title: Acute ethanol induces apoptosis by stimulating TRPC6 via elevation of superoxide in oxygenated podocytes.
abstract: Our recent studies indicate that hydrogen peroxide (H2O2) only at high concentrations can cause oxidative stress in renal epithelial cells and induce apoptosis of podocytes. Consistently, the present study shows that H2O2, even at 1 mM, failed to induce intracellular oxidative stress and apoptosis of the podocytes due to efficient activity of catalase, an enzyme which degrades H2O2 to produce water and oxygen (O2). However, H2O2 acted as a source of O2 to allow acute ethanol to induce superoxide production and cause apoptosis of the podocytes. In contrast, acute ethanol alone did not elevate intracellular superoxide, even though it stimulates expression and translocation of p47phox to the plasma membrane. Inhibition of catalase abolished not only O2 production from H2O2 degradation, but also NOX2-dependent superoxide production in the podocytes challenged by both H2O2 and acute ethanol. In parallel, acute ethanol in the presence of H2O2, but neither ethanol nor H2O2 alone, stimulated transient receptor potential canonical 6 (TRPC6) channels and caused TRPC6-dependent elevation of intracellular Ca2+. These data suggest that exogenous H2O2 does not induce oxidative stress due to rapid degradation to produce O2 in the podocytes, but the oxygenated podocytes become sensitive to acute ethanol challenge and undergo apoptosis via a TRPC6-dependent elevation of intracellular Ca2+. Since cultured podocytes are considered in hypoxic conditions, H2O2 may be used as a source of O2 to establish an ischemia-reperfusion model in some type of cultured cells in which H2O2 does not directly induce intracellular oxidative stress.
authors.affiliation: Department of Neurology, the Second Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China; Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States.
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Lu
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Radiology, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China; Department of Cardiology, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Bing-Chen
authors.initials: BC
authors.lastname: Liu
authors.affiliation: Department of Neurology, the Second Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Wang
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Radiology, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China; Department of Cardiology, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Yang
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States.
authors.forename: Qing
authors.initials: Q
authors.lastname: Bao
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Radiology, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China; Department of Cardiology, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Yu-Jia
authors.initials: YJ
authors.lastname: Zhai
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States.
authors.forename: Abdel A
authors.initials: AA
authors.lastname: Alli
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States.
authors.forename: Tiffany L
authors.initials: TL
authors.lastname: Thai
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States.
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Eaton
authors.affiliation: Department of Neurology, the Second Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Wei-Zhi
authors.initials: WZ
authors.lastname: Wang
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, United States. Electronic address: heping.ma@emory.edu.
authors.forename: He-Ping
authors.initials: HP
authors.lastname: Ma
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002374:Catalase / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D009285:Naphthoquinones / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010100:Oxygen / Q000494:pharmacology*; D050199:Podocytes / Q000187:drug effects / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism*; D050052:TRPC Cation Channels / Q000378:metabolism*; D000074287:TRPC6 Cation Channel
chemical_list: D008562:Membrane Glycoproteins; D009285:Naphthoquinones; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; D013481:Superoxides; D000431:Ethanol; C063002:2,3-dimethoxy-1,4-naphthoquinone; D006861:Hydrogen Peroxide; D002374:Catalase; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D010100:Oxygen
keywords: Catalase; Confocal microscopy; Intracellular Ca(2+); NOX2; Oxidative stress; Patch-clamp technique