Novel mechanisms of vasculogenesis

项目摘要 多种血管疾病，包括高血压、糖尿病、动脉粥样硬化和其他相关疾病 血管内皮细胞功能障碍。然而，目前还没有有效的方法来结合 体内新的内皮细胞进入受损的血管，有助于血管的再生和修复。 新血管的形成有两种不同的机制，即血管生成，即分化 血管内皮细胞新生和血管生成，通过从现有血管分支形成新血管 船只。目前认为，血管生成在很大程度上局限于最初的血管网络 胚胎发生，而后者的大多数血管是由现有的维管系统形成的。 虽然很难研究哺乳动物胚胎中的血管生成，但斑马鱼已经成为一种 研究血管发育的有利模型体系。控制血管的分子机制 包括斑马鱼和人类在内的所有脊椎动物的发育都高度保守。 在这里，我们在斑马鱼胚胎中发现了一个新的推测的血管祖细胞群体。 这些细胞表现出ETS转录因子ETV2的高表达，ETV2是已知的血管生成的关键调节因子， 并位于原肾(原肾相关细胞，PAC)附近。我们的初步数据显示 PAC是器官特异性血管形成的主要来源，它们对胚胎血管形成有贡献 通过一种新的细胞嵌入功能血管的机制。我们的数据进一步表明，PAC 在哺乳动物胚胎中可能是保守的。此外，我们还鉴定了连接性黏附分子 Jam2b作为PAC形成所需的关键调控因子之一。我们假设PAC是一组新的 多能血管前体细胞，为血管生长提供重要贡献。 提出了以下具体目标：1)确定PAC对不同类型血液的贡献 血管；2)确定PAC在血管发育中的功能作用；3)确定Jam2b和其他 上游调节因子参与PAC的形成和血管发育。血统追踪方法将是 用于确定PAC对斑马鱼胚胎中不同类型血管的贡献。PAC消融 和ETV2条件抑制策略将被用于测试PAC在斑马鱼中的功能作用，以及它们的 在小鼠胚胎中的形成也将被研究。JAM2B在PAC形成中的作用及其与PAC的相互作用 将分析斑马鱼中血管内皮生长因子的信号转导途径，以及其他富含PAC基因的功能作用。 本提案中获得的数据将回答有关身份和功能角色的关键问题 PAC，并可能揭示血管生长的新机制。血管生成的机制 是高度保守的，我们的初步数据表明，类似的祖先也存在于 哺乳动物的胚胎。理解PAC如何形成和融入现有的机制 血管造影术可能会为修复受损的血管提供一个新的治疗方向。

Project Summary Multiple vascular diseases including hypertension, diabetes, atherosclerosis, and others are associated with the dysfunction of vascular endothelium. However, there are currently no effective methods to incorporate new endothelial cells into damaged vessels in vivo which could contribute to vascular regeneration and repair. New blood vessels form by two distinct mechanisms, vasculogenesis, which is differentiation of vascular endothelial cells de novo, and angiogenesis, formation of new vessels by branching from the existing vessels. It is currently thought that vasculogenesis is largely limited to the initial vascular network during embryogenesis, while the majority of the later vessels form by angiogenesis from the existing vasculature. While it is difficult to study vasculogenesis in the mammalian embryos, zebrafish has emerged as an advantageous model system to study vascular development. Molecular mechanisms that control vascular development are highly conserved between all vertebrates including zebrafish and humans. Here we have discovered a novel population of putative vascular progenitors in the zebrafish embryos. These cells show high expression of ETS transcription factor etv2, a known key regulator of vasculogenesis, and are located adjacent to the pronephros (pronephros-associated cells, PACs). Our preliminary data indicate that PACs are the major source of organ specific vasculature, and they contribute to the embryonic vasculature by a novel mechanism of cell intercalation into functional blood vessels. Our data further suggest that PACs are likely conserved in mammalian embryos. In addition, we have identified Junctional Adhesion Molecule Jam2b as one of key regulators required for PAC formation. We hypothesize that PACs are a novel group of multipotent vascular progenitors which provide important contribution for vascular growth. The following specific aims are proposed: 1) Define contribution of PACs to different types of blood vessels; 2) Identify functional role for PACs in vascular development; 3) Identify the role of Jam2b and other upstream regulators in the formation of PACs and vascular development. Lineage tracing approaches will be employed to determine contribution of PACs to different types of vessels in zebrafish embryos. PAC ablation and etv2 conditional inhibition strategies will be used to test the functional role of PACs in zebrafish, and their formation will also be investigated in murine embryos. The role of jam2b in PAC formation, its interaction with Vegf signaling pathway, and functional roles of other PAC-enriched genes will be analyzed in zebrafish. Data obtained in this proposal will answer the key questions regarding the identity and functional role of PACs, and are likely to uncover a novel mechanism of vascular growth. The mechanisms of vasculogenesis are highly conserved, and our preliminary data suggest that similar progenitors are also present in the mammalian embryos. Understanding the mechanism of how PACs form and incorporate into existing vasculature may lead to a new direction to repair damaged vessels for therapeutic purposes.