Functional consequences of HSPB1 mutations that result in motor neuron disease

HSPB1 突变导致运动神经元疾病的功能后果

基本信息

批准号：
8309329
负责人：
Stephen J. Kolb
金额：
$ 18.16万
依托单位：
OHIO STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-09-01 至 2015-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8309329
关键词：
Affect Animals Bacterial Artificial Chromosomes Biological Assay Biological Models Biology Cell Culture Techniques Cells Cellular Stress Cessation of life Clinical Data Development Distal Elements Ensure Environment Genes Goals HSPB1 gene Heat shock proteins Infection Inflammatory Inherited Injury Interferons Investigation Lasers Lead Measures Messenger RNA Microglia Microscopy Modeling Molecular Molecular Genetics Motor Motor Neuron Disease Motor Neurons Mus Muscle Weakness Mutant Strains Mice Mutate Mutation Nerve Crush Neurodegenerative Disorders Neuroglia Neurons Neuropathy Ohio Pathogenesis Pathology Pathway interactions Patients Phenotype Physicians Play Prions Proteins RNA RNA Decay Reporter Respiratory Failure Role Scientist Series Testing Training Transgenes Transgenic Animals Transgenic Mice Universities animal model development cytokine effective therapy in vivo insight mRNA Decay motor neuron function motor neuron injury mouse model mutant nervous system disorder neuromuscular neuron loss neurotoxicity new therapeutic target novel overexpression promoter public health relevance treatment strategy

项目摘要

DESCRIPTION (provided by applicant): Motor neuron diseases (MNDs) are neurodegenerative disorders that cause muscle weakness and often respiratory failure and death. Rapid progress in the molecular genetics of MNDs has revealed at least 22 distinct genes that are expressed in all cells and yet result exclusively in motor neuron (MN) loss when mutated. The small heat shock protein B1 (HSPB1, formerly HSP27) is mutated in patients with hereditary motor neuropathy (HMN). HSPB1 is unique among MND-causing genes in that overexpression of the wild type HSPB1 is known to be neuroprotective in MNs whereas mutations are toxic to MNs. The primary goal of this proposal is to determine the molecular function of HSPB1 that is relevant to motor neuron survival. To do this, we have developed a mouse model of motor neuropathy expresing the most common HSPB1 mutation (R136W) in neurons. We find that HSPB1 mutant mice display a phenotype of mild weakness that mimics HMN. We propose to develop a second line of mice expressing mutant HSPB1 in all cells so that we may distinguish between MN and non-MN contributions to MN injury. The role of non-neuronal cells in the progression of MND is emerging as an important concept and genes expressed by microglia in particular may be important targets in reducing MN loss in MNDs. We hypothesize that animals expressing HSPB1(R136W) in all cells will have a phenotype that is more severe than animals expressing HSPB1(R136W) exclusively in neurons. HSPB1 is required for a specific mRNA decay pathway caled AU-rich element (ARE)-dependent mRNA decay. AU-rich element mRNA decay is a critical mechanism in all cells to control the expression of a select group of mRNAs. Our preliminary data demonstrate that HSPB1(R136W) is defective in this RNA decay pathway, which raises the possibility that ARE-containing mRNAs (normally degraded via this pathway) may play a role in MN pathology. Many of these genes encode proteins such as interferons and inflammatory cytokines which have protective functions during injury and infections, but can be damaging when upregulated. We hypothesize that mRNA levels of ARE-containing mRNAs will be elevated in MNs and microglia expressing mutant HSPB1 compared to wild type HSPB1. To test this, we will directly measure ARE-containing mRNAs in MNs and microglia in mice. The development of these animals and the identification of the molecular function of HSPB1 that is important for MN survival will lead to new therapeutic targets and treatments for patients with HMN and has great potential to advance our understanding of and provide novel treatment strategies for all MNDs. PUBLIC HEALTH RELEVANCE: The HSPB1 protein plays a critical role in an important RNA decay pathway and is neuroprotective in motor neurons. The proposed studies of HSPB1 function are highly likely to provide novel insights into normal motor neuron function and to the pathogenesis of motor neuron diseases. Ultimately, this project will lead to the identification of novel targets for the treatment of this devastating class of nervous system disease.

描述（由申请人提供）：运动神经元疾病（MND）是一种神经退行性疾病，会导致肌肉无力，并经常导致呼吸衰竭和死亡。 MND 分子遗传学的快速进展揭示了至少 22 个不同的基因在所有细胞中表达，但在突变时仅导致运动神经元 (MN) 损失。小热休克蛋白 B1（HSPB1，以前称为 HSP27）在遗传性运动神经病 (HMN) 患者中发生突变。 HSPB1 在导致 MND 的基因中是独特的，因为已知野生型 HSPB1 的过度表达对 MN 具有神经保护作用，而突变对 MN 具有毒性。该提案的主要目标是确定与运动神经元存活相关的 HSPB1 分子功能。为此，我们开发了一种运动神经病小鼠模型，表达神经元中最常见的 HSPB1 突变 (R136W)。我们发现 HSPB1 突变小鼠表现出模仿 HMN 的轻度无力表型。我们建议开发在所有细胞中表达突变 HSPB1 的第二个小鼠系，以便我们可以区分 MN 和非 MN 对 MN 损伤的贡献。非神经元细胞在 MND 进展中的作用正在成为一个重要概念，特别是小胶质细胞表达的基因可能是减少 MND 中 MN 损失的重要靶点。我们假设在所有细胞中表达 HSPB1(R136W) 的动物将具有比仅在神经元中表达 HSPB1(R136W) 的动物更严重的表型。 HSPB1 是一种称为 AU 富集元件 (ARE) 依赖性 mRNA 衰减的特定 mRNA 衰减途径所必需的。富含 AU 元素的 mRNA 衰减是所有细胞中控制一组选定 mRNA 表达的关键机制。我们的初步数据表明 HSPB1(R136W) 在该 RNA 降解途径中存在缺陷，这提出了含有 ARE 的 mRNA（通常通过该途径降解）可能在 MN 病理学中发挥作用的可能性。其中许多基因编码干扰素和炎症细胞因子等蛋白质，这些蛋白质在损伤和感染期间具有保护功能，但上调时可能具有破坏性。我们假设与野生型 HSPB1 相比，表达突变型 HSPB1 的 MN 和小胶质细胞中含有 ARE 的 mRNA 的 mRNA 水平会升高。为了测试这一点，我们将直接测量小鼠 MN 和小胶质细胞中含有 ARE 的 mRNA。这些动物的发育以及对 MN 生存至关重要的 HSPB1 分子功能的鉴定将为 HMN 患者带来新的治疗靶点和治疗方法，并且具有巨大的潜力，可以增进我们对所有 MND 的理解并为所有 MND 提供新的治疗策略。公共健康相关性：HSPB1 蛋白在重要的 RNA 衰减途径中发挥着关键作用，并且对运动神经元具有神经保护作用。拟议的 HSPB1 功能研究很可能为正常运动神经元功能和运动神经元疾病的发病机制提供新的见解。最终，该项目将确定治疗此类破坏性神经系统疾病的新靶标。