title: Hypoxia-inducible factor-1 activation in nonhypoxic conditions: the essential role of mitochondrial-derived reactive oxygen species.
abstract: Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor for responses to low oxygen. Different nonhypoxic stimuli, including hormones and growth factors, are also important HIF-1 activators in the vasculature. Angiotensin II (Ang II), the main effecter hormone in the renin-angiotensin system, is a potent HIF-1 activator in vascular smooth muscle cells (VSMCs). HIF-1 activation by Ang II involves intricate mechanisms of HIF-1α transcription, translation, and protein stabilization. Additionally, the generation of reactive oxygen species (ROS) is essential for HIF-1 activation during Ang II treatment. However, the role of the different VSMC ROS generators in HIF-1 activation by Ang II remains unclear. This work aims at elucidating this question. Surprisingly, repression of NADPH oxidase-generated ROS, using Vas2870, a specific inhibitor or a p22(phox) siRNA had no significant effect on HIF-1 accumulation by Ang II. In contrast, repression of mitochondrial-generated ROS, by complex III inhibition, by Rieske Fe-S protein siRNA, or by the mitochondrial-targeted antioxidant SkQ1, strikingly blocked HIF-1 accumulation. Furthermore, inhibition of mitochondrial-generated ROS abolished HIF-1α protein stability, HIF-1-dependent transcription and VSMC migration by Ang II. A large number of studies implicate NADPH oxidase-generated ROS in Ang II-mediated signaling pathways in VSMCs. However, our work points to mitochondrial-generated ROS as essential intermediates for HIF-1 activation in nonhypoxic conditions.
authors.affiliation: Centre de recherche du CHUQ, L'Hôtel-Dieu de Québec, Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Québec, QC, G1R 2J6, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Patten
authors.forename: Véronique N
authors.initials: VN
authors.lastname: Lafleur
authors.forename: Geneviève A
authors.initials: GA
authors.lastname: Robitaille
authors.forename: Denise A
authors.initials: DA
authors.lastname: Chan
authors.forename: Amato J
authors.initials: AJ
authors.lastname: Giaccia
authors.forename: Darren E
authors.initials: DE
authors.lastname: Richard
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology; D002478:Cells, Cultured; D014450:Electron Transport Complex III / Q000235:genetics / Q000378:metabolism; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism*; D008297:Male; D008689:Methacrylates / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism; D011090:Polyenes / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D051793:Hypoxia-Inducible Factor 1; D008689:Methacrylates; D011090:Polyenes; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C037989:Rieske iron-sulfur protein; D013844:Thiazoles; D000804:Angiotensin II; C030517:myxothiazol; C041573:stigmatellin; D019255:NADPH Oxidases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D014450:Electron Transport Complex III