Adrenergic Signaling Controls RGK-Dependent Trafficking of Cardiac Voltage-Gated L-Type Ca2+ Channels Through PKD1

作者：Jhun Bong Sook; O Uchi Jin; Wang Weiye; Ha Chang Hoon; Zhao Jinjing; Kim Ji Young; Wong Chelsea; Dirksen Robert T; Lopes Coeli M B; Jin Zheng Gen^*

来源：Circulation Research, 2012, 110(1): 59-70.

DOI：10.1161/CIRCRESAHA.111.254672

• adrenoceptor
• patch clamp
• phenylephrine

Rationale: The Rad-Gem/Kir-related family (RGKs) consists of small GTP-binding proteins that strongly inhibit the activity of voltage-gated calcium channels. Among RGKs, Rem1 is strongly and specifically expressed in cardiac tissue. However, the physiological role and regulation of RGKs, and Rem1 in particular, are largely unknown.
Objective: To determine if Rem1 function is physiologically regulated by adrenergic signaling and thus impacts voltage-gated L-type calcium channel (VLCC) activity in the heart.
Methods and Results: We found that activation of protein kinase D1, a protein kinase downstream of alpha(1)-adrenergic signaling, leads to direct phosphorylation of Rem1 at Ser18. This results in an increase of the channel activity and plasma membrane expression observed by using a combination of electrophysiology, live cell confocal microscopy, and immunohistochemistry in heterologous expression system and neonatal cardiomyocytes. In addition, we show that stimulation of alpha(1)-adrenergic receptor-protein kinase D1-Rem1 signaling increases transverse-tubule VLCC expression that results in increased L-type Ca2+ current density in adult ventricular myocytes.
Conclusion: The alpha(1)-adrenergic stimulation releases Rem1 inhibition of VLCCs through direct phosphorylation of Rem1 at Ser18 by protein kinase D1, resulting in an increase of the channel activity and transverse-tubule expression. Our results uncover a novel molecular regulatory mechanism of VLCC trafficking and function in the heart and provide the first demonstration of physiological regulation of RGK function. (Circ Res. 2012;110:59-70.)

• 出版日期2012-1-6