Generation of an inducible RPE-specific <i>Cre</i> transgenic-mouse line

The retinal pigment epithelium (RPE) is an epithelial monolayer in the back of the vertebrate eye. RPE dysfunction is associated with retinal degeneration and blindness. In order to fully understand how dysregulation affects visual function, RPE-specific gene knockouts are indispensable. Since the currently available RPE-specific Cre recombinases show lack of specificity or poor recombination, we sought to generate an alternative. We generated a tamoxifen-inducible RPE-specific Cre transgenic mouse line under transcriptional control of an RPE-specific Tyrosinase enhancer. We characterized the Cre-mediated recombinant expression by crossing our RPE-Tyrosinase-CreErT2 mouse line with the tdTomato reporter line, Ai14. Detected fluorescence was quantified via high-content image analysis. Recombination was predominantly observed in the RPE and adjacent ciliary body. RPE flatmount preparations revealed a high level of recombination in adult mice (47.25–69.48%). Regional analysis of dorsal, ventral, nasal and temporal areas did not show significant changes in recombination. However, recombination was higher in the central RPE compared to the periphery. Higher levels of Cre-mediated recombinant expression was observed in embryonic RPE (~83%). Compared to other RPE-specific Cre transgenic mouse lines, this newly generated RPE-Tyrosinase-CreErT2 line shows a more uniform and higher level of recombination with the advantage to initiate recombination in both, prenatal and postnatal animals. This line can serve as a valuable tool for researches exploring the role of individual gene functions, in both developing and differentiated RPE.