Transient correction of excision repair defects in fibroblasts of 9 xeroderma pigmentosum complementation groups by microinjection of crude human cell extracts

Mutat Res. 1986 May;165(3):199-206. doi: 10.1016/0167-8817(86)90055-6.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Fusion
  • Cells, Cultured
  • DNA Repair*
  • Endopeptidase K
  • Endopeptidases / metabolism
  • Genetic Complementation Test
  • Humans
  • In Vitro Techniques
  • Microinjections
  • Xeroderma Pigmentosum / genetics*


  • Endopeptidases
  • Endopeptidase K