Flow Responsive Mediators of Inflammation and Survival

描述(申请人提供)：炎症有助于动脉粥样硬化的发展。与扰动和低血流区域(称为d-血流)相比，动脉粥样硬化在与高切应力相关的稳定血流区域(称为S血流)中减轻。这一发现产生了这样的概念，即S流具有动脉粥样硬化保护作用，而d流具有促进动脉粥样硬化的作用，部分原因是导致内皮细胞(EC)功能障碍。我们先前的研究表明，S流可激活EC中的硫氧还蛋白-1(Trx1)，降低Trx1相互作用蛋白(TXNIP)的表达，并抑制肿瘤坏死因子信号转导。一些发现表明，TXNIP依赖的信号代表了一种独特的促进动脉粥样硬化的机制。1)d-Flow可促进TXNIP的表达，并通过刺激VCAM-1的表达促进EC的黏附表型。2)TXNIP特异性抑制Trx1功能，促进EC的氧化应激。3)肿瘤坏死因子-α介导的JNK和caspase-3在EC的活化需要TXNIP。4)令人兴奋的初步数据显示，肿瘤坏死因子导致Trx1和TXNIP转位到质膜上，并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)。最近发现，蛋白酪氨酸磷酸酶(PTPase)SHP2可激活细胞凋亡信号调节蛋白激酶(ASK1)-JNK-VCAM1通路。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，在EC中同时刺激促进生存和促进炎症的途径。在建议的目标中，我们将确定将TXNIP-Trx1-TKR-Akt生存途径与TXNIP-SHP2-ASK1炎症途径分开的机制。目的1：证明Trx-TXNIP通过组装信号复合体和抑制PTPase来刺激TKR的激活和存活。目的2：表明TXNIP调节SHP2活性和调节ASK1活性的亚细胞定位。目的3：显示D-flow改变TXNIP的表达和定位，抑制Trx1的活性，激活ASK1。目的4：证明EC特异性TXNIP基因敲除小鼠具有改善EC功能和减少动脉粥样硬化的作用。这些研究应该为FLOW抑制炎症的机制提供洞察力，并促进限制动脉粥样硬化的治疗方法的发展。 与公共健康相关：在美国，中风和心脏病发作是主要的死亡原因。搭桥手术和血管成形术等干预措施可治疗急性事件，但预防被称为动脉粥样硬化的潜在疾病的治疗方法有限。我们发现硫氧还蛋白相互作用蛋白在动脉粥样硬化形成部位的血管中增加。在这里，我们将重点介绍抑制该蛋白质功能的新方法。阐明硫氧还蛋白相互作用蛋白调节血管功能的具体途径将为开发预防动脉粥样硬化的新疗法提供基础。

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.