MITOCHONDRIAL DNA REARRANGEMENT IN NEUROMUSCULAR DISEASE

线粒体是细胞中能量的主要来源。 它们含有 它们自己的DNA（mtDNA），其基因编码呼吸系统的组成部分， 链/氧化磷酸化系统。 它们对于正常的 身体中所有细胞的功能，并且对于 这些组织的功能高度依赖于有氧代谢， 尤其是肌肉男和布莱恩。 自1988年以来，线粒体DNA点突变和 mtDNA重排（即大规模缺失[delta-mtDNA]和 重复[dup-mtDNAs]）与一个异质性群体有关， 线粒体脑肌病 这种持续的竞争 申请建议跟进本署现时资助的工作， 零星的mtDNA缺失，并扩大我们的努力，包括mtDNA 重复，这不仅与散发性疾病有关， 孟德尔遗传和母系遗传的疾病。 我们建议处理两个相关的问题。 首先，我们会研究 线粒体DNA重复与缺失的关系 线粒体疾病的发病机制。 我们将线粒体DNA 复制（dup-mtDNA）到无mtDNA的细胞（人无核细胞）， 产生含有不同比例的 双脱氧核糖核酸 将分析这些细胞的相关线粒体 功能特性，以便了解 表型和基因型。 我们还将尝试确定dup-mtDNA 与delta-mtDNA在体内共存，如果dup-mtDNA可以引起delta-mtDNA的缺失， 线粒体DNA 其次，我们将研究delta-mtDNA的遗传互补， 融合含有两个非重叠的 δ-mtDNA的同质群体，并选择其中 野生型功能已经恢复，可能是由于融合 线粒体和两个基因组之间的互补。 我们还建议建立一个delta-mtDNA疾病的小鼠模型， 小鼠胞质杂种克隆，其含有大比例的特定种类的 delta-mtDNA（来自老年小鼠，已知其积累低 水平）注射到受精的小鼠胚胎中。 的 建立一个“传递线粒体”小鼠模型的提议被认为是探索性的 在自然界中。 虽然这个想法充满了潜在的问题， 潜在的回报是巨大的，我们想把它作为一个辅助 我们工作的目标。

Mitochondria are the main sources of energy in the cell. They contain their own DNA (mtDNA), whose genes encode components of athe respiratory chain/oxidative phosphorylation system. They are essential for the normal functioning of all cells in the body, and are absolutely critical for the function of those tissues that are highly dependent on aerobic metabolism, especially muscle and brian. Since 1988, both mtDNA point mutations and mtDNA rearrangements (i.e. large-scale deletions [delta-mtDNAs] and duplications [dup-mtDNAs]) have been associated with a heterogeneous group of mitochondrial encephalomyopathies. This Continuing Competitive Application proposes to follow up on our currently-funded efforts on sporadic mtDNA deletions, and to expand our efforts to include mtDNA duplications, which are associated not only with sporadic disorders, but with mendelian- and maternally-inherited disorders as well. We propose to address two related issues. First, we will study the relationship between mtDNA duplications and mtDNA deletions in the pathogenesis of mitochondrial diseases. We will transfer mtDNA duplications (dup-mtDNAs) to mtDNA-less cells (human pomicron cells) and create cytoplasmic hybrid (cybrid) lines harboring different proportions of dup-mtDNAs. These cells will be analyzed for relevant mitochondrial functional characteristics in order to understand athe relationship between phenotype and genotype. We will also try to determine if dup-mtDNAs coexist with delta-mtDNAs in vivo and if dup-mtDNAs can give rise to delta- mtDNAs. Second, we will study genetic complementation of delta-mtDNAs, by fusing two respiratory-deficient cybrids containing two non-overlapping homoplasmic populations of delta-mtDNAs,a nd selecting for cells in which wild-type function has been restored, due presumably to fusion of mitochondria and to complementation between the two genomes. We also propose to create a mouse model of delta-mtDNA diseases, by using mouse cybrid clones harboring a large proportion of a specific species of delta-mtDNA (derived from aged mice, which are known to accumulate low levels of delta-mtDNAs) for injection into fertilized mouse embryos. The proposal to create a "transmitochondrial" mouse model is deemed exploratory in nature. Although this idea is fraught with potential problems, the potential payoff is great, and we would like to include it as an ancillary aim of our work.