Institut für Medizinische Mikrobiologie, Universität Zürich, Zürich, Switzerland.
Anatomisches Institut, Universität Zürich, Zürich, Switzerland.
EMBO Rep. 2018 Nov;19(11). doi: 10.15252/embr.201846193. Epub 2018 Sep 20.
The 1555 A to G substitution in mitochondrial 12S A-site rRNA is associated with maternally transmitted deafness of variable penetrance in the absence of otherwise overt disease. Here, we recapitulate the suggested A1555G-mediated pathomechanism in an experimental model of mitoribosomal mistranslation by directed mutagenesis of mitoribosomal protein MRPS5. We first establish that the ratio of cysteine/methionine incorporation and read-through of mtDNA-encoded MT-CO1 protein constitute reliable measures of mitoribosomal misreading. Next, we demonstrate that human HEK293 cells expressing mutant V336Y MRPS5 show increased mitoribosomal mistranslation. As for immortalized lymphocytes of individuals with the pathogenic A1555G mutation, we find little changes in the transcriptome of mutant V336Y MRPS5 HEK cells, except for a coordinated upregulation of transcripts for cytoplasmic ribosomal proteins. Homozygous knock-in mutant V338Y mice show impaired mitochondrial function and a phenotype composed of enhanced susceptibility to noise-induced hearing damage and anxiety-related behavioral alterations. The experimental data in V338Y mutant mice point to a key role of mitochondrial translation and function in stress-related behavioral and physiological adaptations.
线粒体 12S A 位 rRNA 的 1555A 到 G 取代与母系遗传的听力损失有关，这种听力损失在没有其他明显疾病的情况下具有不同的外显率。在这里，我们通过定向突变线粒体核糖体蛋白 MRPS5，在翻译错误的线粒体核糖体模型中重现了提示的 A1555G 介导的发病机制。我们首先确定半胱氨酸/蛋氨酸掺入和 mtDNA 编码的 MT-CO1 蛋白通读的比例是线粒体核糖体错误阅读的可靠衡量标准。接下来，我们证明表达突变 V336Y MRPS5 的人 HEK293 细胞显示出增加的线粒体核糖体错误翻译。对于具有致病性 A1555G 突变的个体的永生化淋巴细胞，我们发现突变 V336Y MRPS5 HEK 细胞的转录组变化很小，除了细胞质核糖体蛋白的转录物协调上调。纯合敲入突变 V338Y 小鼠显示线粒体功能受损，以及由噪声诱导的听力损伤和焦虑相关行为改变的易感性增强组成的表型。V338Y 突变小鼠的实验数据表明线粒体翻译和功能在应激相关的行为和生理适应中起着关键作用。
