Generation of Pax2‐Cre mice by modification of a Pax2 bacterial artificial chromosome

The Pax2 gene is expressed in the developing otocyst, kidney, and midbrain-hindbrain boundary. We generated Pax2-Cre transgenic lines by modification of a Pax2 bacterial artificial chromosome (BAC). In one Pax2-Cre line, Cre mRNA starts to be expressed in the otic placode at the late presomite stage. R26R reporter mouse analysis revealed that the Cre expression is sufficient to delete the loxP-flanked sequences in most of the cells in the inner ear. Reporter-positive cells are also detected in other Pax2-expressing tissues such as midbrain, cerebellum, olfactory bulb, and kidney, suggesting that these cells are the descendants of Pax2-expressing cells in these tissues and that Pax2-Cre transgenic mice can delete genes efficiently in these tissues.