Role of CD148 Tyrosine Phosphatase in Diabetic Nephropathy

描述（由申请人提供）：糖尿病肾病（DN）是终末期肾病的主要病程。虽然涉及多种细胞类型，但DN本质上是一种微血管疾病，其发展是血流动力学和代谢紊乱的结果。内皮细胞及其紊乱在这种疾病中起主要作用。 在过去的十年中，大量的研究表明，过度的血管生成信号和肾小球内皮细胞生长失调是DN的一个重要致病机制。VEGF/VEGFR被证明是其驱动力。然而，抗血管生成途径在这种疾病中的作用在很大程度上是未知的，然而血管生成信号的幅度和频谱由血管生成信号和抗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的事实，我们提出了内皮受体蛋白酪氨酸磷酸酶（RPTKs的反酶）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了一种受体型PTP CD 148，并表明CD 148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效活性。此外，我们最近发现，血小板反应蛋白-1（TSP 1），一种抗血管生成蛋白，作为CD 148的配体。这些发现表明，CD 148作为肾小球血管生成反应的关键调节因子发挥作用。因此，在本申请中，我们定义了CD 148在DN中的作用。基于我们的初步数据和CD 148的抗血管生成活性，提出了以下假设：1）糖尿病肾小球内皮中CD 148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），并促进DN的发生和进展。2)CD 148的激活抑制了糖尿病肾小球内皮细胞中血管生成因子的信号，并恢复了DN的功能和结构变化。 在目标1中，我们将通过使用条件性敲除和转基因小鼠操纵糖尿病小鼠中CD 148的表达来确定CD 148在DN中的作用。在aim 2中，我们将通过用CD 148激动剂、特异性TSP 1片段和激动性抗体治疗糖尿病小鼠来确定CD 148活化在DN中的作用。目的3通过在高糖培养的肾小球内皮细胞中敲低或激活CD 148以及在体内（小鼠）的糖尿病肾小球中确定CD 148在糖尿病肾小球内皮细胞中调节的内皮信号传导和功能。因此，本研究将明确CD 148抗血管生成通路在DN中的作用，并为DN的治疗探索新的策略。

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.