Otx2 Homeobox Gene Induces Photoreceptor–specific Phenotypes in Cells Derived From Adult Iris and Ciliary Tissue

Abstract

Abstract: : Purpose: Since it remains unclear which gene induction effectively generates photoreceptor–specific phenotypes from non–retinal tissues, the purpose of this study was to determine whether Crx and Otx2, homeobox genes related to photoreceptor development, can induce the generation of these phenotypes in cells derived from adult ciliary and iris tissue and in mesencephalon–derived neural stem cells. Methods: Crx and Otx2 were transferred into adult rat ciliary– and embryonic mesencephalon–derived neurospheres and adult rat iris–derived cells with the aid of a recombinant retrovirus. The presence of photoreceptor–specific phenotypes was confirmed by means of immunocytochemistry and Western blot analysis. Results: Over 90% of the Crx– and Otx2–transfected ciliary– and iris–derived cells exhibited rod–opsin immunoreactivity, while few of the similarly transfected mesencephalon–derived neural stem cells expressed rod–opsin. At least two additional key components of the phototransduction cascade, recoverin and Gαt1, were expressed by Crx– and Otx2–transfected iris–derived cells. Conclusions: Crx and Otx2 could effectively induce the generation of photoreceptor–specific phenotypes from ciliary– and iris–derived cells. These results demonstrate that not only Crx– but also Otx2–gene induced phenotype generation in cells derived from iris or ciliary tissue may represent a possible approach to photoreceptor cell preparation for retinal transplantation.

Keywords: photoreceptors • iris • ciliary body