MacMARCKS mutation blocks macrophage phagocytosis of zymosan.
A major protein kinase C substrate, MacMARCKS (F52, MPR), was examined for its role in phagocytosis. In macrophage-phagocytosing zymosan particles, MacMARCKS was concentrated around nascent phagosomes as detected by immunofluorescent microscopy. The effector domain of MacMARCKS contains the phosphorylation sites, a calmodulin binding site, as well as a putative actin binding site. Stable J774 macrophage cell lines constitutively expressing effector domain deletion mutants of MacMARCKS were generated. When given zymosan particles, these transfectants showed approximately a 90% reduction in their phagocytic capacity. The receptor-mediated endocytosis of acetylated low density lipoproteins, however, was not affected by the mutant. These results strongly suggest the involvement of MacMARCKS in macrophage phagocytosis.
Zhu
Z
Z
Department of Microbiology and Immunology, College of Medicine, University of Tennessee, Memphis 38163, USA.
Bao
Z
Z
Li
J
J
D015815:Cell Adhesion Molecules; D002460:Cell Line; D004705:Endocytosis; D008077:Lipoproteins, LDL / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D008565:Membrane Proteins; D009154:Mutation; D010587:Phagocytosis / Q000235:genetics*; D010588:Phagosomes / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011506:Proteins / Q000235:genetics*; D011973:Receptors, LDL / Q000378:metabolism; D051116:Receptors, Scavenger; D015054:Zymosan / Q000276:immunology*
D015815:Cell Adhesion Molecules; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D011506:Proteins; D011973:Receptors, LDL; D051116:Receptors, Scavenger; C032629:acetyl-LDL; D015054:Zymosan; D011493:Protein Kinase C