Roles of Aag, Alkbh2, and Alkbh3 in the Repair of Carboxymethylated and Ethylated Thymidine Lesions

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• 作者：Changjun You ; Pengcheng Wang ; Stephanie L. Nay ; Jianshuang Wang ; Xiaoxia Dai ; Timothy R. O’Connor ; Yinsheng Wang
• 刊名：ACS Chemical Biology
• 出版年：2016
• 出版时间：May 20, 2016
• 年：2016
• 卷：11
• 期：5
• 页码：1332-1338
• 全文大小：445K
• 年卷期：0
• ISSN：1554-8937

文摘

Environmental and endogenous genotoxic agents can result in a variety of alkylated and carboxymethylated DNA lesions, including N3-ethylthymidine (N3-EtdT), O²-EtdT, and O⁴-EtdT as well as N3-carboxymethylthymidine (N3-CMdT) and O⁴-CMdT. By using nonreplicative double-stranded vectors harboring a site-specifically incorporated DNA lesion, we assessed the potential roles of alkyladenine DNA glycosylase (Aag); alkylation repair protein B homologue 2 (Alkbh2); or Alkbh3 in modulating the effects of N3-EtdT, O²-EtdT, O⁴-EtdT, N3-CMdT, or O⁴-CMdT on DNA transcription in mammalian cells. We found that the depletion of Aag did not significantly change the transcriptional inhibitory or mutagenic properties of all five examined lesions, suggesting a negligible role of Aag in the repair of these DNA adducts in mammalian cells. In addition, our results revealed that N3-EtdT, but not other lesions, could be repaired by Alkbh2 and Alkbh3 in mammalian cells. Furthermore, we demonstrated the direct reversal of N3-EtdT by purified human Alkbh2 protein in vitro. These findings provided important new insights into the repair of the carboxymethylated and alkylated thymidine lesions in mammalian cells.