Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Heating”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed2006

Induction of the heat shock pathway during hypoxia requires regulation of heat shock factor by hypoxia-inducible factor-1.

Activation of heat shock proteins (Hsps) is critical to adaptation to low oxygen levels (hypoxia) and for enduring the oxidative stress of reoxygenation. Hsps are known to be regulated by heat shock factor (Hsf), but our results demonstrate an unexpected regulatory link between the oxygen-sensing and heat shock pathways. Hsf transcription is up-regulated during hypoxia due to direct binding by hypoxia-inducible factor-1 (HIF-1) to HIF-1 response elements in an Hsf intron. This increase in Hsf transcripts is necessary for full Hsp induction during hypoxia and reoxygenation. The HIF-1-dependent increase in Hsps has a functional impact, as reduced production of Hsps decreases viability of adult flies exposed to hypoxia and reoxygenation. Thus, HIF-1 control of Hsf transcriptional levels is a regulatory mechanism for sensitizing heat shock pathway activity in order to maximize production of protective Hsps. This cross-regulation represents a mechanism by which the low oxygen response pathway has assimilated complex new functions by regulating the key transcriptional activator of the heat shock pathway.

Animals↗
PubMed2002

The effect of early-age food restriction on heat shock protein 70 response in heat-stressed female broiler chickens.

1. This study was conducted to determine the effect of early-age food restriction on heat shock protein (hsp) 70 synthesis in the brains of female broiler chickens exposed to high ambient temperatures. 2. Chicks were brooded for 3 weeks and then maintained at 24+/-1 degrees C. 3. On d 0, chicks were assigned to one of 4 feeding regimens; each regimen was applied to 4 cages of chicks. The regimens were: (1) ad libitum feeding (AL); (2) 80% food restriction at 4, 5 and 6 d of age (F80); (3) 60% food restriction at 4, 5, and 6 d of age (F60); and (4) 40% food restriction at 4, 5 and 6 d of age (F40). From d 35 to d 41, all chicks were subjected to 38+/-1 degrees C for 2 h/d. 4. One day following food restriction (d 7), hsp 70 expression in the brain samples of F60 and F40 chicks was augmented but not those fed AL and F80. 5. Prior to the heat challenge (d 35), all chicks had similar hsp 70 response. Irrespective of feeding regimen, there was a marked increase in hsp 70 expression after 4 d of heat treatment (d 38). Following 7 d of heat exposure (d 41), except for the F60 chicks, the augmented hsp 70 expression in the brains of AL, F80 and F40 birds was not maintained. 6. Enhancement of hsp 70 expression was noted in birds subjected to F60, but not AL, F80 or F40, throughout the period of heat exposure.

Animals↗
PubMed1990

The differentially expressed 16-kD heat shock genes of Caenorhabditis elegans exhibit differential changes in chromatin structure during heat shock.

The 16-kD heat shock genes of Caenorhabditis elegans are encoded by four highly similar genes, arranged as divergently transcribed pairs. In spite of the high level of identity that exists between the HSP16 genes, after 2 hr of heat shock the mRNA from one locus accumulates at 7-14 times the level of that from the other locus. To determine if differential HSP16 gene transcriptional activity contributes to these differences, we examined the chromatin structure of the HSP16 genes in nonshocked embryos and in embryos undergoing both the initial phases of heat shock and after 2 hr of heat shock. To carry out these studies, we developed a nuclei isolation procedure that has allowed us to prepare large amounts of nuclei from C. elegans embryos, larvae, and adults that are essentially free of endogenous nuclease and protease activities and appear to be an excellent substrate for investigating chromatin structure in C. elegans. This procedure has enabled us to report the first observations of C. elegans basic chromatin structure, as well as characterize HSP16 chromatin structure in detail. The data suggest that differential HSP16 RNA accumulation following 2 hr of heat shock appears to be correlated with a change in the chromatin structure of one of the HSP16 loci to a preinduction, transcriptionally inactive configuration.

Animals↗
PubMed1995

Binding of heat shock factor to and transcriptional activation of heat shock genes in Drosophila.

