[The role of transforming growth factor-β1/connective tissue growth factor signaling pathway in paraquat-induced pulmonary fibrosis].
Objective:To investigate the effects of Paraquat on human embryonic lung fibroblasts (MRC5) and explore the role of transforming growth factor-β1/connective tissue growth factor signaling pathway in paraquat-induced pulmonary fibrosis.Methods:MRC5 cells were cultured with different concentration of PQ (0, 12.5, 25, 50, 100, 200, 400 μmol/L) for 24 h. The viability of cells was measured by MTT. The protein level of TGF-β1were analyzed by ELISA after PQ treatment (0, 25, 50, 100 μmol/L) . To examine whether TGF-β1/CTGF signaling pathway was involved in paraquat-induced cytotoxicity, cells was divided into 6 groups: (1) control; (2) 25 μmol/L PQ group; (3) 50 μmol/L PQ group; (4) 100 μmol/L PQ group; (5) TGF-β1positive control group (50 μmol/L rhTGF-β1) ; (6) stimulate group (100 μmol/L PQ+50 μmol/L TGF-β1) . The protein levels of p-Smad2, p-Smad3 and CTGF were assayed by western blot. The mRNA level of CTGF was assayed by real time RT-PCR.Results:MTT showed that cell viability decreased with increasing PQ concentration (P<0.05) . The protein expression of TGF-β1treated with PQ (25, 50, 100 μmol/L) significantly increased compared with control in a dose-independent manner (P<0.05) . Exposure to PQ (25, 50, 100 μmol/L) induced increase of protein levels of p-Smad2 and p-Smad3. Noteworthy, the expression of p-Smad2 and p-Smad3 were dramatically increased following PQ plus TGF-β1stimulation (P<0.05) . Exposure to PQ (50, 100μmol/L) induced increase of CTGF protein expression and similar greatly increase following PQ plus TGF-β1stimulation (P<0.05) . Real time RT-PCR showed CTGF mRNA in all groups also significantly up-regulated compared with control (P<0.05) .Conclusion:TGF-β1regulates the expression of target gene CTGF to exhibit its pro-fibrogenic effects by activating TGF-β1/Smad signaling pathway in PQ-induced pulmonary fibrosis.
School of Public Health, Ningxia Medical University, Yinchuan 750004 China.
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D055513:Connective Tissue Growth Factor / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D008168:Lung; D010269:Paraquat / Q000633:toxicity*; D011658:Pulmonary Fibrosis / Q000139:chemically induced*; D012333:RNA, Messenger; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015291:Transforming Growth Factors
D012333:RNA, Messenger; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D055513:Connective Tissue Growth Factor; D015291:Transforming Growth Factors; D010269:Paraquat