The histone methyltransferase Setd2 is indispensable for V(D)J recombination

Area of Science:

• Immunology
• Epigenetics
• Molecular Biology

Background:

• T cell receptors (TCR) and immunoglobulins are vital for adaptive immunity.
• Their diversity arises from V(D)J recombination during lymphocyte development.
• Epigenetic regulation of this process remains incompletely understood.

Purpose of the Study:

• To investigate the role of Setd2, a histone methyltransferase, in V(D)J recombination and lymphocyte development.
• To elucidate the epigenetic mechanisms governing V(D)J recombination.

Main Methods:

• Utilized a mouse model deficient in Setd2.
• Analyzed thymocyte and B cell development stages.
• Assessed histone modifications (H3K36me3) at TCR loci.
• Examined RAG1 binding and DNA double-strand break repair.

Main Results:

• Setd2 deficiency caused a severe developmental block in thymocytes (DN3 stage) and B cells (pro-B stage).
• Reduced H3K36me3 enrichment at the TCRβ locus in Setd2-deficient mice.
• Impaired TCRβ V(D)J rearrangement due to reduced RAG1 binding and DNA repair.
• Setd2 mutations were identified in patients with primary immunodeficiency.

Conclusions:

• Setd2 is essential for V(D)J recombination in both T and B lymphocytes.
• H3K36me3 modification by Setd2 is critical for V(D)J rearrangement and lymphocyte development.
• Setd2 dysfunction contributes to primary immunodeficiency.