Zahs K R, Bigornia V, Deschepper C F
University of California, Department of Physiology, San Francisco 94143-0444.
Glia. 1993 Feb;7(2):121-33. doi: 10.1002/glia.440070202.
The brain is isolated behind a blood-tissue barrier that restricts the access of circulating proteins to neural cells. There is evidence that some of these proteins are synthesized within the central nervous system. The present study examines the synthesis and secretion of such proteins by cultured macroglial cells. Primary glial cultures were derived from cortical and subcortical regions of neonatal rat brains, and subsequent secondary cultures were enriched in type-1 astrocytes, type-2 astrocytes, or oligodendrocytes. Newly synthesized proteins were immunoprecipitated from the culture media using antisera directed against whole rat serum. All three types of glial cells secreted a range of plasma proteins. In general, type-1 astrocytes secreted more of these proteins than did type-2 astrocytes or oligodendrocytes, although the one-dimensional polyacrylamide gel electrophoresis (PAGE) profiles were specific for each cell type. Anti-sera directed against specific plasma proteins identified three of the most abundant proteins secreted by type-1 astrocytes as transferrin, alpha-2-macroglobulin, and ceruloplasmin. Northern blot analysis of cellular RNA confirmed that type-1 astrocytes contained transferrin mRNA, and that it was more abundant in cultures derived from subcortical regions than from cortical regions. In situ hybridization studies revealed that virtually all type-1 and type-2 astrocytes contained transferrin mRNA. Since the proteins identified in this study have been proposed to have a variety of neurotrophic roles in the central nervous system, these data further extend the range of possible functions that glial cells may serve in the CNS.
大脑被血组织屏障隔离，该屏障限制循环蛋白与神经细胞的接触。有证据表明，其中一些蛋白是在中枢神经系统内合成的。本研究检测了培养的大胶质细胞对这类蛋白的合成与分泌。原代胶质细胞培养物源自新生大鼠大脑的皮质和皮质下区域，随后的传代培养物富含1型星形胶质细胞、2型星形胶质细胞或少突胶质细胞。使用针对全大鼠血清的抗血清从培养基中免疫沉淀新合成的蛋白。所有三种类型的胶质细胞都分泌一系列血浆蛋白。一般来说，1型星形胶质细胞比2型星形胶质细胞或少突胶质细胞分泌更多这类蛋白，尽管一维聚丙烯酰胺凝胶电泳（PAGE）图谱对每种细胞类型具有特异性。针对特定血浆蛋白的抗血清鉴定出1型星形胶质细胞分泌的三种最丰富的蛋白为转铁蛋白、α-2-巨球蛋白和铜蓝蛋白。细胞RNA的Northern印迹分析证实1型星形胶质细胞含有转铁蛋白mRNA，并且在源自皮质下区域的培养物中比源自皮质区域的培养物中更丰富。原位杂交研究显示，几乎所有1型和2型星形胶质细胞都含有转铁蛋白mRNA。由于本研究中鉴定出的蛋白被认为在中枢神经系统中具有多种神经营养作用，这些数据进一步扩展了胶质细胞在中枢神经系统中可能发挥的功能范围。
