title: Acute genome-wide effects of rosiglitazone on PPARγ transcriptional networks in adipocytes.
abstract: Peroxisome proliferator-activated receptor γ (PPARγ) is a master regulator of adipocyte differentiation, and genome-wide studies indicate that it is involved in the induction of most adipocyte genes. Here we report, for the first time, the acute effects of the synthetic PPARγ agonist rosiglitazone on the transcriptional network of PPARγ in adipocytes. Treatment with rosiglitazone for 1 hour leads to acute transcriptional activation as well as repression of a number of genes as determined by genome-wide RNA polymerase II occupancy. Unlike what has been shown for many other nuclear receptors, agonist treatment does not lead to major changes in the occurrence of PPARγ binding sites. However, rosiglitazone promotes PPARγ occupancy at many preexisting sites, and this is paralleled by increased occupancy of the mediator subunit MED1. The increase in PPARγ and MED1 binding is correlated with an increase in transcription of nearby genes, indicating that rosiglitazone, in addition to activating the receptor, also promotes its association with DNA, and that this is causally linked to recruitment of mediator and activation of genes. Notably, both rosiglitazone-activated and -repressed genes are induced during adipogenesis. However, rosiglitazone-activated genes are markedly more associated with PPARγ than repressed genes and are highly dependent on PPARγ for expression in adipocytes. By contrast, repressed genes are associated with the other key adipocyte transcription factor CCAAT-enhancer binding proteinα (C/EBPα), and their expression is more dependent on C/EBPα. This suggests that the relative occupancies of PPARγ and C/EBPα are critical for whether genes will be induced or repressed by PPARγ agonist.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark. s.mandrup@bmb.sdu.dk
authors.forename: Anders Kristian
authors.initials: AK
authors.lastname: Haakonsson
authors.forename: Maria
authors.initials: M
authors.lastname: Stahl Madsen
authors.forename: Ronni
authors.initials: R
authors.lastname: Nielsen
authors.forename: Albin
authors.initials: A
authors.lastname: Sandelin
authors.forename: Susanne
authors.initials: S
authors.lastname: Mandrup
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism; D053263:Gene Regulatory Networks / Q000187:drug effects*; D016678:Genome / Q000235:genetics*; D056913:Mediator Complex Subunit 1 / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D047495:PPAR gamma / Q000235:genetics* / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; C538856:Med1 protein, mouse; D056913:Mediator Complex Subunit 1; D008565:Membrane Proteins; D047495:PPAR gamma; C498709:Pag1 protein, mouse; D010750:Phosphoproteins; D045162:Thiazolidinediones; D000077154:Rosiglitazone