权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Molecular mechanism underlying the regulation and its failure of calcium signalosome in atrial myocytes.

心房肌细胞钙信号小体调节及其失效的分子机制。

基本信息

批准号：
18590244
负责人：
AKAHANE Satomi
金额：
$ 2.57万
依托单位：
Toho University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Recent studies have shown that the impairment of L-type Ca^<2+> channel function is associated with arrhythmia such as atrial fibrillation. Aiming at clarifying the signaling molecular complex involved in the regulation of L-type Ca^<2+> channel in atria (calcium signalosome), we screened proteins associated with the carboxyl terminal region of Cav1.2. We found that the C-terminal region of Cav1.2 interacts with phosphatidylcholine transfer protein-like protein (PCTP-USTARD10). PCTP-L was expressed in embryonic whole heart and, in adult heart, in atria but not in ventricle. In rat atrial myocytes, PCTP-L colocalized and was coimmunoprecipitated with Cav1.2. PCTP-L attenuated the voltage-dependent inactivation of Cav1.2 through the specific interaction with the C-terminal region of Cav1.2. In the present study, our findings are as follows :1) The knockdown of PCTP-L by RNAi, in atrial myocytes, resulted in the shorteningof action potential duration and an increase in the frequency of sp … More ontaneous action potentials as well as Ca^<2+> transients. In addition, in atria of pressure-overloaded atrial fibrillation model rats, the mRNA expression level of PCTP-L was significantly reduced. These results suggest that PCTP-L is involved in the regulation of the excitability of atrial myocytes.2) To elucidate the role of Cav1.3, an atrial-specific subtype of L-type Ca^<2+> channels, we compared the electrophysiological properties with those of Cav1.2. In addition to lower voltage-dependence of activation and inactivation, Cav1.3 exibited slower voltage-dependent inactivation (VDI) and faster recovery from the inactivation compared to Cav1.2. Under voltage-clamp with SA nodal pacemaker action potential (AP) waveform, Cav1.3 current activated during diastolic depolarization and reactivated during repolarizing phase, while Cav1.2 current activated at the threshold of AR. Under repetitive depolarization, Cav1.3 maintained higher availability than Cav1.2. Computer simulation indicates that slow VDI and fast recovery kinetics of Cav1.3 contribute to maintain its availability under repetitive depolarizarion in SA node.3) The functional interaction between Cav1.2 and PCTP-L was impaired by replacing the C-terminal region of Cav1.2 by the comparable region of Cav1.3, thus indicating that PCTP-L interacts with Cav1.2 in a subtype-specific manner.4) ln order to clarify thefunctional role of PCTP-L in the Ca^<2+> signalosome surrounding the L-type Ca^<2+> channel in atria, we generated PCTP-L-KO mice. Phenotypes of PCTP-L-KO mice are under investigation. Less

近年来的研究表明，L型Ca^<2+>通道功能受损与心律失常如心房颤动有关。为了阐明参与心房L型Ca^2+通道调控的信号分子复合体（钙信号体），我们筛选了与Cav1.2羧基端区域相关的蛋白质。我们发现Cav1.2的C-末端区域与磷脂酰胆碱转移蛋白样蛋白（PCTP-USTARD 10）相互作用。PCTP-L在胚胎心脏中表达，在成人心脏中表达于心房，而在心室中不表达。在大鼠心房肌细胞，PCTP-L共定位，并与Cav1.2免疫共沉淀。PCTP-L通过与Cav1.2的C-末端区域特异性相互作用来减弱Cav1.2的电压依赖性失活。本研究的结果如下：1）RNA干扰抑制心房肌细胞PCTP-L基因表达，可使动作电位时程缩短，频率增加。 ...更多信息自发动作电位以及Ca^2+瞬变。此外，在压力负荷性房颤模型大鼠的心房中，PCTP-L的mRNA表达水平明显降低。这些结果表明PCTP-L参与了心房肌细胞兴奋性的调节。2）为了阐明Cav 1. 3（一种心房特异性的L型Ca^<2+>通道亚型）的作用，我们比较了Cav 1. 2和Cav 1. 3的电生理特性。除了激活和失活的电压依赖性较低外，Cav1.3与Cav1.2相比表现出较慢的电压依赖性失活（VEP）和更快的失活恢复。在SA结起搏动作电位（AP）电压钳下，Cav1.3电流在舒张期除极时激活，复极时再激活，Cav1.2电流在AR阈值时激活。在重复去极化下，Cav1.3比Cav1.2保持更高的可用性。计算机模拟表明Cav1.3在SA结重复去极化下的缓慢恢复和快速恢复动力学有助于维持其有效性。3）Cav1.2与PCTP-L之间的功能性相互作用通过Cav1.3的可比区域取代Cav1.2的C-末端区域而被削弱，4）为了阐明PCTP-L在心房L型Ca^<2 +>通道周围Ca^<2 +>信号体中的功能作用，我们产生了PCTP-L-KO小鼠。PCTP-L-KO小鼠的表型正在研究中。少