Restricted ultraviolet mutational spectrum in a shuttle vector propagated in xeroderma pigmentosum cells
A shuttle vector plasmid, pZ189, carrying a bacterial suppressor tRNA marker gene, was treated with ultraviolet radiation and propagated in cultured skin cells from a patient with the skin-cancer-prone, DNA repair-deficient disease xeroderma pigmentosum and in repair-proficient cells. After replication in the human cells, progeny plasmids were purified. Plasmid survival and mutations inactivating the marker gene were scored by transforming an indicator strain of Escherichia coli carrying a suppressible amber mutation in the beta-galactosidase gene. Plasmid survival in the xeroderma pigmentosum cells was less than that of pZ189 harvested from repair-proficient human cells. The point-mutation frequency in the 150-base-pair tRNA marker gene increased up to 100-fold with ultraviolet dose. Sequence analysis of 150 mutant plasmids revealed that mutations were infrequent at potential thymine-thymine dimer sites. Ninety-three percent of the mutant plasmids from the xeroderma pigmentosum cells showed G X C----A X T transitions, compared to 73% in the normal cells (P less than 0.002). There were significantly fewer transversions (P less than 0.002) (especially G X C----T X A) and multiple base substitutions (P less than 0.00001) than when pZ189 was passaged in repair-proficient cells. The subset of mutational changes that are common to ultraviolet-treated plasmids propagated in both repair-proficient and xeroderma pigmentosum skin cells may be associated with the development of ultraviolet-induced skin cancer in humans.
- Research Organization:
- National Cancer Institute, Bethesda, MD
- OSTI ID:
- 6914870
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 21
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PLASMIDS
ULTRAVIOLET RADIATION
GENETIC EFFECTS
CELL CULTURES
DNA REPAIR
EPIDERMIS
GENE MUTATIONS
XERODERMA PIGMENTOSUM
ANIMAL TISSUES
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BODY
CELL CONSTITUENTS
DISEASES
ELECTROMAGNETIC RADIATION
EPITHELIUM
MUTATIONS
ORGANS
RADIATIONS
RECOVERY
REPAIR
SKIN
SKIN DISEASES
TISSUES
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture