Genetic Lineage Tracing in Mice

Eight- to twelve-week-old male and female C57BL6/J mice, Lgr5-eGFP-IRES-CreERT2 mice, Gt (ROSA)26Sortm4(ACTB-tdTomato- EGFP) Luo/J mice, and B6. Cg-Gt (ROSA)26Sortm9(CAG- tdTomato) Hze/J mice were purchased from Jackson laboratories. Lgr5-eGFP-IRES-CreERT2 mice were crossed with Gt (ROSA)26Sortm4(ACTB-tdTomato-EGFP) Luo/J mice (Jackson Laboratories) to generate Lgr5/eGFP-IRES-Cre-ERT2; R26-ACTB-tdTomato-EGFP [23 (link),24 (link)]. In Gt (ROSA)26Sortm4(ACTB- tdTomato-EGFP) Luo/J mice tdTomato is constitutively expressed (independent of Cre recombination) in the membrane of all the cells, and therefore allows better visualization of cellular morphology. Lgr5-eGFP-IRES-CreERT2 mice were crossed with B6 Cg-Gt (ROSA)26Sortm9(CAG-tdTomato) Hze/J mice (Jackson Laboratories) to generate the Lgr5-eGFP-IRES-CreERT2; the Rosa26-CAG-tdTomato heterozygote was used for lineage tracing experiments. All the mice were maintained ad libitum, and all the studies were performed under the guidelines and protocols of the Institutional Animal Care and Use Committee of the University of Kansas Medical Center. All the animal experimental protocols were approved by the Institutional Animal Care and Use Committee of the University of Kansas Medical Center (ACUP number 2019-2487).