Temporally-segregated dual functions for Gfi1 in the development of retinal direction-selectivity

There is great diversity in retinal ganglion cells subtypes in the mouse retina, but little is known about the molecular factors required to generate this subtype diversity. Here, we identify the transcription factor Gfi1 as a conserved driver of differentiation specifically in two downward-tuned direction selective ganglion cells (DSGCs). Further, we describe a post-differentiation role for Gfi1 in regulating dendritic development of Down ON-type DSGCs crucial for their ability to detect downward motion. These results define novel temporally-segregated dual functions for Gfi1 in the development of retinal direction-selective circuits, and they provide a framework for understanding fundamental mechanisms underlying direction-selectivity in the retina.