title: ATM influences the efficiency of TCRβ rearrangement, subsequent TCRβ-dependent T cell development, and generation of the pre-selection TCRβ CDR3 repertoire.
abstract: Generation and resolution of DNA double-strand breaks is required to assemble antigen-specific receptors from the genes encoding V, D, and J gene segments during recombination. The present report investigates the requirement for ataxia telangiectasia-mutated (ATM) kinase, a component of DNA double-strand break repair, during TCRβ recombination and in subsequent TCRβ-dependent repertoire generation and thymocyte development. CD4(-)CD8(-) double negative stage 2/3 thymocytes from ATM-deficient mice have both an increased frequency of cells with DNA break foci at TCRβ loci and reduced Vβ-DJβ rearrangement. Sequencing of TCRβ complementarity-determining region 3 demonstrates that ATM-deficient CD4(+)CD8(+) double positive thymocytes and peripheral T cells have altered processing of coding ends for both in-frame and out-of-frame TCRβ rearrangements, providing the unique demonstration that ATM deficiency alters the expressed TCRβ repertoire by a selection-independent mechanism. ATMKO thymi exhibit a partial developmental block in DN cells as they negotiate the β-selection checkpoint to become double negative stage 4 and CD4(+)CD8(+) thymocytes, resulting in reduced numbers of CD4(+)CD8(+) cells. Importantly, expression of a rearranged TCRβ transgene substantially reverses this defect in CD4(+)CD8(+) cells, directly linking a requirement for ATM during endogenous TCRβ rearrangement to subsequent TCRβ-dependent stages of development. These results demonstrate that ATM plays an important role in TCRβ rearrangement, generation of the TCRβ CDR3 repertoire, and efficient TCRβ-dependent T cell development.
authors.affiliation: Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America. hathcock@mail.nih.gov
authors.forename: Karen S
authors.initials: KS
authors.lastname: Hathcock
authors.forename: Steven
authors.initials: S
authors.lastname: Bowen
authors.forename: Ferenc
authors.initials: F
authors.lastname: Livak
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hodes
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D022801:Complementarity Determining Regions / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded; D023061:Gene Order; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D051379:Mice; D018345:Mice, Knockout; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D013601:T-Lymphocytes / Q000378:metabolism*; D060168:Thymocytes / Q000378:metabolism
chemical_list: D022801:Complementarity Determining Regions; D016693:Receptors, Antigen, T-Cell, alpha-beta; D064007:Ataxia Telangiectasia Mutated Proteins