title: Radiosensitive Chinese hamster irs2 cells show enhanced chromosomal sensitivity to ionizing radiation and restriction endonuclease induced blunt-ended double-strand breaks.
abstract: The Chinese hamster irs2 cell line shows cellular hypersensitivity to ionizing radiation although the induction and repair of double-strand breaks (dsb) in bulk DNA is normal. Here we report that irs2 shows chromosomal hypersensitivity to ionizing radiation and the restriction endonuclease PvuII. The ratio of induced chromosomal aberrations in irs2 versus V79 was similar to that for survival (factor of between 2 and 4). PvuII was administered during cell poration with the bacterial toxin streptolysin O. We also report that when streptolysin O porated irs2 and V79 cells were treated with PvuII, and dsb assayed by neutral filter elution, equivalent numbers of dsb were induced in the two lines as a function of time following treatment. Our data show that irs2 has a DNA damage processing defect that leads to enhanced conversion of blunt-ended dsb into visible chromosomal damage.
authors: School of Biological and Medical Sciences, University of St Andrews, Fife, UK.
authors: P E
authors: PE
authors: Bryant
authors: N J
authors: NJ
authors: Jones
authors: N
authors: N
authors: Liu
mesh_terms: D000818:Animals; D002460:Cell Line; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000528:radiation effects*; D002999:Clone Cells; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D008677:Metaphase; D048629:Micronuclei, Chromosome-Defective / Q000528:radiation effects; D015183:Restriction Mapping; D014965:X-Rays
chemical_list: D004247:DNA; C025630:CAGCTG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific