Fig. 4.

Schematic representation of the overlapping embryonic (black) and postnatal (red) expression pattern of Pax2 and Pou4f3 promoters and the associated conditional, inducible expression constructs. (A) Note that GOI expression for this constructs is driven by a Tet_ON system that will be restricted to the embryonic and postnatal inner ear, an area of overlap (orange) for Pax2 (red) and Pou4f3 (yellow). (B) Regulation of the GOI is mediated by the absence or presence of Cre recombinase and the antibiotic (purple circle) tetracycline. The Pax2 promoter (red box) is used to drive Cre (gray box) expression. The loxP sites (triangle) are located 5′ and 3′ to the LacZ (dark blue box) gene. The Pou4f3 promoters in nonoverlapping expression areas (yellow box) and in overlapping with Pax2 expression are designated. The rtetR proteins (gray) in the absence tetracycline are unable to bind the Tet_ON regulatory elements (blue box) and the presence of antibotics permits rtetR protein (colored) binding. Expression of the LacZ reporter or the GOI (green box) is indicated by the green arrow while blockage of expression is indicated by parallel vertical lines.