Coupled axonal protein synthesis and lipidation in axon growth and homeostasis

轴突在生长过程中不断对环境中的外部信号做出反应， 在发育过程中向靶组织导航，并进行维护和修复 在成年生活中。mRNA定位和局部蛋白质合成是一种保守的机制， 允许对外部营养和指导线索做出快速和轴突自主反应。 尽管对轴突蛋白合成功能的认识越来越多，但轴突蛋白合成中的一个主要空白是， 我们的知识是了解新生蛋白质如何进一步加工， 定位在轴突中以产生功能齐全的蛋白质。我们的初步结果表明 神经营养因子（神经生长因子）能剧烈调节局部蛋白质合成 以及轴突中新产生的蛋白质的脂化（异戊烯化）。已经假设 蛋白质异戊烯化是在整个细胞质中发生的组成性机制， 是允许细胞功能的。与此形成鲜明对比的是，我们发现，在神经元中， 是在外部信号的精确时空控制下。这个应用程序的目标是 是为了确定是否耦合轴突蛋白合成和异戊二烯化作为一个 调节机制，以定位和丰富轴突隔室中的蛋白质， 动态和空间反应的外在生长促进线索。我们将使用一个 结合成像、生化和功能分析， 神经元培养物以及小鼠体内分析来实现这一目标。这些 研究将推进神经元信号传导的空间模式的知识， 轴突发育、维持和再生。

Axons continuously respond to external signals in their environment as they grow and navigate toward their target tissues during development, and for maintenance and repair in adult life. mRNA localization and local protein synthesis is a conserved mechanism that allows for rapid and axon-autonomous responses to external trophic and guidance cues. Despite growing appreciation for the functions of axonal protein synthesis, a major gap in our knowledge is in understanding how the nascent proteins are further processed and localized in axons to generate fully functional proteins. Our preliminary results suggest that a neurotrophic factor (Nerve Growth Factor) acutely regulates local protein synthesis and lipidation (prenylation) of newly-made proteins in axons. It has been assumed that protein prenylation is a constitutive mechanism that occurs throughout the cytoplasm and is permissive for cellular functions. In striking contrast, we find that, in neurons, prenylation is under exquisite spatio-temporal control by extrinsic signals. The goal of this application is to define whether coupled axonal protein synthesis and prenylation serves as a regulatory mechanism to localize and enrich proteins in axonal compartments to ensure dynamic and spatial responses to extrinsic growth-promoting cues. We will use a combination of imaging, biochemical, and functional analyses in compartmentalized neuronal cultures, as well as in vivo analyses in mice to accomplish this goal. These studies will advance the knowledge of spatial modes of signaling in neurons that underlie axon development, maintenance, and regeneration.