Objective: To study the effect of PKC signalling pathway and aldose reductase (AR) on the expression of fibronectin (FN) induced by transforming growth factor-β1 (TGF-β1).
Methods: Human mesangial cells (HMCs) were cultured and transfected with pcDNA3-AR, and subject to AR gene silencing with small interfering RNA (siRNA) and then the cell was treated with recombinant human TGF-β1. The AR mRNA expression in the HMCs was examined using real time RT-PCR and protein expression of AR and FN was detected by Western blotting.
Results: The cultured HMC treated with TGF-β1 showed increased expression of AR and FN, the normal HMC showed not reduced expression of FN after incubation with single inhibitors of AR.Pre-incubation of cells with inhibitors of AR and PKC, then the different groups of cells were treated with TGF-β1, and the induction effect on FN expression was suppressed (34%) in HMC. HMCs transfected with AR showed a strong protein expression of FN, which was increased by 3.6-fold after treatment with TGF-β1 (P < 0.05), and the induction effect on FN expression was suppressed by GÖ6983 (42%) in HMCs (P < 0.05). The HMC with AR gene knock-down by siRNA showed a decreased expression of AR and 90% decrease of FN protein in HMCs (P < 0.01), and TGF-β1-induced up-regulation of FN was significantly suppressed by siRNA (12%) in HMCs (P < 0.01).
Conclusions: AR is capable of regulating FN expression only in the presence of TGF-β1, and this reaction is possibly accomplished through the activation of PKC signalling pathway.