An Igh distal enhancer modulates antigen receptor diversity by determining locus conformation.

Bhat, Khalid H; Priyadarshi, Saurabh; Naiyer, Sarah; Qu, Xinyan; Farooq, Hammad; Kleiman, Eden; Xu, Jeffery; Lei, Xue et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

The mouse Igh locus is organized into a developmentally regulated topologically associated domain (TAD) that is divided into subTADs. Here we identify a series of distal V<sub>H</sub> enhancers (E<sub>VH</sub>s) that collaborate to configure the locus. E<sub>VH</sub>s engage in a network of long-range interactions that interconnect the subTADs and the recombination center at the D<sub>H</sub>J<sub>H</sub> gene cluster. Deletion of E<sub>VH</sub>1 reduces V gene rearrangement in its vicinity and alters discrete chromatin loops and higher order locus conformation. Reduction in the rearrangement of the V<sub>H</sub>11 gene used in anti-PtC responses is a likely cause of the observed reduced splenic B1 B cell compartment. E<sub>VH</sub>1 appears to block long-range loop extrusion that in turn contributes to locus contraction and determines the proximity of distant V<sub>H</sub> genes to the recombination center. E<sub>VH</sub>1 is a critical architectural and regulatory element that coordinates chromatin conformational states that favor V(D)J rearrangement.

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