SATB1 prevents immune cell infiltration by regulating chromatin organization and gene expression of a chemokine gene cluster in T cells.

SATB1, a key regulator of T cell development, governs lineage-specific transcriptional programs upon T cell activation. The absence of SATB1 has been linked to the initiation and progression of autoimmunity. However, its precise roles in this process remain incompletely understood. Here we show that conditional knockout of Satb1 in CD4 T cells in mice led to T cell hyperactivation and inflammatory cell infiltration across multiple organs. Transcriptional profiling on activated T cells revealed that the loss of SATB1 led to aberrant upregulation of CC chemokines. Treating Satb1 conditional knockout mice with CC chemokine receptor inhibitor alleviated inflammatory cell infiltration. Intriguingly, SATB1's transcriptional regulation of chemokine genes could not be attributed to its direct binding to chemokine promoters. Instead, SATB1 exerted its regulatory effects by controlling higher-order chromatin organization at a CC chemokine locus. The loss of SATB1 led to the emergence of a new chromatin domain encompassing the Ccl3, Ccl4, Ccl5, Ccl6, and Ccl9 genes and a distal enhancer, resulting in increased contacts between the enhancer and all five chemokine genes, thus inducing their upregulation. Collectively, these results demonstrate that SATB1 protects organs from immune cell infiltration by regulating chemokine expression, providing valuable insights into the development of autoimmunity-related phenotypes.