Journal of Lipid Research, Vol 31, 1455-1466, Copyright © 1990 by Lipid Research, Inc.

ARTICLES

Processing of lipoproteins in human monocyte-macrophages

BJ Van Lenten and AM Fogelman
Department of Medicine, School of Medicine, University of California, Los Angeles 90024-1679.

Subcellular fractionation of human monocyte-macrophages (HMM) yielded a fraction rich in endosomes, lysosomes, and mitochondria. This pellet was further fractionated in a metrizamide gradient and the subcellular organelles were distributed among seven distinct bands. All of the bands contained lysosomal enzymes in similar amounts. However one band, poor in mitochondria, was markedly enriched in cathepsin D and cholesteryl ester hydrolase activities. A number of different ligands (low density lipoproteins (LDL), malondialdehyde-altered LDL, beta- migrating very low density lipoprotein, high density lipoprotein, reductively methylated LDL, mannose-bovine serum albumin, and transferrin) were presented to HMM at a concentration of 20 micrograms/ml at 4 degrees C. Three minutes after warming the cells at 37 degrees C all ligands except two were found predominantly in the cathepsin D- and cholesteryl ester hydrolase-rich fraction. Unlike the other ligands, LDL had distributed to other more dense fractions and reductively methylated LDL was found mainly in less dense fractions. At a lower concentration, 2 micrograms/ml, the distribution of LDL was identical to the other ligands. In vitro incubation of the fractions obtained from the gradient suggested that cathepsin D was largely responsible for the hydrolysis of the lipoproteins. We conclude that studies of LDL metabolism in HMM must take into account the different processing of this ligand at commonly used concentrations.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				N. L. Jones, J. A. Saunders, and R. R. Mallory Intracellular trafficking of pigeon {beta}-very low density lipoprotein and low density lipoprotein at low and high concentrations in pigeon macrophages J. Lipid Res., November 1, 2000; 41(11): 1823 - 1831. [Abstract] [Full Text]

				W. Li, X. M. Yuan, A. G. Olsson, and U. T. Brunk Uptake of Oxidized LDL by Macrophages Results in Partial Lysosomal Enzyme Inactivation and Relocation Arterioscler. Thromb. Vasc. Biol., February 1, 1998; 18(2): 177 - 184. [Abstract] [Full Text] [PDF]

				J. Kreuzer, S. Denger, L. Jahn, J. Bader, K. Ritter, E. von Hodenberg, and W. Kubler LDL Stimulates Chemotaxis of Human Monocytes Through a Cyclooxygenase-Dependent Pathway Arterioscler. Thromb. Vasc. Biol., December 1, 1996; 16(12): 1481 - 1487. [Abstract] [Full Text]