Mechanisms of Translation in the CNS

描述(由申请人提供)：这项建议的广泛目标是描述哺乳动物神经元，特别是树突中改变突触有效性的mRNA翻译机制。CPEB是一种序列特异性的mRNA结合蛋白，可促进胞浆多聚腺苷诱导的翻译，存在于哺乳动物神经元的突触树突中。CPEB基因敲除小鼠在突触可塑性和学习记忆方面表现出缺陷，表明细胞质聚腺苷酸化机制在复杂的脑功能中的重要性。CPEB在mRNA上核化一系列促进聚腺苷酸化的因子，包括非规范的聚(A)聚合酶Gld2、死烯基化酶Parn、eIF4E结合蛋白NeuroGuidin(NGD)、支架蛋白symplekin等。这些蛋白质存在于哺乳动物神经元树突中的一个复合体中，在那里它们调节几个mRNAs的多聚腺苷化和翻译。其中两个因子，Gld2和NGD，调节海马神经元的突触可塑性，但方向相反；Gld2缺失导致长时程增强(LTP)不足，而NGD缺失增强它。此外，Gld2的缺失减少了树突的翻译，而NGD的缺失刺激了树突的翻译。这些数据表明，CPEB、Gld2和NGD之间的相互作用形成了树突中翻译控制的一致的分子基础，进而调节突触的功效。第一个特定目标的目标是确定可能改变聚(A)长度和翻译变化的去烯化酶，以及评估它们是否影响突触功能。目的2是研究大脑中CPEB结合的全套mRNAs，并确定它们是否在树突中经历活性依赖的多聚腺苷酸化和翻译。目标3的目标是开发和使用一种新的深度测序方法来鉴定在体外LTP诱导和体内学习过程中经历细胞质多聚腺苷基化和翻译的树突状mRNAs。这些实验将增强我们对神经元中局部mRNA翻译如何介导突触功能的理解，这对更高的大脑功能和神经疾病，如自闭症、阿尔茨海默病、帕金森病等具有重要意义。

DESCRIPTION (provided by applicant): The broad objective of this proposal is to delineate mechanisms of mRNA translation in mammalian neurons and especially dendrites that modify synaptic efficacy. CPEB, a sequence-specific mRNA binding protein that promotes cytoplasmic polyadenylation- induced translation, is present at synapto-dendrites of mammalian neurons. CPEB knockout mice display defects in synaptic plasticity and learning and memory, indicating the importance of the cytoplasmic polyadenylation machinery in complex brain function. CPEB nucleates a set of factors on mRNA to promote polyadenylation including the non- canonical poly(A) polymerase Gld2, the deadenylating enzyme PARN, the eIF4E-binding protein neuroguidin (Ngd), the scaffold protein symplekin, and others. These proteins reside in a complex in dendrites of mammalian neurons where they modulate the polyadenylation and translation of several mRNAs. Two of these factors, Gld2 and Ngd, regulate synaptic plasticity in hippocampal neurons but do so in opposite directions; Gld2 depletion induces a deficit in long-term potentiation (LTP) while Ngd depletion enhances it. Moreover, Gld2 depletion reduces translation in dendrites while Ngd depletion stimulates it. These data indicate that the interplay among CPEB, Gld2, and Ngd form a coherent molecular foundation of translation control in dendrites that in turn modulates synaptic efficacy. The goals of the first specific aim are to identify deadenylating enzymes that are likely to modify poly(A) length and changes in translation as well as to assess whether they influence synaptic function. Aim 2 is to investigate the full panoply of mRNAs that are bound by CPEB in the brain and determine whether they undergo activity-dependent polyadenylation and translation in dendrites. The goal of aim 3 is to develop and use a new deep sequencing method to identify dendritic mRNAs that undergo cytoplasmic polyadenylation and translation in response to in LTP induction in vitro and learning in vivo. These experiments will enhance our understanding of how local mRNA translation in neurons mediates synapse function, which has important implications for higher brain function and neuropathies such as autism, Alzheimer's Disease, Parkinson's Disease, and others.