Silencing of striatin alters the association of caveolin‐3 with the L‐type calcium channel in cardiomyocytes.

Abstract

Striatin (STRN) is a dynamic protein containing binding domains for caveolin (Cav), protein phosphatases 2A (PP2A), and calmodulin (CaM). Although these proteins regulate the kinetics of the L‐type calcium channel (LCC), the role of STRN in this context remains unknown. We have previously reported that STRN can modulate the intracellular calcium and the contraction rate of cultured cardiomyocytes (CMs). Here we show that STRN is highly expressed in adult rat ventricles as compared to atria. Biochemical analysis revealed that neither the knockdown of STRN (shRNA) nor its overexpression in CMs modulated the expression level of Cav‐3, PP2A, or LCC. Interestingly, silencing of STRN enhanced the association of Cav‐3 with CaM but not PP2A. In contrast, the overexpression of STRN significantly reduced the interaction of Cav‐3 with CaM and PP2A. In both cases, the amount of LCC interacting with STRN/Cav‐3/CaM/PP2A complex was unchanged. Taken together, our data suggest that the regulation of intracellular calcium by STRN may be due to alterations in Caveolin‐3 binding to CaM/PP2A/LCC complex thus regulating the kinetics of LCC in cardiomyocytes.