The multiple roles of the helix-loop-helix protein extramacrochaetae in drosophila eye development

My graduate research has focused on how the helix-loop-helix protein, Extramacrochaetae (Emc), is involved in regulation of retinal development in Drosophila. The maturing Drosophila eye is a single layer of epithelial cells that undergo dramatic growth and patterning throughout development until ultimately becoming an intricately structured adult compound eye. The processes of patterning and proliferation must be tightly coordinated to ensure that the proper number of retinal cell types are created and are appropriately arranged. I have found that Emc is able to regulate the rate of retinal patterning by controlling the speed of a front of differentiation known as the morphogenetic furrow. My data suggests that Emc functions to restrict high levels of Hedgehog (Hh) signaling by regulating the transcriptional activator CiACT , and in doing so, prevents inappropriate advancement of the morphogenetic furrow. Additionally, a loss of emc leads to ectopic furrow formation at the dorsal and ventral lateral margins and is required for Wingless (Wg) signaling in the ventral compartment of the eye disc. Before morphogenetic furrow initiation, the eye is divided into Dorsal and Ventral domains, after which a large amount of cellular proliferation occurs to provide enough cells to constitute a functional adult eye. My studies of emc have uncovered an unknown function of Emc in Dorsal/Ventral (D/V) patterning and proliferation. Experimental data shows that Emc functions downstream of Notch to promote four-jointed expression along the midline. Emc is also able to mediate the effect that Daughterless has on growth inhibition in the eye, finally linking the emc mutant growth phenotype with a target sequestered by Emc in vivo.