The radiosensitive cell line 180BR is not defective in the major DNA damage-sensing proteins.
The fibroblast culture 180BR, established from a patient showing an adverse response to radiotherapy, has been shown previously to be hypersensitive to ionizing radiation and to be defective in the repair of DNA double-strand breaks. We demonstrate here that the products of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) and its regulatory subunits (Ku 70 and Ku 80) are present at normal levels and possess functional activity. The product of the gene mutated in the human genetic disorder ataxia-telangiectasia was also detected in these cells. Apoptosis was detected after high-dose ionizing radiation exposure, and this process was accompanied by specific degradation of DNA-PKcs, ATM, and poly(ADP-ribose) polymerase. Activation of CPP32, an interleukin 1beta converting enzyme-like protease implicated in apoptosis, was also observed in 180BR cells in response to radiation damage. The radiosensitivity observed in 180BR cells can be accounted for, at least in part, by radiation-induced apoptosis, and the defect in these cells is not a gross one in DNA-PKcs or ATM.
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The Queensland Institute of Medical Research, The Bancroft Centre, Herston, Brisbane, Australia.
Song
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Arlett
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Lavin
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D001260:Ataxia Telangiectasia / Q000201:enzymology; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D004249:DNA Damage; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D005347:Fibroblasts / Q000201:enzymology* / Q000528:radiation effects; D006801:Humans; D009687:Nuclear Proteins; D011065:Poly(ADP-ribose) Polymerases / Q000032:analysis; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000201:enzymology; D017346:Protein Serine-Threonine Kinases / Q000032:analysis*; D011506:Proteins / Q000032:analysis; D011836:Radiation Tolerance; D014407:Tumor Cells, Cultured / Q000201:enzymology / Q000528:radiation effects; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011506:Proteins; D025521:Tumor Suppressor Proteins; D011065:Poly(ADP-ribose) Polymerases; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases