Lyz1-H2BmCherry-lRES-CreERT2 Mouse

Lyz1-H2BmCherry-IRES-CreERT2 mice were crossed with Rosa26-LSL-tdTomato mice, which conditionally express a red fluorescent protein (tdTomato). When the offspring mice reach 8 weeks of age, they are intraperitoneally injected with tamoxifen at a dose of 50 mg/kg every 48 hours for a total of 5 times. The Cre recombinase-mediated deletion of the loxP-flanked STOP cassette (LSL) will result in the expression of tdTomato protein in Cre-positive cells. Seven days after the induction, ileal tissues are collected and analyzed using frozen sections to detect autofluorescence and confirm Cre recombinase expression.

Cre+Tam+: Lyz1-H2BmCherry-IRES-CreERT2[KI/+]; Rosa26-LSL-tdTomato[CKI/+]; Tamoxifen

Cre+Tam-: Lyz1-H2BmCherry-IRES-CreERT2[KI/+]; Rosa26-LSL-tdTomato[CKI/+]; Corn oil

Cre-Tam+: Rosa26-LSL-tdTomato[CKI/+]; Tamoxifen

Cre+: Lyz1-H2BmCherry-IRES-CreERT2[KI/+]

Histological analysis indicates that no significant mCherry autofluorescence is observed in the intestines of Lyz1-H2BmCherry-IRES-CreERT2 mice, suggesting that this strain exhibits weak autofluorescence. After mating Lyz1-H2BmCherry-IRES-CreERT2 mice with Rosa26-LSL-tdTomato mice, prominent orange tdTomato autofluorescence is observed in the Paneth cells at the base of the intestinal glands in tamoxifen-treated mice (Cre+Tam+), indicating that Cre recombination has occurred in these tissues. No orange tdTomato autofluorescence is detected in the ileal tissues of tamoxifen control mice (Cre+Tam-). Additionally, combined with internal PCR validation results, it is inferred that Lyz1-H2BmCherry-IRES-CreERT2 mice do not exhibit significant leakage without tamoxifen induction.

In the Lyz1-H2BmCherry-IRES-CreERT2 mouse model, Cre recombinase is significantly expressed in the Paneth cells of the adult mouse small intestine. It is recommended to use a tamoxifen dosage of 50-100 mg/kg, administered every 48 hours for 5 times, with tissue collection 7 days after induction showing the best results.