Cd19-Cre Mice

Catalog Number: I001184

Strain Name: C57BL/6JCya-Cd19em2(Cre)/Cya

Genetic Background: C57BL/6JCya

 

Strain Description

The cluster of differentiation 19 (CD19) gene encodes a member of the immunoglobulin gene superfamily, whose expression is restricted to B lymphocytes and is a marker of pre-B cells. In humans, CD19 is expressed on all cells of the B lymphoid lineage except plasma cells and follicular dendritic cells. CD19 acts as an adapter protein to recruit cytoplasmic signaling proteins to the membrane and acts within the CD19/CD21 complex to lower the threshold of the B cell receptor signaling pathway. The protein is a biomarker for B lymphocyte development and lymphoma diagnosis and may serve as a target for leukemia immunotherapy. Mutations in this gene are associated with common variable immunodeficiency 3 (CVID3) disease, which is characterized by hypogammaglobulinemia, failure to mount an antibody response to antigen, and recurrent bacterial infections, and certain loss-of-function mutations in this gene also fails B cell differentiation and impaired immunoglobulin secretion.

CD19-Cre mice were constructed by inserting a Cre recombinase gene expression element into the endogenous Cd19 gene of mice to drive its specific expression. A "Rabbit β-globin intron" is attached downstream of the Cre recombinase gene expression element, which can greatly increase the expression level of Cre recombinase. When this strain is crossed with mice containing the loxP locus, sequence recombination between loxP loci mediated by Cre recombinase can occur in the majority of B-lymph spectrum cells of the offspring mice.

Strain Strategy

The “Cre-CYAGEN-Rabbit β-globin intron and flanking region-rBG pA” gene expression element was integrated into the endogenous Cd19 gene of mice by gene editing technology. The CYAGEN element represents the specific identification sequence of Cyagen Biosciences.



Validation Data

a. Method

Cd19-Cre mice were crossed with Rosa26-LSL-tdTomato mice, which conditionally express a red fluorescent protein (tdTomato), to generate double-heterozygous offspring. In the offspring, deletion of the loxP-stop-loxP (LSL) cassette by Cre recombinase leads to tdTomato protein expression in Cre-positive cells. When these offsprings developed to 6 weeks of age, peripheral blood, spleen, and bone marrow tissues were collected and analyzed for tdTomato protein distribution by flow cytometry to determine Cre recombinase expression.

b. Group

Cre+: Cd19-Cre[KI/+];Rosa26-LSL-tdTomato[CKI/+];

Cre-: Rosa26-LSL-tdTomato[CKI/CKI].

c. Result

1) Expression of Cre recombinase in B cells from peripheral blood, spleen, and bone marrow


Figure 1. Flow cytometry detection of tdTomato protein expression in B cells from peripheral blood (PB), spleen, and bone marrow (BM). The results showed that B cells in peripheral blood, spleen, and bone marrow tissues of Cre+ mice showed higher levels of tdTomato-positive signals. This suggests that tdTomato protein expression mediated by Cre recombinase occurs in these cells. B cells from peripheral blood showed the highest efficiency of recombination, with more than 50% of the cells expressing tdTomato; while B cells from spleen and bone marrow showed slightly lower efficiency of recombination. In contrast, Cre- mice show no detectable Cre recombinase activity in corresponding tissues.

2) Expression of Cre recombinase in T cells from peripheral blood, spleen, and bone marrow


Figure 2. Flow cytometry detection of tdTomato protein expression in T cells from peripheral blood (PB), spleen, and bone marrow (BM). The results showed that tdTomato-positive signals were virtually absent from T cells in the peripheral blood, spleen, and bone marrow of Cre+ mice, suggesting that Cre recombinase is not expressed in such cells. In addition, Cre recombinase activity was also not detected in T cells from Cre- mice.

d. Summary

In Cd19-Cre mice, Cre recombinase is expressed mainly in B cells in tissues such as peripheral blood, spleen, and bone marrow, whereas there is no Cre recombinase activity in T cells. Taken together, this model can be used for tissue-specific studies targeting B lymphocytes.

 

Announcement

The Cre recombinase gene expression cassette is integrated into chromosome 7 in this strain. It is recommended to avoid breeding with Flox mice that have been targeted on the same chromosome.