title: NADPH oxidase-mitochondria axis-derived ROS mediate arsenite-induced HIF-1α stabilization by inhibiting prolyl hydroxylases activity.
abstract: Arsenic exposure has been shown to induce hypoxia inducible factor 1α (HIF-1α) accumulation, however the underlying mechanism remains unknown. In the present study, we tested the hypothesis that arsenic exposure triggered the interaction between NADPH oxidase and mitochondria to promote reactive oxygen species (ROS) production, which inactivate prolyl hydroxylases (PHDs) activity, leading to the stabilization of HIF-1α protein. Exposure of human immortalized liver cell line HL-7702 cells to arsenite induced HIF-1α accumulation in a dose-dependent manner, which was abolished by SOD mimetic MnTMPyP. Inhibition of NADPH oxidase with diphenyleneiodonium chloride (DPI) or inhibition of mitochondrial respiratory chain with rotenone significantly blocked arsenite-induced ROS production, and the mitochondria appeared to be the major source of ROS production. Arsenite treatment inhibited HIF-1α hydroxylation by prolyl hydroxylases (PHDs) and increased HIF-1α stabilization, but did not affect HIF-1α mRNA expression and Akt activation. Supplementation of ascorbate or Fe(II) completely abolished arsenite-induced PHDs inhibition and HIF-1α stabilization. In conclusion, these results define a unique mechanism of HIF-1α accumulation following arsenic exposure, that is, arsenic activates NADPH oxidase-mitochondria axis to produce ROS, which deplete intracellular ascorbate and Fe(II) to inactivate PHDs, leading to HIF-1α stabilization.
authors.affiliation: Department of Geriatrics, The Second Affiliated Hospital of Medicine School, The Xi'an Jiaotong University, Xi'an 710004, China.
authors.forename: Ying-Na
authors.initials: YN
authors.lastname: Li
authors.forename: Miao-Miao
authors.initials: MM
authors.lastname: Xi
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.forename: Chun-Xu
authors.initials: CX
authors.lastname: Hai
authors.forename: Wei-Lin
authors.initials: WL
authors.lastname: Yang
authors.forename: Xu-Jun
authors.initials: XJ
authors.lastname: Qin
mesh_terms: D018053:Arsenites / Q000633:toxicity*; D002478:Cells, Cultured; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000737:chemistry / Q000378:metabolism*; D008928:Mitochondria / Q000502:physiology*; D019255:NADPH Oxidases / Q000502:physiology*; D064800:Prolyl-Hydroxylase Inhibitors / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D018053:Arsenites; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D064800:Prolyl-Hydroxylase Inhibitors; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; C015001:arsenite
keywords: 2′,7′-dichlorofluorescein-diacetate; Arsenic; DCFH-DA; DHE; DPI; HIF-1α; Mitochondria; NADPH oxidase; O(2)(−); PHDs; Prolyl hydroxylases (PHDs); ROS; Reactive oxygen species (ROS); VEGF; VHL; dihydroethidium; diphenyleneiodonium chloride; hypoxia inducible factor 1α; prolyl hydroxylases; reactive oxygen species; superoxide anion radical; vascular endothelial growth factor; von Hippel Lindau