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-CreER;Rosa26eYFP (Bmi1Ctrl) and Bmi1-CreER;Rosa26eYFP;Klf4fl/fl (Bmi1ΔKlf4) 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 Bmi1ΔKlf4 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 Bmi1ΔKlf4 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.
Keywords: Goblet cell; Intestinal stem cell; Krüppel-like factor 4; Mucin 2.