Keywords: f. eye disc; d. compartments and boundaries
The development of an organism relies on interactions between genes within specific signaling networks across diverse tissues. The regulatory genes of these networks are responsible for programming the proliferation, cell fate specification, and differentiation of unique cell populations that create a tissue pattern central to organogenesis. A well-characterized family of developmental regulatory genes is represented by the T-box (Tbx) gene family that encodes transcription factor (TF) proteins sharing an evolutionarily conserved T-box DNA-binding domain. The Drosophila melanogaster T-box TF, midline (mid), has been shown to play an important role in cell fate determination and patterning within developing tissues such as the wing and leg imaginal discs as well as the embryonic nervous system. The Drosophila Transcription Growth Factor-beta (TGF-β) homolog decapentaplegic (dpp) is expressed within the morphogenetic furrow (MF) of third-instar larval eye imaginal discs which is a region critical for cell fate specification. Previous studies have uncovered a regulatory relationship between mid and dpp in cell fate specification and patterning. We hypothesize that mid and dpp execute a long-range cell signaling mechanism to regulate cell specification within the MF and patterning anterior of the MF. Using the UAS-Gal4 binary expression system, we found that Dpp maintains the proper boundaries of mid and Groucho (Gro) expression within the eye imaginal disc. We are now investigating whether the Notch-Delta signaling pathway plays a role in modulating dpp and mid activity to pattern the eye disc.