Gupta S K, Pringle J, Poduslo J F, Mezei C
Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
J Neurosci Res. 1993 Jan;34(1):14-23. doi: 10.1002/jnr.490340103.
The effect of a permanent transection on myelin gene expression in a regenerating sciatic nerve and in an adult sciatic nerve was compared to establish the degree of axonal control exerted upon Schwann cells in each population. First, the adult sciatic nerve was crushed, and the distal segment allowed to regenerate. At 12 days post-crush, the sciatic nerve was transected distal to the site of crush to disrupt the Schwann cell-axonal contacts that had reformed. Messenger RNA (mRNA) levels coding for five myelin proteins were assayed in the distal segment of the crush-transected nerve after 9 days and were compared to corresponding levels in the distal segments of sciatic nerves at 21 days post-crush and 21 days post-transection using Northern blot and slot-blot analysis. Levels of mRNAs found in the distal segment of the transected and crush-transected nerve suggested that Schwann cells in the regenerating nerve and in the mature adult nerve are equally responsive to axonal influences. The crush-transected model allowed the genes that were studied to be classified according to their response to Schwann cell-axonal contact. The levels of mRNAs were 1) down-regulated to basal levels (P0 and MBP mRNAs), 2) down-regulated to undetectable levels (myelin-associated glycoprotein mRNAs), 3) upregulated (mRNAs encoding 2'3'-cyclic nucleotide phosphodiesterase and beta-actin), or 4) not stringently controlled by the removal of Schwann cell-axonal contact (proteolipid protein mRNAs). This novel experimental model has thus provided evidence that the expression of some of the important myelin genes during peripheral nerve regeneration is dependent on continuous signals from the ingrowing axons.
比较永久性横断对再生坐骨神经和成年坐骨神经中髓鞘基因表达的影响，以确定每个群体中轴突对施万细胞施加的控制程度。首先，对成年坐骨神经进行挤压，让远端部分再生。在挤压后12天，在挤压部位远端横断坐骨神经，以破坏已经重新形成的施万细胞 - 轴突接触。在9天后，对挤压 - 横断神经的远端部分中编码五种髓鞘蛋白的信使核糖核酸（mRNA）水平进行检测，并使用Northern印迹和狭缝印迹分析，将其与挤压后21天和横断后21天坐骨神经远端部分的相应水平进行比较。在横断和挤压 - 横断神经远端部分中发现的mRNA水平表明，再生神经和成熟成年神经中的施万细胞对轴突影响的反应相同。挤压 - 横断模型使所研究的基因能够根据它们对施万细胞 - 轴突接触的反应进行分类。mRNA水平分别为：1）下调至基础水平（P0和髓磷脂碱性蛋白mRNA），2）下调至不可检测水平（髓鞘相关糖蛋白mRNA），3）上调（编码2'3'-环核苷酸磷酸二酯酶和β-肌动蛋白的mRNA），或4）不受施万细胞 - 轴突接触去除的严格控制（蛋白脂蛋白mRNA）。因此，这个新的实验模型提供了证据，表明周围神经再生过程中一些重要髓鞘基因的表达依赖于向内生长轴突的持续信号。
