The role of chromatin organizer Satb1 in shaping TCR repertoire in adult thymus.

T cells recognize the universe of foreign antigens with a diverse repertoire of T cell receptors generated by V(D)J recombination. Special AT-rich binding protein 1 (Satb1) is a chromatin organizer that plays an essential role in T cell development. Previous study has shown that Satb1 regulates the re-induction of recombinase Rag1 and Rag2 in CD4CD8 thymocytes, affecting the secondary rearrangement of the gene. Here, we detected the repertoires of four TCR genes, , , , and , in the adult thymus, and explored the role of the Satb1 in shaping the TCR repertoires. We observed a strong bias in the V and J gene usages of the and repertoires in WT and Satb1-deleted thymocytes. Satb1 deletion had few effects on the V(D)J rearrangement and repertoire of the , , and genes. The repertoire was severely impaired in Satb1-deleted thymocytes, while the primary rearrangement was relatively normal. We also found the CDR3 length of TCRα chain was significantly longer in Satb1-deleted thymocytes, which can be explained by the strong bias of the proximal Jα usage. Our results showed that Satb1 plays an essential role in shaping TCR repertoires in αβ T cells.