RING E3 ligase and ubiquitin-loaded E2 primed for catalysis

    Science.gov (United States)

    Plechanovová, Anna; Jaffray, Ellis; Tatham, Michael H.; Naismith, James H.; Hay, Ronald T.

    2012-01-01

    SUMMARY Ubiquitin modification is mediated by a large family of specificity determining ubiquitin E3 ligases. To facilitate ubiquitin transfer, RING E3 ligases bind both substrate and a ubiquitin E2 conjugating enzyme linked to ubiquitin via a thioester bond, but the mechanism of transfer has remained elusive. Here we report the crystal structure of the dimeric RING of RNF4 in complex with E2 (UbcH5a) linked by an isopeptide bond to ubiquitin. While the E2 contacts a single protomer of the RING, ubiquitin is folded back onto the E2 by contacts from both RING protomers. The C-terminal tail of ubiquitin is locked into an active site groove on the E2 by an intricate network of interactions, resulting in changes at the E2 active site. This arrangement is primed for catalysis as it can deprotonate the incoming substrate lysine residue and stabilise the consequent tetrahedral transition state intermediate. PMID:22842904

  14. The ubiquitin proteasome system in glia and its role in neurodegenerative diseases

    NARCIS (Netherlands)

    Jansen, A.H.P.; Reits, E.A.J.; Hol, E.M.

    2014-01-01

    The ubiquitin proteasome system (UPS) is crucial for intracellular protein homeostasis and for degradation of aberrant and damaged proteins. The accumulation of ubiquitinated proteins is a hallmark of many neurodegenerative diseases, including amyotrophic lateral sclerosis, Alzheimer's, Parkinson's,

  15. Characterization of ubiquitination dependent dynamics in growth factor receptor signaling by quantitative proteomics

    DEFF Research Database (Denmark)

    Akimov, Vyacheslav; Rigbolt, Kristoffer T G; Nielsen, Mogens M;

    2011-01-01

    ) for selectively decoding ubiquitination-driven processes involved in the regulation of cellular signaling networks. We applied this approach to characterize the temporal dynamics of ubiquitination events accompanying epidermal growth factor receptor (EGFR) signal transduction. We used recombinant UBDs derived...

  16. Glutamine deamidation and dysfunction of ubiquitin/NEDD8 induced by a bacterial effector family.

    Science.gov (United States)

    Cui, Jixin; Yao, Qing; Li, Shan; Ding, Xiaojun; Lu, Qiuhe; Mao, Haibin; Liu, Liping; Zheng, Ning; Chen, She; Shao, Feng

    2010-09-03

    A family of bacterial effectors including Cif homolog from Burkholderia pseudomallei (CHBP) and Cif from Enteropathogenic Escherichia coli (EPEC) adopt a functionally important papain-like hydrolytic fold. We show here that CHBP was a potent inhibitor of the eukaryotic ubiquitination pathway. CHBP acted as a deamidase that specifically and efficiently deamidated Gln40 in ubiquitin and ubiquitin-like protein NEDD8 both in vitro and during Burkholderia infection. Deamidated ubiquitin was impaired in supporting ubiquitin-chain synthesis. Cif selectively deamidated NEDD8, which abolished the activity of neddylated Cullin-RING ubiquitin ligases (CRLs). Ubiquitination and ubiquitin-dependent degradation of multiple CRL substrates were impaired by Cif in EPEC-infected cells. Mutations of substrate-contacting residues in Cif abolished or attenuated EPEC-induced cytopathic phenotypes of cell cycle arrest and actin stress fiber formation.

  17. In silico analysis of ubiquitin/ubiquitin-like modifiers and their conjugating enzymes in Entamoeba species.

    Science.gov (United States)

    Arya, Shweta; Sharma, Gaurav; Gupta, Preeti; Tiwari, Swati

    2012-07-01

    Covalent modification of proteins by ubiquitin (Ub) and ubiquitin-like modifiers (Ubls) regulates many cellular functions in eukaryotes. These modifications are likely to be associated with pathogenesis, growth, and development of many protozoan parasites but molecular details about this pathway are unavailable for most protozoa. This study presents an analysis of the Ub pathway in three members of the Entamoeba species. Using bioinformatics tools we have identified all Ub and Ubl genes along with their corresponding activating, conjugating, and ligating enzymes (E1, E2s, and E3s) in three Entamoeba species, Entamoeba histolytica, Entamoeba dispar, and Entamoeba invadens. Phylogenetic trees were established for the identified E2s and RING finger E3s using maximum-likelihood method to infer the relationship among these proteins. In silico co-domain analysis of RING finger E3s implicates these proteins in a variety of functions. Several known and putative regulatory motifs were identified in the upstream regions of RING finger domain containing E3 genes. All E2 and E3 genes were analyzed in genomic context in E. histolytica and E. dispar. Most E2s and E3s were in syntenic positions in the two genomes. Association of these genes with transposable elements (TEs) was compared between E. histolytica and E. dispar. A closer association was found between RING finger E3s with TEs in E. histolytica. In summary, our analyses suggests that the complexity of the Ub pathway in Entamoeba species is close to that observed in higher eukaryotes. This study provides important data for further understanding the role of Ub pathway in the biology of these organisms.

  18. Functional assessment of ubiquitin-depended processes under microgravity conditions

    Science.gov (United States)

    Zhabereva, Anastasia; Shenkman, Boris S.; Gainullin, Murat; Gurev, Eugeny; Kondratieva, Ekaterina; Kopylov, Arthur

    Ubiquitylation, a widespread and important posttranslational modification of eukaryotic proteins, controls a multitude of critical cellular processes, both in normal and pathological conditions. The present work aims to study involvement of ubiquitin-dependent regulation in adaptive response to the external stimuli. Experiments were carried out on C57BL/6 mice. The microgravity state under conditions of real spaceflight on the biosatellite “BION-M1” was used as a model of stress impact. Additionally, number of control series including the vivarium control and experiments in Ground-based analog were also studied. The aggregate of endogenously ubiquitylated proteins was selected as specific feature of ubiquitin-dependent processes. Dynamic changes of modification pattern were characterized in liver tissue by combination of some methods, particularly by specific isolation of explicit protein pool, followed by immunodetection and/or mass spectrometry-based identification. The main approach includes specific extraction of proteins, modified by multiubiquitin chains of different length and topology. For this purpose two techniques were applied: 1) immunoprecipitation with antibodies against ubiquitin and/or multiubiquitin chains; 2) pull-down using synthetic protein construct termed Tandem Ubiquitin Binding Entities (TUBE, LifeSensors). TUBE represents fusion protein, composed of well characterized ubiquitin-binding domains, and thereby allows specific high-affinity binding and extraction of ubiquitylated proteins. Resulting protein fractions were analyzed by immunoblotting with antibodies against different types of multiubiquitin chains. Using this method we mapped endogenously modified proteins involved in two different types of ubiquitin-dependent processes, namely catabolic and non-catabolic ubiquitylation, in liver tissues, obtained from both control as well as experimental groups of animals, mentioned above. Then, isolated fractions of ubiquitylated proteins

  19. The ubiquitin system: a critical regulator of innate immunity and pathogen–host interactions

    OpenAIRE

    Li, Jie; Chai, Qi-Yao; Liu, Cui Hua

    2016-01-01

    The ubiquitin system comprises enzymes that are responsible for ubiquitination and deubiquitination, as well as ubiquitin receptors that are capable of recognizing and deciphering the ubiquitin code, which act in coordination to regulate almost all host cellular processes, including host–pathogen interactions. In response to pathogen infection, the host innate immune system launches an array of distinct antimicrobial activities encompassing inflammatory signaling, phagosomal maturation, autop...

  20. New Insights into the Role of Mitochondrial Dynamics and Autophagy during Oxidative Stress and Aging in the Heart

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Ikeda

    2014-01-01

    Full Text Available The heart is highly sensitive to the aging process. In the elderly, the heart tends to become hypertrophic and fibrotic. Stiffness increases with ensuing systolic and diastolic dysfunction. Aging also affects the cardiac response to stress. At the molecular level, the aging process is associated with accumulation of damaged proteins and organelles, partially due to defects in protein quality control systems. The accumulation of dysfunctional and abnormal mitochondria is an important pathophysiological feature of the aging process, which is associated with excessive production of reactive oxygen species. Mitochondrial fusion and fission and mitochondrial autophagy are crucial mechanisms for maintaining mitochondrial function and preserving energy production. In particular, mitochondrial fission allows for selective segregation of damaged mitochondria, which are afterward eliminated by autophagy. Unfortunately, recent evidence indicates that mitochondrial dynamics and autophagy are progressively impaired over time, contributing to the aging process. This suggests that restoration of these mechanisms could delay organ senescence and prevent age-associated cardiac diseases. Here, we discuss the current understanding of the close relationship between mitochondrial dynamics, mitophagy, oxidative stress, and aging, with a particular focus on the heart.

  1. Ubiquitination independent of E1 and E2 enzymes by bacterial effectors

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Jiazhang; Sheedlo, Michael J.; Yu, Kaiwen; Tan, Yunhao; Nakayasu, Ernesto S.; Das, Chittaranjan; Liu, Xiaoyun; Luo, Zhao-Qing

    2016-04-06

    Signaling by ubiquitination regulates virtually every cellular process in eukaryotes. Covalent attachment of ubiquitin to a substrate is catalyzed by the E1, E2 and E3 three-enzyme cascade 1, which links the C terminus of ubiquitin via an isopeptide bond mostly to the ε-amino group of a lysine of the substrate. Given the essential roles of ubiquitination in the regulation of the immune system, it is not surprising that the ubiquitination network is a common target for diverse infectious agents 2. For example, many bacterial pathogens exploit ubiquitin signaling using virulence factors that function as E3 ligases, deubiquitinases 3 or as enzymes that directly attack ubiquitin 4. The bacterial pathogen Legionella pneumophila utilizes approximately 300 effectors that modulate diverse host processes to create a niche permissive for its replication in phagocytes 5. Here we demonstrate that members of the SidE effector family (SidEs) of L. pneumophila ubiquitinate multiple Rab small GTPases associated with the endoplasmic reticulum (ER). Moreover, we show that these proteins are capable of catalyzing ubiquitination without the need for the E1 and E2 enzymes. The E1/E2-independent ubiquitination catalyzed by these enzymes requires NAD but not ATP and Mg2+. A putative mono ADP-ribosyltransferase (mART) motif critical for the ubiquitination activity is also essential for the role of SidEs in intracellular bacterial replication in a protozoan host. These results establish that ubiquitination can be catalyzed by a single enzyme.

  2. UBPY-mediated epidermal growth factor receptor (EGFR) de-ubiquitination promotes EGFR degradation

    NARCIS (Netherlands)

    Alwan, H.A.J.; Leeuwen, J.E.M. van

    2007-01-01

    Whereas poly-ubiquitination targets protein substrates for proteasomal degradation, mono-ubiquitination is known to regulate protein trafficking in the endosomal system and to target cargo proteins for lysosomal degradation. The role of the de-ubiquitinating enzymes AMSH and UBPY in endosomal traffi

  3. Extralysosomal turnover of cellular proteins: Targeting substrates in the ubiquitin, ATP-dependent degradation system

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, D.

    1988-01-01

    Calmodulin derived from a cloned chicken gene can be ubiquitinated and degraded by an in vitro reticulocyte lysate system. The chemical reactivity and the surface accessibility of the {epsilon}-amino group on lysine 115 in the calmodulin polypeptide chain were studied by trace labeling with acetic anhydride and with a ubiquitin derivative containing an azido group at the C-terminal glycine residue. Fractionation of reticulocyte lysate proteins separated the activity which degrades the calmodulin moiety of ubiquitin-calmodulin conjugates from that which acts on the isopeptide linkage. Neither of these two activities act on a synthetic isopeptide, which mimics the junction of ubiquitin-calmodulin, indicating the importance of the folding of ubiquitin for recognition. Based on recent findings that the ubiquitin moieties linked to {beta}galactosidase exist as a single multiubiquitin chain, studies were carried out to determine the structure of the ubiquitin-ubiquitin linkage. Ubiquitin was in vivo labeled with ({sup 3}H) and conjugated to {beta}galactosidase. Individual conjugates were isolated and subjected to peptide mapping by trypsin digestion, and tryptic fragments were analyzed of HPLC. The results indicated that the ubiquitin-ubiquitin linkage involves lysine residue 48 in the ubiquitin sequence.

  4. Selectivity of E2-E3 interactions in the human ubiquitin system

    NARCIS (Netherlands)

    van Wijk, S.J.L.

    2010-01-01

    Highly selective interactions between ubiquitin-conjugating enzymes and RING-type E3 ligases are crucial for the adequate and efficient action of ubiquitin and ubiquitin-like pathways. Within these cascades, E2 enzymes provide a connecting link between activation and the final covalent conjugation,

  5. Cannabidiol Post-Treatment Alleviates Rat Epileptic-Related Behaviors and Activates Hippocampal Cell Autophagy Pathway Along with Antioxidant Defense in Chronic Phase of Pilocarpine-Induced Seizure.

    Science.gov (United States)

    Hosseinzadeh, Mahshid; Nikseresht, Sara; Khodagholi, Fariba; Naderi, Nima; Maghsoudi, Nader

    2016-04-01

    Abnormal and sometimes severe behavioral and molecular symptoms are usually observed in epileptic humans and animals. To address this issue, we examined the behavioral and molecular aspects of seizure evoked by pilocarpine. Autophagy can promote both cell survival and death, but there are controversial reports about the neuroprotective or neurodegenerative effects of autophagy in seizure. Cannabidiol has anticonvulsant properties in some animal models when used as a pretreatment. In this study, we investigated alteration of seizure scores, autophagy pathway proteins, and antioxidant status in hippocampal cells during the chronic phase of pilocarpine-induced epilepsy after treatment with cannabidiol. Cannabidiol (100 ng, intracerebroventricular injection) delayed the chronic phase of epilepsy. Single administration of cannabidiol during the chronic phase of seizure significantly diminished seizure scores such as mouth clonus, head nodding, monolateral and bilateral forelimb clonus and increased the activity of catalase enzyme and reduced glutathione content. Such a protective effect in the behavioral scores of epileptic rats was also observed after repeated administrations of cannabidiol at the onset of the silent phase. Moreover, the amount of Atg7, conjugation of Atg5/12, Atg12, and LC3II/LC3I ratio increased significantly in epileptic rats treated with repeated injections of cannabidiol. In short, our results suggest that post-treatment of Cannabidiol could enhance the induction of autophagy pathway and antioxidant defense in the chronic phase of epilepsy, which could be considered as the protective mechanisms of cannabidiol in a temporal lobe epilepsy model.

