The role of FAT10 in the pathogenesis of HIV-associated nephropathy

描述（由申请方提供）：肾小管间质性肾病是HIV相关肾病（HIVAN）病理学的重要组成部分，是HIV感染个体慢性肾衰竭的最常见原因。在HIVAN中，肾小管上皮细胞（RTECs）的HIV感染导致失调的细胞凋亡和促炎分子的产生，这两者都是进行性肾衰竭的重要原因。HIVAN几乎只发生在非洲血统的人群中，个体的遗传背景是决定肾上皮感染HIV是否会导致进行性肾脏疾病的关键因素。我们最近已经证明，泛素样蛋白FAT 10是高度上调的HIV感染的人RTEC在体外和HIVAN活检标本，FAT 10的表达诱导RTEC的细胞凋亡，并防止FAT 10表达与shRNA结构改善HIV诱导的RTEC细胞凋亡。我们实验室的初步研究还表明，FAT 10表达上调人RTEC中的NF-κ B信号传导，因此可能诱导这些细胞产生促炎介质。我们已经确定了FAT 10基因的四个等位基因，其中一个在HIVAN患者中更常见。由于RTEC细胞凋亡和RTEC产生的促炎介质是HIVAN发病机制中的重要因素，我们假设FAT 10基因的多态性改变了其诱导RTEC细胞凋亡和NF-kB激活的能力。我们将从以下三个方面来验证这些假设：1.确定FAT 10中非同义FAT 10 SNP对其亚细胞定位和促凋亡功能的影响。在这一目标中，我们将确定FAT 10蛋白的四种变体在亚细胞定位和诱导细胞凋亡的能力方面的差异。第二章：明确FAT 10在人肾小管上皮细胞NF-κ B信号传导中的作用，并确定FAT 10等位基因刺激NF-κ B信号传导的能力是否不同。目的二是研究FAT 10激活NF-κ B信号通路的机制。3：确定FAT 10表达是否是HIVAN的HIV-1转基因模型中HIVAN表型发展所必需的。目的三：利用FAT基因敲除小鼠与HIV-1转基因小鼠共育，研究FAT基因缺失对HIV-1表型的影响。这些研究将阐明HIVAN疾病进展的新机制。

DESCRIPTION (provided by applicant): Tubulointerstitial renal disease is an important component of the pathobiology of HIV-associated nephropathy (HIVAN), the most common cause of chronic renal failure in HIV-infected individuals. In HIVAN, HIV infection of renal tubular epithelial cells (RTECs) leads to dysregulated apoptosis and production of proinflammatory molecules, both of which contribute importantly to progressive renal failure. HIVAN occurs almost exclusively in people of African ancestry and the genetic background of the individual is a critical determinant of whether renal epithelial infection by HIV will lead to progressive renal disease. We have recently demonstrated that the ubiquitin-like protein FAT10 is highly upregulated by HIV-infection of human RTECs in vitro and in HIVAN biopsy specimens, that FAT10 expression induces apoptosis in RTECs, and that preventing FAT10 expression with shRNA constructs ameliorates HIV-induced RTEC apoptosis. Preliminary studies in our laboratory have also demonstrated that FAT10 expression upregulates NF-KB signaling in human RTECs and may therefore induce production of proinflammatory mediators by these cells. We have identified four alleles of the FAT10 gene, one of which is significantly more common in patients with HIVAN. Since RTEC apoptosis and production of proinflammatory mediators by RTECs are important factors in HIVAN pathogenesis, we hypothesize that polymorphisms in the FAT10 gene alter its ability to induce RTEC apoptosis and NF-kB activation in RTECs. We will test these hypotheses in the following three Specific Aims: 1: To determine the effects of nonsynonymous FAT10 SNPs in FAT10 upon its subcellular localization and proapoptotic function. In this aim, we will determine how the four variants of the FAT10 protein differ in their subcellular localization and their ability to induce apoptosis. 2: To define the role of FAT10 in NF-KB signaling in human renal tubular epithelial cells and to determine if the FAT10 alleles differ in their ability to stimulate NF-KB signaling. In aim 2, we will study the mechanisms by FAT10 activates NF-KB signaling. 3: To determine whether FAT10 expression is necessary for the development of the HIVAN phenotype in the HIV-1 transgenic model of HIVAN. In aim 3, we will breed FAT10 knockout mice with HIV-1 transgenic mice and study the effect of FAT gene deletion upon the HIVAN phenotype. These studies will elucidate novel mechanisms of disease progression in HIVAN.