哈尔滨医科大学杜伟杰等研究人员合作发现，Mettl1敲低通过失活Mettl1-CYLD-P53正反馈环路缓解小鼠心脏I/R损伤。这一研究成果于2024年10月16日在线发表在《中国药理学报》上。

研究人员探讨了Mettl1在小鼠心肌细胞损伤中的作用及其潜在机制。通过结扎左前降支冠状动脉（LAD）45分钟后再灌注24小时建立小鼠心脏缺血/再灌注（I/R）模型。研究人员显示Mettl1的mRNA和蛋白水平在小鼠I/R心脏和H₂O₂处理的新生小鼠心肌细胞（NMCM）中显著上调。Mettl1敲低显著改善了心脏I/R损伤，表现为梗死面积、凋亡减少以及心脏功能改善。Mettl1的过表达在体内和体外均引发了心肌细胞的凋亡。

通过在Mettl1过表达的小鼠心脏中进行RNA测序结合N7-甲基鸟苷（m7G）甲基化RNA测序，研究人员揭示了Mettl1催化去泛素化酶cylindromatosis（CYLD）mRNA的m7G修饰，从而增加CYLD的表达，进而通过抑制其泛素化降解来增强P53的稳定性。反之，P53作为转录因子在I/R损伤期间正向调控Mettl1的表达。CYLD敲低减轻了Mettl1过表达或氧化应激引起的心肌细胞凋亡。从现有的药物靶点数据库和文献中，研究人员鉴定出了4种m7G修饰的小分子抑制剂。Mettl1抑制剂之一的Sinefungin在体内和体外对心脏I/R损伤表现出显著的保护作用。

总的来说，该研究确定了Mettl1是心肌细胞凋亡的关键调节因子，靶向Mettl1-CYLD-P53正反馈回路可能代表一种缓解心脏I/R损伤的新型治疗途径。

据介绍，m7G甲基转移酶Mettl1最近被认为与心脏修复和纤维化有关。

附：英文原文

Title: Mettl1 knockdown alleviates cardiac I/R injury in mice by inactivating the Mettl1-CYLD-P53 positive feedback loop

Author: Yu, Shu-ting, Sun, Zhi-yong, Li, Na, Qu, Zhe-zhe, Wang, Chang-hao, Ju, Tian-tian, Liu, Ying-qi, Mei, Zhong-ting, Liu, Kui-wu, Lu, Mei-xi, Huang, Min, Li, Ying, Dou, Shun-kang, Jiang, Jian-hao, Zhang, Yao-zhi, Huang, Chuan-hao, Pang, Xiao-chen, Jia, Ying-qiong, Dong, Xian-hui, Wu, Fan, Zhang, Yi, Li, Wan-hong, Yang, Bao-feng, Du, Wei-jie

Issue&Volume: 2024-10-16

Abstract: The N7-methylguanosine (m7G) methyltransferase Mettl1 has been recently implicated in cardiac repair and fibrosis. In this study we investigated the role of Mettl1 in mouse cardiomyocytes injury and the underlying mechanisms. Cardiac ischemia/reperfusion (I/R) I/R model was established in mice by ligation of the left anterior descending coronary artery (LAD) for 45min followed by reperfusion for 24h. We showed the mRNA and protein levels of Mettl1 were significantly upregulated in mouse I/R hearts and H2O2-treated neonatal mouse cardiomyocytes (NMCMs). Mettl1 knockdown markedly ameliorated cardiac I/R injury, evidenced by decreased infarct size, apoptosis, and improved cardiac function. Overexpression of Mettl1 triggered cardiomyocytes apoptosis in vivo and in vitro. By performing RNA sequencing combined with m7G methylated RNA sequencing in Mettl1-overexpressing mouse hearts, we revealed that Mettl1 catalyzed m7G modification of the deubiquitinase cylindromatosis (CYLD) mRNA to increase the expression of CYLD, which enhanced the stability of P53 via abrogating its ubiquitination degradation. Vice versa, P53 served as a transcriptional factor to positively regulate Mettl1 expression during I/R injury. Knockdown of CYLD mitigated cardiomyocytes apoptosis induced by Mettl1 overexpression or oxidative stress. From the available drug-targets databases and literature, we identified 4 small molecule inhibitors of m7G modification. Sinefungin, one of the Mettl1 inhibitors exerted profound protection against cardiac I/R injury in vivo and in vitro. Collectively, this study has identified Mettl1 as a key regulator of cardiomyocyte apoptosis, and targeting the Mettl1-CYLD-P53 positive feedback circuit may represent a novel therapeutic avenue for alleviating cardiac I/R injury.

DOI: 10.1038/s41401-024-01395-5

Source: https://www.nature.com/articles/s41401-024-01395-5