Influences On TGF-β₁ Induced Human Lung Fibroblast Proliferation And α-SMA Expression By SRFsiRNA Transfection

Objective:In pulmonary fibrosis,TGF-β₁ stimulates myofibroblast differentiation characterized by expression ofα-smooth muscle actin (α-SMA).In order to examine the role of serum response factor(SRF) in the mechanism of TGF-β₁-induced pulmonary myofibroblast differentiation of human lung fibroblasts(HLF),we use SRF short hairpin RNA to inhibit the expression of SRF and then observe the changes of fibroblast proliferation and expression ofα-SMA.From this,we can get the relationship between SRF andα-SMA expression.That might provide a research evidence for further study of SRF in pulmonary fibrosis.Methods:Three SRF small interference RNA(siRNA) expressing plasmids(SRF-siRNA) were constructed and transfected into human lung fibroblast cell line,MRC-5.According to the expression of SRF mRNA and proteins detected by real-time quantitative PCR and Western blot, chose the siRNA which had the best inhibitory effect.Then transfected the constructed plasmid into MRC-5,determined the expression ofα-SMA by Western blot and cell proliferation investigated by growth curve analysis after TGF-β₁ stimulation.Results:Compared with control cells,cell doubling time of the SRF-siRNA/MRC-5 cells was markedly longer than that of the control cells(P＜0.05).The expression ofα-smooth muscle actin(α-SMA),the marker of myofibroblast differentiation,was decreased in SRF-siRNA /MRC-5 cells.Conclusions:1.The down-regulation of SRF expression could inhibit the prolifetation of MRC-5 after the stimulation of TGF-β₁.2.In the stimulation of TGF-β₁,the decline of SRF transcription could inhibit the expression ofα-SMA in MRC-5.