Phospholipid metabolism in human neutrophils activated by N-formyl-methionyl-leucyl-phenylalanine. Degranulation is not required for release of arachidonic acid: studies with neutrophils and neutrophil-derived cytoplasts

Neutrophils respond to chemoattractants by aggregating, degranulating, remodelling of phospholipids and releasing arachidonic acid. To determine whether ligand-induced remodelling of phospholipids depends on redistribution of intracellular organelles (degranulation), we compared phospholipid remodelling of human neutrophils with that of neutrophil-derived cytoplasts. Cytoplasts, organelle-depleted vesicles of cytosol surrounded by plasmalemma, cannot degranulate. Without a stimulus, [3H]arachidonate was incorporated preferentially into phosphatidylinositol (PI) and phosphatidylcholine (PC). Exposure of cytoplasts and neutrophils prelabelled with [3H]arachidonate or [14C]glycerol to fMet-Leu-Phe (10(-7) M) induced rapid changes in distribution of label and mass of individual phospholipids: [3H]arachidonate in phosphatidic acid (PA) increased 500% (120 s), [14C]glycerol incorporation and mass of PA approached 200% of unstimulated values, and [3H]arachidonate in PI decreased continuously; these data are compatible with activity of a PI/PA cycle. However, the mass of PI in both preparations and [14C]glycerol label in intact neutrophils increased initially (5 s), suggesting net synthesis and mobilization of more than one pool of PI. Heterogeneity of PC pools was also observed: [3H]arachidonate was lost from PC immediately upon addition of stimulus, whereas mass and [14C]glycerol values increased. Thus, net phospholipid synthesis, redistribution of arachidonate and activation of the PI/PA cycle are immediate responses of the neutrophil to receptor occupancy by chemoattractants. Furthermore, the similarity in response to fMet-Leu-Phe of neutrophils and granule-free cytoplasts indicates that these processes are independent of degranulation.

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The initial action of thrombin on platelets. Conversion of phosphatidylinositol to phosphatidic acid preceding the production of arachidonic acid.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)69362-2 ◽

1981 ◽

Vol 256 (10) ◽

pp. 5037-5040 ◽

Cited By ~ 1

Author(s):

E.G. Lapetina ◽

M.M. Billah ◽

P. Cuatrecasas

Keyword(s):

Arachidonic Acid ◽

Phosphatidic Acid ◽

Initial Action

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Alterations in cellular and organellar phospholipid compositions of HepG2 cells during cell growth

Scientific Reports ◽

10.1038/s41598-021-81733-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tokuji Tsuji ◽

Shin-ya Morita ◽

Yoshinobu Nakamura ◽

Yoshito Ikeda ◽

Taiho Kambe ◽

...

Keyword(s):

Cell Growth ◽

Hepg2 Cells ◽

Phospholipid Class ◽

Present Report ◽

Phospholipid Metabolism ◽

Cancer Cell Growth ◽

Microsomal Membranes ◽

Intracellular Organelles ◽

The Relationship ◽

Pe Ratio

AbstractThe human hepatoblastoma cell line, HepG2, has been used for investigating a wide variety of physiological and pathophysiological processes. However, less information is available about the phospholipid metabolism in HepG2 cells. In the present report, to clarify the relationship between cell growth and phospholipid metabolism in HepG2 cells, we examined the phospholipid class compositions of the cells and their intracellular organelles by using enzymatic fluorometric methods. In HepG2 cells, the ratios of all phospholipid classes, but not the ratio of cholesterol, markedly changed with cell growth. Of note, depending on cell growth, the phosphatidic acid (PA) ratio increased and phosphatidylcholine (PC) ratio decreased in the nuclear membranes, the sphingomyelin (SM) ratio increased in the microsomal membranes, and the phosphatidylethanolamine (PE) ratio increased and the phosphatidylserine (PS) ratio decreased in the mitochondrial membranes. Moreover, the mRNA expression levels of enzymes related to PC, PE, PS, PA, SM and cardiolipin syntheses changed during cell growth. We suggest that the phospholipid class compositions of organellar membranes are tightly regulated by cell growth. These findings provide a basis for future investigations of cancer cell growth and lipid metabolism.

