Molecular Mechanisms Regulating Drosophila Visual System Development
My lab is interested in the molecular mechanism controlling the development of the visual system in Drosophila. We are primarily studying (1) specification of the eye fate, (2) control of cell proliferation in eye disc, and (3) brain-eye interaction.
The Drosophila eye and antenna arise from a single epithelium disc called the eye-antennal imaginal disc. Genes specifying the eye fate and antenna fate have been identified. However, the mechanism for subdividing this disc into distinct eye and antennal primordia and the interaction between the two parts is not clear. We (in collaboration with Al Courey, UCLA) have identified the mis-expression of a single gene Dip3, encoding a MADF/ BESS family transcription factor, can cause antennal duplication and eye-to-antenna transformation. We are exploring the molecular mechanism accounting for this developmental fate change.
For the control of cell proliferation during eye development, it was known that the localized activation of Notch receptor at the dorso-ventral midline is critical for the growth in the entire eye disc. We found that Notch signal induces the transcription of the Pax gene eye gone (eyg). Eyg then induces the transcription of unpaired (upd) which encodes a ligand for the Jak/STAT signaling pathway. The locally expressed Upd protein then distributes over a long distance to promote cell proliferation in the eye disc. This explained how a localized Notch signal can promote global cell proliferation. Our results have suggested that the transcriptional regulation of both eyg and upd requires signals in addition to Notch. We are trying to define the molecular mechanisms in specifying the spatial and temporal expression pattern of eyg and upd. Our results also suggested that the Upd/ Jak/STAT signal can be regulated by novel mechanisms. This study is in progress.
We have recently begun to study the interaction between the photoreceptor neurons and glia cells, including glia in the optic lobe of the brain and the retinal basal glia (RBGs) that migrate from the brain into the eye disc. We are studying the mechanisms regulating the proliferation, survival, migration and distribution of the glia within the visual system, and also their effects on photoreceptor development and functions.