Collagen 3

Briefly, paraffin sections (thickness, 5 μm) were deparaffinized, rehydrated, immersed in 3% hydrogen peroxide for 10 min, and then incubated for 30 min in blocking buffer (5% bovine serum albumin). The sections were incubated overnight at 4 °C with antibodies against ɑ-SMA (1:100; Servicebio, China) or Collagen III (1:100; Servicebio, China), followed by incubation at room temperature with a horseradish-peroxidase (HRP)-conjugated secondary antibody (1:100; Sigma-Aldrich, USA). Images were acquired by a microscope (Nikon, Japan).

Mice lung tissue was fixed, embedded in paraffin, sectioned to 5-μm-thick slices, deparaffinized, and dehydrated. Endogenous peroxidase activity was quenched in 0.3% H₂O₂ for 10 min, and the slides were blocked with 5% bovine serum albumin (BSA) for 30 min. The sections were stained with primary antibodies against α-SMA (1:100; Servicebio, Wuhan, China), collagen I (1:100; Servicebio, Wuhan, China) or collagen III (1:100; Servicebio, Wuhan, China) overnight at 4 °C, followed by incubation with an HRP-conjugated secondary antibody (1:100; Sigma-Aldrich, MI, USA) at room temperature (20–25 °C) for 30 min. Images were acquired by a microscope (Nikon, Tokyo, Japan).

Reagent sources are as follows: Bleomycin and DOT1L inhibitor EPZ5676 were purchased from Meilunbio (Meilun Biotechnology, Dalian, China); recombinant human and mouse TGF-β1 proteins were purchased from R&D (R&D Systems, Inc. USA); the Notch signaling inhibitor LY-411575 was purchased from MedChemExpress (HY-50752); the Smad3-specific inhibitor SIS3 was purchased from Sigma (S0447). Antibodies were obtained from the following commercial sources: DOT1L, Collagen I, FN, and MMP9 were purchased from ABclonal (Wuhan, China); MMP2 and Collagen III were purchased from Servicebio (Wuhan, China); α-SMA and Jagged1 was purchased from Cell Signaling Technology (Danvers, MA, USA); NICD and CTGF for western blot was purchased from Abcam (Cambridge, MA, USA); β-Tubulin and GAPDH were purchased from Proteintech (Rosemont, IL, USA); CTGF for immunofluorescence staining was purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA).