title: Differential role of PPAR gamma in the regulation of UCP-1 and adipogenesis by TNF-alpha in brown adipocytes.
abstract: Extracellular regulated kinases (ERKs) mediate the inhibitory effect of tumor necrosis factor alpha (TNF-alpha) on uncoupling protein-1 (UCP-1), but not on lipid accumulation. TNF-alpha-induced ERK-dependent peroxisome proliferator activator receptor gamma (PPAR gamma) phosphorylation could be responsible for UCP-1 downregulation. Thus, the negative effect of TNF-alpha on UCP-1 mRNA expression at 4-5 h, under basal conditions or in cells treated with the PPAR gamma agonist, rosiglitazone, was reversed by the MEK1 inhibitor PD98059. In contrast, fatty acid synthase and malic enzyme mRNA downregulation was not prevented. Moreover, rosiglitazone has no positive effect on adipogenic gene expression or lipid accumulation. Therefore, there is a differential regulation of thermogenic and adipogenic differentiation by PPAR gamma, which might account for the differences in the TNF-alpha regulation through ERKs.
authors.affiliation: Departamento de Bioquímica y Biología Molecular II, Instituto de Bioquímica, Centro Mixto del Consejo Superior de Investigaciones Científicas y de la Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid, Spain. maporras@farm.ucm.es
authors.forename: Almudena
authors.initials: A
authors.lastname: Porras
authors.forename: Amparo
authors.initials: A
authors.lastname: Valladares
authors.forename: Alberto M
authors.initials: AM
authors.lastname: Alvarez
authors.forename: Cesar
authors.initials: C
authors.lastname: Roncero
authors.forename: Manuel
authors.initials: M
authors.lastname: Benito
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002001:Adipose Tissue, Brown / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D005419:Flavonoids / Q000494:pharmacology; D007473:Ion Channels; D050356:Lipid Metabolism; D008565:Membrane Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D024101:Mitochondrial Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism / Q000502:physiology*; D022722:Thermogenesis / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000071256:Uncoupling Protein 1
chemical_list: D002352:Carrier Proteins; D005419:Flavonoids; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C000604372:Ucp1 protein, mouse; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one