Heat shock proteins delivered with a virus vector can protect cardiac cells against apoptosis as well as against thermal or hypoxic stress

Acute Changes in Myocardial Expression of Heat Shock Proteins and Apoptotic Response Following Blood, delNido, or Custodiol Cardioplegia in Infants Undergoing Open-Heart Surgery

Stress caused by cardioplegic ischemic arrest was shown to alter the expression levels of heat shock proteins (Hsp), but little is known about their effects, particularly on pediatric hearts. This study aimed to investigate whether myocardial cellular stress and apoptotic response changes due to different cardioplegia (CP) solutions during cardiopulmonary bypass (CPB) in infants and to determine their influence on surgical/clinical outcomes. Therefore, twenty-seven infants for surgical closure of ventricular septal defect were randomly assigned to a CP solution: normothermic blood (BCP), delNido (dNCP), and Custodiol (CCP). Hsp levels and apoptosis were determined by immunoblotting in cardiac tissue from the right atrium before and after CP, and their correlations with cardiac parameters were evaluated. No significant change was observed in Hsp27 levels. Hsp60, Hsp70, and Hsp90 levels decreased significantly in the BCP-group but increased markedly in the CCP-group. Decreased Hsp60 and increased Hsp70 expression were detected in dNCP-group. Importantly, apoptosis was not observed in dNCP- and CCP-groups, whereas marked increases in cleaved caspase-3 and -8 were determined after BCP. Serum cardiac troponin-I (cTn-I), myocardial injury marker, was markedly lower in the BCP- and dNCP-groups than CCP. Additionally, Hsp60, Hsp70, and Hsp90 levels were positively correlated with aortic cross-clamp time, total perfusion time, and cTn-I release. Our findings show that dNCP provides the most effective myocardial preservation in pediatric open-heart surgery and indicate that an increase in Hsp70 expression may be associated with a cardioprotective effect, while an increase in Hsp60 and Hsp90 levels may be an indicator of myocardial damage during CPB.

Intracellular transduction of TAT-Hsp27 fusion protein enhancing cell survival and regeneration capacity of cardiac stem cells in acute myocardial infarction

Myocardial infarction (MI) results in the substantial loss of functional cardiomyocytes, which frequently leads to intractable heart disorders. Cardiac stem cells (CSCs) that retain the capacity to replace all cardiac cells might be a promising strategy for providing a source of new functional cardiomyocytes; however, the poor survival and engraftment of transplanted CSCs in the hostile environment of MI critically mitigate their therapeutic benefits. To capitalize their therapeutic potential, an ex vivo strategy in which CSCs were introduced to the recombinant heat shock protein 27 (Hsp27) through a TAT protein transduction domain for increasing the viability and engraftment in the infarcted myocardium was designed. A recombinant TAT fused Hsp27 (TAT-Hsp27) was able to enter CSCs in a dose-dependent manner. CSCs transduced with TAT-Hsp27 expressed not only endogenous Hsp27 but externally introduced Hsp27, resulting in substantial increase of their anti-oxidative and anti-apoptotic properties via suppressing reactive oxygen species production, the MAPKs signaling pathway, and caspase activation. TAT-Hsp27 enabled CSCs to be protected from apoptotic- and hypoxic-induced cell death during in vitro cardiomyogenic differentiation. In vivo studies demonstrated that CSCs transduced TAT-Hsp27 significantly increased the survival and engraftment in the acutely infarcted myocardium, which is closely related to caspase activity suppression. Finally, CSCs transduced TAT-Hsp27 improved cardiac function and attenuated cardiac remodeling in comparison with non-transduced CSCs. Overall, our approach, which is based on the ex vivo intracellular transduction of TAT-Hsp27 into CSCs before myocardial delivery, might be effective in treating MI.

Transduced protein transduction domain linked HSP27 protected LECs against UVB radiation-induced damage

PTD-fusion protein technology was used to transduce heat shock protein 27 (HSP27), an anti-apoptotic protein, into human lens epithelial cells (HLECs) (SRA01/04). The protein transduction domain (PTD) of the 11-amino acid YGRKKRRQRRR was tagged at the N-terminus of HSP27. The fusion protein was purified from bacteria transformed with a pKYB-PTD-HSP27 construct. The HLECs were incubated with PTD-HSP27-FITC and the fluorescence inside HLECs was found by fluorescence microscopic examination. To test the ability of PTD-HSP27 to pass through the corneas, PTD-HSP27-FITC was dropped onto the conjunctival sacs of rabbits; fluorescent labeled PTD-HSP27 was then observed in the rabbit aqueous humor. After being incubated with the PTD-HSP27 protein and irradiated with ultraviolet-B (UVB) light, HLECs was analyzed by flow cytometry, Hoechst 33258 staining and measurement of the potential of the mitochondrial transmembrane. HLECs incubated with PTD-HSP27 had a lower apoptotic rate and a higher mitochondrial membrane potential than the control cells. PTD-HSP27 appears to be sufficient to protect HLECs against UVB-induced apoptosis.

Protein O-GlcNAcylation is a novel cytoprotective signal in cardiac stem cells

Clinical trials demonstrate the regenerative potential of cardiac stem cell (CSC) therapy in the postinfarcted heart. Despite these encouraging preliminary clinical findings, the basic biology of these cells remains largely unexplored. The principal requirement for cell transplantation is to effectively prime them for survival within the unfavorable environment of the infarcted myocardium. In the adult mammalian heart, the β-O-linkage of N-acetylglucosamine (i.e., O-GlcNAc) to proteins is a unique post-translational modification that confers cardioprotection from various otherwise lethal stressors. It is not known whether this signaling system exists in CSCs. In this study, we demonstrate that protein O-GlcNAcylation is an inducible stress response in adult murine Sca-1(+) /lin(-) CSCs and exerts an essential prosurvival role. Posthypoxic CSCs responded by time-dependently increasing protein O-GlcNAcylation upon reoxygenation. We used pharmacological interventions for loss- and gain-of-function, that is, enzymatic inhibition of O-GlcNAc transferase (OGT) (adds the O-GlcNAc modification to proteins) by TT04, or inhibition of OGA (removes O-GlcNAc) by thiamet-G (ThG). Reduction in the O-GlcNAc signal (via TT04, or OGT gene deletion using Cre-mediated recombination) significantly sensitized CSCs to posthypoxic injury, whereas augmenting O-GlcNAc levels (via ThG) enhanced cell survival. Diminished O-GlcNAc levels render CSCs more susceptible to the onset of posthypoxic apoptotic processes via elevated poly(ADP-ribose) polymerase cleavage due to enhanced caspase-3/7 activation, whereas promoting O-GlcNAcylation can serve as a pre-emptive antiapoptotic signal regulating the survival of CSCs. Thus, we report the primary demonstration of protein O-GlcNAcylation as an important prosurvival signal in CSCs, which could enhance CSC survival prior to in vivo autologous transfer.

Proteomic study on the protective mechanism of fibroblast growth factor 21 to ischemia-reperfusion injury

Fibroblast growth factor (FGF)-21 is a novel regulator of insulin-independent glucose transport in 3T3-L1 adipocytes and has glucose and triglyceride lowering effects in rodent models of diabetes. In this study, we found that FGF-21 can significantly attenuate ischemia-reperfusion (I/R) induced damage in H9c2 cells (rat heart). However, it is unclear which signal transduction pathway is involved in the cardioprotective effect of FGF-21. Thus, this study was designed to investigate the potential mechanism induced by FGF-21. The results showed that FGF-21 treatment prevented the oxidative stress and apoptosis associated with I/R damage by reducing the levels of superoxide anions, inhibiting glycogen synthase kinase (GSK) 3β by activating Akt phosphorylation, and recovering the levels of ATP synthase pyruvate kinase isozymes M1 and protein kinase C, thereby improving energy supply. In summary, we conclude that FGF-21 protects H9c2 cells against I/R injury mainly through the Akt-GSK-3β-caspase-3 dependent pathway, preventing oxidative stress, and recovery of the energy supply.

