FLOW SHEAR INDUCED NF-KB MEDIATED REGULATION

动脉粥样硬化病变通常发生在低切变区。发生这些损害的机制还知之甚少。我们的长期目标是开发新的介入程序和药物的策略，以控制增强的内皮-单核细胞(EN-MN)黏附，从而有利于疾病的发展。最近，我们报道了长时间的低切应力，而不是高切应力，导致了关键的转录调节因子NF-kappaB在人主动脉内皮细胞(HAEC)的持续激活。本研究的目的是确定在HAEC中长时间低切应力和高切应力条件下，导致核因子-kappaB差异激活的介质。中心假说是剪切力诱导的活性氧(ROS)通过对上游信号机制的不同调节来介导核因子-kappaB的激活。这些机制决定了在易病变的低切变区和高切变区，介导动脉粥样硬化形成的炎症事件的不同。这一假说将通过三个特定的目的来检验：1)确定调节NF-kappaB激活的上游信号机制；2)确定ROS可能触发上游信号通路激活的作用；3)研究AP-1和八聚体结合蛋白在低切和高切暴露的HAEC中对NF-kappaB介导的血管细胞黏附分子(VCAM-1)基因表达的差异调控中的作用。这项研究的基本原理是，一旦确定了在低切应力下调节NF-kappaB持续激活的关键因子，就有可能调控参与EN-MN黏附的NF-kappaB介导的VCAM-1的表达。结果将是重要的，因为确定核因子-kappaB信号通路涉及的机制将识别有利于EN-MN粘附性增强的关键介质，从而导致疾病的发展。这一知识将有助于开发选择性靶向这些介体的新治疗策略。了解NF-kappaB在VCAM-1调节中的信号机制也可应用于其他炎症条件。

Atherosclerotic lesions typically occur in areas of low shear flow regions. The mechanisms involved in developing these lesions are poorly understood. Our long-term goal is to develop strategies for novel interventional procedures and agents to control enhanced endothelial-monocyte (En-Mn) adhesion that favors the development of the disease. Recently, we reported that prolonged low shear, as opposed to high shear stress, causes a persistent activation of the key transcriptional regulator NF- kappaB in human aortic endothelial cells (HAEC). The objective of this proposal is to identify the mediators that cause the differential activation of NF-kappaB in prolonged low and high shear stress in HAEC. The central hypothesis is that shear stress-induced reactive oxygen species (ROS) mediate activation of NF-kappaB through differential regulation of upstream signaling mechanisms. These mechanisms determine the differences in the inflammatory events mediating the development of atherogenesis in lesion prone low shear areas and resistant high shear regions. The hypothesis will be examined by three specific aims: 1) To determine the upstream signaling mechanisms that regulate the activation of NF-kappaB; 2) To ascertain the role of ROS that would possibly trigger activation of the upstream signaling kinases; and 3) To investigate the role of Ap-1 and octamer binding protein in the differential regulation of the NF- kappaB mediated vascular cell adhesion molecule (VCAM-1) gene expression in low and high shear exposed HAEC. The rationale of this study is that once the key players that regulate the persistent activation of NF-kappaB in low shear stress are identified, it will be possible to modulate the expression of NF- kappaB mediated VCAM-1 expression involved in En-Mn adhesion. The outcome would be significant because ascertaining the mechanisms involved in the NF-kappaB signaling pathway would identify key mediators that favor the enhanced En-Mn adhesion that leads to the development of the disease. This knowledge would help in developing novel therapeutic strategies for selective targeting of those mediators. Understanding of NF- kappaB signaling mechanisms in VCAM-1 regulation can also be applied to other inflammatory conditions.