Heat shock factor (HSF) binds to heat shock elements (HSEs) and the binding can be highly cooperative. Here we report an analysis of binding of Drosophila HSF to both native and synthetic heat shock regulatory regions. We find that cooperative binding of HSF requires close proximity, rather than helical alignment, of HSEs. Two or more trimeric HSEs organized as contiguous 5 bp units show much higher levels of cooperativity than multiple but separated HSEs. We discuss these in vitro observations in the context of the in vivo status of heat shock genes under mild and full heat shock conditions. Finally, we show that the DNA binding and trimerization domains alone may be sufficient for the full level of binding cooperativity between HSF trimers. This last result suggests that close proximity of HSEs for cooperative binding of HSF is a result of protein-protein interactions near the point of DNA contact.

Animals↗
PubMed1994

The coagulopathy of heat stroke: alterations in coagulation and fibrinolysis in heat stroke patients during the pilgrimage (Haj) to Makkah.

Haemostatic measurements were undertaken in 132 patients diagnosed with heat stroke during the pilgrimage to Makkah, in two successive summers of 1989-90. The control group comprised 49 patients, all pilgrims, with a wide range of clinical conditions, but without hyperpyrexia or deranged haemostasis. Heat stroke patients showed (i) significant prolongation of the prothrombin (PT), activated partial thromboplastin (aPTT) and thrombin times (TT) but normal reptilase time (RT); (ii) significant reduction in plasma levels of antithrombin III (AT-III), factor V, proteins C and S, plasminogen activator inhibitor (PAI) and platelet count; (iii) increase in plasma factor VIII, tissue plasminogen activator (t-PA) and serum FDP; (iv) no significant changes in plasma fibrinogen, plasminogen, alpha 2-antiplasmin and factors VII and X. Heat stroke patients were then grouped into those with and those without bleeding symptoms. Bleeders showed greater prolongation of the PT, aPTT and TT and significant reductions in fibrinogen, AT-III, factors V, VIII and X, plasminogen, alpha 2-antiplasmin and platelet count. Logistic regression and discriminant analysis showed that AT-III was the parameter associated most with heat stroke and reliable enough to predict its occurrence, whether or not bleeding occurred. The results indicate that activation of the haemostatic mechanism, consumptive in nature, regularly accompanies heat stroke and highlights the physiological role of AT-III in checking this activation process.

Adult↗
PubMed1998

The small, methionine-rich chloroplast heat-shock protein protects photosystem II electron transport during heat stress.

Evidence suggests that the small chloroplast heat-shock protein (Hsp) is involved in plant thermotolerance but its site of action is unknown. Functional disruption of this Hsp using anti-Hsp antibodies or addition of purified Hsp to chloroplasts indicated that (a) this Hsp protects thermolabile photosystem II and, consequently, whole-chain electron transport during heat stress; and (b) this Hsp completely accounted for heat acclimation of electron transport in pre-heat-stressed plants. Therefore, this Hsp is a major adaptation to acute heat stress in plants.

Acclimatization↗
PubMed1983

Regulation of heat-shock protein synthesis in chicken muscle culture during recovery from heat shock.

Exposure of chick myotube cultures to a temperature (45 degrees C) higher than their normal growing temperature (37 degrees C) caused extensive synthesis of three major polypeptides of Mr = 25 000, 65 000 and 81 000 referred to as 'heat-shock polypeptides' (hsps). When these cells were allowed to recover from heat-shock treatment at 37 degrees C for 6-8 h, the rate of accumulation of isotope into the 65 000-Mr and 81 000-Mr hsps declined to levels comparable to those in control cultures maintained at 37 degrees C. However, incorporation of isotope in the 25 000-Mr hsp continued at an elevated rate for a longer period than the 65 000-Mr and 81 000-Mr hsps. When heat-shocked cells were allowed to recover at 37 degrees C in the presence of actinomycin D to block new mRNA synthesis, the hsp synthesis as measured by the incorporation of radioactive isotope in these polypeptides continued at levels comparable to those in heat-shocked cells prior to recovery. The block of recovery by actinomycin D was due to the presence of a greater amount of functional hsp mRNAs in the polysomes as compared to untreated controls. The role of competition between the mRNAs for hsps and normal cellular proteins for the translation machinery in regulating protein synthesis during the recovery from heat shock has been discussed.

Animals↗
PubMed1997

Heat acclimation and heat stress have different effects on cholinergic muscarinic receptors.

In this brief report we have proved that membranal changes take place upon short-term heat acclimation. These changes may switch on a cascade of transient acclimatory compensatory responses as well as long-term processes. The changes observed in the MR profile are heat acclimation specific, and differ from those observed upon heat stress. These bring about functional changes in the signal transduction pathway for water secretion in the submaxillary salivary gland. A recovery period from heat stress, similar to STHA, leads to MR upregulation and decreased binding affinity. This response, however, is more pronounced than that observed upon STHA. The functional importance of the phenomenon is unclear. However, it could designate a novel component of the heat shock response.

