Free Apolipoproteins A-I and A-IV Present in Human Plasma Displace High-Density Lipoprotein on Cultured Bovine Aortic Endothelial Cells

  • Naphtali Savion
  • Aviva Gamliel
Part of the GWUMC Department of Biochemistry Annual Spring Symposia book series (GWUN)


Adult bovine aortic endothelial (ABAE) cells in a serum-free medium specifically bind [125I]-labeled high-density lipoprotein ([125I]HDL). Addition of lipoprotein-deficient serum (LPDS) to the incubation medium interferes with the binding in a concentration-dependent manner such that at a concentration of 6 mg protein/ml of LPDS almost a complete inhibition of the specific [125I]HDL binding is observed. Cultures of ABAE cells exposed to [125I]-labeled LPDS ([125I]LPDS) specifically bind two peptides that appear as minor iodinated components in the [125I]LPDS. The binding of the two iodinated LPDS components is abolished in the presence of excess amounts of unlabeled LPDS or HDL. Preincubation of ABAE cells with 25-hydroxycholesterol (25-HC) results in an increase in the binding of these two [125I]LPDS components similarly to the increase in [125I]HDL binding. These two LPDS components comigrated on sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with apolipoproteins (apos) A-I and A-IV with molecular weights of 28,000 and 43,000, respectively. The apo A-IV is also found in commercial preparations of human and bovine albumin, and indeed, these albumin preparations interfere with [125I]HDL binding to ABAE cultures similarly to the effect of LPDS.

When ABAE cultures are treated with 25-HC and subjected to cell surface iodination followed by analysis on SDS-PAGE, the apo A-IV appears as one of the major proteins on the cell surface accessible to iodination. The interaction of apo A-IV with the cell surface of 25-HC-treated cells is not specific only to ABAE cells and appears also in human skin fibroblasts.

The results indicate that free apos A-I and A-IV present in LPDS can displace HDL on the cell surface of ABAE cells. It therefore indicates that the free apos A-I and A-IV present in plasma control the binding of HDL to endothelial cells and may regulate the important process of cholesterol removal from the cells by HDL.


Human Skin Fibroblast Bovine Albumin Bovine Aortic Endothelial Cell Cholesterol Removal Aortic Endothelial 
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  1. Cohen, D. C., Massoglia, S. L., and Gospodarowicz, D., 1982, Correlation between two effects of high density lipoproteins on vascular endothelial cells. The induction of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and the support of cellular proliferation, J. Biol. Chem. 257:9429– 9437.PubMedGoogle Scholar
  2. Fidge, N. H., and Nestle, P. J., 1985, Identification of apolipoproteins involved in the interaction of human high density lipoproteins with receptors of cultured cells, J. Biol. Chem. 260:3570–3575.PubMedGoogle Scholar
  3. Miller, N. E., Weinstein, D. B., and Steinberg, D., 1977, Binding, internalization and degradation of high density lipoprotein by cultured human fibroblasts, J. Lipid Res. 18:438–450.PubMedGoogle Scholar
  4. Stein, O., Vanderhoek, J., and Stein, Y., 1976, Cholesterol content and sterol synthesis in human skin fibroblasts and rat aortic smooth muscle cells exposed to lipoprotein-depleted serum and high density apolipoprotein/phospholipid mixtures, Biochim. Biophys. Acta 431:347–358.PubMedGoogle Scholar
  5. Tabas, I., and Tall, A. R., 1984, Mechanism of the association of HDL3 with endothelial cells, smooth muscle cells and fibroblasts. Evidence against the role of specific ligand and receptor proteins, J. Biol. Chem. 259:13897–13905.PubMedGoogle Scholar
  6. Tauber, J.-P., Cheng, J., and Gospodarowicz, D., 1980, Effect of high and low density lipoproteins on proliferation of cultured bovine vascular endothelial cells, J. Clin. Invest. 66:696–708.PubMedCrossRefGoogle Scholar
  7. Tauber, J.-P., Goldminz, D., and Gospodarowicz, D., 1981, Up-regulation in vascular endothelial cells of binding sites of high density lipoprotein induced by 25-hydroxycholesterol, Eur. J. Biochem. 119:327–339.PubMedCrossRefGoogle Scholar
  8. Weinberg, R. B., and Scanu, A. M., 1983, Isolation and characterization of human apolipoprotein A-IV from lipoprotein-depleted serum, J. Lipid Res. 24:52–59.PubMedGoogle Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • Naphtali Savion
    • 1
  • Aviva Gamliel
    • 1
  1. 1.Maurice and Gabriela Goldschleger Eye Research InstituteTel-Aviv University Sackler Faculty of Medicine, Chaim Sheba Medical CenterTel HashomerIsrael

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