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PubMed1982

Drosophila gene related to the major heat shock-induced gene is transcribed at normal temperatures and not induced by heat shock.

A gene related to the major heat shock-induced (hsp70) gene of Drosophila has been isolated from the sibling species D. melanogaster and D. simulans. This heat shock-cognate (hsc70) gene is present at cytological locus 70C. The primary sequence of approximately one-third of the protein-coding region has been compared with that of the hsp70 gene; 72% homology of the base sequence and 74% homology of the deduced amino acid sequence was found. In the codon specifying amino acid 66, the hsc70 gene contains an insertion of 1.7 kilobases; the hsp70 genes contain no intervening sequences. The sequence at the 5' and 3' junctions of the insertion is similar to that found in many intervening sequences. cDNA extension experiments indicate that the hsc70 gene is transcribed at normal temperatures in adult flies and that transcription is not enhanced by heat treatment.

Amino Acid Sequence↗
PubMed1984

Proteins related to the mouse L-cell major heat shock protein are synthesized in the absence of heat shock gene expression.

Heat shock of mouse L cells induces the synthesis of two polypeptides of Mrs 68,000 and 89,000. Using a fragment of a cloned gene encoding the Drosophila melanogaster Mr 70,000 heat shock protein (hsp70), we have shown that this protein has been highly conserved during eukaryotic evolution. We extended this observation by probing at low stringency for the expression in mouse L cells of RNA homologous to the Drosophila hsp70 gene. In addition to the RNA encoding the inducible Mr 68,000 heat shock protein (hsp68), there are mouse mRNAs encoding proteins of Mrs 70,000 and 74,000 that are homologous to the Drosophila hsp70 gene. The Mrs 70,000 and 74,000 proteins and their mRNAs are abundant components of unstressed mouse L cells. These constituitively expressed proteins are unique polypeptides in contrast to the several isoelectric point variants of the inducible hsp68. We do not detect hsp68 or its mRNA in unstressed L cells. In addition to the mRNAs corresponding to hsp68 and the Mrs 74,000 and 70,000 proteins, we detect a fourth RNA homologous to the Drosophila hsp70 gene but whose protein product has not been identified. Our results suggest that the hsp68 gene of mouse L cells is a member of a multigene family and that the individual family members are distinguishable by their degree of similarity but show differences in the regulation of their expression.

Animals↗
PubMed1990

Decreased expression of heat shock protein 70 mRNA and protein after heat treatment in cells of aged rats.

The effect of aging on the induction of heat shock protein 70 (HSP70)-encoding gene expression by elevated temperatures was studied in cultures of lung- or skin-derived fibroblasts from young (5 mo) and old (24 mo) male Wistar rats. Although the kinetics of the heat shock response were found to be similar in the two age groups, we observed lower levels of induction of HSP70 mRNA and HSP70 protein in confluent primary lung and skin fibroblast cultures derived from aged animals. Additional experiments with freshly excised lung tissue showed a similar age-related decline in the heat-induced expression of HSP70.

Aging↗
PubMed2005

Preheating accelerates mitogen-activated protein (MAP) kinase inactivation post-heat shock via a heat shock protein 70-mediated increase in phosphorylated MAP kinase phosphatase-1.

Heat shock (HS) activates mitogen-activated protein (MAP) kinases. Although prior exposure to nonlethal HS makes cells refractory to the lethal effect of a subsequent HS, it is unclear whether this also occurs in MAP kinase activation. This study was undertaken to evaluate the effect of a heat pretreatment on MAP kinase activation by a subsequent HS and to elucidate its possible mechanism. Preheating did not make BEAS-2B cells refractory to extracellular signal-regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK) activation by a second HS but accelerated their inactivation after HS. The rapid inactivation of ERK and JNK was dependent on de novo protein synthesis and associated with the up-regulation of heat shock protein 70 (HSP70). Moreover, the inhibition of phosphatase activity reversed this rapid inactivation. MAP kinase phosphatase-1 (MKP-1) expression was increased by HS, and the presence of its phosphorylated form (p-MKP-1) correlated with the observed rapid ERK and JNK inactivation. Blocking induction of p-MKP-1 with antisense MKP-1 oligonucleotides suppressed the rapid inactivation of ERK and JNK in preheated cells. HSP70 overexpression caused the early phosphorylation of MKP-1. Moreover, MKP-1 phosphorylation and the rapid inactivation of ERK were inhibited by blocking HSP70 induction in preheated cells. In addition, MKP-1 was insolubilized by HS, and HSP70 associated physically with MKP-1, suggesting that a chaperone effect of HSP70 might have caused the early phosphorylation of MKP-1. These results indicate that preheating accelerated MAP kinase inactivation after a second HS and that this is related to a HSP70-mediated increase in p-MKP-1.

