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

描述（由申请人提供）：突触可塑性描述了神经元经验对突触连接的特定改变，被广泛认为是记忆的细胞基础。大量研究表明，新生蛋白合成对于稳定长期增强（LTP）和长期抑制（LTD）等突触可塑性的持久形式至关重要。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。更常见和研究更充分的模式是典型翻译或帽依赖翻译，当翻译起始因子的多蛋白复合物结合真核mrna的5'帽时启动。蛋白质合成也可以通过非规范途径发生，该途径通过mRNA内核糖体进入位点（IRES）的一组不同因子启动翻译。我们对这种非规范通路在神经元正常生理活动中的作用知之甚少。然而，我们实验室之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。本研究的目的是了解非规范翻译如何参与海马中代谢性谷氨酸受体（mGluR）介导的蛋白质合成依赖形式的LTD。我将使用靶向病毒和药理学操作结合报告活性分析、图像分析和蛋白质组学来验证非规范翻译被积极利用来支持海马体中的mGluR-LTD的中心假设。具体目的是表征在海马mGluR-LTD之后，非规范翻译是如何在时间和空间上受到调节的。这项工作是重要的，因为它通过提供对非规范翻译机制的洞察，解决了我们对突触可塑性期间蛋白质合成的活性依赖调节的知识的主要空白。更好地理解突触可塑性背后的神经生物学事件

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.