Mechanisms that Govern Vasculogenesis

项目总结/摘要 缺血性心脏病（IHD）是世界上主要的死亡原因，目前的治疗方法是有限的， 无法促进受伤心脏的肌肉再生。在没有肌肉再生的情况下， 心脏在心肌梗死（MI）后形成疤痕，可进展为心力衰竭。不足 血管和灌注受损是影响IHD发病率和死亡率的关键因素。 这些心血管疾病是慢性的、使人衰弱的、致命的，并且它们需要开发新的治疗方法。 治疗一种方法是促进血管发生以增强心脏再生。临床试验 使用外源性因素治疗IHD显示出相互矛盾的结果， 这些因素驱动血管生成。因此，可以完全驱动血管生成的新疗法 IHD的治疗是必要的。我们的实验室已经表明，ets变异因子2（ETV 2）是一种转录因子， 这是必要的和足够的发展的血内皮细胞（HE）谱系的损失， ETV 2由于缺乏所有血液和脉管系统而具有胚胎致死性。我们最近的证据显示， 实验室表明ETV 2作为HE谱系的先驱转录因子发挥作用。先锋转录 因子结合和松弛凝聚的染色质，以驱动基因表达的变化， 细胞谱系的发育或特化。我们的初步数据显示，ETV 2与 BRG 1，一种染色质重塑酶，已被证明与其他先驱转录因子合作， 不同血统的发展因素。然而，目前尚不清楚ETV 2-BRG 1相互作用如何影响 与HE的发展和ETV 2的先锋作用有关。此外，ETV 2的过表达已经被证实是一种新的基因表达。 显示出在体外将成纤维细胞重编程为功能性内皮细胞。目前尚不清楚ETV 2是否 过表达可以在大型动物模型中体内用于在MI后重编程成纤维细胞以增强成纤维细胞的功能。 血管生成以治疗IHD。因此，本提案的总体目标是开发治疗性药物， 通过了解控制血管发生的机制来制定IHD的策略。我假设ETV 2驱动 HE谱系以BRG 1依赖的方式发育，体内ETV 2的过表达将增强 通过促进血管生成来实现心脏再生。我将通过追求以下目标来检验这一假设：（1） 确定BRG 1在HE谱系中ETV 2的先锋功能中的作用，以及（2）确定BRG 1在HE谱系中ETV 2的能力。 使用猪模型进行心脏损伤后ETV 2的体内重编程。完成这些研究将 增强我们对ETV 2作为先锋因子如何靶向和松弛细胞中浓缩的染色质的理解。 BRG 1依赖性方式驱动HE发育和血管发生。这些研究还将确定新的 机制，可以加强重编程策略，并可能导致新的发展 治疗心血管疾病。

PROJECT SUMMARY/ABSTRACT Ischemic heart disease (IHD) is the leading cause of death in the world and current therapies are limited due to the inability to promote remuscularization of the injured heart. In the absence of remuscularization, the injured heart forms a scar following a myocardial infarction (MI) that can progress towards heart failure. Insufficient vasculature and impaired perfusion are critical factors affecting the morbidity and mortality observed in IHD. These cardiovascular diseases are chronic, debilitating, lethal and they warrant the development of novel therapies. One approach is to promote vasculogenesis in order to enhance heart regeneration. Clinical trials using exogenous factors to treat IHD have shown conflicting results that have been attributed to the inability of such factors to drive vasculogenesis. Therefore, new therapies that can fully drive vasculogenesis for the treatment of IHD are warranted. Our laboratory has shown that the ets variant factor 2 (ETV2) is a transcription factor that is both necessary and sufficient for the development of hematoendothelial (HE) lineages as loss of ETV2 is embryonically lethal due to the absence of all blood and vasculature. Recent evidence from our laboratory suggests that ETV2 functions as a pioneer transcription factor for the HE lineage. Pioneer transcription factors bind and relax condensed chromatin in order to drive gene expression changes necessary for the development or specification of cell lineages. Our preliminary data shows that ETV2 physically interacts with BRG1, a chromatin remodeling enzyme, which has been shown to collaborate with other pioneer transcription factors in the development of different lineages. However, it remains unclear how ETV2-BRG1 interactions might be related to HE development and the pioneer function of ETV2. Furthermore, overexpression of ETV2 has been shown to reprogram fibroblasts into functional endothelial cells in vitro. However, it is not known whether ETV2 overexpression can be used in vivo in a large animal model to reprogram fibroblasts after a MI to enhance vasculogenesis in order to treat IHD. Therefore, the overall goal of this proposal is to develop therapeutic strategies for IHD by understanding the mechanisms that govern vasculogenesis. I hypothesize that ETV2 drives HE lineage development in a BRG1 dependent fashion and that in vivo overexpression of ETV2 will enhance cardiac regeneration by promoting vasculogenesis. I will test this hypothesis by pursuing the following aims: (1) to define the role of BRG1 in the pioneer function of ETV2 in the HE lineage, and (2) to define the capacity of in vivo reprogramming by ETV2 following cardiac injury using a swine model. Completion of these studies will enhance our understanding of how ETV2, as a pioneer factor, targets and relaxes condensed chromatin in a BRG1-dependent fashion to drive HE development and vasculogenesis. These studies will also identify new mechanisms that can enhance reprogramming strategies and potentially lead to the development of new therapies for cardiovascular disease.