BMP-7 counteracts TGF-β1-induced epithelial-to-mesenchymal transition in human renal proximal tubular epithelial cells
- Xu, Yanfang
- Wan, Jianxin
- Jiang, Dewen
- Wu, Xiaonan
Abstract
Background:
A large proportion of interstitial fibroblasts actually originate from tubular epithelial cells via the epithelial-to-mesenchymal transition (EMT) in renal fibrogenesis. Transforming growth factor-β1 (TGF-β1) is capable of initiating and completing the entire EMT course. Bone morphogenetic protein-7 (BMP-7) is a member of the TGF-β superfamily. Recent studies indicate that BMP-7 could reverse established renal fibrosis in mice, primarily through counteracting TGF-β1-mediated EMT. Therefore, we tested the hypothesis that BMP-7 functions by antagonizing profibrogenic events that are induced by TGF-β1 in cultured human renal proximal tubular epithelial (HK-2) cells.
Methods:
Cultured HK-2 cells were treated with TGF-β1 (3 ng/mL) or a combination of TGF-β1 and BMP-7 (100–400 ng/mL) for 48 hours. Morphological changes were assessed by phase contrast microscopy. The expression of α-smooth muscle actin (α-SMA), E-cadherin, fibronectin, collagen I and connective tissue growth factor (CTGF) was analyzed by immunofluorescence, reverse transcriptase polymerase chain reaction and Western blotting.
Results:
Incubation of HK-2 cells with 3 ng/mL TGF-β1 for 48 hours induced EMT, in association with decreased E-cadherin expression, increased α-SMA, fibronectin, collagen I and CTGF expression, and loss of epithelial morphology. BMP-7 inhibited all these effects in a dose-dependent manner. In addition, 200 ng/mL BMP-7 reversed TGF-β1-induced EMT, in association with reexpression of endogenous E-cadherin.
Conclusions:
These data suggest that BMP-7 attenuates progressive loss of kidney function and renal fibrosis through counteracting TGF-β1-mediated EMT.