Acclimatization↗
PubMed1984

Heat shock and heat stroke proteins observed during germination of the blastoconidia of Candida albicans.

Cytoplasmic proteins extracted from germinating yeast cells of Candida albicans were analyzed by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis. Similar extracts from a recently isolated nongerminating variant were compared with those from the parent. Five proteins (18, 22, 40, 68, and 70 kilodaltons [kd]) behaved as heat-shock proteins in that they appeared or were greatly increased in amount within 20 min of a temperature shift from 23 to 37 degrees C. Three of the five (40, 68, and 70 kd) were undetected in cells incubated at 23 degrees C, appeared within 20 min of temperature shift, and were no longer detected after 120 min at 37 degrees C, whereas two of the five (18 and 22 kd) were present in small amounts at 23 degrees C, increased greatly after shift, and persisted for 120 min at the elevated temperature. Two temperature-repressed (heat-stroke) proteins (30 and 88 kd) were also observed. The same heat-shock and heat-stroke proteins were also found in the nongerminating variant. The differences in proteins expressed by blastoconidia and by germlings appeared to be related to the heat-shock response.

Candida albicans↗
PubMed1992

Characterization of the heat shock response in Brucella abortus and isolation of the genes encoding the GroE heat shock proteins.

In an effort to define the heat shock response in the bovine intracellular pathogen Brucella abortus, a rough variant lacking extensive lipopolysaccharide was pulse-labeled with [35S]methionine following exposure to elevated temperatures. The major heat shock proteins observed following sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography migrate at 70, 62, 18, and 10 kDa. The maximum response was observed between 42 and 46 degrees C and within 2 to 3 h of the shif in temperature and varied slightly for the different proteins. Accumulation of the 62-kDa heat shock protein (62-kDa Hsp) was observed to continue for up to 5 h following the shift in temperature. In an effort to better define the heat shock response and its potential relationship with protective immunity, genes encoding the major heat shock proteins were isolated from recombinant libraries constructed from B. abortus S19 and S2308 and sequenced. The 62-kDa Hsp shares more than 60% amino acid homology with members of the GroEL family and is immunoprecipitated with polyclonal antibodies to Escherichia coli GroEL and monoclonal antibodies to mycobacterial Hsp 65. Western blot (immunoblot) analysis with pooled sera from vaccinated and infected cattle revealed that the 62-kDa Hsp is a predominantly recognized antigen. The roles of these gene products during environmental stress and in protective immunity against brucellosis are under investigation.

Amino Acid Sequence↗
PubMed1986

In vitro effect of the Escherichia coli heat shock regulatory protein on expression of heat shock genes.

In Escherichia coli, the ability to elicit a heat shock response depends on the htpR gene product. Previous work has shown that the HtpR protein serves as a sigma factor (sigma 32) for RNA polymerase that specifically recognizes heat shock promoters (A.D. Grossman, J.W. Erickson, and C.A. Gross Cell 38:383-390, 1984). In the present study we showed that sigma 32 synthesized in vitro could stimulate the expression of heat shock genes. The in vitro-synthesized sigma 32 was found to be associated with RNA polymerase. In vivo-synthesized sigma 32 was also associated with RNA polymerase, and this polymerase (E sigma 32) could be isolated free of the standard polymerase (E sigma 70). E sigma 32 was more active than E sigma 70 with heat shock genes; however, non-heat-shock genes were not transcribed by E sigma 32. The in vitro expression of the htpR gene required E sigma 70 but did not require E sigma 32.

Chromatography, Gel↗
PubMed1993

Heat shock applied early in sporulation affects heat resistance of Bacillus megaterium spores.

Cells of Bacillus megaterium 27 were challenged by a 30-min heat shock at 45 degrees C during various sporulation stages and then shifted back to a temperature permissive for sporulation (27 degrees C), at which they developed spores. Heat shock applied at 120 min after the end of the exponential phase induced synthesis of heat shock proteins (HSPs) in the sporangia and delayed the inactivation of spores at 85 degrees C. Several HSPs, mainly HSP 70, could be detected in the cytoplasm of these spores. An analogous HSP, the main HSP induced by increased temperature during growth, belongs to the GroEL group according to its N-terminal sequence. The identity of this protein was confirmed by Western blot (immunoblot) analysis with polyclonal antibodies against B. subtilis GroEL. Sporangia treated by heat shock immediately or 240 min after exponential phase also synthesized HSPs, but none of them could be detected in the spores in an appreciable amount. These spores showed only a slightly increased heat resistance.

