Figure 6. Neuroplastin and PMCA2 expressions are down-regulated in the outer hair cells (OHCs) with fused stereocilia in Manf^fl/fl;Pax2-Cre B6 mice.

(A, B) At P35, double-immunostaining for neuroplastin and PMCA2, coupled with phalloidin labeling, shows co-localization of these proteins in the 45-kHz OHC hair bundles in both control and cKO mice. In mutant specimen, many bundles show weak neuroplastin and PMCA2 expression (arrowhead). (A′, A″, B′, B″) The stainings are separately shown in these views. The down-regulation of both expressions is seen in the mutant specimen. (C, C″) At P56, PMCA2 expression is weak or undetectable in those OHCs that exhibit strong stereocilia fusion, as interpreted from phalloidin labeling (arrowheads in C′). Asterisks mark sites of lost OHCs. Abbreviations: B6, C57BL/6J strain; cKO, conditional knock out; Ctrl, control; OHC, outer hair cell; PMCA2, plasma membrane Ca²⁺ ATPase 2. Scale-bar: (A″) 5 μm in all images.