Rod outer segment (ROS) phagocytosis by the retinal pigment epithelium (RPE) is essential for the maintenance of photoreceptors, however, the mechanism is not fully understood. One component that we have been studying is the ligand-receptor interaction. Our lab has been the first to identify a mannose receptor on the RPE apical surface which shares biochemical and immunological properties with the macrophage mannose receptor. We have shown that the ROS ligands for this receptor are rhodopsin and several other mannose-containing glycoproteins. Recently, we have shown that the mannose receptor on normal RPE is expressed on the apical membrane just before the onset of ROS phagocytosis (8 da.) and is retained throughout development. In RGS retinas, which show a greatly reduced ROS ingestion rate, mannose receptor is expressed at 8 days and is retained on the apical membrane only for one month before disappearing. In collaboration with Dr. Virginia Shepherd's lab at Vanderbilt University, who has cloned the macrophage mannose receptor, we are beginning to clone the rat RPE mannose receptor and are now in position to determine its primary structure and eventually identify any differences in the dystrophic receptor. The RCS retina will be useful in helping us achieve our long range goal, which is to elucidate the contribution of the man nose receptor to the mechanism of phagocytosis. To that end we must understand the cell biology of the mannose receptor during ROS binding and ingestion. We will determine the biosynthetic and turnover rates of the RPE mannose receptor and whether there are differences in the biosynthetic processing to its mature form in the RCS animals. Secondly, we will examine if the RPE man nose receptor is recycled after ROS phagocytosis. Thirdly, we will study whether the RPE mannose receptor is associated with the cytoskeleton during ROS binding and whether the mannose receptor in RCS animals is not linked to the cytoskeleton during binding.
The fourth aim will determine what oligosaccharides are present on the mannose receptor and whether there are differences in the oligosaccharide structure of the RCS mannose receptor. The last aim will determine whether the mannose receptor of these two cell types is the product of a single gene, and whether there is a mutational basis for the phagocytic defect in RCS cells.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY002853-19
Application #
2444255
Study Section
Visual Sciences C Study Section (VISC)
Project Start
1988-01-01
Project End
2000-06-30
Budget Start
1997-07-01
Budget End
1998-06-30
Support Year
19
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Louisville
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
City
Louisville
State
KY
Country
United States
Zip Code
40292
Feng, Wei; Zheng, Jing J; Lutz, Douglas A et al. (2003) Loss of RPE phenotype affects phagocytic function. Graefes Arch Clin Exp Ophthalmol 241:232-40
Fan, Wei; Zheng, Jing Juan; Peiper, Stephen C et al. (2002) Changes in gene expression of ARPE-19 cells in response to vitreous treatment. Ophthalmic Res 34:357-65
Fan, Wei; Zheng, Jing Juan; McLaughlin, Barbara J (2002) An in vitro model of the back of the eye for studying retinal pigment epithelial-choroidal endothelial interactions. In Vitro Cell Dev Biol Anim 38:228-34
Singh, S; Zheng, J J; Peiper, S C et al. (2001) Gene expression profile of ARPE-19 during repair of the monolayer. Graefes Arch Clin Exp Ophthalmol 239:946-51
Singh, S; Woerly, S; McLaughlin, B J (2001) Natural and artificial substrates for retinal pigment epithelial monolayer transplantation. Biomaterials 22:3337-43
Hadlock, T; Singh, S; Vacanti, J P et al. (1999) Ocular cell monolayers cultured on biodegradable substrates. Tissue Eng 5:187-96
Egan, B S; Lane, K B; Shepherd, V L (1999) PU.1 and USF are required for macrophage-specific mannose receptor promoter activity. J Biol Chem 274:9098-107
Wilt, S D; Greaton, C J; Lutz, D A et al. (1999) Mannose receptor is expressed in normal and dystrophic retinal pigment epithelium. Exp Eye Res 69:405-11
Wilt, S D; McLaughlin, B J (1999) Is another mannose receptor-like lectin present in retinal pigment epithelium? Curr Eye Res 19:1-3
Yan, F; Cooper, N G; McLaughlin, B J (1998) Temperature-sensitive interactions between RPE and rod outer segment surface proteins. Exp Eye Res 66:783-90

Showing the most recent 10 out of 22 publications