Fig. 1

Mitochondrial folate pathway is involved in myofibroblast differentiation and silica-induced pulmonary fibrosis. A Schematic diagram of folate metabolism. Proteins with blue frame were detected by mass spectrometry. Proteins highlighted in red were upregulated. B Lysates from MRC-5 cells treated with or without TGF-β1 for different time were analyzed by western blotting with indicated antibodies. C Volcano plot of proteins quantified by mass spectrometry following TGF-β1 treatment for 48 h. Mitochondrial proteins were highlighted with indicated color. D Heatmap of differentially expressed mitochondrial proteins detected by mass spectrometry. E Relative abundance of proteins involved in cytosolic and mitochondrial folate pathway detected by mass spectrometry. Proteins highlighted in red were above the upregulation threshold dash line. F SLC25A32 and MTHFD2 expression levels in MRC-5 with or without TGF-β1 treatment for 48 h were determined by RT-qPCR. Results are expressed as mean ± SD, n = 3, * represents P < 0.05. G, H Immunofluorescence of MRC-5 cells with indicated antibodies following TGF-β treatment for 48 h. Scale bar = 20 μm. I Western blotting of MRC-5 cells with indicated antibodies following TGF-β treatment for 48 h. J Slc25a32 and Mthfd2 expression levels in normal and fibrotic lung tissue of mice were determined by RT-qPCR. Results are expressed as mean ± SD, n = 4, * represents P < 0.05. K Immunohistochemical staining of MTHFD2 in normal and silica induced fibrotic lung tissue of mice. Scale bar = 50 μm