Figure 4
Syk-KO inhibits the disappearance of F-actin around phagosomes. (a) Representative images of F-actin (Alexa Fluor 594-labeled phalloidin) during phagocytosis of macrophage-like differentiated parental and Syk-KO HL60 cells after incubation with complement-opsonized FITC-zymosan particles for 15 min, followed by incubation for indicated time intervals, as quantified in (b). Arrows show the phagosomes that are not surrounded by F-actin and arrowheads show the phagosomes surrounded by F-actin. Scale bars show 10 μm. (b) Quantification of the percentage of the phagosomes surrounded by F-actin in macrophage-like differentiated parental and Syk-KO HL60 cells during phagocytic process. More than 100 phagosomes per single clone were analyzed. Data show the means ± SD derived from three independent experiments. p values were calculated using a two-tailed unpaired Student’s t-test. ** < 0.01; * < 0.05. (c) Representative electron micrographs of macrophage-like differentiated parental and Syk-KO HL60 cells after incubation with complement-opsonized FITC-zymosan particles for 15 min, followed by incubation for additional 2 h. Phagosomes (Ph) enclosed in dash squares are enlarged in the middle and right panels. Dashed circles indicate surface of phagosome surrounded by F-actin (red), and surface of zymosan particles (yellow), respectively. Scale bars show 2 μm.
