scholarly journals Leukotriene B4 stimulates the release of arachidonate in human neutrophils via the action of cytosolic phospholipase A2

1997 ◽  
Vol 1359 (1) ◽  
pp. 80-88 ◽  
Author(s):  
James R Burke ◽  
Lynda B Davern ◽  
Kurt R Gregor ◽  
Kenneth M Tramposch
Keyword(s):  
Phospholipase A2 ◽  
Leukotriene B4 ◽  
Cytosolic Phospholipase A2 ◽  
Human Neutrophils ◽  
Cytosolic Phospholipase

scholarly journals Cytosolic phospholipase A2 and its mode of activation in human neutrophils by opsonized zymosan: Correlation between 42/44 kDa mitogen-activated protein kinase, cytosolic phospholipase A2 and NADPH oxidase

1997 ◽  
Vol 326 (3) ◽  
pp. 867-876 ◽  
Author(s):  
Inbal HAZAN ◽  
Raya DANA ◽  
Yoseph GRANOT ◽  
Rachel LEVY
Keyword(s):  
Protein Kinase ◽  
Nadph Oxidase ◽  
Phospholipase A2 ◽  
Kinase Activity ◽  
Kinase Inhibitor ◽  
Cytosolic Phospholipase A2 ◽  
Human Neutrophils ◽  
Pla2 Activity ◽  
Cytosolic Phospholipase ◽  
Gf 109203X

The role of cytosolic phospholipase A2 (cPLA2) and its mode of activation by opsonized zymosan (OZ) was studied in human neutrophils in comparison with activation by PMA. The activation of cPLA2 by 1 mg/ml OZ or 50 ng/ml PMA is evidenced by its translocation to the membrane fractions on stimulation. This translocation is consistent with dithiothreitol (DTT)-resistant phospholipase A2 (PLA2) activity detected in the membranes of activated cells. Neutrophils stimulated by either OZ or PMA exhibited an immediate stimulation of extracellular-signal-regulated kinases (ERKs). The inhibition of ERKs, DTT-resistant PLA2 and NADPH oxidase activities by the MAP kinase kinase inhibitor PD-98059 indicates that ERKs mediate the activation of cPLA2 and NADPH oxidase stimulated by either OZ or PMA. The protein kinase C (PKC) inhibitor GF-109203X inhibited epidermal growth factor receptor peptide kinase activity, the release of [3H]arachidonic acid, DTT-resistant PLA2 activity and superoxide generation induced by PMA, but did not inhibit any of these activities induced by OZ. PKC activity was similarly inhibited by GF-109203X in membrane fractions separated from neutrophils stimulated by either PMA or OZ. In the presence of the tyrosine kinase inhibitor genistein, ERKs, PLA2 and NADPH oxidase activities were inhibited in cells stimulated by OZ, whereas they were hardly affected in cells stimulated by PMA. The results suggest that the activation of cPLA2 by PMA or OZ is mediated by ERKs. Whereas PMA stimulates ERKs activity through a PKC-dependent pathway, signal transduction stimulated by OZ involves tyrosine kinase activity leading to activation of ERKs via a PKC-independent pathway.

scholarly journals Granulocyte-macrophage colony-stimulating factor (GM-CSF) promotes phosphorylation and an increase in the activity of cytosolic phospholipase A2 in human neutrophils

1996 ◽  
Vol 313 (2) ◽  
pp. 503-508 ◽  
Author(s):  
Nabeel NAHAS ◽  
Waltraut H. WATERMAN ◽  
Ramadan I. SHA'AFI
Keyword(s):  
Phospholipase A2 ◽  
Cytosolic Phospholipase A2 ◽  
Time Dependent ◽  
Human Neutrophils ◽  
Colony Stimulating Factor ◽  
Gm Csf ◽  
Cytosolic Phospholipase ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor

Incubation of human neutrophils with 500 pM granulocyte-macrophage colony-stimulating factor (GM-CSF) results in a rapid and time-dependent increase in the phosphorylation of cytosolic phospholipase A2 (cPLA2), which was reflected in a slower electrophoretic mobility of the enzyme. The GM-CSF-induced phosphorylation of cPLA2 was accompanied by a parallel and time-dependent increase in the enzyme activity. Preincubation of neutrophils with the tyrosine kinase inhibitor genistein caused inhibition of the GM-CSF-stimulated phosphorylation and activity of cPLA2. Immunoprecipitation of the enzyme following incubation of neutrophils with [32P]Pi shows that cPLA2 is phosphorylated by GM-CSF. Potato acid phosphatase caused dephosphorylation of the enzyme, indicating that cPLA2 is indeed phosphorylated by GM-CSF. The subcellular distribution of cPLA2 in GM-CSF-stimulated neutrophils revealed that the enzyme resides almost completely in the cytosolic fraction. Addition of Ca2+ to the lysis buffer before homogenization results in the translocation of the phosphorylated and the dephosphorylated forms of the enzyme to the membranes. Translocation of cPLA2 was also achieved after incubation with 0.1 μM N-formylmethionyl-leucyl-phenylalanine (fMLP) after GM-CSF stimulation and when neutrophils were challenged with the Ca2+ ionophore A23187. EDTA and EGTA were unable to solubilize the translocated enzyme from the neutrophil membranes, indicating that cPLA2 is attached to the membranes by strong bonds and not merely due to ionic forces exerted by Ca2+. The inability of GM-CSF to promote arachidonic acid mobilization is probably due to the fact that GM-CSF does not cause an increase in intracellular Ca2+, which is necessary for the translocation of the enzyme to the membranes where its substrate(s) reside.

