5-HT2A receptors in the feline brain: 123I-5-I-R91150 kinetics and the influence of ketamine measured with micro-SPECT.

Science.gov (United States)

Waelbers, Tim; Polis, Ingeborgh; Vermeire, Simon; Dobbeleir, André; Eersels, Jos; De Spiegeleer, Bart; Audenaert, Kurt; Slegers, Guido; Peremans, Kathelijne

2013-08-01

Subanesthetic doses of ketamine can be used as a rapid-acting antidepressant in patients with treatment-resistant depression. Therefore, the brain kinetics of (123)I-5-I-R91150 (4-amino-N-[1-[3-(4-fluorophenyl)propyl]-4-methylpiperidin-4-yl]-5-iodo-2-methoxybenzamide) and the influence of ketamine on the postsynaptic serotonin-2A receptor (5-hydroxytryptamine-2A, or 5-HT2A) status were investigated in cats using micro-SPECT. This study was conducted on 6 cats using the radioligand (123)I-5-I-R91150, a 5-HT2A receptor antagonist, as the imaging probe. Anesthesia was induced and maintained with a continuous-rate infusion of propofol (8.4 ± 1.2 mg kg(-1) followed by 0.22 mg kg(-1) min(-1)) 75 min after tracer administration, and acquisition of the first image began 15 min after induction of anesthesia. After this first acquisition, propofol (0.22 mg kg(-1) min(-1)) was combined with ketamine (5 mg kg(-1) followed by 0.023 mg kg(-1) min(-1)), and the second acquisition began 15 min later. Semiquantification, with the cerebellum as a reference region, was performed to calculate the 5-HT2A receptor binding indices (parameter for available receptor density) in the frontal and temporal cortices. The binding indices were analyzed with Wilcoxon signed ranks statistics. The addition of ketamine to the propofol continuous-rate infusion resulted in decreased binding indices in the right frontal cortex (1.25 ± 0.22 vs. 1.45 ± 0.16; P = 0.028), left frontal cortex (1.34 ± 0.15 vs. 1.49 ± 0.10; P = 0.028), right temporal cortex (1.30 ± 0.17 vs. 1.45 ± 0.09; P = 0.046), and left temporal cortex (1.41 ± 0.20 vs. 1.52 ± 0.20; P = 0.046). This study showed that cats can be used as an animal model for studying alterations of the 5-HT2A receptor status with (123)I-5-I-R91150 micro-SPECT. Furthermore, an interaction between ketamine and the 5-HT2A receptors resulting in decreased binding of (123)I-5-I-R91150 in the frontal and temporal cortices was demonstrated. Whether the

DNA binding properties of dioxin receptors in wild-type and mutant mouse hepatoma cells

International Nuclear Information System (INIS)

Cuthill, S.; Poellinger, L.

1988-01-01

The current model of action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) entails stimulation of target gene transcription via the formation of dioxin-receptor complexes and subsequent accumulation of the complexes within the cell nucleus. Here, the authors have analyzed the DNA binding properties of the dioxin receptor in wild-type mouse hepatoma (Hepa 1c1c7) cells and a class of nonresponsive mutant cells which fail to accumulate dioxin-receptor complexes within the nucleus in vivo. In vitro, both the wild-type and mutant [ 3 H]dioxin-receptor complexes exhibited low affinity for DNA-cellulose (5-8% and around 4% retention, respectively) in the absence of prior biochemical manipulations. However, following chromatography on heparin-Sepharose, the wild-type but not the mutant dioxin receptor was transformed to a species with an increased affinity for DNA (40-50% retention on DNA-cellulose). The gross molecular structure of the mutant, non DNA binding dioxin receptor did not appear to be altered as compared to that of the wild-type receptor. These results imply that the primary deficiency in the mutant dioxin receptor form may reside at the DNA binding level and that, in analogy to steroid hormone receptors, DNA binding of the receptor may be an essential step in the regulation of target gene transcription by dioxin

Biofilm formation and binding specificities of CFA/I, CFA/II and CS2 adhesions of enterotoxigenic Escherichia coli and Cfae-R181A mutant.

Science.gov (United States)

Liaqat, Iram; Sakellaris, Harry

2012-07-01

Enterotoxigenic Escherichia coli (ETEC) strains are leading causes of childhood diarrhea in developing countries. Adhesion is the first step in pathogenesis of ETEC infections and ETEC pili designated colonization factor antigens (CFAs) are believed to be important in the biofim formation, colonization and host cell adhesions. As a first step, we have determined the biofilm capability of ETEC expressing various types of pili (CFA/I, CfaE-R181A mutant/CfaE tip mutant, CFA/II and CS2). Further, enzyme-linked immunosorbent assay (ELISA) assay were developed to compare the binding specificity of CFA/I, CFA/II (CS1 - CS3) and CS2 of ETEC, using extracted pili and piliated bacteria. CFA/II strain (E24377a) as well as extracted pili exhibited significantly higher binding both in biofilm and ELISA assays compared to non piliated wild type E24377a, CFA/I and CS2 strains. This indicates that co-expression of two or more CS2 in same strain is more efficient in increasing adherence. Significant decrease in binding specificity of DH5αF'lacI (q)/∆cotD (CS2) strain and MC4100/pEU2124 (CfaE-R181A) mutant strain indicated the important contribution of tip proteins in adherence assays. However, CS2 tip mutant strain (DH5αF'lacI (q)/pEU5881) showed that this specific residue may not be important as adhesions in these strains. In summary, our data suggest that pili, their minor subunits are important for biofilm formation and adherence mechanisms. Overall, the functional reactivity of strains co expressing various antigens, particularly minor subunit antigen observed in this study suggest that fewer antibodies may be required to elicit immunity to ETEC expressing a wider array of related pili.

41 CFR 102-117.255 - What actions may I take if the TSP's performance is not satisfactory?

Science.gov (United States)

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What actions may I take if the TSP's performance is not satisfactory? 102-117.255 Section 102-117.255 Public Contracts and... may I take if the TSP's performance is not satisfactory? If the TSP's performance is not satisfactory...

Altered lipid homeostasis in Drosophila InsP3 receptor mutants leads to obesity and hyperphagia

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Manivannan Subramanian

2013-05-01

Obesity is a complex metabolic disorder that often manifests with a strong genetic component in humans. However, the genetic basis for obesity and the accompanying metabolic syndrome is poorly defined. At a metabolic level, obesity arises from an imbalance between the nutritional intake and energy utilization of an organism. Mechanisms that sense the metabolic state of the individual and convey this information to satiety centers help achieve this balance. Mutations in genes that alter or modify such signaling mechanisms are likely to lead to either obese individuals, who in mammals are at high risk for diabetes and cardiovascular disease, or excessively thin individuals with accompanying health problems. Here we show that Drosophila mutants for an intracellular calcium signaling channel, the inositol 1,4,5-trisphosphate receptor (InsP3R store excess triglycerides in their fat bodies and become unnaturally obese on a normal diet. Although excess insulin signaling can rescue obesity in InsP3R mutants to some extent, we show that it is not the only cause of the defect. Through mass spectrometric analysis of lipids we find that homeostasis of storage and membrane lipids are altered in InsP3R mutants. Possibly as a compensatory mechanism, InsP3R mutant adults also feed excessively. Thus, reduced InsP3R function alters lipid metabolism and causes hyperphagia in adults. Together, the metabolic and behavioral changes lead to obesity. Our results implicate altered InsP3 signaling as a previously unknown causative factor for metabolic syndrome in humans. Importantly, our studies also suggest preventive dietary interventions.

Quorum-sensing regulator RhlR but not its autoinducer RhlI enables Pseudomonas to evade opsonization.

Science.gov (United States)

Haller, Samantha; Franchet, Adrien; Hakkim, Abdul; Chen, Jing; Drenkard, Eliana; Yu, Shen; Schirmeier, Stefanie; Li, Zi; Martins, Nelson; Ausubel, Frederick M; Liégeois, Samuel; Ferrandon, Dominique

2018-03-09

When Drosophila melanogaster feeds on Pseudomonas aeruginosa , some bacteria cross the intestinal barrier and eventually proliferate in the hemocoel. This process is limited by hemocytes through phagocytosis. P. aeruginosa requires the quorum-sensing regulator RhlR to elude the cellular immune response of the fly. RhlI synthesizes the autoinducer signal that activates RhlR. Here, we show that rhlI mutants are unexpectedly more virulent than rhlR mutants, both in fly and in nematode intestinal infection models, suggesting that RhlR has RhlI-independent functions. We also report that RhlR protects P. aeruginosa from opsonization mediated by the Drosophila thioester-containing protein 4 (Tep4). RhlR mutant bacteria show higher levels of Tep4- mediated opsonization, as compared to rhlI mutants, which prevents lethal bacteremia in the Drosophila hemocoel. In contrast, in a septic model of infection, in which bacteria are introduced directly into the hemocoel, Tep4 mutant flies are more resistant to wild-type P. aeruginosa, but not to the rhlR mutant. Thus, depending on the infection route, the Tep4 opsonin can either be protective or detrimental to host defense. © 2018 The Authors.

Functional characterisation of homomeric ionotropic glutamate receptors GluR1-GluR6 in a fluorescence-based high throughput screening assay

DEFF Research Database (Denmark)

Strange, Mette; Bräuner-Osborne, Hans; Jensen, Anders A.

2006-01-01

We have constructed stable HEK293 cell lines expressing the rat ionotropic glutamate receptor subtypes GluR1(i), GluR2Q(i), GluR3(i), GluR4(i), GluR5Q and GluR6Q and characterised the pharmacological profiles of the six homomeric receptors in a fluorescence-based high throughput screening assay...... assay reported to date. We propose that high throughput screening of compound libraries at the six GluR-HEK293 cell lines could be helpful in the search for structurally and pharmacologically novel ligands acting at the receptors....

Zebrafish bandoneon mutants display behavioral defects due to a mutation in the glycine receptor β-subunit

Science.gov (United States)

Hirata, Hiromi; Saint-Amant, Louis; Downes, Gerald B.; Cui, Wilson W.; Zhou, Weibin; Granato, Michael; Kuwada, John Y.

2005-01-01

Bilateral alternation of muscle contractions requires reciprocal inhibition between the two sides of the hindbrain and spinal cord, and disruption of this inhibition should lead to simultaneous activation of bilateral muscles. At 1 day after fertilization, wild-type zebrafish respond to mechanosensory stimulation with multiple fast alternating trunk contractions, whereas bandoneon (beo) mutants contract trunk muscles on both sides simultaneously. Similar simultaneous contractions are observed in wild-type embryos treated with strychnine, a blocker of the inhibitory glycine receptor (GlyR). This result suggests that glycinergic synaptic transmission is defective in beo mutants. Muscle voltage recordings confirmed that muscles on both sides of the trunk in beo are likely to receive simultaneous synaptic input from the CNS. Recordings from motor neurons revealed that glycinergic synaptic transmission was missing in beo mutants. Furthermore, immunostaining with an antibody against GlyR showed clusters in wild-type neurons but not in beo neurons. These data suggest that the failure of GlyRs to aggregate at synaptic sites causes impairment of glycinergic transmission and abnormal behavior in beo mutants. Indeed, mutations in the GlyR β-subunit, which are thought to be required for proper localization of GlyRs, were identified as the basis for the beo mutation. These data demonstrate that GlyRβ is essential for physiologically relevant clustering of GlyRs in vivo. Because GlyR mutations in humans lead to hyperekplexia, a motor disorder characterized by startle responses, the zebrafish beo mutant should be a useful animal model for this condition. PMID:15928085

Morphine-induced internalization of the L83I mutant of the rat μ-opioid receptor.

Science.gov (United States)

Cooke, A E; Oldfield, S; Krasel, C; Mundell, S J; Henderson, G; Kelly, E

2015-01-01

Naturally occurring single-nucleotide polymorphisms (SNPs) within GPCRs can result in alterations in various pharmacological parameters. Understanding the regulation and function of endocytic trafficking of the μ-opioid receptor (MOP receptor) is of great importance given its implication in the development of opioid tolerance. This study has compared the agonist-dependent trafficking and signalling of L83I, the rat orthologue of a naturally occurring variant of the MOP receptor. Cell surface elisa, confocal microscopy and immunoprecipitation assays were used to characterize the trafficking properties of the MOP-L83I variant in comparison with the wild-type receptor in HEK 293 cells. Functional assays were used to compare the ability of the L83I variant to signal to several downstream pathways. Morphine-induced internalization of the L83I MOP receptor was markedly increased in comparison with the wild-type receptor. The altered trafficking of this variant was found to be specific to morphine and was both G-protein receptor kinase- and dynamin-dependent. The enhanced internalization of L83I variant in response to morphine was not due to increased phosphorylation of serine 375, arrestin association or an increased ability to signal. These results suggest that morphine promotes a specific conformation of the L83I variant that makes it more liable to internalize in response to morphine, unlike the wild-type receptor that undergoes significantly less morphine-stimulated internalization, providing an example of a ligand-selective biased receptor. The presence of this SNP within an individual may consequently affect the development of tolerance and analgesic responses. This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2. © 2014 The British Pharmacological Society.

RECEPTOR POTENTIAL AND LIGHT-INDUCED MITOCHONDRIAL ACTIVATION IN BLOWFLY PHOTORECEPTOR MUTANTS

NARCIS (Netherlands)

MOJET, MH; TINBERGEN, J; STAVENGA, DG

1991-01-01

1. Simultaneous measurements of the receptor potential and the light-induced mitochondrial activation were performed in white-eyed blowflies Calliphora vicina, mutant chalky, and Lucilia cuprina, mutants w(F) and w'nss. The intensity dependence and the temporal dynamics were investigated. 2. The

Rapid characterization of disease-causing mutations in the low density lipoprotein receptor (LDL-R) gene by overexpression in COS cells

DEFF Research Database (Denmark)

Jensen, T G; Andresen, B S; Jensen, H K

1996-01-01

To characterize disease-causing mutations in the low density lipoprotein receptor (LDL-R) gene, COS cells are transfected with the mutant gene in an EBV-based expression vector and characterized by flow cytometry. Using antibodies against the LDL-receptor the amount of receptor protein on the cel...

Modeling the interactions of a peptide-major histocompatibility class I ligand with its receptors. I. Recognition by two alpha beta T cell receptors

DEFF Research Database (Denmark)

Rognan, D; Stryhn, A; Fugger, L

2000-01-01

dynamics. Next, three-dimensional models of two different T cell receptors (TCRs) both specific for the Ha255-262/Kk complex were generated based on previously published TCR X-ray structures. Finally, guided by the recently published X-ray structures of ternary TCR/peptide/MHC-I complexes, the TCR models...... the models. They were found to account well for the experimentally obtained data, lending considerable support to the proposed models and suggesting a universal docking mode for alpha beta TCRs to MHC-peptide complexes. Such models may also be useful in guiding future rational experimentation....

Metabotropic Glutamate Receptor I (mGluR1) Antagonism Impairs Cocaine-Induced Conditioned Place Preference via Inhibition of Protein Synthesis

OpenAIRE

Yu, Fei; Zhong, Peng; Liu, Xiaojie; Sun, Dalong; Gao, Hai-qing; Liu, Qing-song

2013-01-01

Antagonism of group I metabotropic glutamate receptors (mGluR1 and mGluR5) reduces behavioral effects of drugs of abuse, including cocaine. However, the underlying mechanisms remain poorly understood. Activation of mGluR5 increases protein synthesis at synapses. Although mGluR5-induced excessive protein synthesis has been implicated in the pathology of fragile X syndrome, it remains unknown whether group I mGluR-mediated protein synthesis is involved in any behavioral effects of drugs of abus...

Evaluation and metabolite studies of {sup 125}I- and {sup 123}I-labelled E-(R,R)-IQNP: potential radioligands for visualization of M{sub 1} muscarinic acetylcholine receptors in brain

Energy Technology Data Exchange (ETDEWEB)

Bergstroem, Kim A.; Halldin, Christer; Hiltunen, Jukka; Swahn, Carl-Gunnar; Ito, Hiroshi; Ginovart, Nathalie; Hall, Haakan; McPherson, Daniel W.; Knapp, F. F. (Russ); Larsson, Stig; Schnell, Per-Olof; Farde, Lars

1998-04-01

A new ligand for the M{sub 1} muscarinic receptor subtype, E-(R,R)-1-azabicyclo[2.2.2]oct-3-yl {alpha}-hydroxy-{alpha}-(1-iodo-1-propen-3-yl)-{alpha}-phenylacetate (E-IQNP), was labelled with {sup 125}I and {sup 123}I for autoradiographic studies on human whole-brain cryosections and SPET studies, respectively, in Cynomolgus monkey. Autoradiography demonstrated E-[{sup 125}I]IQNP binding in M{sub 1} receptor-rich regions such as the neocortex and the striatum. The binding was displaceable by the selective M{sub 1} antagonist biperiden. In vivo single photon emission tomography (SPET) studies with E-[{sup 123}I]IQNP demonstrated a high accumulation of radioactivity in the monkey neocortex. Rapid hydrolysis of the quinuclidinyl ester to the free acid was found to be a major biotransformation route for E-[{sup 123}I]IQNP. The free acid of E-[{sup 123}I]IQNP does not pass the blood-brain barrier, but the plasma concentration was high as compared to the total radioactivity in brain. It is thus necessary to correct for the high concentration of radioactive metabolites in parenchymal blood (CBV) to obtain accurate values for E-[{sup 123}I]IQNP binding in brain.

Role of the ERC motif in the proximal part of the second intracellular loop and the C-terminal domain of the human prostaglandin F2alpha receptor (hFP-R) in G-protein coupling control.

Science.gov (United States)

Pathe-Neuschäfer-Rube, Andrea; Neuschäfer-Rube, Frank; Püschel, Gerhard P

2005-05-15

The human FP-R (F2alpha prostaglandin receptor) is a Gq-coupled heptahelical ectoreceptor, which is of significant medical interest, since it is a potential target for the treatment of glaucoma and preterm labour. On agonist exposure, it mediates an increase in intracellular inositol phosphate formation. Little is known about the structures that govern the agonist-dependent receptor activation. In other prostanoid receptors, the C-terminal domain has been inferred in the control of agonist-dependent receptor activation. A DRY motif at the beginning of the second intracellular loop is highly conserved throughout the G-protein-coupled receptor family and appears to be crucial for controlling agonist-dependent receptor activation. It is replaced by an ERC motif in the FP-R and no evidence for the relevance of this motif in ligand-dependent activation of prostanoid receptors has been provided so far. The aim of the present study was to elucidate the potential role of the C-terminal domain and the ERC motif in agonist-controlled intracellular signalling in FP-R mutants generated by site-directed mutagenesis. It was found that substitution of the acidic Glu(132) in the ERC motif by a threonine residue led to full constitutive activation, whereas truncation of the receptor's C-terminal domain led to partial constitutive activation of all three intracellular signal pathways that had previously been shown to be activated by the FP-R, i.e. inositol trisphosphate formation, focal adhesion kinase activation and T-cell factor signalling. Inositol trisphosphate formation and focal adhesion kinase phosphorylation were further enhanced by ligand binding in cells expressing the truncation mutant but not the E132T (Glu132-->Thr) mutant. Thus C-terminal truncation appeared to result in a receptor with partial constitutive activation, whereas substitution of Glu132 by threonine apparently resulted in a receptor with full constitutive activity.

Mutants of Escherichia coli K-12 with enhanced resistance to ionizing radiation. 4. Peculiarities of recombination in Gamsup(r) mutants

International Nuclear Information System (INIS)

Bresler, S.E.; Kalinin, V.L.; Laneeva, N.I.

1984-01-01

Radioresistant mutant Gam sup(r) 444 differs from a wild type and from Gam sup(r) 445 mutant in decreased frequency of long episome heritage ORF 1 (pur E + -tsx + -proC + -lac + ) and F 14 (ilv + -argE + ), containing hot points of RecRecF - depending recombination and in increased frequency of chromosome mobilization and integrative suppression of temperature sensitive dna A46 mutation by sexual factor F. In this respect Gam sup(r) 444 mutant resembles rec BC sbs B mutant with RecF - recombination type

123I-5-I-R91150, a new single-photon emission tomography ligand for 5-HT2A receptors: influence of age and gender in healthy subjects

International Nuclear Information System (INIS)

Baeken, C.; D'haenen, H.; Flamen, P.; Bossuyt, A.; Mertens, J.; Terriere, D.; Chavatte, K.; Boumon, R.

1998-01-01

5-HT 2A receptors have been implicated in the pathophysiology of mood disorders and in the therapeutic effect of the so-called atypical antipsychotics. Recently, a new radioiodinated ligand with high affinity and selectivity for serotonin 5-HT 2A receptors, 123 iodinated 4-amino-N-1-[3-(4-fluorophenoxy)propyl-4-methyl-4-piperidinyl] 5-iodo-2-methoxybenzamide ( 123 I-5-I-R91150), has been developed and has been shown to be suitable for single-photon emission tomography (SPET) imaging. In this study the influence of age and gender on the ligand binding was investigated in normal volunteers. One hundred and fifty MBq of 123 I-5-I-R91150 was administered to 26 normal volunteers (13 females and 13 males) with an age range of 23-60 years. SPET imaging was performed with a triple-headed gamma camera. For semi-quantitative analysis, ratios of ligand binding in different regions of interest to the binding in the cerebellum were calculated. Mean ratios of 1.7 were obtained. No gender difference was demonstrated. 5-HT 2A binding was shown to decline with age. Over an age range of 40 years a reduction in ligand binding of 42%±7% was found. These results are in agreement with in vitro and positron emission tomography findings of a decline in 5-HT 2A receptor binding with age. The findings confirm the suitability of 123 I-5-I-R91150 for SPET imaging of 5-HT 2A receptors, and highlight the necessity for age-matched controls in clinical studies. (orig.)

Functional enhancement of AT1R potency in the presence of the TPαR is revealed by a comprehensive 7TM receptor co-expression screen.

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Jonas Tind Hansen

Full Text Available BACKGROUND: Functional cross-talk between seven transmembrane (7TM receptors can dramatically alter their pharmacological properties, both in vitro and in vivo. This represents an opportunity for the development of novel therapeutics that potentially target more specific biological effects while causing fewer adverse events. Although several studies convincingly have established the existence of 7TM receptor cross-talk, little is known about the frequencey and biological significance of this phenomenon. METHODOLOGY/PRINCIPAL FINDINGS: To evaluate the extent of synergism in 7TM receptor signaling, we took a comprehensive approach and co-expressed 123 different 7TM receptors together with the angiotensin II type 1 receptor (AT1R and analyzed how each receptor affected the angiotensin II (AngII response. To monitor the effect we used integrative receptor activation/signaling assay called Receptor Selection and Amplification Technology (R-SAT. In this screen the thromboxane A2α receptor (TPαR was the only receptor which significantly enhanced the AngII-mediated response. The TPαR-mediated enhancement of AngII signaling was significantly reduced when a signaling deficient receptor mutant (TPαR R130V was co-expressed instead of the wild-type TPαR, and was completely blocked both by TPαR antagonists and COX inhibitors inhibiting formation of thromboxane A2 (TXA2. CONCLUSIONS/SIGNIFICANCE: We found a functional enhancement of AT1R only when co-expressed with TPαR, but not with 122 other 7TM receptors. In addition, the TPαR must be functionally active, indicating the AT1R enhancement is mediated by a paracrine mechanism. Since we only found one receptor enhancing AT1R potency, our results suggest that functional augmentation through 7TM receptor cross-talk is a rare event that may require specific conditions to occur.

The phosphatidylinositol-3 kinase pathway is not essential for insulin-like growth factor I receptor-mediated clonogenic radioresistance

International Nuclear Information System (INIS)

Yu, Dong; Watanabe, Hiroshi; Shibuya, Hitoshi; Miura, Masahiko

2002-01-01

The insulin-like growth factor I receptor (IGF-IR) is known to induce clonogenic radioresistance in cells following ionizing irradiation. To explore the downstream signaling pathways, we focused on the phosphatidylinositol-3 kinase (PI3-K) pathway, which is thought to be the primary cell survival signal originating from the receptor. For this purpose, R- cells deficient in the endogenous IGF-IR were used as a recipient of the human IGF-IR with or without mutations at potential PI3-K activation sites: NPXY 950 and Y 1316 XXM. Mutats with double mutation at Y950/Y1316 exhibited not abrogated, but reduced activation of insulin receptor substance-1 (IRS-1), PI3-K, and Akt upon IGF-I stimulation. However, the mutants had the same clonogenic radioresistance as cells with wild type (WT) receptors. Neither wortmannin nor LY294002, specific inhibitors of PI3-K, affected the radioresistance of cells with WT receptors at concentrations specific for PI3-K. Collectively, these results indicate that the PI3-K pathway is not essential for IGF-IR-mediated clonogenic radioresistance. (author)

Metabotropic glutamate receptor I (mGluR1) antagonism impairs cocaine-induced conditioned place preference via inhibition of protein synthesis.

Science.gov (United States)

Yu, Fei; Zhong, Peng; Liu, Xiaojie; Sun, Dalong; Gao, Hai-Qing; Liu, Qing-Song

2013-06-01

Antagonism of group I metabotropic glutamate receptors (mGluR1 and mGluR5) reduces behavioral effects of drugs of abuse, including cocaine. However, the underlying mechanisms remain poorly understood. Activation of mGluR5 increases protein synthesis at synapses. Although mGluR5-induced excessive protein synthesis has been implicated in the pathology of fragile X syndrome, it remains unknown whether group I mGluR-mediated protein synthesis is involved in any behavioral effects of drugs of abuse. We report that group I mGluR agonist DHPG induced more pronounced initial depression of inhibitory postsynaptic currents (IPSCs) followed by modest long-term depression (I-LTD) in dopamine neurons of rat ventral tegmental area (VTA) through the activation of mGluR1. The early component of DHPG-induced depression of IPSCs was mediated by the cannabinoid CB1 receptors, while DHPG-induced I-LTD was dependent on protein synthesis. Western blotting analysis indicates that mGluR1 was coupled to extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin (mTOR) signaling pathways to increase translation. We also show that cocaine conditioning activated translation machinery in the VTA via an mGluR1-dependent mechanism. Furthermore, intra-VTA microinjections of mGluR1 antagonist JNJ16259685 and protein synthesis inhibitor cycloheximide significantly attenuated or blocked the acquisition of cocaine-induced conditioned place preference (CPP) and activation of translation elongation factors. Taken together, these results suggest that mGluR1 antagonism inhibits de novo protein synthesis; this effect may block the formation of cocaine-cue associations and thus provide a mechanism for the reduction in CPP to cocaine.

The TLX-miR-219 cascade regulates neural stem cell proliferation in neurodevelopment and schizophrenia iPSC model.

Science.gov (United States)

Murai, Kiyohito; Sun, Guoqiang; Ye, Peng; Tian, E; Yang, Su; Cui, Qi; Sun, Guihua; Trinh, Daniel; Sun, Olivia; Hong, Teresa; Wen, Zhexing; Kalkum, Markus; Riggs, Arthur D; Song, Hongjun; Ming, Guo-li; Shi, Yanhong

2016-03-11

Dysregulated expression of miR-219, a brain-specific microRNA, has been observed in neurodevelopmental disorders, such as schizophrenia (SCZ). However, its role in normal mammalian neural stem cells (NSCs) and in SCZ pathogenesis remains unknown. We show here that the nuclear receptor TLX, an essential regulator of NSC proliferation and self-renewal, inhibits miR-219 processing. miR-219 suppresses mouse NSC proliferation downstream of TLX. Moreover, we demonstrate upregulation of miR-219 and downregulation of TLX expression in NSCs derived from SCZ patient iPSCs and DISC1-mutant isogenic iPSCs. SCZ NSCs exhibit reduced cell proliferation. Overexpression of TLX or inhibition of miR-219 action rescues the proliferative defect in SCZ NSCs. Therefore, this study uncovers an important role for TLX and miR-219 in both normal neurodevelopment and in SCZ patient iPSC-derived NSCs. Moreover, this study reveals an unexpected role for TLX in regulating microRNA processing, independent of its well-characterized role in transcriptional regulation.

Mutant with diphtheria toxin receptor and acidification function but defective in entry of toxin

International Nuclear Information System (INIS)

Kohno, Kenji; Hayes, H.; Mekada, Eisuke; Uchida, Tsuyoshi

1987-01-01

A mutant of Chinese hamster ovary cells, GE1, that is highly resistant to diphtheria toxin was isolated. The mutant contains 50% ADP-ribosylatable elongation factor 2, but its protein synthesis was not inhibited by the toxin even at concentrations above 100 μg/ml. 125 I-labeled diphtheria toxin was associated with GE1 cells as well as with the parent cells but did not block protein synthesis of GE1 cells even when the cells were exposed to low pH in the presence or absence of NH 4 Cl. The infections of GE1 cells and the parent cells by vesicular stomatitis virus were similar. GE1 cells were cross-resistant to Pseudomonas aeruginosa exotoxin A and so were about 1,000 times more resistant to this toxin than the parent cells. Hybrids of GE1 cells and the parent cells or mutant cells lacking a functional receptor were more sensitive to diphtheria toxin than GE1 cells. These results suggest that entry of diphtheria toxin into cells requires a cellular factor(s) in addition to those involved in receptor function and acidification of endosomes and that GE1 cells do not express this cellular factor. This character is recessive in GE1 cells

Comparison of D2 receptor binding (123I-IBZM) and rCBF (99mTc-HMPAO) in extrapyramidal disorders

International Nuclear Information System (INIS)

Saur, H.B.; Bartenstein, P.; Schober, O.; Oberwittler, C.; Lerch, H.; Masur, H.

1994-01-01

The aim of this SPECT study was to determine whether there is a correlation between rCBF ( 99m Tc-HMPAO) and D2 receptor binding ( 123 I-IBZM) in disorders of the extrapyramidal system and in which situation the 99 MTc-HMPAO scan could predict the outcome of the 123 I-IBZM study. 13 patients with Parkinson's syndrome and 13 patients with hyperkinetic extrapyramidal disorders were studied. In all patients the two SPECT studies were performed within 2-7 days. ROIs were placed over the basal ganglia (BG), the frontal cortex (FC) and the cerebellum (CE). The ratios BG/FC and BG/CE were calculated. In both groups the scatter was lower when the frontal cortex was used as reference region. Among the patients with hyperkinetic extrapyramidal hyperkinetic extrapyramidal disorders the two patients with Huntington's chorea had lower rCBF and D2 receptor binding compared to other hyperkinetic extrapyramidal disorders. There was no correlation between D2 receptor binding and rCBF in the basal ganglia. The 99 MTc-HMPAO studies did not provide clinically useful information, except in Huntington's chorea. (orig.) [de

Glycine receptor mutants of the mouse: what are possible routes of inhibitory compensation?

Directory of Open Access Journals (Sweden)

Natascha eSchaefer

2012-10-01

Full Text Available Defects in glycinergic inhibition result in a complex neuromotor disorder in humans known as hyperekplexia (OMIM 149400 with similar phenotypes in rodents characterized by an exaggerated startle reflex and hypertonia. Analogous to genetic defects in humans, single point mutations, microdeletions, or insertions in the Glra1 gene but also in the Glrb gene underlie the pathology in mice. The mutations either localized in the α (spasmodic, oscillator, cincinnati, Nmf11 or the β (spastic subunit of the GlyR are much less tolerated in mice than in humans, leaving the question for the existence of different regulatory elements of the pathomechanisms in humans and rodents. In addition to the spontaneous mutations, new insights into understanding of the regulatory pathways in hyperekplexia or glycine encephalopathy arose from the constantly increasing number of knock-out as well as knock-in mutants of GlyRs. Over the last five years, various efforts using in vivo whole cell recordings provided a detailed analysis of the kinetic parameters underlying glycinergic dysfunction. Presynaptic compensation as well as postsynaptic compensatory mechanisms in these mice by other GlyR subunits or GABAA receptors, and the role of extra-synaptic GlyRs is still a matter of debate. A recent study on the mouse mutant oscillator, displayed a novel aspect for compensation of functionality by complementation of receptor domains that fold independently. This review focuses on defects in glycinergic neurotransmission in mice discussed with the background of human hyperekplexia en route to strategies of compensation.

Frequency of mutant T lymphocytes defective in the expression of the T-cell antigen receptor gene among radiation-exposed people

International Nuclear Information System (INIS)

Kyoizumi, Seishi; Umeki, Shigeko; Akiyama, Mitoshi

1991-06-01

The frequency of mutant T lymphocytes defective in T-cell receptor gene (α or β) expression was measured using the two-color flow cytometric technique. Results for a total of 203 atomic bomb survivors, 78 of whom were proximally exposed (DS86 doses of ≥ 1.5 Gy) and 125 of whom were distally exposed (DS86 doses of 228 Th formerly used for radiodiagnosis. In addition, thyroid disease patients treated with 131 I showed a dose-related increase of mutant frequency. It was suggested that the present T-cell receptor mutation assay has a unique characteristic as a biological dosimeter for the measurement of recent exposures to genotoxic agents. (author)

Concurrent Targeting of KRAS and AKT by MiR-4689 Is a Novel Treatment Against Mutant KRAS Colorectal Cancer

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Masayuki Hiraki

2015-01-01

Full Text Available KRAS mutations are a major cause of drug resistance to molecular-targeted therapies. Aberrant epidermal growth factor receptor (EGFR signaling may cause dysregulation of microRNA (miRNA and gene regulatory networks, which leads to cancer initiation and progression. To address the functional relevance of miRNAs in mutant KRAS cancers, we transfected exogenous KRASG12V into human embryonic kidney 293 and MRC5 cells with wild-type KRAS and BRAF genes, and we comprehensively profiled the dysregulated miRNAs. The result showed that mature miRNA oligonucleotide (miR-4689, one of the significantly down-regulated miRNAs in KRASG12V overexpressed cells, was found to exhibit a potent growth-inhibitory and proapoptotic effect both in vitro and in vivo. miR-4689 expression was significantly down-regulated in cancer tissues compared to normal mucosa, and it was particularly decreased in mutant KRAS CRC tissues. miR-4689 directly targets v-ki-ras2 kirsten rat sarcoma viral oncogene homolog (KRAS and v-akt murine thymoma viral oncogene homolog 1(AKT1, key components of two major branches in EGFR pathway, suggesting KRAS overdrives this signaling pathway through inhibition of miR-4689. Overall, this study provided additional evidence that mutant KRAS functions as a broad regulator of the EGFR signaling cascade by inhibiting miR-4689, which negatively regulates both RAS/mitogen-activated protein kinase (MAPK and phosphoinositide 3-kinase (PI3K/AKT pathways. These activities indicated that miR-4689 may be a promising therapeutic agent in mutant KRAS CRC.

Mutant forms of Escherichia coli protein L25 unable to bind to 5S rRNA are incorporated efficiently into the ribosome in vivo.

Science.gov (United States)

Anikaev, A Y; Korepanov, A P; Korobeinikova, A V; Kljashtorny, V G; Piendl, W; Nikonov, S V; Garber, M B; Gongadze, G M

2014-08-01

5S rRNA-binding ribosomal proteins of the L25 family are an evolutional acquisition of bacteria. Earlier we showed that (i) single replacements in the RNA-binding module of the protein of this family result in destabilization or complete impossibility to form a complex with 5S rRNA in vitro; (ii) ΔL25 ribosomes of Escherichia coli are less efficient in protein synthesis in vivo than the control ribosomes. In the present work, the efficiency of incorporation of the E. coli protein L25 with mutations in the 5S rRNA-binding region into the ribosome in vivo was studied. It was found that the mutations in L25 that abolish its ability to form the complex with free 5S rRNA do not prevent its correct and efficient incorporation into the ribosome. This is supported by the fact that even the presence of a very weakly retained mutant form of the protein in the ribosome has a positive effect on the activity of the translational machinery in vivo. All this suggests the existence of an alternative incorporation pathway for this protein into the ribosome, excluding the preliminary formation of the complex with 5S rRNA. At the same time, the stable L25-5S rRNA contact is important for the retention of the protein within the ribosome, and the conservative amino acid residues of the RNA-binding module play a key role in this.

Distinct human and mouse membrane trafficking systems for sweet taste receptors T1r2 and T1r3.

Science.gov (United States)

Shimizu, Madoka; Goto, Masao; Kawai, Takayuki; Yamashita, Atsuko; Kusakabe, Yuko

2014-01-01

The sweet taste receptors T1r2 and T1r3 are included in the T1r taste receptor family that belongs to class C of the G protein-coupled receptors. Heterodimerization of T1r2 and T1r3 is required for the perception of sweet substances, but little is known about the mechanisms underlying this heterodimerization, including membrane trafficking. We developed tagged mouse T1r2 and T1r3, and human T1R2 and T1R3 and evaluated membrane trafficking in human embryonic kidney 293 (HEK293) cells. We found that human T1R3 surface expression was only observed when human T1R3 was coexpressed with human T1R2, whereas mouse T1r3 was expressed without mouse T1r2 expression. A domain-swapped chimera and truncated human T1R3 mutant showed that the Venus flytrap module and cysteine-rich domain (CRD) of human T1R3 contain a region related to the inhibition of human T1R3 membrane trafficking and coordinated regulation of human T1R3 membrane trafficking. We also found that the Venus flytrap module of both human T1R2 and T1R3 are needed for membrane trafficking, suggesting that the coexpression of human T1R2 and T1R3 is required for this event. These results suggest that the Venus flytrap module and CRD receive taste substances and play roles in membrane trafficking of human T1R2 and T1R3. These features are different from those of mouse receptors, indicating that human T1R2 and T1R3 are likely to have a novel membrane trafficking system.

Cloning and primary immunological study of TGF-β1 and its receptors TβR I /TβR II in tilapia(Oreochromis niloticus).

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Zhan, Xu-liang; Ma, Tai-yang; Wu, Jin-ying; Yi, Li-yuan; Wang, Jing-yuan; Gao, Xiao-ke; Li, Wen-sheng

2015-07-01

The transforming growth factor β (TGF-β) superfamily plays critical roles in tumor suppression, cell proliferation and differentiation, tissue morphogenesis, lineage determination, cell migration and apoptosis. Recently, TGF-β1, one important member of TGF-β superfamily, is suggested as an immune regulator in the teleost. In this study, we cloned the cDNAs of TGF-β1 and its receptors, TβR I and TβR II (including three isoforms) from tilapia (Genbank accession numbers: KP754231- KP754235). A tissue distribution profile analysis indicated that TGF-β1 was highly expressed in the head kidney, gill, spleen, kidney and PBLs (peripheral blood leukocytes); TβR I only showed considerable expression in the liver; and TβR II-2 was highly expressed in the kidney, gill, liver, head kidney and heart. We determined that the mRNA expressions of TGF-β and TβR I /TβR II-2 were significantly increased in tilapia head kidney and spleen leukocytes by the stimulation of Lipopolysaccharide (LPS) or Poly I: C. We also examined their expressions in the spleen and head kidney of tilapia after IP injection of streptococcus agalactiae. The results showed that the mRNA expressions of these three genes all increased in the head kidney as early as 6 h post infection, and in the spleen 3 d post infection. In addition, the protein level of TGF-β1 was also up-regulated in the head kidney and the spleen after infection. Taken together, our data indicate that the TGF-β1-TβR I /TβR II-2 system functions potentially in tilapia immune system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Calcium imaging with genetically encoded sensor Case12: Facile analysis of α7/α9 nAChR mutants.

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Irina Shelukhina

Full Text Available Elucidation of the structural basis of pharmacological differences for highly homologous α7 and α9 nicotinic acetylcholine receptors (nAChRs may shed light on their involvement in different physiological functions and diseases. Combination of site-directed mutagenesis and electrophysiology is a powerful tool to pinpoint the key amino-acid residues in the receptor ligand-binding site, but for α7 and α9 nAChRs it is complicated by their poor expression and fast desensitization. Here, we probed the ligand-binding properties of α7/α9 nAChR mutants by a proposed simple and fast calcium imaging method. The method is based on transient co-expression of α7/α9 nAChR mutants in neuroblastoma cells together with Ric-3 or NACHO chaperones and Case12 fluorescent calcium ion sensor followed by analysis of their pharmacology using a fluorescence microscope or a fluorometric imaging plate reader (FLIPR with a GFP filter set. The results obtained were confirmed by electrophysiology and by calcium imaging with the conventional calcium indicator Fluo-4. The affinities for acetylcholine and epibatidine were determined for human and rat α7 nAChRs, and for their mutants with homologous residues of α9 nAChR incorporated at positions 117-119, 184, 185, 187, and 189, which are anticipated to be involved in ligand binding. The strongest decrease in the affinity was observed for mutations at positions 187 and 119. The L119D mutation of α7 nAChR, showing a larger effect for epibatidine than for acetylcholine, may implicate this position in pharmacological differences between α7 and α9 nAChRs.

The octopamine receptor Octβ2R regulates ovulation in Drosophila melanogaster.

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Junghwa Lim

Full Text Available Oviposition is induced upon mating in most insects. Ovulation is a primary step in oviposition, representing an important target to control insect pests and vectors, but limited information is available on the underlying mechanism. Here we report that the beta adrenergic-like octopamine receptor Octβ2R serves as a key signaling molecule for ovulation and recruits protein kinase A and Ca(2+/calmodulin-sensitive kinase II as downstream effectors for this activity. We found that the octβ2r homozygous mutant females are sterile. They displayed normal courtship, copulation, sperm storage and post-mating rejection behavior but were unable to lay eggs. We have previously shown that octopamine neurons in the abdominal ganglion innervate the oviduct epithelium. Consistently, restored expression of Octβ2R in oviduct epithelial cells was sufficient to reinstate ovulation and full fecundity in the octβ2r mutant females, demonstrating that the oviduct epithelium is a major site of Octβ2R's function in oviposition. We also found that overexpression of the protein kinase A catalytic subunit or Ca(2+/calmodulin-sensitive protein kinase II led to partial rescue of octβ2r's sterility. This suggests that Octβ2R activates cAMP as well as additional effectors including Ca(2+/calmodulin-sensitive protein kinase II for oviposition. All three known beta adrenergic-like octopamine receptors stimulate cAMP production in vitro. Octβ1R, when ectopically expressed in the octβ2r's oviduct epithelium, fully reinstated ovulation and fecundity. Ectopically expressed Octβ3R, on the other hand, partly restored ovulation and fecundity while OAMB-K3 and OAMB-AS that increase Ca(2+ levels yielded partial rescue of ovulation but not fecundity deficit. These observations suggest that Octβ2R have distinct signaling capacities in vivo and activate multiple signaling pathways to induce egg laying. The findings reported here narrow the knowledge gap and offer insight into novel

Defective Glycinergic Synaptic Transmission in Zebrafish Motility Mutants

OpenAIRE

Hirata, Hiromi; Carta, Eloisa; Yamanaka, Iori; Harvey, Robert J.; Kuwada, John Y.

2010-01-01

Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo) mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR) β subunit genes. These mutants exhibit a loss of glycinergic synaptic ...

Role of ELA region in auto-activation of mutant KIT receptor: a molecular dynamics simulation insight.

Science.gov (United States)

Purohit, Rituraj

2014-01-01

KIT receptor is the prime target in gastrointestinal stromal tumor (GISTs) therapy. Second generation inhibitor, Sunitinib, binds to an inactivated conformation of KIT receptor and stabilizes it in order to prevent tumor formation. Here, we investigated the dynamic behavior of wild type and mutant D816H KIT receptor, and emphasized the extended A-loop (EAL) region (805-850) by conducting molecular dynamics simulation (∼100 ns). We analyzed different properties such as root mean square cutoff or deviation, root mean square fluctuation, radius of gyration, solvent-accessible surface area, hydrogen bonding network analysis, and essential dynamics. Apart from this, clustering and cross-correlation matrix approach was used to explore the conformational space of the wild type and mutant EAL region of KIT receptor. Molecular dynamics analysis indicated that mutation (D816H) was able to alter intramolecular hydrogen bonding pattern and affected the structural flexibility of EAL region. Moreover, flexible secondary elements, specially, coil and turns were dominated in EAL region of mutant KIT receptor during simulation. This phenomenon increased the movement of EAL region which in turn helped in shifting the equilibrium towards the active kinase conformation. Our atomic investigation of mutant KIT receptor which emphasized on EAL region provided a better insight into the understanding of Sunitinib resistance mechanism of KIT receptor and would help to discover new therapeutics for KIT-based resistant tumor cells in GIST therapy.

mTORC2 promotes type I insulin-like growth factor receptor and insulin receptor activation through the tyrosine kinase activity of mTOR.

Science.gov (United States)

Yin, Yancun; Hua, Hui; Li, Minjing; Liu, Shu; Kong, Qingbin; Shao, Ting; Wang, Jiao; Luo, Yuanming; Wang, Qian; Luo, Ting; Jiang, Yangfu

2016-01-01

Mammalian target of rapamycin (mTOR) is a core component of raptor-mTOR (mTORC1) and rictor-mTOR (mTORC2) complexes that control diverse cellular processes. Both mTORC1 and mTORC2 regulate several elements downstream of type I insulin-like growth factor receptor (IGF-IR) and insulin receptor (InsR). However, it is unknown whether and how mTOR regulates IGF-IR and InsR themselves. Here we show that mTOR possesses unexpected tyrosine kinase activity and activates IGF-IR/InsR. Rapamycin induces the tyrosine phosphorylation and activation of IGF-IR/InsR, which is largely dependent on rictor and mTOR. Moreover, mTORC2 promotes ligand-induced activation of IGF-IR/InsR. IGF- and insulin-induced IGF-IR/InsR phosphorylation is significantly compromised in rictor-null cells. Insulin receptor substrate (IRS) directly interacts with SIN1 thereby recruiting mTORC2 to IGF-IR/InsR and promoting rapamycin- or ligand-induced phosphorylation of IGF-IR/InsR. mTOR exhibits tyrosine kinase activity towards the general tyrosine kinase substrate poly(Glu-Tyr) and IGF-IR/InsR. Both recombinant mTOR and immunoprecipitated mTORC2 phosphorylate IGF-IR and InsR on Tyr1131/1136 and Tyr1146/1151, respectively. These effects are independent of the intrinsic kinase activity of IGF-IR/InsR, as determined by assays on kinase-dead IGF-IR/InsR mutants. While both rictor and mTOR immunoprecitates from rictor(+/+) MCF-10A cells exhibit tyrosine kinase activity towards IGF-IR and InsR, mTOR immunoprecipitates from rictor(-/-) MCF-10A cells do not induce IGF-IR and InsR phosphorylation. Phosphorylation-deficient mutation of residue Tyr1131 in IGF-IR or Tyr1146 in InsR abrogates the activation of IGF-IR/InsR by mTOR. Finally, overexpression of rictor promotes IGF-induced cell proliferation. Our work identifies mTOR as a dual-specificity kinase and clarifies how mTORC2 promotes IGF-IR/InsR activation.

Impaired associative fear learning in mice with complete loss or haploinsufficiency of AMPA GluR1 receptors

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Michael Feyder

2007-12-01

Full Text Available There is compelling evidence that L-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA glutamate receptors containing the GluR1 subunit contribute to the molecular mechanisms associated with learning. AMPA GluR1 glutamate receptor knockout mice (KO exhibit abnormal hippocampal and amygdala plasticity, and deficits on various assays for cognition including Pavlovian fear conditioning. Here we examined associative fear learning in mice with complete absence (KO or partial loss (heterozygous mutant, HET of GluR1 on multiple fear conditioning paradigms. After multi-trial delay or trace conditioning, KO displayed impaired tone and context fear recall relative to WT, whereas HET were normal. After one-trial delay conditioning, both KO and HET showed impaired tone and context recall. HET and KO showed normal nociceptive sensitivity in the hot plate and tail flick tests. These data demonstrate that the complete absence of GluR1 subunit-containing receptors prevents the formation of associative fear memories, while GluR1 haploinsufficiency is sufficient to impair one-trial fear learning. These findings support growing evidence of a major role for GluR1-containing AMPA receptors in amygdalamediated forms of learning and memory.

Enhancing cellulase production by overexpression of xylanase regulator protein gene, xlnR, in Talaromyces cellulolyticus cellulase hyperproducing mutant strain.

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Okuda, Naoyuki; Fujii, Tatsuya; Inoue, Hiroyuki; Ishikawa, Kazuhiko; Hoshino, Tamotsu

2016-10-01

We obtained strains with the xylanase regulator gene, xlnR, overexpressed (HXlnR) and disrupted (DXlnR) derived from Talaromyces cellulolyticus strain C-1, which is a cellulase hyperproducing mutant. Filter paper degrading enzyme activity and cellobiohydrolase I gene expression was the highest in HXlnR, followed by C-1 and DXlnR. These results indicate that the enhancement of cellulase productivity was succeeded by xlnR overexpression.

Ligand-independent Thrombopoietin Mutant Receptor Requires Cell Surface Localization for Endogenous Activity*

OpenAIRE

Marty, Caroline; Chaligné, Ronan; Lacout, Catherine; Constantinescu, Stefan N.; Vainchenker, William; Villeval, Jean-Luc

2009-01-01

The activating W515L mutation in the thrombopoietin receptor (MPL) has been identified in primary myelofibrosis and essential thrombocythemia. MPL belongs to a subset of the cytokine receptor superfamily that requires the JAK2 kinase for signaling. We examined whether the ligand-independent MPLW515L mutant could signal intracellularly. Addition of the endoplasmic reticulum (ER) retention KDEL sequence to the receptor C terminus efficiently locked MPLW515L within its na...

Structural analogs of human insulin-like growth factor I with reduced affinity for serum binding proteins and the type 2 insulin-like growth factor receptor

International Nuclear Information System (INIS)

Bayne, M.L.; Applebaum, J.; Chicchi, G.G.; Hayes, N.S.; Green, B.G.; Cascieri, M.A.

1988-01-01

Four structural analogs of human insulin-like growth factor I (hIGF-I) have been prepared by site-directed mutagenesis of a synthetic IGF-I gene and subsequent expression and purification of the mutant protein from the conditioned media of transformed yeast. [Phe -1 , Val 1 , Asn 2 , Gln 3 , His 4 , Ser 8 , His 9 , Glu 12 , Tyr 15 , Leu 16 ]IGF-I (B-chain mutant), in which the first 16 amino acids of hIGF-I were replaced with the first 17 amino acids of the B-chain of insulin, has >1000-, 100-, and 2-fold reduced potency for human serum binding proteins, the rat liver type 2 IGF receptor, and the human placental type 1 IGF receptor, respectively. The B-chain mutant also has 4-fold increased affinity for the human placental insulin receptor. [Gln 3 , Ala 4 ] IGF-I has 4-fold reduced affinity for human serum binding proteins, but is equipotent to hIGF-I at the types 1 and 2 IGF and insulin receptors. [Tyr 15 , Leu 16 ] IGH-I has 4-fold reduced affinity for human serum binding proteins and 10-fold increased affinity for the insulin receptor. The peptide in which these four-point mutations are combined, [Gln 3 , Ala 4 , Tyr 15 ,Leu 16 ]IGF-I, has 600-fold reduced affinity for the serum binding proteins. All four of these mutants stimulate DNA synthesis in the rat vascular smooth muscle cell line A10 with potencies reflecting their potency at the type 1 IGF receptor. These studies identify some of the domains of hIGF-I which are responsible for maintaining high affinity binding with the serum binding protein and the type 2 IGF receptor. In addition, These peptides will be useful in defining the role of the type 2 IGF receptor and serum binding proteins in the physiological actions of hIGF-I

Inactivation of JAK2/STAT3 Signaling Axis and Downregulation of M1 mAChR Cause Cognitive Impairment in klotho Mutant Mice, a Genetic Model of Aging

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Park, Seok-Joo; Shin, Eun-Joo; Min, Sun Seek; An, Jihua; Li, Zhengyi; Hee Chung, Yoon; Hoon Jeong, Ji; Bach, Jae-Hyung; Nah, Seung-Yeol; Kim, Won-Ki; Jang, Choon-Gon; Kim, Yong-Sun; Nabeshima, Yo-ichi; Nabeshima, Toshitaka; Kim, Hyoung-Chun

2013-01-01

We previously reported cognitive dysfunction in klotho mutant mice. In the present study, we further examined novel mechanisms involved in cognitive impairment in these mice. Significantly decreased janus kinase 2 (JAK2) and signal transducer and activator of transcription3 (STAT3) phosphorylation were observed in the hippocampus of klotho mutant mice. A selective decrease in protein expression and binding density of the M1 muscarinic cholinergic receptor (M1 mAChR) was observed in these mice. Cholinergic parameters (ie, acetylcholine (ACh), choline acetyltransferase (ChAT), and acetylcholinesterase (AChE)) and NMDAR-dependent long-term potentiation (LTP) were significantly impaired in klotho mutant mice. McN-A-343 (McN), an M1 mAChR agonist, significantly attenuated these impairments. AG490 (AG), a JAK2 inhibitor, counteracted the attenuating effects of McN, although AG did not significantly alter the McN-induced effect on AChE. Furthermore, AG significantly inhibited the attenuating effects of McN on decreased NMDAR-dependent LTP, protein kinase C βII, p-ERK, p-CREB, BDNF, and p-JAK2/p-STAT3-expression in klotho mutant mice. In addition, k252a, a BDNF receptor tyrosine kinase B (TrkB) inhibitor, significantly counteracted McN effects on decreased ChAT, ACh, and M1 mAChR and p-JAK2/p-STAT3 expression. McN-induced effects on cognitive impairment in klotho mutant mice were consistently counteracted by either AG or k252a. Our results suggest that inactivation of the JAK2/STAT3 signaling axis and M1 mAChR downregulation play a critical role in cognitive impairment observed in klotho mutant mice. PMID:23389690

The inability of Bacillus licheniformis perR mutant to grow is mainly due to the lack of PerR-mediated fur repression.

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Kim, Jung-Hoon; Yang, Yoon-Mo; Ji, Chang-Jun; Ryu, Su-Hyun; Won, Young-Bin; Ju, Shin-Yeong; Kwon, Yumi; Lee, Yeh-Eun; Youn, Hwan; Lee, Jin-Won

2017-06-01

PerR, a member of Fur family protein, is a metal-dependent H 2 O 2 sensing transcription factor that regulates genes involved in peroxide stress response. Industrially important bacterium Bacillus licheniformis contains three PerR-like proteins (PerR BL , PerR2, and PerR3) compared to its close relative Bacillus subtilis. Interestingly, unlike other bacteria including B. subtilis, no authentic perR BL null mutant could be established for B. licheniformis. Thus, we constructed a conditional perR BL mutant using a xylose-inducible promoter, and investigated the genes under the control of PerR BL . PerR BL regulon genes include katA, mrgA, ahpC, pfeT, hemA, fur, and perR as observed for PerR BS . However, there is some variation in the expression levels of fur and hemA genes between B. subtilis and B. licheniformis in the derepressed state. Furthermore, katA, mrgA, and ahpC are strongly induced, whereas the others are only weakly or not induced by H 2 O 2 treatment. In contrast to the B. subtilis perR null mutant which frequently gives rise to large colony phenotype mainly due to the loss of katA, the suppressors of B. licheniformis perR mutant, which can form colonies on LB agar, were all catalase-positive. Instead, many of the suppressors showed increased levels of siderophore production, suggesting that the suppressor mutation is linked to the fur gene. Consistent with this, perR fur double mutant could grow on LB agar without Fe supplementation, whereas perR katA double mutant could only grow on LB agar with Fe supplementation. Taken together, our data suggest that in B. licheniformis, despite the similarity in PerR BL and PerR BS regulon genes, perR is an essential gene required for growth and that the inability of perR null mutant to grow is mainly due to elevated expression of Fur.

