Promoter-enhancer looping at the PPAR gamma 2 locus during adipogenic differentiation requires the Prmt5 methyltransferase

作者：LeBlanc Scott E; Wu Qiong; Lamba Pallavi; Sif Said; Imbalzano Anthony N

来源：Nucleic Acids Research, 2016, 44(11): 5133-5147.

DOI：10.1093/nar/gkw129

PPAR gamma 2 is a critical lineage-determining transcription factor that is essential for adipogenic differentiation. Here we report characterization of the three-dimensional structure of the PPAR gamma 2 locus after the onset of adipogenic differentiation and the mechanisms by which it forms. We identified a differentiation-dependent loop between the PPAR gamma 2 promoter and an enhancer sequence 10 kb upstream that forms at the onset of PPAR gamma 2 expression. The arginine methyltransferase Prmt5 was required for loop formation, and overexpression of Prmt5 resulted in premature loop formation and earlier onset of PPAR gamma 2 expression. Kinetic studies of regulatory factor interactions at the PPAR gamma 2 promoter and enhancer revealed enhanced interaction of Prmt5 with the promoter that preceded stable association of Prmt5 with enhancer sequences. Prmt5 knockdown prevented binding of both MED1, a subunit of Mediator complex that facilitates enhancer-promoter interactions, and Brg1, the ATPase of the mammalian SWI/SNF chromatin remodeling enzyme required for PPAR gamma 2 activation and adipogenic differentiation. The data indicate a dynamic association of Prmt5 with the regulatory sequences of the PPAR gamma 2 gene that facilitates differentiation-dependent, three-dimensional organization of the locus. In addition, other differentiation-specific, long-range chromatin interactions showed Prmt5-dependence, indicating a more general role for Prmt5 in mediating higher-order chromatin connections in differentiating adipocytes.

• 出版日期2016-6-20