Blissman G, Menzies S, Beard J, Palmer C, Connor J
George M. Leader Family Laboratory for Alzheimer's Disease Research, Hershey, Pa., USA.
Dev Neurosci. 1996;18(4):274-81. doi: 10.1159/000111417.
Myelination is an essential component of normal development in the brain. Thus, the factors which influence the onset of myelination need to be identified and monitored during development to insure adequate myelination. These factors may also play a role in remyelination attempts which occur as a result of demyelinating diseases. One factor known to be involved in myelination is iron. In this study, the cellular deposition of iron and the intracellular iron storage protein ferritin are examined in the brains of 1-month-old piglets. Ferritin consists of 2 subunits (H and L chains) which occur in different ratios in different organs. The subunits are functionally distinct so their pattern of expression at the cellular level reveals information about the iron requirement of the cell and utilization versus storage. The H subunit of ferritin is expressed in abundance in oligodendrocytes within white-matter tracts whereas the L subunit in this region is found only in endothelial cells of blood vessels. H-ferritin-positive cells occur in clearly defined patches which are scattered throughout the white-matter tracts. The cellular distribution of iron is identical to that of H ferritin. H-ferritin-positive cells are identified as oligodendrocytes on the basis of immunofluorescent colocalization with CNPase. Also, some of the H-ferritin-positive cells are positive for myelin basic protein. However, the distribution of CNPase-positive cells is more even in the white matter than the patches of H-ferritin/iron-positive cells. The relationship between H-ferritin- and CNPase-positive cells indicates that the former are oligodendrocytes, but also reveals a subset of oligodendrocytes in the white matter. The results of this study provide insight into how the intracellular iron is managed in oligodendrocytes. The factors which initiate iron uptake and ferritin expression in a select population of oligodendrocytes, and the relationship of this select population to myelinogenesis and myelin maintenance, have yet to be identified.
髓鞘形成是大脑正常发育的重要组成部分。因此，在发育过程中需要识别和监测影响髓鞘形成起始的因素，以确保有足够的髓鞘形成。这些因素在因脱髓鞘疾病而发生的髓鞘再生过程中也可能起作用。已知参与髓鞘形成的一个因素是铁。在本研究中，对1月龄仔猪大脑中铁的细胞沉积和细胞内铁储存蛋白铁蛋白进行了检测。铁蛋白由2个亚基（H链和L链）组成，它们在不同器官中的比例不同。这些亚基功能不同，因此它们在细胞水平的表达模式揭示了有关细胞铁需求以及利用与储存的信息。铁蛋白的H亚基在白质束内的少突胶质细胞中大量表达，而该区域的L亚基仅在血管内皮细胞中发现。H铁蛋白阳性细胞出现在明确界定的斑块中，这些斑块散布于整个白质束。铁的细胞分布与H铁蛋白的分布相同。基于与CNPase的免疫荧光共定位，H铁蛋白阳性细胞被鉴定为少突胶质细胞。此外，一些H铁蛋白阳性细胞髓鞘碱性蛋白呈阳性。然而，白质中CNPase阳性细胞的分布比H铁蛋白/铁阳性细胞斑块更均匀。H铁蛋白阳性细胞与CNPase阳性细胞之间的关系表明前者是少突胶质细胞，但也揭示了白质中少突胶质细胞的一个亚群。本研究结果为少突胶质细胞内铁的管理方式提供了见解。启动特定少突胶质细胞群体中铁摄取和铁蛋白表达的因素，以及该特定群体与髓鞘形成和髓鞘维持的关系，尚待确定。
