Fig. 1.

Aged miR-34a−/− mice are protected from experimental lung fibrosis. Aged wild-type (WT) or miR-34a−/− mice (20 mo old) were intratracheally instilled with saline or bleomycin (BLM; 1.5 U/kg body wt in 50 μl saline). Three weeks after BLM instillation, mice were killed and lungs collected. A: hydroxyproline levels in right lungs were determined. Values are means ± SE; n = 3, 10, 3, and 7 WT mice without and with BLM, and miR-34a−/− mice without and with BLM, respectively. *P < 0.05. **P < 0.01. B: mRNA levels of Col1A1 and fibronectin (Fn) in BLM-treated lungs were determined by real-time PCR. C: protein levels of Fn in the lungs were determined by Western blotting. D: acid- and pepsin-soluble collagens in BLM-treated lungs were determined by Sircol collagen assays. B–D: values are means ± SE; n = 5 and 7 WT and miR-34a−/− BLM-treated mice, respectively. *P < 0.05 and **P < 0.01 compared with BLM WT group. E: lung sections were prepared from the above experiments. Hematoxylin and eosin (H&E) staining (original magnification, × 5), Masson's trichrome staining, and immunohistochemistry assay for α-SMA were performed (original magnification, × 10).