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

• 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
• 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

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）是导致肌肉无力的神经退行性疾病，通常是呼吸衰竭和死亡。 MND的分子遗传学的快速进展揭示了至少22种不同的基因，这些基因在所有细胞中均表达，但在突变时仅导致运动神经元（MN）丧失。在遗传性运动神经病（HMN）患者中，小热休克蛋白B1（HSPB1，以前的HSP27）突变。 HSPB1在MND引起的基因中是独一无二的，因为已知野生型HSPB1的过表达在MNS中具有神经保护作用，而突变对MNS有毒。该建议的主要目标是确定与运动神经元存活有关的HSPB1的分子功能。为此，我们开发了一种运动神经病的小鼠模型，该模型阐明了神经元中最常见的HSPB1突变（R136W）。我们发现HSPB1突变小鼠表现出模仿HMN的轻度弱点的表型。我们建议在所有细胞中开发出表达突变HSPB1的第二行小鼠，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的概念，特别是小胶质细胞表达的基因可能是减少MND中MN损失的重要靶标。我们假设所有细胞中表达HSPB1（R136W）的动物的表型将比仅在神经元中表达HSPB1（R136W）的动物更为严重。对于特定的mRNA衰变途径钙化Au富元素（AS）依赖性mRNA衰减所需的HspB1是必需的。富含Au的元素mRNA衰减是所有细胞中控制选定mRNA表达的关键机制。我们的初步数据表明，HSPB1（R136W）在此RNA衰变途径中有缺陷，这增加了含有mRNA的可能性（通常通过此途径降解）可能在MN病理学中起作用。这些基因中有许多编码蛋白质，例如干扰素和炎性细胞因子，它们在受伤和感染过程中具有保护功能，但在上调时可能会损害。我们假设与野生型HSPB1相比，在MNS和表达突变HSPB1的小胶质细胞中，含有的mRNA mRNA水平将升高。为了测试这一点，我们将直接测量小鼠MN和小胶质细胞中的mRNA。这些动物的发展以及HSPB1的分子功能对MN存活很重要的鉴定将为HMN患者带来新的治疗靶标和治疗方法，并具有巨大的潜力，可以提高我们对所有MND的理解并提供新颖的治疗策略。 公共卫生相关性：HSPB1蛋白在重要的RNA衰减途径中起关键作用，并且在运动神经元中具有神经保护作用。提出的HSPB1功能的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理提供新的见解。最终，该项目将导致确定治疗这种毁灭性类神经系统疾病的新目标。