The 3D enhancer network of the developing T cell genome is controlled by SATB1 [RNA-seq]

Mechanisms of tissue-specific gene expression regulation, particularly via spatial coordination of gene promoters and their regulatory elements are poorly understood. Here we investigated the 3D genome organization of developing murine T cells. We identified a tissue-specific genome organizer SATB1 as a factor enriched at the anchors of promoter-enhancer chromatin loops. To unravel its functions in T cells, we generated Satb1fl/flCd4-Cre+ (Satb1 cKO) conditional knockout animals. Satb1 cKO animals suffer from severe autoimmunity so we sought to investigate a potential link between the autoimmunity and putatively deregulated nuclear architecture caused by SATB1 depletion. This series of RNA-Seq experiments is a part of SuperSeries including also ATAC-Seq, Hi-C and HiChIP experiments to fully understand the deregulation of Satb1 cKO thymocytes and to unravel the roles of SATB1 in T cell chromatin organization. RNA-Seq experiments supported the repressive nature of Satb1 cKO nuclear environment and together with the other datasets it showed that SATB1 functions primarily as an activator. SATB1 mediates promoter-enhancer chromatin loops affecting a number of master regulator genes whose deregulation in knockout animals may comprise a cell-intrinsic mechanism of the autoimmunity. Our findings indicate a possible existence of a special class of genome organizers controlling tissue and/or time-specific transcriptional programs via spatial chromatin arrangements that are complementary to the function of conventional and ubiquitously expressed genome organizers. Three biological replicates from each wild type and conditional knockout Satb1fl/flCd4-Cre+ mice were analyzed. Total RNA was isolated from thymocytes and depleted from ribosomal RNA. Strand-specific total RNA libraries were created and sequenced.