Abstract
Mutations in Artemis in both humans and mice result in severe combined immunodeficiency due to a defect in V(D)J recombination. In addition, Artemis mutants are radiosensitive and chromosomally unstable, which has been attributed to a defect in nonhomologous end joining (NHEJ). We show here, however, that Artemis-depleted cell extracts are not defective in NHEJ and that Artemis-deficient cells have normal repair kinetics of double-strand breaks after exposure to ionizing radiation (IR). Artemis is shown, however, to interact with known cell cycle checkpoint proteins and to be a phosphorylation target of the checkpoint kinase ATM or ATR after exposure of cells to IR or UV irradiation, respectively. Consistent with these findings, our results also show that Artemis is required for the maintenance of a normal DNA damage-induced G2/M cell cycle arrest. Artemis does not appear, however, to act either upstream or downstream of checkpoint kinase Chk1 or Chk2. These results define Artemis as having a checkpoint function and suggest that the radiosensitivity and chromosomal instability of Artemis-deficient cells may be due to defects in cell cycle responses after DNA damage.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Ataxia Telangiectasia Mutated Proteins
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cell Division / physiology
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Checkpoint Kinase 1
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Checkpoint Kinase 2
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Chromosomal Instability / physiology
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Chromosomal Instability / radiation effects
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DNA / metabolism
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DNA / radiation effects
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DNA Damage*
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DNA Repair*
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DNA-Activated Protein Kinase
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DNA-Binding Proteins / metabolism
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Endonucleases
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G2 Phase / physiology*
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Humans
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Mice
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Phosphorylation
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Protein Kinases / metabolism
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism
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Radiation, Ionizing
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Tumor Suppressor Proteins
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Ultraviolet Rays
Substances
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Cell Cycle Proteins
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DNA-Binding Proteins
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Nuclear Proteins
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RNA, Small Interfering
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Recombinant Fusion Proteins
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Tumor Suppressor Proteins
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DNA
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Protein Kinases
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Checkpoint Kinase 2
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ATM protein, human
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ATR protein, human
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Ataxia Telangiectasia Mutated Proteins
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Atm protein, mouse
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CHEK1 protein, human
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CHEK2 protein, human
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Checkpoint Kinase 1
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Chek1 protein, mouse
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Chek2 protein, mouse
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DNA-Activated Protein Kinase
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PRKDC protein, human
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Protein Serine-Threonine Kinases
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DCLRE1C protein, human
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Endonucleases