Effect of PKC signalling pathway and aldose reductase on expression of fibronectin induced by transforming growth factor-β1 in human mesangial cells

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-$l showed increased expression of AR and FN,the normal HMC showed not reduced expression of FN after incubation with single inhibitors of AR. Pre-incubation of cells with inhibitors of AR and PKC, then the different groups of cells were treated with TGF-$l ,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-pl (P <0. 05) , and the induction effect on FN expression was suppressed by G(O)6983 (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.