Transient correction of excision repair defects in fibroblasts of 9 xeroderma pigmentosum complementation groups by microinjection of crude human cell extracts.
Crude extracts from human cells were microinjected into the cytoplasm of cultured fibroblasts from 9 excision-deficient xeroderma pigmentosum (XP) complementation groups. The level of UV-induced unscheduled DNA synthesis (UDS) was measured to determine the effect of the extract on the repair capacity of the injected cells. With a sensitive UDS assay procedure a (transient) increase in UV-induced UDS level was found in fibroblasts from all complementation groups after injection of extracts from repair-proficient (HeLa) or complementing XP cells (except in the case of XP-G), but not after introduction of extracts from cells belonging to the same complementation group. This indicates that the phenotypic correction is exerted by complementation-group-specific factors in the extract, a conclusion that is in agreement with the observation that different levels of correction are found for different complementation groups. The XP-G-correcting factor was shown to be sensitive to proteolytic degradation, suggesting that it is a protein like the XP-A factor.
D002459:Cell Fusion; D002478:Cells, Cultured; D004260:DNA Repair; D019286:Endopeptidase K; D010450:Endopeptidases / Q000378:metabolism; D005816:Genetic Complementation Test; D006801:Humans; D066298:In Vitro Techniques; D008845:Microinjections; D014983:Xeroderma Pigmentosum / Q000235:genetics*
D010450:Endopeptidases; D019286:Endopeptidase K