title: The Role of Janus Kinase 3 in the Regulation of Na⁺/K⁺ ATPase under Energy Depletion.
abstract: OBJECTIVE
  Janus kinase-3 (JAK3) is activated during energy depletion. Energy-consuming pumps include the Na(+)/K(+)-ATPase. The present study explored whether JAK3 regulates Na(+)/K(+)-ATPase in dendritic cells (DCs).
  
  
  METHODS
  Ouabain (100 µM)-sensitive (Iouabain) and K(+)-induced (Ipump) outward currents were determined by utilizing whole cell patch-clamp, Na(+)/K(+)-ATPase α1-subunit mRNA levels by RT-PCR, Na(+)/K(+)-ATPase protein abundance by flow cytometry or immunofluorescence, and cellular ATP by luciferase-assay in DCs from bone marrow of JAK3-knockout (jak3(-/-)) or wild-type mice (jak3(+/+)). Ipump was further determined by voltage clamp in Xenopus oocytes expressing JAK3, active (A568V)JAK3 or inactive (K851A)JAK3.
  
  
  RESULTS
  Na(+)/K(+)-ATPase α1-subunit mRNA and protein levels, as well as Ipump and Iouabain were significantly higher in jak3(-/-)DCs than in jak3(+/+)DCs. Energy depletion by 4h pre-treatment with 2,4-dinitro-phenol significantly decreased Ipump in jak3(+/+) DCs but not in jak3(-/-)DCs. Cellular ATP was significantly lower in jak3(-/-)DCs than in jak3(+/+)DCs and decreased in both genotypes by 2,4-dinitro-phenol, an effect significantly more pronounced in jak3(-/-)DCs than in jak3(+/+)DCs and strongly blunted by ouabain in both jak3(+/+) and jak3(-/-)DCs. Ipump and Iouabain in oocytes were decreased by expression of JAK3 and of (A568V)JAK3 but not of (K851A)JAK3. JAK3 inhibitor WHI-P154 (4-[(3'-bromo-4'-hydroxyphenyl)amino]-6,7-dimethoxyquinazoline, 22 μM) enhanced Ipump and Iouabain in JAK3 expressing oocytes. The difference between (A568V)JAK3 and (K851A)JAK3 expressing oocytes was virtually abrogated by actinomycin D (50 nM).
  
  
  CONCLUSIONS
  JAK3 down-regulates Na(+)/K(+)-ATPase activity, an effect involving gene expression and profoundly curtailing ATP consumption.
authors.affiliation: Department of Physiology I, University of Tübingen, Tuebingen, Germany.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Hosseinzadeh
authors.forename: Sabina
authors.initials: S
authors.lastname: Honisch
authors.forename: Evi
authors.initials: E
authors.lastname: Schmid
authors.forename: Kashif
authors.initials: K
authors.lastname: Jilani
authors.forename: Kalina
authors.initials: K
authors.lastname: Szteyn
authors.forename: Shefalee
authors.initials: S
authors.lastname: Bhavsar
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Singh
authors.forename: Monica
authors.initials: M
authors.lastname: Palmada
authors.forename: Anja T
authors.initials: AT
authors.lastname: Umbach
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Shumilina
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects; D005260:Female; D017353:Gene Deletion; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D009154:Mutation; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014981:Xenopus
chemical_list: D011799:Quinazolines; C113888:WHI P154; D000255:Adenosine Triphosphate; D053616:Janus Kinase 3; D000254:Sodium-Potassium-Exchanging ATPase; D019297:2,4-Dinitrophenol