Investigating the Roles of APJ, Hypoxia, and SOX17 in the Development of Coronary Vessels

项目摘要 这项建议使用转基因小鼠模型和现代细胞和分子生物学方法来表征 APJ、缺氧和SOX17在冠状动脉血管形成调节中的作用。冠状动脉疾病是 是世界范围内的主要死亡原因之一，目前仍缺乏有效的治疗。因此，了解如何 这些血管首次在胚胎中形成，剖析它们的细胞和分子机制可以 在设计合适的治疗方法时要有价值。从对小鼠的研究中，我们知道冠状动脉血管 由多个内皮祖细胞形成，即心外膜、静脉窦和心内膜。虽然 祖细胞干细胞对于冠状动脉血管形成的起源已被鉴定，这方面的知识严重缺乏 存在着引导这些祖细胞形成冠状血管树的线索。在这方面，我们已经确定 选择性地影响来自静脉窦和心内膜的冠状动脉生长的分子途径。阿佩林 受体(俗称APJ)是一种G蛋白偶联受体，被发现对鼻窦静脉起重要作用 衍生的祖细胞通路，而心肌缺氧被发现对心内膜有潜在的重要作用 冠脉血管形成的衍生祖细胞途径。此外，还发现了转录因子SOX17 由激活的心内膜祖细胞表达，提示SOX17在冠状动脉病变中的作用 血管生成。在这一点上，我们对APJ、缺氧诱导因子-1α(HIF-1α)以及 Sox17对冠脉血管生成有调节作用。APJ被两种多肽配体激活，ELABELA(别名：APELA， 和APELIN，它们都在胚胎心脏中表达。目前尚不清楚APJ信号是如何从 这两种配体协调静脉窦前体细胞形成冠状动脉的进程 路径。这一提议旨在解开APJ、缺氧和SOX17介导的未知因素 冠脉血管形成的调控。在目标1中，我们假设ELABELA/APJ和APELIN/APJ 静脉窦来源的冠状动脉前体细胞对血管生成信号的反应 (心外膜)和血管内皮生长因子A(心肌)。在目标2中，我们假设 心肌缺氧激活心内膜祖细胞SOX17表达，SOX17促进冠脉病变 血管生成。这项研究中提出的实验非常适合高中、本科生、 研究生和这些学生将参与项目的每个阶段，允许他们 通过包括转基因小鼠模型在内的创新方法获得真实的研究经验(Gain- 功能丧失和功能丧失模型)、细胞和组织培养系统以及现代细胞和分子 生物学技术。

Project Summary This proposal uses transgenic mouse models and modern cell and molecular biology approaches to characterize the roles of APJ, hypoxia, and SOX17 in the regulation of coronary vessel formation. Coronary artery disease is one of the leading causes of death worldwide and still lacks effective treatment. Therefore, understanding how these vessels form for the first time in the embryos and dissecting their cellular and molecular mechanisms can be valuable in designing appropriate therapeutics. From studies in mice, it is known that coronary vessels are formed from multiple endothelial progenitors namely proepicardium, sinus venosus, and endocardium. Although the progenitor stem cells for the origin of coronary vessel formation is identified, a significant lack of knowledge exist on what cues guide these progenitors to form coronary vascular tree. In this context, we have identified molecular pathways that selectively impact coronary growth from sinus venosus and endocardium. Apelin receptor (commonly known as APJ), a G-protein coupled receptor, is found to be important for the sinus venous derived progenitor pathway whereas myocardial hypoxia is found to be potentially important for the endocardium derived progenitor pathway of coronary vessel formation. Furthermore, a transcription factor SOX17 is also found to be expressed by activated endocardial progenitors, suggesting a role for SOX17 during coronary angiogenesis. At this point, we know very little on how APJ, hypoxia inducible factor-1alpha (HIF-1alpha), and SOX17 regulate coronary angiogenesis. APJ is activated by two peptide ligands, ELABELA (aliases: APELA, TODDLER) and APELIN, which are both expressed in embryonic hearts. It is not clear how APJ signaling from these two ligands coordinate the progression of coronary vessel formation from sinus venosus progenitor pathway. This proposal is aimed at unraveling the unknowns of APJ, Hypoxia, and SOX17 mediated regulation of coronary vessel formation. In Aim 1, we hypothesize that ELABELA/APJ and APELIN/APJ signaling primes sinus venosus derived coronary progenitors to respond to angiogenic cues such as VEGFC (in the epicardium) and VEGF-A (in the myocardium) respectively. In Aim 2, we hypothesize that myocardial hypoxia activates SOX17 expression in endocardial progenitors, and SOX17 promotes coronary angiogenesis. The experiments proposed in this study are highly appropriate for high school, undergraduate, and graduate students and these students will be engaged in every stage of the project, allowing them to obtain authentic research experience with innovative approaches including transgenic mouse models (gain- of-function and loss-of-function models), cell and tissue culture systems, and modern cell and molecular biology techniques.