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: 8223928
• 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 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8223928
• 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. PUBLIC HEALTH RELEVANCE: This research seeks to use yeast as a model to understand the mechanistic basis for the cellular pathology of frontotemporal dementia linked to chromosome three (FTD3). In humans, FTD3 is a dominantly inherited neurodegenerative disorder, and the mutated gene responsible for the disease is structurally and functionally identical in yeast. This research is directly relevant to understanding the human disease because the cellular processes affected in the disease state are similarly affected in yeast.

描述（由申请人提供）：额颞痴呆（FTD）是第二大常见的早期神经退行性疾病，具有认知障碍，几乎一半的FTD病例被认为是家族性的。与3号染色体（FTD3）相关的FTD是常染色体显性占主导地位，并且与CHMP2B基因中的突变密切相关，该突变编码了传输-III（ESCRT-III）所需的内体分类复合物的亚基。在晚期内体时，ESCRT-III通过其组装过程催化膜分裂反应，而CHMP2B通过刺激ATPase促进ESCRT-III的ATPase来维持这种活性，从而补充了复杂组装重复的子圈的亚基的可用性。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的截断，从而消除了ATPase结合位点并同时消除了自身抑制区域。 CHMP2B表达的截断导致遗传抑制ESCRT-III膜分裂活性，但是这种功能障碍的机械基础尚不清楚，也不了解它如何导致晚期内体和自噬体的积累，这是FTDD333333的主要细胞病理学。这项研究的长期目的是使用酿酒酵母作为模型系统，了解FTD3晚期内体功能障碍的机理基础。中心假设是CHMP2B截断抑制了晚期内体和自噬体与溶酶体的融合，这通常会阻止这些细胞器积聚。这项研究将研究杂合二倍体酵母，其中CHMP2B基因直系同源物的一个副本以与FTD3折磨的大型丹麦亲戚同源的方式截断。要使用的方法包括蛋白质生物化学，定位研究，表达分析和功能测定，以研究FTD3截断如何影响ESCRT-III和调节溶酶体融合活性的机械。这项研究的基本原理是必须确定这些参数，以制定一种策略来定义关键蛋白质相互作用和特定的调节元素，将内溶性融合与ESCRT-III功能联系起来。使用酵母作为模型系统来理解这种关系与人类健康直接相关，因为内溶液融合和ESCRT-III功能的机制是高度保守的。关于预期的结果，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体和自噬体的积累。预计此类结果将产生重要的积极影响，因为它们将产生对内吞途径中的调节步骤不足的基本见解，揭示了预防和治疗FTD3的潜在靶标，并激发新的和创新的方法，以了解内体功能障碍的机制，以表征许多其他神经脱发性疾病的内体功能障碍。 公共卫生相关性：这项研究试图使用酵母作为模型来了解与第三染色体（FTD3）相关的额颞痴呆的细胞病理的机理基础。在人类中，FTD3是一种主要遗传的神经退行性疾病，负责该疾病的突变基因在酵母上在结构和功能上相同。这项研究与理解人类疾病直接相关，因为在疾病状态下受影响的细胞过程在酵母中类似地影响。