Figure 7. Inhibition of Gαi reverses hair bundle orientation in the Emx2-positive domain of maculae.

(A–B’) In control utricles, hair bundles are pointing toward medial and lateral in the respective LES and MES (arrows), and Gαi staining (A’,B’) is associated with the kinocilium (A,B; n = 3). (C–D’) In Foxg1^Cre/+;Rosa^Ptx/+ utricles, hair bundles in the LES (C) are sometimes reversed (red arrows) or misoriented (blue arrows) but not in the MES (D; n = 3). The accumulation of Gαi in HCs is reduced across the utricle (C’,D’, arrowheads). Occasionally, uncoupling between the kinocilium and Gαi is found in HCs of the LES (C-C’, asterisks). (E,F) Quantification of the hair bundle orientation in regions L and M of control and Foxg1^Cre/+; Rosa^Ptx/+ utricles are plotted in a bar graph (E; Figure 7—source data 1) and circular histogram (F). HCs with the kinocilium positioned within 30°-150° are green (pointing medial), between 210°-330° are pink (pointing lateral), and intermediates (misoriented) are denoted by grey. In region L of mutants, 15% HCs showed abnormal hair bundle orientations. (G–J’) Compared to controls (G-H’; n = 3), reduced Gαi is observed across Foxg1^Cre/+;Rosa^Ptx/+ saccules (I-J’; n = 3) but misoriented (blue arrows) or reversed (red arrows) kinocilia are only found in the IR (I–I’) but not the OR (J–J’). (K–L) Quantification of hair bundle orientation pointing toward inner or outer margin are defined as 30°–150° (green) or 210°–330° (pink), respectively (Figure 7—source data 1). In the IR of mutants, 46% of hair bundles showed reversed or misoriented polarity. Red asterisks, arrows, and lines represent hair bundle reversal, misorientation, and average degree of HC orientation, respectively. Schematic diagrams indicate the locations of where the corresponding panels were taken as well as positions of all HCs with reversed hair bundles are found in the sample (red dots). **p<0.01, ***p<0.001.

DOI: http://dx.doi.org/10.7554/eLife.23661.019