title: Restoration of ATM Expression in DNA-PKcs-Deficient Cells Inhibits Signal End Joining.
abstract: Unlike most DNA-dependent protein kinase, catalytic subunit (DNA-PKcs)-deficient mouse cell strains, we show in the present study that targeted deletion of DNA-PKcs in two different human cell lines abrogates VDJ signal end joining in episomal assays. Although the mechanism is not well defined, DNA-PKcs deficiency results in spontaneous reduction of ATM expression in many cultured cell lines (including those examined in this study) and in DNA-PKcs-deficient mice. We considered that varying loss of ATM expression might explain differences in signal end joining in different cell strains and animal models, and we investigated the impact of ATM and/or DNA-PKcs loss on VDJ recombination in cultured human and rodent cell strains. To our surprise, in DNA-PKcs-deficient mouse cell strains that are proficient in signal end joining, restoration of ATM expression markedly inhibits signal end joining. In contrast, in DNA-PKcs-deficient cells that are deficient in signal end joining, complete loss of ATM enhances signal (but not coding) joint formation. We propose that ATM facilitates restriction of signal ends to the classical nonhomologous end-joining pathway.
authors.affiliation: Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824;
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Neal
authors.affiliation: Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824;
authors.forename: Yao
authors.initials: Y
authors.lastname: Xu
authors.affiliation: National Institute of Radiological Sciences, Chiba 263-8555, Japan; and.
authors.forename: Masumi
authors.initials: M
authors.lastname: Abe
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455.
authors.forename: Eric
authors.initials: E
authors.lastname: Hendrickson
authors.affiliation: Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; kmeek@msu.edu.
authors.forename: Katheryn
authors.initials: K
authors.lastname: Meek
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000172:deficiency / Q000235:genetics*; D002460:Cell Line; D059766:DNA End-Joining Repair; D051747:DNA-Activated Protein Kinase / Q000172:deficiency*; D000066630:Ectopic Gene Expression; D053595:Embryonic Stem Cells / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression; D018390:Gene Targeting; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D010641:Phenotype; D060152:V(D)J Recombination
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase