PDF(Pubmed)
Abstract：
MAGUK scaffold proteins play a central role in maintaining and modulating synaptic signaling, providing a framework to retain and position receptors, signaling molecules, and other synaptic components. In particular, the MAGUKs SAP102 and PSD-95 are essential for synaptic function at distinct developmental timepoints and perform both overlapping and unique roles. While their similar structures allow for common binding partners, SAP102 is expressed earlier in synapse development and is required for synaptogenesis, whereas PSD-95 expression peaks later and is associated with synapse maturation. PSD-95 and other key synaptic proteins organize into subsynaptic nanodomains that have a significant impact on synaptic transmission, but the nanoscale organization of SAP102 is unknown. How SAP102 is organized within the synapse, and how it relates spatially to PSD-95 on a nanometer scale, could underlie its unique functions and impact how SAP102 scaffolds synaptic proteins. Here we used DNA-PAINT super-resolution microscopy to measure SAP102 nano-organization and its spatial relationship to PSD-95 at individual synapses in mixed-sex rat cultured neurons. We found that like PSD-95, SAP102 accumulates in high-density subsynaptic nanoclusters (NCs). However, SAP102 NCs were smaller and denser than PSD-95 NCs across development. Additionally, only a subset of SAP102 NCs co-organized with PSD-95, revealing MAGUK nanodomains within individual synapses containing either one or both proteins. These MAGUK nanodomain types had distinct NC properties and were differentially enriched with the presynaptic release protein Munc13-1. This organization into both shared and distinct subsynaptic nanodomains may underlie the ability of SAP102 and PSD-95 to perform both common and unique synaptic functions.
摘要：
MAGUK支架蛋白在维持和调节突触信号中起着核心作用，提供一个框架来保留和定位受体，信号分子，和其他突触成分。特别是,MAGUKsSAP102和PSD-95在不同的发育时间点对突触功能至关重要，并发挥重叠和独特的作用。虽然它们的相似结构允许共同的结合伴侣，SAP102在突触发育中早期表达，是突触发生所必需的，而PSD-95表达峰较晚，与突触成熟有关。PSD-95和其他关键突触蛋白组织成突触下纳米结构域，对突触传递有重大影响，但是SAP102的纳米级组织是未知的。SAP102是如何在突触中组织的，以及它在空间上与纳米尺度上的PSD-95的关系，可能是其独特功能的基础，并影响SAP102如何支架突触蛋白。在这里，我们使用DNA-PAINT超分辨率显微镜来测量SAP102纳米组织及其与PSD-95在混合性别大鼠培养神经元的单个突触处的空间关系。我们发现，像PSD-95一样，SAP102在高密度突触下纳米团簇中积累。然而,在整个开发过程中，SAP102纳米团簇比PSD-95纳米团簇更小，更致密。此外,仅SAP102纳米簇的子集与PSD-95共同组织，揭示了包含一种或两种蛋白质的单个突触内的MAGUK纳米结构域。这些MAGUK纳米结构域类型具有不同的纳米簇特性，并且差异富含突触前释放蛋白Munc13-1。这种组织成共享和不同的突触下纳米结构域可能是SAP102和PSD-95执行共同和独特突触功能的能力的基础。SAP102和PSD-95是突触支架蛋白的膜相关鸟苷酸激酶（MAGUK）家族的两个关键成员，对突触发育至关重要。维护,和可塑性。由于PSD-95具有影响突触功能的高度复杂的突触下纳米结构，我们询问SAP102是否类似地组织成纳米簇,以及它与PSD-95突触组织有什么关系.我们发现SAP102形成具有来自PSD-95的独特性质的突触下纳米簇。在单个突触中，这些蛋白质形成MAGUK特异性和重叠的纳米结构域，具有独特的特性，并与囊泡引发蛋白Munc13-1进行跨突触富集。因此，将突触蛋白组织成纳米簇可能维持在MAGUK家族中，并揭示了基于支架蛋白纳米结构域的单个突触中特定功能的潜在机制。
