Pseudouridine is the most prevalent RNA modification, and its aberrant function is implicated in various human diseases. However, the specific impact of pseudouridylation on hematopoiesis remains poorly understood. Here, we investigated the role of transfer RNA (tRNA) pseudouridylation in erythropoiesis and its association with mitochondrial myopathy, lactic acidosis, and sideroblastic anemia syndrome (MLASA) pathogenesis. By using patient-specific induced pluripotent stem cells (iPSCs) carrying a genetic pseudouridine synthases (PUS1) mutation and a corresponding mutant mouse model, we demonstrated impaired erythropoiesis in MLASA-iPSCs and anemia in the MLASA mouse model. Both MLASA-iPSCs and mouse erythroblasts exhibited compromised mitochondrial function and impaired protein synthesis. Mechanistically, we revealed that PUS1 deficiency resulted in reduced mitochondrial tRNA levels because of pseudouridylation loss, leading to aberrant mitochondrial translation. Screening of mitochondrial supplements aimed at enhancing respiration or heme synthesis showed limited effect in promoting erythroid differentiation. Interestingly, the mammalian target of rapamycin (mTOR) inhibitor rapamycin facilitated erythroid differentiation in MLASA-iPSCs by suppressing mTOR signaling and protein synthesis, and consistent results were observed in the MLASA mouse model. Importantly, rapamycin treatment effectively ameliorated anemia phenotypes in the patients with MLASA. Our findings provide novel insights into the crucial role of mitochondrial tRNA pseudouridylation in governing erythropoiesis and present potential therapeutic strategies for patients with anemia facing challenges related to protein translation.

中文翻译：

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线粒体 tRNA 假尿苷化控制红细胞生成


假尿苷是最常见的 RNA 修饰，其异常功能与多种人类疾病有关。然而，假尿苷化对造血的具体影响仍知之甚少。在这里，我们研究了转移 RNA (tRNA) 假尿苷化在红细胞生成中的作用及其与线粒体肌病、乳酸性酸中毒和铁粒幼细胞贫血综合征 (MLASA) 发病机制的关系。通过使用携带遗传假尿苷合酶 (PUS1) 突变的患者特异性诱导多能干细胞 (iPSC) 和相应的突变小鼠模型，我们证明了 MLASA-iPSC 中的红细胞生成受损，以及 MLASA 小鼠模型中的贫血。 MLASA-iPSC 和小鼠成红细胞均表现出线粒体功能受损和蛋白质合成受损。从机制上讲，我们发现 PUS1 缺陷会因假尿苷化丢失而导致线粒体 tRNA 水平降低，从而导致线粒体翻译异常。旨在增强呼吸或血红素合成的线粒体补充剂的筛选显示在促进红细胞分化方面效果有限。有趣的是，哺乳动物雷帕霉素靶标 (mTOR) 抑制剂雷帕霉素通过抑制 mTOR 信号传导和蛋白质合成来促进 MLASA-iPSC 中的红系分化，并且在 MLASA 小鼠模型中观察到一致的结果。重要的是，雷帕霉素治疗有效改善了 MLASA 患者的贫血表型。我们的研究结果为线粒体 tRNA 假尿苷化在控制红细胞生成中的关键作用提供了新的见解，并为面临蛋白质翻译相关挑战的贫血患者提供了潜在的治疗策略。