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PubMed1997

Tissue-Type-Specific Heat-Shock Response and Immunolocalization of Class I Low-Molecular-Weight Heat-Shock Proteins in Soybean.

A monospecific polyclonal antibody was used to study the tissue-type specificity and intracellular localization of class I low-molecular-weight (LMW) heat-shock proteins (HSPs) in soybean (Glycine max) under different heat-shock regimes. In etiolated soybean seedlings, the root meristematic regions contained the highest levels of LMW HSP. No tissue-type-specific expression of class I LMW HSP was detected using the tissue-printing method. In immunolocalization studies of seedlings treated with HS (40[deg]C for 2 h) the class I LMW HSPs were found in the aggregated granular structures, which were distributed randomly in the cytoplasm and in the nucleus. When the heat shock was released, the granular structures disappeared and the class I LMW HSPs became distributed homogeneously in the cytoplasm. When the seedlings were then given a more severe heat shock following the initial 40[deg]C -> 28[deg]C treatment, a large proportion of the class I LMW HSPs that originally localized in the cytoplasm were translocated into the nucleus and nucleolus. Class I LMW HSPs may assist in the resolubilization of proteins denatured or aggregated by heat and may also participate in the restoration of organellar function after heat shock.

Journal Article↗
PubMed1987

Establishment of thermotolerance in maize by exposure to stresses other than a heat shock does not require heat shock protein synthesis.

Maize (Zea mays) seedlings were pretreated prior to heat shock with either a progressive water stress of -0.25 megapascal PEG/hour from 0 to -1.25 megapascal over a 6-hour time period, or various concentrations of copper, cadmium, or zinc for 4 days. When the subsequent heat shock of 40 or 45 degrees C was administered for 3 hours, the seedlings showed an induced thermotolerance to these temperatures, which were otherwise lethal to control (water grown) seedlings. Thermotolerance was exhibited by both the root and the shoot of pretreated seedlings, even though the water and heavy metal stresses were applied only to the roots. Neither of these pretreatments had induced the synthesis of detectable levels of heat shock proteins (Hsps) at the time of heat shock. Pretreatment of seedlings with a progressive heat shock of 2 degrees C/hour from 26 to 36 degrees C, which did induce Hsps 18, 70, and 84, resulted in tolerance of a severe water stress of -1.5, -1.75, or -2.0 megapascal for 24 hours. But these seedlings producing Hsps were no better protected against water stress than those pretreated with a progressive water stress which did not produce Hsps. Hsps appear not to act as general stress proteins and their presence is not always required for the establishment of thermotolerance.

Journal Article↗
PubMed1992

Effect of heat shock on expression of proteins not involved in the heat-shock regulon.

The effect of heat shock on the expression of some genes of Escherichia coli was tested. To avoid side effects, promoters of the genes were fused to lacZ and their expression measured by the level of beta-galactosidase. The results show that expression of umuC, recA and polB, after induction of the SOS response, was somewhat higher in the heat-shocked than in the non-shocked cells, whereas expression of ada, alkB and alkA genes, after induction of the adaptive response, was about the same. Unexpectedly, it was found that expression of lacZ from its own promoter was drastically lowered in the heat-shocked cells. This effect, however, seems not to be dependent on the induction of heat-shock proteins.

Enzyme Induction↗
PubMed1998

Relationship between efficacy of defibrillation shocks and frequency characteristics of shock waveforms.

INTRODUCTION: Using the Fourier transform, it is possible to replace each time domain representation of a defibrillatory shock by a unique frequency domain representation in which the shock waveform is defined in terms of a complex number function of frequency and typically described as an amplitude in amperes per hertz (or, closely related, joules per hertz) and an associated frequency-dependent phase angle. METHODS AND RESULTS: The present article describes the conceptual basis of the Fourier transform, sketches a simplified mathematical framework for deriving frequency domain parameters, considers properties crucial to interpreting defibrillatory-type shocks when expressed in the frequency domain, and then presents a series of shock waveforms in the frequency domain. Although not definitive, knowledge of the energy distribution with frequency alone, usually presented in joules per hertz, is shown to yield considerable insight into the probable comparable efficacy of uniphasic/biphasic rectangular, untruncated/truncated uniphasic exponential, and various biphasic "single capacitor" waveforms. CONCLUSION: In general, efficacy in achieving ventricular defibrillation is improved by parameter changes that shift a larger percentage of the delivered energy into a mid-frequency range (very roughly, 40 to 160 Hz). With further study, the frequency domain approach may prove to be a useful tool in the a priori selection of optimal defibrillatory shock waveforms.

