An RNAi screen for secreted factors and cell-surface players in coordinating neuron and glia development in Drosophila.

The establishment of the functional nervous system requires coordinated development of neurons and glia in the embryo. Our understanding of underlying molecular and cellular mechanisms, however, remains limited. The developing Drosophila visual system is an excellent model for understanding the developmental control of the nervous system. By performing a systematic transgenic RNAi screen, we investigated the requirements of secreted proteins and cell-surface receptors for the development of photoreceptor neurons (R cells) and wrapping glia (WG) in the Drosophila visual system. From the screen, we identified seven genes whose knockdown disrupted the development of R cells and/or WG, including amalgam (ama), domeless (dome), epidermal growth factor receptor (EGFR), kuzbanian (kuz), N-Cadherin (CadN), neuroglian (nrg), and shotgun (shg). Cell-type-specific analysis revealed that ama is required in the developing eye disc for promoting cell proliferation and differentiation, which is essential for the migration of glia in the optic stalk. Our results also suggest that nrg functions in both eye disc and WG for coordinating R-cell and WG development.