Molecular and Cellular Biology
Geisel School of Medicine
Interstrand cross-links (ICLs) make up a unique class of DNA lesions in which both strands of the double helix are covalently joined, precluding strand opening during replication and transcription. The repair of DNA ICLs has become a focus of study since ICLs are recognized as the main cytotoxic lesion inflicted by an array of alkylating compounds used in cancer treatment. As is the case for double-strand breaks, a damage-free homologous copy is essential for the removal of ICLs in an error-free manner. However, recombination-independent mechanisms may exist to remove ICLs in an error-prone fashion. We have developed an in vivo reactivation assay that can be used to examine the removal of site-specific mitomycin C-mediated ICLs in mammalian cells. We found that the removal of the ICL from the reporter substrate could take place in the absence of undamaged homologous sequences in repair-proficient cells, suggesting a cross-link repair mechanism that is independent of homologous recombination. Systematic analysis of nucleotide excision repair mutants demonstrated the involvement of transcription-coupled nucleotide excision repair and a partial requirement for the lesion bypass DNA polymerase eta encoded by the human POLH gene. From these observations, we propose the existence of a recombination-independent and mutagenic repair pathway for the removal of ICLs in mammalian cells.
Zheng H, Wang X, Warren AJ, Legerski RJ, Nairn RS, Hamilton JW, Li L. Nucleotide excision repair- and polymerase eta-mediated error-prone removal of mitomycin C interstrand cross-links. Mol Cell Biol. 2003 Jan;23(2):754-61. doi: 10.1128/mcb.23.2.754-761.2003. PMID: 12509472; PMCID: PMC151552.
Dartmouth Digital Commons Citation
Zheng, H.; Wang, X.; Warren, A. J.; Legerski, R. J.; Nairn, Rodney S.; Hamilton, Joshua W.; and Li, Lei, "Nucleotide Excision Repair- and Polymerase Eta-Mediated Error-Prone Removal of Mitomycin C Interstrand Cross-Links" (2003). Dartmouth Scholarship. 1803.