Redox signaling of cardiac HSF1 DNA binding

Zain Paroo1, Michael J. Meredith5, Marius Locke4, James V. Haist3, Morris Karmazyn3, and Earl G. Noble1,2

1 School of Kinesiology, Faculty of Health Sciences, 2 Lawson Health Research Institute, and 3 Department of Pharmacology and Toxicology, Faculty of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada N6A 3K7; 4 Faculty of Physical Education and Health, University of Toronto, Toronto, Ontario, Canada M5S 2W6; and 5 School of Dentistry, Oregon Health and Science University, Portland, Oregon 97201-3098


    ABSTRACT
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ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

Experiments involving chemical induction of the heat shock response in simple biological systems have generated the hypothesis that protein denaturation and consequential binding of heat shock transcription factor 1 (HSF1) to proximal heat shock elements (HSEs) on heat shock protein (hsp) genes are the result of oxidation and/or depletion of intracellular thiols. The purpose of the present investigation was to determine the role of redox signaling of HSF1 in the intact animal in response to physiological and pharmacological perturbations. Heat shock and exercise induced HSF1-HSE DNA binding in the rat myocardium (P < 0.001) in the absence of changes in reduced glutathione (GSH), the major nonprotein thiol in the cell. Ischemia-reperfusion, which decreased GSH content (P < 0.05), resulted in nonsignificant HSF1-HSE formation. This dissociation between physiological induction of HSF1 and changes in GSH was not gender dependent. Pharmacological ablation of GSH with L-buthionine-[S,R]-sulfoximine (BSO) treatment increased myocardial HSF1-HSE DNA binding in estrogen-naive animals (P = 0.007). Thus, although physiological induction of HSF1-HSE DNA binding is likely regulated by mediators of protein denaturation other than cellular redox status, the proposed signaling pathway may predominate with pharmacological oxidation and may represent a plausible and accessible strategy in the development of HSP-based therapies.

protein denaturation; exercise; glutathione; heat shock protein; ischemia-reperfusion


    INTRODUCTION
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ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

A HIGHLY CONSERVED, ubiquitous endogenous defense mechanism is the induction of heat shock proteins (HSPs) in response to proteotoxic stress. Aside from this protective feature, of particular interest in cardiovascular research, biologists have used the heat shock response as a model by which to study cellular sensing mechanisms.

In the unstressed cell, the products of the heat shock response, the HSPs themselves, are bound to inactive, monomeric heat shock transcription factors (HSF1; Refs. 1, 35, 44). Initiation of the response requires HSF1 trimerization for high-affinity binding with proximal promoter heat shock elements (HSEs) on hsp transcriptional units (28, 47, 52). HSPs serve to maintain intracellular components by assisting in the proper folding of nascent polypeptides and in the refolding of anative proteins, preventing aggregation and aiding in translocation and degradation of peptides (4, 8, 9, 12, 25). Stress-induced increases in intracellular levels of anative proteins require increased chaperoning activity for the maintenance of cellular homeostasis. Such demand for HSPs permits HSF1 trimerization and the acquisition of DNA binding competency and consequential upregulation of hsp gene expression. Indeed, heat shock and various other inducers of the response have been shown to increase cellular proteotoxicity (27, 36). Moreover, introduction of anative proteins into otherwise quiescent biological systems results in HSP induction (2, 20, 34). Thus protein denaturation is a key cellular signal by which the HSP response is regulated.

Observations of a wide variety of inducers of the heat shock response converging to a single cellular event have led to the question of whether this convergence occurs at the level of protein denaturation or whether there is a more proximal merger. Russo et al. (42) first observed that depletion of cellular reduced glutathione (GSH) resulted in thermotolerance and concomitant synthesis of HSPs. Further work continued this characterization using a variety of experimental models and perturbations to manipulate intracellular redox status, demonstrating that oxidation and depletion of nonprotein thiols results in HSF1 activation, hsp gene transcription, and HSP synthesis and, moreover, that maintaining a reducing cellular environment inhibits this response (14, 15, 17-19, 21, 22, 24, 29, 32, 43, 45, 51). This led to the hypothesis that protein denaturation and consequential activation of HSF1 are the result of anative protein modifications caused by oxidation and/or depletion of intracellular nonprotein thiols (Fig. 1; Ref. 51).


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Fig. 1.   Schematic outlining the hypothesized oxidation and/or depletion of nonprotein sulfhydryls (NPSH) as a proximal signal in activation of the heat shock response. HSF, heat shock transcription factor; HSP, heat shock protein.