Heat shock protein 27 is increased in cyanotic tetralogy of Fallot myocardium and is associated with improved cardiac output and contraction

Tetralogy of Fallot (TOF) is a congenital heart condition in which the right ventricle is exposed to cyanosis and pressure overload. Patients have an increased risk of right ventricle dysfunction following corrective surgery. Whether the cyanotic myocardium is less tolerant of injury compared to non-cyanotic is unclear. Heat shock proteins (HSPs) protect against cellular stresses. The aim of this study was to examine HSP 27 expression in the right ventricle resected from TOF patients and determine its relationship with right ventricle function and clinical outcome. Ten cyanotic and ten non-cyanotic patients were studied. Western blotting was used to quantify HSP 27 in resected myocardium at (1) baseline (first 15 min of aortic cross clamp and closest representation of pre-operative status) and (2) after 15 min during ischemia until surgery was complete. The cyanotic group had significantly increased haematocrit, lower O2 saturation, thicker interventricular septal wall thickness and released more troponin-I on post-operative day 1 (p < 0.05). HSP 27 expression was significantly increased in the < 15 min cyanotic compared to the < 15 min non-cyanotic group (p = 0.03). In the cyanotic group, baseline HSP 27 expression also significantly correlated with oxygen extraction ratio (p = 0.028), post-operative basal septal velocity (p = 0.036) and mixed venous oxygen saturation (p = 0.02), markers of improved cardiac output/contraction. Increased HSP 27 expression and associated improved right ventricle function and systemic perfusion supports a cardio-protective effect of HSP 27 in cyanotic TOF.

Angiogenic therapy for cardiac repair based on protein delivery systems

Cardiovascular diseases remain the first cause of morbidity and mortality in the developed countries and are a major problem not only in the western nations but also in developing countries. Current standard approaches for treating patients with ischemic heart disease include angioplasty or bypass surgery. However, a large number of patients cannot be treated using these procedures. Novel curative approaches under investigation include gene, cell, and protein therapy. This review focuses on potential growth factors for cardiac repair. The role of these growth factors in the angiogenic process and the therapeutic implications are reviewed. Issues including aspects of growth factor delivery are presented in relation to protein stability, dosage, routes, and safety matters. Finally, different approaches for controlled growth factor delivery are discussed as novel protein delivery platforms for cardiac regeneration.

Gene transfer of heme oxygenase-1 using an adeno-associated virus serotype 6 vector prolongs cardiac allograft survival

Introduction. Allograft survival can be prolonged by overexpression of cytoprotective genes such as heme oxygenase-1 (HO-1). Modifications in vector design and delivery have provided new opportunities to safely and effectively administer HO-1 into the heart prior to transplantation to improve long-term graft outcome. Methods. HO-1 was delivered to the donor heart using an adeno-associated virus vector (AAV) with a pseudotype 6 capsid and vascular endothelial growth factor (VEGF) to enhance myocardial tropism and microvascular permeability. Survival of mouse cardiac allografts, fully or partially mismatched at the MHC, was determined with and without cyclosporine A. Intragraft cytokine gene expression was examined by PCR. Results. The use of AAV6 to deliver HO-1 to the donor heart, combined with immunosuppression, prolonged allograft survival by 55.3% when donor and recipient were completely mismatched at the MHC and by 94.6% if partially mismatched. The combination of gene therapy and immunosuppression was more beneficial than treatment with either AAV6-HO-1 or CsA alone. IL-17a, b, e and f were induced in the heart at rejection. Conclusions. Pretreatment of cardiac allografts with AAV6-HO-1 plus cyclosporine A prolonged graft survival. HO-1 gene therapy represents a beneficial adjunct to immunosuppressive therapy in cardiac transplantation.

Anti-Heat Shock Protein 27 Titers and Oxidative Stress Levels are Elevated in Patients With Valvular Heart Disease

We studied the immune responses to heat shock protein (Hsp)-27 and pro-oxidant–antioxidant balance (PAB) values in patients with valvular heart disease, but free of angiographically evident coronary artery disease (CAD). Patients who were candidates for valvuloplasty surgery and 30 healthy matched controls were recruited. The anti-Hsp-27 antibody titers were 0.35 ± 0.04 absorbency units (AU) in the valvuloplasty group, being significantly higher than for the controls (0.11 ± 0.02 AU; P < .05). The PAB values were significantly higher in cases (134.67 ± 13.69 Hamidi-Koliakos(HK) unit) when compared with controls (49.78 ± 6.75 HK unit; P < .05). In cases, the ejection fraction was inversely correlated with anti-Hsp-27 antibody ( P < .05) but was not significantly related to PAB values ( P > .05). Based on the echocardiographic findings, the patients had no evident heart failure, but the high levels of anti-Hsp-27 and PAB values in patients with valvular heart disease may indicate that these variables can be used as markers of heart failure. However, a longitudinal study is required to confirm this hypothesis.

Sca-1+ cardiac stem cells mediate acute cardioprotection via paracrine factor SDF-1 following myocardial ischemia/reperfusion

Background

Cardiac stem cells (CSCs) promote myocardial recovery following ischemia through their regenerative properties. However, little is known regarding the implication of paracrine action by CSCs in the setting of myocardial ischemia/reperfusion (I/R) injury although it is well documented that non-cardiac stem cells mediate cardioprotection via the production of paracrine protective factors. Here, we studied whether CSCs could initiate acute protection following global myocardial I/R via paracrine effect and what component from CSCs is critical to this protection.

Methodology/Principal Findings

A murine model of global myocardial I/R was utilized to investigate paracrine effect of Sca-1+ CSCs on cardiac function. Intracoronary delivery of CSCs or CSC conditioned medium (CSC CM) prior to ischemia significantly improved myocardial function following I/R. siRNA targeting of VEGF in CSCs did not affect CSC-preserved myocardial function in response to I/R injury. However, differentiation of CSCs to cardiomyocytes (DCSCs) abolished this protection. Through direct comparison of the protein expression profiles of CSCs and DCSCs, SDF-1 was identified as one of the dominant paracrine factors secreted by CSCs. Blockade of the SDF-1 receptor by AMD3100 or downregulated SDF-1 expression in CSCs by specific SDF-1 siRNA dramatically impaired CSC-induced improvement in cardiac function and increased myocardial damage following I/R. Of note, CSC treatment increased myocardial STAT3 activation after I/R, whereas downregulation of SDF-1 action by blockade of the SDF-1 receptor or SDF-1 siRNA transfection abolished CSC-induced STAT3 activation. In addition, inhibition of STAT3 activation attenuated CSC-mediated cardioprotection following I/R. Finally, post-ischemic infusion of CSC CM was shown to significantly protect I/R-caused myocardial dysfunction.

Conclusions/Significance

This study suggests that CSCs acutely improve post-ischemic myocardial function through paracrine factor SDF-1 and up-regulated myocardial STAT3 activation.

