Mitophagy-driven selection against heteroplasmic mitochondrial DNA mutations

线粒体自噬驱动的针对异质线粒体 DNA 突变的选择

• 批准号: 8323862
• 负责人: DAVID K. SIMON
• 金额: $ 21.75万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 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/8323862
• 关键词: Age; Aging; Attenuated; Autophagocytosis; Behavioral; Blood - brain barrier anatomy; Brain; Cardiac; Cardiomyopathies; Cell Line; Cell physiology; Cells; Chronic; Clinical Treatment; Clinical Trials; Cognitive deficits; Complex; DNA; DNA Fingerprinting; DNA-Directed DNA Polymerase; Data; Defect; Disease; Dose; FDA approved; Family; Functional disorder; Gene Mutation; Genome; Hereditary Disease; Heredity; Human; Impairment; Inherited; Laboratories; Lead; Longevity; Metabolic; Mitochondria; Mitochondrial DNA; Mitochondrial Diseases; Mus; Mutation; Myopathy; Neurodegenerative Disorders; Neurologic; Non-Insulin-Dependent Diabetes Mellitus; Oral; Oxidative Stress; Parkinson Disease; Parkinsonian Disorders; Patients; Phenotype; Phosphotransferases; Premature aging syndrome; Process; Resistance; Resources; Role; Safety; Seizures; Sirolimus; Stroke; Testing; Therapeutic; Time; Tissues; Translations; Work; age related; cancer therapy; cell motility; clinical application; effective therapy; fly; gene therapy; high risk; human FRAP1 protein; kinase inhibitor; member; mitochondrial DNA mutation; mitochondrial genome; mutant; neurochemistry; novel; novel strategies; optic nerve disorder

DESCRIPTION (provided by applicant): Disorders caused by maternally inherited pathogenic mitochondrial DNA (mtDNA) mutations can lead to a wide array of neurological, cardiac, and other disorders. Unfortunately, clearly effective clinical treatments for these often devastating disorders are lacking. An ideal strategy would eliminate the mutant mtDNA and replace it with wild type (WT) DNA. However, classic "gene therapy" approaches are difficult to apply to mtDNA mutations. On the other hand, mitochondria undergo frequent turnover (every few days), even in postmitotic cells, with only a subset of copies of the mitochondrial genome being replicated during this process, providing an opportunity to influence which mtDNA molecules are replicated. We now propose to test a novel strategy to promote the selective elimination of deleterious mtDNA mutations that can be applied to heteroplasmic mtDNA mutations. Heteroplasmy is a common feature of pathogenic mtDNA mutations, and refers to a mix of WT and mutant mtDNA within the same cells or tissue. Our hypothesis takes advantage of a natural cellular process known as "mitophagy" (mitochondrial degradation by autophagy), which is a mechanism for selectively eliminating dysfunctional mitochondria. We hypothesize that some mitochondria within a cell will harbor greater levels of a heteroplasmic mtDNA mutation than others. Those with greater levels of a deleterious mutation will tend to have relatively greater impairment of mitochondrial function. Therefore, we propose to test the novel hypothesize that stimulating mitophagy by inhibiting mTOR kinase activity in cells harboring a heteroplasmic pathogenic mtDNA mutation will drive selection against the mutant mtDNA, over time leading to a substantial reduction in the mutational burden and hence an improvement in mitochondrial function. We have a unique resource available for testing this hypothesis: multiple SH-SY5Y cybrid cell lines harboring different levels of a heteroplasmic G11778A complex I (CI) gene mutation associated with Leber's Heredity Optic Neuropathy (LHON), all prepared at the same time from members of a single family. Our preliminary data with these cell lines support our hypothesis. A second important resource in our laboratory is the "mutator" mouse that expresses a proofreading deficient mtDNA polymerase 3 (Polg) leading to accumulation with age of heteroplasmic somatic mtDNA mutations in association with a premature aging phenotype. Our preliminary data demonstrate substantial metabolic, behavioral, and neurochemical deficits in these mice. We now hypothesize that enhancing mitophagy in the Polg mutator mice will attenuate the accumulation of somatic mtDNA mutations and ameliorate the deficits in these mice. Ultimately, clinical applications of this strategy have the potential to be of benefit to patients with classic mitochondrial disorders associated with heteroplasmic mtDNA mutations, to families harboring Polg mutations associated with familial parkinsonism and other disorders, and potentially for age-related neurodegenerative disorders.

描述（由申请人提供）：由母系遗传的致病性线粒体 DNA (mtDNA) 突变引起的疾病可导致多种神经、心脏和其他疾病。不幸的是，对于这些往往具有破坏性的疾病，缺乏明显有效的临床治疗方法。理想的策略是消除突变 mtDNA，并用野生型 (WT) DNA 替代。然而，经典的“基因治疗”方法很难应用于线粒体DNA突变。另一方面，即使在有丝分裂后细胞中，线粒体也经历频繁的周转（每隔几天），在此过程中仅复制线粒体基因组的一部分副本，从而提供了影响哪些 mtDNA 分子复制的机会。我们现在建议测试一种新策略，以促进选择性消除有害 mtDNA 突变，该策略可应用于异质性 mtDNA 突变。异质性是致病性线粒体DNA突变的一个共同特征，是指同一细胞或组织内野生型和突变型线粒体DNA的混合。我们的假设利用了一种称为“线粒体自噬”（线粒体自噬降解）的自然细胞过程，这是一种选择性消除功能失调的线粒体的机制。我们假设细胞内的某些线粒体比其他线粒体具有更高水平的异质 mtDNA 突变。那些有害突变水平较高的人往往会受到相对较大的线粒体功能损害。因此，我们建议测试新的假设，即通过抑制含有异质致病性 mtDNA 突变的细胞中的 mTOR 激酶活性来刺激线粒体自噬，将驱动针对突变 mtDNA 的选择，随着时间的推移，导致突变负担大幅减少，从而改善线粒体功能。功能。我们有一个独特的资源可用于检验这一假设：多个 SH-SY5Y 细胞杂种细胞系，含有不同水平的与莱伯遗传性视神经病 (LHON) 相关的异质性 G11778A 复合物 I (CI) 基因突变，所有这些细胞系均由成员同时制备一个单身家庭的。我们对这些细胞系的初步数据支持我们的假设。我们实验室的第二个重要资源是“突变”小鼠，它表达校对缺陷的 mtDNA 聚合酶 3 (Polg)，导致异质体细胞 mtDNA 突变随着年龄的增长而积累，与过早衰老表型相关。我们的初步数据表明这些小鼠存在严重的代谢、行为和神经化学缺陷。我们现在假设增强 Polg 突变小鼠的线粒体自噬将减弱体细胞 mtDNA 突变的积累并改善这些小鼠的缺陷。最终，该策略的临床应用可能对患有与异质 mtDNA 突变相关的经典线粒体疾病的患者、携带与家族性帕金森病和其他疾病相关的 Polg 突变的家庭以及与年龄相关的神经退行性疾病有潜在的益处。

项目成果

Rapamycin drives selection against a pathogenic heteroplasmic mitochondrial DNA mutation.

雷帕霉素驱动针对致病性异质线粒体 DNA 突变的选择。

• 发表时间: 2014-02-01
• 影响因子: 3.5
• 作者: Dai, Ying;Zheng, Kangni;Clark, Joanne;Swerdlow, Russell H;Pulst, Stefan M;Sutton, James P;Shinobu, Leslie A;Simon, David K
• 通讯作者: Simon, David K