Although well supported in simple biological systems using chemical inducers of HSF1, this hypothesis has not been addressed in higher-order experimental systems, which limits its physiological relevance and potential applicability to HSP-based therapeutic research. Thus the purpose of the present investigation was to determine the role of redox signaling of HSF1 in the intact animal in response to physiological and pharmacological perturbations. Because GSH is the most prominent intracellular nonprotein thiol (46), changes in GSH levels should accurately reflect cellular thiol oxidation (21, 33, 46, 51). Because of the established cardioprotective potential of HSPs, the relevance of the current hypothesis to the regulation of the heat shock response in the heart was of particular interest.

Furthermore, we previously demonstrated (37, 38, 40) a gender-specific HSP response, with males demonstrating twofold greater levels of HSP70 than females after exercise. Removal of the ovaries, the major endogenous source of estrogen in females, resulted in increased induction of HSP70, similar to that observed for males. Exogenous replacement of estrogen in these animals reversed this effect. Because estrogen is an antioxidant compound (50), it was of interest to us to determine whether the ovarian hormone was mitigating HSP induction through this proposed redox signaling system. Thus the present experiments were conducted in estrogen-positive and estrogen-naive animal models.


    METHODS
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INTRODUCTION
METHODS
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REFERENCES

The study was approved by the University of Western Ontario Council on Animal Care and was performed in accordance with the guiding principles of the Canadian Council on Animal Care. Eleven-week-old male, gonadally intact female, and ovariectomized female (major source of estrogen removed; ovariectomy performed at 8 wk) rats, purchased from Charles River, were housed two per cage in an environmentally controlled room with a 12:12 h dark-light cycle with food and water ad libitum.

Experimental procedures. Animals were chosen at random for experimental treatment. Nonexertional hyperthermia was induced as previously described (n = 4 males, 4 females; Ref. 48). Animals were lightly anesthetized with Somnitol (30 mg/kg ip) and placed on heating pads. Colonic temperatures were maintained between 41.5 and 42.0°C for 20 min, after which hearts were immediately extirpated. Exercise consisted of treadmill running at 30 m/min for 60 min. In the experiments reported in Fig. 3, animals were anesthetized immediately after exercise with Somnitol (60 mg/kg ip) and hearts were extirpated (n = 4 males, 4 females). Exercise experiments outlined in Fig. 4 are those in which animals were decapitated to minimize the time between the end of the exercise bout and harvesting of tissues (n = 6 ovariectomized, 6 intact per treatment group). Myocardial ischemia-reperfusion was performed with a modified Langendorff procedure (31), with a 30-min zero-flow global ischemic period followed by a 30-min period of reperfusion (n = 4 males, 4 females). Tissues were immediately frozen in liquid nitrogen and stored at -80°C for analysis.

Pharmacological manipulation of myocardial GSH. Pharmacological manipulation of cardiac GSH content was achieved by treatment with L-buthionine-[S,R]-sulfoximine (BSO), a specific inhibitor of gamma -glutamylcysteine synthetase, the rate-limiting enzyme in the synthesis of glutathione (33). Rats were either treated with BSO (1 g/kg ip, dissolved in physiological saline) or sham injected 24 and 3 h before experimental treatment (n = 6 ovariectomized, 6 intact per treatment group).

HSF1-HSE DNA binding. Gel mobility shift assays were performed with tissue samples homogenized in 15 vols of extraction buffer as per Locke et al. (30). Protein concentration was determined with a Bio-Rad assay modified for microplate analysis. One hundred micrograms of myocardial extracts were incubated with 1 ng of 32P-labeled self-complementary ideal HSE oligonucleotide (5'-CTAGAAGCTTCTAGAAGCTTCTAG-3') and separated on full-size nondenaturing polyacrylamide gels as previously outlined (30). Competition experiments were performed with 200-fold molar excess of cold HSE and Oct2A oligonucleotides, and supershift experiments were carried out with monoclonal anti-serum specific for HSF1 (Neomarkers).

GSH measurement. Hearts (100 mg/ml) were homogenized in 10% perchloric acid with 15 µM gamma -glutamylglutamate, which was used as HPLC standard. GSH content was assessed by HPLC as described by Farris and Reed (10) and Freeman et al. (16).

Statistical analysis. Quantitation of blots was carried out with Scion image analysis software (National Institutes of Health). HSF1-HSE oligonucleotide binding is reported as percentage of internal standard (100 µg of cardiac extract from heat-shocked male Sprague-Dawley rat; means ± SE). Group data were compared by analysis of variance among treatment groups. Pairwise comparisons were conducted with a Tukey post hoc test, where the minimum level of significance was assigned as P < 0.05.


