Transcriptional Networks and Signaling Pathways That Govern Vertebrate Intestinal Development

The vertebrate intestine is a complex and highly specialized organ comprising tissues derived from all three germ layers. While a description of the morphological events underlying the consolidation and organization of the endoderm, mesoderm, and ectoderm-derived cells into a multi-layered, continuously renewing organ has been available for several decades, only recently has a strong genetic framework for this process started to emerge, and as yet it remains incomplete. This review highlights the roles played by a number of transcription factors and signaling pathways in the development of the vertebrate intestine from the moment the definitive endoderm is formed. These molecular pathways often interact with each other and play multiple roles at different stages of intestinal formation. What is currently attracting considerable attention in the field is the realization that the deregulated activities of these same pathways often play a key role in the initiation and progression of a number of complex, serious intestinal diseases, including inflammatory bowel disease and cancer.