Figure 3. F-actin depolymerization reduces membrane tension.
(A) To measure surface tension in oligodendrocytes we used an optical trap setup to pull membrane tubes (tethers) in a vertical direction with high force resolution. We cultured cells for 2 and 5 days in vitro (div). Treatment for 2 hours with 5 μM latrunculin A (LatA) and 5 μM cytochalasin D (CytoD) reduced tether forces, whereas 50 μM blebbistatin (Blebb) and 10 μM Y27631 (Y27) had no effect. Static tether force is shown as mean ± SEM (n=37-80 cells for each condition; ***p < 0.001). (B) Atomic force microscopy (AFM) was used to measure membrane tension at different positions of the cell. The measured tether force is shown in relation to the distance from the cell body. Force map of oligodendrocytes cultured for 2 days and treated with latrunculin A, jasplakinolide or vehicle respectively. Tether force is shown as mean ± SEM (n=10-13 cells with a total of 67-245 pulled tethers per treatment). (C) AFM was used to generate force maps of oligodendrocytes cultured for two days (left panel) and five days (right panel). Tether force was anisotropic in sheath forming cells with higher values in the outer cellular rim (**p < 0.01, ***p < 0.001, one-way analysis of variance and Tukey’s multiple comparison test). Tether force is shown as mean ± SEM. (n=9-12 cells with a total of 291-800 pulled tethers for each stage).
See also Figure S3