    RESULTS
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INTRODUCTION
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DISCUSSION
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HSF1-HSE DNA binding. To establish a gel mobility shift assay specific for HSF1 and the HSE oligonucleotide, several control experiments were performed (Fig. 2). No mobility shift was observed for lanes loaded with the labeled HSE alone or for cardiac extracts from control hearts (see following sections). Heat shock and exercise treatments resulted in retarded migration of the labeled oligonucleotide, indicating the presence of a factor in the cardiac extracts with HSE binding competency. Competitive experiments with a 200-fold molar excess of unlabeled HSE resulted in a loss of the mobility shift, whereas competition with a control oligonucleotide, Oct2A, did not, indicating specificity of the cellular binding factor for the HSE oligonucleotide. Addition of antibodies specific for HSF1 resulted in a supershift, indicating that the factor in extracts from heat-shocked and exercised animals responsible for retarding migration of the labeled HSE was HSF1. Thus the present gel mobility shift assay is specific for HSF1-HSE DNA binding.


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Fig. 2.   Gel mobility shift control experiments illustrating specificity of the assay for HSF1 and the heat shock element (HSE) for heat shock and exercise conditions. Cardiac extracts (100 µg) were incubated with a 32P-labeled oligonucleotide containing the HSE sequence and separated by nondenaturing polyacrylamide gel electrophoresis. Lanes from left to right show free probe, control (Cont), heat shock (HS); heat shock + 200-fold molar excess cold HSE, heat shock + 200-fold molar excess cold Oct2A, supershift of heat shock with 0.5 µg of anti-HSF1, exercise (Ex), exercise + 200-fold molar excess cold HSE, exercise + 200-fold molar excess cold Oct2A, and supershift of exercise with 0.5 µg anti-HSF1.

Dissociation of HSF1 activation and changes in GSH with physiological stimuli. Heat shock and exercise markedly induced cardiac HSF1-HSE oligonucleotide binding in males and females (P < 0.001; Fig. 3). However, neither heat shock nor exercise was accompanied by alterations in cardiac GSH levels in either males or females. Analysis of mixed cysteinyl glutathione, the mixed disulfide between glutathione and cysteine, also indicated low levels of oxidation with these perturbations (data not shown). Ischemia-reperfusion, a well-established model of oxidative stress, diminished myocardial GSH content (and increased cysteinyl glutathione; P < 0.05). However, only minimal, statistically nonsignificant HSF1-HSE binding was observed in these experiments. Thus, in intact animal models of both genders, heat shock and exercise, physiological inducers of HSF1 DNA binding, were not associated with alterations in cardiac GSH and physiological depletion of GSH was not accompanied by induction of HSF1.


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Fig. 3.   Heat shock and exercise result in HSF1-HSE DNA binding without any changes in myocardial reduced glutathione (GSH). Top: representative gel mobility shift autoradiogram illustrating HSF1-HSE binding for control (C), heat shock (HS), exercise (Ex), and ischemia-reperfusion (I/R) for males and females as indicated. Bottom: graphic representation of HSF1-HSE binding (expressed as % of a male heat shock heart standard) and myocardial GSH content. Gel mobility shift assays were performed with 100 µg of cardiac extract. Animals in these experiments were killed by cardiac extirpation. * Significantly different from all other groups, psi  less than heat shock (P < 0.05; n = 4 per group).

Pharmacological depletion of GSH induces cardiac HSF1-HSE DNA binding. Decreasing myocardial GSH levels via BSO treatment resulted in significantly greater levels of HSF1-HSE binding relative to sham treatment in ovariectomized animals (P = 0.007; Fig. 4). In line with previous work with simple biological systems, these findings represent an important positive control for the present work and indicate the potential for redox-mediated induction of cardiac HSF1. To investigate a possible additive effect of chemical and physiological stimuli on induction of HSF1, animals were administered BSO before exercise. However, such treatment did not potentiate the response. BSO treatment in intact females, which also resulted in decreased GSH content (P = 0.008), had no effect on HSF1-HSE binding. Thus pharmacological depletion of GSH activated myocardial HSF1-HSE oligonucleotide binding in estrogen-naive but not estrogen-positive animals.


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Fig. 4.   Pharmacological depletion of GSH results in greater HSF1-HSE DNA binding in ovariectomized (OVX) but not intact females. Top: representative gel mobility shift autoradiogram illustrating HSF1-HSE binding for sham- or L-buthionine-[S,R]-sulfoximine (BSO)-treated, control or exercised OVX and intact females. Arrowhead indicates HSF1-HSE DNA binding. NS denotes nonspecific binding. Bottom: graphic representation of HSF1-HSE binding (expressed as % of male heat shock heart standard) and myocardial GSH content. Gel mobility shift assays were performed with 100 µg of cardiac extract. Animals in these experiments were killed by decapitation, and the observed HSF1-HSE binding for control animals may be the result of such treatment. * Significant difference between sham and BSO treatment (P < 0.05; n = 4-6 per group).

