Replicative and Transcriptional Bypass of Alkylated DNA Lesions in Human Cells
Alkylation is a major type of DNA damage, and DNA alkylation also represents the main mechanism of action for many widely prescribed cancer chemotherapeutic agents. Understanding how alkylated DNA adducts impact the flow of genetic information is important for assessing the implications of these lesions in the etiologies of human diseases, and for improving cancer chemotherapy. In recent years, our laboratory has developed shuttle vector- and mass spectrometry-based approaches to examine the effects of alkylated DNA lesions on DNA replication and transcription in mammalian cells. In this chapter, we summarise the recent findings made from these studies. We review the effects of alkylated lesions on DNA replication, with special emphasis being placed on the influences of regiochemistry in alkylation and size of the alkyl groups. We also compare and contrast the involvement of translesion synthesis polymerases in bypassing different alkylated DNA lesions. Additionally, we discuss how regioisomeric alkylated lesions, situated in the template strand of DNA impact transcription, induce transcriptional mutagenesis, and how they are repaired. Together, we illustrate that the chemical biology approach allows for determination, at the molecular level, how alkylated DNA lesions perturb genomic stability and how they are repaired in cells.