Implications of Notch signaling in HIV associated nephropathy

 描述（由申请人提供）：Notch信号传导已显示在与肾小球硬化和足细胞凋亡相关的几种肾脏疾病中起关键作用。然而，其在人类免疫缺陷病毒相关肾病（HIVAN）中的作用尚不清楚，HIVAN表现为肾小球硬化的塌陷变体、局灶节段性肾小球硬化和足细胞/壁细胞增殖。我们使用了HIVAN患者和HIVAN的啮齿动物模型，这些模型表达了9种HIV基因中的7种，并且表现出HIVAN的大多数特征。我们发现，与Notch 1和Notch 2受体激活占主导地位的其他肾小球疾病相比，Notch 4途径似乎在HIVAN中占主导地位。我们发现活化的Notch 4在足细胞、壁上皮细胞和肾小管上皮细胞中表达和升高。体内Notch途径的药理学抑制改善了Tg 26小鼠中的疾病进展。此外，Notch抑制剂可抑制HIV蛋白诱导的足细胞增殖。这些研究表明，异常的Notch信号传导有助于HIVAN的发病机制。在第一个目标中，我们将确定足细胞和壁细胞特异性的Notch信号传导的遗传抑制对Tg 26小鼠疾病严重程度的影响。在第二个目标中，我们将从来自Tg 26小鼠的足细胞进行体外研究，以确定Notch抑制对足细胞增殖、分化和凋亡的影响。我们还将使用壁上皮细胞和足细胞来评估Notch蛋白与HIV-1蛋白相互作用的可能性。最后，在第三个目标中，我们将在Tg 26小鼠中基因敲除Notch 4，并确定疾病预防的可能性。这些研究将提供：1）HIV-1激活Notch的机制和2）在HIVAN患者中测试Notch抑制剂的治疗平台。

 DESCRIPTION (provided by applicant): Notch signaling has shown to play a key role in several kidney diseases, associated with glomerulosclerosis and podocyte apoptosis. However, its role in Human Immunodeficiency Virus Associated Nephropathy (HIVAN) which presents with collapsing variant of glomerulosclerosis, focal segmental glomerulosclerosis, and podocyte/parietal cell proliferation is not known. We used HIVAN patients and rodent models of HIVAN that express seven of the nine HIV genes and phenocopy most characteristics of HIVAN. We show that in contrast to other glomerular diseases, where Notch 1 and Notch2 receptor activation is predominant, Notch 4 pathway appeared to be most predominating in HIVAN. We found activated Notch4 expressed and elevated in podocytes, parietal epithelial cells and tubular epithelium. Pharmacological inhibition of Notch pathway in vivo ameliorated the disease progression in the Tg26 mice. Moreover podocyte proliferation induced by HIV proteins was inhibited by Notch inhibitors. These studies suggest that aberrant Notch signaling, contributes to the pathogenesis of HIVAN. In the first aim, we will determine the effects of podocyte and parietal cell specific genetic inhibition of Notch signaling on disease severity in Tg26 mice. In the second aim, we will perform in vitro studies from podocytes derived from Tg26 mice to determine the effect of Notch inhibition on podocyte proliferation, differentiation and apoptosis. We will also use parietal epithelial cells and podocytes to evaluate the possibility of interaction of Notch proteins with HIV-1 proteins. Finally in the third aim, we will genetically knockdown Notch4 in Tg26 mice and the possibility of disease prevention will be determined. These studies will provide: 1) a mechanism of Notch activation by HIV-1 and 2) a therapeutic platform to test Notch inhibitors in HIVAN patients.