Constitutive HSF1-HSE DNA binding is dependent on method of euthanasia. The first series of experiments, those illustrated in Fig. 3, were performed with animals killed by cardiac extirpation after anesthetization. Extracts from control animals subjected to such treatment demonstrated no HSF1-HSE binding. Because GSH levels are transient, to ensure that GSH measurement was not hindered by the time required for this process, subsequent experiments employed decapitation as the method of euthanasia (Fig. 4). Myocardial extracts from these control animals demonstrated constitutive HSF1-HSE oligonucleotide binding. To more discriminately determine the effect of different euthanizing techniques on the activation state of HSF1, animals were killed by one of three methods commonly employed by animal researchers: 1) cardiac extirpation after anesthetization (extirpation); 2) exsanguination before extirpation (exsanguination); and 3) decapitation. Extirpation of the heart after pentobarbital treatment produced no DNA binding (Fig. 5, lane 1). Exsanguination before extirpation resulted in a low level of extract-oligonucleotide interaction (Fig. 5, lane 2). Cardiac extracts from decapitated animals demonstrated a consistent and high degree of HSE oligonucleotide binding (Fig. 5, lane 3) comparable to that observed after heat shock (Fig. 5, lane 4; Table 1). Moreover, extract-oligonucleotide binding affinity was similar between decapitation and heat shock conditions as extract-oligonucleotide binding reaction temperatures of 25, 30, and 37°C resulted in a proportionate decrease in signal (data not shown). Because we previously documented (37, 38, 40) gender-specific, hormone-mediated HSP induction, these experiments were performed on male, intact female, and ovariectomized female rats. However, neither gender nor hormonal status appeared to influence this pattern of response.


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Fig. 5.   Decapitation induces cardiac HSF1-HSE DNA binding. Representative gel mobility shift assays for animals killed by extirpation (n = 8; lane 1), exsanguination followed by extirpation (n = 15; lane 2), decapitation (n = 16; lane 3), or extirpation after heat shock (n = 8; lane 4). Gel mobility shift assays were performed with 100 µg of cardiac extract. Arrowhead indicates HSF1-HSE oligonucleotide binding. NS denotes nonspecific binding.


                              
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Table 1.   Observed frequency and relative degree of HSF1-HSE DNA binding

These fortuitous findings provided a further model in addressing the objectives of the present study. That is, although decapitation resulted in marked HSF1-HSE binding relative to extirpation, myocardial GSH content was not different between these groups (2.54 ± 0.12 vs. 2.63 ± 0.51 mM/mg for decapitated and extirpated groups, respectively), indicating that redox signaling is not likely predominant in decapitation-induced activation of HSF1.


    DISCUSSION
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ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

A major deficiency in HSP research is a lack of understanding of the regulation of these transcriptional units in complex biological systems. Although the response is highly conserved evolutionarily, there have been reports of interorganismal and, indeed, interspecies variations (11, 47). Our understanding of the mechanisms of the HSP response is derived largely from in vitro and cell culture experiments. Validating these hypotheses in higher-order experimental models tremendously increases the physiological significance of such work and is a prerequisite to harnessing the protective potential of these critical cellular components.

The present study was undertaken to investigate a hypothesis, well developed and well supported in simple biological systems with chemical inducers of the heat shock response, in whole animal models. The possibility that this highly complex endogenous defense mechanism may be signaled by a single early cellular event, which is relatively easy to manipulate, is an attractive postulate for potential applications in cardiac pathology and preventive medicine, particularly as redox-related compounds such as BSO have been tested in clinical trials.

If the hypothesized signaling pathway is involved in HSF1 acquiring DNA binding competency in response to physiological inducers, then such perturbations should cause thiol depletion. Although heat shock and exercise resulted in marked HSF1-HSE DNA binding, neither stressor was accompanied by decreases in cardiac GSH content in either males or females. It should be noted that such treatments may have caused some transient cellular oxidation but because of the time course selected and/or the speed at which glutathione reductase catalyzes its reaction these alterations were not detected. However, analysis of cysteinyl glutathione, the mixed disulfide between cysteine and glutathione, a more stable marker of cellular oxidation, revealed a similar pattern of low-level oxidation after heat shock and exercise. Moreover, in an effort to minimize the time interval between the completion of exercise and the harvesting of hearts, GSH data from animals killed by decapitation also revealed a lack of change in GSH content. Thus exercise-induced activation of HSF1 is not likely mediated through cellular oxidation. Furthermore, ischemia-reperfusion, which was effective in decreasing GSH levels (and increasing cysteinyl glutathione levels), resulted in only faintly detectable and statistically nonsignificant HSF1-HSE DNA binding, findings inconsistent with the present hypothesis. Thus, although the data presented do not completely rule out the possibility of changes in redox status and association with activation of HSF1, in response to physiological stimuli induction of myocardial HSF1 is likely regulated predominantly by mechanisms other than redox signaling.

