Adenylyl cyclase type VI corrects cardiac sarcoplasmic reticulum calcium uptake defects in cardiomyopathy

Calcium malfunction plays a central role in heart failure. Here, we provide evidence that adenylyl cyclase type VI restores sarco(endo)plasmic reticulum 2a (SERCA2a) affinity for calcium and maximum velocity of cardiac calcium uptake by sarcoplasmic reticulum in murine dilated cardiomyopathy. Restoration of normal SERCA2a affinity for calcium is associated not only with decreased phospholamban protein expression but also with increased phospholamban phosphorylation by PKA activation. The ratio of phosphorylated ryanodine receptor 2 (RyR2) to RyR2 protein was increased, but the amount of phosphorylated RyR2 was unaffected. These data provide a possible mechanism by which adenylyl cyclase type VI (in contrast to other signaling elements associated with increased cAMP generation) has a salutary effect in the failing heart.