Kameda Kazutoshi, Fukao Mitsuhiro, Kobayashi Takeshi, Tsutsuura Masaaki, Nagashima Masato, Yamada Yoichi, Yamashita Toshihiko, Tohse Noritsugu
Department of Cellular Physiology and Signal Transduction, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.
J Mol Cell Cardiol. 2006 Apr;40(4):562-9. doi: 10.1016/j.yjmcc.2006.01.007. Epub 2006 Feb 14.
L-type Ca(2+) channels have a wide tissue distribution and play essential roles in physiological responses. Recent studies have indicated that regulation of L-type Ca(2+) channels involves the assembly of macromolecular signaling complexes such as the beta(2)-adrenergic receptor signaling complex, the small G-protein kir/Gem and the BK channel. Here, we report the previously unidentified role of another protein in binding to the II-III linker of the alpha(1C) subunit of the L-type Ca(2+) channel. This protein is COP9 signalosome subunit 5 (CSN5)/Jun activation domain-binding protein 1 (Jab1). We have demonstrated that CSN5 interacts specifically with the II-III linker of the alpha(1C) subunit in a yeast two-hybrid system. The alpha(1C) subunit and CSN5 were coimmunoprecipitated in rat heart and both proteins were colocalized in sarcolemmal membranes and transverse tubules of cardiac myocytes. Silencing of CSN5 mRNA using siRNA decreased the endogenous protein level of CSN5 and activated L-type Ca(2+) channels expressed in COS7 cells. These data indicate that CSN5 is a protein that plays a newly defined functional role in association with the cardiac L-type Ca(2+) channel.
L型Ca(2+)通道具有广泛的组织分布，在生理反应中发挥着重要作用。最近的研究表明，L型Ca(2+)通道的调节涉及大分子信号复合物的组装，如β(2)-肾上腺素能受体信号复合物、小G蛋白kir/Gem和BK通道。在此，我们报道了另一种蛋白质与L型Ca(2+)通道α(1C)亚基的II-III连接区结合的此前未被发现的作用。这种蛋白质是COP9信号体亚基5（CSN5）/Jun激活域结合蛋白1（Jab1）。我们已经证明，在酵母双杂交系统中，CSN5与α(1C)亚基的II-III连接区特异性相互作用。α(1C)亚基和CSN5在大鼠心脏中进行了共免疫沉淀，并且这两种蛋白质在心肌细胞的肌膜和横管中共定位。使用siRNA沉默CSN5 mRNA降低了CSN5的内源性蛋白水平，并激活了在COS7细胞中表达的L型Ca(2+)通道。这些数据表明，CSN5是一种与心脏L型Ca(2+)通道相关的发挥新定义功能作用的蛋白质。
