Fig. 3

Wnt/β-catenin signaling inhibits retinal identity and proneural gene expression. A: The neural competence factor sox2 is expressed adjacent to the domain of Wnt/β-pathway activation and is absent from the most peripheral cells (arrows). B: The sox2 domain is centrally shifted in 48 hours postfertilization (hpf) apc mutant eyes. The more peripheral, expanded zone of Wnt/β-pathway activation is devoid of sox2 expression. C: The proneural gene atoh7 is expressed in a wedge adjacent, and more central to the sox2 domain. D: In 48 hpf apc mutant eyes, the atoh7 domain is centrally displaced. E,G: Double fluorescent in situ analysis of sox2 in red and atoh7 in green in 38 and 48 hpf wild-type eyes reveals that sox2 and atoh7 are expressed in adjacent, mutually exclusive domains. F,H: In 38 hpf apc eyes, the sox2 and atoh7 expression domains are shifted toward the central retina. In 48 hpf apc eyes, sox2 and atoh7 expression becomes more disorganized. I,J: Immunofluorescence with Zn8 shows that retinal ganglion cells differentiate in 48 hpf mutant eyes, even though they are restricted to the central retina.