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. 1986 May;77(5):1548–1556. doi: 10.1172/JCI112470

Cultured fibroblast monolayers secrete a protein that alters the cellular binding of somatomedin-C/insulinlike growth factor I.

D R Clemmons, R G Elgin, V K Han, S J Casella, A J D'Ercole, J J Van Wyk
PMCID: PMC424558  PMID: 2422210

Abstract

We studied somatomedin-C/insulinlike growth factor (Sm-C/IGF-I) binding to human fibroblasts in both adherent monolayers and in suspension cultures. The addition of Sm-C/IGF-I in concentrations between 0.5 and 10 ng/ml to monolayers cultures resulted in a paradoxical increase in 125I-Sm-C/IGF-I binding and concentrations between 25 and 300 ng/ml were required to displace the labeled peptide. The addition of unlabeled insulin resulted in no displacement of labeled Sm-C/IGF-I from the adherent cells. When fibroblast suspensions were used Sm-C/IGF-I concentrations between 1 and 10 ng/ml caused displacement, the paradoxical increase in 125I-Sm-C/IGF-I binding was not detected, and insulin displaced 60% of the labeled peptide. Affinity cross-linking to fibroblast monolayers revealed a 43,000-mol wt 125I-Sm-C-binding-protein complex that was not detected after cross-linking to suspended cells. The 43,000-mol wt complex was not detected after cross-linking to smooth muscle cell monolayers, and binding studies showed that 125I-Sm-C/IGF-I was displaced greater than 90% by Sm-C/IGF-I using concentrations between 0.5 and 10 ng/ml. Because fibroblast-conditioned medium contains the 43,000-mol wt complex, smooth muscle cells were incubated with conditioned medium for 24 h prior to initiation of the binding studies. 125I-Sm-C/IGF-I-binding increased 1.6-fold compared to control cultures and after cross-linking the 43,000-mol wt complex could be detected on the smooth muscle cell surface. Human fibroblast monolayers secrete a protein that binds 125I-Sm-C/IGF-I which can be transferred to the smooth muscle cell surface and alters 125I-Sm-C/IGF-I binding.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Adams S. O., Nissley S. P., Kasuga M., Foley T. P., Jr, Rechler M. M. Receptors for insulin-like growth factors and growth effects of multiplication-stimulating activity (rat insulin-like growth factor II) in rat embryo fibroblasts. Endocrinology. 1983 Mar;112(3):971–978. doi: 10.1210/endo-112-3-971. [DOI] [PubMed] [Google Scholar]
  2. Armstrong G. D., Hollenberg M. D., Bhaumick B., Bala R. M. Comparative studies on human placental insulin and basic somatomedin receptors. J Cell Biochem. 1982;20(3):283–292. doi: 10.1002/jcb.240200308. [DOI] [PubMed] [Google Scholar]
  3. Armstrong M. L., Heistad D. D., Marcus M. L., Piegors D. J., Abboud F. M. Hemodynamic sequelae of regression of experimental atherosclerosis. J Clin Invest. 1983 Jan;71(1):104–113. doi: 10.1172/JCI110738. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Baldwin D., Jr, Prince M., Tsai P., Johnson C., Lotan R., Rubenstein A. H., Olefsky J. M. Insulin binding, internalization, and receptor regulation in cultured human fibroblasts. Am J Physiol. 1981 Sep;241(3):E251–E260. doi: 10.1152/ajpendo.1981.241.3.E251. [DOI] [PubMed] [Google Scholar]
  5. Chernausek S. D., Jacobs S., Van Wyk J. J. Structural similarities between human receptors for somatomedin C and insulin: analysis by affinity labeling. Biochemistry. 1981 Dec 22;20(26):7345–7350. doi: 10.1021/bi00529a004. [DOI] [PubMed] [Google Scholar]
  6. Clemmons D. R., Shaw D. S. Variables controlling somatomedin production by cultured human fibroblasts. J Cell Physiol. 1983 May;115(2):137–142. doi: 10.1002/jcp.1041150206. [DOI] [PubMed] [Google Scholar]
  7. Clemmons D. R., Underwood L. E., Van Wyk J. J. Hormonal control of immunoreactive somatomedin production by cultured human fibroblasts. J Clin Invest. 1981 Jan;67(1):10–19. doi: 10.1172/JCI110001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Conover C. A., Dollar L. A., Hintz R. L., Rosenfeld R. G. Insulin-like growth factor I/somatomedin-C (IGF-I/SM-C) and glucocorticoids synergistically regulate mitosis in competent human fibroblasts. J Cell Physiol. 1983 Aug;116(2):191–197. doi: 10.1002/jcp.1041160210. [DOI] [PubMed] [Google Scholar]