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Effect of membrane cholesterol on phospholipid metabolism in thrombin-stimulated platelets. Enhanced activation of platelet phospholipase(s) for liberation of arachidonic acid.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)34506-x ◽

1982 ◽

Vol 257 (12) ◽

pp. 6844-6849 ◽

Cited By ~ 2

Author(s):

R M Kramer ◽

J A Jakubowski ◽

R Vaillancourt ◽

D Deykin

Keyword(s):

Arachidonic Acid ◽

Phospholipid Metabolism ◽

Membrane Cholesterol

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Phorbol Esters Stimulate Phospholipase D Activity in C-6 Glioma Cells

Alternatives to Laboratory Animals ◽

10.1177/026119298901600309 ◽

1989 ◽

Vol 16 (3) ◽

pp. 257-262

Author(s):

Lena Gustavsson ◽

Christofer Lundqvist ◽

Christer Ailing

Keyword(s):

Arachidonic Acid ◽

Phosphatidic Acid ◽

Phospholipase D ◽

Culture Medium ◽

Phorbol Esters ◽

Glioma Cells

The effects of phorbol esters on phospholipase D activity were studied in C-6 glioma cells. The cell lipids were prelabelled with [3H]-glycerol or [14C]-arachidonic acid. Phosphatidylethanol was formed during stimulation with 100nM 12-0-tetradecanoylphorbol-13-acetate (TPA), when ethanol was present in the culture medium. After 30 minutes of stimulation, phosphatidylethanol constituted 2.6% of the [3H]-glycerol-labelled lipids. Stimulating the cells with TPA in the absence of ethanol caused a significant increase in labelled phosphatidic acid. This increase was inhibited by ethanol. The present findings demonstrate that TPA stimulates phospholipase D activity in cultured C-6 glioma cells.

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Arachidonic acid stimulates the formation of 1,2-diacylglycerol and phosphatidic acid in human platelets. Degree of phospholipase C activation correlates with protein phosphorylation, platelet shape change, serotonin release, and aggregation.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)44408-5 ◽

1983 ◽

Vol 258 (18) ◽

pp. 11236-11242 ◽

Cited By ~ 21

Author(s):

W Siess ◽

F L Siegel ◽

E G Lapetina

Keyword(s):

Arachidonic Acid ◽

Phosphatidic Acid ◽

Protein Phosphorylation ◽

Phospholipase C ◽

Shape Change ◽

Human Platelets ◽

Serotonin Release ◽

Platelet Shape

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Arachidonic acid release from diacylglycerol in human neutrophils. Translocation of diacylglycerol-deacylating enzyme activities from an intracellular pool to plasma membrane upon cell activation

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)98454-1 ◽

1991 ◽

Vol 266 (24) ◽

pp. 15638-15643 ◽

Cited By ~ 2

Author(s):

J. Balsinde ◽

E. Diez ◽

F. Mollinedo

Keyword(s):

Arachidonic Acid ◽

Plasma Membrane ◽

Enzyme Activities ◽

Cell Activation ◽

Human Neutrophils ◽

Arachidonic Acid Release ◽

Intracellular Pool ◽

Acid Release

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Transfer of arachidonic acid from phosphatidylcholine to phosphatidylethanolamine during storage of human platelets for 5 days

Biochemistry and Cell Biology ◽

10.1139/o90-016 ◽

1990 ◽

Vol 68 (1) ◽

pp. 117-122 ◽

Cited By ~ 1

Author(s):

Julie Lacasse ◽

Rosalind S. Labow ◽

Morris Kates ◽

George A. Adams

Keyword(s):

Arachidonic Acid ◽

Storage Conditions ◽

Phospholipid Metabolism ◽

Human Platelets ◽

Acyl Transfer ◽

Acid Uptake ◽

Molar Composition ◽

Platelet Storage ◽

Head Groups ◽

Glycerol Uptake

Human platelets are routinely stored for 5 days prior to transfusion, but they deteriorate during storage. Since very little information is available concerning the effect of storage on platelet phospholipid metabolism, the biosynthesis and remodelling of platelet phospholipids were studied. Platelets were incubated separately with [14C]glycerol, [14C]arachidonic acid, or a mixture of [14C]glycerol and [3H]arachidonic acid, and stored in a platelet storage medium at 22 °C. Maximum glycerol uptake (20%) was attained after 6 h. [14C]Glycerol was incorporated into phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol, and to a much lesser extent phosphatidylserine, under storage conditions for 5 days. The distribution of the initial arachidonic acid uptake was not as would be expected based on the molar composition of endogenous phospholipids. The arachidonic acid (75%) which was taken up within 10 min of incubation distributed 55% into the phosphatidylcholine and only 14% into the phosphatidylethanolamine; the molar composition is actually 18% phosphatidylcholine and 47% phosphatidylethanolamine. During storage, there was a continuous transfer of the radiolabeled arachidonic acid from phosphatidylcholine to phosphatidylethanolamine until, after 5 days, the distribution of arachidonic acid was identical to the endogenous distribution. In contrast, no change in the glycerol incorporation pattern was detected during storage. This suggested that the mechanism for arachidonic acid redistribution was not through exchange of polar head groups, but through acyl transfer of arachidonic acid from phosphatidylcholine to phosphatidylethanolamine.Key words: human, platelet, storage, arachidonate, phospholipids.

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