  6. Laser stimulation can activate autophagy in HeLa cells

    Science.gov (United States)

    Wang, Yisen; Lan, Bei; He, Hao; Hu, Minglie; Cao, Youjia; Wang, Chingyue

    2014-10-01

    For decades, lasers have been a daily tool in most biological research for fluorescent excitation by confocal or multiphoton microscopy. More than 20 years ago, cell photodamage caused by intense laser stimulation was noticed by generating reactive oxygen species, which was then thought as the main damage effect by photons. In this study, we show that laser stimulation can induce autophagy, an important cell lysosomal pathway responding to immune stimulation and starvation, without any biochemical treatment. Two different types of laser stimulations are found to be capable of activating autophagy: continuous scanning by continuous-wave visible lasers and a short-time flash of femtosecond laser irradiation. The autophagy generation is independent from wavelength, power, and scanning duration of the visible lasers. In contrast, the power of femtosecond laser is very critical to autophagy because the multiphoton excited Ca2+ dominates autophagy signaling. In general, we show here the different mechanisms of autophagy generation by such laser stimulation, which correspond to confocal microscopy and cell surgery, respectively. Those results can help further understanding of photodamage and autophagy signaling.

  7. Laser stimulation can activate autophagy in HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yisen; Hu, Minglie; Wang, Chingyue [Ultrafast Laser Laboratory, Key Laboratory of Optoelectronic Information Technology (Ministry of Education), College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin (China); Lan, Bei; Cao, Youjia [Key Laboratory of Microbial Functional Genomics of Ministry of Education, College of Life Sciences, Nankai University, Tianjin (China); He, Hao, E-mail: haohe@tju.edu.cn [Ultrafast Laser Laboratory, Key Laboratory of Optoelectronic Information Technology (Ministry of Education), College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin (China); Med-X Research Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai (China)

    2014-10-27

    For decades, lasers have been a daily tool in most biological research for fluorescent excitation by confocal or multiphoton microscopy. More than 20 years ago, cell photodamage caused by intense laser stimulation was noticed by generating reactive oxygen species, which was then thought as the main damage effect by photons. In this study, we show that laser stimulation can induce autophagy, an important cell lysosomal pathway responding to immune stimulation and starvation, without any biochemical treatment. Two different types of laser stimulations are found to be capable of activating autophagy: continuous scanning by continuous-wave visible lasers and a short-time flash of femtosecond laser irradiation. The autophagy generation is independent from wavelength, power, and scanning duration of the visible lasers. In contrast, the power of femtosecond laser is very critical to autophagy because the multiphoton excited Ca{sup 2+} dominates autophagy signaling. In general, we show here the different mechanisms of autophagy generation by such laser stimulation, which correspond to confocal microscopy and cell surgery, respectively. Those results can help further understanding of photodamage and autophagy signaling.

  8. Lifespan extension by suppression of autophagy genes in Caenorhabditis elegans.

    Science.gov (United States)

    Hashimoto, Yasufumi; Ookuma, Sadatsugu; Nishida, Eisuke

    2009-06-01

    Lifespan is regulated by a complex combination of environmental and genetic factors. Autophagy, which is a bulk degradation system of macromolecules and organelles, has an important role in various biological events. In Caenorhabditis elegans, several autophagy genes have been shown to have a role in promoting longevity, but many other autophagy genes have not been examined for their role in the lifespan regulation. Here we have systematically examined the effect of RNAi suppression of 14 autophagy genes on lifespan. While maternal RNAi of autophagy genes in wild-type worms tended to reduce lifespan, maternal RNAi of each of seven autophagy genes in the insulin/IGF-1 receptor daf-2 mutants extended lifespan. Remarkably, RNAi of unc-51/atg-1, bec-1/atg-6 or atg-9, from young adult, i.e. after development, extended lifespan in both wild-type animals and daf-2 mutants, although RNAi of one or two genes shortened it. Moreover, our analysis suggests that the lifespan extension, which is induced by RNAi of unc-51, bec-1 or atg-9 after development, does not require the transcription factor daf-16, the NAD(+)-dependent protein deacetylase sir-2.1 or the genes related to mitochondrial functions. Collectively, our results suggest that autophagy may not always be beneficial to longevity, but may also function to restrict lifespan in C. elegans.

  9. Basal autophagy protects cardiomyocytes from doxorubicin-induced toxicity.

    Science.gov (United States)

    Pizarro, Marcela; Troncoso, Rodrigo; Martínez, Gonzalo J; Chiong, Mario; Castro, Pablo F; Lavandero, Sergio

    2016-08-31

    Doxorubicin (Doxo) is one of the most effective anti-neoplastic agents but its cardiotoxicity has been an important clinical limitation. The major mechanism of Doxo-induced cardiotoxicity is associated to its oxidative capacity. However, other processes are also involved with significant consequences for the cardiomyocyte. In recent years, a number of studies have investigated the role of autophagy on Doxo-induced cardiotoxicity but to date it is not clear how Doxo alters that process and its consequence on cardiomyocytes viability. Here we investigated the effect of Doxo 1uM for 24h of stimulation on cultured neonatal rat cardiomyocytes. We showed that Doxo inhibits basal autophagy. This inhibition is due to both Akt/mTOR signaling pathway activation and Beclin 1 level decrease. To assess the role of autophagy on Doxo-induced cardiomyocyte death, we evaluated the effects 3-methyladenine (3-MA), bafilomycin A1 (BafA), siRNA Beclin 1 (siBeclin 1) and rapamycin (Rapa) on cell viability. Inhibition of autophagy with 3-MA, BafA and siBeclin 1 increased lactate dehydrogenase (LDH) release but, when autophagy was induced by Rapa, Doxo-induced cardiomyocyte death was decreased. These results suggest that Doxo inhibits basal autophagy and contributes to cardiomyocyte death. Activation of autophagy could be used as a strategy to protect the heart against Doxo toxicity.

  10. Nanomaterials and Autophagy: New Insights in Cancer Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Panzarini, Elisa; Inguscio, Valentina; Tenuzzo, Bernardetta Anna; Carata, Elisabetta; Dini, Luciana, E-mail: luciana.dini@unisalento.it [Department of Biological and Environmental Science and Technology (Di.S.Te.B.A.), University of Salento, Lecce 73100 (Italy)

    2013-03-21

    Autophagy represents a cell’s response to stress. It is an evolutionarily conserved process with diversified roles. Indeed, it controls intracellular homeostasis by degradation and/or recycling intracellular metabolic material, supplies energy, provides nutrients, eliminates cytotoxic materials and damaged proteins and organelles. Moreover, autophagy is involved in several diseases. Recent evidences support a relationship between several classes of nanomaterials and autophagy perturbation, both induction and blockade, in many biological models. In fact, the autophagic mechanism represents a common cellular response to nanomaterials. On the other hand, the dynamic nature of autophagy in cancer biology is an intriguing approach for cancer therapeutics, since during tumour development and therapy, autophagy has been reported to trigger both an early cell survival and a late cell death. The use of nanomaterials in cancer treatment to deliver chemotherapeutic drugs and target tumours is well known. Recently, autophagy modulation mediated by nanomaterials has become an appealing notion in nanomedicine therapeutics, since it can be exploited as adjuvant in chemotherapy or in the development of cancer vaccines or as a potential anti-cancer agent. Herein, we summarize the effects of nanomaterials on autophagic processes in cancer, also considering the therapeutic outcome of synergism between nanomaterials and autophagy to improve existing cancer therapies.

  11. The Regulation of Autophagy by Influenza A Virus

    Directory of Open Access Journals (Sweden)

    Rong Zhang

    2014-01-01

    Full Text Available Influenza A virus is a dreadful pathogen of animals and humans, causing widespread infection and severe morbidity and mortality. It is essential to characterize the influenza A virus-host interaction and develop efficient counter measures against the viral infection. Autophagy is known as a catabolic process for the recycling of the cytoplasmic macromolecules. Recently, it has been shown that autophagy is a critical mechanism underlying the interaction between influenza A virus and its host. Autophagy can be induced by the infection with influenza A virus, which is considered as a necessary process for the viral proliferation, including the accumulation of viral elements during the replication of influenza A virus. On the other hand, influenza A virus can inhibit the autophagic formation via interaction with the autophagy-related genes (Atg and signaling pathways. In addition, autophagy is involved in the influenza virus-regulated cell deaths, leading to significant changes in host apoptosis. Interestingly, the high pathogenic strains of influenza A virus, such as H5N1, stimulate autophagic cell death and appear to interplay with the autophagy in distinct ways as compared with low pathogenic strains. This review discusses the regulation of autophagy, an influenza A virus driven process.

  12. TOR-dependent post-transcriptional regulation of autophagy.

    Science.gov (United States)

    Hu, Guowu; McQuiston, Travis; Bernard, Amélie; Park, Yoon-Dong; Qiu, Jin; Vural, Ali; Zhang, Nannan; Waterman, Scott R; Blewett, Nathan H; Myers, Timothy G; Maraia, Richard J; Kehrl, John H; Uzel, Gulbu; Klionsky, Daniel J; Williamson, Peter R

    2015-01-01

    Regulation of autophagy is required to maintain cellular equilibrium and prevent disease. While extensive study of post-translational mechanisms has yielded important insights into autophagy induction, less is known about post-transcriptional mechanisms that could potentiate homeostatic control. In our study, we showed that the RNA-binding protein, Dhh1 in Saccharomyces cerevisiae and Vad1 in the pathogenic yeast Cryptococcus neoformans is involved in recruitment and degradation of key autophagy mRNAs. In addition, phosphorylation of the decapping protein Dcp2 by the target of rapamycin (TOR), facilitates decapping and degradation of autophagy-related mRNAs, resulting in repression of autophagy under nutrient-replete conditions. The post-transcriptional regulatory process is conserved in both mouse and human cells and plays a role in autophagy-related modulation of the inflammasome product IL1B. These results were then applied to provide mechanistic insight into autoimmunity of a patient with a PIK3CD/p110δ gain-of-function mutation. These results thus identify an important new post-transcriptional mechanism of autophagy regulation that is highly conserved between yeast and mammals.

  13. YY1-MIR372-SQSTM1 regulatory axis in autophagy.

    Science.gov (United States)

    Feng, Lifeng; Ma, Yanning; Sun, Jie; Shen, Qi; Liu, Leiming; Lu, Haiqi; Wang, Faliang; Yue, Yongfang; Li, Jiaqiu; Zhang, Shenjie; Lin, Xiaoying; Chu, Jue; Han, Weidong; Wang, Xian; Jin, Hongchuan

    2014-08-01

    Autophagy is a self-proteolytic process that degrades intracellular material to enable cellular survival under unfavorable conditions. However, how autophagy is activated in human carcinogenesis remains largely unknown. Herein we report an epigenetic regulation of autophagy in human cancer cells. YY1 (YY1 transcription factor) is a well-known epigenetic regulator and is upregulated in many cancers. We found that YY1 knockdown inhibited cell viability and autophagy flux through downregulating SQSTM1 (sequestosome 1). YY1 regulated SQSTM1 expression through the epigenetic modulation of the transcription of MIR372 (microRNA 372) which was found to target SQSTM1 directly. During nutrient starvation, YY1 was stimulated to promote SQSTM1 expression and subsequent autophagy activation by suppressing MIR372 expression. Similar to YY1 depletion, MIR372 overexpression blocked autophagy activation and inhibited in vivo tumor growth. SQSTM1 upregulation and competent autophagy flux thus contributed to the oncogenic function of YY1. YY1-promoted SQSTM1 upregulation might be a useful histological marker for cancer detection and a potential target for drug development.

  14. Autophagy in the immune response to tuberculosis: clinical perspectives.

    LENUS (Irish Health Repository)

    Ní Cheallaigh, C

    2011-06-01

    A growing body of evidence points to autophagy as an essential component in the immune response to tuberculosis. Autophagy is a direct mechanism of killing intracellular Mycobacterium tuberculosis and also acts as a modulator of proinflammatory cytokine secretion. In addition, autophagy plays a key role in antigen processing and presentation. Autophagy is modulated by cytokines; it is stimulated by T helper type 1 (Th1) cytokines such as tumour necrosis factor (TNF)-α and interferon (IFN)-γ, and is inhibited by the Th2 cytokines interleukin (IL)-4 and IL-13 and the anti-inflammatory cytokine IL-10. Vitamin D, via cathelicidin, can also induce autophagy, as can Toll-like receptor (TLR)-mediated signals. Autophagy-promoting agents, administered either locally to the lungs or systemically, could have a clinical application as adjunctive treatment of drug-resistant and drug-sensitive tuberculosis. Moreover, vaccines which effectively induce autophagy could be more successful in preventing acquisition or reactivation of latent tuberculosis.

  15. The inositol trisphosphate receptor in the control of autophagy.

    Science.gov (United States)

    Criollo, Alfredo; Vicencio, José Miguel; Tasdemir, Ezgi; Maiuri, M Chiara; Lavandero, Sergio; Kroemer, Guido

    2007-01-01

    The second messenger myo-inositol-1,4,5-trisphosphate (IP(3)) acts on the IP(3) receptor (IP(3)R), an IP(3)-activated Ca(2+) channel of the endoplasmic reticulum (ER). The IP(3)R agonist IP(3) inhibits starvation-induced autophagy. The IP(3)R antagonist xestospongin B induces autophagy in human cells through a pathway that requires the obligate contribution of Beclin-1, Atg5, Atg10, Atg12 and hVps34, yet is inhibited by ER-targeted Bcl-2 or Bcl-XL, two proteins that physically interact with IP(3)R. Autophagy can also be induced by depletion of the IP(3)R by small interfering RNAs. Autophagy induction by IP(3)R blockade cannot be explained by changes in steady state levels of Ca(2+) in the endoplasmic reticulum (ER) and the cytosol. Autophagy induction by IP(3)R blockade is effective in cells lacking the obligate mediator of ER stress IRE1. In contrast, IRE1 is required for autophagy induced by ER stress-inducing agents such a tunicamycin or thapsigargin. These findings suggest that there are several distinct pathways through which autophagy can be initiated at the level of the ER.

