title: WNK4 inhibits NCC protein expression through MAPK ERK1/2 signaling pathway.
abstract: WNK [with no lysine (K)] kinase is a subfamily of serine/threonine kinases. Mutations in two members of this family (WNK1 and WNK4) cause pseudohypoaldosteronism type II featuring hypertension, hyperkalemia, and metabolic acidosis. WNK1 and WNK4 were shown to regulate sodium chloride cotransporter (NCC) activity through phosphorylating SPAK and OSR1. Previous studies including ours have also shown that WNK4 inhibits NCC function and its protein expression. A recent study reported that a phorbol ester inhibits NCC function via activation of extracellular signal-regulated kinase (ERK) 1/2 kinase. In the current study, we investigated whether WNK4 affects NCC via the MAPK ERK1/2 signaling pathway. We found that WNK4 increased ERK1/2 phosphorylation in a dose-dependent manner in mouse distal convoluted tubule (mDCT) cells, whereas WNK4 mutants with the PHA II mutations (E562K and R1185C) lost the ability to increase the ERK1/2 phosphorylation. Hypertonicity significantly increased ERK1/2 phosphorylation in mDCT cells. Knock-down of WNK4 expression by siRNA resulted in a decrease of ERK1/2 phosphorylation. We further showed that WNK4 knock-down significantly increases the cell surface and total NCC protein expressions and ERK1/2 knock-down also significantly increases cell surface and total NCC expression. These data suggest that WNK4 inhibits NCC through activating the MAPK ERK1/2 signaling pathway.
authors: Renal Div., Emory Univ. School of Medicine, Atlanta, GA 30322, USA. hcai3@emory.edu
authors: Bo
authors: B
authors: Zhou
authors: Dexuan
authors: D
authors: Wang
authors: Xiuyan
authors: X
authors: Feng
authors: Yiqian
authors: Y
authors: Zhang
authors: Yanhui
authors: Y
authors: Wang
authors: Jieqiu
authors: J
authors: Zhuang
authors: Xuemei
authors: X
authors: Zhang
authors: Guangping
authors: G
authors: Chen
authors: Eric
authors: E
authors: Delpire
authors: Dingying
authors: D
authors: Gu
authors: Hui
authors: H
authors: Cai
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism*; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters / Q000235:genetics / Q000378:metabolism*
chemical_list: D011955:Receptors, Drug; C578875:Slc12a3 protein, mouse; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters; C499024:Prkwnk4 protein, mouse; D017346:Protein Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases