Signal transduction mechanisms that mediate normal and pathologic angiogenesis

奖助金名称 介导正常和病理性血管生成的信号转导机制 摘要 肺动脉高压(PAH)是一种进行性疾病，以血管收缩、细胞 增殖和纤维化，导致肺动脉压升高，并经常导致右心衰竭 和死亡。这种疾病没有治愈的办法。因此，新的机制研究和新的治疗策略 都是迫切需要的。PAH患者血浆细胞因子升高是炎症的标志。作为少校 作为效应器，单核细胞释放细胞因子，并渗入肺血管周围区域。单核细胞耗竭 减轻PAH动物模型的血管重塑和血流动力学改变。这一证据表明 单核细胞和内皮细胞(ECs)之间的通讯。然而，潜在的机制并不是 很好理解。当前提案的目的是定义裂解的胞外结构域的作用 Deltalike 4(ExD114)在PAH发病机制中的作用在体外，我们发现钙调蛋白1可以 切开Dll4。我们还发现，肿瘤坏死因子和IL-1增加了人单核细胞DLL4的表达，DLL4的裂解， 单核细胞释放exD114。此外，我们还发现，重组exDll4显著增加了 内皮细胞凋亡和屏障功能降低。在寻找作用机制时，我们发现exDll4与 与完整的DLL4结合，这种相互作用阻止DLL4与Notch1结合，从而抑制Notch1的激活。在体内， 我们发现PAH小鼠单核细胞中DLL4的表达和exDLL4的释放显著增加 在PAH患者中。然而，在小鼠和大鼠的PAH进展过程中，Notch1信号在肺中减少。 基于这些发现，我们假设来自单核细胞的exDLL4通过以下方式对PAH的进展起关键作用 诱导肺内皮细胞凋亡，损害屏障功能。从机理上讲，exD114与其他分子形成杂二聚体 DLL4来阻止DLL4和Notch1的关联，从而阻止Notch1信令。为了检验我们的假设，我们建议 三个目标。目的1.明确单核细胞DLL4表达和exDL4释放的调节机制 啊哈。目的2.探讨exDL4-Notch1在肺内皮细胞中的生物学功能及其分子机制。目标 3.研究抑制单核细胞DLL4对PAH进展的治疗作用。实现这些目标 AIMS将1)填补关于血管重塑和EC功能障碍机制的知识空白 单核细胞来源的exDL4介导的PAH的发病机制：2)揭示了DLL4裂解的调节；3) 通过靶向单核细胞DLL4，发明一种治疗PAH的新策略。

Title of the grant Signal transduction mechanisms that mediate normal and pathologic angiogenesis Abstract Pulmonary arterial hypertension (PAH) is a progressive disease, characterized by vasoconstriction, cell proliferation, and fibrosis, leading to elevated pulmonary arterial pressure and often causing right heart failure and death. There is no cure for this disease. Therefore, novel mechanistic studies and new therapeutic strategies are urgently needed. Elevation of plasma cytokines in PAH patients is a hallmark of inflammation. As the major effector, monocytes release cytokines and infiltrate in perivascular regions of the lung. Depletion of monocytes attenuates vascular remodeling and hemodynamic changes in PAH animal models. This evidence implies a communication between monocytes and endothelial cells (ECs). However, the underlying mechanisms are not well understood. The objective of the current proposal is to define the role of extracellular domain of cleaved delta like 4 (exDll4) in the pathogenesis of PAH and its mechanisms. In vitro, we discovered that calpain1 can cleave Dll4. We also found that TNF and IL-1 increases Dll4 expression, Dll4 cleavage in human monocyte, and exDll4 release from monocytes. Furthermore, we found that recombinant exDll4 significantly increased apoptosis and decreased barrier function in ECs. Seeking the mechanism of action, we found exDll4 associated with intact Dll4, and this interaction prevents Dll4 binding to Notch1 and thus inhibits Notch1 activation. In vivo, we found that Dll4 expression and exDll4 release in monocyte are significantly elevated in PAH mice as well as in PAH patients. However, Notch1 signaling is decreased in lungs during PAH progression in mice and rats. Based on these findings, we hypothesize that exDll4 derived from monocytes is crucial for PAH progression by inducing apoptosis and impairing barrier function in lung EC. Mechanistically, exDll4 forms a heterodimer with Dll4 to prevent the association of Dll4 and Notch1, blocking Notch1 signaling. To test our hypothesis, we propose three aims. Aim 1. Define the regulatory mechanisms of Dll4 expression and exDll4 release from monocyte in PAH. Aim 2. Determine the biological function of exDll4-Notch1 in lung EC and its molecular mechanisms. Aim 3. Characterize the therapeutic effects of inhibiting monocyte Dll4 on PAH progression. Accomplishing these aims will 1) fill the knowledge gap regarding the mechanisms of vascular remodeling and EC dysfunction in the pathogenesis of PAH mediated by monocyte derived exDll4; 2) reveal the regulation of Dll4 cleavage; and 3) invent a novel therapeutic strategy for PAH by targeting monocyte Dll4.