부산대학교 도서관

While extended loop extrusion across the entire Igh locus controls VH‐DJH recombination, local regulatory sequences, such as the PAIR elements, may also activate VH gene recombination in pro‐B‐cells. Here, we show that PAIR‐associated VH8 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 VH gene recombination over a 100‐kb distance on either side of the deletion. Reconstitution by insertion of PAIR4‐V8.7E strongly activated distal VH 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 VH gene recombination. Hence, enhancers of the PAIR4‐V8.7E module and V8.8E element activate distal VH gene recombination and thus contribute to the diversification of the BCR repertoire in the context of loop extrusion. Synopsis: In vivo deletion and reconstitution experiments in the mouse Igh locus show that enhancers of the PAIR regulatory module activate distal VH gene recombination over a distance of 100 kb and thus contribute to the diversification of the BCR repertoire in the context of loop extrusion.PAIR‐associated VH8 genes contain a conserved putative regulatory element (V8E) in their downstream sequences.Deletion of an 890‐kb distal Igh region containing all 14 PAIRs reduced VH gene recombination over a 100‐kb distance on either side of the deletion.Reconstitution by inserting the enhancers of the PAIR4‐V8.7E module strongly promoted distal VH gene recombination by inducing active chromatin over a distance of 100 kb.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. [ABSTRACT FROM AUTHOR]