Characterization of Adult Vestibular Organs in 11 CreER Mouse Lines.

Utricles are vestibular sense organs that encode linear head movements. They are composed of a sensory epithelium with type I and type II hair cells and supporting cells, sitting atop connective tissue, through which vestibular nerves project. We characterized utricular Cre expression in 11 murine CreER lines using the ROSA26 reporter line and tamoxifen induction at 6 weeks of age. This characterization included Calbindin2, Fgfr3-iCreER, GFAP-A-CreER™, GFAP-B-CreER™, GLAST-CreER, Id2, Otoferlin, Parvalbumin, Prox1, Sox2, and Sox9-CreER. Otoferlin mice had inducible Cre activity specific to hair cells. GLAST-CreER, Id2, and Sox9-CreER had inducible Cre activity specific to supporting cells. Sox2 had inducible Cre activity in supporting cells and most type II hair cells. Parvalbumin mice had small numbers of labeled vestibular nerve afferents. Calbindin2 mice had labeling of most type II hair cells and some type I hair cells and supporting cells. Only rare (or no) tdTomato-positive cells were detected in utricles of Fgfr3-iCreER, GFAP-A-CreER™, GFAP-B-CreER™, and Prox1 mice. No Cre leakiness (tdTomato expression in the absence of tamoxifen) was observed in Otoferlin mice. A small degree of leakiness was seen in GLAST-CreER, Id2, Sox2, and Sox9-CreER lines. Calbindin2 mice had similar tdTomato expression with or without tamoxifen, indicating lack of inducible control under the conditions tested. In conclusion, 5 lines-GLAST-CreER, Id2, Otoferlin, Sox2, and Sox9-CreER-showed cell-selective, inducible Cre activity with little leakiness, providing new genetic tools for researchers studying the vestibular periphery.