Regulation of thrombospondin-1 expression by glucose

描述(申请人提供)：血管并发症是糖尿病患者死亡人数最多的原因。然而，导致这些并发症的分子机制仍然知之甚少。我们最近报道，血栓反应蛋白-1(TSP-1)在2型糖尿病动物模型Zucker大鼠的大血管中表达显著升高，无论是在基础状态下还是在损伤反应中，提示该蛋白在该动物模型和糖尿病患者动脉粥样硬化加速和再狭窄增加中发挥了作用。TSP-1具有大量有文献记载的致动脉粥样硬化特性，包括遗传和生化证据，也是最有效的抗血管生成剂之一，这一功能与糖尿病并发症直接相关。我们的初步数据表明，TSP-1的表达在转录水平上受到葡萄糖的调控，并提示了这种激活的可能信号通路。我们将验证一种假设，即高糖急性刺激动脉平滑肌细胞(SMC)后迅速激活的特定信号和转录分子机制介导了大血管壁上TSP-1表达的增加，并在高血糖和加速的动脉粥样硬化之间提供了联系。该项目的总体目标是阐明葡萄糖上调SMC中TSP-1表达的特定信号和转录机制，并测试TSP-1在血管壁上的表达增加是否有助于动脉粥样硬化病变的发展。长期目标是揭示高血糖导致血管并发症发生的分子机制。其具体目的是：1.确定TSP-1基因的启动子区域和葡萄糖上调TSP-1的核因子；2.确定葡萄糖调节TSP-1表达的信号通路；3.在转基因小鼠模型中直接证明TSP-1在血管壁的表达增加有助于动脉粥样硬化病变的发展。这些实验的结果将：1)确定TSP-1的调控靶点，TSP-1是一种可能导致血管糖尿病并发症的强大的抗血管生成和促动脉粥样硬化蛋白；2)提供关于葡萄糖对SMC影响的分子机制的更多信息；以及3)直接证明TSP-1可能是糖尿病和血管并发症之间的联系。

Description (provided by applicant): Vascular complications account for the greatest numbers of deaths in diabetic patients. However, the molecular mechanisms responsible for these complications remain poorly understood. We recently reported that the expression of thrombospondin-1 (TSP-1) is strikingly elevated in large vessels of Zucker rats, an animal model of type 2 diabetes, both in basal conditions and in response to injury, suggesting a role for this protein in the accelerated atherosclerosis and increased restenosis in this animal model and diabetic patients. TSP-1 has a number of well-documented proatherogenic properties, including genetic and biochemical evidence, and is also one of the most potent antiangiogenic agents, a function directly relevant to diabetic complications. Our preliminary data indicated that TSP-1 expression is regulated by glucose at the transcriptional level and suggested possible signaling pathways for this activation. We will test the hypothesis that specific signaling and transcriptional molecular mechanisms rapidly activated by acute stimulation of arterial smooth muscle cells (SMC) with high glucose mediate the increased expression of TSP-1 in the wall of large blood vessels and provide a link between hyperglycemia and accelerated atherogenesis. The overall goal of the proposed project is to elucidate specific signaling and transcriptional mechanisms responsible for the upregulation of TSP-1 expression by glucose in SMC and to test whether that increased expression of TSP-1 in the vascular wall contributes to the development of atherosclerotic lesions. The long-term objective is to uncover the hyperglycemia-induced molecular mechanisms that lead to development of vascular complications. Specific Aims are: 1. To identify the promoter region of the TSP-1 gene and nuclear factors responsible for the upregulation of TSP-1 by glucose; 2. To identify signaling pathways involved in regulation of TSP-1 expression by glucose; 3. To demonstrate directly in the transgenic mouse model that increased expression of TSP-1 in the vascular wall contributes to the development of atherosclerotic lesions. The results of these experiments will: 1) identify targets for the regulation of TSP-1, a potent antiangiogenic and proatherogenic protein that may contribute to vascular diabetic complications; 2) provide additional information about the molecular mechanisms of the effects of glucose in SMC; and 3) demonstrate directly that TSP-1 may serve as a link between diabetes and vascular complications.