PubMed Central (PMC3 - NLM DTD)
(2,081,148 recursos)
Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).
Mostrando recursos 21 - 40 de 951
21.
In vivo resolution of oligomers with fluorescence photobleaching recovery histograms - Youn, B.S.; Lepock, J.R.; Borrelli, M.J.; Jervis, E.J.
Simple independent enzyme-catalyzed reactions distributed homogeneously throughout an aqueous environment cannot adequately explain the regulation of metabolic and other cellular processes in vivo. Such an unstructured system results in unacceptably slow substrate turnover rates and consumes inordinate amounts of cellular energy. Current approaches to resolving compartmentalization in living cells requires the partitioning of the molecular species in question such that its localization can be resolved with fluorescence microscopy. Standard imaging approaches will not resolve localization of protein activity for proteins that are ubiquitously distributed, but whose function requires a change in state of the protein. The small heat shock protein...
22.
Human resting extracellular heat shock protein 72 concentration decreases during the initial adaptation to exercise in a hot, humid environment - Marshall, Helen C.; Ferguson, Richard A.; Nimmo, Myra A.
Heat shock protein (Hsp) 72 is a cytosolic protein that also is present in the circulation. Extracellular Hsp72 (eHsp72) is inducible by exercise and is suggested to act as a danger signal to the immune system. The adaptive response of eHsp72 to repeated exercise-heat exposures in humans remains to be determined. An intracellular animal study found a reduced Hsp72 response, with no change in resting levels, during heat stress after a single day of passive heat acclimation. The current study therefore tested whether adaptations in human eHsp72 levels would similarly occur 24 hours after a single exercise-heat exposure. Seven males...
24.
Self-cytoprotection against stress: feedback regulation of heme- dependent metabolism - Schwartsburd, P.M.
This minireview provides insight into feedback regulation of heme-dependent metabolism as a defensive cellular response against stress. Interactions among heme-, iron-, porphyrin-, and CO/NO-dependent metabolic pathways during the stress-induced response are emphasized in the context of feedback regulation. The hypothetical model of the latter interactions is presented as tightly controlled feedback cycles.
25.
Arsenite-inducible RNA-associated protein (AIRAP) protects cells from arsenite toxicity - Sok, John; Calfon, Marcella; Lu, Jinyu; Lichtlen, Peter; Clark, Scott G.; Ron, David
Exposure of cells to arsenicals activates multiple stress pathways resulting in the induction of specific genes whose identity and role in the adaptation to arsenical-induced cellular stress are poorly understood. We report here the identification of a novel gene encoding an arsenite-inducible, cysteine- and histidine-rich RNA-associated protein, AIRAP, that is conserved among mammals, Drosophila and C elegans. Immunochemistry and cell fractionation experiments indicate that, when induced, AIRAP is present in both the nucleus and the cytoplasm, and cross-linking experiments indicate that it associates with RNA in vivo. The expression of a C elegans homologue of AIRAP, aip-1, is also induced...
26.
Protein kinase inhibitors can suppress stress-induced dissociation of Hsp27 - Kato, Kanefusa; Ito, Hidenori; Iwamoto, Ikuko; Iida, Kayo; Inaguma, Yutaka
We previously showed that the aggregated form of Hsp27 in cultured cells becomes dissociated as a result of phosphorylation with various types of stress. In order to clarify the signal transduction cascade involved, the effects of various inhibitors of protein kinases and dithiothreitol on the dissociation of Hsp27 were here examined by means of an immunoassay after fractionation of cell extracts by sucrose density gradient centrifugation. The dissociation of Hsp27 induced by exposure of U251 MG human glioma cells to metals (NaAsO2 and CdCl2), hypertonic stress (sorbitol and NaCl), or anisomycin, an activator of p38 mitogenactivated protein (MAP) kinase, was...
27.
?B-crystallin, a low-molecular-weight heat shock protein, acts as a regulator of platelet function - Kozawa, O.; Matsuno, H.; Niwa, M.; Hatakeyama, D.; Kato, K.; Uematsu, T.
It has recently been reported that ?B-crystallin, a low-molecular-weight heat shock protein, may be released from cells by mechanical stretch. We investigated a physiological role of ?B-crystallin in platelet function. ?B-crystallin inhibited platelet aggregation induced by thrombin or botrocetin in hamsters and humans. These platelets had specific binding sites for ?B-crystallin. Moreover, ?B-crystallin significantly reduced thrombin-induced Ca2+ influx and phosphoinositide hydrolysis by phospholipase C in human platelets. Additionally, plasma levels of ?B-crystallin were markedly elevated in cardiomyopathic hamsters. Levels of ?B-crystallin in vessel walls after endothelial injury were markedly reduced. Therefore, our results suggest that ?B-crystallin, which is discharged from...
28.
DnaK/DnaJ chaperone system reactivates endogenous E coli thermostable FBP aldolase in vivo and in vitro; the effect is enhanced by GroE heat shock proteins - K?dzierska, Sabina; Jezierski, Grzegorz; Taylor, Alina
Thermally aggregated, endogenous proteins in Escherichia coli cells form the S fraction, which is separable by sucrose density gradient centrifugation. To date, relatively little is known about the mechanisms of elimination of the heat-aggregated proteins from E coli cells and the composition of the S fraction. We have identified several proteins of the S fraction using 2D-gel electrophoresis and microsequencing. A thermostable II class fructose-1,6-bisphosphate aldolase (Fda protein) appeared to be one of numerous proteins of the S fraction. Fda was purified from E coli overproducer strain and used as a model substrate for investigation of the role of Hsps...
29.
Expression of the chaperonin 10 gene during zebrafish development - Cristofre Martin, C.; Tang, Pingtao; Barnardo, Georgina; Krone, Patrick H.
We have isolated a cDNA encoding chaperonin 10 (cpn10) from the zebrafish. Using northern, western, and in situ hybridization analysis, we observed that the cpn10 gene is expressed uniformly and ubiquitously throughout embryonic development of the zebrafish. Upregulation of cpn10 expression was observed following exposure of zebrafish embryos to a heat shock of 1 hour at 37°C compared to control embryos raised at 27°C. The extracellular form of Cpn10 called early pregnancy factor (EPF), found in the serum of pregnant mammals, was not detected in the serum of either male or female zebrafish. These expression studies suggest that Cpn10 plays...
30.
Effects of schisandrin B pretreatment on tumor necrosis factor-? induced apoptosis and Hsp70 expression in mouse liver - Ip, Siu-Po; Che, Chun-Tao; Kong, Yun-Cheung; Ko, Kam-Ming
Tumor necrosis factor-? (TNF?) could cause apoptosis in hepatic tissue of d-galactosamine sensitized mice, as evidenced by the increase in the extent of DNA fragmentation. The hepatic apoptosis induced by TNF? was associated with hepatocellular damage as assessed by plasma alanine aminotransferase activity. Schisandrin B (Sch B) pretreatment at daily doses ranging from 0.5 to 2 mmol/kg for 3 days caused a dose-dependent protection against TNF?-induced apoptosis in mice. The hepatoprotection was accompanied by a parallel reduction in the extent of hepatocellular damage. The same Sch B pretreatment regimens increased hepatic Hsp70 level in a dose-dependent manner. The relevance of...
31.
Hsp27 protects mitochondria of thermotolerant cells against apoptotic stimuli - Samali, Afshin; Robertson, John D.; Peterson, Elisabeth; Manero, Florence; van Zeijl, Leone; Paul, Catherine; Cotgreave, Ian A.; Arrigo, André-Patrick; Orrenius, Sten
Enhanced cell survival and resistance to apoptosis during thermotolerance correlates with an increased expression of heat shock proteins (Hsps). Here we present additional evidence in support of the hypothesis that the induction of Hsp27 and Hsp72 during acquired thermotolerance in Jurkat T-lymphocytes prevents apoptosis. In thermotolerant cells, Hsp27 was shown to associate with the mitochondrial fraction, and inhibition of Hsp27 induction during thermotolerance in cells transfected with hsp27 antisense potentiated mitochondrial cytochrome c release after exposure to various apoptotic stimuli, despite the presence of elevated levels of Hsp72. Caspase activation and apoptosis were inhibited under these conditions. In vitro studies...
32.
Human cyclophilin 40 is a heat shock protein that exhibits altered intracellular localization following heat shock - Mark, Peter J.; Ward, Bryan K.; Kumar, Premlata; Lahooti, Hooshang; Minchin, Rodney F.; Ratajczak, Thomas
The unactivated steroid receptors are chaperoned into a conformation that is optimal for binding hormone by a number of heat shock proteins, including Hsp90, Hsp70, Hsp40, and the immunophilin, FKBP52 (Hsp56). Together with its partner cochaperones, cyclophilin 40 (CyP40) and FKBP51, FKBP52 belongs to a distinct group of structurally related immunophilins that modulate steroid receptor function through their association with Hsp90. Due to the structural similarity between the component immunophilins, FKBP52 and cyclophilin 40, we decided to investigate whether CyP40 is also a heat shock protein. Exposure of MCF-7 breast cancer cells to elevated temperatures (42°C for 3 hours) resulted...
33.
The hsp60B gene of Drosophila melanogaster is essential for the spermatid individualization process - Timakov , Benjamin; Zhang, Ping
The 60-kDa heat shock protein family (Hsp60) is found in prokaryotes, mitochondria, and chloroplasts. The Hsp60 proteins promote proper protein folding by preventing aggregation. In Drosophila melanogaster, the hsp60 gene is essential for a variety of developmental processes, beginning at early embryogenesis. In this study we show that an additional member of the Drosophila hsp60 gene family, hsp60B, is essential in male fertility. In males homozygous for a mutation of the hsp60B gene, developmental processes appeared normal throughout most of spermatogenesis, including spermatocyte growth, meiosis, and spermatid elongation. At these stages, mitochondria also displayed a differentiation process similar to wild-types....
