scholarly journals The localization of phospholipase A2 in the secretory granule

1994 ◽  
Vol 300 (3) ◽  
pp. 619-622 ◽  
Author(s):  
S P Chock ◽  
E A Schmauder-Chock ◽  
E Cordella-Miele ◽  
L Miele ◽  
A B Mukherjee
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Secretory Granule ◽  
Secretory Granules ◽  
Lipid Mediator ◽  
Arachidonic Acid Cascade ◽  
Surface Receptors ◽  
The Matrix ◽  
Immunocytochemical Techniques ◽  
Granule Matrix

A heat-resistant phospholipase A2 has been detected in the secretory granules of the mast cell [Chock, Rhee, Tang and Schmauder-Chock (1991) Eur. J. Biochem. 195, 707-713]. By using ultrastructural immunocytochemical techniques, we have now localized this enzyme to the matrix of the secretory granule. Like the cyclo-oxygenase [Schmauder-Chock and Chock (1989) J. Histochem. Cytochem. 37, 1319-1328], this enzyme also adheres tightly to the ribbon-like granule matrix components. The results from Western-blot analysis suggest that it has a molecular mass of about 14 kDa. The localization of the phospholipase A2, the presence of a phospholipid store with millimolar concentrations of calcium and the localization of the enzymes of the arachidonic acid cascade make the secretory granule a natural site for lipid-mediator synthesis. The packaging of phospholipase A2, together with its substrate and the components of the arachidonic acid cascade, in the secretory granule represents a physical arrangement by which the initiation of the cascade and the release of mediators can be directly linked to the stimulation of cell-surface receptors.

scholarly journals Localization of cyclo-oxygenase and prostaglandin E2 in the secretory granule of the mast cell.

1989 ◽  
Vol 37 (9) ◽  
pp. 1319-1328 ◽  
Author(s):  
E A Schmauder-Chock ◽  
S P Chock
Keyword(s):  
Prostaglandin E2 ◽  
Secretory Granule ◽  
Plasma Membranes ◽  
Secretory Granules ◽  
Arachidonic Acid Cascade ◽  
Cell Surfaces ◽  
Previous Conclusion ◽  
Cyclooxygenase Activity ◽  
Granule Matrix ◽  
Exposed Cell

The application of anti-cyclo-oxygenase and anti-prostaglandin E2 immunoglobulins to A23187-stimulated rat connective tissue mast cells has permitted the localization of cyclooxygenase activity (prostaglandin H2 synthetase) and the site of prostaglandin E2 (PGE2) formation in the secretory granules. Because binding was carried out after stimulation but before dehydration and embedding, we have limited the loss of these antigens due to normal degradation and to aqueous and solvent washes. As this method permits labeling of exposed cell surfaces, only granules that have been exteriorized can be labeled. Contrary to what might have been expected, no labeling was associated with plasma membranes or with any portion of damaged cells. Antibodies to PGE2 were bound evenly over the surface of the granule matrix, whereas antibodies to cyclo-oxygenase appeared to be bound to strands of proteo-heparin projecting from the surface of the granule matrix. Where granule matrix had become unraveled and dispersed, label appeared to adhere throughout the ribbon-like proteo-heparin strands. These results support our previous conclusion that the secretory granule is the site of the arachidonic acid cascade during exocytosis.

scholarly journals Ca2+-independent fusion of secretory granules with phospholipase A2-treated plasma membranes in vitro

1995 ◽  
Vol 307 (2) ◽  
pp. 563-569 ◽  
Author(s):  
T Nagao ◽  
T Kubo ◽  
R Fujimoto ◽  
H Nishio ◽  
T Takeuchi ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Phospholipase A2 ◽  
Plasma Membranes ◽  
Secretory Granules ◽  
Fusion Process ◽  
Amylase Release ◽  
Fusogenic Activity ◽  
Rat Parotid

