Generation and characterization of transgenic mice expressing tamoxifen-inducible cre-fusion protein specifically in mouse liver

AIM: To establish transgenic mice expressing tamoxifeninducible Cre-ERt recombinase specifically in the liver and to provide an efficient animal model for studying gene function in the liver and creating various mouse models mimicking human diseases.METHODS: Alb-Cre-ERt transgenic mice were produced by microinjecting the construct with Cre-ERt fusion gene of DNA fragments into fertilized eggs derived from inbred C57BL/6strain. Transgenic mice were identified by using PCR and Southern blotting. Expression of Cre-ERt fusion gene was analyzed in the liver, kidney, brain and lung from F1generation transgenic mice at 8 weeks of age by reverse transcription (RT)-PCR.RESULTS: Four hundred and fourteen fertilized eggs of C57 BL/6 mice were microinjected with recombinant AlbCre-ERt DNA fragments, and 312 survival eggs injected were transferred to the oviducts of 12 pseudopregnant recipient mice, 6 of 12 recipient mice became pregnant and gave birth to 44 offsprings. Of the 44 offsprings, two males and one female carried the hybrid Cre-ERt fusion gene. Three mice were determined as founders, and were back crossed to set up F1 generations with other inbred C57BL/6 mice.Transmission of Cre-ERt fusion gene in F1 offspring followed Mendelian rules. The expression of Cre-ERt mRNA was detected only in the liver of F1 offspring from two of three founder mice.CONCLUSION: Transgenic mice expressing tamoxifeninducible Cre-ERt recombinase under control of the liverspecific promoter are preliminary established.