V(D)J Recombination Exploits DNA Damage Responses to Promote Immunity.

It has been recognized for 40 years that the variable (diversity) joining [V(D)J] recombination-mediated assembly of diverse B and T lymphocyte antigen receptor (AgR) genes is not only essential for adaptive immunity, but also a risk for autoimmunity and lymphoid malignancies. Over the past few years, several studies have revealed that recombination-activating gene (RAG) endonuclease-induced DNA double-strand breaks (DSBs) transcend hazardous intermediates during antigen receptor gene assembly. RAG cleavage within the genomes of lymphocyte progenitors and immature lymphocytes regulates the expression of ubiquitous and lymphocyte-specific gene transcripts to control the differentiation and function of both adaptive and innate immune cell lineages. These unexpected discoveries raise important new questions that have broad implications for basic immunology research and the screening, diagnosis, and treatment of human immunological disease.