Expression of insulin-like growth factor I receptors and binding proteins by colonic smooth muscle cells
| Autor: | H. S. Ennes, W. J. Snape, P. Hoffmann, J. M. Zeeh, F. Procaccino, J. A. McRoberts, V. E. Eysselein |
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| Rok vydání: | 1997 |
| Předmět: |
Male
medicine.medical_specialty Colon Physiology medicine.medical_treatment Blotting Western Gene Expression Biology Receptor IGF Type 1 Rats Sprague-Dawley Radioligand Assay Insulin-like growth factor Downregulation and upregulation Physiology (medical) Internal medicine medicine Animals Myocyte RNA Messenger Binding site Receptor Cells Cultured Hepatology Binding protein Growth factor Smooth muscle layer Gastroenterology Muscle Smooth Rats Cell biology Insulin-Like Growth Factor Binding Proteins Molecular Weight Cross-Linking Reagents Endocrinology |
| Zdroj: | American Journal of Physiology-Gastrointestinal and Liver Physiology. 272:G481-G487 |
| ISSN: | 1522-1547 0193-1857 |
| Popis: | We recently demonstrated upregulation of insulin-like growth factor I (IGF-I) binding sites in the smooth muscle layer of inflamed rat colon. The increase in binding sites was due to increased expression of IGF binding proteins (IGFBPs), which modulate the effects of IGF. To further study the role of IGF in the colon, we investigated whether cultured colonic smooth muscle cells (SMC) express IGF-I receptors and IGFBPs. SMC were isolated by collagenase digestion from rat colonic smooth muscle and grown in primary culture. Equilibrium binding experiments using (125)I-labeled IGF-I showed the presence of an IGF-I receptor with a dissociation constant of 1.96 nM and a maximal binding constant of 53,000 receptors/cell. Competition binding studies with IGF-II and insulin, together with chemical cross-linking experiments, corroborated this conclusion. Western ligand blotting of conditioned medium and Northern analysis of total RNA demonstrated that the cells expressed and secreted IGFBP-4, -5, and -3 with molecular masses of 25, 31, and 45 kDa, respectively. These results, together with our in vivo studies in the rat, support a role for IGF in tissue fibrosis and stricture formation during chronic intestinal inflammation. |
| Databáze: | OpenAIRE |
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