PMID: 2111368Mar 1, 1990Paper

Interaction of LDL with human arterial proteoglycans stimulates its uptake by human monocyte-derived macrophages.

Journal of Lipid Research
E HurtG Camejo

Abstract

The aim of this work was to investigate the possible mechanisms for uptake by human monocyte-derived macrophages (HMDM) of low density lipoprotein (LDL) pretreated with human arterial chondroitin-6-SO4-rich proteoglycan (LDL-PG). HMDM were incubated with 125I-labeled tyramine cellobiose-labeled LDL-PG, native LDL, and acetylated LDL (Ac-LDL). The results showed that two to four times more LDL-PG than LDL was bound and internalized by the HMDM. Competition experiments showed that LDL-PG competed with native LDL for the apoB,E (LDL) receptor, but not for the Ac-LDL scavenger receptor. Both the LDL and LDL-PG uptake were reduced after preincubation of the macrophages with unlabeled native LDL, though to a lesser extent with LDL-PG. The specific binding of 125I-labeled LDL and 125I-labeled LDL-PG at 4 degrees C was both saturable and concentration-dependent. The dissociation constant (Kd) for binding was 8.6 x 10(-9) M for LDL and 9.4 x 10(-9) M for LDL-PG, but the maximum binding (Bmax) was 1.5-times higher for LDL-PG. Cholesterol derived from LDL-PG was less effective than native LDL in suppressing HMG-CoA reductase activity. The results indicate that the uptake of LDL-PG is mediated not only by the LDL-receptor, but also by anot...Continue Reading

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