Intracellular platelet‐activating factor regulates eicosanoid generation in guinea‐pig resident peritoneal macrophages

Stewart, Alastair G.; Phillips, Wayne A.

doi:10.1111/j.1476-5381.1989.tb16874.x

Cited by 51 publications

(16 citation statements)

References 25 publications

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“…We have previously found that this extraction gives a recovery of 94% from Tyrode's buffer [28], The extracts were subjected to centrifugation (5 min, 1,000 g) to remove the precipitate, and the supernatants were evaporated to dry ness under reduced pressure. The dried extracts were reconstituted in 200 pi of Tyrode's buffer (pH 7.4) containing 0.25% w/v BSA before PAF assay.…”

Section: Bioassay Ofpafmentioning

confidence: 99%

“…The dried extracts were reconstituted in 200 pi of Tyrode's buffer (pH 7.4) containing 0.25% w/v BSA before PAF assay. The amount of PAF was assayed by platelet aggregation at 37°C using a 540 ChronoLog aggregometer (Chrono-Log, USA) as described by Stewart and Phillips [28]. The reference cells contained a 1 in 10 dilution of platelets in Tyrodc's buffer (pH 7.4) containing 0.25% w/v BSA.…”

Section: Bioassay Ofpafmentioning

confidence: 99%

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Platelet-Activating Factor Biosynthesis in Rat Vascular Smooth Muscle Cells

Tomlinson

Croft

Harris³

et al. 1994

J Vasc Res

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The ability of platelet-activating factor (PAF) receptor antagonists to protect rats from the cardiovascular collapse induced by large doses of endothelin 1 led us to examine the capacity of rat cultured vascular smooth muscle cells to produce PAF and also to evaluate its potential functional roles in this cell type. Adenosine triphosphate and the vasoactive peptides, endothelin 1, angiotensin II, and arginine vasopressin, each elicited an increase in the PAF level in extracts of rat cultured vascular smooth muscle cells as determined by bioassay. PAF was not detectable (above 20 fmol/mg protein) in the supernatants of these cells. The identity of the bioactivity as PAF was confirmed by GC/MS which indicated that more than 80% of the PAF was 1-O-hexadecyl-2-acetyl-3-sn-glyceryl-phosphorylcholine. Exogenous PAF (100 nM) elicited increases in intracellular calcium that were inhibited by WEB 2086 (10 µM). Endothelin 1, at a concentration which stimulated PAF synthesis, (1 nM), elicited increases in intracellular calcium levels that were not inhibited by WEB 2086 (10 µM). Thus, endogenous PAF is unlikely to be involved in the endothelin-1-induced calcium increases. Although WEB 2086 (3–100 µM) inhibited concentration dependently fetal calf serum (10% v/v) induced [³H]-thymidine incorporation, reaching a maximum effect at 30 µM of 40-50% reduction, in parallel experiments WEB 2086 had no effect on serum-induced increases in cell numbers. We conclude that PAF is produced and retained by cultured rat vascular smooth muscle and that it is unlikely to contribute to the signaling of increases in intracellular calcium or proliferation.

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Section: Bioassay Ofpafmentioning

confidence: 99%

Section: Bioassay Ofpafmentioning

confidence: 99%

Platelet-Activating Factor Biosynthesis in Rat Vascular Smooth Muscle Cells

Tomlinson

Croft

Harris³

et al. 1994

J Vasc Res

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“…However, unlike other lipid mediators (e.g., prostaglandins and lipoxygenase products), once formed, PAF is often retained in cells (4)(5)(6). This cellular retention is a prominent feature of stimulus-evoked PAF and may underlie intracellular functions (4,7,8). When PAF is added to cells (e.g., washed rabbit platelets), it is rapidly internalized (9).…”

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confidence: 99%

Platelet-activating factor and retinoic acid synergistically activate the inducible prostaglandin synthase gene.

