Alfy-mediated selective macroautophagy and the pathogenesis of Huntington???s Dis

Alfy 介导的选择性巨自噬和亨廷顿舞蹈症的发病机制

• 批准号: 8647622
• 负责人: Leora Mestel Fox
• 金额: $ 3.82万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8647622
• 关键词: Adaptor Signaling Protein; Address; Adult; Affect; Aging; Alleles; Animal Model; Automobile Driving; Autophagocytosis; Behavioral; Biochemical; Biological Models; Brain; Cell Count; Cell model; Cells; Cessation of life; Clinical; Corpus striatum structure; Deposition; Development; Disease; Doxycycline; Drosophila genus; Drug Targeting; Dyskinetic syndrome; Epitopes; Event; Excision; Exhibits; Exons; Functional disorder; Genes; Genetic; Huntington Disease; Huntington gene; Immunohistochemistry; Impaired cognition; Inherited; Intervention; Knockout Mice; Light; Link; Lysosomes; Mediating; Mediator of activation protein; Membrane; Methods; Modeling; Molecular; Molecular Target; Motor; Mus; Mutation; Nerve Degeneration; Neurodegenerative Disorders; Neurons; Outcome; Pathogenesis; Pathology; Pathway interactions; Patients; Phenotype; Process; Proteins; Recovery; Role; Small Interfering RNA; Source; Staining method; Stains; Starvation; Symptoms; Tamoxifen; Testing; Tetracyclines; Toxic effect; Transgenes; Transgenic Mice; Trinucleotide Repeat Expansion; Ubiquitin; aging brain; behavior test; cellular pathology; genetic manipulation; human Huntingtin protein; in vivo; insight; motor control; motor deficit; mouse model; mutant; nervous system disorder; neuropathology; overexpression; polyglutamine; protein aggregate; protein degradation; public health relevance; research study; response; therapeutic development

DESCRIPTION (provided by applicant): Huntington's disease (HD) is a neurodegenerative disorder arising from an inherited CAG expansion mutation within the HD gene, resulting in mutant huntingtin (Htt) protein containing an expanded polyglutamine (polyQ) tract. Degeneration of the striatum causes patients to suffer from progressive loss of voluntary motor control, psychiatric disturbances, and debilitating cognitive decline. A pathological hallmark of HD is the accumulation of mutant Htt and ubiquitin in intracellular deposits throughout the brain. The link between Htt aggregates and disease symptoms remains unclear, but improvements in both cellular and behavioral pathology have been observed in studies that silence the Htt transgene. In an inducible HD mouse model, transgene silencing leads to the elimination of aggregates in conjunction with amelioration of motor deficits. These findings imply that aggregate removal has the potential to alleviate the underlying cellular dysfunction associated with HD. Understanding the molecular mechanisms by which neurons dispose of aggregated proteins is a critical step towards the development of therapeutics for a variety of neurodegenerative disorders. Cellular model systems have suggested that Htt aggregates are broken down by a degradation process known as macroautophagy, in which cytosolic proteins are sequestered into a double-membrane structure that fuses with a lysosome to degrade its cargo. The macroautophagic machinery comprises a core group of autophagy-related proteins, such as Atg5, Atg7, and LC3. While this process was initially found to degrade proteins in bulk in response to starvation, it can also occur selectively for particular substrates. Our lab has identified a protein called Alfy (autophagy-linked FYVE protein) that mediates selective macroautophagy of aggregated proteins. In cells expressing mutant Htt, Alfy is essential for the clearance of aggregates. Additionally, overexpression of c-terminal Alfy decreases inclusions and protects against neurodegeneration in drosophila and primary neuronal models of polyQ expansion. This proposal seeks to address the role of Alfy-mediated selective macroautophagy in aging brain and in HD. Eliminating core macroautophagic proteins such as Atg7 from developing brain results in neurodegeneration and protein accumulation, but the role of selective and nonselective macroautophagy during aging remains largely unexplored in vivo. This project will examine this by eliminating Alfy or Atg7 in aging mice using a tamoxifen-inducible Cre to drive excision of a conditional allele (Aim 1). This will provide insight into the importance of macroautophagy in aging brain. Furthermore, this project will investigate Alfy- mediated macroautophagy of Htt aggregates in vivo, by eliminating Alfy in an inducible HD mouse model (Aim 2). This will address how removal of Alfy affects clearance of mutant Htt, and whether disease reversal is dependent upon clearance of aggregates.

描述（由申请人提供）：亨廷顿病（HD）是一种神经退行性疾病，由HD基因内的遗传性CAG扩增突变引起，导致突变亨廷顿（Htt）蛋白含有扩增的多聚谷氨酰胺（polyQ）道。纹状体的退化导致患者遭受自愿运动控制的进行性丧失、精神障碍和使人衰弱的认知下降。HD的病理学标志是突变型Htt和泛素在整个脑的细胞内沉积物中的积累。Htt聚集体和疾病症状之间的联系尚不清楚，但在沉默Htt转基因的研究中已经观察到细胞和行为病理学的改善。在诱导型HD小鼠模型中，转基因沉默导致聚集体的消除以及运动缺陷的改善。这些发现意味着，聚集体的清除有可能减轻与HD相关的潜在细胞功能障碍。了解神经元处理聚集蛋白的分子机制是开发各种神经退行性疾病治疗方法的关键一步。 细胞模型系统已经表明，Htt聚集体通过称为大自噬的降解过程被分解，其中胞质蛋白被隔离成与溶酶体融合以降解其货物的双膜结构。巨自噬机制包括一组核心的自噬相关蛋白，如Atg 5、Atg 7和LC 3。虽然这个过程最初被发现在饥饿时大量降解蛋白质，但它也可以选择性地发生在特定的底物上。我们的实验室已经确定了一种名为Alfy（自噬相关FYVE蛋白）的蛋白质，它介导聚集蛋白的选择性大自噬。在表达突变体Htt的细胞中，Alfy对于聚集体的清除至关重要。此外，c-末端Alfy的过表达减少了果蝇和polyQ扩增的原代神经元模型中的包涵体并防止神经变性。 该提案旨在解决Alfy介导的选择性巨自噬在衰老大脑和HD中的作用。从发育中的大脑中消除核心大自噬蛋白（如Atg 7）会导致神经退行性变和蛋白质积累，但选择性和非选择性大自噬在衰老过程中的作用在很大程度上尚未在体内探索。该项目将通过使用他莫昔芬诱导的Cre消除衰老小鼠中的Alfy或Atg 7来检测这一点，以驱动条件等位基因的切除（Aim 1）。这将提供深入了解 大自噬在衰老大脑中的重要性。此外，该项目将通过在诱导型HD小鼠模型中消除Alfy来研究体内Alfy介导的Htt聚集体的大自噬（Aim 2）。这将解决Alfy的去除如何影响突变体Htt的清除，以及疾病逆转是否依赖于聚集体的清除。