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TITLE |
AUTHORS |
KEYWORDS |
MATERIALS & METHODS
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MICROSCOPIC
TECHNIQUES |
SPECIES |
MORPHOLOGY |
CELL
LINE |
| 634 |
Trichothiodystrophy
Fibroblasts Are Deficient in the Repair of Ultraviolet-Induced Cyclobutane Pyrimidine Dimers
and (6–4)Photoproducts |
Yoko
Nishiwaki, Nobuhiko Kobayashi, Kyoko Imoto, Taka-aki Iwamoto, Aya Yamamoto, Sachiko Katsumi,
Toshihiko Shirai, Shigeki Sugiura, Yu Nakamura, Alain Sarasin, Sachiko Miyagawa, and Toshio
Mori |
CPD,
6–4PP, TTD, xeroderma pigmentosum, XPB |
Briefly, cells were cultured
in 35-mm glass-bottom dishes (MatTek,
Ashland, MA) for 2 days.
|
fluorescence
microscopy |
human |
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MSU-1 |
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A photosensitive form of trichothiodystrophy
(TTD) results from mutations in the same XPD gene as the DNArepair- deficient genetic disorder
xeroderma pigmentosum group D (XP-D). Nevertheless, unlike XP, no increase in skin cancers appears
in patients with TTD. Although the ability to repair ultraviolet (UV)-induced DNA damage has
been examined to explain their cancer-free phenotype, the information accumulated to date is
contradictory. In this study, we determined the repair kinetics of cyclobutane pyrimidine dimers
(CPD) and (6–4)photoproducts (6–4PP) in three TTD cell strains using an enzyme-linked
immunosorbent assay. We found that all three TTD cell strains are deficient in the repair of
CPD and of 6–4PP. UV sensitivity correlated well with the severity of repair defects. Moreover,
accumulation of repair proteins (XPB and proliferating cell nuclear antigen) at localized DNA
damage sites, detected using micropore UV irradiation combined with fluorescent antibody labeling,
reflected their DNA repair activity. Importantly, mutations of the XPD gene affected both the
recruitment of the TFIIH complex to DNA damage sites and the TFIIH expression. Our results suggest
that there is no major difference in the repair defect between TTD and XP-D and that the cancer-free
phenotype in TTD is unrelated to a DNA repair defect. |
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