If thiol oxidation can signal HSF1 DNA binding in the whole animal, then pharmacological depletion of GSH should induce the response. Indeed, depletion of myocardial GSH with BSO treatment resulted in increased HSF1-HSE DNA binding in ovariectomized (estrogen naive) animals. These findings indicate that alterations in cardiac redox status can signal activation of HSF1 in response to pharmacological oxidation. Such findings, however, were not observed for intact females (estrogen positive) despite the effectiveness of BSO in depleting GSH in these animals. Such discrepancy may be due to the indirect antioxidant cell membrane stabilizing activity of estrogen (50), particularly as denaturation of membrane-bound proteins has been shown as a key regulator of HSP induction in response to nonthermal stress (13, 43). Alternatively, the effect of BSO on HSF1-HSE binding observed in ovariectomized animals may be related to effects of the compound other than those related to oxidation. Thus estrogen may attenuate BSO-induced activation of HSF1 through such nonspecific mechanisms.

The rationale for including estrogen-naive and estrogen-positive models in the present series of experiments is derived from our previous findings of gender-specific, hormone-mediated HSP regulation (37, 38, 40). Gender has been a discounted factor in biomedical research, and it is only beginning to become apparent how great an impact sex and hormonal status have on biological function. The disparate effects of pharmacological induction of HSF1 between estrogen-naive and estrogen-positive animals serves as yet another example of this and may indicate that exploitation of this signaling system in cardiac therapeutics may also be dependent on these factors.

In the above series of experiments, an unexpected observation was made. To minimize the time required for harvesting of tissues, animals were euthanized by decapitation. Cardiac extracts from control animals subjected to this treatment demonstrated significant HSF1-HSE oligonucleotide binding. Control animals killed by extirpation demonstrated no such response. To more discriminately investigate the influence of method of euthanasia on induction of HSF1 DNA binding, animals were euthanized by three techniques commonly employed by animal researchers. Decapitation consistently resulted in dramatic HSF1-HSE DNA binding relative to exsanguination and extirpation. This phenomenon, although beyond the scope of the present work, may be the result of hormonal signaling of the stress response (3, 11, 39, 49), because decapitation results in dramatic increases in plasma catecholamines (41) and tissue levels of second messenger activity (26). Relevant to the present question, there were no differences in myocardial GSH levels between decapitated animals and those killed by extirpation, despite the marked HSF1-HSE binding observed with the former treatment. Such observations provide an additional nonpharmacological model of HSF1 induction that is likely regulated by mechanisms other than those mediated by cellular redox state.

This proposed relationship between redox state and induction of HSF1 was of particular interest to us because we previously reported (37, 38, 40) a gender-specific, hormone-mediated HSP response. After exercise, male rodents demonstrated higher HSP70 levels than females and estrogen administration to estrogen-naive animals resulted in an attenuated, femalelike response. Estrogen has been characterized as an antioxidant (50). Thus, if cellular oxidation was involved in signaling the HSP response, then estrogen may mitigate HSP signaling through this cascade. However, exercise-induced activation of HSF1 was not associated with changes in GSH levels, and moreover, there were no differences in cardiac GSH levels among male, intact female, and ovariectomized animals with exercise. These observations are consistent with our previous reports (37, 38) indicating that estrogen-mediated attenuation of HSP induction is likely conferred through physicochemical membrane stabilization. Antioxidant compounds with structural and membrane-stabilizing properties similar to those of 17beta -estradiol, the major endogenous estrogen in mammalian systems, mitigated HSP induction in a fashion similar to that of the hormone. Therefore, the mechanism by which estrogen attenuates HSP induction is not likely related to cellular redox state but rather to indirect antioxidant stabilization of cellular membranes.

The present investigation was undertaken to test the hypothesis that intracellular thiol oxidation serves as a proximal signal for HSF1-HSE DNA binding in the whole animal. This issue was previously addressed indirectly in the intact animal. Ethanol treatment in rats resulted in cellular oxidation and increased HSP70 content in the central nervous system (5, 6). Ito et al. (23) demonstrated induction of hsp32 mRNA in rat liver and kidney after depletion of GSH with BSO. It should be noted, however, that these studies assessed distal parameters in the heat shock response. The present hypothesis specifically requires HSF1-HSE DNA binding as the critical outcome of protein denaturation. Because proximal promoter elements, other than HSEs, have been shown to mediate HSP synthesis with nondenaturing stimuli (7), the alterations in HSP and hsp mRNA levels in the above studies may not have been HSF1-HSE mediated. Thus this is the first study to directly investigate the relationship between redox state and HSF1-HSE DNA binding in the intact animal.

Clearly, activation of HSF1 is dependent on protein denaturation. The present results indicate that the proximal events in this process may be stress specific as physiological induction is not likely related to redox signaling but perhaps is a consequence of thermal unfolding, mechanical disruption, and proteolytic and/or proteasome activity. However, activation of the response with pharmacological oxidation, in both simple and complex biological systems, may be mediated through the current hypothesized signaling cascade. Transgenic and gene transfection approaches have clearly established the cardioprotective potential of the heat shock response. However, such perturbations must overcome significant obstacles before they are employed in therapeutics. Although the present study does not support the hypothesis that cellular oxidation is a proximal signal common to all inducers of HSF1, exploiting this signaling system may represent a plausible and accessible strategy in the development of HSP-based therapies.


