title: DNA-PKcs Is Involved in Ig Class Switch Recombination in Human B Cells.
abstract: Nonhomologous end-joining (NHEJ) is one of the major DNA double-strand break repair pathways in mammalian cells and is required for both V(D)J recombination and class switch recombination (CSR), two Ig gene-diversification processes occurring during B cell development. DNA-dependent protein kinase, catalytic subunit (DNA-PKcs) is a component of the classical NHEJ machinery and has a critical function during V(D)J recombination. However, its role in CSR has been controversial. In this study, we examined the pattern of recombination junctions from in vivo-switched B cells from two DNA-PKcs-deficient patients. One of them harbored mutations that did not affect DNA-PKcs kinase activity but caused impaired Artemis activation; the second patient had mutations resulting in diminished DNA-PKcs protein expression and kinase activity. These results were compared with those from DNA-PKcs-deficient mouse B cells. A shift toward the microhomology-based alternative end-joining at the recombination junctions was observed in both human and mouse B cells, suggesting that the classical NHEJ pathway is impaired during CSR when DNA-PKcs is defective. Furthermore, cells from the second patient showed additional or more severe alterations in CSR and/or NHEJ, which may suggest that DNA-PKcs and/or its kinase activity have additional, Artemis-independent functions during these processes.
authors.affiliation: Department of Laboratory Medicine, Karolinska Institutet, 141 86 Stockholm, Sweden;
authors.forename: Andrea
authors.initials: A
authors.lastname: Björkman
authors.affiliation: Department of Laboratory Medicine, Karolinska Institutet, 141 86 Stockholm, Sweden;
authors.forename: Likun
authors.identifier: http://orcid.org/0000-0002-8448-2187
authors.initials: L
authors.lastname: Du
authors.affiliation: Division of Immunology, Harvard Medical School, Boston Children's Hospital, Boston, MA 02115;
authors.forename: Kerstin
authors.initials: K
authors.lastname: Felgentreff
authors.affiliation: Department of Laboratory Medicine, Karolinska Institutet, 141 86 Stockholm, Sweden;
authors.forename: Cornelia
authors.initials: C
authors.lastname: Rosner
authors.affiliation: Department of Laboratory Medicine, Karolinska Institutet, 141 86 Stockholm, Sweden;
authors.forename: Radhika
authors.identifier: http://orcid.org/0000-0001-7442-7830
authors.initials: R
authors.lastname: Pankaj Kamdar
authors.affiliation: Department of Laboratory Medicine, Karolinska Institutet, 141 86 Stockholm, Sweden;
authors.forename: Georgia
authors.initials: G
authors.lastname: Kokaraki
authors.affiliation: Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550, Japan; Department of Nuclear Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan;
authors.forename: Yoshihisa
authors.identifier: http://orcid.org/0000-0002-0758-290X
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Centre for Immunodeficiency, Great Ormond Street Hospital and Institute of Child Health, London WC1N 3JH, United Kingdom;
authors.forename: E Graham
authors.initials: EG
authors.lastname: Davies
authors.affiliation: Department of Immunology, Erasmus Medical Center, Rotterdam 3015 CN, the Netherlands; and.
authors.forename: Mirjam
authors.initials: M
authors.lastname: van der Burg
authors.affiliation: Division of Immunology, Harvard Medical School, Boston Children's Hospital, Boston, MA 02115; Harvard Stem Cell Institute, Cambridge, MA 02138.
authors.forename: Luigi D
authors.initials: LD
authors.lastname: Notarangelo
authors.affiliation: Department of Laboratory Medicine, Karolinska Institutet, 141 86 Stockholm, Sweden;
authors.forename: Lennart
authors.initials: L
authors.lastname: Hammarström
authors.affiliation: Department of Laboratory Medicine, Karolinska Institutet, 141 86 Stockholm, Sweden; qiang.pan-hammarstrom@ki.se.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Pan-Hammarström
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D017578:Immunoglobulin Class Switching; D007153:Immunologic Deficiency Syndromes / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016513:Mice, SCID; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D051747:DNA-Activated Protein Kinase; C497264:Prkdc protein, mouse; D004720:Endonucleases; C473337:Dclre1c protein, mouse