Abstract
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) (Bmi1Ctrl) 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 Bmi1Ctrl 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 Bmi1Ctrl 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.