Figure 1

The Gjd3^{3′UTR-IRES-CreEGFP/+} allele mediates recombination in the postnatal AV junction. (a) Schematic of the endogenous Gjd3 locus (encoding for mouse Cx30.2) comprising untranslated exon 1 and exon 2, which contains the coding region (orange box) and 3′UTR (black box). A targeting vector was designed to insert an IRES-CreEGFP-FRT-Neo^R-FRT cassette into the Gjd3 3′UTR. Following FLP-mediated recombination, CreEGFP is expressed under the control of the native regulatory sequences. PCR genotyping primer sets (F1-R1, F2-R2, and F3-R3) are indicated by black arrows, and the Gjd3 stop codon is shown. (b) Whole mount fluorescent images of hearts dissected from Gjd3^{3′UTR-IRES-CreEGFP/+}; R26R^tdTomato/+ mice at P0, P7, P14, P21, and P28. Robust tdTomato expression is observed at the AV junction (dashed outline). Number of hearts dissected (n) = 12 per group of animals; LA, Left Atrium; RA Right Atrium; LV, Left Ventricle; RV, Right Ventricle. Scale bar: 500 µm.