Ablation of SetD2 impaired the lymphocyte development in mouse models.

The repertoire of diverse T-cell receptors (TCRs) and immunoglobulins is generated through restrictedly lineage and stage specific DNA rearrangements of variable (V), diversity (D) and Joining (J) gene segments at early T and B cell development. Histone modifications has been demonstrated to ensure proper VDJ recombination. However, the epigenetic mechanisms and the role of enzymes that catalyze epigenetic modifications in regulating VDJ recombination still remain largely unexplored. Herein we report that deletion of SetD2, the histone methyltransferase to catalyze the trimethylation of lysine 36 on histone 3, leads to severe lymphopenia due to development blockage of T lymphocyte at the double negative 3 (DN3) stage and differentiation arrest of B cell development at the pro-B stage in genetically engineered mouse models. SetD2 deficiency causes a loss of H3K36me3 and markedly impairs VDJ rearrangement of TCRβ and immunoglobulin heavy chain. Our study demonstrates that SetD2 and its mediated H3K36M3 modification are required for the VDJ recombination and normal lymphocyte development. Examination of transcriptional difference between SetD2-deficient mice DN3 thymocytes and control