期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 107, 期 45, 页码 19332-19337出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1008248107
关键词
fluorescence; macrophage; microscopy; phosphatidylinositol 3-kinase; phosphoinositides
资金
- National Institutes of Health [AI35950, AI64668]
During Fc gamma receptor (FcR)-mediated phagocytosis by macrophages, cytoplasm advances over IgG-coated particles by the sequential ligation of FcR in plasma membranes. If FcR signaling was strictly autonomous, then the signals generated during phagocytosis should be proportional to the number of ligated receptors. By measuring FcR-dependent responses to beads coated with various densities of IgG, this study identified nonlinear signaling that organizes an all or none response during particle ingestion. Phagocytosis of beads with IgG at low density either stalled after making small, actin-rich cups or proceeded to completion at the same rate as phagocytosis of high-density IgG beads. Signals were measured by quantifying the recruitment of YFP-labeled probes to phagocytic cup membranes. Although the magnitude of early signals correlated with IgG density, later signals showed an all or none response, which was regulated by the concentrations of 3' phosphoinositides in phagocytic cup membranes. Thus, 3' phosphoinositides, shown previously to be required for phagocytosis, function in a feedback regulatory mechanism affecting late but not early signals. This indicates a mechanism for the coordination of cell movements initiated by receptor signaling.
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