DNA methylation is associated with genetic regulation, cell memory, transposable element silencing, genomic imprinting and repression of pseudo-elements coming from duplicate sequences. Methylation patterns are established, kept and translated via an appropriate functional DNA methylation machinery, which includes a family of proteins classified into three methyltransferase enzyme groups: DNMT1, DNMT3 e DNMT2. DNA methyltransferase 2 (DNMT2) was first identified by searching for novel DNA methyltransferase candidates. DNMT2 does not have a biological function well defined so far; although, it has been shown to be capable of methylating both DNA and RNA, most specifically transfer RNA (tRNA). In human cells, DNMT2 is localized both in the nucleus and in the cytoplasm, being capable to migrate from nucleus to cytoplasm under stress conditions. In cytoplasm, DNMT2 methylates tRNAs, possibly to protect against cleavage events that occur under stress conditions. In several species, including plants, these cleavage events are specific, generating tRNA-derived small RNAs fragments or tRFs. These tRFs might have biological roles in the cell metabolism and differentiation. Most importantly, these tRFS are common among eukaryotes, including plants. Using Arabidopsis thaliana as a model, this work aim to determine the possible roles of DNMT2 during development and stress responses, and its possible association with tRF biogenesis in plants.
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