FLOW SHEAR INDUCED NF-KB MEDIATED REGULATION

动脉粥样硬化病变通常发生在低剪切血流区。这些病变发生的机制尚不清楚。我们的长期目标是开发新的介入手术策略和药物，以控制有利于疾病发展的内皮-单核细胞（En-Mn）粘附增强。最近，我们报道了长时间的低剪切，而不是高剪切，导致人主动脉内皮细胞（HAEC）中关键转录调节因子NF- kappaB的持续激活。本提案的目的是确定在长时间的低剪切应力和高剪切应力下导致HAEC中NF-kappaB差异激活的介质。核心假设是剪切应力诱导的活性氧（ROS）通过上游信号机制的差异调节介导NF-kappaB的激活。这些机制决定了炎症事件在病变易发低剪切区和抵抗高剪切区介导动脉粥样硬化发展的差异。该假设将通过三个具体目标进行检验：1)确定调节NF-kappaB激活的上游信号机制；2)确定可能触发上游信号激酶激活的ROS的作用；3)探讨Ap-1和八聚体结合蛋白在低、高剪切暴露HAEC中NF- kappaB介导的血管细胞粘附分子（VCAM-1）基因表达的差异调控中的作用。本研究的基本原理是，一旦确定了在低剪切应力下调节NF-kappaB持续激活的关键因素，就有可能调节NF-kappaB介导的参与En-Mn粘附的VCAM-1表达。这一结果意义重大，因为确定NF-kappaB信号通路的机制将确定促进En-Mn粘附增强的关键介质，从而导致疾病的发展。这一知识将有助于开发新的治疗策略，选择性靶向这些介质。了解NF- kappaB信号在VCAM-1调节中的作用机制也可以应用于其他炎症情况。

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.