Increased removal of 3-alkyladenine reduces the frequencies of hprt mutations induced by methyl- and ethylmethanesulfonate in Chinese hamster fibroblast cells.
Nucleic Acids Res
; 22(9): 1670-4, 1994 May 11.
Article
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| MEDLINE
| ID: mdl-8202370
ABSTRACT
We have previously reported the isolation of mammalian cell lines expressing the 3-methyladenine DNA glycosylase I (tag) gene from E. coli. These cells are 2-5 fold more resistant to the toxic effects of methylating agents than normal cells (15). Kinetic measurements of 3-methyladenine removal from the genome in situ show a moderate (3-fold) increase in Tag expressing cells relative to normal as compared to a high (50-fold) increase in exogenous alkylated DNA in vitro by cell extracts. Excision of 7-methylguanine is as expected, unaffected by the tag+ gene expression. The frequency of mutations formed in the hypoxanthine phosphoribosyl transferase (hprt) locus was investigated after methylmethanesulfonate (MMS), ethylmethanesulfonate (EMS), N-nitroso-N-methylurea (NMU) and N-nitroso-N-ethylurea (NEU) exposure. Tag expression reduced the frequency of MMS and EMS induced mutations to about half the normal rate, whereas the mutation frequency in cells exposed to NMU or NEU is not affected by the tag+ gene expression. These results indicate that after exposure to compounds which produce predominantly N-alkylations in DNA, a substantial proportion of the mutations induced is formed at 3-alkyladenine residues in DNA.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Adenina
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Metanosulfonato de Etilo
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Hipoxantina Fosforribosiltransferasa
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Metilmetanosulfonato
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Mutación
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N-Glicosil Hidrolasas
Límite:
Animals
Idioma:
En
Revista:
Nucleic Acids Res
Año:
1994
Tipo del documento:
Article
País de afiliación:
Noruega