Elf5-Cre Mice

The TGA stop codon was replaced with the “P2A-Cre-WPRE-rBG pA” cassette.

a. Method

The Elf5-Cre mice were bred with Rosa26-LSL-tdTomato mice to generate double heterozygous offspring. Cre-mediated recombination will result in the expression of tdTomato protein in the Cre-positive cells of the offspring. The mammary gland, uterus, ovary, testis, epididymis, prostate, adrenal gland, and skin tissues of 6-week-old offspring mice were collected and immunofluorescence was used to observe the expression of tdTomato protein to determine the activity of Cre recombinase.

b. Genotype

Cre+: Elf5-Cre[KI/+]; Rosa26-LSL-tdTomato[CKI/+]
Cre-: Rosa26-LSL-tdTomato[CKI/CKI]

c. Result

1. Expression of Cre recombinase in the uterus

Figure 1. Immunofluorescence staining of the uterus in female mice. In Cre+ female mice, there was a large amount of red fluorescence from tdTomato protein in uterine cells, indicating that a large amount of Cre recombinase-mediated recombination occurred in this location. In contrast, no expression of tdTomato red fluorescence was detected in the control group (Cre-) mice, indicating the absence of Cre recombinase.

2. Expression of Cre recombinase in the female mammary gland and ovary

Figure 2. Immunofluorescence staining of the mammary glands and ovaries in female mice. In Cre+ female mice, there was a large amount of red fluorescence from tdTomato protein in the mammary gland, which was almost completely co-localized with the DAPI signal, indicating that a large amount of Cre recombinase-mediated recombination occurred in this location. In contrast, no expression of tdTomato red fluorescence was detected in the control group (Cre-) mice, indicating the absence of Cre recombinase. However, there was no red fluorescence signal from tdTomato protein in the ovary, indicating that there was no Cre recombinase-mediated recombination in this location.

3. Expression of Cre recombinase in the male reproductive system and prostate gland

Figure 3. Immunofluorescence staining of the testis, epididymis, and prostate gland in male mice. In Cre+ male mice, there was a large amount of red fluorescence in the suspected spermatogenesis region of the testis, epididymis, and prostate gland, indicating that Cre recombinase-mediated recombination occurred in these areas. In contrast, no expression of tdTomato red fluorescence was detected in the control group (Cre-) mice, indicating the absence of Cre recombinase.

4. Expression of Cre recombinase in the skin and ureters

Figure 4. Immunofluorescence staining of the skin and ureters. In Cre+ mice, there was partial red fluorescence in some cells of the skin hair follicles, some sebaceous gland cells, and the ureter, indicating that Cre recombination occurred in these areas. In contrast, no expression of tdTomato red fluorescence was detected in the control group (Cre-) mice, indicating the absence of Cre recombinase.

5. Expression of Cre recombinase in the adrenal gland

Figure 5. Immunofluorescence staining of the adrenal gland. In Cre+ mice, no red fluorescence was detected in the adrenal gland, indicating that there was no Cre recombinase-mediated recombination occurring in this area.

6. Expression of Cre recombinase in the embryonic stage placenta

Figure 6. Immunofluorescence staining of placental tissue at different embryonic stages. In Cre+ mice, a significant red fluorescent signal was detected in the placenta of embryos at E10, E15, and E18, indicating a large amount of Cre recombinase expression in this area. In contrast, no red fluorescence from tdTomato was detected in the control group (Cre-) mice, indicating the absence of Cre recombinase.

d. Summary

In the Elf5-Cre mice, the expression of Cre recombinase is mainly localized in the placenta, columnar epithelial cells of the uterus, mammary ductal epithelial cells, and some hair follicles and sebaceous gland cells of the skin. At the same time, recombination mediated by Cre recombinase can be partially detected in the ureter and testis, epididymis, and prostate gland of male mice. However, almost no recombination signal was found in the ovary and adrenal glands. The expression of Cre recombinase in this model is similar to that of the endogenous Elf5 gene in mice and has good specificity.

The Cre recombinase gene is located on chromosome 2 in Elf5-Cre mice. Please avoid using mice that have been targeted on the same chromosome for breeding.