Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, 13005 Marseille, France.
Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974, Paris, France.
Science. 2024 Aug 23;385(6711):eado2032. doi: 10.1126/science.ado2032.
Clathrin-mediated endocytosis has characteristic features in neuronal dendrites and presynapses, but how membrane proteins are internalized along the axon shaft remains unclear. We focused on clathrin-coated structures and endocytosis along the axon initial segment (AIS) and their relationship to the periodic actin-spectrin scaffold that lines the axonal plasma membrane. A combination of super-resolution microscopy and platinum-replica electron microscopy on cultured neurons revealed that AIS clathrin-coated pits form within "clearings", circular areas devoid of actin-spectrin mesh. Actin-spectrin scaffold disorganization increased clathrin-coated pit formation. Cargo uptake and live-cell imaging showed that AIS clathrin-coated pits are particularly stable. Neuronal plasticity-inducing stimulation triggered internalization of the clathrin-coated pits through polymerization of branched actin around them. Thus, spectrin and actin regulate clathrin-coated pit formation and scission to control endocytosis at the AIS.
网格蛋白介导的内吞作用在神经元树突和突触前具有特征性，但沿着轴突轴如何内化膜蛋白尚不清楚。我们专注于网格蛋白包被结构和沿着轴突起始段 (AIS) 的内吞作用及其与周期性肌动蛋白-血影蛋白支架的关系，该支架排列在轴突质膜上。在培养神经元上进行的超分辨率显微镜和铂复制电子显微镜的组合揭示了 AIS 网格蛋白包被陷窝形成于“间隙”内，即没有肌动蛋白-血影蛋白网格的圆形区域内。肌动蛋白-血影蛋白支架的解聚增加了网格蛋白包被陷窝的形成。货物摄取和活细胞成像表明，AIS 网格蛋白包被陷窝特别稳定。神经元可塑性诱导刺激通过围绕网格蛋白包被陷窝的分支肌动蛋白聚合触发其内化。因此，血影蛋白和肌动蛋白调节网格蛋白包被陷窝的形成和分裂，以控制 AIS 处的内吞作用。
