[Changes of fibronectin and type IV collagen expression in cultured rat mesangial cells transfected with Smad 2 vector].

OBJECTIVE: To study the changes of fibronectin (FN) and type IV collagen (ColIV) expression in cultured rat mesangial cells (MsC) transfected with Smad 2 vector and to investigate the molecular mechanism of glomerular extracellular matrix accumulation in glomerulosclerosis via transforming growth factor-beta (TGF-beta)/Smad signal pathway. METHODS: Smad 2 vector was transfected into MsC by calcium phosphate. Western blot analysis was used to detect Smad 2 protein. The expression of FN and ColIV proteins and their mRNAs was determined by Western blot and reverse transcriptase-polymerase chain reaction respectively. RESULTS: Four MsC clones (T-12, T-31, T-35, T-40) with Smad 2 overexpression were established. The expression of FN and ColIV was significantly increased at mRNA and protein levels in two (T-12, T-31). Compared with controls, the expression of FN proteins and mRNAs in these two clones was 2.4 times (P < 0.05) and 2.7 times (P < 0.05) higher respectively. The expression of ColIV proteins and mRNAs was 2.9 times (P < 0.01) and 3.3 times (P < 0.01) higher respectively. CONCLUSIONS: It is postulated that Smad 2 in TGF-beta/Smad signal pathway is important in promoting the accumulation of FN and ColIV in sclerotic glomeruli of diseased kidneys.