New York Area Drosophila Discussion Group

New York Area Drosophila Discussion Group meetings will held in the evenings from 6 to 8 PM and will be followed by a reception to which all participants are welcome. Each meeting will include four presentations by graduate students and post-docs selected from area laboratories by the program committee with an emphasis on new and emerging data.

Presentations

Crag is a Novel Regulator of Epithelial Architecture and the Polarized Deposition of Basement Membrane Proteins
Natalie Denef, Princeton University (Schupbach Lab)

Contact with the basement membrane (BM) provides an important spatial cue required for orienting the apical-basal axis of epithelial cells. The polarized secretion of BM proteins and their restricted accumulation on the basal side of epithelia is therefore crucial in ensuring a robust tissue organization. The molecular and cellular mechanisms underlying the polarized trafficking of BM proteins remain largely elusive. In a genetic screen for genes regulating epithelial organization in Drosophila we have identified Crag (Calmodulin binding protein related to a Rab3 GDP/GTP exchange protein) as the first component required specifically for the polarized deposition of BM proteins.

Heterochronic Functions of the Drosophila let-7 and miR-125 microRNAs During Metamorphosis
Elizabeth E. Caygill, Columbia University (Johnston Lab)

let-7 and mir-125 are co-expressed homologs of temporally expressed microRNAs which function as heterochronic genes in the nematode, C. elegans. We have made a mutant of the let-7 locus in Drosophila that disrupts expression of let-7 and miR-125. This mutation leads to specific defects during metamorphosis, including delayed timing of cell cycle exit in the wing and delayed development of abdominal neuromuscular junctions (NMJs). Our data suggest that these defects are primarily due to loss of let-7. The mistiming of metamorphic processes in the mutant suggests that the heterochronic role of these microRNAs is conserved in Drosophila.

Understanding Cross-Talk Between the Wg and RTK Signaling Pathways in the Drosophila Eye
Emily R. Olson, New York University (Dasgupta Lab)

The Wnt/wingless and Receptor Tyrosine Kinase (RTK) signaling pathways are two of a core set of evolutionarily conserved signaling pathways. Aberrant Wnt and RTK signaling have both been linked to multiple human diseases including cancer. In our recent cell-based RNAi screen aimed at isolating novel regulators of the Wg pathway, we identified yan, an ETS transcription factor of the RTK pathway, as a putative negative regulator. I will describe our initial studies on Yan function and a putative molecular mechanism for its inhibitory role in the regulation of the Wg pathway in vivo.

Adhesion and Signaling: Patterning the Pupal Eye
Sujin Bao, Mount Sinai School of Medicine (Cagan Lab)

Cell adhesion is essential for organizing cells into tissues and organs with a variety of forms and shapes during animal development. However, how cell adhesion drives cells into characteristic patterns is poorly understood. At the pupal stage of the developing Drosophila compound eye, disorganized epithelial pigment cells are rearranged into one-cell thick hexagonal lattice. Here we show that cell adhesion mediated by transmembrane adhesion molecules Hibris and Roughest is essential for organizing pigment cells into the hexagonal pattern in the eye. Further, we show that Notch signaling is also required for organizing cells into hexagons. Notch signaling is both necessary and sufficient for specifying primary pigment cells and controlling cell shape. In addition, we provide evidence that Notch signaling is both sufficient and necessary for regulating hibris expression. Thus, our data suggests a link between Notch signaling and cell adhesion.