Segal Cancer Center, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada.
Departments of Human Genetics, McGill University, Montreal, Canada.
Elife. 2023 Jun 7;12:RP84570. doi: 10.7554/eLife.84570.
In skeletal muscle, muscle stem cells (MuSC) are the main cells responsible for regeneration upon injury. In diseased skeletal muscle, it would be therapeutically advantageous to replace defective MuSCs, or rejuvenate them with drugs to enhance their self-renewal and ensure long-term regenerative potential. One limitation of the replacement approach has been the inability to efficiently expand MuSCs ex vivo, while maintaining their stemness and engraftment abilities. Herein, we show that inhibition of type I protein arginine methyltransferases (PRMTs) with MS023 increases the proliferative capacity of ex vivo cultured MuSCs. Single cell RNA sequencing (scRNAseq) of ex vivo cultured MuSCs revealed the emergence of subpopulations in MS023-treated cells which are defined by elevated Pax7 expression and markers of MuSC quiescence, both features of enhanced self-renewal. Furthermore, the scRNAseq identified MS023-specific subpopulations to be metabolically altered with upregulated glycolysis and oxidative phosphorylation (OxPhos). Transplantation of MuSCs treated with MS023 had a better ability to repopulate the MuSC niche and contributed efficiently to muscle regeneration following injury. Interestingly, the preclinical mouse model of Duchenne muscular dystrophy had increased grip strength with MS023 treatment. Our findings show that inhibition of type I PRMTs increased the proliferation capabilities of MuSCs with altered cellular metabolism, while maintaining their stem-like properties such as self-renewal and engraftment potential.
在骨骼肌中，肌肉干细胞（MuSC）是损伤后再生的主要细胞。在患病的骨骼肌中，如果能够用药物替代有缺陷的 MuSC，或者使它们恢复活力来增强自我更新能力，并确保长期的再生潜力，这将具有治疗上的优势。替代方法的一个局限性是无法有效地在体外扩增 MuSC，同时保持其干细胞特性和植入能力。本文中，我们发现，用 MS023 抑制 I 型蛋白精氨酸甲基转移酶（PRMTs）可以增加体外培养的 MuSC 的增殖能力。对体外培养的 MuSC 进行单细胞 RNA 测序（scRNAseq）显示，在 MS023 处理的细胞中出现了亚群，这些亚群的特征是 Pax7 表达升高和 MuSC 静止的标志物，这两个特征都增强了自我更新能力。此外，scRNAseq 鉴定出 MS023 特异性亚群的代谢发生改变，糖酵解和氧化磷酸化（OxPhos）上调。用 MS023 处理的 MuSC 移植后，有更好的能力重新填充 MuSC 龛，并在损伤后有效地促进肌肉再生。有趣的是，Duchenne 肌营养不良症的临床前小鼠模型在接受 MS023 治疗后握力增加。我们的研究结果表明，抑制 I 型 PRMTs 可以增加 MuSC 的增殖能力，同时改变细胞代谢，保持其干细胞特性，如自我更新和植入潜力。
