Schweitzer E S, Paddock S
Department of Anatomy and Cell Biology, University of California School of Medicine, Los Angeles 90024.
J Cell Sci. 1990 Jul;96 ( Pt 3):375-81. doi: 10.1242/jcs.96.3.375.
Two distinct population of vesicles can be identified in PC12 cells by subcellular fractionation and immunofluorescence. Density gradient separation reveals one population of dense vesicles that contains the transgenic regulated secretory protein hGH (human growth hormone) along with the endogenous neurotransmitter norepinephrine. Some of the neuronal vesicle marker synaptophysin (P38) is also associated with these vesicles. A second population of low-density vesicles contains synaptophysin but not hGH or norepinephrine. Immunofluorescence localization of hGH revealed a pattern consistent with packaging into catecholaminergic vesicles: the staining is punctate and most concentrated in the tips of the neuritic processes, with secondary accumulation in the perinuclear region. Double-staining of cells for hGH and synaptophysin confirms that these proteins do not co-localize but rather are spatially segregated within the cell. The observed distribution of vesicle markers is inconsistent with simple models for the generation of one type of vesicle from the other, suggesting that the vesicles are products of two divergent biosynthetic pathways. While the hGH is clearly contained in regulated secretory vesicles, the function of the second population of vesicles remains uncertain.
通过亚细胞分级分离和免疫荧光技术，可以在PC12细胞中鉴定出两种不同的囊泡群体。密度梯度分离显示出一种致密囊泡群体，其包含转基因调控分泌蛋白hGH（人生长激素）以及内源性神经递质去甲肾上腺素。一些神经元囊泡标志物突触素（P38）也与这些囊泡相关。第二种低密度囊泡群体含有突触素，但不含有hGH或去甲肾上腺素。hGH的免疫荧光定位显示出一种与包装到儿茶酚胺能囊泡中相一致的模式：染色呈点状，最集中在神经突末端，在核周区域有次要积累。对细胞进行hGH和突触素的双重染色证实，这些蛋白质并非共定位，而是在细胞内空间上分离。观察到的囊泡标志物分布与一种囊泡由另一种囊泡产生的简单模型不一致，这表明这些囊泡是两条不同生物合成途径的产物。虽然hGH显然包含在调控分泌囊泡中，但第二种囊泡群体的功能仍不确定。
