Abstract：
UNASSIGNED: 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 synthase 1 (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 partially ameliorated anemia phenotypes in a patient 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.
摘要：
假尿嘧啶是最普遍的RNA修饰，其异常功能与各种人类疾病有关。然而,目前人们对假性尿嘧啶化对造血的具体影响知之甚少.在这项研究中,我们研究了tRNA假尿酰在红细胞生成中的作用及其与线粒体肌病的关系，乳酸性酸中毒,和铁粒幼细胞性贫血综合征（MLASA）的发病机制。通过利用携带遗传PUS1突变的患者特异性诱导多能干细胞（iPSCs）和相应的突变小鼠模型，我们证实MLASAiPSCs红细胞生成受损,MLASA小鼠模型出现贫血.MLASAiPSC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。机械上,我们发现PUS1缺乏导致线粒体tRNA水平降低，导致异常的线粒体翻译。旨在增强呼吸或血红素合成的线粒体补充剂的筛选在促进红细胞分化方面显示出有限的作用。有趣的是,mTOR抑制剂雷帕霉素通过抑制mTOR信号和蛋白质合成促进MLASA-iPSCs的红系分化,在MLASA小鼠模型中观察到一致的结果。重要的是,雷帕霉素治疗可有效改善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，并为面临与蛋白质翻译相关挑战的贫血患者提供了潜在的治疗策略。
