PDF(Pubmed)
Abstract：
Rationale: Myocardial infarction (MI) is a severe global clinical condition with widespread prevalence. The adult mammalian heart\'s limited capacity to generate new cardiomyocytes (CMs) in response to injury remains a primary obstacle in developing effective therapies. Current approaches focus on inducing the proliferation of existing CMs through cell-cycle reentry. However, this method primarily elevates cyclin dependent kinase 6 (CDK6) and DNA content, lacking proper cytokinesis and resulting in the formation of dysfunctional binucleated CMs. Cytokinesis is dependent on ribosome biogenesis (Ribo-bio), a crucial process modulated by nucleolin (Ncl). Our objective was to identify a novel approach that promotes both DNA synthesis and cytokinesis. Methods: Various techniques, including RNA/protein-sequencing analysis, Ribo-Halo, Ribo-disome, flow cytometry, and cardiac-specific tumor-suppressor retinoblastoma-1 (Rb1) knockout mice, were employed to assess the series signaling of proliferation/cell-cycle reentry and Ribo-bio/cytokinesis. Echocardiography, confocal imaging, and histology were utilized to evaluate cardiac function. Results: Analysis revealed significantly elevated levels of Rb1, bur decreased levels of circASXL1 in the hearts of MI mice compared to control mice. Deletion of Rb1 induces solely cell-cycle reentry, while augmenting the Ribo-bio modulator Ncl leads to cytokinesis. Mechanically, bioinformatics and the loss/gain studies uncovered that circASXL1/CDK6/Rb1 regulates cell-cycle reentry. Moreover, Ribo-Halo, Ribo-disome and circRNA pull-down assays demonstrated that circASXL1 promotes cytokinesis through Ncl/Ribo-bio. Importantly, exosomes derived from umbilical cord mesenchymal stem cells (UMSC-Exo) had the ability to enhance cardiac function by facilitating the coordinated signaling of cell-cycle reentry and Ribo-bio/cytokinesis. These effects were attenuated by silencing circASXL1 in UMSC-Exo. Conclusion: The series signaling of circASXL1/CDK6/Rb1/cell-cycle reentry and circASXL1/Ncl/Ribo-bio/cytokinesis plays a crucial role in cardiac repair. UMSC-Exo effectively repairs infarcted myocardium by stimulating CM cell-cycle reentry and cytokinesis in a circASXL1-dependent manner. This study provides innovative therapeutic strategies targeting the circASXL1 signaling network for MI and offering potential avenues for enhanced cardiac repair.
摘要：
原理：心肌梗塞（MI）是一种严重的全球性临床疾病，普遍存在。成年哺乳动物心脏对损伤的反应产生新的心肌细胞（CMs）的能力有限仍然是开发有效疗法的主要障碍。目前的方法集中在通过细胞周期再入诱导现有CM的增殖。然而,这种方法主要提高细胞周期蛋白依赖性激酶6（CDK6）和DNA含量，缺乏适当的胞质分裂，并导致功能失调的双核CMs的形成。胞质分裂依赖于核糖体生物发生（Ribo-bio），核仁素(Ncl)调节的一个关键过程。我们的目标是确定一种促进DNA合成和胞质分裂的新方法。方法：各种技术，包括RNA/蛋白质测序分析，Ribo-Halo,Ribo-disome,流式细胞术,和心脏特异性肿瘤抑制视网膜母细胞瘤-1（Rb1）基因敲除小鼠，用于评估增殖/细胞周期再入和Ribo-bio/胞质分裂的系列信号传导。超声心动图,共焦成像，和组织学用于评估心功能。结果：与对照小鼠相比，分析显示MI小鼠心脏中Rb1的水平显着升高，circASXL1的水平降低。Rb1的缺失仅诱导细胞周期重新进入，同时增强Ribo-生物调节剂Ncl导致胞质分裂。机械上,生物信息学和损失/增益研究发现circASXL1/CDK6/Rb1调节细胞周期重新进入。此外，Ribo-Halo,Ribo-disome和circRNA下拉测定表明circASXL1通过Ncl/Ribo-bio促进胞质分裂。重要的是,来自脐带间充质干细胞（UMSC-Exo）的外泌体能够通过促进细胞周期折返和Ribo-bio/胞质分裂的协调信号来增强心脏功能。通过在UMSC-Exo中沉默circASXL1来减弱这些作用。结论：circASXL1/CDK6/Rb1/细胞周期折返和circASXL1/Ncl/Ribo-bio/胞质分裂的系列信号在心脏修复中起着至关重要的作用。UMSC-Exo通过以circASXL1依赖性方式刺激CM细胞周期折返和胞质分裂来有效修复梗塞心肌。这项研究提供了针对MI的circASXL1信号网络的创新治疗策略，并提供了增强心脏修复的潜在途径。
