title: 4-Hydroxynonenal induces Nrf2-mediated UCP3 upregulation in mouse cardiomyocytes.
abstract: 4-Hydroxy-2-nonenal (HNE) is a highly cytotoxic product of lipid peroxidation. Nevertheless, at low concentrations, it is able to mediate cell signaling and to activate protective pathways, including that of the transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2). In addition, HNE activates uncoupling proteins (UCPs), mitochondrial inner membrane proteins that mediate uncoupling of oxidative phosphorylation and have been proposed to protect against oxidative stress. It is not known, however, whether HNE might induce UCP expression via Nrf2 to cause mitochondrial uncoupling. We investigated the effects of HNE on UCP3 expression in mouse cardiomyocytes and the involvement of Nrf2. HNE induced the nuclear accumulation of Nrf2 and enhanced UCP3 expression, effects prevented by the antioxidant N-acetylcysteine. ChIP assays indicated that Nrf2 bound to the Ucp3 promoter after HNE treatment, increasing its expression. Cardiomyocytes treated with Nrf2- or UCP3-specific siRNA were less tolerant to HNE as reflected by increased cell death, and Nrf2 siRNA prevented HNE-induced UCP3 upregulation. The treatment with HNE greatly altered cardiomyocyte bioenergetics, increasing the proton leak across the inner mitochondrial membrane and severely decreasing the maximal respiratory capacity and the respiratory reserve capacity. These findings confirm that low HNE doses activate Nrf2 in cardiomyocytes and provide the first evidence of Nrf2 binding to the Ucp3 promoter in response to HNE, leading to increased protein expression. These results suggest that the upregulation of UCP3 mediated by Nrf2 in response to HNE might be important in the protection of the heart under conditions of oxidative stress such as ischemia-reperfusion.
authors.affiliation: Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; Instituto de Investigación Sanitaria Princesa (IIS-IP), 28006 Madrid, Spain.
authors.forename: Elia
authors.initials: E
authors.lastname: López-Bernardo
authors.affiliation: Instituto de Investigación Sanitaria Princesa (IIS-IP), 28006 Madrid, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Anedda
authors.affiliation: Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Sánchez-Pérez
authors.affiliation: Instituto de Investigación Sanitaria Princesa (IIS-IP), 28006 Madrid, Spain.
authors.forename: Bárbara
authors.initials: B
authors.lastname: Acosta-Iborra
authors.affiliation: Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid, Spain; Instituto de Investigación Sanitaria Princesa (IIS-IP), 28006 Madrid, Spain. Electronic address: scadenas@cbm.csic.es.
authors.forename: Susana
authors.initials: S
authors.lastname: Cadenas
mesh_terms: D000447:Aldehydes / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D004734:Energy Metabolism / Q000502:physiology; D005434:Flow Cytometry; D015151:Immunoblotting; D007473:Ion Channels / Q000096:biosynthesis*; D051379:Mice; D024101:Mitochondrial Proteins / Q000096:biosynthesis*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D034741:RNA, Small Interfering; D060888:Real-Time Polymerase Chain Reaction; D014162:Transfection; D000071247:Uncoupling Protein 3; D015854:Up-Regulation
chemical_list: D000447:Aldehydes; D007473:Ion Channels; D024101:Mitochondrial Proteins; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D034741:RNA, Small Interfering; C000604393:Ucp3 protein, mouse; D000071247:Uncoupling Protein 3; C027576:4-hydroxy-2-nonenal
keywords: 4-Hydroxy-2-nonenal; Free radicals; Nrf2; Nuclear factor erythroid 2-related factor 2; Oxidative stress; Oxygen consumption; Respiration; Uncoupling protein 3