Figure 3

Normal fibrinogen content, but decreased fibrinogen binding upon activation and delayed fibrinogen uptake of mutant platelets. (a) Immunoblot analysis of fibrinogen content (α, β and γ-chain) of platelet lysates from two control (Str^+/+) and two Strumpellin-deficient (Str^−/−) mice. Filamin A served as loading control. (b) Binding of labeled fibrinogen (Fibrinogen-Alexa488) to platelets under resting conditions and upon activation with adenosine diphosphate (ADP) + U46619 (U46, thromboxane analogue), convulxin (CVX) and rhodocytin (Rhod). Values are mean ± s.d. (n = 5; ***P < 0.001). (c) Time dependent (0 min, 5 min, 15 min, 30 min) uptake of labeled fibrinogen by platelets. Values are mean ± s.d. (n = 3; **P < 0.01). (d) Representative confocal images of resting control and Strumpellin-deficient platelets, which were fixed after 30 min incubation with fluorescently-labeled fibrinogen (magenta). vWF staining (cyan) was used to visualize α-granules. Scale bar represents 1 µm.