FIGURE 3.

Microtubule disruption leads to the formation of small SGs after arsenite exposure. A, MT disruption leads to the formation of small SGs at high and low level of stress. HeLa cells were treated with 0.1% DMSO (Control) or with 3 μm vinblastine (VLB). These treatments were applied 2 h prior to and during 45-min exposure to arsenite at varying concentrations. At all concentrations of arsenite, large SGs are formed in control cells, even though they appear less contrasted at the lowest arsenite concentration (100 μm). In the presence of vinblastine, SGs are smaller and homogenously distributed in the cytoplasm whatever the arsenite concentration. Cells were stained with anti-YB-1 antibody. B, cells resume the formation of large SGs after MT repolymerization. i, HeLa cells after exposure to 0.5 mm arsenite for 90 min; ii, vinblastine-treated HeLa cells exposed to 0.5 mm arsenite for 90 min; iii, same as ii except that vinblastine was removed during the last 45 min of exposure to arsenite; iv, HeLa cells were first exposed to arsenite for 45 min to form large granules and then treated with vinblastine for the last 45 min of arsenite exposure. We note that, upon removal of vinblastine to allow MT regrowth, cells are again able to form large SGs (iii). However, the dissociation of large SGs into small SGs upon MT disruption is not possible, meaning that, after their formation, large SGs are rather stable when MTs are disrupted (iv).