Regulation of low density lipoprotein receptor activity in primary cultures of human hepatocytes by serum lipoproteins
Article first published online: 5 DEC 2005
Copyright © 1986 American Association for the Study of Liver Diseases
Volume 6, Issue 6, pages 1356–1360, November/December 1986
How to Cite
Havekes, L. M., Verboom, H., de Wit, E., Yap, S. H. and Princen, H. M. G. (1986), Regulation of low density lipoprotein receptor activity in primary cultures of human hepatocytes by serum lipoproteins. Hepatology, 6: 1356–1360. doi: 10.1002/hep.1840060623
- Issue published online: 5 DEC 2005
- Article first published online: 5 DEC 2005
- Manuscript Accepted: 3 JUL 1986
- Manuscript Received: 20 JAN 1986
The low density lipoprotein receptor activity was measured in primary cultures of human hepatocytes. The receptor-mediated association and degradation of low density lipoprotein increased gradually up to 140 and 190%, respectively, upon incubation of the cells with increasing amounts of whole serum (up to 100%). Preincubation of the cells with low density lipoprotein resulted in a weak downregulation of the receptor-mediated association of low density lipoprotein (only 35% reduction at 100 μg low density lipoprotein per ml). However, preincubation with high density lipoproteins with density between 1.16 and 1.20 gm per ml (heavy high density lipoprotein) resulted in a more than 2-fold stimulation of the receptor-mediated association of low density lipoprotein. This heavy high density lipoprotein-mediated stimulation could not be antagonized by a simultaneous addition of low density lipoprotein during that preincubation.
We conclude that, in primary cultures of human hepatocytes, the downregulation of the low density lipoprotein receptor activity by low density lipoprotein is weak and completely overruled by heavy high density lipoprotein. If these results for human hepatocytes in vitro hold true for hepatocytes in vivo, our results might explain why in vivo liver cells still display low density lipoprotein receptor activity notwithstanding the exposure of these cells to physiological concentrations of low density lipoprotein.