  16. The IKK complex contributes to the induction of autophagy.

    Science.gov (United States)

    Criollo, Alfredo; Senovilla, Laura; Authier, Hélène; Maiuri, Maria Chiara; Morselli, Eugenia; Vitale, Ilio; Kepp, Oliver; Tasdemir, Ezgi; Galluzzi, Lorenzo; Shen, Shensi; Tailler, Maximilien; Delahaye, Nicolas; Tesniere, Antoine; De Stefano, Daniela; Younes, Aména Ben; Harper, Francis; Pierron, Gérard; Lavandero, Sergio; Zitvogel, Laurence; Israel, Alain; Baud, Véronique; Kroemer, Guido

    2010-02-03

    In response to stress, cells start transcriptional and transcription-independent programs that can lead to adaptation or death. Here, we show that multiple inducers of autophagy, including nutrient depletion, trigger the activation of the IKK (IkappaB kinase) complex that is best known for its essential role in the activation of the transcription factor NF-kappaB by stress. Constitutively active IKK subunits stimulated autophagy and transduced multiple signals that operate in starvation-induced autophagy, including the phosphorylation of AMPK and JNK1. Genetic inhibition of the nuclear translocation of NF-kappaB or ablation of the p65/RelA NF-kappaB subunit failed to suppress IKK-induced autophagy, indicating that IKK can promote the autophagic pathway in an NF-kappaB-independent manner. In murine and human cells, knockout and/or knockdown of IKK subunits (but not that of p65) prevented the induction of autophagy in response to multiple stimuli. Moreover, the knockout of IKK-beta suppressed the activation of autophagy by food deprivation or rapamycin injections in vivo, in mice. Altogether, these results indicate that IKK has a cardinal role in the stimulation of autophagy by physiological and pharmacological stimuli.

  17. A Rare Stapes Abnormality

    Directory of Open Access Journals (Sweden)

    Hala Kanona

    2015-01-01

    Full Text Available The aim of this study is to increase awareness of rare presentations, diagnostic difficulties alongside management of conductive hearing loss and ossicular abnormalities. We report the case of a 13-year-old female reporting progressive left-sided hearing loss and high resolution computed tomography was initially reported as normal. Exploratory tympanotomy revealed an absent stapedius tendon and lack of connection between the stapes superstructure and footplate. The footplate was fixed. Stapedotomy and stapes prosthesis insertion resulted in closure of the air-bone gap by 50 dB. A review of world literature was performed using MedLine. Middle ear ossicular discontinuity can result in significant conductive hearing loss. This can be managed effectively with surgery to help restore hearing. However, some patients may not be suitable or decline surgical intervention and can be managed safely conservatively.

  18. Autophagy contributes to gefitinib-induced glioma cell growth inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Cheng-Yi [Department of Surgery, Fong-Yuan Hospital, Taichung 420, Taiwan (China); Graduate Institute of Pharmaceutical Science and Technology, Central Taiwan University of Science and Technology, Taichung 406, Taiwan (China); Kuan, Yu-Hsiang [Department of Pharmacology, School of Medicine, Chung Shan Medical University, Taichung 402, Taiwan (China); Department of Pharmacy, Chung Shan Medical University Hospital, Taichung 402, Taiwan (China); Ou, Yen-Chuan; Li, Jian-Ri [Division of Urology, Taichung Veterans General Hospital, Taichung 407, Taiwan (China); Wu, Chih-Cheng [Department of Anesthesiology, Taichung Veterans General Hospital, Taichung 407, Taiwan (China); Department of Financial and Computational Mathematics, Providence University, Taichung 433, Taiwan (China); Pan, Pin-Ho [Department of Pediatrics, Tungs’ Taichung MetroHarbor Hospital, Taichung 435, Taiwan (China); Chen, Wen-Ying [Department of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan (China); Huang, Hsuan-Yi [Department of Surgery, Fong-Yuan Hospital, Taichung 420, Taiwan (China); Chen, Chun-Jung, E-mail: cjchen@vghtc.gov.tw [Department of Medical Research, Taichung Veterans General Hospital, Taichung 407, Taiwan (China); Institute of Biomedical Sciences, National Chung Hsing University, Taichung 402, Taiwan (China); Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan (China); Center for General Education, Tunghai University, Taichung 407, Taiwan (China); Department of Nursing, HungKuang University, Taichung 433, Taiwan (China)

    2014-09-10

    Epidermal growth factor receptor tyrosine kinase inhibitors, including gefitinib, have been evaluated in patients with malignant gliomas. However, the molecular mechanisms involved in gefitinib-mediated anticancer effects against glioma are incompletely understood. In the present study, the cytostatic potential of gefitinib was demonstrated by the inhibition of glioma cell growth, long-term clonogenic survival, and xenograft tumor growth. The cytostatic consequences were accompanied by autophagy, as evidenced by monodansylcadaverine staining of acidic vesicle formation, conversion of microtubule-associated protein-1 light chain 3-II (LC3-II), degradation of p62, punctate pattern of GFP-LC3, and conversion of GFP-LC3 to cleaved-GFP. Autophagy inhibitor 3-methyladenosine and chloroquine and genetic silencing of LC3 or Beclin 1 attenuated gefitinib-induced growth inhibition. Gefitinib-induced autophagy was not accompanied by the disruption of the Akt/mammalian target of rapamycin signaling. Instead, the activation of liver kinase-B1/AMP-activated protein kinase (AMPK) signaling correlated well with the induction of autophagy and growth inhibition caused by gefitinib. Silencing of AMPK suppressed gefitinib-induced autophagy and growth inhibition. The crucial role of AMPK activation in inducing glioma autophagy and growth inhibition was further supported by the actions of AMP mimetic AICAR. Gefitinib was shown to be capable of reducing the proliferation of glioma cells, presumably by autophagic mechanisms involving AMPK activation. - Highlights: • Gefitinib causes cytotoxic and cytostatic effect on glioma. • Gefitinib induces autophagy. • Gefitinib causes cytostatic effect through autophagy. • Gefitinib induces autophagy involving AMPK.

  19. The interplays between autophagy and apoptosis induced by enterovirus 71.

    Directory of Open Access Journals (Sweden)

    Xueyan Xi

    Full Text Available BACKGROUND: Enterovirus 71 (EV71 is the causative agent of human diseases with distinct severity, from mild hand, foot and mouth disease to severe neurological syndromes, such as encephalitis and meningitis. The lack of understanding of viral pathogenesis as well as lack of efficient vaccine and drugs against this virus impedes the control of EV71 infection. EV71 virus induces autophagy and apoptosis; however, the relationship between EV71-induced autophagy and apoptosis as well as the influence of autophagy and apoptosis on virus virulence remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: In this study, it was observed that the Anhui strain of EV71 induced autophagy and apoptosis in human rhabdomyosarcoma (RD-A cells. Additionally, by either applying chemical inhibitors or knocking down single essential autophagic or apoptotic genes, inhibition of EV71 induced autophagy inhibited the apoptosis both at the autophagosome formation stage and autophagy execution stage. However, inhibition of autophagy at the stage of autophagosome and lysosome fusion promoted apoptosis. In reverse, the inhibition of EV71-induced apoptosis contributed to the conversion of microtubule-associated protein 1 light chain 3-I (LC3-I to LC3-II and degradation of sequestosome 1 (SQSTM1/P62. Furthermore, the inhibition of autophagy in the autophagsome formation stage or apoptosis decreased the release of EV71 viral particles. CONCLUSIONS/SIGNIFICANCE: In conclusion, the results of this study not only revealed novel aspect of the interplay between autophagy and apoptosis in EV71 infection, but also provided a new insight to control EV71 infection.

  20. Autophagy Is an Innate Mechanism Associated with Leprosy Polarization

    Science.gov (United States)

    Andrade, Priscila Ribeiro; Ferreira, Helen; Nery, José Augusto da Costa; Côrte-Real, Suzana; da Silva, Gilberto Marcelo Sperandio; Rosa, Patricia Sammarco; Fabri, Mario; Sarno, Euzenir Nunes

    2017-01-01

    Leprosy is a chronic infectious disease that may present different clinical forms according to the immune response of the host. Levels of IFN-γ are significantly raised in paucibacillary tuberculoid (T-lep) when compared with multibacillary lepromatous (L-lep) patients. IFN-γ primes macrophages for inflammatory activation and induces the autophagy antimicrobial mechanism. The involvement of autophagy in the immune response against Mycobacterium leprae remains unexplored. Here, we demonstrated by different autophagic assays that LC3-positive autophagosomes were predominantly observed in T-lep when compared with L-lep lesions and skin-derived macrophages. Accumulation of the autophagic receptors SQSTM1/p62 and NBR1, expression of lysosomal antimicrobial peptides and colocalization analysis of autolysosomes revealed an impairment of the autophagic flux in L-lep cells, which was restored by IFN-γ or rapamycin treatment. Autophagy PCR array gene-expression analysis revealed a significantly upregulation of autophagy genes (BECN1, GPSM3, ATG14, APOL1, and TPR) in T-lep cells. Furthermore, an upregulation of autophagy genes (TPR, GFI1B and GNAI3) as well as LC3 levels was observed in cells of L-lep patients that developed type 1 reaction (T1R) episodes, an acute inflammatory condition associated with increased IFN-γ levels. Finally, we observed increased BCL2 expression in L-lep cells that could be responsible for the blockage of BECN1-mediated autophagy. In addition, in vitro studies demonstrated that dead, but not live M. leprae can induce autophagy in primary and lineage human monocytes, and that live mycobacteria can reduce the autophagy activation triggered by dead mycobacteria, suggesting that M. leprae may hamper the autophagic machinery as an immune escape mechanism. Together, these results indicate that autophagy is an important innate mechanism associated with the M. leprae control in skin macrophages. PMID:28056107

  1. mTOR signaling and its roles in normal and abnormal brain development.

    Science.gov (United States)

    Takei, Nobuyuki; Nawa, Hiroyuki

    2014-01-01

    Target of rapamycin (TOR) was first identified in yeast as a target molecule of rapamycin, an anti-fugal and immunosuppressant macrolide compound. In mammals, its orthologue is called mammalian TOR (mTOR). mTOR is a serine/threonine kinase that converges different extracellular stimuli, such as nutrients and growth factors, and diverges into several biochemical reactions, including translation, autophagy, transcription, and lipid synthesis among others. These biochemical reactions govern cell growth and cause cells to attain an anabolic state. Thus, the disruption of mTOR signaling is implicated in a wide array of diseases such as cancer, diabetes, and obesity. In the central nervous system, the mTOR signaling cascade is activated by nutrients, neurotrophic factors, and neurotransmitters that enhances protein (and possibly lipid) synthesis and suppresses autophagy. These processes contribute to normal neuronal growth by promoting their differentiation, neurite elongation and branching, and synaptic formation during development. Therefore, disruption of mTOR signaling may cause neuronal degeneration and abnormal neural development. While reduced mTOR signaling is associated with neurodegeneration, excess activation of mTOR signaling causes abnormal development of neurons and glia, leading to brain malformation. In this review, we first introduce the current state of molecular knowledge of mTOR complexes and signaling in general. We then describe mTOR activation in neurons, which leads to translational enhancement, and finally discuss the link between mTOR and normal/abnormal neuronal growth during development.

  2. mTOR signaling and its roles in normal and abnormal brain development.

    Directory of Open Access Journals (Sweden)

    Nobuyuki eTakei

    2014-04-01

    Full Text Available Target of rapamycin (TOR was first identified in yeast as a target molecule of rapamycin, an anti-fugal and immunosuppressant macrolide compound. In mammals, its orthologue is called mTOR (mammalian TOR. mTOR is a serine/threonine kinase that converges different extracellular stimuli, such as nutrients and growth factors, and diverges into several biochemical reactions, including translation, autophagy, transcription, and lipid synthesis among others. These biochemical reactions govern cell growth and cause cells to attain an anabolic state. Thus, the disruption of mTOR signaling is implicated in a wide array of diseases such as cancer, diabetes, and obesity. In the central nervous system (CNS, the mTOR signaling cascade is activated by nutrients, neurotrophic factors, and neurotransmitters that enhances protein (and possibly lipid synthesis and suppresses autophagy. These processes contribute to normal neuronal growth by promoting their differentiation, neurite elongation and branching, and synaptic formation during development. Therefore, disruption of mTOR signaling may cause neuronal degeneration and abnormal neural development. While reduced mTOR signaling is associated with neurodegeneration, excess activation of mTOR signaling causes abnormal development of neurons and glia, leading to brain malformation. In this review, we first introduce the current state of molecular knowledge of mTOR complexes and signaling in general. We then describe mTOR activation in neurons, which leads to translational enhancement, and finally discuss the link between mTOR and normal/abnormal neuronal growth during development.

  3. Chaperone-mediated autophagy is defective in mucolipidosis type IV.

    Science.gov (United States)

    Venugopal, Bhuvarahamurthy; Mesires, Nicholas T; Kennedy, John C; Curcio-Morelli, Cyntia; Laplante, Janice M; Dice, J Fred; Slaugenhaupt, Susan A

    2009-05-01

    Mucolipidosis type IV (MLIV) is a lysosomal storage disorder caused by mutations in the MCOLN1 gene, a member of the transient receptor potential (TRP) cation channel gene family. The encoded protein, transient receptor potential mucolipin-1 (TRPML1), has been localized to lysosomes and late endosomes but the pathogenic mechanism by which loss of TRPML1 leads to abnormal cellular storage and neuronal cell death is still poorly understood. Yeast two-hybrid and co-immunoprecipitation (coIP) experiments identified interactions between TRPML1 and Hsc70 as well as TRPML1 and Hsp40. Hsc70 and Hsp40 are members of a molecular chaperone complex required for protein transport into the lysosome during chaperone-mediated autophagy (CMA). To determine the functional relevance of this interaction, we compared fibroblasts from MLIV patients to those from sex- and age-matched controls and show a defect in CMA in response to serum withdrawal. This defect in CMA was subsequently confirmed in purified lysosomes isolated from control and MLIV fibroblasts. We further show that the amount of lysosomal-associated membrane protein type 2A (LAMP-2A) is reduced in lysosomal membranes of MLIV fibroblasts. As a result of decreased CMA, MLIV fibroblasts have increased levels of oxidized proteins compared to control fibroblasts. We hypothesize that TRPML1 may act as a docking site for intralysosomal Hsc70 (ly-Hsc70) allowing it to more efficiently pull in substrates for CMA. It is also possible that TRPML1 channel activity may be required for CMA. Understanding the role of TRPML1 in CMA will undoubtedly help to characterize the pathogenesis of MLIV.

