低密度リポ蛋白代謝におけるマクロファージと血管内皮細胞の役割

ことにscavenger receptorの発現機構を中心に

抄録

In order to clarify the role of macrophages and endothelial cells in low density lipoprotein (LDL) metabolism, we have performed the immunohistochemical and immunoelectron microscopic studies of tissue distribution, intracellular localization, and expression of scavenger receptors and LDL receptors.
Scavenger receptors are a trimeric membrane protein mediating endocytosis of modified LDL including acetylated LDL (acLDL). The receptors were detected specifically in macrophages in various tissues. Reaction products for scavenger receptors were localized on the cell surface, vesicles, and endosomes.
As for the intracellular localization of scavenger receptors during receptor-mediated endocytosis of acLDL, we demonstrated that the receptors were internalized through coated pits and moved into endosomes and recycled to the cell surface via Golgi apparatus. Expression of scavenger receptors in cultured macrophagic and non-macrophage cells suggested that efficient intracellular transport of the receptors is mediated by a macrophage specific transport system.
Endothelial cells have LDL receptors but not scavenger receptors. However, they bound to and took up both LDL and acLDL into the cytoplasm. These results suggest that endothelial cells possess different receptors capable of scavenging acLDL. Endothelial cells were considered to share intermediate characteristics between fibroblasts and macrophages in LDL metabolism.