Local mRNA degradation in GluR1 signaling, synaptic plasticity, and cognitive function

项目摘要 突触功能的主要调节器是局部蛋白质合成。深度RNA测序显示， 是数以千计的树突状定位的mRNA。树突中选择的mRNA的局部翻译提供了一个 快速，适应机制的经验依赖性形成新的突触或稳定的前， 现有的连接。这种可塑性是神经网络动力学变化的基础，因此被认为是 是学习和记忆的基础。改变的蛋白质合成和突触可塑性是相关的 患有多种神经发育障碍然而，调节树突蛋白质组的途径 并没有得到很好的理解。 树突中的蛋白质合成需要精确调节局部mRNA的稳定性和翻译。一个伟大 大量的先前研究已经解决了调节树突中的翻译去阻遏的途径。 然而，在突触功能期间控制mRNA水平的机制尚未得到证实。我们 最近已经表明，轴突内翻译耦合到mRNA降解途径“无意义”， 介导的mRNA衰变（NMD）控制受体表达的转换，从而调节轴突导向; 表明mRNA周转是局部蛋白质合成的关键因素。目前，尚不清楚是否 树突中mRNA的稳定性有助于突触可塑性的调节。 本申请的目的是了解树突内翻译与mRNA偶联的作用， NMD降解途径对突触可塑性和认知性能的影响。突触可塑性蛋白Arc 是NMD介导的mRNA降解的已知靶标，用于限制树突中Arc的量。我们 我发现，除了Arc，NMD限制了GluR 1中涉及的各种其他蛋白质的量 调节，这对于调节突触强度是必不可少的。根据已发表的文献和我们的 初步研究中，我们假设局部NMD对于突触功能和轴突一样重要 指导为了验证这一假设，我们建议确定是否NMD：1）局部功能在树突; 2） 通过限制GluR 1的内化或翻译抑制来促进突触强度; 3）发挥 在不同形式的突触可塑性（如LTP和LTD）中发挥作用; 4）是学习和记忆所必需的。我们将 使用多种技术的组合，包括新颖的微流体装置来独特地研究突触事件， 诱导遗传小鼠模型、电生理学和行为测定。虽然NMD是唯一的RNA 调节途径与许多神经认知障碍，它代表了一个相对未开发的 调节突触功能的机制。这项研究的成功完成将提供一个连贯的 局部蛋白质组动态突触可塑性的观点，可能是有价值的，为提供新的见解， 突触功能障碍和神经认知疾病的机制。

PROJECT SUMMARY A major regulator of synaptic function is local protein synthesis. Deep RNA sequencing has revealed that there are thousands of dendritically localized mRNAs. Local translation of selected mRNAs in dendrites provides a fast, adaptive mechanism for the experience-dependent formation of new synapses or the stability of pre- existing connections. This plasticity underlies changes in neuronal network dynamics and is therefore thought to be the foundation of learning and memory. Altered protein synthesis and synaptic plasticity are associated with a variety of neurodevelopmental disorders. However, the pathways that regulate the dendritic proteome are not well understood. Protein synthesis in dendrites requires precise regulation of local mRNA stability and translation. A great amount of prior research has addressed the pathways that regulate translational derepression in dendrites. However, the mechanisms that control mRNA levels during synaptic function have not been demonstrated. We have recently shown that intra-axonal translation coupled to the mRNA-degradation pathway `Nonsense Mediated mRNA Decay' (NMD) controls a switch in receptor expression and thereby regulates axon guidance; indicating that mRNA turnover is a key player in local protein synthesis. Currently, it is not known whether mRNA stability in dendrites contribute to the regulation of synaptic plasticity. The goal of this application is to understand the contribution of intra-dendritic translation coupled to mRNA- degradation pathway NMD to synaptic plasticity and cognitive performance. The synaptic plasticity protein Arc is a known target of NMD-mediated mRNA degradation, serving to limit the amount of Arc in dendrites. We have found that, in addition to Arc, NMD limits the amount of various other proteins involved in GluR1 regulation, which is essential for modulation of synaptic strength. Based on the published literature and our preliminary studies, we hypothesize that local NMD is as essential for synaptic function as it is for axon guidance. To test this hypothesis, we propose to determine whether NMD: 1) locally functions in dendrites; 2) promotes synaptic strength by restricting either internalization or translational repression of GluR1; 3) plays a role in different forms of synaptic plasticity (e.g. LTP and LTD); 4) is required for learning and memory. We will use a combination of techniques including a novel microfluidic device to uniquely study synaptic events, an inducible-genetic mouse model, electrophysiology and behavioral assays. Although NMD is the only RNA regulatory pathway linked to numerous neurocognitive disorders, it represents a relatively unexplored mechanism for regulating synaptic function. The successful completion of this research will provide a coherent view of local proteome dynamics in synaptic plasticity and might be valuable for providing new insights into the mechanisms of synaptic dysfunction and neurocognitive diseases.