Figure 2

FCF, which stabilizes septin fibers, inhibits human OC resorption and in particular OCs making trenches. (A) Bone slices stained with toluidine after exposing bone resorbing OCs to various concentrations of FCF. Scale bar: 50 µm. (B) Total number of TRAcP⁺ cells with 2 nuclei or more per bone slice with and without FCF. Statistics: Kruskal-Wallis test, two-tailed, p = ns (not significant); horizontal line indicates the median. (C) Metabolic activity of cells seeded on the same bone slices as shown in A. Statistics: Kruskal-Wallis test, two-tailed, **p = 0.0014; Dunn’s multiple comparisons test, **p = 0.0056 compared to 0 µM FCF; horizontal line indicates the median. (D) IC50 of FCF with respect to the total number of resorption events per bone slice. Linear fit, r² = 0.92; IC50 = 28.99 µM. (E) IC50 of FCF based on data shown in D, but sub-split into pits and trenches. Pits: linear fit, r² = 0.79. IC50 = 32.6 µM; Trenches: non-linear fit, r² = 0.90. IC50 = 18.0 µM. (F) IC50 of FCF with respect to the total eroded surface (ES). Non-linear fit, r² = 0.92. IC50 = 18.97 µM. (G) IC50 of FCF based on data shown in F, but sub-split into pits and trenches. Pits: non-linear fit, r² = 0.53. IC50 = 54.65 µM; Trenches: non-linear fit, r² = 0.93. IC50 = 16.57 µM. (D–G) Each data point represents the mean ± SD (n = 4) from a representative experiment (a total of five independent experiments). (H) Comparison of FCF IC50s for pits and trenches, respectively, showing the means from five independent experiments. Statistics: Wilcoxon matched-pairs signed rank test, one-tailed, *p = 0.03.