Cre and Reporter Mice

Taking Cre expression occurring in as an example: Cre recombinase interacts with flox to mediate the splicing of the flox region into null. During subsequent -egg union and individual development, the null gene on this chromosome will be inherited and develop into systemic null expression.

When conducting relevant research using Cre strains, we can usually query the tissue expression information of Cre in the following ways: ① Query the references of the relevant strains; ② Query the Cre expression information induced by various promoters through MGI-Recombinase(Cre) Activity. If Cre is expressed in early embryos, the reproductive system, or widely throughout the body, then after breeding with flox strains, mice with systemic knockout of the flox gene may be directly obtained; ③ When the Cre used has no such reference information, the strain can be bred with Tool mice carrying a fluorescent reporter gene, and the applicability of Cre mice can be judged by observing the expression of the reporter gene in double-positive offspring. In addition, Cre strains driven by specific promoters may also have Cre activity in non-target tissues, and special attention needs to be paid to the leaky expression of Cre in the reproductive system. If there is leaky expression, it may prevent us from obtaining fl/fl;T mice, and the offspring may exhibit phenotypes related to systemic gene knockout. For example, the Prrx1 (paired related homeobox 1) promoter is expected to drive Cre expression in early limb buds and craniofacial regions, but staining results show that this Cre is also active in some oocytes in females and some interstitial cells in males. Therefore, to minimize the impact of leaky expression of Cre in the reproductive system, male Cre mice can be selected to breed with female flox mice, and mice with null bands can be excluded.