Distinct role of Hsp70 in Drosophila hemocytes during severe hypoxia

Severe hypoxia can lead to injury and mortality in vertebrate or invertebrate organisms. Our research is focused on understanding the molecular mechanisms that lead to injury or adaptation to hypoxic stress using Drosophila as a model system. In this study, we employed the UAS-Gal4 system to dissect the protective role of Hsp70 in specific tissues in vivo under severe hypoxia. In contrast to overexpression in tissues such as muscles, heart, and brain, we found that overexpression of Hsp70 in hemocytes of flies provides a remarkable survival benefit to flies exposed to severe hypoxia for days. Furthermore, these flies were tolerant not only to severe hypoxia but also to other stresses such as oxidant stress (e.g., paraquat feeding or hyperoxia). Interestingly we observed that the better survival with Hsp70 overexpression in hemocytes under hypoxia or oxidant stress is causally linked to reactive oxygen species (ROS) reduction in whole flies. We also show that hemocytes are a major source of ROS generation, leading to injury during hypoxia, and their elimination results in a better survival under hypoxia. Hence, our study identified a protective role for Hsp70 in Drosophila hemocytes, which is linked to ROS reduction in the whole flies and thus helps in their remarkable survival during oxidant or hypoxic stress.

Transgenic overexpression of HSP56 does not result in cardiac hypertrophy nor protect from ischaemia/reperfusion injury

Heat shock proteins are known to be induced during and following different forms of cardiac stress. It has previously been shown that their expression is beneficial for the heart following trauma such as ischaemia-reperfusion (I/R) injury. Heat shock protein 56 (HSP56) belongs to the family of FK506-binding immunophilin proteins and is found in steroid receptor complexes, notably the glucocorticoid receptor. We have previously shown that HSP56 and other HSPs are induced in cardiac myocytes treated with cardiotrophin-1, a cytokine with potent hypertrophic and protective properties on cardiac cells. The hypertrophic action of cardiotrophin-1 on cardiac cells is dependent on HSP56 induction and overexpression of HSP56 is sufficient for inducing hypertrophy in cardiac cells. To investigate this phenomenon in vivo, we have generated transgenic mice overexpressing HSP56 and assessed them for the development cardiac hypertrophy and resistance of their hearts to I/R-injury by Langendorff perfusion. Mice generated demonstrated stable, yet varying expression levels of HSP56. Initial characterisation identified a sex-specific phenotype where male overexpressing mice exhibited a moderate, but significant, reduced body weight compared to wild-type controls. In ex vivo stress analyses we found, unexpectedly, that significant overexpression of HSP56 does not induce myocardial hypertrophy and nor does it protect the intact heart from I/R-injury. These observations now suggest a more intricate HSP56-Sp. Cardiophenotype that requires further studies to determine if HSP56 is necessary in mediating hypertrophy induced by other myocardial stimuli.

Protective effect of phosphorylated Hsp27 in coronary arteries through actin stabilization

There is evidence for an inverse association between cellular expression of Hsp27 and vascular disease with carotid plaques, endarterectomy specimens, and cardiac biopsies investigated to date. Here we compare non-diseased coronary arteries from human heart transplant donors and patients with dilated cardiomyopathy (DCM) with no evidence of coronary artery disease, to coronary arteries from patients with ischemic heart disease (IHD) in order to determine abundance of phosphorylated Hsp27 (phospho-Hsp27) in plaque-free diseased vessels and elucidate how this protective effect is brought about through protein regulation. Western blotting identified phospho-Hsp27, phosphorylated on Ser82, Ser78, and Ser15, to be specifically decreased in IHD, but not DCM, compared to non-diseased vessels. Immunohistochemistry confirmed these results and revealed phospho-Hsp27 was located within both smooth muscle and endothelial cells. Disease-free coronary arteries and from patients with IHD were then subjected to 2-Dimensional Difference Gel Electrophoresis (2D-DIGE) analysis to detect proteins with altered abundance, which were subsequently identified by mass spectrometry. Hsp27 showed decreased abundance in ischemic vessels as expected. The expression of cytoskeletal proteins, namely vimentin was significantly reduced, while transgelin and tropomyosin showed significantly increased abundance in vessels with IHD. Immunohistochemistry studies suggested an increase in G-actin abundance to be present within IHD vessels. The results are consistent with the hypothesis that phospho-Hsp27 protects against vascular disease possibly by stabilizing the actin cytoskeleton within endothelial and/or smooth muscle cells.

Mesenchymal stem cells pretreated with delivered Hph-1-Hsp70 protein are protected from hypoxia-mediated cell death and rescue heart functions from myocardial injury

Mesenchymal stem cell (MSC) therapy for myocardial injury has inherent limitations due to the poor viability of MSCs after cell transplantation. In this study, we directly delivered Hsp70, a protein with protective functions against stress, into MSCs, using the Hph-1 protein transduction domain ex vivo for high transfection efficiency and low cytotoxicity. Compared to control MSCs in in vitro hypoxic conditions, MSCs delivered with Hph-1-Hsp70 (Hph-1-Hsp70-MSCs) displayed higher viability and anti-apoptotic properties, including Bcl2 increase, reduction of Bax, JNK phosphorylation and caspase-3 activity. Hsp70 delivery also attenuated cellular ATP-depleting stress. Eight animals per group were used for in vivo experiments after occlusion of the left coronary artery. Transplantation of Hph-1-Hsp70-MSCs led to a decrease in the fibrotic heart area, and significantly reduced the apoptotic positive index by 19.5 +/- 2%, compared to no-treatment controls. Hph-1-Hsp70-MSCs were well-integrated into the infarcted host myocardium. The mean microvessel count per field in the infarcted myocardium of the Hph-1-Hsp70-MSC-treated group (122.1 +/- 13.5) increased relative to the MSC-treated group (75.9 +/- 10.4). By echocardiography, transplantation of Hph-1-Hsp70-MSCs resulted in additional increases in heart function, compared to the MSCs-transplanted group. Our results may help formulate better clinical strategies for in vivo MSC cell therapy for myocardial damage.

Controlled delivery of heat shock protein using an injectable microsphere/hydrogel combination system for the treatment of myocardial infarction

Myocardial infarction causes a high rate of morbidity and mortality worldwide, and heat shock proteins as molecular chaperones have been attractive targets for protecting cardiomyoblasts under environmental stimuli. In this study, in order to enhance the penetration of heat shock protein 27 (HSP27) across cell membranes, we fused HSP27 with transcriptional activator (TAT) derived from human immunodeficiency virus (HIV) as a protein transduction domain (PTD). We loaded the fusion protein (TAT-HSP27) into microsphere/hydrogel combination delivery systems to control the release behavior for prolonged time periods. We found that the release behavior of TAT-HSP27 was able to be controlled by varying the ratio of PLGA microspheres and alginate hydrogels. Indeed, the released fusion protein maintained its bioactivity and could recover the proliferation of cardiomyoblasts cultured under hypoxic conditions. This approach to controlling the release behavior of TAT-HSP27 using microsphere/hydrogel combination delivery systems may be useful for treating myocardial infarction in a minimally invasive manner.

Irradiation leads to apoptosis of Kupffer cells by a Hsp27-dependant pathway followed by release of TNF-alpha

In a previous publication, we were able to show that irradiation of Kupffer cells, the liver resident macrophages, leads to an increased TNF-alpha concentration in the culture medium. The pathomechanisms underlying this phenomenon, however, remained to be elucidated. Here, we show that following irradiation of Kupffer cells, the apoptosis rate increased drastically within 48 h. At the same time, the total TNF-alpha concentration in cell lysates of Kupffer cells attached to the culture plate decreased. However, normalization of the TNF-alpha concentration with respect to cell number revealed that TNF-alpha concentration per attached cell remained constant during the observation period. Western blot analysis showed that heat shock protein 27 (Hsp27) is strongly downregulated and bax is upregulated in irradiated Kupffer cells as compared to sham-irradiated cells. Overexpression of Hsp27 in Kupffer cells was shown to prevent the effect of irradiation on bax expression, apoptosis and, at the same time, on increase of TNF-alpha concentration in the Kupffer cell medium. We conclude that irradiation of Kupffer cells leads to apoptosis because of downregulation of Hsp27 and consecutive upregulation of bax expression. Furthermore, we suggest that apoptosis of Kupffer cells leads to an increase of TNF-alpha concentration in the culture medium which may be due to cell death rather than active release or synthesis.

