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

Authors: You, Changjun; Wang, Pengcheng; Nay, Stephanie L; Wang, Jianshuang; Dai, Xiaoxia; O'Connor, Timothy R; Wang, Yinsheng

Published In ACS Chem Biol, (2016 May 20)

Abstract: Environmental and endogenous genotoxic agents can result in a variety of alkylated and carboxymethylated DNA lesions, including N3-ethylthymidine (N3-EtdT), O(2)-EtdT, and O(4)-EtdT as well as N3-carboxymethylthymidine (N3-CMdT) and O(4)-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, O(2)-EtdT, O(4)-EtdT, N3-CMdT, or O(4)-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.

PubMed ID: 26930515

MeSH Terms: AlkB Homolog 2, Alpha-Ketoglutarate-Dependent Dioxygenase/metabolism*; AlkB Homolog 3, Alpha-Ketoglutarate-Dependent Dioxygenase/metabolism*; Alkylation; Animals; Cell Line; DNA Adducts/chemistry; DNA Adducts/genetics; DNA Adducts/metabolism*; DNA Glycosylases/metabolism*; DNA Repair; Humans; Mice; Thymidine/analogs & derivatives; Thymidine/chemistry; Thymidine/genetics; Thymidine/metabolism