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
- Michigan State Univ., East Lansing (United States)
({plus minus})-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 (>95%) with guanine. To investigate the effect of nucleotide excision repair on the kinds and locations (spectra) of mutations induced in diploid human fibroblasts by BPDE, the authors synchronized cells and exposed them to BPDE either at the beginning of S phase just when the target gene hypoxanthine (guanine) phosphoribosyltransferase (HPRT) is replicated or 12 hours prior to the beginning of S phase (early G{sub 1} phase). Clones resistant to 6-thioguanine were isolated, and the mRNA in lysates of 100-500 cells from each mutant clone was used to synthesize cDNA. HPRT cDNA was amplified 10{sup 11}-fold by the polymerase chain reaction and then sequenced directly. The mutants derived from the two populations did not differ in the kinds of mutations; 19/20 of the base substitutions in cells taken from S phase and 19/19 of those from G{sub 1} phase involved G{center dot}C base pairs, predominantly G{center dot}C{yields}T{center dot}A. However, they differed significantly in the distribution of the mutations in the coding region of the gene. In the cells from G{sub 1} phase, 29% of the mutations were clustered within a unique run of six guanine bases; in the S-phase cells, only 4% were located there. Assuming that the premutagenic BPDE-induced lesions involved purines, in the cells treated at the beginning strand, whereas in the G{sub 1}-treated cells, none were. This suggests that in the HPRT gene of diploid human cells excision repair of BPDE adducts occurs preferentially on the transcribed strand.
- OSTI ID:
- 5822298
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Vol. 87:21; ISSN 0027-8424; ISSN PNASA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cell cycle-dependent strand bias for UV-induced mutations in the transcribed strand of excision repair-proficient human fibroblasts but not in repair-deficient cells
Mutations and homologous recombination induced in mammalian cells by metabolites of benzo(a)pyrene and 1-nitropyrene
Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ADDUCTS
AMINES
ANIMAL CELLS
ANIMALS
AROMATICS
AZAARENES
BENZOPYRENE
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL CYCLE
CONDENSED AROMATICS
CONNECTIVE TISSUE CELLS
DNA
DNA ADDUCTS
DNA BASE TRANSITIONS
DNA REPAIR
DOSE-RESPONSE RELATIONSHIPS
ENZYMES
EXCISION REPAIR
FIBROBLASTS
GLYCOSYL TRANSFERASES
GUANINE
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROXY COMPOUNDS
HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE
MAMMALS
MAN
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PENTOSYL TRANSFERASES
PRIMATES
PROTEINS
PURINES
RECOMBINANT DNA
RECOVERY
REPAIR
SOMATIC CELLS
TRANSFERASES
VERTEBRATES