Nascent protein degradation-based fast homeostatic mechanism mediated by neuronal membrane proteasomes

神经元膜蛋白酶体介导的基于新生蛋白降解的快速稳态机制

• 批准号: 10717075
• 负责人: Haiyan He
• 金额: $ 38.69万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2028-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10717075
• 关键词: Amino Acids; Animal Behavior; Behavior; Behavioral; Biochemical; Brain; Cells; Data; Development; Disease; Equilibrium; Etiology; Feedback; Functional Imaging; Functional disorder; Future; Health; Hippocampus; Homeostasis; Human; Hypothetical Protein; Image; Imaging Techniques; Investigation; Label; Learning; Link; Maps; Mediating; Membrane; Memory; Methods; Microscopy; Molecular; Molecular Genetics; Nature; Neurodegenerative Disorders; Neurons; Neurophysiology - biologic function; Pathway interactions; Pattern; Physiological; Play; Process; Protein Biosynthesis; Proteins; Proteome; Regimen; Regulation; Role; Sensory; Synapses; Synaptic plasticity; System; Tadpoles; Tectum Mesencephali; Testing; Time; Visual; Visual System; Xenopus laevis; avoidance behavior; behavioral plasticity; cell type; cognitive function; experience; experimental study; functional plasticity; imaging genetics; improved; in vivo; innovation; multicatalytic endopeptidase complex; neural circuit; novel; prevent; protein degradation; proteostasis; recruit; response; spatiotemporal; structural imaging; superior colliculus Corpora quadrigemina; temporal measurement; tool; visual motor

Project Summary/Abstract Activity-dependent associative Hebbian plasticity, is recognized as a core mechanism underlying learning and memory, cognitive function, and brain development. Hebbian plasticity is intrinsically unstable due to its positive feedback nature, and has to be balanced by homeostatic mechanisms, which maintain the stability of overall neuronal activity. A major gap in the field concerns the incomplete understanding of cellular pathways by which neurons maintain homeostasis and how these mechanisms interact with Hebbian plasticity, especially on fast time scales. Our preliminary data suggest that a recently discovered neuronal membrane proteasome (NMP) may be involved in the fast homeostatic mechanism in vivo. NMPs are expressed in the tadpole brain and degrade nascent proteins in vivo. Inhibition of NMP activity led to a rapid increase in spontaneous neuronal activity and abolished learning-induced behavioral improvement in a visuomotor behavior paradigm. Activity-induced de novo synthesis of proteins that are important for the expression of downstream plasticity mechanisms is a hallmark of Hebbian plasticity. We hypothesize that NMP-mediated degradation of activity-induced nascent proteins serves as a negative feedback mechanism for fast homeostatic regulation of neuronal activity in response to plasticity-inducing activities. We will test this hypothesis in a well-established visually driven experience-dependent plasticity paradigm in Xenopus laevis tadpoles, which allows the combination of biochemical, physiological, molecular genetics, and behavioral experiments in an intact neural circuit with physiologically relevant sensory stimulation. Most critically, this experimental system provides the fast temporal resolution that is pivotal for the investigation of the rapid degradation of nascent proteins by NMPs in vivo. Specifically, in Aim 1, we will use in vivo BONCAT labeling to characterize the proteolytic activity of NMPs under different activity regimens and use expansion microscopy to delineate the spatiotemporal expression profile of NMPs in the optic tectum over development. In Aim 2, we will combine in vivo Ca++ imaging with molecular genetic tools to examine how NMPs regulate spontaneous and visually-evoked activity in tectal neurons, and determine whether NMP-mediated regulation of neuronal activity is cell-autonomous. In Aim3, we will use time-lapse structural and functional imaging and the visual avoidance behavior to assess the functional role of NMPs in experience-dependent plasticity at both cellular and circuit levels in the visual system. The proposed experiments will generate data for in-depth understanding of the NMP function in vivo. These results will shed light on a novel proteostasis-based fast homeostatic mechanism and lay the groundwork for future studies to further elucidate downstream cellular and molecular pathways underlying the functional interplay between activity-dependent proteostasis of nascent proteins and experience- dependent plasticity mechanisms.

项目概要/摘要 活动依赖的联想赫布可塑性被认为是学习和学习的核心机制 记忆、认知功能和大脑发育。赫布塑性本质上是不稳定的，因为它 正反馈性质，并且必须通过稳态机制来平衡，从而维持稳定性 整体神经元活动。该领域的一个主要差距涉及对细胞通路的不完全理解 神经元通过哪些机制维持稳态以及这些机制如何与赫布可塑性相互作用， 尤其是在快速时间尺度上。我们的初步数据表明，最近发现的神经元膜 蛋白酶体（NMP）可能参与体内快速稳态机制。 NMP 的表达形式为 蝌蚪大脑并降解体内新生蛋白质。 NMP活性的抑制导致NMP活性快速增加 自发神经元活动和废除学习诱导的视觉运动行为改善 行为范式。活性诱导的蛋白质从头合成对于表达很重要 下游可塑性机制是赫布可塑性的一个标志。我们假设 NMP 介导 活性诱导的新生蛋白的降解作为快速的负反馈机制 响应可塑性诱导活动的神经元活动的稳态调节。我们将测试这个 非洲爪蟾成熟的视觉驱动的依赖于经验的可塑性范式的假设 蝌蚪，它允许生物化学、生理学、分子遗传学和行为学的结合 在完整的神经回路中进行具有生理相关感觉刺激的实验。最关键的是，这 实验系统提供了快速的时间分辨率，这对于快速研究至关重要 NMPs 在体内降解新生蛋白。具体来说，在目标 1 中，我们将使用体内 BONCAT 标记 表征不同活性方案下 NMP 的蛋白水解活性并扩展用途 显微镜描绘视顶盖发育过程中 NMP 的时空表达谱。 在目标 2 中，我们将结合体内 Ca++ 成像与分子遗传学工具来研究 NMPs 如何调节 顶盖神经元的自发和视觉诱发活动，并确定 NMP 介导的调节是否 神经元活动是细胞自主的。在 Aim3 中，我们将使用延时结构和功能成像 视觉回避行为来评估 NMP 在经验依赖性可塑性中的功能作用 视觉系统中的细胞和电路水平。拟议的实验将生成深入的数据 了解NMP在体内的功能。这些结果将揭示一种新型的基于蛋白质稳态的禁食 稳态机制，为未来的研究奠定基础，进一步阐明下游细胞和 新生细胞活性依赖性蛋白质稳态之间功能相互作用的分子途径 蛋白质和经验依赖性可塑性机制。