Hormonal regulation of low‐density lipoprotein (LDL) receptor activity in human hepatoma Hep G2 cells
- 1 May 1988
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 174 (1) , 213-218
- https://doi.org/10.1111/j.1432-1033.1988.tb14084.x
Abstract
Low‐density lipoprotein (LDL) receptors of approximate Mr 130000 on non‐reduced gels have been identified in Hep G2 cells by immuno‐ and ligand‐blotting of cell extracts. Measurement of LDL receptor protein by scanning ligand blots was correlated with the specific binding, uptake and degradation of 125I‐labelled LDL by intact cells, confirming that this is mediated by the LDL receptor. Cells incubated in medium with serum expressed significant LDL receptor activity. This increased when cells were transferred to medium containing lipoprotein‐deficient serum (LPDS) but was not maximal because a further increase occurred when compactin was included in the medium. Inclusion of 17α‐ethinyl estradiol or 17β‐estradiol in the medium at concentrations up to 500 ng/ml had no effect on LDL receptor activity in the cells as assayed by ligand blotting. Inclusion of insulin (100 mU/ml) in the preincubation medium containing LPDS resulted in a twofold increase in LDL‐receptor protein and of LDL binding and degradation by intact cells. Insulin also diminished the suppressive effect of LDL on LDL receptor activity. If insulin exerts this effect in vivo it may partly explain why the liver expresses LDL receptors despite high levels of LDL in plasma and interstitial fluid.This publication has 32 references indexed in Scilit:
- Binding of low‐density lipoprotein to monolayer cultures of rat hepatocytes is increased by insulin and decreased by dexamethasoneFEBS Letters, 1987
- Regulation of synthesis and cell content of the low-density-lipoprotein receptor protein in cultured fibroblasts from normal and familial hypercholesterolaemic subjectsEuropean Journal of Biochemistry, 1987
- Binding of low-density lipoprotein and chylomicron remnants to the hepatic low-density lipoprotein receptor of dogs, rats and rabbits demonstrated by ligand blotting. Failure to detect a distinct chylomicron-remnant-binding protein by ligand blottingEuropean Journal of Biochemistry, 1986
- The expressed human hepatic receptor for low-density lipoproteins differs from the fibroblast low-density lipoprotein receptorBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1986
- Stimulation of the LDL receptor activity in the human hepatoma cell line Hep G2 by high-density serum fractionsBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1986
- Low density lipoprotein receptors and catabolism in primary cultures of rabbit hepatocytesBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1979
- Regulatory role of insulin in the degradation of low density lipoprotein by cultured human skin fibroblastsBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1978
- Heterozygous familial hypercholesterolemia: Failure of normal allele to compensate for mutant allele at a regulated genetic locusCell, 1976
- Release of low density lipoprotein from its cell surface receptor by sulfated glycosaminoglycansCell, 1976
- Degradation of I125-labelled serum low density lipoprotein in normal and estrogen-treated male ratsBiochemical and Biophysical Research Communications, 1971