Phosphoribosylpyrophosphate (PRPP)-less mutants of <i>Escherichia colii>

DEFF Research Database (Denmark)

Hove-Jensen, Bjarne

1989-01-01

A DNA fragment encoding kanamycin resistance was inserted in vitro into a plasmid-borne prs gene encoding phosphoribosylpyrophosphate synthetase of Escherichia coli. The resulting plasmids were subsequently transferred to the chromosome by homologous recombination and the haploid strains prs-3::Kan......R and prs-4::KanR were obtained. These strains were fully viable, but required guanosine, uridine, histidine, tryptophan and nicotinamide mononucleotide. There was no phosphoribosylpyrophosphate synthetase activity or phosphoribosylpyrophosphate pool in the mutant strains. These results show...

Kinetics of leptin binding to the Q223R leptin receptor.

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Hans Verkerke

Full Text Available Studies in human populations and mouse models of disease have linked the common leptin receptor Q223R mutation to obesity, multiple forms of cancer, adverse drug reactions, and susceptibility to enteric and respiratory infections. Contradictory results cast doubt on the phenotypic consequences of this variant. We set out to determine whether the Q223R substitution affects leptin binding kinetics using surface plasmon resonance (SPR, a technique that allows sensitive real-time monitoring of protein-protein interactions. We measured the binding and dissociation rate constants for leptin to the extracellular domain of WT and Q223R murine leptin receptors expressed as Fc-fusion proteins and found that the mutant receptor does not significantly differ in kinetics of leptin binding from the WT leptin receptor. (WT: ka 1.76×106±0.193×106 M-1 s-1, kd 1.21×10-4±0.707×10-4 s-1, KD 6.47×10-11±3.30×10-11 M; Q223R: ka 1.75×106±0.0245×106 M-1 s-1, kd 1.47×10-4±0.0505×10-4 s-1, KD 8.43×10-11±0.407×10-11 M. Our results support earlier findings that differences in affinity and kinetics of leptin binding are unlikely to explain mechanistically the phenotypes that have been linked to this common genetic variant. Future studies will seek to elucidate the mechanism by which this mutation influences susceptibility to metabolic, infectious, and malignant pathologies.

Molecular mechanism of action of pharmacoperone rescue of misrouted GPCR mutants: the GnRH receptor.

Science.gov (United States)

Janovick, Jo Ann; Patny, Akshay; Mosley, Ralph; Goulet, Mark T; Altman, Michael D; Rush, Thomas S; Cornea, Anda; Conn, P Michael

2009-02-01

The human GnRH receptor (hGnRHR), a G protein-coupled receptor, is a useful model for studying pharmacological chaperones (pharmacoperones), drugs that rescue misfolded and misrouted protein mutants and restore them to function. This technique forms the basis of a therapeutic approach of rescuing mutants associated with human disease and restoring them to function. The present study relies on computational modeling, followed by site-directed mutagenesis, assessment of ligand binding, effector activation, and confocal microscopy. Our results show that two different chemical classes of pharmacoperones act to stabilize hGnRHR mutants by bridging residues D(98) and K(121). This ligand-mediated bridge serves as a surrogate for a naturally occurring and highly conserved salt bridge (E(90)-K(121)) that stabilizes the relation between transmembranes 2 and 3, which is required for passage of the receptor through the cellular quality control system and to the plasma membrane. Our model was used to reveal important pharmacophoric features, and then identify a novel chemical ligand, which was able to rescue a D(98) mutant of the hGnRHR that could not be rescued as effectively by previously known pharmacoperones.

Tumor therapy with 125I-octreotide and 125I-UdR

International Nuclear Information System (INIS)

Fan, W.; Zhu, R.; Yang, C.; Sun, J.J.; Xu, Y.J.; Zhang, Y.J.; Wu, M.J.; Wang, D.J.

2005-01-01

Purpose: To determine the tumor cell damage effect with Auger-electron emitter 125 I in different chemical states. Methods: (1) [Tyr 3 ] octreotide (TOC) and UdR are labeled with 125 I,respectively. (2) Receptor analysis of 125 I-TOC on small cell lung cancer (SCLC) NCI-H446 cell lines is performed comparing with normal lymph cells. NCI-H446 cells added various dose of 125 I-TOC are incubated for different time with 125 I-Nal and non-labeled TOC as control. The capacity of NCI-H446 cell lines bound and internalization of 125 I TOC are determined. The radiation damage of tumor cells is measured by MTF methods. (3) The killing effects of 125 I-UdR in human pancreatic cancer cell line Bax-Pc and Sca-BER bladder carcinoma cells are evaluated with the similar methods. I-UdR penetrating into the Sca-BER cell nucleus is observed with confocal microscope. The grow suppression and clonogenic formation of Sca-BER cells after incubation with 125 I-UdR are analyzed. Proliferation fraction and S phase cell fraction of Sca-BER cell added 125 I-UdR is measured with flow cytometric analysis. Results: (1) Kd=(0.56∼2.0) x 10 -11 mol/L and B max =(1.17∼2.0) x 10 5 cell site are obtained by receptor analysis of 125 I-TOC on NCI-H446 cells. Comparatively, the difference between total binding and non-specific binding is low and there is no saturation of specific binding for normal lymphocyte. About 50% of 125 I-TOC is internalized into the NCI-H446 cell nucleus at 24h after incubation. The damige of NCI-H446 cells by 125 I-TOC is clearly observed. (2) The penetration amount of 125 I-UdR into cell nucleus increases with the incubate time when the concentration of 125 I-UdR is in the range of 10∼500 kBq/mL and reaches the peak fraction of 94% at 36 h after incubation. The radioactivity of 125 I-UdR is then achieved equelibration and no more increased with time. The linear correlation with γ=0.867∼0.978 between the concentration of 125 I-UdR in cell nucleus and the incubation time

Manipulation of Very Few Receptor Discriminator Residues Greatly Enhances Receptor Specificity of Non-visual Arrestins*

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Gimenez, Luis E.; Vishnivetskiy, Sergey A.; Baameur, Faiza; Gurevich, Vsevolod V.

2012-01-01

Based on the identification of residues that determine receptor selectivity of arrestins and the analysis of the evolution in the arrestin family, we introduced 10 mutations of “receptor discriminator” residues in arrestin-3. The recruitment of these mutants to M2 muscarinic (M2R), D1 (D1R) and D2 (D2R) dopamine, and β2-adrenergic receptors (β2AR) was assessed using bioluminescence resonance energy transfer-based assays in cells. Seven of 10 mutations differentially affected arrestin-3 binding to individual receptors. D260K and Q262P reduced the binding to β2AR, much more than to other receptors. The combination D260K/Q262P virtually eliminated β2AR binding while preserving the interactions with M2R, D1R, and D2R. Conversely, Y239T enhanced arrestin-3 binding to β2AR and reduced the binding to M2R, D1R, and D2R, whereas Q256Y selectively reduced recruitment to D2R. The Y239T/Q256Y combination virtually eliminated the binding to D2R and reduced the binding to β2AR and M2R, yielding a mutant with high selectivity for D1R. Eleven of 12 mutations significantly changed the binding to light-activated phosphorhodopsin. Thus, manipulation of key residues on the receptor-binding surface modifies receptor preference, enabling the construction of non-visual arrestins specific for particular receptor subtypes. These findings pave the way to the construction of signaling-biased arrestins targeting the receptor of choice for research or therapeutic purposes. PMID:22787152

Manipulation of very few receptor discriminator residues greatly enhances receptor specificity of non-visual arrestins.

Science.gov (United States)

Gimenez, Luis E; Vishnivetskiy, Sergey A; Baameur, Faiza; Gurevich, Vsevolod V

2012-08-24

Based on the identification of residues that determine receptor selectivity of arrestins and the analysis of the evolution in the arrestin family, we introduced 10 mutations of "receptor discriminator" residues in arrestin-3. The recruitment of these mutants to M2 muscarinic (M2R), D1 (D1R) and D2 (D2R) dopamine, and β(2)-adrenergic receptors (β(2)AR) was assessed using bioluminescence resonance energy transfer-based assays in cells. Seven of 10 mutations differentially affected arrestin-3 binding to individual receptors. D260K and Q262P reduced the binding to β(2)AR, much more than to other receptors. The combination D260K/Q262P virtually eliminated β(2)AR binding while preserving the interactions with M2R, D1R, and D2R. Conversely, Y239T enhanced arrestin-3 binding to β(2)AR and reduced the binding to M2R, D1R, and D2R, whereas Q256Y selectively reduced recruitment to D2R. The Y239T/Q256Y combination virtually eliminated the binding to D2R and reduced the binding to β(2)AR and M2R, yielding a mutant with high selectivity for D1R. Eleven of 12 mutations significantly changed the binding to light-activated phosphorhodopsin. Thus, manipulation of key residues on the receptor-binding surface modifies receptor preference, enabling the construction of non-visual arrestins specific for particular receptor subtypes. These findings pave the way to the construction of signaling-biased arrestins targeting the receptor of choice for research or therapeutic purposes.

Receptor type I and type II binding regions and the peptidyl-prolyl isomerase site of cyclophilin B are required for enhancement of T-lymphocyte adhesion to fibronectin.

Science.gov (United States)

Carpentier, Mathieu; Allain, Fabrice; Slomianny, Marie-Christine; Durieux, Sandrine; Vanpouille, Christophe; Haendler, Bernard; Spik, Geneviève

2002-04-23

Cyclophilin B (CyPB), a cyclosporin A (CsA) binding protein, interacts with two types of binding sites at the surface of T-lymphocytes. The type I sites correspond to functional receptors involved in endocytosis and the type II sites to sulfated glycosaminoglycans (GAGs). Mutational analysis of CyPB has revealed that W128, which is part of the CsA-binding pocket, is implicated in the binding to the functional type I receptors and that two amino acid clusters located in the N-terminus ensure the binding to GAGs. The peptidyl-prolyl isomerase activity of CyPB is not required for receptor binding. We have recently demonstrated that CyPB enhances adhesion of peripheral blood T-lymphocytes to fibronectin, a component of the extracellular matrix. We intended to identify additional amino acids involved in the binding of CyPB to its functional type I receptor and to determine regions responsible for the stimulation of peripheral blood T-lymphocyte adhesion. We determined that residues R76, G77, K132, D155, and D158 of the calcineurin (CN) interacting region were implicated in the recognition of type I receptor but not of GAGs. We also found that two different changes in the N-terminal extension that abated binding to GAGs prevented adhesion of peripheral blood T-lymphocytes to coated CyPB, whereas abbrogation of the PPIase activity had no effect. On the other hand, the adhesion of peripheral blood T-lymphocytes to coated fibronectin was not stimulated by CyPB mutants devoid of either type I receptor or GAGs binding activity or by mutants of the PPIase site. Altogether, the results demonstrate that different regions of CyPB are involved in peripheral blood T-lymphocyte activation and imply a novel important physiological function for peptidyl-prolyl isomerase activity.

A novel Arabidopsis CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) mutant with enhanced pathogen-induced cell death and altered receptor processing.

Science.gov (United States)

Petutschnig, Elena K; Stolze, Marnie; Lipka, Ulrike; Kopischke, Michaela; Horlacher, Juliane; Valerius, Oliver; Rozhon, Wilfried; Gust, Andrea A; Kemmerling, Birgit; Poppenberger, Brigitte; Braus, Gerhard H; Nürnberger, Thorsten; Lipka, Volker

2014-12-01

Plants detect pathogens by sensing microbe-associated molecular patterns (MAMPs) through pattern recognition receptors. Pattern recognition receptor complexes also have roles in cell death control, but the underlying mechanisms are poorly understood. Here, we report isolation of cerk1-4, a novel mutant allele of the Arabidopsis chitin receptor CERK1 with enhanced defense responses. We identified cerk1-4 in a forward genetic screen with barley powdery mildew and consequently characterized it by pathogen assays, mutant crosses and analysis of defense pathways. CERK1 and CERK1-4 proteins were analyzed biochemically. The cerk1-4 mutation causes an amino acid exchange in the CERK1 ectodomain. Mutant plants maintain chitin signaling capacity but exhibit hyper-inducible salicylic acid concentrations and deregulated cell death upon pathogen challenge. In contrast to chitin signaling, the cerk1-4 phenotype does not require kinase activity and is conferred by the N-terminal part of the receptor. CERK1 undergoes ectodomain shedding, a well-known process in animal cell surface proteins. Wild-type plants contain the full-length CERK1 receptor protein as well as a soluble form of the CERK1 ectodomain, whereas cerk1-4 plants lack the N-terminal shedding product. Our work suggests that CERK1 may have a chitin-independent role in cell death control and is the first report of ectodomain shedding in plants. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

KB-R7943, an inhibitor of the reverse Na+/Ca2+ exchanger, blocks N-methyl-D-aspartate receptor and inhibits mitochondrial complex I

Science.gov (United States)

Brustovetsky, Tatiana; Brittain, Matthew K; Sheets, Patrick L; Cummins, Theodore R; Pinelis, Vsevolod; Brustovetsky, Nickolay

2011-01-01

BACKGROUND AND PURPOSE An isothiourea derivative (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methane sulfonate (KB-R7943), a widely used inhibitor of the reverse Na+/Ca2+ exchanger (NCXrev), was instrumental in establishing the role of NCXrev in glutamate-induced Ca2+ deregulation in neurons. Here, the effects of KB-R7943 on N-methyl-D-aspartate (NMDA) receptors and mitochondrial complex I were tested. EXPERIMENTAL APPROACH Fluorescence microscopy, electrophysiological patch-clamp techniques and cellular respirometry with Seahorse XF24 analyzer were used with cultured hippocampal neurons; membrane potential imaging, respirometry and Ca2+ flux measurements were made in isolated rat brain mitochondria. KEY RESULTS KB-R7943 inhibited NCXrev with IC50= 5.7 ± 2.1 µM, blocked NMDAR-mediated ion currents, and inhibited NMDA-induced increase in cytosolic Ca2+ with IC50= 13.4 ± 3.6 µM but accelerated calcium deregulation and mitochondrial depolarization in glutamate-treated neurons. KB-R7943 depolarized mitochondria in a Ca2+-independent manner. Stimulation of NMDA receptors caused NAD(P)H oxidation that was coupled or uncoupled from ATP synthesis depending on the presence of Ca2+ in the bath solution. KB-R7943, or rotenone, increased NAD(P)H autofluorescence under resting conditions and suppressed NAD(P)H oxidation following glutamate application. KB-R7943 inhibited 2,4-dinitrophenol-stimulated respiration of cultured neurons with IC50= 11.4 ± 2.4 µM. With isolated brain mitochondria, KB-R7943 inhibited respiration, depolarized organelles and suppressed Ca2+ uptake when mitochondria oxidized complex I substrates but was ineffective when mitochondria were supplied with succinate, a complex II substrate. CONCLUSIONS AND IMPLICATIONS KB-R7943, in addition to NCXrev, blocked NMDA receptors in cultured hippocampal neurons and inhibited complex I in the mitochondrial respiratory chain. These findings are critical for the correct interpretation of experimental

Mathematical modeling of mutant transferrin-CRM107 molecular conjugates for cancer therapy.

Science.gov (United States)

Yoon, Dennis J; Chen, Kevin Y; Lopes, André M; Pan, April A; Shiloach, Joseph; Mason, Anne B; Kamei, Daniel T

2017-03-07

The transferrin (Tf) trafficking pathway is a promising mechanism for use in targeted cancer therapy due to the overexpression of transferrin receptors (TfRs) on cancerous cells. We have previously developed a mathematical model of the Tf/TfR trafficking pathway to improve the efficiency of Tf as a drug carrier. By using diphtheria toxin (DT) as a model toxin, we found that mutating the Tf protein to change its iron release rate improves cellular association and efficacy of the drug. Though this is an improvement upon using wild-type Tf as the targeting ligand, conjugated toxins like DT are unfortunately still highly cytotoxic at off-target sites. In this work, we address this hurdle in cancer research by developing a mathematical model to predict the efficacy and selectivity of Tf conjugates that use an alternative toxin. For this purpose, we have chosen to study a mutant of DT, cross-reacting material 107 (CRM107). First, we developed a mathematical model of the Tf-DT trafficking pathway by extending our Tf/TfR model to include intracellular trafficking via DT and DT receptors. Using this mathematical model, we subsequently investigated the efficacy of several conjugates in cancer cells: DT and CRM107 conjugated to wild-type Tf, as well as to our engineered mutant Tf proteins (K206E/R632A Tf and K206E/R534A Tf). We also investigated the selectivity of mutant Tf-CRM107 against non-neoplastic cells. Through the use of our mathematical model, we predicted that (i) mutant Tf-CRM107 exhibits a greater cytotoxicity than wild-type Tf-CRM107 against cancerous cells, (ii) this improvement was more drastic with CRM107 conjugates than with DT conjugates, and (iii) mutant Tf-CRM107 conjugates were selective against non-neoplastic cells. These predictions were validated with in vitro cytotoxicity experiments, demonstrating that mutant Tf-CRM107 conjugates is indeed a more suitable therapeutic agent. Validation from in vitro experiments also confirmed that such whole

Hepatitis B virus X protein mutant HBxΔ127 promotes proliferation of hepatoma cells through up-regulating miR-215 targeting PTPRT

Energy Technology Data Exchange (ETDEWEB)

Liu, Fabao [Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071 (China); Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin 300071 (China); You, Xiaona [Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071 (China); Chi, Xiumei [Department of Hepatology, The First Hospital, Jilin University, Changchun 130021 (China); Wang, Tao [Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071 (China); Ye, Lihong [Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin 300071 (China); Niu, Junqi, E-mail: junqiniu@yahoo.com.cn [Department of Hepatology, The First Hospital, Jilin University, Changchun 130021 (China); Zhang, Xiaodong, E-mail: zhangxd@nankai.edu.cn [Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071 (China)

2014-02-07

Highlights: • Relative to wild type HBx, HBX mutant HBxΔ127 strongly enhances cell proliferation. • Relative to wild type HBx, HBxΔ127 remarkably up-regulates miR-215 in hepatoma cells. • HBxΔ127-elevated miR-215 promotes cell proliferation via targeting PTPRT mRNA. - Abstract: The mutant of virus is a frequent event. Hepatitis B virus X protein (HBx) plays a vital role in the development of hepatocellular carcinoma (HCC). Therefore, the identification of potent mutant of HBx in hepatocarcinogenesis is significant. Previously, we identified a natural mutant of the HBx gene (termed HBxΔ127). Relative to wild type HBx, HBxΔ127 strongly enhanced cell proliferation and migration in HCC. In this study, we aim to explore the mechanism of HBxΔ127 in promotion of proliferation of hepatoma cells. Our data showed that both wild type HBx and HBxΔ127 could increase the expression of miR-215 in hepatoma HepG2 and H7402 cells. However, HBxΔ127 was able to significantly increase miR-215 expression relative to wild type HBx in the cells. We identified that protein tyrosine phosphatase, receptor type T (PTPRT) was one of the target genes of miR-215 through targeting 3′UTR of PTPRT mRNA. In function, miR-215 was able to promote the proliferation of hepatoma cells. Meanwhile anti-miR-215 could partially abolish the enhancement of cell proliferation mediated by HBxΔ127 in vitro. Knockdown of PTPRT by siRNA could distinctly suppress the decrease of cell proliferation mediated by anti-miR-215 in HepG2-XΔ127/H7402-XΔ127 cells. Moreover, we found that anti-miR-215 remarkably inhibited the tumor growth of hepatoma cells in nude mice. Collectively, relative to wild type HBx, HBxΔ127 strongly enhances proliferation of hepatoma cells through up-regulating miR-215 targeting PTPRT. Our finding provides new insights into the mechanism of HBx mutant HBxΔ127 in promotion of proliferation of hepatoma cells.

R Factor-Controlled Restriction and Modification of Deoxyribonucleic Acid: Restriction Mutants

Science.gov (United States)

Yoshimori, Robert; Roulland-Dussoix, Daisy; Boyer, Herbert W.

1972-01-01

Restriction mutants of two different R factor-controlled host specificities (RI and RII) were isolated. All of the restriction mutants examined had a normal modification phenotype. No complementation was observed between the RI and RII host specificities. It is concluded that for each host specificity no protein subunit is shared by the restriction endonuclease and modification methylase. PMID:4565538

On the ligand binding profile and desensitization of plant ionotropic glutamate receptor (iGluR)-like channels functioning in MAMP-triggered Ca2+ influx

DEFF Research Database (Denmark)

Kwaaitaal, Mark Adrianus Cornelis J; Maintz, Jens; Cavdar, Meltem

2012-01-01

in the putative agonist binding profile and potential mode of desensitization of MAMP-activated plant iGluRs. Based on results from pharmacological inhibition and desensitization experiments, we propose that plant iGluR complexes responsible for the MAMP-triggered Ca ( 2+) signature have a binding profile...... that combines the specificities of mammalian NMDA-and non-NMDA types of iGluRs, possibly reflecting the evolutionary history of plant and animal iGluRs. We further hypothesize that, analogous to the mammalian NMDA-NR1 receptor, desensitization of plant iGluR-like channels might involve binding of the ubiquitous...

Structural Basis for a Switch in Receptor Binding Specificity of Two H5N1 Hemagglutinin Mutants

Directory of Open Access Journals (Sweden)

Xueyong Zhu

2015-11-01

Full Text Available Avian H5N1 influenza viruses continue to spread in wild birds and domestic poultry with sporadic infection in humans. Receptor binding specificity changes are a prerequisite for H5N1 viruses and other zoonotic viruses to be transmitted among humans. Previous reported hemagglutinin (HA mutants from ferret-transmissible H5N1 viruses of A/Vietnam/1203/2004 and A/Indonesia/5/2005 showed slightly increased, but still very weak, binding to human receptors. From mutagenesis and glycan array studies, we previously identified two H5N1 HA mutants that could more effectively switch receptor specificity to human-like α2-6-linked sialosides with avidity comparable to wild-type H5 HA binding to avian-like α2-3-linked sialosides. Here, crystal structures of these two H5 HA mutants free and in complex with human and avian glycan receptor analogs reveal the structural basis for their preferential binding to human receptors. These findings suggest continuous surveillance should be maintained to monitor and assess human-to-human transmission potential of H5N1 viruses.

1H-cyclopentapyrimidine-2,4(1H,3H)-dione-related ionotropic glutamate receptors ligands. Structure-activity relationships and identification of potent and selective iGluR5 modulators

DEFF Research Database (Denmark)

Butini, Stefania; Pickering, Darryl S; Morelli, Elena

2008-01-01

(S)-CPW399 ((S)-1) is a potent and excitotoxic AMPA receptor partial agonist. Modifying the cyclopentane ring of (S)-1, we developed two of the most potent and selective functional antagonists (5 and 7) for kainate receptor (KA-R) subunit iGluR5. Derivatives 5 and 7, with their unique pharmacolog...

Synthesis and evaluation of [125I]I-TSA as a brain nicotinic acetylcholine receptor α7 subtype imaging agent

International Nuclear Information System (INIS)

Ogawa, Mikako; Tatsumi, Ryo; Fujio, Masakazu; Katayama, Jiro; Magata, Yasuhiro

2006-01-01

Introduction: Some in vitro investigations have suggested that the nicotinic acetylcholine receptor (nAChR) α 7 subtype is implicated in Alzheimer's disease, schizophrenia and others. Recently, we developed (R)-3'-(5-bromothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'-[1',3'] oxazolidin]-2'-one (Br-TSA), which has a high affinity and selectivity for α 7 nAChRs. Therefore we synthesized (R)-3'-(5-[ 125 I]iodothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'- [1',3']oxazolidin]-2'-one ([ 125 I]I-TSA) and evaluated its potential for the in vivo detection of α 7 nAChR in brain. Methods: In vitro binding affinity of I-TSA was measured in rat brain homogenates. Radioiodination was accomplished by a Br-I exchange reaction. Biodistribution studies were undertaken in mice by tail vein injection of [ 125 I]I-TSA. In vivo receptor blocking studies were carried out by treating mice with methyllycaconitine (MLA; 5 nmol/5 μl, i.c.v.) or nonradioactive I-TSA (50 μmol/kg, i.v.). Results: I-TSA exhibited a high affinity and selectivity for the α 7 nAChR (K i for α 7 nAChR=0.54 nM). Initial uptake in the brain was high (4.42 %dose/g at 5 min), and the clearance of radioactivity was relatively slow in the hippocampus (α 7 nAChR-rich region) and was rather rapid in the cerebellum (α 7 nAChR poor region). The hippocampus to cerebellum uptake ratio was 0.9 at 5 min postinjection, but it was increased to 1.8 at 60 min postinjection. Although the effect was not statistically significant, administration of I-TSA and MLA decreased the accumulation of radioactivity in hippocampus. Conclusion: Despite its high affinity and selectivity, [ 125 I]I-TSA does not appear to be a suitable tracer for in vivo α 7 nAChR receptor imaging studies due to its high nonspecific binding. Further structural optimization is needed

Tyrosyl-DNA Phosphodiesterase I Catalytic Mutants Reveal an Alternative Nucleophile That Can Catalyze Substrate Cleavage*

Science.gov (United States)

Comeaux, Evan Q.; Cuya, Selma M.; Kojima, Kyoko; Jafari, Nauzanene; Wanzeck, Keith C.; Mobley, James A.; Bjornsti, Mary-Ann; van Waardenburg, Robert C. A. M.

2015-01-01

Tyrosyl-DNA phosphodiesterase I (Tdp1) catalyzes the repair of 3′-DNA adducts, such as the 3′-phosphotyrosyl linkage of DNA topoisomerase I to DNA. Tdp1 contains two conserved catalytic histidines: a nucleophilic His (Hisnuc) that attacks DNA adducts to form a covalent 3′-phosphohistidyl intermediate and a general acid/base His (Hisgab), which resolves the Tdp1-DNA linkage. A Hisnuc to Ala mutant protein is reportedly inactive, whereas the autosomal recessive neurodegenerative disease SCAN1 has been attributed to the enhanced stability of the Tdp1-DNA intermediate induced by mutation of Hisgab to Arg. However, here we report that expression of the yeast HisnucAla (H182A) mutant actually induced topoisomerase I-dependent cytotoxicity and further enhanced the cytotoxicity of Tdp1 Hisgab mutants, including H432N and the SCAN1-related H432R. Moreover, the HisnucAla mutant was catalytically active in vitro, albeit at levels 85-fold less than that observed with wild type Tdp1. In contrast, the HisnucPhe mutant was catalytically inactive and suppressed Hisgab mutant-induced toxicity. These data suggest that the activity of another nucleophile when Hisnuc is replaced with residues containing a small side chain (Ala, Asn, and Gln), but not with a bulky side chain. Indeed, genetic, biochemical, and mass spectrometry analyses show that a highly conserved His, immediately N-terminal to Hisnuc, can act as a nucleophile to catalyze the formation of a covalent Tdp1-DNA intermediate. These findings suggest that the flexibility of Tdp1 active site residues may impair the resolution of mutant Tdp1 covalent phosphohistidyl intermediates and provide the rationale for developing chemotherapeutics that stabilize the covalent Tdp1-DNA intermediate. PMID:25609251

Gamma ray induced mutants in Coleus

Energy Technology Data Exchange (ETDEWEB)

Vasudevan, K; Jos, J S [Central Tuber Crops Research Institute, Trivandrum, Kerala (India)

1988-07-01

The germplasm collection of Chinese potato (Coleus parviflorus Benth) contains almost no variation for yield contributing traits. The crop does not produce seeds. Treatment of underground tubers with 1 kR, 2 kR, 3 kR and 4 kR gamma rays resulted in 50 morphologically different mutants which are maintained as mutant clones. In the M{sub 1}V{sub 1} generation, suspected mutant sprouts, were carefully removed and grown separately. The most interesting mutant types are the following: (i) erect mutant with spoon shaped light green leaves, 30 cm long inflorescences against 20 cm in the control, cylindrical tubers measuring ca. 7.0 cm long and 3 cm girth against 4 cm and 2.5 cm in the control (ii) early mutants 1 and 2, one having less leaf serration, the other having light green small leaves and dwarf type (iii) fleshy leaf mutant, dark green, thick and smooth leaves. Control plants spread almost in 1 m{sup 2} area and bear tubers from the nodes of branches. In the early mutants tuber formation is mainly restricted to the base of the plant, which makes harvest easier. The crop usually matures within 150 - 160 days, the early mutants are ready for harvest 100 days after planting. As the mutants are less spreading, the yield could be increased by closer spacing.

Gamma ray induced mutants in Coleus

International Nuclear Information System (INIS)

Vasudevan, K.; Jos, J.S.

1988-01-01

The germplasm collection of Chinese potato (Coleus parviflorus Benth) contains almost no variation for yield contributing traits. The crop does not produce seeds. Treatment of underground tubers with 1 kR, 2 kR, 3 kR and 4 kR gamma rays resulted in 50 morphologically different mutants which are maintained as mutant clones. In the M 1 V 1 generation, suspected mutant sprouts, were carefully removed and grown separately. The most interesting mutant types are the following: (i) erect mutant with spoon shaped light green leaves, 30 cm long inflorescences against 20 cm in the control, cylindrical tubers measuring ca. 7.0 cm long and 3 cm girth against 4 cm and 2.5 cm in the control (ii) early mutants 1 and 2, one having less leaf serration, the other having light green small leaves and dwarf type (iii) fleshy leaf mutant, dark green, thick and smooth leaves. Control plants spread almost in 1 m 2 area and bear tubers from the nodes of branches. In the early mutants tuber formation is mainly restricted to the base of the plant, which makes harvest easier. The crop usually matures within 150 - 160 days, the early mutants are ready for harvest 100 days after planting. As the mutants are less spreading, the yield could be increased by closer spacing

Towards a "Golden Standard" for computing globin stability: Stability and structure sensitivity of myoglobin mutants.

Science.gov (United States)

Kepp, Kasper P

2015-10-01

Fast and accurate computation of protein stability is increasingly important for e.g. protein engineering and protein misfolding diseases, but no consensus methods exist for important proteins such as globins, and performance may depend on the type of structural input given. This paper reports benchmarking of six protein stability calculators (POPMUSIC 2.1, I-Mutant 2.0, I-Mutant 3.0, CUPSAT, SDM, and mCSM) against 134 experimental stability changes for mutations of sperm-whale myoglobin. Six different high-resolution structures were used to test structure sensitivity that may impair protein calculations. The trend accuracy of the methods decreased as I-Mutant 2.0 (R=0.64-0.65), SDM (R=0.57-0.60), POPMUSIC2.1 (R=0.54-0.57), I-Mutant 3.0 (R=0.53-0.55), mCSM (R=0.35-0.47), and CUPSAT (R=0.25-0.48). The mean signed errors increased as SDMMean absolute errors increased as I-Mutant 2.0<I-Mutant 3.0I-Mutant 3.0 (0.05)<I-Mutant 2.0 (0.09)I-Mutant 2.0 is proficient for this purpose, as further validated against a data set of related cytochrome c like proteins. The results also emphasize the importance of high-quality crystal structures and reveal structure-dependent effects even in the near-atomic resolution limit. Copyright © 2015 Elsevier B.V. All rights reserved.

Identification of transmembrane domain 6 & 7 residues that contribute to the binding pocket of the urotensin II receptor.

Science.gov (United States)

Holleran, Brian J; Domazet, Ivana; Beaulieu, Marie-Eve; Yan, Li Ping; Guillemette, Gaétan; Lavigne, Pierre; Escher, Emanuel; Leduc, Richard

2009-04-15

Urotensin II (U-II), a cyclic undecapeptide, is the natural ligand of the urotensin II (UT) receptor, a G protein-coupled receptor. In the present study, we used the substituted-cysteine accessibility method to identify specific residues in transmembrane domains (TMDs) six and seven of the rat urotensin II receptor (rUT) that contribute to the formation of the binding pocket of the receptor. Each residue in the R256(6.32)-Q283(6.59) fragment of TMD6 and the A295(7.31)-T321(7.57) fragment of TMD7 was mutated, individually, to a cysteine. The resulting mutants were expressed in COS-7 cells, which were subsequently treated with the positively charged methanethiosulfonate-ethylammonium (MTSEA) or the negatively charged methanethiosulfonate-ethylsulfonate (MTSES) sulfhydryl-specific alkylating agents. MTSEA treatment resulted in a significant reduction in the binding of TMD6 mutants F268C(6.44) and W278C(6.54) and TMD7 mutants L298C(7.34), T302C(7.38), and T303C(7.39) to (125)I-U-II. MTSES treatment resulted in a significant reduction in the binding of two additional mutants, namely L282C(6.58) in TMD6 and Y300C(7.36) in TMD7. These results suggest that specific residues orient themselves within the water-accessible binding pocket of the rUT receptor. This approach, which allowed us to identify key determinants in TMD6 and TMD7 that contribute to the UT receptor binding pocket, enabled us to further refine our homology-based model of how U-II interacts with its cognate receptor.

R-268712, an orally active transforming growth factor-β type I receptor inhibitor, prevents glomerular sclerosis in a Thy1 nephritis model.

Science.gov (United States)

Terashima, Hideki; Kato, Mikio; Ebisawa, Masayuki; Kobayashi, Hideki; Suzuki, Kanae; Nezu, Yoshikazu; Sada, Toshio

2014-07-05

R-268712 is a novel and specific inhibitor of activin receptor-like kinase 5 (ALK5), a transforming growth factor β (TGF-β) type I receptor. Evaluation of in vitro inhibition indicated that R-268712 is a potent and selective inhibitor of ALK5 with an IC50 of 2.5nM, an approximately 5000-fold more selectivity for ALK5 than p38 mitogen-activated protein kinase (MAPK). Oral administration of R-268712 at doses of 1, 3 and 10mg/kg also inhibited the development of renal fibrosis in a dose-dependent manner in a unilateral ureteral obstruction (UUO) model. Additionally, we evaluated the efficacy of R-268712 in a heminephrectomized anti-Thy1 glomerulonephritis model at doses of 0.3 and 1mg/kg. R-268712 reduced proteinuria and glomerulosclerosis significantly with improvement of renal function. Collectively, these results suggested that R-268712 and other ALK5 inhibitors could suppress glomerulonephritis as well as glomerulosclerosis by an inhibitory mechanism that involves suppression of TGF-β signaling. Copyright © 2014 Elsevier B.V. All rights reserved.

Structural analysis of the interaction of IGF I with the IGF types 1 and 2 and insulin receptors

International Nuclear Information System (INIS)

Cascieri, M.A.; Chicchi, G.G.; Hayes, N.S.; Green, B.G.; Applebaum, J.A.; Bayne, M.L.

1987-01-01

A synthetic gene for human IGF I has been synthesized which directs the synthesis and secretion of fully active human IGF I (rIGF I) from yeast. rIGF I inhibits binding of 125 I-IGF I to type 1 IGF receptors from human placenta (IGF-R1, IC50 = 4 nM), binding of 125 I-insulin to insulin receptors (IR, IC50 = 881 nM), binding of 125 I-MSA to type 2 IGF receptors from rat liver (IGF-R2, IC50 = 80 nM), and binding of 125 I-IGF I to crude human serum binding protein (hBP, IC50 = 0.42 nM). rIGF I is equipotent to human IGF I in stimulating glucose transport in murine BC3H1 cells and in stimulating DNA synthesis in rat A10 cells. Site directed mutagenesis of the synthetic gene is being used to characterize the structural requirements for binding to these receptors. IGF I (FFY) B(23-25) is equipotent to rIGF I at the IGF-R1 (6.9 nM), the IGF-R2 (36 nM), and the IR (841 nM) and is less potent at the hBP (1.7 nM). In contrast, IGF I(SFY) B(23-25) is 20-fold less potent than rIGF I at the IGF-R1 and is 10-fold less potent than rIGF I at hBP. This peptide is greater than 10-fold less active at the IGF-R2 and the IR. This peptide is a full agonist in the cell assays but 20-50 fold less potent than rIGF I. These data are consistent with the hypothesis that the F to S change destabilizes the tertiary structure of IGF I

The yeast complex I equivalent NADH dehydrogenase rescues pink1 mutants.

Directory of Open Access Journals (Sweden)

Sven Vilain

2012-01-01

Full Text Available Pink1 is a mitochondrial kinase involved in Parkinson's disease, and loss of Pink1 function affects mitochondrial morphology via a pathway involving Parkin and components of the mitochondrial remodeling machinery. Pink1 loss also affects the enzymatic activity of isolated Complex I of the electron transport chain (ETC; however, the primary defect in pink1 mutants is unclear. We tested the hypothesis that ETC deficiency is upstream of other pink1-associated phenotypes. We expressed Saccaromyces cerevisiae Ndi1p, an enzyme that bypasses ETC Complex I, or sea squirt Ciona intestinalis AOX, an enzyme that bypasses ETC Complex III and IV, in pink1 mutant Drosophila and find that expression of Ndi1p, but not of AOX, rescues pink1-associated defects. Likewise, loss of function of subunits that encode for Complex I-associated proteins displays many of the pink1-associated phenotypes, and these defects are rescued by Ndi1p expression. Conversely, expression of Ndi1p fails to rescue any of the parkin mutant phenotypes. Additionally, unlike pink1 mutants, fly parkin mutants do not show reduced enzymatic activity of Complex I, indicating that Ndi1p acts downstream or parallel to Pink1, but upstream or independent of Parkin. Furthermore, while increasing mitochondrial fission or decreasing mitochondrial fusion rescues mitochondrial morphological defects in pink1 mutants, these manipulations fail to significantly rescue the reduced enzymatic activity of Complex I, indicating that functional defects observed at the level of Complex I enzymatic activity in pink1 mutant mitochondria do not arise from morphological defects. Our data indicate a central role for Complex I dysfunction in pink1-associated defects, and our genetic analyses with heterologous ETC enzymes suggest that Ndi1p-dependent NADH dehydrogenase activity largely acts downstream of, or in parallel to, Pink1 but upstream of Parkin and mitochondrial remodeling.

A proteome analysis of the response of a Pseudomonas aeruginosa oxyR mutant to iron limitation.

Science.gov (United States)

Vinckx, Tiffany; Wei, Qing; Matthijs, Sandra; Noben, Jean-Paul; Daniels, Ruth; Cornelis, Pierre

2011-06-01

In Pseudomonas aeruginosa the response to oxidative stress is orchestrated by the LysR regulator OxyR by activation of the transcription of two catalase genes (katA and katB), of the alkyl-hydroxyperoxidases ahpCF and ahpB. Next to the expected high sensitivity to oxidative stress generated by reactive oxygen species (ROS: H(2)O(2), O(2)(-)), the oxyR mutant shows a defective growth under conditions of iron limitation (Vinckx et al. 2008). Although production and uptake of the siderophore pyoverdine is not affected by the absence of oxyR, the mutant is unable to satisfy its need for iron when grown under iron limiting conditions. In order to get a better insight into the effects caused by iron limitation on the physiological response of the oxyR mutant we decided to compare the proteomes of the wild type and the mutant grown in the iron-poor casamino acids medium (CAA), in CAA plus H(2)O(2), and in CAA plus the strong iron chelator ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) (EDDHA). Especially in the presence of hydrogen peroxide the oxyR cells increase the production of stress proteins (Dps and IbpA). The superoxide dismutase SodM is produced in higher amounts in the oxyR mutant grown in CAA plus H(2)O(2). The PchB protein, a isochorismate-pyruvate lyase involved in the siderophore pyochelin biosynthesis is not detectable in the extracts from the oxyR mutant grown in the presence of hydrogen peroxide. When cells were grown in the presence of EDDHA, we observed a reduction of the ferric uptake regulator (Fur), and an increase in the two subunits of the succinyl-CoA synthetase and the fumarase FumC1.

A structural model of the pore-forming region of the skeletal muscle ryanodine receptor (RyR1.

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Srinivas Ramachandran

2009-04-01

Full Text Available Ryanodine receptors (RyRs are ion channels that regulate muscle contraction by releasing calcium ions from intracellular stores into the cytoplasm. Mutations in skeletal muscle RyR (RyR1 give rise to congenital diseases such as central core disease. The absence of high-resolution structures of RyR1 has limited our understanding of channel function and disease mechanisms at the molecular level. Here, we report a structural model of the pore-forming region of RyR1. Molecular dynamics simulations show high ion binding to putative pore residues D4899, E4900, D4938, and D4945, which are experimentally known to be critical for channel conductance and selectivity. We also observe preferential localization of Ca(2+ over K(+ in the selectivity filter of RyR1. Simulations of RyR1-D4899Q mutant show a loss of preference to Ca(2+ in the selectivity filter as seen experimentally. Electrophysiological experiments on a central core disease mutant, RyR1-G4898R, show constitutively open channels that conduct K(+ but not Ca(2+. Our simulations with G4898R likewise show a decrease in the preference of Ca(2+ over K(+ in the selectivity filter. Together, the computational and experimental results shed light on ion conductance and selectivity of RyR1 at an atomistic level.

Kinetic properties of 'dual' orexin receptor antagonists at OX1R and OX2R orexin receptors.

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Gabrielle Elizabeth Callander

2013-12-01

Full Text Available Orexin receptor antagonists represent attractive targets for the development of drugs for the treatment of insomnia. Both efficacy and safety are crucial in clinical settings and thorough investigations of pharmacokinetics and pharmacodynamics can predict contributing factors such as duration of action and undesirable effects. To this end, we studied the interactions between various ‘dual’ orexin receptor antagonists and the orexin receptors, OX1R and OX2R, over time using saturation and competition radioligand binding with [3H]-BBAC ((S-N-([1,1'-biphenyl]-2-yl-1-(2-((1-methyl-1H-benzo[d]imidazol-2-ylthioacetylpyrrolidine-2-carboxamide. In addition, the kinetics of these compounds were investigated in cells expressing human, mouse and rat OX1R and OX2R using FLIPR® assays for calcium accumulation. We demonstrate that almorexant reaches equilibrium very slowly at OX2R, whereas SB-649868, suvorexant and filorexant may take hours to reach steady state at both orexin receptors. By contrast, compounds such as BBAC or the selective OX2R antagonist IPSU ((2-((1H-Indol-3-ylmethyl-9-(4-methoxypyrimidin-2-yl-2,9-diazaspiro[5.5]undecan-1-one bind rapidly and reach equilibrium very quickly in both binding and / or functional assays. Overall, the dual antagonists tested here tend to be rather unselective under non-equilibrium conditions and reach equilibrium very slowly. Once equilibrium is reached, each ligand demonstrates a selectivity profile that is however, distinct from the non-equilibrium condition. The slow kinetics of the dual antagonists tested suggest that in vitro receptor occupancy may be longer lasting than would be predicted. This raises questions as to whether pharmacokinetic studies measuring plasma or brain levels of these antagonists are accurate reflections of receptor occupancy in vivo.

Consequences of ChemR23 heteromerization with the chemokine receptors CXCR4 and CCR7.

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de Poorter, Cédric; Baertsoen, Kevin; Lannoy, Vincent; Parmentier, Marc; Springael, Jean-Yves

2013-01-01

Recent studies have shown that heteromerization of the chemokine receptors CCR2, CCR5 and CXCR4 is associated to negative binding cooperativity. In the present study, we build on these previous results, and investigate the consequences of chemokine receptor heteromerization with ChemR23, the receptor of chemerin, a leukocyte chemoattractant protein structurally unrelated to chemokines. We show, using BRET and HTRF assays, that ChemR23 forms homomers, and provide data suggesting that ChemR23 also forms heteromers with the chemokine receptors CCR7 and CXCR4. As previously described for other chemokine receptor heteromers, negative binding cooperativity was detected between ChemR23 and chemokine receptors, i.e. the ligands of one receptor competed for the binding of a specific tracer of the other. We also showed, using mouse bone marrow-derived dendritic cells prepared from wild-type and ChemR23 knockout mice, that ChemR23-specific ligands cross-inhibited CXCL12 binding on CXCR4 in a ChemR23-dependent manner, supporting the relevance of the ChemR23/CXCR4 interaction in native leukocytes. Finally, and in contrast to the situation encountered for other previously characterized CXCR4 heteromers, we showed that the CXCR4-specific antagonist AMD3100 did not cross-inhibit chemerin binding in cells co-expressing ChemR23 and CXCR4, demonstrating that cross-regulation by AMD3100 depends on the nature of receptor partners with which CXCR4 is co-expressed.

Initial evaluation of 123I-5-I-R91150, a selective 5-HT2Aligand for single-photon emission tomography, in healthy human subjects

International Nuclear Information System (INIS)

Busatto, G.F.; Pilowsky, L.S.; Costa, D.C.; Mertens, J.; Terriere, D.; Ell, P.J.; Mulligan, R.; Travis, M.J.; Leysen, J.E.; Lui, D.; Gacinovic, S.; Waddington, W.; Lingford-Hughes, A.; Kerwin, R.W.

1997-01-01

The mapping of 5-HT 2 receptors in the brain using functional imaging techniques has been limited by a relative lack of selective radioligands. Iodine-123 labelled 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methox ybenzamide ( 123 I-5-I-R91150 or 123 I-R93274) is a new ligand for single-photon emission tomography (SPET), with high affinity and selectivity for 5-HT 2A receptors. This study reports on preliminary 123 I-5-I-R91150 SPET, whole-body and blood distribution findings in five healthy human volunteers. Maximal brain uptake was approximately 2% of total body counts at 180 min post injection (p.i.). Dynamic SPET sequences were acquired with the brain-dedicated, single-slice multi-detector system SME-810 over 200 min p.i. Early peak uptake (at 5 min p.i.) was seen in the cerebellum, a region free from 5HT 2A receptors. In contrast, radioligand binding in the frontal cortex increased steadily over time, up to a peak at approximately 100-120 min p.i. Frontal cortex-cerebellum activity ratios reached values of 1.4, and remained stable from approximately 100 min p.i. onwards. Multi-slice SPET sequences showed a pattern of regional variation of binding compatible with the autoradiographic data on the distribution of 5-HT 2A receptors in humans (cerebral cortex >striatum >cerebellum). These findings suggest that 123 I-5-I-R91150 may be used for the imaging of 5-HT 2A receptors in the living human brain with SPET. (orig.). With 4 figs., 2 tabs

Disturbed neuronal ER-Golgi sorting of unassembled glycine receptors suggests altered subcellular processing is a cause of human hyperekplexia.

Science.gov (United States)

Schaefer, Natascha; Kluck, Christoph J; Price, Kerry L; Meiselbach, Heike; Vornberger, Nadine; Schwarzinger, Stephan; Hartmann, Stephanie; Langlhofer, Georg; Schulz, Solveig; Schlegel, Nadja; Brockmann, Knut; Lynch, Bryan; Becker, Cord-Michael; Lummis, Sarah C R; Villmann, Carmen

2015-01-07

Recent studies on the pathogenic mechanisms of recessive hyperekplexia indicate disturbances in glycine receptor (GlyR) α1 biogenesis. Here, we examine the properties of a range of novel glycine receptor mutants identified in human hyperekplexia patients using expression in transfected cell lines and primary neurons. All of the novel mutants localized in the large extracellular domain of the GlyR α1 have reduced cell surface expression with a high proportion of receptors being retained in the ER, although there is forward trafficking of glycosylated subpopulations into the ER-Golgi intermediate compartment and cis-Golgi compartment. CD spectroscopy revealed that the mutant receptors have proportions of secondary structural elements similar to wild-type receptors. Two mutants in loop B (G160R, T162M) were functional, but none of those in loop D/β2-3 were. One nonfunctional truncated mutant (R316X) could be rescued by coexpression with the lacking C-terminal domain. We conclude that a proportion of GlyR α1 mutants can be transported to the plasma membrane but do not necessarily form functional ion channels. We suggest that loop D/β2-3 is an important determinant for GlyR trafficking and functionality, whereas alterations to loop B alter agonist potencies, indicating that residues here are critical elements in ligand binding. Copyright © 2015 the authors 0270-6474/15/350422-16$15.00/0.

The SOL-2/Neto auxiliary protein modulates the function of AMPA-subtype ionotropic glutamate receptors.

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Wang, Rui; Mellem, Jerry E; Jensen, Michael; Brockie, Penelope J; Walker, Craig S; Hoerndli, Frédéric J; Hauth, Linda; Madsen, David M; Maricq, Andres V

2012-09-06

The neurotransmitter glutamate mediates excitatory synaptic transmission by gating ionotropic glutamate receptors (iGluRs). AMPA receptors (AMPARs), a subtype of iGluR, are strongly implicated in synaptic plasticity, learning, and memory. We previously discovered two classes of AMPAR auxiliary proteins in C. elegans that modify receptor kinetics and thus change synaptic transmission. Here, we have identified another auxiliary protein, SOL-2, a CUB-domain protein that associates with both the related auxiliary subunit SOL-1 and with the GLR-1 AMPAR. In sol-2 mutants, behaviors dependent on glutamatergic transmission are disrupted, GLR-1-mediated currents are diminished, and GLR-1 desensitization and pharmacology are modified. Remarkably, a secreted variant of SOL-1 delivered in trans can rescue sol-1 mutants, and this rescue depends on in cis expression of SOL-2. Finally, we demonstrate that SOL-1 and SOL-2 have an ongoing role in the adult nervous system to control AMPAR-mediated currents. Copyright © 2012 Elsevier Inc. All rights reserved.

A Leu to Ile but not Leu to Val change at HIV-1 reverse transcriptase codon 74 in the background of K65R mutation leads to an increased processivity of K65R+L74I enzyme and a replication competent virus

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Crumpacker Clyde S

2011-01-01

Full Text Available Abstract Background The major hurdle in the treatment of Human Immunodeficiency virus type 1 (HIV-1 includes the development of drug resistance-associated mutations in the target regions of the virus. Since reverse transcriptase (RT is essential for HIV-1 replication, several nucleoside analogues have been developed to target RT of the virus. Clinical studies have shown that mutations at RT codon 65 and 74 which are located in β3-β4 linkage group of finger sub-domain of RT are selected during treatment with several RT inhibitors, including didanosine, deoxycytidine, abacavir and tenofovir. Interestingly, the co-selection of K65R and L74V is rare in clinical settings. We have previously shown that K65R and L74V are incompatible and a R→K reversion occurs at codon 65 during replication of the virus. Analysis of the HIV resistance database has revealed that similar to K65R+L74V, the double mutant K65R+L74I is also rare. We sought to compare the impact of L→V versus L→I change at codon 74 in the background of K65R mutation, on the replication of doubly mutant viruses. Methods Proviral clones containing K65R, L74V, L74I, K65R+L74V and K65R+L74I RT mutations were created in pNL4-3 backbone and viruses were produced in 293T cells. Replication efficiencies of all the viruses were compared in peripheral blood mononuclear (PBM cells in the absence of selection pressure. Replication capacity (RC of mutant viruses in relation to wild type was calculated on the basis of antigen p24 production and RT activity, and paired analysis by student t-test was performed among RCs of doubly mutant viruses. Reversion at RT codons 65 and 74 was monitored during replication in PBM cells. In vitro processivity of mutant RTs was measured to analyze the impact of amino acid changes at RT codon 74. Results Replication kinetics plot showed that all of the mutant viruses were attenuated as compared to wild type (WT virus. Although attenuated in comparison to WT virus

The cognition-enhancing activity of E1R, a novel positive allosteric modulator of sigma-1 receptors

Science.gov (United States)

Zvejniece, L; Vavers, E; Svalbe, B; Vilskersts, R; Domracheva, I; Vorona, M; Veinberg, G; Misane, I; Stonans, I; Kalvinsh, I; Dambrova, M

2014-01-01

Background and Purpose Here, we describe the in vitro and in vivo effects of (4R,5S)-2-(5-methyl-2-oxo-4-phenyl-pyrrolidin-1-yl)-acetamide (E1R), a novel positive allosteric modulator of sigma-1 receptors. Experimental Approach E1R was tested for sigma receptor binding activity in a [3H](+)-pentazocine assay, in bradykinin (BK)-induced intracellular Ca2+ concentration ([Ca2+]i) assays and in an electrically stimulated rat vas deferens model. E1R's effects on cognitive function were tested using passive avoidance (PA) and Y-maze tests in mice. A selective sigma-1 receptor antagonist (NE-100), was used to study the involvement of the sigma-1 receptor in the effects of E1R. The open-field test was used to detect the effects of E1R on locomotion. Key Results Pretreatment with E1R enhanced the selective sigma-1 receptor agonist PRE-084's stimulating effect during a model study employing electrically stimulated rat vasa deferentia and an assay measuring the BK-induced [Ca2+]i increase. Pretreatment with E1R facilitated PA retention in a dose-related manner. Furthermore, E1R alleviated the scopolamine-induced cognitive impairment during the PA and Y-maze tests in mice. The in vivo and in vitro effects of E1R were blocked by treatment with the selective sigma-1 receptor antagonist NE-100. E1R did not affect locomotor activity. Conclusion and Implications E1R is a novel 4,5-disubstituted derivative of piracetam that enhances cognition and demonstrates efficacy against scopolamine-induced cholinergic dysfunction in mice. These effects are attributed to its positive modulatory action on the sigma-1 receptor and this activity may be relevant when developing new drugs for treating cognitive symptoms related to neurodegenerative diseases. PMID:24490863

Selective Negative Allosteric Modulation Of Metabotropic Glutamate Receptors - A Structural Perspective of Ligands and Mutants

DEFF Research Database (Denmark)

Harpsøe, Kasper; Isberg, Vignir; Tehan, Benjamin G

2015-01-01

modulators. In this analysis, we make the first comprehensive structural comparison of all metabotropic glutamate receptors, placing selective negative allosteric modulators and critical mutants into the detailed context of the receptor binding sites. A better understanding of how the different m......Glu allosteric modulator binding modes relates to selective pharmacological actions will be very valuable for rational design of safer drugs....

An Acquired HER2T798I Gatekeeper Mutation Induces Resistance to Neratinib in a Patient with HER2 Mutant-Driven Breast Cancer.

Science.gov (United States)

Hanker, Ariella B; Brewer, Monica Red; Sheehan, Jonathan H; Koch, James P; Sliwoski, Gregory R; Nagy, Rebecca; Lanman, Richard; Berger, Michael F; Hyman, David M; Solit, David B; He, Jie; Miller, Vincent; Cutler, Richard E; Lalani, Alshad S; Cross, Darren; Lovly, Christine M; Meiler, Jens; Arteaga, Carlos L

2017-06-01

We report a HER2 T798I gatekeeper mutation in a patient with HER2 L869R -mutant breast cancer with acquired resistance to neratinib. Laboratory studies suggested that HER2 L869R is a neratinib-sensitive, gain-of-function mutation that upon dimerization with mutant HER3 E928G , also present in the breast cancer, amplifies HER2 signaling. The patient was treated with neratinib and exhibited a sustained partial response. Upon clinical progression, HER2 T798I was detected in plasma tumor cell-free DNA. Structural modeling of this acquired mutation suggested that the increased bulk of isoleucine in HER2 T798I reduces neratinib binding. Neratinib blocked HER2-mediated signaling and growth in cells expressing HER2 L869R but not HER2 L869R/T798I In contrast, afatinib and the osimertinib metabolite AZ5104 strongly suppressed HER2 L869R/T798I -induced signaling and cell growth. Acquisition of HER2 T798I upon development of resistance to neratinib in a breast cancer with an initial activating HER2 mutation suggests HER2 L869R is a driver mutation. HER2 T798I -mediated neratinib resistance may be overcome by other irreversible HER2 inhibitors like afatinib. Significance: We found an acquired HER2 gatekeeper mutation in a patient with HER2 -mutant breast cancer upon clinical progression on neratinib. We speculate that HER2 T798I may arise as a secondary mutation following response to effective HER2 tyrosine kinase inhibitors (TKI) in other cancers with HER2 -activating mutations. This resistance may be overcome by other irreversible HER2 TKIs, such as afatinib. Cancer Discov; 7(6); 575-85. ©2017 AACR. This article is highlighted in the In This Issue feature, p. 539 . ©2017 American Association for Cancer Research.

