Regulation of Myocardial Regeneration in Zebrafish

描述：心肌梗死(Ml)是由缺血引起的心肌局灶性损失，是这个国家的主要死亡原因。发病率和死亡率与ML密切相关的一个原因是，人类心脏通过再生心肌细胞(CMS)进行自我修复的能力极其有限，CMS是心脏的收缩细胞。与哺乳动物相比，硬骨斑马鱼对心脏损伤表现出高效的再生反应，能够再生高达20%的切除的心肌。新的细胞质雄性不育是如何在再生过程中产生的，人们对此知之甚少。这项建议的目的是利用斑马鱼作为了解心肌再生的细胞和分子机制的模型。以前的研究已经记录了在低等脊椎动物的肢体、尾巴或晶状体再生过程中，去分化是如何产生前体细胞的，去分化是成熟的、分化的细胞的专门功能成分的程序性减少。人们认为这些前体细胞的起源、增殖和模式是由共同的胚胎信号通路控制的。我们建议的总体假设是斑马鱼的心肌损伤激活了分子程序，该程序调节从收缩的、非增殖的心肌到增殖并有图案的再生性CMS的转变。为了验证这一假设，我们提出了三个具体的目标：1)确定心肌再生过程中的变化，这将包括对超微结构分化、基因表达、细胞增殖和心功能的详细研究。我们还将比较斑马鱼和小鼠损伤诱导的心肌基因表达。2)确定成纤维细胞生长因子信号在心肌再生中的作用。我们将使用新的可诱导的转基因品系，通过FG受体促进信号调节，研究实验性增加或减少成纤维细胞生长因子信号活性如何影响再生心脏发生。3)明确维甲酸(RA)信号在心肌再生中的作用。我们将产生并分析促进显性负性或结构性表达的转基因株系！活性RA受体同型。我们在斑马鱼中的分子遗传学方法将为理解在心肌再生过程中活跃的重要调控机制提供基础，并可能导致理解并可能增强人类在ML后表现出的有限的再生反应。

DESCRIPTION: Myocardial infarction (Ml), the focal loss of cardiac muscle caused by ischemia, is the leading cause of death in this country. One reason why morbidity and mortality are intimately associated with Ml is that the human heart has an extremely limited ability to repair itself through regeneration of cardiomyocytes (CMs), the contractile cells of the heart. By contrast with mammals, the teleost zebrafish displays a highly efficient regenerative response to cardiac injury, able to renew up to 20% of resected ventricular myocardium. How new CMs originate during regeneration is poorly understood. The objective of this proposal is to exploit zebrafish as a model for understanding the cellular and molecular mechanisms of myocardial regeneration. Previous studies have documented how dedifferentiation, a programmed reduction in the specialized, functional components of a mature, differentiated cell, generates precursor cells during regeneration of the limb, tail, or lens in lower vertebrates. It is believed that the origin, proliferation, and patterning of these precursors are controlled by common embryonic signaling pathways. The overall hypothesis of our proposal is that myocardial damage in the zebrafish activates molecular programs that regulate a transition from contractile, non-proliferating cardiac muscle to regenerative CMs that proliferate and are patterned. To test this hypothesis, we propose three specific aims: 1) Define myocardial changes during regeneration This will include detailed studies of ultrastructural differentiation, gene expression, cellular proliferation, and cardiac function. We will also compare injury-induced myocardial gene expression between zebrafish and mice. 2) Determine the functions of Fibroblast growth factor (Fgf) signaling in myocardial regeneration. We will examine how experimental increases or decreases in Fgf signaling activity affect regenerative cardiogenesis, using new inducible transgenic lines that facilitate modulation of signaling through Fg receptors. 3) Identify the functions of retinoic acid (RA) signaling in myocardial regeneration. We wil generate and analyze transgenic lines that facilitate expression of a dominant-negative or constitutive! active RA receptor isotype. Our molecular genetic approach in zebrafish will provide a foundation fo understanding important regulatory mechanisms active during myocardial regeneration, and may lead t approaches for comprehending, and possibly enhancing, the limited regenerative response displayed b humans after Ml.