Fig. 4

Exosomal miR-17-5p directly targets Smad7 in fibroblasts. a Schematic miR-17-5p predicted binding sites in the 3’ UTRs of Smad7 and the sequence of mutant UTRs. b Luciferase reporter assay was performed on HEK293T after co-transfected with the miR-NC or miR-17-5p mimic and the Smad7-wt plasmid or Smad7-mut plasmid. c Luciferase reporter was carried out in HEK293T transfected with Smad7-wt plasmid or Smad7-mut plasmid, then incubated with exosomes (50 μg/mL) derived from PBS-, Arecoline- and Arecoline+GW4869- treated epithelial cells for 48 h. d After transfection miR-17-5p in fibroblast, Immunostaining detection of miR-17-5p (red) and Smad7 (green) expression. Scale bars, 100 μm. e The expression level of Smad7 in normal (n = 12) and OSF (n = 17) tissues detected by qRT-PCR. f The relationship between relative Smad7 expression normalized to GAPDH and miR-17-5p expression normalized to U6. g Immunoblotting of Smad7, fibrotic markers and TGF-β path pathway. Statistics: mean ± SEM, unpaired, two-tailed Student’s t test, *P < 0.05, ***P < 0.001