Effects of aldose reductase on the transforming growth factor-beta1-induced expression of fibronectin and collagen IV: experiment with cultured rat mesangial cells

Abstract

To study the effects of aldose reductase (AR) on the transforming growth factor (TGF)-beta1-induced expression of fibronectin (FN) and collagen IV. Restriction endonucleases digestion and ligation were used to reconstruct the eukaryotic expression plasmid pCDNA3-AR. Rat mesangial cells (MsCs) were isolated, cultured, and transfected with pCDNA3-AR, or blank vector. The AR expression in the MsCs was examined by immunofluorescence analysis. RT-PCR was performed to detect the mRNA expression of AR in the MsCs and Western blotting was used to detect the protein expression of AR. AR inhibitors (ARIs), Sorbinil and Zopolrestat were added and co-incubated, then TGF)-beta1 was added and Western blotting was used to analyze the protein expression of FN, collagen IV (Col IV), and mitogen-activated protein kinases (MAPKs) in the MsCs. Immunofluorescence analysis showed stronger expression of AR in the MsCs transfected with AR then in the normal MsCs and the MsCs transfected with blank vector. In comparison with the normal MsCs and those transfected with blank vector, the MsCs transfected with AR showed stronger protein expression of FN and Col IV (all P < 0.05). After incubation of ARIs the protein expression of FN and Col IV decreased by 1.8 and 2.0 times respectively in the MsCs transfected with AR (all P < 0.05). After stimulation of TGF-beta1, the protein expression of FN and Col IV increased in both the normal MsCs and those transfected with AR (P < 0.05 for the latter). After preincubation with ARIs the protein expression of FN and Col IV in the MsCs transfected decreased significantly (both P < 0.05). After stimulation of TGF-beta1, the normal MsCs showed increased expression of phospho-ERK, phospho-JNK, and phospho-p38; the MsCs preincubated with ARIs showed reduced expression of phospho-JNK and phospho-p38; and the MsCs transfected with AR showed increased expression of phosphor-JNK (P < 0.05). AR can regulates the expression of FN and Col IV with the stimulation of TGF-beta1 as AR gene is one of the responsive genes of TGF-beta1, which may have relations with the activation of JNK-MAPK and p38-MAPK signaling pathways induced by TGF-beta1. AR may play a role in the pathogenesis of glomerulosclerosis.