The removal of UV-induced pyrimidine dimers from DNA of rat skin cells in vitro and in vivo in relation to aging

E. Mullaart, L. Roza, P. H.M. Lohman, J. Vijg

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16 Scopus citations


Young and old rats were compared with respect to the capacity of their skin fibroblasts and epidermal keratinocytes to remove low levels of ultraviolet light (UV) induced UV-endonuclease sensitive sites (pyrimidine dimers) from their DNA, in vitro and in vivo, respectively. In vitro, over a 24-h time period, fibroblasts from both young and old rats were found to remove about 20% of the pyrimidine dimers originally induced by 4.6 J/m2 of UV-C. In vivo, after 2.6 kJ/m2 of UV-B hardly any UV lesions were found to be present in fibroblasts, as demonstrated by immunohistochemistry using an anti-thymine dimer antibody. As reported earlier (Mullaart et a., J. Invest. Dermatol., 90 (1988) 346-349) cultured epidermal keratinocytes do not differ from cultured fibroblasts in UV repair kinetics, whereas in vivo they remove at least 50% of the pyrimidine dimers induced by 4 kJ/m2 of UV-B within 3 h. We now show that epidermal keratinocytes from old rats are not deficient in their in vivo repair characteristics upon this low UV-B dose. However, since a considerable fraction of the pyrimidine dimers appeared to be persistent in fibroblasts and keratinocytes, demonstrated by both enzymatic and immunochemical assays, the possibility is discussed that long-term exposure of skin cells to UV may lead to an accumulation of DNA damage with age.

Original languageEnglish (US)
Pages (from-to)253-264
Number of pages12
JournalMechanisms of Ageing and Development
Issue number3
StatePublished - Mar 1989
Externally publishedYes


  • Aging
  • DNA repair
  • Persisting DNA damage
  • Rat skin cells
  • UV-induced pyrimidine dimers

ASJC Scopus subject areas

  • Aging
  • Developmental Biology


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