Affiliation: San Francisco State University, San Francisco, CA
Keywords: j. endoplasmic reticulum; w. other (gene screening )
The endoplasmic reticulum (ER) is a continuous network of membrane tubules and flattened cisternae involved in protein and lipid synthesis, protein secretion, and post-translational protein modification. A recent study showed that the ER is partitioned asymmetrically in proneuronal cells during mitosis in early Drosophila embryos prior to cell fate determination. Furthermore, this asymmetric ER partitioning relies on the highly conserved ER transmembrane protein Jagunal (Jagn), however, the molecular pathway that drives Jagn-dependent ER partitioning is currently unknown. Here, we hypothesize that Jagn interacts with pathways involving cell fate selection to drive the generation of neuronal cell diversity. To identify possible genes that interact with Jagn, we performed a dominant modifier screen in the Drosophila compound eye. Expression of JagnRNAi in the Drosophila compound eyes results in a rough eye phenotype in 80% of the eyes examined. Based on this, we crossed a collection of deficiency lines (DF) covering the entire 3rd chromosome and examined for either enhancement or suppression of the rough eye phenotype. We have identified ten suppressors and twelve enhancers of Jagn-induced rough eye lines phenotype. We examined these DF lines and selected eight genes involved in functions such as organelle assembly, microtubule attachment, and organelle movements. We then performed a secondary dominant modifier screen in the Drosophila compound eye, using mutants of the selected target genes and mutant gene Dally gave us a similar rough eye phenotype percentage. Dally is important for neuron projection morphogenesis, and positive regulation of signal transduction. We hypothesize that Dally can be working with Jagn as a cell fate determinant. Targets will provide important insight into the molecular pathway involved in ER organization and partitioning.