SATB1 Regulates 3D Genome Architecture in T cells by Constraining Chromatin Interactions surrounding CTCF-binding sites [RNA-seq]

Spatial genome organization is critical for precise gene regulation during development. Special AT-rich sequence binding protein 1 (SATB1) has long been proposed to act as a global chromatin loop organizer in T cells. However, the exact functions of SATB1 in genome organization remain elusive. Here we show that the depletion of SATB1 in human and murine T cells led to transcriptional dysregulation for genes involved in T cell activation, as well as alterations of 3D genome architecture at multiple scales, including the A/B compartment, topologically associating domains (TADs), and loops. Importantly, SATB1 extensively colocalizes with CTCF throughout the genome. Depletion of SATB1 led to increased chromatin contacts among and across the SATB1/CTCF co-occupied sites, thereby affecting the transcription of critical genes involved in T cell activation. The loss of SATB1 did not affect the genome-wide occupancy of CTCF, but significantly reduced the retention of CTCF in the nuclear matrix. Collectively, our data reveal that SATB1 constrains chromatin topology surrounding CTCF-binding sites by tethering CTCF to the nuclear matrix, and suggest that the functional interplay between SATB1 and CTCF contributes to 3D genome organization. Overall design: Naive CD4+ T cells were isolated from spleens of control and Satb1 flox/flox CD4-Cre mice and subsequently subjected to RNA-seq experiments.