    ACKNOWLEDGEMENTS

This research was made possible by a Natural Sciences and Engineering Research Council of Canada postgraduate scholarship to Z. Paroo, an operating grant and a Career Investigator Award from the Canadian Institutes of Health Research and the Heart and Stroke Foundation of Ontario, respectively, to M. Karmazyn, a Natural Sciences and Engineering Research Council of Canada and Heart and Stroke Foundation of Canada operating grant (NA-4445) to E. G. Noble, and the St. Joseph's Hospital Foundation Doris May Anderson Fund.


    FOOTNOTES

Address for reprint requests and other correspondence: E. Noble, Rm. 2160C Thames Hall, Faculty of Health Sciences, Univ. of Western Ontario, London, ON, Canada N6A 3K7 (E-mail: enoble{at}uwo.ca).

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

March 27, 2002;10.1152/ajpcell.00051.2002

Received 31 January 2002; accepted in final form 23 March 2002.


    REFERENCES
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

1.   Abravaya, K, Myers MP, Murphy SP, and Morimoto RI. The human heat shock protein hsp70 interacts with HSF, the transcription factor that regulates heat shock gene expression. Genes Dev 6: 1153-1164, 1992[Abstract].

2.   Ananthan, J, Goldberg AL, and Voellmy R. Abnormal proteins serve as eukaryotic stress signals and trigger the activation of heat shock genes. Science 232: 522-524, 1986[ISI][Medline].

3.   Blake, MJ, Udelsman R, Feulner GJ, Norton DD, and Holbrook NJ. Stress-induced heat shock protein 70 expression in adrenal cortex: an adrenocorticotropic hormone-sensitive, age-dependent response. Proc Natl Acad Sci USA 88: 9873-9877, 1991[Abstract].

4.   Buchner, J. Supervising the fold: functional principles of molecular chaperones. FASEB J 10: 10-19, 1996[Abstract/Free Full Text].

5.   Calabrese, V, Renis M, Calderone A, Russo A, Reale S, Barcellona ML, and Rizza V. Stress proteins and SH-groups in oxidant-induced cellular injury after chronic ethanol administration in rat. Free Radic Biol Med 24: 1159-1167, 1998[ISI][Medline].

6.   Calabrese, V, Testa G, Ravagna A, Bates TE, and Stella AM. HSP70 induction in the brain following ethanol administration in the rat: regulation by glutathione redox state. Biochem Biophys Res Commun 269: 397-400, 2000[ISI][Medline].

7.   Choi, HS, Li B, Lin Z, Huang E, and Liu AY. cAMP and cAMP-dependent protein kinase regulate the human heat shock protein 70 gene promoter activity. J Biol Chem 266: 11858-11865, 1991[Abstract/Free Full Text].

8.   Eggers, DK, Welch WJ, and Hansen WJ. Complexes between nascent polypeptides and their molecular chaperones in the cytosol of mammalian cells. Mol Biol Cell 8: 1559-1573, 1997[Abstract].

9.   Ellis, RJ, and Hartl FU. Protein folding in the cell: competing models of chaperonin function. FASEB J 10: 20-26, 1996[Abstract/Free Full Text].

10.   Farris, MC, and Reed DJ. Measurement of glutathione and glutathione disulfide efflux from isolated rat hepatocytes. In: Isolation, Characterization, and Use of Hepatocytes, , edited by Harris RA, and Cornell NW.. Amsterdam: Elsevier/North Holland Biomedical, 1983.

11.   Fawcett, TW, Sylvester SL, Sarge KD, Morimoto RI, and Holbrook NJ. Effects of neurohormonal stress and aging on the activation of mammalian heat shock factor 1. J Biol Chem 269: 32272-32278, 1994[Abstract/Free Full Text].

12.   Freeman, BC, and Morimoto RI. The human cytosolic molecular chaperones hsp90, hsp70 (hsc70) and hdj-1 have distinct roles in recognition of a non-native protein and protein refolding. EMBO J 15: 2969-2979, 1996[Abstract].

13.   Freeman, ML, Borrelli MJ, Meredith MJ, and Lepock JR. On the path to the heat shock response: destabilization and formation of partially folded protein intermediates, a consequence of protein thiol modification. Free Radic Biol Med 26: 737-745, 1999[ISI][Medline].

14.   Freeman, ML, Borrelli MJ, Syed K, Senisterra G, Stafford DM, and Lepock JR. Characterization of a signal generated by oxidation of protein thiols that activates the heat shock transcription factor. J Cell Physiol 164: 356-366, 1995[ISI][Medline].

