Flow Responsive Mediators of Inflammation and Survival

摘要/摘要 炎症在动脉粥样硬化的发展中起重要作用。动脉粥样硬化在稳定的区域减轻 与高剪应力相关的流动(称为S流)，与扰动区和低流区(称为 D-Flow)。这一发现产生了S流是动脉粥样硬化保护的概念，而d流是促进动脉粥样硬化的概念。 部分原因是导致内皮细胞(EC)功能障碍。先前我们发现S-Flow激活硫氧还蛋白-1 (Trx1)在EC中，减少Trx1相互作用蛋白(TXNIP)的表达，并抑制肿瘤坏死因子 (肿瘤坏死因子)信号。一些发现表明，TXNIP依赖的信号转导代表了一种独特的促进动脉粥样硬化的机制 机制。1)D-Flow促进TXNIP的表达，促进黏附 EC的表型，通过刺激VCAM-1的表达。2)TXNIP特异性抑制Trx1 在EC中起作用并促进氧化应激。3)肿瘤坏死因子需要TXNIP- 介导内皮细胞JNK和caspase-3的激活。4)令人兴奋的初步数据显示 肿瘤坏死因子导致Trx1和TXNIP移位到质膜并刺激 酪氨酸激酶受体(TKR)信号通路通过Akt抑制细胞凋亡 激活(图1)。最近，蛋白酪氨酸磷酸酶(PTPase)SHP2被发现。 激活细胞凋亡信号调节蛋白1-JNK-VCAM1 路径。5)我们的数据表明，TXNIP与SHP2的结合也激活了这一途径(图4)。 1)。因此，我们的主要假设是，TXNIP和核因子-kB一样，既能刺激促生存，又能刺激 EC中的促炎途径。在拟议的目标中，我们将确定以下机制 将TXNIP-Trx1-TKR-Akt生存通路与TXNIP-SHP2-ASK1分离 炎症途径。目的1：显示TRX-TXNIP刺激TKR激活和 通过组装信号复合体和抑制PTPase存活。目的2：证明TXNIP调节SHP2 调节ASK1活性的活性和亚细胞定位。目的3：证明D-Flow改变TXNIP的表达和 抑制Trx1活性和激活ASK1的位置。目的4：显示EC特异性TXNIP基因敲除小鼠表现出 改善内皮细胞功能，减少动脉粥样硬化。这些研究应该提供对机制的洞察 通过这种流动抑制炎症并促进治疗方法的发展，以限制 动脉硬化。

Abstract/Summary 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- 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.