title: Congenital bone marrow failure in DNA-PKcs mutant mice associated with deficiencies in DNA repair.
abstract: The nonhomologous end-joining (NHEJ) pathway is essential for radioresistance and lymphocyte-specific V(D)J (variable [diversity] joining) recombination. Defects in NHEJ also impair hematopoietic stem cell (HSC) activity with age but do not affect the initial establishment of HSC reserves. In this paper, we report that, in contrast to deoxyribonucleic acid (DNA)-dependent protein kinase catalytic subunit (DNA-PKcs)-null mice, knockin mice with the DNA-PKcs(3A/3A) allele, which codes for three alanine substitutions at the mouse Thr2605 phosphorylation cluster, die prematurely because of congenital bone marrow failure. Impaired proliferation of DNA-PKcs(3A/3A) HSCs is caused by excessive DNA damage and p53-dependent apoptosis. In addition, increased apoptosis in the intestinal crypt and epidermal hyperpigmentation indicate the presence of elevated genotoxic stress and p53 activation. Analysis of embryonic fibroblasts further reveals that DNA-PKcs(3A/3A) cells are hypersensitive to DNA cross-linking agents and are defective in both homologous recombination and the Fanconi anemia DNA damage response pathways. We conclude that phosphorylation of DNA-PKcs is essential for the normal activation of multiple DNA repair pathways, which in turn is critical for the maintenance of diverse populations of tissue stem cells in mice.
authors.affiliation: Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Shichuan
authors.initials: S
authors.lastname: Zhang
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Yajima
authors.forename: Hoangdinh
authors.initials: H
authors.lastname: Huynh
authors.forename: Junke
authors.initials: J
authors.lastname: Zheng
authors.forename: Elsa
authors.initials: E
authors.lastname: Callen
authors.forename: Hua-Tang
authors.initials: HT
authors.lastname: Chen
authors.forename: Nancy
authors.initials: N
authors.lastname: Wong
authors.forename: Samuel
authors.initials: S
authors.lastname: Bunting
authors.forename: Yu-Fen
authors.initials: YF
authors.lastname: Lin
authors.forename: Mengxia
authors.initials: M
authors.lastname: Li
authors.forename: Kyung-Jone
authors.initials: KJ
authors.lastname: Lee
authors.forename: Michael
authors.initials: M
authors.lastname: Story
authors.forename: Eric
authors.initials: E
authors.lastname: Gapud
authors.forename: Barry P
authors.initials: BP
authors.lastname: Sleckman
authors.forename: André
authors.initials: A
authors.lastname: Nussenzweig
authors.forename: Cheng Cheng
authors.initials: CC
authors.lastname: Zhang
authors.forename: David J
authors.initials: DJ
authors.lastname: Chen
authors.forename: Benjamin P C
authors.initials: BP
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000633:toxicity; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics*; D051747:DNA-Activated Protein Kinase / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005199:Fanconi Anemia / Q000235:genetics*; D005347:Fibroblasts / Q000378:metabolism; D055879:Gene Knock-In Techniques; D006410:Hematopoiesis / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D017495:Hyperpigmentation / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D011995:Recombination, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D051747:DNA-Activated Protein Kinase; C497264:Prkdc protein, mouse