title: Heat shock preconditioning protects against ER stress-induced apoptosis through the regulation of the BH3-only protein BIM.
abstract: A mild heat shock (HS) preconditioning and acquisition of thermotolerance protects cells against a variety of cytotoxic agents that otherwise induce apoptosis. Here we tested whether there is a molecular link between HS preconditioning and endoplasmic reticulum (ER) stress-induced apoptosis. ER stress results from a loss of ER lumen homeostasis, culminating in an accumulation of unfolded/misfolded proteins in the ER and activation of unfolded protein response (UPR). Unresolved, ER stress leads to activation of BH3-only proteins, mitochondrial membrane permeabilization, caspase activation and apoptotic cell death. HS preconditioning (1 h at 42 °C) induced a rapid increase in HSPA1 (HSP70) levels which remained elevated for at least 48 h post-HS. HS preconditioning significantly reduced BAX, caspase activation and apoptosis in cell cultures treated with the ER stress-inducing agents thapsigargin (TG) and tunicamycin (TM). HS-mediated protection was found to be due to regulation of the BH3-only protein BIM. Further, overexpression of HSPA1 could not mimic the effect of HS on BIM expression, suggesting that other HS factors may play a role in inhibiting ER stress-induced apoptosis by regulating BIM.
authors.affiliation: Apoptosis Research Centre, NUI Galway, Ireland.
authors.forename: Donna
authors.initials: D
authors.lastname: Kennedy
authors.affiliation: Apoptosis Research Centre, NUI Galway, Ireland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Mnich
authors.affiliation: Apoptosis Research Centre, NUI Galway, Ireland.
authors.forename: Afshin
authors.initials: A
authors.lastname: Samali
keywords: Apoptosis; BCL-2 family; BIM; ER, endoplasmic reticulum; Endoplasmic reticulum stress; HS, heat shock; Heat shock; TG, thapsigargin; TM, tunicamycin; UPR, unfolded protein response; Unfolded protein response