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S T Feldman, D Gately, B L Seely, A Schonthal, J R Feramisco; Stimulation of DNA synthesis and c-fos expression in corneal endothelium by insulin or insulin-like growth factor-I.. Invest. Ophthalmol. Vis. Sci. 1993;34(6):2105-2111.
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© ARVO (1962-2015); The Authors (2016-present)
PURPOSE: To study the growth regulation of bovine corneal endothelium, the effects of insulin and insulin-like growth factor-I on the expression of the c-fos proto-oncogene as well as on DNA synthesis were analyzed. Bovine corneal endothelial cells were also analyzed for the presence of insulin and insulin-like growth factor-I receptors. METHODS: Indirect immunofluorescence was used to assess the effect of stimulation by insulin and insulin-like growth factor-I on c-fos protein expression and DNA synthesis quiescent bovine corneal endothelium. Receptor number was determined by 125I-insulin or 125I-IGF-I binding studies. RESULTS: Fetal bovine serum strongly stimulated c-fos protein expression and DNA synthesis. Insulin-like growth factor-I was less effective while insulin was effective only at high concentrations. Scatchard analysis of 125I-insulin-like growth factor-I and 125I-insulin binding to bovine corneal endothelium revealed 180,000 IGF-I receptors and 7,000 insulin receptors. CONCLUSION: The number of insulin-like growth factor-I receptors far exceeds the number of insulin receptors in bovine corneal endothelium, suggesting that the effects of insulin on c-fos gene expression and mitogenesis were likely to be mediated through the insulin-like growth factor-I receptor.
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