Defining the role of SUMOylation in spinobulbar muscular atrophy

定义 SUMO 化在脊髓延髓肌萎缩中的作用

• 批准号: 8202319
• 负责人: Jason Paul Chua
• 金额: $ 4.68万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8202319
• 关键词: Affect; Androgen Receptor; Behavioral; Cell model; Cell physiology; Cells; Data; Degenerative Disorder; Development; Disease; Gene Targeting; Glutamine; Goals; Hormones; Knock-in Mouse; Knowledge; Laboratories; Ligands; Limb structure; Mediating; Modification; Motor Neurons; Mus; Muscle Weakness; Mutation; Neurodegenerative Disorders; Pathogenesis; Pathology; Pathway interactions; Phenotype; Post-Translational Protein Processing; Proteins; Public Health; Quality Control; Receptor Gene; Resistance; Role; Signal Pathway; Skeletal Muscle; Spinobulbar Muscular Atrophy; Sumoylation Pathway; System; Testing; Therapeutic; Toxic effect; Ubiquitin; Ubiquitination; Work; design; disease phenotype; disease-causing mutation; in vivo; insight; men; motor neuron degeneration; mouse model; mutant; neuromuscular; new therapeutic target; polyglutamine; prevent; protective effect; protein aggregation; protein misfolding; protein protein interaction; therapeutic target; ubiquitin ligase

DESCRIPTION (provided by applicant): Spinobulbar muscular atrophy (SBMA) is a degenerative disorder of lower motor neurons caused by a CAG/glutamine expansion in the androgen receptor (AR) gene. The mutant protein (polyQ AR) undergoes hormone-dependent unfolding and oligomerization, steps that are critical to toxicity and to the development of progressive proximal limb and bulbar muscle weakness in men. Recent studies demonstrate that post- translational modifications of the AR triggered by ligand regulate toxicity. Specifically, conjugation of the polyQ AR by SUMO (small ubiquitin-like modifier) has been shown to impair ligand-dependent oligomerization of the mutant protein. However, the mechanism by which this occurs and the extent to which it alters the disease phenotype in vivo are currently unknown. The objective of this application is to determine how SUMOylation of the polyQ AR affects SBMA pathogenesis. The central hypothesis of this proposal is that SUMOylation promotes degradation of the polyQ AR and thereby limits accumulation of the misfolded protein and diminishes toxicity. This hypothesis springs from preliminary data demonstrating that SUMOylation decreases the levels of soluble AR oligomers in cellular models of SBMA. In Aim 1, the extent to which SUMO Targeted Ubiquitin Ligases (STUbLs) degrade the SUMOylated polyQ AR will be delineated. This will be accomplished by stably expressing wild type and non-SUMOylatable AR mutants in an inducible cell model of SBMA and characterizing SUMO-mediated effect on STUbL recruitment, AR ubiquitination and degradation, and cell toxicity. In Aim 2, the effects of SUMOylation will be characterized in a knock-in mouse model of SBMA. This will be accomplished by using gene targeting to generate SBMA knock-in mice that express a non- SUMOylatable polyQ AR. Analyses will then be performed to compare motor neuron degeneration and skeletal muscle pathology with that occurring in existing knock-in mice expressing a polyQ AR that is a target for SUMO. Successful completion of these aims is expected to define the mechanism underlying the protective effects of SUMO and allow for specific targeting of the SUMO pathway for therapeutic design. PUBLIC HEALTH RELEVANCE: The results of the proposed studies are expected to positively impact public health by defining the role of SUMO in protecting against motor neuron degeneration in spinobulbar muscular atrophy, thereby identifying potential therapeutic targets. As the mechanisms identified here are expected to regulate degradation of the androgen receptor (AR) at large, they will provide insights into the treatment of other AR-mediated diseases. Further, as several neurodegenerative disease-causing proteins are targeted by SUMO, these findings will serve as a paradigm for understanding how SUMOylation affects protein quality control and the phenotype of these related disorders.

描述（由申请人提供）： 脊髓延髓肌萎缩症（SBMA）是一种由雄激素受体（AR）基因CAG/谷氨酰胺扩增引起的下运动神经元退行性疾病。突变蛋白（polyQ AR）经历了蛋白依赖性解折叠和寡聚化，这些步骤对毒性和男性进行性近端肢体和延髓肌无力的发展至关重要。最近的研究表明，由配体触发的AR的翻译后修饰调节毒性。具体地，通过SUMO（小泛素样修饰物）缀合polyQ AR已显示损害突变蛋白的配体依赖性寡聚化。然而，这种情况发生的机制以及它在体内改变疾病表型的程度目前尚不清楚。本申请的目的是确定polyQ AR的SUMO化如何影响SBMA发病机制。该提议的中心假设是SUMO化促进polyQ AR的降解，从而限制错误折叠蛋白的积累并降低毒性。这一假设源于初步数据，表明SUMO化降低了SBMA细胞模型中可溶性AR寡聚体的水平。在目标1中，将描述SUMO靶向泛素连接酶（STUbL）降解SUMO化polyQ AR的程度。这将通过在SBMA的诱导型细胞模型中稳定表达野生型和不可SUMO化的AR突变体并表征SUMO介导的对STUbL募集、AR泛素化和降解以及细胞毒性的作用来实现。在目标2中，将在SBMA的敲入小鼠模型中表征SUMO化的作用。这将通过使用基因靶向产生表达不可SUMO化的polyQ AR的SBMA敲入小鼠来实现。然后将进行分析，将运动神经元变性和骨骼肌病理学与表达作为SUMO靶点的polyQ AR的现有基因敲入小鼠中发生的情况进行比较。这些目标的成功完成有望确定SUMO保护作用的机制，并允许针对SUMO通路进行治疗设计。 公共卫生相关性： 拟议研究的结果预计将通过定义SUMO在预防脊髓延髓肌萎缩症运动神经元变性中的作用，从而确定潜在的治疗靶点，对公共卫生产生积极影响。由于这里确定的机制预计将调节雄激素受体（AR）的降解，它们将为其他AR介导的疾病的治疗提供见解。此外，由于SUMO靶向了几种神经退行性疾病引起的蛋白质，这些发现将作为了解SUMO化如何影响蛋白质质量控制和这些相关疾病表型的范例。