黄芩素下调TGF-β1/Smad3信号改善肺泡上皮细胞衰老的机制研究OA

This study aims to investigate the effect and mechanism of baicalein in improving alveolar epithelial cell senescence.A cellular model of alveolar epithelial cell senescence induced by transforming growth factor-β1(TGF-β1)was established.Cells were randomly divided into control group,model group,baicalein group,small interfering RNA(siRNA)targeting Smad family member 2(Smad2)group,siRNA targeting Smad3 group,and baicalein+Smad3 plasmid group.Western blot was employed to detect the protein expression level of plasminogen activator inhibitor-1(PAI-1),a marker protein of alveolar epithelial cell senescence.Senescence-associated β-galactosidase(SA-β-gal)staining was used to measure the percentage of SA-β-gal-positive cells.The results show that baicalein can significantly inhibit the protein expression of PAI-1 in TGF-β1-induced alveolar epithelial cells and markedly reduce the percentage of SA-β-gal-positive cells in TGF-β1-induced alveolar epithelial cells.Baicalein can also significantly decrease the phosphorylation levels of Smad2 protein and Smad3 protein in TGF-β1-induced alveolar epithelial cells.Knockdown of Smad2 does not affect the protein expression level of PAI-1 in TGF-β1-induced alveolar epithelial cells,nor does it alter the percentage of SA-β-gal-positive cells in TGF-β1-induced alveolar epithelial cells.In contrast,knockdown of Smad3 can significantly downregulate the protein expression level of PAI-1 and reduce the percentage of SA-β-gal-positive cells in TGF-β1-induced alveolar epithelial cells.Overexpression of Smad3 can notably reverse the inhibitory effects of baicalein on PAI-1 protein expression and the percentage of SA-β-gal-positive cells in TGF-β1-induced alveolar epithelial cells.In conclusion,baicalein improves alveolar epithelial cell senescence by downregulating the TGF-β1/Smad3 signaling,but this effect might be independent of Smad2 signaling.