Spinal muscular atrophy: a novel role of SMN in axonal ribonucleoprotein complexe

脊髓性肌萎缩症：SMN 在轴突核糖核蛋白复合物中的新作用

• 批准号: 7293410
• 负责人: Wilfried Rossoll
• 金额: $ 19.13万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7293410
• 关键词: Actins; Affect; Amino Acids; Animal Model; Anterior; Anterior Horn Cells; Atrophic; Attention; Axon; Back; Biological; Cell Line; Cell Nucleus; Cells; Childhood; Code; Complex; Cultured Cells; Cytoplasmic Granules; DNA; Data; Defect; Development; Disease; Distal; Functional disorder; Gel; Genes; Genetic; Genomics; Growth Cones; Heterogeneous Nuclear RNA; Horns; Infant Mortality; Inherited; Isotope Labeling; Link; Localized; Maintenance; Messenger RNA; Methods; Modeling; Motor; Motor Neurons; Mus; Muscle Weakness; Mutation; Natural regeneration; Neurites; Neuroglia; Neuromuscular Diseases; Neurons; Nuclear; Patients; Play; Primary Cell Cultures; Process; Protein Biosynthesis; Protein Deficiency; Proteins; Proteome; Proteomics; RNA; RNA Splicing; RNA Transport; Radiolabeled; Regulation; Reporter; Research; Ribonucleoproteins; Role; SMN protein (spinal muscular atrophy); Small Nuclear Ribonucleoproteins; Spinal Cord; Spinal Muscular Atrophy; Stable Isotope Labeling; Staging; Stem cells; Testing; Therapeutic; Time; Transcript; Transgenic Mice; Translating; Translational Regulation; Translations; Work; axon guidance; axonopathy; base; beta Actin; cell motility; cell type; disease-causing mutation; embryonic stem cell; in vivo; innovation; interest; mRNA Precursor; molecular pathology; motor neuron degeneration; nervous system development; neuron loss; neuronal cell body; novel; novel strategies; particle; promoter; radiotracer; red fluorescent protein; research study

DESCRIPTION (provided by applicant): Spinal muscular atrophy (SMA) represents the most common genetic cause of infant mortality. This autosomal recessive neuromuscular disorder is characterized by degeneration of the anterior horn cells of the spinal cord, leading to symmetrical muscle weakness and atrophy. The pathomechanism is still unclear and currently there is no cure or treatment available to stop its progression. SMA is caused by mutations or deletions in the ubiquitously expressed gene encoding the survival of motor neuron protein (SMN). Previous work has focused mainly on the essential role of SMN in the efficient assembly and remodeling of spliceosomal ribonucleoprotein (RNP) complexes in all cell types. It is still unknown why motor neurons are so specifically vulnerable to low levels of SMN and how SMN deficiency selectively causes motor neuron cell death. In neurons, SMN is found located in both the nucleus and in neurites and it is actively transported in the form of dynamic granules. This suggests a novel neuron-specific function of SMN and we hypothesize that an inefficiency of axonal SMN-associated RNPs may contribute to SMA. To better understand the biological role of SMN in the development and maintenance of motor axons, we propose to investigate the in vivo localization of SMN-RNP complexes. We will generate transgenic mice that express biological functional Smn fused to a fluorescent protein reporter to study the dynamic localization of Smn-containing RNP granules during development. Previously, we have shown that growth cones and distal axons of SMN deficient primary motor neurons contain reduced levels of ¿- actin mRNA and protein. New data suggest that Smn-deficiency affects transport and/or local translation of additional transcripts and we will identify and study these affected transcripts and proteins. This proposal will focus on a novel approach to overcome limitations of primary cell culture by using stem-cell derived motor neurons growing as compartmentalized cultures that separate cell bodies and axons. We will identify RNAs that are transported in axons of wild type and SMN-deficient motor neurons and we will also compare the proteome of locally translated proteins in the axons of wild type and Smn-deficient motor neurons. Our results will clarify a potential role of SMN in the transport, stability or local translation of mRNAs in neuronal processes. As these processes have been linked to growth cone motility and axon guidance, it is of big interest to find out how SMN may be involved and how defects in the delivery of RNP complexes may trigger or at least modulate the disease process in SMA. The proposed research is also important more broadly for understanding the function of mRNA localization during the development of the nervous system. Spinal muscular Atrophy (SMA) is an inherited pediatric disease caused by mutations or deletions in a gene encoding the survival motor neuron protein (SMN) that results in rapid degeneration of spinal cord motor neurons and is the leading genetic cause of infant mortality. Its pathomechanism is still unclear and currently there is no cure or treatment available to stop its progression. We propose studies on the axonal function of SMN and the underlying molecular pathology of SMA that have the potential to reveal essential aspects of motor neuron function and development and also to suggest therapeutic strategies for this disease.

描述（由申请人提供）：脊髓性肌萎缩症（SMA）是婴儿死亡的最常见遗传原因。这种常染色体隐性遗传神经肌肉疾病的特征是脊髓前角细胞变性，导致对称性肌肉无力和萎缩。病理机制尚不清楚，目前没有治愈或治疗方法可以阻止其进展。SMA是由编码运动神经元存活蛋白（SMN）的普遍表达基因突变或缺失引起的。以前的工作主要集中在SMN在所有细胞类型中剪接体核糖核蛋白（RNP）复合物的有效组装和重塑中的重要作用。目前还不清楚为什么运动神经元对低水平的SMN如此敏感，以及SMN缺乏如何选择性地导致运动神经元细胞死亡。在神经元中，SMN被发现位于细胞核和神经突中，并且其以动态颗粒的形式被积极地运输。这表明SMN的一种新的神经元特异性功能，我们假设轴突SMN相关RNP的低效率可能有助于SMA。为了更好地了解SMN在运动轴突发育和维持中的生物学作用，我们建议研究SMN-RNP复合物的体内定位。我们将产生转基因小鼠，表达生物功能Smn融合到荧光蛋白报告研究动态定位的Smn含RNP颗粒在发展过程中。以前，我们已经表明，生长锥和远端轴突的SMN缺陷的初级运动神经元含有减少水平的<$-肌动蛋白mRNA和蛋白质。新的数据表明，Smn缺乏影响运输和/或本地翻译的其他成绩单，我们将确定和研究这些受影响的成绩单和蛋白质。该提案将集中于一种新的方法，以克服限制的原代细胞培养，通过使用干细胞衍生的运动神经元生长的分隔文化，分离细胞体和轴突。我们将鉴定野生型和SMN缺陷型运动神经元轴突中转运的RNA，我们还将比较野生型和SMN缺陷型运动神经元轴突中局部翻译蛋白的蛋白质组。我们的研究结果将阐明SMN在神经元过程中mRNA的运输，稳定性或局部翻译中的潜在作用。由于这些过程与生长锥运动和轴突导向有关，因此了解SMN如何参与以及RNP复合物递送中的缺陷如何触发或至少调节SMA中的疾病过程是非常有意义的。这项研究对于更广泛地理解mRNA定位在神经系统发育过程中的功能也很重要。脊髓性肌萎缩（SMA）是一种遗传性儿科疾病，由编码运动神经元存活蛋白（SMN）的基因突变或缺失引起，导致脊髓运动神经元快速变性，是婴儿死亡的主要遗传原因。其病理机制仍不清楚，目前没有治愈或治疗方法可以阻止其进展。我们建议研究SMN的轴突功能和SMA的潜在分子病理学，有可能揭示运动神经元功能和发育的重要方面，并提出这种疾病的治疗策略。