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Proinflammatory macrophage-activating properties of the novel phospholipid diacylglycerol pyrophosphate
M A Balboa1, J Balsinde, D A Dillon
1Department of Chemistry and Biochemistry, School of Medicine and Revelle College, University of California at San Diego, La Jolla, California 92093-0601, USA.
Abstract:
We have found that the novel phospholipid diacylglycerol pyrophosphate (DGPP), identified in bacteria, yeast, and plants, but not in mammalian cells, is able to potently activate macrophages for enhanced secretion of arachidonate metabolites, a key event in the immunoinflammatory response of leukocytes. Macrophage responses to DGPP are specific and are not mediated by its conversion into other putative lipid mediators such as phosphatidic acid, lysophosphatidic acid, or diacylglycerol. The responses to DGPP are compatible with a receptor-recognition event because they are blocked by suramin. Intracellular signaling initiated by DGPP includes phosphorylation and activation of the Group IV cytosolic phospholipase A2 and of the extracellular-signal regulated p42 mitogen-activated protein kinase (MAPK) and p44 MAPK, and membrane translocation of the protein kinase C isoenzymes alpha, epsilon, delta. These results establish DGPP as a novel macrophage-activating factor and suggest a potential role for this compound in triggering homeostatic cellular responses.
Insights
Diacylglycerol pyrophosphate (DGPP), a novel lipid, potently activates immune cells called macrophages. This discovery reveals DGPP as a key factor in initiating inflammatory and homeostatic responses.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophages play a crucial role in immune responses.
- Arachidonate metabolites are key mediators in leukocyte inflammatory responses.
- The function of diacylglycerol pyrophosphate (DGPP) in mammalian cells is largely unknown.
Purpose of the Study:
- To investigate the role of the novel phospholipid diacylglycerol pyrophosphate (DGPP) in immune cell activation.
- To elucidate the signaling pathways involved in DGPP-mediated macrophage activation.
Main Methods:
- Macrophage activation assays.
- Analysis of lipid mediator secretion.
- Inhibition studies using suramin.
- Western blotting to assess protein phosphorylation and translocation.
- Mitogen-activated protein kinase (MAPK) pathway analysis.
Main Results:
- DGPP potently activates macrophages, enhancing arachidonate metabolite secretion.
- DGPP-induced responses are specific and not due to conversion to other lipid mediators.
- Responses are blocked by suramin, suggesting receptor involvement.
- DGPP triggers intracellular signaling, including activation of phospholipase A2 and MAPK, and PKC translocation.
Conclusions:
- DGPP is identified as a novel macrophage-activating factor.
- DGPP initiates specific intracellular signaling cascades.
- DGPP may play a role in triggering homeostatic cellular responses.