Effect of excision repair by diploid human fibroblasts on the kinds and locations of mutations induced by (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene in the coding region of the HPRT gene.

作者: R. H. Chen , V. M. Maher , J. J. McCormick

DOI: 10.1073/PNAS.87.21.8680

关键词:

摘要: Abstract (+/-)-7 beta,8 alpha-Dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (BPDE) is a direct-acting carcinogen that forms DNA adducts only with purines, predominantly (greater than 95%) guanine. To investigate the effect of nucleotide excision repair on kinds and locations (spectra) mutations induced in diploid human fibroblasts by BPDE, we synchronized cells exposed them to BPDE either at beginning S phase just when target gene hypoxanthine (guanine) phosphoribosyltransferase (HPRT) replicated or 12 hr prior (early G1 phase). Clones resistant 6-thioguanine were isolated, mRNA lysates 100-500 from each mutant clone was used synthesize cDNA. HPRT cDNA amplified 10(11)-fold polymerase chain reaction then sequenced directly. The mutants derived two populations did not differ mutations; 19/20 base substitutions taken 19/19 those involved G.C pairs, G.C----T.A. However, they differed significantly distribution coding region gene. In phase, 29% clustered within unique run six guanine bases; S-phase cells, 4% located there. Assuming premutagenic BPDE-induced lesions treated 24% these transcribed strand, whereas G1-treated none were. This suggests occurs preferentially strand.

参考文章(0)