POU DOMAIN FACTOR BRN-3B IS REQUIRED FOR THE DEVELOPMENT OF A LARGE SET OF RETINAL GANGLION-CELLS

The three members of the Brn-3 family of POU domain transcription fact ors are found in highly restricted sets of central nervous system neur ons. Within the retina, these factors are present only within subsets of ganglion cells. We show here that in the developing mouse retina, B rn-3b protein is first observed in presumptive ganglion cell precursor s as they begin to migrate from the zone of dividing neuroblasts to th e future ganglion cell layer, and that targeted disruption of the Brn- 3b gene leads in the homozygous state to a selective loss of 70% of re tinal ganglion cells. In Brn-3b (-/-) mice other neurons within the re tina and brain are minimally or not at all affected. These experiments indicate that Brn-3b plays an essential role in the development of sp ecific ganglion cell types.