Glucosamine protects neonatal cardiomyocytes from ischemia-reperfusion injury via increased protein O-GlcNAc and increased mitochondrial Bcl-2

We have previously reported that glucosamine protected neonatal rat ventricular myocytes against ischemia-reperfusion (I/R) injury, and this was associated with an increase in protein O-linked-N-acetylglucosamine (O-GlcNAc) levels. However, the protective effect of glucosamine could be mediated via pathways other that O-GlcNAc formation; thus the initial goal of the present study was to determine whether increasing O-GlcNAc transferase (OGT) expression, which catalyzes the formation of O-GlcNAc, had a protective effect similar to that of glucosamine. To better understand the potential mechanism underlying O-GlcNAc-mediated cytoprotection, we examined whether increased O-GlcNAc levels altered the expression and translocation of members of the Bcl-2 protein family. Both glucosamine (5 mM) and OGT overexpression increased basal and I/R-induced O-GlcNAc levels, significantly decreased cellular injury, and attenuated loss of cytochrome c. Both interventions also attenuated the loss of mitochondrial membrane potential induced by H2O2 and were also associated with an increase in mitochondrial Bcl-2 levels but had no effect on Bad or Bax levels. Compared with glucosamine and OGT overexpression, NButGT (100 microM), an inhibitor of O-GlcNAcase, was less protective against I/R and H2O2 and did not affect Bcl-2 expression, despite a 5- to 10-fold greater increase in overall O-GlcNAc levels. Decreased OGT expression resulted in lower basal O-GlcNAc levels, prevented the I/R-induced increase in O-GlcNAc and mitochondrial Bcl-2, and increased cellular injury. These results demonstrate that the protective effects of glucosamine are mediated via increased formation of O-GlcNAc and suggest that this is due, in part, to enhanced mitochondrial Bcl-2 translocation.

Hsp27 inhibits Bax activation and apoptosis via a phosphatidylinositol 3-kinase-dependent mechanism

Hsp27 inhibits mitochondrial injury and apoptosis in both normal and cancer cells by an unknown mechanism. To test the hypothesis that Hsp27 decreases apoptosis by inhibiting Bax, Hsp27 expression was manipulated in renal epithelial cells before transient metabolic stress, an insult that activates Bax, induces mitochondrial injury, and causes apoptosis. Compared with control, enhanced Hsp27 expression inhibited conformational Bax activation, oligomerization, and translocation to mitochondria, reduced the leakage of both cytochrome c and apoptosis-inducing factor, and significantly improved cell survival by >50% after stress. In contrast, Hsp27 down-regulation using RNA-mediated interference promoted Bax activation, increased Bax translocation, and reduced cell survival after stress. Immunoprecipitation did not detect Hsp27-Bax interaction before, during, or after stress, suggesting that Hsp27 indirectly inhibits Bax. During stress, Hsp27 expression prevented the inactivation of Akt, a pro-survival kinase, and increased the interaction between Akt and Bax, an Akt substrate. In contrast, Hsp27 RNA-mediated interference promoted Akt inactivation during stress. Hsp27 up- or down-regulation markedly altered the activity of phosphatidylinositol 3-kinase (PI3-kinase), a major regulator of Akt. Furthermore, distinct PI3-kinase inhibitors completely abrogated the protective effect of Hsp27 expression on Akt activation, Bax inactivation, and cell survival. These data show that Hsp27 antagonizes Bax-mediated mitochondrial injury and apoptosis by promoting Akt activation via a PI3-kinase-dependent mechanism.

Myocardial heat shock protein changes in the failing heart following coronary artery ligation

BACKGROUND

Production of several heat shock proteins (Hsp) is enhanced after exposure to stress. There is little information concerning changes in myocardial Hsp under pathophysiological conditions. The aim of this study was to determine alterations in Hsp content in the viable left ventricular myocardium during the development of heart failure following coronary artery ligation (CAL).

METHODS

Myocardial infarction was produced by CAL of Wistar rats. One and eight weeks after the operation, haemodynamic parameters of rats with CAL were determined and then expression of Hsp27, Hsp60 and Hsp72 was measured by western blotting.

RESULTS

Animals showed a decrease in cardiac output and an increase in left ventricular end-diastolic pressure, symptoms of chronic heart failure (CHF), 8 weeks after CAL. Myocardial Hsp27 and Hsp72 at 1 week after CAL significantly increased, whereas expression of both proteins at 8 weeks was similar to that in rats which underwent a sham operation (without coronary artery ligation). In contrast, Hsp60 at 8 weeks, but not at 1 week, significantly increased in the sham rats.

CONCLUSIONS

Diverse changes in myocardial Hsp occurred during the development of CHF.

Protective effect of heat shock protein 27 using protein transduction domain-mediated delivery on ischemia/reperfusion heart injury

Heat shock protein 27 (HSP27) is an intracellular stress protein with the cytoprotective effect for a variety of noxious stresses. In this study, using a protein delivery system, we demonstrated the potential cytoprotective effect of HSP27 as a therapeutic protein in cardiac cells and ischemia/reperfusion animal model. We constructed a recombinant HSP27 fused to the protein transduction domain (PTD) derived from HIV-1 TAT protein. Purified recombinant TAT-HSP27 protein was efficiently delivered to H9c2 cells, and its transduction showed cytoprotective effect against the hypoxic stress. Moreover, transduction of TAT-HSP27 also attenuated hypoxia-induced apoptosis, which was accompanied by reduced caspase-3 activity. In addition, intraperitoneal injection of TAT-HSP27 into rat resulted in efficient protein transduction in heart tissues, decreased infarcted myocardium (control vs TAT-HSP27, 39.1% vs 29.5%, P<0.05) and preserved heart function (fractional shortening, 15.6% vs 33.4%, P<0.05), as determined at 7 d after I/R. These results suggest that the PTD-mediated delivery of HSP27 protein may represent a potential therapeutic strategy as protein drug for ischemic heart diseases.

Over-expression of heat shock protein 27 attenuates doxorubicin-induced cardiac dysfunction in mice

BACKGROUND

Oxidative stress and myocyte apoptosis are thought to play an important role in the pathogenesis, progression and prognosis of heart failure (HF). Heat shock protein 27 (Hsp27) has been found to confer resistance to oxidative stress in cultured cells; however, the role of Hsp27 in in-vivo hearts remains to be determined.

AIM

To investigate the effects of Hsp27 over-expression on doxorubicin-induced HF.

METHODS AND RESULTS

Transgenic mice (TG) with cardiac specific over-expression of Hsp27 and their wild type littermates (WT) were challenged with doxorubicin (25 mg/kg, IP) to induce HF. At day 5, TG mice had significantly improved cardiac function and viability and decreased loss of heart weight following doxorubicin exposure compared with WT. In another parallel experiment, doxorubicin-induced increased levels of reactive oxygen species, protein carbonylation, apoptosis and morphologic changes were detected in the mitochondria in WT hearts, whereas these effects were markedly attenuated in TG hearts. In addition, upregulation of heat shock protein 70 and heme oxygenase-1 was present in the TG hearts after doxorubicin stimulation in comparison to WT hearts.

