Identification and Characterization of X-Ray-induced Proteins in Human Cells

摘要: In order to investigate the biochemical events involved in potentially lethal DNA damage repair (PLDR), we have identified a pleiotropic protein expression response that is activated upon X-irradiation of confluence-arrested human malignant melanoma (U1-Mel) cells. Plateau-phase U1-Mel cells were selected because their extraordinary capacity for PLDR. Eight major X-ray-induced polypeptides (XIPs) Mr 126,000-275,000 (i.e., XIP126 through XIP275) detected by resolving L-[35S]methionine-labeled whole cell extracts using two-dimensional gel electrophoresis. XIPs found unirradiated, proliferating cells, shut off under plateau-phase conditions and resynthesized X-irradiation. The three classes proteins was affected Class I proteins, XIP145 XIP269, induced linearly with increasing X-ray doses. rate synthesis class II XIP126, XIP135, XIP138, XIP141, XIP147, XIP275, increased low doses, but plateaued at doses 150-250 cGy. contrast, III 47,000 254,000 decreased Tumor, cancer-prone, normal which represent wide range varied capacities, investigated better understand role responses. X-irradiated tumor XIP269. A strong correlation between induction XIP269 PLDR capacity, as measured delayed plating noted. present six seven types, completely absent from patients Bloom's syndrome ataxia telangiectasia. Fanconi's anemia xeroderma pigmentosum synthesized levels majority cancer-prone molecular weights. number XIP characteristics suggest either gross chromosomal and/or adaptivity responses: (a) inhibited 1 microgram/ml cycloheximide, dose survival 6-fold during holding resulted greater than 80% inhibition synthesis; (b) specific ionizing radiation damage, since heat shock, hypoxia, alkylating agents failed induce (c) time course long, first appearance 3 h maximal 4 h.