Purchase this article with an account.
M. M. McNally, J. Handa, D. J. Zack, V. Canto-Soler; Effects of Sustained Pax6 Expression in Retinal Progenitor Cells in ovo. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1308.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The dynamic pattern of expression of Pax6 during retinal development suggests that Pax6 plays an important role during retinal progenitor differentiation, but the exact role(s) and timing of its function remain unclear. The purpose of this study was to analyze the function of Pax6 during retinal cell differentiation by overexpressing Pax6 in vivo.
The coding region of chicken Pax6 was amplified by RT-PCR, modified to include a N-terminal HA-tag, and cloned into an RCAS vector. RCAS-Pax6 and RCAS-GFP (control) DNA were electroporated into the optic vesicle of ED2 chick embryos. Embryos were fixed at different stages, sectioned, and processed for immunohistochemical detection of markers for different retinal cell types. Infected areas were identified by HA immunostaining (RCAS-Pax6) or by GFP expression (control).
Embryos from both experimental and control groups showed normal macroscopic eye phenotypes as well as normal multi-layered retinas. In control retinas, RA4, a ganglion cell specific marker, showed its characteristic "radial" pattern of expression that demarcates the progressive advance of the "neurogenic front" from the fundus to more peripheral regions. RA4(+)-radially oriented cells spanning the thickness of the retina were confined to the fundal region at ED6; by ED8 the RA4(+) territory had advanced to more peripheral regions leaving the fundus devoid of "radial" RA4 positive cells; by ED10, most of the retina was negative for RA4 except for the most distal tip. No significant differences were observed between Pax6-treated retinas and control retinas at ED6. In contrast, at later stages RCAS-Pax6 infected regions showed persistence of "radially oriented" RA4 (+) cells even in the most fundal regions of the retina. Furthermore, ectopic "rounded" RA4 positive cells located in the outer nuclear layer were observed at ED10. No significant differences in the expression pattern of Prox1, Lim1, Ap2, Islet1 and Brn3a were observed.
These results suggest that sustained Pax6 expression in retinal progenitor cells alters the dynamics of developmental neurogenesis, particularly that of ganglion cells. Further studies are being carried out to better characterize this phenomenon.
This PDF is available to Subscribers Only