Mechanistic basis for endosomal dysfunction in frontotemporal dementia linked to

额颞叶痴呆内体功能障碍的机制基础

• 批准号: 8320089
• 负责人: CHARLES G ODORIZZI
• 金额: $ 7.63万
• 依托单位: UNIVERSITY OF COLORADO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8320089
• 关键词: ATP phosphohydrolase; Affect; Alleles; Autophagosome; Binding Sites; Biological Assay; Biological Models; Cell physiology; Chromosomes; Chromosomes, Human, Pair 3; Code; Complex; Cultured Cells; Data; Diploidy; Disease; Dominant Genetic Conditions; Ectopic Expression; Frontotemporal Dementia; Functional disorder; Genes; Genomics; Goals; Health; Human; Impaired cognition; Inherited; Link; Longitudinal Studies; Lysosomes; Membrane; Membrane Fusion; Methodology; Modeling; Molecular Profiling; Mutate; Mutation; Nature; Neurodegenerative Disorders; Organelles; Orthologous Gene; Outcome; Pathway interactions; Patients; Point Mutation; Prevention; Process; Protein Biochemistry; Proteins; Reaction; Regulatory Element; Research; Saccharomyces cerevisiae; Saccharomycetales; Sorting - Cell Movement; Testing; Vesicle; Work; Yeasts; base; cellular pathology; design; early onset; human disease; innovation; insight; kindred; late endosome; mutant; prevent; rab GTP-Binding Proteins

DESCRIPTION (provided by applicant): Frontotemporal dementia (FTD) is the second most common early-onset neurodegenerative disease with cognitive impairment, and almost one half of FTD cases are thought to be familial. FTD linked to chromosome 3 (FTD3) is autosomal dominant and strongly linked to mutations in the CHMP2B gene, which encodes a subunit of the endosomal sorting complex required for transport-III (ESCRT-III). At late endosomes, ESCRT-III catalyzes membrane scission reactions through its assembly process, and CHMP2B sustains this activity by stimulating the ATPase that catalyzes disassembly of ESCRT-III, thereby replenishing the availability of subunits for repeated rounds of complex assembly. In FTD3 patients, point-mutation of one genomic CHMP2B locus results in truncation of its coding sequence, which eliminates the ATPase-binding site and simultaneously removes an autoinhibitory region. Truncated CHMP2B expression results in genetic-dominant inhibition of ESCRT-III membrane scission activity, but the mechanistic basis for this dysfunction is unknown, nor is it understood how it results in the accumulation of late endosomes and autophagosomes, which is the predominant cellular pathology in FTD3. The long-term objective of this research is to understanding the mechanistic basis for late endosomal dysfunction in FTD3 using the budding yeast Saccharomyces cerevisiae as a model system. The central hypothesis is that CHMP2B truncation inhibits the fusion of late endosomes and autophagosomes with lysosomes, which normally prevents these organelles from accumulating. This research will study heterozygous diploid yeast in which one copy of the CHMP2B gene ortholog is truncated in a manner homologous to that described in a large Danish kindred afflicted with FTD3. The methodology to be used includes protein biochemistry, localization studies, expression profiling, and functional assays to study how the FTD3 truncation affects ESCRT-III and the machinery that regulates lysosomal fusion activity. The rationale for this research is that these parameters must be determined in order to develop a strategy for defining the critical protein interactions and specific regulatory elements that link endolysosomal fusion to ESCRT-III function. Using yeast as a model system to understand this relationship is directly relevant to human health because the mechanisms of endolysosomal fusion and ESCRT-III function are highly conserved. With respect to expected outcomes, it is anticipated that completion of this research will reveal the nature of ESCRT-III dysfunction in FTD3 and how it results in accumulation of late endosomes and autophagosomes. Such results are expected to have an important positive impact because they will yield fundamental insight into a poorly understood regulatory step in the endocytic pathway, reveal potential targets for the prevention and treatment of FTD3, and inspire new and innovative approaches to understand the mechanisms of endosomal dysfunction that characterize many other neurodegenerative diseases.

描述(申请人提供)：额颞性痴呆(FTD)是第二种最常见的早发性神经退行性疾病，伴有认知障碍，几乎一半的FTD病例被认为是家族性的。与3号染色体连锁的FTD(FTD3)是常染色体显性的，并与CHMP2B基因的突变密切相关，CHMP2B基因编码运输所需的内体分选复合体的一个亚单位(ESCRT-III)。在内体晚期，ESCRT-III通过其组装过程催化膜断裂反应，CHMP2B通过刺激催化ESCRT-III分解的ATPase来维持这一活性，从而补充亚基的可用性，用于重复几轮复杂的组装。在FTD3患者中，一个基因组CHMP2B基因座的点突变导致其编码序列截断，从而消除了ATPase结合部位，同时去除了一个自身抑制区。CHMP2B的表达被截断会导致ESCRT-III膜断裂活性的遗传显性抑制，但这种功能障碍的机制尚不清楚，也不清楚它是如何导致晚期内噬小体和自噬小体积累的，这是FTD3的主要细胞病理。这项研究的长期目标是以发芽酵母酿酒酵母为模型系统，了解FTD3中晚期内体功能障碍的机制基础。核心假设是，CHMP2B截断抑制了晚期内噬体和自噬小体与溶酶体的融合，这通常会阻止这些细胞器的积累。这项研究将研究杂合二倍体酵母，其中CHMP2B基因同源基因的一个拷贝被截断，其方式与一个患有FTD3的丹麦大家族中所描述的方式相同。将使用的方法包括蛋白质生物化学、定位研究、表达谱和功能分析，以研究FTD3截断如何影响ESCRT-III和调节溶酶体融合活性的机制。这项研究的基本原理是，必须确定这些参数，以便制定一种策略，以定义将内溶酶体融合与ESCRT-III功能联系起来的关键蛋白质相互作用和特定调控元件。使用酵母作为模型系统来理解这种关系直接关系到人类健康，因为内溶体融合和ESCRT-III功能的机制是高度保守的。关于预期结果，预计这项研究的完成将揭示FTD3中ESCRT-III功能障碍的性质，以及它如何导致晚期内噬体和自噬体积聚。这些结果有望产生重要的积极影响，因为它们将从根本上洞察内吞途径中一个知之甚少的调控步骤，揭示预防和治疗FTD3的潜在靶点，并启发新的创新方法来理解内体功能障碍的机制，这些机制是许多其他神经退行性疾病的特征。