The cytoskeleton builds and supports the complex architecture of neurons. It orchestrates the specification, growth, and compartmentation of the axon: axon initial segment, axonal shaft, presynapses. The cytoskeleton must then maintain this intricate architecture for the whole life of its host, but also drive its adaptation to new network demands and changing physiological conditions. Microtubules are readily visible inside axon shafts by electron microscopy, whereas axonal actin study has long been focused on dynamic structures of the axon such as growth cones. Super-resolution microscopy and live-cell imaging have recently revealed new actin-based structures in mature axons: rings, hotspots and trails. This has caused renewed interest for axonal actin, with efforts underway to understand the precise organization and cellular functions of these assemblies. Actin is also present in presynapses, where its arrangement is still poorly defined, and its functions vigorously debated. Here we review the organization of axonal actin, focusing on recent advances and current questions in this rejuvenated field.

细胞骨架建立并支持神经元的复杂结构。它编排了轴突的规格，生长和分隔：轴突初始段，轴突轴，突触前突触。然后，细胞骨架必须在其宿主的整个生命中保持这种复杂的结构，而且还必须使其适应新的网络需求和不断变化的生理状况。通过电子显微镜可以容易地在轴突轴内部看到微管，而轴突肌动蛋白的研究长期以来一直专注于轴突的动态结构，例如生长锥。超分辨率显微镜和活细胞成像最近揭示了成熟轴突中基于肌动蛋白的新结构：环，热点和尾迹。这引起了对轴突肌动蛋白的新兴趣，正在努力了解这些组件的精确组织和单元功能。肌动蛋白也存在于突触前，在那里其排列仍不清楚，并且对其功能进行了激烈的辩论。在这里，我们回顾了轴突肌动蛋白的组织，着重于这个复兴领域中的最新进展和当前问题。