Enhancers of the PAIR4 regulatory module promote distal V_H gene recombination at the Igh locus.

ABSTRACT: While extended loop extrusion across the entire Igh locus controls V_H -DJ_H recombination, local regulatory sequences, such as the PAIR elements, may also activate V_H gene recombination in pro-B-cells. Here, we show that PAIR-associated V_H 8 genes contain a conserved putative regulatory element (V8E) in their downstream sequences. To investigate the function of PAIR4 and its V8.7E, we deleted 890 kb containing all 14 PAIRs in the Igh 5' region, which reduced distal V_H gene recombination over a 100-kb distance on either side of the deletion. Reconstitution by insertion of PAIR4-V8.7E strongly activated distal V_H gene recombination. PAIR4 alone resulted in lower induction of recombination, indicating that PAIR4 and V8.7E function as one regulatory unit. The pro-B-cell-specific activity of PAIR4 depends on CTCF, as mutation of its CTCF-binding site led to sustained PAIR4 activity in pre-B and immature B-cells and to PAIR4 activation in T-cells. Notably, insertion of V8.8E was sufficient to activate V_H gene recombination. Hence, enhancers of the PAIR4-V8.7E module and V8.8E element activate distal V_H gene recombination and thus contribute to the diversification of the BCR repertoire in the context of loop extrusion.

SUBMITTER: Hill L 

PROVIDER: S-EPMC10390877 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature