Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pretreatment of mammalian cell with DNA-damaging agents, such as UV light or mitomycin C, but not the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA), results in the enhanced repair of subsequently transfected UV-damaged expression vectors. To determine the cellular factors that are responsible for this enhancement, we have used a modified gel retardation assay to detect the proteins that interact with damaged DNA. We have identified a constitutive DNA binding protein in extracts from primate cells that has a high affinity for UV-irradiated double-stranded DNA. Cells pretreated with UV light, mitomycin C, or aphidicolin, but not TPA or serum starvation, have higher levels of this damage-specific DNA binding (DDB) protein. These results suggest that the signal for induction of DDB protein can either be damage to the DNA or interference with cellular DNA replication. The induction of DDB protein varies among primate cells with different phenotypes: (1) virus-transformed repair-proficient cells have partially or fully lost the ability to induce DDB protein above constitutive levels; (2) primary cells from repair-deficient xeroderma pigmentosum (XP) group C, and transformed XP groups A and D, show constitutive DDB protein, but do not show induced levels of this protein 48 h after UV; and (3) primary and transformed repair-deficient cells from one XP E patient are lacking both the constitutive and the induced DDB activity. The correlation between the induction of the DDB protein and the enhanced repair of UV-damaged expression vectors implies the involvement of the DDB protein in this inducible cellular response.
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PMID:Induction of a novel damage-specific DNA binding protein correlates with enhanced DNA repair in primate cells. 251 95

A rapid procedure for measuring unscheduled DNA synthesis has been studied in detail. Human fibroblasts were brought into the non-dividing state by either growing to confluence or starvation for arginine. Residual semi-conservative synthesis was abolished by hydroxyurea. Hydroxyurea-resistant DNA synthesis which was induced by irradiation and chemical mutagens was presumed to represent repair synthesis and provided a very rapid semi-quantitative procedure for its measurement. Problems were encountered, however, when comparing the quantitative response of different cell strains. The variability between experiments was quite large, and we found that the level of repair synthesis depended not only on the mutagen and the genotype of the cell, but also on physiological factors. This led to some anomalous results. The system was able to detect with ease the large defects in UV-induced repair synthesis in fibroblasts from patients with xeroderma pigmentosum (XP) but it would probably not easily detect less than a 50% reduction in the level of repair synthesis. By extension of this procedure, in combination with cell fusion induced by polyethylene glycol, we have developed a method for carrying out genetic complementation of XP fibroblasts, which does not entail the use of either Sendai virus or of autoradiography. Results of complementation analysis of 4 XP cell strains are presented.
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PMID:A rapid procedure for measurement of DNA repair in human fibroblasts and for complementation analysis of xeroderma pigmentosum cells. 698 95