A somatic T15091C mutation in the Cytb gene of mouse mitochondrial DNA dominantly induces respiration defects.
A somatic T15091C mutation in the Cytb gene of mouse mitochondrial DNA dominantly induces respiration defects.
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小鼠线粒体 DNA Cytb 基因中的体细胞 T15091C 突变主要诱导呼吸缺陷。
DOI：
10.1016/j.bbrc.2015.06.052
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Hayashi JI
中科院分区：
文献类型：
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作者：
Hayashi C;Takibuchi G;Shimizu A;Mito T;Ishikawa K;Nakada K;Hayashi JI
我们以前的研究证明，导致线粒体呼吸缺陷的哺乳动物线粒体DNA(MtDNA)突变是以隐性方式表现的，因为在没有突变的情况下，可以通过一小部分(10%-20%)的mtDNA来防止呼吸缺陷的诱导。然而，随后的研究发现，通过加速积累具有各种体细胞突变的一小部分mtDNA而导致呼吸缺陷，这表明存在以显性方式表现的mtDNA突变。在这里，为了提供mtDNA存在显性突变的证据，我们使用小鼠肺癌P29细胞，并检查了一些mtDNA分子是否具有主要导致呼吸缺陷的体细胞突变。为了筛选蛋白质编码基因的体细胞突变，从P29细胞中克隆了40-48个mtDNA分子并进行了序列分析，因为这些基因的突变主要通过形成异常多肽来调节呼吸缺陷。我们发现在一个或多个40-48个mtDNA分子中存在108个错义突变。在这些错义突变中，Cytb基因的T15091C突变被认为是致病的，因为它在心肌病患者的mtDNA中存在同源突变。从亲本P29细胞中分离出多个亚克隆后，获得了不同比例的T15091C线粒体DNA亚克隆，其中一个亚克隆仅含有49%的T15091C线粒体DNA，可诱发呼吸缺陷。由于没有T15091C突变的剩余51%的mtDNA不能阻止呼吸缺陷的发生，因此，T15091C突变是导致呼吸缺陷的主要原因。
Our previous studies provided evidence that mammalian mitochondrial DNA (mtDNA) mutations that cause mitochondrial respiration defects behave in a recessive manner, because the induction of respiration defects could be prevented with the help of a small proportion (10%–20%) of mtDNA without the mutations. However, subsequent studies found the induction of respiration defects by the accelerated accumulation of a small proportion of mtDNA with various somatic mutations, indicating the presence of mtDNA mutations that behave in a dominant manner. Here, to provide the evidence for the presence of dominant mutations in mtDNA, we used mouse lung carcinoma P29 cells and examined whether some mtDNA molecules possess somatic mutations that dominantly induce respiration defects. Cloning and sequence analysis of 40–48 mtDNA molecules from P29 cells was carried out to screen for somatic mutations in protein-coding genes, because mutations in these genes could dominantly regulate respiration defects by formation of abnormal polypeptides. We found 108 missense mutations existing in one or more of 40–48 mtDNA molecules. Of these missense mutations, a T15091C mutation in theCytbgene was expected to be pathogenic due to the presence of its orthologous mutation in mtDNA from a patient with cardiomyopathy. After isolation of many subclones from parental P29 cells, we obtained subclones with various proportions of T15091C mtDNA, and showed that the respiration defects were induced in a subclone with only 49% T15091C mtDNA. Because the induction of respiration defects could not be prevented with the help of the remaining 51% mtDNA without the T15091C mutation, the results indicate that the T15091C mutation in mtDNA dominantly induced the respiration defects.