Adenoviridae↗
PubMed2003

Inverse response of leukocyte heat shock proteins and DNA damage to exercise and heat.

Elevated ambient temperature may exert an additional impact on the exercise-induced expression of heat shock proteins (HSP) and DNA damage in leukocytes. The protective functions of HSP include antioxidative and antiapoptotic effects and may prevent damage to DNA. Twelve athletes completed a continuous run (75% VO2max) on the treadmill, six at 28 degrees C and six at 18 degrees C room temperature. Leukocyte expression of HSP27 and inducible HSP70 was analyzed on mRNA- (RT-PCR) and protein-level (flow cytometry), while DNA damage was quantified by the comet assay. High ambient temperature induced an additional accumulation of HSP-mRNA and -protein in leukocytes compared with the exercise-induced expression at 18 degrees C. HSP27 showed a special heat sensitivity. Surprisingly, the increase of DNA damage was less pronounced after exercise at 28 degrees C compared to 18 degrees C although heat shock in vitro clearly induced DNA damage. The inverse relation between HSP and DNA damage may indicate functions of HSP which protect against exercise-induced DNA-damage in terms of thermotolerance or apoptosis.

Adaptation, Physiological↗
PubMed1983

Is the major Drosophila heat shock protein present in cells that have not been heat shocked?

When eukaryotic cells are exposed to elevated temperatures they respond by vigorously synthesizing a small group of proteins called the heat shock proteins. An essential element in defining the role of these proteins is determining whether they are unique to a stressed state or are also found in healthy, rapidly growing cells at normal temperatures. To date, there have been conflicting reports concerning the major heat-induced protein of Drosophila cells, HSP 70. We report the development of monoclonal antibodies specific for this protein. These antibodies were used to assay HSP 70 in cells incubated under different culture conditions. The protein was detectable in cells maintained at normal temperatures, but only when immunological techniques were pushed to the limits of their sensitivity. To test for the possibility that these cells contain a reservoir of protein in a cryptic antigenic state (i.e., waiting posttranslational modification for use at high temperature), we treated cells with cycloheximide or actinomycin D immediately before heat shock. HSP 70 was not detected in these cells. Finally, we tested for the presence of a reservoir of inactive messages by using a high stringency hybridization of 32P-labeled cloned gene sequences to electrophoretically separated RNAs. Although HSP 70 mRNA was detectable in rapidly growing cells, it was present at less than 1/1,000th the level achieved after induction.

Animals↗
PubMed1994

Comparison of heated water-filled mattress and space-heated room with infant incubator in providing warmth to low birthweight newborns.

BACKGROUND: Prevention of excessive heat loss is fundamental to survival of low birthweight (LBW) newborns. The use of infant incubators (INC) is beyond the resources of developing countries, and the space-heated room (SHR) has been the only feasible means of providing thermal protection to LBW newborns. Recently a thermostatically controlled, heated, water-filled mattress (HWM) has been developed as a potentially simpler and affordable alternative. METHODS: In a neonatal care ward of a referral hospital in Addis Ababa, 62 < 1 week old newborns, weighing 1000-1999 g, who were well enough to breathe comfortably in room air and tolerate oral feeds, were randomly allocated to INC, HWM or SHR and followed for 3 weeks. The level of cold stress as assessed by core-to-skin temperature gradient and the rate of weight gain were the main outcome measures. RESULTS: The level of cold stress was lowest in the INC, intermediate in the HWM and highest in the SHR. Relative to the INC group, the HWM group exhibited a modest increase in the occurrence of clinically important hyperthermic or hypothermic deviations in core temperature (rate ratio (RR) = 2.3; 95% CI: 0.9, 5.6), and the SHR displayed a definite increase (RR = 4.0; 95% CI: 1.7, 9.3). During the first week, the rate of weight gain was highest in the INC group (3.6 g/kg/day), lowest in the SHR group (-2.3 g/kg/day, P < 0.05 versus INC) and intermediate in the HWM group (1.6 g/kg/day, P > 0.1 versus INC). CONCLUSION: Care in the SHR produced clinically significant thermal stresses and was associated with deficient early neonatal growth, but the use of HWM may constitute a feasible and clinically acceptable alternative in providing warmth to LBW newborns during the neonatal period.

Beds↗
PubMed1994

Cloning and expression of cDNA coding for a new allergen from the house dust mite, Dermatophagoides farinae: homology with human heat shock cognate proteins in the heat shock protein 70 family.

