Figure 3. AT2sAxin2 have increased clonal growth potential.
(A and B) Clonal expansion is enhanced in AT2sAxin2 during alveologenesis. Following lineage tracing with the R26RBr2.1 reporter, AT2sAxin2 can expand clonally to a greater extent than the AT2 lineage in general. Arrows indicate single cell clones, dashed lined circles indicate two cell clones, and solid lined circles indicate three cell clones. Note the three cell clone in the AT2Axin2 lineage trace versus the two cell clone in the Sftpc+ lineage trace. (C) Quantitatively, the average AT2Axin2 clone size is larger than AT2s in general. (D) The distribution of clone size exhibits a shift towards more two and three cell clones in AT2sAxin2 compared to the total AT2 population. (E-H) Assessment of proliferation by EdU incorporation at P4 shows that the majority of AT2sAxin2 are actively proliferating compared to a minority of Axin2- AT2s. Arrows represent EdU+ AT2sAxin2, and arrowheads indicate EdU+ Axin2− AT2s. (I) Quantification of average clone size and percent of EdU+ AT2s are represented as mean ± SEM, and size distribution is represented % of total clones. Two-tailed student's t-test: *P < 0.05 and Fisher's Exact Test: **P < 0.007, n=5 (58 clones) for AT2sAxin2, n=4 (191 clones) for total AT2s; Two-tailed student's t-test: ***P < 0.05, n=3 with 10 independent fields of view per mouse. Scale bars: A and B = 50 μm, E-H = 5 μm.