The dynamic phagosomal proteome and the contribution of the endoplasmic reticulum.
Macrophages use phagocytosis to control the spread of pathogens in the body, to clear apoptotic cells, and to aid in tissue remodeling. The phagosomal membrane is traditionally thought to originate from the plasmalemma and then go through a series of maturation steps involving sequential fusion with endosomal compartments, leading to the formation of a phagolysosome. A recent model suggests that the endoplasmic reticulum (ER) is involved in the maturation as well. Here we use stable isotope labeling and multiple quantitative proteomic approaches to follow the dynamic composition of the maturing phagosome in RAW 264.7 macrophage cells to a greater depth and higher temporal resolution than was previously possible. Analysis of the results suggests that the traditional model of a linear sequence of fusion events with different compartments is more complex or variable than previously thought. By concomitantly measuring the degree to which each component is enriched on phagosomes, our data argue that the amount of ER involved in phagocytosis is much less than predicted by the model of ER-mediated phagocytosis.
Rogers
Lindsay D
LD
Centre for Proteomics, Department of Biochemistry and Molecular Biology, University of British Columbia, 301-2185 East Mall, Vancouver, BC, Canada.
Foster
Leonard J
LJ
D000818:Animals; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D051379:Mice; D008863:Microspheres; D010588:Phagosomes / Q000378:metabolism*; D021381:Protein Transport; D020543:Proteome / Q000378:metabolism*; D050600:SNARE Proteins / Q000378:metabolism; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism
D020543:Proteome; D050600:SNARE Proteins; D020691:rab GTP-Binding Proteins