title: Somatic hypermutation in the absence of DNA-dependent protein kinase catalytic subunit (DNA-PK(cs)) or recombination-activating gene (RAG)1 activity.
abstract: Somatic hypermutation and isotype switch recombination occur in germinal center B cells, are linked to transcription, and are similarly affected by deficiency in MutS homologue (MSH)2. Class-switch recombination is abrogated by disruption of genes encoding components of the catalytic subunit of DNA-dependent protein kinase (DNA-PK(cs))/Ku complex and likely involves nonhomologous end joining (NHEJ). That somatic hypermutation might also be associated with end joining is suggested by its association with the creation of deletions, duplications, and sites accessible to terminal transferase. However, a requirement for NHEJ in the mutation process has not been demonstrated. Here we show that somatic mutation in mice deficient in NHEJ can be tested by introduction of rearranged immunoglobulin and T cell receptor transgenes: the transgene combination not only permits reconstitution of peripheral lymphoid compartments but also allows formation of germinal centers, despite the wholly monoclonal nature of the lymphocyte antigen receptors in these animals. Using this strategy, we confirm that somatic hypermutation like class-switching can occur in the absence of recombination-activating gene (RAG)1 but show that the two processes differ in that hypermutation can proceed essentially unaffected by deficiency in DNA-PK(cs) activity.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 2QH, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Bemark
authors.forename: J E
authors.initials: JE
authors.lastname: Sale
authors.forename: H J
authors.initials: HJ
authors.lastname: Kim
authors.forename: C
authors.initials: C
authors.lastname: Berek
authors.forename: R A
authors.initials: RA
authors.lastname: Cosgrove
authors.forename: M S
authors.initials: MS
authors.lastname: Neuberger
mesh_terms: D000818:Animals; D001483:Base Sequence; D020134:Catalytic Domain; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D015321:Gene Rearrangement; D016654:Genes, RAG-1; D018858:Germinal Center; D018398:Homeodomain Proteins; D007136:Immunoglobulins / Q000235:genetics; D051379:Mice; D016513:Mice, SCID; D008969:Molecular Sequence Data; D009113:Muramidase / Q000276:immunology; D016296:Mutagenesis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D021122:Protein Subunits; D011947:Receptors, Antigen, B-Cell / Q000235:genetics; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D011995:Recombination, Genetic; D019895:Transposases / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D007136:Immunoglobulins; D021122:Protein Subunits; D011947:Receptors, Antigen, B-Cell; D011948:Receptors, Antigen, T-Cell; C064658:RAG-1 protein; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases; D019895:Transposases; D009113:Muramidase