Expression of CTGF induced by TGF-β1 in human proximal renal epithelial cells

Objective:To investigate the expression of connective tissue growth factor (CTGF) as well as extra-cellular matrix (ECM), tissue metalloproteinase-1 (TIMP-1), and α-smooth muscle actin (α-SMA) induced by TGF-β1 in cultured human proximal renal epithelial cells (HK-2 cells). Methodology:HK-2 cells were cultured with the concentrations of 0.05, 1, 5 10 and 15ng/ml TGF-β1 for 24 hours or treated with 5ng/ml TGF-β1 for 0, 6, 12, 24, 48, and 72 hours. The expression of CTGF, fibronectin, type Ⅰ collagen, TIMP-1 and α-SMA was measured by reverse transcription-polymerase chain reaction (RT-PCR). Results:The expression of CTGF was detected in the absence of TGF-β1 in HK-2 cells. TGF-β1 induced CTGF expression in a dose and time- dependent manner, which reached its highest level at the dose of 10ng/ml TGF-β1 and 24 hours after stimulation of 5ng/ml TGF-β1. TGF-β1 also induced the accumulation of ECM and expression of α-SMA, while the up-regulation of ECM and α-SMA stimulated by TGF-β1 was later than that of CTGF at the transcription level. Although the expression of TIMP-1 increased with the increasing of TGF-β1, its expression was not significant until TGF-β1 was 15 ng/ml(P0.05). Conclusion:TGF-β1 induced CTGF expression in HK-2 cells in a dose and time- dependent manner, which was early than that of ECM andα-SMA. CTGF may mediate the deposition of ECM and the epithelial-myofibroblast trans-differentiation induced by TGF-β1.