Aims To investigate the effect and underlying mechanism of melittin and tripartite motif (TRIM) family in human embryonic lung fibroblast (HELF). Materials and methods Lentiviral RNA interference vector and lentiviral overexpression vector were constructed and packaged by transfecting 293T cells; the proliferation of HELF was examined using Cell Counting Kit 8; Western blot and qRT-PCR were performed to examine protein and mRNA expression; the interaction with protein phosphatase magnesium-dependent 1A (PPM1A) was examined by Co-immunoprecipitation. Key findings Compared with the control group, the mRNA expression of the TRIM6, TRIM8 and TRIM47 in the IPF group significantly increased. Melittin inhibited the mRNA expression and protein expression levels of TRIM47, the HELF proliferation, the hydroxyproline levels, and the phosphorylation of Smad2/3; the interference of TRIM47 inhibited the protein expression of Vimentin, α-SMA, CTGF, the phosphorylation of Smad2/3 and the synthesis of hydroxyproline; TRIM47 overexpression elevated the phosphorylation of Smad2/3, induced ubiquitination of PPM1A and decreased the expression level of PPM1A, while TRIM47 RNA interference reversed this result. Significance Melittin has anti-fibrotic effect in HELF by directly reducing the phosphorylation of Smad2/3 or indirectly reducing the phosphorylation of Smad2/3 by decreasing the expression levels of TRIM47 whose overexpression induces ubiquitination of PPM1A.
Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease characterized by lung inflammation and excessive deposition of extracellular matrix components. Transforming growth factor-β1 (TGF-β1) induced epithelial–mesenchymal transformation of type 2 lung epithelial cells leads to excessive extracellular matrix deposition, which plays an important role in fibrosis. Our objective was to evaluate the effects of 3-cyclopropylmethoxy-4-(difluoromethoxy) benzoic acid (DGM) on pulmonary fibrosis and aimed to determine whether EMT plays a key role in the pathogenesis of pulmonary fibrosis and whether EMT can be used as a therapeutic target for DGM therapy to reduce IPF. Firstly, stimulation of in vitro cultured A549 cells to construct EMTs with TGF-β1. DGM treatment inhibited the expression of proteins such as α-SMA, vimentin, and collagen Ⅰ and increased the expression of E-cadherin. Accordingly, Smad2/3 phosphorylation levels were significantly reduced by DGM treatment. Secondly, models of tracheal instillation of bleomycin and DGM were used to treat rats to demonstrate their therapeutic effects, such as improving lung function, reducing lung inflammation and fibrosis, reducing collagen deposition, and reducing the expression of E-cadherin. In conclusion, DGM attenuates TGF-β1-induced EMT in A549 cells and bleomycin-induced pulmonary fibrosis in rats.Keywords:IPF;A549;EMT;TGF-β1/Smad;ECM
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