Animals↗
PubMed1969

Responding in the cat maintained under response-independent electric shock and response-produced electric shock.

Key-pressing responses in the cat were maintained under conditions in which brief electric shock was first postponed by responses (avoidance), then periodically presented independently of responses, and finally produced by responses on a fixed-interval schedule of 15 min (FI 15-min). A steady rate of responding occurred under shock avoidance and under response-independent shock; positively accelerated responding was engendered by the FI 15-min schedule. A second experiment studied responding under second-order schedules composed of three FI 5-min components. Responding was suppressed when a stimulus was presented briefly at completion of each FI 5-min component and a shock followed the brief stimulus at completion of the third component. Responding was maintained when each of the first two components was completed either with or without presentation of a brief stimulus and a shock alone was presented at completion of the third FI 5-min component.

Journal Article↗
PubMed1972

Shock-induced aggression as a function of prior experience with avoidance, fighting, or unavoidable shock.

Rats were trained in shock-induced aggression, free operant avoidance, or were presented with unavoidable shocks. Fighting in response to shock was subsequently measured by intermatching individual animals that had received the three training procedures. The fighting probabilities of animals with histories of avoidance and dominant animals with histories of fighting were higher than the fighting probabilities of non-dominant fighting rats or rats with a history of unavoidable shocks. Animals with higher fighting probabilities disrupted avoidance baselines more than animals with lower fighting probabilities. Control experiments suggested that fighting decrements produced by administration of prior grid-shock were due to the acquisition of behaviors incompatible with aggression.

Aggression↗
PubMed1996

Effect of caloric restriction on the expression of heat shock protein 70 and the activation of heat shock transcription factor 1.

The regulation of heat shock protein 70 (hsp70) expression is an excellent example of a cellular mechanism that has evolved to protect all living organisms from various types of physiological stresses; therefore, the reported age-related alterations in the ability of cells to express hsp70 in response to stress could seriously compromise the ability of a senescent organism in respond to changes in its environment. Because caloric restriction (CR) is the only experimental manipulation known to retard aging and increase the survival of rodents, it was of interest to analyze the effect of CR on the age-related alteration in the induction of hsp70 expression in rat hepatocytes. The effect of CR on the nuclear transcription of hsp70 gene in rat hepatocytes in response to various levels of heat shock was determined, and it was found that the age-related decline in the transcription of hsp70 at all temperatures studied was reversed by CR. Because the heat shock transcription factor (HSF) mediates the heat-induced transcription of hsp70, the effect of CR on the induction of HSF binding activity by heat shock was studied and found to arise from HSF1, which has been shown to be involved in the induction of HSF binding activity in other cell types. The age-related decrease in the induction of HSF1 binding activity in rat hepatocytes was reversed by CR, and did not appear to be due to an accumulation of inhibitory molecules with age. Interestingly, the level of HSF1 protein was significantly higher in hepatocytes isolated from old rats fed ad libitum compared to hepatocytes obtained from rats fed the CR diet even though the levels of HSF1 binding activity were lower for hepatocytes isolated from the old rats fed ad libitum. The levels of the mRNA transcript for HSF1 was not significantly altered by age or CR. Thus, the changes in HSF1 binding activity with age and CR do not arise from changes in the level of HSF1 protein available for activation.

Age Factors↗
PubMed1993

A critical role for heat shock transcription factor in establishing a nucleosome-free region over the TATA-initiation site of the yeast HSP82 heat shock gene.

Heat shock genes are poised for rapid transcriptional activation in response to environmental stress. A universal structural characteristic of such genes is the presence of a nucleosome-free, DNase I hypersensitive promoter region. Here we investigate the structural and functional effects of mutating HSE1, the preferred heat shock factor (HSF) binding site upstream of the yeast HSP82 gene. In situ deletion or substitution of this sequence reduces both basal and induced transcription by at least two orders of magnitude. Moreover, such mutations lead to a dramatic transition in chromatin structure: the DNase I hypersensitive region is replaced by two stable, sequence-positioned nucleosomes. One of these is centered over the mutated heat shock element, while the other--as revealed by DNase I genomic footprinting--is precisely positioned in a rotational sense over the TATA-initiation site. Overexpression of yeast HSF strongly suppresses the null phenotype of the induced hsp82-delta HSE1 gene and re-establishes DNase I hypersensitivity over its promoter. Such suppression is mediated through sequence disposed immediately upstream of HSE1 and containing two low affinity heat shock elements. These data imply a critical role for HSF in displacing stably positioned nucleosomes in Saccharomyces cerevisiae and suggest that HSF transcriptionally activates HSP82 at least partly through its ability to alleviate nucleosome repression of the core promoter.

