title: Cyclin D3 promotes adipogenesis through activation of peroxisome proliferator-activated receptor gamma.
abstract: In addition to their role in cell cycle progression, new data reveal an emerging role of D-type cyclins in transcriptional regulation and cellular differentiation processes. Using 3T3-L1 cell lines to study adipogenesis, we observed an up-regulation of cyclin D3 expression throughout the differentiation process. Surprisingly, cyclin D3 was only minimally expressed during the initial stages of adipogenesis, when mitotic division is prevalent. This seemingly paradoxical expression led us to investigate a potential cell cycle-independent role for cyclin D3 during adipogenesis. We show here a direct interaction between cyclin D3 and the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma). Our experiments reveal cyclin D3 acts as a ligand-dependent PPARgamma coactivator, which, together with its cyclin-dependent kinase partner, phosphorylates the A-B domain of the nuclear receptor. Overexpression and knockdown studies with cyclin D3 had marked effects on PPARgamma activity and subsequently on adipogenesis. Chromatin immunoprecipitation assays confirm the participation of cyclin D3 in the regulation of PPARgamma target genes. We show that cyclin D3 mutant mice are protected from diet-induced obesity, display smaller adipocytes, have reduced adipogenic gene expression, and are insulin sensitive. Our results indicate that cyclin D3 is an important factor governing adipogenesis and obesity.
authors.affiliation: INSERM, Equipe Avenir, U540, 60, rue de Navacelles, F34090 Montpellier, France.
authors.forename: David A
authors.initials: DA
authors.lastname: Sarruf
authors.forename: Irena
authors.initials: I
authors.lastname: Iankova
authors.forename: Anna
authors.initials: A
authors.lastname: Abella
authors.forename: Said
authors.initials: S
authors.lastname: Assou
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Miard
authors.forename: Lluis
authors.initials: L
authors.lastname: Fajas
mesh_terms: D017667:Adipocytes / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D001391:Azo Compounds / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D047369:Chromatin Immunoprecipitation; D056743:Cyclin D3; D051361:Cyclin-Dependent Kinase 6 / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism / Q000502:physiology*; D004032:Diet; D005786:Gene Expression Regulation; D047468:Immunoprecipitation; D007328:Insulin / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D009154:Mutation; D041681:NIH 3T3 Cells; D009765:Obesity / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic; D015854:Up-Regulation
chemical_list: D001391:Azo Compounds; C534697:Ccnd3 protein, mouse; D056743:Cyclin D3; D016213:Cyclins; D007328:Insulin; D047495:PPAR gamma; D034741:RNA, Small Interfering; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases; C011049:oil red O