Role of CD148 Tyrosine Phosphatase in Diabetic Nephropathy

描述(申请人提供)：糖尿病肾病是终末期肾病的主要病程。尽管涉及多种细胞类型，但糖尿病肾病本质上是一种微血管疾病，是血流动力学和代谢紊乱共同作用的结果。血管内皮细胞及其紊乱在本病中起主要作用。在过去的十年中，大量的研究表明，血管生成信号过多和肾小球内皮细胞生长失控是糖尿病肾病的一个关键发病机制。血管内皮生长因子/血管内皮生长因子受体被证明是这一过程的驱动力。然而，抗血管生成途径在本病中的作用尚不清楚，但血管生成信号的大小和光谱由血管生成信号和反血管生成信号之间的平衡决定。鉴于内皮受体蛋白酪氨酸激酶(RPTKs)在血管生成信号转导中起主要作用，我们提出了RPTKs的对偶酶--内皮受体蛋白酪氨酸磷酸酶(RPTPs)可能诱导抗血管生成信号的假说。我们已经从肾小球内皮细胞中分离到一种受体类型的PTP CD148，表明CD148具有抑制内皮生长因子信号(包括VEGFR)、抑制内皮细胞生长和血管生成的强大活性。此外，我们最近发现，血栓反应蛋白-1(TSP1)，一种抗血管生成蛋白，作为CD148的配体。这些发现表明CD148在肾小球血管生成反应中起着关键的调节作用。因此，在本申请中，我们定义了CD148在糖尿病肾病中的作用。根据我们的初步数据和CD148的抗血管生成活性，提出了以下假设：1)糖尿病肾小球内皮细胞CD148的表达/活性降低。这增强了血管生成内皮生长因子信号(包括VEGFR)，促进了糖尿病肾病的发生和发展。2)激活CD148抑制糖尿病肾小球内皮细胞血管生成生长因子信号，恢复糖尿病肾病的功能和结构改变。在目标1中，我们将通过使用条件基因敲除和转基因小鼠来调控糖尿病小鼠的CD148表达，以确定CD148在糖尿病肾病中的作用。在AIM2中，我们将通过用CD148激动剂、特定的TSP1片段和激动型抗体治疗糖尿病小鼠来确定CD148激活在糖尿病肾病中的作用。目的3通过在高糖培养的糖尿病肾小球内皮细胞和体内(小鼠)糖尿病肾小球中敲除或激活CD148，研究CD148对糖尿病肾小球内皮细胞CD148调节的内皮信号和功能。因此，这些研究将明确CD148抗血管生成通路在糖尿病肾病中的作用，并探索治疗该疾病的新策略。

DESCRIPTION (provided by applicant): Diabetic nephropathy (DN) is the leading course of end-stage renal disease. Although multiple cell types are involved, DN is in essence a microvascular disease that develops as a result of a confluence of hemodynamic and metabolic perturbations. Endothelial cells and its disorders play a major role in this disease. In the past decade, a large body of studies has shown that excessive angiogenic signals and unregulated glomerular endothelial growth is a key pathogenic mechanism of DN. VEGF/VEGFR was shown to serve as a driving force of this. However, the role of anti-angiogenic pathway in this disease is largely unknown, yet the magnitude and spectrum of angiogenic signals are determined by the balance between angiogenic and anti- angiogenic signals. Given the fact that endothelial receptor protein tyrosine kinases (RPTKs) play a major role in transduction of angiogenic signals, we have advanced the hypothesis that endothelial receptor protein tyrosine phosphatases (RPTPs), counter-enzymes of RPTKs, may induce anti-angiogenic signals. We have isolated a receptor-type PTP CD148 from glomerular endothelial cells and shown that CD148 has a potent activity in suppressing endothelial growth factor signals (including VEGFR) and in inhibiting endothelial cell growth and angiogenesis. Further, we have recently found that thrombospondin-1(TSP1), an anti-angiogenic protein, acts as a ligand for CD148. These findings suggest that CD148 functions as a key regulator of glomerular angiogenic response. In this application we therefore define the role of CD148 in DN. Based on our preliminary data and anti-angiogenic activity of CD148, the following hypotheses were advanced; 1) CD148 expression/activity is decreased in diabetic glomerular endothelium. This enhances angiogenic endothelial growth factor signals (including VEGFR) and promotes the development and progression of DN. 2) Activation of CD148 suppresses angiogenic growth factor signals in diabetic glomerular endothelium and restores the functional and structural changes of DN. In aim 1, we will determine the role of CD148 in DN by manipulating CD148 expression in diabetic mice using conditional knockout and transgenic mice. In aim2, we will determine the effects of CD148 activation in DN by treating diabetic mice with the CD148 agonists, a specific TSP1 fragment and an agonistic antibody. Aim 3 will determine the endothelial signaling and function which is regulated by CD148 in diabetic glomerular endothelial cells, by knocking-down or activating CD148 in high-glucose glomerular endothelial culture and in diabetic glomeruli in vivo (in mice). Thus, the proposed studies will define the role of CD148 anti- angiogenic pathway in DN and explore a new strategy for the treatment of this disease.