Figure 4. Ac45 is important for osteoclast bone resorption and F-actin ring formation.

(A) Knockdown of Ac45 impairs bone resorption. Ac45-silenced pre-osteoclasts cultured on bone discs for 48hrs were examined for bone resorptive activity by scanning electron microscopy (SEM). (B) The area of bone resorptive pits in each bone disc was quantified as a percentage of the whole bone disc area. (C) The resorptive activity per osteoclast was quantified as the average bone resorption area per osteoclast (%; total area/total osteoclast number). *P-values<0.05. (D and F) Low magnification (20X) confocal analysis of F-actin ring formation in Ctrl and Ac45 siRNA treated osteoclasts cultured on bone discs. Ac45-silenced osteoclasts cultured on bone discs were fixed and stained with rhodamine-conjugated phalloidin for the visualization of F-actin. Nuclei were counterstained with Hoechst. (E and G) Higher magnification (60X) confocal analysis of dotted region in E and F respectively. Osteoclasts are outlined in white. The average number of F-actin ring per osteoclast (H) and the average area ( µm²) of F-actin rings (I) were quantified. Data representative of three independent experiments (mean ± SEM). *P-values<0.05.