Comparison of Insulin-Like Growth Factor Receptors in Human Retinal Cells
Specific receptors for insulin and insulin-like growth factors have been identified in a variety of tissues, including brain and retinal cells. Covalent crosslinking analysis using disuccinimidyl suberate has enabled us to determine altered molecular weight forms of both the insulin and Type I IGF receptors in human retinal tissue. Autopsy eye donations were frozen and collected until adequate tissue was available for tissue to be solubilized using Triton-X-100. Retinal pigment epithelial cells were also identified and similarly treated. In addition, retinal pigment epithelial cells were cultured following transformation with plasmid pSV2Neo. Using these cells or tissues, we have analyzed the binding of [125I] insulin, IGF I and IGF II, and have determined the molecular weight for the insulin and IGF receptors. We have also examined the effect of mannose-6-phosphate (M6P) on the binding of IGF I to adult rat tissue. M6P had a dramatic effect on the crosslinking of IGF I binding to the Type II IGF/M6P receptor in detergent solubilized tissue preparations; however, no effect of M6P has been seen on autoradiographs of 125I-IGF I crosslinked to solubilized human retinal pigment epithelial cells or human neural retinal membranes. This agrees with our finding that human retinal cells have few Type II IGF/M6P receptors.
KeywordsRetinal Pigment Epithelial Insulin Receptor Retinal Pigment Epithelial Cell Human Retinal Pigment Epithelial Cell Retinal Homogenate
Unable to display preview. Download preview PDF.
- 2.S. Salardi, E. Cacciari, D. Ballardini, F. Righetti, M. Capello, A. Cicognani, S. Zucchini, G. Natali, and D. Tassinari, Relationships between growth factors (somatomedin-C and growth hormones) and body development, metabolic control, and retinal changes in children and adolescents with IDDM. Diabetes 35:832 (1986).PubMedCrossRefGoogle Scholar
- 26.W. Kiess, J.F. Haskell, L. Lee, L.A. Greenstein, B.E. Miller, A.L. Aarons, M.M. Reckler, and S.P. Nissley, An antibody that blocks insulin-like growth factor (IGF) binding to the Type II IGF receptor is neither an agonist nor an inhibitor of several IGF stimulated biologic responses in L6 myoblasts, J Biol Chem 262:12745 (1987).PubMedGoogle Scholar
- 30.R.C. Hunt, A.A. Davis, A. Dewey, J.F. Haskell, Transferrin and insulin-like growth factor-I receptors on retinal pigment epithelia cells, J. Cell Biology 105:236A (1987).Google Scholar
- 32.J. Haskell, L. Haws, and T. Lin, Insulin-like growth factor receptors in rat testicular vascular tissue, Endocrinology 70th Annual Meeting Abst. 519 (1988).Google Scholar
- 33.T. Braulke, C. Causin, A. Waheed, U. Junghans, A. Hasilik, P. Maly, R.E. Humbel, and K. von Figura, Mannose-6-phosphate/insulin-like growth factor II receptor: Distinct binding sites for mannose 6-phosphate and insulin-like growth factor II, Biochem Biophys Res Commun 150:1287 (1988).PubMedCrossRefGoogle Scholar