Figure 3
From: β-catenin/Wnt signaling controls progenitor fate in the developing and regenerating zebrafish retina
Inhibition of GSK3β blocks retinal differentiation and maintains proliferative progenitors. Tg(gfap:GFP)mi2002 zebrafish embryos were treated with 0.025% DMSO as a vehicle control or 2.5 μM 1-azakenpaullone to inhibit GSK3β at various times during development. Retinal cryosections from DMSO-treated embryos show normal development of Müller glia (MG; GFP under control of a glial-specific promoter), photoreceptors (the zpr-1 antibody marks red-green double cones (DC)), and calretinin-positive neurons in the ganglion cell layer (GCL) and INL (A, D). The fluorescent signal in the lens (L) is non-specific. Proliferative cells marked with PCNA are found at the retinal margins in the CMZ (D). In contrast, retinas from embryos treated with 1-azakenpaullone from 12 hpf show no expression of GFAP, Zpr-1 labeled photoreceptors, or calretinin (B, E). Nuclear lamination is absent in these retinas, and proliferative cells labeled with PCNA extend throughout the retina (E). Treatment from 36 hpf allows more differentiation to occur, and the central retina is laminated (C). However, the CMZ, which contains proliferative cells, is expanded (F). Scale bar = 100 μm.