Inducible Cx40-Cre expression in the cardiac conduction system and arterial endothelial cells.

The Connexin-40 (Cx40) gene encodes a gap junction protein that plays an important role in cell-cell communication in cardiomyocytes of the atria and cardiac conduction system and endothelial cells of large arteries. During embryonic development, Cx40 expression is tightly regulated and correlates with progressive ventricular conduction system (VCS) differentiation and vessel function. We have generated Cx40(Cre) mice carrying a CreERT2-IRESmRFP cassette by targeted recombination. In Cx40(Cre) mice, the pattern of expression of RFP is identical to that of the endogenous Cx40 gene and a Cx40(GFP) allele. Using a LacZ-based Cre reporter mouse line, tamoxifen dependent Cre recombination was observed throughout the spatio-temporal profile of Cx40 expression in the VCS and arterial endothelial cells. Cx40(Cre) mice can therefore be used to direct inducible genetic modification in Cx40 expressing cells.