Purchase this article with an account.
D.M. Maddox, A. Manlapat, P. Prasad, V. Ganapathy, S.B. Smith; Analysis of Folate Transport Proteins in Developing Mouse Retina . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1599.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Folate, a water-soluble vitamin essential for DNA, RNA and protein synthesis, requires a carrier mechanism for transport into cells. In adult retina, two folate transport proteins have been reported: folate receptor alpha (FRα) is present in all adult retinal cells; reduced-folate transporter-1 (RFT-1) is present only in adult retinal pigment epithelium (RPE). While studies have shown that lack of FRα leads to impaired optic vesicle development, little is known about the tissue requirements of the folate transport proteins during early eye development. The purpose of this study was to determine the temporo-spatial expression pattern of mRNA encoding these proteins and to localized the proteins themselves in the developing mouse retina. Methods: Adult ICR mice were bred and embryos harvested at embryonic (E) days 9.0, 10.0, 11.5 and 12.5. Gene expression was analyzed by in situ hybridization using digoxigenin-labeled probes specific for mRNA encoding FRα and RFT-1. These two proteins were localized immunohistochemically using polyclonal antibodies specific for FRα and RFT-1 followed by detection using an HRP-based method. Results: Regarding FRα, in situ hybridization analysis revealed abundant expression in the optic eminence at E9.0, with the expression in the eye continuing through E10.0 and E11.5; however, immunohistochemical analysis suggested low levels of FRα in retinal cells. RFT-1 mRNA was expressed abundantly in the optic eminence at E9.0 and throughout the developing retina as early as E10.0; such expression continued through all ages examined. Immunohistochemical analysis detected abundant RFT-1 in the optic eminence as early as E9.0 and throughout the retina and lens at E10.0. By E12.5 RFT-1 was localized to the RPE, particularly in the dorsal region. Conclusions: Although RFT-1 is present only in RPE of adult retina, during early mouse eye development both FRα and RFT-1 are expressed in all retinal cells. Thus, we predict that both proteins are essential for normal retinal development. Future studies, using our recently-acquired heterozygous RFT-1 knockout mice, will permit in-depth analysis of the role of RFT-1 in retinal development.
This PDF is available to Subscribers Only