Base Sequence↗
PubMed1995

Heat shock factor-1 and the heat shock cognate 70 protein associate in high molecular weight complexes in the cytoplasm of NIH-3T3 cells.

Interaction of heat shock transcription factor-1 (HSF-1) with the seventy kilodalton heat shock cognate protein (HSC70) was examined in NIH 3T3 cells. HSF-1 was found in the cytoplasm of non-stressed cells associated with HSC70 in large (Mr 400-500,000) complexes. After heat shock, HSF-1 became concentrated in the nucleus in smaller, more stable complexes that did not contain HSC70, an indication of significant rearrangement within the complexes. These experiments show a profound effect of heat shock on the structure and stability of HSF-1 complexes during nuclear localization and support the hypothesis that HSC70 binding may control HSF-1 function.

3T3 Cells↗
PubMed2001

Transcription of the ibpB heat-shock gene is under control of sigma(32)- and sigma(54)-promoters, a third regulon of heat-shock response.

The expression of the ibpAibpB heat-shock operon of Escherichia coli was found previously not to conform to the known pattern of expression of the sigma(32)-regulated operons because the rpoH gene mutation inactivating the sigma(32) protein did not abolish the ibp induction. We show here that this effect can depend partly on the sigma(54)-promoter that is inducible by heat shock, located upstream of the ibpB, the distal gene of the operon. It may also depend on a metabolic signal, postulated by others, and possibly required for the expression of the ibpAB genes. Thus, the ibpB gene can be translated from the transcript covering the whole operon starting from the sigma(32)-promoter and from the ibpB gene transcript starting from the sigma(54)-promoter. These results indicate that the ibpB gene is a second member of the sigma(54)-heat-shock regulon in E. coli besides pspA-E operon. Thus, heat-shock response involves three regulons controlled by sigma(32), sigma(24), and sigma(54) RNA polymerase subunits.

Bacterial Proteins↗
PubMed1995

Analysis by confocal microscopy of the behavior of heat shock protein 70 within the nucleus and of a nuclear matrix polypeptide during prolonged heat shock response in HeLa cells.

By means of confocal laser scanning microscopy and indirect fluorescence experiments we have examined the behavior of heat-shock protein 70 (HSP70) within the nucleus as well as of a nuclear matrix protein (M(r) = 125 kDa) during a prolonged heat-shock response (up to 24 h at 42 degrees C) in HeLa cells. In control cells HSP70 was mainly located in the cytoplasm. The protein translocated within the nucleus upon cell exposure to hyperthermia. The fluorescent pattern revealed by monoclonal antibody to HSP70 exhibited several changes during the 24-h-long incubation. The nuclear matrix protein showed changes in its location that were evident as early as 1 h after initiation of heat shock. After 7 h of treatment, the protein regained its original distribution. However, in the late stages of the hyperthermic treatment (17-24 h) the fluorescent pattern due to 125-kDa protein changed again and its original distribution was never observed again. These results show that HSP70 changes its localization within the nucleus conceivably because it is involved in solubilizing aggregated polypeptides present in different nuclear regions. Our data also strengthen the contention that proteins of the insoluble nucleoskeleton are involved in nuclear structure changes that occur during heat-shock response.

Antibodies, Monoclonal↗
PubMed1992

Effects of thermal shocks on interleukin-1 levels and heat shock protein 72 (HSP72) expression in normal human keratinocytes.

Interleukin-1 expression is reported to be modified under a number of cell conditions including physiological stress, injury and activation. We report the effects of the physiological stresses cold and heat shock on IL-1 levels in keratinocytes. Having observed that normal human skin obtained from plastic surgery, usually stored at 4 degrees C for a few hours, highly expressed HSP72, a constant feature of stressed human keratinocytes, we wondered whether this induction could be linked to a cold shock and to modification of IL-1 levels in keratinocytes. Cultured keratinocytes were incubated at 4, 37, 40 and 43 degrees C for 1.5, 4, 8 and 16 h in a defined medium. HSP72 expression was studied by immunohistochemistry and immunoblot and IL-1 was quantified using specific and sensitive radioimmunoassay. Our findings showed that intracellular IL-1 alpha and IL-1 beta levels are not significantly modified by thermal shock. HSP72 is only induced after cell exposure to 43 degrees C and is not a cold-shock protein. These results demonstrate that thermal stress is not an inductive signal for IL-1 modification in keratinocytes.

