An Investigation of Distal Enhancer-Enhancer and Enhancer-Promoter Communication for the brinker Locus in Drosophila melanogaster

Abstract

In metazoans, the transcription of many developmental patterning genes is highly regulated both spatially and temporally to ensure proper gene expression in the developing embryo. In Drosophila melanogaster, these genes often have multiple enhancers that are believed to work in pairs with overlapping activity. Because most of the studies on these genes have been done using reporter plasmids and by performing in-situ hybridization to evaluate the expression of these reporters, the exact mechanism for how these enhancers communicate is not well understood. However, this method lacks temporal resolution and quantitative accuracy. By utilizing new sophisticated live imaging techniques such as the MS2 reporter system to monitor the levels and timing of the brinker (brk) locus, I will be able to better understand the temporal and spatial aspects of developmental gene expression especially concerning distal enhancer-enhancer communication in Drosophila. Previous evidence produced by Levine Lab suggests, that these pair of enhancers do not necessarily act in the widely accepted primary and “shadow” enhancer model but interact with each other in an additive manner. It is still not completely understood how distal enhancers loop to promoters to initiate transcription. GAGA factor (GAF) is a putative genome architectural protein that we suspect may facilitate the looping and binding of enhancers to their gene’s promoters. To further investigate this potential additive property of enhancers and GAF’s role in enhancer-promoter communication, we will focus on the interaction between two distally located enhancers of the early brk gene expression by temporally monitoring and measuring the levels of nascent brk transcripts using the MS2 reporter system.