title: SPAK and OSR1 Sensitive Cell Membrane Protein Abundance and Activity of KCNQ1/E1 K+ Channels.
abstract: OBJECTIVE
  KCNQ1/E1 channels are expressed in diverse tissues and serve a variety of functions including endolymph secretion in the inner ear, cardiac repolarization, epithelial transport and cell volume regulation. Kinases involved in regulation of epithelial transport and cell volume include SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1), which are under control of WNK (with-no-K[Lys]) kinases. The present study explored whether KCNQ1/E1 channels are regulated by SPAK and/or OSR1.
  
  
  METHODS
  cRNA encoding KCNQ1/E1 was injected into Xenopus oocytes with or without additional injection of cRNA encoding wild-type SPAK, constitutively active T233ESPAK, WNK insensitive T233ASPAK, catalytically inactive D212ASPAK, wild-type OSR1, constitutively active T185EOSR1, WNK insensitive T185AOSR1 and catalytically inactive D164AOSR1. Voltage gated K+ channel activity was quantified utilizing dual electrode voltage clamp and KCNQ1/E1 channel protein abundance in the cell membrane utilizing chemiluminescence of KCNQ1/E1 containing an extracellular Flag tag epitope (KCNQ1-Flag/E1).
  
  
  RESULTS
  KCNQ1/E1 activity and KCNQ1-Flag/E1 protein abundance were significantly enhanced by wild-type SPAK and T233ESPAK, but not by T233ASPAK and D212ASPAK. Similarly, KCNQ1/E1 activity and KCNQ1-Flag/E1 protein abundance were significantly increased by wild-type OSR1 and T185EOSR1, but not by T185AOSR1 and D164AOSR1.
  
  
  CONCLUSIONS
  SPAK and OSR1 participate in the regulation of KCNQ1/E1 protein abundance and activity.
authors.forename: Bernat
authors.initials: B
authors.lastname: Elvira
authors.forename: Jamshed
authors.initials: J
authors.lastname: Warsi
authors.forename: Myriam
authors.initials: M
authors.lastname: Fezai
authors.forename: Carlos
authors.initials: C
authors.lastname: Munoz
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000200:Action Potentials; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D007477:Ions / Q000737:chemistry / Q000378:metabolism; D051657:KCNQ1 Potassium Channel / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000254:growth & development / Q000378:metabolism
chemical_list: D007477:Ions; C489622:KCNE1 protein, human; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; D024642:Potassium Channels, Voltage-Gated; C118135:OXSR1 protein, human; D017346:Protein Serine-Threonine Kinases; C486409:STK39 protein, human; D011188:Potassium