Gupta S K, Poduslo J F, Dunn R, Roder J, Mezei C
Department of Biochemistry, Dalhousie University, Halifax, Canada.
Dev Neurosci. 1990;12(1):22-33. doi: 10.1159/000111832.
The distal segments of the crush-injured and permanently transected sciatic nerve provide models to study Schwann cell activity in the presence and absence of Schwann cell-axonal contact, respectively. We examined the quantity and quality of transcript coding for the myelin-associated glycoprotein (MAG) over a 3-week period following crush injury and at 35 days after transection to investigate possible regulation of this gene during nerve injury and subsequent repair. Northern blot and slot blot analysis indicated a sharp decrease in levels of MAG mRNA 2 days after crush injury which was followed by a progressive increase in levels of message between 7 and 21 days after injury. Western blot analysis showed that levels of MAG protein decreased substantially 7 days after crush injury, which returned to 70% of the adult value by 21 days after injury. MAG mRNA and protein were undetectable by Northern and Western analysis, respectively, in the distal segment of the sciatic nerve 35 days after permanent transection. This infers distinct down-regulation of MAG gene expression after permanent transection of a peripheral nerve. These comparative studies of MAG transcripts and encoded protein may indicate regulation of MAG gene expression at the level of transcription, and possibly at the level of post-transcription in these experimental models of peripheral neuropathies.
挤压损伤和永久性横断的坐骨神经远段分别为研究施万细胞在有和没有施万细胞-轴突接触情况下的活性提供了模型。我们在挤压损伤后的3周内以及横断后35天检测了髓磷脂相关糖蛋白（MAG）编码转录本的数量和质量，以研究该基因在神经损伤及随后修复过程中可能的调控情况。Northern印迹和狭缝印迹分析表明，挤压损伤后2天MAG mRNA水平急剧下降，随后在损伤后7至21天内mRNA水平逐渐升高。蛋白质印迹分析显示，挤压损伤后7天MAG蛋白水平大幅下降，损伤后21天恢复至成年值的70%。在永久性横断35天后，坐骨神经远段经Northern和蛋白质印迹分析分别未检测到MAG mRNA和蛋白。这表明外周神经永久性横断后MAG基因表达有明显下调。这些对MAG转录本和编码蛋白的比较研究可能表明在这些外周神经病变实验模型中，MAG基因表达在转录水平以及可能在转录后水平受到调控。