Novel cellular targets of AhR underlie alterations in neutrophilic inflammation and iNOS expression during influenza virus infection

Science.gov (United States)

Head Wheeler, Jennifer L.; Martin, Kyle C.; Lawrence, B. Paige

2012-01-01

The underlying reasons for variable clinical outcomes from respiratory viral infections remain uncertain. Several studies suggest that environmental factors contribute to this variation, but limited knowledge of cellular and molecular targets of these agents hampers our ability to quantify or modify their contribution to disease and improve public health. The aryl hydrocarbon receptor (AhR) is an environment sensing transcription factor that binds many anthropogenic and natural chemicals. The immunomodulatory properties of AhR ligands are best characterized with extensive studies of changes in CD4+ T cell responses. Yet, AhR modulates other aspects of immune function. We previously showed that during influenza virus infection, AhR activation modulates neutrophil accumulation in the lung, and this contributes to increased mortality in mice. Enhanced levels of inducible nitric oxide synthase (iNOS) in infected lungs are observed during the same timeframe as AhR-mediated increased pulmonary neutrophilia. In this study, we evaluated whether these two consequences of AhR activation are causally linked. Reciprocal inhibition of AhR-mediated elevations in iNOS and pulmonary neutrophilia reveal that, although they are contemporaneous, they are not causally related. We show using Cre/loxP technology that elevated iNOS levels and neutrophil number in the infected lung result from separate, AhR-dependent signaling in endothelial and respiratory epithelial cells, respectively. Studies using mutant mice further reveal that AhR-mediated alterations in these innate responses to infection require a functional nuclear localization signal and DNA binding domain. Thus, gene targets of AhR in non-hematopoietic cells are important new considerations for understanding AhR-mediated changes in innate anti-viral immunity. PMID:23233726

Isolation of temperature-sensitive mutants of 16 S rRNA in Escherichia coli

DEFF Research Database (Denmark)

Triman, K; Becker, E; Dammel, C

1989-01-01

Temperature-sensitive mutants have been isolated following hydroxylamine mutagenesis of a plasmid containing Escherichia coli rRNA genes carrying selectable markers for spectinomycin resistance (U1192 in 16 S rRNA) and erythromycin resistance (G2058 in 23 S rRNA). These antibiotic resistance....... The mutations were localized by in vitro restriction fragment replacement followed by in vivo marker rescue and were identified by DNA sequence analysis. We report here seven single-base alterations in 16 S rRNA (A146, U153, A350, A359, A538, A1292 and U1293), five of which produce temperature......-sensitive spectinomycin resistance and two that produce unconditional loss of resistance. In each case, loss of ribosomal function can be accounted for by disruption of base-pairing in the secondary structure of 16 S rRNA. For the temperature-sensitive mutants, there is a lag period of about two generations between...

Serotonin hyperinnervation and upregulated 5-HT2A receptor expression and motor-stimulating function in nigrostriatal dopamine-deficient Pitx3 mutant mice.

Science.gov (United States)

Li, Li; Qiu, Guozhen; Ding, Shengyuan; Zhou, Fu-Ming

2013-01-23

The striatum receives serotonin (5-hydroxytryptamine, 5-HT) innervation and expresses 5-HT2A receptors (5-HT2ARs) and other 5-HT receptors, raising the possibility that the striatal 5-HT system may undergo adaptive changes after chronic severe dopamine (DA) loss and contribute to the function and dysfunction of the striatum. Here we show that in transcription factor Pitx3 gene mutant mice with a selective, severe DA loss in the dorsal striatum mimicking the DA denervation in late Parkinson's disease (PD), both the 5-HT innervation and the 5-HT2AR mRNA expression were increased in the dorsal striatum. Functionally, while having no detectable motor effect in wild type mice, the 5-HT2R agonist 2,5-dimethoxy-4-iodoamphetamine increased both the baseline and l-dopa-induced normal ambulatory and dyskinetic movements in Pitx3 mutant mice, whereas the selective 5-HT2AR blocker volinanserin had the opposite effects. These results demonstrate that Pitx3 mutant mice are a convenient and valid mouse model to study the compensatory 5-HT upregulation following the loss of the nigrostriatal DA projection and that the upregulated 5-HT2AR function in the DA deficient dorsal striatum may enhance both normal and dyskinetic movements. Copyright © 2012 Elsevier B.V. All rights reserved.

Internalization and down-regulation of the human epidermal growth factor receptor are regulated by the carboxyl-terminal tyrosines

DEFF Research Database (Denmark)

Helin, K; Beguinot, L

1991-01-01

with receptors in which 1, 2, or all 3 tyrosines were changed to phenylalanines. The triple point mutant EGF-R, expressed in NIH-3T3, exhibited low autophosphorylation in vivo, low biological and reduced kinase activities. Single and double point mutants were down-regulated, as well as wild type EGF......-R in response to EGF showing a half-life of about 1 h. Degradation of the triple point mutant, however, was impaired and resulted in a half-life of 4 h in the presence of EGF. EGF-dependent down-regulation of surface receptors was decreased in the triple point mutant EGF-R as was internalization and degradation...... of EGF. The specific rate of internalization of the triple point mutant was reduced. By contrast, intracellular processing of ligand previously internalized at 20 degrees C was similar between wild type and mutant receptors. Taken together the data indicate that the delay in degradation observed in cells...

Repeated administration of alpha7 nicotinic acetylcholine receptor (nAChR) agonists, but not positive allosteric modulators, increases alpha7 nAChR levels in the brain

DEFF Research Database (Denmark)

Christensen, Ditte Z; Mikkelsen, Jens D; Hansen, Henrik H

2010-01-01

AChR binding sites in several brain regions, particularly in the prefrontal cortex. The alpha7 nAChR agonists SSR180711 and PNU-282987 also increase [(125)I]-BTX binding, suggesting that this is a general consequence of alpha7 nAChR agonism. Interestingly, the alpha7 nAChR positive allosteric modulators PNU......The alpha7 nicotinic acetylcholine receptor (nAChR) is an important target for treatment of cognitive deficits in schizophrenia and Alzheimer's disease. However, the receptor desensitizes rapidly in vitro, which has led to concern regarding its applicability as a clinically relevant drug target....... Here we investigate the effects of repeated agonism on alpha7 nAChR receptor levels and responsiveness in vivo in rats. Using [(125)I]-alpha-bungarotoxin (BTX) autoradiography we show that acute or repeated administration with the selective alpha7 nAChR agonist A-582941 increases the number of alpha7 n...

Consequences of ChemR23 heteromerization with the chemokine receptors CXCR4 and CCR7.

Directory of Open Access Journals (Sweden)

Cédric de Poorter

Full Text Available Recent studies have shown that heteromerization of the chemokine receptors CCR2, CCR5 and CXCR4 is associated to negative binding cooperativity. In the present study, we build on these previous results, and investigate the consequences of chemokine receptor heteromerization with ChemR23, the receptor of chemerin, a leukocyte chemoattractant protein structurally unrelated to chemokines. We show, using BRET and HTRF assays, that ChemR23 forms homomers, and provide data suggesting that ChemR23 also forms heteromers with the chemokine receptors CCR7 and CXCR4. As previously described for other chemokine receptor heteromers, negative binding cooperativity was detected between ChemR23 and chemokine receptors, i.e. the ligands of one receptor competed for the binding of a specific tracer of the other. We also showed, using mouse bone marrow-derived dendritic cells prepared from wild-type and ChemR23 knockout mice, that ChemR23-specific ligands cross-inhibited CXCL12 binding on CXCR4 in a ChemR23-dependent manner, supporting the relevance of the ChemR23/CXCR4 interaction in native leukocytes. Finally, and in contrast to the situation encountered for other previously characterized CXCR4 heteromers, we showed that the CXCR4-specific antagonist AMD3100 did not cross-inhibit chemerin binding in cells co-expressing ChemR23 and CXCR4, demonstrating that cross-regulation by AMD3100 depends on the nature of receptor partners with which CXCR4 is co-expressed.

GEI-8, a homologue of vertebrate nuclear receptor corepressor NCoR/SMRT, regulates gonad development and neuronal functions in Caenorhabditis elegans.

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Pavol Mikoláš

Full Text Available NCoR and SMRT are two paralogous vertebrate proteins that function as corepressors with unliganded nuclear receptors. Although C. elegans has a large number of nuclear receptors, orthologues of the corepressors NCoR and SMRT have not unambiguously been identified in Drosophila or C. elegans. Here, we identify GEI-8 as the closest homologue of NCoR and SMRT in C. elegans and demonstrate that GEI-8 is expressed as at least two isoforms throughout development in multiple tissues, including neurons, muscle and intestinal cells. We demonstrate that a homozygous deletion within the gei-8 coding region, which is predicted to encode a truncated protein lacking the predicted NR domain, results in severe mutant phenotypes with developmental defects, slow movement and growth, arrested gonadogenesis and defects in cholinergic neurotransmission. Whole genome expression analysis by microarrays identified sets of de-regulated genes consistent with both the observed mutant phenotypes and a role of GEI-8 in regulating transcription. Interestingly, the upregulated transcripts included a predicted mitochondrial sulfide:quinine reductase encoded by Y9C9A.16. This locus also contains non-coding, 21-U RNAs of the piRNA class. Inhibition of the expression of the region coding for 21-U RNAs leads to irregular gonadogenesis in the homozygous gei-8 mutants, but not in an otherwise wild-type background, suggesting that GEI-8 may function in concert with the 21-U RNAs to regulate gonadogenesis. Our results confirm that GEI-8 is the orthologue of the vertebrate NCoR/SMRT corepressors and demonstrate important roles for this putative transcriptional corepressor in development and neuronal function.

Functional characterization of AVPR2 mutants found in Turkish patients with nephrogenic diabetes insipidus.

Science.gov (United States)

Erdem, Beril; Schulz, Angela; Saglar, Emel; Deniz, Ferhat; Schöneberg, Torsten; Mergen, Hatice

2018-01-01

Diabetes insipidus is a rare disorder characterized by an impairment in water balance because of the inability to concentrate urine. While central diabetes insipidus is caused by mutations in the AVP , the reason for genetically determined nephrogenic diabetes insipidus can be mutations in AQP2 or AVPR2 After release of AVP from posterior pituitary into blood stream, it binds to AVPR2, which is one of the receptors for AVP and is mainly expressed in principal cells of collecting ducts of kidney. Receptor activation increases cAMP levels in principal cells, resulting in the incorporation of AQP2 into the membrane, finally increasing water reabsorption. This pathway can be altered by mutations in AVPR2 causing nephrogenic diabetes insipidus. In this study, we functionally characterize four mutations (R68W, ΔR67-G69/G107W, V162A and T273M) in AVPR2, which were found in Turkish patients. Upon AVP stimulation, R68W, ΔR67-G69/G107W and T273M showed a significantly reduced maximum in cAMP response compared to wild-type receptor. All mutant receptor proteins were expressed at the protein level; however, R68W, ΔR67-G69/G107W and T273M were partially retained in the cellular interior. Immunofluorescence studies showed that these mutant receptors were trapped in ER and Golgi apparatus. The function of V162A was indistinguishable from the indicating other defects causing disease. The results are important for understanding the influence of mutations on receptor function and cellular trafficking. Therefore, characterization of these mutations provides useful information for further studies addressing treatment of intracellularly trapped receptors with cell-permeable antagonists to restore receptor function in patients with nephrogenic diabetes insipidus. © 2018 The authors.

Receptor activation and 2 distinct COOH-terminal motifs control G-CSF receptor distribution and internalization kinetics

NARCIS (Netherlands)

L.H.J. Aarts (Bart); O. Roovers (Onno); A.C. Ward (Alister); I.P. Touw (Ivo)

2004-01-01

textabstractWe have studied the intracellular distribution and internalization kinetics of the granulocyte colony-stimulating factor receptor (G-CSF-R) in living cells using fusion constructs of wild-type or mutant G-CSF-R and enhanced green fluorescent protein (EGFP). Under

Synthesis and evaluation of [{sup 125}I]I-TSA as a brain nicotinic acetylcholine receptor {alpha}{sub 7} subtype imaging agent

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Mikako [Laboratory of Genome Bio-Photonics, Photon Medical Research Center, Hamamatsu Medical University, Hamamatsu 431-3192 (Japan); Tatsumi, Ryo [Pharmaceuticals Research Unit, Research and Development Division, Mitsubishi Pharma Corporation, Yokohama 227-0033 (Japan); Fujio, Masakazu [Pharmaceuticals Research Unit, Research and Development Division, Mitsubishi Pharma Corporation, Yokohama 227-0033 (Japan); Katayama, Jiro [Pharmaceuticals Research Unit, Research and Development Division, Mitsubishi Pharma Corporation, Yokohama 227-0033 (Japan); Magata, Yasuhiro [Laboratory of Genome Bio-Photonics, Photon Medical Research Center, Hamamatsu Medical University, Hamamatsu 431-3192 (Japan)]. E-mail: magata@hama-med.ac.jp

2006-04-15

Introduction: Some in vitro investigations have suggested that the nicotinic acetylcholine receptor (nAChR) {alpha}{sub 7} subtype is implicated in Alzheimer's disease, schizophrenia and others. Recently, we developed (R)-3'-(5-bromothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'-[1',3'] oxazolidin]-2'-one (Br-TSA), which has a high affinity and selectivity for {alpha}{sub 7} nAChRs. Therefore we synthesized (R)-3'-(5-[{sup 125}I]iodothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'- [1',3']oxazolidin]-2'-one ([{sup 125}I]I-TSA) and evaluated its potential for the in vivo detection of {alpha}{sub 7} nAChR in brain. Methods: In vitro binding affinity of I-TSA was measured in rat brain homogenates. Radioiodination was accomplished by a Br-I exchange reaction. Biodistribution studies were undertaken in mice by tail vein injection of [{sup 125}I]I-TSA. In vivo receptor blocking studies were carried out by treating mice with methyllycaconitine (MLA; 5 nmol/5 {mu}l, i.c.v.) or nonradioactive I-TSA (50 {mu}mol/kg, i.v.). Results: I-TSA exhibited a high affinity and selectivity for the {alpha}{sub 7} nAChR (K {sub i} for {alpha}{sub 7} nAChR=0.54 nM). Initial uptake in the brain was high (4.42 %dose/g at 5 min), and the clearance of radioactivity was relatively slow in the hippocampus ({alpha}{sub 7} nAChR-rich region) and was rather rapid in the cerebellum ({alpha}{sub 7} nAChR poor region). The hippocampus to cerebellum uptake ratio was 0.9 at 5 min postinjection, but it was increased to 1.8 at 60 min postinjection. Although the effect was not statistically significant, administration of I-TSA and MLA decreased the accumulation of radioactivity in hippocampus. Conclusion: Despite its high affinity and selectivity, [{sup 125}I]I-TSA does not appear to be a suitable tracer for in vivo {alpha}{sub 7} nAChR receptor imaging studies due to its high nonspecific binding. Further structural optimization is needed.

Radiolabeling and in vitro and in vivo characterization of [18F]FB-[R(8,15,21), L17]-VIP as a PET imaging agent for tumor overexpressed VIP receptors.

Science.gov (United States)

Cheng, Dengfeng; Yin, Duanzhi; Li, Gucai; Wang, Mingwei; Li, Shiqiang; Zheng, Mingqiang; Cai, Hancheng; Wang, Yongxian

2006-12-01

In an effort to develop a peptide-based radiopharmaceutical for the detection of tumors overexpressed vasoactive intestinal peptide receptors with positron emission tomography, we have prepared a novel [R(8,15,21), L17]-VIP peptide for 18F-labeling. This peptide inhibited 125I-VIP binding to rats lung membranes with high affinity [half-maximal inhibitory concentrations (IC50) of 0.12 nm]. Additionally, [R(8,15,21), L17]-VIP showed higher stability than native vasoactive intestinal peptide in vivo of mice. With N-succinimidyl 4-[18F] fluorobenzoate as labeling prosthetic group, [18F]FB-[R(8,15,21), L17]-VIP was obtained in >99% radiochemical purity within 100 min in decay-for-corrected radiochemical yield of 33.6 +/- 3% (n = 5) and a specific radioactivity 255 GBq/micromol at the end of synthesis. Stability of [18F]FB-[R(8,15,21), L17]-VIP in vitro and in vivo were investigated. Biodistribution of this trace was carried out in mice with induced C26 colorectal tumor. Fast clearance of [18F]FB-[R(8,15,21), L17]-VIP from non-target tissues and specific uptakes by tumors realized higher tumor-to-muscle ratio (3.55) and tumor-to-blood ratio (2.37) 60 min postinjection. Clear difference was observed between the blocking and unblocking experiments in biodistribution and whole body radioautography. [18F]FB-[R(8,15,21), L17]-VIP has demonstrated its potential for diagnosing tumors overexpressed vasoactive intestinal peptide receptors both in vitro and in vivo.

Characterization of a family of gamma-ray-induced CHO mutants demonstrates that the ldlA locus is diploid and encodes the low-density lipoprotein receptor

International Nuclear Information System (INIS)

Sege, R.D.; Kozarsky, K.F.; Krieger, M.

1986-01-01

The ldlA locus is one of four Chinese hamster ovary (CHO) cell loci which are known to be required for the synthesis of functional low-density lipoprotein (LDL) receptors. Previous studies have suggested that the ldlA locus is diploid and encodes the LDL receptor. To confirm this assignment, we have isolated a partial genomic clone of the Chinese hamster LDL receptor gene and used this and other nucleic acid and antibody probes to study a family of ldlA mutants isolated after gamma-irradiation. Our analysis suggests that there are two LDL receptor alleles in wild-type CHO cells. Each of the three mutants isolated after gamma-irradiation had detectable deletions affecting one of the two LDL receptor alleles. One of the mutants also had a disruption of the remaining allele, resulting in the synthesis of an abnormal receptor precursor which was not subject to Golgi-associated posttranslational glycoprotein processing. The correlation of changes in the expression, structure, and function of LDL receptors with deletions in the LDL receptor genes in these mutants directly demonstrated that the ldlA locus in CHO cells is diploid and encodes the LDL receptor. In addition, our analysis suggests that CHO cells in culture may contain a partial LDL receptor pseudogene

Toll-like receptor 4 mutant and null mice retain morphine-induced tolerance, hyperalgesia, and physical dependence.

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Theresa Alexandra Mattioli

Full Text Available The innate immune system modulates opioid-induced effects within the central nervous system and one target that has received considerable attention is the toll-like receptor 4 (TLR4. Here, we examined the contribution of TLR4 in the development of morphine tolerance, hyperalgesia, and physical dependence in two inbred mouse strains: C3H/HeJ mice which have a dominant negative point mutation in the Tlr4 gene rendering the receptor non-functional, and B10ScNJ mice which are TLR4 null mutants. We found that neither acute antinociceptive response to a single dose of morphine, nor the development of analgesic tolerance to repeated morphine treatment, was affected by TLR4 genotype. Likewise, opioid induced hyperalgesia and opioid physical dependence (assessed by naloxone precipitated withdrawal were not altered in TLR4 mutant or null mice. We also examined the behavioural consequence of two stereoisomers of naloxone: (- naloxone, an opioid receptor antagonist, and (+ naloxone, a purported antagonist of TLR4. Both stereoisomers of naloxone suppressed opioid induced hyperalgesia in wild-type control, TLR4 mutant, and TLR4 null mice. Collectively, our data suggest that TLR4 is not required for opioid-induced analgesic tolerance, hyperalgesia, or physical dependence.

Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

International Nuclear Information System (INIS)

Zirak, P.; Penzkofer, A.; Hegemann, P.; Mathes, T.

2007-01-01

The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster (τ rec ∼ 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be φ s ∼ 0.3 (for AppA-wt: φ s ∼ 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed

Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

Science.gov (United States)

Zirak, P.; Penzkofer, A.; Hegemann, P.; Mathes, T.

2007-05-01

The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster ( τrec ≈ 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be ϕs ≈ 0.3 (for AppA-wt: ϕs ≈ 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed.

Escherichia coli ArgR mutants defective in cer/Xer recombination, but not in DNA binding.

Science.gov (United States)

Sénéchal, Hélène; Delesques, Jérémy; Szatmari, George

2010-04-01

The Escherichia coli arginine repressor (ArgR) is an L-arginine-dependent DNA-binding protein that controls the expression of the arginine biosynthetic genes and is required as an accessory factor for Xer site-specific recombination at cer and related recombination sites in plasmids. We used the technique of pentapeptide scanning mutagenesis to isolate a series of ArgR mutants that were considerably reduced in cer recombination, but were still able to repress an argA::lacZ fusion. DNA sequence analysis showed that all of the mutants mapped to the same nucleotide, resulting in a five amino acid insertion between residues 149 and 150 of ArgR, corresponding to the end of the alpha6 helix. A truncated ArgR containing a stop codon at residue 150 displayed the same phenotype as the protein with the five amino acid insertion, and both mutants displayed sequence-specific DNA-binding activity that was L-arginine dependent. These results show that the C-terminus of ArgR is more important in cer/Xer site-specific recombination than in DNA binding.

Covalent attachment of antagonists to the a7 nicotinic acetylcholine receptor: synthesis and reactivity of substituted maleimides

DEFF Research Database (Denmark)

Ambrus, Joseph I; Halliday, Jill I; Kanizaj, Nicholas

2012-01-01

The 3-methylmaleimide congeners of the natural product methyllycaconitine (MLA) and an analogue covalently attach to functional cysteine mutants of the a7 nicotinic acetylcholine receptor (nAChR).......The 3-methylmaleimide congeners of the natural product methyllycaconitine (MLA) and an analogue covalently attach to functional cysteine mutants of the a7 nicotinic acetylcholine receptor (nAChR)....

Loss of Hda activity stimulates replication initiation from I-box, but not R4 mutant origins in Escherichia coli

DEFF Research Database (Denmark)

Riber, Leise; Fujimitsu, K.; Katayama, T.

2009-01-01

in synchrony or with slight asynchrony only. Furthermore, lack of Hda stimulated initiation in all these mutants. The DnaA(ATP) containing complex that leads to initiation can therefore be formed in the absence of several of the origin DnaA binding sites including both DnaA(ATP) specific I-boxes. However...

Switch of SpnR function from activating to inhibiting quorum sensing by its exogenous addition

International Nuclear Information System (INIS)

Takayama, Yuriko; Kato, Norihiro

2016-01-01

The opportunistic human pathogen Serratia marcescens AS-1 produces the N-hexanoylhomoserine lactone (C6HSL) receptor SpnR, a homologue of LuxR from Vibrio fischeri, which activates pig clusters to produce the antibacterial prodigiosin. In this study, we attempted to artificially regulate quorum sensing (QS) by changing the role of SpnR in N-acylhomoserine lactone (AHL)-mediated QS. SpnR was obtained as a fusion protein tagged with maltose-binding protein (MBP) from overexpression in Escherichia coli, and its specific affinity to C6HSL was demonstrated by quartz crystal microbalance analysis and AHL-bioassay with Chromobacterium violaceum CV026. Prodigiosin production was effectively inhibited by externally added MBP-SpnR in both wild-type AS-1 and the AHL synthase-defective mutant AS-1(ΔspnI). For the mutant, the induced amount of prodigiosin was drastically reduced to approximately 4% with the addition of 18 μM MBP-SpnR to the liquid medium, indicating 81% trapping of C6HSL. A system for inhibiting QS can be constructed by adding exogenous AHL receptor to the culture broth to keep the concentration of free AHL low, whereas intracellular SpnR naturally functions as the activator in response to QS. - Highlights: • Quorum sensing (QS) regulates the expression of some bacterial genes. • We added an AHL receptor to culture media to inhibit QS in Serratia marcescens AS-1. • The exogenous receptor effectively bound C6HSL and inhibited QS. • This approach can be used to artificially regulate AHL-mediated QS.

Switch of SpnR function from activating to inhibiting quorum sensing by its exogenous addition

Energy Technology Data Exchange (ETDEWEB)

Takayama, Yuriko [Department of Innovation Systems Engineering, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan); CREST, Japan Science and Technology Agency, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan); Kato, Norihiro, E-mail: katon@cc.utsunomiya-u.ac.jp [CREST, Japan Science and Technology Agency, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan); Department of Material and Environmental Chemistry, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585 (Japan)

2016-09-02

The opportunistic human pathogen Serratia marcescens AS-1 produces the N-hexanoylhomoserine lactone (C6HSL) receptor SpnR, a homologue of LuxR from Vibrio fischeri, which activates pig clusters to produce the antibacterial prodigiosin. In this study, we attempted to artificially regulate quorum sensing (QS) by changing the role of SpnR in N-acylhomoserine lactone (AHL)-mediated QS. SpnR was obtained as a fusion protein tagged with maltose-binding protein (MBP) from overexpression in Escherichia coli, and its specific affinity to C6HSL was demonstrated by quartz crystal microbalance analysis and AHL-bioassay with Chromobacterium violaceum CV026. Prodigiosin production was effectively inhibited by externally added MBP-SpnR in both wild-type AS-1 and the AHL synthase-defective mutant AS-1(ΔspnI). For the mutant, the induced amount of prodigiosin was drastically reduced to approximately 4% with the addition of 18 μM MBP-SpnR to the liquid medium, indicating 81% trapping of C6HSL. A system for inhibiting QS can be constructed by adding exogenous AHL receptor to the culture broth to keep the concentration of free AHL low, whereas intracellular SpnR naturally functions as the activator in response to QS. - Highlights: • Quorum sensing (QS) regulates the expression of some bacterial genes. • We added an AHL receptor to culture media to inhibit QS in Serratia marcescens AS-1. • The exogenous receptor effectively bound C6HSL and inhibited QS. • This approach can be used to artificially regulate AHL-mediated QS.

Characterization of a mutant of Escherichia coli B/R defective in mutation frequency decline

International Nuclear Information System (INIS)

George, D.L.

1974-01-01

A mutant of Escherichia coli B/r designated mfd is very deficient in the ability to exhibit mutation frequency decline (MFD), the characteristic loss of potential suppressor mutations which occurs when protein synthesis is briefly inhibited after irradiation with ultraviolet light (uv). This mutant is known to excise pyrimidine dimers very slowly, although it is as uv-resistant as its mfd + B/r parent strain. We have found that the mfd mutant performs the initial incision step of excision repair normally, but repairs the resulting single-strand breaks much more slowly than the mfd + strain. In spite of the slow dimer excision in the mfd mutant, single-strand DNA breaks do not accumulate during postirradiation incubation, implying that incision and excision are well corrdinated. the prolonged postirradiation lag in cell division and DNA synthesis which accompany slow excision in the mfd strain indicates that resumption of these processes of optimal rates is linked to the timing of excision repair. The normal uv-resistance of the mfd mutant also suggests such coordination and shows that the rate of excision repair is independent of its ultimate efficiency in the removal of potentially lethal uv-induced damage. (U.S.)

T1R3 homomeric sweet taste receptor regulates adipogenesis through Gαs-mediated microtubules disassembly and Rho activation in 3T3-L1 cells.

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Yosuke Masubuchi

Full Text Available We previously reported that 3T3-L1 cells express a functional sweet taste receptor possibly as a T1R3 homomer that is coupled to Gs and negatively regulates adipogenesis by a Gαs-mediated but cAMP-independent mechanism. Here, we show that stimulation of this receptor with sucralose or saccharin induced disassembly of the microtubules in 3T3-L1 preadipocytes, which was attenuated by overexpression of the dominant-negative mutant of Gαs (Gαs-G226A. In contrast, overexpression of the constitutively active mutant of Gαs (Gαs-Q227L as well as treatment with cholera toxin or isoproterenol but not with forskolin caused disassembly of the microtubules. Sweetener-induced microtubule disassembly was accompanied by activation of RhoA and Rho-associated kinase (ROCK. This was attenuated with by knockdown of GEF-H1, a microtubule-localized guanine nucleotide exchange factor for Rho GTPase. Furthermore, overexpression of the dominant-negative mutant of RhoA (RhoA-T19N blocked sweetener-induced dephosphorylation of Akt and repression of PPARγ and C/EBPα in the early phase of adipogenic differentiation. These results suggest that the T1R3 homomeric sweet taste receptor negatively regulates adipogenesis through Gαs-mediated microtubule disassembly and consequent activation of the Rho/ROCK pathway.

A transcriptionally active estrogen receptor mutant is a novel type of dominant negative inhibitor of estrogen action.

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McInerney, E M; Ince, B A; Shapiro, D J; Katzenellenbogen, B S

1996-12-01

We have characterized a human estrogen receptor (ER) mutant, V364E, which has a single amino acid substitution in its hormone-binding domain. This ER mutant is fully active or even superactive at saturating levels of estradiol (10(-8) M E2) yet has the capacity to act as a strong dominant negative inhibitor of the wild type ER. In transient transfection assays using ER-negative Chinese hamster ovary (CHO) cells and two different estrogen response element (ERE)-containing promoter reporter genes, V364E treated with 10(-8) M E2 exhibited approximately 250% and 100% of the activity of the wild type ER with these two promoter contexts, respectively. Despite the high activity of V364E when present alone in cells, coexpression of both V364E and wild type ER causes a significant decrease in overall ER-mediated transcriptional activity. On the TATA promoter, where V364E was more inhibitory, estrogen-stimulated activity was reduced by approximately 50% at a 1:1 ratio of mutant to wild type ER expression vector, and at a 10:1 ratio, 75% of ER activity was inhibited. V364E was expressed at lower levels than wild type ER and has a approximately 40-fold lower affinity for E2 compared with wild type ER. In promoter interference assays, V364E exhibited a strict dependence upon E2 for binding to an ERE. Surprisingly, even when V364E was unable to bind to ERE DNA (i.e. either at low E2 concentration or by mutation of its DNA-binding domain), this mutant retained full dominant negative activity. This highly active ER mutant is, thus, able to repress ER-mediated transcription when the mutant and wild type ER are present together in cells, even without DNA binding. Since competition for ERE binding and the formation of inactive heterodimers cannot fully account for the dominant negative activity of V364E, it is probable that altered interactions with proteins important in ER-mediated transcription play a key role in the repression of transcription by V364E. The properties and probable

The effect of citalopram hydrobromide on 5-HT2A receptors in the impulsive-aggressive dog, as measured with 123I-5-I-R91150 SPECT

International Nuclear Information System (INIS)

Peremans, K.; Hoybergs, Y.; Gielen, I.; Audenaert, K.; Vervaet, M.; Heeringen, C. van; Otte, A.; Goethals, I.; Dierckx, R.; Blankaert, P.

2005-01-01

Involvement of the serotonergic system in impulsive aggression has been demonstrated in both human and animal studies. The purpose of the present study was to investigate the effect of citalopram hydrobromide (a selective serotonin re-uptake inhibitor) on the 5-HT 2A receptor and brain perfusion in impulsive-aggressive dogs by means of single-photon emission computed tomography. The binding index of the radioligand 123 I-5-I-R91150 was measured before and after treatment with citalopram hydrobromide in nine impulsive-aggressive dogs. Regional perfusion was measured with 99m Tc-ethyl cysteinate dimer (ECD). Behaviour was assessed before treatment and again after 6 weeks of treatment. A correlation was found between decreased binding and behavioural improvement in eight out of nine dogs. The 5-HT 2A receptor binding index was significantly reduced after citalopram hydrobromide treatment in all cortical regions but not in the subcortical area. None of the dogs displayed alterations in perfusion on the post-treatment scans. This study supports previous findings regarding the involvement of the serotonergic system in impulsive aggression in dogs in general. More specifically, the effect of treatment on the 5-HT 2A receptor binding index could be demonstrated and the decreased binding index correlated with behavioural improvement. (orig.)

Modeling the interactions of a peptide-major histocompatibility class I ligand with its receptors. II. Cross-reaction between a monoclonal antibody and two alpha beta T cell receptors

DEFF Research Database (Denmark)

Rognan, D; Engberg, J; Stryhn, A

2000-01-01

-peptide pair into the Fab combining site. Interestingly, the most energetically favored binding mode shows numerous analogies to the recently determined recognition of class I MHC-peptide complexes by alpha beta T cell receptors (TCRs). The pSAN13.4.1 also binds diagonally across the MHC binding groove......The recombinant antibody, pSAN13.4.1, has a unique T cell like specificity; it binds an Influenza Hemagglutinin octapeptide (Ha255-262) in an MHC (H-2Kk)-restricted manner, and a detailed comparison of the fine specificity of pSAN13.4.1 with the fine specificity of two Ha255-262-specific, H-2Kk......-restricted T cell hybridomas has supported this contention. A three-dimensional model of pSAN13.4.1 has been derived by homology modeling techniques. Subsequently, the structure of the pSAN13.4.1 antibody in complex with the antigenic Ha-Kk ligand was derived after a flexible and automated docking of the MHC...

Rescue of a pathogenic mutant human glucagon receptor by pharmacological chaperones.

Science.gov (United States)

Yu, Run; Chen, Chun-Rong; Liu, Xiaohong; Kodra, János T

2012-10-01

We have previously demonstrated that a homozygous inactivating P86S mutation of the glucagon receptor (GCGR) causes a novel human disease of hyperglucagonemia, pancreatic α-cell hyperplasia, and pancreatic neuroendocrine tumors (Mahvash disease). The mechanisms for the decreased activity of the P86S mutant (P86S) are abnormal receptor localization to the endoplasmic reticulum (ER) and defective interaction with glucagon. To search for targeted therapies for Mahvash disease, we examined whether P86S can be trafficked to the plasma membrane by pharmacological chaperones and whether novel glucagon analogs restore effective receptor interaction. We used enhanced green fluorescent protein-tagged P86S stably expressed in HEK 293 cells to allow fluorescence imaging and western blotting and molecular modeling to design novel glucagon analogs in which alanine 19 was replaced with serine or asparagine. Incubation at 27 °C largely restored normal plasma membrane localization and normal processing of P86S but osmotic chaperones had no effects. The ER stressors thapsigargin and curcumin partially rescued P86S. The lipophilic GCGR antagonist L-168,049 also partially rescued P86S, so did Cpd 13 and 15 to a smaller degree. The rescued P86S led to more glucagon-stimulated cAMP production and was internalized by glucagon. Compared with the native glucagon, the novel glucagon analogs failed to stimulate more cAMP production by P86S. We conclude that the mutant GCGR is partially rescued by several pharmacological chaperones and our data provide proof-of-principle evidence that Mahvash disease can be potentially treated with pharmacological chaperones. The novel glucagon analogs, however, failed to interact with P86S more effectively.

The extracellular loop 2 (ECL2 of the human histamine H4 receptor substantially contributes to ligand binding and constitutive activity.

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David Wifling

Full Text Available In contrast to the corresponding mouse and rat orthologs, the human histamine H4 receptor (hH4R shows extraordinarily high constitutive activity. In the extracellular loop (ECL, replacement of F169 by V as in the mouse H4R significantly reduced constitutive activity. Stabilization of the inactive state was even more pronounced for a double mutant, in which, in addition to F169V, S179 in the ligand binding site was replaced by M. To study the role of the FF motif in ECL2, we generated the hH4R-F168A mutant. The receptor was co-expressed in Sf9 insect cells with the G-protein subunits Gαi2 and Gβ1γ2, and the membranes were studied in [3H]histamine binding and functional [35S]GTPγS assays. The potency of various ligands at the hH4R-F168A mutant decreased compared to the wild-type hH4R, for example by 30- and more than 100-fold in case of the H4R agonist UR-PI376 and histamine, respectively. The high constitutive activity of the hH4R was completely lost in the hH4R-F168A mutant, as reflected by neutral antagonism of thioperamide, a full inverse agonist at the wild-type hH4R. By analogy, JNJ7777120 was a partial inverse agonist at the hH4R, but a partial agonist at the hH4R-F168A mutant, again demonstrating the decrease in constitutive activity due to F168A mutation. Thus, F168 was proven to play a key role not only in ligand binding and potency, but also in the high constitutive activity of the hH4R.

The G protein Gi1 exhibits basal coupling but not preassembly with G protein-coupled receptors.

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Bondar, Alexey; Lazar, Josef

2017-06-09

The G i/o protein family transduces signals from a diverse group of G protein-coupled receptors (GPCRs). The observed specificity of G i/o -GPCR coupling and the high rate of G i/o signal transduction have been hypothesized to be enabled by the existence of stable associates between G i/o proteins and their cognate GPCRs in the inactive state (G i/o -GPCR preassembly). To test this hypothesis, we applied the recently developed technique of two-photon polarization microscopy (2PPM) to Gα i1 subunits labeled with fluorescent proteins and four GPCRs: the α 2A -adrenergic receptor, GABA B , cannabinoid receptor type 1 (CB 1 R), and dopamine receptor type 2. Our experiments with non-dissociating mutants of fluorescently labeled Gα i1 subunits (exhibiting impaired dissociation from activated GPCRs) showed that 2PPM is capable of detecting GPCR-G protein interactions. 2PPM experiments with non-mutated fluorescently labeled Gα i1 subunits and α 2A -adrenergic receptor, GABA B , or dopamine receptor type 2 receptors did not reveal any interaction between the G i1 protein and the non-stimulated GPCRs. In contrast, non-stimulated CB 1 R exhibited an interaction with the G i1 protein. Further experiments revealed that this interaction is caused solely by CB 1 R basal activity; no preassembly between CB 1 R and the G i1 protein could be observed. Our results demonstrate that four diverse GPCRs do not preassemble with non-active G i1 However, we also show that basal GPCR activity allows interactions between non-stimulated GPCRs and G i1 (basal coupling). These findings suggest that G i1 interacts only with active GPCRs and that the well known high speed of GPCR signal transduction does not require preassembly between G proteins and GPCRs. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The chicken type III GnRH receptor homologue is predominantly expressed in the pituitary, and exhibits similar ligand selectivity to the type I receptor

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Joseph, Nerine T; Morgan, Kevin; Sellar, Robin; McBride, Derek; Millar, Robert P; Dunn, Ian C

2009-01-01

Two GnRH isoforms (cGnRH-I and GnRH-II) and two GnRH receptor subtypes (cGnRH-R-I and cGnRH-R-III) occur in chickens. Differential roles for these molecules in regulating gonadotrophin secretion or other functions are unclear. To investigate this we cloned cGnRH-R-III from a broiler chicken and compared its structure, expression and pharmacological properties with cGnRH-R-I. The broiler cGnRH-R-III cDNA was 100% identical to the sequence reported in the red jungle fowl and white leghorn breed. Pituitary cGnRH-R-III mRNA was ∼1400-fold more abundant than cGnRH-R-I mRNA. Northern analysis indicated a single cGnRH-R-III transcript. A pronounced sex and age difference existed, with higher pituitary transcript levels in sexually mature females versus juvenile females. In contrast, higher expression levels occurred in juvenile males versus sexually mature males. Functional studies in COS-7 cells indicated that cGnRH-R-III has a higher binding affinity for GnRH-II than cGnRH-I (Kd: 0·57 vs 19·8 nM) with more potent stimulation of inositol phosphate production (ED50: 0·8 vs 4·38 nM). Similar results were found for cGnRH-R-I, (Kd: 0·51 vs 10·8 nM) and (ED50: 0·7 vs 2·8 nM). The initial rate of internalisation was faster for cGnRH-R-III than cGnRH-R-I (26 vs 15·8%/min). Effects of GnRH antagonists were compared at the two receptors. Antagonist #27 distinguished between cGnRH-R-I and cGnRH-R-III (IC50: 2·3 vs 351 nM). These results suggest that cGnRH-R-III is probably the major mediator of pituitary gonadotroph function, that antagonist #27 may allow delineation of receptor subtype function in vitro and in vivo and that tissue-specific recruitment of cGnRH-R isoforms has occurred during evolution. PMID:19380456

Type-I Insulin-Like Growth Factor Receptor (IGF1R)-Estrogen Receptor (ER) Crosstalk Contributes to Antiestrogen Therapy Resistance in Breast Cancer Cells

Science.gov (United States)

2013-02-01

vitro have downregulated J GF1R making antibodies directed agai nst th is receptor ineffective. Inhlbition of IH may be necessary to manage ...monoclonal antibody to insulin-like growth factor receptor 1. J Clin Oncol 2009;27:580Q-7. 31. Drury s. Detre s. Leary A, Salter J, Reis-Filho J

Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

Energy Technology Data Exchange (ETDEWEB)

Zirak, P. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Hegemann, P.; Mathes, T. [Institut fuer Biologie, Experimentelle Biophysik, Humboldt-Universitaet zu Berlin, Invalidenstr. 42, D-10115 Berlin (Germany)

2007-05-21

The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster ({tau}{sub rec} {approx} 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be {phi}{sub s} {approx} 0.3 (for AppA-wt: {phi}{sub s} {approx} 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed.

Regulation of protease-activated receptor 1 signaling by the adaptor protein complex 2 and R4 subfamily of regulator of G protein signaling proteins.

Science.gov (United States)

Chen, Buxin; Siderovski, David P; Neubig, Richard R; Lawson, Mark A; Trejo, Joann

2014-01-17

The G protein-coupled protease-activated receptor 1 (PAR1) is irreversibly proteolytically activated by thrombin. Hence, the precise regulation of PAR1 signaling is important for proper cellular responses. In addition to desensitization, internalization and lysosomal sorting of activated PAR1 are critical for the termination of signaling. Unlike most G protein-coupled receptors, PAR1 internalization is mediated by the clathrin adaptor protein complex 2 (AP-2) and epsin-1, rather than β-arrestins. However, the function of AP-2 and epsin-1 in the regulation of PAR1 signaling is not known. Here, we report that AP-2, and not epsin-1, regulates activated PAR1-stimulated phosphoinositide hydrolysis via two different mechanisms that involve, in part, a subset of R4 subfamily of "regulator of G protein signaling" (RGS) proteins. A significantly greater increase in activated PAR1 signaling was observed in cells depleted of AP-2 using siRNA or in cells expressing a PAR1 (420)AKKAA(424) mutant with defective AP-2 binding. This effect was attributed to AP-2 modulation of PAR1 surface expression and efficiency of G protein coupling. We further found that ectopic expression of R4 subfamily members RGS2, RGS3, RGS4, and RGS5 reduced activated PAR1 wild-type signaling, whereas signaling by the PAR1 AKKAA mutant was minimally affected. Intriguingly, siRNA-mediated depletion analysis revealed a function for RGS5 in the regulation of signaling by the PAR1 wild type but not the AKKAA mutant. Moreover, activation of the PAR1 wild type, and not the AKKAA mutant, induced Gαq association with RGS3 via an AP-2-dependent mechanism. Thus, AP-2 regulates activated PAR1 signaling by altering receptor surface expression and through recruitment of RGS proteins.

Acute Cocaine Induces Fast Activation of D1 Receptor and Progressive Deactivation of D2 Receptor Strial Neurons: In Vivo Optical Microprobe [Ca2+]i Imaging

International Nuclear Information System (INIS)

Du, C.; Luo, Z.; Volkow, N.D.; Heintz, N.; Pan, Y.; Du, C.

2011-01-01

Cocaine induces fast dopamine increases in brain striatal regions, which are recognized to underlie its rewarding effects. Both dopamine D1 and D2 receptors are involved in cocaine's reward but the dynamic downstream consequences of cocaine effects in striatum are not fully understood. Here we used transgenic mice expressing EGFP under the control of either the D1 receptor (D1R) or the D2 receptor (D2R) gene and microprobe optical imaging to assess the dynamic changes in intracellular calcium ([Ca 2+ ] i ) responses (used as marker of neuronal activation) to acute cocaine in vivo separately for D1R- versus D2R-expressing neurons in striatum. Acute cocaine (8 mg/kg, i.p.) rapidly increased [Ca 2+ ] i in D1R-expressing neurons (10.6 ± 3.2%) in striatum within 8.3 ± 2.3 min after cocaine administration after which the increases plateaued; these fast [Ca 2+ ] i increases were blocked by pretreatment with a D1R antagonist (SCH23390). In contrast, cocaine induced progressive decreases in [Ca 2+ ] i in D2R-expressing neurons (10.4 ± 5.8%) continuously throughout the 30 min that followed cocaine administration; these slower [Ca 2+ ] i decreases were blocked by pretreatment with a D2R antagonist (raclopride). Since activation of striatal D1R-expressing neurons (direct-pathway) enhances cocaine reward, whereas activation of D2R expressing neurons suppresses it (indirect-pathway) (Lobo et al., 2010), this suggests that cocaine's rewarding effects entail both its fast stimulation ofD1R (resulting in abrupt activation of direct-pathway neurons) and a slower stimulation of D2R (resulting in longer-lasting deactivation of indirect-pathway neurons). We also provide direct in vivo evidence of D2R and D1R interactions in the striatal responses to acute cocaine administration.

40 CFR 255.2 - Definitions.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Definitions. 255.2 Section 255.2 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES IDENTIFICATION OF REGIONS AND AGENCIES FOR SOLID WASTE MANAGEMENT General Provisions § 255.2 Definitions. The Act contains an...

Characteristics of recombinantly expressed rat and human histamine H3 receptors.

Science.gov (United States)

Wulff, Birgitte S; Hastrup, Sven; Rimvall, Karin

2002-10-18

Human and rat histamine H(3) receptors were recombinantly expressed and characterized using receptor binding and a functional cAMP assay. Seven of nine agonists had similar affinities and potencies at the rat and human histamine H(3) receptor. S-alpha-methylhistamine had a significantly higher affinity and potency at the human than rat receptor, and for 4-[(1R*,2R*)-2-(5,5-dimethyl-1-hexynyl)cyclopropyl]-1H-imidazole (Perceptin) the preference was the reverse. Only two of six antagonists had similar affinities and potencies at the human and the rat histamine H(3) receptor. Ciproxifan, thioperamide and (1R*,2R*)-trans-2-imidazol-4 ylcyclopropyl) (cyclohexylmethoxy) carboxamide (GT2394) had significantly higher affinities and potencies at the rat than at the human histamine H(3) receptor, while for N-(4-chlorobenzyl)-N-(7-pyrrolodin-1-ylheptyl)guanidine (JB98064) the preference was the reverse. All antagonists also showed potent inverse agonism properties. Iodoproxyfan, Perceptin, proxyfan and GR175737, compounds previously described as histamine H(3) receptor antagonists, acted as full or partial agonists at both the rat and the human histamine H(3) receptor. Copyright 2002 Elsevier Science B.V.

40 CFR 96.255 - Banking.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Banking. 96.255 Section 96.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET... Tracking System § 96.255 Banking. (a) CAIR SO2 allowances may be banked for future use or transfer in a...

20 CFR 255.11 - Fault.

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than the...

Ac-Trp-DPhe(p-I)-Arg-Trp-NH2, a 250-Fold Selective Melanocortin-4 Receptor (MC4R) Antagonist over the Melanocortin-3 Receptor (MC3R), Affects Energy Homeostasis in Male and Female Mice Differently.

Science.gov (United States)

Lensing, Cody J; Adank, Danielle N; Doering, Skye R; Wilber, Stacey L; Andreasen, Amy; Schaub, Jay W; Xiang, Zhimin; Haskell-Luevano, Carrie

2016-09-21

The melanocortin-4 receptor (MC4R) has been indicated as a therapeutic target for metabolic disorders such as anorexia, cachexia, and obesity. The current study investigates the in vivo effects on energy homeostasis of a 15 nM MC4R antagonist SKY2-23-7, Ac-Trp-DPhe(p-I)-Arg-Trp-NH2, that is a 3700 nM melanocortin-3 receptor (MC3R) antagonist with minimal MC3R and MC4R agonist activity. When monitoring both male and female mice in TSE metabolic cages, sex-specific responses were observed in food intake, respiratory exchange ratio (RER), and energy expenditure. A 7.5 nmol dose of SKY2-23-7 increased food intake, increased RER, and trended toward decreasing energy expenditure in male mice. However, this compound had minimal effect on female mice's food intake and RER at the 7.5 nmol dose. A 2.5 nmol dose of SKY2-23-7 significantly increased female food intake, RER, and energy expenditure while having a minimal effect on male mice at this dose. The observed sex differences of SKY2-23-7 administration result in the discovery of a novel chemical probe for elucidating the molecular mechanisms of the sexual dimorphism present within the melanocortin pathway. To further explore the melanocortin sexual dimorphism, hypothalamic gene expression was examined. The mRNA expression of the MC3R and proopiomelanocortin (POMC) were not significantly different between sexes. However, the expression of agouti-related peptide (AGRP) was significantly higher in female mice which may be a possible mechanism for the sex-specific effects observed with SKY2-23-7.

Gene editing rescue of a novel MPL mutant associated with congenital amegakaryocytic thrombocytopenia.

Science.gov (United States)

Cleyrat, Cédric; Girard, Romain; Choi, Eun H; Jeziorski, Éric; Lavabre-Bertrand, Thierry; Hermouet, Sylvie; Carillo, Serge; Wilson, Bridget S

2017-09-26

Thrombopoietin (Tpo) and its receptor (Mpl) are the principal regulators of early and late thrombopoiesis and hematopoietic stem cell maintenance. Mutations in MPL can drastically impair its function and be a contributing factor in multiple hematologic malignancies, including congenital amegakaryocytic thrombocytopenia (CAMT). CAMT is characterized by severe thrombocytopenia at birth, which progresses to bone marrow failure and pancytopenia. Here we report unique familial cases of CAMT that presented with a previously unreported MPL mutation: T814C (W272R) in the background of the activating MPL G117T (K39N or Baltimore) mutation. Confocal microscopy, proliferation and surface biotinylation assays, co-immunoprecipitation, and western blotting analysis were used to elucidate the function and trafficking of Mpl mutants. Results showed that Mpl protein bearing the W272R mutation, alone or together with the K39N mutation, lacks detectable surface expression while being strongly colocalized with the endoplasmic reticulum (ER) marker calreticulin. Both WT and K39N-mutated Mpl were found to be signaling competent, but single or double mutants bearing W272R were unresponsive to Tpo. Function of the deficient Mpl receptor could be rescued by using 2 separate approaches: (1) GRASP55 overexpression, which partially restored Tpo-induced signaling of mutant Mpl by activating an autophagy-dependent secretory pathway and thus forcing ER-trapped immature receptors to traffic to the cell surface; and (2) CRISPR-Cas9 gene editing used to repair MPL T814C mutation in transfected cell lines and primary umbilical cord blood-derived CD34 + cells. We demonstrate proof of principle for rescue of mutant Mpl function by using gene editing of primary hematopoietic stem cells, which indicates direct therapeutic applications for CAMT patients.

Increased abundance of insulin/insulin-like growth factor-I hybrid receptors in skeletal muscle of obese subjects is correlated with in vivo insulin sensitivity.

Science.gov (United States)

Federici, M; Porzio, O; Lauro, D; Borboni, P; Giovannone, B; Zucaro, L; Hribal, M L; Sesti, G

1998-08-01

We reported that in noninsulin-dependent diabetes melitus (NIDDM) patients expression of insulin/insulin-like growth factor I (IGF-I) hybrid receptors is increased in insulin target tissues. Whether this is a defect associated with NIDDM or represents a generalized abnormality associated with insulin resistant states is still unsettled. To address this, we applied a microwell-based immunoassay to measure abundance of insulin receptors, type 1 IGF receptors, and hybrid receptors in muscle of eight normal and eight obese subjects. Maximal insulin binding to insulin receptors was lower in obese than in control subjects (B/T = 1.8 +/- 0.20 and 2.6 +/- 0.30; P < 0.03, respectively) and was negatively correlated with insulinemia (r = -0.60; P < 0.01). Maximal IGF-I binding to type 1 IGF receptors was higher in obese than in controls (B/T = 1.9 +/- 0.20 and 0.86 +/- 0.10; P < 0.0001, respectively) and was negatively correlated with plasma IGF-I levels (r = -0.69; P < 0.003). Hybrid receptor abundance was higher in obese than in normal subjects (B/T = 1.21 +/- 0.14 and 0.44 +/- 0.06; P < 0.0003, respectively) and was negatively correlated with insulin binding (r = -0.60; P < 0.01) and positively correlated with IGF-I binding (r = 0.92; P < 0.0001). Increased abundance of hybrids was correlated with insulinemia (r = 0.70; P < 0.002) and body mass index (r = 0.71; P < 0.0019), whereas it was negatively correlated with in vivo insulin sensitivity measured by ITT (r = -0.67; P < 0.016). These results indicate that downregulation of insulin receptors or upregulation of type 1 IGF receptors because of changes in plasma insulin and IGF-I levels may result in modifications in hybrid receptor abundance.

The effect of citalopram hydrobromide on 5-HT{sub 2A} receptors in the impulsive-aggressive dog, as measured with {sup 123}I-5-I-R91150 SPECT

Energy Technology Data Exchange (ETDEWEB)

Peremans, K.; Hoybergs, Y.; Gielen, I. [Ghent University, Department of Medical Imaging, Faculty of Veterinary Medicine, Merelbeke (Belgium); Audenaert, K.; Vervaet, M.; Heeringen, C. van [Ghent University, Department of Psychiatry and Medical Psychology, Gent (Belgium); Otte, A.; Goethals, I.; Dierckx, R. [Ghent University Hospital, Division of Nuclear Medicine, Gent (Belgium); Blankaert, P. [Ghent University, Laboratory of Radiopharmacy, Gent (Belgium)

2005-06-01

Involvement of the serotonergic system in impulsive aggression has been demonstrated in both human and animal studies. The purpose of the present study was to investigate the effect of citalopram hydrobromide (a selective serotonin re-uptake inhibitor) on the 5-HT{sub 2A} receptor and brain perfusion in impulsive-aggressive dogs by means of single-photon emission computed tomography. The binding index of the radioligand {sup 123}I-5-I-R91150 was measured before and after treatment with citalopram hydrobromide in nine impulsive-aggressive dogs. Regional perfusion was measured with {sup 99m}Tc-ethyl cysteinate dimer (ECD). Behaviour was assessed before treatment and again after 6 weeks of treatment. A correlation was found between decreased binding and behavioural improvement in eight out of nine dogs. The 5-HT{sub 2A} receptor binding index was significantly reduced after citalopram hydrobromide treatment in all cortical regions but not in the subcortical area. None of the dogs displayed alterations in perfusion on the post-treatment scans. This study supports previous findings regarding the involvement of the serotonergic system in impulsive aggression in dogs in general. More specifically, the effect of treatment on the 5-HT{sub 2A} receptor binding index could be demonstrated and the decreased binding index correlated with behavioural improvement. (orig.)

7 CFR 65.255 - United States.

Science.gov (United States)

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false United States. 65.255 Section 65.255 Agriculture..., PEANUTS, AND GINSENG General Provisions Definitions § 65.255 United States. United States means the 50... United States. ...

Furfural and hydroxymethylfurfural tolerance in Escherichia coli ΔacrR regulatory mutants.

