Figure S3. Abnormal expression of the taper region proteins is restricted to the adult high-frequency outer hair cells (OHCs) in Manf^fl/fl;Pax2-Cre B6 mice.

(A, B, B′, C, D, D′) PTPRQ immunostaining coupled with phalloidin labeling shows PTPRQ expression in the tapering region of 45-kHz inner hair cells (IHCs) in both control and cKO mice at P56. A single representative IHC is presented from each genotype as a maximum intensity projection spanning the stereocilia and cuticular plate in a top-down perspective. (E, F, F′, G, H, H′) Radixin is expressed in the stereocilia and tapering region of 45-kHz IHCs in P56 control and mutant mice. Radixin expression looks less granular than that of PTPRQ because the stereociliary radixin projection obscures the detailed organization in the taper region. (I, J, J′, K, L, L′) Myosin 6 expression in the cuticular plate of 45-kHz IHCs is comparable in P56 control and mutant mice. Myosin 6 was also expressed in the hair cell bodies, but expression was not detected in stereocilia. (M, M′, N, N′) At P22, PTPRQ expression is absent from 45-kHz OHCs in both control and mutant mice, in contrast to what it seen in the adult 45-kHz OHCs with fused stereocilia (see Fig 5). (O, O′, P, P′) At P15, radixin expression in 45-kHz OHCs is comparable in mutant and control mice. (Q, Q′, R, R′) At P56, PTPRQ is up-regulated in occasional OHCs in the 16-kHz region of mutant cochleas. The intensity of this expression varied between OHCs. (S, T) At P56, alpha-2-spectrin is strongly expressed in the OHC cuticular plates in control mice. This expression was unaltered in the OHC cuticular plates of mutants, despite the strong decrease in phalloidin labeling (see Fig 5). The lost OHCs in mutant cochleas are marked with asterisks. Abbreviations: B6, C57BL/6J strain; cKO, conditional knock out; Ctrl, control; IHC, inner hair cell; OHC, outer hair cell; PTPRQ, Protein Tyrosine Phosphatase Receptor Type Q. Scale bars: (A) 10 μm A, C, E, G, I, K; (B) 1 μm B, B′, D, D′, F, F′, H, H′, J, J′, L, L’; (M) 5 μm M-T.