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In vitro correction of G.T mispairs to G.C pairs in nuclear extracts from human cells


Wiebauer, K; Jiricny, J (1989). In vitro correction of G.T mispairs to G.C pairs in nuclear extracts from human cells. Nature, 339(6221):234-236.

Abstract

In differentiated cells, only a specific subset of genes is expressed. Recently, several genes have been shown to be transcriptionally inactivated by methylation of cytosine residues, mainly within their promoter sequences. Spontaneous hydrolytic deamination of 5-methylcytosine to thymine, which has been estimated to generate up to 12 G.T mismatched base pairs in the human genome per day, could have a deleterious effect on the expression of such genes. We recently reported that mammalian cells possess a specific repair pathway, which counteracts the mutagenic effects of this deamination by correcting G.T mismatches almost exclusively to G.C pairs. We show here that, in nuclear extracts from HeLa cells, this repair is mediated by excision of the aberrant thymidine monophosphate residue, followed by gap-filling to generate a G.C pair. We also provide preliminary evidence that the initial step of this process involves a DNA glycosylase.

Abstract

In differentiated cells, only a specific subset of genes is expressed. Recently, several genes have been shown to be transcriptionally inactivated by methylation of cytosine residues, mainly within their promoter sequences. Spontaneous hydrolytic deamination of 5-methylcytosine to thymine, which has been estimated to generate up to 12 G.T mismatched base pairs in the human genome per day, could have a deleterious effect on the expression of such genes. We recently reported that mammalian cells possess a specific repair pathway, which counteracts the mutagenic effects of this deamination by correcting G.T mismatches almost exclusively to G.C pairs. We show here that, in nuclear extracts from HeLa cells, this repair is mediated by excision of the aberrant thymidine monophosphate residue, followed by gap-filling to generate a G.C pair. We also provide preliminary evidence that the initial step of this process involves a DNA glycosylase.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Molecular Cancer Research
07 Faculty of Science > Institute of Molecular Cancer Research
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:1989
Deposited On:09 Jul 2010 08:55
Last Modified:07 Dec 2017 02:37
Publisher:Nature Publishing Group
ISSN:0028-0836
Publisher DOI:https://doi.org/10.1038/339234a0
PubMed ID:2716851

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