Fig. 2: Radixin expression and localization in guinea pig cochlear hair cells.

a Schematic diagram showing the putative function of radixin in stereocilia. b A low magnification image of the temporal bone preparation. Note the apical opening used for imaging. c Release of the dye di-3-ANEPPDHQ into the endolymphatic space stained Reissner’s membrane as well as the hair bundles. d Outer hair cell (OHC) stereocilia imaged during sound stimulation at 220 Hz, 80 dB sound pressure level. e Representative confocal images of sections of the organ of Corti labeled with phalloidin (red, staining actin) and a radixin-specific monoclonal antibody (green), as well as an overlay. The bundles of the sensory hair cells are intensely labeled by the radixin antibody. OHC 1, 2, 3 indicate the three rows of outer hair cells. Images were taken from the surface preparations of the apical turn. e’ Inset showing a higher magnification view. f Three-dimensional reconstruction of the inner hair cell area shows absence of radixin label in the cell bodies of the inner hair cells. Likewise, no radixin label was detected in the neuronal or synaptic region of the inner hair cells. g A 3D reconstruction of OHC stereocilia showing predominance of radixin labeling near the stereocilia base and consistent actin labeling in the cuticular plate and stereocilia bundles. h Normalized average ± s.e.m. (dotted) signal intensity profiles for radixin and actin expression (average of 11 bundles from 3 different animals) which shows decline in radixin labeling toward the tip of stereocilia and consistent actin labeling by phalloidin throughout the stereocilia. i Scatter plot showing lack of relation between radixin and phalloidin pixel intensities.