Science.gov (United States)

Luhe, Annette Lin; Lim, Chan Yuen; Gerken, Henri; Wu, Jinchuan; Zhao, Hua

2015-01-01

The presence of the highly toxic furfural and hydroxymethylfurfural (HMF) in the hydrolysate of lignocellulosic biomass prompted the investigation of the Escherichia coli ΔacrR regulatory mutant for higher tolerance to these compounds, to facilitate the production of biofuels and biochemicals, and further biocatalytic conversions. In comparison with the parental strain, the regulatory mutant with the upregulated efflux pump AcrAB-TolC produced moderately better growth and higher tolerance to concentrations of furfural and HMF between 1 and 2 g L(-1) . © 2014 International Union of Biochemistry and Molecular Biology, Inc.

Growth hormone-releasing hormone as an agonist of the ghrelin receptor GHS-R1a.

Science.gov (United States)

Casanueva, Felipe F; Camiña, Jesus P; Carreira, Marcos C; Pazos, Yolanda; Varga, Jozsef L; Schally, Andrew V

2008-12-23

Ghrelin synergizes with growth hormone-releasing hormone (GHRH) to potentiate growth hormone (GH) response through a mechanism not yet fully characterized. This study was conducted to analyze the role of GHRH as a potential ligand of the ghrelin receptor, GHS-R1a. The results show that hGHRH(1-29)NH(2) (GHRH) induces a dose-dependent calcium mobilization in HEK 293 cells stably transfected with GHS-R1a an effect not observed in wild-type HEK 293 cells. This calcium rise is also observed using the GHRH receptor agonists JI-34 and JI-36. Radioligand binding and cross-linking studies revealed that calcium response to GHRH is mediated by the ghrelin receptor GHS-R1a. GHRH activates the signaling route of inositol phosphate and potentiates the maximal response to ghrelin measured in inositol phosphate turnover. The presence of GHRH increases the binding capacity of (125)I-ghrelin in a dose dependent-fashion showing a positive binding cooperativity. In addition, confocal microscopy in CHO cells transfected with GHS-R1a tagged with enhanced green fluorescent protein shows that GHRH activates the GHS-R1a endocytosis. Furthermore, the selective GHRH-R antagonists, JV-1-42 and JMR-132, act also as antagonists of the ghrelin receptor GHS-R1a. Our findings suggest that GHRH interacts with ghrelin receptor GHS-R1a, and, in consequence, modifies the ghrelin-associated intracellular signaling pathway. This interaction may represent a form of regulation, which could play a putative role in the physiology of GH regulation and appetite control.

Function of the cytoplasmic tail of human calcitonin receptor-like receptor in complex with receptor activity-modifying protein 2

Energy Technology Data Exchange (ETDEWEB)

Kuwasako, Kenji, E-mail: kuwasako@fc.miyazaki-u.ac.jp [Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan); Kitamura, Kazuo; Nagata, Sayaka; Hikosaka, Tomomi [Division of Circulation and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan); Kato, Johji [Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan)

2010-02-12

Receptor activity-modifying protein 2 (RAMP2) enables calcitonin receptor-like receptor (CRLR) to form an adrenomedullin (AM)-specific receptor. Here we investigated the function of the cytoplasmic C-terminal tail (C-tail) of human (h)CRLR by co-transfecting its C-terminal mutants into HEK-293 cells stably expressing hRAMP2. Deleting the C-tail from CRLR disrupted AM-evoked cAMP production or receptor internalization, but did not affect [{sup 125}I]AM binding. We found that CRLR residues 428-439 are required for AM-evoked cAMP production, though deleting this region had little effect on receptor internalization. Moreover, pretreatment with pertussis toxin (100 ng/mL) led to significant increases in AM-induced cAMP production via wild-type CRLR/RAMP2 complexes. This effect was canceled by deleting CRLR residues 454-457, suggesting Gi couples to this region. Flow cytometric analysis revealed that CRLR truncation mutants lacking residues in the Ser/Thr-rich region extending from Ser{sup 449} to Ser{sup 467} were unable to undergo AM-induced receptor internalization and, in contrast to the effect on wild-type CRLR, overexpression of GPCR kinases-2, -3 and -4 failed to promote internalization of CRLR mutants lacking residues 449-467. Thus, the hCRLR C-tail is crucial for AM-evoked cAMP production and internalization of the CRLR/RAMP2, while the receptor internalization is dependent on the aforementioned GPCR kinases, but not Gs coupling.

Altered expression patterns of group I and II metabotropic glutamate receptors in multiple sclerosis

NARCIS (Netherlands)

Geurts, J. J. G.; Wolswijk, G.; Bö, L.; van der Valk, P.; Polman, C. H.; Troost, D.; Aronica, E.

2003-01-01

Recent evidence supports a role for glutamate receptors in the pathophysiology of multiple sclerosis. In the present study, we have focused specifically on the expression of metabotropic glutamate receptors (mGluRs) in multiple sclerosis brain tissue. The expression of group I (mGluR1alpha and

Insulin and IGF1 Receptors Are Essential for XX and XY Gonadal Differentiation and Adrenal Development in Mice

Science.gov (United States)

Romero, Yannick; Conne, Béatrice; Truong, Vy; Papaioannou, Marilena D.; Schaad, Olivier; Docquier, Mylène; Herrera, Pedro Luis; Wilhelm, Dagmar; Nef, Serge

2013-01-01

Mouse sex determination provides an attractive model to study how regulatory genetic networks and signaling pathways control cell specification and cell fate decisions. This study characterizes in detail the essential role played by the insulin receptor (INSR) and the IGF type I receptor (IGF1R) in adrenogenital development and primary sex determination. Constitutive ablation of insulin/IGF signaling pathway led to reduced proliferation rate of somatic progenitor cells in both XX and XY gonads prior to sex determination together with the downregulation of hundreds of genes associated with the adrenal, testicular, and ovarian genetic programs. These findings indicate that prior to sex determination somatic progenitors in Insr;Igf1r mutant gonads are not lineage primed and thus incapable of upregulating/repressing the male and female genetic programs required for cell fate restriction. In consequence, embryos lacking functional insulin/IGF signaling exhibit (i) complete agenesis of the adrenal cortex, (ii) embryonic XY gonadal sex reversal, with a delay of Sry upregulation and the subsequent failure of the testicular genetic program, and (iii) a delay in ovarian differentiation so that Insr;Igf1r mutant gonads, irrespective of genetic sex, remained in an extended undifferentiated state, before the ovarian differentiation program ultimately is initiated at around E16.5. PMID:23300479

Receptor tyrosine phosphatase R-PTP-kappa mediates homophilic binding

DEFF Research Database (Denmark)

Sap, J; Jiang, Y P; Friedlander, D

1994-01-01

Receptor tyrosine phosphatases (R-PTPases) feature PTPase domains in the context of a receptor-like transmembrane topology. The R-PTPase R-PTP-kappa displays an extracellular domain composed of fibronectin type III motifs, a single immunoglobulin domain, as well as a recently defined MAM domain (Y...... not require PTPase activity or posttranslational proteolytic cleavage of the R-PTP-kappa protein and is calcium independent. The results suggest that R-PTPases may provide a link between cell-cell contact and cellular signaling events involving tyrosine phosphorylation....

Signal transduction by normal isoforms and W mutant variants of the Kit receptor tyrosine kinase.

Science.gov (United States)

Reith, A D; Ellis, C; Lyman, S D; Anderson, D M; Williams, D E; Bernstein, A; Pawson, T

1991-09-01

Germline mutations at the Dominant White Spotting (W) and Steel (Sl) loci have provided conclusive genetic evidence that c-kit mediated signal transduction pathways are essential for normal mouse development. We have analysed the interactions of normal and mutant W/c-kit gene products with cytoplasmic signalling proteins, using transient c-kit expression assays in COS cells. In addition to the previously identified c-kit gene product (Kit+), a second normal Kit isoform (KitA+) containing an in-frame insertion, Gly-Asn-Asn-Lys, within the extracellular domain, was detected in murine mast cell cultures and mid-gestation placenta. Both Kit+ and KitA+ isoforms showed increased autophosphorylation and enhanced association with phosphatidylinositol (PI) 3' kinase and PLC gamma 1, when stimulated with recombinant soluble Steel factor. No association or increase in phosphorylation of GAP and two GAP-associated proteins, p62 and p190, was observed. The two isoforms had distinct activities in the absence of exogenous soluble Steel factor; Kit+, but not KitA+, showed constitutive tyrosine phosphorylation that was accompanied by a low constitutive level of association with PI-3' kinase and PLC gamma 1. Introduction of the point substitutions associated with W37 (Glu582----Lys) or W41 (Val831----Met) mutant alleles into c-kit expression constructs abolished (W37) or reduced (W41) the Steel factor-induced association of the Kit receptor with signalling proteins in a manner proportional to the overall severity of the corresponding W mutant phenotype. These data suggest a diversity of normal Kit signalling pathways and indicate that W mutant phenotypes result from primary defects in the Kit receptor that affect its interaction with cytoplasmic signalling proteins.

Accumulation of infectious mutants in stocks during the propagation of fiber-modified recombinant adenoviruses

International Nuclear Information System (INIS)

Ugai, Hideyo; Inabe, Kumiko; Yamasaki, Takahito; Murata, Takehide; Obata, Yuichi; Hamada, Hirofumi; Yokoyama, Kazunari K.

2005-01-01

In infected cells, replication errors during viral proliferation generate mutations in adenoviruses (Ads), and the mutant Ads proliferate and evolve in the intracellular environment. Genetically fiber-modified recombinant Ads (rAd variants) were generated, by modification of the fiber gene, for therapeutic applications in host cells that lack or express reduced levels of the Coxsackievirus and adenovirus receptor. To assess the genetic modifications of rAd variants that might induce the instability of Ad virions, we examined the frequencies of mutants that accumulated in propagated stocks. Seven of 41 lines of Ad variants generated mutants in the stocks and all mutants were infectious. Moreover, all the mutations occurred in the modified region that had been added at the 3' end of the fiber gene. Our results show that some genetic modifications at the carboxyl terminus of Ad fiber protein lead to the instability of Ad virions

Investigating the structure and dynamics of the PIK3CA wild-type and H1047R oncogenic mutant.

Directory of Open Access Journals (Sweden)

Paraskevi Gkeka

2014-10-01

Full Text Available The PIK3CA gene is one of the most frequently mutated oncogenes in human cancers. It encodes p110α, the catalytic subunit of phosphatidylinositol 3-kinase alpha (PI3Kα, which activates signaling cascades leading to cell proliferation, survival, and cell growth. The most frequent mutation in PIK3CA is H1047R, which results in enzymatic overactivation. Understanding how the H1047R mutation causes the enhanced activity of the protein in atomic detail is central to developing mutant-specific therapeutics for cancer. To this end, Surface Plasmon Resonance (SPR experiments and Molecular Dynamics (MD simulations were carried out for both wild-type (WT and H1047R mutant proteins. An expanded positive charge distribution on the membrane binding regions of the mutant with respect to the WT protein is observed through MD simulations, which justifies the increased ability of the mutated protein variant to bind to membranes rich in anionic lipids in our SPR experiments. Our results further support an auto-inhibitory role of the C-terminal tail in the WT protein, which is abolished in the mutant protein due to loss of crucial intermolecular interactions. Moreover, Functional Mode Analysis reveals that the H1047R mutation alters the twisting motion of the N-lobe of the kinase domain with respect to the C-lobe and shifts the position of the conserved P-loop residues in the vicinity of the active site. These findings demonstrate the dynamical and structural differences of the two proteins in atomic detail and propose a mechanism of overactivation for the mutant protein. The results may be further utilized for the design of mutant-specific PI3Kα inhibitors that exploit the altered mutant conformation.

The Conserved Arginine Cluster in the Insert of the Third Cytoplasmic Loop of the Long Form of the D2 Dopamine Receptor (D2L-R Acts as an Intracellular Retention Signal

Directory of Open Access Journals (Sweden)

Valentina Kubale

2016-07-01

Full Text Available This study examined whether the conserved arginine cluster present within the 29-amino acid insert of the long form of the D2 dopamine receptor (D2L-R confers its predominant intracellular localization. We hypothesized that the conserved arginine cluster (RRR located within the insert could act as an RXR-type endoplasmic reticulum (ER retention signal. Arginine residues (R within the cluster at positions 267, 268, and 269 were charge-reserved to glutamic acids (E, either individually or in clusters, thus generating single, double, and triple D2L-R mutants. Through analyses of cellular localization by confocal microscopy and enzyme-linked immunosorbent assay (ELISA, radioligand binding assay, bioluminescence resonance energy transfer (BRET2 β-arrestin 2 (βarr2 recruitment assay, and cAMP signaling, it was revealed that charge reversal of the R residues at all three positions within the motif impaired their colocalization with ER marker calnexin and led to significantly improved cell surface expression. Additionally, these data demonstrate that an R to glutamic acid (E substitution at position 2 within the RXR motif is not functionally permissible. Furthermore, all generated D2L-R mutants preserved their functional integrity regarding ligand binding, agonist-induced βarr2 recruitment and Gαi-mediated signaling. In summary, our results show that the conserved arginine cluster within the 29-amino acid insert of third cytoplasmic loop (IC3 of the D2L-R appears to be the ER retention signal.

Group I mGlu receptors potentiate synaptosomal [3H]glutamate release independently of exogenously applied arachidonic acid

International Nuclear Information System (INIS)

Reid, M.E.; Toms, N.J.; Bedingfield, J.S.; Roberts, P.J.

1999-01-01

In the current study, we have characterized group I metabotropic glutamate (mGlu) receptor enhancement of 4-aminopyridine (4AP)-evoked [ 3 H]glutamate release from rat cerebrocortical synaptosomes. The broad spectrum mGlu receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD, 10 μM) increased 4AP-evoked [ 3 H]glutamate release (143.32±2.73% control) only in the presence of exogenously applied arachidonic acid; an effect reversed by the inclusion of bovine serum albumin (BSA, fatty acid free). In contrast, the selective group I mGlu receptor agonist (S)-3,5-dihydroxyphenylglycine (DHPG) potentiated (EC 50 =1.60±0.25 μM; E max =147.61±10.96% control) 4AP-evoked [ 3 H]glutamate release, in the absence of arachidonic acid. This potentiation could be abolished by either the selective mGlu 1 receptor antagonist (R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA, 1 mM) or the selective PKC inhibitor (Ro 31-8220, 10 μM) and was BSA-insensitive. The selective mGlu 5 receptor agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG, 300μM) was without effect. DHPG (100 μM) also potentiated both 30 mM and 50 mM K + -evoked [ 3 H]glutamate release (121.60±12.77% and 121.50±4.45% control, respectively). DHPG (100 μM) failed to influence both 4AP-stimulated 45 Ca 2+ influx and 50 mM K + -induced changes in synaptosomal membrane potential. Possible group I mGlu receptor suppression of tonic adenosine A 1 receptor, group II/III mGlu receptors or GABA B receptor activity is unlikely since 4AP-evoked [ 3 H]glutamate release was insensitive to the selective inhibitory receptor antagonists 8-cyclopentyl-1,3-dimethylxanthine, (R,S)-α-cyclopropyl-4-phosphonophenylglycine or CGP55845A, respectively. These data suggest an 'mGlu 1 receptor-like' receptor potentiates [ 3 H]glutamate release from cerebrocortical synaptosomes in the absence of exogenously applied arachidonic acid. This PKC dependent effect is unlikely to be via modulation of synaptosomal membrane

29 CFR 1910.255 - Resistance welding.

Science.gov (United States)

2010-07-01

... 29 Labor 5 2010-07-01 2010-07-01 false Resistance welding. 1910.255 Section 1910.255 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Welding, Cutting and Brazing § 1910.255 Resistance welding. (a.... Ignitron tubes used in resistance welding equipment shall be equipped with a thermal protection switch. (3...

The biological activity of the human epidermal growth factor receptor is positively regulated by its C-terminal tyrosines

DEFF Research Database (Denmark)

Helin, K; Velu, T; Martin, P

1991-01-01

mutants in the full length receptor. EGF-dependent transforming ability of the single point mutants is similar to that of the wild type, while that of double mutants is decreased and an even lower activity is present in the triple mutant. In each bioassay, including EGF-dependent focal transformation...... biologically. The EGF-R kinase activity is affected by tyrosine substitution since in vitro phosphorylation of exogenous substrates is reduced in the double and triple mutants. Autophosphorylation, in vivo and in vitro, is also reduced, but not totally abolished in the triple point mutant and Dc123 indicating......The epidermal growth factor receptor (EGF-R) C-terminus contains three conserved tyrosines (Y-1068, Y-1148, Y-1173) which are phosphorylated upon EGF activation. To clarify the functional role of these tyrosines, each has been mutated to phenylalanine and studied as single, double and triple...

Ligand-independent Thrombopoietin Mutant Receptor Requires Cell Surface Localization for Endogenous Activity*

Science.gov (United States)

Marty, Caroline; Chaligné, Ronan; Lacout, Catherine; Constantinescu, Stefan N.; Vainchenker, William; Villeval, Jean-Luc

2009-01-01

The activating W515L mutation in the thrombopoietin receptor (MPL) has been identified in primary myelofibrosis and essential thrombocythemia. MPL belongs to a subset of the cytokine receptor superfamily that requires the JAK2 kinase for signaling. We examined whether the ligand-independent MPLW515L mutant could signal intracellularly. Addition of the endoplasmic reticulum (ER) retention KDEL sequence to the receptor C terminus efficiently locked MPLW515L within its natural ER/Golgi maturation pathway. In contrast to cells expressing the parental MPLW515L, MPLW515L-KDEL-expressing FDC-P1 cells were unable to grow autonomously and to produce tumors in nude mice. When observed, tumor nodules resulted from in vivo selection of cells leaking the receptor at their surface. JAK2 co-immunoprecipitated with MPLW515L-KDEL but was not phosphorylated. We generated disulfide-bonded MPLW515L homodimers by the S402C substitution, both in the normal and KDEL context. Unlike MPLW515L-KDEL, MPLW515L-S402C-KDEL signaled constitutively and exhibited cell surface localization. These data establish that MPLW515L with appended JAK2 matures through the ER/Golgi system in an inactive conformation and suggest that the MPLW515L/JAK2 complex requires membrane localization for JAK2 phosphorylation, resulting in autonomous receptor signaling. PMID:19261614

21 CFR 173.255 - Methylene chloride.

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2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methylene chloride. 173.255 Section 173.255 Food... Solvents, Lubricants, Release Agents and Related Substances § 173.255 Methylene chloride. Methylene chloride may be present in food under the following conditions: (a) In spice oleoresins as a residue from...

20 CFR 632.255 - Program planning.

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2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Program planning. 632.255 Section 632.255... EMPLOYMENT AND TRAINING PROGRAMS Summer Youth Employment and Training Programs § 632.255 Program planning. (a... with its title IV program. (2) Native American grantees shall use the planning process described in...

Defective glycinergic synaptic transmission in zebrafish motility mutants

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Hiromi Hirata

2010-01-01

Full Text Available Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR β subunit genes. These mutants exhibit a loss of glycinergic synaptic transmission due to a lack of synaptic aggregation of GlyRs. Due to the consequent loss of reciprocal inhibition of motor circuits between the two sides of the spinal cord, motor neurons activate simultaneously on both sides resulting in bilateral contraction of axial muscles of beo mutants, eliciting the so-called ‘accordion’ phenotype. Similar defects in GlyR subunit genes have been observed in several mammals and are the basis for human hyperekplexia/startle disease. By contrast, zebrafish shocked (sho mutants have a defect in slc6a9, encoding GlyT1, a glycine transporter that is expressed by astroglial cells surrounding the glycinergic synapse in the hindbrain and spinal cord. GlyT1 mediates rapid uptake of glycine from the synaptic cleft, terminating synaptic transmission. In zebrafish sho mutants, there appears to be elevated extracellular glycine resulting in persistent inhibition of postsynaptic neurons and subsequent reduced motility, causing the ‘twitch once’ phenotype. We review current knowledge regarding zebrafish ‘accordion’ and ‘twitch once’ mutants, including beo and sho, and report the identification of a new α2 subunit that revises the phylogeny of zebrafish GlyRs.

Defective Glycinergic Synaptic Transmission in Zebrafish Motility Mutants

Science.gov (United States)

Hirata, Hiromi; Carta, Eloisa; Yamanaka, Iori; Harvey, Robert J.; Kuwada, John Y.

2009-01-01

Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo) mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR) β subunit genes. These mutants exhibit a loss of glycinergic synaptic transmission due to a lack of synaptic aggregation of GlyRs. Due to the consequent loss of reciprocal inhibition of motor circuits between the two sides of the spinal cord, motor neurons activate simultaneously on both sides resulting in bilateral contraction of axial muscles of beo mutants, eliciting the so-called ‘accordion’ phenotype. Similar defects in GlyR subunit genes have been observed in several mammals and are the basis for human hyperekplexia/startle disease. By contrast, zebrafish shocked (sho) mutants have a defect in slc6a9, encoding GlyT1, a glycine transporter that is expressed by astroglial cells surrounding the glycinergic synapse in the hindbrain and spinal cord. GlyT1 mediates rapid uptake of glycine from the synaptic cleft, terminating synaptic transmission. In zebrafish sho mutants, there appears to be elevated extracellular glycine resulting in persistent inhibition of postsynaptic neurons and subsequent reduced motility, causing the ‘twitch-once’ phenotype. We review current knowledge regarding zebrafish ‘accordion’ and ‘twitch-once’ mutants, including beo and sho, and report the identification of a new α2 subunit that revises the phylogeny of zebrafish GlyRs. PMID:20161699

Molecular determinants of ivermectin sensitivity at the glycine receptor chloride channel

DEFF Research Database (Denmark)

Lynagh, Timothy; Webb, Timothy I.; Dixon, Christine L.

2011-01-01

Ivermectin is an anthelmintic drug that works by activating glutamate-gated chloride channel receptors (GluClRs) in nematode parasites. GluClRs belong to the Cys-loop receptor family that also includes glycine receptor (GlyR) chloride channels. GluClRs and A288G mutant GlyRs are both activated...

42 CFR 447.255 - Related information.

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2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Related information. 447.255 Section 447.255 Public... Facility Services Payment Rates § 447.255 Related information. The Medicaid agency must submit, with the assurances described in § 447.253(a), the following information: (a) The amount of the estimated average...

Prediction of the damage-associated non-synonymous single nucleotide polymorphisms in the human MC1R gene.

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Hepp, Diego; Gonçalves, Gislene Lopes; de Freitas, Thales Renato Ochotorena

2015-01-01

The melanocortin 1 receptor (MC1R) is involved in the control of melanogenesis. Polymorphisms in this gene have been associated with variation in skin and hair color and with elevated risk for the development of melanoma. Here we used 11 computational tools based on different approaches to predict the damage-associated non-synonymous single nucleotide polymorphisms (nsSNPs) in the coding region of the human MC1R gene. Among the 92 nsSNPs arranged according to the predictions 62% were classified as damaging in more than five tools. The classification was significantly correlated with the scores of two consensus programs. Alleles associated with the red hair color (RHC) phenotype and with the risk of melanoma were examined. The R variants D84E, R142H, R151C, I155T, R160W and D294H were classified as damaging by the majority of the tools while the r variants V60L, V92M and R163Q have been predicted as neutral in most of the programs The combination of the prediction tools results in 14 nsSNPs indicated as the most damaging mutations in MC1R (L48P, R67W, H70Y, P72L, S83P, R151H, S172I, L206P, T242I, G255R, P256S, C273Y, C289R and R306H); C273Y showed to be highly damaging in SIFT, Polyphen-2, MutPred, PANTHER and PROVEAN scores. The computational analysis proved capable of identifying the potentially damaging nsSNPs in MC1R, which are candidates for further laboratory studies of the functional and pharmacological significance of the alterations in the receptor and the phenotypic outcomes.

Prediction of the damage-associated non-synonymous single nucleotide polymorphisms in the human MC1R gene.

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Diego Hepp

Full Text Available The melanocortin 1 receptor (MC1R is involved in the control of melanogenesis. Polymorphisms in this gene have been associated with variation in skin and hair color and with elevated risk for the development of melanoma. Here we used 11 computational tools based on different approaches to predict the damage-associated non-synonymous single nucleotide polymorphisms (nsSNPs in the coding region of the human MC1R gene. Among the 92 nsSNPs arranged according to the predictions 62% were classified as damaging in more than five tools. The classification was significantly correlated with the scores of two consensus programs. Alleles associated with the red hair color (RHC phenotype and with the risk of melanoma were examined. The R variants D84E, R142H, R151C, I155T, R160W and D294H were classified as damaging by the majority of the tools while the r variants V60L, V92M and R163Q have been predicted as neutral in most of the programs The combination of the prediction tools results in 14 nsSNPs indicated as the most damaging mutations in MC1R (L48P, R67W, H70Y, P72L, S83P, R151H, S172I, L206P, T242I, G255R, P256S, C273Y, C289R and R306H; C273Y showed to be highly damaging in SIFT, Polyphen-2, MutPred, PANTHER and PROVEAN scores. The computational analysis proved capable of identifying the potentially damaging nsSNPs in MC1R, which are candidates for further laboratory studies of the functional and pharmacological significance of the alterations in the receptor and the phenotypic outcomes.

Mutant analysis of Cdt1's function in suppressing nascent strand elongation during DNA replication in Xenopus egg extracts.

Science.gov (United States)

Nakazaki, Yuta; Tsuyama, Takashi; Azuma, Yutaro; Takahashi, Mikiko; Tada, Shusuke

2017-09-02

The initiation of DNA replication is strictly regulated by multiple mechanisms to ensure precise duplication of chromosomes. In higher eukaryotes, activity of the Cdt1 protein is temporally regulated during the cell cycle, and deregulation of Cdt1 induces DNA re-replication. In previous studies, we showed that excess Cdt1 inhibits DNA replication by suppressing progression of replication forks in Xenopus egg extracts. Here, we investigated the functional regions of Cdt1 that are required for the inhibition of DNA replication. We constructed a series of N-terminally or C-terminally deleted mutants of Cdt1 and examined their inhibitory effects on DNA replication in Xenopus egg extracts. Our results showed that the region spanning amino acids (a. a.) 255-620 is required for efficient inhibition of DNA replication, and that, within this region, a. a. 255-289 have a critical role in inhibition. Moreover, one of the Cdt1 mutants, Cdt1 R285A, was compromised with respect to the licensing activity but still inhibited DNA replication. This result suggests that Cdt1 has an unforeseen function in the negative regulation of DNA replication, and that this function is located within a molecular region that is distinct from those required for the licensing activity. Copyright © 2017 Elsevier Inc. All rights reserved.

The Environmental Neurotoxicant PCB 95 Promotes Synaptogenesis via Ryanodine Receptor-Dependent miR132 Upregulation

Science.gov (United States)

Lesiak, Adam; Zhu, Mingyan; Chen, Hao; Appleyard, Suzanne M.; Impey, Soren; Wayman, Gary A.

2014-01-01

Non–dioxin-like (NDL) polychlorinated biphenyls (PCBs) are widespread environmental contaminants linked to neuropsychological dysfunction in children. NDL PCBs increase spontaneous Ca2+ oscillations in neurons by stabilizing ryanodine receptor (RyR) calcium release channels in the open configuration, which results in CREB-dependent dendritic outgrowth. In this study, we address the question of whether activation of CREB by NDL PCBs also triggers dendritic spine formation. Nanomolar concentrations of PCB 95, a NDL congener with potent RyR activity, significantly increased spine density and the frequency of miniature EPSCs in primary dissociated rat hippocampal cultures coincident with upregulation of miR132. Inhibition of RyR, CREB, or miR132 as well as expression of a mutant p250GAP cDNA construct that is not suppressed by miR132 blocked PCB 95 effects on spines and miniature EPSCs. PCB 95 also induced spine formation via RyR- and miR132-dependent mechanisms in hippocampal slice cultures. These data demonstrate a novel mechanism of PCB developmental neurotoxicity whereby RyR sensitization modulates spine formation and synaptogenesis via CREB-mediated miR132 upregulation, which in turn suppresses the translation of p250GAP, a negative regulator of synaptogenesis. In light of recent evidence implicating miR132 dysregulation in Rett syndrome and schizophrenia, these findings identify NDL PCBs as potential environmental risk factors for neurodevelopmental disorders. PMID:24431430

Acute Cocaine Induces Fast Activation of D1 Receptor and Progressive Deactivation of D2 Receptor Strial Neurons: In Vivo Optical Microprobe [Ca(superscript)2+]subscript)i Imaging

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Du, C.; Luo, Z.; Volkow, N.D.; Heintz, N.; Pan, Y.; Du, C.

2011-09-14

Cocaine induces fast dopamine increases in brain striatal regions, which are recognized to underlie its rewarding effects. Both dopamine D1 and D2 receptors are involved in cocaine's reward but the dynamic downstream consequences of cocaine effects in striatum are not fully understood. Here we used transgenic mice expressing EGFP under the control of either the D1 receptor (D1R) or the D2 receptor (D2R) gene and microprobe optical imaging to assess the dynamic changes in intracellular calcium ([Ca{sup 2+}]{sub i} ) responses (used as marker of neuronal activation) to acute cocaine in vivo separately for D1R- versus D2R-expressing neurons in striatum. Acute cocaine (8 mg/kg, i.p.) rapidly increased [Ca{sup 2+}]{sub i} in D1R-expressing neurons (10.6 {+-} 3.2%) in striatum within 8.3 {+-} 2.3 min after cocaine administration after which the increases plateaued; these fast [Ca{sup 2+}]{sub i} increases were blocked by pretreatment with a D1R antagonist (SCH23390). In contrast, cocaine induced progressive decreases in [Ca{sup 2+}]{sub i} in D2R-expressing neurons (10.4 {+-} 5.8%) continuously throughout the 30 min that followed cocaine administration; these slower [Ca{sup 2+}]{sub i} decreases were blocked by pretreatment with a D2R antagonist (raclopride). Since activation of striatal D1R-expressing neurons (direct-pathway) enhances cocaine reward, whereas activation of D2R expressing neurons suppresses it (indirect-pathway) (Lobo et al., 2010), this suggests that cocaine's rewarding effects entail both its fast stimulation ofD1R (resulting in abrupt activation of direct-pathway neurons) and a slower stimulation of D2R (resulting in longer-lasting deactivation of indirect-pathway neurons). We also provide direct in vivo evidence of D2R and D1R interactions in the striatal responses to acute cocaine administration.

A novel albumin gene mutation (R222I) in familial dysalbuminemic hyperthyroxinemia.

Science.gov (United States)

Schoenmakers, Nadia; Moran, Carla; Campi, Irene; Agostini, Maura; Bacon, Olivia; Rajanayagam, Odelia; Schwabe, John; Bradbury, Sonia; Barrett, Timothy; Geoghegan, Frank; Druce, Maralyn; Beck-Peccoz, Paolo; O'Toole, Angela; Clark, Penelope; Bignell, Michelle; Lyons, Greta; Halsall, David; Gurnell, Mark; Chatterjee, Krishna

2014-07-01

Familial dysalbuminemic hyperthyroxinemia, characterized by abnormal circulating albumin with increased T4 affinity, causes artefactual elevation of free T4 concentrations in euthyroid individuals. Four unrelated index cases with discordant thyroid function tests in different assay platforms were investigated. Laboratory biochemical assessment, radiolabeled T4 binding studies, and ALB sequencing were undertaken. (125)I-T4 binding to both serum and albumin in affected individuals was markedly increased, comparable with known familial dysalbuminemic hyperthyroxinemia cases. Sequencing showed heterozygosity for a novel ALB mutation (arginine to isoleucine at codon 222, R222I) in all four cases and segregation of the genetic defect with abnormal biochemical phenotype in one family. Molecular modeling indicates that arginine 222 is located within a high-affinity T4 binding site in albumin, with substitution by isoleucine, which has a smaller side chain predicted to reduce steric hindrance, thereby facilitating T4 and rT3 binding. When tested in current immunoassays, serum free T4 values from R222I heterozygotes were more measurably abnormal in one-step vs two-step assay architectures. Total rT3 measurements were also abnormally elevated. A novel mutation (R222I) in the ALB gene mediates dominantly inherited dysalbuminemic hyperthyroxinemia. Susceptibility of current free T4 immunoassays to interference by this mutant albumin suggests likely future identification of individuals with this variant binding protein.

Altered metabolism of growth hormone receptor mutant mice: a combined NMR metabonomics and microarray study.

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Horst Joachim Schirra

Full Text Available BACKGROUND: Growth hormone is an important regulator of post-natal growth and metabolism. We have investigated the metabolic consequences of altered growth hormone signalling in mutant mice that have truncations at position 569 and 391 of the intracellular domain of the growth hormone receptor, and thus exhibit either low (around 30% maximum or no growth hormone-dependent STAT5 signalling respectively. These mutations result in altered liver metabolism, obesity and insulin resistance. METHODOLOGY/PRINCIPAL FINDINGS: The analysis of metabolic changes was performed using microarray analysis of liver tissue and NMR metabonomics of urine and liver tissue. Data were analyzed using multivariate statistics and Gene Ontology tools. The metabolic profiles characteristic for each of the two mutant groups and wild-type mice were identified with NMR metabonomics. We found decreased urinary levels of taurine, citrate and 2-oxoglutarate, and increased levels of trimethylamine, creatine and creatinine when compared to wild-type mice. These results indicate significant changes in lipid and choline metabolism, and were coupled with increased fat deposition, leading to obesity. The microarray analysis identified changes in expression of metabolic enzymes correlating with alterations in metabolite concentration both in urine and liver. Similarity of mutant 569 to the wild-type was seen in young mice, but the pattern of metabolites shifted to that of the 391 mutant as the 569 mice became obese after six months age. CONCLUSIONS/SIGNIFICANCE: The metabonomic observations were consistent with the parallel analysis of gene expression and pathway mapping using microarray data, identifying metabolites and gene transcripts involved in hepatic metabolism, especially for taurine, choline and creatinine metabolism. The systems biology approach applied in this study provides a coherent picture of metabolic changes resulting from impaired STAT5 signalling by the growth hormone

Evaluation of the G145R Mutant of the Hepatitis B Virus as a Minor Strain in Mother-to-Child Transmission.

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Haruki Komatsu

Full Text Available The role of the hepatitis B virus (HBV mutant G145R, with a single change in amino acid 145 of the surface protein, as a minor population remains unknown in mother-to-child transmission. The minor strain as well as the major strain of the G145R mutant were evaluated in three cohorts using a locked nucleic acid probe-based real-time PCR. The breakthrough cohort consisted of children who were born to HBV carrier mothers and became HBV carriers despite immnoprophylaxis (n = 25. The control cohort consisted of HBV carriers who had no history of receiving the hepatitis B vaccine, hepatitis B immunoglobulin or antiviral treatment (n = 126. The pregnant cohort comprised pregnant women with chronic HBV infection (n = 31. In the breakthrough cohort, 6 showed positive PCR results (major, 2; minor, 4. In the control cohort, 13 showed positive PCR results (major, 0; minor, 13. HBeAg-positive patients were prone to have the G145R mutant as a minor population. Deep sequencing was performed in a total of 32 children (PCR positive, n = 13; negative, n = 19. In the breakthrough cohort, the frequency of the G145R mutant ranged from 0.54% to 6.58%. In the control cohort, the frequency of the G145R mutant ranged from 0.42% to 4.1%. Of the 31 pregnant women, 4 showed positive PCR results (major, n = 0; minor, n = 4. All of the pregnant women were positive for HBeAg and showed a high viral load. Three babies born to 3 pregnant women with the G145R mutant were evaluated. After the completion of immunoprophylaxis, 2 infants became negative for HBsAg. The remaining infant became negative for HBsAg after the first dose of HB vaccine. G145R was detected in one-fourth of the children with immunoprophylaxis failure. However, the pre-existence of the G145R mutant as a minor population in pregnant women does not always cause breakthrough infection in infants.

dsRNA binding characterization of full length recombinant wild type and mutants Zaire ebolavirus VP35.

Science.gov (United States)

Zinzula, Luca; Esposito, Francesca; Pala, Daniela; Tramontano, Enzo

2012-03-01

The Ebola viruses (EBOVs) VP35 protein is a multifunctional major virulence factor involved in EBOVs replication and evasion of the host immune system. EBOV VP35 is an essential component of the viral RNA polymerase, it is a key participant of the nucleocapsid assembly and it inhibits the innate immune response by antagonizing RIG-I like receptors through its dsRNA binding function and, hence, by suppressing the host type I interferon (IFN) production. Insights into the VP35 dsRNA recognition have been recently revealed by structural and functional analysis performed on its C-terminus protein. We report the biochemical characterization of the Zaire ebolavirus (ZEBOV) full-length recombinant VP35 (rVP35)-dsRNA binding function. We established a novel in vitro magnetic dsRNA binding pull down assay, determined the rVP35 optimal dsRNA binding parameters, measured the rVP35 equilibrium dissociation constant for heterologous in vitro transcribed dsRNA of different length and short synthetic dsRNA of 8bp, and validated the assay for compound screening by assessing the inhibitory ability of auryntricarboxylic acid (IC(50) value of 50μg/mL). Furthermore, we compared the dsRNA binding properties of full length wt rVP35 with those of R305A, K309A and R312A rVP35 mutants, which were previously reported to be defective in dsRNA binding-mediated IFN inhibition, showing that the latter have measurably increased K(d) values for dsRNA binding and modified migration patterns in mobility shift assays with respect to wt rVP35. Overall, these results provide the first characterization of the full-length wt and mutants VP35-dsRNA binding functions. Copyright © 2012 Elsevier B.V. All rights reserved.

Pre-thymic somatic mutation leads to high mutant frequency at hypoxanthine-guanine phosphoribosyltransferase gene

Energy Technology Data Exchange (ETDEWEB)

Jett, J. [Lawrence Livermore National Lab., CA (United States)

1994-12-01

While characterizing the background mutation spectrum of the Hypoxathine-guanine phosphoribosyltransferase (HPRT) gene in a healthy population, an outlier with a high mutant frequency of thioguanine resistant lymphocytes was found. When studied at the age of 46, this individual had been smoking 60 cigarettes per day for 38 years. His mutant frequency was calculated at 3.6 and 4.2x10{sup {minus}4} for two sampling periods eight months apart. Sequencing analysis of the HPRT gene in his mutant thioguanine resistant T lymphocytes was done to find whether the cells had a high rate of mutation, or if the mutation was due to a single occurrence of mutation and, if so, when in the T lymphocyte development the mutation occurred. By T-cell receptor analysis it has been found that out of 35 thioguanine resistant clones there was no dominant gamma T cell receptor gene rearrangement. During my appointment in the Science & Engineering Research Semester, I found that 34 of those clones have the same base substitution of G{yields}T at cDNA position 197. Due to the consistent mutant frequency from both sampling periods and the varying T cell receptors, the high mutant frequency cannot be due to recent proliferation of a mature mutant T lymphocyte. From the TCR and DNA sequence analysis we conclude that the G{yields}T mutation must have occurred in a T lymphocyte precursor before thymic differentiation so that the thioguanine resistant clones share the same base substitution but not the same gamma T cell receptor gene.

Metabolic and molecular analyses of white mutant Vaccinium berries show down-regulation of MYBPA1-type R2R3 MYB regulatory factor.

Science.gov (United States)

Primetta, Anja K; Karppinen, Katja; Riihinen, Kaisu R; Jaakola, Laura

2015-09-01

MYBPA1-type R2R3 MYB transcription factor shows down-regulation in white mutant berries of Vaccinium uliginosum deficient in anthocyanins but not proanthocyanidins suggesting a role in the regulation of anthocyanin biosynthesis. Berries of the genus Vaccinium are among the best natural sources of flavonoids. In this study, the expression of structural and regulatory flavonoid biosynthetic genes and the accumulation of flavonoids in white mutant and blue-colored wild-type bog bilberry (V. uliginosum) fruits were measured at different stages of berry development. In contrast to high contents of anthocyanins in ripe blue-colored berries, only traces were detected by HPLC-ESI-MS in ripe white mutant berries. However, similar profile and high levels of flavonol glycosides and proanthocyanidins were quantified in both ripe white and ripe wild-type berries. Analysis with qRT-PCR showed strong down-regulation of structural genes chalcone synthase (VuCHS), dihydroflavonol 4-reductase (VuDFR) and anthocyanidin synthase (VuANS) as well as MYBPA1-type transcription factor VuMYBPA1 in white berries during ripening compared to wild-type berries. The profiles of transcript accumulation of chalcone isomerase (VuCHI), anthocyanidin reductase (VuANR), leucoanthocyanidin reductase (VuLAR) and flavonoid 3'5' hydroxylase (VuF3'5'H) were more similar between the white and the wild-type berries during fruit development, while expression of UDP-glucose: flavonoid 3-O-glucosyltransferase (VuUFGT) showed similar trend but fourfold lower level in white mutant. VuMYBPA1, the R2R3 MYB family member, is a homologue of VmMYB2 of V. myrtillus and VcMYBPA1 of V. corymbosum and belongs to MYBPA1-type MYB family which members are shown in some species to be related with proanthocyanidin biosynthesis in fruits. Our results combined with earlier data of the role of VmMYB2 in white mutant berries of V. myrtillus suggest that the regulation of anthocyanin biosynthesis in Vaccinium species could differ

Alpha-gamma decay studies of 255No

International Nuclear Information System (INIS)

Hessberger, F.P.; Ackermann, D.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P.; Lommel, B.; Mann, R.; Hofmann, S.; Antalic, S.; Saro, S.; Streicher, B.; Venhart, M.; Leino, M.; Nishio, K.; Popeko, A.G.; Yeremin, A.V.; Sulignano, B.

2006-01-01

The decay of 255 No was investigated by means of α-γ spectroscopy. The isotope was produced in the reactions 208 Pb( 48 Ca,n) 255 No, 209 Bi( 48 Ca,2n) 255 Lr EC → 255 No, and 238 U( 22 Ne,5n) 255 No. Levels of the daughter nucleus 251 Fm were assigned by α-γ coincidence measurements and on the basis of systematics. Level energies were determined precisely using measured γ-rays. The results are compared with the known level schemes of the lighter N=151 isotones 247 Cm and 249 Cf as well as with data for 253 No. (orig.)

Restriction of phage T4 internal protein I mutants by a strain of Escherichia coli

International Nuclear Information System (INIS)

Black, L.W.; Abremski, K.

1974-01-01

Phage T4 internal protein I(IPI), a small (ca, 10,000 MW), basic protein injected into the host with the phage DNA, is not required for infection of most hosts, but mutants defective in IPI are restricted by at least one naturally occurring strain of Escherichia coli, CT 596 (CT). Phages lacking IPI (IPI - ) appear to inject their DNA and bind it to the membrane of CT cells as well as wild-type phage T4 does, but shutoff of host protein synthesis, initiation of T4 protein synthesis, and cell killing are abnormal in the IPI - mutant infected CT host. The injection of IPI appears to be important in allowing T4 DNA to carry out early steps involved in takeover of this host. Restriction of IPI - phage growth by CT cells appears to be due, at least in part, to a defective prophage it harbors which renders the host resistant to successful infection by phage T4 which lack IPI or rII functions. Bacteria cured of this prophage can be infected by mutants defective in these functions. The resistance of CT cells to other coliphages, and the question of T-even phage internal protein diversity are discussed. (U.S.)

RIG-I-like receptor-induced IRF3 mediated pathway of apoptosis (RIPA: a new antiviral pathway

Directory of Open Access Journals (Sweden)

Saurabh Chattopadhyay

2016-11-01

Full Text Available Abstract The innate immune response is the first line of host defense to eliminate viral infection. Pattern recognition receptors in the cytosol, such as RIG-I-like receptors (RLR and Nod-like receptors (NLR, and membrane bound Toll like receptors (TLR detect viral infection and initiate transcription of a cohort of antiviral genes, including interferon (IFN and interferon stimulated genes (ISGs, which ultimately block viral replication. Another mechanism to reduce viral spread is through RIPA, the RLR-induced IRF3-mediated pathway of apoptosis, which causes infected cells to undergo premature death. The transcription factor IRF3 can mediate cellular antiviral responses by both inducing antiviral genes and triggering apoptosis through the activation of RIPA. The mechanism of IRF3 activation in RIPA is distinct from that of transcriptional activation; it requires linear polyubiquitination of specific lysine residues of IRF3. Using RIPA-active, but transcriptionally inactive, IRF3 mutants, it was shown that RIPA can prevent viral replication and pathogenesis in mice.

Pharmacokinetic properties of radiolabeled mutant Interleukin-2v: a PET imaging study.

Science.gov (United States)

Hartimath, Siddesh V; Manuelli, Valeria; Zijlma, Rolf; Signore, Alberto; Nayak, Tapan K; Freimoser-Grundschober, Anne; Klein, Christian; Dierckx, Rudi A J O; de Vries, Erik F J

2018-01-23

Interleukin-2 (IL2) is a cytokine that can stimulate cytotoxic immune cells to attack infected and malignant cells. Unfortunately, IL2 can also cause serious immune-related toxicity. Recently, a mutant of IL2 (IL2v) with abolished CD25 binding, increased plasma half-life and less toxicity was engineered. Unlike wild-type IL2 (wt-IL2), mutant IL2v does not bind to the α-subunit (CD25) of the high affinity IL2αβγ receptor, but only to its β and γ subunit. Here, we investigated the biological properties of IL2v and compared with the wt-IL2 using fluorine-18 and PET. [ 18 F]FB-IL2v binds specifically to IL2 receptors (IL2R) on activated human peripheral blood monocytes (hPBMCs) and is cleared mainly by the kidneys (Balb/c mice). [ 18 F]FB-IL2v PET studies in SCID mice injected with hPBMCs revealed high uptake in the implant (0.85 ± 0.15 SUV), which was significantly reduced after pretreatment with wt-IL2 or mutant IL2v (SUV 0.26 ± 0.1 and 0.46 ± 0.1, p FB-IL2v to IL2R was reversible. The volume of distribution (V T ) and the non-displaceable binding potential (BP nd ) of mutant [ 18 F]FB-IL2v in the implant were approximately 3 times lower than those of wild-type [ 18 F]FB-IL2 ( p FB-IL2v in the implant ( p FB-IL2 binds stronger to IL2R and has faster kinetics than [18F]FB-IL2v, which makes it less suitable as a therapeutic drug. [ 18 F]FB-IL2v, on the other hand, seems to have better properties for use as a therapeutic drug.

Mutations affecting RNA polymerase I-stimulated exchange and rDNA recombination in yeast

International Nuclear Information System (INIS)

Lin, Y.H.; Keil, R.L.

1991-01-01

HOT1 is a cis-acting recombination-stimulatory sequence isolated from the rDNA repeat unit of yeast. The ability of HOT1 to stimulate mitotic exchange appears to depend on its ability to promote high levels of RNA polymerase I transcription. A qualitative colony color sectoring assay was developed to screen for trans-acting mutations that alter the activity of HOT1. Both hypo-recombination and hyper-recombination mutants were isolated. Genetic analysis of seven HOT1 recombination mutants (hrm) that decrease HOT1 activity shows that they behave as recessive nuclear mutations and belong to five linkage groups. Three of these mutations, hrm1, hrm2, and hrm3, also decrease rDNA exchange but do not alter recombination in the absence of HOT1. Another mutation, hrm4, decreases HOT1-stimulated recombination but does not affect rDNA recombination or exchange in the absence of HOT1. Two new alleles of RAD52 were also isolated using this screen. With regard to HOT1 activity, rad52 is epistatic to all four hrm mutations indicating that the products of the HRM genes and of RAD52 mediate steps in the same recombination pathway. Finding mutations that decrease both the activity of HOT1 and exchange in the rDNA supports the hypothesis that HOT1 plays a role in rDNA recombination

Ligand-independent interaction of the type I interferon receptor complex is necessary to observe its biological activity.

Science.gov (United States)

Krause, Christopher D; Digioia, Gina; Izotova, Lara S; Xie, Junxia; Kim, Youngsun; Schwartz, Barbara J; Mirochnitchenko, Olga V; Pestka, Sidney

2013-10-01

Ectopic coexpression of the two chains of the Type I and Type III interferon (IFN) receptor complexes (IFN-αR1 and IFN-αR2c, or IFN-λR1 and IL-10R2) yielded sensitivity to IFN-alpha or IFN-lambda in only some cells. We found that IFN-αR1 and IFN-αR2c exhibit FRET only when expressed at equivalent and low levels. Expanded clonal cell lines expressing both IFN-αR1 and IFN-αR2c were sensitive to IFN-alpha only when IFN-αR1 and IFN-αR2c exhibited FRET in the absence of human IFN-alpha. Coexpression of RACK-1 or Jak1 enhanced the affinity of the interaction between IFN-αR1 and IFN-αR2c. Both IFN-αR1 and IFN-αR2c exhibited FRET with Jak1 and Tyk2. Together with data showing that disruption of the preassociation between the IFN-gamma receptor chains inhibited its biological activity, we propose that biologically active IFN receptors require ligand-independent juxtaposition of IFN receptor chains assisted by their associated cytosolic proteins. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mechanism of A2 adenosine receptor activation. I. Blockade of A2 adenosine receptors by photoaffinity labeling

International Nuclear Information System (INIS)

Lohse, M.J.; Klotz, K.N.; Schwabe, U.

1991-01-01

It has previously been shown that covalent incorporation of the photoreactive adenosine derivative (R)-2-azido-N6-p-hydroxy-phenylisopropyladenosine [(R)-AHPIA] into the A1 adenosine receptor of intact fat cells leads to a persistent activation of this receptor, resulting in a reduction of cellular cAMP levels. In contrast, covalent incorporation of (R)-AHPIA into human platelet membranes, which contain only stimulatory A2 adenosine receptors, reduces adenylate cyclase stimulation via these receptors. This effect of (R)-AHPIA is specific for the A2 receptor and can be prevented by the adenosine receptor antagonist theophylline. Binding studies indicate that up to 90% of A2 receptors can be blocked by photoincorporation of (R)-AHPIA. However, the remaining 10-20% of A2 receptors are sufficient to mediate an adenylate cyclase stimulation of up to 50% of the control value. Similarly, the activation via these 10-20% of receptors occurs with a half-life that is only 2 times longer than that in control membranes. This indicates the presence of a receptor reserve, with respect to both the extent and the rate of adenylate cyclase stimulation. These observations require a modification of the models of receptor-adenylate cyclase coupling

Computational modeling of the bHLH domain of the transcription factor TWIST1 and R118C, S144R and K145E mutants

Directory of Open Access Journals (Sweden)

Maia Amanda M

2012-07-01

Full Text Available Abstract Background Human TWIST1 is a highly conserved member of the regulatory basic helix-loop-helix (bHLH transcription factors. TWIST1 forms homo- or heterodimers with E-box proteins, such as E2A (isoforms E12 and E47, MYOD and HAND2. Haploinsufficiency germ-line mutations of the twist1 gene in humans are the main cause of Saethre-Chotzen syndrome (SCS, which is characterized by limb abnormalities and premature fusion of cranial sutures. Because of the importance of TWIST1 in the regulation of embryonic development and its relationship with SCS, along with the lack of an experimentally solved 3D structure, we performed comparative modeling for the TWIST1 bHLH region arranged into wild-type homodimers and heterodimers with E47. In addition, three mutations that promote DNA binding failure (R118C, S144R and K145E were studied on the TWIST1 monomer. We also explored the behavior of the mutant forms in aqueous solution using molecular dynamics (MD simulations, focusing on the structural changes of the wild-type versus mutant dimers. Results The solvent-accessible surface area of the homodimers was smaller on wild-type dimers, which indicates that the cleft between the monomers remained more open on the mutant homodimers. RMSD and RMSF analyses indicated that mutated dimers presented values that were higher than those for the wild-type dimers. For a more careful investigation, the monomer was subdivided into four regions: basic, helix I, loop and helix II. The basic domain presented a higher flexibility in all of the parameters that were analyzed, and the mutant dimer basic domains presented values that were higher than the wild-type dimers. The essential dynamic analysis also indicated a higher collective motion for the basic domain. Conclusions Our results suggest the mutations studied turned the dimers into more unstable structures with a wider cleft, which may be a reason for the loss of DNA binding capacity observed for in vitro

39 CFR 255.5 - Employment.

Science.gov (United States)

2010-07-01

... 39 Postal Service 1 2010-07-01 2010-07-01 false Employment. 255.5 Section 255.5 Postal Service... Employment. No qualified individual with a disability shall, on the basis of disability, be subjected to discrimination in employment with the Postal Service. The definitions, requirements, and procedures of section...

Development of tilted fibre Bragg gratings using highly coherent 255 ...

Indian Academy of Sciences (India)

R&D C-1 Block, Raja Ramanna Centre for Advanced Technology, Indore 452 013, India. ∗. Corresponding author. E-mail: oprakash@rrcat.gov.in. DOI: 10.1007/s12043-013-0672-7; ePublication: 6 February 2014. Abstract. This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 ...

Mutation of I696 and W697 in the TRP box of vanilloid receptor subtype I modulates allosteric channel activation.

Science.gov (United States)

Gregorio-Teruel, Lucia; Valente, Pierluigi; González-Ros, José Manuel; Fernández-Ballester, Gregorio; Ferrer-Montiel, Antonio

2014-03-01

The transient receptor potential vanilloid receptor subtype I (TRPV1) channel acts as a polymodal sensory receptor gated by chemical and physical stimuli. Like other TRP channels, TRPV1 contains in its C terminus a short, conserved domain called the TRP box, which is necessary for channel gating. Substitution of two TRP box residues-I696 and W697-with Ala markedly affects TRPV1's response to all activating stimuli, which indicates that these two residues play a crucial role in channel gating. We systematically replaced I696 and W697 with 18 native l-amino acids (excluding cysteine) and evaluated the effect on voltage- and capsaicin-dependent gating. Mutation of I696 decreased channel activation by either voltage or capsaicin; furthermore, gating was only observed with substitution of hydrophobic amino acids. Substitution of W697 with any of the 18 amino acids abolished gating in response to depolarization alone, shifting the threshold to unreachable voltages, but not capsaicin-mediated gating. Moreover, vanilloid-activated responses of W697X mutants showed voltage-dependent gating along with a strong voltage-independent component. Analysis of the data using an allosteric model of activation indicates that mutation of I696 and W697 primarily affects the allosteric coupling constants of the ligand and voltage sensors to the channel pore. Together, our findings substantiate the notion that inter- and/or intrasubunit interactions at the level of the TRP box are critical for efficient coupling of stimulus sensing and gate opening. Perturbation of these interactions markedly reduces the efficacy and potency of the activating stimuli. Furthermore, our results identify these interactions as potential sites for pharmacological intervention.

40 CFR 97.255 - Banking.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Banking. 97.255 Section 97.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX... Banking. (a) CAIR SO2 allowances may be banked for future use or transfer in a compliance account or a...

Functional characterization of the modified melanocortin peptides responsible for ligand selectivity at the human melanocortin receptors.

Science.gov (United States)

Chen, Min; Georgeson, Keith E; Harmon, Carroll M; Haskell-Luevano, Carrie; Yang, Yingkui

2006-11-01

The melanocortin system plays an important role in energy homeostasis as well as skin pigmentation, steroidogenesis and exocrine gland function. In this study, we examined eight Ac-His-Phe-Arg-Trp-NH(2) tetrapeptides that were modified at the Phe position and pharmacologically characterized their activities at the human MCR wild-types and their mutants. Our results indicate that at the hMC1R, all D stereochemical modified residues at the Phe position of peptides increase cAMP production in a dose-dependent manner. At the hMC3R, the DPhe peptide dose dependently increases cAMP production but all other three tetrapeptides were not. At the hMC4R, both the DPhe and DNal(1') peptides induce cAMP production. However, both DTyr and DNal(2') were not able to induce cAMP production. Further studies indicated that at the hMC1R M128L mutant receptor, the all D-configured tetrapeptides reduce their potencies as compared to that of hMC1R wild-type. However, at the hMC3R and hMC4R L165M and L133M mutant receptors, the DNal(2') and DTyr tetrapeptides possess agonist activity. These findings indicate that DPhe in tetrapeptide plays an important role in ligand selectivity and specific residue TM3 of the melanocortin receptors is crucial for ligand selectivity.

Theoretical Analysis of Allosteric and Operator Binding for Cyclic-AMP Receptor Protein Mutants

Science.gov (United States)

Einav, Tal; Duque, Julia; Phillips, Rob

2018-02-01

Allosteric transcription factors undergo binding events both at their inducer binding sites as well as at distinct DNA binding domains, and it is often difficult to disentangle the structural and functional consequences of these two classes of interactions. In this work, we compare the ability of two statistical mechanical models - the Monod-Wyman-Changeux (MWC) and the Koshland-N\\'emethy-Filmer (KNF) models of protein conformational change - to characterize the multi-step activation mechanism of the broadly acting cyclic-AMP receptor protein (CRP). We first consider the allosteric transition resulting from cyclic-AMP binding to CRP, then analyze how CRP binds to its operator, and finally investigate the ability of CRP to activate gene expression. In light of these models, we examine data from a beautiful recent experiment that created a single-chain version of the CRP homodimer, thereby enabling each subunit to be mutated separately. Using this construct, six mutants were created using all possible combinations of the wild type subunit, a D53H mutant subunit, and an S62F mutant subunit. We demonstrate that both the MWC and KNF models can explain the behavior of all six mutants using a small, self-consistent set of parameters. In comparing the results, we find that the MWC model slightly outperforms the KNF model in the quality of its fits, but more importantly the parameters inferred by the MWC model are more in line with structural knowledge of CRP. In addition, we discuss how the conceptual framework developed here for CRP enables us to not merely analyze data retrospectively, but has the predictive power to determine how combinations of mutations will interact, how double mutants will behave, and how each construct would regulate gene expression.

Pharmacological Characterisation of Nicotinic Acetylcholine Receptors Expressed in Human iPSC-Derived Neurons.

Directory of Open Access Journals (Sweden)

Anna Chatzidaki

Full Text Available Neurons derived from human induced pluripotent stem cells (iPSCs represent a potentially valuable tool for the characterisation of neuronal receptors and ion channels. Previous studies on iPSC-derived neuronal cells have reported the functional characterisation of a variety of receptors and ion channels, including glutamate receptors, γ-aminobutyric acid (GABA receptors and several voltage-gated ion channels. In the present study we have examined the expression and functional properties of nicotinic acetylcholine receptors (nAChRs in human iPSC-derived neurons. Gene expression analysis indicated the presence of transcripts encoding several nAChR subunits, with highest levels detected for α3-α7, β1, β2 and β4 subunits (encoded by CHRNA3-CHRNA7, CHRNB1, CHRNB2 and CHRNB4 genes. In addition, similarly high transcript levels were detected for the truncated dupα7 subunit transcript, encoded by the partially duplicated gene CHRFAM7A, which has been associated with psychiatric disorders such as schizophrenia. The functional properties of these nAChRs have been examined by calcium fluorescence and by patch-clamp recordings. The data obtained suggest that the majority of functional nAChRs expressed in these cells have pharmacological properties typical of α7 receptors. Large responses were induced by a selective α7 agonist (compound B, in the presence of the α7-selective positive allosteric modulator (PAM PNU-120596, which were blocked by the α7-selective antagonist methyllycaconitine (MLA. In addition, a small proportion of the neurons express nAChRs with properties typical of heteromeric (non-α7 containing nAChR subtypes. These cells therefore represent a great tool to advance our understanding of the properties of native human nAChRs, α7 in particular.

Pharmacological properties of homomeric and heteromeric GluR1o and GluR3o receptors

DEFF Research Database (Denmark)

Nielsen, B S; Banke, T G; Schousboe, A

1998-01-01

Homomeric and heteromeric alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunits GluR1o and GluR3o were expressed in Spodoptera frugiperda (Sf9) insect cells. Membranes containing the recombinant receptors showed a doublet of bands of the expected size (99-109 kDa) after...

Mutant Runx2 regulates amelogenesis and osteogenesis through a miR-185-5p-Dlx2 axis.

Science.gov (United States)

Chang, Huaiguang; Wang, Yue; Liu, Haochen; Nan, Xu; Wong, Singwai; Peng, Saihui; Gu, Yajuan; Zhao, Hongshan; Feng, Hailan

2017-12-14

Regulation of microRNAs (miRNA) has been extensively investigated in diseases; however, little is known about the roles of miRNAs in cleidocranial dysplasia (CCD). The aim of the present study was to investigate the potential involvement of miRNAs in CCD. In vitro site-directed mutagenesis was performed to construct three mutant Runx2 expression vectors, which were then transfected into LS8 cells and MC3T3-E1 cells, to determine the impact on amelogenesis and osteogenesis, respectively. miRCURY LNA miRNA microarray identify miR-185-5p as a miRNA target commonly induced by all three Runx2 mutants. Real-time quantitative PCR was applied to determine the expression of miR-185-5p and Dlx2 in samples. Dual-luciferase reporter assays were conducted to confirm Dlx2 as a legitimate target of miR-185-5p. The suppressive effect of miR-185-5p on amelogenesis and osteogenesis of miR-185-5p was evaluated by RT-PCR and western blot examination of Amelx, Enam, Klk4, and Mmp20 gene and protein expression, and by Alizarin Red stain. We found that mutant Runx2 suppressed amelogenesis and osteogenesis. miR-185-5p, induced by Runx2, suppressed amelogenesis and osteogenesis. Furthermore, we identified Dlx2 as direct target of miR-185-5p. Consistently, Dlx2 expression was inversely correlated with miR-185-5p levels. This study highlights the molecular etiology and significance of miR-185-5p in CCD, and suggests that targeting miR-185-5p may represent a new therapeutic strategy in prevention or intervention of CCD.

Clinical significance of AGE-RAGE axis in colorectal cancer: associations with glyoxalase-I, adiponectin receptor expression and prognosis

International Nuclear Information System (INIS)

Sakellariou, Stratigoula; Fragkou, Paraskevi; Levidou, Georgia; Gargalionis, Antonios N.; Piperi, Christina; Dalagiorgou, Georgia; Adamopoulos, Christos; Saetta, Angelica; Agrogiannis, George; Theohari, Irini; Sougioultzis, Stavros; Tsioli, Panagiota; Karavokyros, Ioannis; Tsavaris, Nikolaos; Kostakis, Ioannis D.; Zizi-Serbetzoglou, Adamantia; Vandoros, Gerasimos P.; Patsouris, Efstratios; Korkolopoulou, Penelope

2016-01-01

Advanced glycation end products (AGEs) and their receptor RAGE emerge as important pathogenic contributors in colorectal carcinogenesis. However, their relationship to the detoxification enzyme Glyoxalase (GLO)-I and Adiponectin receptors (AdipoR1, AdipoR2) in colorectal carcinoma (CRC) is currently understudied. In the present study, we investigated the expression levels of the above molecules in CRC compared to adjacent non-tumoral tissue and their potential correlation with clinicopathological characteristics and patients’ survival. We analyzed the immunohistochemical expression of AGE, RAGE, GLO-1, AdipoR1 and AdipoR2 in 133 primary CRC cases, focusing on GLO-I. The tumour MSI status was further assessed in mucinous carcinomas. Western immunoblotting was employed for validation of immunohistochemical data in normal and tumoral tissues as well in three CRC cell lines. An independent set of 55 patients was also used to validate the results of univariate survival analysis regarding GLO-I. CRC tissue showed higher intensity of both AGE and RAGE expression compared with normal colonic mucosa which was negative for GLO-I in most cases (78 %). Western immunoblotting confirmed AGE, RAGE and GLO-I overexpression in tumoral tissue. GLO-I expression was directly related to RAGE and inversely related to AGE immunolabeling. There was a trend towards higher expression of all markers (except for RAGE) in the subgroup of mucinous carcinomas which, although of borderline significance, seemed to be more prominent for AdipoR1 and AGE. Additionally, AGE, AdipoR1 and Adipo R2 expression was related to tumor grade, whereas GLO-1 and AdipoR1 to T-category. In survival analysis, AdipoR2 and GLO-I overexpression predicted shortened survival in the entire cohort and in early stage cases, an effect which for GLO-I was reproduced in the validation cohort. Moreover, GLO-I emerged as an independent prognosticator of adverse significance in the patients’ cohort. We herein provide novel

14 CFR 255.4 - Display of information.

Science.gov (United States)

2010-01-01

... REGULATIONS AIRLINE COMPUTER RESERVATIONS SYSTEMS § 255.4 Display of information. (a) All systems shall provide at least one integrated display that includes the schedules, fares, rules, and availability of all... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Display of information. 255.4 Section 255.4...

21 CFR 25.5 - Terminology.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Terminology. 25.5 Section 25.5 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ENVIRONMENTAL IMPACT...). (12) Legislation (40 CFR 1508.17). (13) Major Federal action (40 CFR 1508.18). (14) Mitigation (40 CFR...

Group I mGlu receptors potentiate synaptosomal [{sup 3}H]glutamate release independently of exogenously applied arachidonic acid

Energy Technology Data Exchange (ETDEWEB)

Reid, M.E.; Toms, N.J.; Bedingfield, J.S.; Roberts, P.J. [Department of Pharmacology, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD (United Kingdom)

1999-04-01

In the current study, we have characterized group I metabotropic glutamate (mGlu) receptor enhancement of 4-aminopyridine (4AP)-evoked [{sup 3}H]glutamate release from rat cerebrocortical synaptosomes. The broad spectrum mGlu receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD, 10 {mu}M) increased 4AP-evoked [{sup 3}H]glutamate release (143.32{+-}2.73% control) only in the presence of exogenously applied arachidonic acid; an effect reversed by the inclusion of bovine serum albumin (BSA, fatty acid free). In contrast, the selective group I mGlu receptor agonist (S)-3,5-dihydroxyphenylglycine (DHPG) potentiated (EC{sub 50}=1.60{+-}0.25 {mu}M; E{sub max}=147.61{+-}10.96% control) 4AP-evoked [{sup 3}H]glutamate release, in the absence of arachidonic acid. This potentiation could be abolished by either the selective mGlu{sub 1} receptor antagonist (R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA, 1 mM) or the selective PKC inhibitor (Ro 31-8220, 10 {mu}M) and was BSA-insensitive. The selective mGlu{sub 5} receptor agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG, 300{mu}M) was without effect. DHPG (100 {mu}M) also potentiated both 30 mM and 50 mM K{sup +}-evoked [{sup 3}H]glutamate release (121.60{+-}12.77% and 121.50{+-}4.45% control, respectively). DHPG (100 {mu}M) failed to influence both 4AP-stimulated {sup 45}Ca{sup 2+} influx and 50 mM K{sup +}-induced changes in synaptosomal membrane potential. Possible group I mGlu receptor suppression of tonic adenosine A{sub 1} receptor, group II/III mGlu receptors or GABA{sub B} receptor activity is unlikely since 4AP-evoked [{sup 3}H]glutamate release was insensitive to the selective inhibitory receptor antagonists 8-cyclopentyl-1,3-dimethylxanthine, (R,S)-{alpha}-cyclopropyl-4-phosphonophenylglycine or CGP55845A, respectively. These data suggest an 'mGlu{sub 1} receptor-like' receptor potentiates [{sup 3}H]glutamate release from cerebrocortical synaptosomes in the absence of

Excision-repair in mutants of Escherichia coli deficient in DNA polymerase I and/or its associated 5'. -->. 3' exonuclease

Energy Technology Data Exchange (ETDEWEB)

Cooper, P [Stanford Univ., Calif. (USA). Dept. of Biological Sciences

1977-01-01

The UV sensitivity of E.coli mutants deficient in the 5'..-->..3' exonuclease activity of DNA polymerase I is intermediate between that of pol/sup +/ strains and mutants which are deficient in the polymerizing activity of pol I (polA1). Like polA1 mutants, the 5'-econuclease deficient mutants exhibit increased UV-induced DNA degradation and increased repair synthesis compared to a pol/sup +/ strain, although the increase is not as great as in polA1 or in the conditionally lethal mutant BT4113ts deficient in both polymerase I activities. When dimer excision was measured at UV doses low enough to avoid interference from extensive DNA degradation, all three classes of polymerase I deficient mutants were found to remove dimers efficiently from their DNA. We conclude that enzymes alternative to polymerase I can operate in both the excision and resynthesis steps of excision repair and that substitution for either of the polymerase I functions results in longer patches of repair. A model is proposed detailing the possible events in the alternative pathways.

Identification of tetrapeptides from a mixture based positional scanning library that can restore nM full agonist function of the L106P, I69T, I102S, A219V, C271Y, and C271R human melanocortin-4 polymorphic receptors (hMC4Rs).

Science.gov (United States)

Haslach, Erica M; Huang, Huisuo; Dirain, Marvin; Debevec, Ginamarie; Geer, Phaedra; Santos, Radleigh G; Giulianotti, Marc A; Pinilla, Clemencia; Appel, Jon R; Doering, Skye R; Walters, Michael A; Houghten, Richard A; Haskell-Luevano, Carrie

2014-06-12

Human obesity has been linked to genetic factors and single nucleotide polymorphisms (SNPs). Melanocortin-4 receptor (MC4R) SNPs have been associated with up to 6% frequency in morbidly obese children and adults. A potential therapy for individuals possessing such genetic modifications is the identification of molecules that can restore proper receptor signaling and function. These compounds could serve as personalized medications improving quality of life issues as well as alleviating diseases symptoms associated with obesity including type 2 diabetes. Several hMC4 SNP receptors have been pharmacologically characterized in vitro to have a decreased, or a lack of response, to endogenous agonists such as α-, β-, and γ2-melanocyte stimulating hormones (MSH) and adrenocorticotropin hormone (ACTH). Herein we report the use of a mixture based positional scanning combinatorial tetrapeptide library to discover molecules with nM full agonist potency and efficacy to the L106P, I69T, I102S, A219V, C271Y, and C271R hMC4Rs. The most potent compounds at all these hMC4R SNPs include Ac-His-(pI)DPhe-Tic-(pNO2)DPhe-NH2, Ac-His-(pCl)DPhe-Tic-(pNO2)DPhe-NH2, Ac-His-(pCl)DPhe-Arg-(pI)Phe-NH2, and Ac-Arg-(pCl)DPhe-Tic-(pNO2)DPhe-NH2, revealing new ligand pharmacophore models for melanocortin receptor drug design strategies.

Wnt signaling pathway involvement in genotypic and phenotypic variations in Waardenburg syndrome type 2 with MITF mutations.

Science.gov (United States)

Wang, Xue-Ping; Liu, Ya-Lan; Mei, Ling-Yun; He, Chu-Feng; Niu, Zhi-Jie; Sun, Jie; Zhao, Yu-Lin; Feng, Yong; Zhang, Hua

2018-05-01

Mutation in the gene encoding microphthalmia-associated transcription factor (MITF) lead to Waardenburg syndrome 2 (WS2), an autosomal dominantly inherited syndrome with auditory-pigmentary abnormalities, which is clinically and genetically heterogeneous. Haploinsufficiency may be the underlying mechanism for WS2. However, the mechanisms explaining the genotypic and phenotypic variations in WS2 caused by MITF mutations are unclear. A previous study revealed that MITF interacts with LEF-1, an important factor in the Wnt signaling pathway, to regulate its own transcription through LEF-1-binding sites on the MITF promoter. In this study, four different WS2-associated MITF mutations (p.R217I, p.R217G, p.R255X, p.R217del) that are associated with highly variable clinical features were chosen. According to the results, LEF-1 can activate the expression of MITF on its own, but MITF proteins inhibited the activation. This inhibition weakens when the dosage of MITF is reduced. Except for p.R217I, p.R255X, p.R217G, and p.R217del lose the ability to activate TYR completely and do not inhibit the LEF-1-mediated activation of the MITF-M promoter, and the haploinsufficiency created by mutant MITF can be overcome; correspondingly, the mutants' associated phenotypes are less severe than that of p.R217I. The dominant negative of p.R217del made it have a second-most severe phenotype. This study's data imply that MITF has a negative feedback loop of regulation to stabilize MITF gene dosage that involves the Wnt signaling pathway and that the interaction of MITF mutants with this pathway drives the genotypic and phenotypic differences observed in Waardenburg syndrome type 2 associated with MITF mutations.

A highly conserved glycine within linker I and the extreme C terminus of G protein alpha subunits interact cooperatively in switching G protein-coupled receptor-to-effector specificity

DEFF Research Database (Denmark)

Kostenis, Evi; Martini, Lene; Ellis, James

2004-01-01

Numerous studies have attested to the importance of the extreme C terminus of G protein alpha subunits in determining their selectivity of receptor recognition. We have previously reported that a highly conserved glycine residue within linker I is important for constraining the fidelity of receptor...... recognition by Galpha(q) proteins. Herein, we explored whether both modules (linker I and extreme C terminus) interact cooperatively in switching G protein-coupled receptor (GPCR)-to-effector specificity and created as models mutant Galpha(q) proteins in which glycine was replaced with various amino acids...... and the C-terminal five Galpha(q) residues with the corresponding Galpha(i) or Galpha(s) sequence. Coupling properties of the mutated Galpha(q) proteins were determined after coexpression with a panel of 13 G(i)-and G(s) -selective receptors and compared with those of Galpha proteins modified in only one...

Familial defective apolipoprotein B-100: low density lipoproteins with abnormal receptor binding

International Nuclear Information System (INIS)

Innerarity, T.L.; Weisgraber, K.H.; Arnold, K.S.; Mahley, R.W.; Krauss, R.M.; Vega, G.L.; Grundy, S.M.

1987-01-01

Previous in vivo turnover studies suggested that retarded clearance of low density lipoproteins (LDL) from the plasma of some hypercholesterolemic patients is due to LDL with defective receptor binding. The present study examined this postulate directly by receptor binding experiments. The LDL from a hypercholesterolemic patient (G.R.) displayed a reduced ability to bind to the LDL receptors on normal human fibroblasts. The G.R. LDL possessed 32% of normal receptor binding activity. Likewise, the G.R. LDL were much less effective than normal LDL in competing with 125 I-labeled normal LDL for cellular uptake and degradation and in stimulating intracellular cholesteryl ester synthesis. The defect in LDL binding appears to be due to a genetic abnormality of apolipoprotein B-100: two brothers of the proband possess LDL defective in receptor binding, whereas a third brother and the proband's son have normally binding LDL. Further, the defect in receptor binding does not appear to be associated wit an abnormal lipid composition or structure of the LDL. Normal and abnormal LDL subpopulations were partially separated from plasma of two subjects by density-gradient ultracentrifugation, a finding consistent with the presence of a normal and a mutant allele. The affected family members appear to be heterozygous for this disorder, which has been designated familial defective apolipoprotein B-100. These studies indicate that the defective receptor binding results in inefficient clearance of LDL and the hypercholesterolemia observed in these patients

Isolation of New Gravitropic Mutants under Hypergravity Conditions

OpenAIRE

Mori, Akiko; Toyota, Masatsugu; Shimada, Masayoshi; Mekata, Mika; Kurata, Tetsuya; Tasaka, Masao; Morita, Miyo T.

2016-01-01

Forward genetics is a powerful approach used to link genotypes and phenotypes, and mutant screening/analysis has provided deep insights into many aspects of plant physiology. Gravitropism is a tropistic response in plants, in which hypocotyls and stems sense the direction of gravity and grow upward. Previous studies of gravitropic mutants have suggested that shoot endodermal cells in Arabidopsis stems and hypocotyls are capable of sensing gravity (i.e., statocytes). In the present study, we r...

Enhanced thyroid hormone breakdown in hepatocytes by mutual induction of the constitutive androstane receptor (CAR, NR1I3) and arylhydrocarbon receptor by benzo[a]pyrene and phenobarbital

International Nuclear Information System (INIS)

Schraplau, Anne; Schewe, Bettina; Neuschäfer-Rube, Frank; Ringel, Sebastian; Neuber, Corinna; Kleuser, Burkhard; Püschel, Gerhard P.

2015-01-01

Xenobiotics may interfere with the hypothalamic-pituitary-thyroid endocrine axis by inducing enzymes that inactivate thyroid hormones and thereby reduce the metabolic rate. This induction results from an activation of xeno-sensing nuclear receptors. The current study shows that benzo[a]pyrene, a frequent contaminant of processed food and activator of the arylhydrocarbon receptor (AhR) activated the promoter and induced the transcription of the nuclear receptor constitutive androstane receptor (CAR, NR1I3) in rat hepatocytes. Likewise, phenobarbital induced the AhR transcription. This mutual induction of the nuclear receptors enhanced the phenobarbital-dependent induction of the prototypic CAR target gene Cyp2b1 as well as the AhR-dependent induction of UDP-glucuronosyltransferases. In both cases, the induction by the combination of both xenobiotics was more than the sum of the induction by either substance alone. By inducing the AhR, phenobarbital enhanced the benzo[a]pyrene-dependent reduction of thyroid hormone half-life and the benzo[a]pyrene-dependent increase in the rate of thyroid hormone glucuronide formation in hepatocyte cultures. CAR ligands might thus augment the endocrine disrupting potential of AhR activators by an induction of the AhR

17-AAG increases autophagic removal of mutant androgen receptor in spinal and bulbar muscular atrophy.

Science.gov (United States)

Rusmini, Paola; Simonini, Francesca; Crippa, Valeria; Bolzoni, Elena; Onesto, Elisa; Cagnin, Monica; Sau, Daniela; Ferri, Nicola; Poletti, Angelo

2011-01-01

Several types of motorneuron diseases are linked to neurotoxic mutant proteins. These acquire aberrant conformations (misfolding) that trigger deleterious downstream events responsible for neuronal dysfunction and degeneration. The pharmacological removal of misfolded proteins might thus be useful in these diseases. We utilized a peculiar motorneuronal disease model, spinobulbar muscular atrophy (SBMA), in which the neurotoxicity of the protein involved, the mutant androgen receptor (ARpolyQ), can be modulated by its ligand testosterone (T). 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) has already been proven to exert beneficial action in SBMA. Here we demonstrated that 17-AAG exerts its pro-degradative activity on mutant ARpolyQ without impacting on proteasome functions. 17-AAG removes ARpolyQ misfolded species and aggregates by activating the autophagic system. We next analyzed the 17-AAG effects on two proteins (SOD1 and TDP-43) involved in related motorneuronal diseases, such as amyotrophic lateral sclerosis (ALS). In these models 17-AAG was unable to counteract protein aggregation. Copyright © 2010 Elsevier Inc. All rights reserved.

An allosteric binding site at the human serotonin transporter mediates the inhibition of escitalopram by R-citalopram: kinetic binding studies with the ALI/VFL-SI/TT mutant.

Science.gov (United States)

Zhong, Huailing; Hansen, Kasper B; Boyle, Noel J; Han, Kiho; Muske, Galina; Huang, Xinyan; Egebjerg, Jan; Sánchez, Connie

2009-10-25

The human serotonin transporter (hSERT) has primary and allosteric binding sites for escitalopram and R-citalopram. Previous studies have established that the interaction of these two compounds at a low affinity allosteric binding site of hSERT can affect the dissociation of [(3)H]escitalopram from hSERT. The allosteric binding site involves a series of residues in the 10th, 11th, and 12th trans-membrane domains of hSERT. The low affinity allosteric activities of escitalopram and R-citalopram are essentially eliminated in a mutant hSERT with changes in some of these residues, namely A505V, L506F, I507L, S574T, I575T, as measured in dissociation binding studies. We confirm that in association binding experiments, R-citalopram at clinically relevant concentrations reduces the association rate of [(3)H]escitalopram as a ligand to wild type hSERT. We demonstrate that the ability of R-citalopram to reduce the association rate of escitalopram is also abolished in the mutant hSERT (A505V, L506F, I507L, S574T, I575T), along with the expected disruption the low affinity allosteric function on dissociation binding. This suggests that the allosteric binding site mediates both the low affinity and higher affinity interactions between R-citalopram, escitalopram, and hSERT. Our data add an additional structural basis for the different efficacies of escitalopram compared to racemic citalopram reported in animal studies and clinical trials, and substantiate the hypothesis that hSERT has complex allosteric mechanisms underlying the unexplained in vivo activities of its inhibitors.

Effects of Asn318 and Asp87Asn318 mutations on signal transduction by the gonadotropin-releasing hormone receptor and receptor regulation.

Science.gov (United States)

Awara, W M; Guo, C H; Conn, P M

1996-02-01

GnRH receptor (GnRH-R) contains Asn87 and Asp318 instead of the more frequently observed Asp87 and Asn318 found in other G protein-coupled receptors. In the present study, site-directed mutagenesis was used to introduce Asn318 and Asp87Asn318 into GnRH-R. The effect on coupling and regulation of GnRH-R was studied by stable expression of wild and mutant mouse GnRH-R in the lactotropic GH3 cells; these normally release PRL in response to TRH stimulation. The responses to Buserelin (a metabolically stable GnRH analog) in three different cell lines, M1, N8, and ND1 (expressing wild-type, Asn318 mutant, and Asp87Asn318 mutant mouse GnRH-R, respectively) were compared with that observed in the previously characterized GGH3-1' cells, which stably express rat GnRH-R. The Asn318 and Asp87Asn318 mutations had no measurable effect on ligand binding, but abolished the initial down-regulation of receptor that was observed in M1 and GGH3-1' cells, suggesting that the normal location of Asn87 and Asp318 in GnRH-R is involved in the regulation of GnRH-R. In N8 and ND1 cells, Buserelin-stimulated inositol phosphate (IP) production was attenuated, but the release of both cAMP and PRL was stimulated in a dose- and time-dependent manner. These mutations apparently impaired the coupling between GnRH-R and G proteins involved in IP production, but not those involved in cAMP release. In M1 cells, Buserelin stimulation produced a significant increase in IP production, but neither cAMP nor PRL release was significantly stimulated. These findings are consistent with the previous suggestion that GnRH-stimulated PRL release is mediated by a cAMP second messenger system in transfected GGH3 cells.

Transcriptional switching by the MerR protein: Activation and repression mutants implicate distinct DNA and mercury(II) binding domains

International Nuclear Information System (INIS)

Shewchuk, L.M.; Helmann, J.D.; Ross, W.; Park, S.J.; Summers, A.O.; Walsh, C.T.

1989-01-01

Bacterial resistance to mercuric compounds is controlled by the MerR metalloregulatory protein. The MerR protein functions as both a transcriptional repressor and a mercuric ion dependent transcriptional activator. Chemical mutagenesis of the cloned merR structural gene has led to the identification of mutant proteins that are specifically deficient in transcriptional repression, activation, or both. Five mutant proteins have been overproduced, purified to homogeneity, and assayed for ability to dimerize, bind mer operator DNA, and bind mercuric ion. A mutation in the recognition helix of a proposed helix-turn-helix DNA binding motif (E22K) yields protein deficient in both activation and repression in vivo (a - r - ) and deficient in operator binding in vitro. In contrast, mutations in three of the four MerR cysteine residues are repression competent but activation deficient (a - r + ) in vivo. In vitro, the purified cysteine mutant proteins bind to the mer operator site with near wild-type affinity but are variable deficient in binding the in vivo inducer mercury(II) ion. A subset of the isolated proteins also appears compromised in their ability to form dimers at low protein concentrations. These data support a model in which DNA-bound MerR dimer binds one mercuric ion and transmits this occupancy information to a protein region involved in transcriptional activation

Regiospecificity determinants of human heme oxygenase: differential NADPH- and ascorbate-dependent heme cleavage by the R183E mutant.

Science.gov (United States)

Wang, Jinling; Lad, Latesh; Poulos, Thomas L; Ortiz de Montellano, Paul R

2005-01-28

The ability of the human heme oxygenase-1 (hHO-1) R183E mutant to oxidize heme in reactions supported by either NADPH-cytochrome P450 reductase or ascorbic acid has been compared. The NADPH-dependent reaction, like that of wild-type hHO-1, yields exclusively biliverdin IXalpha. In contrast, the R183E mutant with ascorbic acid as the reductant produces biliverdin IXalpha (79 +/- 4%), IXdelta (19 +/- 3%), and a trace of IXbeta. In the presence of superoxide dismutase and catalase, the yield of biliverdin IXdelta is decreased to 8 +/- 1% with a corresponding increase in biliverdin IXalpha. Spectroscopic analysis of the NADPH-dependent reaction shows that the R183E ferric biliverdin complex accumulates, because reduction of the iron, which is required for sequential iron and biliverdin release, is impaired. Reversal of the charge at position 183 makes reduction of the iron more difficult. The crystal structure of the R183E mutant, determined in the ferric and ferrous-NO bound forms, shows that the heme primarily adopts the same orientation as in wild-type hHO-1. The structure of the Fe(II).NO complex suggests that an altered active site hydrogen bonding network supports catalysis in the R183E mutant. Furthermore, Arg-183 contributes to the regiospecificity of the wild-type enzyme, but its contribution is not critical. The results indicate that the ascorbate-dependent reaction is subject to a lower degree of regiochemical control than the NADPH-dependent reaction. Ascorbate may be able to reduce the R183E ferric and ferrous dioxygen complexes in active site conformations that cannot be reduced by NADPH-cytochrome P450 reductase.

Untangling dopamine-adenosine receptor-receptor assembly in experimental parkinsonism in rats

Directory of Open Access Journals (Sweden)

Víctor Fernández-Dueñas

2015-01-01

Full Text Available Parkinson’s disease (PD is a dopaminergic-related pathology in which functioning of the basal ganglia is altered. It has been postulated that a direct receptor-receptor interaction – i.e. of dopamine D2 receptor (D2R with adenosine A2A receptor (A2AR (forming D2R-A2AR oligomers – finely regulates this brain area. Accordingly, elucidating whether the pathology prompts changes to these complexes could provide valuable information for the design of new PD therapies. Here, we first resolved a long-standing question concerning whether D2R-A2AR assembly occurs in native tissue: by means of different complementary experimental approaches (i.e. immunoelectron microscopy, proximity ligation assay and TR-FRET, we unambiguously identified native D2R-A2AR oligomers in rat striatum. Subsequently, we determined that, under pathological conditions (i.e. in a rat PD model, D2R-A2AR interaction was impaired. Collectively, these results provide definitive evidence for alteration of native D2R-A2AR oligomers in experimental parkinsonism, thus conferring the rationale for appropriate oligomer-based PD treatments.

Dwarf mutant of Papaver somniferum with high morphine content

International Nuclear Information System (INIS)

Chauhan, S.P.; Patra, N.K.; Srivastava, H.K.

1987-01-01

Opium poppy, Papaver somniferum L. is an important medicinal plant known for its morphine, codeine, and thebaine alkaloids. This Institute had earlier released two latex opium yielding poppy varieties, Shyama and Shweta, which are now cultivated by the farmers under the supervision of the Narcotic Department of the Government of India. However, both these varieties became susceptible to downy mildew (Peronospora arborescens). Lodging due to heavy capsule weight is another problem affecting latex yield. With these problems in mind, we undertook mutation breeding on the above mentioned two varieties employing gamma rays (5 kR, 15 kR, 20 kR) and EMS (0.2%, 0.4%, 0.6%) and combined mutagens (5 kR + 0.2% EMS, 5 kR + 0.4% EMS and 5 kR + 0.6% EMS). M 1 from the treated seeds (405 plants) was raised in winter 1984-85. M 2 generation of 13,500 plants (i.e. 270 M 1 progenies x 50 plants) was raised in winter 1985/86. A dwarf mutant with high morphine content was identified in M 2 from the variety Shweta treated with 5 kR + 0.4% EMS. The mutant differs by its dwarf stature, compact leaf arrangements, multilocular capsules, increased capsule number, and small capsule size. The mutant is under testing for its superior morphine production. It may be used as dwarf gene source in hybridization for improving lodging resistance. This mutant is a novel type, which was not available in our germplasm collection

Fission of 255,256Es, 255-257Fm, and 258Md at moderate excitation energies

NARCIS (Netherlands)

Britt, H.C.; Hoffman, D.C.; Plicht, J. van der; Wilhelmy, J.; Cheifetz, E.; Dupzyk, R.J.; Lougheed, R.W.

1984-01-01

The fission of 255,256Es, 255-257Fm, and 258Md has been studied in the excitation energy range from threshold to 25 MeV. A target of 254Es was used in the direct reaction studies; (d,pf), (t,pf), (3He,df), (3He,pf), and in the compound induced fission reactions formed with p, d, t, and α particle

Follicle-stimulating hormone (FSH) activates extracellular signal-regulated kinase phosphorylation independently of beta-arrestin- and dynamin-mediated FSH receptor internalization

Science.gov (United States)

Piketty, Vincent; Kara, Elodie; Guillou, Florian; Reiter, Eric; Crepieux, Pascale

2006-01-01

Background The follicle-stimulating hormone receptor (FSH-R) is a seven transmembrane spanning receptor (7TMR) which plays a crucial role in male and female reproduction. Upon FSH stimulation, the FSH-R activates the extracellular signal-regulated kinases (ERK). However, the mechanisms whereby the agonist-stimulated FSH-R activates ERK are poorly understood. In order to activate ERK, some 7 TMRs require beta-arrestin-and dynamin-dependent internalization to occur, whereas some others do not. In the present study, we examined the ability of the FSH-activated FSH-R to induce ERK phosphorylation, in conditions where its beta-arrestin- and dynamin-mediated internalization was impaired. Methods Human embryonic kidney (HEK) 293 cells were transiently transfected with the rat FSH-R. Internalization of the FSH-R was manipulated by co-expression of either a beta-arrestin (319–418) dominant negative peptide, either an inactive dynamin K44A mutant or of wild-type beta-arrestin 1 or 2. The outcomes on the FSH-R internalization were assayed by measuring 125I-FSH binding at the cell surface when compared to internalized 125I-FSH binding. The resulting ERK phosphorylation level was visualized by Western blot analysis. Results In HEK 293 cells, FSH stimulated ERK phosphorylation in a dose-dependent manner. Co-transfection of the beta- arrestin (319–418) construct, or of the dynamin K44A mutant reduced FSH-R internalization in response to FSH, without affecting ERK phosphorylation. Likewise, overexpression of wild-type beta-arrestin 1 or 2 significantly increased the FSH-R internalization level in response to FSH, without altering FSH-induced ERK phosphorylation. Conclusion From these results, we conclude that the FSH-R does not require beta-arrestin- nor dynamin-mediated internalization to initiate ERK phosphorylation in response to FSH. PMID:16787538

Functional importance of the Ala(116)-Pro(136) region in the calcium-sensing receptor. Constitutive activity and inverse agonism in a family C G-protein-coupled receptor

DEFF Research Database (Denmark)

Jensen, Anders A.; Spalding, T A; Burstein, E S

2000-01-01

The calcium-sensing receptor (CaR) belongs to family C of the G-protein-coupled receptor superfamily. To date 14 activating mutations in CaR showing increased sensitivity to Ca(2+) have been identified in humans with autosomal dominant hypocalcemia. Four of these activating mutations are found......, suppressed the elevated basal response of the constitutively activated Ca/1a mutants demonstrating inverse agonist activity of CPCCOEt. Taken together, our results demonstrate that the Ala(116)-Pro(136) region is of key importance for the maintenance of the inactive conformation of CaR....

The Fifth Transmembrane Domain of Angiotensin II Type 1 Receptor Participates in the Formation of the Ligand-binding Pocket and Undergoes a Counterclockwise Rotation upon Receptor Activation*

Science.gov (United States)

Domazet, Ivana; Martin, Stéphane S.; Holleran, Brian J.; Morin, Marie-Ève; Lacasse, Patrick; Lavigne, Pierre; Escher, Emanuel; Leduc, Richard; Guillemette, Gaétan

2009-01-01

The octapeptide hormone angiotensin II exerts a wide variety of cardiovascular effects through the activation of the angiotensin II Type 1 (AT1) receptor, which belongs to the G protein-coupled receptor superfamily. Like other G protein- coupled receptors, the AT1 receptor possesses seven transmembrane domains that provide structural support for the formation of the ligand-binding pocket. The role of the fifth transmembrane domain (TMD5) was investigated using the substituted cysteine accessibility method. All of the residues within Thr-190 to Leu-217 region were mutated one at a time to cysteine, and after expression in COS-7 cells, the mutant receptors were treated with the sulfhydryl-specific alkylating agent methanethiosulfonate-ethylammonium (MTSEA). MTSEA reacts selectively with water-accessible, free sulfhydryl groups of endogenous or introduced point mutation cysteines. If a cysteine is found in the binding pocket, the covalent modification will affect the binding kinetics of the ligand. MTSEA substantially decreased the binding affinity of L197C-AT1, N200C-AT1, I201C-AT1, G203C-AT1, and F204C-AT1 mutant receptors, which suggests that these residues orient themselves within the water-accessible binding pocket of the AT1 receptor. Interestingly, this pattern of acquired MTSEA sensitivity was altered for TMD5 reporter cysteines engineered in a constitutively active N111G-AT1 receptor background. Indeed, mutant I201C-N111G-AT1 became more sensitive to MTSEA, whereas mutant G203C-N111G-AT1 lost some sensitivity. Our results suggest that constitutive activation of AT1 receptor causes an apparent counterclockwise rotation of TMD5 as viewed from the extracellular side. PMID:19773549

The fifth transmembrane domain of angiotensin II Type 1 receptor participates in the formation of the ligand-binding pocket and undergoes a counterclockwise rotation upon receptor activation.

Science.gov (United States)

Domazet, Ivana; Martin, Stéphane S; Holleran, Brian J; Morin, Marie-Eve; Lacasse, Patrick; Lavigne, Pierre; Escher, Emanuel; Leduc, Richard; Guillemette, Gaétan

2009-11-13

The octapeptide hormone angiotensin II exerts a wide variety of cardiovascular effects through the activation of the angiotensin II Type 1 (AT(1)) receptor, which belongs to the G protein-coupled receptor superfamily. Like other G protein- coupled receptors, the AT(1) receptor possesses seven transmembrane domains that provide structural support for the formation of the ligand-binding pocket. The role of the fifth transmembrane domain (TMD5) was investigated using the substituted cysteine accessibility method. All of the residues within Thr-190 to Leu-217 region were mutated one at a time to cysteine, and after expression in COS-7 cells, the mutant receptors were treated with the sulfhydryl-specific alkylating agent methanethiosulfonate-ethylammonium (MTSEA). MTSEA reacts selectively with water-accessible, free sulfhydryl groups of endogenous or introduced point mutation cysteines. If a cysteine is found in the binding pocket, the covalent modification will affect the binding kinetics of the ligand. MTSEA substantially decreased the binding affinity of L197C-AT(1), N200C-AT(1), I201C-AT(1), G203C-AT(1), and F204C-AT(1) mutant receptors, which suggests that these residues orient themselves within the water-accessible binding pocket of the AT(1) receptor. Interestingly, this pattern of acquired MTSEA sensitivity was altered for TMD5 reporter cysteines engineered in a constitutively active N111G-AT(1) receptor background. Indeed, mutant I201C-N111G-AT(1) became more sensitive to MTSEA, whereas mutant G203C-N111G-AT(1) lost some sensitivity. Our results suggest that constitutive activation of AT(1) receptor causes an apparent counterclockwise rotation of TMD5 as viewed from the extracellular side.

Enhanced thyroid hormone breakdown in hepatocytes by mutual induction of the constitutive androstane receptor (CAR, NR1I3) and arylhydrocarbon receptor by benzo[a]pyrene and phenobarbital.

Science.gov (United States)

Schraplau, Anne; Schewe, Bettina; Neuschäfer-Rube, Frank; Ringel, Sebastian; Neuber, Corinna; Kleuser, Burkhard; Püschel, Gerhard P

2015-02-03

Xenobiotics may interfere with the hypothalamic-pituitary-thyroid endocrine axis by inducing enzymes that inactivate thyroid hormones and thereby reduce the metabolic rate. This induction results from an activation of xeno-sensing nuclear receptors. The current study shows that benzo[a]pyrene, a frequent contaminant of processed food and activator of the arylhydrocarbon receptor (AhR) activated the promoter and induced the transcription of the nuclear receptor constitutive androstane receptor (CAR, NR1I3) in rat hepatocytes. Likewise, phenobarbital induced the AhR transcription. This mutual induction of the nuclear receptors enhanced the phenobarbital-dependent induction of the prototypic CAR target gene Cyp2b1 as well as the AhR-dependent induction of UDP-glucuronosyltransferases. In both cases, the induction by the combination of both xenobiotics was more than the sum of the induction by either substance alone. By inducing the AhR, phenobarbital enhanced the benzo[a]pyrene-dependent reduction of thyroid hormone half-life and the benzo[a]pyrene-dependent increase in the rate of thyroid hormone glucuronide formation in hepatocyte cultures. CAR ligands might thus augment the endocrine disrupting potential of AhR activators by an induction of the AhR. Copyright © 2014. Published by Elsevier Ireland Ltd.

A hotspot in the glucocorticoid receptor DNA-binding domain susceptible to loss of function mutation

Science.gov (United States)

Banuelos, Jesus; Shin, Soon Cheon; Lu, Nick Z.

2015-01-01

Glucocorticoids (GCs) are used to treat a variety of inflammatory disorders and certain cancers. However, GC resistance occurs in subsets of patients. We found that EL4 cells, a GC-resistant mouse thymoma cell line, harbored a point mutation in their GC receptor (GR) gene, resulting in the substitution of arginine 493 by a cysteine in the second zinc finger of the DNA-binding domain. Allelic discrimination analyses revealed that the R493C mutation occurred on both alleles. In the absence of GCs, the GR in EL4 cells localized predominantly in the cytoplasm and upon dexamethasone treatment underwent nuclear translocation, suggesting the ligand binding ability of the GR in EL4 cells was intact. In transient transfection assays, the R493C mutant could not transactivate the MMTV-luciferase reporter. Site-directed mutagenesis to revert the R493C mutation restored the transactivation activity. Cotransfection experiments showed that the R493C mutant did not inhibit the transcriptional activities of the wild-type GR. In addition, the R493C mutant did not repress either the AP-1 or NF-κB reporters as effectively as WT GR. Furthermore, stable expression of the WT GR in the EL4 cells enabled GC-mediated gene regulation, specifically upregulation of IκBα and downregulation of interferon γ and interleukin 17A. Arginine 493 is conserved among multiple species and all human nuclear receptors and its mutation has also been found in the human GR, androgen receptor, and mineralocorticoid receptor. Thus, R493 is necessary for the transcriptional activity of the GR and a hotspot for mutations that result in GC resistance. PMID:25676786

Properties of GluR3 receptors tagged with GFP at the amino or carboxyl terminus.

Science.gov (United States)

Limon, Agenor; Reyes-Ruiz, Jorge Mauricio; Eusebi, Fabrizio; Miledi, Ricardo

2007-09-25

Anatomical visualization of neurotransmitter receptor localization is facilitated by tagging receptors, but this process can alter their functional properties. We have evaluated the distribution and properties of WT glutamate receptor 3 (GluR3) alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (WT GluR3) and two receptors in which GFP was tagged to the amino terminus (GFP-GluR3) or to the carboxyl terminus (GluR3-GFP). Although the fluorescence in Xenopus oocytes was stronger in the vegetal hemisphere because of localization of internal structures (probable sites of production, storage or recycling of receptors), the insertion of receptors into the plasma membrane was polarized to the animal hemisphere. The fluorescence intensity of oocytes injected with GluR3-GFP RNA was approximately double that of oocytes injected with GFP-GluR3 RNA. Accordingly, GluR3-GFP oocytes generated larger kainate-induced currents than GFP-GluR3 oocytes, with similar EC(50) values. Currents elicited by glutamate, or AMPA coapplied with cyclothiazide, were also larger in GluR3-GFP oocytes. The glutamate- to kainate-current amplitude ratios differed, with GluR3-GFP being activated more efficiently by glutamate than the WT or GFP-GluR3 receptors. This pattern correlates with the slower decay of glutamate-induced currents generated by GluR3-GFP receptors. These changes were not observed when GFP was tagged to the amino terminus, and these receptors behaved like the WT. The antagonistic effects of 6-nitro-7-sulfamoylbenzo[f]quinoxaline-2,3-dione (NBQX) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) were not altered in any of the tagged receptors. We conclude that GFP is a useful and convenient tag for visualizing these proteins. However, the effects of different sites of tag insertion on receptor characteristics must be taken into account in assessing the roles played by these receptor proteins.

40 CFR 255.31 - Integration with other acts.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Integration with other acts. 255.31 Section 255.31 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... Relationship to Other Programs § 255.31 Integration with other acts. The Governor shall integrate the...

40 CFR 255.32 - Coordination with other programs.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Coordination with other programs. 255.32 Section 255.32 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... Relationship to Other Programs § 255.32 Coordination with other programs. The region and agency identification...

Growth Hormone-Releaser Diet Attenuates Cognitive Dysfunction in Klotho Mutant Mice via Insulin-Like Growth Factor-1 Receptor Activation in a Genetic Aging Model

Directory of Open Access Journals (Sweden)

Seok Joo Park

2014-09-01

Full Text Available BackgroundIt has been recognized that a defect in klotho gene expression accelerates the degeneration of multiple age-sensitive traits. Accumulating evidence indicates that aging is associated with declines in cognitive function and the activity of growth hormone (GH/insulin-like growth factor-1 (IGF-1.MethodsIn this study, we examined whether a GH-releaser diet could be effective in protecting against cognitive impairment in klotho mutant mice.ResultsThe GH-releaser diet significantly induced the expression of IGF-1 and IGF-1 receptors in the hippocampus of klotho mutant mice. Klotho mutant mice showed significant memory impairments as compared with wild-type mice. In addition, the klotho mutation significantly decreased the expression of cell survival/antiapoptotic factors, including phospho-Akt (p-Akt/phospho-glycogen synthase kinase3β (p-GSK3β, phospho-extracellular signal-related kinase (p-ERK, and Bcl-2, but significantly increased those of cell death/proapoptotic factors, such as phospho-c-jun N-terminal kinase (p-JNK, Bax, and cleaved caspase-3 in the hippocampus. Treatment with GH-releaser diet significantly attenuated both decreases in the expression of cell survival/antiapoptotic factors and increases in the expression of cell death/proapoptotic factors in the hippocampus of klotho mutant mice. In addition, klotho mutation-induced oxidative stress was significantly attenuated by the GH-releaser diet. Consequently, a GH-releaser diet significantly improved memory function in the klotho mutant mice. GH-releaser diet-mediated actions were significantly reversed by JB-1, an IGF-1 receptor antagonist.ConclusionThe results suggest that a GH-releaser diet attenuates oxidative stress, proapoptotic changes and consequent dysfunction in klotho mutant mice by promoting IGF-1 expression and IGF-1 receptor activation.

Regulation of Pattern Formation and Gene Amplification During <i>Drosophila> Oogenesis by the miR-318 microRNA

DEFF Research Database (Denmark)

Ge, Wanzhong; Deng, Qiannan; Guo, Ting

2015-01-01

Pattern formation during epithelial development requires the coordination of multiple signaling pathways. Here, we investigate the functions of an ovary-enriched miRNA, miR-318, in epithelial development during Drosophila oogenesis. miR-318 maternal loss-of-function mutants were female sterile...... and laid eggs with abnormal morphology. Removal of miR-318 disrupted the dorsal-anterior follicle cell patterning, resulting in abnormal dorsal appendages. miR-318 mutant females also produced thin and fragile eggshells, due to impaired chorion gene amplification. We provide evidence that the ecdysone......RNAs in maintaining cell fate and promoting the developmental transition in the female follicular epithelium....

Type I and II positive allosteric modulators differentially modulate agonist-induced up-regulation of α7 nicotinic acetylcholine receptors

DEFF Research Database (Denmark)

Thomsen, Morten Skøtt; Mikkelsen, Jens D

2012-01-01

Long-term treatment with nicotine or selective α7 nicotinic acetylcholine receptor (nAChR) agonists increases the number of α7 nAChRs and this up-regulation may be involved in the mechanism underlying the sustained procognitive effect of these compounds. Here, we investigate the influence of type I...... expressing human α7 nAChR, whereas the type I PAMs AVL-3288 or NS1738 do not. Contrarily, neither type I nor II PAMs affect 10 μM nicotine-induced receptor up-regulation, suggesting that nicotine and A-582941 induce up-regulation through different mechanisms. We further show in vivo that 3 mg/kg PNU-120596...... is involved in A-582941-induced up-regulation. Our results are the first to show an in vivo difference between type I and II α7 nAChR PAMs, and demonstrate an agonist-dependent effect of type II PAMs occurring on a much longer time scale than previously appreciated. Furthermore, our data suggest that nicotine...

Synthesis of iodine-123 labelled analogues of the partial agonist (S)-and (R)-bretazenil for the study of CNS benzodiazepine receptors using SPECT

Energy Technology Data Exchange (ETDEWEB)

Katsifis, Andrew; Mattner, Filomena; McPhee, Meredith; Kassiou, Michael; Najdovski, Ljubco; Dikic, Branko [Australian Nuclear Science and Technology Organisation, Radiopharmaceutical Div., Menai, Sydney, NSW (Australia)

1996-09-01

The (S) and (R)-[{sup 123}I]iodinated analogues of the benzodiazepine receptor partial agonist bretazenil have been synthesized for study of the central benzodiazepine receptor using SPECT, (S)- and (R)-[{sup 123}I]iodobretazenil were prepared from the appropriate tin precursors by electrophilic iododestannylation with Na[{sup 123}I] in the presence of Chloramine-T. The products were purified by semi-preparative reverse-phase HPLC with radiochemical yields of 80% in a total synthesis time of 50 minutes. The specific activity was determined to be greater than 2500 Ci/mmol. The radiochemical and chemical purity assessed by radio-TLC and HPLC were found to be 98%. The enantiomeric purity of the (S) and (R) isomers were greater than 97% as assessed by analytical chiral HPLC analysis. (author).

Prevalence of melanocortin receptor 4 (MC4R) V103I gene variant and its association with obesity among the Kampar Health Clinic cohort, Perak, Malaysia.

Science.gov (United States)

Chua, H N; Fan, S H; Say, Y H

2012-04-01

This study investigated the prevalence of the Melanocortin receptor 4 (MC4R) V1031 gene variant and its association with obesity among a cohort of 254 patients (101 males; 118 obese) attending the Kampar Health Clinic. Genotyping revealed the mutated I allele frequency of 0.02, no homozygous mutated (II), and similar distribution of V and I alleles across BMI groups, genders and ethnic groups. No significant difference was found for the means of anthropometric measurements between alleles. Prevalence of this gene variant among the Malaysian cohort was similar with previous populations (2-4% of mutated allele carrier), but was not associated with obesity.

Allantoin ameliorates chemically-induced pancreatic β-cell damage through activation of the imidazoline I3 receptors

Directory of Open Access Journals (Sweden)

Marie Amitani

2015-08-01

Full Text Available Objective. Allantoin is the primary active compound in yams (Dioscorea spp.. Recently, allantoin has been demonstrated to activate imidazoline 3 (I3 receptors located in pancreatic tissues. Thus, the present study aimed to investigate the role of allantoin in the effect to improve damage induced in pancreatic β-cells by streptozotocin (STZ via the I3 receptors.Research Design and Methods. The effect of allantoin on STZ-induced apoptosis in pancreatic β-cells was examined using the ApoTox-Glo triplex assay, live/dead cell double staining assay, flow cytometric analysis, and Western blottings. The potential mechanism was investigated using KU14R: an I3 receptor antagonist, and U73122: a phospholipase C (PLC inhibitor. The effects of allantoin on serum glucose and insulin secretion were measured in STZ-treated rats.Results. Allantoin attenuated apoptosis and cytotoxicity and increased the viability of STZ-induced β-cells in a dose-dependent manner; this effect was suppressed by KU14R and U73112. Allantoin decreased the level of caspase-3 and increased the level of phosphorylated B-cell lymphoma 2 (Bcl-2 expression detected by Western blotting. The improvement in β-cells viability was confirmed using flow cytometry analysis. Daily injection of allantoin for 8 days in STZ-treated rats significantly lowered plasma glucose and increased plasma insulin levels. This action was inhibited by treatment with KU14R.Conclusion. Allantoin ameliorates the damage of β-cells induced by STZ. The blockade by pharmacological inhibitors indicated that allantoin can activate the I3 receptors through a PLC-related pathway to decrease this damage. Therefore, allantoin and related analogs may be effective in the therapy for β-cell damage.

Monoclonal antibody to the type I insulin-like growth factor (IGF-I) receptor blocks IGF-I receptor-mediated DNA synthesis: clarification of the mitogenic mechanisms of IGF-I and insulin in human skin fibroblasts

International Nuclear Information System (INIS)

Flier, J.S.; Usher, P.; Moses, A.C.

1986-01-01

Insulin and insulin-like growth factor type I (IGF-I) stimulate an overlapping spectrum of biological responses in human skin fibroblasts. Although insulin and IGF-I are known to stimulate the incorporation of [ 3 H]thymidine into DNA in these cells, the identify of the receptor(s) that mediates this effect has not been fully clarified. The mouse anti-human IGF-I receptor antibody αIR-3 binds with specificity to IGF-I but not to insulin receptors in human placental membranes; it also specifically inhibits the binding of 125 I-labeled IGF-I but not 125 I-labeled insulin to suspensions of human skin fibroblasts in a dose-dependent manner. αIR-3 competitively inhibits IGF-I-mediated stimulation of [ 3 H]thymidine incorporation into DNA. This inhibition is dependent on the concentration of αIR-3 and in the presence of a fixed antibody concentration can be partially overcome by high concentrations of IGF-I. In contrast, at concentrations of 3 H]thymidine incorporation is not inhibited by αIR-3. However, the incremental effects of higher concentrations (> 1 μg/ml) of insulin on [ 3 H]thymidine incorporation are inhibited by αIR-3. αIR-3 is a highly specific antagonist of IGF-I receptor-mediated mitogenesis in human skin fibroblasts. By using this antibody, it is shown directly that insulin can act through the IGF-I receptor to stimulate DNA synthesis but can also activate this effect through the insulin receptor itself

Enhanced antitumor efficacy of folate-linked liposomal doxorubicin with TGF-β type I receptor inhibitor

International Nuclear Information System (INIS)

Taniguchi, Yukimi; Kawano, Kumi; Minowa, Takuya; Shimojo, Yuki; Maitani, Yoshie; Sugino, Takashi

2010-01-01

Tumor cell targeting of drug carriers is a promising strategy and uses the attachment of various ligands to enhance the therapeutic potential of chemotherapy agents. Folic acid is a high-affinity ligand for folate receptor, which is a functional tumor-specific receptor. The transforming growth factor (TGF)-β type I receptor (TβR-I) inhibitor A-83-01 was expected to enhance the accumulation of nanocarriers in tumors by changing the microvascular environment. To enhance the therapeutic effect of folate-linked liposomal doxorubicin (F-SL), we co-administrated F-SL with A-83-01. Intraperitoneally injected A-83-01-induced alterations in the cancer-associated neovasculature were examined by magnetic resonance imaging (MRI) and histological analysis. The targeting efficacy of single intravenous injections of F-SL combined with A-83-01 was evaluated by measurement of the biodistribution and the antitumor effect in mice bearing murine lung carcinoma M109. A-83-01 temporarily changed the tumor vasculature around 3 h post injection. A-83-01 induced 1.7-fold higher drug accumulation of F-SL in the tumor than liposome alone at 24 h post injection. Moreover F-SL co-administrated with A-83-01 showed significantly greater antitumor activity than F-SL alone. This study shows that co-administration of TβR-I inhibitor will open a new strategy for the use of folate receptor (FR)-targeting nanocarriers for cancer treatment. (author)

Silencing neuronal mutant androgen receptor in a mouse model of spinal and bulbar muscular atrophy.

