Molecular Neurobiology and Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, European Neuroscience Institute, D-37077 Göttingen, Germany.
J Neurosci. 2013 Aug 14;33(33):13398-409. doi: 10.1523/JNEUROSCI.6255-11.2013.
Activity-dependent regulation of AMPA receptor (AMPAR)-mediated synaptic transmission is the basis for establishing differences in synaptic weights among individual synapses during developmental and experience-dependent synaptic plasticity. Synaptic signaling scaffolds of the Discs large (DLG)-membrane-associated guanylate kinase (MAGUK) protein family regulate these processes by tethering signaling proteins to receptor complexes. Using a molecular replacement strategy with RNAi-mediated knockdown in rat and mouse hippocampal organotypic slice cultures, a postsynaptic density-95 (PSD-95) knock-out mouse line and electrophysiological analysis, our current study identified a functional interplay between two paralogs, PSD-95 and synapse-associated protein 102 (SAP102) to regulate synaptic AMPARs. During synaptic development, the SAP102 protein levels normally plateau but double if PSD-95 expression is prevented during synaptogenesis. For an autonomous function of PSD-95 in regulating synaptic AMPARs, in addition to the previously demonstrated N-terminal multimerization and the first two PDZ (PSD-95, Dlg1, zona occludens-1) domains, the PDZ3 and guanylate kinase domains were required. The Src homology 3 domain was dispensable for the PSD-95-autonomous regulation of basal synaptic transmission. However, it mediated the functional interaction with SAP102 of PSD-95 mutants to enhance AMPARs. These results depict a protein domain-based multifunctional aspect of PSD-95 in regulating excitatory synaptic transmission and unveil a novel form of domain-based interplay between signaling scaffolds of the DLG-MAGUK family.
活动依赖性调节 AMPA 受体 (AMPAAR)-介导的突触传递是在发育和经验依赖性突触可塑性过程中，个体突触之间建立突触权重差异的基础。Discs large (DLG)-膜相关鸟苷酸激酶 (MAGUK) 蛋白家族的突触信号支架通过将信号蛋白固定到受体复合物上来调节这些过程。通过在大鼠和小鼠海马器官型切片培养物中使用 RNAi 介导的敲低的分子置换策略、一个 postsynaptic density-95 (PSD-95) 敲除小鼠系和电生理分析，我们的研究当前确定了两个旁系同源物 PSD-95 和突触相关蛋白 102 (SAP102) 之间的功能相互作用，以调节突触 AMPAR。在突触发育过程中，SAP102 蛋白水平通常达到平台期，但如果在突触发生期间阻止 PSD-95 表达，则会增加一倍。对于 PSD-95 在调节突触 AMPAR 中的自主功能，除了先前证明的 N 端多聚化和前两个 PDZ（PSD-95、Dlg1、zonula occludens-1）结构域外，PDZ3 和鸟苷酸激酶结构域也是必需的。Src 同源 3 结构域对于 PSD-95 自主调节基础突触传递是可有可无的。然而，它介导了 PSD-95 与 SAP102 之间的功能相互作用，以增强 AMPAR。这些结果描绘了 PSD-95 在调节兴奋性突触传递中的基于蛋白质结构域的多功能方面，并揭示了 DLG-MAGUK 家族信号支架之间基于结构域的新型相互作用形式。
