title: Identification of a novel WNK4 mutation in Chinese patients with pseudohypoaldosteronism type II.
abstract: BACKGROUND
  It has been reported that mutations in WNK1 and WNK4 cause pseudohypoaldosteronism type II (PHA2), an autosomal dominant renal disease. WNK kinase proteins are expressed in the kidney and regulate ion transport including the thiazide-sensitive sodium chloride cotransporter (NCC). In this report, we screened 4 Chinese PHA2 pedigrees for WNK4 mutations, identified a novel mutation, and studied its effects on NCC protein trafficking in vitro.
  
  
  METHODS
  The patients' genomic DNA was extracted from peripheral leukocytes. Sequence analysis was performed by PCR amplification of the 19 exons of WNK4. The wild-type or mutant WNK4 was coexpressed with NCC in HEK293 cells. We measured the effect of wild-type WNK4 compared to the mutant WNK4 on NCC protein surface expression.
  
  
  RESULTS
  A novel missense mutation in WNK4, K1169E, was identified in 1 of the 4 pedigrees. Analysis of confocal images showed that K1169E lost its inhibitory effect on NCC surface expression compared to wild-type WNK4 when expressed in HEK293 cells, while it did not change NCC total protein expression.
  
  
  CONCLUSIONS
  We identified an unreported disease-causing WNK4 missense mutation, K1169E, in 1 Chinese PHA2 pedigree. This mutation appears to be a 'loss of function' of NCC inhibition and suggests that some important functional roles lie in the 2nd coiled-coil domain of WNK4.
authors.affiliation: Department of Nephrology, School of Medicine, Shanghai Jiao Tong University, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Zhang
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Wang
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Xie
authors.forename: Fuhong
authors.initials: F
authors.lastname: Yan
authors.forename: Weiming
authors.initials: W
authors.lastname: Wang
authors.forename: Xiaobei
authors.initials: X
authors.lastname: Feng
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D044466:Asian People / Q000235:genetics; D001483:Base Sequence; D015153:Blotting, Western; D002648:Child; D002681:China; D004252:DNA Mutational Analysis; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010375:Pedigree; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D011546:Pseudohypoaldosteronism / Q000208:ethnology / Q000235:genetics*; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters / Q000235:genetics / Q000378:metabolism
chemical_list: D011955:Receptors, Drug; C578874:SLC12A3 protein, human; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters; D017346:Protein Serine-Threonine Kinases; C433806:WNK4 protein, human