Science.gov (United States)

Sahashi, Kentaro; Katsuno, Masahisa; Hung, Gene; Adachi, Hiroaki; Kondo, Naohide; Nakatsuji, Hideaki; Tohnai, Genki; Iida, Madoka; Bennett, C Frank; Sobue, Gen

2015-11-01

Spinal and bulbar muscular atrophy (SBMA), an adult-onset neurodegenerative disease that affects males, results from a CAG triplet repeat/polyglutamine expansions in the androgen receptor (AR) gene. Patients develop progressive muscular weakness and atrophy, and no effective therapy is currently available. The tissue-specific pathogenesis, especially relative pathological contributions between degenerative motor neurons and muscles, remains inconclusive. Though peripheral pathology in skeletal muscle caused by toxic AR protein has been recently reported to play a pivotal role in the pathogenesis of SBMA using mouse models, the role of motor neuron degeneration in SBMA has not been rigorously investigated. Here, we exploited synthetic antisense oligonucleotides to inhibit the RNA levels of mutant AR in the central nervous system (CNS) and explore its therapeutic effects in our SBMA mouse model that harbors a mutant AR gene with 97 CAG expansions and characteristic SBMA-like neurogenic phenotypes. A single intracerebroventricular administration of the antisense oligonucleotides in the presymptomatic phase efficiently suppressed the mutant gene expression in the CNS, and delayed the onset and progression of motor dysfunction, improved body weight gain and survival with the amelioration of neuronal histopathology in motor units such as spinal motor neurons, neuromuscular junctions and skeletal muscle. These findings highlight the importance of the neurotoxicity of mutant AR protein in motor neurons as a therapeutic target. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

γ-Aminobutyric Acid Type B (GABAB) Receptor Internalization Is Regulated by the R2 Subunit*

Science.gov (United States)

Hannan, Saad; Wilkins, Megan E.; Dehghani-Tafti, Ebrahim; Thomas, Philip; Baddeley, Stuart M.; Smart, Trevor G.

2011-01-01

γ-Aminobutyric acid type B (GABAB) receptors are important for slow synaptic inhibition in the CNS. The efficacy of inhibition is directly related to the stability of cell surface receptors. For GABAB receptors, heterodimerization between R1 and R2 subunits is critical for cell surface expression and signaling, but how this determines the rate and extent of receptor internalization is unknown. Here, we insert a high affinity α-bungarotoxin binding site into the N terminus of the R2 subunit and reveal its dominant role in regulating the internalization of GABAB receptors in live cells. To simultaneously study R1a and R2 trafficking, a new α-bungarotoxin binding site-labeling technique was used, allowing α-bungarotoxin conjugated to different fluorophores to selectively label R1a and R2 subunits. This approach demonstrated that R1a and R2 are internalized as dimers. In heterologous expression systems and neurons, the rates and extents of internalization for R1aR2 heteromers and R2 homomers are similar, suggesting a regulatory role for R2 in determining cell surface receptor stability. The fast internalization rate of R1a, which has been engineered to exit the endoplasmic reticulum, was slowed to that of R2 by truncating the R1a C-terminal tail or by removing a dileucine motif in its coiled-coil domain. Slowing the rate of internalization by co-assembly with R2 represents a novel role for GPCR heterodimerization whereby R2 subunits, via their C terminus coiled-coil domain, mask a dileucine motif on R1a subunits to determine the surface stability of the GABAB receptor. PMID:21724853

Analysis of various types of single-polypeptide-chain (sc) heterodimeric A{sub 2A}R/D{sub 2}R complexes and their allosteric receptor–receptor interactions

Energy Technology Data Exchange (ETDEWEB)

Kamiya, Toshio, E-mail: kamiya@z2.keio.jp [Department of Molecular Cell Signaling, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526 (Japan); Department of Neurology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526 (Japan); Cell Biology Laboratory, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502 (Japan); Yoshioka, Kazuaki; Nakata, Hiroyasu [Department of Molecular Cell Signaling, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu, Tokyo 183-8526 (Japan)

2015-01-09

Highlights: • Various scA{sub 2A}R/D{sub 2}R constructs, with spacers between the two receptors, were created. • Using whole cell binding assay, constructs were examined for their binding activity. • Although the apparent ratio of A{sub 2A}R to D{sub 2}R binding sites should be 1, neither was 1. • Counter agonist-independent binding cooperativity occurred in context of scA{sub 2A}R/D{sub 2}R. - Abstract: Adenosine A{sub 2A} receptor (A{sub 2A}R) heteromerizes with dopamine D{sub 2} receptor (D{sub 2}R). However, these class A G protein-coupled receptor (GPCR) dimers are not fully formed, but depend on the equilibrium between monomer and dimer. In order to stimulate the heteromerization, we have previously shown a successful design for a fusion receptor, single-polypeptide-chain (sc) heterodimeric A{sub 2A}R/D{sub 2}R complex. Here, using whole cell binding assay, six more different scA{sub 2A}R/D{sub 2}R constructs were examined. Not only in scA{sub 2A}R/D{sub 2}R ‘liberated’ with longer spacers between the two receptors, which confer the same configuration as the prototype, the A{sub 2A}R-odr4TM-D{sub 2L}R, but differ in size (Forms 1–3), but also in scA{sub 2A}R/D{sub 2L}R (Form 6) fused with a transmembrane (TM) of another type II TM protein, instead of odr4TM, neither of their fixed stoichiometry (the apparent ratios of A{sub 2A}R to D{sub 2}R binding sites) was 1, suggesting their compact folding. This suggests that type II TM, either odr4 or another, facilitates the equilibrial process of the dimer formation between A{sub 2A}R and D{sub 2L}R, resulting in the higher-order oligomer formation from monomer of scA{sub 2A}R/D{sub 2L}R itself. Also, in the reverse type scA{sub 2A}R/D{sub 2L}R, i.e., the D{sub 2L}R-odr4TM-A{sub 2A}R, counter agonist-independent binding cooperativity (cooperative folding) was found to occur (Forms 4 and 5). In this way, the scA{sub 2A}R/D{sub 2L}R system has unveiled the cellular phenomenon as a snapshot of the

21 CFR 137.255 - Bolted white corn meal.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Bolted white corn meal. 137.255 Section 137.255... Flours and Related Products § 137.255 Bolted white corn meal. (a) Bolted white corn meal is the food prepared by so grinding and sifting cleaned white corn that: (1) Its crude fiber content is less than 1.2...

Structure and assembly mechanism for heteromeric kainate receptors.

Science.gov (United States)

Kumar, Janesh; Schuck, Peter; Mayer, Mark L

2011-07-28

Native glutamate receptor ion channels are tetrameric assemblies containing two or more different subunits. NMDA receptors are obligate heteromers formed by coassembly of two or three divergent gene families. While some AMPA and kainate receptors can form functional homomeric ion channels, the KA1 and KA2 subunits are obligate heteromers which function only in combination with GluR5-7. The mechanisms controlling glutamate receptor assembly involve an initial step in which the amino terminal domains (ATD) assemble as dimers. Here, we establish by sedimentation velocity that the ATDs of GluR6 and KA2 coassemble as a heterodimer of K(d) 11 nM, 32,000-fold lower than the K(d) for homodimer formation by KA2; we solve crystal structures for the GluR6/KA2 ATD heterodimer and heterotetramer assemblies. Using these structures as a guide, we perform a mutant cycle analysis to probe the energetics of assembly and show that high-affinity ATD interactions are required for biosynthesis of functional heteromeric receptors. Copyright © 2011 Elsevier Inc. All rights reserved.

TRAIL-receptor preferences in pancreatic cancer cells revisited: Both TRAIL-R1 and TRAIL-R2 have a licence to kill

International Nuclear Information System (INIS)

Mohr, Andrea; Yu, Rui; Zwacka, Ralf M.

2015-01-01

TRAIL is a potent and specific inducer of apoptosis in tumour cells and therefore is a possible new cancer treatment. It triggers apoptosis by binding to its cognate, death-inducing receptors, TRAIL-R1 and TRAIL-R2. In order to increase its activity, receptor-specific ligands and agonistic antibodies have been developed and some cancer types, including pancreatic cancer, have been reported to respond preferentially to TRAIL-R1 triggering. The aim of the present study was to examine an array of TRAIL-receptor specific variants on a number of pancreatic cancer cells and test the generality of the concept of TRAIL-R1 preference in these cells. TRAIL-R1 and TRAIL-R2 specific sTRAIL variants were designed and tested on a number of pancreatic cancer cells for their TRAIL-receptor preference. These sTRAIL variants were produced in HEK293 cells and were secreted into the medium. After having measured and normalised the different sTRAIL variant concentrations, they were applied to pancreatic and control cancer cells. Twenty-four hours later apoptosis was measured by DNA hypodiploidy assays. Furthermore, the specificities of the sTRAIL variants were validated in HCT116 cells that were silenced either for TRAIL-R1 or TRAIL-R2. Our results show that some pancreatic cancer cells use TRAIL-R1 to induce cell death, whereas other pancreatic carcinoma cells such as AsPC-1 and BxPC-3 cells trigger apoptosis via TRAIL-R2. This observation extended to cells that were naturally TRAIL-resistant and had to be sensitised by silencing of XIAP (Panc1 cells). The measurement of TRAIL-receptor expression by FACS revealed no correlation between receptor preferences and the relative levels of TRAIL-R1 and TRAIL-R2 on the cellular surface. These results demonstrate that TRAIL-receptor preferences in pancreatic cancer cells are variable and that predictions according to cancer type are difficult and that determining factors to inform the optimal TRAIL-based treatments still have to be identified

Coamplification of miR-4728 protects HER2-amplified breast cancers from targeted therapy

Science.gov (United States)

Floros, Konstantinos V.; Hu, Bin; Monterrubio, Carles; Hughes, Mark T.; Wells, Jason D.; Morales, Cristina Bernadó; Ghotra, Maninderjit S.; Costa, Carlotta; Souers, Andrew J.; Boikos, Sosipatros A.; Leverson, Joel D.; Tan, Ming; Serra, Violeta; Koblinski, Jennifer E.; Arribas, Joaquin; Prat, Aleix; Paré, Laia; Miller, Todd W.; Harada, Hisashi; Windle, Brad E.; Scaltriti, Maurizio; Faber, Anthony C.

2018-01-01

HER2 (ERBB2) amplification is a driving oncogenic event in breast cancer. Clinical trials have consistently shown the benefit of HER2 inhibitors (HER2i) in treating patients with both local and advanced HER2+ breast cancer. Despite this benefit, their efficacy as single agents is limited, unlike the robust responses to other receptor tyrosine kinase inhibitors like EGFR inhibitors in EGFR-mutant lung cancer. Interestingly, the lack of HER2i efficacy occurs despite sufficient intracellular signaling shutdown following HER2i treatment. Exploring possible intrinsic causes for this lack of response, we uncovered remarkably depressed levels of NOXA, an endogenous inhibitor of the antiapoptotic MCL-1, in HER2-amplified breast cancer. Upon investigation of the mechanism leading to low NOXA, we identified a micro-RNA encoded in an intron of HER2, termed miR-4728, that targets the mRNA of the Estrogen Receptor α (ESR1). Reduced ESR1 expression in turn prevents ERα-mediated transcription of NOXA, mitigating apoptosis following treatment with the HER2i lapatinib. Importantly, resistance can be overcome with pharmacological inhibition of MCL-1. More generally, while many cancers like EGFR-mutant lung cancer are driven by activated kinases that when drugged lead to robust monotherapeutic responses, we demonstrate that the efficacy of targeted therapies directed against oncogenes active through focal amplification may be mitigated by coamplified genes. PMID:29476008

Double-strand break repair and genetic recombination in topoisomerase and primase mutants of bacteriophage T4.

Science.gov (United States)

Shcherbakov, Victor P; Kudryashova, Elena

2014-09-01

The effects of primase and topoisomerase II deficiency on the double-strand break (DSB) repair and genetic recombination in bacteriophage T4 were studied in vivo using focused recombination. Site-specific DSBs were induced by SegC endonuclease in the rIIB gene of one of the parents. The frequency/distance relationship was determined in crosses of the wild-type phage, topoisomerase II mutant amN116 (gene 39), and primase mutant E219 (gene 61). Ordinary two-factor (i×j) and three-factor (i k×j) crosses between point rII mutations were also performed. These data provide information about the frequency and distance distribution of the single-exchange (splice) and double-exchange (patch) events. In two-factor crosses ets1×i, the topoisomerase and primase mutants had similar recombinant frequencies in crosses at ets1-i distances longer than 1000 bp, comprising about 80% of the corresponding wild-type values. They, however, differ remarkably in crosses at shorter distances. In the primase mutant, the recombinant frequencies are similar to those in the wild-type crosses at distances less than 100 bp, being a bit diminished at longer distances. In two-factor crosses ets1×i of the topoisomerase mutant, the recombinant frequencies were reduced ten-fold at the shortest distances. In three-factor crosses a6 ets1×i, where we measure patch-related recombination, the primase mutant was quite proficient across the entire range of distances. The topoisomerase mutant crosses demonstrated virtually complete absence of rII(+) recombinants at distances up to 33 bp, with the frequencies increasing steadily at longer distances. The data were interpreted as follows. The primase mutant is fully recombination-proficient. An obvious difference from the wild-type state is some shortage of EndoVII function leading to prolonged existence of HJs and thus stretched out ds-branch migration. This is also true for the topoisomerase mutant. However, the latter is deficient in the ss

Detailed conformation dynamics and activation process of wild type c-Abl and T315I mutant

Science.gov (United States)

Yang, Li-Jun; Zhao, Wen-Hua; Liu, Qian

2014-10-01

Bcr-Abl is an important target for therapy against chronic myelogenous leukemia (CML) and acute lymphocytic leukemia (ALL). The synergistic effect between myristyl pocket and the ATP pocket has been found. But its detailed information based on molecular level still has not been achieved. In this study, conventional molecular dynamics (CMD) and target molecular dynamics (TMD) simulations were performed to explore the effect of T315I mutation on dynamics and activation process of Abl containing the N-terminal cap (Ncap). The CMD simulation results reveal the increasing flexibility of ATP pocket in kinase domain (KD) after T315I mutation which confirms the disability of ATP-pocket inhibitors to the Abl-T315I mutant. On the contrary, the T315I mutation decreased the flexibility of remote helix αI which suggests the synergistic effect between them. The mobility of farther regions containing Ncap, SH3, SH2 and SH2-KD linker were not affected by T315I mutation. The TMD simulation results show that the activation process of wild type Abl and Abl-T315I mutant experienced global conformation change. Their differences were elucidated by the activation motion of subsegments including A-loop, P-loop and Ncap. Besides, the T315I mutation caused decreasing energy barrier and increasing intermediate number in activation process, which results easier activation process. The TMD and CMD results indicate that a drug targeting only the ATP pocket is not enough to inhibit the Abl-T315I mutant. An effective way to inhibit the abnormal activity of Abl-T315I mutant is to combine the ATP-pocket inhibitors with inhibitors binding at non-ATP pockets mainly related to Ncap, SH2-KD linker and myristyl pocket.

Bacterio-opsin mutants of Halobacterium halobium

Science.gov (United States)

Betlach, Mary; Pfeifer, Felicitas; Friedman, James; Boyer, Herbert W.

1983-01-01

The bacterio-opsin (bop) gene of Halobacterium halobium R1 has been cloned with about 40 kilobases of flanking genomic sequence. The 40-kilobase segment is derived from the (G+C)-rich fraction of the chromosome and is not homologous to the major (pHH1) or minor endogenous covalently closed circular DNA species of H. halobium. A 5.1-kilobase Pst I fragment containing the bop gene was subcloned in pBR322 and a partial restriction map was determined. Defined restriction fragments of this clone were used as probes to analyze the defects associated with the bop gene in 12 bacterio-opsin mutants. Eleven out of 12 of the mutants examined had inserts ranging from 350 to 3,000 base pairs either in the bop gene or up to 1,400 base pairs upstream. The positions of the inserts were localized to four regions in the 5.1-kilobase genomic fragment: within the gene (one mutant), in a region that overlaps the 5′ end of the gene (seven mutants), and in two different upstream regions (three mutants). Two revertants of the mutant with the most distal insert had an additional insert in the same region. The polar effects of these inserts are discussed in terms of inactivation of a regulatory gene or disruption of part of a coordinately expressed operon. Given the defined nature of the bop mRNA—i.e., it has a 5′ leader sequence of three ribonucleotides—these observations indicate that the bop mRNA might be processed from a large mRNA transcript. Images PMID:16593291

Cytogenetic characteristics of soft wheat mutants under x-irradiation

International Nuclear Information System (INIS)

Shakaryan, Zh.O.; Avakyan, V.A.; Amirbekyan, V.A.

1981-01-01

Radiosensitivity of induced mutants of soft wheat is studied by criteria of frequency and character of changes in 1 and 2 divisions of meiosis. Two constant induced mutant forms of soft wheat were investigated. Mutant lines of squareheads with red ear (re) and erectoids 37/1 were obtained by X-ray irradiating hydride seeds F 1 of hybride combination of Alty-Agach Awnless 1. Seeds of mutants and initial kinds were exposed to X-rays at a dose of 10 kR. A conclusion may be drawn on the basis of studying the meiosis process in mutants and initial kinds of soft wheat on X-ray radiation that the mutants are more radiosensitive. This testifies to that that the induced mutants of soft wheat represent new genotypes in comparison with the initial kinds and differ from the latter not only in morphological characters but in the reaction norm with respect to external medium factors, i.e. the limit of possible changeability of the genotype has been extended [ru

Potent haloperidol derivatives covalently binding to the dopamine D2 receptor.

Science.gov (United States)

Schwalbe, Tobias; Kaindl, Jonas; Hübner, Harald; Gmeiner, Peter

2017-10-01

The dopamine D 2 receptor (D 2 R) is a common drug target for the treatment of a variety of neurological disorders including schizophrenia. Structure based design of subtype selective D 2 R antagonists requires high resolution crystal structures of the receptor and pharmacological tools promoting a better understanding of the protein-ligand interactions. Recently, we reported the development of a chemically activated dopamine derivative (FAUC150) designed to covalently bind the L94C mutant of the dopamine D 2 receptor. Using FAUC150 as a template, we elaborated the design and synthesis of irreversible analogs of the potent antipsychotic drug haloperidol forming covalent D 2 R-ligand complexes. The disulfide- and Michael acceptor-functionalized compounds showed significant receptor affinity and an irreversible binding profile in radioligand depletion experiments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Role of interleukin-1 receptor signaling in the behavioral effects of ethanol and benzodiazepines.

Science.gov (United States)

Blednov, Yuri A; Benavidez, Jillian M; Black, Mendy; Mayfield, Jody; Harris, R Adron

2015-08-01

Gene expression studies identified the interleukin-1 receptor type I (IL-1R1) as part of a pathway associated with a genetic predisposition to high alcohol consumption, and lack of the endogenous IL-1 receptor antagonist (IL-1ra) strongly reduced ethanol intake in mice. Here, we compared ethanol-mediated behaviors in mice lacking Il1rn or Il1r1. Deletion of Il1rn (the gene encoding IL-1ra) increases sensitivity to the sedative/hypnotic effects of ethanol and flurazepam and reduces severity of acute ethanol withdrawal. Conversely, deletion of Il1r1 (the gene encoding the IL-1 receptor type I, IL-1R1) reduces sensitivity to the sedative effects of ethanol and flurazepam and increases the severity of acute ethanol withdrawal. The sedative effects of ketamine and pentobarbital were not altered in the knockout (KO) strains. Ethanol intake and preference were not changed in mice lacking Il1r1 in three different tests of ethanol consumption. Recovery from ethanol-induced motor incoordination was only altered in female mice lacking Il1r1. Mice lacking Il1rn (but not Il1r1) showed increased ethanol clearance and decreased ethanol-induced conditioned taste aversion. The increased ethanol- and flurazepam-induced sedation in Il1rn KO mice was decreased by administration of IL-1ra (Kineret), and pre-treatment with Kineret also restored the severity of acute ethanol withdrawal. Ethanol-induced sedation and withdrawal severity were changed in opposite directions in the null mutants, indicating that these responses are likely regulated by IL-1R1 signaling, whereas ethanol intake and preference do not appear to be solely regulated by this pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evidence for cooperative signal triggering at the extracellular loops of the TSH receptor.

Science.gov (United States)

Kleinau, Gunnar; Jaeschke, Holger; Mueller, Sandra; Raaka, Bruce M; Neumann, Susanne; Paschke, Ralf; Krause, Gerd

2008-08-01

The mechanisms governing transition of the thyroid stimulating hormone (TSH) receptor (TSHR) from basal to active conformations are poorly understood. Considering that constitutively activating mutations (CAMs) and inactivating mutations in each of the extracellular loops (ECLs) trigger only partial TSHR activation or inactivation, respectively, we hypothesized that full signaling occurs via multiple extracellular signal propagation events. Therefore, individual CAMs in the extracellular region were combined to create double and triple mutants. In support of our hypothesis, combinations of mutants in the ECLs are in some cases additive, while in others they are even synergistic, with triple mutant I486A/I568V/V656F exhibiting a 70-fold increase in TSH-independent signaling. The proximity but likely different spatial orientation of the residues of activating and inactivating mutations in each ECL supports a dual functionality to facilitate signal induction and conduction, respectively. This is the first report for G-protein coupled receptors, suggesting that multiple and cooperative signal propagating events at all three ECLs are required for full receptor activation. Our findings provide new insights concerning molecular signal transmission from extracellular domains toward the transmembrane helix bundle of the glycoprotein hormone receptors.

Neurospora crassa ncs-1, mid-1 and nca-2 double-mutant ...

Indian Academy of Sciences (India)

logue of Neuronal Calcium Sensor-1 has a role in growth, cal- cium stress tolerance, and ultraviolet survival. Genetica 139,. 885–894. Lew R. R., Abbas Z., Anderca M. I. and Free S. J. 2008 Phe- notype of a mechanosensitive channel mutant, mid-1, in a fil- amentous fungus, Neurospora crassa. Eukaryot. Cell. 7, 647–. 655.

rigor mortis encodes a novel nuclear receptor interacting protein required for ecdysone signaling during Drosophila larval development.

Science.gov (United States)

Gates, Julie; Lam, Geanette; Ortiz, José A; Losson, Régine; Thummel, Carl S

2004-01-01

Pulses of the steroid hormone ecdysone trigger the major developmental transitions in Drosophila, including molting and puparium formation. The ecdysone signal is transduced by the EcR/USP nuclear receptor heterodimer that binds to specific response elements in the genome and directly regulates target gene transcription. We describe a novel nuclear receptor interacting protein encoded by rigor mortis (rig) that is required for ecdysone responses during larval development. rig mutants display defects in molting, delayed larval development, larval lethality, duplicated mouth parts, and defects in puparium formation--phenotypes that resemble those seen in EcR, usp, E75A and betaFTZ-F1 mutants. Although the expression of these nuclear receptor genes is essentially normal in rig mutant larvae, the ecdysone-triggered switch in E74 isoform expression is defective. rig encodes a protein with multiple WD-40 repeats and an LXXLL motif, sequences that act as specific protein-protein interaction domains. Consistent with the presence of these elements and the lethal phenotypes of rig mutants, Rig protein interacts with several Drosophila nuclear receptors in GST pull-down experiments, including EcR, USP, DHR3, SVP and betaFTZ-F1. The ligand binding domain of betaFTZ-F1 is sufficient for this interaction, which can occur in an AF-2-independent manner. Antibody stains reveal that Rig protein is present in the brain and imaginal discs of second and third instar larvae, where it is restricted to the cytoplasm. In larval salivary gland and midgut cells, however, Rig shuttles between the cytoplasm and nucleus in a spatially and temporally regulated manner, at times that correlate with the major lethal phase of rig mutants and major switches in ecdysone-regulated gene expression. Taken together, these data indicate that rig exerts essential functions during larval development through gene-specific effects on ecdysone-regulated transcription, most likely as a cofactor for one or more

Phosphoribosylpyrophosphate synthetase of <i>Escherichia colii>, Identification of a mutant enzyme

DEFF Research Database (Denmark)

Hove-Jensen, Bjarne; Nygaard, Per

1982-01-01

, stimulated the mutant enzyme. The activity of PRib-PP synthetase in crude extract was higher in the mutant than in the parent. When starved for purines an accumulation of PRib-PP was observed in the parent strain, while the pool decreased in the mutant. During pyrimidine starvation derepression of PRib...

alpha7 Nicotinic acetylcholine receptor knockout selectively enhances ethanol-, but not beta-amyloid-induced neurotoxicity.

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de Fiebre, Nancyellen C; de Fiebre, Christopher M

2005-01-03

The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.

AcvR1-mediated BMP signaling in second heart field is required for arterial pole development: implications for myocardial differentiation and regional identity.

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Thomas, Penny S; Rajderkar, Sudha; Lane, Jamie; Mishina, Yuji; Kaartinen, Vesa

2014-06-15

BMP signaling plays an essential role in second heart field-derived heart and arterial trunk development, including myocardial differentiation, right ventricular growth, and interventricular, outflow tract and aortico-pulmonary septation. It is mediated by a number of different BMP ligands, and receptors, many of which are present simultaneously. The mechanisms by which they regulate morphogenetic events and degree of redundancy amongst them have still to be elucidated. We therefore assessed the role of BMP Type I receptor AcvR1 in anterior second heart field-derived cell development, and compared it with that of BmpR1a. By removing Acvr1 using the driver Mef2c[AHF]-Cre, we show that AcvR1 plays an essential role in arterial pole morphogenesis, identifying defects in outflow tract wall and cushion morphology that preceded a spectrum of septation defects from double outlet right ventricle to common arterial trunk in mutants. Its absence caused dysregulation in gene expression important for myocardial differentiation (Isl1, Fgf8) and regional identity (Tbx2, Tbx3, Tbx20, Tgfb2). Although these defects resemble to some degree those in the equivalent Bmpr1a mutant, a novel gene knock-in model in which Bmpr1a was expressed in the Acvr1 locus only partially restored septation in Acvr1 mutants. These data show that both BmpR1a and AcvR1 are needed for normal heart development, in which they play some non-redundant roles, and refine our understanding of the genetic and morphogenetic processes underlying Bmp-mediated heart development important in human congenital heart disease. Copyright © 2014 Elsevier Inc. All rights reserved.

Secretory overexpression and isotopic labeling of the chimeric relaxin family peptide R3/I5 in Pichia pastoris.

Science.gov (United States)

Guo, Yu-Qi; Wu, Qing-Ping; Shao, Xiao-Xia; Shen, Ting; Liu, Ya-Li; Xu, Zeng-Guang; Guo, Zhan-Yun

2015-06-01

Relaxin family peptides are a group of peptide hormones with divergent biological functions. Mature relaxin family peptides are typically composed of two polypeptide chains with three disulfide linkages, rendering their preparation a challenging task. In the present study, we established an efficient approach for preparation of the chimeric relaxin family peptide R3/I5 through secretory overexpression in Pichia pastoris and in vitro enzymatic maturation. A designed single-chain R3/I5 precursor containing the B-chain of human relaxin-3 and the A-chain of human INSL5 was overexpressed in PichiaPink strain 1 by high-density fermentation in a two-liter fermenter, and approximately 200 mg of purified precursor was obtained from one liter of the fermentation supernatant. We also developed an economical approach for preparation of the uniformly (15)N-labeled R3/I5 precursor by culturing in shaking flasks, and approximately 15 mg of purified (15)N-labeled precursor was obtained from one liter of the culture supernatant. After purification by cation ion-exchange chromatography and reverse-phase high performance liquid chromatography, the R3/I5 precursor was converted to the mature two-chain form by sequential treatment with endoproteinase Lys-C and carboxypeptidase B. The mature R3/I5 peptide had an α-helix-dominated conformation and retained full receptor-binding and receptor activation activities. Thus, Pichia overexpression was an efficient approach for sample preparation and isotopic labeling of the chimeric R3/I5 peptide. This approach could also be extended to the preparation of other relaxin family peptides in future studies.

Replication-dependent 65R→K reversion in human immunodeficiency virus type 1 reverse transcriptase double mutant K65R + L74V

International Nuclear Information System (INIS)

Sharma, Prem L.; Nurpeisov, Viktoria; Lee, Kimberly; Skaggs, Sara; Di San Filippo, Christina Amat; Schinazi, Raymond F.

2004-01-01

Understanding of the mechanisms of interaction among nucleoside reverse transcriptase inhibitor (NRTI)-selected mutations in the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) coding sequence is essential for the design of newer drugs and for enhancing our vision of the structure function relationship among amino acids of the polymerase domain of HIV-1. Although several nucleoside reverse transcriptase inhibitors select RT mutations K65R and L74V, the combination of 65R + 74V is rare in clinics. A novel NRTI (-)-β-D-dioxolane-guanosine (DXG) is known to select in vitro either the 65R or 74V mutant virus (Antimicrob. Agents Chemother. 44 (2000) 1783). These mutations were not selected together during repeated passaging of the HIV-1 in the presence of this drug. To analyze the impact of these RT mutations on viral replication, a double mutant containing K65R + L74V was created by site-directed mutagenesis in a pNL4-3 background. Replication kinetic assays revealed that the mutant K65R + L74V is unstable, and 65R→K reversion occurs during replication of virus in phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear (PBM) cells in the absence of selection pressure. Replication kinetic assays in MT-2 cells demonstrated that double mutant 65R + 74V is highly attenuated for replication and the initiation of reversion is related to the increase in RT activity. Additionally, the suppression of viral replication in the presence of DXG or under suboptimal human recombinant interleukin-2 leads to minimal or no 65R→K reversion. These observations provide evidence that 65R→K reversion in the double mutant 65R + 74V is dependent on a specific rate of viral replication in a pNL4-3 background. A similar phenomenon may occur in vivo, which may have implications for treatment management strategies

The expression of the ACTH receptor

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L.L.K. Elias

2000-10-01

Full Text Available Adrenal glucocorticoid secretion is regulated by adrenocorticotropic hormone (ACTH acting through a specific cell membrane receptor (ACTH-R. The ACTH-R is a member of the G protein superfamily-coupled receptors and belongs to the subfamily of melanocortin receptors. The ACTH-R is mainly expressed in the adrenocortical cells showing a restricted tissue specificity, although ACTH is recognized by the other four melanocortin receptors. The cloning of the ACTH-R was followed by the study of this gene in human diseases such as familial glucocorticoid deficiency (FGD and adrenocortical tumors. FGD is a rare autosomal recessive disease characterized by glucocorticoid deficiency, elevated plasma ACTH levels and preserved renin/aldosterone secretion. This disorder has been ascribed to an impaired adrenal responsiveness to ACTH due to a defective ACTH-R, a defect in intracellular signal transduction or an abnormality in adrenal cortical development. Mutations of the ACTH-R have been described in patients with FGD in segregation with the disease. The functional characterization of these mutations has been prevented by difficulties in expressing human ACTH-R in cells that lack endogenous melanocortin receptor activity. To overcome these difficulties we used Y6 cells, a mutant variant of the Y1 cell line, which possesses a non-expressed ACTH-R gene allowing the functional study without any background activity. Our results demonstrated that the several mutations of the ACTH-R found in FGD result in an impaired cAMP response or loss of sensitivity to ACTH stimulation. An ACTH-binding study showed an impairment of ligand binding with loss of the high affinity site in most of the mutations studied.

4 CFR 25.5 - Conformity with signs and directions.

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2010-01-01

... 4 Accounts 1 2010-01-01 2010-01-01 false Conformity with signs and directions. 25.5 Section 25.5 Accounts GOVERNMENT ACCOUNTABILITY OFFICE GENERAL PROCEDURES CONDUCT IN THE GOVERNMENT ACCOUNTABILITY OFFICE BUILDING AND ON ITS GROUNDS § 25.5 Conformity with signs and directions. Persons in the GAO...

The chimeric ubiquitin ligase SH2-U-box inhibits the growth of imatinib-sensitive and resistant CML by targeting the native and T315I-mutant BCR-ABL.

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Ru, Yi; Wang, Qinhao; Liu, Xiping; Zhang, Mei; Zhong, Daixing; Ye, Mingxiang; Li, Yuanchun; Han, Hua; Yao, Libo; Li, Xia

2016-06-22

Chronic myeloid leukemia (CML) is characterized by constitutively active fusion protein tyrosine kinase BCR-ABL. Although the tyrosine kinase inhibitor (TKI) against BCR-ABL, imatinib, is the first-line therapy for CML, acquired resistance almost inevitably emerges. The underlying mechanism are point mutations within the BCR-ABL gene, among which T315I is notorious because it resists to almost all currently available inhibitors. Here we took use of a previously generated chimeric ubiquitin ligase, SH2-U-box, in which SH2 from the adaptor protein Grb2 acts as a binding domain for activated BCR-ABL, while U-box from CHIP functions as an E3 ubiquitin ligase domain, so as to target the ubiquitination and degradation of both native and T315I-mutant BCR-ABL. As such, SH2-U-box significantly inhibited proliferation and induced apoptosis in CML cells harboring either the wild-type or T315I-mutant BCR-ABL (K562 or K562R), with BCR-ABL-dependent signaling pathways being repressed. Moreover, SH2-U-box worked in concert with imatinib in K562 cells. Importantly, SH2-U-box-carrying lentivirus could markedly suppress the growth of K562-xenografts in nude mice or K562R-xenografts in SCID mice, as well as that of primary CML cells. Collectively, by degrading the native and T315I-mutant BCR-ABL, the chimeric ubiquitin ligase SH2-U-box may serve as a potential therapy for both imatinib-sensitive and resistant CML.

Cytotoxicity of 125I decay in the DNA double strand break repair deficient mutant cell line, xrs-5

International Nuclear Information System (INIS)

Yasui, L.S.

1992-01-01

Survival of parental Chinese hamster ovary (CHO) K1 cells and the DNA double strand break (DSB) repair deficient mutant, xrs-5 was determined after accumulation of 125 I decays. Both CHO and xrs-5 cells were extremely sensitive to accumulated 125 I decays. D o values for CHO and xrs-5 cells were 40 and approximately 7 decays per cell, respectively. Difference in cell survival between CHO and xrs-5 cells was not due to differences in overall 125 IUdR incorporation, differences in labelling index (LI) or differences in plating efficiency (PE). Relative biological effectiveness (RBE) values calculated relative to 137 Cs gamma radiation survival values (D o and D 10 ) were higher in xrs-5 cells compared with CHO cells, although both CHO and xrs-5 cells have high RBE values that correspond to a high sensitivity of CHO and xrs-5 cells to 125 I decay. (Author)

T1r3 taste receptor involvement in gustatory neural responses to ethanol and oral ethanol preference.

Science.gov (United States)

Brasser, Susan M; Norman, Meghan B; Lemon, Christian H

2010-05-01

Elevated alcohol consumption is associated with enhanced preference for sweet substances across species and may be mediated by oral alcohol-induced activation of neurobiological substrates for sweet taste. Here, we directly examined the contribution of the T1r3 receptor protein, important for sweet taste detection in mammals, to ethanol intake and preference and the neural processing of ethanol taste by measuring behavioral and central neurophysiological responses to oral alcohol in T1r3 receptor-deficient mice and their C57BL/6J background strain. T1r3 knockout and wild-type mice were tested in behavioral preference assays for long-term voluntary intake of a broad concentration range of ethanol, sucrose, and quinine. For neurophysiological experiments, separate groups of mice of each genotype were anesthetized, and taste responses to ethanol and stimuli of different taste qualities were electrophysiologically recorded from gustatory neurons in the nucleus of the solitary tract. Mice lacking the T1r3 receptor were behaviorally indifferent to alcohol (i.e., ∼50% preference values) at concentrations typically preferred by wild-type mice (5-15%). Central neural taste responses to ethanol in T1r3-deficient mice were significantly lower compared with C57BL/6J controls, a strain for which oral ethanol stimulation produced a concentration-dependent activation of sweet-responsive NTS gustatory neurons. An attenuated difference in ethanol preference between knockouts and controls at concentrations >15% indicated that other sensory and/or postingestive effects of ethanol compete with sweet taste input at high concentrations. As expected, T1r3 knockouts exhibited strongly suppressed behavioral and neural taste responses to sweeteners but did not differ from wild-type mice in responses to prototypic salt, acid, or bitter stimuli. These data implicate the T1r3 receptor in the sensory detection and transduction of ethanol taste.

Arabidopsis mutant sk156 reveals complex regulation of SPL15 in a miR156-controlled gene network.

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Wei, Shu; Gruber, Margaret Y; Yu, Bianyun; Gao, Ming-Jun; Khachatourians, George G; Hegedus, Dwayne D; Parkin, Isobel A P; Hannoufa, Abdelali

2012-09-18

The Arabidopsis microRNA156 (miR156) regulates 11 members of the SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) family by base pairing to complementary target mRNAs. Each SPL gene further regulates a set of other genes; thus, miR156 controls numerous genes through a complex gene regulation network. Increased axillary branching occurs in transgenic Arabidopsis overexpressing miR156b, similar to that observed in loss-of-function max3 and max4 mutants with lesions in carotenoid cleavage dioxygenases. Arabidopsis miR156b was found to enhance carotenoid levels and reproductive shoot branching when expressed in Brassica napus, suggesting a link between miR156b expression and carotenoid metabolism. However, details of the miR156 regulatory network of SPL genes related to carotenoid metabolism are not known. In this study, an Arabidopsis T-DNA enhancer mutant, sk156, was identified due to its altered branching and trichome morphology and increased seed carotenoid levels compared to wild type (WT) ecovar Columbia. Enhanced miR156b expression due to the 35S enhancers present on the T-DNA insert was responsible for these phenotypes. Constitutive and leaf primodium-specific expression of a miR156-insensitive (mutated) SPL15 (SPL15m) largely restored WT seed carotenoid levels and plant morphology when expressed in sk156. The Arabidopsis native miR156-sensitive SPL15 (SPL15n) and SPL15m driven by a native SPL15 promoter did not restore the WT phenotype in sk156. Our findings suggest that SPL15 function is somewhat redundant with other SPL family members, which collectively affect plant phenotypes. Moreover, substantially decreased miR156b transcript levels in sk156 expressing SPL15m, together with the presence of multiple repeats of SPL-binding GTAC core sequence close to the miR156b transcription start site, suggested feedback regulation of miR156b expression by SPL15. This was supported by the demonstration of specific in vitro interaction between DNA-binding SBP domain of SPL15

Association of the IL4R single-nucleotide polymorphism I50V with recurrent spontaneous abortion (RSA).

Science.gov (United States)

Tavasolian, Fataneh; Abdollahi, Elham; Samadi, Morteza

2014-07-01

Recurrent spontaneous abortion (RSA) is defined as three or more consecutive abortions before the 20th week of gestation. There is increasing evidence to support an immunological mechanism for the occurrence of RSA. The purpose of our study was to examine whether single-nucleotide polymorphisms (SNPs) of the interleukin-4 receptor gene IL4R influence susceptibility to, recurrent spontaneous abortion. This is a case-control study. We recruited 200 patients with RSA (case group) using established diagnostic criteria and 200, normal individuals (control group) at the fertility and infertility center in Yazd city and Isfahan city during 2012 to 2013. We screened the I50V variant in IL-4R in patients and controls by PCR-RFLF method, and we performed an association analysis between I50V variant and RSA.the data was analyzed by spss 16 software using Chi-square test. No differences in the genotype and allele frequencies of the I50V SNPs were identified between patients with RSA and healthy controls. The frequency of SNP in IL-4 receptor (I50V) in patients with recurrent spontaneous abortion did not differ significantly compared with the control group. Analysis of IL4R SNP haplotypes or complex alleles suggested no dominant protection in patients with RSA.

20 CFR 255.18 - Compromise of overpayments.

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Compromise of overpayments. 255.18 Section 255.18 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT... standards which the Board applies in exercising its authority under 31 U.S.C. 3711 to compromise an...

Multiple roles of the extracellular vestibule amino acid residues in the function of the rat P2X4 receptor.

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Milos B Rokic

Full Text Available The binding of ATP to trimeric P2X receptors (P2XR causes an enlargement of the receptor extracellular vestibule, leading to opening of the cation-selective transmembrane pore, but specific roles of vestibule amino acid residues in receptor activation have not been evaluated systematically. In this study, alanine or cysteine scanning mutagenesis of V47-V61 and F324-N338 sequences of rat P2X4R revealed that V49, Y54, Q55, F324, and G325 mutants were poorly responsive to ATP and trafficking was only affected by the V49 mutation. The Y54F and Y54W mutations, but not the Y54L mutation, rescued receptor function, suggesting that an aromatic residue is important at this position. Furthermore, the Y54A and Y54C receptor function was partially rescued by ivermectin, a positive allosteric modulator of P2X4R, suggesting a rightward shift in the potency of ATP to activate P2X4R. The Q55T, Q55N, Q55E, and Q55K mutations resulted in non-responsive receptors and only the Q55E mutant was ivermectin-sensitive. The F324L, F324Y, and F324W mutations also rescued receptor function partially or completely, ivermectin action on channel gating was preserved in all mutants, and changes in ATP responsiveness correlated with the hydrophobicity and side chain volume of the substituent. The G325P mutant had a normal response to ATP, suggesting that G325 is a flexible hinge. A topological analysis revealed that the G325 and F324 residues disrupt a β-sheet upon ATP binding. These results indicate multiple roles of the extracellular vestibule amino acid residues in the P2X4R function: the V49 residue is important for receptor trafficking to plasma membrane, the Y54 and Q55 residues play a critical role in channel gating and the F324 and G325 residues are critical for vestibule widening.

Characterization of the transgenic CA-AhR mouse - cell specific expression of the CA-AhR using CYP1A1 as a marker

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Brunnberg, S.; Lindstam, M.; Andersson, P.; Hanberg, A. [Institute of Environmental Medicine, Stockholm (Sweden); Poellinger, L. [Department of Cell and Molecular Biology, Stockholm (Sweden)

2004-09-15

The risk assessments of dioxins and dioxin-like PCBs performed by WHO and EU lead to major concerns. The tolerable daily intake for humans has been assessed to be within the range of human exposures occurring in the general population today. Dioxins are known to adversely impair reproduction and affect development of reproductive organs, as well as the early development of the immune and the nervous systems. The Aryl hydrocarbon Receptor (AhR) mediates most toxic effects of dioxins, such as 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) and PCBs. In order to study the mechanisms of toxicity of ligands of the Ah receptor we have created a transgenic mouse model expressing a constitutively active Ah receptor (CA-AhR). The mutant Ah receptor is expressed and functionally active in most (or all) organs. Consequently, the CA-AhR mice show several of the well-known effects of dioxin exposure. Since the CA-AhR is continuously active at a relatively low level and from early development, this model resembles the human exposure scenario and is thus suitable for studies on mechanisms of action of Ah receptor ligands.

Overexpression of IGF-I receptor in HeLa cells enhances in vivo radioresponse

International Nuclear Information System (INIS)

Kaneko, Haruna; Yu, Dong; Miura, Masahiko

2007-01-01

Insulin-like growth factor I receptor (IGF-IR) is a transmembrane receptor tyrosine kinase whose activation strongly promotes cell growth and survival. We previously reported that IGF-IR activity confers intrinsic radioresistance in mouse embryo fibroblasts in vitro. However, it is still unclear whether tumor cells overexpressing IGF-IR exhibit radioresistance in vivo. For this purpose, we established HeLa cells that overexpress IGF-IR (HeLa-R), subcutaneously transplanted these cells into nude mice, and examined radioresponse in the resulting solid tumors. HeLa-R cells exhibited typical in vitro phenotypes generally observed in IGF-IR-overexpressing cells, as well as significant intrinsic radioresistance in vitro compared with parent cells. As expected, the transplanted HeLa-R tumors grew at a remarkably higher rate than parent tumors. Histological analysis revealed that HeLa-R tumors expressed more VEGF and had a higher density of tumor vessels. Unexpectedly, a marked growth delay was observed in HeLa-R tumors following 10 Gy of X-irradiation. Immunostaining of HeLa-R tumors for the hypoxia marker pimonidazole revealed a significantly lower level of hypoxic cells. Moreover, clamp hypoxia significantly increased radioresistance in HeLa-R tumors. Tumor microenvironments in vivo generated by the IGF-IR expression thus could be a major factor in determining the tumor radioresponse in vivo

mGluR1 receptors contribute to non-purinergic slow excitatory transmission to submucosal VIP neurons of guinea-pig ileum

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Jaime Pei Pei Foong

2009-05-01

Full Text Available Vasoactive intestinal peptide (VIP immunoreactive secretomotor neurons in the submucous plexus are involved in mediating bacterial toxin-induced hypersecretion leading to diarrhoea. VIP neurons become hyperexcitable after the mucosa is exposed to cholera toxin, which suggests that the manipulation of the excitability of these neurons may be therapeutic. This study used standard intracellular recording methods to systematically characterize slow excitatory postsynaptic potentials (EPSPs evoked in submucosal VIP neurons by different stimulus regimes (1, 3 and 15 pulse 30 Hz stimulation, together with their associated input resistances and pharmacology. All slow EPSPs were associated with a significant increase in input resistance compared to baseline values. Slow EPSPs evoked by a single stimulus were confirmed to be purinergic, however, slow EPSPs evoked by 15 pulse trains were non-purinergic and those evoked by 3 pulse trains were mixed. NK1 or NK3 receptor antagonists did not affect slow EPSPs. The group I mGluR receptor antagonist, PHCCC reduced the amplitude of purinergic and non-purinergic slow EPSPs. Blocking mGluR1 receptors depressed the overall response to 3 and 15 pulse trains, but this effect was inconsistent, while blockade of mGluR5 receptors had no effect on the non-purinergic slow EPSPs. Thus, although other receptors are almost certainly involved, our data indicate that there are at least two pharmacologically distinct types of slow EPSPs in the VIP secretomotor neurons: one mediated by P2Y receptors and the other in part by mGluR1 receptors.

Epilepsy, E/I balance and GABAA receptor plasticity

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Jean-Marc Fritschy

2008-03-01

Full Text Available GABAA receptors mediate most of the fast inhibitory transmission in the CNS. They form heteromeric complexes assembled from a large family of subunit genes. The existence of multiple GABAA receptor subtypes differing in subunit composition, localization and functional properties underlies their role for fi ne-tuning of neuronal circuits and genesis of network oscillations. The differential regulation of GABAA receptor subtypes represents a major facet of homeostatic synaptic plasticity and contributes to the excitation/inhibition (E/I balance under physiological conditions and upon pathological challenges. The purpose of this review is to discuss recent fi ndings highlighting the signifi cance of GABAA receptor heterogeneity for the concept of E/I balance and its relevance for epilepsy. Specifi cally, we address the following issues: (1 role for tonic inhibition, mediated by extrasynaptic GABAA receptors, for controlling neuronal excitability; (2 signifi cance of chloride ion transport for maintenance of the E/I balance in adult brain; and (3 molecular mechanisms underlying GABAA receptor regulation (traffi cking, posttranslational modifi cation, gene transcription that are important for homoeostatic plasticity. Finally, the relevance of these fi ndings is discussed in light of the involvement of GABAA receptors in epileptic disorders, based on recent experimental studies of temporal lobe epilepsy (TLE and absence seizures and on the identifi cation of mutations in GABAA receptor subunit genes underlying familial forms of epilepsy.

Isolation of αL I domain mutants mediating firm cell adhesion using a novel flow-based sorting method.

Science.gov (United States)

Pepper, Lauren R; Parthasarathy, Ranganath; Robbins, Gregory P; Dang, Nicholas N; Hammer, Daniel A; Boder, Eric T

2013-08-01

The inserted (I) domain of αLβ2 integrin (LFA-1) contains the entire binding site of the molecule. It mediates both rolling and firm adhesion of leukocytes at sites of inflammation depending on the activation state of the integrin. The affinity change of the entire integrin can be mimicked by the I domain alone through mutations that affect the conformation of the molecule. High-affinity mutants of the I domain have been discovered previously using both rational design and directed evolution. We have found that binding affinity fails to dictate the behavior of I domain adhesion under shear flow. In order to better understand I domain adhesion, we have developed a novel panning method to separate yeast expressing a library of I domain variants on the surface by adhesion under flow. Using conditions analogous to those experienced by cells interacting with the post-capillary vascular endothelium, we have identified mutations supporting firm adhesion that are not found using typical directed evolution techniques that select for tight binding to soluble ligands. Mutants isolated using this method do not cluster with those found by sorting with soluble ligand. Furthermore, these mutants mediate shear-driven cell rolling dynamics decorrelated from binding affinity, as previously observed for I domains bearing engineered disulfide bridges to stabilize activated conformational states. Characterization of these mutants supports a greater understanding of the structure-function relationship of the αL I domain, and of the relationship between applied force and bioadhesion in a broader context.

Sequential emergence and clinical implications of viral mutants with K70E and K65R mutation in reverse transcriptase during prolonged tenofovir monotherapy in rhesus macaques with chronic RT-SHIV infection

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Pedersen Niels C

2007-04-01

Full Text Available Abstract Background We reported previously on the emergence and clinical implications of simian immunodeficiency virus (SIVmac251 mutants with a K65R mutation in reverse transcriptase (RT, and the role of CD8+ cell-mediated immune responses in suppressing viremia during tenofovir therapy. Because of significant sequence differences between SIV and HIV-1 RT that affect drug susceptibilities and mutational patterns, it is unclear to what extent findings with SIV can be extrapolated to HIV-1 RT. Accordingly, to model HIV-1 RT responses, 12 macaques were inoculated with RT-SHIV, a chimeric SIV containing HIV-1 RT, and started on prolonged tenofovir therapy 5 months later. Results The early virologic response to tenofovir correlated with baseline viral RNA levels and expression of the MHC class I allele Mamu-A*01. For all animals, sensitive real-time PCR assays detected the transient emergence of K70E RT mutants within 4 weeks of therapy, which were then replaced by K65R mutants within 12 weeks of therapy. For most animals, the occurrence of these mutations preceded a partial rebound of plasma viremia to levels that remained on average 10-fold below baseline values. One animal eventually suppressed K65R viremia to undetectable levels for more than 4 years; sequential experiments using CD8+ cell depletion and tenofovir interruption demonstrated that both CD8+ cells and continued tenofovir therapy were required for sustained suppression of viremia. Conclusion This is the first evidence that tenofovir therapy can select directly for K70E viral mutants in vivo. The observations on the clinical implications of the K65R RT-SHIV mutants were consistent with those of SIVmac251, and suggest that for persons infected with K65R HIV-1 both immune-mediated and drug-dependent antiviral activities play a role in controlling viremia. These findings suggest also that even in the presence of K65R virus, continuation of tenofovir treatment as part of HAART may be

Métodos semiempíricos para la evaluación rápida de orbitales frontera en la clasificación de agonistas y antagonistas de la subunidad NR1 de los receptores iGluR-NMDA

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Juvenal Yosa-Reyes

2010-12-01

Full Text Available Los receptores iGluR-NMDAposeen gran interés farmacológico debido a que están implicadosen desordenes neurodegenerativos y neurosiquiátricos inclusoparticipan en procesos como plasticidad sináptica, esencial para la formación de la memoria. La subunidad NR1 de los iGluR-NMDA es fundamental para que éste tipo de receptores se activen apropiadamente, de hecho muchos de los fármacos estudiados paralos desordenes anteriormente mencionados, están dirigidos específicamente a la subunidad NR1. Estudios previos han determinado que el orbital molecular de más baja energía (LUMO, puede ser usado como parámetro para estimar la actividad agonista o antagonista en la subunidad NR1. Objetivo Evaluar el método semiempírico CNDO para el cálculo rápido de la energía LUMO, con la finalidad de crear un modelo sencillo para el diseño in silico de nuevos fármacos. Materiales y métodos. Fueron seleccionadas 168 moléculas entre agonistas y antagonistas de la subunidad NR1. La energía de cada estructura fue optimizada y posteriormente fueron calculadas las energías de los orbitales frontera, el LogP, la energía total, la capacidad de formar puentes de hidrógeno, la energía de unión y el momento dipolar. Resultados. Se demuestra quela energía LUMO es suficiente para discriminar entre moléculas agonistas y antagonistas de esta subunidad y que el método CNDO evalúa estas propiedades de manera rápida y eficiente, Conclusión. El método CNDO permite el cálculo rápido, generando a futuro procedimientos eficaces para la caracterización de fármacos potenciales que actúen sobre este sitio en particular.

Reversion of autocrine transformation by a dominant negative platelet-derived growth factor mutant.

Science.gov (United States)

Vassbotn, F S; Andersson, M; Westermark, B; Heldin, C H; Ostman, A

1993-07-01

A non-receptor-binding mutant of the platelet-derived growth factor (PDGF) A chain, PDGF-0, was generated by exchanging 7 amino acids in the sequence. The mutant chains formed dimers that were similar to wild-type PDGF-AA with regard to stability and rate of processing to the mature 30-kDa secreted forms. Moreover, the mutant chains formed disulfide-bonded heterodimers with the PDGF B chain in NIH 3T3 cells heterodimer underwent the same processing and secretion as PDGF-AB. Transfection of c-sis-expressing 3T3 cells with PDGF-0 significantly inhibited the transformed phenotype of these cells, as determined by the following criteria. (i) Compared with PDGF-0-negative clones, PDGF-0-producing clones showed a reverted morphology. (ii) Clones producing PDGF-0 grew more slowly than PDGF-0-negative clones, with a fivefold difference in cell number after 14 days in culture. (iii) The expression of PDGF-0 completely inhibited the ability of the c-sis-expressing 3T3 cells to form colonies in soft agar; this inhibition was overcome by the addition of recombinant PDGF-BB to the culture medium, showing that the lack of colony formation of these cells was not due to a general unresponsiveness to PDGF. The specific expression of a PDGF-0/PDGF wild-type heterodimer in COS cells revealed that the affinity of the mutant heterodimer for the PDGF alpha receptor was decreased by approximately 50-fold compared with that of PDGF-AA. Thus, we show that a non-receptor-binding PDGF A-chain mutant neutralizes in a trans-dominant manner the autocrine transforming potential of the c-sis/PDGF B chain by forming low-affinity heterodimers with wild-type PDGF chains. This method of specifically antagonizing the effect of PDGF may be useful in investigations of the role of PDGF in normal and pathological conditions.

Changing the insulin receptor to possess insulin-like growth factor I ligand specificity

International Nuclear Information System (INIS)

Andersen, A.S.; Kjeldsen, T.; Wiberg, F.C.; Christensen, P.M.; Rasmussen, J.S.; Norris, K.; Moeller, K.B.; Moeller, N.P.H.

