Protein S‐nitrosylation regulates Ca2+ handling and myofilament Ca2+ sensitivity in beta‐adrenergic signaling

Abstract

ObjectiveTo assess the impact of increased rotein denitrosylation on beta‐adrenergic receptor (b‐AR)‐dependent signaling and to evaluate effects of augmented denitrosylation during nitrosative stress in cardiomyocytes.Methods and ResultsWe studied cardiomyocytes isolated from wild‐type (WT) and cardiomyocytespecific S‐nitrosoglutathione reductase (GSNOR) overexpressing transgenic (GSNOR‐CMTg) mice. Stimulation of the b‐AR with isoproterenol (ISO)increased sarcomere shortening in both genotypes, while systolic Ca2+ release and sarcoplasmic Ca2+ load only increased in WT. This effect was correlated with increased myofilament Ca2+ sensitivity in ISO‐treated GSNOR‐CMTg cells. Both genotypes showed similar increases in phosphorylation of phospholamban (PLN) and troponin I after b‐AR stimulation while S‐nitrosylation of PLN and troponin C was only increased in WT. Exposure of ISO‐stimulated WT cells to S‐nitrosocysteine severely depressed contractility and systolic Ca2+ release, associated with sarcoplasmic Ca2+ leak and increased ryanodine receptor (RyR2) S‐nitrosylation. GSNOR overexpression prevented RyR2 S‐nitrosylation and preserved contractile function during nitrosative stress.ConclusionThese results suggest that b‐AR‐induced S‐nitrosylation of excitation‐contraction coupling proteins is required for b‐AR‐induced augmentation of cardiomyocyte function.