  9. D'Ercole A. J., Underwood L. E., Groelke J., Plet A. Leprechaunism: studies of the relationship among hyperinsulinism, insulin resistance, and growth retardation. J Clin Endocrinol Metab. 1979 Mar;48(3):495–502. doi: 10.1210/jcem-48-3-495. [DOI] [PubMed] [Google Scholar]
  10. Grizzard J. D., D'Ercole A. J., Wilkins J. R., Moats-Staats B. M., Williams R. W. Affinity-labeled somatomedin-C receptors and binding proteins from the human fetus. J Clin Endocrinol Metab. 1984 Mar;58(3):535–543. doi: 10.1210/jcem-58-3-535. [DOI] [PubMed] [Google Scholar]
  11. Kasuga M., Van Obberghen E., Nissley S. P., Rechler M. M. Demonstration of two subtypes of insulin-like growth factor receptors by affinity cross-linking. J Biol Chem. 1981 Jun 10;256(11):5305–5308. [PubMed] [Google Scholar]
  12. Knauer D. J., Cunningham D. D. Epidermal growth factor carrier protein binds to cells via a complex with released carried protein nexin. Proc Natl Acad Sci U S A. 1982 Apr;79(7):2310–2314. doi: 10.1073/pnas.79.7.2310. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Kull F. C., Jr, Jacobs S., Su Y. F., Svoboda M. E., Van Wyk J. J., Cuatrecasas P. Monoclonal antibodies to receptors for insulin and somatomedin-C. J Biol Chem. 1983 May 25;258(10):6561–6566. [PubMed] [Google Scholar]
  14. Massagué J., Czech M. P. The subunit structures of two distinct receptors for insulin-like growth factors I and II and their relationship to the insulin receptor. J Biol Chem. 1982 May 10;257(9):5038–5045. [PubMed] [Google Scholar]
  15. Rechler M. M. Leprechaunism and related syndromes with primary insulin resistance: heterogeneity of molecular defects. Prog Clin Biol Res. 1982;97:245–281. [PubMed] [Google Scholar]
  16. Rechler M. M., Podskalny J. M., Goldfine I. D., Wells C. A. DNA synthesis in human fibroblasts: stimulation by insulin and by nonsuppressible insulin-like activity (NSILA-S). J Clin Endocrinol Metab. 1974 Sep;39(3):512–521. doi: 10.1210/jcem-39-3-512. [DOI] [PubMed] [Google Scholar]
  17. Rosenfeld R. G., Dollar L. A. Characterization of the somatomedin-C/insulin-like growth factor I (SM-C/IGF-I) receptor on cultured human fibroblast monolayers: regulation of receptor concentrations by SM-C/IGF-I and insulin. J Clin Endocrinol Metab. 1982 Sep;55(3):434–440. doi: 10.1210/jcem-55-3-434. [DOI] [PubMed] [Google Scholar]
  18. Rosenfeld R. G., Dollar L. A., Conover C. A. Density-associated loss of functional receptors for somatomedin-C/insulinlike growth factor I (SM-C/IGF-I) on cultured human fibroblast monolayers. J Cell Physiol. 1984 Nov;121(2):419–424. doi: 10.1002/jcp.1041210221. [DOI] [PubMed] [Google Scholar]
  19. Svoboda M. E., Van Wyk J. J. Purification of somatomedin-C/insulin-like growth factor I. Methods Enzymol. 1985;109:798–816. doi: 10.1016/0076-6879(85)09131-5. [DOI] [PubMed] [Google Scholar]
  20. Van Obberghen-Schilling E. E., Rechler M. M., Romanus J. A., Knight A. B., Nissley S. P., Humbel R. E. Receptors for insulinlike growth factor I are defective in fibroblasts cultured from a patient with leprechaunism. J Clin Invest. 1981 Nov;68(5):1356–1365. doi: 10.1172/JCI110383. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Van Wyk J. J., Graves D. C., Casella S. J., Jacobs S. Evidence from monoclonal antibody studies that insulin stimulates deoxyribonucleic acid synthesis through the type I somatomedin receptor. J Clin Endocrinol Metab. 1985 Oct;61(4):639–643. doi: 10.1210/jcem-61-4-639. [DOI] [PubMed] [Google Scholar]
  22. Wilkins J. R., D'Ercole A. J. Affinity-labeled plasma somatomedin-C/insulinlike growth factor I binding proteins. Evidence of growth hormone dependence and subunit structure. J Clin Invest. 1985 Apr;75(4):1350–1358. doi: 10.1172/JCI111836. [DOI] [PMC free article] [PubMed] [Google Scholar]

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