Apoprotein E mediates the interaction of beta-VLDL with macrophages.

S. R. Bates*, B. A. Coughlin, T. Mazzone, J. Borensztajn, G. S. Getz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

beta-Very low density lipoproteins (beta-VLDL) isolated from cholesterol-fed rhesus monkeys stimulated cholesteryl ester synthesis and accumulation in mouse peritoneal macrophages. The apoprotein specificity and requirement for the cell surface uptake of beta-VLDL was investigated by treating the beta-VLDL with trypsin (beta-VLDL (T], incubating the beta-VLDL (T) with other lipoproteins or apoproteins, reisolating the beta-VLDL (T) and measuring its biological activity which, for this study, is defined as the ability of the lipoprotein to stimulate cholesterol esterification in the macrophages. Trypsin treatment of beta-VLDL abolished its biological activity. Apoprotein analysis of the beta-VLDL (T) demonstrated the absence of intact apoproteins B-100, B-48, and E. The J774 macrophage-like cell line and mouse peritoneal macrophages responded similarly with respect to cholesterol esterification following incubation with inactive and treated beta-VLDL. The J774 macrophage-like cell line was used to establish the conditions necessary for the restoration of biologic activity to the trypsinized beta-VLDL. The loss of biological activity of beta-VLDL (T) could be reversed by restoring apoprotein E-containing LDL from hyperlipemic monkeys or purified apoprotein E. Apoprotein A-I had no such effect. The restored biological activity of the beta-VLDL (T) was proportional to the amount of apoprotein E acquired by the lipoprotein. beta-VLDL particles composed of apoprotein E and either intact or degraded apoprotein B-100 had comparable biological activity. Thus, intact apoprotein E, without intact apoprotein B, is a sufficient mediator for the biological activity and metabolism of beta-VLDL by macrophages and plays a major role in receptor-lipoprotein interaction.

Original languageEnglish (US)
Pages (from-to)787-797
Number of pages11
JournalJournal of lipid research
Volume28
Issue number7
StatePublished - Jul 1987

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Cell Biology

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