title: Glutaredoxin-2 is required to control proton leak through uncoupling protein-3.
abstract: Glutathionylation has emerged as a key modification required for controlling protein function in response to changes in cell redox status. Recently, we showed that the glutathionylation state of uncoupling protein-3 (UCP3) modulates the leak of protons back into the mitochondrial matrix, thus controlling reactive oxygen species production. However, whether or not UCP3 glutathionylation is mediated enzymatically has remained unknown because previous work relied on the use of pharmacological agents, such as diamide, to alter the UCP3 glutathionylation state. Here, we demonstrate that glutaredoxin-2 (Grx2), a matrix oxidoreductase, is required to glutathionylate and inhibit UCP3. Analysis of bioenergetics in skeletal muscle mitochondria revealed that knock-out of Grx2 (Grx2(-/-)) increased proton leak in a UCP3-dependent manner. These effects were reversed using diamide, a glutathionylation catalyst. Importantly, the increased leak did not compromise coupled respiration. Knockdown of Grx2 augmented proton leak-dependent respiration in primary myotubes from wild type mice, an effect that was absent in UCP3(-/-) cells. These results confirm that Grx2 deactivates UCP3 by glutathionylation. To our knowledge, this is the first enzyme identified to regulate UCP3 by glutathionylation and is the first study on the role of Grx2 in the regulation of energy metabolism.
authors: Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
authors: Ryan J
authors: RJ
authors: Mailloux
authors: Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
authors: Jian Ying
authors: JY
authors: Xuan
authors: Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
authors: Brittany
authors: B
authors: Beauchamp
authors: Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
authors: Linda
authors: L
authors: Jui
authors: Center of Redox Biology and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, Nebraska 68583.
authors: Marjorie
authors: M
authors: Lou
authors: Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada. Electronic address: mharper@uottawa.ca.
authors: Mary-Ellen
authors: ME
authors: Harper
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D002952:Citric Acid Cycle; D003958:Diamide / Q000494:pharmacology; D042967:Electron Transport Complex I / Q000378:metabolism; D004734:Energy Metabolism; D054477:Glutaredoxins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007473:Ion Channels / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008930:Mitochondria, Liver / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010101:Oxygen Consumption; D061251:Primary Cell Culture; D011499:Protein Processing, Post-Translational; D011522:Protons; D017382:Reactive Oxygen Species / Q000378:metabolism; D000071247:Uncoupling Protein 3
chemical_list: C516009:Glrx2 protein, mouse; D054477:Glutaredoxins; D007473:Ion Channels; D024101:Mitochondrial Proteins; D016877:Oxidants; D011522:Protons; D017382:Reactive Oxygen Species; C000604393:Ucp3 protein, mouse; D000071247:Uncoupling Protein 3; D003958:Diamide; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D042967:Electron Transport Complex I; D005978:Glutathione