title: Minimal oxidative load: a prerequisite for thyroid cell function.
abstract: In addition to reactive oxygen species (ROS) produced by mitochondria during aerobic respiration, thyrocytes are continuously producing H(2)O(2), a key element for hormonogenesis. Because nothing is known about ROS implication in normal non-stimulated cells, we studied their possible involvement in thyrocytes incubated with a potent antioxidant, N-acetylcysteine (NAC). NAC, which blocked the production of intracellular ROS, also decreased dual oxidases, thyroperoxidase, pendrin, and thyroglobulin protein and/or gene expression. By contrast, Na(+)/I(-) symporter mRNA expression was unaffected. Among antioxidant systems, peroxiredoxin (PRDX) five expression was reduced by NAC, whereas peroxiredoxin three increased and catalase remained unchanged. In vivo, the expression of both dual oxidases and peroxiredoxin five proteins was also decreased by NAC. In conclusion, when intracellular ROS levels drop below a basal threshold, the expression of proteins involved in thyroid cell function is hampered. This suggests that keeping ROS at a minimal level is required for safeguarding thyrocyte function.
authors.affiliation: Unité de Morphologie Expérimentale, Université Catholique de Louvain, UCL-5251, Bruxelles, Belgium.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Poncin
authors.forename: Ides M
authors.initials: IM
authors.lastname: Colin
authors.forename: Anne-Catherine
authors.initials: AC
authors.lastname: Gérard
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D000074623:Dual Oxidases; D006801:Humans; D051379:Mice; D019255:NADPH Oxidases / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D054464:Peroxiredoxins / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D000074623:Dual Oxidases; D054464:Peroxiredoxins; C515975:Prdx5 protein, mouse; D019255:NADPH Oxidases; C519130:Duox1 protein, mouse; D000111:Acetylcysteine