scholarly journals Calcium-dependent cytosolic phospholipase A2 activation is implicated in neuroinflammation and oxidative stress associated with ApoE4

2021 ◽  
Author(s):  
Shaowei Wang ◽  
Boyang Li ◽  
Victoria Solomon ◽  
Alfred Fonteh ◽  
Stanley I. Rapoport ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Phospholipase A2 ◽  
Late Onset ◽  
Leukotriene B4 ◽  
Cytosolic Phospholipase A2 ◽  
Calcium Dependent ◽  
Cytosolic Phospholipase ◽  
Primary Astrocytes ◽  
Oxide Synthase ◽  
And Oxidative Stress

Abstract Background: Apolipoprotein E4 (APOE4) is associated with a greater response to neuroinflammation and the risk of developing late-onset Alzheimer's disease (AD), but the mechanisms for this association are not clear. The activation of calcium-dependent cytosolic phospholipase A2 (cPLA2) is involved in inflammatory signaling and is elevated within the plaques of AD brains. The relation between APOE4 genotype and cPLA2 activity is not known.Methods: Mouse primary astrocytes, mouse and human brain samples differing by APOE genotypes were collected for measuring cPLA2 expression, phosphorylation, and activity in relation to measures of inflammation and oxidative stress. Results: Greater cPLA2 phosphorylation and activity was identified in ApoE4 compared to ApoE3 in primary astrocytes and brains of ApoE-targeted replacement (ApoE-TR) mice. These differences were also demonstrated in brain homogenates from the inferior frontal cortex from AD patients carrying APOE3/4 compared to APOE3/3. Higher cPLA2 activation with APOE4 was associated with greater activation of the MAPK p38 pathway in human postmortem frontal cortical synaptosomes and astrocytes, as well as with higher levels of leukotriene B4 (LTB4), reactive oxygen species (ROS), and inducible nitric oxide synthase (iNOS) in astrocytes. Inhibition of cPLA2 reduced LTB4, ROS, and iNOS levels in ApoE4 primary astrocytes to those in ApoE3 astrocytes. Conclusions: Our findings implicate greater activation of cPLA2 signaling system with APOE4, which could represent a potential drug target for mitigating the increased neuroinflammation with APOE4 and AD.

scholarly journals Effect of lipopolysaccharide on mitogen-activated protein kinases and cytosolic phospholipase A2

1995 ◽  
Vol 308 (3) ◽  
pp. 815-822 ◽  
Author(s):  
S I Fouda ◽  
T F P Molski ◽  
M S E Ashour ◽  
R I Sha′afi
Keyword(s):  
Phospholipase A2 ◽  
Map Kinase ◽  
Map Kinases ◽  
Kinase Inhibitor ◽  
Cytosolic Phospholipase A2 ◽  
Mitogen Activated Protein Kinase ◽  
Human Neutrophils ◽  
Cytosolic Phospholipase ◽  
Low Concentrations ◽  
Mitogen Activated Protein

The addition of platelet-activating factor (PAF) to human neutrophils increases phosphorylation on tyrosine residues and stimulates the activity of p42erk2 mitogen-activated protein kinase (MAP kinase). This action is rapid and transient. In contrast, p42erk2, p44erk1 and the p40hera MAP kinase isoforms are all not tyrosine phosphorylated or activated in human neutrophils stimulated with low concentrations of lipopolysaccharide (LPS) in combination with serum. In spite of this, the PAF-induced tyrosine phosphorylation and activation of the p42erk2 MAP kinase are greatly potentiated in cells pretreated with LPS. More interestingly, although low concentrations of LPS do not affect MAP kinase isoforms in these cells, they cause the phosphorylation of cytosolic phospholipase A2 (cPLA2), as evidenced by a decrease in the electrophoretic mobility of the enzyme. In addition, this stimulus-induced upward shift in the mobility of the enzyme is not inhibited by the tyrosine kinase inhibitor, genistein. Furthermore, LPS increases the release of arachidonic acid in control and PAF-stimulated human neutrophils. These observations clearly show that cPLA2 can be phosphorylated and activated by kinases other than the currently known MAP kinases. It is proposed that there are MAP kinase-dependent and -independent mechanisms for the phosphorylation of cPLA2.

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