Cell Extracts↗
PubMed1983

Advantages of dextran 70 over Ringer acetate solution in shock treatment and in prevention of adult respiratory distress syndrome. A randomized study in man after traumatic-haemorrhagic shock.

Twenty-three patients aged 20-58 years in a serious state of shock and suffering from major pelvic and femoral fractures sustained in traffic accidents were studied. As initial fluid management, either dextran 70 (1000-1500 ml) together with Ringer's acetate solution (2000-3000 ml), or Ringer's acetate alone (5000-8000 ml), was administered on a random basis. Thus, 12 patients received dextran and 11 patients crystalloid treatment to counteract shock. Both groups were given whole blood. The resuscitation time--i.e. the interval from the start of fluid therapy until a stable circulatory condition was achieved--was significantly shorter (P less than 0.001) in the dextran group (108 +/- 18 min; mean +/- S.D.) than in the Ringer group (170 +/- 43 min). During the post-resuscitative observation period of 6 days the dextran patients were given 500 ml of dextran daily, while the Ringer group did not receive any colloidal solution. To maintain a stable circulation and a urinary output above 50 ml/h the Ringer patients required significantly more (P less than 0.001) crystalloid solution (910 +/- 300 ml) daily than the dextran patients (460 +/- 400 ml). The frequency of adult respiratory distress syndrome (ARDS) was significantly lower (P less than 0.05) in the dextran group (0 of 12) than in the Ringer group (4 of 11). Thus, in the initial treatment of traumatic-haemorrhagic shock and in the post-resuscitative period dextran 70 would seem of advantage over Ringer's acetate both in shortening the shock period and in reducing the frequency of adult respiratory distress syndrome.

Adult↗
PubMed2006

Protective role of heat shock and heat shock protein 70 in lactacystin-induced cell death both in the rat substantia nigra and PC12 cells.

Proteasomal dysfunction plays an important role in the pathogenesis of Parkinson disease (PD). Although clinical and experimental evidence continues to accumulate indicating heat shock protein 70 (HSP70) is significant in the pathogenesis of PD, few studies have been made to investigate the role of HSP70 under the condition of proteasome dysfunction. In in vivo study, we infused lactacystin into the unilateral substantia nigra (SN) of Sprague-Dawley rats with or without preceding whole body hyperthermia (WBH). Immunohistochemical studies showed the death of dopaminergic neurons and activated microglia in the SN. Lactacystin with prior WBH increased the expression of HSP70 more than did lactacystin alone and decreased lactacystin-induced dopaminergic neuronal death in the SN. In PC12 cells, heat shock pretreatment decreased lactacystin-induced cell death. Although additional treatment of nocodazole, ammonium chloride, and 3-methyladenine augmented cell death by lactacystin, heat shock pretreated to these drugs offsets their additional toxicity. These results indicate that heat shock proteins, especially HSP70, could play an important role under the condition of proteasome dysfunction in part by fostering aggresome formation and lysosome-mediated autophagy.

Acetylcysteine↗
PubMed2000

Heat shock-induced arrests in different cell cycle phases of rat C6-glioma cells are attenuated in heat shock-primed thermotolerant cells.

The response kinetics of rat C6 glioma cells to heat shock was investigated by means of flow cytometric DNA measurements and western blot analysis of HSP levels. The results showed that the effects on cell cycle progression are dependent on the cell cycle phase at which heat shock is applied, leading to either G1 or G2/M arrest in randomly proliferating cells. When synchronous cultures were stressed during G0 they were arrested with G1 DNA content and showed prolongation of S and G2 phases after release from the block. In proliferating cells, HSC70 and HSP68 were induced during the recovery and reached maximum levels just before cells were released from the cell cycle blocks. Hyperthermic pretreatment induced thermotolerance both in asynchronous and synchronous cultures as evidenced by the reduced arrest of cell cycle progression after the second heat shock. Thermotolerance development was independent of the cell cycle phase. Pre-treated cells already had high HSP levels and did not further increase the amount of HSP after the second treatment. However, as in unprimed cells, HSP reduction coincided with the release from the cell cycle blocks. These results imply that the cell cycle machinery can be rendered thermotolerant by heat shock pretreatment and supports the assumption that HSP70 family members might be involved in thermotolerance development.

