A model for elimination of defective mitochondrial genomes

消除有缺陷的线粒体基因组的模型

• 批准号: 10266765
• 负责人: Joel H. Rothman
• 金额: $ 19.44万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA BARBARA
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-30 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10266765
• 关键词: Address; Adopted; Adult; Affect; Age; Aging; Animals; Apoptosis; Attenuated; Automobile Driving; Caenorhabditis elegans; Cell Nucleus; Cells; Cytoplasm; DNA; Defect; Development; Discrimination; Disease; Elements; Ensure; Environment; Epigenetic Process; Event; Excision; Experimental Models; Foundations; Generations; Genes; Genetic; Genetic Processes; Genome; Genomics; Genotype; Goals; Health; Heritability; Human; Individual; Intervention; Laboratory Animals; Lead; Learning; Location; Longevity; Mediating; Mitochondria; Mitochondrial Diseases; Modeling; Mothers; Mutation; Nerve Degeneration; Nuclear; Pathway interactions; Population; Positioning Attribute; Prevention; Process; Quality Control; Repression; Research; Role; Signal Transduction; System; Testing; Tissues; age related; heteroplasmy; male; mitochondrial genome; mutant; non-genetic; novel; offspring; prevent; synergism; transmission process

SUMMARY The major objective of the proposed research is to unveil mechanisms that eliminate defective mitochondrial genomes (mtDNA) through genetic and epigenetic processes. The heteroplasmic state of mtDNA in animal cells allows accumulation of defective mtDNAs with potential replicative advantage. Quality control systems function to remove such deleterious mitochondrial genomes. We found that the abundance of a large deletion-bearing mtDNA in C. elegans, uaDf5, that is normally stably maintained in a heteroplasmic state with wild-type mtDNA (WT-mtDNA) increases with adult age and that this increased burden is passed onto offspring of older mothers. This defective mtDNA is also elevated in mutants lacking either of two quality control systems: mitophagy (pink- 1(-)) or germline programmed cell death (PCD; ced-13(-)). Unexpectedly, however, we found that when both pink-1 and ced-13 functions are eliminated, the opposite occurs: uaDf5 is rapidly and completely removed, effectively curing the animal of mitochondrial disease. Even more startling, descendants of crosses between pink-1(-) or ced-13(-) single mutant mothers with males lacking both PINK-1 and CED-13 also show rapid removal of the deleted mtDNA, and this effect occurs irrespective of the differing descendant genotypes. These findings lead us to hypothesize that an initiating genetic event (IGE) from these crosses triggers a potent transgenerational epigenetic process that discriminates and effectively removes defective mtDNA. With these foundational findings, we will investigate the mechanisms of this striking mtDNA quality control process. In Aim 1, we will analyze the effect of the IGE-triggered removal of uaDf5 on its age-dependent accumulation and analyze its developmental timing. We will test whether the elimination process is general to other mtDNA deletions and assess the impact of size and sequence location on the removal process. We will investigate whether other components in the mitophagy and PCD pathways show synergy in activating removal and will test the hypothesis that enhanced mitochondrial fission may allow for discrimination and elimination of uaDf5. In Aim 2, we will analyze the basis for the apparently epigenetic transgenerational transmission of the mtDNA quality control process. We will evaluate the hypothesis that the dramatic amplification of WT-mtDNA that we found occurs prior to the generations in which uaDf5 is removed is required for the removal process and that uaDf5 is required to trigger this amplification. We will investigate whether the IGE antagonizes the mitochondrial UPR, which protects uaDf5 from removal. We will test the hypothesis that the IGE is triggered specifically by paternal loss of PINK-1 and CED-13. Finally, we will assess whether the IGE-activated epigenetic process is transmitted through the nucleus or cytoplasm/mitochondria. These studies will contribute to our understanding of how a healthy mitochondrial genome is maintained, a problem of premier importance to aging, neurodegeneration, and mitochondrial disease.

概括 拟议研究的主要目的是揭示消除线粒体缺陷的机制 基因组（mtDNA）通过遗传和表观遗传过程。动物细胞中mtDNA的杂质状态 允许积累具有潜在复制优势的有缺陷的mtDNA。质量控制系统功能 去除这种有害的线粒体基因组。我们发现大删除的丰度 秀丽隐杆线虫中的mtDNA，UADF5，通常稳定地保持在异质状态，野生型mtDNA （WT-MTDNA）随着成人年龄的增长而增加，这种增加的负担被传给了年长母亲的后代。 在缺乏两个质量控制系统的突变体中，这种缺陷的mtDNA也升高：线粒体（粉红色 - 1（ - ））或种系编程细胞死亡（PCD； CED-13（ - ））。但是，出乎意料的是，我们发现两者都 消除了粉红色1和CED-13功能，情况相反：UADF5迅速且完全去除， 有效治愈线粒体疾病的动物。更令人震惊的十字架后代 pink-1（ - ）或Ced-13（ - ）单身突变母亲，男性缺乏粉红色1和CED-13也显示出迅速 去除已删除的mtDNA，而这种效果发生在不同的后代基因型的情况下。这些 调查结果使我们假设从这些杂交中引发的遗传事件（IgE）触发了有效的 跨代表观遗传过程可区分并有效地消除了缺陷的mtDNA。与这些 基本发现，我们将研究这种引人注目的mtDNA质量控制过程的机制。目标 1，我们将分析IgE触发的去除UADF5对年龄依赖性积累的影响 分析其发育时机。我们将测试消除过程是否是其他mtDNA的一般 删除并评估大小和序列位置对去除过程的影响。我们将调查 线粒体和PCD途径中的其他组件是否在激活去除方面表现出协同作用，并将测试 增强线粒体裂变的假设可能允许歧视和消除UADF5。目标 2，我们将分析明显的表观遗传转世质量传播的基础 控制过程。我们将评估我们发现WT-MTDNA的戏剧性扩增的假设 发生在去除UADF5的几代之前发生，而UADF5是 触发这种扩增所需。我们将研究IgE是否拮抗线粒体UPR， 保护UADF5免于拆卸。我们将检验以下假设：IgE是由父亲专门触发的 粉红色1和CED-13的损失。最后，我们将评估IgE激活的表观遗传过程是否已传输 通过细胞核或细胞质/线粒体。这些研究将有助于我们理解 维持健康的线粒体基因组，对衰老，神经变性和 线粒体疾病。