The fusion of secretory granules with plasma membranes prepared from rat parotid gland was studied in vitro to clarify the mechanism of exocytosis. Fusion of the granules with plasma membranes was measured by a fluorescence-dequenching assay with octadecyl rhodamine B, and release of amylase was also measured to confirm the fusion as a final step of the secretory process. Plasma membranes that had been pretreated with porcine phospholipase A2 (PLA2) in the presence of 20 microM Ca2+ fused with the granules within 30 s, and induced amylase release by reacting with the membranes of granules, whereas without this pretreatment they had no significant effect. The fusion process accompanied by amylase release was induced in the presence of 10 mM EGTA, and therefore was apparently Ca(2+)-independent. On the other hand, the presence of EGTA or 100 microM quinacrine, an inhibitor of PLA2, during treatment of plasma membranes with PLA2 inhibited their fusogenic activity, suggesting the importance of activation of PLA2. Arachidonic acid and linoleic acid were released from the plasma membranes during the PLA2 treatment. The presence of albumin, an adsorbent of fatty acids, during the treatment also inhibited the activity. Pretreatment of the membranes with arachidonic acid or linoleic acid did not have any effect, but the presence of exogenously added arachidonic acid during PLA2 treatment enhanced the membrane-fusion-inducing effect of PLA2. Pretreatment of the membranes with lysophosphatidylcholine induced fusogenic activity. These findings suggest that the conformational change in the plasma-membrane phospholipids induced by PLA2 and the presence of arachidonic acid or linoleic acid produced by PLA2 are important in the process of fusion of secretory granules with the plasma membranes of rat parotid acinar cells and that the fusion process itself is independent of Ca2+.

Brain phospholipase A2-arachidonic acid cascade is involved in the activation of central sympatho-adrenomedullary outflow in rats

2000 ◽  
Vol 398 (3) ◽  
pp. 341-347 ◽  
Author(s):  
Kunihiko Yokotani ◽  
Muchung Wang ◽  
Yoshinori Murakami ◽  
Shoshiro Okada ◽  
Masakazu Hirata
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Arachidonic Acid Cascade

scholarly journals Vitamin E Improves Microsomal Phospholipase A2 Activity and the Arachidonic Acid Cascade in Kidney of Diabetic Rats

2001 ◽  
Vol 131 (4) ◽  
pp. 1297-1301 ◽  
Author(s):  
Oh-Gye Kwag ◽  
Sung-Ok Kim ◽  
Jeong-Hwa Choi ◽  
In-Koo Rhee ◽  
Myung-Sook Choi ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Vitamin E ◽  
Phospholipase A2 ◽  
Diabetic Rats ◽  
Arachidonic Acid Cascade ◽  
Phospholipase A2 Activity

scholarly journals Lipid Droplets, Phospholipase A2, Arachidonic Acid, and Atherosclerosis

Biomedicines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1891
Author(s):  
Miguel A. Bermúdez ◽  
María A. Balboa ◽  
Jesús Balsinde
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Lipid Synthesis ◽  
Lipid Mediator ◽  
Droplet Dynamics ◽  
Potent Inducer ◽  
Inflammatory State ◽  
Dynamic Structures

Lipid droplets, classically regarded as static storage organelles, are currently considered as dynamic structures involved in key processes of lipid metabolism, cellular homeostasis and signaling. Studies on the inflammatory state of atherosclerotic plaques suggest that circulating monocytes interact with products released by endothelial cells and may acquire a foamy phenotype before crossing the endothelial barrier and differentiating into macrophages. One such compound released in significant amounts into the bloodstream is arachidonic acid, the common precursor of eicosanoids, and a potent inducer of neutral lipid synthesis and lipid droplet formation in circulating monocytes. Members of the family of phospholipase A2, which hydrolyze the fatty acid present at the sn-2 position of phospholipids, have recently emerged as key controllers of lipid droplet homeostasis, regulating their formation and the availability of fatty acids for lipid mediator production. In this paper we discuss recent findings related to lipid droplet dynamics in immune cells and the ways these organelles are involved in regulating arachidonic acid availability and metabolism in the context of atherosclerosis.

scholarly journals Phospholipid Arachidonic Acid Remodeling During Phagocytosis in Mouse Peritoneal Macrophages

Biomedicines ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 274
Author(s):  
Luis Gil-de-Gómez ◽  
Patricia Monge ◽  
Juan P. Rodríguez ◽  
Alma M. Astudillo ◽  
María A. Balboa ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Peritoneal Macrophages ◽  
Lipid Mediator ◽  
Membrane Phospholipids ◽  
Lipid Profiling ◽  
Surface Receptors ◽  
Cytosolic Phospholipase ◽  
Mouse Peritoneal Macrophages ◽  
Phospholipid Species ◽  
Potential Use

