Temporally segregated functions for Gfi1 in the development and maintenance of direction selectivity in the vertebrate retina

Retinal direction selectivity is a vital component of many visual functions, including motion processing and gaze stabilization. Direction selectivity emerges from specialized retinal ganglion cells (RGCs) that encode motion along a single preferred direction. In the mouse retina, direction-selective (DS) RGC (DSGC) subtypes are quite diverse, but little is known about the genetic programs required to generate this diversity. Moreover, it is unclear whether transcription factors that specify distinct DS subtypes play additional roles in their maintenance or maturation. Here, we show that the transcription factor Gfi1 is a conserved regulator of two DSGC subtypes tuned to vertical motion: down ON-type DSGCs (D-oDSGCs) and F-mini ONs. We show that Gfi1 promotes early differentiation of both subtypes but has distinct roles later in their development. In D-oDSGCs, Gfi1 is required postnatally for directing dendritic elaboration, and loss of Gfi1 disrupts D-oDSGC-mediated downward motion-tracking behavior, whereas in F-mini ONs, Gfi1 is required for continued cell survival . These findings reveal shared and divergent temporally segregated functions of Gfi1 in the assembly of retinal DS circuits.