CONCLUSION

These findings indicate that Hsp27 may play a key role in resistance to doxorubicin-induced cardiac dysfunction.

The cellular "networking" of mammalian Hsp27 and its functions in the control of protein folding, redox state and apoptosis

Cells possess effective mechanisms to cope with chronic or acute disturbance of homeostasis. Key roles in maintaining or restoring homeostasis are played by the various heat shock or stress proteins (Hsps). Among the Hsps, the group of proteins characterized by low molecular masses (between 20 to 30 kDa) and homology to alpha-crystallin are called small stress proteins (denoted sHsps). The present chapter summarizes the actual knowledge of the protective mechanisms generated by the expression of mammalian Hsp27 (also denoted HspB1 in human) against the cytotoxicity induced by heat shock and oxidative stress. It also describes the anti-apoptotic properties of Hsp27 and their putative consequences in different pathological conditions.

Endothelial STAT3 plays a critical role in generalized myocardial proinflammatory and proapoptotic signaling

Signal transducer and activator of transcription (STAT) 3 is involved in mediating a broad range of biological processes, including cell survival, proliferation, and immune response. Recent evidence has indicated that STAT3 in cardiomyocytes can be activated by ischemic-oxidative stress and exerts cardioprotection in the ischemic heart. There is no information, however, regarding the effect of endothelial cell-derived STAT3 on the myocardial response to ischemiareperfusion (I/R) injury. We hypothesized that the ablation of the STAT3 gene in endothelial cells would worsen postischemic myocardial function by affecting capillary network integrity, suppressing antiapoptotic signaling. Isolated hearts from wild-type and endothelial cell STAT3 knockout (STAT3KO) mice were subjected to 20 min of global ischemia followed by 60 min of reperfusion. Endothelial cell STAT3 deficiency decreased recovery of myocardial function in response to I/R, which was associated with higher levels of LDH release, decreased activation of myocardial STAT3, and elevated p38 MAPK activation in STAT3 endothelial knockout (KO) hearts. In addition, although no significant apoptosis was observed in wild-type and KO hearts, our results showed more expression of myocardial caspase-8 and more apoptosis in the myocardium around the capillary in STAT3KO mice subjected to I/R. Furthermore, endothelial cell STAT3 ablation resulted in increased myocardial expression of IL-6 and suppressor of cytokine signal 3. This study demonstrates that endothelial cell-derived STAT3 plays an important role in postischemic myocardial function.

Hsp27 (HspB1) and alphaB-crystallin (HspB5) as therapeutic targets

Hsp27 and alphaB-crystallin are molecular chaperones that are constitutively expressed in several mammalian cells, particularly in pathological conditions. These proteins share functions as diverse as protection against toxicity mediated by aberrantly folded proteins or oxidative-inflammation conditions. In addition, these proteins share anti-apoptotic properties and are tumorigenic when expressed in cancer cells. This review summarizes the current knowledge about Hsp27 and alphaB-crystallin and the implications, either positive or deleterious, of these proteins in pathologies such as neurodegenerative diseases, myopathies, asthma, cataracts and cancers. Approaches towards therapeutic strategies aimed at modulating the expression and/or the activities of Hsp27 and alphaB-crystallin are presented.

Niacin-bound chromium enhances myocardial protection from ischemia-reperfusion injury

A novel niacin-bound, chromium-based energy formula (EF; InterHealth Nutraceuticals, Benicia, CA) has been developed in conjunction with D-ribose, caffeine, ashwagandha extract (containing 5% withanolides), and selected amino acids. We have assessed the efficacy of oral administration of EF (40 mg x kg body wt(-1) x day(-1)) in male and female rats over a period of 90 consecutive days on the cardiovascular and pathophysiological functions in an isolated rat heart model. After 30, 60, and 90 days of treatment with EF, the hearts of male and female rats were subjected to 30 min of global ischemia followed by 2 h of reperfusion and were measured for myocardial ATP, creatine phosphate (CP), phosphorylated AMP kinase (p-AMPK), and heat shock proteins. Myocardial ATP and CP levels were increased in both male and female rats after EF treatment compared with the controls. Western blot analyses were performed to quantify the expression of stress-related proteins such as heat shock proteins (HSP-70, -32, and -25) and are found to be increased in both male and female rats after EF treatment. The p-AMPK level, which is a sensor for the energy state in various cell types, was also found to be increased after treatment with EF in both male and female rats. Aortic flow, maximum first derivative of developed pressure, left ventricular developed pressure, and infarct size were observed after ischemia-reperfusion and found to be significantly improved in EF-treated rats compared with control animals. Thus EF demonstrated long-term safety as well as exhibiting significant cardioprotective ability during ischemia and reperfusion injury by increased energy production, improved cardiac function, and reduced infarct size.

THERMAL PRECONDITIONING PROTECTS THE HUMAN INTERNAL MAMMARY ARTERY FROM HYPOXIA/RE-OXYGENATION-INDUCED DAMAGE

1. Preconditioning has been demonstrated to ameliorate ischaemia/reperfusion injury in several cells and tissues. Therefore, in the present study we investigated whether preconditioning of human bypass grafts, internal mammary artery (IMA) and saphenous vein (SV) induces heat shock protein (Hsp) expression and reduces apoptosis in response to subsequent hypoxia/re-oxygenation damage in both vessels. 2. Internal mammary artery and SV rings, obtained from 30 patients (median age 66.5 years) undergoing coronary artery bypass grafting, were either incubated for 30 min at 42 degrees C (preconditioned) or kept in a standard incubator at 37 degrees C (not preconditioned). Six hours later, graft segments were exposed to 90 min hypoxia followed by a 30 min re-oxygenation period. Western blot, real-time quantative polymerase chain reaction analysis and apoptosis detection by the Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling method were performed. 3. Heat-preconditioned IMA showed significantly increased protein expression of Hsp72 after hypoxia/re-oxygenation treatment compared with controls (median 9.1 vs 5.0 microg/mg total protein; P = 0.048). Expression of Hsp73 was weak and Hsp60 was not detectable in the IMA. 4. In the SV, neither protein nor mRNA expression of Hsp were significantly different between preconditioned and not preconditioned veins. 5. There were significantly fewer apoptotic cells in the intima of the preconditioned compared with not preconditioned IMA (P = 0.041) after hypoxia/re-oxygenation injury, whereas in the SV apoptosis was not significantly prevented by preconditioning. 6. Mild heat preconditioning before hypoxia/re-oxygenation injury is a stimulus for Hsp72 protein expression and a reduction in apoptosis in the human IMA.

Brain temperature during 340-kHz pulsed ultrasound insonation: a safety study for sonothrombolysis

BACKGROUND AND PURPOSE

Because ultrasound is used for improving thrombolysis of cerebral infarction but continuous ultrasound insonation also has significant thermal effects, we evaluated brain temperature increase and tissue destruction during pulsed ultrasound emission.

METHODS

We examined 340-kHz pulsed ultrasound effects in male Wistar rats. Ultrasound was applied transcranially for 30 minutes on different power levels (1 to 7 W/cm2). Temperature was measured at different locations (brain, in the focus of ultrasound beam, inner ear, temporalis muscle, and rectum). The cooling time after 30-minute insonation for every power level was recorded, and animals were examined by postmortem brain histology (TUNEL and hematoxylin/eosin).

RESULTS

Brain temperature increased within 2 to 5 minutes of insonation. Brain temperature increase and cooling time were in proportion to power level, and even with the highest intensity of 7 W/cm2 for 30 minutes, the maximum elevation of mean brain temperature was 0.9 degrees C, with the highest cooling time of 40 minutes. No deleterious side effects of this treatment could be found in histological examination.

