Understanding essential roles of microtubule regulators during synapse formation and maintenance

了解微管调节器在突触形成和维持过程中的重要作用

• 批准号: BB/M007456/1
• 负责人: Natalia Sanchez-Soriano
• 金额: $ 52.2万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FM007456%2F1
• 关键词: Understanding; essential; roles; microtubule; regulators

A key prerequisite for nervous system function is the capability of neurons to communicate with other cells via specialised cell junctions called synapses. Synapses contain complex machinery for rapid transmission of signals to partner cells. Once formed, synapses have to be maintained in a plastic state, and precocious loss of synapses is considered a potential cause of neuronal decay in ageing and in neurodegenerative diseases. However, in spite of this importance, the mechanisms underlying synaptic maintenance are very little understood. The overarching aim of this project is to deliver such understanding, thus bridging an important gap in our knowledge about processes of ageing and degeneration in the brain.During a neuron's life, its synaptic machinery is constantly recycled. To this end, its building blocks have to be efficiently transported between the neuronal cell body and the very distant synapses (up to a meter away in humans), connected only by a cable-like neuronal protrusion called the axon. Such precise movement of synaptic proteins along the axon is achieved by motor proteins which bind to transport vesicles containing synaptic proteins and trail along highways made out of parallel bundles of microtubules (MTs). MTs are dynamic filamentous polymers which are continuously built and degraded throughout a neuron's life, and these processes have to be regulated to sustain proper axonal transport. The number of MTs needs to be well controlled, they have to bear the right posttranslational modifications (PTMs) to promote the right motor protein interactions, and they have to maintain their bundled organisation - all so that blockage or slowdown of transport is prevented. For this, MTs are regulated through MT-binding proteins (MTBPs) which can control MT de/polymerisation, stabilisation, cross-linkage and PTMs. It seems therefore obvious that MTBPs, through controlling MT networks, can regulate axonal transport and consequently also synaptic maintenance and neuronal survival, and this causative chain could provide important explanations for why a number of MTBPs are associated with neurodegenerative disease. However, MTBP-based mechanisms of synaptic maintenance remain poorly understood. For example, the MTBP Tau was discovered several decades ago. It has been associated with Alzheimer's Disease and Frontotemporal Dementia and has therefore been intensely researched. However, its function in health and disease remains surprisingly poorly understood. This is due to the complexity and robustness of the regulatory networks underpinning MT regulation which are experimentally difficult to decipher. To tackle this problem I am using a genetic model organism, the fruit fly Drosophila, I have extensive experience with this system and the role and regulation of the neuronal cytoskeleton therein. I have provided substantial proof of principle that regulatory mechanisms can be deciphered and applied to higher animals. Apart from the enormous amenability and speed of experimentation, the fundamental advantage for cytoskeletal research in Drosophila is the efficiency with which genes can be manipulated and investigated in combination. Thus, on this project, I capitalise on my finding that functions of tau become apparent when combined with loss of a second MTBP, called Shot. Only upon combined deletion does a new phenotype occur consisting in dramatic loss of synapses caused by collapse of axonal transport of synaptic proteins. This phenotype provides robust readouts to decipher the underlying mechanisms, which will be one key objective of this project. In addition, I will study the relevance of these mechanisms for neuronal survival and assess their potential conservation in mouse neurons. This work will unlock important new mechanistic understanding that will advance research on brain development, ageing and degeneration.

神经系统功能的关键先决条件是神经元通过称为突触的专门细胞连接与其他细胞进行通信的能力。突触包含复杂的机械，以快速将信号传输到伴侣细胞。一旦形成，必须将突触保持在塑性状态，并且早熟突触被认为是衰老和神经退行性疾病中神经元衰减的潜在原因。然而，尽管有这种重要性，但很少了解突触维护的机制。该项目的总体目的是提供这样的理解，从而弥合我们对大脑衰老和变性过程的重要差距。在神经元的生活中，其突触机器不断回收。为此，必须在神经元细胞体和非常遥远的突触之间有效地运输其构建块（在人类中最多一米），仅通过称为轴突的电缆状神经元突出连接。突触蛋白沿轴突的精确运动是通过运动蛋白与含有突触蛋白的囊泡结合的，沿着平行束微管（MTS）结合的囊泡。 MT是动态的丝状聚合物，在整个神经元的生命中不断建造和退化，必须调节这些过程以维持适当的轴突运输。 MT的数量需要得到很好的控制，它们必须承担正确的翻译后修饰（PTM），以促进正确的运动蛋白质相互作用，并且必须维持其捆绑的组织 - 所有这些都可以防止运输的阻塞或放缓。为此，MT通过MT结合蛋白（MTBP）调节，该蛋白可以控制MT DE/聚合，稳定，交叉链接和PTM。因此，很明显，MTBP通过控制MT网络可以调节轴突运输，因此也可以进行突触维持和神经元的存活，并且该因果关系可以为为什么许多MTBP与神经退行性疾病有关。但是，基于MTBP的突触维持机制仍然很少了解。例如，几十年前发现了mtbp tau。它与阿尔茨海默氏病和额颞痴呆有关，因此经过深入研究。但是，它在健康和疾病中的功能仍然令人惊讶地了解。这是由于基于MT调节的调节网络的复杂性和鲁棒性，这些网络在实验上很难解密。为了解决这个问题，我正在使用遗传模型生物，即果蝇果蝇，我在该系统以及其中神经元细胞骨架的作用和调节方面具有丰富的经验。我提供了实质性的原则证明，即可以将调节机制解密并应用于高等动物。除了实验的巨大舒适性和速度外，果蝇细胞骨架研究的基本优势是可以组合进行基因和研究基因的效率。因此，在这个项目上，我利用自己的发现，当tau的功能与第二个MTBP的损失相结合，称为Shot。仅在结合缺失后才发生新的表型，包括由突触蛋白的轴突转运引起的突触的急剧丧失。该表型提供了强大的读数来破译基本机制，这将是该项目的关键目标。此外，我将研究这些机制对于神经元存活的相关性，并评估其在小鼠神经元中的潜在保护。这项工作将释放重要的新机械理解，以提高对大脑发育，衰老和变性的研究。

项目成果

Tau, XMAP215 and Eb1 act as a functional trio to regulate microtubule polymerisation and organisation in neurons. Microtubules

Tau、XMAP215 和 Eb1 作为功能三重奏来调节神经元中的微管聚合和组织。

• 发表时间: 2018
• 作者: Hahn I,

Understanding the microtubule regulation that underlies neuronal cell biology

了解神经元细胞生物学基础的微管调节

• 发表时间: 2018
• 作者: Hahn I

Functional and Genetic Analysis of Spectraplakins in Drosophila.

• DOI: 10.1016/bs.mie.2015.06.022
• 发表时间: 2015-08
• 期刊: Methods in enzymology
• 作者: Ines Hahn;M. Ronshaugen;N. Sánchez-Soriano;A. Prokop

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

XMAP215, Eb1 and tau jointly regulate microtubule polymerisation and organisation in axons

XMAP215、Eb1 和 tau 共同调节轴突中的微管聚合和组织

• 发表时间: 2018
• 作者: Hahn I,