The mechanistic basis and potential disease relevance of microtubule disorganisation in axons

轴突微管紊乱的机制基础和潜在疾病相关性

• 批准号: BB/P020151/1
• 负责人: Andreas Prokop
• 金额: $ 63.16万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FP020151%2F1
• 关键词: mechanistic; basis; potential; disease; relevance

Here we will study the properties of the microtubule (MT) cytoskeleton of neuronal axons to gain a better understanding of the important roles that MTs play during the formation, maintenance and degeneration of neurons. Axons are the slender, cable-like, up to several meter long protrusions of neurons which form the nerves that electrically wire our bodies. They can usually not be replaced, hence need to be maintained for up to a century in humans. Unsurprisingly, we gradually lose ~50% of our axons towards old age - and far more in neurodegenerative diseases (ND). In spite of their enormous importance, we know far too little about the mechanisms that maintain these delicate structures long-term or lead to their premature decay in neurodegeneration. Axon formation and maintenance essentially depends on the microtubule (MT) cytoskeleton. MTs consist of filamentous protein polymers arranged into 25nm thick tubules. In axons, MTs form continuous parallel bundles, serving as structural backbones and highways for life sustaining cargo/organelle transport. In ageing and ND, axons often form swellings where MT bundles become disorganised into criss-crossing curls, which trap organelles and are believed to trigger axonal loss. For the study of MT disorganisation, we developed the working model of axonal homeostasis based on our experimental data obtained in Drosophila neurons; this model involves three steps (details in CfS pt. 1): (1) MTs have to undergo constant polymerisation/depolymerisation to self-renew. (2) Each MT polymerisation event poses a risk of MT disorganisation, particularly in axons where high densities of MTs and molecular motors generate shear forces which can induce MT curling. (3) Order is imposed by a range of different mechanisms mediated by MT-binding proteins (e.g. by guiding MTs into parallel bundles, or eliminating MTs that have gone off-track). We propose that loss of single (or multiple) of these order-imposing mechanisms increases the risk of MT disorganisation leading to axon swellings - thereby providing potential explanations for late-onset axon degeneration linked genetically to various MT regulators. So far we have tested and refined this model primarily through experimental work in cultured fly and mouse neurons, by focusing on mechanisms regarding step 3 of our model (i.e. order-imposing MT regulators). Here we will focus on the mechanisms involved in step 2 (i.e. causing the curling of MTs), and compare our knowledge in cultured neurons to the situation in the nervous system in vivo. This work is important for several reasons: First, data obtained here will reveal the degree to which observations made in the highly efficient model of cultured neurons, reflect mechanisms underlying axon swellings in vivo. This will give important direction for experimental work aiming to unravel how axon swellings form and can be prevented. Second, we will generate important data concerning MT dynamics and their spatial arrangements in axons. These data will provide important information for the mathematical models of MT behaviours (see support letters) which we are developing in parallel projects - aiming to eventually perform long-term in silico experiments that can test pathological roles of MTs in late-onset neurodegeneration.Third, our data will provide important understanding, descriptions and concepts of axonal MTs that will aid worldwide research into axonal transport, organelle dynamics and MT regulation, thus promoting general advances in our understanding of axon biology during development, ageing, regeneration and degeneration.

在这里，我们将研究神经元轴突微管（MT）细胞骨架的特性，以更好地理解MTS在神经元的形成，维持和变性过程中扮演的重要作用。轴突是细长的电缆状的，最多几米长的神经元突出，形成电气电线的神经。通常无法替换它们，因此需要在人类中维持一个世纪的时间。毫不奇怪，我们逐渐损失了约50％的轴突，而在神经退行性疾病（ND）方面，我们的轴突却更多。尽管它们非常重要，但我们对长期保持这些微妙结构的机制知之甚少，或者导致神经退行性的过早衰变。轴突的形成和维护基本上取决于微管（MT）细胞骨架。 MT由排列成25nm厚小管中的丝状蛋白聚合物组成。在轴突中，MTS形成连续的平行束，用作结构骨架和维持货物/细胞器运输的寿命的高速公路。在衰老和ND中，轴突经常形成肿胀，其中MT束变成纵横交错的卷发，该卷发会捕获细胞器并被认为会触发轴突损失。为了研究MT混乱的研究，我们根据在果蝇神经元中获得的实验数据开发了轴突稳态的工作模型。该模型涉及三个步骤（CFSpt。1中的详细信息）：（1）MTS必须经过恒定的聚合/解聚化以自我更新。 （2）每个MT聚合事件都会构成MT混乱的风险，尤其是在高密度MT和分子电机产生剪切力的轴突中，可以诱导MT卷曲。 （3）通过MT结合蛋白介导的一系列不同机制（例如，通过将MT引导成平行束或消除已经偏离轨道的MT）来施加阶。我们提出，这些订单的单一（或多个）的丧失会增加MT混乱的风险，从而导致轴突肿胀，从而为遗传上与各种MT调节剂相关的后期发作轴突变性提供了潜在的解释。到目前为止，我们已经通过专注于有关我们模型的步骤3（即订购的MT调节剂）的机制，主要是通过培养的苍蝇和小鼠神经元中的实验性工作来测试和完善了该模型的。在这里，我们将重点介绍步骤2中涉及的机制（即导致MT卷曲），并将我们在培养的神经元中的知识与体内神经系统的情况进行比较。这项工作很重要，原因有几个：首先，此处获得的数据将揭示在培养神经元高效模型中的观察结果，反映了体内轴突肿胀的机制。这将为实验工作提供重要方向，以揭示轴突肿胀如何形成并可以预防。其次，我们将生成有关MT动力学及其空间排列的重要数据。 These data will provide important information for the mathematical models of MT behaviours (see support letters) which we are developing in parallel projects - aiming to eventually perform long-term in silico experiments that can test pathological roles of MTs in late-onset neurodegeneration.Third, our data will provide important understanding, descriptions and concepts of axonal MTs that will aid worldwide research into axonal transport, organelle dynamics and MT regulation, thus promoting在发展，衰老，再生和退化过程中，我们对轴突生物学的理解的总体发展。

项目成果

Tau, XMAP215/Msps and Eb1 co-operate interdependently to regulate microtubule polymerisation and bundle formation in axons.

• DOI: 10.1371/journal.pgen.1009647
• 发表时间: 2021-07
• 期刊: PLoS genetics
• 影响因子: 4.5
• 作者: Hahn I;Voelzmann A;Parkin J;Fülle JB;Slater PG;Lowery LA;Sanchez-Soriano N;Prokop A
• 通讯作者: Prokop A

ALFRED: Automated image analysis of microtubule networks in nerve cells

ALFRED：神经细胞微管网络的自动图像分析

• 发表时间: 2018
• 作者: Costa-Gomes, B

A new concept explaining axonal cell biology, ageing and pathology

解释轴突细胞生物学、衰老和病理学的新概念

• 发表时间: 2021
• 作者: Hahn I

The model of local axon homeostasis - explaining the role and regulation of microtubule bundles in axon maintenance and pathology

局部轴突稳态模型 - 解释微管束在轴突维持和病理学中的作用和调节

• DOI: 10.1101/577320
• 发表时间: 2019
• 作者: Hahn I

ALFRED: automated image analysis application to inform mathematical modelling of microtubule networks in nerve cells

ALFRED：自动图像分析应用程序，为神经细胞中微管网络的数学建模提供信息

• 发表时间: 2018
• 作者: Costa-Gomes, B.