Analysis of UV-B-induced DNA damage and its repair in heat-shocked skin cells

Citation
T. Schmidt-rose et al., Analysis of UV-B-induced DNA damage and its repair in heat-shocked skin cells, J PHOTOCH B, 53(1-3), 1999, pp. 144-152
Citations number
44
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY
ISSN journal
10111344 → ACNP
Volume
53
Issue
1-3
Year of publication
1999
Pages
144 - 152
Database
ISI
SICI code
1011-1344(199911/12)53:1-3<144:AOUDDA>2.0.ZU;2-5
Abstract
The heat-shock response is a cellular defence mechanism against environment al stresses that is evolutionarily conserved from bacteria to man. Numerous reports demonstrate the beneficial effects of heat-shock protein induction on cell survival under toxic or oxidative stress, e.g., in cardiac and cer ebral ischemia or prior to organ transplantation. However, there is little data on the effects of heat treatment on damage caused by UV irradiation. A pplying three independent techniques, we have tested the influence of therm al pretreatment of skin cells (1 h, 43 degrees C) on the initial extent of UV-B induced DNA damage and its subsequent repair. For cultured human epide rmal keratinocytes and dermal fibroblasts we can show reduced levels of nuc leotide-excision-repair-associated DNA strand incision in the comet assay. Moreover, immunostaining and how cytometric quantitation of thymidine dimer s immediately and one day after irradiation, respectively, reveal that the initial DNA damage is not (keratinocytes) or only moderately (fibroblasts) lower in heat-shocked cells as compared to untreated controls. However, exc ision repair of dimers is significantly attenuated during the first 24 h in both cell types. Furthermore, using a modified host-cell reactivation assa y, we are able to demonstrate that repair of UV-B-damaged plasmid DNA is lo wer if the transfected cells are previously heat shocked. In summary, heat treatment (1 h, 43 degrees C) inducing heat-shock proteins reduces nucleoti de excision repair of UV-B-mediated DNA lesions in fibroblasts and keratino cytes during the following 24 h. This is not necessarily caused by elevated heat-shock protein levels themselves. Possibly the direct thermal damage o f repair enzymes is more severe than the potential protective effects of he at-shock proteins. (C)1999 Elsevier Science S.A. All rights reserved.