An immunoreactive clone, which shares no homology with the major allergens, Der f I and Der f II, was isolated by screening of a Dermatophagoides farinae cDNA library with rabbit antiserum raised against an extract of the house dust mite and sera from patients with mite allergy. The deduced amino acid sequence of the cDNA of the clone is significantly homologous, up to 65.5%, to the carboxyl-terminal region of the heat shock cognate protein (hsc) 71 in the heat shock protein (hsp) 70 family. A pool of the recombinant protein-specific IgE purified from mite-allergic sera recognized a 67 kDa protein on a blot of ATP-binding components partially purified from the mite body extract, while the antibody did not bind to the major allergens. We conclude that the recombinant protein, one of several important allergens, may be a protein in the heat shock protein 70 family from the house dust mite, D. farinae.

Allergens↗
PubMed1999

Transcriptional control of development, protein synthesis, and heat-induced heat shock protein 70 synthesis in 2-cell bovine embryos.

Experiments were performed to evaluate the role of transcription in early development of bovine embryos. Two transcription inhibitors-5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) and actinomycin D-were used to test whether 1) the inhibitors alter the rate of early embryonic development and protein synthesis, 2) heat shock increases the steady-state amounts of mRNA for the inducible form of heat shock protein 70 (HSP70) in embryos, and 3) this latter effect is blocked by transcription inhibitors. Addition of either DRB or actinomycin D to culture medium beginning 8 h postinsemination (hpi) reduced the proportion of oocytes that had undergone cleavage by 32-34 hpi. Both transcription inhibitors also reduced the proportion of cleaved embryos that reached the 4-cell stage by 32-34 hpi. Incorporation of (35)S-labeled amino acids into de novo synthesized protein by bovine 2-cell embryos was lower for embryos cultured with DRB. Using reverse transcription-polymerase chain reaction, HSP70 mRNA in 2- and 4-cell embryos was increased by exposure to 42 degrees C. Both inhibitors reduced amounts of HSP70 mRNA at 42 degrees C. Results indicate that bovine embryos can undergo transcription in response to heat shock as early as the 2-cell stage. Moreover, the observations that transcription inhibitors reduce rates of cleavage and early development point out the importance of transcription for development from the earliest period of embryonic life.

Animals↗
PubMed2002

Perceptual versus physiological heat strain during exercise-heat stress.

PURPOSE: The physiological strain index (PSI) has been proposed as a universally applicable measure of exercise-heat strain. Unknown is whether this index, based on normalized increases in core temperature and heart rate, is matched by its perceptual analog. METHODS: By using a similar mathematical construct to the PSI, the perceptions of thermal sensation and perceived exertion were combined, and the resultant index, PeSI, was compared with its physiological counterpart, denoted as PhSI, for the exercise-heat stress specific to this study. Twenty-six young and healthy subjects wore semi-impermeable clothing and walked (3.5 km.h(-1)) under hot conditions (40 degrees C and 30% RH) until exhaustion or when their core temperature reached 39.5 degrees C. Subjects were divided into two fitness groups [endurance trained (T) and untrained (U)] comprised of 10 men and 3 women each. U subjects had a higher level of body fatness (mean +/- SD 18.1 +/- 5.3 vs 12.6 +/- 4.5%; P=0.010) and a lower level of aerobic fitness ((.)VO(2max)= 43.6 +/- 3.8 +/- vs 59.0 +/- 6.2 mL.min(-1).kg(-1); P<0.001). RESULTS: During the first hour of exposure, there was no group difference in PhSI, yet T perceived their physiological strain (PeSI) lower than U (P=0.002). Further, the indices were not different for U whereas PhSI was higher than PeSI for T (P=0.008). At the end of the exposure, T had a higher value of PhSI than U (8.23 +/- 0.72 vs 6.74 +/- 1.47; = 0.002), but there was no group difference in PeSI. Although the indices were again not different for U, PhSI at the end was higher than PeSI for T (6.14 +/- 1.68; P<0.001). CONCLUSION: T underestimated and U consistently perceived their physiological strain, as defined by PhSI, in accordance with the measured increases in core temperature and heart rate throughout an exposure to uncompensable exercise-heat stress.

Adult↗
PubMed1984

Expression of a Drosophila heat shock protein in mammalian cells: transient association with nucleoli after heat shock.

