Protein kinase A-mediated phosphorylation of HERG potassium channels in a human cell line

作     者：WEI Zhang, Dierk Thomas, Christoph A Karle, Sven Kathfer, Johannes Schenkel, Volker A W Kreye, Eckhard Ficker Barbara A Wible and Johann Kiehn Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany (Zhang W, T 

作者机构：Department of Cardiology Medical University Hospital Heidelberg Heidelberg Germany Department of Physiology and Pathophysiology University of HeidelbergHeidelberg Germany Rammelkamp Center for Education and Research Case Western Reserve University School of Medicine MetroHealth Medical Center Cleveland USA 

出 版 物：《中华医学杂志(英文版)》 (Chinese Medical Journal)

年 卷 期：2002年第000卷第5期

页      面：28-36页

核心收录：

学科分类：1001[医学-基础医学(可授医学、理学学位)] 10[医学] 

基　　金：This work was supported by a grant from the Deutsche Forschungsgemeinschaft (ProjectKI 6 6 3/1 1toDr J Kiehn) D Thomas was supported by the German National Merit Scholarship Foundation 

主　　题：adrenergic stimulation · arrhythmia · cyclic AMP · HERG potassium channel · protein kinase A 

摘      要：Objective To investigate the molecular mechanism of human ether a go go related gene (HERG) potassium channels regulated by protein kinase A (PKA) in a human cell line Methods HERG channels were stably expressed in human embryonic kidney (HEK) 293 cells, and currents were measured with the patch clamp technique The direct phosphorylation of HERG channel proteins expressed heterologously in Xenopus laevis oocytes was examined by 32 P labeling and immunoprecipitation with an anti HERG antibody Results Elevation of the intracellular cAMP concentration by incubation with the adenylate cyclase activator, forskolin (10?μmol/L), and the broad range phosphodiesterase inhibitor, IBMX (100?μmol/L), caused a HERG tail current reduction of 83 2% In addition, direct application of the membrane permeable cAMP analog, 8 Br cAMP (500?μmol/L), reduced the tail current amplitude by 29 3% Intracellular application of the catalytic subunit of protein kinase A (200 U/ml) led to a tail current decrease by 56 9% and shifted the activation curve by 15 4 mV towards more positive potentials HERG WT proteins showed two phosphorylated bands, an upper band with a molecular mass of ≈155 kDa and a lower band with a molecular mass of ≈135 kDa, indicating that both the core and the fully glycosylated forms of the protein were phosphorylated Conclusions PKA mediated phosphorylation of HERG channels causes current reduction in a human cell line The coupling between the repolarizing cardiac HERG potassium current and the protein kinase A system could contribute to arrhythmogenesis under pathophysiological conditions