Notch信号通路调控心室再生过程的机制研究

Heart failure is the leading cause of death in the world due to the inability to adequately replace damaged ventricular myocardium from ischemia-induced infarcts. Though adult mammalian ventricular cardiomyocytes have a limited capacity to divide, this proliferation is not sufficient to overcome the significant loss of myocardium. In contrast, lower vertebrates like zebrafish have the remarkable capacity for cardiac regeneration after severe injury. Understanding the underlying cellular and molecular mechanisms of this process may provide innovative approaches for human cardiac regenerative medicine. However, the signaling pathways regulating cardiac regeneration remain poorly understood. ..Utilizing the zebrafish, a powerful genetic model organism, we have generated a genetic injury model that can specifically damage the ventricle and allow it to recover. We have observed that Notch signaling becomes activated following ventricular injury and this activation is required to promote ventricular myocardial regeneration, partially through transdifferentiation of atrial cardiomyocytes. The result has been published in Nature. In this project we will further study the function and molecular mechanism of Notch signaling in cardiac ventricle regeneration, using techniques such as whole mount in situ hybridization, immunohistochemistry, small molecule treatment, tissue-specific gene induction/repression and in vivo live imaging. We will focus on the interaction between Notch signaling and downstream signaling network as well as the specific roles of Notch signaling in cellular processes like cell proliferation, cell migration and cell transdifferentiation. This project will provide further understanding on the regulation of cardiac regeneration, also may provide novel approaches in the future toward new therapeutic strategies in human cardiac regenerative medicine.

心肌梗死及引发的心力衰竭是现代社会致死的主要原因之一。哺乳动物包括人的心脏出生后只具备很弱的细胞增殖能力，不足以补充心肌梗死中失去的心肌细胞。相反，斑马鱼具有很强的心脏再生能力，研究其心脏再生的分子和细胞机制对再生医学的研究具有重要的借鉴意义。然而目前对于调控心脏再生信号通路的具体机制了解依旧不多，我们创建了一个心室特异性心肌细胞损伤和再生遗传模型，以克服常用的机械损伤技术的不足。我们之前发表在Nature的研究表明，Notch信号通路在心室再生过程中被激活，抑制其激活会阻遏心房心肌细胞的转分化，显著降低心室的再生。本项目将深入研究Notch信号通路在心室再生过程中的变化规律和调控机制，特别是调控相关信号通路如BMP和Nrg/Erbb信号以及对细胞增殖、细胞迁移和细胞转分化等过程的具体作用。本项目的成功实施可以加深对心脏再生机制的了解，有望为诱导人类心脏再生提供理论依据和潜在途径。

心肌梗死及引发的心力衰竭是现代社会致死的主要原因之一。哺乳动物包括人的心脏出生后只具备很弱的细胞增殖能力，不足以补充心肌梗死中失去的心肌细胞。相反，斑马鱼具有很强的心脏再生能力，研究其心脏再生的分子和细胞机制对再生医学的研究具有重要的借鉴意义。. 本项目前期发现Notch信号通路在心室再生过程中被激活，抑制其激活会显著降低心室的再生。本项目深入研究Notch信号通路在心室再生过程中的作用和分子机制，特别是和上、下游相关的信号通路网络的相互作用以及对再生过程中各细胞事件的调控。. 我们发现血流动力变化能够影响Notch信号的激活，进而影响心室再生,而且主要的血流感知分子klf2在心脏损伤后表达上调。我们使用CRISPR/Cas9技术创制了斑马鱼同源基因klf2a和klf2b的单基因敲除和双基因敲除品系，证明这两个同源基因都是Notch信号通路激活所必须，它们之间存在协同作用。由于纤毛上富集了多种感知血流动力的离子通道，我们进一步研究了纤毛对心脏再生的影响，通过化学和遗传学手段阻止纤毛的生成，klf2在心脏损伤后的激活被抑制，不能诱导notch信号通路促进再生。. 我们还证明了Notch信号通路位于BMP和Nrg/Erbb2信号的上游。对这几个信号通路的进一步分析发现，Notch信号通路影响再生过程中细胞增殖、迁移和转分化等各项细胞事件，而BMP信号通路更专门调控细胞增殖，Nrg/Erbb2信号通路则对转分化有影响。我们建立了一个基于泛素化降解的细胞周期指示系统报告品系，可以实时观察心脏再生中的细胞增殖事件，并进一步比较了Notch与BMP信号通路调节机制的异同。. 通过本项目的研究，加深了我们对心脏再生机制的了解，有望为诱导人类心脏再生提供理论依据和潜在途径。