FIGURE 2.

TERC or TERT deficiency induced alveolar epithelial cell replicative senescence. A, SPC-positive staining of AECII in TERC-null mice by immunohistochemistry. Red arrows, SPC-positive staining; double yellow arrowheads, thin alveolar walls; asterisks, alveolar sacs. B, quantitation of AECII on the pulmonary sections from WT, G2, and G3 TERC-null mice. Data are the mean ± S.D. (error bars) from three animals. C, SPC mRNA expression in AECII from TERT-null mice. Data are the mean ± S.E. (error bars) (n = 8). D, podoplanin mRNA expression in alveolar epithelial type I cells from TERC-null mice. Data are the mean ± S.E. (n = 4). E, AECII in the lung of G3 TERC-null mice by flow cytometry labeled with APC-EpCAM and PE-podoplanin. The left and middle panels are representative of AECII sorting, and the right bar graph shows the pooled data (mean ± S.E.) from four animals. F, total alveolar epithelial cells in the lung of G3 TERC-null mice were labeled with APC-EpCAM and analyzed by flow cytometry. The left and middle panels are representative of cell sorting, and the right bar graph shows the pooled data (mean ± S.E.) from four animals.