DICKKOPF-1 locates in the nucleus of human differentiated epithelial intestinal and mammary cells and regulates gene expression

Wnt/b-catenin pathway is a key modulator of intestinal homeostasis by regulating stem cell biology during gut organogenesis and in adult life. DICKKOPF (DKK)-1 is a secreted inhibitor of Wnt/b-catenin signaling from plasma membrane receptors. We found that in human intestine, DKK-1 locates within the nucleus of differentiated enterocytes and enteroendocrine cells but not of proliferating and stem cells at the bottom of the crypts. DKK-1 is also nuclear in colon cancer cells locating at sites of active gene transcription. ChIP-seq and transcriptomic analysis both confirmed that DKK-1 binds chromatin and regulates gene expression. Thus, we demonstrate that DKK-1 is a multifunctional protein that inhibits Wnt/b-catenin signaling at plasma membrane and controls specific genes in the nucleus, suggesting that these functions are relevant for intestinal homeostasis. Analysis of DKK-1 location and associated roles in human colon cancer cells and crypts of small and large bowel.