WNK1 activates large-conductance Ca2+-activated K+ channels through modulation of ERK1/2 signaling

• Published in: Journal of the American Society of Nephrology Vol. 26; no. 4; pp. 844 - 854
• Main Authors: Liu, Yingli, Song, Xiang, Shi, Yanling, Shi, Zhen, Niu, Weihui, Feng, Xiuyan, Gu, Dingying, Bao, Hui-Fang, Ma, He-Ping, Eaton, Douglas C, Zhuang, Jieqiu, Cai, Hui
• Format: Journal Article
• Language: English
• Published: United States American Society of Nephrology 01.04.2015
• Subjects: Animals; Basic Research; HEK293 Cells; Humans; Intracellular Signaling Peptides and Proteins - metabolism; Large-Conductance Calcium-Activated Potassium Channels - metabolism; Lysosomes - metabolism; MAP Kinase Signaling System; Mice, Inbred C57BL; Minor Histocompatibility Antigens; Protein-Serine-Threonine Kinases - metabolism; Water-Electrolyte Balance; WNK Lysine-Deficient Protein Kinase 1; Cell and transport physiology; K channels; cell signaling
• ISSN: 1046-6673; 1533-3450
• DOI: 10.1681/asn.2014020186

With no lysine (WNK) kinases are members of the serine/threonine kinase family. We previously showed that WNK4 inhibits renal large-conductance Ca(2+)-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 α subunit of BK (HEK-BKα cells), siRNA-mediated knockdown of WNK1 expression significantly inhibited both BKα channel activity and open probability. Knockdown of WNK1 expression also significantly inhibited BKα protein expression and increased ERK1/2 phosphorylation, whereas overexpression of WNK1 significantly enhanced BKα expression and decreased ERK1/2 phosphorylation in a dose-dependent manner in HEK293 cells. Knockdown of ERK1/2 prevented WNK1 siRNA-mediated inhibition of BKα expression. Similarly, pretreatment of HEK-BKα cells with the lysosomal inhibitor bafilomycin A1 reversed the inhibitory effects of WNK1 siRNA on BKα expression in a dose-dependent manner. Knockdown of WNK1 expression also increased the ubiquitination of BKα channels. Notably, mice fed a high-K(+) diet for 10 days had significantly higher renal protein expression levels of BKα 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.