Functional characterization of Dnmt2 in Drosophila

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Dnmt2 enzymes represent a central paradigm for understanding the biological function of cytosine-5 methylation, a nucleic acid modification that has been associated with numerous human diseases, including cancer. Dnmt2 utilizes the catalytic mechanism of DNA methyltransferases, but robust catalytic activity has only been observed at tRNA substrates. This makes Dnmt2 enzymes well suited to investigate the biological function of cytosine methylation in RNA and DNA. We will focus on the characterization of Dnmt2 in Drosophila and in the mouse, because Drosophila has been proven to be highly suitable for combined molecular, biochemical and genetic approaches whereas the mouse model links these observations to mammalian biology. Our previous findings allowed us to establish Dnmt2 as a multi-substrate tRNA methyltransferase and to identify a role of these enzymes in cellular stress responses. We will now (1) analyze the function of Dnmt2-dependent tRNA fragmentation in stress signaling, (2) determine the interaction of Dnmt2 with small RNA silencing pathways, (3) characterize differentiation phenotypes of cytosine-5 tRNA methylation-deficient mouse models and (4) determine cytosine-5 RNA methylation patterns on the whole-transcriptome level.