Molecular chaperones, including the heat-shock proteins (Hsps), are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Hsps have received the most attention in model organisms undergoing experimental stress in the laboratory, and the function of Hsps at the molecular and cellular level is becoming well understood in this context. A complementary focus is now emerging on the Hsps of both model and nonmodel organisms undergoing stress in nature, on the roles of Hsps in the stress physiology of whole multicellular eukaryotes and the tissues and organs they comprise, and on the ecological and evolutionary correlates of variation in Hsps and the genes that encode them. This focus discloses that (a) expression of Hsps can occur in nature, (b) all species have hsp genes but they vary in the patterns of their expression, (c) Hsp expression can be correlated with resistance to stress, and (d) species' thresholds for Hsp expression are correlated with levels of stress that they naturally undergo. These conclusions are now well established and may require little additional confirmation; many significant questions remain unanswered concerning both the mechanisms of Hsp-mediated stress tolerance at the organismal level and the evolutionary mechanisms that have diversified the hsp genes.

/pdf/heat-shock-proteins-molecular-chaperones-and-the-stress-p3ghklf1z7.pdf

Heat-shock proteins, molecular chaperones, and the stress response: evolutionary and ecological physiology

The cellular stress response protects organisms from damage resulting from exposure to a wide variety of stressors, including elevated temperatures, ultraviolet (UV) light, trace metals, and xenobiotics. The stress response entails the rapid synthesis of a suite of proteins referred to as stress proteins, or heat-shock proteins, upon exposure to adverse environmental conditions. These proteins are highly conserved and have been found in organisms as diverse as bacteria, molluscs, and humans. In this review, we discuss the stress response in aquatic organisms from an environmental perspective. Our current understanding of the cellular functions of stress proteins is examined within the context of their role in repair and protection from environmentally induced damage, acquired tolerance, and environmental adaptation. The tissue specificity of the response and its significance relative to target organ toxicity also are addressed. In addition, the usefulness of using the stress response as a diagnostic in environmental toxicology is evaluated. From the studies discussed in this review, it is apparent that stress proteins are involved in organismal adaptation to both natural and anthropogenic environmental stress, and that further research using this focus will make important contributions to both environmental physiology and ecotoxicology.

Stress Proteins in Aquatic Organisms: An Environmental Perspective

http://www.jbc.org/content/268/2/1046.full.pdf

Structural and functional similarities of bovine alpha-crystallin and mouse small heat-shock protein. A family of chaperones.

Inhibition of HIV-1 integrase by flavones, caffeic acid phenethyl ester (CAPE) and related compounds

The role of fever in the infected host.

Effect of pH on quercetin-induced suppression of heat shock gene expression and thermotolerance development in HT-29 cells.

Since both heat and sodium arsenite induce thermotolerance, we investigated the differences in synthesis and redistribution of stress proteins induced by these agents in Chinese hamster ovary cells Five major heat shock proteins (HSPs; Mr 110, 87, 70, 28, and 85 kDa) were preferentially synthesized after heat for 10 min at 455 degrees C, whereas four major HSPs (Mr 110, 87, 70, and 28 kDa) and one stress protein (333 kDa) were preferentially synthesized after treatment with 100 microM sodium arsenite (ARS) for 1 hr Two HSP families (HSP70a,b,c, and HSP28a,b,c) preferentially relocalized in the nucleus after heat shock In contrast, only HSP70b redistributed into the nucleus after ARS treatment Furthermore, the kinetics of synthesis of each member of HSP70 and HSP28 families and their redistribution were different after these treatments The maximum rates of synthesis of HSP70 and HSP28 families, except HSP28c, were 6-9 hr after heat shock, whereas those of HSP70b and HSP28b,c were 0-2 hr after ARS treatment In addition, the maximum rates of redistribution of HSP70 and HSP28 families occurred 3-6 hr after heat shock, whereas that of HSP70b occurred immediately after ARS treatment The degree of redistribution of HSP70b after ARS treatment was significantly less than that after heat treatment These results suggest that heat treatment but not sodium arsenite treatment stimulates the entry of HSP70 and HSP28 families into the nucleus

Differences in preferential synthesis and redistribution of HSP70 and HSP28 families by heat or sodium arsenite in Chinese hamster ovary cells.

We investigated the correlation between the development of acute thermotolerance and the phosphorylation, synthesis, and expression of the HSP28 family in murine L929 cells. Following heating at 43 degrees C for 30 min, thermotolerance developed rapidly in exponential-phase cells and reached its maximum 4-9 h after heat shock. Maximal thermal resistance was maintained for 24 h and then gradually decayed. However, heat-induced phosphorylation of HSP28 was not detected. Furthermore, HSP28 synthesis during incubation at 37 degrees C for 12 h following heat shock was not detected by [3H]-leucine labeling followed by two-dimensional polyacrylamide gel electrophoresis. In addition, Northern blots failed to demonstrate expression of the HSP28 gene. Unlike HSP28, the expression of constitutive and inducible HSP70 genes, along with the synthesis of their proteins, was observed during incubation at 37 degrees C after heat shock. These results demonstrate that HSP28 synthesis and its phosphorylation are not required to develop acute thermotolerance in L929 cells.

Development of acute thermotolerance in 1929 cells: Lack of HSP28 synthesis and phosphorylation

In this study, we investigated the mechanism of synergistic effects of cytokine and hyperthermia on cytotoxicity in HT-29. When cells were heated at 42 degrees C in the presence of recombinant human tumor necrosis factor (rhTNF-alpha), recombinant interferon-gamma (rhIFN-gamma), or in a combination of both, a synergistic increase in the cytotoxic effects of the respective drugs was observed. We hypothesized that alteration of cytokine or heat-induced polypeptides synthesis was responsible for a synergistic interaction between heat and cytokine. Five heat shock proteins (HSPs, M(r) 110,000, 100,000, 90,000, 70,000, and 28,000) were preferentially synthesized during chronic heating at 42 degrees C. In contrast, the synthesis of two proteins (M(r) 60,000 and 29,000) was induced by treatment with rhIFN-gamma (1,000 U/ml). Although the combination of chronic hyperthermia (42 degrees C) with TNF-alpha, IFN-gamma, or TNF-alpha + IFN-gamma increased cytotoxicity, alteration/induction of polypeptides was not correlated with the synergistical cytotoxic effects of cytokine and heat. Thus, the synergistic effects of cytokine and hyperthermia are not mediated through an induction of polypeptides.

Synergistic effects of cytokine and hyperthermia on cytotoxicity in HT‐29 cells are not mediated by alteration of induced protein levels

Three heat-resistant mutant cell lines (78-1, 78-2, 78-3) were previously selected from Chinese hamster ovary cells. In this study, we investigated whether the differences in intrinsic thermal sensitivity result from alteration of stress protein levels or cellular structural changes. Although there was no significant difference in the levels of stress proteins, i.e., constitutive HSP70 in wild type and three heat-resistant mutant strains, there were marked differences in the amounts of vimentin among the cell lines. Two-dimensional gel electrophoresis and Western blot showed a 2.3–2.9-fold increase in the level of vimentin in the mutant cells under normal growth conditions. Northern blot also revealed higher amounts of vimentin mRNA in the mutant cells. Electron microscopy and immunofluorescence suggest that increased amounts of the vimentin-containing intermediate filaments are correlated with the heat-resistant phenotypes. © 1992 Wiley-Liss, Inc.

Heat‐resistant variants of the Chinese hamster ovary cell: Alteration of cellular structure and expression of vimentin

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