Flow Responsive Mediators of Inflammation and Survival

描述（由申请人提供）：炎症有助于动脉粥样硬化的发展。动脉粥样硬化在与高剪切应力相关的稳定血流区域（称为s-flow）与受干扰和低血流区域（称为d-flow）相比减少。这一发现产生了s流是动脉粥样硬化保护和d流是动脉粥样硬化促进的概念，部分原因是引起内皮细胞（EC）功能障碍。先前我们发现s-flow激活EC中的硫氧还蛋白-1 (Trx1)，降低Trx1相互作用蛋白（Txnip）的表达，抑制肿瘤坏死因子（TNF）信号传导。一些研究结果表明，txnip依赖的信号代表了一种独特的动脉粥样硬化促进机制。1) d-flow增加Txnip表达，通过刺激VCAM-1表达促进EC粘附表型。2) Txnip特异性抑制Trx1功能，促进EC氧化应激。3) Txnip是EC中TNF- α介导的JNK和caspase-3激活所必需的。4)令人兴奋的初步数据显示，TNF使Trx1和Txnip转运到质膜上，刺激酪氨酸激酶受体（TKR）信号通路，通过Akt激活抑制细胞凋亡（图1）。最近，一种蛋白酪氨酸磷酸酶（PTPase） SHP2被证明可以刺激凋亡信号调节激酶(ASK1)-JNK-VCAM1通路。5)我们的数据显示，与SHP2结合的Txnip也激活了这一途径（图1）。因此，我们的主要假设是Txnip，像NF-kB一样，刺激EC的促生存和促炎症途径。在拟议的目标中，我们将确定将Txnip-Trx1-TKR-Akt存活途径与Txnip-SHP2-ASK1炎症途径分离的机制。目的1：证明Trx-Txnip通过组装信号复合物和抑制PTPases来刺激TKR的激活和存活。目的2：表明Txnip调节SHP2活性和亚细胞定位调节ASK1活性。目的3：表明d-flow改变Txnip的表达和位置，抑制Trx1活性并激活ASK1。目的4：表明EC特异性Txnip敲除小鼠表现出改善EC功能和减少动脉粥样硬化。这些研究应该为血流抑制炎症的机制提供见解，并促进限制动脉粥样硬化治疗方法的发展。

DESCRIPTION (provided by applicant): Inflammation contributes to development of atherosclerosis. Atherosclerosis is decreased in regions of steady flow associated with high shear stress (termed s-flow), compared to regions of disturbed and low flow (termed d-flow). This finding has yielded the concept that s-flow is atheroprotective and d-flow is atheropromoting, in part by causing endothelial cell (EC) dysfunction. Previously we showed that s-flow activated thioredoxin-1 (Trx1) in EC, decreased expression of the Trx1 interacting protein (Txnip), and inhibited tumor necrosis factor (TNF) signaling. Several findings indicate that Txnip-dependent signaling represents a unique atheropromoting mechanism. 1) Txnip expression is increased by d-flow and promotes the adhesive phenotype of EC, by stimulating VCAM-1 expression. 2) Txnip specifically inhibits Trx1 function and contributes to oxidative stress in EC. 3) Txnip is required for TNF- alpha mediated JNK and caspase-3 activation in EC. 4) Exciting preliminary data show that TNF causes Trx1 and Txnip to translocate to the plasma membrane and stimulate a tyrosine kinase receptor (TKR) signaling pathway that inhibits apoptosis via Akt activation (Fig. 1). Recently, SHP2, a protein tyrosine phosphatase (PTPase), was shown to stimulate the Apoptosis Signal-regulated Kinase (ASK1)-JNK-VCAM1 pathway. 5) Our data show that Txnip binding to SHP2 also activates this pathway (Fig. 1). Thus our major hypothesis is Txnip, like NF-kB, stimulates both pro-survival and pro-inflammatory pathways in EC. In the proposed aims we will identify mechanisms to separate the Txnip-Trx1-TKR-Akt survival pathway from the Txnip-SHP2-ASK1 inflammation pathway. Aim 1: Show that Trx-Txnip stimulates TKR activation and survival by assembling signal complexes and inhibiting PTPases. Aim 2: Show that Txnip regulates SHP2 activity and subcellular location modulating ASK1 activity. Aim 3: Show that d-flow alters Txnip expression and location inhibiting Trx1 activity and activating ASK1. Aim 4: Show that EC-specific Txnip knockout mice exhibit improved EC function and decreased atherosclerosis. These studies should provide insight into mechanisms by which flow inhibits inflammation and facilitate development of therapeutic approaches to limit atherosclerosis. PUBLIC HEALTH RELEVANCE: Strokes and heart attacks are the leading cause of death in the US. Interventions such as bypass surgery and angioplasty treat acute events, but there are limited therapies to prevent the underlying disease termed atherosclerosis. We have found that thioredoxin interacting protein is increased in blood vessels at sites where atherosclerosis develops. Here we will focus on novel approaches to inhibit the function of this protein. Elucidating the specific pathways by which thioredoxin interacting protein modulates vessel function will provide the basis to develop new therapies to prevent atherosclerosis.