1990-01-01

To examine the role of the N-terminal part of the insulin-like growth factor I (IGF-I) receptor and insulin receptor in determining ligand specificity, the authors prepared an expression vector encoding a hybrid receptor where exon 1 (encoding the signal peptide and seven amino acids of the α-subunit), exon 2, and exon 3 of the insulin receptor were replaced with the corresponding IGF-I receptor cDNA (938 nucleotides). To allow direct quantitative comparison of the binding capabilities of this hybrid receptor with those of the human IGF-I receptor and the insulin receptor, all three receptors were expressed in baby hamster kidney (BHK) cells as soluble molecules and partially purified before characterization. The hybrid IGF-I/insulin receptor bound IGF-I with an affinity comparable to that of the wild-type IGF-I receptor. In contrast, the hybrid receptor no longer displayed high-affinity binding of insulin. These results directly demonstrate that it is possible to change the specificity of the insulin receptor to that of the IGF-I receptor and, furthermore, that the binding specificity for IGF-I is encoded within the nucleotide sequence from 135 to 938 of the IGF-I receptor cDNA. Since the hybrid receptor only bound insulin with low affinity, the insulin binding region is likely to be located within exons 2 and 3 of the insulin receptor

Cellular androgen content influences enzalutamide agonism of F877L mutant androgen receptor

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Coleman, Daniel J.; Van Hook, Kathryn; King, Carly J.; Schwartzman, Jacob; Lisac, Robert; Urrutia, Joshua; Sehrawat, Archana; Woodward, Josha; Wang, Nicholas J.; Gulati, Roman; Thomas, George V.; Beer, Tomasz M.; Gleave, Martin; Korkola, James E.; Gao, Lina; Heiser, Laura M.; Alumkal, Joshi J.

2016-01-01

Prostate cancer is the most commonly diagnosed and second-most lethal cancer among men in the United States. The vast majority of prostate cancer deaths are due to castration-resistant prostate cancer (CRPC) – the lethal form of the disease that has progressed despite therapies that interfere with activation of androgen receptor (AR) signaling. One emergent resistance mechanism to medical castration is synthesis of intratumoral androgens that activate the AR. This insight led to the development of the AR antagonist enzalutamide. However, resistance to enzalutamide invariably develops, and disease progression is nearly universal. One mechanism of resistance to enzalutamide is an F877L mutation in the AR ligand-binding domain that can convert enzalutamide to an agonist of AR activity. However, mechanisms that contribute to the agonist switch had not been fully clarified, and there were no therapies to block AR F877L. Using cell line models of castration-resistant prostate cancer (CRPC), we determined that cellular androgen content influences enzalutamide agonism of mutant F877L AR. Further, enzalutamide treatment of AR F877L-expressing cell lines recapitulated the effects of androgen activation of F877L AR or wild-type AR. Because the BET bromodomain inhibitor JQ-1 was previously shown to block androgen activation of wild-type AR, we tested JQ-1 in AR F877L-expressing CRPC models. We determined that JQ-1 suppressed androgen or enzalutamide activation of mutant F877L AR and suppressed growth of mutant F877L AR CRPC tumors in vivo, demonstrating a new strategy to treat tumors harboring this mutation. PMID:27276681

IGF-I, IGF-II, and Insulin Stimulate Different Gene Expression Responses through Binding to the IGF-I Receptor

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Versteyhe, Soetkin; Klaproth, Birgit; Borup, Rehannah

2013-01-01

Insulin and the insulin-like growth factors (IGF)-I and -II are closely related peptides important for regulation of metabolism, growth, differentiation, and development. The IGFs exert their main effects through the IGF-I receptor. Although the insulin receptor is the main physiological receptor...... for insulin, this peptide hormone can also bind at higher concentrations to the IGF-I receptor and exert effects through it. We used microarray gene expression profiling to investigate the gene expression regulated by IGF-I, IGF-II, and insulin after stimulation of the IGF-I receptor. Fibroblasts from mice......, knockout for IGF-II and the IGF-II/cation-independent mannose-6-phosphate receptor, and expressing functional IGF-I but no insulin receptors, were stimulated for 4 h with equipotent saturating concentrations of insulin, IGF-I, and IGF-II. Each ligand specifically regulated a group of transcripts...

Phosphatidylinositol 3-Kinase (PI3K) Activity Bound to Insulin-like Growth Factor-I (IGF-I) Receptor, which Is Continuously Sustained by IGF-I Stimulation, Is Required for IGF-I-induced Cell Proliferation*

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Fukushima, Toshiaki; Nakamura, Yusaku; Yamanaka, Daisuke; Shibano, Takashi; Chida, Kazuhiro; Minami, Shiro; Asano, Tomoichiro; Hakuno, Fumihiko; Takahashi, Shin-Ichiro

2012-01-01

Continuous stimulation of cells with insulin-like growth factors (IGFs) in G1 phase is a well established requirement for IGF-induced cell proliferation; however, the molecular components of this prolonged signaling pathway that is essential for cell cycle progression from G1 to S phase are unclear. IGF-I activates IGF-I receptor (IGF-IR) tyrosine kinase, followed by phosphorylation of substrates such as insulin receptor substrates (IRS) leading to binding of signaling molecules containing SH2 domains, including phosphatidylinositol 3-kinase (PI3K) to IRS and activation of the downstream signaling pathways. In this study, we found prolonged (>9 h) association of PI3K with IGF-IR induced by IGF-I stimulation. PI3K activity was present in this complex in thyrocytes and fibroblasts, although tyrosine phosphorylation of IRS was not yet evident after 9 h of IGF-I stimulation. IGF-I withdrawal in mid-G1 phase impaired the association of PI3K with IGF-IR and suppressed DNA synthesis the same as when PI3K inhibitor was added. Furthermore, we demonstrated that Tyr1316-X-X-Met of IGF-IR functioned as a PI3K binding sequence when this tyrosine is phosphorylated. We then analyzed IGF signaling and proliferation of IGF-IR−/− fibroblasts expressing exogenous mutant IGF-IR in which Tyr1316 was substituted with Phe (Y1316F). In these cells, IGF-I stimulation induced tyrosine phosphorylation of IGF-IR and IRS-1/2, but mutated IGF-IR failed to bind PI3K and to induce maximal phosphorylation of GSK3β and cell proliferation in response to IGF-I. Based on these results, we concluded that PI3K activity bound to IGF-IR, which is continuously sustained by IGF-I stimulation, is required for IGF-I-induced cell proliferation. PMID:22767591

Genetics of Ustilago violacea. I. Carotenoid mutants and carotenogenesis

International Nuclear Information System (INIS)

Garber, E.D.; Baird, M.L.; Chapman, D.J.

1975-01-01

Wild-type strains of Ustilago violacea produce pink colonies on laboratory medium and yield white, orange, pumpkin, and yellow colonies after uv mutagenesis. The wild-type strains contain neurosporene and lycopene; one orange mutant, γ-carotene; and one yellow mutant, β-carotene. One white mutant had no detectable carotenoids. Diploid colonies heterozygous for wild type and orange, pumpkin, yellow, or white are phenotypically wild type. Diploid colonies heterozygous for yellow and orange are also phenotypically wild type. Diploid colonies heterozygous for white and orange; white and yellow; and white, yellow, and orange are phenotypically light orange, light yellow, and orange-yellow, respectively. The white mutants give a circular complementation map; the color mutants fit a linear complementation map. We propose a multienzyme of four identical dehydrogenases and one or two identical cyclases for carotenogenesis in this species. The white and color mutants represent structural mutations altering the conformation of the dehydrogenase or cyclase, respectively. Furthermore, cyclases may or may not aggregate in association with the dehydrogenase aggregate to form the multienzyme aggregate responsible for the color mutants

Role of the RIG-I-like receptors in antiviral response

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Agnieszka Jabłońska

2014-01-01

Full Text Available The innate nonspecific immunity is the first line of defense against viral infection. Toll-like receptors (TLRs and retinoic acid-inducible gene I (RIG-I-like receptors (RLRs are two main receptor families detecting viral nucleic acid. So far, three RLR family members were characterized: RIG-I, MDA5 and LGP2. RLR constitute a family of cytoplasmic helicases, which recognized intracellular single-stranded and double-stranded RNA that is introduced to cytosol during viral infection and replication. In this work we review the current knowledge about the mechanisms of viral recognition by RIG-I-like receptors and their signaling pathways for the activation of type I interferons and pro-inflammatory cytokines synthesis.

Type I and type II interferons upregulate functional type I interleukin-1 receptor in a human fibroblast cell line TIG-1.

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Takii, T; Niki, N; Yang, D; Kimura, H; Ito, A; Hayashi, H; Onozaki, K

1995-12-01

The regulation of type I interleukin-1 receptor (IL-1R) expression by type I, interferon (IFN)-alpha A/D, and type II IFN, IFN-gamma, in a human fibroblast cell line TIG-1 was investigated. After 2 h stimulation with human IFN-alpha A/D or IFN-gamma, the levels of type I IL-1R mRNA increased. We previously reported that IL-1 upregulates transcription and cell surface molecules of type I IL-1R in TIG-1 cells through induction of prostaglandin (PG) E2 and cAMP accumulation. However, indomethacin was unable to inhibit the effect of IFNs, indicating that IFNs augment IL-1R expression through a pathway distinct from that of IL-1. The augmentation was also observed in other fibroblast cell lines. Nuclear run-on assays and studies of the stability of mRNA suggested that the increase in IL-1R mRNA was a result of the enhanced transcription of IL-1R gene. Binding studies using 125I-IL-1 alpha revealed that the number of cell surface IL-1R increased with no change in binding affinity by treatment with these IFNs. Pretreatment of the cells with IFNs enhanced IL-1-induced IL-6 production, indicating that IFNs upregulate functional IL-1R. IL-1 and IFNs are produced by the same cell types, as well as by the adjacent different cell types, and are concomitantly present in lesions of immune and inflammatory reactions. These results therefore suggest that IFNs exhibit synergistic effects with IL-1 through upregulation of IL-1R. Augmented production of IL-6 may also contribute to the reactions.

Novel Functional Properties of Drosophila CNS Glutamate Receptors

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Li, Yan; Dharkar, Poorva; Han, Tae-Hee; Serpe, Mihaela; Lee, Chi-Hon; Mayer, Mark L.

2016-12-01

Phylogenetic analysis reveals AMPA, kainate, and NMDA receptor families in insect genomes, suggesting conserved functional properties corresponding to their vertebrate counterparts. However, heterologous expression of the Drosophila kainate receptor DKaiR1D and the AMPA receptor DGluR1A revealed novel ligand selectivity at odds with the classification used for vertebrate glutamate receptor ion channels (iGluRs). DKaiR1D forms a rapidly activating and desensitizing receptor that is inhibited by both NMDA and the NMDA receptor antagonist AP5; crystallization of the KaiR1D ligand-binding domain reveals that these ligands stabilize open cleft conformations, explaining their action as antagonists. Surprisingly, the AMPA receptor DGluR1A shows weak activation by its namesake agonist AMPA and also by quisqualate. Crystallization of the DGluR1A ligand-binding domain reveals amino acid exchanges that interfere with binding of these ligands. The unexpected ligand-binding profiles of insect iGluRs allows classical tools to be used in novel approaches for the study of synaptic regulation.

Group III mGlu receptor agonists potentiate the anticonvulsant effect of AMPA and NMDA receptor block.

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De Sarro, Giovambattista; Chimirri, Alba; Meldrum, Brian S

2002-09-06

We report the anticonvulsant action in DBA/2 mice of two mGlu Group III receptor agonists: (R,S)-4-phosphonophenylglycine, (R,S)-PPG, a compound with moderate mGlu8 selectivity, and of (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid, ACPT-1, a selective agonist for mGlu4alpha receptors. Both compounds, given intracerebroventricularly at doses which did not show marked anticonvulsant activity, produced a consistent shift to the left of the dose-response curves (i.e. enhanced the anticonvulsant properties) of 1-(4'-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-one hydrochloride, CFM-2, a noncompetitive AMPA receptor antagonist, and 3-((+/-)-2-carboxypiperazin-4-yl)-1-phosphonic acid, CPPene, a competitive NMDA receptor antagonist, in DBA/2 mice. In addition, (R,S)-PPG and ACPT-1 administered intracerebroventricularly prolonged the time course of the anticonvulsant properties of CFM-2 (33 micromol/kg, i.p.) and CPPene (3.3 micromol/kg, i.p.) administered intraperitoneally. We conclude that modest reduction of synaptic glutamate release by activation of Group III metabotropic receptors potentiates the anticonvulsant effect of AMPA and NMDA receptor blockade. Copyright 2002 Elsevier Science B.V.

Receptor Autoradiography Protocol for the Localized Visualization of Angiotensin II Receptors.

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Linares, Andrea; Couling, Leena E; Carrera, Eduardo J; Speth, Robert C

2016-06-07

This protocol describes receptor binding patterns for Angiotensin II (Ang II) in the rat brain using a radioligand specific for Ang II receptors to perform receptor autoradiographic mapping. Tissue specimens are harvested and stored at -80 °C. A cryostat is used to coronally section the tissue (brain) and thaw-mount the sections onto charged slides. The slide-mounted tissue sections are incubated in (125)I-SI-Ang II to radiolabel Ang II receptors. Adjacent slides are separated into two sets: 'non-specific binding' (NSP) in the presence of a receptor saturating concentration of non-radiolabeled Ang II, or an AT1 Ang II receptor subtype (AT1R) selective Ang II receptor antagonist, and 'total binding' with no AT1R antagonist. A saturating concentration of AT2 Ang II receptor subtype (AT2R) antagonist (PD123319, 10 µM) is also present in the incubation buffer to limit (125)I-SI-Ang II binding to the AT1R subtype. During a 30 min pre-incubation at ~22 °C, NSP slides are exposed to 10 µM PD123319 and losartan, while 'total binding' slides are exposed to 10 µM PD123319. Slides are then incubated with (125)I-SI-Ang II in the presence of PD123319 for 'total binding', and PD123319 and losartan for NSP in assay buffer, followed by several 'washes' in buffer, and water to remove salt and non-specifically bound radioligand. The slides are dried using blow-dryers, then exposed to autoradiography film using a specialized film and cassette. The film is developed and the images are scanned into a computer for visual and quantitative densitometry using a proprietary imaging system and a spreadsheet. An additional set of slides are thionin-stained for histological comparisons. The advantage of using receptor autoradiography is the ability to visualize Ang II receptors in situ, within a section of a tissue specimen, and anatomically identify the region of the tissue by comparing it to an adjacent histological reference section.

Genetic analyses of nonfluorescent root mutants induced by mutagenesis in soybean

International Nuclear Information System (INIS)

Sawada, S.; Palmer, R.G.

1987-01-01

Nonfluorescent root mutants in soybean [Glycine max (L.) Merr.] are useful as markers in genetic studies and in tissue culture research. Our objective was to obtain mutagen-induced nonfluorescent root mutants and to conduct genetic studies with them. Thirteen nonfluorescent mutants were detected among 154016 seedlings derived from soybean lines treated with six mutagens. One of these mutants, derived from Williams treated with 20 kR gamma rays, did not correspond to any of the known (standard) nonfluorescent spontaneous mutants. This is the first mutagen-induced nonfluorescent root mutant in soybean. It was assigned Genetic Type Collection no. T285 and the gene symbol fr5 fr5. The fr5 allele was not located on trisomics A, B, or C and was not linked to five chlorophyll-deficient mutants (y9, y11, y12, y13, and y20-k2) or flower color mutant w1. The remaining nonfluorescent root mutants were at the same loci as known spontaneous mutants; i.e., four had the fr1 allele, five had the fr2 allele, and three had the fr4 allele

Arabidopsis mutant sk156 reveals complex regulation of SPL15 in a miR156-controlled gene network

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Wei Shu

2012-09-01

Full Text Available Abstract Background The Arabidopsis microRNA156 (miR156 regulates 11 members of the SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL family by base pairing to complementary target mRNAs. Each SPL gene further regulates a set of other genes; thus, miR156 controls numerous genes through a complex gene regulation network. Increased axillary branching occurs in transgenic Arabidopsis overexpressing miR156b, similar to that observed in loss-of-function max3 and max4 mutants with lesions in carotenoid cleavage dioxygenases. Arabidopsis miR156b was found to enhance carotenoid levels and reproductive shoot branching when expressed in Brassica napus, suggesting a link between miR156b expression and carotenoid metabolism. However, details of the miR156 regulatory network of SPL genes related to carotenoid metabolism are not known. Results In this study, an Arabidopsis T-DNA enhancer mutant, sk156, was identified due to its altered branching and trichome morphology and increased seed carotenoid levels compared to wild type (WT ecovar Columbia. Enhanced miR156b expression due to the 35S enhancers present on the T-DNA insert was responsible for these phenotypes. Constitutive and leaf primodium-specific expression of a miR156-insensitive (mutated SPL15 (SPL15m largely restored WT seed carotenoid levels and plant morphology when expressed in sk156. The Arabidopsis native miR156-sensitive SPL15 (SPL15n and SPL15m driven by a native SPL15 promoter did not restore the WT phenotype in sk156. Our findings suggest that SPL15 function is somewhat redundant with other SPL family members, which collectively affect plant phenotypes. Moreover, substantially decreased miR156b transcript levels in sk156 expressing SPL15m, together with the presence of multiple repeats of SPL-binding GTAC core sequence close to the miR156b transcription start site, suggested feedback regulation of miR156b expression by SPL15. This was supported by the demonstration of specific in vitro

Restoration of tumor suppressor miR-34 inhibits human p53-mutant gastric cancer tumorspheres

International Nuclear Information System (INIS)

Ji, Qing; Hao, Xinbao; Meng, Yang; Zhang, Min; DeSano, Jeffrey; Fan, Daiming; Xu, Liang

2008-01-01

MicroRNAs (miRNAs), some of which function as oncogenes or tumor suppressor genes, are involved in carcinogenesis via regulating cell proliferation and/or cell death. MicroRNA miR-34 was recently found to be a direct target of p53, functioning downstream of the p53 pathway as a tumor suppressor. miR-34 targets Notch, HMGA2, and Bcl-2, genes involved in the self-renewal and survival of cancer stem cells. The role of miR-34 in gastric cancer has not been reported previously. In this study, we examined the effects of miR-34 restoration on p53-mutant human gastric cancer cells and potential target gene expression. Human gastric cancer cells were transfected with miR-34 mimics or infected with the lentiviral miR-34-MIF expression system, and validated by miR-34 reporter assay using Bcl-2 3'UTR reporter. Potential target gene expression was assessed by Western blot for proteins, and by quantitative real-time RT-PCR for mRNAs. The effects of miR-34 restoration were assessed by cell growth assay, cell cycle analysis, caspase-3 activation, and cytotoxicity assay, as well as by tumorsphere formation and growth. Human gastric cancer Kato III cells with miR-34 restoration reduced the expression of target genes Bcl-2, Notch, and HMGA2. Bcl-2 3'UTR reporter assay showed that the transfected miR-34s were functional and confirmed that Bcl-2 is a direct target of miR-34. Restoration of miR-34 chemosensitized Kato III cells with a high level of Bcl-2, but not MKN-45 cells with a low level of Bcl-2. miR-34 impaired cell growth, accumulated the cells in G1 phase, increased caspase-3 activation, and, more significantly, inhibited tumorsphere formation and growth. Our results demonstrate that in p53-deficient human gastric cancer cells, restoration of functional miR-34 inhibits cell growth and induces chemosensitization and apoptosis, indicating that miR-34 may restore p53 function. Restoration of miR-34 inhibits tumorsphere formation and growth, which is reported to be

Transcriptome changes associated wtih delayed flower senescence on transgenic petunia by inducing expression of etr1-1, a mutant ethylene receptor

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Flowers of ethylene-sensitive ornamental plants transformed with ethylene-insensitive 1-1(etr 1-1), a mutant ethylene receptor first isolated from Arabidopsis, are known to have longer shelf lives. We have generated petunia plants in which the etr 1-1 gene was over-expressed under the control of a c...

Assessment of cerebral benzodiazepine receptor distribution in anxiety disorders by 123I-iomazenil-SPECT. Comparison to cerebral perfusion scintigraphy by 123I-IMP

International Nuclear Information System (INIS)

Uchiyama, Mayuki; Sue, Hironari; Fukumitsu, Nobuyoshi; Mori, Yutaka; Kawakami, Kenji

1997-01-01

123 I-Iomazenil ( 123 I-IMZ) and 123 I-IMP imaging were performed in 5 patients with anxiety disorder (PAD) and 6 normal volunteers (NV). On 123 I-IMZ delayed imaging, the 2 PAD showed abnormally decreased findings. In anxiety disorder, decreased accumulation on 123 I-IMZ delayed images was seen in left hippocampus and parahippocampal gyrus in one patient, in right frontal and temporal lobe and left occipital pole in the other. Compared with NV, PAD had lower 123 I-IMZ uptake on delayed image in right upper and left lower frontal cortices, indicating the involvement of the benzodiazepine receptor complex in anxiety disorder. Compared with grading for anxiety disorder with Hamilton anxiety scale (HAS) and delayed to early count ratios of 123 I-IMZ, negative correlation (R 123 I-IMP image, positive correlation (R>0.7) was recognized in the hippocampus, the parahippocampal gyrus, the lower outer temporal cortex and the lower frontal cortex. (author)

Pårørende i psykiatrien

DEFF Research Database (Denmark)

Thomassen, Preben

Pårørende i psykiatrien: Formulerede visioner og pårørendeorganisationers ønsker og oplevelser i forhold til Regionernes politiske visioner med fokus på Region Midtjylland. Afrapportering fra projekt udført i VIAUC´s regi i Videncenter for Sundhedsfremme, Sundhedsteknologi og Rehabilitering under...

Structure-activity relationships of the melanocortin tetrapeptide Ac-His-DPhe-Arg-Trp-NH(2) at the mouse melanocortin receptors: part 2 modifications at the Phe position.

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Holder, Jerry Ryan; Bauzo, Rayna M; Xiang, Zhimin; Haskell-Luevano, Carrie

2002-07-04

The melanocortin pathway is an important participant in skin pigmentation, steroidogenesis, obesity, energy homeostasis and exocrine gland function. The centrally located melanocortin-3 and melanocortin-4 receptors (MC3R, MC4R) are involved in the metabolic and food intake aspects of energy homeostasis and are stimulated by melanocortin agonists such as alpha-melanocyte stimulation hormone (alpha-MSH). The melanocortin agonists contain the putative message sequence "His-Phe-Arg-Trp," and it has been well-documented that inversion of chirality of the Phe to DPhe results in a dramatic increase in melanocortin receptor potency. Herein, we report a tetrapeptide library, based upon the template Ac-His-DPhe-Arg-Trp-NH(2), consisting of 26 members that have been modified at the DPhe(7) position (alpha-MSH numbering) and pharmacologically characterized for agonist and antagonist activity at the mouse melanocortin receptors MC1R, MC3R, MC4R, and MC5R. The most notable results of this study include the identification of the tetrapeptide Ac-His-(pI)DPhe-Arg-Trp-NH(2) that is a full nanomolar agonist at the mMC1 and mMC5 receptors, a mMC3R partial agonist with potent antagonist activity (pA(2) = 7.25, K(i) = 56 nM) and, but unexpectedly, is a potent agonist at the mMC4R (EC(50) = 25 nM). This ligand possesses novel melanocortin receptor pharmacology, as compared to previously reported peptides, and is potentially useful for in vivo studies to differentiate MC3R vs MC4R physiological roles in animal models, such as primates, where "knockout" animals are not viable options. The DNal(2') substitution for DPhe resulted in a mMC3R partial agonist with antagonist activity (pA(2) = 6.5, K(i) = 295 nM) and a mMC4R (pA(2) = 7.8, K(i) = 17 nM) antagonist possessing 60- and 425-fold decreased potency, respectively, as compared with SHU9119 at these receptors. Examination of this DNal(2')-containing tetrapeptide at the F254S and F259S mutant mMC4Rs resulted in agonist activity of this m

A multiscale computational approach to dissect early events in the Erb family receptor mediated activation, differential signaling, and relevance to oncogenic transformations.

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Liu, Yingting; Purvis, Jeremy; Shih, Andrew; Weinstein, Joshua; Agrawal, Neeraj; Radhakrishnan, Ravi

2007-06-01

We describe a hierarchical multiscale computational approach based on molecular dynamics simulations, free energy-based molecular docking simulations, deterministic network-based kinetic modeling, and hybrid discrete/continuum stochastic dynamics protocols to study the dimer-mediated receptor activation characteristics of the Erb family receptors, specifically the epidermal growth factor receptor (EGFR). Through these modeling approaches, we are able to extend the prior modeling of EGF-mediated signal transduction by considering specific EGFR tyrosine kinase (EGFRTK) docking interactions mediated by differential binding and phosphorylation of different C-terminal peptide tyrosines on the RTK tail. By modeling signal flows through branching pathways of the EGFRTK resolved on a molecular basis, we are able to transcribe the effects of molecular alterations in the receptor (e.g., mutant forms of the receptor) to differing kinetic behavior and downstream signaling response. Our molecular dynamics simulations show that the drug sensitizing mutation (L834R) of EGFR stabilizes the active conformation to make the system constitutively active. Docking simulations show preferential characteristics (for wildtype vs. mutant receptors) in inhibitor binding as well as preferential enhancement of phosphorylation of particular substrate tyrosines over others. We find that in comparison to the wildtype system, the L834R mutant RTK preferentially binds the inhibitor erlotinib, as well as preferentially phosphorylates the substrate tyrosine Y1068 but not Y1173. We predict that these molecular level changes result in preferential activation of the Akt signaling pathway in comparison to the Erk signaling pathway for cells with normal EGFR expression. For cells with EGFR over expression, the mutant over activates both Erk and Akt pathways, in comparison to wildtype. These results are consistent with qualitative experimental measurements reported in the literature. We discuss these

Radiation induced mutants in cassava (Manihot esculenta Crantz)

International Nuclear Information System (INIS)

Nayar, G.G.; Rajendran, P.G.

1987-01-01

Full text: Stem cuttings and true seeds of three promising cultivars of cassava were exposed respectively to 1 to 5 kR and 10 to 50 kR acute gamma rays from a 60 Co source. Treatments of stem cuttings beyond 5 kR and seeds beyond 50 kR were lethal. One mutant each in the cultivars M4, H-165 and H-2304 was obtained from the stem irradiated populations. Another mutant was found in the seed irradiated progeny of H-2304. The mutant of M4 is characterised by light green (chlorina) leaves. The mutant of H-165 shows significantly shorter petiole (22,5 against 35.2 cm) and narrow leaf lobes, while the H-2304 mutant shows speckled leaves, branching and early flowering. The mutant found in the seed irradiated progeny of H-2304 is having yellow tuber flesh indicating the presence of carotene. The mutants may be useful in studies related to basic information as well as in practical breeding. The chlorina mutant in M4 showed slow growth and high HCN content in leaves. Late branching may be a useful trait in the traditionally non-branching clones of cassava to maintain the desirable leaf area index during high leaf fall period. Early flowering could be useful in a recombinant breeding programme. The tuber yield of the short petiole mutant in H-165 increased by 20% - 25% through closer planting. The narrow leaf lobes of this mutant permit better light penetration to lower leaves. (author)

Genetic Analysis Using Partial Sequencing of Melanocortin 4 Receptor (MC4R Gene in Bligon Goat

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Latifah Latifah

2017-08-01

Full Text Available Melanocortin 4 Receptor gene is involved in sympathetic nerve activity, adrenal and thyroid functions, and media for leptin in regulating energy balance and homeostasis. The aim of this research was to perform genetic analysis of MC4R gene sequences from Bligon goats. Fourty blood samples of Bligon does were used for DNA extraction. The primers were designed after alignment of 12 DNA sequences of MC4R gene from goat, sheep, and cattle. The primers were constructed on the Capra hircus MC4R gene sequence from GenBank (accession No. NM_001285591. Two DNA polymorphisms of MC4R were revealed in exon region (g.998 A/G and g.1079 C/T. The SNP g.998 A/G was a non-synonymous polymorphism i.e., changing of amino acid from methionine (Met to isoleucine (Ile. The SNP g.1079 C/T was a synonymous polymorphism. Restriction enzyme mapping on Bligon goat MC4R gene revealed three restriction enzymes (RsaI (GT’AC, Acc651 (G’GTAC_C, and KpnI (G_GTAC’C, which can recognize the SNP at g.1079 C/T. The restriction enzymes may be used for genotyping of the gene target using PCR-RFLP method in the future research.

Extracellular pH regulates zinc signaling via an Asp residue of the zinc-sensing receptor (ZnR/GPR39).

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Cohen, Limor; Asraf, Hila; Sekler, Israel; Hershfinkel, Michal

2012-09-28

Zinc activates a specific Zn(2+)-sensing receptor, ZnR/GPR39, and thereby triggers cellular signaling leading to epithelial cell proliferation and survival. Epithelial cells that express ZnR, particularly colonocytes, face frequent changes in extracellular pH that are of physiological and pathological implication. Here we show that the ZnR/GPR39-dependent Ca(2+) responses in HT29 colonocytes were maximal at pH 7.4 but were reduced by about 50% at pH 7.7 and by about 62% at pH 7.1 and were completely abolished at pH 6.5. Intracellular acidification did not attenuate ZnR/GPR39 activity, indicating that the pH sensor of this protein is located on an extracellular domain. ZnR/GPR39-dependent activation of extracellular-regulated kinase (ERK)1/2 or AKT pathways was abolished at acidic extracellular pH of 6.5. A similar inhibitory effect was monitored for the ZnR/GPR39-dependent up-regulation of Na(+)/H(+) exchange activity at pH 6.5. Focusing on residues putatively facing the extracellular domain, we sought to identify the pH sensor of ZnR/GPR39. Replacing the histidine residues forming the Zn(2+) binding site, His(17) or His(19), or other extracellular-facing histidines to alanine residues did not abolish the pH dependence of ZnR/GPR39. In contrast, replacing Asp(313) with alanine resulted in similar Ca(2+) responses triggered by ZnR/GPR39 at pH 7.4 or 6.5. This mutant also showed similar activation of ERK1/2 and AKT pathways, and ZnR-dependent up-regulation of Na(+)/H(+) exchange at pH 7.4 and pH 6.5. Substitution of Asp(313) to His or Glu residues restored pH sensitivity of the receptor. This indicates that Asp(313), which was shown to modulate Zn(2+) binding, is an essential residue of the pH sensor of GPR39. In conclusion, ZnR/GPR39 is tuned to sense physiologically relevant changes in extracellular pH that thus regulate ZnR-dependent signaling and ion transport activity.

Extracellular pH Regulates Zinc Signaling via an Asp Residue of the Zinc-sensing Receptor (ZnR/GPR39)*

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Cohen, Limor; Asraf, Hila; Sekler, Israel; Hershfinkel, Michal

2012-01-01

Zinc activates a specific Zn2+-sensing receptor, ZnR/GPR39, and thereby triggers cellular signaling leading to epithelial cell proliferation and survival. Epithelial cells that express ZnR, particularly colonocytes, face frequent changes in extracellular pH that are of physiological and pathological implication. Here we show that the ZnR/GPR39-dependent Ca2+ responses in HT29 colonocytes were maximal at pH 7.4 but were reduced by about 50% at pH 7.7 and by about 62% at pH 7.1 and were completely abolished at pH 6.5. Intracellular acidification did not attenuate ZnR/GPR39 activity, indicating that the pH sensor of this protein is located on an extracellular domain. ZnR/GPR39-dependent activation of extracellular-regulated kinase (ERK)1/2 or AKT pathways was abolished at acidic extracellular pH of 6.5. A similar inhibitory effect was monitored for the ZnR/GPR39-dependent up-regulation of Na+/H+ exchange activity at pH 6.5. Focusing on residues putatively facing the extracellular domain, we sought to identify the pH sensor of ZnR/GPR39. Replacing the histidine residues forming the Zn2+ binding site, His17 or His19, or other extracellular-facing histidines to alanine residues did not abolish the pH dependence of ZnR/GPR39. In contrast, replacing Asp313 with alanine resulted in similar Ca2+ responses triggered by ZnR/GPR39 at pH 7.4 or 6.5. This mutant also showed similar activation of ERK1/2 and AKT pathways, and ZnR-dependent up-regulation of Na+/H+ exchange at pH 7.4 and pH 6.5. Substitution of Asp313 to His or Glu residues restored pH sensitivity of the receptor. This indicates that Asp313, which was shown to modulate Zn2+ binding, is an essential residue of the pH sensor of GPR39. In conclusion, ZnR/GPR39 is tuned to sense physiologically relevant changes in extracellular pH that thus regulate ZnR-dependent signaling and ion transport activity. PMID:22879599

Differentiation of 5-hydroxytryptamine2 receptor subtypes using 125I-R-(-)2,5-dimethoxy-4-iodo-phenylisopropylamine and 3H-ketanserin

International Nuclear Information System (INIS)

McKenna, D.J.; Peroutka, S.J.

1989-01-01

The radioligand binding characteristics of 125I-R-(-)4-iodo-2,5-dimethoxyphenylisopropylamine [125I-R-(-)DOI] and 3H-ketanserin were compared in rat and bovine cortical membranes. In rat cortex, 125I-R-(-)DOI labels a relatively low density of binding sites (Bmax = 2.5 +/- 0.2 pmol/gm tissue) with high affinity (KD = 0.63 +/- 0.09 nM). In bovine cortex, specific binding of 125I-R-(-)DOI represents less than 20% of total binding at radioligand concentrations above 0.6 nM, and, therefore, the data cannot be analyzed adequately by Scatchard transformation. By contrast, 3H-ketanserin displays saturable, specific high-affinity binding in both rat cortex (KD = 1.0 +/- 0.1 nM; Bmax = 11 +/- 0.4 pmol/gm tissue) and bovine cortex (KD = 1.2 +/- 0.2 nM; Bmax = 5.3 +/- 0.4 pmol/gm tissue). Ki values for 30 drugs were determined for 125I-R-(-)DOI-labeled sites in rat cortex and 3H-ketanserin-labeled sites in bovine cortex. 5-Hydroxytryptamine (5-HT) displays 250-fold higher selectivity for the 125I-R-(-)DOI-labeled sites (Ki = 3.0 +/- 0.7 nM) than for the 3H-ketanserin-labeled sites (Ki = 750 +/- 50 nM). Structural congeners of R-(-)DOI display 80- to 160-fold higher affinity for the 125I-R-(-)DOI binding site than for the 3H-ketanserin-labeled binding site. d-LSD and putative 5-HT2 antagonists are approximately equipotent at both sites. Significant correlations were found between drug affinities for 125I-R-(-)DOI-labeled sites in rat cortex and putative 5-HT2A sites labeled previously by 77Br-R-(-)DOB (r = 0.93, p less than 0.01), putative 5-HT2B sites labeled by 3H-ketanserin in bovine cortex (r = 0.63, p less than 0.01), and 5-HT1C binding sites that have been characterized by other investigators (r = 0.78, p less than 0.01). No significant correlations were found between drug affinities for 125I-R-(-)DOI-labeled sites in rat cortex and 5-HT1A, 5-HT1B, 5-HT1D, or 5-HT3 sites, as determined by previous investigators

Differential binding of prohibitin-2 to estrogen receptor α and to drug-resistant ERα mutants

Energy Technology Data Exchange (ETDEWEB)

Chigira, Takeru, E-mail: 8120661875@mail.ecc.u-tokyo.ac.jp [Department of Chemistry and Biotechnology, School of Engineering, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639 (Japan); Nagatoishi, Satoru, E-mail: nagatoishi@bioeng.t.u-tokyo.ac.jp [Department of Bioengineering, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan); Tsumoto, Kouhei, E-mail: tsumoto@bioeng.t.u-tokyo.ac.jp [Department of Chemistry and Biotechnology, School of Engineering, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639 (Japan); Department of Bioengineering, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan)

2015-08-07

Endocrine resistance is one of the most challenging problems in estrogen receptor alpha (ERα)-positive breast cancer. The transcriptional activity of ERα is controlled by several coregulators, including prohibitin-2 (PHB2). Because of its ability to repress the transcriptional activity of activated ERα, PHB2 is a promising antiproliferative agent. In this study, were analyzed the interaction of PHB2 with ERα and three mutants (Y537S, D538G, and E380Q) that are frequently associated with a lack of sensitivity to hormonal treatments, to help advance novel drug discovery. PHB2 bound to ERα wild-type (WT), Y537S, and D538G, but did not bind to E380Q. The binding thermodynamics of Y537S and D538G to PHB2 were favorably altered entropically compared with those of WT to PHB2. Our results show that PHB2 binds to the ligand binding domain of ERα with a conformational change in the helix 12 of ERα. - Highlights: • Molten globule-likeness of an ERα repressor Prohibitin-2 (PHB2) is identified. • The thermodynamics is validated for the interaction between ERα and PHB2. • PHB2 binds to Y537S and D538G mutants of ERα commonly found in breast cancer. • ERα WT and mutants showed different thermodynamic parameters in the binding to PHB2. • ERα binds to PHB2 with conformational change involving packing of helix 12.

Characterizing the role of endothelin-1 in the progression of cardiac hypertrophy in aryl hydrocarbon receptor (AhR) null mice

International Nuclear Information System (INIS)

Lund, Amie K.; Goens, M. Beth; Nunez, Bethany A.; Walker, Mary K.

2006-01-01

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor characterized to play a role in detection and adaptation to environmental stimuli. Genetic deletion of AhR results in hypertension, and cardiac hypertrophy and fibrosis, associated with elevated plasma angiotensin II (Ang II) and endothelin-1 (ET-1), thus AhR appears to contribute to cardiovascular homeostasis. In these studies, we tested the hypothesis that ET-1 mediates cardiovascular pathology in AhR null mice via ET A receptor activation. First, we determine the time courses of cardiac hypertrophy, and of plasma and tissue ET-1 expression in AhR wildtype and null mice. AhR null mice exhibited increases in heart-to-body weight ratio and age-related expression of cardiac hypertrophy markers, β-myosin heavy chain (β-MHC), and atrial natriuretic factor (ANF), which were significant at 2 months. Similarly, plasma and tissue ET-1 expression was significantly elevated at 2 months and increased further with age. Second, AhR null mice were treated with ET A receptor antagonist, BQ-123 (100 nmol/kg/day), for 7, 28, or 58 days and blood pressure, cardiac fibrosis, and cardiac hypertrophy assessed, respectively. BQ-123 for 7 days significantly reduced mean arterial pressure in conscious, catheterized mice. BQ-123 for 28 days significantly reduced the histological appearance of cardiac fibrosis. Treatment for 58 days significantly reduced cardiac mass, assessed by heart weight, echocardiography, and β-MHC and ANF expression; and reduced cardiac fibrosis as determined by osteopontin and collagen I mRNA expression. These findings establish ET-1 and the ET A receptor as primary determinants of hypertension and cardiac pathology in AhR null mice

Receptors for insulin-like growth factors I and II: autoradiographic localization in rat brain and comparison to receptors for insulin

International Nuclear Information System (INIS)

Lesniak, M.A.; Hill, J.M.; Kiess, W.; Rojeski, M.; Pert, C.B.; Roth, J.

1988-01-01

Receptors for insulin-like growth factor I (IGF-I) in rat brain were visualized using autoradiography with [125I]IGF-I. The binding of the labeled peptide was competed for fully by high concentrations of unlabeled IGF-I. At intermediate concentrations of unlabeled peptide the binding of [125I]IGF-I was competed for by unlabeled IGF-I more effectively than by IGF-II or insulin, which is typical of receptors for IGF-I. Essentially every brain section shows specific binding of IGF-I, and the pattern of binding of IGF-I to its receptors correlated well with the cytoarchitectonic structures. In parallel studies we showed that [125I]IGF-II was bound to tissue sections of rat brain and that the binding was competed for by an excess of unlabeled IGF-II. However, intermediate concentrations of unlabeled peptides gave inconclusive results. To confirm that the binding of [125I]IGF-II was to IGF-II receptors, we showed that antibodies specific for the IGF-II receptor inhibited the binding of labeled IGF-II. Furthermore, the binding of the antibody to regions of the brain section, visualized by the application of [125I]protein-A, gave patterns indistinguishable from those obtained with [125I]IGF-II alone. Again, the binding was very widely distributed throughout the central nervous system, and the patterns of distribution corresponded well to the underlying neural structures. Densitometric analysis of the receptors enabled us to compare the distribution of IGF-I receptors with that of IGF-II receptors as well as retrospectively with that of insulin receptors

Mutante espontâneo de Bacillus licheniformis bloqueado no estágio I da esporogênese, possuidor de metabolismo respiratório aumentado A spontaneous mutant of Bacillus licheniformis with increased respiratory metabolism, blocked in stage I of sporogenesis

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Leon Rabinovitch

1976-01-01

Full Text Available Um mutante espontâneo de Bacillus licheniformis, derivado da amostra esporogênica 2390, foi estudado com vistas ao reconhecimento do estágio da evolução para esporo em que o mesmo se encontrava bloqueado. Eletronmicrografias sugeriram que as células desse mutante, colhidas durante a fase estacionária da curva de crescimento, não ultrapassaram o estágio I da esporogênese (i.e., permaneceram com o nucleóide disposto como filamento axial, enquanto a produção de antibiótico (bacitracina e a atividade proteolítica foram francamente detectadas. A linhagem mutante, designada Spolp-72, nas condições experimentais empregadas não biossintetizou esporos por estarvação em solução de sais inorgãnicos, mas evidenciou uma frequência de esporulação menor que 10*-7, após crescimento vegetativo em meio de cultura favorável á esporogênese. A amostra Spolp-72 externa um crescimento vegetativo inicial restringido, quando comparada com a amostra 2390, enquanto que, inversamente, sua atividade respiratória é significativamente mais elevada. Este último comportamento foi confirmado no presente trabalho, contrastando, nesse particular, com outros tipos de mutantes de esporulação já descritos, os quais se encontram bloqueados nos primeiros estágios da via esporogenética.A spontaneous mutant strain derived from the sporogenic B. licheniformis 2390 was studied with a view to determining at what developmental stage toward sporulation it was blocked. Electronmicrographs suggested that the mutant cells harvested during the stationary phase of the growth curve were unable to go beyond stage I of sporogenesis (i. e., their nucleoid remained as an axial filament. On the other hand, antibiotic production (bacitracin and proteolytic activity were easily detected. Under the present experimental conditions the mutant strain, named Spolp-72, did not synthesize spores by starvation in a solution of inorganic salts, in contrast with the parental

14 CFR 25.255 - Out-of-trim characteristics.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Out-of-trim characteristics. 25.255 Section 25.255 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT...-trim characteristics. (a) From an initial condition with the airplane trimmed at cruise speeds up to...

Expression and Purification of Functional Ligand-binding Domains of T1R3 Taste Receptors

Energy Technology Data Exchange (ETDEWEB)

Nie,Y.; Hobbs, J.; Vigues, S.; Olson, W.; Conn, G.; Munger, S.

2006-01-01

Chemosensory receptors, including odor, taste, and vomeronasal receptors, comprise the largest group of G protein-coupled receptors (GPCRs) in the mammalian genome. However, little is known about the molecular determinants that are critical for the detection and discrimination of ligands by most of these receptors. This dearth of understanding is due in part to difficulties in preparing functional receptors suitable for biochemical and biophysical analyses. Here we describe in detail two strategies for the expression and purification of the ligand-binding domain of T1R taste receptors, which are constituents of the sweet and umami taste receptors. These class C GPCRs contain a large extracellular N-terminal domain (NTD) that is the site of interaction with most ligands and that is amenable to expression as a separate polypeptide in heterologous cells. The NTD of mouse T1R3 was expressed as two distinct fusion proteins in Escherichia coli and purified by column chromatography. Spectroscopic analysis of the purified NTD proteins shows them to be properly folded and capable of binding ligands. This methodology should not only facilitate the characterization of T1R ligand interactions but may also be useful for dissecting the function of other class C GPCRs such as the large family of orphan V2R vomeronasal receptors.

Discovery of Mixed Pharmacology Melanocortin-3 Agonists and Melanocortin-4 Receptor Tetrapeptide Antagonist Compounds (TACOs) Based on the Sequence Ac-Xaa1-Arg-(pI)DPhe-Xaa4-NH2.

Science.gov (United States)

Doering, Skye R; Freeman, Katie T; Schnell, Sathya M; Haslach, Erica M; Dirain, Marvin; Debevec, Ginamarie; Geer, Phaedra; Santos, Radleigh G; Giulianotti, Marc A; Pinilla, Clemencia; Appel, Jon R; Speth, Robert C; Houghten, Richard A; Haskell-Luevano, Carrie

2017-05-25

The centrally expressed melanocortin-3 and -4 receptors (MC3R/MC4R) have been studied as possible targets for weight management therapies, with a preponderance of studies focusing on the MC4R. Herein, a novel tetrapeptide scaffold [Ac-Xaa 1 -Arg-(pI)DPhe-Xaa 4 -NH 2 ] is reported. The scaffold was derived from results obtained from a MC3R mixture-based positional scanning campaign. From these results, a set of 48 tetrapeptides were designed and pharmacologically characterized at the mouse melanocortin-1, -3, -4, and -5 receptors. This resulted in the serendipitous discovery of nine compounds that were MC3R agonists (EC 50 DPhe-Tic-NH 2 ], 1 [Ac-His-Arg-(pI)DPhe-Tic-NH 2 ], and 41 [Ac-Arg-Arg-(pI)DPhe-DNal(2')-NH 2 ] were more potent (EC 50 DPhe-Arg-Trp-NH 2 . This template contains a sequentially reversed "Arg-(pI)DPhe" motif with respect to the classical "Phe-Arg" melanocortin signaling motif, which results in pharmacology that is first-in-class for the central melanocortin receptors.

Cerebellar Expression of the Neurotrophin Receptor p75 in Naked-Ataxia Mutant Mouse

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Maryam Rahimi Balaei

2016-01-01

Full Text Available Spontaneous mutation in the lysosomal acid phosphatase 2 (Acp2 mouse (nax—naked-ataxia mutant mouse correlates with severe cerebellar defects including ataxia, reduced size and abnormal lobulation as well as Purkinje cell (Pc degeneration. Loss of Pcs in the nax cerebellum is compartmentalized and harmonized to the classic pattern of gene expression of the cerebellum in the wild type mouse. Usually, degeneration starts in the anterior and posterior zones and continues to the central and nodular zones of cerebellum. Studies have suggested that the p75 neurotrophin receptor (NTR plays a role in Pc degeneration; thus, in this study, we investigated the p75NTR pattern and protein expression in the cerebellum of the nax mutant mouse. Despite massive Pc degeneration that was observed in the nax mouse cerebellum, p75NTR pattern expression was similar to the HSP25 pattern in nax mice and comparable with wild type sibling cerebellum. In addition, immunoblot analysis of p75NTR protein expression did not show any significant difference between nax and wild type sibling (p > 0.5. In comparison with wild type counterparts, p75NTR pattern expression is aligned with the fundamental cytoarchitecture organization of the cerebellum and is unchanged in the nax mouse cerebellum despite the severe neurodevelopmental disorder accompanied with Pc degeneration.

Functional rescue of mutant ABCA1 proteins by sodium 4-phenylbutyrate.

Science.gov (United States)

Sorrenson, Brie; Suetani, Rachel J; Williams, Michael J A; Bickley, Vivienne M; George, Peter M; Jones, Gregory T; McCormick, Sally P A

2013-01-01

Mutations in the ATP-binding cassette transporter A1 (ABCA1) are a major cause of decreased HDL cholesterol (HDL-C), which infers an increased risk of cardiovascular disease (CVD). Many ABCA1 mutants show impaired localization to the plasma membrane. The aim of this study was to investigate whether the chemical chaperone, sodium 4-phenylbutyrate (4-PBA) could improve cellular localization and function of ABCA1 mutants. Nine different ABCA1 mutants (p.A594T, p.I659V, p.R1068H, p.T1512M, p.Y1767D, p.N1800H, p.R2004K, p.A2028V, p.Q2239N) expressed in HEK293 cells, displaying different degrees of mislocalization to the plasma membrane and discrete impacts on cholesterol efflux, were subject to treatment with 4-PBA. Treatment restored localization to the plasma membrane and increased cholesterol efflux function for the majority of mutants. Treatment with 4-PBA also increased ABCA1 protein expression in all transfected cell lines. In fibroblast cells obtained from low HDL-C subjects expressing two of the ABCA1 mutants (p.R1068H and p.N1800H), 4-PBA increased cholesterol efflux without any increase in ABCA1 expression. Our study is the first to investigate the effect of the chemical chaperone, 4-PBA on ABCA1 and shows that it is capable of restoring plasma membrane localization and enhancing the cholesterol efflux function of mutant ABCA1s both in vitro and ex vivo. These results suggest 4-PBA may warrant further investigation as a potential therapy for increasing cholesterol efflux and HDL-C levels.

Importance of constitutive activity and arrestin-independent mechanisms for intracellular trafficking of the ghrelin receptor

DEFF Research Database (Denmark)

Holliday, Nicholas D; Holst, Birgitte; Rodionova, Elena A

2007-01-01

. Furthermore the interaction between phosphorylated receptors and beta-arrestin adaptor proteins has been examined. Replacement of the FLAG-tagged GhrelinR C tail with the equivalent GPR39 domain (GhR-39 chimera) preserved G(q) signaling. However in contrast to the GhrelinR, GhR-39 receptors exhibited no basal......,9), Leu(11)] substance P and a naturally occurring mutant GhrelinR (A204E) with eliminated constitutive activity inhibited basal GhrelinR internalization. Surprisingly, we found that noninternalizing GPR39 was highly phosphorylated and that basal and agonist-induced phosphorylation of the GhR-39 chimera......, but the high levels of GPR39 phosphorylation, and of the GhR-39 chimera, are not sufficient to drive endocytosis. In addition, basal GhrelinR internalization occurs independently of beta-arrestins....

Phenotypic and epistatic grouping of hypo- and hyper-rec mus mutants in Aspergillus.

Science.gov (United States)

Kafer, E; Chae, S K

1994-03-01

The mutants musK to musS of Aspergillus nidulans are sensitive to methyl-methanesulfonate (MMS) and several of them are meiotic-defective and alter mitotic recombination frequencies. All were found to be cross-sensitive to 4-nitro-quinoline-N-oxide (4-NQO) but unexpectedly none of them was hypersensitive to gamma-rays and few to UV light. Double mus; uvs mutants were constructed to test for interactions with uvs mutations of the four epistatic groups of Aspergillus, "UvsF", "UvsC", "UvsI", and "UvsB". All meiotic-defective mus mutations caused some lethal interactions, usually with uvsF. None of them showed epistasis with UvsF or UvsB group mutants and one, musO, may represent a new group. Three mus mutations that affect recombination were assigned to the UvsC group, namely musN and K, and also musL which is recombination-defective and closely resembles uvsC. While uvsC mutants are mutators and lack UV-mutagenesis, most mus mutants had no effects on mutation. Only musR, which appeared epistatic with uvsI, showed reduced UV-reversion frequencies similar to uvsI. The recombination-proficient mus mutants appeared to be epistatic with more than one group, but in several cases sensitivities were slight and overlaps insufficient to obtain corroborating results with MMS and 4-NQO.

Covalent modification of mutant rat P2X2 receptors with a thiol-reactive fluorophore allows channel activation by zinc or acidic pH without ATP.

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Shlomo S Dellal

Full Text Available Rat P2X2 receptors open at an undetectably low rate in the absence of ATP. Furthermore, two allosteric modulators, zinc and acidic pH, cannot by themselves open these channels. We describe here the properties of a mutant receptor, K69C, before and after treatment with the thiol-reactive fluorophore Alexa Fluor 546 C(5-maleimide (AM546. Xenopus oocytes expressing unmodified K69C were not activated under basal conditions nor by 1,000 µM ATP. AM546 treatment caused a small increase in the inward holding current which persisted on washout and control experiments demonstrated this current was due to ATP independent opening of the channels. Following AM546 treatment, zinc (100 µM or acidic external solution (pH 6.5 elicited inward currents when applied without any exogenous ATP. In the double mutant K69C/H319K, zinc elicited much larger inward currents, while acidic pH generated outward currents. Suramin, which is an antagonist of wild type receptors, behaved as an agonist at AM546-treated K69C receptors. Several other cysteine-reactive fluorophores tested on K69C did not cause these changes. These modified receptors show promise as a tool for studying the mechanisms of P2X receptor activation.

Estimates of regional cerebral blood flow and 5-HT2A receptor density in impulsive, aggressive dogs with 99mTc-ECD and 123I-5-I-R91150

International Nuclear Information System (INIS)

Peremans, Kathelijne; Coopman, Frank; Verschooten, Francis; Bree, Henri van; Audenaert, Kurt; Heeringen, Kees van; Blanckaert, Peter; Slegers, Guido; Jacobs, Filip; Otte, Andreas; Dierckx, Rudi; Mertens, John

2003-01-01

Impulsive aggression in dogs has an important impact on human public health. Better insight into the pathophysiology of this phenomenon could lead to more adequate diagnosis and treatment. Indirect in vivo research on peripheral body fluids and post-mortem studies in impulsive animals and humans indicate a deficient serotonergic system in general and disturbances in the serotonin-2A (5-HT2A) receptor in particular. In this study, brain perfusion and the 5-HT2A receptors were examined in impulsive, aggressive dogs, in comparison with a group of normally behaving animals. In order to decide which dogs to include in this study, owners were asked to describe the general behaviour of the dogs, the circumstances in which aggression occurred and their conduct during aggressive acts. Finally, 19 dogs were retained for this study, showing, according to different behavioural specialists, disinhibited dominance aggression. Functional imaging studies were performed on all these dogs. Single-photon emission tomography (SPET) was used to measure regional brain perfusion using technetium-99m labelled ethyl cysteinate dimer (ECD). The 5-HT2A receptor binding properties were investigated using the selective radioligand iodine-123 labelled 5-I-R91150. A significant increase in uptake of the 5-HT2A radioligand was noted in all cortical areas. No significant alterations were found in regional cortical perfusion, indicating that the increased binding index was not a consequence of increased tracer delivery. This study supports a role for the serotonergic system in canine impulsive aggression. (orig.)

40 CFR 52.255 - Gasoline transfer vapor control.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Gasoline transfer vapor control. 52.255... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS California § 52.255 Gasoline transfer vapor control. (a) “Gasoline” means any petroleum distillate having a Reid vapor pressure of 4 pounds or greater...

Angiotensin II reduces cardiac AdipoR1 expression through AT1 receptor/ROS/ERK1/2/c-Myc pathway.

