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 tissues. Human milk contains growth factors that maintain gastrointestinal mucosal homeostasis. We chose two major growth factors in human milk, TGF‐â (10 ng/ml) and IGF‐1 (30 ng/ml) to study global activation of TFs during early intestinal development in IEC‐6 (crypt cell) and FHs74 cells (fetal intestine). Active transcription factors were detected by Protein‐DNA Array. Among all the active TFs, EGR‐1 expression showed the most substantial up‐(IEC‐6 cell differentiation) and down‐regulation (FHs74 cell proliferation) after stimulation of the two cell lines. For IEC‐6 cells, EGR‐1 is predicted to have binding sites in the promoters of the Axin1 (‐258bp/260bp) and LRP5 (‐84bp/113bp) genes, which are mediators involved in the Wnt signaling pathway. The binding sites were verified by chromatin immunoprecipitation (CHIP) and EMSA. Changes in the Wnt/â‐catenin downstream targets Cyclin D and E‐cadherin further indicate that EGR1 interferes with the Wnt pathway through Axin1 and LRP5. In conclusion, we showed transcription factors regulated by growth factors during small intestinal development. EGR1 was further found to regulate the Wnt pathway through the multiprotein complex, which shows that human milk growth factors are likely to impact small intestinal development considerably.Grant Funding Source: research grant from Mead Johnson Nutrition