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Phospholipases D1 and D2 coordinately regulate macrophage phagocytosis
Shankar S Iyer1, James A Barton, Sylvain Bourgoin
1Inflammation Program, Division of Infectious Diseases, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City 52241, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|August 6, 2004
Summary
Both Phospholipase D1 (PLD1) and PLD2 regulate phagocytosis in human macrophages. PLD1 and PLD2 show distinct cellular localizations, with PLD1 specifically targeting phagosome membranes during this crucial immune process.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Phagocytosis is a critical innate immune process for defense and tissue repair.
- Phospholipase D (PLD) is implicated in phagocytosis, but specific isoforms and mechanisms remain unclear.
Purpose of the Study:
- To investigate the roles of PLD1 and PLD2 in human macrophage phagocytosis.
- To elucidate the localization and activation of PLD isoforms during phagocytosis.
Main Methods:
- Utilized primary human macrophages and THP-1 promonocytes.
- Employed a novel immunoprecipitation-in vitro PLD assay.
- Used dominant-negative transfections to assess PLD isoform function.
- Examined subcellular localization via microscopy.
Main Results:
- Both PLD1 and PLD2 are expressed in human myelomonocytic cells and are activated during phagocytosis.
- Inhibition of either PLD1 or PLD2 significantly reduced phagocytosis extent.
- PLD1 and PLD2 displayed distinct localizations, with PLD1 found on the phagosome membrane.
- Heterologous COS-7 cells, lacking PLD1, did not accurately model these PLD-dependent events.
Conclusions:
- Macrophage phagocytosis is coordinately regulated by both PLD1 and PLD2, with isoform-specific localization.
- Human myelomonocytic cell lines are suitable models for studying PLD-dependent phagocytosis, unlike COS cells.