IMMUNOHISTOLOGICAL LOCALIZATION OF THE ADHESION MOLECULES L1, N-CAM, AND MAG IN THE DEVELOPING AND ADULT OPTIC-NERVE OF MICE
IMMUNOHISTOLOGICAL LOCALIZATION OF THE ADHESION MOLECULES L1, N-CAM, AND MAG IN THE DEVELOPING AND ADULT OPTIC-NERVE OF MICE
复制标题
DOI：
10.1002/cne.902840310
复制
发表时间：
1989-06-15
影响因子：
2.5
通讯作者：
SCHACHNER, M
中科院分区：
文献类型：
--
作者：
BARTSCH, U;KIRCHHOFF, F;SCHACHNER, M
在光镜和电镜水平和免疫化学的发展和成年小鼠视神经和视网膜的细胞粘附分子L1，神经细胞粘附分子（N-CAM），髓鞘相关糖蛋白（MAG）的本地化进行了研究。从胚胎第15天到成年，在所有年龄段，神经粘附分子L1在成束无髓鞘轴突轴上都有强烈表达。视网膜神经节细胞轴突的生长锥弱L1阳性或L1阴性时，接触胶质细胞。无髓轴突不仅L1阳性时，彼此接触，但也接触神经胶质细胞，而神经胶质细胞之间的接触是L1阴性的在所有的发展阶段。在无髓视网膜神经纤维层或无髓视神经乳头中以成束状态表达L1的相同轴突在被视神经中的髓鞘包裹时变为L1阴性。在发育的各个阶段，N-CAM在成束轴突、生长锥及其与神经胶质细胞的接触部位以及神经胶质细胞之间的接触部位上显示出丰富的标记。与L1相反，轴突在有髓鞘时保持N-CAM阳性。N-CAM有时见于致密的髓鞘中。然而，N-CAM不存在于与脑膜、血管和眼睛玻璃体的界面处的基底膜接触的神经胶质表面。MAG首先在与内质网和高尔基体相关的少突胶质细胞中细胞内检测到，然后在细胞表面变得明显。在轴突鞘化之前和第一阶段，它存在于少突胶质细胞上，无论是在细胞体还是在突起上。在形成致密髓鞘后，MAG仍然在轴突周围强烈表达，仅在非致密髓鞘（包括内层轴突和结旁环）中微弱地检测到。细胞外基质、脑膜或内皮细胞上均未检测到粘附分子。免疫化学分析的抗原表达在不同的发展阶段是一致的免疫组织学数据。我们从这些观察结果推断，L1不仅参与轴突-轴突的稳定，而且参与轴突-胶质细胞接触，而生长锥的更动态结构通常表达较少的L1。L1沿着轴突的路线的差异表达存在于其无髓鞘部分，但不存在于其有髓鞘部分，这进一步支持了L1可能参与轴突束的稳定而不是轴突-髓鞘接触的稳定的观点。由于轴突-星形胶质细胞并置是L1阴性的节点Ranvier和L1阳性的无髓鞘的地区，L1似乎发挥了区域差异的功能作用，神经元-星形胶质细胞的相互作用。MAG似乎参与髓鞘形成开始前轴突-少突胶质细胞相互作用的启动，以及成熟髓鞘中神经元-少突胶质细胞和少突胶质细胞-少突胶质细胞接触的稳定。由于其一般发生在所有细胞类型之间的接触，除了星形胶质细胞基底膜沉积，N-CAM似乎是负责一般稳定的组织完整性在所有发育阶段的研究和成人。
The localization of the cell adhesion molecules L1, neural cell adhesion molecule (N-CAM), and myelin-associated glycoprotein (MAG) was studied immunohistologically at the light and electron microscopic levels and immunochemically in the developing and adult mouse optic nerve and retina. The neural adhesion molecule L1 is strongly expressed on the shafts of fasciculating unmyelinated axons at all ages studied from embryonic day 15 through adulthood. Growth cones of retinal ganglion cell axons were weakly L1-positive or L1-negative when contacting glial cells. Unmyelinated axons were not only L1-positive when contacting each other but also when contacting glia, whereas contacts between glial cells were L1-negative at all developmental stages. The same axons that expressed L1 in their fasciculating state in the unmyelinated retinal nerve fiber layer or in the unmyelinated optic nerve head became L1-negative when enwrapped by myelin in the optic nerve proper. At all stages of development N-CAM showed profuse labeling on fasciculating axons, growth cones, and their contact sites with glial cells as well as contacts between glial cells. In contrast to L1, axons remained N-CAM-positive when becoming myelinated. Sometimes, N-CAM was found in compact myelin. However, N-CAM was absent from glial surfaces contacting basement membranes at the interface to meninges, blood vessels, and the vitreous body of the eye. MAG was first detectable intracellularly in oligodendrocytes associated with the endoplasmic reticulum and Golgi apparatus before it became apparent at the cell surface. There it was present on oligodendrocytes prior and during the first stages of ensheathment of axons, both on cell body and processes. After formation of compact myelin MAG remained strongly expressed periaxonally and was only weakly detectable in noncompacted myelin including inner mesaxon and paranodal loops. None of the adhesion molecules was detectable on extracellular matrix, in the meninges, or on endothelial cells. Immunochemical analysis of antigen expression at different developmental stages was in agreement with the immunohistological data. We infer from these observations that L1 is involved in stabilization not only of axon-axon, but also axon-glia contacts, while the more dynamic structure of the growth cone generally expresses less L1. A differential expression of L1 along the course of an axon.sbd.being present on its unmyelinated, but absent on its myelinated part.sbd.further supports the notion that L1 may be involved in the stabilization of axonal fascicles but not of axon-myelin contacts. Since axon-astrocyte appositions are L1-negative at the node of Ranvier and L1-positive in nonmyelinated areas, L1 appears to play a regionally differential functional role in neuron-astrocyte interactions. MAG seems to be involved in the initiation of axon-oligodendrocyte interactions before the onset of myelination and in the stabilization of neuron-oligodendrocyte and oligodendrocyte-oligodendrocyte contacts in the mature myelin. Because of its general occurrence at contacts between all cell types studied except for the astroglial-basement membrane apposition, N-CAM appears to be responsible for the general stabilization of tissue integrity at all developmental stages studied and in the adult.