FIG. 2.

TGF-β1-induced ECM gene and TGF-β2 expression changes in proximal tubular epithelial cells. A: NRK52E cells (Dulbecco's modified Eagle medium, 25 mmol/l glucose, 2% serum) were treated with TGF-β1 (10 ng/ml, 3 days), and the expression of several genes was assessed by real-time QPCR. Significant changes are indicated (*P < 0.05 compared with control). B: The change in expression of TGF-β1 and TGF-β2 genes was assessed by real-time QPCR, and significant changes are indicated (*P < 0.0005 compared with control). C: TGF-β2 proteins levels were measured by ELISA and expressed as pg/mg (*P < 0.0005 compared with control). D: NRK52E cells were incubated with either control IgG (1 μg/ml) or TGF-β2-specific neutralizing antibody (1 μg/ml) for 1 h, and then TGF-β1 was added (10 ng/ml). Cells were harvested 3 days later and subjected to real-time QPCR analysis. The TGF-β2 antibody prevented the increased expression of αSMA, Collagen I, and fibronectin that is induced by TGF-β1, compared with the IgG control antibody (*P < 0.05 compared with control). E: Cells were then treated with TGF-β1 (10 ng/ml, 3 days) in the presence or absence of SB432542, the TGF-β2 receptor inhibitor. Real-time QPCR analysis confirmed that the gene expression changes induced by TGF-β1 are attenuated by SB432542 (*P < 0.05 and #P < 0.001 compared with control).