15.   Freeman, ML, Huntley SA, Meredith MJ, Senisterra GA, and Lepock J. Destabilization and denaturation of cellular protein by glutathione depletion. Cell Stress Chaperones 2: 191-198, 1997[ISI][Medline].

16.   Freeman, ML, Malcolm AW, and Meredith MJ. Role of glutathione in cell survival after hyperthermic treatment of Chinese hamster ovary cells. Cancer Res 45: 6308-6313, 1985[Abstract].

17.   Freeman, ML, Meredith MJ, and Laszlo A. Depletion of glutathione, heat shock protein synthesis, and the development of thermotolerance in Chinese hamster ovary cells. Cancer Res 48: 7033-7037, 1988[Abstract].

18.   Freeman, ML, Scidmore NC, Malcolm AW, and Meredith MJ. Diamide exposure, thermal resistance, and synthesis of stress (heat shock) proteins. Biochem Pharmacol 36: 21-29, 1987[ISI][Medline].

19.   Freeman, ML, Sierra-Rivera E, Voorhees GJ, Eisert DR, and Meredith MJ. Synthesis of hsp-70 is enhanced in glutathione-depleted Hep G2 cells. Radiat Res 135: 387-393, 1993[ISI][Medline].

20.   Goff, SA, and Goldberg AL. Production of abnormal proteins in E. coli stimulates transcription of lon and other heat shock genes. Cell 41: 587-595, 1985[ISI][Medline].

21.   Hatayama, T, and Hayakawa M. Differential temperature dependency of chemical stressors in HSF1-mediated stress response in mammalian cells. Biochem Biophys Res Commun 265: 763-769, 1999[ISI][Medline].

22.   Huang, LE, Zhang H, Bae SW, and Liu AY. Thiol reducing reagents inhibit the heat shock response. Involvement of a redox mechanism in the heat shock signal transduction pathway. J Biol Chem 269: 30718-30725, 1994[Abstract/Free Full Text].

23.   Ito, K, Yano T, Hagiwara K, Ozasa H, and Horikawa S. Effects of vitamin E deficiency and glutathione depletion on stress protein heme oxygenase 1 mRNA expression in rat liver and kidney. Biochem Pharmacol 54: 1081-1086, 1997[ISI][Medline].

24.   Jacquier-Sarlin, MR, and Polla BS. Dual regulation of heat-shock transcription factor (HSF) activation and DNA-binding activity by H2O2: role of thioredoxin. Biochem J 318: 187-193, 1996[ISI][Medline].

25.   Kelley, WL, and Georgopoulos C. Chaperones and protein folding. Curr Opin Cell Biol 4: 984-991, 1992[Medline].

26.   Kimura, H, Thomas E, and Murad F. Effects of decapitation, ether and pentobarbital on guanosine 3',5'-phosphate and adenosine 3',5'-phosphate levels in rat tissues. Biochim Biophys Acta 343: 519-528, 1974[ISI][Medline].

27.   Lepock, JR, Frey HE, Rodahl AM, and Kruuv J. Thermal analysis of CHL V79 cells using differential scanning calorimetry: implications for hyperthermic cell killing and the heat shock response. J Cell Physiol 137: 14-24, 1988[ISI][Medline].

28.   Lis, J, and Wu C. Protein traffic on the heat shock promoter: parking, stalling, and trucking along. Cell 74: 1-4, 1993[ISI][Medline].

29.   Liu, H, Lightfoot R, and Stevens JL. Activation of heat shock factor by alkylating agents is triggered by glutathione depletion and oxidation of protein thiols. J Biol Chem 271: 4805-4812, 1996[Abstract/Free Full Text].

30.   Locke, M, Noble EG, Tanguay RM, Feild MR, Ianuzzo SE, and Ianuzzo CD. Activation of heat-shock transcription factor in rat heart after heat shock and exercise. Am J Physiol Cell Physiol 268: C1387-C1394, 1995[Abstract/Free Full Text].

31.   Mathur, S, Farhangkhgoee P, and Karmazyn M. Cardioprotective effects of propofol and sevoflurane in ischemic and reperfused rat hearts: role of K(ATP) channels and interaction with the sodium-hydrogen exchange inhibitor HOE 642 (cariporide). Anesthesiology 91: 1349-1360, 1999[ISI][Medline].

32.   McDuffee, AT, Senisterra G, Huntley S, Lepock JR, Sekhar KR, Meredith MJ, Borrelli MJ, Morrow JD, and Freeman ML. Proteins containing non-native disulfide bonds generated by oxidative stress can act as signals for the induction of the heat shock response. J Cell Physiol 171: 143-151, 1997[ISI][Medline].