  4. The role of chaperone-mediated autophagy in huntingtin degradation.

    Directory of Open Access Journals (Sweden)

    Lin Qi

    Full Text Available Huntington Disease (HD is caused by an abnormal expansion of polyQ tract in the protein named huntingtin (Htt. HD pathology is featured by accumulation and aggregation of mutant Htt in striatal and cortical neurons. Aberrant Htt degradation is implicated in HD pathogenesis. The aim of this study was to investigate the regulatory role of chaperone-mediated autophagy (CMA components, heat shock protein cognate 70 (Hsc70 and lysosome-associated protein 2A (LAMP-2A in degradation of Htt fragment 1-552aa (Htt-552. A cell model of HD was produced by overexpression of Htt-552 with adenovirus. The involvement of CMA components in degradation of Htt-552 was determined with over-expression or silencing of Hsc70 and LAMP-2A. The results confirmed previous reports that both macroautophagy and CMA were involved in degradation of Htt-552. Changing the levels of CMA-related proteins affected the accumulation of Htt-552. The lysosomal binding and luminal transport of Htt-552 was demonstrated by incubation of Htt-552 with isolated lysosomes. Expansion of the polyQ tract in Htt-552 impaired its uptake and degradation by lysosomes. Mutation of putative KFERQ motif in wild-type Htt-552 interfered with interactions between Htt-552 and Hsc70. Endogenous Hsc70 and LAMP-2A interacted with exogenously expressed Htt-552. Modulating the levels of CMA related proteins degraded endogenous full-length Htt. These studies suggest that Hsc70 and LAMP-2A through CMA play a role in the clearance of Htt and suggest a novel strategy to target the degradation of mutant Htt.

  5. Autophagy and immunity – insights from human herpesviruses

    Directory of Open Access Journals (Sweden)

    Luke eWilliams

    2012-07-01

    Full Text Available The herpesviruses are a family of double-stranded DNA viruses that infect a large variety of organisms. Having co-evolved with their hosts over millennia, herpesviruses have developed a large repertoire of mechanisms to manipulate normal cellular processes. Given the important role of autophagy in cells, this pathway is a target for manipulation by herpesviruses. Here we describe the ways that human herpesviruses interact and interfere with the cellular autophagy machinery in order to escape innate and adaptive immunity. Recent research on the human herpesvirus Epstein-Barr Virus (EBV suggesting that localisation within the nucleus can shelter viral proteins from autophagy is also discussed.

  6. Alternative autophagy, brefeldin A and viral trafficking pathways

    Science.gov (United States)

    Grose, Charles; Klionsky, Daniel J.

    2016-01-01

    ABSTRACT Two topics that have attracted recent attention in the field of autophagy concern the source of the membrane that is used to form the autophagosome during macroautophagy and the role of noncanonical autophagic pathways. The 2 topics may converge when considering the intersection of autophagy with viral infection. We suggest that noncanonical autophagy, which is sensitive to treatment with brefeldin A, may converge with the infectious cycles of certain DNA and RNA viruses that utilize membrane from the ER and cis-Golgi. PMID:27439673

  7. Role of autophagy in acute myeloid leukemia therapy

    Institute of Scientific and Technical Information of China (English)

    Su-Ping Zhang; Yu-Na Niu; Na Yuan; Ai-Hong Zhang; Dan Chao; Qiu-Ping Xu; Li-Jun Wang

    2013-01-01

    Despite its dual role in determining cell fate in a wide array of solid cancer cell lines,autophagy has been robustly shown to suppress or kill acute myeloid leukemia cells via degradation of the oncogenic fusion protein that drives leukemogenesis.However,autophagy also induces the demise of acute leukemia cells that do not express the known fusion protein,though the molecular mechanism remains elusive.Nevertheless,since it can induce cooperation with apoptosis and differentiation in response to autophagic signals,autophagy can be manipulated for a better therapy on acute myeloid leukemia.

  8. The protective roles of autophagy in ischemic preconditioning

    Institute of Scientific and Technical Information of China (English)

    Wen-jun YAN; Hai-long DONG; Li-ze XIONG

    2013-01-01

    Autophagy,a process for the degradation of protein aggregates and dysfunctional organelles,is required for cellular homeostasis and cell survival in response to stress and is implicated in endogenous protection.Ischemic preconditioning is a brief and nonlethal episode of ischemia,confers protection against subsequent ischemia-repenfusion through the up-regulation of endogenous protective mechanisms.Emerging evidence shows that autophagy is associated with the protective effect of ischemic preconditioning.This review summarizes recent progress in research on the functions and regulations of the autophagy pathway in preconditioning-induced protection and cellular survival.

  9. The bacterial pathogen-ubiquitin interface: lessons learned from Shigella.

    Science.gov (United States)

    Tanner, Kaitlyn; Brzovic, Peter; Rohde, John R

    2015-01-01

    Shigella species are the aetiological agents of shigellosis, a severe diarrhoeal disease that is a significant cause of morbidity and mortality worldwide. Shigellosis causes massive colonic destruction, high fever and bloody diarrhoea. Shigella pathogenesis is tightly linked to the ability of the bacterium to invade and replicate intracellularly within the colonic epithelium. Shigella uses a type 3 secretion system to deliver its effector proteins into the cytosol of infected cells. Among the repertoire of Shigella effectors, many are known to target components of the actin cytoskeleton to promote bacterial entry. An emerging alternate theme for effector function is the targeting of the host ubiquitin system. Ubiquitination is a post-translational modification restricted to eukaryotes and is involved in many essential host processes. By virtue of sheer number of ubiquitin-modulating effector proteins, it is clear that Shigella has invested heavily into subversion of the ubiquitin system. Understanding these host-pathogen interactions will inform us about the strategies used by successful pathogens and may also provide avenues for novel antimicrobial strategies.

  10. Breaking It Down: The Ubiquitin Proteasome System in Neuronal Morphogenesis

    Directory of Open Access Journals (Sweden)

    Andrew M. Hamilton

    2013-01-01

    Full Text Available The ubiquitin-proteasome system (UPS is most widely known for its role in intracellular protein degradation; however, in the decades since its discovery, ubiquitination has been associated with the regulation of a wide variety of cellular processes. The addition of ubiquitin tags, either as single moieties or as polyubiquitin chains, has been shown not only to mediate degradation by the proteasome and the lysosome, but also to modulate protein function, localization, and endocytosis. The UPS plays a particularly important role in neurons, where local synthesis and degradation work to balance synaptic protein levels at synapses distant from the cell body. In recent years, the UPS has come under increasing scrutiny in neurons, as elements of the UPS have been found to regulate such diverse neuronal functions as synaptic strength, homeostatic plasticity, axon guidance, and neurite outgrowth. Here we focus on recent advances detailing the roles of the UPS in regulating the morphogenesis of axons, dendrites, and dendritic spines, with an emphasis on E3 ubiquitin ligases and their identified regulatory targets.

  11. How the ubiquitin proteasome system regulates the regulators of transcription.

    Science.gov (United States)

    Ee, Gary; Lehming, Norbert

    2012-01-01

    The ubiquitin proteasome system plays an important role in transcription. Monoubiquitination of activators is believed to aid their function, while the 26S proteasomal degradation of repressors is believed to restrict their function. What remains controversial is the question of whether the degradation of activators aids or restricts their function.

  12. Ubiquitin chain topology and its impact on plant cell signalling

    Directory of Open Access Journals (Sweden)

    Charlotte Kirsten Walsh

    2014-04-01

    Full Text Available Ubiquitin is a peptide modifier able to form polymers of varying length and linkage as part of a powerful signalling system. Perhaps the best-known aspect of this protein’s function is as the driver of targeted protein degradation through the Ubiquitin Proteasome System (UPS. Through the formation of lysine 48-linked polyubiquitin chains, it is able to direct the degradation of tagged proteins by the 26S proteasome, indirectly controlling many processes within the cell. However, recent research has indicated that ubiquitin performs a multitude of other roles within the cell beyond protein degradation. It is able to form 6 other ‘atypical’ linkages though lysine residues at positions 6, 11, 27, 29, 33 and 63. These atypical chains perform a range of diverse functions, including the regulation of iron uptake in response to perceived deficiency, repair of double stranded breaks in the DNA, and regulation of the auxin response through the non-proteasomal degradation of auxin efflux carrier protein PIN1. This review explores the role ubiquitin chain topology plays in plant cellular function. We aim to highlight the importance of these varying functions and the future challenges to be encountered within this field.

  13. Regulation of autophagy by some natural products as a potential therapeutic strategy for cardiovascular disorders.

    Science.gov (United States)

    Hashemzaei, Mahmoud; Entezari Heravi, Reza; Rezaee, Ramin; Roohbakhsh, Ali; Karimi, Gholamreza

    2017-02-24

    Autophagy is a lysosomal degradation process through which long-lived and misfolded proteins and organelles are sequestered, degraded by lysosomes, and recycled. Autophagy is an essential part of cardiomyocyte homeostasis and increases the survival of cells following cellular stress and starvation. Recent studies made clear that dysregulation of autophagy in the cardiovascular system leads to heart hypertrophy and failure. In this manner, autophagy seems to be an attractive target in the new treatment of cardiovascular diseases. Although limited activation of autophagy is generally considered to be cardioprotective, excessive autophagy leads to cell death and cardiac atrophy. Natural products such as resveratrol, berberine, and curcumin that are present in our diet, can trigger autophagy via canonical (Beclin-1-dependent) and non-canonical (Beclin-1-independent) pathways. The autophagy-modifying capacity of these compounds should be taken into consideration for designing novel therapeutic agents. This review focuses on the role of autophagy in the cardioprotective effects of these compounds.

  14. Spermidine and resveratrol induce autophagy by distinct pathways converging on the acetylproteome.

    Science.gov (United States)

    Morselli, Eugenia; Mariño, Guillermo; Bennetzen, Martin V; Eisenberg, Tobias; Megalou, Evgenia; Schroeder, Sabrina; Cabrera, Sandra; Bénit, Paule; Rustin, Pierre; Criollo, Alfredo; Kepp, Oliver; Galluzzi, Lorenzo; Shen, Shensi; Malik, Shoaib Ahmad; Maiuri, Maria Chiara; Horio, Yoshiyuki; López-Otín, Carlos; Andersen, Jens S; Tavernarakis, Nektarios; Madeo, Frank; Kroemer, Guido

    2011-02-21

    Autophagy protects organelles, cells, and organisms against several stress conditions. Induction of autophagy by resveratrol requires the nicotinamide adenine dinucleotide-dependent deacetylase sirtuin 1 (SIRT1). In this paper, we show that the acetylase inhibitor spermidine stimulates autophagy independent of SIRT1 in human and yeast cells as well as in nematodes. Although resveratrol and spermidine ignite autophagy through distinct mechanisms, these compounds stimulate convergent pathways that culminate in concordant modifications of the acetylproteome. Both agents favor convergent deacetylation and acetylation reactions in the cytosol and in the nucleus, respectively. Both resveratrol and spermidine were able to induce autophagy in cytoplasts (enucleated cells). Moreover, a cytoplasm-restricted mutant of SIRT1 could stimulate autophagy, suggesting that cytoplasmic deacetylation reactions dictate the autophagic cascade. At doses at which neither resveratrol nor spermidine stimulated autophagy alone, these agents synergistically induced autophagy. Altogether, these data underscore the importance of an autophagy regulatory network of antagonistic deacetylases and acetylases that can be pharmacologically manipulated.

  15. ER stress, autophagy, and RNA viruses

    Directory of Open Access Journals (Sweden)

    Jia-Rong eJheng

    2014-08-01

    Full Text Available Endoplasmic reticulum (ER stress is a general term for representing the pathway by which various stimuli affect ER functions. ER stress induces the evolutionarily conserved signaling pathways, called the unfolded protein response (UPR, which compromises the stimulus and then determines whether the cell survives or dies. In recent years, ongoing research has suggested that these pathways may be linked to the autophagic response, which plays a key role in the cell’s response to various stressors. Autophagy performs a self-digestion function, and its activation protects cells against certain pathogens. However, the link between the UPR and autophagy may be more complicated. These two systems may act dependently, or the induction of one system may interfere with the other. Experimental studies have found that different viruses modulate these mechanisms to allow them to escape the host immune response or, worse, to exploit the host’s defense to their advantage; thus, this topic is a critical area in antiviral research. In this review, we summarize the current knowledge about how RNA viruses, including influenza virus, poliovirus, coxsackievirus, enterovirus 71, Japanese encephalitis virus, hepatitis C virus, and dengue virus, regulate these processes. We also discuss recent discoveries and how these will produce novel strategies for antiviral treatment.

  16. Zymophagy: Selective Autophagy of Secretory Granules

    Directory of Open Access Journals (Sweden)

    Maria I. Vaccaro

    2012-01-01

    Full Text Available Timing is everything. That's especially true when it comes to the activation of enzymes created by the pancreas to break down food. Pancreatic enzymes are packed in secretory granules as precursor molecules called zymogens. In physiological conditions, those zymogens are activated only when they reach the gut, where they get to work releasing and distributing nutrients that we need to survive. If this process fails and the enzymes are prematurely activated within the pancreatic cell, before they are released from the gland, they break down the pancreas itself causing acute pancreatitis. This is a painful disease that ranges from a mild and autolimited process to a severe and lethal condition. Recently, we demonstrated that the pancreatic acinar cell is able to switch on a refined mechanism that could explain the autolimited form of the disease. This is a novel selective form of autophagy named zymophagy, a cellular process to specifically detect and degrade secretory granules containing activated enzymes before they can digest the organ. In this work, we revise the molecules and mechanisms that mediate zymophagy, a selective autophagy of secretory granules.

