Validation of a Novel Knock-in Mouse Line Targeting FGF10 Cells Postnatally.

is a key gene during development, homeostasis and repair after injury. We previously reported a knock-in line (with the Cre-ERT2 cassette inserted in frame with the start codon of exon 1), called thereafter , to target FGF10 cells. While this line allowed fairly efficient and specific labeling of FGF10 cells during the embryonic stage, it failed to target these cells after birth, particularly in the postnatal lung, which has been the focus of our research. We report here the generation and validation of a new knock-in line (called thereafter ) with the insertion of the expression cassette in frame with the stop codon of exon 3. heterozygous mice exhibited comparable expression levels to wild type animals. However, a mismatch between and expression levels was observed in lungs. In addition, lung and limb agenesis were observed in homozygous embryos suggesting a loss of functional allele in mice. Bioinformatic analysis shows that the 3'UTR, where the Cre-ERT2 cassette is inserted, contains numerous putative transcription factor binding sites. By crossing this line with tdTomato reporter line, we demonstrated that tdTomato expression faithfully recapitulated expression during development. Importantly, mouse is capable of significantly targeting FGF10 cells in the adult lung. Therefore, despite the aforementioned limitations, this new line opens the way for future mechanistic experiments involving the postnatal lung.