FIGURE 6.

Inhibition of actomyosin contractility prevents the effects of exosome-like vesicles on cell surface area. A, primary oligodendrocytes were treated for 3 days with NCM and incubated with exosome-like vesicles during the last 2 days in the absence or presence of 10 μm Y27632 (Y27). The cells were immunolabled for A2B5 (red) and MBP (green). Scale bar, 100 μm. B, Y27632 did not change cell surface area of A2B5- and MBP-positive cells treated with only NCM, but the inhibitory effect of exosomes on cell surface expansion was reduced by Y27632. Black column, without Y27632; blue column, with Y27632 (n = 42 confocal images from three independent experiments). C, oligodendrocytes were cultured in NCM for 4 days with or without exosome-like vesicles. Using a pulldown assay, the amount of active RhoA (RhoA-GTP) compared with total RhoA was measured. Treatment with exosome like-vesicles leads to an increase in RhoA activity as compared with the control (n = 3). D, the phosphorylation of MLC2 (Ser-19) was evaluated after treatment of oligodendrocytes with exosome-like vesicles (n = 3). E, blebbistatin (50 μm) did not change cell surface area of A2B5- and MBP-positive cells treated with only NCM, but the inhibitory effect of exosomes on cell surface expansion was reduced by blebbistatin (n = 30 confocal images from two independent experiments). Black column, without blebbistatin; blue column, with blebbistatin (*, p < 0.05; ***, p < 0.001; t test). exo, exosomes.