Localization of mRNAs at Synaptic Sites on Dendrites

树突突触位点 mRNA 的定位

• 批准号: 7371707
• 负责人: OSWALD STEWARD
• 金额: $ 32.23万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-06-01 至 2011-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7371707
• 关键词: Affect; Bacterial Proteins; Binding; Biological; Brain; Cell Nucleus; Chimeric Proteins; Chromosome Pairing; Cytoskeleton; DTR gene; Defect; Dendrites; Disruption; Docking; FMR1 Gene; Fragile X Mental Retardation Protein; Fragile X Syndrome; Functional RNA; Genes; Genetic Transcription; Green Fluorescent Proteins; Immediate-Early Genes; In Vitro; Information Storage; Localized; Long-Term Depression; Long-Term Potentiation; Mediating; Memory; Mental Retardation; Messenger RNA; MicroRNAs; Mitogen Activated Protein Kinase 1; Modification; Molecular; N-Methyl-D-Aspartate Receptors; Neurologic; Neurons; Pathway interactions; Phosphotransferases; Physiological; Preparation; Protein Biosynthesis; Proteins; RNA; Receptor Activation; Research; Role; Signal Transduction; Site; Synapses; Synaptic plasticity; Syndrome; Testing; Thinking; Transcript; Translational Regulation; Translations; base; dendrin; diphtheria toxin receptor; in vivo; insight; nervous system disorder; novel; postsynaptic; programs; research study; scaffold

DESCRIPTION (provided by applicant): The experiments of this proposal will define the mechanisms and functional role of mRNA localization and local translation at synaptic sites on neuronal dendrites. Local synthesis of critical proteins at synapses is necessary for long-lasting forms of synaptic plasticity including long-term potentiation (LTP) and long-term depression (LTD), and for the consolidation of memory. Recent studies indicate that the core neurological defect in a common neurological disorder Fragile X Mental Retardation Syndrome (FXS), may involve a disruption of protein synthesis at synapses due to the loss of Fragile X Mental Retardation Protein, the product of the Fmr1 gene which is defective in FXS. Thus, studies of mRNA transport, localization and translation may reveal new targets for therapy for this important and prevalent neurological disorder. Our previous studies have revealed aspects of the mechanisms underlying the selective targeting of mRNA to active synapses through studies of the unique immediate early gene (IEG) Arc, activity-regulated cytoskeleton-associated protein. Arc is strongly induced by physiological activity and its mRNA is rapidly delivered throughout dendrites based on a targeting signal in the mRNA sequence. Arc mRNA localizes selectively at active synapses, and mediates a local synthesis of Arc protein. Both the transcription of Arc mRNA in the nucleus, and the targeting of the newly synthesized transcript to active synapses are triggered by NMDA receptor activation of ERK1/2 and the MAP kinase pathway. Our studies have also revealed that other mRNAs are localized in different ways. The experiments of the present proposal will continue to identify and characterize mRNAs that are localized in dendrites, and further characterize the mechanisms underlying the docking of mRNAs at active synapses using in vivo and in vitro preparations. We will test the hypothesis that the docking mechanism involves a molecular scaffold beneath synapses or within the postsynaptic specialization that is modified by signals generated by intense synaptic activity. We will test the hypothesis that Arc mRNA contains sequences that determine that the mRNA will be transported into dendrites (a dendritic transport sequence) and sequence(s) that cause the mRNA to dock selectively at active synapses (a synaptic targeting sequence) by assessing targeting of exogenously expressed transcripts containing portions of Arc mRNA. Our previous studies indicate that other dendritic mRNAs do not re-localize to active synapses, and so we will determine whether these mRNAs are immobile in dendrites or instead lack the necessary targeting sequences. Together, our studies will reveal key features of the mechanism through which protein synthesis at synapses is regulated, thus providing insights into the fundamental mechanisms that underlie protein synthesis-dependent synaptic modifications, including the mechanisms that are disrupted in FXS and other neurological disorders that affect mRNA transport and localization. This research program will define biological mechanisms that make it possible for nerve cells to modify their connections with one-another (synapses) by controlling the synthesis of the protein building blocks of synapses at the synaptic contact site. These studies will provide novel insights into the basic mechanisms underlying information storage in the brain and neurological disorders that disrupt this fundamental mechanism, including Fragile-X Mental Retardation Syndrome.

描述（由申请人提供）：本提案的实验将定义神经元树突突触位点 mRNA 定位和局部翻译的机制和功能作用。突触关键蛋白质的局部合成对于持久形式的突触可塑性（包括长时程增强（LTP）和长期抑制（LTD））以及记忆的巩固是必要的。最近的研究表明，常见神经系统疾病脆性 X 型智力迟钝综合征 (FXS) 的核心神经缺陷可能涉及由于脆性 X 型智力迟钝蛋白（Fmr1 基因的产物）缺失而导致突触蛋白质合成中断。 FXS 有缺陷。因此，对 mRNA 运输、定位和翻译的研究可能会揭示治疗这种重要且普遍的神经系统疾病的新靶点。我们之前的研究通过对独特的即早期基因 (IEG) Arc（活性调节细胞骨架相关蛋白）的研究，揭示了 mRNA 选择性靶向活性突触的机制的各个方面。 Arc 受到生理活动的强烈诱导，其 mRNA 根据 mRNA 序列中的靶向信号快速传递到整个树突。 Arc mRNA 选择性地定位于活跃突触，并介导 Arc 蛋白的局部合成。 Arc mRNA 在细胞核中的转录以及新合成的转录物靶向活性突触都是由 NMDA 受体激活 ERK1/2 和 MAP 激酶途径触发的。我们的研究还表明其他 mRNA 以不同的方式定位。本提案的实验将继续鉴定和表征位于树突中的 mRNA，并使用体内和体外制剂进一步表征 mRNA 在活性突触处对接的机制。我们将测试这样的假设，即对接机制涉及突触下方或突触后特化内的分子支架，该分子支架被强烈突触活动产生的信号所修改。我们将通过评估靶向来测试 Arc mRNA 包含确定 mRNA 将被转运到树突的序列（树突转运序列）和导致 mRNA 选择性地停靠在活动突触上的序列（突触靶向序列）的假设。含有 Arc mRNA 部分的外源表达转录物。我们之前的研究表明其他树突 mRNA 不会重新定位到活跃的突触，因此我们将确定这些 mRNA 是否在树突中不动或缺乏必要的靶向序列。总之，我们的研究将揭示突触蛋白质合成调节机制的关键特征，从而深入了解蛋白质合成依赖性突触修饰的基本机制，包括 FXS 和其他影响影响的神经系统疾病中被破坏的机制。 mRNA 运输和定位。该研究计划将定义生物机制，使神经细胞能够通过控制突触接触部位蛋白质构建块的合成来改变它们彼此（突触）的连接。这些研究将为大脑信息存储的基本机制和破坏这一基本机制的神经系统疾病（包括脆性 X 智力迟钝综合症）提供新的见解。