Arvanitis D, Dumas M, Szuchet S
Department of Pathology, Aghia Sophia Children's Hospital, Athens, Greece.
Dev Neurosci. 1992;14(5-6):328-35. doi: 10.1159/000111679.
Myelin is a membrane with unique characteristics that set it apart from any other membrane. It has a very high lipid:protein ratio (approximately 75:25) not found in other multilamellar membranes; it has a high content of two glycolipids--galactocerebrosides and sulfatides--which account for 26.5% of its lipids. The physiological role of these glycolipids in myelin and/or oligodendrocytes is unknown, but evidence that Abs directed against them interfere with myelination has been presented. Moreover, one of the early events in the process of oligodendrocyte differentiation prior to myelination is the acquisition of galactocerebroside on their surface. In earlier work, we have demonstrated that adhesion of oligodendrocytes to a positively charged substratum signals the commencement of myelinogenesis. Among the events that take place following adhesion are the rapid synthesis of glycolipids. Since over time in culture, oligodendrocytes elaborate multilamellar membranes that contain all the myelin characteristic proteins, we undertook to investigate whether these structures also accumulate myelin characteristic glycolipids. We have used three monoclonal antibodies--two are directed against galactocerebroside, the third one is an antisulfatide--in conjunction with the immunogold method, at the electron microscopic level, to examine the distribution of these glycolipids in the multilammelar structures that accumulate in long-term oligodendrocyte cultures. Our data show that galactocerebrosides and sulfatides are present in the multilamellar structures. Staining is easily demonstrated on the outermost membrane. However, as was the situation with myelin proteins, detection of these glycolipids on the inner lamellae is only achieved at the expense of destroying the ultrastructure. This is so, independent of whether the structures are compact or not.(ABSTRACT TRUNCATED AT 250 WORDS)
髓磷脂是一种具有独特特性的膜，使其有别于其他任何膜。它具有非常高的脂质与蛋白质比例（约为75:25），这在其他多层膜中并不存在；它含有高含量的两种糖脂——半乳糖脑苷脂和硫脂——占其脂质的26.5%。这些糖脂在髓磷脂和/或少突胶质细胞中的生理作用尚不清楚，但已有证据表明，针对它们的抗体干扰髓鞘形成。此外，在髓鞘形成之前少突胶质细胞分化过程中的早期事件之一是其表面获得半乳糖脑苷脂。在早期工作中，我们已经证明少突胶质细胞与带正电荷的基质的粘附标志着髓鞘形成的开始。粘附后发生的事件包括糖脂的快速合成。由于在培养过程中，少突胶质细胞会形成包含所有髓磷脂特征性蛋白质的多层膜，我们着手研究这些结构是否也积累髓磷脂特征性糖脂。我们使用了三种单克隆抗体——两种针对半乳糖脑苷脂，第三种针对硫脂——结合免疫金方法，在电子显微镜水平上，检查这些糖脂在长期少突胶质细胞培养物中积累的多层结构中的分布。我们的数据表明，半乳糖脑苷脂和硫脂存在于多层结构中。染色很容易在最外层膜上显示出来。然而，与髓磷脂蛋白的情况一样，只有以破坏超微结构为代价才能在内层薄片上检测到这些糖脂。无论这些结构是否紧密，情况都是如此。（摘要截断于250字）
