Purchase this article with an account.
Lisa Kelly, Heithem M El-Hodiri; The retinal homeobox (Rx) gene is expressed in putative progenitor cells in the INL of the mature frog tadpole retina. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1493.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The retinal homeobox (Rx/Rax) gene is essential for vertebrate retinal development. In part, Rx functions to promote retinal progenitor cell development in the anterior neural plate in all vertebrates and the ciliary marginal zone in cold-blooded animals. In the mature Xenopus tadpole retina, Rx is expressed in all retinal stem and progenitor cells, in photoreceptors, and in scattered cells in the INL. The purpose of this study is to identify and characterize these Rx-expressing INL cells.
Transgenic Xenopus laevis tadpoles were prepared by intra-cytosolic sperm injection (ICSI). Transgene expression was detected by GFP fluorescence or immunofluorescence using cryopreserved tadpole sections. Proliferation was detected by immuno-detection of BrdU incorporation.
Rx-positive INL cells can be identified by expression of a green fluorescent protein (GFP) transgene driven by a Rx promoter and the conserved enhancer, UCE1. We have previously demonstrated that UCE1 contains putative Rx binding sites that are necessary for transgene expression in the INL and that Rx binds to UCE1 in vivo. We found that Rx-positive INL cells incorporate BrdU, demonstrating that they proliferate. We found examples of Rx-positive INL cells that are positive for pan-Otx expression using an antibody that does not distinguish between Otx2 and Crx/Otx5b. These cells are negative for markers of differentiated GCL and INL cells. Finally, we observed examples of GFP-positive cells in the outer INL, near the ONL.<br />
The Rx-positive INL cells are likely to represent a set of progenitor cells in the mature Xenopus retina. These cells do not seem to contribute to differentiated cells in the GCL or INL but may contribute to photoreceptor development.
This PDF is available to Subscribers Only