title: UCP4 is a target effector of the NF-κB c-Rel prosurvival pathway against oxidative stress.
abstract: Mitochondrial uncoupling protein-4 (UCP4) enhances neuronal survival in 1-methyl-4-phenylpyridinium (MPP(+)) toxicity by suppressing oxidative stress and preserving intracellular ATP and mitochondrial membrane potential (MMP). NF-κB regulates neuronal viability via its complexes, p65 mediating cell death and c-Rel promoting cell survival. We reported previously that NF-κB mediates UCP4 neuroprotection against MPP(+) toxicity. Here, we investigated its link with the NF-κB c-Rel prosurvival pathway in alleviating mitochondrial dysfunction and oxidative stress. We overexpressed a c-Rel-encoding plasmid in SH-SY5Y cells and showed that c-Rel overexpression induced NF-κB activity without affecting p65 level. Overexpression of c-Rel increased UCP4 promoter activity and protein expression. Electrophoretic mobility shift assay showed that H(2)O(2) increased NF-κB binding to the UCP4 promoter and that NF-κB complexes were composed of p50/p50 and p50/c-Rel dimers. Under H(2)O(2)-induced oxidative stress, UCP4 knockdown significantly increased superoxide levels, decreased reduced glutathione (GSH) levels, and increased oxidized glutathione levels, compared to controls. UCP4 expression induced by c-Rel overexpression significantly decreased superoxide levels and preserved GSH levels and MMP under similar stress. These protective effects of c-Rel overexpression in H(2)O(2)-induced oxidative stress were significantly reduced after UCP4 knockdown, indicating that UCP4 is a target effector gene of the NF-κB c-Rel prosurvival pathway to mitigate the effects of oxidative stress.
authors.affiliation: Division of Neurology, University Department of Medicine, University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Jessica Wing-Man
authors.initials: JW
authors.lastname: Ho
authors.forename: Philip Wing-Lok
authors.initials: PW
authors.lastname: Ho
authors.forename: Hui-Fang
authors.initials: HF
authors.lastname: Liu
authors.forename: Danny Hon-Fai
authors.initials: DH
authors.lastname: So
authors.forename: Koon-Ho
authors.initials: KH
authors.lastname: Chan
authors.forename: Zero Ho-Man
authors.initials: ZH
authors.lastname: Tse
authors.forename: Michelle Hiu-Wai
authors.initials: MH
authors.lastname: Kung
authors.forename: David Boyer
authors.initials: DB
authors.lastname: Ramsden
authors.forename: Shu-Leong
authors.initials: SL
authors.lastname: Ho
mesh_terms: D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D015870:Gene Expression; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D000071245:Mitochondrial Uncoupling Proteins; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020569:Proto-Oncogene Proteins c-rel; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013481:Superoxides / Q000037:antagonists & inhibitors / Q000378:metabolism; D051996:Transcription Factor RelA / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D026901:Membrane Transport Proteins; D000071245:Mitochondrial Uncoupling Proteins; D009687:Nuclear Proteins; D020569:Proto-Oncogene Proteins c-rel; C068059:REL protein, human; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; C117577:SLC25A27 protein, human; D051996:Transcription Factor RelA; D013481:Superoxides; D006861:Hydrogen Peroxide