Roles of Zn~(2+) and mPTP in resveratrol-induced myocardial protection against endoplasmic reticulum stress

OBJECTIVE To investigate resveratrolinduced myocardial protection against endoplasmic reticulum stress(ERS), focusing on the roles of Zn~(2+)and the mitochondrial permeability transition pore(m PTP).METHODS H9c2 cardiac cell were cultured in DMEM,ERS was induced by 2-deoxy-d-glucose(2-DG), resveratrol/ZnCl_2 was pretreated for 20 min, the Zn~(2+)chelator TPEN and inhibitors were applied for 10 min before resveratrol/ZnCl_2. Cell viability/toxicity were measured by the MTT/LDH kit. The expressions of endoplasmic reticulum chaperone GRP 78/94, ERS-related apoptosis proteins CHOP, caspase 12, JNK and Protein Kinase pathway(ERK, PI3K/AKT, GSK-3β) phosphorylation were detected by Western blotting. The expressions of GRP 94 and JNK were detected by immunocytochemistry. The m PTP opening and intracellular Zn~(2+)concentration were evaluated by measuring the mitochondrial membrane potential(ΔΨm) with TMRE and Newport Green DCF fluorescent intensity by laser confocal microscopy. RESULTS 2-DG significantly enhanced cell toxicity and decreased viability.Resveratrol reversed the action of 2-DG. Resveratrol markedly inhibited GRP 78/94, CHOP, caspase 12, JNK expressions, which were blocked by TPEN, ERK inhibitor PD98059, GSK-3β inhibitor SB216763 and ERK/GSK-3β siRNA. In addition, resveratrol significantly increased phosphorylated ERK and GSK-3β. AKT inhibitor LY294002 and AKT siRNA were not altered the action of resveratrol. Resvetrol prevented 2-DG-induced m PTP opening and increased intracellular Zn~(2+)concentration, which were further abrogated by PD98059, SB216763 and ERK/GSK-3β siRNA. CONCLUSION These data suggest that resveratrol mobilize intracellular Zn~(2+)and protect cardiac cells against ERS by preventing the m PTP opening through the ERK/GSK-3β pathway. The important regulator of the PI3K/AKT signaling may not be involved in the action of resveratrol.