Macrophages contain large amounts of arachidonic acid (AA), which distributes differentially across membrane phospholipids. This is largely due to the action of coenzyme A-independent transacylase (CoA-IT), which transfers the AA primarily from diacyl choline-containing phospholipids to ethanolamine-containing phospholipids. In this work we have comparatively analyzed glycerophospholipid changes leading to AA mobilization in mouse peritoneal macrophages responding to either zymosan or serum-opsonized zymosan (OpZ). These two phagocytic stimuli promote the cytosolic phospholipase A2-dependent mobilization of AA by activating distinct surface receptors. Application of mass spectrometry-based lipid profiling to identify changes in AA-containing phospholipids during macrophage exposure to both stimuli revealed significant decreases in the levels of all major choline phospholipid molecular species and a major phosphatidylinositol species. Importantly, while no changes in ethanolamine phospholipid species were detected on stimulation with zymosan, significant decreases in these species were observed when OpZ was used. Analyses of CoA-IT-mediated AA remodeling revealed that the process occurred faster in the zymosan-stimulated cells compared with OpZ-stimulated cells. Pharmacological inhibition of CoA-IT strongly blunted AA release in response to zymosan but had only a moderate effect on the OpZ-mediated response. These results suggest a hitherto undescribed receptor-dependent role for CoA-independent AA remodeling reactions in modulating the eicosanoid biosynthetic response of macrophages. Our data help define novel targets within the AA remodeling pathway with potential use to control lipid mediator formation

Extracellular matrix: the gatekeeper of tumor angiogenesis

2019 ◽  
Vol 47 (5) ◽  
pp. 1543-1555 ◽  
Author(s):  
Maurizio Mongiat ◽  
Simone Buraschi ◽  
Eva Andreuzzi ◽  
Thomas Neill ◽  
Renato V. Iozzo
Keyword(s):  
Extracellular Matrix ◽  
Tumor Angiogenesis ◽  
Signaling Cascades ◽  
Cancer Growth ◽  
Cell Behavior ◽  
Metastatic Progression ◽  
Surface Receptors ◽  
The Matrix ◽  
Multiple Signaling

Abstract The extracellular matrix is a network of secreted macromolecules that provides a harmonious meshwork for the growth and homeostatic development of organisms. It conveys multiple signaling cascades affecting specific surface receptors that impact cell behavior. During cancer growth, this bioactive meshwork is remodeled and enriched in newly formed blood vessels, which provide nutrients and oxygen to the growing tumor cells. Remodeling of the tumor microenvironment leads to the formation of bioactive fragments that may have a distinct function from their parent molecules, and the balance among these factors directly influence cell viability and metastatic progression. Indeed, the matrix acts as a gatekeeper by regulating the access of cancer cells to nutrients. Here, we will critically evaluate the role of selected matrix constituents in regulating tumor angiogenesis and provide up-to-date information concerning their primary mechanisms of action.

Stimulation of Ca(2+)-dependent exocytosis of the sperm acrosome by cAMP acting downstream of phospholipase A2

Reproduction ◽  
2000 ◽  
pp. 57-68 ◽  
Author(s):  
J Garde ◽  
ER Roldan
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Phospholipase C ◽  
Phosphodiesterase Inhibitors ◽  
Dibutyryl Camp ◽  
Camp Phosphodiesterase ◽  
Ram Sperm ◽  
Camp Formation ◽  
Stimulation Of

Spermatozoa undergo exocytosis in response to agonists that induce Ca2+ influx and, in turn, activation of phosphoinositidase C, phospholipase C, phospholipase A2, and cAMP formation. Since the role of cAMP downstream of Ca2+ influx is unknown, this study investigated whether cAMP modulates phospholipase C or phospholipase A2 using a ram sperm model stimulated with A23187 and Ca2+. Exposure to dibutyryl-cAMP, phosphodiesterase inhibitors or forskolin resulted in enhancement of exocytosis. However, the effect was not due to stimulation of phospholipase C or phospholipase A2: in spermatozoa prelabelled with [3H]palmitic acid or [14C]arachidonic acid, these reagents did not enhance [3H]diacylglycerol formation or [14C]arachidonic acid release. Spermatozoa were treated with the phospholipase A2 inhibitor aristolochic acid, and dibutyryl-cAMP to test whether cAMP acts downstream of phospholipase A2. Under these conditions, exocytosis did not occur in response to A23187 and Ca2+. However, inclusion of dibutyryl-cAMP and the phospholipase A2 metabolite lysophosphatidylcholine did result in exocytosis (at an extent similar to that seen when cells were treated with A23187/Ca2+ and without the inhibitor). Inclusion of lysophosphatidylcholine alone, without dibutyryl-cAMP, enhanced exocytosis to a lesser extent, demonstrating that cAMP requires a phospholipase A2 metabolite to stimulate the final stages of exocytosis. These results indicate that cAMP may act downstream of phospholipase A2, exerting a regulatory role in the exocytosis triggered by physiological agonists.

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