HNF-3β is essential for node and notochord formation in mouse development

Abstract HNF -3β, a member of the HNF-3/fork head family of transcription factors, is expressed in the node, notochord, floor plate, and gut in mouse embryos. A null mutation of this gene leads to embryonic lethality. The primary defect of HNF-3β −/− embryos is an absence of organized node and notochord formation, which leads to secondary defects in dorsal-ventral patterning of the neural tube. In contrast, patterning along the anterior-posterior axis was surprisingly little affected. Although HNF-3β is required for node and notochord formation, some organizer activity persists in the absence of these structures. HNF-3β Is not required for the development of definitive endoderm cells, but foregut morphogenesis is severely affected in HNF-3β −/− embryos.