We transformed mouse L cells with a cloned Drosophila hsp70 gene and obtained cells with either heat-inducible or constitutively expressed copies of the gene. The distribution of hsp70 in these cells was examined by indirect immunofluorescence with monoclonal antibodies specific to the Drosophila protein. In constitutive cells, hsp70 was present in both cytoplasm and nucleus. After heat shock, the nuclear hsp70 was transiently concentrated in nucleoli, from which it had previously been excluded; the cytoplasmic hsp70 moved to a perinuclear location, a result consistent with it being associated with intermediate filaments of the cytoskeleton. The nucleolar migration took several hours and was partly inhibited by actinomycin D, but was independent of protein synthesis; it may reflect binding to newly-synthesized rRNA. Drosophila hsp70 was also expressed from replicating plasmids in monkey COS cells, and was found to be concentrated in nuclei even at low temperature. Migration to nucleoli occurred after heat shock. These results indicate that a single protein can have multiple interactions with cellular components, and form the basis for future studies of these interactions by in vitro mutagenesis and expression of the hsp70 gene.

Animals↗
PubMed1992

The human heat shock protein hsp70 interacts with HSF, the transcription factor that regulates heat shock gene expression.

Transcriptional regulation of the human hsp70 gene in response to heat shock and other forms of physiological stress occurs through the activation of heat shock transcription factor (HSF). Exposure of cells to a heat shock temperature of 42 degrees C results in transient activation of HSF; its DNA-binding activity increases rapidly, plateaus, and attenuates, during which the intracellular levels of hsp70 increase. In an effort to understand whether HSF is regulated negatively by hsp70, we have examined whether HSF associates with hsp70. We show that activated HSF associates with hsp70 and that the interaction is detected as the levels of hsp70 increase in the cell. Addition of ATP and other hydrolyzable nucleotides results in the dissociation of hsp70 from HSF while nonhydrolyzable nucleotide analogs do not disrupt the complex. We demonstrate that exogenous recombinant wild-type hsp70 can associate with activated HSF, whereas no association is observed with an amino-terminal or a carboxy-terminal deletion mutant of hsp70. We also show that hsp70 blocks the in vitro activation of HSF from its cryptic non-DNA-binding state to a DNA-binding form; this inhibitory effect of hsp70 is abolished by ATP. We suggest that hsp70 may negatively regulate the activation of HSF.

Adenosine Triphosphate↗
PubMed2000

Nuclear export of heat shock and non-heat-shock mRNA occurs via similar pathways.

Several studies of the yeast Saccharomyces cerevisiae support differential regulation of heat shock mRNA (hs mRNA) and non-hs mRNA nuclear export during stress. These include the finding that hs mRNA export at 42 degrees C is inhibited in the absence of the nucleoporinlike protein Rip1p (also called Nup42p) (C. A. Saavedra, C. M. Hammell, C. V. Heath, and C. N. Cole, Genes Dev. 11:2845-2856, 1997; F. Stutz, J. Kantor, D. Zhang, T. McCarthy, M. Neville, and M. Rosbash, Genes Dev. 11:2857-2868, 1997). However, the results reported in this paper provide little evidence for selective non-hs mRNA retention or selective hs mRNA export under heat shock conditions. First, we do not detect a block to non-hs mRNA export at 42 degrees C in a wild-type strain. Second, hs mRNA export appears to be mediated by the Ran system and several other factors previously reported to be important for general mRNA export. Third, the export of non-hs mRNA as well as hs mRNA is inhibited in the absence of Rip1p at 42 degrees C. As a corollary, we find no evidence for cis-acting hs mRNA sequences that promote transport during heat shock. Taken together, our data suggest that a shift to 42 degrees C in the absence of Rip1p impacts a late stage of transport affecting most if not all mRNA.

Biological Transport↗
PubMed1997

Setting heat stress limits for acclimatised soldiers exercising in heat.

Heat illness is a recognised risk of military training. The Combat Fitness Test (CFT) has been identified as an activity that has been associated with heat casualties. The aim of this study was to establish whether a heat stress limit could be set for acclimatised soldiers performing the CFT by measuring the group mean rises in core temperature whilst performing the CFT at various environmental temperatures. The study showed that CFTs should not be undertaken when the start or expected end Wet Bulb Globe Test (WBGT) is greater than 25 degrees C if the group mean rise in core temperature is not to exceed 0.6 degree C (95% CI 0.2 degree C to 1 degree C).

Acclimatization↗
PubMed1996

Heat strain in protective clothing following hot-wet or hot-dry heat acclimation.

