Stra8-P2A-ZsGreen1-T2A-Cre Mice

Catalog Number: C001536

Strain Name: C57BL/6JCya-Stra8^{em1(P2A-ZsGreen1-T2A-Cre)}/Cya

Genetic Background: C57BL/6JCya

Reproduction: Heterozygote x WT / Heterozygote x Heterozygote

Strain Description

The STRA8 gene encodes a meiosis-inducing factor required for the transition of both male and female germ cells to meiosis. It is involved in activating meiosis, cellular responses to retinoic acid, and germ cell development. STRA8 expression is limited to germ cells before meiosis. In females, STRA8 protein is expressed in embryos and ovaries. In males, it is expressed in the testes during puberty and adulthood, as well as in pre-meiotic germ cells, including certain A-type and B-type spermatogonia, preleptotene spermatocytes, and early leptotene spermatocytes (at the protein level). Expression begins in late undifferentiated spermatogonia and continues during differentiated spermatogonia (protein level).

The Stra8-P2A-ZsGreen1-T2A-Cre mouse is generated by inserting the “P2A-ZsGreen1-T2A-Cre” cassette upstream of the stop codon of the mouse Stra8 gene. Cre recombinase is expressed under the regulatory control of mouse Stra8 gene elements, without impacting the endogenous expression of the Stra8 gene. When crossed with mice containing loxP sites, the offspring can undergo sequence recombination between loxP sites in spermatogonial cells mediated by Cre recombinase. The heterozygotes are viable and fertile.

Strain Strategy

The TAA stop codon was replaced with the “P2A-ZsGreen1-T2A-Cre” cassette.

Validation Data

a. Method

Stra8-P2A-ZsGreen1-T2A-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, Cre recombinase-mediated deletion of the stop element (LSL) resulted in tdTomato protein expression in Cre-positive cells. Testicular and epididymal tissues from 4-week-old offspring mice were collected, and immunofluorescence (IF) analysis was performed to determine the distribution of tdTomato protein, thereby assessing Cre recombinase expression.

b. Group

Cre+: Stra8-P2A-ZsGreen1-T2A-Cre[KI/+]; Rosa26-LSL-tdTomato[CKI/+];

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

c. Result

1) Expression of Cre recombinase in testicles

Figure 1. tdTomato protein expression in testicles. Histological analysis revealed abundant red fluorescent signals of tdTomato protein in spermatogonial cells of Cre+ mice, indicating that Cre-mediated recombination occurs in this type of tissue.

2) Expression of Cre recombinase in the epididymis

Figure 2. tdTomato protein expression in the epididymis. Histological analysis revealed a small amount of red fluorescent signals from tdTomato protein in the epididymis of Cre+ mice, indicating that Cre-mediated recombination occurs in this type of tissue.

d. Summary

In the Stra8-P2A-ZsGreen1-T2A-Cre mice, the Cre recombinase expression is primarily concentrated in spermatogonial cells, with partial recombination signals also detected in the epididymis. Additionally, no significant spontaneous Zsgreen fluorescence signal was observed (data not shown). Overall, this model is suitable for tissue-specific research targeting spermatogonial cells.

Announcements

The Cre recombinase gene expression cassette is integrated into chromosome 6 in this strain. it is recommended to avoid breeding with Flox mice that have been targeted on the same chromosome.