Cheng L, Mudge A W
Department of Biology, University College London, United Kingdom.
Neuron. 1996 Feb;16(2):309-19. doi: 10.1016/s0896-6273(00)80049-5.
It is widely thought that mammalian Schwann cells do not express Po, the major glycoprotein in peripheral myelin, unless they are induced to do so by axonal signals that can be mimicked by agents that trigger cAMP signaling pathways. In contrast, we find that cultured Schwann cells make large amounts of Po without the addition of any axonal-like signal, provided they have not been exposed to serum during the culture process. We also report that glial growth factor/neuregulin inhibits this constitutive Po expression. Myelin basic protein is regulated in a similar way. We suggest that expression of Po by Schwann cells before the onset of myelination may be prevented by inhibitory signals within the nerve, rather than by the absence of a positive signal from axons.
人们普遍认为，哺乳动物的施万细胞不表达外周髓鞘中的主要糖蛋白Po，除非它们被轴突信号诱导表达，而能触发cAMP信号通路的物质可以模拟这些轴突信号。相比之下，我们发现，培养的施万细胞在不添加任何类轴突信号的情况下就能大量产生Po，前提是它们在培养过程中未接触血清。我们还报告称，胶质细胞生长因子/神经调节蛋白会抑制这种组成型Po表达。髓鞘碱性蛋白也以类似方式受到调节。我们认为，在髓鞘形成开始之前，施万细胞中Po的表达可能是被神经内的抑制性信号所阻止，而不是因为缺乏来自轴突的正向信号。
