Project Summary: A long-standing question in biology is how cells respond to multiple signaling inputs with a specific response. This proposal investigates the intersections of Notch and Hh signaling pathways, which are widely required during development, and basic mechanisms congenital eye disease. Both signaling systems regulate cell proliferation, morphogenesis, cell polarity, differentiation, apoptosis and stem cell maintenance. However, the spatiotemporal contexts for each differs at the cellular and tissue levels during optic vesicle morphogenesis and growth. This proposal will use in vivo complex conditional (cre-lox) mouse genetics, mouse transgenics, embryology, iPSC-derived retinal organoids, histology, immunohistochemistry, confocal microscopy, in situ hybridization, qPCR and bioinformatics technologies to investigate basic, mechanistic questions about the initiation and progression of eye formation from the embryonic brain. We will address several important questions: 1) What are the spatial and temporal constraints for Notch versus Hh in controlling growth, morphogenesis, patterning, tissue polarity and the timing of differentiation in the optic vesicle, optic cup, RPE and optic stalk? 3) What are the optimal conditions by which Notch and Shh pathways contribute to the generation of retinal ganglion cell and cone photoreceptor neurons in retinal organoid culture? 1) How do the Notch and Hh pathways regulate the eye expression domains of a common target gene, Hes1?