  17. The Role of Ubiquitination in TWEAK-Stimulated Signaling.

    Science.gov (United States)

    Vucic, Domagoj

    2013-12-19

    Tumor necrosis factor superfamily ligands and receptors are responsible for development, immunity, and homeostasis of metazoan organisms. Thus, it is not surprising that signals emanating from these receptors are tightly regulated. Binding of TNF-related weak inducer of apoptosis (TWEAK) to its cognate receptor, FN14, triggers the assembly of receptor-associated signaling complex, which allows the activation of canonical and non-canonical nuclear factor kappa B (NF-κB) as well as mitogen-activated protein kinase signaling pathways. Ubiquitin ligases cellular inhibitor of apoptosis 1 and 2 (c-IAP1 and 2) and adaptor proteins TNFR-associated factors 2 and 3 (TRAF2 and TRAF3) are crucial for the regulation of TWEAK signaling as they facilitate the recruitment of distal signaling components including IKK and linear ubiquitin chain assembly complex complexes. At the same time c-IAP1/2, together with TRAF2 and TRAF3, promote constitutive ubiquitination and proteasomal degradation of NF-κB inducing kinase (NIK) - a kinase with critical role in the activation of non-canonical NF-κB signaling. While c-IAP1/2 mediated ubiquitination allows the activation of TWEAK-stimulated canonical NF-κB signaling, these E3 ligases are negative regulators of non-canonical signaling. TWEAK stimulation prompts the recruitment of c-IAP1/2 as well as TRAF2 and TRAF3 to the FN14 signaling complex leading to c-IAP1/2 autoubiquitination and degradation, which stabilizes NIK and allows subsequent phosphorylation of IKKα and partial proteasomal processing of p100 to activate gene expression. Recent studies have revealed that the spatio-temporal pattern of TWEAK-stimulated ubiquitination is a carefully orchestrated process involving several substrates that are modified by different ubiquitin linkages. Understanding the significance of ubiquitination for TWEAK signaling is important for the overall understanding of TWEAK biology and for the design of therapeutics that can be used in the

  18. mir-30d Regulates multiple genes in the autophagy pathway and impairs autophagy process in human cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaojun [Ovarian Cancer Research Center and Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of General Surgery, Gansu Provincial Hospital, Lanzhou, Gansu 710000 (China); Zhong, Xiaomin [Ovarian Cancer Research Center and Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Obstetrics and Gynecology Hospital, Fudan University, Shanghai 200011 (China); Tanyi, Janos L.; Shen, Jianfeng [Ovarian Cancer Research Center and Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, PA 19104 (United States); Xu, Congjian [Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Obstetrics and Gynecology Hospital, Fudan University, Shanghai 200011 (China); Gao, Peng [Department of General Surgery, Gansu Provincial Hospital, Lanzhou, Gansu 710000 (China); Zheng, Tim M. [Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104 (United States); DeMichele, Angela [Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104 (United States); Zhang, Lin, E-mail: linzhang@mail.med.upenn.edu [Ovarian Cancer Research Center and Department of Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2013-02-15

    Highlights: ► Gene set enrichment analysis indicated mir-30d might regulate the autophagy pathway. ► mir-30d represses the expression of BECN1, BNIP3L, ATG12, ATG5 and ATG2. ► BECN1, BNIP3L, ATG12, ATG5 and ATG2 are direct targets of mir-30d. ► mir-30d inhibits autophagosome formation and LC3B-I conversion to LC3B-II. ► mir-30d regulates the autophagy process. -- Abstract: In human epithelial cancers, the microRNA (miRNA) mir-30d is amplified with high frequency and serves as a critical oncomir by regulating metastasis, apoptosis, proliferation, and differentiation. Autophagy, a degradation pathway for long-lived protein and organelles, regulates the survival and death of many cell types. Increasing evidence suggests that autophagy plays an important function in epithelial tumor initiation and progression. Using a combined bioinformatics approach, gene set enrichment analysis, and miRNA target prediction, we found that mir-30d might regulate multiple genes in the autophagy pathway including BECN1, BNIP3L, ATG12, ATG5, and ATG2. Our further functional experiments demonstrated that the expression of these core proteins in the autophagy pathway was directly suppressed by mir-30d in cancer cells. Finally, we showed that mir-30d regulated the autophagy process by inhibiting autophagosome formation and LC3B-I conversion to LC3B-II. Taken together, our results provide evidence that the oncomir mir-30d impairs the autophagy process by targeting multiple genes in the autophagy pathway. This result will contribute to understanding the molecular mechanism of mir-30d in tumorigenesis and developing novel cancer therapy strategy.

  19. Dihydroartemisinin potentiates the anticancer effect of cisplatin via mTOR inhibition in cisplatin-resistant ovarian cancer cells: involvement of apoptosis and autophagy

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xue [Department of Gynecology and Obstetrics, The First Affiliated Hospital of Harbin Medical University, Harbin 150001 (China); Li, Ling [Department of Brain Cognition Computing Lab, University of Kent, Kent CT2 7NZ (United Kingdom); Jiang, Hong; Jiang, Keping; Jin, Ye [Department of Gynecology and Obstetrics, The First Affiliated Hospital of Harbin Medical University, Harbin 150001 (China); Zheng, Jianhua, E-mail: zhengjianhua1115@126.com [Department of Gynecology and Obstetrics, The First Affiliated Hospital of Harbin Medical University, Harbin 150001 (China)

    2014-02-14

    Highlights: • Phosphorylation of mTOR is abnormal activation in SKOV3/DDP ovarian cancer cells. • Downregulation of mTOR by DHA helps to sensitize the SKOV3/DDP cells to chemotherapy. • DHA has the potential of induce autophagy in cancer cells. - Abstract: Dihydroartemisinin (DHA) exhibits anticancer activity in tumor cells but its mechanism of action is unclear. Cisplatin (DDP) is currently the best known chemotherapeutic available for ovarian cancer. However, tumors return de novo with acquired resistance over time. Mammalian target of rapamycin (mTOR) is an important kinase that regulates cell apoptosis and autophagy, and its dysregulation has been observed in chemoresistant human cancers. Here, we show that compared with control ovarian cancer cells (SKOV3), mTOR phosphorylation was abnormally activated in cisplatin-resistant ovarian cancer cells (SKOV3/DDP) following cisplatin monotherapy. Treatment with cisplatin combined with DHA could enhance cisplatin-induced proliferation inhibition in SKOV3/DDP cells. This mechanism is at least partially due to DHA deactivation of mTOR kinase and promotion of apoptosis. Although autophagy was also induced by DHA, the reduced cell death was not found by suppressing autophagic flux by Bafilomycin A1 (BAF). Taken together, we conclude that inhibition of cisplatin-induced mTOR activation is one of the main mechanisms by which DHA dramatically promotes its anticancer effect in cisplatin-resistant ovarian cancer cells.

  20. Ubiquitin trafficking to the lysosome: keeping the house tidy and getting rid of unwanted guests.

    Science.gov (United States)

    Purdy, Georgiana E; Russell, David G

    2007-01-01

    Bacterial killing by autophagic delivery to the lysosomal compartment has been shown for Mycobacteria, Streptococcus, Shigella, Legionella and Salmonella, indicating an important role for this conserved trafficking pathway for the control of intracellular bacterial pathogens.(1-5) In a recent study we found that solubilized lysosomes isolated from bone marrow-derived macrophages had potent antibacterial properties against M. tuberculosis and M. smegmatis that were associated with ubiquitin and ubiquitin-derived peptides. We propose that ubiquitinated proteins are delivered to the lysosomal compartment, where degradation by lysosomal proteinases generates ubiquitin-derived peptides with antimycobacterial properties. This surprising finding provokes a number of questions regarding the nature and trafficking of ubiquitin and ubiquitin-modified proteins in mammalian cells. We discuss the possible role(s) that the multivesicular body (MVB), the late endosome and the autophagosome may play in trafficking of ubiquitinated proteins to the lysosome.

  1. [Ubiquitous Ribonucleic Acid:miRNA is the Ubiquitin of RNA].

    Science.gov (United States)

    Zheng, Xiao-fei

    2015-10-01

    Small RNAs, especially microRNAs (miRNAs),widely exist in eukaryotic cells, with their main functions being regulating gene expression and function of target molecules through the degradation of cellular target RNAs by the ribonuclease-based system. Ubiquitins and ubiquitin-like proteins are polypeptides that exist in most eukaryotic cells, and their main function is almost to regulate protein level through the degradation of cellular proteins by ubiquitin proteasome system. Small RNAs, including miRNAs,and ubiquitins or ubiquitin-like proteins have similarities in many aspects although small RNAs and ubiquitin or ubiquitin-like proteins interact different substrates respectively. Therefore, miRNAs can be defined as ubiquitra (ubiquitous ribonucleic acid, ubiquitra or uRNA), and the other small RNAs can be defined as ubiquitra-like RNA or uRNA-like RNA. The concept of ubiquitra may be applied for explaining the biological essence of small RNAs diversity.

  2. Communication and abnormal behaviour.

    Science.gov (United States)

    Crown, S

    1979-01-01

    In this paper the similarities between normal and abnormal behaviour are emphasized and selected aspects of communication, normal and aberrant, between persons are explored. Communication in a social system may be verbal or non-verbal: one person's actions cause a response in another person. This response may be cognitive, behavioural or physiological. Communication may be approached through the individual, the social situation or social interaction. Psychoanalysis approaches the individual in terms of the coded communications of psychoneurotic symptoms or psychotic behaviour; the humanist-existential approach is concerned more with emotional expression. Both approaches emphasize the development of individual identity. The interaction between persons and their social background is stressed. Relevant are sociological concepts such as illness behaviour, stigma, labelling, institutionalization and compliance. Two approaches to social interactions are considered: the gamesplaying metaphor, e.g. back pain as a psychosocial manipulation--the 'pain game'; and the 'spiral of reciprocal perspectives' which emphasizes the interactional complexities of social perceptions. Communicatory aspects of psychological treatments are noted: learning a particular metaphor such as 'resolution' of the problem (psychotherapy), learning more 'rewarding' behaviour (learning theory) or learning authenticity or self-actualization (humanist-existential).

  3. Interactions between Autophagy and Bacterial Toxins: Targets for Therapy?

    Directory of Open Access Journals (Sweden)

    Jacques Mathieu

    2015-08-01

    Full Text Available Autophagy is a physiological process involved in defense mechanisms for clearing intracellular bacteria. The autophagic pathway is finely regulated and bacterial toxins interact with this process in a complex manner. Bacterial toxins also interact significantly with many biochemical processes. Evaluations of the effects of bacterial toxins, such as endotoxins, pore-forming toxins and adenylate cyclases, on autophagy could support the development of new strategies for counteracting bacterial pathogenicity. Treatment strategies could focus on drugs that enhance autophagic processes to improve the clearance of intracellular bacteria. However, further in vivo studies are required to decipher the upregulation of autophagy and potential side effects limiting such approaches. The capacity of autophagy activation strategies to improve the outcome of antibiotic treatment should be investigated in the future.

  4. A role for TOR complex 2 signaling in promoting autophagy.

    Science.gov (United States)

    Vlahakis, Ariadne; Powers, Ted

    2014-01-01

    The conserved target of rapamycin (TOR) kinase is a central regulator of cell growth in response to nutrient availability. TOR forms 2 structurally and functionally distinct complexes, TORC1 and TORC2, and negatively regulates autophagy via TORC1. Here we demonstrate TOR also operates independently through the TORC2 signaling pathway to promote autophagy upon amino acid limitation. Under these conditions, TORC2, through its downstream target kinase Ypk1, inhibits the Ca(2+)- and Cmd1/calmodulin-dependent phosphatase, calcineurin, to enable the activation of the amino acid-sensing EIF2S1/eIF2α kinase, Gcn2, and promote autophagy. Thus TORC2 signaling regulates autophagy in a pathway distinct from TORC1 to provide a tunable response to the cellular metabolic state.

  5. The emerging role of acid sphingomyelinase in autophagy.

    Science.gov (United States)

    Perrotta, Cristiana; Cervia, Davide; De Palma, Clara; Assi, Emma; Pellegrino, Paolo; Bassi, Maria Teresa; Clementi, Emilio

    2015-05-01

    Autophagy, the main intracellular process of cytoplasmic material degradation, is involved in cell survival and death. Autophagy is regulated at various levels and novel modulators of its function are being continuously identified. An intriguing recent observation is that among these modulators is the sphingolipid metabolising enzyme, Acid Sphingomyelinase (A-SMase), already known to play a fundamental role in apoptotic cell death participating in several pathophysiological conditions. In this review we analyse and discuss the relationship between autophagy and A-SMase describing how A-SMase may regulate it and defining, for the first time, the existence of an A-SMase-autophagy axis. The imbalance of this axis plays a role in cancer, nervous system, cardiovascular, and hepatic disorders.

  6. Autophagy-modulating aminosteroids isolated from the sponge Cliona celata

    NARCIS (Netherlands)

    R.A. Keyzers; J. Daoust; M.T. Davies-Coleman; R. van Soest; A. Balgi; E. Donohue; M. Roberge; R.J. Andersen

    2008-01-01

    Clionamines A−D (1−4), new aminosteroids that modulate autophagy, have been isolated from South African specimens of the sponge Cliona celata. Clionamine D (4) has an unprecedented spiro bislactone side chain.

  7. Monitoring of autophagy is complicated--salinomycin as an example.

    Science.gov (United States)

    Jangamreddy, Jaganmohan Reddy; Panigrahi, Soumya; Łos, Marek J

    2015-03-01

    Monitoring of autophagy is challenging because of its multiple steps and lack of single befitting technique for a complete mechanistic understanding, which makes the task complicated. Here, we evaluate the functionality of autophagy triggered by salinomycin (anti-cancer stem cell agent) using flow cytometry and advanced microscopy. We show that salinomycin does induce functional autophagy at lower concentrations and such a dose is cell type-dependent. For example, PC3 cells show active autophagic flux at 10 μM concentration of salinomycin while murine embryonic fibroblasts already show an inhibition of flux at such doses. A higher concentration of salinomycin (i.e. 30 μM) inhibits autophagic flux in both cell types. The data confirms our previous findings that salinomycin is an inducer of autophagy, whereas autophagic flux inhibition is a secondary response.