CONCLUSIONS

Using a pulsed ultrasound design, only a moderate temperature increase could be observed with no histopathological abnormalities. Deleterious side effects of mid-kilohertz ultrasound (eg, intracerebral hemorrhage) are therefore not a consequence of local brain temperature increase.

Hsf1-mediated stress response can transiently enhance cellular radioresistance

To elucidate how the heat-shock transcription factor 1 (Hsf1)-mediated stress response affects cellular radioresistance, mouse embryo fibroblasts with Hsf1-gene knockout (Hsf1(-/-) cells) or with normal wild-type Hsf1 expression (Hsf1 wild-type cells) were preconditioned by heating (43 degrees C, 30 min) without or with quercetin (an inhibitor of Hsf1) and then exposed to gamma radiation (4 or 6 Gy). Some cell samples were infected with virus-based vectors to overexpress the constitutively active (mutant) form of Hsf1 or individual heat-shock proteins (Hsps). The heat preconditioning transiently up-regulated the Hsp levels in Hsf1 wild-type cells and significantly improved their postirradiation survival; these effects could be abolished by quercetin or simulated (without preheating) by the Hsf1 overexpression. In contrast, no enhanced radioresistance was found in heat-preconditioned Hsf1(-/-) cells that were unable to trigger Hsf1-mediated Hsp induction after heating. However, when the constitutively active Hsf1 was overexpressed in Hsf1(-/-) cells, the latter accumulated stress-inducible Hsps and became more radioresistant like heat-preconditioned Hsf1 wild-type cells. The overexpression of Hsp70 or/ and Hsp27 also enhanced radioresistance of both cell cultures. Thus the preirradiation stress response resulting in the intracellular Hsp accumulation can improve survival of severely irradiated mammalian cells.

Castration inhibits exercise-induced accumulation of Hsp70 in male rodent hearts

Intense exercise leads to accumulation of the inducible member of the 70-kDa family of heat shock proteins, Hsp70, in male, but not female, hearts. Estrogen is at least partially responsible for this difference. Because androgen receptors are expressed in the heart and castration leads to decreases in calcium regulatory proteins and altered cardiac function, testosterone (T) or its metabolites could also be involved. We hypothesized that removal of endogenous T production through castration would reduce cardiac Hsp70 accumulation after an acute exercise bout, whereas castrated animals supplemented with 5α-dihydrotestosterone (DHT) would show the intact male response. Fifty-four 8-wk-old male Sprague-Dawley rats were divided into intact, castrated, or castrated + DHT groups ( n = 18/group). At 11 wk of age, 12 animals in each group undertook a 60-min bout of treadmill running at 30 m/min (2% incline) while the remaining 6 in each group remained sedentary. At 30 min or 24 h after exercise ( n = 6/time point), blood and hearts were harvested for analysis. Serum T was undetectable in castrated and DHT-treated castrated rats, whereas serum DHT was significantly reduced in castrated animals only (∼60% reduction) ( P < 0.05). Although there were no differences in constitutive levels of Hsp70 protein, exercise significantly increased cardiac hsp70 mRNA and protein in intact and DHT-supplemented rats, but not in castrated animals ( P < 0.05). To examine whether castration eliminated the ability to respond to stress, another six intact and six castrated animals were subjected to a 15-min period of hyperthermia (core temperature raised to 42°C) and killed 24 h later. As opposed to exercise, castrated animals subjected to heat shock exhibited increases in Hsp70 above nonshocked (i.e., sedentary) animals, similarly to intact males ( P < 0.05). These data suggest that androgens, in addition to estrogen, play a role in the sexual dimorphism observed in the stress response to exercise but not heat shock.

[The toxic aggregation of proteins: a kind of "molecular delinquency" actively fought in the cell by molecular chaperones and proteases]

Under various stresses, mutation-sensitised proteins may spontaneously convert into inactive, aggregation-prone structures, which may be cytotoxic and infectious. In the cell, this new kind of "molecular criminality" is actively fought against by a network of molecular chaperones that can specifically identify, isolate and unfold damaged (delinquent) proteins and favour their subsequent native refolding. Irreversibly damaged molecules unable to natively refold are preferentially "executed" and recycled by proteases. Failing that, they are "imprisoned" within compact amyloids, or "evicted" from the cell. Thus, striking parallels, although of questionable ethical value, exist between protein and human criminality, and between the cellular and social responses to these different types of criminality. Fundamental differences also exist. Whereas programmed death (apoptosis) is the preferred solution chosen by aged and aggregation-stressed cells, collective suicide is seldom an option chosen by lawless human societies. More significantly, there is no clear cellular equivalent for the role of the family and the education system, which are so essential to the proper shaping of functional individuals in the society, and give rise to humanism, that favours crime prevention, reeducation and reinsertion programs over capital punishment. To the cardiologist and transplantation surgeon, the interest of molecular chaperones, in particular of Hsp70, Hsp90 and Hsp27, lays in their ability to inhibit the signalling pathway of programmed cell death. Their induction before and during ischemia, by various treatments and drugs could significantly reduce damages from the post ischemic reperfusion of organs.

The influence of extremely low frequency magnetic fields on cytoprotection and repair

Ischemia-reperfusion injuries, such as those suffered from various types of cardiovascular disease, are major causes of death and disability. For relatively short periods of ischemia, much of the damage is potentially reversible and in fact, does not occur until the influx of oxygen during the reperfusion stage. Because of this, there is a window of opportunity to protect the ischemic tissue. Here, we review several mechanisms of protection, such as heat shock proteins, opioids, collateral blood flow, and nitric oxide induction, and the evidence indicating that magnetic fields may be used as a means of providing protection via each of these mechanisms. While there are few studies demonstrating direct protection with magnetic field therapies, there are a number of published reports indicating that electromagnetic fields may be able to influence some of the biochemical systems with protective applications.

A protective role of 27-kDa heat shock protein in glucocorticoid-evoked apoptotic cell death of hippocampal progenitor cells

Hippocampus is one of the most vulnerable tissues to glucocorticoid (GC). In the present study, we demonstrate that dexamethasone (DEX), a synthetic GC, induces apoptotic cell death in hippocampal progenitor HiB5 cells without any additional insult. Interestingly, expression of 27-kDa heat shock protein (HSP27) was markedly induced by DEX in time- and dose-dependent manners. This induction was dependent on the production of reactive oxygen species (ROS), suggesting that DEX-evoked oxidative damage to HiB5 cells is responsible for the HSP27 induction. To evaluate a possible role of HSP27, we generated two mutant HiB5 cell lines, in which expression of HSP27 was inhibited or enhanced by the over-expression of HSP27 cDNA with antisense or sense orientation (AS-HSP27 and S-HSP27, respectively). DEX-induced apoptotic cell population was significantly increased in AS-HSP27 HiB5 cells and evidently decreased in S-HSP27 cells. These results indicate that HSP27 protects hippocampal progenitor cells from GC-induced apoptotic cell death.

