Epithelial Beta-catenin Signaling Improves Chronic Renal Injury

慢性肾脏疾病(CKD)是一个日益严重的公共卫生问题，影响着超过10%的退伍军人， 增加发病率和死亡率，并造成巨大的经济负担。持续性肾小管损伤是一种 肾小管间质纤维化(TIF)的重要组成部分，是任何病因的进展性CKD的共同特征。 生长因子，如转化生长因子-(转化生长因子-)和WNT/-连环蛋白是重要的决定因素 肾小管上皮细胞对损伤的反应。Wnt/-Catenin途径的各种抑制剂具有混合作用 关于慢性肾损伤。我们使用一种遗传方法来增强近端小管中的-连环蛋白信号，并且 这导致了肾损伤后慢性肾脏病进展的显著改善。Wnt/-连环蛋白信号转导途径 在伤害和动态平衡方面有着截然不同的行为。我们的初步数据表明，-连环蛋白与 转录因子foxO可能是损伤时-连环蛋白依赖反应改变的重要介导物。 这项建议测试了上皮性-连环蛋白信号通过以下途径预防慢性肾脏病进展的假设 对炎症、氧化应激和细胞周期进程的保护作用部分依赖于 福克斯。 第一个目的是研究上皮性-连环蛋白信号如何通过影响 用小鼠损伤模型研究炎症、细胞周期和抗氧化剂的产生。我们将在基因上使用 具有-连环蛋白突变以防止其降解的改良小鼠，而这种突变的-连环蛋白 在近端小管中特异表达，或以多西环素可诱导的形式存在于整个小管中 举止。我们将通过血管紧张素/单肾切除或马兜铃酸诱导慢性肾损伤。我们 预计上皮-连环蛋白活性增加的小鼠可以减轻炎症，改变细胞周期 进展，减少氧化应激，增加损伤后的上皮存活率。我们已经确定了一个 根据我们的初步数据，可能介导这些影响的潜在-连环蛋白靶标的数量。我们会 测量这些靶点在损伤动物模型中的表达，并利用细胞测试它们如何影响细胞死亡 培养技术。 第二个目的是探讨fox在介导-连环蛋白对慢性肾损伤保护作用中的作用。 受伤。我们将确定损伤(即氧化应激)如何改变-连环蛋白信号以促进FOXO- 使用一种特殊的报告老鼠进行中介反应。我们还将在包含活动的鼠标上划线- 与我们的小鼠在同一上皮段缺少FoxO的情况下，近端小管中的连接素。如果的好处- 连环蛋白活性是通过FoxO介导的，那么这个双条件基因敲除小鼠应该会失去 -连环蛋白活性增强所产生的保护作用(即更多的上皮细胞死亡)。此外，我们还将 确定FoxO靶标如何使用细胞培养技术改变上皮细胞对压力的反应。 这项建议使用创新的遗传方法来确定-连环蛋白和FOXO的作用 上皮损伤中的相互作用。我们将研究这些蛋白质相互作用的几个新靶点 通过对转录组进行测序(初步数据)。这些研究将为以下项目提供宝贵的临床前数据 这些靶点可能会导致CKD的未来治疗。此外，这些研究将进一步加深我们的知识 Wnt/-catenin信号转导通路及FoxO在慢性肾脏病中的作用。

Chronic kidney disease (CKD) is a growing public health problem that affects more than 10% of Veterans, increases morbidity and mortality, and imposes a huge economic burden. Persistent renal tubular injury is an important component of tubulointerstitial fibrosis (TIF), the common feature of progressive CKD of any etiology. Growth factors such as transforming growth factor- (TGF-) and Wnt/-catenin are important determinants of how tubular epithelia respond to injury. Various inhibitors of the Wnt/-catenin pathway have had mixed effects on chronic renal injury. We used a genetic approach to augment -catenin signaling in the proximal tubule, and this resulted in marked improvement in CKD progression after renal injury. Wnt/-catenin signaling mediates very different actions in injury versus homeostasis. Our preliminary data suggest that -catenin binding to the transcription factor FoxO may be an important mediator of the altered -catenin-dependent responses in injury. This proposal tests the hypothesis that epithelial -catenin signaling protects against CKD progression by protective effects on inflammation, oxidative stress, and cell cycle progression in a manner partly dependent on FoxO. The first aim investigates how epithelial -catenin signaling alters epithelial survival through effects on inflammation, cell cycle, and antioxidant production using murine models of injury. We will use genetically modified mice that have a mutation in -catenin that prevents its degradation, and this mutant -catenin is either specifically expressed in the proximal tubule or present throughout the tubule in a doxycycline-inducible manner. We will induce chronic kidney injury by either angiotensin/uninephrectomy or aristolochic acid. We anticipate that mice with increased epithelial -catenin activity have reduced inflammation, altered cell cycle progression, reduced oxidative stress, and increased epithelial survival after injury. We have identified a number of potential -catenin targets that may mediate these effects based on our preliminary data. We will measure expression of these targets in the injured animal models and test how they affect cell death using cell culture techniques. The second aim explores the role of FoxO in mediating -catenin's protective effect after chronic kidney injury. We will determine how injury (i.e. oxidative stress) alters the way -catenin signals to promote FoxO- mediated responses using a special reporter mouse. We will also cross our mouse containing the active - catenin in the proximal tubule with our mouse lacking FoxO in the same epithelial segment. If the benefit of - catenin activity is mediated through FoxO, then this double conditional knockout mouse should lose the protective effect (i.e. more epithelial cell death) conferred by augmented -catenin activity. Furthermore, we will define how FoxO targets change epithelial responses to stress using cell culture techniques. This proposal uses innovative genetic approaches to determine the role of -catenin and FoxO interactions in epithelial injury. We will investigate several novel targets of these protein interactions identified by sequencing the transcriptome (preliminary data). These studies will provide valuable pre-clinical data for these targets which may lead to future therapies for CKD. In addition, these studies will further our knowledge of Wnt/-catenin signaling and the role of FoxO in CKD.