Role of microRNAs and RISC in activity regulated translation in neurons

描述（由申请人提供）：许多神经和神经精神疾病，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调节改变引起的。MicroRNAs （miRs）是一种小的、保守的非编码rna，与rna诱导沉默复合体（RISC）联合作用，在转录后调节基因表达。据推测，MicroRNAs在控制神经元发育和突触可塑性的活性调控mRNA翻译中起着关键作用。我们最近的工作发现了一种新的神经递质调节蛋白合成的分子机制，该机制涉及从其靶mRNA释放microRNA诱导的沉默复合物（miRISC）。本提案将研究这是否被用作microrna调节神经元活性介导的mRNA翻译的一般机制。我们将鉴定新的microrna和靶向mrna，利用miRISC复合体的可逆性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不同地影响microRNA/RISC靶向mrna。最后，我们将评估脆性x智力迟钝蛋白（FMRP）的磷酸化作为调节突触中一小部分microrna的机制的作用。这项研究有望揭示活性介导的基因表达的新分子机制，从而实现选择性、动态和时空控制。该建议将填补我们理解的一个关键空白，通过表征一个统一的分子机制，允许活性调节和序列特异性mRNA翻译。目的1将使用候选分析和微阵列来测试神经递质受体信号改变相互作用的假设

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.