Radiation-induced delayed cell death in a hypomorphic Artemis cell line.
Null mutations in Artemis confer a condition described as RS-SCID, in which patients display radiosensitivity combined with severe combined immunodeficiency. Here, we characterize the defect in Artemis in a patient who displayed progressive combined immunodeficiency (CID) and elevated lymphocyte apoptosis. The patient is a compound heterozygote with novel mutations in both alleles, resulting in Artemis proteins with either L70 deletion or G126D substitution. Both mutational changes impact upon Artemis function and a fibroblast cell line derived from the patient (F96-224) has greatly reduced Artemis protein. In contrast to Artemis null cell lines, which fail to repair a subset of DNA double strand breaks (DSBs) induced by ionizing radiation, F96-224 cells show slow but residual DSB rejoining. Despite showing intermediate cellular and clinical features, F96-224 cells are as radiosensitive as Artemis null cell lines. We developed a FACS-based assay to examine cell division and cellular characteristics for 10 days following exposure to ionizing radiation (2 and 4 Gy). This analysis demonstrated that F96-224 cells show delayed cell death when compared with rapid growth arrest of an Artemis null cell line, and the emergence of a cycling population shown by a control line. F96-224 cells also display elevated chromosome aberrations when compared with control cells. F96-224 therefore represents a novel phenotype for a hypomorphic cell line. We suggest that delayed cell death contributes to the progressive CID phenotype of the Artemis patient.
Evans
Paul M
PM
Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
Woodbine
Lisa
L
Riballo
Enriquetta
E
Gennery
Andrew R
AR
Hubank
Michael
M
Jeggo
Penny A
PA
D016923:Cell Death / Q000528:radiation effects*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair; D004268:DNA-Binding Proteins; D004720:Endonucleases; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006579:Heterozygote; D006801:Humans; D007700:Kinetics; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D016511:Severe Combined Immunodeficiency / Q000378:metabolism; D045567:VDJ Recombinases / Q000378:metabolism
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D045567:VDJ Recombinases; C426344:DCLRE1C protein, human; D004720:Endonucleases