title: Ligand binding reduces SUMOylation of the peroxisome proliferator-activated receptor γ (PPARγ) activation function 1 (AF1) domain.
abstract: Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated nuclear receptor regulating adipogenesis, glucose homeostasis and inflammatory responses. The activity of PPARγ is controlled by post-translational modifications including SUMOylation and phosphorylation that affects its biological and molecular functions. Several important aspects of PPARγ SUMOylation including SUMO isoform-specificity and the impact of ligand binding on SUMOylation remain unresolved or contradictory. Here, we present a comprehensive study of PPARγ1 SUMOylation. We show that PPARγ1 can be modified by SUMO1 and SUMO2. Mutational analyses revealed that SUMOylation occurs exclusively within the N-terminal activation function 1 (AF1) domain predominantly at lysines 33 and 77. Ligand binding to the C-terminal ligand-binding domain (LBD) of PPARγ1 reduces SUMOylation of lysine 33 but not of lysine 77. SUMOylation of lysine 33 and lysine 77 represses basal and ligand-induced activation by PPARγ1. We further show that lysine 365 within the LBD is not a target for SUMOylation as suggested in a previous report, but it is essential for full LBD activity. Our results suggest that PPARγ ligands negatively affect SUMOylation by interdomain communication between the C-terminal LBD and the N-terminal AF1 domain. The ability of the LBD to regulate the AF1 domain may have important implications for the evaluation and mechanism of action of therapeutic ligands that bind PPARγ.
authors.affiliation: Institute of Molecular Biology and Tumor Research, Philipps-University Marburg, Marburg, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Diezko
authors.forename: Guntram
authors.initials: G
authors.lastname: Suske
mesh_terms: D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D008239:Lysine / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D047495:PPAR gamma / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism; D012694:Serine / Q000235:genetics; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D058207:Sumoylation; D014158:Transcription, Genetic
chemical_list: D008024:Ligands; D050505:Mutant Proteins; D047495:PPAR gamma; D012097:Repressor Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D012694:Serine; D008239:Lysine