A knock-in Foxj1(CreERT2::GFP) mouse for recombination in epithelial cells with motile cilia.

The transcription factor Foxj1 is expressed by cells destined to differentiate into epithelial cells projecting motile cilia into fluid- or air-filled cavities. Here, we report the generation of an inducible knock-in Foxj1(CreERT2::GFP) mouse, which we show reliably induces Cre-mediated recombination for genetic studies in epithelial cells with motile cilia throughout embryonic and postnatal development. Induction during embryonic stages revealed efficient recombination in the epithelial component of the choroid plexus in the developing brain as early as E12.5. Induction during late embryonic stages showed confined recombination not only in the choroid plexus but also in the ventricular walls of the brain. Recombination induced during postnatal periods expanded to include epithelia of the lungs, testis, oviduct, and brain. Using these mice, we confirmed our recent discovery of a perinatally derived neuronal population in the mouse olfactory bulbs, which is derived from the Foxj1 lineage. Our Foxj1(CreERT2::GFP) knock-in mouse will be a powerful tool for studying molecular mechanisms associated with the continuum of cells that form the Foxj1 lineage, and for assessing their physiological significance during development and aging.