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 3β (GSK-3β). ANP prevented loss of mitochondrial membrane potential (ΔΨm) caused by H2O2 in a dose-dependent manner. Similarly, cyclosporin A, an inhibitor of the mPTP opening, could also preserve ΔΨm. ANP increased GSK-3β phosphorylation at Ser9, pointing to that ANP inactivates GSK-3β. ANP could not prevent the loss of ΔΨm in cells transfected with the constitutively active GSK-3β (GSK-3β-S9A) mutant. The effects of ANP on GSK-3β phosphorylation and ΔΨm 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-3β phosphorylation. ANP-induced GSK-3β 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 ΔΨm in the presence of LY294002. These data suggest that ANP modulates the mPTP opening by inactivating GSK-3β through PKG and PI3K. GSK-3β 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.