Enhancer-bound LDB1 regulates a corticotrope promoter-pausing repression program

F Zhang, B Tanasa, D Merkurjev… - Proceedings of the …, 2015 - National Acad Sciences
F Zhang, B Tanasa, D Merkurjev, C Lin, X Song, W Li, Y Tan, Z Liu, J Zhang, KA Ohgi…
Proceedings of the National Academy of Sciences, 2015National Acad Sciences
Substantial evidence supports the hypothesis that enhancers are critical regulators of cell-
type determination, orchestrating both positive and negative transcriptional programs;
however, the basic mechanisms by which enhancers orchestrate interactions with cognate
promoters during activation and repression events remain incompletely understood. Here
we report the required actions of LIM domain-binding protein 1 (LDB1)/cofactor of LIM
homeodomain protein 2/nuclear LIM interactor, interacting with the enhancer-binding protein …
Substantial evidence supports the hypothesis that enhancers are critical regulators of cell-type determination, orchestrating both positive and negative transcriptional programs; however, the basic mechanisms by which enhancers orchestrate interactions with cognate promoters during activation and repression events remain incompletely understood. Here we report the required actions of LIM domain-binding protein 1 (LDB1)/cofactor of LIM homeodomain protein 2/nuclear LIM interactor, interacting with the enhancer-binding protein achaete-scute complex homolog 1, to mediate looping to target gene promoters and target gene regulation in corticotrope cells. LDB1-mediated enhancer:promoter looping appears to be required for both activation and repression of these target genes. Although LDB1-dependent activated genes are regulated at the level of transcriptional initiation, the LDB1-dependent repressed transcription units appear to be regulated primarily at the level of promoter pausing, with LDB1 regulating recruitment of metastasis-associated 1 family, member 2, a component of the nucleosome remodeling deacetylase complex, on these negative enhancers, required for the repressive enhancer function. These results indicate that LDB1-dependent looping events can deliver repressive cargo to cognate promoters to mediate promoter pausing events in a pituitary cell type.
National Acad Sciences