  8. Role of autophagy in liver physiology and pathophysiology

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Autophagy is a highly conserved intracellular degradation pathway by which bulk cytoplasm and superfluous or damaged organelles are enveloped by double membrane structures termed autophagosomes. The autophago-somes then fuse with lysosomes for degradation of their contents, and the resulting amino acids can then recycle back to the cytosol. Autophagy is normally activated in response to nutrient deprivation and other stressors and occurs in all eukaryotes. In addition to maintaining energy and nutrient balance in the liver, it is now clear that autophagy plays a role in liver protein aggregates related diseases, hepatocyte cell death, steatohepatitis, hepatitis virus infection and hepatocellular carcinoma. In this review, I discuss the recent findings of autophagy with a focus on its role in liver pathophysiology.

  9. Heat shock response and autophagy--cooperation and control.

    Science.gov (United States)

    Dokladny, Karol; Myers, Orrin B; Moseley, Pope L

    2015-01-01

    Protein quality control (proteostasis) depends on constant protein degradation and resynthesis, and is essential for proper homeostasis in systems from single cells to whole organisms. Cells possess several mechanisms and processes to maintain proteostasis. At one end of the spectrum, the heat shock proteins modulate protein folding and repair. At the other end, the proteasome and autophagy as well as other lysosome-dependent systems, function in the degradation of dysfunctional proteins. In this review, we examine how these systems interact to maintain proteostasis. Both the direct cellular data on heat shock control over autophagy and the time course of exercise-associated changes in humans support the model that heat shock response and autophagy are tightly linked. Studying the links between exercise stress and molecular control of proteostasis provides evidence that the heat shock response and autophagy coordinate and undergo sequential activation and downregulation, and that this is essential for proper proteostasis in eukaryotic systems.

  10. Ultrastructure of autophagy in plant cells: a review.

    Science.gov (United States)

    van Doorn, Wouter G; Papini, Alessio

    2013-12-01

    Just as with yeasts and animal cells, plant cells show several types of autophagy. Microautophagy is the uptake of cellular constituents by the vacuolar membrane. Although microautophagy seems frequent in plants it is not yet fully proven to occur. Macroautophagy occurs farther away from the vacuole. In plants it is performed by autolysosomes, which are considerably different from the autophagosomes found in yeasts and animal cells, as in plants these organelles contain hydrolases from the onset of their formation. Another type of autophagy in plant cells (called mega-autophagy or mega-autolysis) is the massive degradation of the cell at the end of one type of programmed cell death (PCD). Furthermore, evidence has been found for autophagy during degradation of specific proteins, and during the internal degeneration of chloroplasts. This paper gives a brief overview of the present knowledge on the ultrastructure of autophagic processes in plants.

  11. Interactions between Autophagy and Bacterial Toxins: Targets for Therapy?

    Science.gov (United States)

    Mathieu, Jacques

    2015-08-04

    Autophagy is a physiological process involved in defense mechanisms for clearing intracellular bacteria. The autophagic pathway is finely regulated and bacterial toxins interact with this process in a complex manner. Bacterial toxins also interact significantly with many biochemical processes. Evaluations of the effects of bacterial toxins, such as endotoxins, pore-forming toxins and adenylate cyclases, on autophagy could support the development of new strategies for counteracting bacterial pathogenicity. Treatment strategies could focus on drugs that enhance autophagic processes to improve the clearance of intracellular bacteria. However, further in vivo studies are required to decipher the upregulation of autophagy and potential side effects limiting such approaches. The capacity of autophagy activation strategies to improve the outcome of antibiotic treatment should be investigated in the future.

  12. Basal autophagy is required for the efficient catabolism of sialyloligosaccharides.

    Science.gov (United States)

    Seino, Junichi; Wang, Li; Harada, Yoichiro; Huang, Chengcheng; Ishii, Kumiko; Mizushima, Noboru; Suzuki, Tadashi

    2013-09-13

    Macroautophagy is an essential, homeostatic process involving degradation of a cell's own components; it plays a role in catabolizing cellular components, such as protein or lipids, and damaged or excess organelles. Here, we show that in Atg5(-/-) cells, sialyloligosaccharides specifically accumulated in the cytosol. Accumulation of these glycans was observed under non-starved conditions, suggesting that non-induced, basal autophagy is essential for their catabolism. Interestingly, once accumulated in the cytosol, sialylglycans cannot be efficiently catabolized by resumption of the autophagic process, suggesting that functional autophagy is important for preventing sialyloligosaccharides from accumulating in the cytosol. Moreover, knockdown of sialin, a lysosomal transporter of sialic acids, resulted in a significant reduction of sialyloligosaccharides, implying that autophagy affects the substrate specificity of this transporter. This study thus provides a surprising link between basal autophagy and catabolism of N-linked glycans.

  13. Detection of Autophagy in Caenorhabditis elegans Using GFP::LGG-1 as an Autophagy Marker.

    Science.gov (United States)

    Palmisano, Nicholas J; Meléndez, Alicia

    2016-01-04

    In yeast and mammalian cells, the autophagy protein Atg8/LC3 (microtubule-associated proteins 1A/1B light chain 3B encoded by MAP1LC3B) has been the marker of choice to detect double-membraned autophagosomes that are produced during the process of autophagy. A lipid-conjugated form of Atg8/LC3B is localized to the inner and outer membrane of the early-forming structure known as the phagophore. During maturation of autophagosomes, Atg8/LC3 bound to the inner autophagosome membrane remains in situ as the autophagosomes fuse with lysosomes. The nematode Caenorhabditis elegans is thought to conduct a similar process, meaning that tagging the nematode ortholog of Atg8/LC3-known as LGG-1-with a fluorophore has become a widely accepted method to visualize autophagosomes. Under normal growth conditions, GFP-modified LGG-1 displays a diffuse expression pattern throughout a variety of tissues, whereas, when under conditions that induce autophagy, the GFP::LGG-1 tag labels positive punctate structures, and its overall level of expression increases. Here, we present a protocol for using fluorescent reporters of LGG-1 coupled to GFP to monitor autophagosomes in vivo. We also discuss the use of alternative fluorescent markers and the possible utility of the LGG-1 paralog LGG-2.

  14. Ubiquitination independent of E1 and E2 enzymes by bacterial effectors.

    Science.gov (United States)

    Qiu, Jiazhang; Sheedlo, Michael J; Yu, Kaiwen; Tan, Yunhao; Nakayasu, Ernesto S; Das, Chittaranjan; Liu, Xiaoyun; Luo, Zhao-Qing

    2016-05-01

    Signalling by ubiquitination regulates virtually every cellular process in eukaryotes. Covalent attachment of ubiquitin to a substrate is catalysed by the E1, E2 and E3 three-enzyme cascade, which links the carboxy terminus of ubiquitin to the ε-amino group of, in most cases, a lysine of the substrate via an isopeptide bond. Given the essential roles of ubiquitination in the regulation of the immune system, it is not surprising that the ubiquitination network is a common target for diverse infectious agents. For example, many bacterial pathogens exploit ubiquitin signalling using virulence factors that function as E3 ligases, deubiquitinases or as enzymes that directly attack ubiquitin. The bacterial pathogen Legionella pneumophila utilizes approximately 300 effectors that modulate diverse host processes to create a permissive niche for its replication in phagocytes. Here we demonstrate that members of the SidE effector family of L. pneumophila ubiquitinate multiple Rab small GTPases associated with the endoplasmic reticulum. Moreover, we show that these proteins are capable of catalysing ubiquitination without the need for the E1 and E2 enzymes. A putative mono-ADP-ribosyltransferase motif critical for the ubiquitination activity is also essential for the role of the SidE family in intracellular bacterial replication in a protozoan host. The E1/E2-independent ubiquitination catalysed by these enzymes is energized by nicotinamide adenine dinucleotide, which activates ubiquitin by the formation of ADP-ribosylated ubiquitin. These results establish that ubiquitination can be catalysed by a single enzyme, the activity of which does not require ATP.

  15. Ubiquitin vinyl methyl ester binding orients the misaligned active site of the ubiquitin hydrolase UCHL1 into productive conformation

    Energy Technology Data Exchange (ETDEWEB)

    Boudreaux, David A.; Maiti, Tushar K.; Davies, Christopher W.; Das, Chittaranjan (Purdue)

    2010-07-06

    Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) is a Parkinson disease-associated, putative cysteine protease found abundantly and selectively expressed in neurons. The crystal structure of apo UCHL1 showed that the active-site residues are not aligned in a canonical form, with the nucleophilic cysteine being 7.7 {angstrom} from the general base histidine, an arrangement consistent with an inactive form of the enzyme. Here we report the crystal structures of the wild type and two Parkinson disease-associated variants of the enzyme, S18Y and I93M, bound to a ubiquitin-based suicide substrate, ubiquitin vinyl methyl ester. These structures reveal that ubiquitin vinyl methyl ester binds primarily at two sites on the enzyme, with its carboxy terminus at the active site and with its amino-terminal {beta}-hairpin at the distal site - a surface-exposed hydrophobic crevice 17 {angstrom} away from the active site. Binding at the distal site initiates a cascade of side-chain movements in the enzyme that starts at a highly conserved, surface-exposed phenylalanine and is relayed to the active site resulting in the reorientation and proximal placement of the general base within 4 {angstrom} of the catalytic cysteine, an arrangement found in productive cysteine proteases. Mutation of the distal-site, surface-exposed phenylalanine to alanine reduces ubiquitin binding and severely impairs the catalytic activity of the enzyme. These results suggest that the activity of UCHL1 may be regulated by its own substrate.

  16. Glucocorticoids induce autophagy in rat bone marrow mesenchymal stem cells

    DEFF Research Database (Denmark)

    Wang, L.; Fan, J.; Lin, Y. S.;

    2015-01-01

    and their responses to diverse stimuli, however, the role of autophagy in glucocorticoidinduced damage to bone marrow mesenchymal stem cells (BMSCs) remains unclear. The current study confirmed that glucocorticoid administration impaired the proliferation of BMSCs. Transmission electron microscopy......Glucocorticoidinduced osteoporosis (GIOP) is a widespread clinical complication following glucocorticoid therapy. This irreversible damage to boneforming and resorbing cells is essential in the pathogenesis of osteoporosis. Autophagy is a physiological process involved in the regulation of cells...

  17. Autophagy Deficiency Promotes β-Lactam Production in Penicillium chrysogenum

    OpenAIRE

    Bartoszewska, Magdalena; Kiel, Jan A.K.W.; Bovenberg, Roel A. L.; Veenhuis, Marten; van der Klei, Ida J.

    2011-01-01

    We have investigated the significance of autophagy in the production of the β-lactam antibiotic penicillin (PEN) by the filamentous fungus Penicillium chrysogenum. In this fungus PEN production is compartmentalized in the cytosol and in peroxisomes. We demonstrate that under PEN-producing conditions significant amounts of cytosolic and peroxisomal proteins are degraded via autophagy. Morphological analysis, based on electron and fluorescence microscopy, revealed that this phenomenon might con...

  18. ROLE OF AUTOPHAGY IN AGE-RELATED MUSCLE LOSS

    OpenAIRE

    Lo Verso, Francesca

    2014-01-01

    Autophagy is an ubiquitous degradation system, that is conserved through species. Cells activate autophagy to degrade long-lived proteins, damaged organelles or portions of cytoplasm, that are engulfed in double-membrane vesicles called autophagosomes, that ultimately fuse to lysosomes, where the cargo is degraded and breakdown products are recycled to sustain cellular energetic demands. Skeletal muscle is the most abundant tissue in mammals and controls 80% of the blood glucose. We have r...

  19. Are mitochondrial reactive oxygen species required for autophagy?

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jianfei, E-mail: jjf73@pitt.edu [Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, University of Pittsburgh (United States); Maeda, Akihiro; Ji, Jing [Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, University of Pittsburgh (United States); Baty, Catherine J.; Watkins, Simon C. [Center for Biologic Imaging, Department of Cell Biology and Physiology, University of Pittsburgh (United States); Greenberger, Joel S. [Department of Radiation Oncology, University of Pittsburgh (United States); Kagan, Valerian E., E-mail: kagan@pitt.edu [Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, University of Pittsburgh (United States)

    2011-08-19

    Highlights: {yields} Autophageal and apoptotic pathways were dissected in cytochrome c deficient cells. {yields} Staurosporine (STS)-induced autophagy was not accompanied by ROS generation. {yields} Autophagy was detectable in mitochondrial DNA deficient {rho}{sup 0} cells. {yields} Mitochondrial ROS are not required for the STS-induced autophagy in HeLa cells. -- Abstract: Reactive oxygen species (ROS) are said to participate in the autophagy signaling. Supporting evidence is obscured by interference of autophagy and apoptosis, whereby the latter heavily relies on ROS signaling. To dissect autophagy from apoptosis we knocked down expression of cytochrome c, the key component of mitochondria-dependent apoptosis, in HeLa cells using shRNA. In cytochrome c deficient HeLa1.2 cells, electron transport was compromised due to the lack of electron shuttle between mitochondrial respiratory complexes III and IV. A rapid and robust LC3-I/II conversion and mitochondria degradation were observed in HeLa1.2 cells treated with staurosporine (STS). Neither generation of superoxide nor accumulation of H{sub 2}O{sub 2} was detected in STS-treated HeLa1.2 cells. A membrane permeable antioxidant, PEG-SOD, plus catalase exerted no effect on STS-induced LC3-I/II conversion and mitochondria degradation. Further, STS caused autophagy in mitochondria DNA-deficient {rho}{sup o} HeLa1.2 cells in which both electron transport and ROS generation were completely disrupted. Counter to the widespread view, we conclude that mitochondrial ROS are not required for the induction of autophagy.

  20. Autophagy as a Possible Underlying Mechanism of Nanomaterial Toxicity

    Directory of Open Access Journals (Sweden)

    Vanessa Cohignac

    2014-07-01

    Full Text Available The rapid development of nanotechnologies is raising safety concerns because of the potential effects of engineered nanomaterials on human health, particularly at the respiratory level. Since the last decades, many in vivo studies have been interested in the pulmonary effects of different classes of nanomaterials. It has been shown that some of them can induce toxic effects, essentially depending on their physico-chemical characteristics, but other studies did not identify such effects. Inflammation and oxidative stress are currently the two main mechanisms described to explain the observed toxicity. However, the exact underlying mechanism(s still remain(s unknown and autophagy could represent an interesting candidate. Autophagy is a physiological process in which cytoplasmic components are digested via a lysosomal pathway. It has been shown that autophagy is involved in the pathogenesis and the progression of human diseases, and is able to modulate the oxidative stress and pro-inflammatory responses. A growing amount of literature suggests that a link between nanomaterial toxicity and autophagy impairment could exist. In this review, we will first summarize what is known about the respiratory effects of nanomaterials and we will then discuss the possible involvement of autophagy in this toxicity. This review should help understand why autophagy impairment could be taken as a promising candidate to fully understand nanomaterials toxicity.

