title: Hypoxia-mediated Na-K-ATPase degradation requires von Hippel Lindau protein.
abstract: Hypoxia inhibits Na-K-ATPase activity and leads to its degradation in mammalian cells. Von Hippel Lindau protein (pVHL) and hypoxia inducible factor (HIF) are key mediators in cellular adaptation to hypoxia; thus, we set out to investigate whether pVHL and HIF participate in the hypoxia-mediated degradation of plasma membrane Na-K-ATPase. We found that in the presence of pVHL hypoxia decreased Na-K-ATPase activity and promoted the degradation of plasma membrane Na-K-ATPase. In pVHL-deficient cells, hypoxia did not decrease the Na-K-ATPase activity and the degradation of plasma membrane Na-K-ATPase was prevented. pVHL-mediated degradation of Na-K-ATPase required the functional pVHL E3 ligase and Ubc5 since pVHL mutants and dominant-negative Ubc5 prevented Na-K-ATPase from degradation. The generation of reactive oxygen species was necessary for pVHL-mediated Na-K-ATPase degradation during hypoxia. Desferrioxamine, which stabilizes HIF1/2alpha, did not affect the half-life of plasma membrane Na-K-ATPase. In addition, stabilizing HIF1/2alpha by infecting mammalian cells with adenoviruses containing the oxygen-dependent degradation domain of HIF1alpha did not affect the plasma membrane Na-K-ATPase degradation. In cells with suppression of pVHL by short hairpin RNA, the Na-K-ATPase was not degraded during hypoxia, whereas cells with knockdown of HIF1/2alpha retained the ability to degrade plasma membrane Na-K-ATPase. These findings suggest that pVHL participates in the hypoxia-mediated degradation of plasma membrane Na-K-ATPase in a HIF-independent manner.
authors: Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, 240 E. Huron, Chicago, IL 60611, USA.
authors: Guofei
authors: G
authors: Zhou
authors: Laura A
authors: LA
authors: Dada
authors: Navdeep S
authors: NS
authors: Chandel
authors: Kazuhiro
authors: K
authors: Iwai
authors: Emilia
authors: E
authors: Lecuona
authors: Aaron
authors: A
authors: Ciechanover
authors: Jacob I
authors: JI
authors: Sznajder
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology; D019556:COS Cells; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003676:Deferoxamine / Q000494:pharmacology; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology; D009942:Organometallic Compounds / Q000494:pharmacology; D012459:Salicylates / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000502:physiology*; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D003676:Deferoxamine; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009942:Organometallic Compounds; D012459:Salicylates; D000254:Sodium-Potassium-Exchanging ATPase; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D000099162:Endothelial PAS Domain-Containing Protein 1; C433928:EUK-134; C497442:HIF1A protein, human