Juvenile Diabetes Research Foundation Danielle Alberti Memorial Centre for Diabetes Complications, Diabetes Division, Baker IDI Heart and Diabetes Institute, Victoria, Australia.
Diabetes. 2010 Jul;59(7):1794-802. doi: 10.2337/db09-1736. Epub 2010 Apr 14.
Increased deposition of extracellular matrix (ECM) within the kidney is driven by profibrotic mediators including transforming growth factor-beta (TGF-beta) and connective tissue growth factor (CTGF). We investigated whether some of their effects may be mediated through changes in expression of certain microRNAs (miRNAs).
Proximal tubular cells, primary rat mesangial cells, and human podocytes were analyzed for changes in the expression of key genes, ECM proteins, and miRNA after exposure to TGF-beta (1-10 ng/microl). Tubular cells were also infected with CTGF-adenovirus. Kidneys from diabetic apoE mice were also analyzed for changes in gene expression and miRNA levels.
TGF-beta treatment was associated with morphologic and phenotypic changes typical of epithelial-mesenchymal transition (EMT) including increased fibrogenesis in all renal cell types and decreased E-cadherin expression in tubular cells. TGF-beta treatment also modulated the expression of certain miRNAs, including decreased expression of miR-192/215 in tubular cells, mesangial cells, which are also decreased in diabetic kidney. Ectopic expression of miR-192/215 increased E-cadherin levels via repressed translation of ZEB2 mRNA, in the presence and absence of TGF-beta, as demonstrated by a ZEB2 3'-untranslated region luciferase reporter assay. However, ectopic expression of miR-192/215 did not affect the expression of matrix proteins or their induction by TGF-beta. In contrast, CTGF increased miR-192/215 levels, causing a decrease in ZEB2, and consequently increased E-cadherin mRNA.
These data demonstrate the linking role of miRNA-192/215 and ZEB2 in TGF-beta/CTGF-mediated changes in E-cadherin expression. These changes appear to occur independently of augmentation of matrix protein synthesis, suggesting that a multistep EMT program is not necessary for fibrogenesis to occur.
细胞外基质（ECM）在肾脏中的沉积增加是由成纤维细胞生长因子-β（TGF-β）和结缔组织生长因子（CTGF）等促纤维化介质驱动的。我们研究了它们的一些作用是否可能通过某些 microRNAs（miRNAs）表达的变化来介导。
分析了近端肾小管细胞、原代大鼠系膜细胞和人足细胞在暴露于 TGF-β（1-10ng/ml）后关键基因、ECM 蛋白和 miRNA 的表达变化。肾小管细胞也被 CTGF-腺病毒感染。还分析了糖尿病 apoE 小鼠肾脏的基因表达和 miRNA 水平变化。
TGF-β 处理与上皮-间充质转化（EMT）的形态和表型变化有关，包括所有肾细胞类型的纤维化增加和肾小管细胞中 E-钙粘蛋白表达减少。TGF-β 处理还调节了某些 miRNA 的表达，包括肾小管细胞和系膜细胞中 miR-192/215 的表达减少，而糖尿病肾脏中也减少了。miR-192/215 的异位表达通过抑制 ZEB2 mRNA 的翻译增加了 E-钙粘蛋白的水平，这在 TGF-β存在和不存在的情况下都得到了证实，通过 ZEB2 3'-非翻译区荧光素酶报告基因测定。然而，miR-192/215 的异位表达并不影响基质蛋白的表达或它们被 TGF-β诱导。相反，CTGF 增加了 miR-192/215 的水平，导致 ZEB2 减少，从而增加了 E-钙粘蛋白 mRNA。
这些数据表明，miR-192/215 和 ZEB2 在 TGF-β/CTGF 介导的 E-钙粘蛋白表达变化中起着联系作用。这些变化似乎独立于基质蛋白合成的增加，这表明纤维化发生不一定需要多步骤 EMT 程序。
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