Cutting Edge: Histone Acetylation and Recombination at the TCR Locus Follows IL-7 Induction

IL-7 signaling is required for V(D)J recombination at the TCR locus. We have recently reported that IL-7 controls chromatin accessibility for RAG-mediated cleavage. Inhibition of histone deacetylase substituted for the IL-7 signal, indicating a role for histone acetylation in altering chromatin accessibility. We found a greatly reduced histone 3 and histone 4 acetylation level in IL-7R / thymocytes in comparison with RAG / thymocytes or fetal thymocytes. Sterile transcripts, indicating an open chromatin configuration, were suppressed in IL-7R / and IL-7 / RAG / thymocytes. Moreover, exogenously added IL-7 induced sterile transcripts from the TCR constant region in cultured thymocytes from IL-7 / RAG / mice. This induction correlated with increased histone acetylation at the J-promoter and C-enhancer regulatory elements at the TCR locus. These results suggest that IL-7 regulates chromatin accessibility for V(D)J recombination by specifically altering histone acetylation within the TCR locus. The Journal of Immunology, 2001, 167: 6073–6077.