title: WNK3 Kinase Enhances the Sodium Chloride Cotransporter Expression via an ERK 1/2 Signaling Pathway.
abstract: BACKGROUND
  WNK kinase is a serine/threonine kinase that plays an important role in normal blood pressure homeostasis. WNK3 was previously found to enhance the activity of sodium chloride cotransporter (NCC) in Xenopus oocyte. However, the mechanism through which it works remains unclear.
  
  
  METHODS
  Using overexpression and siRNA knock-down techniques, the effects of WNK3 on NCC in both Cos-7 and mouse distal convoluted cells were analyzed by Western blot.
  
  
  RESULTS
  We found that WNK3 significantly increased NCC protein expression in a dose-dependent manner. NCC protein expression in Cos-7 cells was markedly decreased after 2 h treatment with protease inhibitor, cycloheximide (CHX) in the NCC alone group, but was significantly decreased after 8 h treatment of CHX in the WNK3 + NCC group. WNK3 significantly increased NCC protein expression in both NCC alone and WNK3 + NCC groups regardless the overnight treatments of bafilomycin A1, a proton pump inhibitor, suggesting that WNK3-mediated increased NCC expression is not dependent on the lysosomal pathway. We further found that WNK3 group had a quicker NCC recovery than the control group using CHX pulse assay, suggesting that WNK3 increases NCC protein synthesis. WNK3 enhanced NCC protein level while reducing ERK 1/2 phosphorylation. In addition, knock-down of ERK 1/2 expression reversed WNK3-mediated increase of NCC expression.
  
  
  CONCLUSIONS
  These results suggest that WNK3 enhances NCC protein expression by increasing NCC synthesis via an ERK 1/2-dependent signaling pathway.
authors.affiliation: Department of Nephrology, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
authors.forename: Dexuan
authors.initials: D
authors.lastname: Wang
authors.forename: Yiqian
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jinhua
authors.initials: J
authors.lastname: Han
authors.forename: Shufang
authors.initials: S
authors.lastname: Pan
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
authors.forename: Xiuyan
authors.initials: X
authors.lastname: Feng
authors.forename: Zhizhi
authors.initials: Z
authors.lastname: Zhuang
authors.forename: Courtney
authors.initials: C
authors.lastname: Caroti
authors.forename: Jieqiu
authors.initials: J
authors.lastname: Zhuang
authors.forename: Robert S
authors.initials: RS
authors.lastname: Hoover
authors.forename: Dingying
authors.initials: D
authors.lastname: Gu
authors.forename: Qiyi
authors.initials: Q
authors.lastname: Zeng
authors.forename: Hui
authors.initials: H
authors.lastname: Cai
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006801:Humans; D020935:MAP Kinase Signaling System; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D049992:Sodium Chloride Symporters / Q000378:metabolism*
chemical_list: D049992:Sodium Chloride Symporters; D017346:Protein Serine-Threonine Kinases; C488586:WNK3 protein, human