Figure 4.

Hair bundle proteins involved in stereociliary elongation

(A–C) Confocal images of the hair bundles from apical-coil IHCs of P25–P29 control Eps8^+/+ mice. Adult cochleae were immunostained for EPS8 (red) together with MYO15 (A), WHIRLIN (B), and BAIAP2L2 (C) (blue). All proteins showed the characteristic localization at the tip of the stereocilia, which were labeled with phalloidin (white). (D–K) Confocal images of the hair bundles from apical-coil IHCs of P25-P29 Eps8^−/− mice (D, E, H) and Eps8^−/− mice transduced with Anc80L65-EPS8 at P1–P2 (F, G, I). For Eps8^−/− mice, the individual color channels used in the “Merge” images in (D), (E), (H), and (J) are shown in Figure S6. In rescued hair bundles, both MYO15 and WHIRLIN localize at the tips of the taller stereocilia. Also, BAIAP2L2 exhibits its normal distribution at the top of the shorter transducing stereocilia. (J and K) Confocal images as shown in the above panels but from basal-coil IHCs of the adult cochlea of Eps8^−/− mice transduced with Anc80L65-EPS8 at P1. Note that the hair bundle of the transduced IHC retained an immature morphology, and that both EPS8 and WHIRLIN are localized throughout the several rows of the short stereocilia. Scale bar in the inset of (K), which also applies for panels (F), (G), and (I), represents 1 μm.