BACKGROUND:Hypertrophic cardiomyopathy (HCM) is a common heritable heart disease. Although HCM has been reported to be associated with many variants of genes involved in sarcomeric protein biomechanics, pathogenic genes have not been identified in patients with partial HCM. FARS2 (the mitochondrial phenylalanyl-tRNA synthetase), a type of mitochondrial aminoacyl-tRNA synthetase, plays a role in the mitochondrial translation machinery. Several variants of FARS2 have been suggested to cause neurological disorders; however, FARS2-associated diseases involving other organs have not been reported. We identified FARS2 as a potential novel pathogenic gene in cardiomyopathy and investigated its effects on mitochondrial homeostasis and the cardiomyopathy phenotype.METHODS:FARS2 variants in patients with HCM were identified using whole-exome sequencing, Sanger sequencing, molecular docking analyses, and cell model investigation. Fars2 conditional mutant (p.R415L) or knockout mice, fars2-knockdown zebrafish, and Fars2-knockdown neonatal rat ventricular myocytes were engineered to construct FARS2 deficiency models both in vivo and in vitro. The effects of FARS2 and its role in mitochondrial homeostasis were subsequently evaluated using RNA sequencing and mitochondrial functional analyses. Myocardial tissues from patients were used for further verification.RESULTS:We identified 7 unreported FARS2 variants in patients with HCM. Heart-specific Fars2-deficient mice presented cardiac hypertrophy, left ventricular dilation, progressive heart failure accompanied by myocardial and mitochondrial dysfunction, and a short life span. Heterozygous cardiac-specific Fars2^R415L mice displayed a tendency to cardiac hypertrophy at age 4 weeks, accompanied by myocardial dysfunction. In addition, fars2-knockdown zebrafish presented pericardial edema and heart failure. FARS2 deficiency impaired mitochondrial homeostasis by directly blocking the aminoacylation of mt-tRNA^Phe and inhibiting the synthesis of mitochondrial proteins, ultimately contributing to an imbalanced mitochondrial quality control system by accelerating mitochondrial hyperfragmentation and disrupting mitochondrion-related autophagy. Interfering with the mitochondrial quality control system using adeno-associated virus 9 or specific inhibitors mitigated the cardiac and mitochondrial dysfunction triggered by FARS2 deficiency by restoring mitochondrial homeostasis.CONCLUSIONS:Our findings unveil the previously unrecognized role of FARS2 in heart and mitochondrial homeostasis. This study may provide new insights into the molecular diagnosis and prevention of heritable cardiomyopathy as well as therapeutic options for FARS2-associated cardiomyopathy.

中文翻译：

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FARS2 缺陷通过破坏线粒体稳态和线粒体质量控制系统导致心肌病

背景：肥厚型心肌病（HCM）是一种常见的遗传性心脏病。尽管据报道 HCM 与肌节蛋白生物力学中涉及的许多基因变异有关，但尚未在部分 HCM 患者中鉴定出致病基因。 FARS2（线粒体苯丙氨酰-tRNA 合成酶）是一种线粒体氨酰-tRNA 合成酶，在线粒体翻译机制中发挥作用。FARS2的几种变体已被认为会导致神经系统疾病；然而，涉及其他器官的FARS2相关疾病尚未见报道。我们将FARS2确定为心肌病中潜在的新型致病基因，并研究了其对线粒体稳态和心肌病表型的影响。方法：通过全外显子组测序、Sanger 测序、分子对接分析和细胞模型研究来鉴定 HCM 患者的FARS2变异。 。Fars2条件突变体（p.R415L）或基因敲除小鼠、fars2敲低斑马鱼和Fars2敲低新生大鼠心室肌细胞被设计用于构建体内和体外FARS2缺陷模型。随后使用 RNA 测序和线粒体功能分析评估了 FARS2 的影响及其在线粒体稳态中的作用。使用患者的心肌组织进行进一步验证。结果：我们在 HCM 患者中发现了 7 个未报告的FARS2变异。心脏特异性Fars2缺陷小鼠表现出心脏肥大、左心室扩张、进行性心力衰竭并伴有心肌和线粒体功能障碍，并且寿命较短。杂合心脏特异性Fars2 ^R415L小鼠在 4 周龄时表现出心脏肥大的倾向，并伴有心肌功能障碍。此外，fars2敲低斑马鱼出现心包水肿和心力衰竭。 FARS2缺陷通过直接阻断mt-tRNA ^Phe的氨酰化并抑制线粒体蛋白质的合成来损害线粒体稳态，最终通过加速线粒体过度碎片化和破坏线粒体相关自噬而导致线粒体质量控制系统失衡。使用腺相关病毒 9 或特定抑制剂干扰线粒体质量控制系统，可通过恢复线粒体稳态来减轻 FARS2 缺陷引发的心脏和线粒体功能障碍。 结论：我们的研究结果揭示了FARS2先前未被认识的作用心脏和线粒体稳态。这项研究可能为遗传性心肌病的分子诊断和预防以及 FARS2 相关心肌病的治疗选择提供新的见解。