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（申请人提供）：额颞叶痴呆（FTD）是第二常见的认知障碍早发性神经退行性疾病，几乎一半的FTD病例被认为是家族性的。与3号染色体相关的FTD （FTD3）是常染色体显性的，与CHMP2B基因突变密切相关，CHMP2B基因编码转运- iii （ESCRT-III）所需的内体分选复合体的一个亚基。在核内体晚期，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拆卸的atp酶来维持这一活性，从而补充亚基的可用性，用于复合体的反复组装。在FTD3患者中，一个基因组CHMP2B位点的点突变导致其编码序列的截断，从而消除了atp酶结合位点，同时消除了一个自身抑制区域。截断的CHMP2B表达导致ESCRT-III膜断裂活性的遗传显性抑制，但这种功能障碍的机制基础尚不清楚，也不清楚它如何导致晚期内体和自噬体的积累，这是FTD3的主要细胞病理。本研究的长期目标是利用出芽酵母酿酒酵母作为模型系统，了解FTD3晚期内体功能障碍的机制基础。中心假设是CHMP2B截断抑制了晚期核内体和自噬体与溶酶体的融合，这通常会阻止这些细胞器的积累。本研究将研究杂合二倍体酵母，其中CHMP2B基因同源物的一个拷贝被截断，其方式与在患有FTD3的大型丹麦亲属中描述的相同。使用的方法包括蛋白质生物化学、定位研究、表达谱分析和功能分析，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，以确定将内溶酶体融合与ESCRT-III功能联系起来的关键蛋白质相互作用和特定调节元件。利用酵母作为模型系统来了解这种关系与人类健康直接相关，因为内溶酶体融合和ESCRT-III功能的机制是高度保守的。关于预期结果，预计本研究的完成将揭示FTD3中ESCRT-III功能障碍的性质及其如何导致晚期内体和自噬体的积累。这些结果有望产生重要的积极影响，因为它们将对内吞途径中一个鲜为人知的调控步骤产生根本性的见解，揭示FTD3预防和治疗的潜在靶点，并激发新的和创新的方法来理解许多其他神经退行性疾病特征的内体功能障碍机制。