Lyz1-H2BmCherry-IRES-CreERT2 Mice

Catalog Number: C001567

Strain Name: C57BL/6JCya-Lyz1em1(H2BmCherry-lRES-CreERT2)/Cya

Genetic Background: C57BL/6JCya

Reproduction: Carrier x WT

Examples of Expressing Tissues/Cells: Paneth cells of the small intestine

 

Strain Description

The Lyz1 gene encodes lysozyme C, a critical enzyme predominantly expressed in embryonic mesenchyme, intestine, liver, biliary system, and lungs. In mice, Paneth cells, specialized epithelial cells residing in the small intestine, serve as the principal source of lysozyme C. Studies have demonstrated that the targeted disruption of Lyz1 provides protection against experimental colitis. Loss of Lyz1 impairs the intestinal immune response to bacterial molecular patterns, thereby promoting the expansion of lysozyme-sensitive, mucus-dissolving bacterial populations [1].

The Lyz1-H2BmCherry-IRES-CreERT2 mice are constructed by knocking the H2BmCherry-IRES-CreERT2-rBG pA cassette into the mouse Lyz1 gene, a strategy that disrupts the expression of the endogenous Lyz1 gene. Without tamoxifen treatment, CreERT2 recombinase remains in the cytoplasm. After tamoxifen treatment, CreERT2 recombinase can enter the nucleus and exert its recombination function. Additionally, this model carries a red fluorescent protein (H2BmCherry) expression element, which can be used for lineage tracing of Lyz1-positive cells. When Lyz1-H2BmCherry-IRES-CreERT2 mice are crossed with mice containing loxP sites, tamoxifen-induced offspring will undergo Cre recombinase-mediated sequence recombination in Paneth cells of the small intestine. The red fluorescence expressed in this strain localizes to chromatin, facilitating detection.

Strain Strategy

The ATG start codon was replaced with the H2BmCherry-IRES-CreERT2-rBG pA cassette.


Validation Data

a. Method

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

b. Group

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/+]

c. Result

1) Expression of Cre recombinase in ileum

Figure 1. Detection of tdTomato Protein Autofluorescence in the Ileum. 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.

d. Summary

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.

Announcements

The insertion site of the Cre recombinase gene expression cassette in this strain is located on chromosome 10. Please avoid breeding with gene-edited mice targeting genes on the same chromosome as the Cre mouse when conducting mating.

 

References
[1]Yu S, Balasubramanian I, Laubitz D, Tong K, Bandyopadhyay S, Lin X, Flores J, Singh R, Liu Y, Macazana C, Zhao Y, Béguet-Crespel F, Patil K, Midura-Kiela MT, Wang D, Yap GS, Ferraris RP, Wei Z, Bonder EM, Häggblom MM, Zhang L, Douard V, Verzi MP, Cadwell K, Kiela PR, Gao N. Paneth Cell-Derived Lysozyme Defines the Composition of Mucolytic Microbiota and the Inflammatory Tone of the Intestine. Immunity. 2020 Aug 18;53(2):398-416.e8.