title: Induction of the Nrf2-driven antioxidant response confers neuroprotection during mitochondrial stress in vivo.
abstract: NF-E2 related factor (Nrf2) controls a pleiotropic cellular defense, where multiple antioxidant/detoxification pathways are up-regulated in unison. Although small molecule inducers of Nrf2 activity have been reported to protect neurons in vitro, whether similar pathways can be accessed in vivo is not known. We have investigated whether in vivo toxicity of the mitochondrial complex II inhibitor 3-nitropropionic acid (3-NP) can be attenuated by constitutive and inducible Nrf2 activity. The absence of Nrf2 function in Nrf2(-/-) mice resulted in 3-NP hypersensitivity that became apparent with time and increasing dose, causing motor deficits and striatal lesions on a more rapid time scale than identically treated Nrf2(+/+) and Nrf2(+/-) controls. Striatal succinate dehydrogenase activity, the target of 3-NP, was inhibited to the same extent in all genotypes by a single acute dose of 3-NP, suggesting that brain concentrations of 3-NP were similar. Dietary supplementation with the Nrf2 inducer tert-butylhydroquinone attenuated 3-NP toxicity in Nrf2(+/-) mice, but not Nrf2(-/-), confirming the Nrf2-specific action of the inducer in vivo. Increased Nrf2 activity alone was sufficient to protect animals from 3-NP toxicity because intrastriatal adenovirus-mediated Nrf2 overexpression significantly reduced lesion size compared with green fluorescent protein overexpressing controls. In cultured astrocytes, 3-NP was found to increase Nrf2 activity leading to antioxidant response element-dependent gene expression providing a potential mechanism for the increased sensitivity of Nrf2(-/-) animals to 3-NP toxicity in vivo. We conclude that Nrf2 may underlie a feedback system limiting oxidative load during chronic metabolic stress.
authors.affiliation: Kinsmen Laboratory, Department of Psychiatry, Brain Research Center, Vancouver, Canada.
authors.forename: Andy Y
authors.initials: AY
authors.lastname: Shih
authors.forename: Sophie
authors.initials: S
authors.lastname: Imbeault
authors.forename: Vilte
authors.initials: V
authors.lastname: Barakauskas
authors.forename: Heidi
authors.initials: H
authors.lastname: Erb
authors.forename: Lei
authors.initials: L
authors.lastname: Jiang
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Murphy
mesh_terms: D000256:Adenoviridae / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D001253:Astrocytes / Q000378:metabolism; D001522:Behavior, Animal; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D005838:Genotype; D005978:Glutathione / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006873:Hydroquinones / Q000494:pharmacology; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism*; D051267:NF-E2-Related Factor 2; D009457:Neuroglia / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D009574:Nitro Compounds; D018384:Oxidative Stress; D010920:Placenta / Q000201:enzymology; D010957:Plasmids / Q000378:metabolism; D011422:Propionates / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013997:Time Factors; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014162:Transfection; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D017931:DNA Primers; D004268:DNA-Binding Proteins; D006873:Hydroquinones; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; C495637:Nfe2l2 protein, rat; D009574:Nitro Compounds; D011422:Propionates; D015534:Trans-Activators; D049452:Green Fluorescent Proteins; C018855:2-tert-butylhydroquinone; D013385:Succinate Dehydrogenase; D000469:Alkaline Phosphatase; D005978:Glutathione; C015392:3-nitropropionic acid