Jacobs Erin C, Bongarzone Ernesto R, Campagnoni Celia W, Kampf Kathy, Campagnoni Anthony T
Developmental and Molecular Neuroscience Group, Neuropsychiatric Institute, UCLA School of Medicine, Los Angeles, Calif 90024-17519, USA.
Dev Neurosci. 2003 Mar-Aug;25(2-4):96-104. doi: 10.1159/000072259.
The myelin proteolipid gene encodes two sets of proteins, the classic PLP and DM20 and the sr (soma-restricted)-PLP and sr-DM20. Unlike the classic proteolipids, the sr-products are expressed in both neurons and oligodendrocytes (OLs) and are not components of the myelin sheath. In OLs, the sr-isoforms are associated with endosomes and recycling vesicles indicating a possible nonmyelin function for these proteins. In this study, a purified antibody specific for the sr-products was used to examine the expression of these proteins during the development of the mouse brain. We found that while sr-PLP and sr-DM20 are expressed in OLs, the highest levels of immunoreactivity were found in neuronal populations. During early embryonic development (E13-E15), sr-proteolipids were detected in the dorsal root ganglion and motor neurons in the spinal cord. By E17, immunostaining for sr-PLP and sr-DM20 in the brain increased dramatically. The highest levels of immunoreactivity were found during the first and second weeks postnatal after which staining intensity declined to adult levels and the pattern of expression was more restricted. Robust staining persisted in many neuronal populations including nuclei in the hindbrain, Purkinje and granule neurons in the cerebellum, pyramidal cells in the cortex and mitral cells in the olfactory bulb. The spatial and temporal pattern of sr-PLP and sr-DM20 expression is very similar to that of the endosomal protein, syntaxin 13, consistent with the finding that the sr-PLPs may play a role in vesicular transport in neurons.
髓磷脂蛋白脂蛋白基因编码两组蛋白质，即经典的PLP和DM20以及sr（胞体受限）-PLP和sr-DM20。与经典的蛋白脂蛋白不同，sr产物在神经元和少突胶质细胞（OL）中均有表达，且不是髓鞘的组成成分。在OL中，sr异构体与内体和循环囊泡相关，表明这些蛋白质可能具有非髓鞘功能。在本研究中，使用针对sr产物的纯化抗体来检测这些蛋白质在小鼠脑发育过程中的表达。我们发现，虽然sr-PLP和sr-DM20在OL中表达，但免疫反应性最高的是神经元群体。在胚胎早期发育阶段（E13-E15），在背根神经节和脊髓运动神经元中检测到sr-蛋白脂蛋白。到E17时，脑中sr-PLP和sr-DM20的免疫染色显著增加。出生后第一周和第二周免疫反应性最高，之后染色强度下降至成年水平，且表达模式更局限。在许多神经元群体中，包括后脑的细胞核、小脑的浦肯野细胞和颗粒细胞、皮质的锥体细胞以及嗅球的二尖瓣细胞中，均持续存在强烈染色。sr-PLP和sr-DM20表达的时空模式与内体蛋白Syntaxin 13非常相似，这与sr-PLPs可能在神经元囊泡运输中起作用的发现一致。
