Opa1 Is Required for Proper Mitochondrial Metabolism in Early Development

Opa1 catalyzes fusion of inner mitochondrial membranes and formation of the cristae. OPA1 mutations in humans lead to autosomal dominant optic atrophy. OPA1 knockout mice lose viability around embryonic day 9 from unknown reasons, indicating that OPA1 is essential for embryonic development. Zebrafish are an attractive model for studying vertebrate development and have been used for many years to describe developmental events that are difficult or impractical to view in mammalian models. In this study, Opa1 was successfully depleted in zebrafish embryos using antisense morpholinos, which resulted in disrupted mitochondrial morphology. Phenotypically, these embryos exhibited abnormal blood circulation and heart defects, as well as small eyes and small pectoral fin buds. Additionally, startle response was reduced and locomotor activity was impaired. Furthermore, Opa1 depletion caused bioenergetic defects, without impairing mitochondrial efficiency. In response to mitochondrial dysfunction, a transient upregulation of the master regulator of mitochondrial biogenesis, pgc1a, was observed. These results not only reveal a new Opa1-associated phenotype in a vertebrate model system, but also further elucidates the absolute requirement of Opa1 for successful vertebrate development.视神经萎缩蛋白1（Opa1）可催化线粒体内膜的融合与线粒体嵴的形成。人类体内的OPA1突变可引发常染色体显性遗传性视神经萎缩。OPA1基因敲除小鼠会在胚胎发育第9天左右丧失生存能力，具体机制尚不明确，这表明Opa1对胚胎发育至关重要。斑马鱼是研究脊椎动物发育的理想模型，多年来被用于阐释哺乳动物模型中难以或不便直接观测的发育过程。本研究通过反义吗啉代寡核苷酸（antisense morpholinos）成功在斑马鱼胚胎中敲低了Opa1的表达，该操作导致线粒体形态出现显著紊乱。表型分析显示，这些胚胎出现血液循环异常、心脏发育缺陷，同时伴随小眼畸形与胸鳍芽发育不全。此外，其惊吓反应减弱，运动能力受损。进一步研究发现，Opa1敲低会引发生物能学缺陷，但并未影响线粒体的能量转换效率。在线粒体功能障碍的应激反应中，研究人员观察到线粒体生物发生的核心调控因子——过氧化物酶体增殖物激活受体γ辅激活因子1α（pgc1a）出现一过性上调。本研究结果不仅在脊椎动物模型体系中揭示了一种全新的Opa1相关表型，还进一步阐明了Opa1对脊椎动物正常发育的绝对必要性。