S-nitrosylation of CaMKII cys273 suppresses CaMKII activation and translocation within cardiac myocytes.

Abstract

In this study, we demonstrate that the Cys273 site on Calcium/Calmodulin-Dependent Protein Kinase II δ (CaMKII δ) is critical for nitric oxide (NO)-induced suppression of CaMKIIδ activation and mobility in adult ventricular myocytes. CaMKII is also regulated by nitrosylation in a potential positive feedback mechanism via S-Nitrosylation of Cys290 on CaMKIIδ which promotes autonomous kinase activity, versus S-Nitrosylation of Cys273 that suppresses activation by Ca-CaM. This suggests a complex interaction between NO and CaMKII in cells with fluctuating [Ca] - like cardiomyocytes. The (patho)physiological role of CaMKII nitrosylation in the cardiomyocyte, however, remains poorly understood. Here, using mutant CaMKIIδ variants of our FRET-based CaMKII activity sensor ‘Camui’ and GFP-tagged constructs of CaMKIIδ lacking the Cys273 S-nitrosylation site (CaMKIIδ-C273S), we assessed CaMKII activation and mobility after exposure to the NO donor S-nitrosoglutathione (GSNO) and Ca. We determined this by measuring Camui fluorescence lifetime values (FLIM) and assessing changes in CaMKII-GFP mobility using FRAP, in cardiomyocytes in the presence and absence of pre-treatment with GSNO. We show that in ventricular cardiomyocytes, nitrosylation of CaMKII at Cys273 prior to electrical field stimulation and activation by Ca2+ or β-adrenergic agonists suppresses CaMKIIδ activity and mobility, whereas mutation of the Cys273 to Serine prevents this effect. These findings support the suggestion that CaMKII nitrosylation at Cys273 could protect from the overactivation of CaMKIIδ in the heart, which has been implicated in numerous pathological states, including the progression from hypertrophy to heart failure, cardiac fibrosis, diabetic hyperglycemia, and upon reperfusion after ischemia.