Adaptation, Physiological↗
PubMed1999

Purification and characterization of the 16-kDa heat-shock-responsive protein from the thermophilic cyanobacterium Synechococcus vulcanus, which is an alpha-crystallin-related, small heat shock protein.

A 16-kDa protein, one of the major proteins that accumulates upon heat-shock treatment in the thermophilic cyanobacterium Synechococcus vulcanus, was purified to apparent homogeneity. The N-terminal and internal amino acid sequences of the protein exhibited a homology to the alpha-crystallin-related, small heat shock proteins from other organisms. The protein was designated HspA. Size-exclusion chromatography and nondenaturing gel electrophoresis demonstrated that HspA formed a large homo-oligomer consisting of 24 subunits. It prevented the aggregation of porcine malic dehydrogenase at 45 degrees C and 50 degrees C and citrate synthase at 50 degrees C. The activity of the malic dehydrogenase, however, was not protected under these heat-shock conditions or reactivated after a shift in temperature from 45 or 50 degrees C to 21 degrees C. HspA was able to enhance the refolding of chemically denatured rabbit muscle lactate dehydrogenase in an ATP-independent manner. A homologue to the 16-kDa protein was also found to be induced upon heat-shock treatment in the mesophilic cyanobacterium Synechocystis sp. PCC 6803.

Amino Acid Sequence↗
PubMed2005

Saccharomyces cerevisiae heat shock transcription factor regulates cell wall remodeling in response to heat shock.

The heat shock transcription factor Hsf1 of the yeast Saccharomyces cerevisiae regulates expression of genes encoding heat shock proteins and a variety of other proteins as well. To better understand the cellular roles of Hsf1, we screened multicopy suppressor genes of a temperature-sensitive hsf1 mutation. The RIM15 gene, encoding a protein kinase that is negatively regulated by the cyclic AMP-dependent protein kinase, was identified as a suppressor, but Rim15-regulated stress-responsive transcription factors, such as Msn2, Msn4, and Gis1, were unable to rescue the temperature-sensitive growth phenotype of the hsf1 mutant. Another class of suppressors encoded cell wall stress sensors, Wsc1, Wsc2, and Mid2, and the GDP/GTP exchange factor Rom2 that interacts with these cell wall sensors. Activation of a protein kinase, Pkc1, which is induced by these cell wall sensor proteins upon heat shock, but not activation of the Pkc1-regulated mitogen-activated protein kinase cascade, was necessary for the hsf1 suppression. Like Wsc-Pkc1 pathway mutants, hsf1 cells exhibited an osmotic remedial cell lysis phenotype at elevated temperatures. Several of the other suppressors were found to encode proteins functioning in cell wall organization. These results suggest that Hsf1 in concert with Pkc1 regulates cell wall remodeling in response to heat shock.

Calcium-Binding Proteins↗
PubMed1993

Characterization of a novel chicken heat shock transcription factor, heat shock factor 3, suggests a new regulatory pathway.

We have cloned three avian heat shock transcription factor (HSF) genes corresponding to a novel factor, HSF3, and the avian homologs of mammalian HSF1 and HSF2. The predicted amino acid sequence of HSF3 is approximately 40% related to the sequence of HSF1 and HSF2. The sequences for all three factors exhibit extensive identify in the DNA binding motifs and the heptad repeats of hydrophobic amino acids which are common to all eukaryotic HSFs. Despite these overall similarities, each avian HSF exhibits distinct DNA binding properties. HSF2 when expressed in vitro binds constitutively to the heat shock element promoter sequence, whereas neither HSF1 nor HSF3 expressed in vitro binds to DNA. HSF1 DNA binding is induced upon heat shock or treatment with nonionic detergents, whereas the DNA binding properties of HSF3 are not induced by these conditions in vitro. These results suggest that HSF3 activation may involve an induction pathway distinct from the traditional forms of heat shock gene induction. HSF3 DNA binding activity, however, is obtained when the carboxyl-terminal region including the distal heptad repeat is deleted, indicating the presence of negative cis-regulatory sequences. The HSF3 message, like HSF1 and HSF2 messages, is coexpressed during development and in most tissues, which suggests a general role for the regulatory pathway involving HSF3.

Age Factors↗