Biopolymers and cell. 1989. Volume 5. № 2. 74 - 78

I. V. Fuki, S. N. Preobrazhensky, A. Yu. Misharin, N. G. Bushmakina, G. B. Menshchikov, V. S. Repin

CHOLESTEROL EFFECT ON APOLIPOPROTEIN B SECRETION AND BINDING OF LOW-DENSITY LIPOPROTEINS BY HEPATOMA HEPQ2 CELLS

Summary

    The effect of cholesterol, oleic acid and recombinant complexes containing apolipoprotein Al/dimyristoylphosphatidylcholine (apoAl/DMPC) on apolipoprotein B (apoB) secretion and uptake of 125I-labeled low-density lipoproteins (LDL) by cultured human hepatoma HepG2 cells was studied. Addition of different concentrations of exogenous cholesterol (as ethanol solution) to the cells increased apoB secretion and inhibited 1 25I-labelled LDL uptake in a dose-dependent manner. Similar effects were found when the cells were incubated with different concentrations of oleic acid, which enhanced the intracellular cholesterol content. The presence of complexes apoAl/DMPC in the culture medium, which decreased the cellular pool of cholesterol, resulted in the opposite effects: apoB secretion was inhibited, while the LDL-receptor activity was stimulated. Significant negative correlation (r = —0.92, p<0.001) was found between apoB secretion and LDL uptake. The obtained data suggest that cholesterol can induce cooperated changes in apoB secretion and LDL-rcceptor activity.