Wrd-specific PP2A substrates that regulate AZ stability

 描述(由申请人提供)：调节AZ稳定性的WRD特异性PP2A底物项目摘要/摘要神经元通讯依赖于轴突终末称为活动区(AZs)的特殊膜室中神经递质的精确协调释放。了解AZ在发育过程中是如何组装和稳定的，以及活动驱动的结构可塑性是理解健康大脑中神经电路是如何建立和修改的，以及突触形成功能障碍如何导致自闭症等神经发育障碍的发病机制的关键。AZ细胞骨架上的一组进化保守的突触前支架蛋白被认为是AZ组装的组织者，然而，确切的分子机制仍然是个谜。我们最近发现，两个主要的AZ组织者，Syd-1和Liprin-α，通过AZ定位的PP2A B‘调节亚单位圆整的线性通路调节特定的PP2A活性，以稳定AZ物质和神经末梢的突触小泡，并且这一途径拮抗GSK-3的β活性，防止突触物质在远端轴突区域异位聚集。基于这些发现，我们假设Syd-1和Liprin-α控制神经末梢PP2A/WRd介导的去磷酸化事件，从而拮抗GSK-3β介导的磷酸化事件，从而稳定神经末梢的AZs。我们的初步数据表明，Futsch是一种微管相关蛋白，是WRD和GSK-3β的潜在底物。我们将验证Syd-1/Liprin-α/WRd磷酸酶通路和GSK-3β激酶通路靶向Futsch以平衡AZ在神经末梢(AIM1)滞留的假设。我们还将对Syd-1-Liprin-α-PP2A/WRd和GSK-3β的下游底物进行无偏倚的蛋白质组筛选，并测试它们的磷酸化和去磷酸化是否能够动态调节AZ的稳定性(AIM2)。

 DESCRIPTION (provided by applicant): Wrd-specific PP2A substrates that regulate AZ stability Project Summary / Abstract Neuronal communication depends on the precisely orchestrated release of neurotransmitters at specialized membrane compartments at the axonal terminal called active zones (AZs). Understanding how AZs are assembled and stabilized during development and activity-driven structural plasticity is key to understanding how neural circuitries are established and modified in healthy brains, and how dysfunction in synaptic formation contributes to pathogenesis of neurodevelopment disorders such as autism. A group of evolutionarily conserved presynaptic scaffolding proteins at the cytomatrix of AZ are thought to organize AZ assembly, however, the precise molecular mechanisms remain enigmatic. We recently showed that two master AZ organizers, Syd-1 and Liprin-α, regulate a specific PP2A activity through a AZ-localized PP2A B' regulatory subunit Well-rounded (Wrd) in a linear pathway to stabilize AZ materials and synaptic vesicles at the nerve terminal, and that this pathway antagonizes GSK-3β activity to prevent ectopic accumulation of synaptic materials at the distal axon region. Based on these findings, we hypothesize that Syd-1 and Liprin-α control PP2A/Wrd-mediated dephosphorylation events at the nerve terminal, which antagonize GSK-3β-mediated phosphorylation events to stabilize AZs at nerve terminal. Our preliminary data suggest that Futsch, a microtubule associated protein, is a potential substrate of both Wrd and GSK-3β. We will test the hypothesis that the syd-1/liprin-α/wrd phosphatase pathway and GSK-3β kinase pathway target Futsch to balance AZ retention at the nerve terminal (Aim1). We will also perform unbiased proteomic screens for downstream substrates of Syd-1-Liprin-α-PP2A/Wrd and GSK-3β, and test whether their phosphorylation and dephosphorylation can dynamically regulate AZ stability (Aim2).