Functional Adaptation of Microtubules by Acetylation

描述（由申请人提供）：微管是普遍存在的真核生物结构，由1-微管蛋白和2-微管蛋白二聚体构成。微管在细胞运动、细胞内运输和细胞极化中起着关键作用。目前还不清楚不同的微管是如何在细胞内的多种情况下起作用的。通常，运动蛋白沿着微管亚群移动特定的细胞货物，这种选择性运输对细胞极化至关重要。一个显著的例子是神经元，特定的货物从细胞体转移到树突或轴突突起。调控微管表面选择性转运的原理和机制尚不清楚。我们探索了一种假设，即微管通过微管蛋白亚基的空间限制性翻译后修饰（PTMs），在功能上适应于选择性运输和其他局部功能。1-微管蛋白上K40的乙酰化是一个高度保守的PTM，标志着微管的周转相对缓慢。在神经元中，与树突微管相比，1-微管蛋白的K40乙酰化在轴突微管上高度富集。最近的研究表明，轴突微管的K40乙酰化刺激轴突内特定运动蛋白的结合和运动，包括运动蛋白-1。我们在这里报道了一种保守蛋白的鉴定，这种蛋白是模式原生动物四膜虫和斑马鱼中K40 1-微管蛋白乙酰化所必需的。该蛋白是MEC-17的同源物，MEC-17是秀丽隐杆线虫触觉受体神经元功能所必需的一种蛋白。我们发现MEC-17在体外介导1-微管蛋白上K40的乙酰化。我们将验证MEC17是长期寻找的1-微管蛋白K40乙酰转移酶的假设，并且MEC17通过使1-微管蛋白上的K40乙酰化，有助于神经元的分化和功能。我们将使用模式生物秀丽隐杆线虫和斑马鱼来评估MEC-17和K40乙酰化对1-微管蛋白的作用，特别是在两种类型的神经元中：触摸受体神经元（秀丽隐杆线虫）和初级运动神经元（斑马鱼）。由于1-微管蛋白的乙酰化在神经系统中高度富集，这一建议与广泛的疾病，特别是神经退行性疾病有关。

DESCRIPTION (provided by applicant): Microtubules are ubiquitous eukaryotic structures, built of dimers of 1- and 2-tubulin. Microtubules play key roles in cell motility, intracellular trafficking and cell polarization. It is not well understood how diverse microtubules function in multiple contexts inside the cell. Commonly, motor proteins move specific cellular cargoes along subsets of microtubules, and this selective transport is critical for cell polarization. One striking example is the neuron, where specific cargoes are moved from the cell body either into the dendrite or axon projections. The principles and mechanisms that govern the selective transport on the surface of microtubules are not well understood. We explore a hypothesis that microtubules are functionally adapted for selective transport and other localized functions, by spatially restricted post-translational modifications (PTMs) of tubulin subunits. Acetylation of K40 on 1- tubulin is a highly conserved PTM, that marks microtubules which turnover relatively slowly. In neurons, K40 acetylation of 1-tubulin is highly enriched on microtubules of the axon as compared to microtubules in dendrites. Recent studies indicate that K40 acetylation of axonal microtubules stimulates binding and motility of specific motor proteins, including kinesin-1 inside the axon. We report here an identification of a conserved protein that is required for K40 1-tubulin acetylation in the model protist Tetrahymena and zebrafish. This protein is an ortholog of MEC-17, a previously studied protein which is required for the function of touch receptor neurons in C. elegans. We show that MEC-17 mediates acetylation of K40 on 1- tubulin in vitro. We will test the hypothesis that MEC17 is the long-sought 1-tubulin K40 acetyltransferase, and that MEC-17, by acetylating K40 on 1-tubulin, contributes to neuronal differentiation and function. We will use model organisms, the worm Caenorhabditis elegans and zebrafish Danio rerio, to evaluate the function of MEC-17 and K40 acetylation on 1- tubulin, specifically in two types of neurons: in touch receptor neurons (C. elegans) and in primary motor neurons (zebrafish). As acetylation of 1-tubulin is highly enriched in the nervous system, this proposal is relevant to a broad range of diseases and in particular to the neurodegenerative disorders. PUBLIC HEALTH RELEVANCE: Eukaryotic cells are filled with fibers known as microtubules, that serve as tracks for intracellular transport and regulate the shape of cells. This project will test a hypothesis that patterns of biochemical marks on the surface of microtubules adapt specific microtubule fibers for specific functions, including a selective transport of certain cellular components. This project will have an impact on understanding of pathology of human diseases that are associated with defects in microtubules, including some neurodegenerative disorders.