Rag1 and Rag2 gene expression in CD4(+)CD8(+) double-positive (DP) thymocytes 
depends on the activity of a distant anti-silencer element (ASE) that 
counteracts the activity of an intergenic silencer. However, the mechanistic 
basis for ASE activity is unknown. Here, we show that the ASE physically 
interacts with the distant Rag1 and Rag2 gene promoters in DP thymocytes, 
bringing the two promoters together to form an active chromatin hub. Moreover, 
we show that the ASE functions as a classical enhancer that can potently 
activate these promoters in the absence of the silencer or other locus elements. 
In thymocytes lacking the chromatin organizer SATB1, we identified a partial 
defect in Tcra gene rearrangement that was associated with reduced expression of 
Rag1 and Rag2 at the DP stage. SATB1 binds to the ASE and Rag promoters, 
facilitating inclusion of Rag2 in the chromatin hub and the loading of RNA 
polymerase II to both the Rag1 and Rag2 promoters. Our results provide a novel 
framework for understanding ASE function and demonstrate a novel role for SATB1 
as a regulator of Rag locus organization and gene expression in DP thymocytes.