Long-term Heat Exposure Prevents Hypoxia-Induced Apoptosis in Mouse Fibroblast Cells
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Long-term continuous exposure to high ambient temperatures induces complete heat acclimation in humans and animals. However, to date, the effects of long-term exposure to heat stress on cells have not been fully evaluated. In this study, we investigated an adaptive physiological process induced in culture cells by continuous exposure to mild heat stress for 60 days. The results of this investigation provide evidence that after long-term heat acclimation in cells, (1) heat shock protein levels are increased, (2) hypoxia inducible factor-1α (HIF-1α) expression is upregulated, and (3) heat shock-induced and hypoxia-induced apoptoses are attenuated. These results suggest that the hypoxia response pathway is an intrinsic part of the heat acclimation repertoire and that the HIF-1 pathway following long-term heat acclimation induces cells with cross tolerance against hypoxia.
KeywordsHeat acclimation Heat shock proteins HIF-1α Heat tolerance Cross tolerance
This work was supported in part by Grants-in-Aid for Science and Culture (22249041 and 23659503 to H. U., 24659105 to N. S., and 23591531 to S. K.) from the Ministry of Education, Culture, Sports, Science and Technology of Japan, and Kanazawa Medical University Research Foundation (C2010-1 to H. U.). The founders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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