title: Peroxisome proliferator-activated receptor γ and C/EBPα synergistically activate key metabolic adipocyte genes by assisted loading.
abstract: Peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) are key activators of adipogenesis. They mutually induce the expression of each other and have been reported to cooperate in activation of a few adipocyte genes. Recently, genome-wide profiling revealed a high degree of overlap between PPARγ and C/EBPα binding in adipocytes, suggesting that cooperativeness could be mediated through common binding sites. To directly investigate the interplay between PPARγ and C/EBPα at shared binding sites, we established a fibroblastic model system in which PPARγ and C/EBPα can be independently expressed. Using RNA sequencing, we demonstrate that coexpression of PPARγ and C/EBPα leads to synergistic activation of many key metabolic adipocyte genes. This is associated with extensive C/EBPα-mediated reprogramming of PPARγ binding and vice versa in the vicinity of these genes, as determined by chromatin immunoprecipitation combined with deep sequencing. Our results indicate that this is at least partly mediated by assisted loading involving chromatin remodeling directed by the leading factor. In conclusion, we report a novel mechanism by which the key adipogenic transcription factors, PPARγ and C/EBPα, cooperate in activation of the adipocyte gene program.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.
authors.forename: Maria Stahl
authors.initials: MS
authors.lastname: Madsen
authors.forename: Rasmus
authors.initials: R
authors.lastname: Siersbæk
authors.forename: Michael
authors.initials: M
authors.lastname: Boergesen
authors.forename: Ronni
authors.initials: R
authors.lastname: Nielsen
authors.forename: Susanne
authors.initials: S
authors.lastname: Mandrup
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D051379:Mice; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D002843:Chromatin; D047495:PPAR gamma