Mechanisms of motor neuron toxicity in Kennedy disease

肯尼迪病运动神经元毒性机制

基本信息

批准号：
9906923
负责人：
ANDREW P LIEBERMAN
金额：
$ 52.31万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-03-05 至 2022-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9906923
关键词：
AR gene Affinity Allosteric Regulation Androgen Receptor Binding Biochemical Biochemical Genetics Biological Models Cell model Cell physiology Cells Complex Crosslinker Data Defect Degenerative Disorder Development Disease Disease model Drosophila genus Foundations Genetic Glutamine Goals Hip region structure Hormones Impairment Kennedy Syndrome Knock-in Mouse Knowledge Laboratories Length Modeling Molecular Chaperones Molecular Conformation Motor Neurons Mus Muscle Weakness Nerve Degeneration Nuclear Translocation Pathogenesis Pathway interactions Patients Permeability Pharmacology Phenotype Play Proteins Public Health Publishing Quality Control Resolution Role Site Skeletal Muscle Speed Structure Sulfhydryl Compounds Supportive care Techniques Testing Therapeutic Toxic effect Transgenic Organisms Triage Ubiquitin Ubiquitination Work age related base cryogenics disease-causing mutation effective therapy expectation men misfolded protein multicatalytic endopeptidase complex mutant nervous system disorder neuromuscular neurotoxicity novel therapeutic intervention novel therapeutics overexpression polyglutamine protein complex receptor receptor expression small molecule spinal and bulbar muscular atrophy ubiquitin-protein ligase

项目摘要

ABSTRACT Spinal and bulbar muscular atrophy (SBMA) is a degenerative disorder of lower motor neurons and skeletal muscle caused by a CAG/glutamine tract expansion in the androgen receptor (AR) gene. The polyglutamine AR (polyQ AR) undergoes hormone-dependent nuclear translocation and unfolding, steps that are essential to toxicity and to the development of progressive muscle weakness in men. Although the disease causing mutation was identified over two and a half decades ago, only supportive therapies are currently available to SBMA patients. Model systems that have been used to study disease pathogenesis show hormone and glutamine length-dependent changes in an array of downstream pathways, supporting a role for divergent mechanisms in toxicity. These observations prompted us to focus instead on understanding the proximal mechanisms that regulate degradation of the mutant androgen receptor protein in hopes of harnessing these for the discovery of effective treatments. However, these clearance pathways are incompletely defined, and this lack of knowledge hinders the development of disease-modifying therapies. The objective of this application is to define the role of Hsp70 in the protein quality control decisions that govern degradation of the full-length polyQ AR. The scientific premise of this application is that the Hsp70, acting through the Hsp90/Hsp70-based machinery and the Hsp70/Hsp110 disaggregase machinery, plays a critical role in controlling polyQ AR degradation through the proteasome. This premise provides the foundation for our central hypothesis that Hsp70 targeted strategies will promote ubiquitination and clearance of the mutant protein. This hypothesis springs from our preliminary data showing that association with Hsp90 stabilizes the polyQ AR, while unfolding of the mutant protein leads to ubiquitination by Hsp70-dependent E3 ligases. Moreover, we will build upon our published studies demonstrating that allosteric regulation of Hsp70 to increase binding to misfolded proteins enhances clearance of the polyQ AR in cells and alleviates toxicity in a Drosophila model. The rationale of the proposed work is that establishing the mechanisms that regulate polyQ AR degradation will identify targets that can be exploited for the development of new therapies. Structural, biochemical, genetic and pharmacological approaches will be used to characterize the Hsp70-CHIP complex with the polyQ AR that regulates protein triage (Aim 1), establish the effects of genetic and small molecule allosteric regulators of Hsp70 in SBMA models (Aim 2), and determine effects of polyQ AR expression on ubiquitin-proteasome pathway function (Aim 3). These studies are expected to characterize the structure and function of the cellular machinery that regulates polyQ AR degradation and provide proof-of-concept data supporting a therapeutic approach centered on targeting Hsp70. As this chaperone also regulates quality control decisions governing the turnover of other mutant proteins that cause neurodegeneration, we expect that the approaches defined here will inform therapeutic strategies that will be applicable to other age-dependent neurological diseases.

抽象的脊柱和鳞茎肌肉萎缩（SBMA）是低运动神经元和骨骼的退化性疾病由雄激素受体（AR）基因中的CAG/谷氨酰胺道膨胀引起的肌肉。聚谷氨酰胺 AR（PolyQ AR）经历激素依赖性的核易位和展开，这是必不可少的步骤毒性和对男性进行性肌肉无力的发展。虽然疾病引起在两年半前确定了突变，目前只能使用支持疗法 SBMA患者。用于研究疾病发病机理的模型系统显示激素和谷氨酰胺的长度依赖性变化在一系列下游途径中，支持发散的角色毒性机制。这些观察结果促使我们专注于理解近端调节突变体雄激素受体蛋白降解的机制，以利用这些蛋白为了发现有效的治疗。但是，这些清除途径未完全定义，并且缺乏知识阻碍了疾病改良疗法的发展。这个目的应用是定义HSP70在控制降级降解的蛋白质质量控制决策中的作用全长Polyq AR。该应用的科学前提是HSP70通过基于HSP90/HSP70的机械和HSP70/HSP110脱聚集酶机械在通过蛋白酶体控制PolyQ AR降解。这个前提为我们的中心奠定了基础假设HSP70靶向策略将促进突变蛋白的泛素化和清除。这假设来自我们的初步数据，表明与HSP90的关联稳定了Polyq ar，突变蛋白的展开导致HSP70依赖性E3连接酶泛素化。而且，我们会的基于我们发表的研究，表明HSP70的变构调节以增加与错误折叠的蛋白质可增强细胞中Polyq AR的清除，并减轻果蝇模型中的毒性。拟议工作的理由是建立调节PolyQ AR降解的机制将确定可以利用用于开发新疗法的靶标。结构，生化，遗传并将使用药理学方法来表征HSP70-CHIP复合物与PolyQ AR的表征调节蛋白质分类（AIM 1），建立遗传和小分子变构调节剂的影响 SBMA模型中的HSP70（AIM 2），并确定Polyq AR表达对泛素 - 蛋白酶体的影响途径功能（AIM 3）。这些研究有望表征细胞的结构和功能调节PolyQ AR降解并提供支持治疗的概念证明数据的机械以靶向HSP70为中心的方法。由于该伴侣还调节了质量控制决策引起神经变性的其他突变蛋白的营业额，我们期望定义的方法这里将为治疗策略提供信息，这些策略适用于其他依赖年龄的神经系统疾病。