The purpose of the present study was to compare the heat strain while wearing nuclear, biological, and chemical (NBC) protective clothing following a hot-wet (HW) or hot-dry (HD) heat acclimation protocol. Twenty-two males were assigned to groups HW (n = 7), HD (n = 8), or control (C, n = 7). Subjects were evaluated during continuous treadmill walking while wearing lightweight combat clothing and during intermittent exercise while wearing the NBC protective clothing. While wearing Combat clothing, greater decreases in rectal temperature (Tre), mean skin temperature (Tsk), and heart rate were observed for both acclimation groups. For the NBC clothing trials, lower Tre, Tsk, and heart rates were observed only for group HW. The time required for Tre to increase 1.0 degrees C and 1.5 degrees C was significantly delayed for groups HW and HD. Sweat evaporation increased for HW, whereas no change was found for HD. The most significant changes in Tre, Tsk, and heart rate while wearing the NBC protective clothing occur following heat acclimation that involves wearing the clothing during exercise.

Acclimatization↗
PubMed1982

Intracellular translocation of cellular and heat shock induced proteins upon heat shock in Drosophila Kc cells.

The intracellular distribution of cellular and heat shock induced proteins (hsp) was studied during a heat shock to Drosophila Kc cells. The different hsp's are unequally distributed between the intracellular organelles; while hsp 84 shows an exclusive cytoplasmic location, hsp 70 is equally distributed between the nucleus and the cytoplasm. The low molecular weight (MW) hsp's 22--26 are mainly concentrated in the nuclear fraction. Hsp 34 also shows a preferential nuclear localization but differs from the 22-26 hsp group with regard to its solubility in salt. During the heat shock (HS) treatment, a major preexisting microsomal polypeptide of relative mass (Mr) 45 000 with some properties similar to cytoskeletal proteins is translocated to the nuclear pellet. This translocation does not occur during arsenite treatment which also induces the synthesis of some hsp's. Furthermore, the hsp's synthesized in response to this arsenite treatment do not become associated with the nucleus as during the HS. Consequently the nuclear translocation of the 45 000 Mr protein does not seem to be involved in the induction of the high MW group of hsp's. Furthermore, it suggests that the hsp's which are found in the nuclear pellet upon HS do not have a nuclear localization per se. It rather reflects a temperature-dependent translocation of certain cellular proteins and hsp to the nucleus during a HS.

Animals↗
PubMed2004

Identification of Xenopus heat shock transcription factor-2: conserved role of sumoylation in regulating deoxyribonucleic acid-binding activity of heat shock transcription factor-2 proteins.

Heat shock transcription factor (Hsf)-1 and Hsf2 are members of the heat shock factor (HSF) protein family involved in heat shock protein (hsp) gene regulation, a regulation that is critical for the ability of cells to survive exposure to stress conditions. Although the role of Hsf1 in binding and activating transcription of hsp gene promoters in response to cell stress is well established, how Hsf2 enhances stress-induced hsp expression is not understood. To gain an insight into the critical conserved features of the regulation and function of Hsf2, we have identified and characterized the Hsf2 protein from Xenopus laevis. We found that, similar to its human counterpart, Xenopus Hsf2 is sumoylated at lysine 82 and that, as it does in human Hsf2, the modification event of the small ubiquitin-related modifier 1 functions to increase the deoxyribonucleic acid-binding activity of this transcription factor in Xenopus. These results indicate that sumoylation is an evolutionarily conserved modification of Hsf2 proteins, supporting the position of this modification as a critical regulator of Hsf2 function.

Amino Acid Sequence↗
PubMed2005

Increase in phagocytosis after geldanamycin treatment or heat shock: role of heat shock proteins.

The response to injury is activated at the systemic and cellular levels. At the systemic level, phagocytosis plays a key role in controlling infections and clearing necrotic and apoptotic cells. The expression of heat shock proteins (Hsp), which is a well-conserved process, is a major component of cellular response to stress. This study investigated the relationship between Hsps and phagocytosis. An increase in the phagocytosis of opsonized bacteria particles and latex beads was observed upon incubation of murine macrophages with geldanamycin (GA), a specific inhibitor of the Hsp90 family of proteins. The effect of GA on phagocytosis was blocked by coincubation with inhibitors of transcription (actinomycin D) or translation (cycloheximide), suggesting that gene expression was required. Because expression of Hsps has been observed after GA treatment, the effect of heat shock on phagocytosis was investigated. Similar to GA treatment, heat shock resulted in an actinomycin D-sensitive elevation of phagocytosis, which suggests that Hsps are involved. The increase in phagocytosis after GA treatment was not due to increased binding of opsonized particles to their respective receptors on the macrophage surface or to elevated oxidative stress. However, it was correlated with a rapid polymerization of actin in proximity to the plasma membrane. These results suggest that Hsps play a role in the modulation of the phagocytic process, which is part of the stress response.

Actins↗