INDUCTION OF LDL RECEPTOR-RELATED PROTEIN DURING THE DIFFERENTIATION OF MONOCYTE-MACROPHAGES - POSSIBLE INVOLVEMENT IN THE ATHEROSCLEROTIC PROCESS

The low-density lipoprotein receptor-related protein (LRP) is a multif unctional receptor that binds to apolipoprotein E-rich lipoproteins, l ipoprotein lipase, alpha(2)-macroglobulin, lactoferrin, and tissue pla sminogen activator. We studied the mRNA expression of LRP in human mon ocyte-derived macrophages and THP-1 cells. mRNA expression of LRP was induced during cell differentiation from human monocytes to macrophage s or after incubation with phorbol ester (tetradecanoylphorbol acetate 100 ng/mL) in THP-1 cells, and the addition of 30 ng/mL macrophage co lony-stimulating factor further enhanced LRP expression. These results indicated that the expression of LRP depended on the stage of differe ntiation and maturation of monocytic cells. mRNA expression of LRP was also enhanced in human monocyte-derived macrophages in the presence o f acetylated low-density lipoprotein and in aorta of rabbits fed a hig h-cholesterol diet. We hypothesize that the LRP induced in monocyte-de rived macrophages is involved in the initial process of atherosclerosi s by interacting with its multiple ligands.