Hosoda Yoshiki, Miyawaki Kyojy, Saito Shouichiro, Chen Jie, Bing Xue, Terashita Takehiro, Kobayashi Naoto, Araki Nobukazu, Shimokawa Tetsuya, Hamada Fumihiko, Sano Akira, Tanabe Hirotaka, Matsuda Seiji
Department of Neuropsychiatry, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0212, Japan.
Cell Tissue Res. 2007 Nov;330(2):197-207. doi: 10.1007/s00441-007-0464-9. Epub 2007 Aug 31.
Prosaposin is the precursor of four sphingolipid activator proteins (saposins A, B, C, and D) for lysosomal hydrolases and is abundant in the nervous system and muscle. In addition to its role as a precursor of saposins in lysosomes, intact prosaposin has neurotrophic effects in vivo or in vitro when supplied exogenously. We examined the distribution of prosaposin in the central and peripheral nervous systems and its intracellular distribution. Using a monospecific antisaposin D antibody that crossreacts with prosaposin but not with saposins A, B, or C, immunoblot experiments showed that both the central and peripheral nervous systems express unprocessed prosaposin and little saposin D. Using the antisaposin D antibodies, we demonstrated that prosaposin is abundant in almost all neurons of both the central and peripheral nervous systems, including autonomic nerves, as well as motor and sensory nerves. Immunoelectron microscopy using double staining with antisaposin D and anticathepsin D antibodies showed strong prosaposin immunoreactivity mainly in the lysosomal granules in the neurons in both the central and peripheral nervous systems. The expression of prosaposin mRNA, examined using in situ hybridization, was observed in these same neurons. Our results suggest that prosaposin is synthesized ubiquitously in neurons of both the central and peripheral nervous systems.
prosaposin是四种溶酶体水解酶鞘脂激活蛋白（鞘脂激活蛋白A、B、C和D）的前体，在神经系统和肌肉中含量丰富。除了作为溶酶体中鞘脂激活蛋白的前体发挥作用外，完整的prosaposin在外源供应时在体内或体外具有神经营养作用。我们研究了prosaposin在中枢和外周神经系统中的分布及其细胞内分布。使用一种与prosaposin发生交叉反应但不与鞘脂激活蛋白A、B或C发生反应的单特异性抗鞘脂激活蛋白D抗体，免疫印迹实验表明，中枢和外周神经系统均表达未加工的prosaposin，而鞘脂激活蛋白D含量很少。使用抗鞘脂激活蛋白D抗体，我们证明prosaposin在中枢和外周神经系统的几乎所有神经元中都很丰富，包括自主神经以及运动和感觉神经。使用抗鞘脂激活蛋白D和抗组织蛋白酶D抗体进行双重染色的免疫电子显微镜显示，prosaposin免疫反应性主要在中枢和外周神经系统神经元的溶酶体颗粒中很强。使用原位杂交检测prosaposin mRNA的表达，在这些相同的神经元中也观察到了。我们的结果表明，prosaposin在中枢和外周神经系统的神经元中普遍合成。
