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）：该提案的实验将定义mRNA定位和在神经元树突上突触部位上的机制和功能作用。突触处关键蛋白质的局部合成对于长期增强（LTP）和长期抑郁（LTD）以及记忆的巩固（包括长期增强）（LTP）和长期抑郁（LTD）是必不可少的。最近的研究表明，常见神经系统疾病中的核心神经系统缺陷脆弱的X智力迟缓综合征（FXS）可能涉及由于FXS中有缺陷的FMR1基因的产物而导致脆弱的X智力障碍蛋白的损失而导致突触时蛋白质合成的破坏。因此，对mRNA转运，定位和翻译的研究可能揭示了这种重要和普遍的神经系统疾病的新靶标。我们以前的研究揭示了通过研究独特的早期基因（IEG）ARC，活性调节的细胞骨架相关蛋白的独特的早期基因（IEG）ARC，将mRNA选择性靶向主动突触的机制。 ARC是由生理活性强烈诱导的，其mRNA基于mRNA序列中的靶向信号迅速传递。 ARC mRNA选择性定位于活性突触，并介导弧蛋白的局部合成。 NMDA受体激活ERK1/2和MAP激酶途径触发了核中电弧mRNA的转录以及新合成的转录物对活性突触的靶向。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识别和表征在树突中定位的mRNA，并进一步表征使用体内和体外制剂在活动突触处mRNA对接的机制。我们将检验以下假设：对接机制涉及突触下的分子支架或突触后专业化中的分子支架，该化合物是由强烈的突触活动所产生的信号所修饰的。我们将检验以下假设：ARC mRNA包含序列，这些序列确定mRNA将被转运到树突（树枝状转运序列）和序列中，这些序列通过评估包含ARC mRNA的外源表达的转录部分，使MRNA在主动突触（突触靶向序列）下选择性地对接，这些序列会导致mRNA选择性地对接。我们先前的研究表明，其他树突状mRNA不会重新定位到主动突触，因此我们将确定这些mRNA是否在树突中不动，还是缺乏必要的靶向序列。总之，我们的研究将揭示通过调节突触处蛋白质合成的机制的关键特征，从而提供洞察力，以了解基于蛋白质合成依赖的突触修饰的基本机制，包括在FXS和其他影响MRNA运输和本地化的神经疾病中破坏的机制。该研究计划将定义生物学机制，从而使神经细胞通过控制突触接触位点突触的蛋白质构建块的合成来改变其与另一种（突触）的连接。这些研究将提供有关大脑中信息存储基本机制和神经系统疾病中的基本机制的新见解，这些机制破坏了这种基本机制，包括脆弱的X心理障碍综合征。