title: Regulation of peroxisome proliferator-activated receptor-alpha by MDM2.
abstract: Peroxisome proliferator-activated receptor-alpha (PPARalpha) belongs to the nuclear receptor (NR) family of transcription factors and regulates lipid and glucose metabolism. Like other NRs, the regulation of gene expression by PPARalpha depends on cofactor recruitment to the transcription complex and multiple protein-protein interactions. In this study, Murine Double Minute 2 (MDM2), an E3 ubiquitin ligase, is identified as a PPARalpha-interacting protein that regulates PPARalpha transcriptional activity. MDM2 modulated the transcriptional activity of PPARalpha and PPARbeta/delta, but not PPARgamma in reporter assays. Knockdown of MDM2 by small interfering RNA in rat hepatoma cells inhibited ligand-induced mRNA levels of several PPARalpha target genes involved in lipid metabolism. MDM2 associated with PPARalpha on target gene promoters, and this association increased in response to Wy14,643 treatment. MDM2 interacted with PPARalpha and this interaction occurred with the A/B domain of PPARalpha. Coexpression of MDM2 increased PPARalpha ubiquitination and the E3 ubiquitin ligase activity of MDM2 affected PPARalpha protein expression and transcriptional activity. MDM2 expression was decreased in response to clofibrate in wild-type (WT), but not in PPARalpha null mice, indicating a PPARalpha-dependent regulation. These studies identify a role for MDM2 in regulating PPARalpha-mediated pathways of lipid metabolism.
authors.affiliation: The Huck Institutes of the Life Sciences, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Gopinathan
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Hannon
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Peters
authors.forename: John P
authors.initials: JP
authors.lastname: Vanden Heuvel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D055785:Gene Knockdown Techniques; D006801:Humans; D050356:Lipid Metabolism / Q000235:genetics; D008099:Liver / Q000737:chemistry / Q000201:enzymology; D008297:Male; D051379:Mice; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism*; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics
chemical_list: D047493:PPAR alpha; D047492:Peroxisome Proliferator-Activated Receptors; D011743:Pyrimidines; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C006253:pirinixic acid; D051736:Proto-Oncogene Proteins c-mdm2