Modulation of I channel-PIP interaction by PRMT1 plays a critical role in the control of cardiac repolarization.

Recent studies have shown that protein arginine methyltransferase 1 (PRMT1) is highly expressed in the human heart, and loss of PRMT1 contributes to cardiac remodeling in the heart failure. However, the functional importance of PRMT1 in cardiac ion channels remains uncertain. The slow activating delayed rectifier K (I ) channel is a cardiac K channel composed of KCNQ1 and KCNE1 subunits and is a new therapeutic target for treating lethal arrhythmias in many cardiac pathologies, especially heart failure. Here, we demonstrate that PRMT1 is a critical regulator of the I channel and cardiac rhythm. In the guinea pig ventricular myocytes, treatment with furamidine, a PRMT1-specific inhibitor, prolonged the action potential duration (APD). We further show that this APD prolongation was attributable to I reduction. In HEK293T cells expressing human KCNQ1 and KCNE1, inhibiting PRMT1 via furamidine reduced I and concurrently decreased the arginine methylation of KCNQ1, a pore-forming α-subunit. Evidence presented here indicates that furamidine decreased I mainly by lowering the affinity of I channels for the membrane phospholipid, phosphatidylinositol 4,5-bisphosphate (PIP ), which is crucial for pore opening. Finally, applying exogenous PIP to cardiomyocytes prevented the furamidine-induced I reduction and APD prolongation. Taken together, these results indicate that PRMT1 positively regulated I activity through channel-PIP interaction, thereby restricting excessive cardiac action potential.