Effect of strand-specific excision repair on the spectra of mutations induced by benzo[a]pyrene-diol epoxide and ultraviolet radiation in diploid human cells
To study the effect of excision repair on the spectra of mutations induced in diploid human cells by UV and [plus minus]-7[beta], 8[alpha]-dihydroxy-9[alpha],10[alpha]-epoxy- 7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), the author synchronized repair-proficient cells, treated them at the beginning of S phase or in G[sub 1] phase several hours prior to the onset of S phase, selected for thioguanine resistant cells, and determined the spectra of mutations in the coding region of the hyproxanthine(guanine)phosphoribosyl-transferase (HPRT) gene in the mutants. As a control, the spectra of mutations similarly induced in repair-deficient xeroderma pigmentosum (XP) cells were compared. There was no difference in the kinds of mutations observed in mutants derived from either cell strain treated with a particular mutagen either in S or in G[sub 1]. With BPDE, the majority were G.C[yields]T.A transversions; with UV, they were mainly G.C.[yields]A.T transitions. The strand distribution of premutagenic lesions in mutants from repair-proficient cells treated in S or G[sub 1] differed significantly. The results strongly support the hypothesis that human cells preferentially repair UV- and BPDE-induced lesions from the transcribed strand of the HPRT gene. To test this, the rate of repair of BPDE adducts from individual strands of the HPRT gene was measured, using the UvrABC exinuclease and Southern hybridizations with strand-specific probes to detect lesions remaining. BPDE lesions were removed from the transcribed strand at a significantly faster rate than from the nontranscribed strand, consistent with my hypothesis. It was found that BPDE adducts were removed faster from either strand of the HPRT gene than from a transcriptionally inactive locus, indicating preferential repair of active genes. The results of these studies provide biochemical and biological evidence of strand-specific DNA repair of BPDE adducts in human cells.
- Research Organization:
- Michigan State Univ., East Lansing, MI (United States)
- OSTI ID:
- 5580344
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BENZOPYRENE
GENETIC EFFECTS
DNA ADDUCTS
EXCISION REPAIR
MAN
GENE MUTATIONS
ULTRAVIOLET RADIATION
BIOLOGICAL RADIATION EFFECTS
EPOXIDES
EXPERIMENTAL DATA
XP CELLS
ADDUCTS
ANIMAL CELLS
ANIMALS
AROMATICS
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CONDENSED AROMATICS
DATA
DNA REPAIR
ELECTROMAGNETIC RADIATION
HYDROCARBONS
INFORMATION
MAMMALS
MUTATIONS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PRIMATES
RADIATION EFFECTS
RADIATIONS
REPAIR
VERTEBRATES
560151* - Radiation Effects on Animals- Man
560300 - Chemicals Metabolism & Toxicology
550400 - Genetics
550200 - Biochemistry