Mechanotransduction and transcriptional regulation during artery development

 描述（由申请人提供）：项目总结冠心病是全球死亡的主要原因，但冠状动脉（CA）的发展和再生仍然不完全清楚。动脉发育受遗传和机械因素的指导，后者涉及到血液动力学力量，其作用是形成血管床的层次组织。机械信号对于CA的发展特别重要，因为它们的分化仅在未灌注的冠状动脉丛附着到主动脉并开始接收血流后才被诱导。我们的长期目标是了解冠状动脉血流的启动如何转化为触发CA分化并刺激其随后成熟和稳定的发育信号。我们最近发现Dach 1是果蝇视网膜决定基因网络（RDGN）中的一种转录因子，在发育中的CA中表达，但一旦血管成熟，高层流剪切应力就会下调。Dach 1基因敲除小鼠的CA较小，经常出现结构异常，包括一些层次结构的丢失。此外，Dach 1在体外耗竭降低冠状动脉内皮细胞的增殖和迁移。本项目的目标是确定 Dach 1通过什么支持CA的发展，以及其流动诱导的下调是否是成熟和/或稳定所必需的。我们假设Dach 1与其他RDGN成员相互作用以调节CA正常生长所必需的基因的转录，并且由于其抑制BMP/SMAD诱导的血管静止，这种活性在血管成熟/稳定期间必须降低。这些假设将在三个目标中进行检验。我们将（1）确定Dach 1如何影响基因转录，RDGN成员是否作为其伴侣，以及这些相互作用如何调节CA发展过程中的内皮细胞行为，（2）研究高切应力介导的Dach 1下调在动脉成熟过程中的作用，（3）测试Dach 1是否与BMP/SMAD相互作用以调节动脉大小。这些研究将描述Dach 1/RDGN转录复合物如何指导动脉生成。他们还将提供深入了解的机制，血液动力学力量调节转录程序，形成成熟的血管树的层次组织。这些机制的知识可以用于刺激疾病期间现有或新动脉的生长。

 DESCRIPTION (provided by applicant): Project summary Coronary heart disease is the leading cause of death worldwide, yet coronary artery (CA) development and regeneration remains incompletely understood. Artery development is guided by both genetic and mechanical cues, the latter of which involves hemodynamic forces that function to shape the hierarchal organization of vascular beds. Mechanical signals are particularly important for CA development since their differentiation is only induced after the unperfused coronary plexus attaches to the aorta and begins to receive blood flow. Our long-term goal is to understand how initiation of coronary blood flow is translated into developmental signals that trigger CA differentiation and stimulate their subsequent maturation and stabilization. We recently discovered that Dach1, a transcription factor in the Drosophila retinal determination gene network (RDGN), is expressed in developing CAs, but is downregulated by high, laminar shear stress once the vessels mature. CAs in Dach1 knockout mice are small with frequent structural abnormalities including some loss of hierarchal structure. Furthermore, Dach1 depletion in vitro decreases the proliferation and migration of coronary endothelial cells. The goal of this project is to identify the mechanisms through which Dach1 supports CA development and whether its flow-induced downregulation is necessary for maturation and/or stabilization. We hypothesize that Dach1 interacts with other RDGN members to regulate the transcription of genes essential for proper CA growth, and that this activity must be decreased during vessel maturation/stabilization due to its inhibition of BMP/SMAD- induced vascular quiescence. These hypotheses will be tested in three Aims. We will (1) identify how Dach1 influences gene transcription, whether RDGN members act as its partners, and how these interactions modulate endothelial cell behavior during CA development, (2) investigate the function of high shear stress mediated Dach1 downregulation during artery maturation, and (3) test whether Dach1 interacts with BMP/SMAD to regulate artery size. These studies will delineate how Dach1/RDGN transcriptional complexes direct arteriogenesis. They will also provide insight into the mechanisms by which hemodynamic forces regulate transcriptional programs to shape the hierarchal organization of the mature vascular tree. Knowledge of these mechanisms could be utilized stimulate the growth of existing or new arteries during disease.