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Li Li

Full Text Available Adiponectin, an abundant adipose tissue-derived protein, exerts protective effect against cardiovascular disease. Adiponectin receptors (AdipoR1 and AdipoR2 mediate the beneficial effects of adiponectin on the cardiovascular system. However, the alteration of AdipoRs in cardiac remodeling is not fully elucidated. Here, we investigated the effect of angiotensin II (AngII on cardiac AdipoRs expression and explored the possible molecular mechanism. AngII infusion into rats induced cardiac hypertrophy, reduced AdipoR1 but not AdipoR2 expression, and attenuated the phosphorylations of adenosine monophosphate-activated protein kinase and acetyl coenzyme A carboxylase, and those effects were all reversed by losartan, an AngII type 1 (AT1 receptor blocker. AngII reduced expression of AdipoR1 mRNA and protein in cultured neonatal rat cardiomyocytes, which was abolished by losartan, but not by PD123319, an AT2 receptor antagonist. The antioxidants including reactive oxygen species (ROS scavenger NAC, NADPH oxidase inhibitor apocynin, Nox2 inhibitor peptide gp91 ds-tat, and mitochondrial electron transport chain complex I inhibitor rotenone attenuated AngII-induced production of ROS and phosphorylation of extracellular signal-regulated kinase (ERK 1/2. AngII-reduced AdipoR1 expression was reversed by pretreatment with NAC, apocynin, gp91 ds-tat, rotenone, and an ERK1/2 inhibitor PD98059. Chromatin immunoprecipitation assay demonstrated that AngII provoked the recruitment of c-Myc onto the promoter region of AdipoR1, which was attenuated by PD98059. Moreover, AngII-induced DNA binding activity of c-Myc was inhibited by losartan, NAC, apocynin, gp91 ds-tat, rotenone, and PD98059. c-Myc small interfering RNA abolished the inhibitory effect of AngII on AdipoR1 expression. Our results suggest that AngII inhibits cardiac AdipoR1 expression in vivo and in vitro and AT1 receptor/ROS/ERK1/2/c-Myc pathway is required for the downregulation of AdipoR1 induced by AngII.

Identification of the RsmG methyltransferase target as 16S rRNA nucleotide G527 and characterization of Bacillus subtilis rsmG mutants

DEFF Research Database (Denmark)

Nishimura, Kenji; Johansen, Shanna K; Inaoka, Takashi

2007-01-01

The methyltransferase RsmG methylates the N7 position of nucleotide G535 in 16S rRNA of Bacillus subtilis (corresponding to G527 in Escherichia coli). Disruption of rsmG resulted in low-level resistance to streptomycin. A growth competition assay revealed that there are no differences in fitness...... between the rsmG mutant and parent strains under the various culture conditions examined. B. subtilis rsmG mutants emerged spontaneously at a relatively high frequency, 10(-6). Importantly, in the rsmG mutant background, high-level-streptomycin-resistant rpsL (encoding ribosomal protein S12) mutants...

The Arabidopsis thaliana lectin receptor kinase LecRK-I.9 is required for full resistance to Pseudomonas syringae and affects jasmonate signalling.

Science.gov (United States)

Balagué, Claudine; Gouget, Anne; Bouchez, Olivier; Souriac, Camille; Haget, Nathalie; Boutet-Mercey, Stéphanie; Govers, Francine; Roby, Dominique; Canut, Hervé

2017-09-01

On microbial attack, plants can detect invaders and activate plant innate immunity. For the detection of pathogen molecules or cell wall damage, plants employ receptors that trigger the activation of defence responses. Cell surface proteins that belong to large families of lectin receptor kinases are candidates to function as immune receptors. Here, the function of LecRK-I.9 (At5g60300), a legume-type lectin receptor kinase involved in cell wall-plasma membrane contacts and in extracellular ATP (eATP) perception, was studied through biochemical, gene expression and reverse genetics approaches. In Arabidopsis thaliana, LecRK-I.9 expression is rapidly, highly and locally induced on inoculation with avirulent strains of Pseudomonas syringae pv. tomato (Pst). Two allelic lecrk-I.9 knock-out mutants showed decreased resistance to Pst. Conversely, over-expression of LecRK-I.9 led to increased resistance to Pst. The analysis of defence gene expression suggests an alteration of both the salicylic acid (SA) and jasmonic acid (JA) signalling pathways. In particular, LecRK-I.9 expression during plant-pathogen interaction was dependent on COI1 (CORONATINE INSENSITIVE 1) and JAR1 (JASMONATE RESISTANT 1) components, and JA-responsive transcription factors (TFs) showed altered levels of expression in plants over-expressing LecRK-I.9. A similar misregulation of these TFs was obtained by JA treatment. This study identified LecRK-I.9 as necessary for full resistance to Pst and demonstrated its involvement in the control of defence against pathogens through a regulation of JA signalling components. The role of LecRK-I.9 is discussed with regard to the potential molecular mechanisms linking JA signalling to cell wall damage and/or eATP perception. © 2016 BSPP AND JOHN WILEY & SONS LTD.

miR-155 Controls Lymphoproliferation in LAT Mutant Mice by Restraining T-Cell Apoptosis via SHIP-1/mTOR and PAK1/FOXO3/BIM Pathways.

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Alexandre K Rouquette-Jazdanian

Full Text Available Linker for Activation of T cells (LAT is an adapter protein that is essential for T cell function. Knock-in mice with a LAT mutation impairing calcium flux develop a fatal CD4+ lymphoproliferative disease. miR-155 is a microRNA that is correlated with hyperproliferation in a number of cancers including lymphomas and leukemias and is overexpressed in mutant LAT T cells. To test whether miR-155 was merely indicative of T cell activation or whether it contributes to lymphoproliferative disease in mutant LAT mice, we interbred LAT mutant and miR-155-deficient mice. miR-155 deficiency markedly inhibited lymphoproliferative disease by stimulating BIM-dependent CD4+ T cell apoptosis, even though ERK activation and T cell proliferation were increased in double mutant CD4+ T cells. Bim/Bcl2l11 expression is activated by the forkhead transcription factor FOXO3. Using miR-155-deficient, LAT mutant T cells as a discovery tool, we found two connected pathways that impact the nuclear translocation and activation of FOXO3 in T cells. One pathway is mediated by the inositide phosphatase SHIP-1 and the serine/threonine kinases AKT and PDK1. The other pathway involves PAK1 and JNK kinase activation. We define crosstalk between the two pathways via the kinase mTOR, which stabilizes PAK1. This study establishes a role for PAK1 in T cell apoptosis, which contrasts to its previously identified role in T cell proliferation. Furthermore, miR-155 regulates the delicate balance between PAK1-mediated proliferation and apoptosis in T cells impacting lymphoid organ size and function.

Effects of the brain-penetrant and selective 5-HT6 receptor antagonist SB-399885 in animal models of anxiety and depression.

Science.gov (United States)

Wesołowska, Anna; Nikiforuk, Agnieszka

2007-04-01

The effects of a selective 5-HT(6) receptor antagonist, SB-399885 (N-[3,5-dichloro-2-(methoxy)phenyl]-4-(methoxy)-3-(1-piperazinyl)benzenesulfonamide), were evaluated in behavioural tests sensitive to clinically effective anxiolytic- and antidepressant-compounds using diazepam and imipramine as reference drugs. In the Vogel conflict drinking test in rats, SB-399885 (1-3mg/kg i.p.) caused an anxiolytic-like activity comparable to that of diazepam (2.5-5mg/kg i.p.). An anxiolytic-like effect was also seen in the elevated plus-maze test in rats, where SB-399885 (0.3-3mg/kg i.p.) was slightly weaker than diazepam (2.5-5mg/kg i.p.). In the four-plate test in mice, SB-399885 (3-20mg/kg i.p.) showed an anxiolytic-like effect which was weaker than that produced by diazepam (2.5-5mg/kg i.p.). In the forced swim test in rats, SB-399885 (10mg/kg i.p.) significantly shortened the immobility time and the effect was stronger than that of imipramine (30mg/kg i.p.). In the forced swim test in mice, SB-399885 (20-30mg/kg i.p.) had an anti-immobility action, comparable to imipramine (30mg/kg i.p.) and also in the tail suspension test in mice, SB-399885 (10-30mg/kg i.p.) had an antidepressant-like effect, though was weaker than imipramine (10-20mg/kg i.p.). The tested 5-HT(6) antagonist (3-20mg/kg i.p.) shortened the walking time of rats in the open field test and, at a dose of 30mg/kg i.p. reduced the locomotor activity of mice. SB-399885 (in doses up to 30mg/kg i.p.) did not affect motor coordination in mice and rats tested in the rota-rod test. Such data indicate that the selective 5-HT(6) receptor antagonist SB-399885had specific effects, indicative of this compound's anxiolytic and antidepressant potential.

Pollen irradiation method to obtain mutants in cucumber

International Nuclear Information System (INIS)

Iida, S.; Amano, E.

1988-01-01

Seed irradiation for mutation induction in dioecious crops like cucumber is not very useful because chimerism of the mutated tissues makes the segregation of mutants in the M 2 generation nearly impossible. This problem does not exist with pollen irradiation. Cucumber (Cucumis sativus L. var. Nishikisuyo) was used for a model experiment. The petals of male and female flowers were closed by pinching with binding wire before flowering to prevent pollination by insects. On the flowering day, the male flowers were collected and irradiated with 1kR to 10 kR of acute gamma rays (137-Cs), then used to pollinate the female flowers. The M 1 seeds thus obtained are not chimeric but heterozygous for induced mutations. When planted, no mutant phenotype appeared. Selfing within a plant lead to segregation of mutants in the M 2 generation. Seedling examination revealed eight mutants. One mutant line, in which the shape of leaves changed from pentagonal to round heart shape, was found under field conditions. The optimal dose for pollen irradiation seems to be between 2 kR and 4kR

Molecular Basis of Natural Killer Cell Tumor Target Recognition: The NKr/MHC Class I Complex

National Research Council Canada - National Science Library

Hasemann, Charles

1999-01-01

.... We have pursued this via the heterologous expression of wild type and mutant NK receptors for the purpose of the determination of the atomic structure of an NK receptor/ class I MHC complex via X-ray crystallography...

Compensatory insulin receptor (IR) activation on inhibition of insulin-like growth factor-1 receptor (IGF-1R): rationale for cotargeting IGF-1R and IR in cancer.

Science.gov (United States)

Buck, Elizabeth; Gokhale, Prafulla C; Koujak, Susan; Brown, Eric; Eyzaguirre, Alexandra; Tao, Nianjun; Rosenfeld-Franklin, Maryland; Lerner, Lorena; Chiu, M Isabel; Wild, Robert; Epstein, David; Pachter, Jonathan A; Miglarese, Mark R

2010-10-01

Insulin-like growth factor-1 receptor (IGF-1R) is a receptor tyrosine kinase (RTK) and critical activator of the phosphatidylinositol 3-kinase-AKT pathway. IGF-1R is required for oncogenic transformation and tumorigenesis. These observations have spurred anticancer drug discovery and development efforts for both biological and small-molecule IGF-1R inhibitors. The ability for one RTK to compensate for another to maintain tumor cell viability is emerging as a common resistance mechanism to antitumor agents targeting individual RTKs. As IGF-1R is structurally and functionally related to the insulin receptor (IR), we asked whether IR is tumorigenic and whether IR-AKT signaling contributes to resistance to IGF-1R inhibition. Both IGF-1R and IR(A) are tumorigenic in a mouse mammary tumor model. In human tumor cells coexpressing IGF-1R and IR, bidirectional cross talk was observed following either knockdown of IR expression or treatment with a selective anti-IGF-1R antibody, MAB391. MAB391 treatment resulted in a compensatory increase in phospho-IR, which was associated with resistance to inhibition of IRS1 and AKT. In contrast, treatment with OSI-906, a small-molecule dual inhibitor of IGF-1R/IR, resulted in enhanced reduction in phospho-IRS1/phospho-AKT relative to MAB391. Insulin or IGF-2 activated the IR-AKT pathway and decreased sensitivity to MAB391 but not to OSI-906. In tumor cells with an autocrine IGF-2 loop, both OSI-906 and an anti-IGF-2 antibody reduced phospho-IR/phospho-AKT, whereas MAB391 was ineffective. Finally, OSI-906 showed superior efficacy compared with MAB391 in human tumor xenograft models in which both IGF-1R and IR were phosphorylated. Collectively, these data indicate that cotargeting IGF-1R and IR may provide superior antitumor efficacy compared with targeting IGF-1R alone.

Group I Metabotropic Glutamate Receptors

DEFF Research Database (Denmark)

Erichsen, Julie Ladeby; Blaabjerg, Morten; Bogetofte Thomasen, Helle

2015-01-01

differentiated an immortalized, forebrain-derived stem cell line in the presence or absence of glutamate and with addition of either the group I mGluR agonist DHPG or the selective antagonists; MPEP (mGluR5) and LY367385 (mGluR1). Characterization of differentiated cells revealed that both mGluR1 and mGluR5 were...

Rent vand i 150 år

DEFF Research Database (Denmark)

Arvin, Erik

2003-01-01

Vandforsyningen i Odense har været en succes siden begyndelsen i 1853. Ny gælder det om at fastholde landvindingerne, og det bør bl.a. ske ved at bevare det fynske selveje i stedet for at kaste sig i armene på en storkoncern.......Vandforsyningen i Odense har været en succes siden begyndelsen i 1853. Ny gælder det om at fastholde landvindingerne, og det bør bl.a. ske ved at bevare det fynske selveje i stedet for at kaste sig i armene på en storkoncern....

Identification of a negative regulatory region for the exchange activity and characterization of T332I mutant of Rho guanine nucleotide exchange factor 10 (ARHGEF10).

Science.gov (United States)

Chaya, Taro; Shibata, Satoshi; Tokuhara, Yasunori; Yamaguchi, Wataru; Matsumoto, Hiroshi; Kawahara, Ichiro; Kogo, Mikihiko; Ohoka, Yoshiharu; Inagaki, Shinobu

2011-08-26

The T332I mutation in Rho guanine nucleotide exchange factor 10 (ARHGEF10) was previously found in persons with slowed nerve conduction velocities and thin myelination of peripheral nerves. However, the molecular and cellular basis of the T332I mutant is not understood. Here, we show that ARHGEF10 has a negative regulatory region in the N terminus, in which residue 332 is located, and the T332I mutant is constitutively active. An N-terminal truncated ARHGEF10 mutant, ARHGEF10 ΔN (lacking amino acids 1-332), induced cell contraction that was inhibited by a Rho kinase inhibitor Y27632 and had higher GEF activity for RhoA than the wild type. The T332I mutant also showed the phenotype similar to the N-terminal truncated mutant. These data suggest that the ARHGEF10 T332I mutation-associated phenotype observed in the peripheral nerves is due to activated GEF activity of the ARHGEF10 T332I mutant.

Identification of a Negative Regulatory Region for the Exchange Activity and Characterization of T332I Mutant of Rho Guanine Nucleotide Exchange Factor 10 (ARHGEF10)*

Science.gov (United States)

Chaya, Taro; Shibata, Satoshi; Tokuhara, Yasunori; Yamaguchi, Wataru; Matsumoto, Hiroshi; Kawahara, Ichiro; Kogo, Mikihiko; Ohoka, Yoshiharu; Inagaki, Shinobu

2011-01-01

The T332I mutation in Rho guanine nucleotide exchange factor 10 (ARHGEF10) was previously found in persons with slowed nerve conduction velocities and thin myelination of peripheral nerves. However, the molecular and cellular basis of the T332I mutant is not understood. Here, we show that ARHGEF10 has a negative regulatory region in the N terminus, in which residue 332 is located, and the T332I mutant is constitutively active. An N-terminal truncated ARHGEF10 mutant, ARHGEF10 ΔN (lacking amino acids 1–332), induced cell contraction that was inhibited by a Rho kinase inhibitor Y27632 and had higher GEF activity for RhoA than the wild type. The T332I mutant also showed the phenotype similar to the N-terminal truncated mutant. These data suggest that the ARHGEF10 T332I mutation-associated phenotype observed in the peripheral nerves is due to activated GEF activity of the ARHGEF10 T332I mutant. PMID:21719701

Computer simulations and modeling-assisted ToxR screening in deciphering 3D structures of transmembrane α-helical dimers: ephrin receptor A1

International Nuclear Information System (INIS)

Volynsky, P E; Mineeva, E A; Goncharuk, M V; Ermolyuk, Ya S; Arseniev, A S; Efremov, R G

2010-01-01

Membrane-spanning segments of numerous proteins (e.g. receptor tyrosine kinases) represent a novel class of pharmacologically important targets, whose activity can be modulated by specially designed artificial peptides, the so-called interceptors. Rational construction of such peptides requires understanding of the main factors driving peptide–peptide association in lipid membranes. Here we present a new method for rapid prediction of the spatial structure of transmembrane (TM) helix–helix complexes. It is based on computer simulations in membrane-like media and subsequent refinement/validation of the results using experimental studies of TM helix dimerization in a bacterial membrane by means of the ToxR system. The approach was applied to TM fragments of the ephrin receptor A1 (EphA1). A set of spatial structures of the dimer was proposed based on Monte Carlo simulations in an implicit membrane followed by molecular dynamics relaxation in an explicit lipid bilayer. The resulting models were employed for rational design of wild-type and mutant genetic constructions for ToxR assays. The computational and the experimental data are self-consistent and provide an unambiguous spatial model of the TM dimer of EphA1. The results of this work can be further used to develop new biologically active 'peptide interceptors' specifically targeting membrane domains of proteins

The mir-279/996 cluster represses receptor tyrosine kinase signaling to determine cell fates in the Drosophila eye.

Science.gov (United States)

Duan, Hong; de Navas, Luis F; Hu, Fuqu; Sun, Kailiang; Mavromatakis, Yannis E; Viets, Kayla; Zhou, Cyrus; Kavaler, Joshua; Johnston, Robert J; Tomlinson, Andrew; Lai, Eric C

2018-04-09

Photoreceptors in the crystalline Drosophila eye are recruited by receptor tyrosine kinase (RTK)/Ras signaling mediated by Epidermal growth factor receptor (EGFR) and the Sevenless (Sev) receptor. Analyses of an allelic deletion series of the mir-279/996 locus, along with a panel of modified genomic rescue transgenes, show that Drosophila eye patterning depends on both miRNAs. Transcriptional reporter and activity sensor transgenes reveal expression and function of miR-279/996 in non-neural cells of the developing eye. Moreover, mir-279/996 mutants exhibit substantial numbers of ectopic photoreceptors, particularly of R7, and cone cell loss. These miRNAs restrict RTK signaling in the eye, since mir-279/996 nulls are dominantly suppressed by positive components of the EGFR pathway and enhanced by heterozygosity for an EGFR repressor. miR-279/996 limit photoreceptor recruitment by targeting multiple positive RTK/Ras signaling components that promote photoreceptor/R7 specification. Strikingly, deletion of mir-279/996 sufficiently derepresses RTK/Ras signaling so as to rescue a population of R7 cells in R7-specific RTK null mutants boss and sev , which otherwise completely lack this cell fate. Altogether, we reveal a rare setting of developmental cell specification that involves substantial miRNA control. © 2018. Published by The Company of Biologists Ltd.

Anthrax Toxin Receptor 2–Dependent Lethal Toxin Killing In Vivo

Science.gov (United States)

Scobie, Heather M; Wigelsworth, Darran J; Marlett, John M; Thomas, Diane; Rainey, G. Jonah A; Lacy, D. Borden; Manchester, Marianne; Collier, R. John; Young, John A. T

2006-01-01

Anthrax toxin receptors 1 and 2 (ANTXR1 and ANTXR2) have a related integrin-like inserted (I) domain which interacts with a metal cation that is coordinated by residue D683 of the protective antigen (PA) subunit of anthrax toxin. The receptor-bound metal ion and PA residue D683 are critical for ANTXR1-PA binding. Since PA can bind to ANTXR2 with reduced affinity in the absence of metal ions, we reasoned that D683 mutant forms of PA might specifically interact with ANTXR2. We show here that this is the case. The differential ability of ANTXR1 and ANTXR2 to bind D683 mutant PA proteins was mapped to nonconserved receptor residues at the binding interface with PA domain 2. Moreover, a D683K mutant form of PA that bound specifically to human and rat ANTXR2 mediated killing of rats by anthrax lethal toxin, providing strong evidence for the physiological importance of ANTXR2 in anthrax disease pathogenesis. PMID:17054395

LC–MS Proteomics Analysis of the Insulin/IGF-1-Deficient <i>Caenorhabditis elegans daf-2(e1370)i> Mutant Reveals Extensive Restructuring of Intermediary Metabolism

Energy Technology Data Exchange (ETDEWEB)

Depuydt, Geert; Xie, Fang; Petyuk, Vladislav A.; Smolders, Arne; Brewer, Heather M.; Camp, David G.; Smith, Richard D.; Braeckman, Bart P.

2014-04-04

The insulin/IGF-1 receptor is a major known determinant of dauer formation, stress resistance, longevity, and metabolism in Caenorhabditis elegans. In the past, whole-genome transcript profiling was used extensively to study differential gene expression in response to reduced insulin/IGF-1 signaling, including the expression levels of metabolism-associated genes. Taking advantage of the recent developments in quantitative liquid chromatography mass spectrometry (LC–MS)-based proteomics, we profiled the proteomic changes that occur in response to activation of the DAF-16 transcription factor in the germline-less glp-4(bn2);daf-2(e1370) receptor mutant. Strikingly, the daf-2 profile suggests extensive reorganization of intermediary metabolism, characterized by the upregulation of many core intermediary metabolic pathways. These include glycolysis/gluconeogenesis, glycogenesis, pentose phosphate cycle, citric acid cycle, glyoxylate shunt, fatty acid β-oxidation, one-carbon metabolism, propionate and tyrosine catabolism, and complexes I, II, III, and V of the electron transport chain. Interestingly, we found simultaneous activation of reciprocally regulated metabolic pathways, which is indicative of spatiotemporal coordination of energy metabolism and/or extensive post-translational regulation of these enzymes. Finally, this restructuring of daf-2 metabolism is reminiscent to that of hypometabolic dauers, allowing the efficient and economical utilization of internal nutrient reserves and possibly also shunting metabolites through alternative energy-generating pathways to sustain longevity.

Platelet-activating factor and group I metabotropic glutamate receptors interact for full development and maintenance of long-term potentiation in the rat medial vestibular nuclei.

Science.gov (United States)

Grassi, S; Francescangeli, E; Goracci, G; Pettorossi, V E

1999-01-01

In rat brainstem slices, we investigated the interaction between platelet-activating factor and group I metabotropic glutamate receptors in mediating long-term potentiation within the medial vestibular nuclei. We analysed the N1 field potential wave evoked in the ventral portion of the medial vestibular nuclei by primary vestibular afferent stimulation. The group I metabotropic glutamate receptor antagonist, (R,S)-1-aminoindan-1,5-dicarboxylic acid, prevented long-term potentiation induced by a platelet-activating factor analogue [1-O-hexadecyl-2-O-(methylcarbamyl)-sn-glycero-3-phosphocholine], as well as the full development of potentiation, induced by high-frequency stimulation under the blocking agent for synaptosomal platelet-activating factor receptors (ginkolide B), at drug washout. However, potentiation directly induced by the group I glutamate metabotropic receptor agonist, (R,S)-3,5-dihydroxyphenylglycine, was reduced by ginkolide B. These findings suggest that platelet-activating factor, whether exogenous or released following potentiation induction, exerts its effect through presynaptic group I metabotropic glutamate receptors, mediating the increase of glutamate release. In addition, we found that this mechanism, which led to full potentiation through presynaptic group I metabotropic glutamate receptor activation, was inactivated soon after application of potentiation-inducing stimulus. In fact, the long-lasting block of the platelet-activating factor and metabotropic glutamate receptors prevented the full potentiation development and the induced potentiation progressively declined to null. Moreover, ginkolide B, given when high-frequency-dependent potentiation was established, only reduced it within 5 min after potentiation induction. We conclude that to fully develop vestibular long-term potentiation requires presynaptic events. Platelet-activating factor, released after the activation of postsynaptic mechanisms which induce potentiation, is necessary

Partially dissecting the steady-state electron fluxes in Photosystem I in wild-type and pgr5 and ndh mutants of Arabidopsis

Directory of Open Access Journals (Sweden)

Jiancun eKou

2015-09-01

Full Text Available Cyclic electron flux (CEF around Photosystem I (PS I is difficult to quantify. We obtained the linear electron flux (LEFO2 through both photosystems and the total electron flux through PS I (ETR1 in Arabidopsis in CO2-enriched air. DeltaFlux = ETR1 – LEFO2 is an upper estimate of CEF, which consists of two components, an antimycin A-sensitive, PGR5 (proton gradient regulation 5 protein-dependent component and an insensitive component facilitated by a chloroplastic nicotinamide adenine dinucleotide dehydrogenase-like complex (NDH. Using wild type as well as pgr5 and ndh mutants, we observed that (1 40% of the absorbed light was partitioned to PS I; (2 at high irradiance a substantial antimycin A-sensitive CEF occurred in the wild type and the ndh mutant; (3 at low irradiance a sizable antimycin A-sensitive CEF occurred in the wild type but not in the ndh mutant, suggesting an enhancing effect of NDH in low light; and (4 in the pgr5 mutant, and the wild type and ndh mutant treated with antimycin A, a residual DeltaFlux existed at high irradiance, attributable to charge recombination and/or pseudo-cyclic electron flow. Therefore, in low-light-acclimated plants exposed to high light, DeltaFlux has contributions from various paths of electron flow through PS I.

An OmpA family protein, a target of the GinI/GinR quorum-sensing system in Gluconacetobacter intermedius, controls acetic acid fermentation.

Science.gov (United States)

Iida, Aya; Ohnishi, Yasuo; Horinouchi, Sueharu

2008-07-01

Via N-acylhomoserine lactones, the GinI/GinR quorum-sensing system in Gluconacetobacter intermedius NCI1051, a gram-negative acetic acid bacterium, represses acetic acid and gluconic acid fermentation. Two-dimensional polyacrylamide gel electrophoretic analysis of protein profiles of strain NCI1051 and ginI and ginR mutants identified a protein that was produced in response to the GinI/GinR regulatory system. Cloning and nucleotide sequencing of the gene encoding this protein revealed that it encoded an OmpA family protein, named GmpA. gmpA was a member of the gene cluster containing three adjacent homologous genes, gmpA to gmpC, the organization of which appeared to be unique to vinegar producers, including "Gluconacetobacter polyoxogenes." In addition, GmpA was unique among the OmpA family proteins in that its N-terminal membrane domain forming eight antiparallel transmembrane beta-strands contained an extra sequence in one of the surface-exposed loops. Transcriptional analysis showed that only gmpA of the three adjacent gmp genes was activated by the GinI/GinR quorum-sensing system. However, gmpA was not controlled directly by GinR but was controlled by an 89-amino-acid protein, GinA, a target of this quorum-sensing system. A gmpA mutant grew more rapidly in the presence of 2% (vol/vol) ethanol and accumulated acetic acid and gluconic acid in greater final yields than strain NCI1051. Thus, GmpA plays a role in repressing oxidative fermentation, including acetic acid fermentation, which is unique to acetic acid bacteria and allows ATP synthesis via ethanol oxidation. Consistent with the involvement of gmpA in oxidative fermentation, its transcription was also enhanced by ethanol and acetic acid.

Characterization of glucagon-like peptide-1 receptor-binding determinants.

Science.gov (United States)

Xiao, Q; Jeng, W; Wheeler, M B

2000-12-01

Glucagon-like peptide 1 (GLP-1) is a potent insulinotropic hormone currently under study as a therapeutic agent for type 2 diabetes. Since an understanding of the molecular mechanisms leading to high-affinity receptor (R) binding and activation may facilitate the development of more potent GLP-1R agonists, we have localized specific regions of GLP-1R required for binding. The purified N-terminal fragment (hereafter referred to as NT) of the GLP-1R produced in either insect (Sf9) or mammalian (COS-7) cells was shown to bind GLP-1. The physical interaction of NT with GLP-1 was first demonstrated by cross-linking ((125)I-GLP-1/NT complex band at approximately 28 kDa) and secondly by attachment to Ni(2+)-NTA beads. The GLP-1R NT protein attached to beads bound GLP-1, but with lower affinity (inhibitory concentration (IC(50)): 4.5 x 10(-7) M) than wild-type (WT) GLP-1R (IC(50): 5.2 x 10(-9)M). The low affinity of GLP-1R NT suggested that other receptor domains may contribute to GLP-1 binding. This was supported by studies using chimeric glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptors. GIP(1-151)/GLP-1R, but not GIP(1-222)/GLP-1R, exhibited specific GLP-1 binding and GLP-1-induced cAMP production, suggesting that the region encompassing transmembrane (TM) domain 1 through to TM3 was required for binding. Since it was hypothesized that certain charged or polar amino acids in this region might be involved in binding, these residues (TM2-TM3) were analyzed by substitution mutagenesis. Five mutants (K197A, D198A, K202A, D215A, R227A) displayed remarkably reduced binding affinity. These studies indicate that the NT domain of the GLP-1R is able to bind GLP-1, but charged residues concentrated at the distal TM2/extracellular loop-1 (EC1) interface (K197, D198, K202) and in EC1 (D215 and R227) probably contribute to the binding determinants of the GLP-1R.

Iodine-123 labelled Z-(R,R)-IQNP: a potential radioligand for visualization of M{sub 1} and M{sub 2} muscarinic acetylcholine receptors in Alzheimer's disease

Energy Technology Data Exchange (ETDEWEB)

Bergstroem, K.A. [Dept. of Clinical Neuroscience, Psychiatry and Nuclear Medicine Sections, Karolinska Institutet, Karolinska Hospital, Stockholm (Sweden); Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio (Finland); Halldin, C.; Okubo, Yoshiro; Nobuhara, Kenji; Swahn, C.G.; Karlsson, P.; Larsson, S.; Schnell, P.O.; Farde, L. [Dept. of Clinical Neuroscience, Psychiatry and Nuclear Medicine Sections, Karolinska Institutet, Karolinska Hospital, Stockholm (Sweden); Savonen, A.; Hiltunen, Jukka [MAP Medical Technologies Oy, Tikkakoski (Finland); McPherson, D.; Knapp, F.F. Jr. [Nuclear Medicine Group, Oak Ridge National Laboratory (ORNL), TN (United States)

1999-11-01

Z-(R)-1-Azabicyclo[2.2.2]oct-3-yl (R)-{alpha}-hydroxy-{alpha}-(1-iodo-1-propen-3-yl)-{alpha}-phenylacetate (Z-IQNP) has high affinity to the M{sub 1}and M {sub 2} muscarinic acetylcholine receptor (mAChR) subtypes according to previous in vitro and in vivo studies in rats. In the present study iodine-123 labelled Z-IQNP was prepared for in vivo single-photon emission tomography (SPET) studies in cynomolgus monkeys. SPET studies with Z-[ {sup 123}I]IQNP demonstrated high accumulation in monkey brain (>5% of injected dose at 70 min p.i.) and marked accumulation in brain regions such as the thalamus, the neocortex, the striatum and the cerebellum. Pretreatment with the non-selective mAChR antagonist scopolamine (0.2 mg/kg) inhibited Z-[ {sup 123}I]IQNP binding in all these regions. The percentage of unchanged Z-[ {sup 123}I]IQNP measured in plasma was less than 10% at 10 min after injection, which may be due to rapid hydrolysis, as has been demonstrated previously with the E-isomer of IQNP. Z-[ {sup 123}I]IQNP showed higher uptake in M {sub 2}-rich regions, compared with previously obtained results with E-[ {sup 123}I]IQNP. In conclusion, the radioactivity distribution from Z-[ {sup 123}I]IQNP in monkey brain indicates that Z-[ {sup 123}I]IQNP binds to the M {sub 1}- and M {sub 2}-rich areas and provides a high signal for specific binding, and is thus a potential ligand for mAChR imaging with SPET. (orig.)

Using iPods[R] and iPads[R] in Teaching Programs for Individuals with Developmental Disabilities: A Systematic Review

Science.gov (United States)

Kagohara, Debora M.; van der Meer, Larah; Ramdoss, Sathiyaprakash; O'Reilly, Mark F.; Lancioni, Giulio E.; Davis, Tonya N.; Rispoli, Mandy; Lang, Russell; Marschik, Peter B.; Sutherland, Dean; Green, Vanessa A.; Sigafoos, Jeff

2013-01-01

We conducted a systematic review of studies that involved iPods[R], iPads[R], and related devices (e.g., iPhones[R]) in teaching programs for individuals with developmental disabilities. The search yielded 15 studies covering five domains: (a) academic, (b) communication, (c) employment, (d) leisure, and (e) transitioning across school settings.…

24 CFR 255.6 - Method of payment of mortgage insurance premiums.

Science.gov (United States)

2010-04-01

... insurance premiums. 255.6 Section 255.6 Housing and Urban Development Regulations Relating to Housing and... PROJECTS § 255.6 Method of payment of mortgage insurance premiums. The provisions of 24 CFR 251.6 shall..., DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT...

20 CFR 255.9 - Individual enrolled under supplementary medical insurance plan.

Science.gov (United States)

2010-04-01

... supplementary medical insurance premiums will be applied toward payment of such premiums, and the balance of the... medical insurance plan. 255.9 Section 255.9 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS... supplementary medical insurance plan. Where recovery of the overpayment is by setoff as provided for in § 255.6...

IRS-1 acts as an endocytic regulator of IGF-I receptor to facilitate sustained IGF signaling.

Science.gov (United States)

Yoneyama, Yosuke; Lanzerstorfer, Peter; Niwa, Hideaki; Umehara, Takashi; Shibano, Takashi; Yokoyama, Shigeyuki; Chida, Kazuhiro; Weghuber, Julian; Hakuno, Fumihiko; Takahashi, Shin-Ichiro

2018-04-11

Insulin-like growth factor-I receptor (IGF-IR) preferentially regulates the long-term IGF activities including growth and metabolism. Kinetics of ligand-dependent IGF-IR endocytosis determines how IGF induces such downstream signaling outputs. Here, we find that the insulin receptor substrate (IRS)-1 modulates how long ligand-activated IGF-IR remains at the cell surface before undergoing endocytosis in mammalian cells. IRS-1 interacts with the clathrin adaptor complex AP2. IRS-1, but not an AP2-binding-deficient mutant, delays AP2-mediated IGF-IR endocytosis after the ligand stimulation. Mechanistically, IRS-1 inhibits the recruitment of IGF-IR into clathrin-coated structures; for this reason, IGF-IR avoids rapid endocytosis and prolongs its activity on the cell surface. Accelerating IGF-IR endocytosis via IRS-1 depletion induces the shift from sustained to transient Akt activation and augments FoxO-mediated transcription. Our study establishes a new role for IRS-1 as an endocytic regulator of IGF-IR that ensures sustained IGF bioactivity, independent of its classic role as an adaptor in IGF-IR signaling. © 2018, Yoneyama et al.

Subtype selective kainic acid receptor agonists

DEFF Research Database (Denmark)

Bunch, Lennart; Krogsgaard-Larsen, Povl

2009-01-01

(S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system, activating the plethora of glutamate receptors (GluRs). In broad lines, the GluRs are divided into two major classes: the ionotropic Glu receptors (iGluRs) and the metabotropic Glu receptors (m......GluRs). Within the iGluRs, five subtypes (KA1, KA2, iGluR5-7) show high affinity and express full agonist activity upon binding of the naturally occurring amino acid kainic acid (KA). Thus these receptors have been named the KA receptors. This review describes all-to our knowledge-published KA receptor agonists...

~ i t i d e r m a t o ~ h ~ t i c Activities of Nine (9) Essential Oils J.R. ...

African Journals Online (AJOL)

i t i d e r m a t o ~ h ~ t i c Activities of Nine (9) Essential Oils. J.R. KUIATE", S.P. KUATE'.~, N.E. KEMADJOU~, S. DJOKOUA~, F. ZIFACK~ AND J. ~. 0. ~. 0. ~. I Department of Biochemistry, FS, University of Dschang, P.O. Box 67 Dschang, Cameroon. 2~epartment of Biochemistry, FS, University of Yaoundt!, P.O. Box 812 ...

Cross-communication between Gi and Gs in a G-protein-coupled receptor heterotetramer guided by a receptor C-terminal domain.

Science.gov (United States)

Navarro, Gemma; Cordomí, Arnau; Brugarolas, Marc; Moreno, Estefanía; Aguinaga, David; Pérez-Benito, Laura; Ferre, Sergi; Cortés, Antoni; Casadó, Vicent; Mallol, Josefa; Canela, Enric I; Lluís, Carme; Pardo, Leonardo; McCormick, Peter J; Franco, Rafael

2018-02-28

G-protein-coupled receptor (GPCR) heteromeric complexes have distinct properties from homomeric GPCRs, giving rise to new receptor functionalities. Adenosine receptors (A 1 R or A 2A R) can form A 1 R-A 2A R heteromers (A 1 -A 2A Het), and their activation leads to canonical G-protein-dependent (adenylate cyclase mediated) and -independent (β-arrestin mediated) signaling. Adenosine has different affinities for A 1 R and A 2A R, allowing the heteromeric receptor to detect its concentration by integrating the downstream G i - and G s -dependent signals. cAMP accumulation and β-arrestin recruitment assays have shown that, within the complex, activation of A 2A R impedes signaling via A 1 R. We examined the mechanism by which A 1 -A 2A Het integrates G i - and G s -dependent signals. A 1 R blockade by A 2A R in the A 1 -A 2A Het is not observed in the absence of A 2A R activation by agonists, in the absence of the C-terminal domain of A 2A R, or in the presence of synthetic peptides that disrupt the heteromer interface of A 1 -A 2A Het, indicating that signaling mediated by A 1 R and A 2A R is controlled by both G i and G s proteins. We identified a new mechanism of signal transduction that implies a cross-communication between G i and G s proteins guided by the C-terminal tail of the A 2A R. This mechanism provides the molecular basis for the operation of the A 1 -A 2A Het as an adenosine concentration-sensing device that modulates the signals originating at both A 1 R and A 2A R.

Impact of ursodeoxycholic acid on a CCK1R cholesterol-binding site may contribute to its positive effects in digestive function.

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Desai, Aditya J; Dong, Maoqing; Harikumar, Kaleeckal G; Miller, Laurence J

2015-09-01

Dysfunction of the type 1 cholecystokinin (CCK) receptor (CCK1R) as a result of increased gallbladder muscularis membrane cholesterol has been implicated in the pathogenesis of cholesterol gallstones. Administration of ursodeoxycholic acid, which is structurally related to cholesterol, has been shown to have beneficial effects on gallstone formation. Our aims were to explore the possible direct effects and mechanism of action of bile acids on CCK receptor function. We studied the effects of structurally related hydrophobic chenodeoxycholic acid and hydrophilic ursodeoxycholic acid in vitro on CCK receptor function in the setting of normal and elevated membrane cholesterol. We also examined their effects on a cholesterol-insensitive CCK1R mutant (Y140A) disrupting a key site of cholesterol action. The results show that, similar to the impact of cholesterol on CCK receptors, bile acid effects were limited to CCK1R, with no effects on CCK2R. Chenodeoxycholic acid had a negative impact on CCK1R function, while ursodeoxycholic acid had no effect on CCK1R function in normal membranes but was protective against the negative impact of elevated cholesterol on this receptor. The cholesterol-insensitive CCK1R mutant Y140A was resistant to effects of both bile acids. These data suggest that bile acids compete with the action of cholesterol on CCK1R, probably by interacting at the same site, although the conformational impact of each bile acid appears to be different, with ursodeoxycholic acid capable of correcting the abnormal conformation of CCK1R in a high-cholesterol environment. This mechanism may contribute to the beneficial effect of ursodeoxycholic acid in reducing cholesterol gallstone formation. Copyright © 2015 the American Physiological Society.

uvsI mutants defective in UV mutagenesis define a fourth epistatic group of uvs genes in Aspergillus.

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Chae, S K; Kafer, E

1993-01-01

Three UV-sensitive mutations of A. nidulans, uvsI, uvsJ and uvsA, were tested for epistatic relationships with members of the previously established groups, here called the "UvsF", "UvsC", and "UvsB" groups. uvsI mutants are defective for spontaneous and induced reversion of certain point mutations and differ also for other properties from previously analyzed uvs types. They are very sensitive to the killing effects of UV-light and 4-NQO (4-nitro-quinoline-N-oxide) but not to MMS (methylmethane sulfonate). When double- and single-mutant uvs strains were compared for sensitivity to these three agents, synergistic or additive effects were found for uvsI with all members of the three groups. The uvsI gene may therefore represent a fourth epistatic group, possibly involved in mutagenic repair. On the other hand, uvsJ was clearly epistatic with members of the UvsF group and fitted well into this group also by phenotype. The uvsA gene was tentatively assigned to the UvsC group. uvsA showed epistatic interactions with uvsC in all tests, and like UvsC-group mutants is UV-sensitive mainly in dividing cells. However, the uvsA mutation does not cause the defects in recombination and UV mutagenesis typical for this group.

Behavioral Sensitization to the Disinhibition Effect of Ethanol Requires the Dopamine/Ecdysone Receptor in Drosophila

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Gissel P. Aranda

2017-08-01

Full Text Available Male flies under the influence of ethanol display disinhibited courtship, which is augmented with repeated ethanol exposures. We have previously shown that dopamine is important for this type of ethanol-induced behavioral sensitization but the underlying mechanism is unknown. Here we report that DopEcR, an insect G-protein coupled receptor that binds to dopamine and steroid hormone ecdysone, is a major receptor mediating courtship sensitization. Upon daily ethanol administration, dumb and damb mutant males defective in D1 (dDA1/DopR1 and D5 (DAMB/DopR2 dopamine receptors, respectively, showed normal courtship sensitization; however, the DopEcR-deficient der males exhibited greatly diminished sensitization. der mutant males nevertheless developed normal tolerance to the sedative effect of ethanol, indicating a selective function of DopEcR in chronic ethanol-associated behavioral plasticity. DopEcR plays a physiological role in behavioral sensitization since courtship sensitization in der males was reinstated when DopEcR expression was induced during adulthood but not during development. When examined for the DopEcR’s functional site, the der mutant’s sensitization phenotype was fully rescued by restored DopEcR expression in the mushroom body (MB αβ and γ neurons. Consistently, we observed DopEcR immunoreactivity in the MB calyx and lobes in the wild-type Canton-S brain, which was barely detectable in the der brain. Behavioral sensitization to the locomotor-stimulant effect has been serving as a model for ethanol abuse and addiction. This is the first report elucidating the mechanism underlying behavioral sensitization to another stimulant effect of ethanol.

37 CFR 255.4 - Definition of digital phonorecord delivery.

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2010-07-01

... phonorecord delivery. 255.4 Section 255.4 Patents, Trademarks, and Copyrights COPYRIGHT OFFICE, LIBRARY OF... delivery. A “digital phonorecord delivery” is each individual delivery of a phonorecord by digital... time or for a specified number of performances. A digital phonorecord delivery includes all...

Molecular analyses of in vivo hprt mutant T cells from atomic bomb survivors

International Nuclear Information System (INIS)

Hakoda, M.; Hirai, Y.; Kyoizumi, S.; Akiyama, M.

1989-01-01

In vivo-derived hprt-deficient mutant T cells isolated from three nonirradiated controls and two atomic bomb survivors were studied by Southern blot analysis to investigate the molecular spectra of the mutations. Mutant frequencies for the three controls were 1.8, 2.3, and 7.3 x 10(-6), and those for the two survivors (who had received radiation doses of 2.46 and 2.15 Gy, based upon the revised atomic bomb shielded kerma estimates) were 9.3 and 14.4 x 10(-6), respectively. Fourteen (13%) of 105 mutant T-cell colonies from the controls showed various structural changes in the hprt gene. The frequency of mutants with hprt gene structural changes in one atomic bomb survivor, who exhibited a mutant frequency of 9.3 x 10(-6), was 26% (16/61), which was significantly higher than that of the controls. However, the frequency of structural changes in the other survivor (14%, 8/59) was not higher than that of the controls. Two sets of mutants (in total, eight mutants) from the survivor, who showed a significantly higher frequency of mutants with hprt gross alterations than did the controls, had the same hprt changes and the same rearrangements of T-cell receptor (TcR) beta- and gamma-chain genes, indicating a clonal expansion from one progenitor mutant. This phenomenon may reflect an in vivo recovery process of T cells in the periphery after exposure to atomic bomb radiation. However, when comparing the frequency of mutations, these two sets of mutants should be reduced. After reducing the total number of mutants from the number of gross hprt changes, the frequency was not significantly higher than that of the controls

Drosophila Insulin receptor regulates the persistence of injury-induced nociceptive sensitization

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Patel, Atit A.

2018-01-01

ABSTRACT Diabetes-associated nociceptive hypersensitivity affects diabetic patients with hard-to-treat chronic pain. Because multiple tissues are affected by systemic alterations in insulin signaling, the functional locus of insulin signaling in diabetes-associated hypersensitivity remains obscure. Here, we used Drosophila nociception/nociceptive sensitization assays to investigate the role of Insulin receptor (Insulin-like receptor, InR) in nociceptive hypersensitivity. InR mutant larvae exhibited mostly normal baseline thermal nociception (absence of injury) and normal acute thermal hypersensitivity following UV-induced injury. However, their acute thermal hypersensitivity persists and fails to return to baseline, unlike in controls. Remarkably, injury-induced persistent hypersensitivity is also observed in larvae that exhibit either type 1 or type 2 diabetes. Cell type-specific genetic analysis indicates that InR function is required in multidendritic sensory neurons including nociceptive class IV neurons. In these same nociceptive sensory neurons, only modest changes in dendritic morphology were observed in the InRRNAi-expressing and diabetic larvae. At the cellular level, InR-deficient nociceptive sensory neurons show elevated calcium responses after injury. Sensory neuron-specific expression of InR rescues the persistent thermal hypersensitivity of InR mutants and constitutive activation of InR in sensory neurons ameliorates the hypersensitivity observed with a type 2-like diabetic state. Our results suggest that a sensory neuron-specific function of InR regulates the persistence of injury-associated hypersensitivity. It is likely that this new system will be an informative genetically tractable model of diabetes-associated hypersensitivity. PMID:29752280

Allosteric Mutant IDH1 Inhibitors Reveal Mechanisms for IDH1 Mutant and Isoform Selectivity

Energy Technology Data Exchange (ETDEWEB)

Xie, Xiaoling; Baird, Daniel; Bowen, Kimberly; Capka, Vladimir; Chen, Jinyun; Chenail, Gregg; Cho, YoungShin; Dooley, Julia; Farsidjani, Ali; Fortin, Pascal; Kohls, Darcy; Kulathila, Raviraj; Lin, Fallon; McKay, Daniel; Rodrigues, Lindsey; Sage, David; Touré, B. Barry; van der Plas, Simon; Wright, Kirk; Xu, Ming; Yin, Hong; Levell, Julian; Pagliarini, Raymond A. (Novartis)

2017-03-01

Oncogenic IDH1 and IDH2 mutations contribute to cancer via production of R-2-hydroxyglutarate (2-HG). Here, we characterize two structurally distinct mutant- and isoform-selective IDH1 inhibitors that inhibit 2-HG production. Both bind to an allosteric pocket on IDH1, yet shape it differently, highlighting the plasticity of this site. Oncogenic IDH1R132H mutation destabilizes an IDH1 “regulatory segment,” which otherwise restricts compound access to the allosteric pocket. Regulatory segment destabilization in wild-type IDH1 promotes inhibitor binding, suggesting that destabilization is critical for mutant selectivity. We also report crystal structures of oncogenic IDH2 mutant isoforms, highlighting the fact that the analogous segment of IDH2 is not similarly destabilized. This intrinsic stability of IDH2 may contribute to observed inhibitor IDH1 isoform selectivity. Moreover, discrete residues in the IDH1 allosteric pocket that differ from IDH2 may also guide IDH1 isoform selectivity. These data provide a deeper understanding of how IDH1 inhibitors achieve mutant and isoform selectivity.

Characterization of a Vibrio vulnificus LysR homologue, HupR, which regulates expression of the haem uptake outer membrane protein, HupA.

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Litwin, C M; Quackenbush, J

2001-12-01

In Vibrio vulnificus, the ability to acquire iron from the host has been shown to correlate with virulence. Here, we show that the DNA upstream of hupA (haem uptake receptor) in V. vulnificus encodes a protein in the inverse orientation to hupA (named hupR). HupR shares homology with the LysR family of positive transcriptional activators. A hupA-lacZ fusion contained on a plasmid was transformed into Fur(-), Fur(+)and HupR(-)strains of V. vulnificus. The beta-galactosidase assays and Northern blot analysis showed that transcription of hupA is negatively regulated by iron and the Fur repressor in V. vulnificus. Under low-iron conditions with added haemin, the expression of hupA in the hupR mutant was significantly lower than in the wild-type. This diminished response to haem was detected by both Northern blot and hupA-lacZ fusion analysis. The haem response of hupA in the hupR mutant was restored to wild-type levels when complemented with hupR in trans. These studies suggest that HupR may act as a positive regulator of hupA transcription under low-iron conditions in the presence of haemin. Copyright 2001 Academic Press.

I1 imidazoline receptor: novel potential cytoprotective target of TVP1022, the S-enantiomer of rasagiline.

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Yaron D Barac

Full Text Available TVP1022, the S-enantiomer of rasagiline (Azilect® (N-propargyl-1R-aminoindan, exerts cyto/cardio-protective effects in a variety of experimental cardiac and neuronal models. Previous studies have demonstrated that the protective activity of TVP1022 and other propargyl derivatives involve the activation of p42/44 mitogen-activated protein kinase (MAPK signaling pathway. In the current study, we further investigated the molecular mechanism of action and signaling pathways of TVP1022 which may account for the cyto/cardio-protective efficacy of the drug. Using specific receptor binding and enzyme assays, we demonstrated that the imidazoline 1 and 2 binding sites (I(1 & I(2 are potential targets for TVP1022 (IC(50 =9.5E-08 M and IC(50 =1.4E-07 M, respectively. Western blotting analysis showed that TVP1022 (1-20 µM dose-dependently increased the immunoreactivity of phosphorylated p42 and p44 MAPK in rat pheochromocytoma PC12 cells and in neonatal rat ventricular myocytes (NRVM. This effect of TVP1022 was significantly attenuated by efaroxan, a selective I(1 imidazoline receptor antagonist. In addition, the cytoprotective effect of TVP1022 demonstrated in NRVM against serum deprivation-induced toxicity was markedly inhibited by efaroxan, thus suggesting the importance of I(1imidazoline receptor in mediating the cardioprotective activity of the drug. Our findings suggest that the I(1imidazoline receptor represents a novel site of action for the cyto/cardio-protective efficacy of TVP1022.

I1 imidazoline receptor: novel potential cytoprotective target of TVP1022, the S-enantiomer of rasagiline.

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Barac, Yaron D; Bar-Am, Orit; Liani, Esti; Amit, Tamar; Frolov, Luba; Ovcharenko, Elena; Angel, Itzchak; Youdim, Moussa B H; Binah, Ofer

2012-01-01

TVP1022, the S-enantiomer of rasagiline (Azilect®) (N-propargyl-1R-aminoindan), exerts cyto/cardio-protective effects in a variety of experimental cardiac and neuronal models. Previous studies have demonstrated that the protective activity of TVP1022 and other propargyl derivatives involve the activation of p42/44 mitogen-activated protein kinase (MAPK) signaling pathway. In the current study, we further investigated the molecular mechanism of action and signaling pathways of TVP1022 which may account for the cyto/cardio-protective efficacy of the drug. Using specific receptor binding and enzyme assays, we demonstrated that the imidazoline 1 and 2 binding sites (I(1) & I(2)) are potential targets for TVP1022 (IC(50) =9.5E-08 M and IC(50) =1.4E-07 M, respectively). Western blotting analysis showed that TVP1022 (1-20 µM) dose-dependently increased the immunoreactivity of phosphorylated p42 and p44 MAPK in rat pheochromocytoma PC12 cells and in neonatal rat ventricular myocytes (NRVM). This effect of TVP1022 was significantly attenuated by efaroxan, a selective I(1) imidazoline receptor antagonist. In addition, the cytoprotective effect of TVP1022 demonstrated in NRVM against serum deprivation-induced toxicity was markedly inhibited by efaroxan, thus suggesting the importance of I(1)imidazoline receptor in mediating the cardioprotective activity of the drug. Our findings suggest that the I(1)imidazoline receptor represents a novel site of action for the cyto/cardio-protective efficacy of TVP1022.

An OmpA Family Protein, a Target of the GinI/GinR Quorum-Sensing System in Gluconacetobacter intermedius, Controls Acetic Acid Fermentation▿ †

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Iida, Aya; Ohnishi, Yasuo; Horinouchi, Sueharu

2008-01-01

Via N-acylhomoserine lactones, the GinI/GinR quorum-sensing system in Gluconacetobacter intermedius NCI1051, a gram-negative acetic acid bacterium, represses acetic acid and gluconic acid fermentation. Two-dimensional polyacrylamide gel electrophoretic analysis of protein profiles of strain NCI1051 and ginI and ginR mutants identified a protein that was produced in response to the GinI/GinR regulatory system. Cloning and nucleotide sequencing of the gene encoding this protein revealed that it encoded an OmpA family protein, named GmpA. gmpA was a member of the gene cluster containing three adjacent homologous genes, gmpA to gmpC, the organization of which appeared to be unique to vinegar producers, including “Gluconacetobacter polyoxogenes.” In addition, GmpA was unique among the OmpA family proteins in that its N-terminal membrane domain forming eight antiparallel transmembrane β-strands contained an extra sequence in one of the surface-exposed loops. Transcriptional analysis showed that only gmpA of the three adjacent gmp genes was activated by the GinI/GinR quorum-sensing system. However, gmpA was not controlled directly by GinR but was controlled by an 89-amino-acid protein, GinA, a target of this quorum-sensing system. A gmpA mutant grew more rapidly in the presence of 2% (vol/vol) ethanol and accumulated acetic acid and gluconic acid in greater final yields than strain NCI1051. Thus, GmpA plays a role in repressing oxidative fermentation, including acetic acid fermentation, which is unique to acetic acid bacteria and allows ATP synthesis via ethanol oxidation. Consistent with the involvement of gmpA in oxidative fermentation, its transcription was also enhanced by ethanol and acetic acid. PMID:18487322

Role of the interplay between quorum sensing regulator VqsR and the Pseudomonas quinolone signal in mediating carbapenem tolerance in Pseudomonas aeruginosa.

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Viducic, Darija; Murakami, Keiji; Amoh, Takashi; Ono, Tsuneko; Miyake, Yoichiro

2017-06-01

Pseudomonas aeruginosa coordinates its response to environmental conditions through activation of a quorum sensing (QS) system. In this study, we investigated the regulatory interaction between the QS transcriptional regulator VqsR and the Pseudomonas quinolone signal (PQS) through integration of sigma factor RpoS, and we addressed whether one of the pathways controlling carbapenem tolerance can be attributed to VqsR. We demonstrate that vqsR expression at the transcriptional level is regulated by pqsA, pqsR, and pqsE. Assessment of the transcriptional expression of vqsR, lasI, rhlI, and qscR in ΔpqsA and ΔpqsAΔrpoS mutants provided insight into pqsA- and rpoS-dependent regulation of vqsR and vqsR-controlled genes. Exogenously supplemented PQS reversed expression of vqsR and vqsR-controlled genes in the ΔpqsA mutant to wild-type levels, but failed to increase expression levels of lasI and qscR in the ΔpqsAΔrpoS mutant to levels observed in wild-type PAO1. The ΔvqsR mutant showed reduced survival when challenged with carbapenems compared to wild-type PAO1. Introduction of a pqsA mutation into the ΔvqsR mutant completely abolished its carbapenem-sensitive phenotype. We conclude that a regulatory link between PQS and vqsR exists, and that RpoS is important in their interaction. We also demonstrate that VqsR affects carbapenem tolerance. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Transcriptomic profile of aguR deletion mutant of Lactococcus lactis subsp. cremoris CECT 8666