首页|Impaired suppressive activities of human MUTYH variant proteins against oxidative mutagenesis

Impaired suppressive activities of human MUTYH variant proteins against oxidative mutagenesis

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AIM:To investigate the suppressive activity of MUTYH variant proteins against mutations caused by oxidative lesion,8-hydroxyguanine (8OHG),in human cells.METHODS:p.R154H,p.M255V,p.L360P,and p.P377L MUTYH variants,which were previously found in patients with colorectal polyposis and cancer,were selected for use in this study.Human H1299 cancer cell lines inducibly expressing wild-type (WT) MUTYH (type 2) or one of the 4 above-mentioned MUTYH variants were established using the piggyBac transposon vector system,enabling the genomic integration of the transposon sequence for MUTYH expression.MUTYH expression was examined after cumate induction using Western blotting analysis and immunofiuorescence analysis.The intracellular localization of MUTYH variants tagged with FLAG was also immunofluorescently examined.Next,the mutation frequency in the supF of the shuttle plasmid pMY189 containing a single 8OHG residue at position 159 of the supFwas compared between empty vector cells and cells expressing WT MUTYH or one of the 4 MUTYH variants using a supF forward mutation assay.RESULTS:The successful establishment of human cell lines inducibly expressing WT MUTYH or one of the 4 MUTYH variants was concluded based on the detection of MUTYH expression in these cell lines after treatment with cumate.All of the MUTYH variants and WT MUTYH were localized in the nucleus,and nuclear localization was also observed for FLAG-tagged MUTYH.The mutation frequency ofsupFwas 2.2 x 102in the 8OHG-containing pMY189 plasmid and 2.5× 10-4 in WT pMY189 in empty vector cells,which was an 86-fold increase with the introduction of 8OHG.The mutation frequency (4.7 × 10-3) of supF in the 8OHG-containing pMY189 plasmid in cells overexpressing WT MUTYH was significantly lower than in the empty vector cells (P ＜ 0.01).However,the mutation frequencies of the supF in the 8OHG-containing pMY189 plasmid in cells overexpressing the p.R154H,p.M255V,p.L360P,or p.P377L MUTYH variant were 1.84 × 10-2,1.55 ×x 102,1.91 × 102,and 1.96 × 10-2,respectively,meaning that no significant difference was observed in the mutation frequency between the empty vector cells and cells overexpressing MUTYH mutants.CONCLUSION:The suppressive activities of p.R154H,p.M255V,p.L360R and p.P377L MUTYH variants against mutations caused by 8OHG are thought to be severely impaired in human cells.

8-hydroxyguanineMutationMUTYHMUTYH-associated polyposisOxidative mutagenesissupF forward mutation assaypiggyBac transposonColorectal polyposis

Kazuya Shinmura、Masanori Goto、Hong Tao、Shun Matsuura、Tomonari Matsuda、Haruhiko Sugimura

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Department of Tumor Pathology,Hamamatsu University School of Medicine, Shizuoka 431-3192,Japan

Research Center for Environmental Quality Management, Kyoto University, Shiga 520-0811, Japan

Ministry of Health,Labour and WelfareJapan Society for the Promotion of ScienceJapan Society for the Promotion of ScienceHamamatsu Foundation for Science and Technology PromotionMinistry of Education,Culture,Sports,Science and TechnologyTakeda Science FoundationAichi Cancer Research FoundationSmoking Research Foundation

21-12259035622790378221S0001

2012

10.3748/wjg.v18.i47.6935

世界胃肠病学杂志(英文版)
太原消化病研治中心

世界胃肠病学杂志(英文版)

SCI
影响因子：1.001
ISSN：1007-9327
年,卷(期)：2012.18(47)
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