View Program - 63rd Annual Drosophila Research Conference

Drosophila epidermal growth factor receptor (Egfr) signaling plays a critical role in many aspects of development including oogenesis, embryogenesis, and proper development of wing and eye tissues. For example, during wing development, Egfr signaling helps specify vein tissues, and in the ovary Egfr signaling is known to establish the body axes during oogenesis. Microarray screens by our lab and others have identified potential downstream transcriptional targets of the Egf receptor using the Drosophila ovary as a model system. Our initial work compared gene expression in fly ovaries where the activity of the Egfr pathway was reduced (gurken mutant), wild-type (OreR), or constitutively active (CY2/λTop). We have employed a number of approaches to further investigate the expression, biological function, and mechanism of action of a subset of putative genes of interest, focusing primarily on genes of previously unknown function. A small-scale functional screen using available collections of UAS-RNAi transgenic flies and P-element insertion lines was used to investigate the possible functions of a group of these novel EGFR-responsive genes. A number of these genes were observed to play roles in normal eggshell structure and morphogenesis. Gene mutant/knockdown phenotypes include decreased chorionic integrity, shortened eggs, and various dorsal appendage malformations, as well as decreased fertility. We have used the CRISPR-Cas9 system to create mutations in some of these “morphogenesis genes.” These mutants have so far recapitulated the previously observed phenotypes, and in at least one case resulted in the observation of an additional phenotype in our null mutant, not seen in the original P-element insertion. We are currently using these CRISPR mutants for further study and characterization of the genes.

Characterization of novel Drosophila Egf receptor signaling targets with roles in eggshell structure and morphology

**Characterization of novel Drosophila Egf receptor signaling targets with roles in eggshell structure and morphology**