In the developing nervous system, extending axons are directed towards their appropriate targets by a myriad of attractive and repulsive guidance cues. Work in the past decade has significantly advanced our understanding of these molecules and has made it increasingly clear that their function is not limited to the guidance of growing axons during embryogenesis. Axon guidance cues fulfill additional roles in angiogenesis, cell migration and the immune system, and often display sustained expression in adulthood. Here we focus on the semaphorin (Sema) family and review their proposed functions in the adult nervous system. Several semaphorin family members continue to be expressed in the adult brain and spinal cord, and increasing evidence indicates that their expression is regulated upon nervous system injury in rodents and in neuropathology in humans. The available evidence suggests that semaphorins might significantly contribute to the maintenance and stability of neuronal networks. Furthermore, semaphorins could play important roles in the regeneration, or failure thereof, of neuronal connections. In the future, genetic manipulation of semaphorins and their receptors in the adult intact and injured nervous system should provide a deeper insight into the mechanisms by which semaphorin signaling contributes to structural plasticity and regeneration in the adult brain.

中文翻译：

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信号量在成人神经系统中的作用。

在发育中的神经系统中，无数引人入胜的排斥性引导线索将轴突伸向适当的靶标。在过去的十年中，研究工作大大提高了我们对这些分子的了解，并且越来越清楚地表明，它们的功能不仅限于在胚胎发生过程中生长轴突的指导。轴突指导线索在血管生成，细胞迁移和免疫系统中发挥其他作用，并且通常在成年期表现出持续表达。在这里，我们重点介绍信号量（Sema）家族，并综述其在成人神经系统中的拟议功能。在成人的大脑和脊髓中，仍有一些信号量家族成员继续表达，越来越多的证据表明，它们的表达受啮齿动物和人类神经病理学的神经系统损伤的调节。现有证据表明，信号量可能会极大地促进神经网络的维持和稳定。此外，信号量可能在神经元连接的再生或失败中起重要作用。将来，对成人完整和受损神经系统中的信号量及其受体进行基因操作，应该可以更深入地了解信号量信号传导有助于成人大脑结构可塑性和再生的机制。信号量可能在神经元连接的再生或失败中起重要作用。将来，对成人完整和受损神经系统中的信号量及其受体进行基因操作，应该可以更深入地了解信号量信号传导有助于成人大脑结构可塑性和再生的机制。信号量可能在神经元连接的再生或失败中起重要作用。将来，对成人完整和受损神经系统中的信号量及其受体进行基因操作，应该可以更深入地了解信号量信号传导有助于成人大脑结构可塑性和再生的机制。