Generation of smooth muscle cell specific Cre transgenic mice

Objective:To establish transgenic mice that express Cre recombinase in smooth muscle cells specifically. Methods: A smooth muscle cell specific transgenic construct (α-SMA-Cre) containing the smooth muscle cell specific α-SMA promoter, the Cre recombinase gene and polyA was constructed. The 5.3 kb DNA fragments were microinjected into fertilized eggs. PCR analysis and LacZ staining were used to examine the function of Cre recombinase in the transgenic mice. Results: The injected 282 eggs were implanted into the oviducts of 10 female mice. In the 19 offspring, there were 4 mice carrying the transgene identified by PCR, and the efficiency of integration was 21%. The SMA-Cre transgenic mice were mated with Smad4 conditional knockout mice and ROSA26 mice to check the Cre mediated recombination in multiple tissues. After the Cre mediated recombination, primers amplified a fragment of 234 bp from the genomic DNA of all the tissues containing smooth muscle cells. LacZ staining showed that smooth muscles of intestine were positive. Conclusion:A kind of transgenic mouse that expresses Cre recombinase in smooth muscle cells specifically was established. The Cre recombinase was expressed in smooth muscle cells and could mediate the recombination between the LoxP sites in vivo.