Role of HIPK2 in Kidney Tubulointerstitial Injury

描述(由申请人提供)：HIV相关肾病(HIVAN)是非裔美国人终末期肾病的主要原因。尽管对疾病机制的了解越来越多，但治疗选择一直有限。虽然基因表达微阵列已广泛应用于肾脏疾病的研究，但数据分析工具相当有限。在这里，我们提出了一种新的方法，利用计算/系统生物学方法将微阵列数据与上游信号激酶激活联系起来。为了做到这一点，我们开发了几个计算程序，包括Gene2 Network，一个利用蛋白质-蛋白质相互作用和细胞信号网络来根据基因种子列表构建子网络的系统，以及一种将蛋白质列表与最有可能调节其活性的激酶联系起来的工具--激酶浓缩分析(KEA)。用这种方法研究HIV-1转基因小鼠模型(TG26小鼠)的肾脏疾病，我们发现同源结构域相互作用蛋白激酶2(HIPK2)是一种新的上游激酶，调节TG26小鼠肾脏中激活的转录因子和基因。已知HIPK2参与P53、转化生长因子-2、WNT/2-连环蛋白和Notch通路的调节，这些通路在包括HIVAN在内的肾脏疾病中介导细胞凋亡和纤维化。我们的初步数据表明，HIPK2蛋白在TG26小鼠和HIVAN患者的肾小管间质中的表达显著增加。此外，HIPK2还介导了HIV诱导的肾小管上皮细胞的凋亡和上皮-间充质转化(EMT)，促进了肾脏纤维化。基于这些初步数据，我们假设HIPK2是一种上游蛋白激酶，在HIVAN和其他肾脏疾病中介导肾小管间质损伤。为了验证我们的假设，我们提出了以下特定目标：特定目标1：通过确认HIPK2在HIV感染细胞的凋亡和EMT中的作用，以及通过确定HIV激活HIPK2上下游的信号通路来研究HIPK2在体外的作用。具体目的2：通过研究HIPK2基因敲除小鼠在单侧输尿管梗阻模型中是否对肾小管间质损伤有保护作用，以及评估HIPK2基因敲除对TG26肾小管间质损伤发生的影响，证实HIPK2在体内的作用。 公共卫生相关性：HIPK2可能是一种新的上游激酶，激活多条下游通路，导致肾小管间质损伤，这是慢性肾脏疾病进展过程中的最终共同途径。HIPK2可能成为治疗HIV相关性肾病和其他肾脏疾病的潜在新靶点。我们的研究还将提供一种新的方法，将上游信号通路与基因表达微阵列的数据联系起来，这可能有助于我们识别导致HIVAN以及其他疾病肾脏损伤的关键上游激酶。

DESCRIPTION (provided by applicant): HIV-associated nephropathy (HIVAN) is a leading cause of end stage kidney disease among African-Americans. Despite growing knowledge of the disease mechanism, therapeutic options have been limited. While gene expression microarray has been widely applied for the study of kidney diseases, data analytical tools are quite limited. Here we propose a novel approach to link the microarray data to the upstream signaling kinase activation using computation/systems biology approach. To accomplish this, we have developed several computational programs including Gene2 Network, a system that uses protein-protein interactions and cell signaling networks to build subnetworks based on seed lists of genes, and kinase enrichment analysis (KEA), a tool that links lists of proteins to the kinases most likely regulating their activity. Using this approach to study the kidney disease in a HIV-1 transgenic mouse model (Tg26 mice), which is a well-characterized animal model for human HIVAN, we identified that homeodomain interacting protein kinase 2 (HIPK2) is a novel upstream kinase regulating the transcription factors and genes activated in kidneys of Tg26 mice. HIPK2 is known to be involved in the regulation of p53, TGF-2, Wnt/2-catenin, and Notch pathways, which are known to mediate apoptosis and fibrosis in kidney disease including HIVAN. Our preliminary data suggest that HIPK2 protein expression is increased markedly in the renal tubulo-interstitial compartment of Tg26 mice and human with HIVAN. In addition, HIPK2 mediates HIV-induced apoptosis and epithelial-mesenchymal transition (EMT) of renal tubular epithelia cells, contributing to kidney fibrosis. Based on these preliminary data we hypothesize that HIPK2 is an upstream protein kinase that mediates tubulointersitial injury in HIVAN and in other kidney diseases. To test our hypotheses, we propose the following specific aims: Specific aim 1: Examine the role of HIPK2 in vitro by confirming the role of HIPK2 in apoptosis and EMT of HIV-infected cells and by determining signaling pathways up- and down-stream of HIPK2 that are activated by HIV. Specific aim 2: Confirm the role of HIPK2 in vivo by investigating whether HIPK2 knockout mice are protected from the development of tubulointerstitial injury in the unilateral ureteral obstruction model and by assessing the effect of HIPK2 knockout on the development of tubulointerstitial injury in Tg26. PUBLIC HEALTH RELEVANCE: HIPK2 could be a novel upstream kinase activating multiple downstream pathways leading to tubulo-interstitial injury, which is a final common pathway in the progression of chronic kidney disease. HIPK2 could be a potential new therapeutic target for the treatment of HIV-associated nephropathy as well as other kidney diseases. Our studies will also provide a novel approach to link upstream signaling pathways to data from gene expression microarray, which could help us to identify key upstream kinases responsible for kidney injury in HIVAN, as well as in other diseases.