WNK1 Activates Large-Conductance Ca2+-Activated K+ Channels through Modulation of ERK1/2 Signaling
WNK1 Activates Large-Conductance Ca2+-Activated K+ Channels through Modulation of ERK1/2 Signaling
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WNK1 通过调节 ERK1/2 信号传导激活大电导 Ca2 激活的 K 通道
DOI：
10.1681/asn.2014020186
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发表时间：
2015-04-01
影响因子：
13.6
通讯作者：
Cai, Hui
中科院分区：
文献类型：
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作者：
Liu, Yingli;Song, Xiang;Cai, Hui
不含赖氨酸(WNK)的激酶是丝氨酸/苏氨酸激酶家族的成员。我们先前发现WNK4通过溶酶体途径促进肾大电导钙激活K+(BK)通道的降解，从而抑制其活性。在本研究中，我们研究了WNK1对BK通道活性的影响。在稳定表达BKα亚基的HEK293细胞(HEK-BKα细胞)中，siRNA介导的WNK1表达下调显著抑制了BKα通道的活性和开放概率。WNK1表达下调可显著抑制HEK293细胞中BKα蛋白的表达和ERK1/2的磷酸化，而WNK1的过表达则显著增强BKα的表达和降低ERK1/2的磷酸化，且呈剂量依赖关系。ERK1/2基因敲除可阻断WNK1 siRNA对BKα表达的抑制。同样，用溶酶体抑制剂Bafilmycin A1预处理HEK-BKα细胞，可剂量依赖地逆转WNK1 siRNA对BKα表达的抑制作用。下调WNK1的表达也增加了BKα通道的泛素化。值得注意的是，与喂食正常K+饮食的小鼠相比，喂食高K+饮食10天的小鼠肾脏BKα和WNK1的蛋白表达水平显著较高，而ERK1/2的磷酸化水平较低。这些数据表明，WNK1通过减少ERK1/2信号介导的BK通道溶酶体降解来增强BK通道的功能。
With no lysine (WNK) kinases are members of the serine/threonine kinase family. We previously showed that WNK4 inhibits renal large-conductance Ca2+-activated K+ (BK) channel activity by enhancing its degradation through a lysosomal pathway. In this study, we investigated the effect of WNK1 on BK channel activity. In HEK293 cells stably expressing the alpha subunit of BK (HEK-BK alpha cells), siRNA-mediated knockdown of WNK1 expression significantly inhibited both BK alpha channel activity and open probability. Knockdown of WNK1 expression also significantly inhibited BK alpha protein expression and increased ERK1/2 phosphorylation, whereas overexpression of WNK1 significantly enhanced BK alpha expression and decreased ERK1/2 phosphorylation in a dose-dependent manner in HEK293 cells. Knockdown of ERK1/2 prevented WNK1 siRNA-mediated inhibition of BK alpha expression. Similarly, pretreatment of HEK-BK alpha cells with the lysosomal inhibitor bafilomycin A1 reversed the inhibitory effects of WNK1 siRNA on BK alpha expression in a dose-dependent manner. Knock-down of WNK1 expression also increased the ubiquitination of BK alpha channels. Notably, mice fed a high-K+ diet for 10 days had significantly higher renal protein expression levels of BK alpha and WNK1 and lower levels of ERK1/2 phosphorylation compared with mice fed a normal-K+ diet. These data suggest that WNK1 enhances BK channel function by reducing ERK1/2 signaling-mediated lysosomal degradation of the channel.