LDL, Scavenger, and B-VLDL Receptors on Aortic Endothelial Cells

Primary and first passage aortic endothelial cells were shown to possess a high affinity receptor for B-mlgrating very low density lipoproteins (B-VLDL) distinct from the low density lipoprotein (LDL) receptor and scavenger receptor on these cells. In bovine aortic endothelial cells, l-rabbit B-VLDL was taken up and degraded by a high affinity process that was competed for by uniabeled rabbit R-VLDL and uniabeled postprandial VLDL from a fat-fed normal subject. However, uniabeled human or rabbit LDL, human LDL modified by malondlaldehyde (MDA-LDL), or VLDL from a fasted normal human or a rabbit were not effective competitors for the degradation of 1 2 5 I rabblt R-VLDL. In contrast to the receptor-mediated degradation of l-human or rabbit LDL and l-human-MDA-LDL, cell density did not affect the receptor-mediated degradation of l-rabblt B-VLDL. Endothelial cells from a Watanabe heritable hyperlipidemic (WHHL) rabbit virtually did not degrade rabbit LDL, but degraded rabbit BVLDL at a rate equal to that seen In normal rabbit endothelial cells. It was concluded that the B-VLDL receptor on endothellal cells is genetically distinct from the LDL receptor. Incubation of cells for 3 days with 100 ^g/ml protein of uniabeled B-VLDL caused an 88% Increase in cellular cholesterol content, even though the B-VLDL receptor activity was down-regulated by 60%. Endothelial cells and monocyte-macrophages are thus far the only cells known to possess the LDL receptor, the scavenger receptor, and the B-VLDL receptor. (Arteriosclerosis 4:248-255, May/June 1984)