Polarized Initiation of Varicosity Formation in Central Neuron Mechanosensation

项目总结 微机械应力在调节神经元形态和功能中的作用知之甚少 两极。机械撞击引起的弥漫性轴索损伤表现为特征性轴索静脉曲张(肿胀 或串珠)，这是创伤性脑损伤(TBI)的一个显著特征。大量的轴索静脉曲张 也是阿尔茨海默氏症和帕金森氏病不可逆神经变性的关键标志，以及多发性 硬化症。在生理条件下，可以在大脑中观察到较低水平的轴突静脉曲张。 尽管轴突静脉曲张深刻地影响动作电位的传播和突触传递，但它们是如何 由机械压力在轴突中特异性地诱导，并在健康和疾病中受到调控仍然是一个谜。 我们的初步研究已经导致了几个新的发现来阐明这个重要的问题。我们发现 机械应力可在无髓轴突中诱导静脉曲张的形成，但在树突或有髓轴突中不能。 中枢神经元的轴突。这一过程出人意料地迅速和可逆，其中一个瞬时受体 电位(Trp)通道是主要的机械敏感(MS)离子通道。我们进一步确定了一部小说 这个通道的结合蛋白，它调节微管(MT)的分解，以响应钙离子内流。 此外，我们还观察到轻度脑外伤小鼠模型脑内轴索静脉曲张的快速发展。 基于我们的初步结果，我们提出了一个原始的假设，即微机械应力 优先诱导中枢神经元的轴突静脉曲张，这一过程由轴突调节 内在机制和外在机制。为了检验这一假设，我们将使用多学科方法。 包括新的微生物力学分析、蛋白质生物化学、电生理记录、最新进展 ART成像、髓鞘共培养、基因敲除小鼠和轻度脑外伤小鼠模型。我们将确定(目标1)是否 MS离子通道的靶向和活性调节中枢神经元的极化机械感觉(目标2) MT的解体是由轴突内钙离子增加引起的，进而导致静脉曲张的形成，(目标3) 轻度脑外伤小鼠模型中轴索静脉曲张的形成模式是否受髓鞘、MS 通道及其结合蛋白。 这个项目代表了一个未被探索的研究领域，有许多有待解决的问题。这项研究具有重要的意义 因为它将为一种新形式的中枢神经元极化提供新的机制洞察力 机械感应。

PROJECT SUMMARY Little is known about the role of micromechanical stress in regulating neuronal morphological and functional polarity. Diffuse axonal injury caused by mechanical impact displays characteristic axonal varicosities (swelling or beading), which are a prominent feature of traumatic brain injury (TBI). Abundant axonal varicosities are also a key sign for irreversible neurodegeneration in Alzheimer's and Parkinson's diseases, and multiple sclerosis. Under physiological conditions, a lower level of axonal varicosities can be observed in the brain. Although axonal varicosities profoundly affect action potential propagation and synaptic transmission, how they are specifically induced in axons by mechanical stress and regulated in health and disease remains a mystery. Our preliminary studies have led to several novel findings to shed light on this important question. We found that mechanical stress induces varicosity formation in unmyelinated axons, but not in dendrites or myelinated axons of central neurons. This process is unexpectedly rapid and reversible, where a transient receptor potential (TRP) channel acts as the major mechanosensitive (MS) ion channel. We further identified a novel binding protein of this channel, which regulates microtubule (MT) disassembly in response to Ca2+ influx. Moreover, we observed the rapid development of axonal varicosities in the brain of a mouse model of mild TBI. Based on our preliminary results, we propose an original hypothesis that micromechanical stress preferentially induces axonal varicosities in central neurons, and this process is regulated by axonal intrinsic and extrinsic mechanisms. To test this hypothesis, we will use a multidisciplinary approach including novel microbiomechanical assays, protein biochemistry, electrophysiological recording, state-of-the- art imaging, myelin coculture, knockout mice and a mild TBI mouse model. We will determine (Aim 1) whether targeting and activity of MS ion channels regulate polarized mechanosensation in central neurons, (Aim 2) how MT disassembly is induced by intra-axonal Ca2+ increase and in turn leads to varicosity formation, and (Aim 3) whether the pattern of axonal varicosity formation in the mild TBI mouse model is regulated by myelin, the MS channel and its binding protein. This project represents an underexplored research field with many open questions. This research is significant because it will provide novel mechanistic insights into a new form of central neuron polarity, polarized mechanosensation.