Janus kinase-2 signaling mediates apoptosis in rat cardiomyocytes

We tested the hypothesis that activation Jak2, which is prominently involved in the up-regulation of the renin-angiotensin system (RAS), constitutes a focal point in relaying signals triggered by a Angiotensin II (Ang II) and hypoxia/reoxygenation separately to cause an enhanced susceptibility of cardiac myocyte to apoptotic cell death. Ang II-treated adult cardiomyocytes in culture exhibited an increased level of apoptosis that accompanied activation of pro-apoptotic as well as anti-apoptotic signaling pathways. We observed increased phosphorylation of Jak2 kinase, Stat1, JNK, with increased expression of Bax protein, followed by an increase in caspase-1 and caspase-3 activity. Activation of these pro-apoptotic pathways was blocked by the Jak2 pharmacological inhibitor, Tyrphostin AG490. We also observed an increase in phosphorylation of cardioprotective pathway components, namely S6 ribosomal protein, and heat shock protein 27 (HSP27). Likewise, the oxidative stress, via the hypoxia/reoxygenation treatment of rat adult cardiomyocytes, produced apoptosis that was dependent upon activation of Jak2. The apoptotic response was not only reduced by Losartan, an inverse agonist of the AT1, receptor, but by treatment with AG490 as well. Taken together, these observations provide clear evidence in favor of Jak2 signaling as mediator of the apoptotic response in cardiomyocytes. However, there was a concomitant induction of cytoprotective signaling that presumably provides a negative feed-back to the deleterious effects of the agonist.

The temporal relationship between p38 MAPK and HSP27 activation in ischaemic and pharmacological preconditioning

An ischaemic preconditioning protocol and subsequent sustained ischaemia were characterized by activation and attenuation of p38 MAPK phosphorylation, respectively. However, the significance of events downstream of p38 MAPK needs investigation. Therefore the temporal relationship between phosphorylation of p38 MAPK and its downstream substrate HSP27 was studied during either an ischaemic or beta-adrenergic preconditioning protocol and during sustained ischaemia. Isolated rat hearts were preconditioned (with or without a p38 MAPK inhibitor, SB203580) with 1 x 5 min or 3 x 5 min global ischaemia or 5 min beta-adrenergic stimulation (10(-7) M isoproterenol), followed by 25 min sustained ischaemia and 30 min reperfusion. Hearts were freeze-clamped at different time intervals and fractionated to determine p38 MAPK and HSP27 phosphorylation, via Western blotting. Significant phosphorylation of cytosolic p38 MAPK and membrane (myo-fibrillar) HSP27 occurred at the end of the first preconditioning episode. However, p38 MAPK phosphorylation disappeared during subsequent preconditioning episodes, while HSP27 phosphorylation was maintained for the duration of the protocol. Similar changes in p38 MAPK and HSP27 occurred with 5 min beta-adrenergic preconditioning. After 25 min ischaemia, significant phosphorylation of cytosolic and membrane HSP27 was observed, while p38 MAPK phosphorylation was attenuated in ischaemic and beta-adrenergic preconditioned compared to non-preconditioned hearts. SB203580-induced abolishment of p38 MAPK and HSP27 phosphorylation during the triggering phase of both preconditioning protocols reversed the changes in these parameters seen after sustained ischaemia. The results suggest that p38 MAPK activation triggers HSP27 phosphorylation during both the preconditioning protocols and during sustained ischaemia. Protection of preconditioned hearts during sustained ischaemia was characterized by phosphorylation of both cytosolic and myofibrillar HSP27.

Heat shock protein 70 or heat shock protein 27 overexpressed in human endothelial cells during posthypoxic reoxygenation can protect from delayed apoptosis

Overexpression of heat shock protein (Hsp) 70 and Hsp27 in vivo was proclaimed as a potential tool in therapy of ischemia-reperfusion injury. However, it was so far not known whether these Hsps can beneficially act when increased in cells just at the stage of postischemic reperfusion. This issue was examined in a model of ischemia-reperfusion stress when cultures of endothelial cells (EC) from human umbilical vein were infected with virus-based vectors expressing Hsp70 or Hsp27, or Hsp56, or green fluorescent protein (GFP) and exposed to 20 hours of hypoxia followed by reoxygenation. The infection was performed either 10 hours before hypoxia or immediately after hypoxia, or at different time points of reoxygenation. Only low cell death was detected during hypoxia, but later, up to 40% of the treated cells died via caspase-dependent apoptosis between 6 and 12 hours of reoxygenation. The percentage of apoptotic cells was 1.6- to 3-fold greater in Hsp56- and GFP-infected EC than in Hsp70- or Hsp27-infected EC. The last 2 groups exhibited a lesser extent of procaspase-9 and procaspase-3 activation within 6-9 hours of reoxygenation. The cytoprotective effects of overexpressed Hsp70 and Hsp27 were observed not only in the case of infection before hypoxia but also when EC were infected at the start of reoxygenation or 1-2 hours later. An increase in the Hsp70 and Hsp27 levels in infected EC correlated well with their resistance to apoptosis under reoxygenation. These findings suggest that overexpression of Hsp70 or Hsp27, if it occurs in the involved cells at the early stage of postischemic reperfusion, can still be cytoprotective.

Heat shock protein 27 protects the heart against myocardial infarction

Heat shock proteins (hsp) represent a group of chaperones which protects the cells against a diversity of stresses. It has been demonstrated that hsp27 is constitutively present in cells where it plays an important role in different cytoprotective processes which ultimately inhibit cell death. We investigated the response of the isolated perfused mouse heart over expressing hsp27 to the ischaemia/reperfusion injury using infarct size as an end point. Our results show for the first time that mice over expressing hsp27 (verified by Western blotting analysis) were found to be protected from lethal ischaemia/reperfusion injury compared to their negative littermates.

Apoptotic adaptations from exercise training in skeletal and cardiac muscles

The effect of exercise on apoptosis in postmitotic tissues is not known. In this study, we investigated the effect of regular moderate physical activity (i.e., exercise training) on the extent of apoptosis in rat skeletal and cardiac muscles. Adult Sprague Dawley rats were trained (TR) 5 days weekly for 8 wk on treadmill. Sedentary rats served as controls (CON). An ELISA was used to detect mono- and oligonucleosome fragmentation as an indicator of apoptosis. Bcl-2, Bax, Apaf-1, AIF, cleaved PARP, cleaved caspase-3, cleaved/active caspase-9, heat shock protein (HSP)70, Cu/Zn-SOD, and Mn-SOD protein levels were determined by Western analyses. Bcl-2 and Bax transcript contents were estimated by RT-PCR. A spectrofluorometric assay was used to determine caspase-3 activity. DNA fragmentation in ventricles of the TR group decreased by 15% whereas that in soleus of the TR group tended to decrease (P=0.058) when compared with CON group. Protein contents of Bcl-2, HSP70, and Mn-SOD increased in both soleus and ventricle muscles of TR animals when compared with CON animals. Apaf-1 protein content in the soleus of TR animals was lower than that of CON animals. Bcl-2 mRNA levels increased in both ventricle and soleus muscles of TR animals, and Bax mRNA levels decreased in the soleus of TR animals when compared with CON animals. Furthermore, HSP70 protein content was negatively correlated to Bax mRNA content and was positively correlated to Bcl-2 protein and mRNA contents. Mn-SOD protein content was negatively correlated to the apoptotic index, and caspase-3 activity and was positively correlated to Bcl-2 transcript content and HSP70 protein content. These data suggest that exercise training attenuates the extent of apoptosis in cardiac and skeletal muscles.

The protective effect of moderate hypothermia during intestinal ischemia-reperfusion is associated with modification of hepatic transcription factor activation

BACKGROUND/PURPOSE

Moderate hypothermia throughout intestinal ischemia-reperfusion (IIR) injury reduces multiple organ dysfunction. Heat shock proteins (HSPs) have been shown to be protective against ischemia-reperfusion injury, and STAT (Signal Transducers and Activators of Transcription) proteins are pivotal determinants of the cellular response to reperfusion injury. The aim of this study is to investigate the mechanism of hypothermic protection during IIR.

