Fig. 2.

miR-34a is upregulated in AECs, but not in lung fibroblasts, of aged mice, and AEC miR-34a is further increased in aged fibrotic lungs. A and B: aged mice (20 mo old) were intratracheally instilled with bleomycin (BLM) (1.5 U/kg body wt in 50 μl saline). Three weeks after BLM instillation, lungs were collected, and levels of mature miR-34a (A) and primary miR-34a (B) in the lungs were determined by real-time PCR. Values are means ± SE; n = 3 and 6 saline and BLM mice, respectively. *P < 0.05 compared with saline group. C–F: young (10 wk old) and aged mice (20 mo old) were intratracheally treated with saline or BLM. At day 21 after BLM treatment, mice were killed and lungs collected. Primary lung epithelial cells and lung fibroblasts were isolated as described in materials and methods. Purity of lung epithelial cells and lung fibroblasts was determined by staining of epithelial marker E-cadherin (C) and fibroblast marker α-SMA (D), respectively. Levels of miR-34a in primary lung epithelial cells (E) and lung fibroblasts (F) were determined by real-time PCR. Values are means ± SE; n = 3, 4, 3, and 3 (B), and n = 3, 8, 3, and 4 (C) young mice without and with BLM and aged mice without and with BLM, respectively. *P < 0.05 and **P < 0.01 compared with young saline group. #P < 0.05 compared with young BLM group. Ab, antibody; DAPI, 4,6-diamidino-2-phenylindole.