Abstract
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 (CaMKIIδ) activity after treatment with the NO donor S-nitrosoglutathione (GSNO). We demonstrate that exposure to NO after Ca2+/CaM binding to CaMKIIδ results in autonomous kinase activation, which is abolished by mutation of the Cys-290 site. However, exposure of CaMKIIδ 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/CaMKIIδ binding and CaMKIIδ-dependent ryanodine receptor activation in adult cardiac myocytes. We conclude that NO can play a dual role in regulating cardiac CaMKIIδ activity.
Background: CaMKIIδ and NO can modulate cardiac signaling/pathology.
Results: NO treatment after calcium/calmodulin binding prolongs CaMKIIδ activation, whereas NO pretreatment inhibits CaMKIIδ activation, effects mediated by Cys-290 and Cys-273, respectively.
Conclusion:S-nitrosylation has a dual role in modulating CaMKIIδ in the heart.
Significance: Dual regulation by NO is a new pathway by which CaMKII can modulate cardiac function.