KLF2 as a regulator of endothelial cell biology

描述（由申请人提供）：血管内皮产生许多生长因子、细胞因子和生物活性介质，在健康和疾病中对血管稳态起关键的调节作用。在之前的资助期内，我们提供了证据，证明内皮细胞中转录因子KLF2的表达是由生物力学刺激（如层流剪切应力（LSS））和药理学刺激(如3-羟基-3-甲基戊二酰辅酶A还原酶抑制剂（也称为他汀类药物）诱导的。我们还证明了这两种刺激对KLF2的诱导依赖于转录因子MEF2家族的成员。旨在阐明KLF2在内皮细胞生物学中的功能的研究表明，该因子直接调节有效的抗炎和抗血栓因子如血栓调节素（TM）和内皮型一氧化氮合酶（eNOS）的表达。重要的是，也有证据表明层流或他汀类药物诱导TM和eNOS的能力依赖于KLF2。最后，我们的研究表明，KLF2可以通过其降低NFkB活性的能力，抑制细胞因子介导的促炎和促血栓因子（如组织因子和纤溶酶原激活物抑制剂-1）的诱导。与此效应一致的是，KLF2过表达增加了凝血时间，而KLF2敲低则缩短了凝血时间。综上所述，这些研究为更详细地探索KLF2的作用提供了更新应用的基础。在Aim 1中，我们将探索体外和体内流动和他汀类药物介导的KLF2诱导的分子基础。在Aim 2中，我们将确定KLF2介导的靶基因诱导的分子基础，以及KLF2缺乏对体内血管血栓形成的功能后果。最后，在Aim 3中，我们将确定KLF2介导的促炎靶基因抑制的分子基础，以及KLF2缺乏对体内动脉粥样硬化血栓形成的功能影响。我们预计这些研究将为KLF2在内皮细胞生物学中的作用提供新的和基本的见解。此外，在他汀类药物的背景下，对KLF2功能的更深入了解可能为治疗血管炎症和血栓性疾病状态的新治疗策略提供基础。

DESCRIPTION (provided by applicant): The vascular endothelium produces numerous growth factors, cytokines, and bioactive mediators that critically regulate vascular homeostasis in health and disease. During the previous funding period, we provided evidence that expression of the transcription factor KLF2 in endothelial cells is induced by biomechanical stimuli such as laminar shear stress (LSS) and pharmacologic stimuli such as 3- hydroxyl-3-methyglutaryl coenzyme A reductase inhibitors (also known as statins). We also demonstrated that this induction of KLF2 by both stimuli was dependent on members of the MEF2 family of transcription factors. Studies aimed at elucidating KLF2 function in endothelial cell biology indicate that this factor directly regulates the expression of potent anti-inflammatory and anti-thrombotic factors such as thrombomodulin (TM) and endothelial nitric oxide synthase (eNOS). Importantly, evidence was also provided that the ability of laminar flow or statins to induce TM and eNOS was KLF2 dependent. Finally, our studies demonstrated that KLF2 can inhibit cytokine-mediated induction of pro- inflammatory and pro-thrombotic factors (e.g. tissue factor and plasminogen activator inhibitor-1) through its ability to reduce NFkB activity. Consistent with this effect, KLF2 overexpression increased blood-clotting time while knockdown of KLF2 reduced blood-clotting time. Taken together, these studies provide the basis for this renewal application that will explore the role of KLF2 in greater detail. In Aim 1, we will explore the molecular basis for flow and statin-mediated induction of KLF2 in vitro and in vivo. In Aim 2, we will determine the molecular basis of KLF2 mediated-induction of target genes and the functional consequences of KLF2 deficiency on vascular thrombosis in vivo. And finally, in Aim 3, we will determine the molecular basis of KLF2 mediated-inhibition of proinflammatory target genes and the functional consequences of KLF2-deficiency on atherothrombosis in vivo. We anticipate that these studies will provide novel and fundamental insights regarding the role of KLF2 in endothelial cell biology. Furthermore, a greater understanding of KLF2 function in the context of statins may provide the foundation for novel therapeutic strategies aimed at the treatment of vascular inflammatory and thrombotic disease states. Project Narrative: Despite maximal medical therapy, cardiovascular disease remains the number one cause of morbidity and mortality in our society. As such the identification of novel treatment strategies is clearly required. Current paradigms suggest that dysfunction of the vascular endothelial cell that lines all blood vessels is a critical early event in the pathogenesis of blood vessel diseases. Our studies have identified a genetic factor that can confer favorable properties to endothelial cells and is induced by a class of medications termed statins. Our efforts are focused on developing a greater understanding of this factors role in endothelial cells with the hope that such investigations may provide the foundation for novel therapeutic strategies aimed at the treatment of vascular inflammatory disease states.