Non-canonical translation in hippocampal mGluR-dependent long-term depression - R

描述（由申请人提供）：突触可塑性描述了响应于神经元体验的突触连接的特定修饰，并且被广泛认为是记忆的细胞基质。大量研究表明，从头蛋白质合成对于稳定突触可塑性的持久形式如长时程增强（LTP）和长时程抑制（LTD）是必不可少的。然而，神经元中有两种翻译模式可以促进这些过程背后的蛋白质合成。更常见且研究充分的模式是典型或帽依赖性翻译，其在翻译起始因子的多蛋白复合物结合真核mRNA的5'帽时起始。蛋白质合成也可以通过非经典途径发生，所述非经典途径用来自mRNA中的内部核糖体进入位点（IRES）的不同因子集合启动翻译。关于这种非经典途径在神经元正常生理活动中的作用知之甚少。然而，我们实验室以前的工作和新的初步数据表明，这种翻译途径可能在突触可塑性的持久形式中发挥作用。拟议研究的目标是了解非规范翻译如何具体参与海马中代谢型谷氨酸受体（mGluR）介导的蛋白质合成依赖性LTD形式。我将使用有针对性的病毒和药理学操作与报告活性测定，图像分析和蛋白质组学的组合，以测试中心的假设，即非典型的翻译是积极利用，以支持mGluR-LTD在海马。具体的目的是表征如何非规范翻译的时间和空间调节海马mGluR-LTD。这项工作是重要的，因为它解决了一个主要的差距，我们的知识活动依赖性调节蛋白质合成过程中突触可塑性提供洞察非规范机制的翻译。更好地理解突触可塑性背后的神经生物学事件 将可能有助于开发新的药物或策略来改善记忆功能或削弱记忆，这具有重要的临床意义。

DESCRIPTION (provided by applicant): Synaptic plasticity describes the specific modification of synaptic connections in response to neuronal experience and is widely held as a cellular substrate of memory. Numerous studies have demonstrated that de novo protein synthesis is essential for stabilizing persistent forms of synaptic plasticity such as long-term potentiation (LTP) and long-term depression (LTD). However, there are two modes of translation in neurons that can contribute to the protein synthesis underlying these processes. The more common and well-studied mode is canonical or cap-dependent translation, which initiates when a multi-protein complex of translation initiation factors bind the 5' cap of eukaryotic mRNAs. Protein synthesis can also occur through a non- canonical pathway that initiates translation with a different set of factors from an internal ribosome entry site (IRES) in the mRNA. Very little is known about the role of this non-canonical pathway during normal physiological activity in neurons. However, previous work and new preliminary data from our lab suggests that this translation pathway may play a role in persistent forms of synaptic plasticity. The goal of the proposed research is to understand how non-canonical translation is involved specifically in a protein synthesis- dependent form of LTD mediated by metabotropic glutamate receptors (mGluR) in the hippocampus. I will use a combination of targeted viral and pharmacological manipulations with reporter activity assays, image analysis and proteomics to test the central hypothesis that non-canonical translation is actively utilized to support mGluR-LTD in the hippocampus. The specific aim is to characterize how non-canonical translation is temporally and spatially regulated following hippocampal mGluR-LTD. This work is significant because it addresses a major gap in our knowledge about activity-dependent regulation of protein synthesis during synaptic plasticity by providing insight into non-canonical mechanisms of translation. A better understanding of the neurobiological events that underlie synaptic plasticity will likely aid the development of new agents or strategies for improving memory function or weakening memories, which has important clinical implications.