Role of protein phosphatases in the run down of guinea pig cardiac Cav1.2 Ca2+ channels
Role of protein phosphatases in the run down of guinea pig cardiac Cav1.2 Ca2+ channels
复制标题
蛋白磷酸酶在豚鼠心脏 Cav1.2 Ca2 通道下降中的作用
DOI：
10.1152/ajpcell.00199.2015
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发表时间：
2016
影响因子：
5.5
通讯作者：
Kameyama Masaki
中科院分区：
文献类型：
--
作者：
Yu Lifeng;Xu Jianjun;Minobe Etsuko;Kameyama Asako;Yang Lei;Feng Rui;Hao Liying;Kameyama Masaki
本研究的目的是研究蛋白磷酸酶参与Cav1.2钙通道的运行。用膜片钳技术记录成年豚鼠单个心室肌细胞钙通道电流。钙调素（CaM）和ATP被用来恢复通道活性的内面向外补丁。蛋白磷酸酶抑制剂被用来研究磷酸酶的作用。特异性蛋白磷酸酶1（PP 1）抑制剂（PP 1 inhibitor-2）和蛋白磷酸酶2A（PP 2A）抑制剂（fostriecin）可阻断CaV 1.2钙通道的缓慢下降，这表现为CaM/ATP对CaV 1.2钙通道的逆转作用随时间而减弱。然而，蛋白磷酸酶2B型（PP 2B，钙调神经磷酸酶）抑制剂环孢素A与亲环素A一起对通道运行没有影响。PP 1 inhibitor-2主要延长通道的开放时间常数，尤其是慢开放时间。Fostriecin主要缩短缓慢关闭时间常数。结果表明，PP 1和PP 2A参与了CaV1.2钙通道的慢相流。此外，它们对通道的开闭动力学产生不同的影响。以上结果支持了PP 1和PP 2A可以去磷酸化Cav1.2钙通道上不同的磷酸化位点的观点。
This study aimed to investigate protein phosphatases involved in the run down of Cav1.2 Ca2+channels. Single ventricular myocytes obtained from adult guinea pig hearts were used to record Ca2+channel currents with the patch-clamp technique. Calmodulin (CaM) and ATP were used to restore channel activity in inside-out patches. Inhibitors of protein phosphatases were applied to investigate the role of phosphatases. The specific protein phosphatase type 1 (PP1) inhibitor (PP1 inhibitor-2) and protein phosphatase type 2A (PP2A) inhibitor (fostriecin) abolished the slow run down of Cav1.2 Ca2+channels, which was evident as the time-dependent attenuation of the reversing effect of CaM/ATP on the run down. However, protein phosphatase type 2B (PP2B, calcineurin) inhibitor cyclosporine A together with cyclophilin A had no effect on the channel run down. Furthermore, PP1 inhibitor-2 mainly prolonged the open time constants of the channel, specifically, the slow open time. Fostriecin primarily shortened the slow close time constants. Our data suggest that PP1 and PP2A were involved in the slow phase of Cav1.2 Ca2+channel run down. In addition, they exerted different effects on the open-close kinetics of the channel. All above support the view that PP1 and PP2A may dephosphorylate distinct phosphorylation sites on the Cav1.2 Ca2+channel.