Control of chromatin accessibility for V(D)J recombination by interleukin-7

IL-7 is a key factor for lymphoid development, and it contributes to V(D)J recombination at multiple loci in immune-receptor genes, IL-7 signal transd uction, involving gamma (c) and Jak3, is required for successful recombinat ion at the TCR-gamma locus, IL-7 signaling controls the initiation phase of V(D)J recombination by controlling access of the V(D)J recombinase to the locus. in the absence of IL-7, the TCR-gamma locus is methylated and packag ed in a repressed form of chromatin consisting of hypoacetylated histones, IL-7 signaling likely increases the acetylation state of the nucleosomal co re histones resulting in an "open" form of chromatin. This opening leads to a higher accessibility for the transcription machinery and increased acces sibility of the Rag heterodimer that performs the cleavage of DNA.