Atrial natriuretic peptide prevents the mitochondrial permeability transition pore opening by inactivating glycogen synthase kinase 3β via PKG and PI3K in cardiac H9c2 cells

The purpose of this study was to test if atrial natriuretic peptide (ANP) can prevent the mitochondrial permeability transition pore (mPTP) opening by inactivating glycogen synthase kinase 3 beta (GSK-3 beta). ANP prevented loss of mitochondrial membrane potential (Delta Psi(m)) caused by H2O2 in a dose-dependent manner. Similarly, cyclosporin A, an inhibitor of the mPTP opening, could also preserve Delta Psi(m) ANP increased GSK-3 beta phosphorylation at Ser(9), pointing to that ANP inactivates GSK-3 beta. ANP could not prevent the loss of Delta Psi(m) in cells transfected with the constitutively active GSK-3 beta (GSK-3 beta-S9A) mutant. The effects of ANP on GSK-3 beta phosphorylation and Delta Psi(m),, were reversed by the selective PKG inhibitor KT5823 [2,3,9,10,11,12-hexahydro-10R-methoxy-2,9-dimethyl-1-oxo-9S,12R-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid, methyl ester]. In support, PKG markedly enhanced GSK-3 beta phosphorylation. ANP-induced GSK-3 beta phosphorylation was also abolished by the PI3K inhibitor LY294002 [2-(4-morpholinyl-4H-1-benzopyran-4-one hydrochloride)] and ANP could not prevent H2O2-induced loss of Delta Psi(m), in the presence of LY294002. These data suggest that ANP modulates the mPTP opening by inactivating GSK-3 beta through PKG and PI3K. GSK-3 beta is a common downstream target of PKG and PI3K. Prevention of the mPTP opening may underlie the mechanism for ANP's protection against reperfusion injury. (C) 2012 Elsevier B.V. All rights reserved.