Human 2'-O-ribose methyltransferases and the oxidative stress response

Abstract

Exposure to environmental toxicants that induce reactive oxygen species (ROS) can damage DNA, proteins and lipids to promote diseases such as cancer. ROS detoxification processes mitigate oxidative stress-induced damage and prevent disease. Conversely, defects in ROS detoxification capacity are implicated in disease etiology. In fact, cancer cells are known to adapt to aberrantly high ROS by up-regulating anti-oxidant defense systems. Recently published work describes a new tRNA epigenetic mechanism of ROS mitigation involving the tRNA methyltransferase, Alkbh8. Additionally, we have new data that implicates a class of ribose methyltransferases (distinct from Alkbh8) in ROS defense and cancer cell adaptive responses. In fact, two such human enzymes stand out because of their links to diseases associated with aberrant ROS production: 1) TARBP1, which undergoes frequent gene amplification in ovarian and breast cancers, and 2) FTSJ1, which is mutated in a familial form of mental retardation, associated with neuronal dysfunction. From these collective observations (i.e. 2'-O-ribose methylation of tRNAs in response to ROS stress and potential methyltransferase deregulation in cancer) we think that human 2'-O-ribose methyltransferases act on stress-related tRNAs to enable cancer cells to adapt to inherently high levels of ROS. We plan to explore this possibility using a multidisciplinary approach that combines ROS stress-induced cellular phenotypes with a direct analysis of tRNA modification chemistries using mass spectrometry. Our approach has the potential to move the field of RNA epigenetics forward, in addition to giving new insight into the complexities of protein translation, with implications for cancer etiology.