Bazán

Fletcher

Herschman

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

139

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Platelet-activating factor (PAF), a potent lipid mediator generated in cell injury and in the inflammatory and immune responses, promotes transcriptional activation of several primary response genes. TIS10/PGS-2 is a primary response gene encoding the inducible form of prostaglandin synthase. The inductive effects of PAF and retinoic acid (RA), alone and in combination, were studied with the regulatory region of TIS10/PGS-2 transfected into an exponentially growing glioblastoma-neuroblastoma NG108-15 hybrid in the human SH-SY5Y neuroblastoma or in the NIH 3T3 cell. RA alone exhibited only a small inductive effect. However, in the presence of RA (100 nM), a PAF-dependent (1-50 nM) synergistic activation of luciferase reporter constructs driven by regulatory regions of the TIS10/PGS-2 gene was found. The hetrazepine BN-50730, an antagonist selective for intracellular PAF binding sites, inhibited PAF and RA induction of luciferase from the TIS10/PGS-2 promoter. Thus, the intracellular PAF binding site is involved in TIS10/PGS-2 expression. Induction is rapid, suggesting that the combination of PAF and RA activates a preexisting latent transcription factor(s). Deletion studies restrict the major PAF and RA cis-acting response element of the TIS10/PGS-2 gene to a 70-nucleotide sequence as an intracellular inducer of TIS10/PGS-2 expression. The synergistic effect of RA and PAF represents an unusual convergence of nuclear signaling pathways by which, through the modulation of preexisting transcription factors, specific gene expression can be upregulated. PAF-dependent induction of TIS10/PGS-2 expression may play a role in cell injury, differentiation, inflammation, and immune responses.

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“…Nevertheless, the se lective, potent and structurally distinct PAF receptor antagonists, CV 6209 [1. 4] or WEB 2086 [5] reduce the basal PGI2 generation in both guinea pig [6] and rat peritoneal macro phages [7] by a mechanism which is clearly distinguishable from direct effects on either phospholipase A2, cyclo-oxygenase or PGI2 synthase [7], The lack of response to exoge nous PAF in rat macrophages is seemingly difficult to reconcile with a specific effect of the PAF receptor antagonists on the basal PGI2 generation.…”

Section: Introductionmentioning

confidence: 99%

Importance of Basal and Agonist-Stimulated Intracellular Calcium for Superoxide Anion Generation in Peritoneal Macrophages

Grigoriadis¹,

Lim²,

Stewart³

1993

Cell Physiol Biochem

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The cellular signalling mechanisms initiated by platelet-activating factor (PAF) for stimulation of superoxide anion (O^–₂) generation in peritoneal macrophages were investigated by monitoring intracellular calcium ([Ca²⁺]_i) levels. In rat peritoneal macrophages, exogenous PAF elicited an increase in [Ca²⁺]_i, but there was no O^–₂ generation. PAF elicited similar increases in [Ca²⁺]_i in guinea pig macrophages, which were accompanied by O^-₂ generation. Removal of external calcium revealed that the major component of the PAF-induced increase in [Ca²⁺]_i, in both rat and guina pig peritoneal macrophages, was dependent on transmembrane Ca²⁺ flux. Pertussis toxin pretreatment had no effect on basal or PAF-induced increases in [Ca²⁺]_i. In guinea pig macrophages, removal of external calcium or pertussis toxin pretreatment reduced O^–₂ generation by approximately 50% and the combination of these pretreatments caused almost complete suppression of the response. Thus, additional second mesenger systems are activated in guinea pig macrophages following PAF receptor activation which appear to be essential for O^–₂ generation.

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Intracellular platelet‐activating factor regulates eicosanoid generation in guinea‐pig resident peritoneal macrophages

Cited by 51 publications

References 25 publications

Platelet-Activating Factor Biosynthesis in Rat Vascular Smooth Muscle Cells

Platelet-Activating Factor Biosynthesis in Rat Vascular Smooth Muscle Cells

Platelet-activating factor and retinoic acid synergistically activate the inducible prostaglandin synthase gene.

Importance of Basal and Agonist-Stimulated Intracellular Calcium for Superoxide Anion Generation in Peritoneal Macrophages

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