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. 2013 Oct 16;288(48):34352–34363. doi: 10.1074/jbc.M113.459750

FIGURE 3.

FIGURE 3.

TGF-β1 secretion by mouse and human platelets is regulated independently by WASp and the actin cytoskeleton. A, PAR4-AP-induced actin assembly by wild-type (white bars) or WASp−/− (black bars) mouse platelets as determined by FITC-phalloidin binding. The data are expressed as means ± S.E. and represent three independent experiments. NS, difference not statistically significant (p > 0.05). B, TRAP-induced actin assembly by human platelets treated with vehicle (white bars) or wiskostatin (black bars) as determined by FITC-phalloidin binding. The data are expressed as means ± S.E. and represent three independent experiments using platelets from different blood donors. NS, difference not statistically significant (p > 0.05). C, TRAP-mediated release of TGF-β1 by human platelets treated with either vehicle (white bar) or 10 μm cytochalasin D (black bar). The data are expressed as means ± S.E. and represent three independent experiments using platelets from different blood donors. *, p < 0.05. D, PAR4-AP-mediated release of TGF-β1 by wild-type (white bars) or WASp−/− (black bars) mouse platelets pretreated with either vehicle or 10 μm cytochalasin D. The data are expressed as means ± S.E. and represent three independent experiments. *, significantly (p < 0.05) different from vehicle-treated wild-type platelets; **, significantly (p < 0.05) different from vehicle-treated WASp−/− platelets or cytochalasin-treated wild-type platelets. E, comparison of the spatial distribution of TGF-β1 (left-hand panels, green) and F-actin (center panels, red) in human platelets stimulated by TRAP (10 μm) and spread on fibrinogen for 15 min. Bar, 10 μm; n = 3. F, comparison of the distribution of WASp (left-hand panels, green) and F-actin (center panels, red) in human platelets stimulated by TRAP (10 μm) and spread on fibrinogen for 15 min. Bar, 10 μm; n = 3. G, effect of cytochalasin D or wiskostatin on PAR4-AP-mediated release of TGF-β1 by wild-type (white bars) or gelsolin-null (black bars) mouse platelets. The data are expressed as means ± S.E. and represent three independent experiments. *, significantly (p < 0.05) different from vehicle-treated wild-type platelets; **, significantly (p < 0.05) different from wild-type platelets (treated with either cytochalasin D or wiskostatin) or Gsn−/− platelets (treated either with vehicle or cytochalasin D). Cyto D, cytochalasin D.