Trojanowski J Q, Gonatas N K
Brain Res. 1983 Aug 8;272(2):201-10. doi: 10.1016/0006-8993(83)90566-8.
In order to elucidate the sequence for the intraneuronal translocation of ligands after internalization in vivo, the adsorptive endocytosis of horseradish peroxidase (HRP) conjugates of the lectin wheat germ agglutinin (WGHRP) by retinal ganglion cells of the rat was studied by ultrastructural morphometry after intravitreal injections of this probe. Retinas were harvested at post-injection survival times of 15 min to 7 days and processed for the electron microscopic visualization of WGHRP in subcellular organelles. The labeled organelles included vesicles, tubules, lysosomes and the cisterns and coated as well as uncoated vesicles of GERL (Golgi Apparatus-Endoplasmic-Reticulum-Lysosomes). For quantitation, labeled organelles were classed as vesicles, lysosomes and GERL. From 15 min to 3 h the number of labeled GERL and vesicles progressively increased to a maximum at 3 h and then declined to zero by 7 days. In contrast, the number of labeled lysosomes continued to increase beyond 3 h to reach a maximum at 24 h before declining to near zero by 7 days. These results are consistent with the hypothesis that the adsorptive endocytosis of WGHRP entails the passage of the ligand through GERL prior to being deposited in lysosomes. They do not exclude the possibility that other endocytic pathways for WGHRP and possible WGHRP-membrane complexes may exist in retinal ganglion cells including a plasma membrane to lysosome route.
为了阐明体内内化后配体在神经元内转运的序列，在玻璃体内注射该探针后，通过超微结构形态计量学研究了大鼠视网膜神经节细胞对凝集素麦胚凝集素（WGHRP）的辣根过氧化物酶（HRP）偶联物的吸附性内吞作用。在注射后15分钟至7天的存活时间采集视网膜，并进行处理以在亚细胞器中对WGHRP进行电子显微镜观察。标记的细胞器包括囊泡、小管、溶酶体以及GERL（高尔基体-内质网-溶酶体）的池、被膜小泡和无被小泡。为了进行定量，将标记的细胞器分类为囊泡、溶酶体和GERL。从15分钟到3小时，标记的GERL和囊泡数量逐渐增加，在3小时达到最大值，然后在7天时降至零。相比之下，标记的溶酶体数量在3小时后继续增加，在24小时达到最大值，然后在7天时降至接近零。这些结果与以下假设一致，即WGHRP的吸附性内吞作用需要配体在沉积于溶酶体之前通过GERL。它们并不排除在视网膜神经节细胞中可能存在其他WGHRP内吞途径以及可能的WGHRP-膜复合物的可能性，包括质膜到溶酶体的途径。
