Pathobiology of Renal Matrix Metabolism

间质纤维化和肾小管萎缩是所有形式的进行性肾纤维化的标志。该实验室在过去十年中一直专注于特定基质金属蛋白酶（MMP-2和MT 1-MMP）在这一过程中的作用。MMP-2与MT 1-MMP结合足以诱导极化上皮细胞转化为成纤维细胞表型，这一过程称为上皮间质转化（EMT）。EMT与间质成纤维细胞群的活化和扩增一起是肾小管萎缩和进行性肾纤维化的主要促成因素。在体外，EMT是由多种细胞因子和环境因素驱动的;然而，我们假设肾脏EMT代表了由三个主要转录网络驱动的亚稳态：TGF-β/Smad; E钙粘蛋白/β-连环蛋白/Wnt/LEF/TCF;和MAPK/ERK信号级联。我们已经确定 MMP-2和MT 1-MMP都是MAPK/ERK信号级联的转录靶点， 确定特定的AP-1复合物组分Fra-2足以驱动 体外EMT。该提议的主要假设是持续的MAPK/ERK信号转导， Fra-2的产生增强，驱动了所需的一组特定基因的转录 肾脏急救解决这个问题的方法包括三个具体目标，提出使用微阵列分析，Fra-2调节基因在一系列上皮细胞克隆群体中显示一系列上皮间充质特征。将使用体外和体内方法验证鉴定的基因的功能意义，包括通过肾近端小管中活性MMP-2的转基因表达产生的肾EMT的独特模型。最后，Fra-2单独在体内诱导EMT的能力将通过该转录因子的转基因近端小管表达来测试。这些研究旨在确定肾脏EMT所需的基因集，从而有望为肾脏疾病的治疗提供新的治疗靶点。

Interstitial fibrosis and tubular atrophy are the hallmarks of all forms of progressive renal fibrosis. This laboratory has focused over the past decade on the role of specific matrix metalloproteinases (MMP-2 and MT1-MMP) in this process. MMP-2, in conjunction with MT1-MMP, is sufficient to induce the conversion of the polarized epithelial cell to a fibroblastic phenotype, a process termed epithelial mesenchymal transition (EMT). Quantitatively, EMT, in conjunction with activation and expansion of the interstitial fibroblast population, is a major contributor to tubular atrophy and progressive renal fibrosis. In vitro, EMT is driven by a diverse number of cytokines and environmental factors; however, we have postulated that renal EMT represents a metastable state driven by three dominant transcriptional networks: TGF-beta/Smad; E cadherin/ beta-catenin/Wnt/LEF/TCF; and MAPK/ERK signaling cascades. We have identified both MMP-2 and MT1-MMP as transcriptional targets of the MAPK/ERK signaling cascades and determined that a specific AP-1 complex component, Fra-2, is sufficient to drive the process of EMT in vitro. The primary hypothesis of this proposal is that sustained MAPK/ERK signaling, with enhanced generation of Fra-2, drives the transcription of a defined cohort of genes required for renal EMT. The approaches to this problem include three Specific Aims proposing to characterize, using microarray analysis, Fra-2-regulated genes in a series of clonal populations of epithelial cells displaying a range of epithelial to mesenchymal features. The functional significance of identified genes will be validated using in vitro and in vivo approaches, including a unique model of renal EMT generated by the transgenic expression of active MMP-2 in the renal proximal tubule. Finally, the ability of Fra-2, alone, to induce EMT in vivo will be tested by the transgenic proximal tubule expression of this transcription factor. These studies are designed to identify those gene sets required for renal EMT and thereby hopefully provide new therapeutic targets for the treatment of renal disease.