Spinal Muscular atrophy: is it a motor axon disease?

脊髓性肌萎缩症：是运动轴突疾病吗？

基本信息

批准号：
8291243
负责人：
CHRISTINE E BEATTIE
金额：
$ 32.69万
依托单位：
OHIO STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-09-15 至 2015-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8291243
关键词：
Actin-Binding Protein Actins Address Affect Animal Model Animals Axon Binding Biochemistry Biological Models Bundling Cells Cellular biology Cessation of life Complex Data Defect Degenerative Disorder Denervation Development Disease DsRed Electrophysiology (science)Embryo F-Actin Fishes Functional disorder Genetic Human Image Individual Infant Intermediate Filaments Knowledge Life Link Messenger RNA Microscopy Modeling Molecular Genetics Motor Motor Neurons Nerve Neuromuscular Junction Neurons Paralysed Pathway interactions Patients Phenotype Photons Proteins RNA Splicing Respiratory System Role SMN protein (spinal muscular atrophy)Small Nuclear Ribonucleoproteins Spinal Muscular Atrophy Structure Synapses Testing Toddler Transgenic Organisms Vimentin Xenopus Zebrafish base in vivo insight mortality mutant new therapeutic target novel plastin protein distribution public health relevance research study survival motor neuron gene therapeutic development

项目摘要

DESCRIPTION (provided by applicant): Motoneuron diseases are devastating in that they rob individuals of the ability to move and are often fatal due to denervation of the respiratory system. Spinal muscular atrophy (SMA) is an autosomal recessive disease that causes motoneuron dysfunction leading to paralysis and in severe cases death making it a leading genetic cause of infant/toddler mortality. Analysis of SMA animal models reveals, motor axon defects, immature neuromuscular junctions (NMJs), and denervation suggesting that changes at the motor nerve terminal may initiate disease. The survival motor neuron (SMN) gene is the genetic cause of SMA and has a clearly defined role in assembling RNAs and proteins needed for mRNA splicing (snRNP assembly). Data from our lab and others, however, suggest that SMN may have other functions that are compromised when SMN levels are decreased. Using zebrafish as a model system, we have shown that SMN has an snRNP independent function important for normal motor axon outgrowth. Moreover, we have shown that plastin 3, an actin binding protein and the first identified modifier of human SMA, can rescue motor axon defects in zebrafish caused by low Smn levels. In addition, zebrafish smn mutants have severely reduced plastin 3 levels. In this proposal we will test the hypothesis that plastin 3 acts with SMN via an snRNP independent pathway to facilitate normal motoneuron development and function. To directly test this hypothesis, we will ask whether other SMA phenotypes are rescued by plastin 3 (Aim 1). This includes motoneuron and NMJ electrophysiology, SV2 protein at the NMJ, and survival. We will determine how plastin 3 is functioning with respect to SMN by performing a structure/function analysis (Aim 2). For these experiments we will use both plastin 3 and SMN mutants to define relevant domains. We will also test the hypothesis that plastin 3 is unique in its ability to modify SMA phenotypes by examining other actin binding proteins. We will test the hypothesis that the SMN plastin 3 interaction is independent of the snRNP function of SMN (Aim 3). Lastly, we will use live imaging to ask where SMN and plastin 3 proteins localize in motoneurons and does decreasing Smn change the levels and/or cellular localization of plastin 3 (Aim 4). Data derived from these Aims will directly address the relationship between SMN and plastin 3 as it relates to SMA using a combination of electrophysiology, molecular genetics, biochemistry, cell biology, and imaging. Moreover, it would establish an snRNP- independent mechanism of SMN that directly affects motoneuron function thus greatly advancing our understanding of this disease and revealing new therapeutic targets. Using zebrafish is a strength in that we can directly analyze motoneurons in vivo in SMA models that we have developed and easily generate novel transgenics to ask specific questions. This is a unique feature of this model system and thus these studies are highly relevant and will advance our understanding of how low Smn levels cause SMA. PUBLIC HEALTH RELEVANCE: Spinal muscular atrophy (SMA) is a motoneuron degenerative disease that is a leading cause of infant/toddler mortality. Low levels of the survival motor neuron (SMN) protein cause SMA, but how this happens is unclear. Recently a modifier of SMA, the actin binding protein plastin 3, was identified. Experiments in this proposal will directly test the hypothesis that SMN stabilized plastin 3 thus promoting normal motor axon outgrowth and synapses. The proposed experiments will elucidate the interaction and function of plastin 3 as it relates to SMN and has the potential to reveal novel therapeutic targets.

