Boyles J K, Notterpek L M, Anderson L J
Gladstone Foundation Laboratories for Cardiovascular Disease, Department of Pathology, University of California, San Francisco 94140-0608.
J Biol Chem. 1990 Oct 15;265(29):17805-15.
In this report, we have identified two apolipoproteins (apo), apoD and apoA-IV, that, together with the previously identified apoA-I and apoE, accumulate in the regenerating peripheral nerve. These four apolipoproteins were identified in regenerating rat sciatic nerves by their molecular weights, their isoelectric points, and their recognition by specific antibodies. Antibodies were also used to document the changing concentrations of these apolipoproteins in homogenates of regenerating sciatic nerves collected 1 day to 6 weeks after a denervating crush injury. By 3 weeks after injury, at their peak accumulation, apoA-IV and apoA-I had increased 14- and 26-fold, respectively, relative to their concentrations in the normal nerve. Apolipoproteins D and E, in contrast, increased over 500- and 250-fold, respectively, by 3 weeks. These same apolipoproteins also accumulated in the regenerating sciatic nerves of two other species, the rabbit and the marmoset monkey. Immunocytochemistry showed that apoD was produced by astrocytes and oligodendrocytes in the normal central nervous system, and by neurolemmal or fibroblastic cells in the normal peripheral nervous system. Metabolic labeling of both apoD and apoE by [35S]methionine during an in vitro incubation of regenerating rat sciatic nerve segments confirmed that these apolipoproteins are synthesized by the nerve. Neither apoA-IV nor apoA-I was metabolically labeled, however, suggesting that they enter the nerve from the plasma. The results from this study provide evidence that several different apolipoproteins from various sources may play a role in lipid transport within neural tissues.
在本报告中，我们鉴定出两种载脂蛋白（apo），即载脂蛋白D和载脂蛋白A-IV，它们与先前鉴定出的载脂蛋白A-I和载脂蛋白E一起，在再生的周围神经中蓄积。通过其分子量、等电点以及特异性抗体的识别，在再生的大鼠坐骨神经中鉴定出了这四种载脂蛋白。抗体还用于记录去神经挤压损伤后1天至6周收集的再生坐骨神经匀浆中这些载脂蛋白浓度的变化。损伤后3周，在其蓄积峰值时，载脂蛋白A-IV和载脂蛋白A-I相对于正常神经中的浓度分别增加了14倍和26倍。相比之下，载脂蛋白D和载脂蛋白E在3周时分别增加了500倍和250倍以上。这四种相同的载脂蛋白也在另外两个物种，即兔子和狨猴的再生坐骨神经中蓄积。免疫细胞化学显示，载脂蛋白D在正常中枢神经系统中由星形胶质细胞和少突胶质细胞产生，在正常周围神经系统中由神经膜细胞或成纤维细胞产生。在对再生的大鼠坐骨神经节段进行体外孵育期间，用[35S]甲硫氨酸对载脂蛋白D和载脂蛋白E进行代谢标记，证实这些载脂蛋白是由神经合成的。然而，载脂蛋白A-IV和载脂蛋白A-I均未被代谢标记，这表明它们是从血浆进入神经的。本研究结果提供了证据，表明来自不同来源的几种不同载脂蛋白可能在神经组织内的脂质转运中起作用。
