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Regulation of Low Density Lipoprotein Receptor Function in a Human Hepatoma Cell Line
Author(s) -
Leichtner Alan M.,
Krieger Monty,
Schwartz Alan L.
Publication year - 1984
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.1840040638
Subject(s) - internalization , ldl receptor , low density lipoprotein , hep g2 , lipoprotein , receptor , cell culture , cholesterol , biochemistry , reductase , coenzyme a , chemistry , biology , enzyme , in vitro , genetics
Low density lipoprotein (LDL) processing was investigated in a human hepatoma‐derived cell line, Hep G2. Hep G2 cells bound, internalized and degraded LDL via a saturable, high affinity (Kd ∼ 2 x 10 −8 M ) pathway similar to that present in other mammalian cells. Although 80% of the uptake and degradation of 125 I‐LDL was inhibited by 40‐fold excess native LDL, the same concentration of methylated LDL, which cannot bind to LDL receptors, had virtually no effect on processing. When added at low concentrations, the lysosomotropic agent, chloroquine, inhibited degradation (I 50 −15 μM ) without affecting the rate of lipoprotein internalization. Receptor activity was decreased 60% by preincubation of the cells in medium containing a source of cholesterol (LDL or unesterified cholesterol) and increased 1.7‐fold by preincubation with com‐pactin, a competitive inhibitor of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase. The Hep G2 cell line may prove a useful system both for the further study of hepatic lipoprotein metabolism and for the evaluation of new antihypercholesterolemic agents.