The etiology and molecular mechanisms for many degenerative conditions of the retina, such as retinitis pigmentosa, remain unclear. It is well established that cell surface glycoconjugates are important in the normal interaction of cells with their environment. While the presence of glycoconjugates in retina and RPE has been demonstrated, they have not been well characterized in either normal or pathological tissue. We will use cell and organ culture systems with radiolabeled precursors to biochemically characterize and analyze the surface proteoglycans and glycoproteins on human RPE and retina and to investigate how these glycoconjugates can be altered in retinitis pigmentosa. The embryonic chick retina, a system more amenable to experimental manipulation, will be used in developmental and regulatory studies, and for correlation with the human investigations. Understanding the regulation of cell surface events during development can provide insight into pathological mechanisms. The chick retinal cell culture system will also allow for the study of different retinal cell subpopulations, which is not possible with adult retinal tissue. Peripheral and integral membrane proteoglycans and glycoproteins will be isolated and characterized on the basis of size, carbohydrate composition, and macromolecular interactions with other membrane components. The glycosaminoglycans and oligosaccharides derived from proteoglycans and glycoproteins, respectively, by extensive protease digestion, will be characterized by chemical and enzymatic means and the use of lectins. Lectin-affinity columns will also be used to characterize the branching patterns of oligosaccharides. Comparisons between regulation studies on animal cells and investigations using human material are expected to yield useful information regarding molecular mechanisms of altered glycoconjugate in retinal pathology.
