First Department of Pathology, Hamamatsu University School of Medicine, Japan.
Hum Mutat. 2010 Nov;31(11):E1861-74. doi: 10.1002/humu.21363.
Biallelic inactivating germline mutations in the base excision repair MUTYH (MYH) gene have been shown to predispose to MUTYH-associated polyposis (MAP), which is characterized by multiple colorectal adenomas and carcinomas. In this study, we successfully prepared highly homogeneous human MUTYH type 2 recombinant proteins and compared the DNA glycosylase activity of the wild-type protein and fourteen variant-type proteins on adenine mispaired with 8-hydroxyguanine, an oxidized form of guanine. The adenine DNA glycosylase activity of the p.I195V protein, p.G368D protein, p.M255V protein, and p.Y151C protein was 66.9%, 15.2%, 10.7%, and 4.5%, respectively, of that of the wild-type protein, and the glycosylase activity of the p.R154H, p.L360P, p.P377L, p.452delE, p.R69X, and p.Q310X proteins as well as of the p.D208N negative control form was extremely severely impaired. The glycosylase activity of the p.V47E, p.R281C, p.A345V, and p.S487F proteins, on the other hand, was almost the same as that of the wild-type protein. These results should be of great value in accurately diagnosing MAP and in fully understanding the mechanism by which MUTYH repairs DNA in which adenine is mispaired with 8-hydroxyguanine.
碱基切除修复 MUTYH（MYH）基因的双等位基因失活种系突变已被证明易患 MUTYH 相关息肉病（MAP），其特征是多发性结直肠腺瘤和癌。在这项研究中，我们成功制备了高度均一的人 MUTYH 型 2 重组蛋白，并比较了野生型蛋白和 14 种变异型蛋白在腺嘌呤与 8-羟基鸟嘌呤（鸟嘌呤的氧化形式）错配时的 DNA 糖基化酶活性。p.I195V 蛋白、p.G368D 蛋白、p.M255V 蛋白和 p.Y151C 蛋白的腺嘌呤 DNA 糖基化酶活性分别为野生型蛋白的 66.9%、15.2%、10.7%和 4.5%，而 p.R154H、p.L360P、p.P377L、p.452delE、p.R69X 和 p.Q310X 蛋白以及 p.D208N 阴性对照形式的糖基化酶活性则严重受损。另一方面，p.V47E、p.R281C、p.A345V 和 p.S487F 蛋白的糖基化酶活性与野生型蛋白几乎相同。这些结果对于准确诊断 MAP 以及充分了解 MUTYH 修复腺嘌呤与 8-羟基鸟嘌呤错配的 DNA 的机制具有重要价值。