  1. Autophagy and lysosomal dysfunction as emerging mechanisms of nanomaterial toxicity

    Directory of Open Access Journals (Sweden)

    Stern Stephan T

    2012-06-01

    Full Text Available Abstract The study of the potential risks associated with the manufacture, use, and disposal of nanoscale materials, and their mechanisms of toxicity, is important for the continued advancement of nanotechnology. Currently, the most widely accepted paradigms of nanomaterial toxicity are oxidative stress and inflammation, but the underlying mechanisms are poorly defined. This review will highlight the significance of autophagy and lysosomal dysfunction as emerging mechanisms of nanomaterial toxicity. Most endocytic routes of nanomaterial cell uptake converge upon the lysosome, making the lysosomal compartment the most common intracellular site of nanoparticle sequestration and degradation. In addition to the endo-lysosomal pathway, recent evidence suggests that some nanomaterials can also induce autophagy. Among the many physiological functions, the lysosome, by way of the autophagy (macroautophagy pathway, degrades intracellular pathogens, and damaged organelles and proteins. Thus, autophagy induction by nanoparticles may be an attempt to degrade what is perceived by the cell as foreign or aberrant. While the autophagy and endo-lysosomal pathways have the potential to influence the disposition of nanomaterials, there is also a growing body of literature suggesting that biopersistent nanomaterials can, in turn, negatively impact these pathways. Indeed, there is ample evidence that biopersistent nanomaterials can cause autophagy and lysosomal dysfunctions resulting in toxicological consequences.

  2. Targeting Protective Autophagy Exacerbates UV-Triggered Apoptotic Cell Death

    Directory of Open Access Journals (Sweden)

    Shih-Hwa Chiou

    2012-01-01

    Full Text Available Autophagy is activated by various stresses, including DNA damage, and previous studies of DNA damage-induced autophagy have focused on the response to chemotherapeutic drugs, ionizing radiation, and reactive oxygen species. In this study, we investigated the biological significance of autophagic response to ultraviolet (UV irradiation in A549 and H1299 cells. Our results indicated that UV induces on-rate autophagic flux in these cells. Autophagy inhibition resulting from the knockdown of beclin-1 and Atg5 reduced cell viability and enhanced apoptosis. Moreover, we found that ATR phosphorylation was accompanied by microtubule-associated protein 1 light chain 3B II (LC3B-II expression during the early phases following UV irradiation, which is a well-established inducer of ATR. Knocking down ATR further attenuated the reduction in LC3B-II at early stages in response to UV treatment. Despite the potential role of ATR in autophagic response, reduced ATR expression does not affect autophagy induction during late phases (24 and 48 h after UV treatment. The result is consistent with the reduced ATR phosphorylation at the same time points and suggests that autophagic response at this stage is activated via a distinct pathway. In conclusion, this study demonstrated that autophagy acts as a cytoprotective mechanism against UV-induced apoptosis and that autophagy induction accompanied with apoptosis at late stages is independent of ATR activation.

  3. Autophagy inhibitors as a potential antiamoebic treatment for Acanthamoeba keratitis.

    Science.gov (United States)

    Moon, Eun-Kyung; Kim, So-Hee; Hong, Yeonchul; Chung, Dong-Il; Goo, Youn-Kyoung; Kong, Hyun-Hee

    2015-07-01

    Acanthamoeba cysts are resistant to extreme physical and chemical conditions. Autophagy is an essential pathway for encystation of Acanthamoeba cells. To evaluate the possibility of an autophagic Acanthamoeba encystation mechanism, we evaluated autophagy inhibitors, such as 3-methyladenine (3MA), LY294002, wortmannin, bafilomycin A, and chloroquine. Among these autophagy inhibitors, the use of 3MA and chloroquine showed a significant reduction in the encystation ratio in Acanthamoeba cells. Wortmannin also inhibited the formation of mature cysts, while LY294002 and bafilomycin A did not affect the encystation of Acanthamoeba cells. Transmission electron microscopy revealed that 3MA and wortmannin inhibited autophagy formation and that chloroquine interfered with the formation of autolysosomes. Inhibition of autophagy or autolysosome formation resulted in a significant block in the encystation in Acanthamoeba cells. Clinical treatment with 0.02% polyhexamethylene biguanide (PHMB) showed high cytopathic effects on Acanthamoeba trophozoites and cysts; however, it also revealed high cytopathic effects on human corneal epithelial cells. In this study, we investigated effects of the combination of a low (0.00125%) concentration of PHMB with each of the autophagy inhibitors 3MA, wortmannin, and chloroquine on Acanthamoeba and human corneal epithelial cells. These new combination treatments showed low cytopathic effects on human corneal cells and high cytopathic effects on Acanthamoeba cells. Taken together, these results provide fundamental information for optimizing the treatment of Acanthamoeba keratitis.

  4. The role of autophagy in microbial infection and immunity

    Directory of Open Access Journals (Sweden)

    Desai M

    2015-01-01

    Full Text Available Mayura Desai,1 Rong Fang,2 Jiaren Sun11Department of Microbiology and Immunology, 2Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX, USAAbstract: The autophagy pathway represents an evolutionarily conserved cell recycling process that is activated in response to nutrient deprivation and other stress signals. Over the years, it has been linked to an array of cellular functions. Equally, a wide range of cell-intrinsic, as well as extracellular, factors have been implicated in the induction of the autophagy pathway. Microbial infections represent one such factor that can not only activate autophagy through specific mechanisms but also manipulate the response to the invading microbe's advantage. Moreover, in many cases, particularly among viruses, the pathway has been shown to be intricately involved in the replication cycle of the pathogen. Conversely, autophagy also plays a role in combating the infection process, both through direct destruction of the pathogen and as one of the key mediating factors in the host defense mechanisms of innate and adaptive immunity. Further, the pathway also plays a role in controlling the pathogenesis of infectious diseases by regulating inflammation. In this review, we discuss various interactions between pathogens and the cellular autophagic response and summarize the immunological functions of the autophagy pathway.Keywords: autophagy, xenophagy, antiviral, antibacterial

  5. Crosstalk between apoptosis and autophagy within the Beclin 1 interactome.

    Science.gov (United States)

    Maiuri, Maria Chiara; Criollo, Alfredo; Kroemer, Guido

    2010-02-03

    Although the essential genes for autophagy (Atg) have been identified, the molecular mechanisms through which Atg proteins control 'self eating' in mammalian cells remain elusive. Beclin 1 (Bec1), the mammalian orthologue of yeast Atg6, is part of the class III phosphatidylinositol 3-kinase (PI3K) complex that induces autophagy. The first among an increasing number of Bec1-interacting proteins that has been identified is the anti-apoptotic protein Bcl-2. The dissociation of Bec1 from Bcl-2 is essential for its autophagic activity, and Bcl-2 only inhibits autophagy when it is present in the endoplasmic reticulum (ER). A paper in this issue of the EMBO Journal has identified a novel protein, NAF-1 (nutrient-deprivation autophagy factor-1), that binds Bcl-2 at the ER. NAF-1 is a component of the inositol-1,4,5 trisphosphate (IP3) receptor complex, which contributes to the interaction of Bcl-2 with Bec1 and is required for Bcl-2 to functionally antagonize Bec1-mediated autophagy. This work provides mechanistic insights into how autophagy- and apoptosis-regulatory molecules crosstalk at the ER.

  6. Role of autophagy in prion protein-induced neurodegenerative diseases

    Institute of Scientific and Technical Information of China (English)

    Hao Yao; Deming Zhao; Sher Hayat Khan; Lifeng Yang

    2013-01-01

    Prion diseases,characterized by spongiform degeneration and the accumulation of misfolded and aggregated PrPSc in the central nervous system,are one of fatal neurodegenerative and infectious disorders of humans and animals.In earlier studies,autophagy vacuoles in neurons were frequently observed in neurodegenerative diseases such as Alzheimer's,Parkinson's,and Huntington's diseases as well as prion diseases.Autophagy is a highly conserved homeostatic process by which several cytoplasmic components (proteins or organelles) are sequestered in a doublemembrane-bound vesicle termed 'autophagosome' and degraded upon their fusion with lysosome.The pathway of intercellular self-digestion at basal physiological levels is indispensable for maintaining the healthy status of tissues and organs.In case of prion infection,increasing evidence indicates that autophagy has a crucial ability of eliminating pathological PrPSc accumulated within neurons.In contrast,autophagy dysfunction in affected neurons may contribute to the formation of spongiform changes.In this review,we summarized recent findings about the effect of mammalian autophagy in neurodegenerative disorders,particularly in prion diseases.We also summarized the therapeutic potential of some small molecules (such as lithium,rapamycin,Sirtuin 1 and resveratrol) targets to mitigate such diseases on brain function.Furthermore,we discussed the controversial role of autophagy,whether it mediates neuronal toxicity or serves a protective function in neurodegenerative disorders.

  7. Impaired Podocyte Autophagy Exacerbates Proteinuria in Diabetic Nephropathy.

    Science.gov (United States)

    Tagawa, Atsuko; Yasuda, Mako; Kume, Shinji; Yamahara, Kosuke; Nakazawa, Jun; Chin-Kanasaki, Masami; Araki, Hisazumi; Araki, Shin-Ichi; Koya, Daisuke; Asanuma, Katsuhiko; Kim, Eun-Hee; Haneda, Masakazu; Kajiwara, Nobuyuki; Hayashi, Kazuyuki; Ohashi, Hiroshi; Ugi, Satoshi; Maegawa, Hiroshi; Uzu, Takashi

    2016-03-01

    Overcoming refractory massive proteinuria remains a clinical and research issue in diabetic nephropathy. This study was designed to investigate the pathogenesis of massive proteinuria in diabetic nephropathy, with a special focus on podocyte autophagy, a system of intracellular degradation that maintains cell and organelle homeostasis, using human tissue samples and animal models. Insufficient podocyte autophagy was observed histologically in patients and rats with diabetes and massive proteinuria accompanied by podocyte loss, but not in those with no or minimal proteinuria. Podocyte-specific autophagy-deficient mice developed podocyte loss and massive proteinuria in a high-fat diet (HFD)-induced diabetic model for inducing minimal proteinuria. Interestingly, huge damaged lysosomes were found in the podocytes of diabetic rats with massive proteinuria and HFD-fed, podocyte-specific autophagy-deficient mice. Furthermore, stimulation of cultured podocytes with sera from patients and rats with diabetes and massive proteinuria impaired autophagy, resulting in lysosome dysfunction and apoptosis. These results suggest that autophagy plays a pivotal role in maintaining lysosome homeostasis in podocytes under diabetic conditions, and that its impairment is involved in the pathogenesis of podocyte loss, leading to massive proteinuria in diabetic nephropathy. These results may contribute to the development of a new therapeutic strategy for advanced diabetic nephropathy.

  8. Systemic abnormalities in liver disease

    Institute of Scientific and Technical Information of China (English)

    Masami Minemura; Kazuto Tajiri; Yukihiro Shimizu

    2009-01-01

    Systemic abnormalities often occur in patients with liver disease. In particular, cardiopulmonary or renal diseases accompanied by advanced liver disease can be serious and may determine the quality of life and prognosis of patients. Therefore, both hepatologists and non-hepatologists should pay attention to such abnormalities in the management of patients with liver diseases.

  9. Abnormal pressure in hydrocarbon environments

    Science.gov (United States)

    Law, B.E.; Spencer, C.W.

    1998-01-01

    Abnormal pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on abnormal pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of abnormally high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of abnormal pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of abnormal pressure. The association of abnormal pressures with hydrocarbon accumulations is statistically significant. Within abnormally pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and gas occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). Abnormally pressured rocks are also commonly associated with unconventional gas accumulations where the pressuring phase is gas of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.

  10. 自噬参与心脏疾病调控的研究进展%The Progress of Autophagy Involved in Heart Disease

    Institute of Scientific and Technical Information of China (English)

    谢凤; 柳威; 陈临溪

    2012-01-01

    damaged, modified or aging proteins and organdies are transported to the lysosome/vacuole for degradation. Autophagy is not only a widespread normal physiological process, but also a cell defense mechanism to adverse environment, involved in the pathological process of diseases. The normal level of autophagy can protect cells from environmental stimuli, however, continued excessive or insufficient autophagy could lead to disease. In the heart, myocardial autophagy plays a vital role to maintain myocardial function, but dysfunctional autophagy contributes to a diverse set of heart diseases, such as Danon disease. Multiple forms of cardiovascular stress can increase autophagic activity in cardiomyocytes, including chronic ischemia, reperfusion injury and Chronic hypoxia. The function of autophagy in these conditions is poorly understood: Does it serve a pro-survival function or contribute to disease pathogenesis, cell death, or both? Heart disease is the abnormal myocardia function when to produce a variety of pathological state. In the state of disease, cardiac autophagy degree will change, related to the occurrence and development of disease. As in Hypertrophic cardiomyopathy process, cell autophagy is reduced and aggravate myocardial hypertrophy. In heart failure process, autophagy increases can lead to cell death; And in myocardial infarction process, autophagy is enhanced and reduce the infarction area. But the real role of autophagy in the myocardium depending on the level of autophagic activation and the context in which it is induced. Currently, more and more people begin to pay close attention to the relationship between drugs and autophagy regulation, particularly on antitumor drugs and cardiovascular drugs. In addition, there are reports of estrogen receptor antagonists tamoxifen and vitamins also has a regulatory role for autophagy. To research of the relationship between autophagy and heart disease, and drugs on the regulation of autophagy will benefit for the

  11. Aggresome–Autophagy Involvement in a Sarcopenic Patient with Rigid Spine Syndrome and a p.C150R Mutation in FHL1 Gene

    Science.gov (United States)

    Sabatelli, Patrizia; Castagnaro, Silvia; Tagliavini, Francesca; Chrisam, Martina; Sardone, Francesca; Demay, Laurence; Richard, Pascale; Santi, Spartaco; Maraldi, Nadir M.; Merlini, Luciano; Sandri, Marco; Bonaldo, Paolo

    2014-01-01

    The four-and-half LIM domain protein 1 (FHL1) is highly expressed in skeletal and cardiac muscle. Mutations of the FHL1 gene have been associated with diverse chronic myopathies including reducing body myopathy, rigid spine syndrome (RSS), and Emery–Dreifuss muscular dystrophy. We investigated a family with a mutation (p.C150R) in the second LIM domain of FHL1. In this family, a brother and a sister were affected by RSS, and their mother had mild lower limbs weakness. The 34-year-old female had an early and progressive rigidity of the cervical spine and severe respiratory insufficiency. Muscle mass evaluated by DXA was markedly reduced, while fat mass was increased to 40%. CT scan showed an almost complete substitution of muscle by fibro-adipose tissue. Muscle biopsy showed accumulation of FHL1 throughout the cytoplasm and around myonuclei into multiprotein aggregates with aggresome/autophagy features as indicated by ubiquitin, p62, and LC3 labeling. DNA deposits, not associated with nuclear lamina components and histones, were also detected in the aggregates, suggesting nuclear degradation. Ultrastructural analysis showed the presence of dysmorphic nuclei, accumulation of tubulofilamentous and granular material, and perinuclear accumulation of autophagic vacuoles. These data point to involvement of the aggresome–autophagy pathway in the pathophysiological mechanism underlying the muscle pathology of FHL1 C150R mutation. PMID:25191266

  12. p62/SQSTM1 differentially removes the toxic mutant androgen receptor via autophagy and inclusion formation in a spinal and bulbar muscular atrophy mouse model.

