Figure 6. Lysosomal function is required for metaplasia‐associated gene expression and increased proliferation.

1. Immunohistochemical analysis of SOX9 expression at peak SPEM stages following gastric injury. In control and Gnptab ^−/+ mice, SOX9 becomes expressed in reprogramming chief cells in the bases of the corpus at SPEM stages, but not in Gnptab ^−/− mice. Color‐coded boxes shown at higher magnification shown at right for panels (A and B). Scale bar, 50 μm; 25 μm pullout.
2. S‐phase, cell cycle marker BrdU is incorporated throughout the gastric corpus unit at peak SPEM stages in control WT or Gnptab ^−/+ mice. In Gnptab ^−/− mice, the gastric unit bases, where proliferation is recruited from chief cells, show a marked relative deficit in BrdU⁺ cells. Scale bar, 50 μm; 25 μm pullout.
3. Immunofluorescence analysis of injured gastric tissue from Gnptab ^−/− and control mice. GIF/GSII co‐expression is the hallmark of SPEM. In control mice, the vast majority of corpus unit bases are converted to GIF/GSII co‐expression state. In Gnptab ^−/− mice, bases are resistant to conversion and remain as GIF single positive cells. Red, GIF; green, GSII. Scale bar, 20 μm.
4. Quantification of randomly sampled 20× fields stained with BrdU. Distribution of BrdU in neck region vs. base region (note total = 100%) is plotted. Note control mice have equivalent amounts of BrdU‐labeled cells in the neck and base (˜50% in each), whereas Gnptab ^−/− mice BrdU‐labeled cells substantially shifted away from the paligenotic base of units and into the isthmal‐neck region, where the constitutive stem cell is active.
5. Quantification of randomly sampled 20× fields stained with BrdU in control and Gnptab ^−/− mice. Gnptab ^−/− mice have significantly more BrdU‐negative base cells compared to control animals.
6. Quantification of control and Gnptab ^−/− corpus units stained for SOX9 scored for the amount of SOX9‐negative chief cells per unit at peak SPEM stages. Gnptab ^−/− mice have significantly more SOX9‐negative bases compared to control animals.
7. Representative immunofluorescence images of injured control and Gnptab ^−/− pancreatic tissue at cerulein 5 days. Red, amylase; green, BrdU; blue, DAPI. White arrows show proliferating, amylase⁺ acinar‐derived cells (note these are not seen in Gnptab ^−/− mice). Yellow arrowheads show proliferating stromal cells that are not affected by loss of GNPTAB. Scale bar, 20 μm.
8. Representative immunohistochemistry of SOX9 stained control and Gnptab ^−/− pancreatic tissue at cerulein 5 days. Gnptab ^−/− tissue has reduced metaplastic phenotype and reduced expression of SOX9. Scale bar, 50 μm.
9. Quantification of amylase⁺BrdU⁺ cells of control and Gnptab ^−/− tissue in randomly sampled 20× fields at 5 days of cerulein injury.

Data information: **P < 0.01; ***P < 0.001 by t‐test with unequal variance; data represented as mean ± SEM of the means from 10 low‐power fields each from 3 independent experiments.