Fig. 4. Cx26 mRNA, but not protein, is maintained in adult Mist1^KO acinar cells. (A-C) Immunohistochemical analysis of wild type (WT) pancreatic acinar cells reveals that Cx32 (red) and Cx26 (green) are localized to the same gap junction plaques. (D) WT and Mist1^KO pancreas RNA samples were subjected to RNA blot hybridization with the indicated nucleic acid probes. WT and Mist1^KO samples express equivalent levels of Cx26 mRNA. (E) Immunoblot analysis of Cx26 protein in 3-week old mice reveals that WT and Mist1^KO samples contain equivalent amounts of Cx26. However, samples from older Mist1^KO animals no longer contain detectable levels of Cx26 protein. (F-I) Cx26 immunofluorescence (green, arrows) was performed on 3-week-old pancreas sections from Mist1^Het and Mist1^KO mice. Whereas Mist1^Het mice exhibit normal, membrane bound Cx26 in the gap junctions (F,H), Cx26 protein in Mist1^KO samples is localized diffusely within the cell (G,I). Note that the boxed regions in F and G are shown at higher magnification in H and I. Adult acini from WT (J) and Mist1^KO (K) mice were also processed for Cx26 immunofluorescence (green, arrows). Adult Mist1^KO acinar cells do not show significant Cx26-containing gap junctions. Nuclei are stained with the DNA fluorochrome DAPI (blue).

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