Regulation of SMN and Identification of its Downstream Target

SMN的调控及其下游目标的识别

• 批准号: 8064286
• 负责人: Judith A Steen
• 金额: $ 44.01万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8064286
• 关键词: 2 year old; 3' Untranslated Regions; APC2 gene; Affect; Axon; Binding; Biogenesis; Biology; Brain Stem; Candidate Disease Gene; Caspase; Cell Cycle; Cell Nucleus; Cessation of life; Co-Immunoprecipitations; Complex; Data; Defect; Disease; Elements; Genes; Genetic; Growth; Growth Factor; Half-Life; Human; Indium; Individual; Infant Mortality; Knockout Mice; Kugelberg-Welander Disease; Length; Maintenance; Maps; Mass Spectrum Analysis; Measures; Messenger RNA; Modeling; Molecular Profiling; Motor Neurons; Muscle; Mutate; Mutation; Neurites; Neurons; Pathology; Pathway interactions; Patients; Phenotype; Play; Proteins; Proteomics; RNA; RNA Splicing; RNA analysis; RNA-Binding Proteins; Regulation; Respiratory Failure; Role; SMN1 gene; SMN2 gene; Severity of illness; Site; Spinal; Spinal Cord; Spinal Muscular Atrophy; Testing; Therapeutic Intervention; Transcript; Translations; Ubiquitination; United States; Western Blotting; Work; anaphase-promoting complex; axon growth; crosslink; deprivation; disease-causing mutation; infant death; insight; interest; loss of function; mRNA Expression; member; multicatalytic endopeptidase complex; neuron apoptosis; neuronal survival; novel; overexpression; prevent; protein complex; protein degradation; public health relevance; research study; survival motor neuron gene; synaptic function; synaptogenesis; therapy design; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): Spinal Muscular Atrophy (SMA), a disease caused by the mutations of Survival Motor Neuron 1 (SMN1) gene, is the most common genetic cause of infant mortality. Humans have two copies of the SMN gene, the telomeric SMN1, which encodes for a full-length form (FL-SMN), and the centromeric SMN2, which encodes primarily for a rapidly-degraded truncated form (SMN 7) as well as the full-length form. In the most severe form, Type 1 SMA, there are 1 or 2 copies of the SMN2 gene, and patients die within 2 years of age due to respiratory failure. Patients with more copies of the SMN2 gene, however, manifest a less severe form of SMA (Type III SMA). SMA occurs due to decreased amount of FL-SMN protein in spinal motor neurons. Therefore, much of the effort for therapeutic interventions in SMA has focused on increasing the level of FL-SMN protein products. Our preliminary results show that SMN is found in a complex containing an E3 ubiquitin ligase the Anaphase- Promoting Complex (APC) and HuD, a RNA binding protein. The APC targets proteins to the proteasome for degradation whereas HuD stabilizes mRNAs. Furthermore, evidence indicates a role for APC in neuronal survival, axonal growth, and synaptic function, and HuD is involved in the maturation and maintenance of neurons. We also know from previous studies that SMN may be necessary for the transport, stability and/or translation of certain mRNAs in neurites. These data together prompted us to formulate a working model in which: 1) ubiquitination by APC regulates the stability and/or function of SMN or other members of the SMN complex and 2) the putative HuD-SMN-associated mRNAs in axons are important for the growth and survival of motor neurons. In the first part of this application, we will investigate the role of APC in regulation of SMN stability and function. We will first characterize the interaction between APC and SMN in neurons. Then, we will investigate the effect of inhibiting the APC-SMN interaction on the function, stability, localization, of SMN protein. In the second part, we will focus on one axonal SMN target mRNA which is likely to play a role in axon outgrowth. Since there is a tight correlation between the amount of FL-SMN and the severity of disease, understanding the interaction between APC and SMN as well as elucidating the downstream targets of SMN will provide important insights into the biology of SMA and has the potential to generate new treatment options for this disease. PUBLIC HEALTH RELEVANCE: Spinal muscular atrophy (SMA) is the leading genetic cause of infant deaths in the United States. We propose to investigate the cellular mechanisms of this disease using state of the art proteomics and RNA analysis. Understanding these cellular mechanisms may ultimately be important for designing therapies for SMA.

描述（由申请人提供）：脊髓性肌萎缩症（SMA）是一种由运动神经元生存1（SMN 1）基因突变引起的疾病，是婴儿死亡的最常见遗传原因。人类有两个拷贝的SMN基因，端粒SMN 1，编码全长形式（FL-SMN），和着丝粒SMN 2，主要编码快速降解的截短形式（SMN 7）以及全长形式。在最严重的1型SMA中，有1或2个SMN 2基因拷贝，患者在2岁内死于呼吸衰竭。然而，具有更多SMN 2基因拷贝的患者表现出不太严重的SMA形式（III型SMA）。SMA的发生是由于脊髓运动神经元中FL-SMN蛋白的量减少。因此，SMA治疗干预的大部分努力都集中在增加FL-SMN蛋白产物的水平上。我们的初步研究结果表明，SMN是在一个复合物中发现的，该复合物含有E3泛素连接酶，后期促进复合物（APC）和HuD，一种RNA结合蛋白。APC将蛋白质靶向蛋白酶体以进行降解，而HuD稳定mRNA。此外，证据表明APC在神经元存活、轴突生长和突触功能中的作用，并且HuD参与神经元的成熟和维持。我们还从以前的研究中知道，SMN可能是必要的运输，稳定性和/或某些mRNA在神经突的翻译。这些数据共同促使我们制定了一个工作模型，其中：1）APC的泛素化调节SMN或SMN复合物其他成员的稳定性和/或功能，2）轴突中推定的HuD-SMN相关mRNA对运动神经元的生长和存活很重要。在本申请的第一部分中，我们将研究APC在SMN稳定性和功能调节中的作用。我们将首先描述APC和SMN在神经元中的相互作用。然后，我们将研究抑制APC-SMN相互作用对SMN蛋白的功能、稳定性、定位的影响。在第二部分中，我们将集中在一个轴突SMN靶mRNA，这是可能发挥作用的轴突生长。由于FL-SMN的数量与疾病的严重程度之间存在密切相关性，因此了解APC和SMN之间的相互作用以及阐明SMN的下游靶点将为SMA的生物学提供重要见解，并有可能为这种疾病提供新的治疗选择。 公共卫生相关性：脊髓性肌萎缩症（SMA）是美国婴儿死亡的主要遗传原因。我们建议使用最先进的蛋白质组学和RNA分析来研究这种疾病的细胞机制。了解这些细胞机制最终可能对设计SMA疗法很重要。