Neural retina identity is specified by lens-derived BMP signals.
Bottom Line: Subsequently, our results provide evidence that a Rax2-positive eye-field state is not sufficient for the progress to a neural retina identity, but requires BMP signals.In addition, our results argue against any essential role of Wnt or FGF signals during the specification of neural retina cells, but provide evidence that Wnt signals together with BMP activity are sufficient to induce cells of retinal pigment epithelial character.We conclude that BMP activity emanating from the lens ectoderm maintains eye-field identity, inhibits telencephalic character and induces neural retina cells.
Affiliation: Umeå Centre for Molecular Medicine, Umeå University, Umeå 901 87, Sweden.Show MeSH
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Mentions: Next, we tested whether Wnt activity alone or in combination with BMP signals is sufficient to induce neural retina cells or RPE cells, by culturing stage 9/10 OV explants together with Wnt3A-conditioned medium alone or together with low levels of BMP4. Stage 9/10 OV explants cultured together with Wnt3A still generated FoxG1+ and Emx2+ dorsal telencephalic cells, but no Rax2+ or Vsx2+ neural retina cells or Mitf+ RPE cells (Fig. 7A). By contrast, the combination of Wnt and BMP activity inhibited the generation of FoxG1+ and Emx2+ dorsal telencephalic cells, and induced Mitf+ RPE cells, as well as Rax2+ and Vsx2+ neural retina cells (Fig. 7B). Thus, Wnt activity is not required or sufficient to specify neural retina cells, but a combination of Wnt and BMP signals can induce RPE cells.Fig. 7.
Affiliation: Umeå Centre for Molecular Medicine, Umeå University, Umeå 901 87, Sweden.