title: Immature Lymphocytes InhibitRag1andRag2Transcription and V(D)J Recombination in Response to DNA Double-Strand Breaks.
abstract: Mammalian cells have evolved a common DNA damage response (DDR) that sustains cellular function, maintains genomic integrity, and suppresses malignant transformation. In pre-B cells, DNA double-strand breaks (DSBs) induced atIgκloci by the Rag1/Rag2 (RAG) endonuclease engage this DDR to modulate transcription of genes that regulate lymphocyte-specific processes. We previously reported that RAG DSBs induced at oneIgκallele signal through the ataxia telangiectasia mutated (ATM) kinase to feedback-inhibit RAG expression and RAG cleavage of the otherIgκallele. In this article, we show that DSBs induced by ionizing radiation, etoposide, or bleomycin suppress Rag1 and Rag2 mRNA levels in primary pre-B cells, pro-B cells, and pro-T cells, indicating that inhibition ofRag1andRag2expression is a prevalent DSB response among immature lymphocytes. DSBs induced in pre-B cells signal rapid transcriptional repression ofRag1andRag2, causing downregulation of both Rag1 and Rag2 mRNA, but only Rag1 protein. This transcriptional inhibition requires the ATM kinase and the NF-κB essential modulator protein, implicating a role for ATM-mediated activation of canonical NF-κB transcription factors. Finally, we demonstrate that DSBs induced in pre-B cells by etoposide or bleomycin inhibit recombination ofIgκloci and a chromosomally integrated substrate. Our data indicate that immature lymphocytes exploit a common DDR signaling pathway to limit DSBs at multiple genomic locations within developmental stages wherein monoallelic Ag receptor locus recombination is enforced. We discuss the implications of our findings for mechanisms that orchestrate the differentiation of monospecific lymphocytes while suppressing oncogenic Ag receptor locus translocations.
authors.affiliation: Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104.|Immunology Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104.|Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Megan R
authors.initials: MR
authors.lastname: Fisher
authors.affiliation: Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104.|Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104.|Cancer Biology Program of the Cell and Molecular Biology Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104; and.
authors.forename: Adrian
authors.initials: A
authors.lastname: Rivera-Reyes
authors.affiliation: Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104.
authors.forename: Noah B
authors.initials: NB
authors.lastname: Bloch
authors.affiliation: Department of Immunobiology, Yale University School of Medicine, Howard Hughes Medical Institute, New Haven, CT 06520.
authors.forename: David G
authors.initials: DG
authors.lastname: Schatz
authors.affiliation: Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104; bassing@email.chop.edu.|Immunology Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104.|Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104.|Cancer Biology Program of the Cell and Molecular Biology Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104; and.
authors.forename: Craig H
authors.initials: CH
authors.lastname: Bassing
mesh_terms: D000818:Animals; D015139:Blotting, Southern; D015153:Blotting, Western; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000378:metabolism; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology*; D018398:Homeodomain Proteins / Q000378:metabolism; D054503:Lymphoid Progenitor Cells / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D060888:Real-Time Polymerase Chain Reaction; D014158:Transcription, Genetic; D060152:V(D)J Recombination / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C499308:Rag2 protein, mouse; C064658:RAG-1 protein