Canonical Wnt Signaling Controls Proliferation of Retinal Stem/Progenitor Cells in Postembryonic Xenopus Eyes
Article first published online: 12 JUN 2008
Copyright © 2008 AlphaMed Press
Volume 26, Issue 8, pages 2063–2074, August 2008
How to Cite
Denayer, T., Locker, M., Borday, C., Deroo, T., Janssens, S., Hecht, A., van Roy, F., Perron, M. and Vleminckx, K. (2008), Canonical Wnt Signaling Controls Proliferation of Retinal Stem/Progenitor Cells in Postembryonic Xenopus Eyes. STEM CELLS, 26: 2063–2074. doi: 10.1634/stemcells.2007-0900
- Issue published online: 2 JAN 2009
- Article first published online: 12 JUN 2008
- Manuscript Accepted: 5 MAY 2008
- Manuscript Received: 30 OCT 2007
- Canonical Wnt pathway;
- Ciliary marginal zone;
- Stem cell;
- Xenopus laevis
Vertebrate retinal stem cells, which reside quiescently within the ciliary margin, may offer a possibility for treatment of degenerative retinopathies. The highly proliferative retinal precursor cells in Xenopus eyes are confined to the most peripheral region, called the ciliary marginal zone (CMZ). Although the canonical Wnt pathway has been implicated in the developing retina of different species, little is known about its involvement in postembryonic retinas. Using a green fluorescent protein-based Wnt-responsive reporter, we show that in transgenic Xenopus tadpoles, the canonical Wnt signaling is activated in the postembryonic CMZ. To further investigate the functional implications of this, we generated transgenic, hormone-inducible canonical Wnt pathway activating and repressing systems, which are directed to specifically intersect at the nuclear endpoint of transcriptional Wnt target gene activation. We found that postembryonic induction of the canonical Wnt pathway in transgenic retinas resulted in increased proliferation in the CMZ compartment. This is most likely due to delayed cell cycle exit, as inferred from a pulse-chase experiment on 5-bromo-2′-deoxyuridine-labeled retinal precursors. Conversely, repression of the canonical Wnt pathway inhibited proliferation of CMZ cells. Neither activation nor repression of the Wnt pathway affected the differentiated cells in the central retina. We conclude that even at postembryonic stages, the canonical Wnt signaling pathway continues to have a major function in promoting proliferation and maintaining retinal stem cells. These findings may contribute to the eventual design of vertebrate, stem cell-based retinal therapies.
Disclosure of potential conflicts of interest is found at the end of this article.