Class IA Phosphatidylinositol 3-Kinase p110α Regulates Phagosome Maturation
Figure 3
Magnetic bead phagosomes from p110α knockdown cells show defective acquisition of the lysosomal proteins LAMP-1 and LAMP-2.
Kinetic analysis of phagosome maturation by flow organellometry shows A) normal acquisition of the early endosomal marker Rab5 and EEA-1, and B) marked defects in the acquisition of the lysosomal membrane proteins LAMP-1 and LAMP-2 by p110α knockdown cells. Solid circles = control cells, empty squares = p110α knockdown cells. Timepoints were taken at 30 minutes, 1 hour, 2 hours, 4 hours, and 6 hours post bead treatment. Data are means +/− s.e.m., from five independent experiments. Ratios of geometric mean over isotype control of 1 or less are interpreted as negligible signal. *p<0.05. C) Whole cell expression of phagosome markers are at similar levels in control and p110α knockdown cells. Staining of permeabilized cells and flow cytometric analysis of various phagosome markers in control and p110α knockdown cells showed no significant differences in cellular levels. Empty bars = control cells, solid bars = p110α knockdown cells. Data are means +/− s.e.m., from three independent experiments.