Role of HIPK2 in Kidney Tubulointerstitial Injury

描述（由申请人提供）：HIV 相关肾病 (HIVAN) 是非洲裔美国人终末期肾病的主要原因。尽管对该疾病机制的了解不断增加，但治疗选择仍然有限。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，我们提出了一种使用计算/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的新方法。为了实现这一目标，我们开发了多个计算程序，包括 Gene2 Network（一种使用蛋白质-蛋白质相互作用和细胞信号网络来构建基于基因种子列表的子网络的系统）和激酶富集分析 (KEA)（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）。使用这种方法研究 HIV-1 转基因小鼠模型（Tg26 小鼠）中的肾脏疾病，该模型是人类 HIVAN 的良好表征动物模型，我们发现同源域相互作用蛋白激酶 2 (HIPK2) 是一种新型上游激酶，调节 Tg26 小鼠肾脏中激活的转录因子和基因。已知 HIPK2 参与 p53、TGF-2、Wnt/2-catenin 和 Notch 通路的调节，这些通路可介导包括 HIVAN 在内的肾脏疾病的细胞凋亡和纤维化。我们的初步数据表明，在携带 HIVAN 的 Tg26 小鼠和人类的肾小管间质室中，HIPK2 蛋白表达显着增加。此外，HIPK2介导HIV诱导的肾小管上皮细胞凋亡和上皮间质转化（EMT），导致肾纤维化。基于这些初步数据，我们假设 HIPK2 是一种上游蛋白激酶，介导 HIVAN 和其他肾脏疾病中的肾小管间质损伤。为了检验我们的假设，我们提出以下具体目标： 具体目标 1：通过确认 HIPK2 在 HIV 感染细胞凋亡和 EMT 中的作用，并确定 HIV 激活的 HIPK2 上下游信号通路，在体外检查 HIPK2 的作用。具体目标2：通过研究HIPK2敲除小鼠在单侧输尿管梗阻模型中是否能免受肾小管间质损伤的发生以及评估HIPK2敲除对Tg26中肾小管间质损伤发生的影响，证实HIPK2在体内的作用。 公共健康相关性：HIPK2 可能是一种新型上游激酶，可激活多种下游途径，导致肾小管间质损伤，这是慢性肾脏疾病进展的最终共同途径。 HIPK2 可能成为治疗 HIV 相关肾病以及其他肾脏疾病的潜在新治疗靶点。我们的研究还将提供一种将上游信号通路与基因表达微阵列数据联系起来的新方法，这可以帮助我们识别导致 HIVAN 以及其他疾病肾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.