Reduction of cytochrome c by fragments of heat shock protein 70

Simpkins, Cuthbert O.; Fogarty, Kenneth W.; Nhamburo, Patson T.

doi:10.1016/0024-3205(93)90110-o

Cited by 10 publications

(10 citation statements)

References 9 publications

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“…Several authors (Simpkins et al 1993;Samali and Orrenius 1998) have postulated an involvement of Hsp70 in preventing electron leak between complexes III and IV by binding and consequently reducing cytochrome c loss from mitochondrial membranes, thereby averting an increase in state IV respiration rates and induction of cytochrome c-linked apoptosis. This possibility is consistent with our observation of prevention of increases in state IV respiration in stressed astrocytes.…”

Section: Discussionmentioning

confidence: 99%

Overexpression of inducible heat shock protein 70 and its mutants in astrocytes is associated with maintenance of mitochondrial physiology during glucose deprivation stress

Ouyang

Sun

et al. 2006

Cell Stress Chaper

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Wild-type inducible Hsp70 (WT) and 2 folding deficient mutants protect the brain against focal cerebral ischemia in vivo and brain cells from oxygen-glucose deprivation (OGD) in vitro, but the protective mechanisms remain unclear. Mitochondria are central to both normal physiological function and the regulation of cell death. We tested the effect of overexpressing Hsp70 and 2 mutants, Hsp70-K71 E, an adenosine triphosphatase (ATPase)-deficient point mutant, and Hsp70-381-640, a deletion mutant lacking the ATPase domain on mitochondrial physiology under glucose deprivation (GD) stress in primary cultured astrocytes. Mitochondrial membrane potential was assessed using a potentiometric fluorescent dye tetramethylrhodamine ethyl ester (TMRE). By 5 hours of GD, the mitochondria in the LXSN control transfected astrocytes had markedly reduced membrane potential. However, in the Hsp70-WT, -K71E, and -381-640 groups, there was no apparent change in TMRE signal during 5 hours of GD. Oxygen consumption was measured to assess oxidative respiration. Overexpression of Hsp70-K71 E and -381-640 prevented the decrease in state III respiration observed at 5 hours, and all 3 prevented the increase in state IV respiration found in LXSN controls after 5 hours of GD. Reactive oxygen species (ROS) production was assessed with hydroethidine. Hsp70 and its mutants all significantly reduced the increases in ROS accumulation during 5 hours of GD. The results demonstrate that the protective effect of the carboxyl-terminal half of Hsp70 and of the full-length molecule is associated with better maintained mitochondrial membrane potential, better maintained state IV respiration, and reduced ROS generation during GD.

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Section: Discussionmentioning

confidence: 99%

Overexpression of inducible heat shock protein 70 and its mutants in astrocytes is associated with maintenance of mitochondrial physiology during glucose deprivation stress

Ouyang

Sun

et al. 2006

Cell Stress Chaper

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“…On one hand, association of hsp with antigenic peptides might serve to shield the antigens from their ultimate degradation, (i) by maintaining or favouring unfolding of antigen, so leading to exposure of previously inaccessible proteolytic sites, or (ii) by reducing antigen, a step which has been described to be suffi-cient to induce T-cell proliferation. 52,53 Indeed, reductive activity of hsp 70 has been evoked by Simpkins et al 54 according to the presence in its N-terminal region of a cysteine-containing hydrophobic sequence (YSCVGVF). On the other hand, we could not exclude the possibility that, depending upon which portion of the antigenic molecules was bound by the hsp, different T-cell determinants on the molecules would be preferentially generated and presented in association with MHC molecules.…”

Section: Discussionmentioning

confidence: 99%

Increased proteolysis of diphtheria toxin by human monocytes after heat shock: a subsidiary role for heat‐shock protein 70 in antigen processing

