Robenek H, Schmitz G, Greven H
Eur J Cell Biol. 1987 Feb;43(1):110-20.
The receptor-mediated endocytosis pathway of colloidal gold labeled beta-very low density lipoprotein (beta-VLDL-Au) derived from patients with familial dysbetalipoproteinemia was analyzed at the ultrastructural level in macrophages. The results showed that beta-VLDL-Au complexes were specifically recognized by a cell surface receptor of the macrophages. beta-VLDL-Au particles once bound to the randomly distributed cell surface receptors clustered in coated pits and were taken up by coated vesicles. Subsequently, the beta-VLDL-Au particles passed through tubular structures and small endosomes before deposited into large electron lucent smooth surfaced endosomes. As revealed by ruthenium red and enzyme cytochemistry the endosomes appeared to be separated from the extracellular space and did not contain acid phosphatase. There were no clear signs of passage of beta-VLDL through the Golgi complex. The accumulation of many flocculated gold particles within Ac-Pase positive vesicles suggests that beta-VLDL once internalized by the macrophages is diverted into a degradative pathway. Incubation of beta-VLDL-loaded macrophages with the hydrophobic fluorescent dye nile red revealed numerous large fluorescent bodies within the cells indicating that the macrophages accumulate large amounts of lipid droplets with time. Additional studies large amounts of lipid droplets with time. Additional studies with native beta-VLDL in conjunction with postembedding immunocytochemical techniques were used to delineate further the intracellular pathway. Immunolabeling was carried out on thin sections of LR White embedded cells using affinity-purified polyclonal rabbit antibodies against apolipoprotein B with the protein A-gold or goat anti-rabbit IgG-gold technique. Indirect visualization of beta-VLDL by these immunocytochemical studies yielded results comparable to those with gold-labeled beta-VLDL. On the basis of both indirect immunocytochemical and direct cytochemical localization of beta-VLDL it is concluded that although colloidal gold labeling of beta-VLDL molecules unquestionably modifies their morphology, their function appears to be unaltered, at least with respect to the process of receptor-mediated endocytosis.
在巨噬细胞的超微结构水平上分析了家族性异常β脂蛋白血症患者来源的胶体金标记β极低密度脂蛋白（β-VLDL-Au）的受体介导内吞途径。结果显示，β-VLDL-Au复合物被巨噬细胞的细胞表面受体特异性识别。β-VLDL-Au颗粒一旦与随机分布的细胞表面受体结合，就会聚集在被膜小窝中，并被被膜小泡摄取。随后，β-VLDL-Au颗粒在沉积到大的电子透亮光滑表面的内体之前，先通过管状结构和小的内体。钌红和酶细胞化学显示，这些内体似乎与细胞外空间分隔开，且不含有酸性磷酸酶。没有明显迹象表明β-VLDL通过高尔基体复合物。在酸性磷酸酶阳性小泡内积累许多絮凝的金颗粒表明，巨噬细胞内化的β-VLDL一旦进入细胞就会转向降解途径。用疏水性荧光染料尼罗红孵育负载β-VLDL的巨噬细胞，发现细胞内有许多大的荧光体，表明巨噬细胞随时间积累了大量脂滴。进一步的研究……随时间积累了大量脂滴。用天然β-VLDL结合包埋后免疫细胞化学技术进行的其他研究进一步描绘了细胞内途径。使用针对载脂蛋白B的亲和纯化兔多克隆抗体，通过蛋白A-金或山羊抗兔IgG-金技术，对LR White包埋细胞的薄切片进行免疫标记。这些免疫细胞化学研究对β-VLDL的间接可视化结果与胶体金标记的β-VLDL的结果相当。基于β-VLDL的间接免疫细胞化学和直接细胞化学定位，得出结论：尽管β-VLDL分子的胶体金标记无疑改变了它们的形态，但至少就受体介导的内吞过程而言它们的功能似乎未改变。
