Molecular mechanisms of regulation of L-type Ca channels

L型Ca通道调节的分子机制

基本信息

批准号：
17590189
负责人：
KAMEYAMA Masaki
金额：
$ 2.18万
依托单位：
Kagoshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17590189/
关键词：
calcium channels calmodulin calmodulin kinase II patch clamp cardiac myocytes GST融合蛋白

项目摘要

Activity of the cardiac L-type Ca^<2+> channel (Ca_v1.2) is modulated by dual feedback mechanisms, i.e., Ca^<2+>-dependent facilitation (CDF) and Ca^<2+>-dependent inactivation (CDI). Although calmodulin (CaM) has been suggested to mediate both CDF and CDI, Ca^<2+>/CaM-dependent protein kinase II (CaMKII) is also suggested to play a primary role in CDF. In this study, we investigated the roles and relations of Ca^<2+>, CaM and CaMKII in the basal activity, CDF and CDI using the patch-clamp method in guinea-pig ventricular myocytes. In the cell-attached mode, inhibitors of CaM significantly reduced both CDF and CDI, whereas those of CaMKII only modulated the time courses of CDF and CDI. In the inside-out mode, CaM (0.1-3μM) + ATP (2.4-3 mM)(at [Ca^<2+>]_i <10 nM) produced dose-dependent channel activity with a bell-shaped relationship between [CaM] and channel activity and with a maximum activation of 200-300% of control. Increasing of [Ca^<2+>]_i (~500 nM) shifted the [CaM]-channel activity curve toward left (i.e., to lower [CaM]). Thus, at a fixed concentration of CaM (e.g. 0.5 μM), Ca^<2+> showed biphasic effects: facilitation at [Ca^<2+>]_i <500 nM, and inactivation at [Ca^<2+>]_i >500 nM. This Ca^<2+>-dependent effect of CaM was considered to represent CDF and CDI. Based on these data, a simple model for Ca^<2+>-and CaM-dependent modulation of the Ca_v1.2 channel has been proposed, in which the channel had two CaM-binding sites, one for the basal activity and CDF and the other for CDI. In conclusion, it is suggested that CaM plays key roles in maintaining the basal activity and in producing CDF and CDI of the channel, and that CaMKII and Ca^<2+> modulate the interaction between the channel and CaM.

CardiACL L型Ca^<2+>通道（CA_V1.2）的活性是模块化的，CA^<2+> - exepepenteppentivation（CDI）已被助长以介导CDI，CAM-DECENTER蛋白激酶II（ Camkii）在这项研究中也起着主要作用。，而那些在内而外模式下（0.1-3μm） + ATP（2.4-3） ^<2+>] _i <10 nm的时间介绍了CDF和CDI的时间课程。 [CAM]和通道活动之间的钟形关系，最大对照的200-300％。因此，在cam（例如0.5μm）d双相效应的固定伴奏中：促进[ca^<2+>] _ I <500 nm在这些数据上，Ca_v1.2通道的CA^<2+> - 依赖性调制的简单模型已占据，一个用于基础活动，CDF和您的另一个用于CDI。 CAM在维持基础活性并产生频道的CDF和CDI方面发挥作用。