PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density
PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density
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DOI：
10.1073/pnas.1517045112
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发表时间：
2015-12-15
影响因子：
11.1
通讯作者：
Reese, Thomas S.
中科院分区：
文献类型：
--
作者：
Chen, Xiaobing;Levy, Jonathan M.;Reese, Thomas S.
膜相关鸟苷酸激酶（MAGUKs）的突触后致密物（PSD）-95家族是谷氨酸能兴奋性突触中PSD处的主要支架蛋白，它们在那里维持和调节突触强度。MAGUKs如何在分子水平上构成突触强度的基础仍未被很好地理解。在此，我们通过同时敲低PSD - 95、PSD - 93和突触相关蛋白（SAP）102，并结合电生理学和透射电子显微镜（TEM）断层扫描成像来分析由此产生的变化，探索MAGUKs在海马兴奋性突触中的结构和功能作用。急性MAGUK敲低极大地减少了由α - 氨基 - 3 - 羟基 - 5 - 甲基 - 4 - 异恶唑 - 丙酸受体（AMPARs）和N - 甲基 - D - 天冬氨酸受体（NMDARs）介导的突触传递。这种敲低导致沉默突触的数量显著增加，在不改变突触前或突触后膜的情况下使PSD的大小减小，并减少了膜相关的PSD - 95样垂直丝和跨膜结构的数量，通过电子显微镜断层扫描确定这些结构为AMPARs和NMDARs。这些受体样结构的差异分布以及它们的数量对PSD大小的依赖性与海马突触中AMPARs和NMDARs的情况相符。MAGUK敲低后这些结构的缺失与突触后AMPAR和NMDAR传递的减少相关，证实了这两种受体的结构身份。这些结果表明，MAGUKs是将两种类型的谷氨酸受体锚定在PSD所必需的，并且与一个结构模型相符，在该模型中，对应于膜相关垂直丝的MAGUKs是锚定和组织两种类型的谷氨酸受体并支配PSD整体分子组织的关键结构蛋白。
The postsynaptic density (PSD)-95 family of membrane-associated guanylate kinases (MAGUKs) are major scaffolding proteins at the PSD in glutamatergic excitatory synapses, where they maintain and modulate synaptic strength. How MAGUKs underlie synaptic strength at the molecular level is still not well understood. Here, we explore the structural and functional roles of MAGUKs at hippocampal excitatory synapses by simultaneous knocking down PSD-95, PSD-93, and synapse-associated protein (SAP)102 and combining electrophysiology and transmission electron microscopic (TEM) tomography imaging to analyze the resulting changes. Acute MAGUK knockdown greatly reduces synaptic transmission mediated by alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) and N-methyl-D-aspartate receptors (NMDARs). This knockdown leads to a significant rise in the number of silent synapses, diminishes the size of PSDs without changes in pre- or postsynaptic membrane, and depletes the number of membrane-associated PSD-95 like vertical filaments and transmembrane structures, identified as AMPARs and NMDARs by EM tomography. The differential distribution of these receptor-like structures and dependence of their abundance on PSD size matches that of AMPARs and NMDARs in the hippocampal synapses. The loss of these structures following MAGUK knockdown tracks the reduction in postsynaptic AMPAR and NMDAR transmission, confirming the structural identities of these two types of receptors. These results demonstrate that MAGUKs are required for anchoring both types of glutamate receptors at the PSD and are consistent with a structural model where MAGUKs, corresponding to membraneassociated vertical filaments, are the essential structural proteins that anchor and organize both types of glutamate receptors and govern the overall molecular organization of the PSD.