PPARγ lipodystrophy mutants reveal intermolecular interactions required for enhancer activation

The peroxisome proliferator-activated receptor γ (PPARγ) is the master regulator of adipocyte differentiation, and mutations that interfere with PPARγ function cause lipodystrophy. Structural studies indicate that PPARγ domains engage in several intra- and inter-moleuclar interactions; however, how these interactions modulate the ability of PPARγ to activate target genes in a cellular context is currently poorly understood. Here we analysed the transcriptional potential of R212Q and E379K two previously uncharacterised lipodystrophy-associated PPARγ mutants that are located in distinct PPARγ domains but are both predicted to affect intermolecular interactions. Using a combination of biochemical and genome-wide approaches we show that these mutations impair binding to an overlapping subset of enhancers that are less accessible and specifically require PPARγ for chromatin remodeling. Based on these findings we propose a model in which recruitment of PPARγ to chromatin is determined by several intermolecular interfaces. Furthermore, our data exemplify that relatively subtle molecular defects in transcription factors are sufficient to significantly affect enhancer binding and thereby transcriptional output.