KLF4 Regulates Goblet Cell Differentiation in BMI1(+) Reserve Intestinal Stem Cell Lineage during Homeostasis

Krüppel-like factor 4 (KLF4) is a zinc-finger transcription factor, expressed in villus cells of the intestinal epithelium, that promotes cellular differentiation and tissue homeostasis. Previous studies suggest that BMI1(+) cells represent secretory progenitors with reserve intestinal stem cell (rISC) activity. However, it has not been elucidated how KLF4 contributes to crypt regeneration originated from BMI1(+) rISC lineage during homeostasis. In this study, Bmi1-Cre(ER);Rosa26(eYFP) (Bmi1(Ctrl)) and Bmi1-Cre(ER);Rosa26(eYFP);Klf4(fl/fl) (Bmi1(ΔKlf4)) mice were injected with tamoxifen to label BMI1(+) cells and their lineage and to delete Klf4. During homeostasis, MUC2(+) goblet cells appeared in the BMI1(+) cell lineage 2, 3 and 7 days after tamoxifen administration. After Klf4 deletion in BMI1(+) cells, the number of KLF4(+) and MUC2(+) cells in eYFP(+) cells decreased in Bmi1(ΔKlf4) mice compared with Bmi1(Ctrl) mice. Thus, KLF4 was positively correlated with goblet cell differentiation in BMI1(+) cell derived lineage. In ex-vivo analysis, organoids derived from single eYFP(+) cells of Bmi1(Ctrl) mice contained MUC2-expressing cells that co-expressed KLF4. On the other hand, organoids derived from Klf4-deleted eYFP(+) cells from Bmi1(ΔKlf4) mice showed reduced number of MUC2-expressing cells. In conclusion, these results suggest that KLF4 regulates goblet cell differentiation in BMI1(+) ISC-derived lineage during homeostasis.