Active transcription factors in the development of the small intestine during early life

Abstract

Transcription factors (TFs) regulate downstream gene expression individually or cooperatively in different cell types and specific tissues. Human milk contains several growth factors that maintain gastrointestinal mucosal homeostasis. We chose two major growth factors in human milk, TGF‐β and IGF‐1 to study global activation of TFs during early intestinal development in IEC‐6 (crypt cell) and FH74 cells (fetal intestine). TGF‐β treatment (10 ng/ml) for 5d significantly induced differentiation (expression of alkaline phosphatase) of IEC‐6 and lead to an abundance of cytoplasm and clear cell boundaries. Optimum proliferation of FHs 74 was found at 30 ng/ml IGF‐1 treatment for 24h (no significant change in morphology). Active transcription factors were detected by Protein‐DNA Array. For IEC‐6 cells, we found EGR1 and YY1 were upregulated; CREB, E2F1, Pax3 and OCT1 were downregulated. By bioinformatics analysis, we found 3 binding sites for EGR1 in the promoter of mir‐146b (−795/−786, −900/−812, −1013/−1005), which has been shown to be upregulated and play a role in TGF‐β signaling. In FHs 74 cells, c‐Myb was upregulated, whereas CREB, EGR1, P53 and Pax3 were downregulated. In conclusion, we showed several transcription factors are regulated by TGF‐β and IGF‐1 during small intestinal development. EGR1 was further found to participate in miRNA regulation of the TGF‐β treatment.Grant Funding Source : Mead Johnson Nutrition Global Discovery