Hippocampal pyramidal neurons are characterized by a unique arborization subdivided in segregated dendritic domains receiving distinct excitatory synaptic inputs with specific properties and plasticity rules that shape their respective contributions to synaptic integration and action potential firing. Although the basal regulation and plastic range of proximal and distal synapses are known to be different, the composition and nanoscale organization of key synaptic proteins at these inputs remains largely elusive. Here we used superresolution imaging and single nanoparticle tracking in rat hippocampal neurons to unveil the nanoscale topography of native GluN2A- and GluN2B-NMDA receptors (NMDARs)—which play key roles in the use-dependent adaptation of glutamatergic synapses—along the dendritic arbor. We report significant changes in the nanoscale organization of GluN2B-NMDARs between proximal and distal dendritic segments, whereas the topography of GluN2A-NMDARs remains similar along the dendritic tree. Remarkably, the nanoscale organization of GluN2B-NMDARs at proximal segments depends on their interaction with calcium/calmodulin-dependent protein kinase II (CaMKII), which is not the case at distal segments. Collectively, our data reveal that the nanoscale organization of NMDARs changes along dendritic segments in a subtype-specific manner and is shaped by the interplay with CaMKII at proximal dendritic segments, shedding light on our understanding of the functional diversity of hippocampal glutamatergic synapses.

海马锥体神经元的特征是独特的树状结构，细分为分离的树突状结构域，这些树突状结构域接收具有特定特性和可塑性规则的独特的兴奋性突触输入，这些规则和形状规则决定了它们各自对突触整合和动作电位激发的作用。尽管已知近端和远端突触的基础调节和可塑性范围不同，但是在这些输入处关键突触蛋白的组成和纳米级组织仍然很难捉摸。在这里，我们使用大鼠海马神经元中的超分辨率成像和单个纳米颗粒跟踪技术，揭示了天然GluN2A和GluN2B-NMDA受体（NMDAR）的纳米级地形图-它们在谷氨酸能突触的使用依赖性适应中以及树突状乔木中起关键作用。我们报告了近端和远端树突节之间的GluN2B-NMDARs纳米尺度组织的重大变化，而GluN2A-NMDARs的地形沿树突树仍然相似。值得注意的是，GluN2B-NMDARs的纳米级组织在近端部分取决于它们与钙/钙调蛋白依赖性蛋白激酶II（CaMKII）的相互作用，而在远端部分则并非如此。总的来说，我们的数据表明，NMDARs的纳米级组织沿树突状节段以亚型特异性方式改变，并由与CaMKII在近端树突节状段的相互作用所塑造，这为我们对海马谷氨酸能突触功能多样性的理解提供了亮点。而GluN2A-NMDAR的地形沿树突状树保持相似。值得注意的是，GluN2B-NMDARs的纳米级组织在近端部分取决于它们与钙/钙调蛋白依赖性蛋白激酶II（CaMKII）的相互作用，而在远端部分则并非如此。总的来说，我们的数据表明，NMDARs的纳米级组织沿树突状节段以亚型特异性方式改变，并由与CaMKII在近端树突节状段的相互作用所塑造，这为我们对海马谷氨酸能突触功能多样性的理解提供了亮点。而GluN2A-NMDAR的地形沿树突状树保持相似。值得注意的是，GluN2B-NMDARs的纳米级组织在近端部分取决于它们与钙/钙调蛋白依赖性蛋白激酶II（CaMKII）的相互作用，而在远端部分则并非如此。总的来说，我们的数据表明，NMDARs的纳米级组织沿树突状节段以亚型特异性方式改变，并由与CaMKII在近端树突节状段的相互作用所塑造，这为我们对海马谷氨酸能突触功能多样性的理解提供了亮点。