33.   Meister, A. Glutathione deficiency produced by inhibition of its synthesis, and its reversal; applications in research and therapy. Pharmacol Ther 51: 155-194, 1991[ISI][Medline].

34.   Mifflin, LC, and Cohen RE. Characterization of denatured protein inducers of the heat shock (stress) response in Xenopus laevis oocytes. J Biol Chem 269: 15710-15717, 1994[Abstract/Free Full Text].

35.   Mosser, DD, Duchaine J, and Massie B. The DNA-binding activity of the human heat shock transcription factor is regulated in vivo by hsp70. Mol Cell Biol 13: 5427-5438, 1993[Abstract].

36.   Nguyen, VT, Morange M, and Bensaude O. Protein denaturation during heat shock and related stress. Escherichia coli beta-galactosidase and Photinus pyralis luciferase inactivation in mouse cells. J Biol Chem 264: 10487-10492, 1989[Abstract/Free Full Text].

37.   Paroo, Z, Dipchand ES, and Noble EG. Estrogen attenuates post-exercise Hsp70 induction in skeletal muscle. Am J Physiol Cell Physiol 282: C245-C251, 2002[Abstract/Free Full Text].

38.   Paroo, Z, Haist JV, Karmazyn M, and Noble EG. Exercise improves post-ischemic cardiac function in males but not females: consequences of a novel gender-specific Hsp70 response. Circ Res 90: 911-917, 2002[Abstract/Free Full Text].

39.   Paroo, Z, and Noble EG. Isoproterenol potentiates exercise-induction of Hsp70 in cardiac and skeletal muscle. Cell Stress Chaperones 4: 199-204, 1999[ISI][Medline].

40.   Paroo, Z, Tiidus PM, and Noble EG. Estrogen attenuates HSP 72 expression in acutely exercised male rodents. Eur J Appl Physiol 80: 180-184, 1999.

41.   Roizen, MF, Moss J, Henry DP, Weise V, and Kopin IJ. Effect of general anesthetics on hand. J Pharmacol Exp Ther 204: 11-18, 1978[Abstract].

42.   Russo, A, Mitchell JB, and McPherson S. The effects of glutathione depletion on thermotolerance and heat stress protein synthesis. Br J Cancer 49: 753-758, 1984[ISI][Medline].

43.   Senisterra, GA, Huntley SA, Escaravage M, Sekhar KR, Freeman ML, Borrelli M, and Lepock JR. Destabilization of the Ca2+-ATPase of sarcoplasmic reticulum by thiol-specific, heat shock inducers results in thermal denaturation at 37 degrees C. Biochemistry 36: 11002-11011, 1997[ISI][Medline].

44.   Shi, Y, Mosser DD, and Morimoto RI. Molecular chaperones as HSF1-specific transcriptional repressors. Genes Dev 12: 654-666, 1998[Abstract/Free Full Text].

45.   Sierra-Rivera, E, Meredith MJ, Voorhees GJ, Oberley LW, Eisert DR, and Freeman ML. Synthesis of heat shock proteins following oxidative challenge: role of glutathione. Int J Hyperthermia 10: 573-586, 1994[ISI][Medline].

46.   Sies, H. Glutathione and its role in cellular functions. Free Radic Biol Med 27: 916-921, 1999[ISI][Medline].

47.   Sorger, PK, and Pelham HR. Yeast heat shock factor is an essential DNA-binding protein that exhibits temperature-dependent phosphorylation. Cell 54: 855-864, 1988[ISI][Medline].

48.   Thomas, JA, and Noble EG. Heat shock does not attenuate low-frequency fatigue. Can J Physiol Pharmacol 77: 64-70, 1999[ISI][Medline].

49.   Udelsman, R, Blake MJ, Stagg CA, Li DG, Putney DJ, and Holbrook NJ. Vascular heat shock protein expression in response to stress. Endocrine and autonomic regulation of this age-dependent response. J Clin Invest 91: 465-473, 1993[ISI][Medline].

50.   Wiseman, H, Quinn P, and Halliwell B. Tamoxifen and related compounds decrease membrane fluidity in liposomes. Mechanism for the antioxidant action of tamoxifen and relevance to its anticancer and cardioprotective actions? FEBS Lett 330: 53-56, 1993[ISI][Medline].

51.   Zou, J, Salminen WF, Roberts SM, and Voellmy R. Correlation between glutathione oxidation and trimerization of heat shock factor 1, an early step in stress induction of the Hsp response. Cell Stress Chaperones 3: 130-141, 1998[ISI][Medline].

52.   Zuo, J, Rungger D, and Voellmy R. Multiple layers of regulation of human heat shock transcription factor 1. Mol Cell Biol 15: 4319-4330, 1995[Abstract].


Am J Physiol Cell Physiol 283(2):C404-C411
0363-6143/02 $5.00 Copyright © 2002 the American Physiological Society




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