Amino Acid Sequence↗
PubMed1998

Heat shock element architecture is an important determinant in the temperature and transactivation domain requirements for heat shock transcription factor.

The baker's yeast Saccharomyces cerevisiae possesses a single gene encoding heat shock transcription factor (HSF), which is required for the activation of genes that participate in stress protection as well as normal growth and viability. Yeast HSF (yHSF) contains two distinct transcriptional activation regions located at the amino and carboxyl termini. Activation of the yeast metallothionein gene, CUP1, depends on a nonconsensus heat shock element (HSE), occurs at higher temperatures than other heat shock-responsive genes, and is highly dependent on the carboxyl-terminal transactivation domain (CTA) of yHSF. The results described here show that the noncanonical (or gapped) spacing of GAA units in the CUP1 HSE (HSE1) functions to limit the magnitude of CUP1 transcriptional activation in response to heat and oxidative stress. The spacing in HSE1 modulates the dependence for transcriptional activation by both stresses on the yHSF CTA. Furthermore, a previously uncharacterized HSE in the CUP1 promoter, HSE2, modulates the magnitude of the transcriptional activation of CUP1, via HSE1, in response to stress. In vitro DNase I footprinting experiments suggest that the occupation of HSE2 by yHSF strongly influences the manner in which yHSF occupies HSE1. Limited proteolysis assays show that HSF adopts a distinct protease-sensitive conformation when bound to the CUP1 HSE1, providing evidence that the HSE influences DNA-bound HSF conformation. Together, these results suggest that CUP1 regulation is distinct from that of other classic heat shock genes through the interaction of yHSF with two nonconsensus HSEs. Consistent with this view, we have identified other gene targets of yHSF containing HSEs with sequence and spacing features similar to those of CUP1 HSE1 and show a correlation between the spacing of the GAA units and the relative dependence on the yHSF CTA.

Base Sequence↗
PubMed1986

Effects of cycloheximide on thermotolerance expression, heat shock protein synthesis, and heat shock protein mRNA accumulation in rat fibroblasts.

A single hyperthermic exposure can render cells transiently resistant to subsequent high temperature stresses. Treatment of rat embryonic fibroblasts with cycloheximide for 6 h after a 20-min interval at 45 degrees C inhibits protein synthesis, including heat shock protein (hsp) synthesis, and results in an accumulation of hsp 70 mRNA, but has no effect on subsequent survival responses to 45 degrees C hyperthermia. hsp 70 mRNA levels decreased within 1 h after removal of cycloheximide but then appeared to stabilize during the next 2 h (3 h after drug removal and 9 h after heat shock). hsp 70 mRNA accumulation could be further increased by a second heat shock at 45 degrees C for 20 min 6 h after the first hyperthermic exposure in cycloheximide-treated cells. Both normal protein and hsp synthesis appeared increased during the 6-h interval after hyperthermia in cultures which received two exposures to 45 degrees C for 20 min compared with those which received only one treatment. No increased hsp synthesis was observed in cultures treated with cycloheximide, even though hsp 70 mRNA levels appeared elevated. These data indicate that, although heat shock induces the accumulation of hsp 70 mRNA in both normal and thermotolerant cells, neither general protein synthesis nor hsp synthesis is required during the interval between two hyperthermic stresses for Rat-1 cells to express either thermotolerance (survival resistance) or resistance to heat shock-induced inhibition of protein synthesis.

Animals↗
PubMed1987

Heat and sodium arsenite act synergistically on the induction of heat shock gene expression in Xenopus laevis A6 cells.

Heat shock protein (HSP) synthesis was studied in the Xenopus epithelial cell line A6 in response to heat and sodium arsenite, either singly or together. Temperatures of 33-35 degrees C consistently brought about the synthesis of HSPs at 87, 73, 70, 54, 31, and 30 kilodaltons (kDa), whereas sodium arsenite at 25-100 microM induced the synthesis of HSPs at 73 and 70 kDa. In cultures exposed to 10 microM sodium arsenite at 30 degrees C, HSP synthesis in the 68- to 73-kDa and 29- to 31-kDa regions was much greater than the HSP synthesis in response to each treatment individually. RNA dot blot analysis using homologous genomic subclones revealed that heat shock induced the accumulation of HSP 70 and 30 mRNAs. The sizes of the HSP 70 and 30 mRNAs determined by Northern hybridization were 2.7 and 1.5 kilobases, respectively. Sodium arsenite (10-100 microM) also induced the accumulation of both HSP 70 and 30 mRNAs. Finally, a mild heat shock (30 degrees C) plus a low concentration of sodium arsenite (10 microM) acted synergistically on HSP 70 and 30 mRNA accumulation in A6 cells. Thus sodium arsenite and heat act synergistically at the level of both HSP synthesis and HSP mRNA accumulation.

