Fig. 4.

Examples of fluorescent markers used to sort cell-types in the cochlea. (A) Schematic representation of Cre-dependent expression of the reporter protein tdTomato in the Ai14 mouse model. (B) Expression of GFP in HCs in the transgenic Atoh1-GFP mouse expressing GFP under the control of the Atoh1 enhancer. (C) Specificity of different Cre mouse models assessed with a reporter mouse (Ai14). The Myo15 promoter is used to mark all HC starting at P4 (Myo15Cre). The Slc26a5 promoter (regulating the expression of the OHC protein prestin) has been utilized to drive inducible Cre recombinase expression specifically in OHCs (PrestinCreERT2, expression in all OHC starting at P7 with induction at P2). The promoter of Gfi1 (Gfi1Cre and Gfi1-P2A-GFP-CreERT2 (Gfi1-GCE)) is used to induce expression in all HCs starting at E16.5 but has been shown to induce recombination in Monocytes/Macropahges (M) as well. The Sox2 promoter has been used for recombination in embryonic prosensory cells, supporting cells (DC- Deiters Cells; PC- Pillar Cells; BC- Border Cells), and glial cells (GC) of the spiral ganglion, depending on the time point of induction (Sox2CreERT2). Scale bar is 20 μm. (D) Labeling of HCs with FM1–43. The dye in incorporated by OHC and IHC at P2 but mainly by OHC starting at P5.