Figure 7. Increased β-catenin activation, hyperproliferation, and elevated stem cell factor expression in IECs from IKK2ca^IEChom mice.

(A) Immunoblot analysis on cytoplasmic and nuclear extracts from colonic IECs showed increased levels of β-catenin and active N terminally nonphosphorylated β-catenin in 8-week-old IKK2ca^IEChom compared with IKK2ca^sFL mice. (B) Immunofluorescent staining for Ki67 reveals increased IEC proliferation in the colon of 10-week-old IKK2ca^IEChom mice, where the proliferating cells were extended toward the lumen. Whereas in control ileum, mainly the TA cells showed Ki67 staining, all crypt cells were Ki67⁺ in the ileum of IKK2ca^IEChom mice. (C) Immunohistochemical staining revealed increased numbers of Sox9-expressing IECs in the colon and SI of 10-week-old IKK2ca^IEChom compared with IKK2ca^sFL mice. Paneth cells and stem cells were not identifiable with Sox9 staining in SI crypts from IKK2ca^IEChom mice. (D and E) qRT-PCR analysis showed increased expression of intestinal stem cell factors in the colon (D) and in the SI (E) of 7- to 8-week-old IKK2ca^IEChom mice compared with IKK2ca^sFL littermates (n ≥ 6 per genotype; mRNA levels are presented as mean ± SD). (F) qRT-PCR analysis showed increased expression of DLK1 in the colon and in the ileum of 7- to 8-week-old IKK2ca^IEChom mice compared with IKK2ca^sFL littermates (n ≥ 6 per genotype; mRNA levels are presented as mean ± SD). Scale bars: 50 μm.