Mechanotransduction and transcriptional regulation during artery development

 项目简介：冠心病是世界范围内导致死亡的主要原因，但对冠状动脉(CA)的发育和再生仍未完全了解。动脉发育受遗传因素和机械因素的双重影响，后者涉及血液动力学因素，这些因素决定了血管床的层次结构。机械信号对于CA的发展特别重要，因为只有在未灌流的冠状神经丛连接到主动脉并开始接受血流后，才能诱导它们的分化。我们的长期目标是了解冠状血流量的起始如何转化为发育信号，从而触发CA分化并刺激其随后的成熟和稳定。我们最近发现，Dach1是果蝇视网膜决定基因网络(RDGN)中的一个转录因子，在发育中的CA中表达，但一旦血管成熟，就会受到高剪切力的下调。Dach1基因敲除小鼠的CAS较小，结构异常频繁，包括一些等级结构的丢失。此外，Dach1在体外的耗竭减少了冠状动脉内皮细胞的增殖和迁移。这个项目的目标是确定 Dach1通过它来支持CA的发展，以及它的流动诱导的下调对于成熟和/或稳定是否是必要的。我们假设Dach1与其他RDGN成员相互作用，调节CA正常生长所必需的基因的转录，并且由于它抑制BMP/SMAD诱导的血管静止，这种活性在血管成熟/稳定过程中一定会降低。这些假设将在三个目标上得到检验。我们将(1)确定Dach1如何影响基因转录，RDGN成员是否作为其合作伙伴，以及这些相互作用如何在CA发展过程中调节内皮细胞的行为，(2)研究高切应力介导的Dach1在动脉成熟过程中下调的功能，(3)测试Dach1是否与BMP/SMAD相互作用来调节动脉大小。这些研究将描绘Dach1/RDGN转录复合体如何引导动脉形成。他们还将提供对血流动力学调节转录程序以塑造成熟血管树的层级组织的机制的洞察。对这些机制的了解可以用来在疾病期间刺激现有或新的动脉的生长。

 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.