METHODS

Adult rats underwent intestinal ischemia-reperfusion (IIR), 60-minute ischemia and 60-minute reperfusion, or sham (120 minutes) at either normothermia or moderate hypothermia. Four groups of animals were studied: (1) normothermic sham (NS), (2) normothermic IIR (NIIR), (3) hypothermic sham (HS), and (4) hypothermic IIR (HIIR). Western blotting measured heat shock protein expression, phosphorylated (p-) and total (T-) hepatic STAT-1 and STAT-3.

RESULTS

There were no differences in expression of HSPs 27, 47, 60, i70, c70, or 90 between any of the experimental groups. NIIR caused a significant increase in p-STAT-1 compared with normothermic sham (P <.05) and a highly significant increase in p-STAT-3 (P <.001), both these increases were completely abolished by moderate hypothermia (P <.01 v NIIR.)

CONCLUSIONS

The protective effect of moderate hypothermia on liver is not mediated by HSP expression at this time-point. Hypothermia may act by decreasing hepatic STAT activation, supporting the potential therapeutic role of moderate hypothermia. Modulation of STAT activation may also provide novel therapeutic targets.

HSP27 but not HSP70 has a potent protective effect against alpha-synuclein-induced cell death in mammalian neuronal cells

alpha-Synuclein is a neuronally expressed protein which is mutated in familial Parkinson's disease. We have previously shown that disease-associated mutants of alpha-synuclein cause enhanced neuronal cell death in response to a variety of stimuli, whereas wild-type alpha-synuclein has a protective effect against some stimuli, whilst enhancing the death response to others. We demonstrate, for the first time, that over-expression of the heat shock protein HSP27 has a potent protective anti-apoptotic effect against the damaging effects of wild-type and particularly of mutant alpha-synuclein. In contrast, HSP70 has some protective effect against the damaging effect of the wild-type protein, but has no effect against the mutant proteins, whilst HSP56 has no protective effect in this system. Our results indicate that disease-associated mutants of alpha-synuclein enhance its death-inducing properties and lead to increased apoptosis, which can be mitigated by either the use of specific caspase inhibitors or HSP27 over-expression. This potent protective effect of HSP27 against the mutant and wild-type proteins may be of potential therapeutic importance.

Heat shock proteins can protect aged human and rodent cells from different stressful stimuli

Heat shock proteins (hsps) are induced by stressful stimuli and have been shown to protect cells and organs from such stresses both in vitro and in vivo. Because of this, mildly stressful stimuli, sufficient to induce hsp over-expression can protect against a subsequent more severe stress. In cells from aged individuals, however, no hsp induction is observed upon exposure to stress and no protective effect of a mild stress is observed. Here, we show that bypassing the block to hsp induction by artificially over-expressing hsps, can produce a protective effect against a variety of damaging stimuli in cells from aged rats or aged humans, indicating that hsps can have a protective effect in aged cells, provided successful over-expression can be achieved. Hence, hsps over-expression could be of therapeutic benefit in aged individuals if procedures to over-express the hsps can be developed either by devising non-stressful procedures to induce endogenous hsp over-expression or by developing vectors able to efficiently deliver exogenous hsps.

Ageing–apoptosis relation in murine spleen

Relatively few studies have been published with regard to modification of apoptosis in normal tissues as a function of ageing. The majority of these studies demonstrated an increase in programmed cell death (PCD) with age. However, opposite results, namely loss of apoptotic control with age, have also been reported. In the present study, we examined proliferation and apoptotic cell death in spleens of C57/BL mice of different ages. A tendency towards decrease in cell proliferative capacity was seen with age. By contrast, apoptosis was increased in spleens from aged animals. Moreover, the proliferative cell/apoptotic cell ratio decreased in function of age. Ladder type DNA degradation was much more pronounced in DNA derived from splenocytes of old mice. These results were supported by a decrease of Bcl-2 and an increase in Fas receptor expression as well as by increased activation of caspases 8, 3 and 9 in splenocytes from aged animals. In addition, cell surface molecular markers recognizable by macrophages in apoptotic cells, namely decreased sialic acid concomitant with increased unmasking of galactose residues, were more pronounced on splenocytes from old mice than on those from young animals. In addition to the experimental evidence which supports a role of apoptotic cell death in ageing, a series of theoretical reasoning, which could also favor this possibility, are discussed.

Regulation of necrosis of H9c2 myogenic cells upon transient energy deprivation. Rapid deenergization of mitochondria precedes necrosis and is controlled by reactive oxygen species, stress kinase JNK, HSP72 and ARC

Subjecting myogenic H9c2 cells to transient energy deprivation leads to a caspase-independent death with typical features of necrosis. Here we show that the rupture of cytoplasmic membrane, the terminal event in necrosis, is shortly preceded by rapid depolarization of mitochondrial membranes. The rapid deenergization of mitochondria critically depended upon prior generation of reactive oxygen species (ROS) during ATP depletion stage. Accordingly, expression of catalase prevented mitochondrial depolarization and averted subsequent necrosis. Interestingly, trifluoperazine, a compound that protects cells from ischemic insults, prevented necrosis of H9c2 cells through inhibition of ROS production. Other factors that regulated the mitochondrial membrane depolarization and subsequent loss of plasma membrane integrity include a stress kinase JNK activated at early steps of recovery from ATP depletion, as well as an apoptotic inhibitory protein ARC. Accordingly, inhibition of JNK or overexpression of ARC prevented mitochondrial depolarization and rescued H9c2 cells from necrosis. ROS and JNK affected mitochondrial deenergization and necrosis independently of each other since inhibition of ROS production did not prevent activation of JNK, whereas inhibition of JNK did not suppress ROS accumulation. Therefore, JNK activation and ROS production represent two independent pathways that control mitochondrial depolarization and subsequent necrosis of cells subjected to transient energy deprivation. Overexpression of ARC, although preventing mitochondrial depolarization, did not affect either JNK activation or production of ROS. The major heat shock protein Hsp72 inhibited JNK-related steps of necrotic pathway but did not affect ROS accumulation. Interestingly, mitochondrial depolarization and subsequent necrosis can be suppressed by an Hsp72 mutant Hsp72DeltaEEVD, which lacks chaperone function but can efficiently suppress JNK activation. Thus, Hsp72 is directly implicated in a signaling pathway, which leads to necrotic death.

Facets of heat shock protein 70 show immunotherapeutic potential

Amongst the families of intracellular molecules that chaperone and assist with the trafficking of other proteins, notably during conditions of cellular stress, heat shock protein (hsp) 70 is one of the most studied. Although its name suggests that expression is exclusively induced during cellular hyperthermia, members of the hsp70 family of proteins can be constitutively expressed and/or induced by a range of other cellular insults. The ubiquitous presence of hsp70 in eukaryotic and prokaryotic cells, combined with its high degree of sequence homology and intrinsic immunogenicity, have prompted the suggestion that inappropriate immune reactivity to hsp70 might lead to pro-inflammatory responses and the development of autoimmune disease. Indeed, hsp70 has been shown to be a potent activator of innate immunity and aberrant expression of hsp70 in certain organs promotes immunopathology. However, studies also suggest that hsp70 might have immunotherapeutic potential, as hsp70 purified from malignant and virally infected cells can transfer and deliver antigenic peptides to antigen-presenting cells to elicit peptide-specific immunity and, in contrast to its reported pro-inflammatory effects, the administration of recombinant hsp70 can attenuate experimental autoimmune disease. This review focuses on the immunoregulatory capacity of hsp70 and its potential therapeutic value.