The Spinal Muscular Atrophy NMJ phenotype: mechanisms and molecular mediators

脊髓性肌萎缩症 NMJ 表型：机制和分子介质

基本信息

批准号：
9385016
负责人：
Umrao Monani
金额：
$ 20万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-05-01 至 2019-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9385016
关键词：
Acute Address Adult Affect Agrin Biogenesis Catalogs Cells Characteristics Childhood Complement Defect Development Disease Event Gene Expression Genes Genetic Transcription Glean Homologous Gene Housekeeping Infant Mortality Inherited Light Link Mediating Mediator of activation protein Molecular Motor Motor Neurons Mus Muscle Mutant Strains Mice Mutation Nature Nerve Neuromuscular Diseases Neuromuscular Junction Neurons Pathology Patients Peripheral Phenotype Play Process Proteins RNA Processing RNA Splicing Reporting Role SMN2 gene Scientist Small Nuclear Ribonucleoproteins Spinal Spinal Muscular Atrophy Structure Synapses Tamoxifen Testing Time Transcript Transgenes Transgenic Organisms Uncertainty disease phenotype experimental study human disease insight knock-down mRNA Precursor motor control mouse model mutant nerve injury neuromuscular neuromuscular system neuron loss novel particle postnatal protein expression protein function selective expression skeletal muscle wasting stem transcriptome

Acute Address Adult Affect Agrin Biogenesis Catalogs Cells Characteristics Childhood Complement Defect Development Disease Event Gene Expression Genes Genetic Transcription Glean Homologous Gene Housekeeping Infant Mortality Inherited Light Link Mediating Mediator of activation protein Molecular Motor Motor Neurons Mus Muscle Mutant Strains Mice Mutation Nature Nerve Neuromuscular Diseases Neuromuscular Junction Neurons Pathology Patients Peripheral Phenotype Play Process Proteins RNA Processing RNA Splicing Reporting Role SMN2 gene Scientist Small Nuclear Ribonucleoproteins Spinal Spinal Muscular Atrophy Structure Synapses Tamoxifen Testing Time Transcript Transgenes Transgenic Organisms Uncertainty disease phenotype experimental study human disease insight knock-down mRNA Precursor motor control mouse model mutant nerve injury neuromuscular neuromuscular system neuron loss novel particle postnatal protein expression protein function selective expression skeletal muscle wasting stem transcriptome

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项目摘要

Spinal muscular atrophy is a common, recessively inherited, pediatric neuromuscular disorder caused by mutations in the Survival of Motor Neuron 1 (SMN1) gene and a deficiency of the SMN protein. SMN is ubiquitously expressed and reported to play a critical role in RNA processing, by orchestrating the biogenesis of spliceosomal small nuclear ribonucleoprotein (snRNP) particles. The assembly of these particles is severely compromised in SMA model mice. Restoring SMN to the mutants not only corrects this defect but also fully rescues the SMA phenotype. Nevertheless, SMN’s role in snRNP assembly, which is a requirement of all cells, has been difficult to reconcile with the selective neuromuscular disease phenotype characteristic of SMA. One way to explain this conundrum is to suggest that transcripts selectively expressed in one or more cells of the neuromuscular system fail to be properly processed owing to defects in SMN’s housekeeping function. Alternatively, the selective SMA phenotype could stem from novel SMN functions in the motor unit. In this project we wish to address each possibility. In aim 1 of the project we will determine if neuronal agrin, which was found to be mis-spliced in SMA motor neurons, presumably as a consequence of defects in snRNP biogenesis, is a true mediator of the SMA phenotype. Neuronal agrin is known to be important for the development of neuromuscular synapses, structures that are profoundly affected in SMA. To test possible links between agrin and the SMA phenotype, we will transgenically restore the protein selectively to the motor neurons of SMA model mice. We will then assess the consequences of agrin repletion in the mice at the molecular, cellular and phenotypic levels. In aim 2 of the project we will identify transcriptional/splice alterations in SMA motor neurons during a critical window of time that defines neuromuscular synapse maturation. This experiment takes advantage of a novel line of tamoxifen-induced SMN knockdown mice that we have developed, and exploits new findings suggesting that the requirements for the SMN protein are greatest when neuromuscular synapses mature. Following acute depletion of SMN prior to or immediately after neuromuscular synapses mature, we will catalogue motor neuronal gene expression changes in mutants and controls. This approach which complements Aim 1, but is unbiased with respect to any one gene, will uncover molecules that are important in the maturation of the neuromuscular synapses, a process that is disrupted in SMA. Some of these molecular alterations may eventually point to novel, disease-relevant and phenotype- specific functions of the protein. The collective results of the project will lead to new insights into a disease for which an optimal treatment has yet to be developed, and whose phenotype continues to puzzle scientists in light of what is currently known about the SMN protein.

脊柱肌肉萎缩是一种常见的，隐性遗传的小儿神经肌肉疾病运动神经元1（SMN1）基因生存中的突变和SMN蛋白的缺乏。 SMN是通过策划生物发生，无处不在表达并据报道在RNA加工中起关键作用剪接小的小核核糖核蛋白（SNRNP）颗粒的颗粒。这些粒子的组装严重在SMA模型小鼠中妥协。将SMN恢复到突变体不仅可以纠正此缺陷，而且还完全营救SMA表型。但是，SMN在SNRNP大会中的作用，这是所有人的要求细胞很难与SMA的选择性神经肌肉疾病表型调和。解释此难题的一种方法是建议在一个或多个单元中选择性表达的转录本由于SMN的管家功能缺陷，神经肌肉系统无法正确处理。或者，选择性SMA表型可能源于运动单元中的新型SMN功能。在这个项目我们希望解决每种可能性。在该项目的目标1中，我们将确定是否神经元Agrin，这是否是被发现在SMA运动神经元中被遗忘，大概是由于SNRNP缺陷而导致的生物发生，是SMA表型的真正介体。众所周知，神经元阿格林对神经肌肉突触的发展，在SMA中受到深远影响的结构。测试可能 Agrin和SMA表型之间的链接，我们将自动将蛋白质选择性地恢复到电动机 SMA模型小鼠的神经元。然后，我们将评估小鼠在小鼠中复制的后果分子，细胞和表型水平。在项目的目标2中，我们将确定转录/剪接更改在定义神经肌肉突触成熟的关键时间窗口中，在SMA运动神经元中。这实验利用了我们拥有的一条新型的他莫昔芬诱导的SMN敲低小鼠开发并利用新发现，表明SMN蛋白的要求是最大的神经肌肉突触成熟。在急性耗尽SMN之前或之后神经肌肉突触成熟，我们将在突变体和控件。完成目标1的这种方法，但相对于任何一个基因都是公正的，将发现在神经肌肉突触的成熟中很重要的分子，这一过程被破坏 SMA。这些分子改变中的一些有时可能指出新型，与疾病相关和表型 - 蛋白质的特定功能。该项目的集体结果将导致对疾病的新见解哪种最佳治疗尚未开发出来，其表型继续使科学家感到困惑目前知道的SMN蛋白的光。