    Science.gov (United States)

    Doi, Hideki; Adachi, Hiroaki; Katsuno, Masahisa; Minamiyama, Makoto; Matsumoto, Shinjiro; Kondo, Naohide; Miyazaki, Yu; Iida, Madoka; Tohnai, Genki; Qiang, Qiang; Tanaka, Fumiaki; Yanagawa, Toru; Warabi, Eiji; Ishii, Tetsuro; Sobue, Gen

    2013-05-01

    Polyglutamine (polyQ) diseases are inherited neurodegenerative disorders that are caused by the expansion of trinucleotide CAG repeats in the causative genes. Spinal and bulbar muscular atrophy (SBMA) is an inherited motor neuron disease that is caused by the expansion of a polyQ tract within the androgen receptor (AR). p62 is a ubiquitin- and light-chain 3-binding protein that is known to regulate the degradation of targeted proteins via autophagy and inclusion formation. In this study, we examined the effects of p62 depletion and overexpression on cultured cells and in a transgenic mouse model that overexpressed the mutant AR. Here, we demonstrate that depletion of p62 significantly exacerbated motor phenotypes and the neuropathological outcome, whereas overexpression of p62 protected against mutant AR toxicity in SBMA mice. Depletion of p62 significantly increased the levels of monomeric mutant AR and mutant AR protein complexes in an SBMA mouse model via the impairment of autophagic degradation. In addition, p62 overexpression improved SBMA mouse phenotypes by inducing cytoprotective inclusion formation. Our results demonstrate that p62 provides two different therapeutic targets in SBMA pathogenesis: (1) autophagy-dependent degradation and (2) benevolent inclusion formation of the mutant AR.

  13. Noncanonical E2 recruitment by the autophagy E1 revealed by Atg7-Atg3 and Atg7-Atg10 structures

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Stephen E; Mao, Kai; Taherbhoy, Asad M; Yu, Shanshan; Olszewski, Jennifer L; Duda, David M; Kurinov, Igor; Deng, Alan; Fenn, Timothy D; Klionsky, Daniel J; Schulman, Brenda A [Cornell; (Stanford); (Michigan); (Tennessee-HSC); (SJCH)

    2012-11-11

    Core functions of autophagy are mediated by ubiquitin-like protein (UBL) cascades, in which a homodimeric E1 enzyme, Atg7, directs the UBLs Atg8 and Atg12 to their respective E2 enzymes, Atg3 and Atg10. Crystallographic and mutational analyses of yeast (Atg7–Atg3)2 and (Atg7–Atg10)2 complexes reveal noncanonical, multisite E1-E2 recognition in autophagy. Atg7's unique N-terminal domain recruits distinctive elements from the Atg3 and Atg10 'backsides'. This, along with E1 and E2 conformational variability, allows presentation of 'frontside' Atg3 and Atg10 active sites to the catalytic cysteine in the C-terminal domain from the opposite Atg7 protomer in the homodimer. Despite different modes of binding, the data suggest that common principles underlie conjugation in both noncanonical and canonical UBL cascades, whereby flexibly tethered E1 domains recruit E2s through surfaces remote from their active sites to juxtapose the E1 and E2 catalytic cysteines.

  14. Atg8 Transfer from Atg7 to Atg3: A Distinctive E1-E2 Architecture and Mechanism in the Autophagy Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Taherbhoy, Asad M.; Tait, Stephen W.; Kaiser, Stephen E.; Williams, Allison H.; Deng, Alan; Nourse, Amanda; Hammel, Michal; Kurinov, Igor; Rock, Charles O.; Green, Douglas R.; Schulman, Brenda A. (Cornell); (LBNL); (SJCH)

    2012-07-11

    Atg7 is a noncanonical, homodimeric E1 enzyme that interacts with the noncanonical E2 enzyme, Atg3, to mediate conjugation of the ubiquitin-like protein (UBL) Atg8 during autophagy. Here we report that the unique N-terminal domain of Atg7 (Atg7{sup NTD}) recruits a unique 'flexible region' from Atg3 (Atg3{sup FR}). The structure of an Atg7{sup NTD}-Atg3{sup FR} complex reveals hydrophobic residues from Atg3 engaging a conserved groove in Atg7, important for Atg8 conjugation. We also report the structure of the homodimeric Atg7 C-terminal domain, which is homologous to canonical E1s and bacterial antecedents. The structures, SAXS, and crosslinking data allow modeling of a full-length, dimeric (Atg7 {approx} Atg8-Atg3){sub 2} complex. The model and biochemical data provide a rationale for Atg7 dimerization: Atg8 is transferred in trans from the catalytic cysteine of one Atg7 protomer to Atg3 bound to the N-terminal domain of the opposite Atg7 protomer within the homodimer. The studies reveal a distinctive E1 {approx} UBL-E2 architecture for enzymes mediating autophagy.

  15. The age-associated loss of ischemic preconditioning in the kidney is accompanied by mitochondrial dysfunction, increased protein acetylation and decreased autophagy

    Science.gov (United States)

    Jankauskas, Stanislovas S.; Pevzner, Irina B.; Andrianova, Nadezda V.; Zorova, Ljubava D.; Popkov, Vasily A.; Silachev, Denis N.; Kolosova, Nataliya G.; Plotnikov, Egor Y.; Zorov, Dmitry B.

    2017-01-01

    In young rats, ischemic preconditioning (IPC), which consists of 4 cycles of ischemia and reperfusion alleviated kidney injury caused by 40-min ischemia. However,old rats lost their ability to protect the ischemic kidney by IPC. A similar aged phenotype was demonstrated in 6-month-old OXYS rats having signs of premature aging. In the kidney of old and OXYS rats, the levels of acetylated nuclear proteins were higher than in young rats, however, unlike in young rats, acetylation levels in old and OXYS rats were further increased after IPC. In contrast to Wistar rats, age-matched OXYS demonstrated no increase in lysosome abundance and LC3 content in the kidney after ischemia/reperfusion. The kidney LC3 levels were also lower in OXYS, even under basal conditions, and mitochondrial PINK1 and ubiquitin levels were higher, suggesting impaired mitophagy. The kidney mitochondria from old rats contained a population with diminished membrane potential and this fraction was expanded by IPC. Apparently, oxidative changes with aging result in the appearance of malfunctioning renal mitochondria due to a low efficiency of autophagy. Elevated protein acetylation might be a hallmark of aging which is associated with a decreased autophagy, accumulation of dysfunctional mitochondria, and loss of protection against ischemia by IPC. PMID:28294175

  16. Identification of sites of ubiquitination in proteins: a fourier transform ion cyclotron resonance mass spectrometry approach.

    Science.gov (United States)

    Cooper, Helen J; Heath, John K; Jaffray, Ellis; Hay, Ronald T; Lam, Tukiet T; Marshall, Alan G

    2004-12-01

    Structural elucidation of posttranslationally modified peptides and proteins is of key importance in the understanding of an array of biological processes. Ubiquitination is a reversible modification that regulates many cellular functions. Consequences of ubiquitination depend on whether a single ubiquitin or polyubiquitin chain is added to the tagged protein. The lysine residue through which the polyubiquitin chain is formed is also critical for biological activity. Robust methods are therefore required to identify sites of ubiquitination modification, both in the target protein and in ubiquitin. Here, we demonstrate the suitability of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, in conjunction with activated ion electron capture dissociation (AI ECD) or infrared multiphoton dissociation (IRMPD), for the analysis of ubiquitinated proteins. Polyubiquitinated substrate protein GST-Ubc5 was generated in vitro. Tryptic digests of polyubiquitinated species contain modified peptides in which the ubiquitin C-terminal Gly-Gly residues are retained on the modified lysine residues. Direct infusion microelectrospray FT-ICR of the digest and comparison with an in silico digest enables identification of modified peptides and therefore sites of ubiquitination. Fifteen sites of ubiquitination were identified in GST-Ubc5 and four sites in ubiquitin. Assignments were confirmed by AI ECD or IRMPD. The Gly-Gly modification is stable and both tandem mass spectrometric techniques are suitable, providing extensive sequence coverage and retention of the modification on backbone fragments.

  17. Mastermind-Like 1 Is Ubiquitinated: Functional Consequences for Notch Signaling.

    Directory of Open Access Journals (Sweden)

    Mozhgan Farshbaf

    Full Text Available Early studies demonstrated the involvement of ubiquitination of the Notch intracellular domain for rapid turnover of the transcriptional complex at Notch target genes. It was shown that this ubiquitination was promoted by the co-activator Mastermind like 1 (MAML1. MAML1 also contains numerous lysine residues that may also be ubiquitinated and necessary for protein regulation. In this study, we show that over-expressed MAML1 is ubiquitinated and identify eight conserved lysine residues which are required for ubiquitination. We also show that p300 stimulates ubiquitination and that Notch inhibits ubiquitination. Furthermore, we show that a mutant MAML1 that has decreased ubiquitination shows increased output from a HES1 reporter gene assay. Therefore, we speculate that ubiquitination of MAML1 might be a mechanism to maintain low levels of the protein until needed for transcriptional activation. In summary, this study identifies that MAML1 is ubiquitinated in the absence of Notch signaling to maintain low levels of MAML1 in the cell. Our data supports the notion that a precise and tight regulation of the Notch pathway is required for this signaling pathway.

  18. Cell fate determination by ubiquitin-dependent regulation of translation

    Science.gov (United States)

    Werner, Achim; Iwasaki, Shintaro; McGourty, Colleen; Medina-Ruiz, Sofia; Teerikorpi, Nia; Fedrigo, Indro; Ingolia, Nicholas T.; Rape, Michael

    2015-01-01

    Metazoan development depends on accurate execution of differentiation programs that allow pluripotent stem cells to adopt specific fates 1. Differentiation requires changes to chromatin architecture and transcriptional networks, yet whether other regulatory events support cell fate determination is less well understood. Here, we have identified the vertebrate-specific ubiquitin ligase CUL3KBTBD8 as an essential regulator of neural crest specification. CUL3KBTBD8 monoubiquitylates NOLC1 and its paralog TCOF1, whose mutation underlies the neurocristopathy Treacher Collins Syndrome 2,3. Ubiquitylation drives formation of a TCOF1-NOLC1 platform that connects RNA polymerase I with ribosome modification enzymes and remodels the translational program of differentiating cells in favor of neural crest specification. We conclude that ubiquitin-dependent regulation of translation is an important feature of cell fate determination. PMID:26399832

  19. Direct observation of silver nanoparticle-ubiquitin corona formation

    CERN Document Server

    Ding, Feng; Choudhary, Poonam; Chen, Ran; Brown, Jared M; Ke, Pu Chun

    2012-01-01

    Upon entering physiological environments, nanoparticles readily assume the form of a nanoparticle-protein corona that dictates their biological identity. Understanding the structure and dynamics of nanoparticle-protein corona is essential for predicting the fate, transport, and toxicity of nanomaterials in living systems and for enabling the vast applications of nanomedicine. We combined multiscale molecular dynamics simulations and complementary experiments to characterize the silver nanoparticle-ubiquitin corona formation. Specifically, ubiquitins competed with citrates for the nanoparticle surface and bound to the particle in a specific manner. Under a high protein/nanoparticle stoichiometry, ubiquitions formed a multi-layer corona on the particle surface. The binding exhibited an unusual stretched-exponential behavior, suggesting a rich kinetics originated from protein-protein, protein-citrate, and protein-nanoparticle interactions. Furthermore, the binding destabilized the {\\alpha}-helices while increasi...

  20. Role of the Ubiquitin Proteasome System in Regulating Skin Pigmentation

    Directory of Open Access Journals (Sweden)

    Hideya Ando

    2009-10-01

    Full Text Available Pigmentation of the skin, hair and eyes is regulated by tyrosinase, the critical rate-limiting enzyme in melanin synthesis by melanocytes. Tyrosinase is degraded endogenously, at least in part, by the ubiquitin proteasome system (UPS. Several types of inherited hypopigmentary diseases, such as oculocutaneous albinism and Hermansky-Pudlak syndrome, involve the aberrant processing and/or trafficking of tyrosinase and its subsequent degradation which can occur due to the quality-control machinery. Studies on carbohydrate modifications have revealed that tyrosinase in the endoplasmic reticulum (ER is proteolyzed via ER-associated protein degradation and that tyrosinase degradation can also occur following its complete maturation in the Golgi. Among intrinsic factors that regulate the UPS, fatty acids have been shown to modulate tyrosinase degradation in contrasting manners through increased or decreased amounts of ubiquitinated tyrosinase that leads to its accelerated or decelerated degradation by proteasomes.