The Retinal Determination Gene Network in <scp> <i>Drosophila</i> </scp>

The transformation of the eye primordium into a monolayer eye epithelium with identical ommatidial units requires corporate and coordinated efforts of the retinal determination genes. During the process, the same set of retinal determination genes is utilized reiteratively to fulfill distinct functions concerning eye specification, eye patterning, cell proliferation, and cell survival. To achieve this sophisticated goal, instructions sent from the key developmental pathways and the dorsal-ventral patterning genes are incorporated, and connections are built among the retinal determination genes with temporal and spatial specificity. This facilitates the establishment of a multi-directional regulatory network named the retinal determination gene network (RDGN), which influences a wide range of retinal developmental processes. In this review, I will introduce the functional outputs of the RDGN and discuss its complexity by investigating the genetic, molecular, and biochemical interactions between the retinal determination genes. I will also clarify the fundamental roles of the key developmental pathways and the dorsal-ventral patterning genes in organizing RDGN activity. Lastly, advancements in transcriptome and ChIP sequencing technology, which facilitate the identification of the downstream effectors of the RDGN, will enable extensive characterization of the retinal determination mechanisms and allow creation of a more comprehensive picture about eye development.