34.
Regulation of the Hsp90-binding immunophilin, cyclophilin 40, is mediated by multiple sites for GA-binding protein (GABP) - Kumar, Premlata; Ward, Bryan K.; Minchin, Rodney F.; Ratajczak, Thomas
Within steroid receptor heterocomplexes the large tetratricopeptide repeat-containing immunophilins, cyclophilin 40 (CyP40), FKBP51, and FKBP52, target a common interaction site in heat shock protein 90 (Hsp90) and act coordinately with Hsp90 to modulate receptor activity. The reversible nature of the interaction between the immunophilins and Hsp90 suggests that relative cellular abundance might be a key determinant of the immunophilin component within steroid receptor complexes. To investigate CyP40 gene regulation, we have isolated a 5-kilobase (kb) 5?-flanking region of the human gene and demonstrated that a ?50 base pair (bp) sequence adjacent to the transcription start site is essential for CyP40...
36.
Presence of antibody against the inducible Hsp71 in patients with acute heat-induced illness - Wu, Tangchun; Chen, Sheng; Xiao, Chengfeng; Wang, Changlai; Pan, Qin; Wang, Zizheng; Xie, Meiyun; Mao, Zhicheng; Wu, Yang; Tanguay, Robert M.
Antibodies against heat shock or stress proteins (Hsps) have been reported in a number of diseases in which they may be involved in the pathogenesis of the disease or may be of use for prognosis. Heat-induced diseases, such as heat cramps, heat exhaustion, or heat stroke, are frequent in hot working or living environments. There are still few investigations on the presence and possible significance of autoantibodies against Hsps in heat-induced illnesses. Using an immunoblotting technique with recombinant human Hsps, we analyzed the presence and titers of antibodies against Hsp60, Hsp71, and Hsp90?, and Hsp90? in a group of 42...
37.
The inducible Hsp70 as a marker of tumor immunogenicity - Clark, Paul R.; Ménoret, Antoine
Growing evidence indicates that the stress response in general and heat shock proteins (Hsps) in particular have a profound impact on tumor immunogenicity. In this study, we show that tumor cells subjected to a nonlethal heat shock stress are unable to form tumors in syngenic mice, whereas they do so in athymic nude mice. Moreover, heat-shocked MethA immunity is tumor specific. Enhancement of T-cellmediated immunogenicity correlates with the expression of the inducible Hsp70 but not the constitutive Hsc70. These observations have a bearing on the proposed functional role of Hsp-peptide association in antigen processing and presentation by major histocompatibility complex...
38.
Influence of trehalose on the molecular chaperone activity of p26, a small heat shock/?-crystallin protein - Viner, Rosa I.; Clegg, James S.
Encysted embryos of the primitive crustacean Artemia franciscana are among the most resistant of all multicellular eukaryotes to environmental stress, in part due to massive amounts of a small heat shock/?-crystallin protein (p26) that acts as a molecular chaperone. These embryos also contain very large amounts of the disaccharide trehalose, well known for its ability to protect macromolecules and membranes against damage due to water removal and temperature extremes. Therefore, we looked for potential interactions between trehalose and p26 in the protection of a model substrate, citrate synthase (CS), against heat denaturation and aggregation and in the restoration of activity...
39.
The nuclear matrix is a thermolabile cellular structure - Lepock, James R.; Frey, Harold E.; Heynen, Miriam L.; Senisterra, Guillermo A.; Warters, Raymond L.
Heat shock sensitizes cells to ionizing radiation, cells heated in S phase have increased chromosomal aberrations, and both Hsp27 and Hsp70 translocate to the nucleus following heat shock, suggesting that the nucleus is a site of thermal damage. We show that the nuclear matrix is the most thermolabile nuclear component. The thermal denaturation profile of the nuclear matrix of Chinese hamster lung V79 cells, determined by differential scanning calorimetry (DSC), has at least 2 transitions at Tm = 48°C and 55°C with an onset temperature of approximately 40°C. The heat absorbed during these transitions is 1.5 cal/g protein, which is...
40.
Activation of human monocyte cell line U937 via cell surface calreticulin - Cho, Jang-Hyun; Homma, Koichi J.; Kanegasaki, Shiro; Natori, Shunji
U937 cells were found to be activated by an antibacterial peptide, KLKLLLLLKLK-NH2 (L5), to generate superoxide anion (O2?)-like peripheral neutrophils. However, the state of cell surface calreticulin, a possible receptor for L5, was suggested to differ between neutrophils and U937 cells. Unlike the former, the latter ones were activated by anti-C-domain peptide antibody of calreticulin even in the absence of L5 and generated O2? in a GTP-binding protein (G-protein)-dependent manner.
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