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Cited by 410Phagocytosis and Immune RegulationCellular transport and secretionPI3K/AKT/mTOR signaling in cancer

A requirement for phosphatidylinositol 3-kinase in pseudopod extension

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Cox, Dianne, Tseng, Ching-Chun, Bjekic, Gordana, Greenberg, Steven·1999·Journal of Biological Chemistry
DOI 10.1074/jbc.274.3.1240
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Abstract

Phagocytosis requires actin assembly and pseudopod extension, two cellular events that coincide spatially and temporally. The signal transduction events underlying both processes may be distinct. We tested whether phagocytic signaling resembles that of growth factor receptors, which induce actin polymerization via activation of phosphatidylinositol 3-kinase (PI 3-kinase). Fcgamma receptor-mediated phagocytosis was accompanied by a rapid increase in the accumulation of phosphatidylinositol 3,4,5-trisphosphate in vivo, and addition of wortmannin (WM) or LY294002, two inhibitors of PI 3-kinase(s), inhibited phagocytosis but not Fcgamma receptor-directed actin polymerization. However, both compounds prevented maximal pseudopod extension, suggesting that PI 3-kinase inhibition produced a limitation in membrane required for pseudopod extension. Availability of plasma membrane was not limiting for phagocytosis, because blockade of ingestion in the presence of WM was not overcome by reducing the number of particles adhering to macrophages. However, decreasing bead size, and hence the magnitude of pseudopod extension required for particle engulfment, relieved the inhibition of phagocytosis in the presence of WM or LY294002 by up to 80%. The block in phagocytosis of large particles occurred before phagosomal closure, because both compounds inhibited spreading of macrophages on substrate-bound IgG. Macrophage spreading on IgG was accompanied by exocytic insertion of membrane from an intracellular source, as measured by the dye FM1-43. These results indicate that one or more isoforms of PI 3 kinase are required for maximal pseudopod extension but not phagocytosis per se. We suggest that PI 3-kinase is required for coordinating exocytic membrane insertion and pseudopod extension.

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Crossref · 10.1074/jbc.274.3.1240

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  • PI3K appears essential for phagocytosis because inhibitors such as wortmannin impair particle engulfment.

    “This kinase appears to be essential for phagocytosis since inhibitors such as wortmannin impair particle engulfment (Ninomiya et al. 1994; Araki et al. 1996; Cox et al. 1999).”

    From Localized Biphasic Changes in Phosphatidylinositol-4,5-Bisphosphate at Sites of Phagocytosis (2000) · cites this paper as Cox et al. 1999

    The Results section, “Wortmannin and LY294002 Inhibit Fcγ-mediated Phagocytosis,” reports concentration-dependent inhibition of particle engulfment by both PI3K inhibitors. But the paper finds weaker inhibition for smaller beads and cautions against generalizing to other phagocytic targets. It therefore supports the inhibitor finding, but not an unqualified requirement for PI3K in phagocytosis generally. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Wortmannin-treated cells fail to internalize particles but nevertheless display marked actin reassembly under adherent RBCs.

    “While wortmannin-treated cells fail to internalize particles, they nevertheless display marked actin reassembly under the adherent RBCs (Araki et al. 1996; Cox et al. 1999; and our own observations, not shown).”

    From Localized Biphasic Changes in Phosphatidylinositol-4,5-Bisphosphate at Sites of Phagocytosis (2000) · cites this paper as Cox et al. 1999

    In “Actin Assembly in Response to Fc” (page unavailable), the paper reports that wortmannin did not visibly reduce F-actin accumulation beneath attached particles, including IgG-coated erythrocytes. It also reports inhibited phagocytosis, but not a complete failure to internalize particles: inhibition depended on particle size and was less effective for smaller beads. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • Consumption of 4,5-PIP2 by PI3K must contribute to the dissociation of PLCδ-PH-GFP from phagosomes.

    “Hence, consumption of 4,5-PIP2 by PI3K must contribute to the dissociation of PLCδ-PH-GFP.”

    From Localized Biphasic Changes in Phosphatidylinositol-4,5-Bisphosphate at Sites of Phagocytosis (2000) · cites this paper as Cox et al. 1999

    The Results (page unavailable) report rapid PIP3 accumulation during Fcγ receptor-mediated phagocytosis, consistent with increased PI3K activity. The Experimental Procedures describe generating PIP3 from 4,5-PIP2 for a laboratory standard. Neither passage establishes that PI3K consumes phagosomal 4,5-PIP2 or causes PLCδ-PH-GFP to dissociate. (LLM, conf=0.83)

    Experimental — accuracy not yet measured

  • The increase in 3,4,5-PIP3 predicted to occur during phagocytosis did not affect the distribution of PLCδ-PH-GFP.

    “The increase in 3,4,5-PIP3 predicted to occur during phagocytosis, based on the reported activation of PI3K (Araki et al. 1996; Cox et al. 1999), did not affect the distribution of PLCδ-PH-GFP.”

    From Localized Biphasic Changes in Phosphatidylinositol-4,5-Bisphosphate at Sites of Phagocytosis (2000) · cites this paper as Cox et al. 1999

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Cites

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Research works printed but not linked: 7

  1. Nakanishi, S., Catt, K. J., and Balla, T. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 5317-5321
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  3. Young, A. T., Dahl, J., Hausdorf, S. F., Bauer, P. H., Birnbaum, M. J., and Benjamin, T. L. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 11613-11617
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Authors
Cox, D., Tseng, C.-C., Bjekic, G., & Greenberg, S.
Affiliations
Columbia University (US)
Corresponding author
Greenberg, Steven
ORCID
Cox, Dianne
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
1999-01
Volume
274
Issue
3
Pages
1240-1247
ISSN
0021-9258 (ISSN-L)
DOI
10.1074/jbc.274.3.1240
OpenAlex
W2159584083
Cited by
410
References
2
Citations by year
2026: 2 · 2025: 7 · 2024: 6 · 2023: 6 · 2022: 4 · 2021: 11 · 2020: 14 · 2019: 11 · 2018: 11 · 2017: 12 · 2016: 24 · 2015: 6 · 2014: 20 · 2013: 20 · 2012: 16
FWCI
7.69
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • American Heart Association
  • National Institutes of Health
Topics
  • Life Sciences › Immunology and Microbiology › Immunology › Phagocytosis and Immune Regulation
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Cellular transport and secretion
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › PI3K/AKT/mTOR signaling in cancer
Keywords
phosphatidylinositol 3-kinase, pseudopod extension, phagocytosis, Fc gamma receptor, actin polymerization, phosphatidylinositol 3,4,5-trisphosphate, wortmannin, LY294002, macrophages, macrophage spreading, bead size
MeSH terms
Wortmannin, Androstadienes, Animals, Cell Line, Cell Membrane, Chromones, Dose-Response Relationship, Drug, Enzyme Inhibitors, Erythrocytes, Exocytosis, Immunosuppressive Agents, Mice, Inbred C57BL, Morpholines, Phagocytosis, Rabbits, Sheep, Inositol 1,4,5-Trisphosphate, Receptors, IgG, Macrophages, Peritoneal, Phosphatidylinositol 3-Kinases, Sirolimus, Mice

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