Journal Article

Comparative repair of the endogenous lesions 8-oxo-7,8-dihydroguanine (8-oxoG), uracil and abasic site by mammalian cell extracts: 8-oxoG is poorly repaired by human cell extracts

Enrico Cappelli, Paolo Degan and Guido Frosina

in Carcinogenesis

Volume 21, issue 6, pages 1135-1141
Published in print June 2000 | ISSN: 0143-3334
Published online June 2000 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/21.6.1135
Comparative repair of the endogenous lesions 8-oxo-7,8-dihydroguanine (8-oxoG), uracil and abasic site by mammalian cell extracts: 8-oxoG is poorly repaired by human cell extracts

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The repair of the endogenous lesions 8-oxo-7,8-dihydroguanine (8-oxoG), uracil (U) and natural abasic site (AP site) was investigated using an in vitro base excision repair assay in which a plasmid substrate containing a single lesion at a defined position was repaired by mammalian cell extracts. Repair replication of an 8-oxoG/cytosine base pair performed by normal human cell extracts was ~5-fold less efficient than repair of a U/adenine base pair and, in turn, the latter was repaired ~10-fold less efficiently than an AP site placed in front of an adenine. A similar pattern of repair capacity for the three lesions was observed in Chinese hamster extracts. Repair of 8-oxoG was performed by the one nucleotide insertion pathway only. The lower repair replication ability of 8-oxoG with respect to U was linked to a lower DNA glycosylase (base removal) activity rather than to inability to process the β-elimination cleaved strand left by the AP lyase activity associated with human oxoguanine DNA glycosylase 1. The data show that DNA repair of 8-oxoG is poor in human cells in comparison with other frequent endogenous lesions.

Keywords: 8-oxoG, 8-oxo-7,8-dihydroguanine; AP site, abasic site; BER, base excision repair; hOGG1, human oxoguanine DNA glycosylase 1; PCNA, proliferating cell nuclear antigen; U, uracil.

Journal Article.  4645 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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