Investigating collective myocardial cell movement during heart tube formation

项目摘要 器官的形成受到组织间通讯的严格调控。成熟的心的架构 是一系列形态发生事件的结果，从原始的心管开始，这是 心灵的其余部分都建立在这个基础上。建造原始心脏导管的过程开始了 随着心肌细胞从前外侧板中的两侧位置集体移动 中胚层到中线，这一过程被称为心脏融合，在所有脊椎动物中都是保守的。遗传 分析表明，相邻的内胚层对这些运动是至关重要的。然而，这些信号 或者，内胚层与心肌沟通的分子仍不清楚。此外， 脊椎动物心肌细胞对这些信号作出反应的分子机制 人们对整体走向中线也知之甚少。为了阐明这些机制， 密西西比大学的本科生和研究生将参加多维度的 从组织、分子、细胞和生物力学水平研究心脏融合。我们有 发现血小板衍生生长因子受体α(PDGFRA)突变导致心脏融合 斑马鱼和老鼠都有缺陷。心肌运动似乎是对局部的 PDGF配体PDGF-AA的来源，我们发现它在内侧邻近的内胚层表达 PDGFRA在心肌中的表达。此外，我们的初步数据显示，PI3K的中断 斑马鱼体内的信号也会导致心脏融合缺陷。心肌细胞表现出突起 在心脏融合过程中表现出细胞形态的异质性变化。总而言之，这些数据表明 内胚层旁分泌PDGF信号激活PDGFRA介导的PI3K信号的假说 心肌产生内侧定向移行突起，从而产生不对称的生物力学 心肌张力促进内侧运动。我们将用组织来检验这个假说- 确定PDGFRA和PDGF-AA功能的组织的特定遗传技术(目标1) AS确定PDGFRA下游是否激活了PI3K信号和迁移突起 (AIM2)。此外，我们将使用微流变学和微激光消融与PDGFRA相结合 突变体检测PDGF信号控制的心肌生物力学特性(AIM 3)。综上所述，这些研究可能会阐明其背后的分子机制 心肌细胞感知并对其局部环境做出反应，并在长期内识别 心脏形态发生在发育和疾病过程中的基本原理。 此外，这项建议将有助于建立一个将学生研究交织在一起的研究计划 发现组织间潜在的基本分子机制带来的机遇 器官形态发生过程中的沟通。

Project Summary Organ formation is critically regulated by inter-tissue communication. The architecture of the mature heart is a result of sequential morphogenetic events, starting with the primitive heart tube, which is the foundation upon which the rest of the heart is built. The process of building the primitive heart tube starts with the collective movement of myocardial cells from bilateral locations in the anterior lateral plate mesoderm to the midline, a process called cardiac fusion which is conserved in all vertebrates. Genetic analysis has revealed that the adjacent endoderm is critical for these movements. However, the signals or molecules by which the endoderm communicates to the myocardium remain unknown. Furthermore, the molecular mechanism by which myocardial cells in vertebrates respond to these signals and collectively move towards the midline is also poorly understood. To elucidate these mechanisms, undergraduate and graduate students from the University of Mississippi will take a multi-dimensional approach examining cardiac fusion at the tissue, molecular, cellular and biomechanical level. We have found that mutations in the Platelet-derived growth factor receptor alpha (Pdgfra) leads to cardiac fusion defects in both zebrafish and mice. Myocardial movement appears to occur in response to a localized source of the PDGF ligand pdgf-aa, which we found is expressed in the endoderm medially adjacent to pdgfra expression in the myocardium. Furthermore, our preliminary data reveals that disruption of PI3K signaling in zebrafish also causes cardiac fusion defects. And that myocardial cells exhibit protrusions and display heterogenous changes in cell shape during cardiac fusion. Together, this data suggests the hypothesis that paracrine PDGF signals from the endoderm activates Pdgfra-mediated PI3K signaling in the myocardium to create medial oriented migratory protrusions which create asymmetric biomechanical tension in the myocardium facilitating medial movement. We will test this hypothesis by using tissue- specific genetic techniques to determine the tissues in which pdgfra and pdgf-aa function (Aim 1) as well as determine whether PI3K signaling and migratory protrusions are activated downstream of Pdgfra (Aim2). Additionally, we will use micro-rheology and micro-laser ablation in combination with pdgfra mutants to examine the biomechanical properties in the myocardium controlled by PDGF signaling (Aim 3). In summary, these studies are likely to elucidate the molecular mechanisms that underlie how myocardial cells sense and respond to their local environment and in the long-term identify the fundamental principles that underlie cardiac morphogenesis in both development and disease. Furthermore, this proposal will help to establish a research program that intertwines student research opportunities with the discovery of fundamental molecular mechanisms underlying inter-tissue communication during organ morphogenesis.