Tyrosine Phosphatases and Endothelial Dysfunction

研究表明，肾素-血管紧张素系统(RAS)和活性氧(ROS)影响血管内皮功能，并参与高血压、动脉粥样硬化和心力衰竭相关的心血管重构。RAS和ROS促进纤溶酶原激活物抑制物-1(PAI-1)的表达，从而破坏纤溶平衡。RAS和ROS还刺激内皮细胞-白细胞黏附分子的表达，促进单核细胞与内皮细胞单层的黏附，这是动脉粥样硬化发病机制中最早发现的事件。然而，血管紧张素II(Ang II)和ROS调控这些基因表达的分子机制在很大程度上还不清楚。我们已经证明，酪氨酸磷酸酶SHP-2的活性在血管紧张素II 1型受体(AT1)的信号转导中起着负面作用。我们还积累了大量的初步数据，表明酪氨酸磷酸酶SHP-2和SHP-1是ROS的直接靶点，可能调节内皮细胞中的ROS活动。这些研究将验证酪氨酸磷酸酶SHP-2和SHP-1在RAS和ROS介导的血管内皮细胞PAI-1和细胞黏附分子表达中起重要作用的假设。利用培养的内皮细胞，我们将：1)确定SHP-2活性在Ang II诱导的内皮功能障碍中的作用；2)揭示SHP-2影响AT1受体信号转导的机制；3)确定SHP-1和SHP-2在ROS介导的信号转导和基因表达中的作用和机制。目前的方法结合了分子、生化和细胞生物学方法，将产生关于酪氨酸磷酸酶SHP-1和SHP-2在RAS和ROS介导的内皮功能障碍中的作用和机制的关键信息，并将导致确定心血管疾病治疗中的特定干预部位。

Studies have indicated that renin-angiotensin system (RAS) and reactive oxygen species (ROS) impact on , endothelial function and are involved in cardiovascular remodeling associated with hypertension, atherosclerosis and heart failure. RAS and ROS promote the expression of plasminogen activator inhibitor-1 (PAI-1), thus interrupting the balance of fibrinolysis. RAS and ROS also stimulate the expression of endothelial-leukocyte adhesion molecules and promote the adhesion of monocytes to monolayers of endothelial cells, which is the earliest detectable event in the pathogenesis of atherosclerosis. However, the molecular mechanisms of angiotensin II (Ang II) and ROS in the regulation of these genes expression are largely unknown. We have demonstrated that enzymatic activity of tyrosine phosphatase SHP-2 plays a negative role in the signal transduction of angiotensin II type-1 receptor (AT1). We also have accumulated substantial preliminary data indicating that tyrosine phosphatases SHP-2 and SHP-1 are the direct targets of ROS and may regulate ROS actions in endothelial cells. The proposed studies will test the hypothesis that tyrosine phosphatases SHP- 2 and SHP-1 play important roles in RAS- and ROS-mediated expression of PAI-1 and cell adhesion molecules in endothelial cells. Using cultured endothelial cells, we will :1) Determine the role of SHP-2 activity in Ang II-induced endothelial dysfunction; 2) Reveal mechanisms by which SHP-2 affects AT1 receptor signal transduction; and 3) Determine roles and mechanisms of SHP-1 and SHP-2 in ROS-mediated signal transduction and gene expression. The present approach, in which molecular, biochemical and cell biological methods are combined, will generate critical information regarding the roles and mechanisms of tyrosine phosphatases SHP-1 and SHP-2 in RAS- and ROS-mediated endothelial dysfunction and will lead to the identification of specific sites of intervention in the treatment of cardiovascular diseases.