Phenotypic correction of xeroderma pigmentosum cells by microinjection of crude extracts and purified proteins

Extracts from prokaryotic and eukaryotic cells and enzymes involved in DNA repair were injected into cultured fibroblasts from patients with the DNA repair syndrome xeroderma pigmentosum (XP). To determine whether the injected cells were complemented with respect to their deficiency in the removal of pyrimidine dimers, they were tested for uv-induced unscheduled DNA synthesis (UDS). Microinjection of extracts prepared from repair proficient cells induced a temporary increase of UDS in uv-irradiated fibroblasts from XP complementation groups A, D and G. The XP-A and XP-G correcting factors are stable on storage and are sensitive to proteolytic degradation, suggesting that they are proteins. 14 references, 1 figure, 3 tables