Griffiths I R, Dickinson P, Montague P
Applied Neurobiology Group, University of Glasgow Veterinary School, UK.
Neuropathol Appl Neurobiol. 1995 Apr;21(2):97-110. doi: 10.1111/j.1365-2990.1995.tb01035.x.
The proteolipid protein (PLP) gene encodes for two proteins, PLP and DM-20, which are produced by alternative splicing of exon 3B. PLP is the major CNS myelin protein and is postulated to play a structural role at the intraperiod line. Its developmental expression mirrors that of CNS myelination. DM-20 predominates in the embryo and prior to myelination of the CNS and may be involved in glial cell development. The PLP gene is expressed in the PNS in which DM-20 is the predominant isoform at all ages. In this study we describe the localization of the two isoforms in the post-natal rodent PNS using immunostaining and reverse transcriptase PCR. DM-20 is present in relatively high abundance in non-myelin-forming Schwann cells and within cytoplasmic regions of myelinated internodes, particularly the paranodes and Schmidt-Lanterman incisures and also the outer Schwann cytoplasm and perinuclear cytoplasm. DM-20 is also located in the perineuronal satellite cells of spinal, cranial and autonomic ganglia and in the ensheathing cells of the olfactory nerve layer of the olfactory bulb. PLP was detected by immunocytochemistry in the perinuclear region of myelinated internodes; PCR analysis indicated small amounts of PLP mRNA in the other locations but protein was not detected by immunostaining. Neither protein was identified in compact myelin of the PNS. DM-20 is the predominant product of the PLP gene expressed in a wide variety of peripheral glia. Its presence is not correlated to a myelin-forming state. Other studies have demonstrated early embryonic expression of the PLP gene throughout the PNS and all these features support the hypothesis that any putative role for DM-20 is unrelated to myelination but may involve glial cell development.
蛋白脂质蛋白（PLP）基因编码两种蛋白，即PLP和DM - 20，它们是由外显子3B的可变剪接产生的。PLP是中枢神经系统（CNS）的主要髓鞘蛋白，据推测在明暗线处起结构作用。其发育表达反映了CNS髓鞘形成的情况。DM - 20在胚胎期以及CNS髓鞘形成之前占主导地位，可能参与神经胶质细胞的发育。PLP基因在周围神经系统（PNS）中表达，在PNS中，DM - 20在所有年龄段都是主要的异构体。在本研究中，我们使用免疫染色和逆转录聚合酶链反应（RT - PCR）描述了这两种异构体在出生后啮齿动物PNS中的定位。DM - 20在非形成髓鞘的施万细胞以及有髓神经节段的细胞质区域中相对大量存在，特别是在 paranodes、施密特 - 兰特尔曼切迹以及施万细胞外细胞质和核周细胞质中。DM - 20也位于脊髓、颅神经和自主神经节的神经周卫星细胞以及嗅球嗅神经层的包被细胞中。通过免疫细胞化学在有髓神经节段的核周区域检测到了PLP；PCR分析表明在其他位置有少量PLP mRNA，但免疫染色未检测到蛋白质。在PNS的致密髓鞘中未鉴定出这两种蛋白质。DM - 20是PLP基因在多种外周神经胶质细胞中表达的主要产物。它的存在与髓鞘形成状态无关。其他研究表明PLP基因在整个PNS中早期胚胎期就有表达，所有这些特征都支持这样的假设，即DM - 20的任何假定作用都与髓鞘形成无关，但可能涉及神经胶质细胞的发育。
