Pathobiology of Renal Matrix Metabolism

间质纤维化和肾小管萎缩是所有进行性肾纤维化的标志。在过去的十年里，该实验室一直专注于研究特异性基质金属蛋白酶（MMP-2和MT1-MMP）在这一过程中的作用。MMP-2与MT1-MMP结合，足以诱导极化上皮细胞向成纤维细胞表型转化，这一过程称为上皮间充质转化（EMT）。定量地说，EMT与间质成纤维细胞群的激活和扩张相结合，是肾小管萎缩和进行性肾纤维化的主要因素。在体外，EMT由多种细胞因子和环境因素驱动；然而，我们假设肾脏EMT是由三种主要转录网络驱动的亚稳态：tgf - β /Smad；

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.