描述（由申请人提供）：运动神经元疾病具有毁灭性，因为它们会剥夺个体的运动能力，并且由于呼吸系统的去神经支配而常常致命。脊髓性肌萎缩症 (SMA) 是一种常染色体隐性遗传疾病，会导致运动神经元功能障碍，导致瘫痪，严重时甚至导致死亡，使其成为婴儿/幼儿死亡的主要遗传原因。对 SMA 动物模型的分析显示，运动轴突缺陷、不成熟的神经肌肉接头 (NMJ) 和去神经支配表明运动神经末梢的变化可能引发疾病。运动神经元存活 (SMN) 基因是 SMA 的遗传原因，在组装 mRNA 剪接（snRNP 组装）所需的 RNA 和蛋白质方面具有明确的作用。然而，我们实验室和其他实验室的数据表明，当 SMN 水平降低时，SMN 的其他功能可能会受到损害。使用斑马鱼作为模型系统，我们证明 SMN 具有对正常运动轴突生长很重要的 snRNP 独立功能。此外，我们还发现，塑性蛋白 3（一种肌动蛋白结合蛋白，也是第一个被鉴定的人类 SMA 修饰剂）可以挽救因 Smn 水平低而引起的斑马鱼运动轴突缺陷。此外，斑马鱼 smn 突变体的 plastin 3 水平严重降低。在本提案中，我们将测试这样的假设：plastin 3 通过 snRNP 独立途径与 SMN 相互作用，以促进正常运动神经元的发育和功能。为了直接检验这一假设，我们将询问其他 SMA 表型是否可以被 plastin 3 拯救（目标 1）。这包括运动神经元和 NMJ 电生理学、NMJ 处的 SV2 蛋白以及存活率。我们将通过进行结构/功能分析来确定 plastin 3 对于 SMN 的作用（目标 2）。对于这些实验，我们将使用 plastin 3 和 SMN 突变体来定义相关域。我们还将通过检查其他肌动蛋白结合蛋白来检验以下假设：plastin 3 具有独特的改变 SMA 表型的能力。我们将检验 SMN plastin 3 相互作用独立于 SMN 的 snRNP 功能的假设（目标 3）。最后，我们将使用实时成像来询问 SMN 和 plastin 3 蛋白在运动神经元中的定位，以及减少 Smn 是否会改变 plastin 3 的水平和/或细胞定位（目标 4）。来自这些目标的数据将结合电生理学、分子遗传学、生物化学、细胞生物学和成像技术，直接解决 SMN 和 plastin 3 之间的关系，因为它与 SMA 相关。此外，它将建立一个独立于snRNP的SMN机制，直接影响运动神经元功能，从而极大地增进我们对这种疾病的理解并揭示新的治疗靶点。使用斑马鱼的优势在于，我们可以在我们开发的 SMA 模型中直接分析体内运动神经元，并轻松生成新的转基因来提出特定问题。这是该模型系统的独特特征，因此这些研究具有高度相关性，并将增进我们对低 Smn 水平如何导致 SMA 的理解。公共卫生相关性：脊髓性肌萎缩症 (SMA) 是一种运动神经元退行性疾病，是婴儿/幼儿死亡的主要原因。低水平的运动神经元存活蛋白 (SMN) 会导致 SMA，但这种情况是如何发生的尚不清楚。最近鉴定出 SMA 的修饰物，即肌动蛋白结合蛋白 plastin 3。本提案中的实验将直接检验 SMN 稳定 plastin 3 从而促进正常运动轴突生长和突触的假设。拟议的实验将阐明 plastin 3 与 SMN 的相互作用和功能，并有可能揭示新的治疗靶点。