Activation of TRPV4 Channels (hVRL-2/mTRP12) by Phorbol Derivatives

作者：Hiroyuki Watanabe, John B. Davis, Darren Smart, Jeff C. Jerman, G. David Smith, Philip D. Hayes, Joris Vriens, William J. Cairns, Ullrich Wissenbach, Jean Prenen, Veit Flockerzi, Guy Droogmans, Christopher D. Benham, Bernd Nilius · 发表于：Journal of Biological Chemistry · 年份：2002 · DOI：10.1074/jbc.m200062200 · 被引用次数：605 · 研究领域：Ion Channels and Receptors、Herbal Medicine Research Studies、Respiratory and Cough-Related Research

We have studied activation by phorbol derivatives of TRPV4 channels, the human VRL-2, and murine TRP12 channels, which are highly homologous to the human VR-OAC, and the human and murine OTRPC4 channel. 4alpha-Phorbol 12,13-didecanoate (4alpha-PDD) induced an increase in intracellular Ca(2+) concentration, [Ca(2+)](i), in 1321N1 cells stably transfected with human VRL-2 (hVRL-2.1321N1) or HEK-293 cells transiently transfected with murine TRP12, but not in nontransfected or mock-transfected cells. Concomitantly with the increase in [Ca(2+)](i), 4alpha-PDD activated an outwardly rectifying cation channel with an Eisenman IV permeation sequence for monovalent cations that is Ca(2+)-permeable with P(Ca)/P(Na) = 5.8. Phorbol 12-myristate 13-acetate also induced an increase in [Ca(2+)](i) but was approximately 50 times less effective than 4alpha-PDD. EC(50) for Ca(2+) increase and current activation was nearly identical (pEC(50) approximately 6.7). Similar effects were observed in freshly isolated mouse aorta endothelial cells which express TRP12 endogenously. By using 4alpha-PDD as a tool to stimulate TRP12, we showed that activation of this channel is modulated by [Ca(2+)](i); an increase in [Ca(2+)](i) inhibits the channel with an IC(50) of 406 nm. Ruthenium Red at a concentration of 1 microm completely blocks inward currents at -80 mV but has a smaller effect on outward currents likely indicating a voltage dependent channel block. We concluded that the phorbol derivatives activ...