S-Nitrosylation Induces Both Autonomous Activation and Inhibition of Calcium/Calmodulin-dependent Protein Kinase II δ

NO is known to modulate calcium handling and cellular signaling in the myocardium, but key targets for NO in the heart remain unidentified. Recent reports have implied that NO can activate calcium/calmodulin (Ca2+/CaM)-dependent protein kinase II (CaMKII) in neurons and the heart. Here we use our novel sensor of CaMKII activation, Camui, to monitor changes in the conformation and activation of cardiac CaMKII (CaMKII delta) activity after treatment with the NO donor S-nitrosoglutathione (GSNO). We demonstrate that exposure to NO after Ca2+/CaM binding to CaMKII delta results in autonomous kinase activation, which is abolished by mutation of the Cys-290 site. However, exposure of CaMKII delta to GSNO prior to Ca2+/CaM exposure strongly suppresses kinase activation and conformational change by Ca2+/CaM. This NO-induced inhibition was ablated by mutation of the Cys-273 site. We found parallel effects of GSNO on CaM/CaMKII delta binding and CaMKII delta-dependent ryanodine receptor activation in adult cardiac myocytes. We conclude that NO can play a dual role in regulating cardiac CaMKII delta activity.