Mutator phenotype of MUTYH-null mouse embryonic stem cells

Seiki Hirano, Yohei Tominaga, Akimasa Ichinoe, Yasuhiro Ushijima, Daisuke Tsuchimoto, Yoko Honda-Ohnishi, Toshio Ohtsubo, Kunihiko Sakumi, Yusaku Nakabeppu

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Abstract

To evaluate the antimutagenic role of a mammalian mutY homolog, namely the Mutyh gene, which encodes adenine DNA glycosylase excising adenine misincorporated opposite 8-oxoguanine in the template DNA, we generated MUTYH-nuR mouse embryonic stem (ES) cells. In the MUTYH-null cells carrying no adenine DNA glycosylase activity, the spontaneous mutation rate increased 2-fold in comparison with wild type cells. The expression of wild type mMUTYH or mutant mMUTYH protein with amino acid substitutions at the proliferating cell nuclear antigen binding motif restored the increased spontaneous mutation rates of the MUTYH-null ES cells to the wild type level. The expression of a mutant mMUTYH protein with an amino acid substitution (G365D) that corresponds to a germ-line mutation (G382D) found in patients with multiple colorectal adenomas could not suppress the elevated spontaneous mutation rate of the MUTYH-null ES cells. Although the recombinant mMUTYH(G365D) purified from Escherichia coli cells had a substantial level of adenine DNA glycosylase activity as did wild type MUTYH, no adenine DNA glycosylase activity was detected in the MUTYH-null ES cells expressing the mMUTYH(G365D) mutant protein. The germ-line mutation (G382D) of the human MUTYH gene is therefore likely to be responsible for the occurrence of a mutator phenotype in these patients.

Original languageEnglish
Pages (from-to)38121-38124
Number of pages4
JournalJournal of Biological Chemistry
Volume278
Issue number40
DOIs
Publication statusPublished - Oct 3 2003

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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