Notch Signaling in Mouse Arterial-Venous Specification

描述（由申请人提供）：我们的长期目标是确定哺乳动物血管系统正常发育和维持的分子机制，并阐明血管发病机制下的分子病变。最近在斑马鱼身上进行的实验表明，Notch表达促进动脉发育，而其下调导致静脉的默认发育。尽管在斑马鱼中有这些发现，小鼠敲除实验表明Notch在哺乳动物动静脉（AV）发育中的作用更为复杂。此外，确切的细胞和分子事件仍有待确定。为了确定Notch通路在小鼠胚胎和成年AV分化中的功能，我们的实验室开发了一种小鼠模型，在该模型中，一种构成型活性形式的Notch仅在内皮细胞中表达。此外，激活的Notch表达是暂时可调节的，从而使我们能够检查其在发育和成人血管系统中的作用。利用这个和其他Notch突变体，我们将实现以下具体目标：确定Notch在胚胎AV分化中的作用（目的1）；定义Notch在成人AV身份维持中的作用（目的2）；定义Notch指定动脉和静脉分化的细胞机制（目标3）；并确定Notch在内皮细胞中触发的分子事件（Aim 4）。本研究的具体目的，包括形态学、细胞和分子分析，包括内皮细胞Notch的功能获得和功能丧失研究。这些努力将揭示Notch在血管分化和维持中的作用，并阐明这些过程的潜在分子机制。在未来，对Notch在哺乳动物产前和产后血管功能中的基本认识将指导其在病理条件下的功能研究，如缺血性侧支动脉形成。最终，我们对Notch通路的理解可能会导致对血管疾病的新药物靶点和治疗干预的鉴定。

DESCRIPTION (provided by applicant): Our long-term goal is to ascertain the molecular mechanisms responsible for the normal development and maintenance of the mammalian vasculature and to elucidate molecular lesions underlying vascular pathogenesis. Recent experiments performed on zebrafish have suggested that Notch expression provokes arterial development while its down-regulation results in the default development of veins. Despite these findings in zebrafish, mouse knockout experiments suggest Notch's role in mammilian arterial-venous (AV) development is more complex. Furthermore, the precise cellular and molecular events remain to be defined. To determine the function of the Notch pathway in AV differentiation both in mouse embryos and adults, our lab has developed a mouse model, in which a constituitively active form of Notch is expressed exclusively in endothelial cells. Furthermore, the activated Notch expression is temporally regulatable, thereby allowing us to examine its effects in both developmental and adult vasculature. Using this and other Notch mutants, we will accomplish the following specific aims: define the role of Notch in embryonic AV differentiation (Aim 1); define the role of Notch in adult maintenance of AV identity (Aim 2); define the cellular mechanisms by which Notch specifies differentiation of arteries and veins (Aim 3); and identify the molecular events triggered by Notch in endothelial cells (Aim 4). The specific aims of this study, engaging morphological, cellular, and molecular analyses, entail both gain-and loss-of-function studies of Notch in endothelial cells. These efforts will reveal the role of Notch in vascular differentiation and maintenance and illuminate potential molecular mechanisms underlying these processes. In the future, this basic understanding of Notch in pre and postnatal mammalian vascular function will guide investigations into its function under pathological conditions, such as ischemic collateral artery formation. Ultimately, our understanding of the Notch pathway may lead to the identification of novel drug targets and therapeutic interventions to vascular diseases.