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

描述(由申请人提供)：肾小管间质疾病是HIV相关肾病(HIVAN)病理生物学的重要组成部分，HIVAN是HIV感染者慢性肾功能衰竭的最常见原因。在HIVAN中，HIV感染肾小管上皮细胞(RTECs)导致细胞凋亡和促炎分子的产生失调，这两者都在进行性肾功能衰竭中起重要作用。HIVAN几乎只发生在非洲血统的人中，个人的遗传背景是艾滋病毒感染肾上皮细胞是否会导致进行性肾脏疾病的关键决定因素。我们最近已经证明，在体外和HIVAN活检标本中，泛素样蛋白FAT10在HIV感染的人RTEC中高度上调，FAT10的表达诱导RTEC凋亡，并且通过shRNA构建的抑制FAT10表达的方法改善了HIV诱导的RTEC的凋亡。我们实验室的初步研究也表明，FAT10的表达上调了人RTEC中的NF-KB信号，从而可能诱导这些细胞产生促炎介质。我们已经确定了FAT10基因的四个等位基因，其中一个在HIVAN患者中明显更常见。由于RTEC的凋亡和RTECs产生的促炎介质是HIVAN发病机制中的重要因素，我们推测FAT10基因的多态性改变了其诱导RTEC凋亡和激活核因子-kB的能力。我们将在以下三个具体目标中验证这些假说：1：确定FAT10中非同义的FAT10 SNPs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FAT10蛋白的四个变体在它们的亚细胞定位和诱导细胞凋亡的能力方面有何不同。2：明确FAT10在人肾小管上皮细胞核因子-KB信号转导中的作用，并确定FAT10等位基因在刺激核因子-KB信号转导的能力上是否存在差异。在目标2中，我们将研究FAT10激活核因子-KB信号的机制。3：确定在HIV-1转基因HIVAN模型中，FAT10的表达是否对HIVAN表型的形成是必需的。在目的3中，我们将用HIV-1转基因小鼠培育FAT10基因敲除小鼠，并研究脂肪基因缺失对HIVAN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.