Autoregulation of the Glial Gene reversed polarity in Drosophila melanogaster

During development, cells of the nervous system begin as unspecified precursors and proceed along one of two developmental paths to become either neurons or glia. I seek to understand more about the genes that control this process, focusing on the lesser understood of the cell types, glial cells. Using Drosophila melanogaster as a model system, previous work from my lab and others has established the role of the master regulatory transcription factor Gcm in directing neuronal precursor cells to assume a lateral glial fate. Gcm acts on many target genes, one of which is reversed polarity (repo). repo is necessary for proper glial cell differentiation; once activated, its expression is maintained throughout the life of the fly through currently unknown mechanisms. I propose that repo expression is maintained in an autoregulatory manner, whereby Repo protein acts as a transcription factor on its own regulatory DNA sequence. Three canonical Repo binding sites (RBSs) are located within the 4.3 kb repo cis-regulatory DNA (CRD). Using both S2 cell culture and in vivo expression systems, I have evidence that suggests Repo protein interacts strongly with one of these sites, designated RBS1, to induce the expression of reporter genes. Mutagenesis of RBS1 results in a significant decrease of reporter gene expression in both systems, while RBS2 and RBS3 appear to have no role in autoregulation of repo expression