Transcriptional Regulation of Notch target E(spl)mÎ3 by Tramtrack69 and Putzig in Drosophila melanogaster

Hunter, Emily, "Transcriptional Regulation of Notch target E(spl)mγ by Tramtrack69 and Putzig in Drosophila melanogaster" (2012). Abstract The Notch pathway plays an important role during development by regulating whether a cell takes on a neuronal or non-neuronal cell fate in the peripheral nervous system of Drosophila melanogaster. When Notch signaling is present in a cell, the cell is prevented from becoming a sensory organ precursor because transcription of proneural genes is blocked by Notch downstream targets such as the Enhancer of Split [E(spl)] complex. Given the importance of neuronal vs. non-neuronal cell fate determination during development, tight regulation of the individual E(spl) genes, such as E(spl)mγ, must occur to ensure proper differentiation. Focusing on the transcriptional regulation of E(spl)mγ, it is possible that this gene is regulated by Tramtrack69 (Ttk69), a transcriptional repressor known to associate with Notch downstream targets, and by Putzig (Pzg), a transcriptional activator that interacts with both Notch downstream targets and TTK69. A two-pronged approach was used to determine whether E(spl)mγ is regulated by Ttk69 and Pzg. Changes in the expression patterns of E(spl)mγ were analyzed when ectopic TTK69 was driven in the imaginal eye discs of D. melanogaster larvae. I hoped to examine changes in E(spl)mγ expression patterns in the presence of ectopic Pzg , but no results were acquired. Using S2 transfections, the changes in expression levels of E(spl)mγ in relation to varying treatments of TTK69, Pzg, and MAM (a transcriptional activator of E(spl)mγ) were analyzed. The results of the ectopic TTK69 analysis indicate TTK69 specifically suppresses expression of E(spl)mγ in vivo. The results of the S2 cell transfection indicate Putzig requires the presence of Intracellular Notch (ICN) and MAM to upregulate expression of E(spl)mγ. TTK69 is capable of blocking this upregulation in the presence of MAM, Pzg, and ICN. Overall, the results provide evidence that both TTK69 and Pzg regulate expression levels of E(spl)mγ.