title: Identification of the WNK-SPAK/OSR1 signaling pathway in rodent and human lenses.
abstract: OBJECTIVE
  To identify whether the kinases that regulate the activity of cation chloride cotransporters (CCC) in other tissues are also expressed in rat and human lenses.
  
  
  METHODS
  The expression of with-no-lysine kinase (WNK 1, 3, 4), oxidative stress response kinase 1 (OSR1), and Ste20-like proline alanine rich kinase (SPAK) were determined at either the transcript or protein levels in the rat and human lenses by reverse-transcriptase PCR and/or Western blotting, respectively. Selected kinases were regionally and subcellularly characterized in rat and human lenses. The transparency, wet weight, and tissue morphology of lenses extracted from SPAK knock-out animals was compared with wild-type lenses.
  
  
  RESULTS
  WNK 1, 3, 4, SPAK, and OSR1 were identified at the transcript level in rat lenses and WNK1, 4, SPAK, and OSR1 expression confirmed at the protein level in both rat and human lenses. SPAK and OSR1 were found to associate with membranes as peripheral proteins and exhibited distinct subcellular and region-specific expression profiles throughout the lens. No significant difference in the wet weight of SPAK knock-out lenses was detected relative to wild-type lenses. However, SPAK knock-out lenses showed an increased susceptibility to opacification.
  
  
  CONCLUSIONS
  Our results show that the WNK 1, 3, 4, OSR1, and SPAK signaling system known to play a role in regulating the phosphorylation status, and hence activity of the CCCs in other tissues, is also present in the rat and human lenses. The increased susceptibility of SPAK lenses to opacification suggests that disruption of this signaling pathway may compromise the ability of the lens to control its volume, and its ability to maintain its transparency.
authors.affiliation: Department of Optometry and Vision Science, University of Auckland, New Zealand The New Zealand National Eye Centre, University of Auckland, New Zealand.
authors.forename: Irene
authors.initials: I
authors.lastname: Vorontsova
authors.affiliation: Department of Optometry and Vision Science, University of Auckland, New Zealand The New Zealand National Eye Centre, University of Auckland, New Zealand.
authors.forename: Leo
authors.initials: L
authors.lastname: Lam
authors.affiliation: Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Delpire
authors.affiliation: Department of Optometry and Vision Science, University of Auckland, New Zealand The New Zealand National Eye Centre, University of Auckland, New Zealand.
authors.forename: Julie
authors.initials: J
authors.lastname: Lim
authors.affiliation: Department of Optometry and Vision Science, University of Auckland, New Zealand The New Zealand National Eye Centre, University of Auckland, New Zealand School of Medical Sciences, University of Auckland, New Zealand.
authors.forename: Paul
authors.initials: P
authors.lastname: Donaldson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015153:Blotting, Western; D002386:Cataract / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D006801:Humans; D007908:Lens, Crystalline / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008875:Middle Aged; D018384:Oxidative Stress; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D055815:Young Adult
chemical_list: D011506:Proteins; D014157:Transcription Factors; D012313:RNA; D011494:Protein Kinases; C118135:OXSR1 protein, human; C486407:Stk39 protein, mouse; C116037:PAS domain kinases; C534421:OXSR1 protein, mouse; C506604:Oxsr1 protein, rat; D017346:Protein Serine-Threonine Kinases; C486409:STK39 protein, human
keywords: OSR1SPAK knock out; SPAK; WNK; cataract; cation chloride cotransporters; cell volume regulation; lens