Tissue-specific splicing of an Ndufs6 gene-trap insertion generates a mitochondrial complex I deficiency-specific cardiomyopathy
Tissue-specific splicing of an Ndufs6 gene-trap insertion generates a mitochondrial complex I deficiency-specific cardiomyopathy
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DOI：
10.1073/pnas.1113987109
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发表时间：
2012-04-17
影响因子：
11.1
通讯作者：
Thorburn, David R.
中科院分区：
文献类型：
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作者：
Ke, Bi-Xia;Pepe, Salvatore;Thorburn, David R.
线粒体复合体I （CI）缺乏症是人类最常见的线粒体酶缺陷。线粒体疾病的治疗目前是不足的，强调需要实验模型。在人类中，编码CI亚基的NDUFS6基因突变可导致严重的CI缺乏和新生儿死亡。在这项研究中，我们利用基因诱捕胚胎干细胞系，通过敲低Ndufs6基因，建立了一个CI缺陷小鼠模型。Ndufs6（gt/gt）小鼠在心脏中基本完全敲除Ndufs6亚基，导致明显的CI缺乏。少量野生型Ndufs6 mRNA存在于其他组织中，显然是由于组织特异性mRNA剪接，导致较轻的CI缺陷。Ndufs6（gt/gt）小鼠出生健康，达到正常体重和成熟，并具有生育能力。然而，在雄性4个月和雌性8个月后，nduf56 （gt/gt）小鼠心力衰竭和死亡的风险增加。在明显的心力衰竭之前，Ndufs6（gt/gt）心脏显示ATP合成减少，羟酰基肉碱积累，但没有活性氧（ROS）。Ndufs6（gt/gt）小鼠在1个月时出现双心室增大，在雄性中最为明显，伴有分散的纤维化和线粒体异常，但肌纤维超微结构正常。Ndufs6（gt/gt）离体工作心脏制剂显示左心室收缩功能、心输出量和功能性工作能力明显降低。这种能量和功能能力的降低与线粒体心肌病患者对应激引起的代谢危机的已知易感性是一致的。这种CI缺乏模型将有助于研究发病机制、修饰基因和治疗方法的测试。
Mitochondrial complex I (CI) deficiency is the most common mitochondrial enzyme defect in humans. Treatment of mitochondrial disorders is currently inadequate, emphasizing the need for experimental models. In humans, mutations in the NDUFS6 gene, encoding a CI subunit, cause severe CI deficiency and neonatal death. In this study, we generated a CI deficient mouse model by knockdown of the Ndufs6 gene using a gene-trap embryonic stem cell line. Ndufs6(gt/gt) mice have essentially complete knockout of the Ndufs6 subunit in heart, resulting in marked CI deficiency. Small amounts of wild-type Ndufs6 mRNA are present in other tissues, apparently due to tissue-specific mRNA splicing, resulting in milder CI defects. Ndufs6(gt/gt) mice are born healthy, attain normal weight and maturity, and are fertile. However, after 4 mo in males and 8 mo in females, Ndufs6(gt/gt) mice are at increased risk of cardiac failure and death. Before overt heart failure, Ndufs6(gt/gt) hearts show decreased ATP synthesis, accumulation of hydroxyacylcarnitine, but not reactive oxygen species (ROS). Ndufs6(gt/gt) mice develop biventricular enlargement by 1 mo, most pronounced in males, with scattered fibrosis and abnormal mitochondrial but normal myofibrillar ultrastructure. Ndufs6(gt/gt) isolated working heart preparations show markedly reduced left ventricular systolic function, cardiac output, and functional work capacity. This reduced energetic and functional capacity is consistent with a known susceptibility of individuals with mitochondrial cardiomyopathy to metabolic crises precipitated by stresses. This model of CI deficiency will facilitate studies of pathogenesis, modifier genes, and testing of therapeutic approaches.