Role of microRNAs and RISC in activity regulated translation in neurons

描述（由申请人提供）：许多神经系统和神经精神疾病，包括脆性X综合征、自闭症谱系障碍和药物成瘾，可能是由microRNA的调节改变引起的。微小RNA（microRNAs，miRs）是一类保守的非编码小RNA，与RNA诱导沉默复合体（RNA-induced silencing complex，RISC）共同参与转录后基因表达调控。microRNA被假设在控制神经元发育和突触可塑性的活性调节的mRNA翻译中起关键作用。我们最近的工作发现了一种新的神经递质调节蛋白质合成的分子机制，涉及从其靶mRNA中释放microRNA诱导的沉默复合物（miRISC）。该提案将研究这是否被用作microRNA调节神经元中活性介导的mRNA翻译的一般机制。我们将鉴定新的microRNA和靶mRNA，它们利用miRISC复合物的可逆性来调节活性介导的翻译。需要解决的一个关键问题是不同的神经递质信号通路如何差异化地影响microRNA/RISC靶向mRNA。最后，我们将评估脆性X智力低下蛋白（FMRP）磷酸化的作用，作为调节突触处microRNA子集的机制。这项研究有望揭示活性介导的基因表达的新分子机制，允许选择性，动态和时空控制。该提案将填补一个关键的差距，在我们的理解，通过表征一个统一的分子机制，允许活动调节和序列特异性mRNA翻译。目标1将使用候选分析和微阵列来检验神经递质受体信号改变相互作用的假设 microRNA/RISC复合物作为活性调节mRNA翻译的新机制。目的2将检验以下假设：在脆性X综合征的小鼠模型中，一个microRNA子集及其通过gp 1 mGlu信号传导调节的mRNA靶向失调。这项研究有可能鉴定出受神经元活性调节的新型microRNA，了解活性调节翻译的统一分子机制，并有助于在分子水平上阐明神经系统疾病的病理生理学。这项研究有望对理解RISC和miRNA如何动态控制基因表达的转录后调控以响应神经元活动以促进神经元功能产生广泛影响，这可能会在神经发育，神经精神疾病和药物成瘾中发生改变。这些研究被认为对未来的治疗策略具有重要意义，以操纵活性调节蛋白质合成治疗神经系统疾病和药物成瘾。

DESCRIPTION (provided by applicant): A number of neurological and neuropsychiatric disorders, including fragile x syndrome, autism spectrum disorders, and drug addiction, may result from altered regulation of microRNAs. MicroRNAs (miRs) are small, conserved, noncoding RNAs that act in association with the RNA-induced silencing complex (RISC) to regulate gene expression post-transcriptionally. MicroRNAs are hypothesized to play a critical role in activity-regulated mRNA translation that controls neuronal development and synaptic plasticity. Our recent work has discovered a novel molecular mechanism for neurotransmitter-regulated protein synthesis that involves the release of a microRNA induced silencing complex (miRISC) from its target mRNA. This proposal will investigate whether this is used as a general mechanism for microRNAs to modulate activity mediated mRNA translation in neurons. We will identify new microRNAs and target mRNAs that utilize reversibility of the miRISC complex to regulate activity-mediated translation. A key question to be addressed is how different neurotransmitter signaling pathways may differentially affect microRNA/RISC targeting to mRNAs. Lastly, we will assess a role for phosphorylation of the fragile x mental retardation protein, FMRP, as a mechanism to regulate a subset of microRNAs at synapses. This research is expected to uncover new molecular mechanisms for activity mediated gene expression that allows for selective, dynamic and spatiotemporal control. The proposal will fill a critical gap in our understanding by characterization of a unifying molecular mechanism allowing for activity- regulated and sequence specific mRNA translation. Aim 1 will use candidate analysis and microarrays to test the hypothesis that neurotransmitter receptor signaling alters the interactions of microRNA/RISC complexes from target mRNAs as a novel mechanism for activity-regulated mRNA translation. Aim 2 will test the hypothesis that a subset of microRNAs and their regulated targeting to mRNAs by gp1 mGlu signaling is dysregulated in a mouse model of fragile x syndrome. This research has the potential to identify novel microRNAs regulated by neuronal activity, understand a unifying molecular mechanism for activity-regulated translation and help to elucidate the pathophysiology of a neurological disorder at the molecular level. This research is expected to have a broad impact on understanding how the posttranscriptional regulation of gene expression is dynamically controlled by RISC and miRNAs in response to neuronal activity to promote neuronal function, which may be altered in neurodevelopmental, neuropsychiatric disorders and drug addiction. These studies are envisioned to have important implications for future therapeutic strategies to manipulate activity-regulated protein synthesis in the treatment of neurological disorders and drug addiction.