Figure 3.

DATPs are the principal source of integrin αvβ6, a key activator of TGF-β in lung fibrosis. A: RNA in situ hybridization for Krt7 (teal) and Itgb6 (magenta) as in Fig. 2A. B: distribution of Itgb6^high cells among Krt7⁺ or Krt7⁻ cells. Each dot represents the average of 10 representative 1,240-µm diameter low-power fields from one mouse with means ± SE indicated. C: flow cytometric histogram of integrin αvβ6 expression on the surface of lung epithelial cells at day 12 after bleomycin. Krt19^CreERT2/+ ROSA26^Ai14/+ reporter mice were exposed to bleomycin and Krt19⁺ DATPs labeled by serial tamoxifen administration. Gated CD45⁻ EPCAM⁺ epithelial cells are shown; in bleomycin-exposed mice, epithelial cells were subgated into TdTomato⁺ DATPs or the remaining TdTomato⁻ epithelial cells. Each overlaid curve represents data from a single mouse. D: immunofluorescence staining for Krt8⁺ DATPs and collagen^high fibroblasts (green). Col1a1::GFP reporter mice were exposed to bleomycin and harvested on day 14. DATP, damage-associated transient progenitor; GFP, green fluorescent protein; TGF-β, transforming growth factor β.