Figure 3. Distribution of F-actin and USH1 proteins in OHCs lacking clarin-1.

(A) Distribution of USH1 proteins (myosin VIIa, harmonin b, cadherin-23, protocadherin-15) and stereocilin in the apical region of F-actin–labeled stereocilia (red) in P12 control mice. (B) The typical targeting and localization of USH1 proteins in the stereocilia is preserved in the absence of clarin-1, regardless of the shape of the Clrn1^ex4–/– hair bundles. (C) The F-actin labeling of the cuticular plate in P12 Clrn1^ex4–/– mice is irregular, with the presence of furrows delimiting regions of clumped stereocilia. Stereocilin immunostaining (green) was used to visualize the hair bundle stereocilia. (D) No such irregularity of staining is observed in OHCs from control and Clrn1^ex4fl/fl Myo15-Cre^+/– mice. Scanning electron microscopy micrographs show selected OHC hair bundles (from P12 Clrn1^ex4–/–, P15 control, and P20 Clrn1^ex4fl/fl Myo15-Cre^+/– mice) with hair bundle shapes similar to those of the immunostained hair bundles. Images obtained from 2–5 mice for each genotype. Scale bars: 1 μm.