A mouse line expressing Foxa2-driven Cre recombinase in node, notochord, floorplate, and endoderm.

Foxa2 is a forkhead transcription factor expressed in the node, notochord, floorplate, and definitive endoderm and is required in the foregut endoderm for the normal development of the endoderm-derived organs, such as the liver, lung and pancreas. To conditionally inactivate genes in these tissues and organs, we have targeted a Cre recombinase into Exon 1 of the Foxa2 gene. We show, upon crossing to the ROSA26 reporter mice, that Cre expression from the Foxa2(iCre) knock-in allele specifically activates beta-galactosidase expression in the node, notochord, floorplate, and endoderm. In addition, we detect Cre recombination activity in the endoderm-derived organs including lung, liver, pancreas, and gastrointestinal tract throughout development. These results demonstrate that the Foxa2(iCre) knock-in mice are a valuable tool to analyze gene function in endoderm progenitors and endoderm-derived organs. Moreover, the widespread beta-galactosidase reporter activity in the endoderm suggests that Foxa2 marks a progenitor cell population, which gives rise to the majority of cells in endoderm-derived organs.