Studies on pathogenesis and gene therapy using mice with the mutated mtDNA in tRNA genes

(1) Sato， A.等。Proc。国家的。学会科学。美国102:16765-16770。2005 . mtdna的致病性突变已被证明是导致呼吸缺陷和线粒体疾病表达的原因。本研究直接解决了利用反线粒体小鼠（mito-mice）受精卵核移植对线粒体疾病进行基因治疗的问题。mito小鼠表达呼吸缺陷和线粒体疾病，这是由于携带大规模缺失的mtDNA的积累（ΔmtDNA）。第二极体作为活检样本用于诊断有丝分裂小鼠受精卵的mtDNA基因型。核移植从有丝分裂小鼠受精卵到去核正常受精卵，并被证明在其一生中拯救所有F_0后代免于呼吸缺陷的表达。这一程序应适用于线粒体疾病患者，以防止其子女患上该疾病。(2) Sato， A.等。Proc。国家的。学会科学。更多美国102:6057-6062。关于重组mtdna能否在哺乳动物细胞中产生的问题多年来一直存在争议。我们通过分离人类体细胞杂交细胞和产生携带两种不同mtDNA单倍型的小鼠，展示了非常罕见的重组mtDNA单倍型产生的令人信服的证据。如此极低频率的mtDNA重组并不需要对基于其缺失的人类进化的重要概念进行任何修改。(3)李勤等。mtDNA变异在代际间的快速变化引发了瓶颈理论。一个长期以来被提出的普遍假设是，在卵子发生早期mtDNA含量的大量减少导致了瓶颈。为了验证这一点，我们估计mtDNA拷贝在整个发育阶段表现出一致和适度的mtDNA拷贝数，而初级卵母细胞在卵母细胞成熟早期表现出大量的mtDNA扩增。一些体细胞具有非常低的mtDNA拷贝数。我们还证明了PGCs每个细胞有超过100个线粒体。综上所述，我们得出的结论是，线粒体瓶颈不是由于卵子发生早期mtDNA拷贝数急剧下降而产生的，而是由于小鼠生殖细胞中mtDNA分离单元的有效数量较少。一些体细胞谱系在早期分化过程中有一个狭窄的瓶颈。这些结果为建立mtDNA分离模型和了解mtDNA疾病的复发风险提供了新的信息。少

(1) Sato, A. et al. Proc. Natl. Acad. Sci. USA 102: 16765-16770. 2005Pathogenic mutations in mtDNAs have been shown to be responsible for expression of respiration defects and resultant expression of mitochondrial diseases. This study directly addressed the issue of gene therapy of mitochondrial diseases using nuclear transplantation of zygotes of trans-mitochondria mice (mito-mice). Mito-mice expressed respiration defects and mitochondrial diseases due to accumulation of mtDNA carrying a large-scale deletion (ΔmtDNA). Second polar bodies were used as biopsy samples for diagnosis of mtDNA genotypes of mito-mouse zygotes. Nuclear transplantation was carried out from mito-mouse zygotes to enucleated normal zygotes, and was shown to rescue all the F_0 progenies from expression of respiration defects throughout their lives. This -procedure should be applicable to patients with mitochondrial diseases for preventing their children from the diseases.(2) Sato, A. et al. Proc. Natl. Acad. Sci. … More USA 102: 6057-6062. 2005The problem of whether recombinant mtDNAs are created in mammalian cells has been controversial for many years. We show convincing evidence for the very rare creation of recombinant mtDNA haplotypes by isolating human somatic hybrid cells and by generating mice carrying two different mtDNA haplotypes. Such an extremely low frequency of mtDNA recombination does not require any revision of important concepts on human evolution that are based on its absence.(3) Liqin, C., et al. Nature Genet. 39:386-390, 2007The observations of rapid shifts in mtDNA variants between generations have originated the bottleneck theory. A prevalent hypothesis which has long been proposed is that a massive reduction in mtDNA content during early oogenesis leads to the bottleneck. To test this we estimated the mtDNA copy single exhibited consistent and moderate mtDNA copy numbers across developmental stages, while primary oocytes demonstrated substantial mtDNA expansion during early oocyte maturation. Some somatic cells possess a very low mtDNA copy number. We also demonstrated that PGCs have more than 100 mitochondria per cell. Taken together, we conclude that the mitochondrial bottleneck is not generated due to a mtDNA copy number drastic decline in early oogenesis rather to a small effective number of segregation units for mtDNA in mouse germ cells. Some somatic cell lineages have a narrow bottleneck during early differentiation. These results provide new information for generating mtDNA segregation models and for understanding of recurrence risks for mtDNA diseases. Less