Polla¹,

Gabert²,

Peyrusse

et al. 2006

Immunology

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Summary The expression of heat‐shock proteins (hsp) increases after exposure to various stresses including elevated temperatures, oxidative injury, infection and inflammation. As molecular chaperones, hsp have been shown to participate in antigen processing and presentation, in part through increasing the stability and expression of major histocompatibility complex molecules. Heat shock selectively increases human T‐cell responses to processed antigen, but does not affect T‐cell proliferation induced by non‐processed antigens. Here, we have analysed the mechanisms by which stress such as heat shock, and the ensuing hsp over‐expression affect the processing of diphtheria toxin (DT) in peripheral blood monocytes. We found that heat shock increased DT proteolysis in endosomes and lysosomes while the activities of the cathepsins B and D, classically involved in DT proteolysis, were decreased. These effects correlated with the heat‐shock‐mediated increase in hsp 70 expression observed in endosomes and lysosomes. Actinomycin D or blocking anti‐hsp 70 antibodies abolished the heat‐shock‐mediated increase in DT proteolysis. These data indicate that the increased expression of hsp 70 constitutes a subsidiary mechanism that facilitates antigen proteolysis in stressed cells. Confirming these data, presentation by formaldehyde‐fixed cells of DT proteolysates that were obtained with endosomes and lysosomes from heat‐shocked peripheral blood monocytes showed higher stimulation of T cells than those generated with endosomes and lysosomes from control peripheral blood monocytes.

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“…Previous reviews have also postulated an involvement of Hsp 72 in preventing electron leak between complexes III and IV by binding and reducing cytochrome c loss from mitochondrial membranes (Figure 7), thereby averting an increase in state 4 respiration rates and induction of cytochrome c linked apoptosis. 40,41 Certainly, Hsp 60/10 over-expression and stress-induced chaperonin-like molecules such as Tcm62p have been shown to markedly protect both nuclear and mitochondrial encoded proteins including primary dehydrogenases from ischemia damage. 13,42 However, protection of mitochondrial proteins from oxidative stress need not necessarily stem exclusively from a chaperoning action of Hsps.…”

Section: Discussionmentioning

confidence: 99%

Heat Stress Contributes to the Enhancement of Cardiac Mitochondrial Complex Activity

Sammut

Jayakumar

Latif

et al. 2001

The American Journal of Pathology

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Hyperthermic stress is known to protect against myocardial dysfunction after ischemia-reperfusion injury. It is unclear however, what energetic mechanisms are affected by the molecular adaptation to heat stress. We hypothesized that mild hyperthermic stress can increase mitochondrial respiratory enzyme activity, affording protection to mitochondrial energetics during prolonged cardiac preservation for transplantation. Rat hearts were excised after heat-stress or sham treatment and subjected to cold cardioplegic arrest and ischemia followed by reperfusion in an ex vivo perfusion system. Cardiac function, mitochondrial respiratory, and complex activities were assessed before and after ischemia. Heat shock protein (Hsp 32, 60, and 72) expression was increased in heat-stressed hearts. This was associated with increased mitochondrial complex activities in heat-stress versus sham-treated groups for complex I-V. During reperfusion, higher complex activities and respiratory control ratios were observed in heat-stressed versus sham-treated groups. Recovery of ventricular function was improved in heat-stressed hearts. Furthermore, mitochondria in reperfused heat-stressed myocardium exhibited intact membranes with packed, parallel, lamellar cristae, whereas in sham-treated myocardium, mitochondria were severely disrupted. This study provides the first evidence of heat-stress-mediated enhancement of mitochondrial energetic capacity. This is associated with increased tolerance to ischemia-reperfusion injury. Protection by heat stress against myocardial dysfunction may be partially due to enhancement of mitochondrial energetics.

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Reduction of cytochrome c by fragments of heat shock protein 70

Cited by 10 publications

References 9 publications

Overexpression of inducible heat shock protein 70 and its mutants in astrocytes is associated with maintenance of mitochondrial physiology during glucose deprivation stress

Overexpression of inducible heat shock protein 70 and its mutants in astrocytes is associated with maintenance of mitochondrial physiology during glucose deprivation stress

Increased proteolysis of diphtheria toxin by human monocytes after heat shock: a subsidiary role for heat‐shock protein 70 in antigen processing

Heat Stress Contributes to the Enhancement of Cardiac Mitochondrial Complex Activity

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