Role of HSP70 in cellular thermotolerance

Background and Objective Thermal pretreatment has been shown to condition tissue to a more severe secondary heat stress. In this research we examined the particular contribution of heat shock protein 70 (HSP70) in thermal preconditioning. Study Design/Materials and Methods For optimization of preshock exposures, a bioluminescent Hsp70‐luciferase reporter system in NIH3T3 cells tracked the activation of the Hsp70 gene. Cells in 96‐well plates were pretreated in a 43°C water bath for 30 minutes, followed 4 hours later with a severe heat shock at 45°C for 50 minutes. Bioluminescence was measured at 2, 4, 6, 8, and 10 hours after preshock only (PS) and at 4 hours after preshock with heatshock (PS+HS). Viability was assessed 48 hours later with a fluorescent viability dye. Preshock induced thermotolerance was then evaluated in hsp70‐containing Murine Embryo Fibroblast (+/+) cells and Hsp70‐deficient MEF cells (−/−) through an Arrhenius damage model across varying temperatures (44.5–46°C). Results A time gap of 4 hours between preconditioning and the thermal insult was shown to be the most effective for thermotolerance with statistical confidence of P