Objective: To investigate if the interaction between TGF-beta1/Smad pathway and ERK pathway in vascular smooth muscle cells exists.
Methods: The rat arota was removed. The primary VSMC were isolated and cultured in vitro, then the VSMC were divided into four groups: (1) control group, (2) (TGF-beta1 group, (3) ERK blocking agent group, (4) TGF-beta1 + ERK blocking agent group. The expression of Smad2/3, ERK1/2 proteins, the content of phosphorylated ERK1/2 and Smad2/3 proteins were detected by Western blot, and the expression of Smad2/3 mRNA was detected by reverse transcription-polymerase chain reaction(RT-PCR) .
Results: (1) In contrast to control group, the content of phosphorylated Smad2/3 and phosphorylated ERK1/2 proteins in TGF-beta1 group was increased (P < 0.05), that in ERK blocking agent group was decreased (P < 0.05). There was no difference between control group and TGF-beta1 + ERK blocking agent group. Compared with TGF-beta1 group, the contents of phosphorylated Smad2/3 and phosphorylated ERK1/2 proteins in TGF-beta1 + ERK blocking agent group was decreased (P < 0.05). There was no difference in the expression of Smad2/3 and ERK1/2 proteins among different groups. (2) There were no differences in expression of Smad2 and Smad3 mRNA among different groups.
Conclusion: (1) TGF-beta1 can induce Smad2/3 proteins to be phosphorylated dependent on the activated ERK pathway. (2) ERK pathway does not effect the expression of Smad2/3 at the level of protein and mRNA.