A large-scale in vivo screen to investigate the roles of human genes in <i>Drosophila melanogaster</i>

Understanding the signaling pathways in which genes participate is essential for discovering the etiology of diseases in humans. The model organism, Drosophila melanogaster, has been crucial in understanding the signaling pathways in humans, given the evolutionary conservation of a significant number of genes between the two species. Genetic screens using Drosophila are a useful way of testing large number of genes to study their function and roles within signaling pathways. We conducted a large-scale genetic screen to identify which human genes cause an alteration in the morphology of the Drosophila eye. The GMR-Gal4 was employed to activate a single UAS-human gene in the eye tissue. In total, we screened 802 UAS-human gene stocks, corresponding to 787 human protein-coding genes, for the ability to influence eye development. We found that overexpression of 64 human genes were capable of disrupting eye development, as determined by phenotypic changes in eye texture, size, shape, bristle morphology, and ommatidia organization. Subsequent analysis revealed that the fly genome encodes proteins that are homologous to a majority of the 64 human genes, raising the possibility that overexpression of these transgenes altered eye development by altering the activity of evolutionarily conserved developmental signaling pathways. Consistent with this hypothesis, a secondary screen demonstrated that overexpression of fly homologs produced phenotypes that mimicked those produced by overexpression of the human gene. Our screening has identified 64 human genes capable of inducing phenotypes in the fly, offering a foundation for ongoing research aimed at understanding functionally conserved pathways across species.