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.