title: Mitochondria-derived reactive oxygen species mediate heme oxygenase-1 expression in sheared endothelial cells.
abstract: Bovine aortic endothelial cells (ECs) respond to nitric oxide (NO) donors by activating the redox-sensitive NF-E2-related factor 2/antioxidant response element pathway and up-regulating heme oxygenase (HO)-1 expression. EC exposure to steady laminar shear stress causes a sustained increase in NO, a transient increase in reactive oxygen species (ROS), and activation of the HO-1 gene. Because steady laminar flow increases the mitochondrial superoxide (O(2)(*-)) production, we hypothesized that mitochondria-derived ROS play a role in shear-induced HO-1 expression. Flow (10 dynes/cm(2), 6 h)-induced expression of HO-1 protein was abolished when BAECs were preincubated and sheared in the presence of either N(G)-nitro-L-arginine methyl ester or N-acetyl-L-cysteine, suggesting that either NO or ROS up-regulates HO-1. Ebselen and diphenylene iodonium blocked HO-1 expression, and uric acid had no effect. The mitochondrial electron transport chain inhibitors, myxothiazol, rotenone, or antimycin A, and the mitochondria-targeted antioxidant peptide, Szeto-Schiller (SS)-31, which scavenges O(2)(*-), hydrogen peroxide (H(2)O(2)), peroxynitrite, and hydroxyl radicals, markedly inhibited the increase in HO-1 expression. These data collectively suggest that mitochondrial H(2)O(2) mediates the HO-1 induction. MitoSOX and 2',7'-dichlorofluorescin (DCF) fluorescence showed that mitochondrial O(2)(*-) levels and intracellular peroxides, respectively, are higher in sheared ECs compared with static controls and, in part, dependent on NO. SS-31 significantly inhibited both the shear-induced MitoSOX and DCF fluorescence signals. Either phosphatidylinositol 3-kinase or mitogen-activated protein kinase cascade inhibitors blocked the HO-1 induction. In conclusion, under shear, EC mitochondria-derived H(2)O(2) diffuses to the cytosol, where it initiates oxidative signaling leading to HO-1 up-regulation and maintenance of the atheroprotective EC status.
authors.affiliation: Davis Heart and Lung Research Institute, Department of Biomedical Engineering, Ohio State University, Columbus, OH 43210, USA.
authors.forename: Zhaosheng
authors.initials: Z
authors.lastname: Han
authors.forename: Saradhadevi
authors.initials: S
authors.lastname: Varadharaj
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Giedt
authors.forename: Jay L
authors.initials: JL
authors.lastname: Zweier
authors.forename: Hazel H
authors.initials: HH
authors.lastname: Szeto
authors.forename: B Rita
authors.initials: BR
authors.lastname: Alevriadou
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D002417:Cattle; D004579:Electron Transport / Q000187:drug effects; D042783:Endothelial Cells / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051547:Heme Oxygenase-1 / Q000096:biosynthesis*; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D008928:Mitochondria / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D052250:Nitric Oxide Synthase Type III; D051547:Heme Oxygenase-1; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases; D019331:NG-Nitroarginine Methyl Ester; D000111:Acetylcysteine