Identifying Chromatin Binding Sites of Ten Eleven Translocation Protein dTet in Drosophila Melanogaster Central Nervous System

Abstract

Epigenetics refers to changes in gene expression without changing the DNA sequence and it has been shown to be involved in normal development and disease. There are various mechanisms through which gene expression is modulated and that includes histone modifications, micro-RNA, noncoding RNA and DNA methylation. DNA methylation is the focus of this study, and it refers to the addition of a methyl group on the cytosine residue by a family of DNA methyltransferases (DNMTs). Methylation occurs at CpG sites near gene promoters and silences gene expression. The reverse process, which is DNA demethylation, turns genes “on” and is facilitated by TET proteins as they are involved in the oxidation of 5-methyl cytosine (5mC). There are 3 mammalian TET proteins TET (1-3). Compared to mammals, Drosophila Melanogaster expresses one TET (dTet) that is most similar to TET3 based on sequence similarity in the catalytic domain. dTet is expressed in muscles and imaginal discs in embryos, in neurons during development, and in the brain specifically in the midline glia and optic chiasm of 3rd instar larvae. The substrate of dTet are 5mC on RNA, and 6-methyl Adenine on DNA unlike the mammalian system which is 5mC on both DNA and RNA. In this study we opt to investigate dTet binding to DNA as well as assess m6A mark on DNA of Drosophila brain using chromatin immunoprecipitation sequencing (ChIP-seq). This study will contribute to better understanding of dTet role in gene regulation that could be extrapolated to the mammalian nervous system. The findings of this study could additionally shed light on possible therapeutic targets for many diseases, for example cancer, where gene regulation is disrupted.