EVIDENCE FOR AN EARLY ROLE FOR MYELIN-ASSOCIATED GLYCOPROTEIN IN THE PROCESS OF MYELINATION
EVIDENCE FOR AN EARLY ROLE FOR MYELIN-ASSOCIATED GLYCOPROTEIN IN THE PROCESS OF MYELINATION
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DOI：
10.1002/glia.440020208
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发表时间：
1989-01-01
期刊：
影响因子：
6.2
通讯作者：
BUNGE, RP
中科院分区：
文献类型：
--
作者：
OWENS, GC;BUNGE, RP
使用免疫细胞化学将纯化的大鼠雪旺细胞与背根神经节神经元共培养后髓磷脂相关糖蛋白 (MAG) 的表达与半乳糖脑苷脂 (GalC) 和 Po 的表达进行比较。在不含抗坏血酸的限定无血清培养基中，雪旺细胞增殖，但既不包鞘也不形成髓鞘轴突，轴突相互作用上调细胞表面 MAG 和 GalC 的表达，但不上调 Po 的细胞表面表达。神经元细胞体的切除导致雪旺细胞表面的 MAG 和 GalC 下调。当共培养物切换为完全培养基（血清加抗坏血酸）以促进髓鞘形成时，致力于形成髓磷脂的雪旺细胞继续在其表面表达高水平的 MAG 和 GalC，但非髓鞘雪旺细胞下调 MAG 和 GalC。发育髓鞘的明显结节区域的外部存在显着的 MAG 免疫反应性。免疫染色前的透化显示，在 Po 免疫反应性出现之前，新生节间的所有雪旺细胞胞质突起均被抗 MAG 抗体显着染色。与发育中的髓鞘节段相比，成熟髓鞘节段表面的 MAG 量减少，但在节旁和 Schmidt-Lanterman 切口中存在大量的抗 MAG 染色。 MAG 的表达和定位时间表明，它可能是施万细胞吞噬注定要形成髓鞘的轴突并确定未来节间范围的过程中的关键分子。
The expression of myelin‐associated glycoprotein (MAG) in purified rat Schwann cells following coculture with dorsal root ganglion neurons was compared with the expression of galactocerebroside (GalC) and Po using immunocytochemistry. In defined serum‐free medium, lacking ascorbic acid, in which Schwann cells proliferate but neither ensheathe nor myelinate axons, axonal interaction up‐regulated the cell surface expression of MAG and GalC but not of Po. Excision of neuronal cell bodies resulted in a down‐regulation of both MAG and GalC from the Schwann cell surface. When cocultures were switched to complete medium (serum plus ascorbic acid) to promote myelination, Schwann cells committed to form myelin continued to express high levels of MAG and GalC on their surface, but nonmyelinating Schwann cells down‐regulated MAG and GalC. There was significant MAG immunoreactivity associated with the external aspect of the apparent nodal region of developing myelin sheath. Permeabilization prior to immunostaining revealed that all of the Schwann cell cytoplasmic processes of nascent internodes were significantly stained with anti‐MAG antibodies before the appearance of Po immunoreactivity. The amount of MAG on the surface of mature myelin segments was reduced compared with developing myelin segments, but there was a considerable amount of anti‐MAG staining in the paranodes and Schmidt‐Lanterman incisures. The time of expression and localization of MAG indicates that it may be a critical molecule in the process by which the Schwann cell engulfs an axon destined to be myelinated and establishes the extent of the future internode.