Figure 11

Model of Vsx2 function during early retinal development. As a part of the eye field transcription factor (EFTF) network, Lhx2 provides the competence for the optic neuroepithelium to express Mitf and Vsx2. Pigmentation program signals (that is, TGF-beta family) activate Mitf, and in turn, retinal program signals (FGFs, BMPs) activate Vsx2. Vsx2 then represses Mitf in the retinal domain. Once the retinal program is initiated, Vsx2 promotes RPC proliferation through cell-autonomous and cell-nonautonomous mechanisms, and the timing of onset of neurogenesis through a cell-autonomous mechanism. Finally, the timing mechanism for neurogenesis onset does not appear to be dependent on the mechanisms regulated by Vsx2 to promote proliferation. Abbreviations: RPC, retinal progenitor cells.