Role of CD148 Tyrosine Phosphatase in Diabetic Nephropathy

描述（申请人提供）：糖尿病肾病（DN）是终末期肾脏疾病的主要病程。虽然涉及多种细胞类型，但DN本质上是一种微血管疾病，是血液动力学和代谢紊乱共同作用的结果。内皮细胞及其紊乱在本病中起主要作用。近十年来，大量研究表明，血管生成信号过多和肾小球内皮生长不调节是DN的关键致病机制。VEGF/VEGFR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在很大程度上是未知的，然而血管生成信号的大小和频谱是由血管生成和抗血管生成信号之间的平衡决定的。鉴于内皮受体蛋白酪氨酸激酶（endothelial receptor protein tyrosine kinase, RPTKs）在血管生成信号的转导中起着重要作用，我们提出了内皮受体蛋白酪氨酸磷酸酶（endothelial receptor protein tyrosine phosphatases, RPTKs）可能诱导抗血管生成信号的假设。我们已经从肾小球内皮细胞中分离出受体型PTP CD148，并表明CD148在抑制内皮生长因子信号（包括VEGFR）和抑制内皮细胞生长和血管生成方面具有强大的活性。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是肾小球血管生成反应的关键调节因子。因此，在这个应用中，我们定义了CD148在DN中的作用。根据我们的初步数据和CD148的抗血管生成活性，我们提出了以下假设：1) CD148在糖尿病肾小球内皮中的表达/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DN的发生和进展。2)激活CD148抑制糖尿病肾小球内皮血管生成生长因子信号，恢复DN的功能和结构变化。在目的1中，我们将通过条件敲除和转基因小鼠操纵糖尿病小鼠的CD148表达来确定CD148在DN中的作用。在目的2中，我们将通过使用CD148激动剂、特定的TSP1片段和激动抗体治疗糖尿病小鼠来确定CD148在DN中的激活作用。目的3将通过敲低或激活高糖肾小球内皮细胞和体内（小鼠）糖尿病肾小球中的CD148，确定CD148在糖尿病肾小球内皮细胞中调控的内皮信号和功能。因此，本研究将明确CD148抗血管生成通路在DN中的作用，并探索治疗该病的新策略。

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.