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（由适用提供）：脊柱肌肉萎缩（SMA）代表婴儿死亡率最常见的遗传原因。这种常染色体隐性神经肌肉疾病的特征是脊髓的前角细胞退化，导致对称肌肉无力和萎缩。病理机制仍不清楚，目前尚无治愈或治疗可阻止其进展。 SMA是由编码运动神经元蛋白（SMN）存活的普遍表达基因中的突变或缺失引起的。先前的工作主要集中在SMN在所有细胞类型中的剪接体色膜蛋白（RNP）配合物的有效组装和重塑中的重要作用。仍然未知运动神经元如此易受SMN水平的特定症状以及SMN缺乏症如何有选择地导致运动神经元细胞死亡。在神经元中，SMN均位于核和神经元中，并以动态颗粒的形式积极运输。这表明SMN具有新的神经特异性功能，我们假设轴突SMN相关的RNP效率低下可能会导致SMA。为了更好地了解SMN在运动轴突的开发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。我们将生成转基因小鼠，表达与荧光蛋白报道融合的生物学功能性SMN，以研究开发过程中含有SMN的RNP颗粒的动态定位。以前，我们已经表明，SMN缺乏原发性运动神经元的生长锥和远端轴突含有降低的 - 肌动蛋白mRNA和蛋白质的水平。新数据表明，SMN缺陷会影响其他成绩单的运输和/或局部翻译，我们将识别和研究这些受影响的成绩单和蛋白质。该建议将着重于一种新的方法来克服原代细胞培养的局限性，通过使用生长的干细胞衍生运动神经元作为分隔细胞体和轴突的分隔培养物。我们将确定在野生型和SMN缺乏运动神经元轴突中运输的RNA，我们还将比较野生型和SMN缺陷运动神经元轴突中局部翻译的蛋白质的蛋白质。我们的结果将阐明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的指导有关，因此了解如何参与SMN以及RNP复合物输送的缺陷如何触发或至少调节SMA中的疾病过程是很大的兴趣。拟议的研究对于理解神经系统发展过程中mRNA定位的功能也更为重要。脊柱肌肉萎缩（SMA）是由编码生存运动神经元蛋白（SMN）的突变或缺失引起的遗传性儿科疾病，导致脊髓运动神经元快速退化，是婴儿死亡率的主要遗传原因。病理机理尚不清楚，目前尚无治愈或治疗可阻止其进展。我们提出了有关SMN的轴突功能和SMA的潜在分子病理的研究，这些功能有可能揭示运动神经元功能和发育的基本方面，并提出针对该疾病的治疗策略。