Department of Neuroscience, University of Pennsylvania School of Medicine, 421 Curie Boulevard, BRB2/3 1113, Philadelphia, PA 19104, USA.
Curr Opin Neurobiol. 2010 Feb;20(1):79-85. doi: 10.1016/j.conb.2009.12.006. Epub 2010 Jan 14.
In bilaterally symmetric organisms, the midline is a critical organizing center for the developing central nervous system. There is a striking conservation of the molecules and mechanisms that control axon path finding at the midline in vertebrate and invertebrate nervous systems. The majority of axons in the CNS cross the midline before projecting to their contralateral synaptic targets and this crossing decision is under exquisite spatial and temporal regulation. Growing commissural axons initially respond to attractive signals, while inhibiting responses to repulsive signals. Once across, repulsion dominates, allowing axons to leave and preventing them from re-entering the midline. Here we review recent advances in flies and mice that illuminate the molecular mechanisms underlying the establishment of precise connectivity at the midline.
在双侧对称的生物体中，中线是中枢神经系统发育的关键组织中心。在脊椎动物和无脊椎动物的神经系统中，控制神经轴突在中线上寻路的分子和机制有着惊人的保守性。中枢神经系统中的大多数轴突在投射到它们对侧的突触靶点之前都会穿过中线，而这个穿越的决定受到精细的时空调节。生长的连合轴突最初对吸引信号做出反应，同时抑制对排斥信号的反应。一旦穿过中线，排斥就会占据主导地位，允许轴突离开并防止它们重新进入中线。在这里，我们回顾了在果蝇和小鼠中取得的最新进展，这些进展阐明了在中线上建立精确连接的分子机制。
