Investigating the Role of MBNL1 in Maintaining Cardiomyocyte Terminal Differentiation.

项目摘要/总结。 心肌细胞的状态在出生后的发育过程中发生了巨大的变化。在此期间， 心肌细胞终末分化，从根本上改变它们的能量，功能机制， 细胞生长的机制。虽然我们对控制胚胎心脏的因素有很好的了解， 尽管如此，我们仍然对建立心肌细胞终末的机制缺乏了解， 在出生后的发育过程中分化，并在成人中保持这种细胞状态。关键是，心肌细胞 终末分化与心脏重塑和再生密切相关。虽然一个终端 分化的转录组是心肌细胞适应成人循环需求所必需的， 转录程序也抑制心肌细胞增殖，这是哺乳动物细胞不能正常增殖的基础。 心脏在受伤后有意义地再生。事实上，在心脏再生的模型系统中，心肌细胞 必须首先去分化并返回到胎儿样转录组状态以便增殖。很少有研究 负责维持心肌细胞终末分化的因素，但理所当然的是，目标 心肌细胞终末分化的破坏可以揭示成人中潜在的促增殖途径， 心脏并促进内源性心脏再生。 在这项研究中，我们将研究RNA结合蛋白肌盲样蛋白1（MBNL 1）的作用， 控制心肌细胞终末分化和心脏再生。虽然MBNL 1表达 在心肌细胞终末分化期间增加，并且已知MBNL 1促进胎儿至成人同种型 由于它是许多发育调控基因的开关，因此从未直接检查过它是否控制了 心肌细胞终末分化或整合到心脏可塑性周围的调节机制。 具体而言，该提案将使用各种体内和体外遗传方法来解决以下问题 目的：（1）探讨MBNL 1在维持成人心肌细胞终末分化中的作用 哺乳动物心脏和（2）确定MBNL 1在控制心脏再生潜力中的作用。洞察力 从这些目标中收集的信息将表征MBNL 1依赖的转录后调控机制 控制心肌细胞终末分化，并将确定MBNL 1是否可用作新的 治疗靶点，以促进内源性心脏再生。

PROJECT ABSTRACT/SUMMARY. Cardiomyocyte cell state is dramatically altered during postnatal development. During this period, cardiomyocytes terminally differentiate, fundamentally changing their energetics, functional machinery, and mechanism of cell growth. Although we have a good understanding of the factors controlling embryonic heart development, we still have a poor understanding of the mechanisms that establish cardiomyocyte terminal differentiation during postnatal development and maintain this cell state in the adult. Critically, cardiomyocyte terminal differentiation is integrally linked to cardiac remodeling and regeneration. While a terminally differentiated transcriptome is necessary for cardiomyocytes to accommodate adult circulatory demands, this transcriptional program also suppresses cardiomyocyte proliferation, underlying the inability of the mammalian heart to meaningfully regenerate after injury. Indeed, in model systems of cardiac regeneration, cardiomyocytes must first de-differentiate and return to a fetal-like transcriptomic state in order to proliferate. Few studies examine the factors responsible for maintaining cardiomyocyte terminal differentiation, but it stands to reason that targeted disruption of cardiomyocyte terminal differentiation could unmask latent pro-proliferative pathways in the adult heart and promote endogenous cardiac regeneration. In this study, we will examine the role of the RNA-binding protein Muscleblind-like protein 1 (MBNL1) in controlling cardiomyocyte terminal differentiation and cardiac regeneration. Although MBNL1 expression increases during cardiomyocyte terminal differentiation and MBNL1 is known to promote fetal-to-adult isoform switching of a number of developmentally regulated genes, it has never been examined directly for controlling cardiomyocyte terminal differentiation or integrated into regulatory mechanisms surrounding cardiac plasticity. Specifically, this proposal will use a variety of in vivo and in vitro genetic approaches to address the following aims: (1) to determine the role of MBNL1 in maintaining cardiomyocyte terminal differentiation in the adult mammalian heart and (2) to determine the role of MBNL1 in controlling cardiac regenerative potential. Insight gleaned from these aims will characterize MBNL1-dependent post-transcriptional regulatory mechanisms governing cardiomyocyte terminal differentiation and will determine if MBNL1 could be used as a novel therapeutic target to promote endogenous cardiac regeneration.