Sequestration of Basic Fibroblast Growth Factor in the Primate Retinal Interphotoreceptor Matrix

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 88; no. 15; pp. 6706 - 6710
• Main Authors: Hageman, Gregory S., Kirchoff-Rempe, Margaret A., Lewis, Geoffrey P., Fisher, Steven K., Anderson, Don H.
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01-08-1991; National Acad Sciences
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Antibodies, Monoclonal; Basement membrane; Biological and medical sciences; Cells; Epithelium; Extracellular Space - chemistry; Fibroblast Growth Factor 2 - analysis; Fibroblast Growth Factor 2 - immunology; Fibroblast Growth Factor 2 - isolation & purification; Fibroblast growth factors; Fundamental and applied biological sciences. Psychology; Macaca fascicularis; Microscopy, Fluorescence; Molecular Weight; Neuroglia; Neurons; Photoreceptor Cells - chemistry; Photoreceptor Cells - cytology; Photoreceptors; Primates; Protein hormones. Growth factors. Cytokines; Proteins; Retina; Ungulates; Immunohistochemistry; Fibroblast growth factor; Antibody; Macaca fascicularis; Retina; Vertebrata; Mammalia; Basic protein; Primates; Simioidea; Extracellular matrix; Localization; Fluorescence microscopy
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.88.15.6706

The interphotoreceptor matrix (IPM) occupies the extracellular space between the photoreceptors of the retina and the apical surface of the retinal pigmented epithelium. A large proportion of the IPM is composed of aqueousinsoluble glycoconjugates, including chondroitin sulfatecontaining proteoglycans, the distribution of which exhibits both apical-basal and photoreceptor cell type-specific heterogeneities. The precise function of most insoluble IPM constituents is unknown, although the available evidence suggests some may contribute to retinal adhesion or photoreceptor survival. We have now identified basic fibroblast growth factor (bFGF), or an immunologically related protein from the FGF family, within the IPM. The IPM is labeled on sections of primate retinas by a battery of polyclonal antibodies (Abs) directed against various peptide sequences of bFGF and by an Ab to bovine brain bFGF. bFGF Abs also bind to purified preparations of aqueous-insoluble IPM. All bFGF Abs utilized cross-react with equivalent low molecular mass components of 16.5-17.5 kDa on Western blots of insoluble IPM proteins, purified bFGF, and recombinant bFGF. The Abs do not bind any aqueous-soluble IPM components, suggesting that the bFGF is normally bound to an insoluble IPM constituent(s) in situ. The fact that bFGF is sequestered in the IPM and is located in such close proximity to the photoreceptors, the retinal pigmented epithelium, and Mueller's glia raises the strong possibility that it is synthesized by and regulates the activities of one or more of these three cell types in vivo.