Defining the developmental mechanisms of pericardium formation

项目总结 心包是包裹心脏以支持其发育和维持的间皮囊 随着时间的推移，心脏的动态平衡。在整个心脏循环过程中，心包作为细胞来源。 形成各种心脏结构，使其成为心脏形态发生中的关键角色。然而，人们对此知之甚少 关于它的发育起源，以及它是如何在心脏发育、动态平衡、 和损伤后的再生。虽然早期间皮起源总体上直到最近才被详细描述 利用斑马鱼，心包特别难研究，因为它的动态发育和 缺乏遗传标记。我们的实验室已经将间皮祖细胞映射到侧板中胚层表达 转录因子Hand2，并进一步将Hand2的功能与间皮和心包的形成联系起来。 这些间皮生物学的概念和技术进展使我们能够研究心包和 心脏结构在发育过程中聚集在一起，形成一个单一的功能器官系统。我的扩展 这一数据表明，心包祖细胞和心脏祖细胞是后来出现的不同的祖细胞群体 在胚胎发育过程中融合在一起。这项建议的目的是揭示发展的 调控祖细胞进入心脏和心包的机制及确定规范基因的作用 控制心包浮现的WNT信号。在目标1中，我将使用转基因斑马鱼的组合 标记发育中的心脏和心包的线条，活体时间推移成像，稳定的基因敲除 心脏成分，以及多色谱系追踪记者，以检查细胞起源和动力学 发育中的心包。在目标2中，我将研究Hand2和规范Wnt信号之间的相互作用 通过记录Wnt靶标在Hand2突变体斑马鱼中的表达动态，过量表达Wnt 利用CRISPR-Cas9突变突变Hand2结合位点。总而言之，这个项目将是 第一个全面描述心包发育是如何进行的，并结合了心脏和相互作用 Hand2和规范的Wnt信号在控制心包发育中的作用。

PROJECT SUMMARY The pericardium is a mesothelial sac that encapsulates the heart to support its development and maintain cardiac homeostasis over time. Throughout the process of heart looping, the pericardium serves as a cell source to form various cardiac structures, making it a crucial player in heart morphogenesis. However, little is known about its developmental origins and how it acquires its unique properties in cardiac development, homeostasis, and regeneration post-injury. While early mesothelial origins overall have only been recently described in detail using the zebrafish, the pericardium has been particularly difficult to study due to its dynamic development and a lack of genetic markers. Our lab has mapped mesothelial progenitors to the lateral plate mesoderm expressing the transcription factor Hand2, and further linked Hand2 function to mesothelium and pericardium formation. These conceptual and technical advances in mesothelial biology enable us to investigate how pericardial and cardiac structures come together to form a single functional organ system during development. My expansion of this data suggests that pericardial and cardiac progenitors are distinct progenitor populations that later come together to fuse together during embryogenesis. The objective of this proposal is to uncover the developmental mechanisms governing progenitor patterning into the heart and pericardium and identify the role of canonical Wnt signaling that controls the pericardial emergence. In Aim 1, I will use a combination of transgenic zebrafish lines that label the developing heart and pericardium, in vivo time-lapse imaging, stable genetic knockdowns of cardiac components, and multi-color lineage tracing reporters to examine the cellular origins and dynamics of the developing pericardium. In Aim 2, I will investigate the interplay between Hand2 and canonical Wnt signaling by documenting the expression dynamics of Wnt targets in Hand2 mutant zebrafish, overexpressing Wnt components, and using CRISPR-Cas9 mutagenesis to mutate Hand2 binding sites. Together, this project will be the first to fully characterize how pericardial development proceeds and incorporates the heart and the interplay between Hand2 and canonical Wnt signaling in controlling pericardium development.