PDF(Pubmed)
Abstract：
Functions of the cerebellar cortex, from motor learning to emotion and cognition, depend on the appropriate molecular composition at diverse synapse types. Glutamate receptor distributions have been partially mapped using immunogold electron microscopy. However, information is lacking on the distribution of many other components, such as Shank2, a postsynaptic scaffolding protein whose cerebellar dysfunction is associated with autism spectrum disorders. Here, we used an adapted Magnified Analysis of the Proteome, an expansion microscopy approach, to map multiple glutamate receptors, scaffolding and signaling proteins at single synapse resolution in the cerebellar cortex. Multiple distinct synapse-selective distribution patterns were observed. For example, AMPA receptors were most concentrated at synapses on molecular layer interneurons and at climbing fiber synapses, Shank1 was most concentrated at parallel fiber synapses on Purkinje cells, and Shank2 at both climbing fiber and parallel fiber synapses on Purkinje cells but little on molecular layer interneurons. Our results are consistent with gene expression data but also reveal input-selective targeting within Purkinje cells. In specialized glomerular structures of the granule cell layer, AMPA receptors as well as most other synaptic components preferentially targeted to synapses. However, NMDA receptors and the synaptic GTPase activating protein SynGAP preferentially targeted to extrasynaptic sites. Thus, glomeruli may be considered integrative signaling units through which mossy fibers differentially activate synaptic AMPA and extrasynaptic NMDA receptor complexes. Furthermore, we observed NMDA receptors and SynGAP at adherens junctions, suggesting a role in structural plasticity of glomeruli. Altogether, these data contribute to mapping the cerebellar \'synaptome\'.
摘要：
小脑皮层的功能,从运动学习到情感和认知，取决于不同突触类型的适当分子组成。已使用免疫金电子显微镜对谷氨酸受体分布进行了部分定位。然而,缺乏许多其他组件分布的信息，例如Shank2，一种突触后支架蛋白，其小脑功能障碍与自闭症谱系障碍有关。这里,我们使用了蛋白质组的适应性放大分析，扩展显微镜方法，绘制多个谷氨酸受体，小脑皮质单突触分辨率的支架和信号蛋白。观察到多种不同的突触选择性分布模式。例如,AMPA受体最集中在分子层中间神经元的突触和攀爬纤维突触，Shank1最集中在浦肯野细胞的平行纤维突触上，和Shank2在浦肯野细胞上的攀爬纤维和平行纤维突触，但在分子层中间神经元上很少。我们的结果与基因表达数据一致，但也揭示了浦肯野细胞内的输入选择性靶向。在颗粒细胞层的特殊肾小球结构中，AMPA受体以及大多数其他突触成分优先靶向突触。然而,NMDA受体和突触GTP酶激活蛋白SynGAP优先靶向突触外位点。因此，肾小球可能被认为是整合的信号单元，苔藓纤维通过它差异激活突触AMPA和突触外NMDA受体复合物。此外，我们在粘附连接处观察到NMDA受体和SynGAP，提示在肾小球的结构可塑性中起作用。总之,这些数据有助于绘制小脑突触组。
