Journal Article

Low amounts of the DNA repair XPA protein are sufficient to recover UV-resistance

Alysson R. Muotri, Maria C.N. Marchetto, Miriam F. Suzuki, Kayo Okazaki, Claudimara F.P. Lotfi, Gabriela Brumatti, Gustavo P. Amarante-Mendes and Carlos F.M. Menck

in Carcinogenesis

Volume 23, issue 6, pages 1039-1046
Published in print June 2002 | ISSN: 0143-3334
Published online June 2002 | e-ISSN: 1460-2180 | DOI:
Low amounts of the DNA repair XPA protein are sufficient to recover UV-resistance

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DNA integrity is threatened by the damaging effects of physical and chemical agents that can affect its function. Nucleotide excision repair (NER) is one of the most known and flexible mechanisms of DNA repair. This mechanism can recognize and remove damages causing DNA double-helix distortion, including the cyclobutane pyrimidine dimers (CPDs) and the pyrimidine-pyrimidone (6–4) photoproducts, promoted by ultraviolet light (UV). The human syndrome xeroderma pigmentosum (XP) is clinically characterized chiefly by the early onset of severe photosensitivity of the exposed regions of the skin, a very high incidence of skin cancers and frequent neurological abnormalities. The xpa gene seems to be involved during UV damage recognition, in both global genome repair (GGR) and transcription-coupled repair (TCR). The modulation of xpa expression may modify the DNA repair rate in the cell genome, providing a valuable contribution to an understanding of the NER process. The controlled expression of the cDNA xpa in XP12RO deficient cells was achieved through the transfection of a muristerone-A inducible vector, pINXA. The INXA15 clone shows good induction of the XPA protein and total complementation of XP12RO cell deficiency. Overexpression of this protein resulted in UV cell survival comparable to normal control human cells. Moreover, low expression of the XPA protein in these cells is sufficient for total complementation in cellular UV sensitivity and DNA repair activity. These data demonstrate that XPA protein concentration is not a limiting factor for DNA repair.

Keywords: CPDs, cyclobutane pyrimidine dimers; ESS, endonuclease-sensitive site; GGR, global genome repair; Mu, muristerone A hormone; NER, nucleotide excision repair; TCR, transcription-coupled repair; UDS, unscheduled DNA repair; UV, ultraviolet; XPA, xeroderma pigmentosum group A.

Journal Article.  6769 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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