FoxM1 regulates endothelial repair following lung vascular injury

描述(由申请人提供)：肺血管损伤后内皮细胞完整性的恢复是血管稳态的一个鲜为人知的方面。我们使用分子、细胞和体内方法的长期目标是阐明血管损伤后内皮屏障修复的机制，并确定新的治疗靶点，以防止与脓毒症诱导的急性肺损伤相关的持续性肺血管损伤和微血管泄漏。FOXM1是Forkhead box(FOX)转录因子家族中的一员，对细胞增殖至关重要。小鼠的FOXM1零突变导致胚胎死亡，原因是有丝分裂执行不当，从而导致心脏和肝脏中的多倍体细胞。我们将检验FOXM1是肺血管损伤后内皮修复的关键决定因素这一普遍假设。我们的目标是确定FOXM1在调节内皮细胞增殖和重新退烧内皮细胞连接，从而恢复肺血管损伤后内皮细胞完整性中的重要作用。这些研究将针对以下具体目的：1.确定肺血管损伤时FOXM1表达的调节机制。我们将剖析在脂多糖诱导的肺血管损伤后，在肺微血管中介导FOXM1诱导的信号通路。我们将通过PI3K/Akt依赖的p27Kip1下调细胞接触抑制的关键决定因素p27Kip1来检验这一假设，即肺血管损伤后内皮细胞与细胞接触的丧失诱导内皮细胞中FOXM1的表达。2.阐明FOXM1调控内皮细胞增殖的分子机制。我们将对FOXM1缺陷的肺内皮细胞的细胞周期进程中的缺陷进行表征，并确定FOXM1对内皮细胞增殖至关重要的基因转录网络。我们还将剖析FOXM1对p27Kip1的调控机制。3.探讨FOXM1在内皮细胞完整性恢复机制中的作用。我们将讨论FOXM1在肺血管损伤后内皮细胞-细胞连接的重组中发挥重要作用的可能性。我们还将检查脂多糖诱导的血管损伤后，FOXM1内皮细胞限制性缺陷小鼠肺血管渗漏和修复失败的超微结构缺陷和细胞性质。

DESCRIPTION (provided by applicant): Recovery of endothelial integrity after lung vascular injury is a poorly understood aspect of vascular homeostasis. Our long term goals using molecular, cellular, and in vivo approaches are to elucidate mechanisms of endothelial barrier repair following vascular injury and identify novel therapeutic targets to prevent persistent lung vascular injury and leaky microvessels associated with sepsis-induced acute lung injury. FoxM1 is a member of the Forkhead box (Fox) family of transcription factors essential for cell proliferation. FoxM1-null mutation in mice causes embryonic lethality due to improper execution of mitosis and the resulting polyploid cells in heart and liver. We will test the general HYPOTHESIS that FoxM1 is a critical determinant of endothelial repair following lung vascular injury. Our objective is to determine the essential role of FoxM1 in regulating endothelial cell proliferation and re-annealing endothelial junctions, thereby restoring endothelial integrity following lung vascular injury. The studies will address the following Specific Aims: 1. To determine the mechanisms of regulation of FoxM1 expression in response to lung vascular injury. We will dissect the signaling pathways that mediate FoxM1 induction in the pulmonary microvasculature following LPS-induced lung vascular injury. We will test the hypothesis that loss of endothelial cell-cell contact following lung vascular injury induces FoxM1 expression in endothelial cells through PI3K/Akt-dependent downregulation of p27Kip1, a key determinant of cell contact inhibition. 2. To elucidate the molecular mechanisms of FoxM1-regulated endothelial cell proliferation. We will characterize the defects in cell cycle progression of FoxM1 -deficient pulmonary endothelial cells and identify the FoxM1 transcriptional network of genes essential for endothelial cell proliferation. We will also dissect the mechanisms involved in FoxM1 regulation of p27Kip1. 3. To determine the role of FoxM1 in the mechanism of restoring endothelial integrity. We will address the possibility that FoxM1 plays an important role in re-organizing the endothelial cell-cell junctions following lung vascular injury. We will also examine following LPS-induced vascular injury the ultrastructural defects and the cellular nature of the leaks and repair failure of the pulmonary vasculature in mice with endothelial cell- restricted deficiency of FoxM1.