Animals↗
PubMed1988

Heat shock gene expression in Xenopus laevis A6 cells in response to heat shock and sodium arsenite treatments.

Continuous exposure of a Xenopus laevis kidney epithelial cell line, A6, to either heat shock (33 degrees C) or sodium arsenite (50 microM) resulted in transient but markedly different temporal patterns of heat-shock protein (HSP) synthesis and HSP 70 and 30 mRNA accumulation. Heat-shock-induced synthesis of HSPs was detectable within 1 h and reached maximum levels by 2-3 h. While sodium arsenite induced the synthesis of some HSPs within 1 h, maximal HSP synthesis did not occur until 12 h. The pattern of HSP 70 and 30 mRNA accumulation was similar to the response observed at the protein level. During recovery from heat shock, a coordinate decline in HSPs and HSP 70 and 30 mRNA was observed. During recovery from sodium arsenite, a similar phenomenon occurred during the initial stages. However, after 6 h of recovery, HSP 70 mRNA levels persisted in contrast to the declining HSP 30 mRNA levels. Two-dimensional polyacrylamide gel electrophoresis revealed the presence of 5 HSPs in the HSP 70 family, of which two were constitutive, and 16 different stress-inducible proteins in the HSP 30 family. In conclusion, heat shock and sodium arsenite induce a similar set of HSPs but maximum synthesis of the HSP is temporally separated by 12-24 h.

Animals↗
PubMed1993

Heat stress regulates the human 70-kDa heat-shock gene through the 3'-untranslated region.

Cells respond to a variety of stresses by synthesizing a family of proteins termed heat-shock proteins (HSP). Recently, the 3'-untranslated regions (UTRs) of some mRNAs have been shown to be important in the posttranscriptional regulation of protein production. Therefore, we hypothesized that heat could regulate HSP70 production through the HSP70 3'-UTR, in addition to its known effects on transcription. To test this hypothesis, cells were transfected with either a plasmid containing sequences encoding the human HSP70 or beta-globin 3'-untranslated region placed downstream of a chloramphenicol acetyltransferase (CAT) reporter gene. In both plasmids, the CAT gene was driven by an SV40 promoter. Following heat stress, cells transfected with the CAT construct containing the HSP70 3'-UTR showed increased CAT activity relative to the beta-globin 3'-UTR construct. This effect paralleled increases in HSP70 mRNA and levels of the inducible HSP70 protein by Western blot. These studies identify a heat-induced mechanism of posttranscriptional control of HSP70 synthesis utilizing the HSP70 3'-UTR, which may be important in the cells ability to regulate the heat-shock response.

Base Sequence↗
PubMed1999

Heat stress induces ultrastructural changes in cutaneous capillary wall of heat-acclimated rock pigeon.

In heat-acclimated rock pigeons, cutaneous water evaporation is the major cooling mechanism when exposed at rest to an extremely hot environment of 50-60 degrees C. This evaporative pathway is also activated in room temperature by a beta-adrenergic antagonist (propranolol) or an alpha-adrenergic agonist (clonidine) and inhibited by a beta-adrenergic agonist (isoproterenol). In contrast, neither heat exposure nor drug administration activates cutaneous evaporation in cold-acclimated pigeons. To elucidate the mechanisms underlying this phenomenon, we studied the role of the ultrastructure and permeability of the cutaneous vasculature. During both heat stress and the administration of propranolol and clonidine, we observed increased capillary fenestration and endothelial gaps. Similarly, propranolol increased the extravasation of Evans blue-labeled albumin in the skin tissue. We concluded that heat acclimation reinforces a mechanism by which the activation of adrenergic signal transduction pathways alters microvessel permeability during heat stress. Consequently the flux of plasma proteins and water into the interstitial space is accelerated, providing an interstitial source of water for sustained cutaneous evaporative cooling.

Acclimatization↗