Involvement of a pertussis toxin-sensitive G-protein-coupled phospholipase A2 in lipopolysaccharide-stimulated prostaglandin E2 synthesis in cultured rat mesangial cells

Wang, Jin; Kester, Mark; Dünn, Michael J.

doi:10.1016/0005-2760(88)90311-6

Cited by 40 publications

(19 citation statements)

References 26 publications

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“…Even less is known about the early intracellular events that mediate specific LPS responses. A pertussis toxinsensitive guanine nucleotide-binding protein (G protein) has been identified which couples the binding of LPS to the cell surface to the intracellular signal transduction pathways leading to the response such as altered gene expression of may cytokines (Jakway & DeFranco, 1986;Wang et al, 1988;Daniel-Issakani et al, 1989;Dziarski, 1989). However, some actions of LPS in cells are unaffected by pertussis toxin treatment (Dziarski, 1989;Forehand et al, 1989), suggesting that some of the responses elicited by LPS do not occur through a single class of a G protein-dependent signalling mechanism.…”

Section: Discussionmentioning

confidence: 99%

Involvement of tyrosine kinase in the induction of cyclo‐oxygenase and nitric oxide synthase by endotoxin in cultured cells

Akarasereenont

Mitchell

Appleton

et al. 1994

British J Pharmacology

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1 Cyclo-oxygenase (COX) and nitric oxide synthase (NOS) are two enzymes which have distinct cytokine-inducible isoforms (COX-2 and iNOS). Many cytokine receptors have an intracellular tyrosine kinase domain. Here we have used the tyrosine kinase inhibitors, erbstatin and genistein, to investigate the potential role of tyrosine kinase activation in the induction on COX-2 and iNOS caused by endotoxin (lipopolysaccharide; LPS) in bovine aortic endothelial cells (BAEC) and J774.2 macrophages. 2 The main COX metabolites, 6-oxo-prostaglandin Fl, (6-oxo-PGFI,) (for BAEC) and PGF2, (for 774.2 macrophages) were measured by radioimmunossay: (i) accumulation of COX metabolites from endogenous arachidonic acid was measured at 24 h after addition of LPS (1 jig ml-'); (ii) in experiments designed to measure 'COX activity', COX metabolites generated by BAEC or J774.2 macrophages activated with LPS were assayed (at 12 h after LPS administration) after incubation of the washed cells with exogenous arachidonic acid (30 tiM for 15 min). Western blot analysis with a specific antibody to COX-2 was used to determine the expression of COX-2 protein caused by LPS in cell extracts. Accumulation of nitrite (measured by the Griess reaction) was used as an indicator of NO formation and, hence, iNOS activity. 3 Erbstatin (0.05 to 5 jg ml-') or genistein (0.5 to 50 pg ml-') caused a dose-dependent inhibition of the accumulation of COX metabolites in the supernatant of BAEC or J774.2 macrophages activated with LPS. Erbstatin or genistein also caused a dose-dependent inhibition of 'COX activity' in both cell types. Western blot analysis showed that erbstatin (5 ig ml1') or genistein (50gg ml-') inhibited the expression of COX-2 protein in BAEC and J774.2 macrophages activated with LPS (lLgml-' for 24 h). 4 Erbstatin or genistein also caused a dose-dependent inhibition of nitrite accumulation in J774.2 macrophages activated with LPS (1 sg ml-' for 24 h). In contrast to J774.2 macrophages, BAEC stimulated with LPS (1 pg ml-' for 24 h) did not produce detectable amounts (<1PiM) of nitrite. 5These results suggest that tyrosine phosphorylation is part of the signal transduction mechanism that mediates (i) the induction of COX-2 and iNOS elicited by LPS in J774.2 macrophages, and (ii) the induction of COX-2 by LPS in BAEC.

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Section: Discussionmentioning

confidence: 99%

Involvement of tyrosine kinase in the induction of cyclo‐oxygenase and nitric oxide synthase by endotoxin in cultured cells

Akarasereenont

Mitchell

Appleton

et al. 1994

British J Pharmacology

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“…In terms of second-messenger systems, LPSstimulated inositolphospholipid hydrolysis has been observed in peritoneal macrophages (11). However, LPS does not stimulate detectable inositolphospholipid breakdown in many LPS-responsive cell types (9,12,13), including several murine macrophage cell lines (M.R.G., S. J. Estey, J. P. Jakway, and A.L.D., unpublished data). Thus, inositolphospholipid hydrolysis does not appear to be obligatory for many cellular responses to LPS.…”

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confidence: 95%

“…Even less is known about the early intracellular events that mediate LPS responses. Several investigators have reported that LPS activates a pertussis toxin-sensitive guanine nucleotidebinding protein (G protein) (6)(7)(8)(9). However, some LPS actions in cells are unaffected by pertussis toxin treatment (refs.…”

mentioning

confidence: 99%

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Bacterial lipopolysaccharide stimulates protein tyrosine phosphorylation in macrophages.

Weinstein

Gold

DeFranco

1991

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

334

213

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Lipopolysaccharide (LPS), a membrane component of Gram-negative bacteria, stimulates immune responses by activating macrophages, B lymphocytes, and other cells of the immune system. The mechanisms by which LPS activates these cells are poorly characterized. Since protein tyrosine phosphorylation appears to be a major intracellular signaling event that mediates cellular responses, we examined whether LPS alters tyrosine phosphorylation in macrophages.We found that Escherichia coli K235 LPS increased tyrosine phosphorylation of several proteins in the RAW 264.7 murine macrophage cell line and in resident peritoneal macrophages from C3H/HeSNJ mice. Changes in tyrosine phosphorylation were detectable by 4-5 min, reached a maximum by 15 min, and declined after 30-60 min. Protein tyrosine phosphorylation increased following stimulation with LPS at 100 pg/ml and was maximal with 10 ng/ml. Similar changes in tyrosine phosphorylation were induced by Salmonella minnesota R595 LPS and by the biologically active domain of LPS, lipid A, but not by the inactive lipid A derivative N2-monoacylglucosamine 1-phosphate. Phorbol 12-myristate 13-acetate also stimulated protein tyrosine phosphorylation, but some of the modulated proteins were different than those phosphorylated by LPS. Treatment ofRAW 264.7 cells with a tyrosine kinase inhibitor, herbimycin A, inhibited both LPS-stimulated tyrosine phosphorylation and LPS-stimulated release of arachidonic acid metabolites. Thus, increased protein tyrosine phosphorylation is a rapid LPSactivated signaling event that may mediate release of arachidonic acid metabolites in RAW 264.7 cells.

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“…5 Studies utilizing pertussis toxin, which specifically inhibits receptor-G i coupling by catalyzing the adenosine diphosphate ribosylation of G αi proteins, have demonstrated inhibition of LPS-induced transcription of TNFα and IL1 mRNA and inhibition of p38, JNK, and ERK1/2 phosphorylation. 17 Considering all the evidence that G i proteins are important regulators for the inflammatory effects of LPS in monocytes/ macrophages, cells with leading roles in cardiovascular disease initiation and progression, and that a potent G i inhibitor, guanosine 5′-O-(2-thiodiphosphate) (GOT), reduced inflammation in vascular cells, we evaluated in this study the anti-inflammatory effects of free GOT and GOT encapsulated in liposomes (Lipo/GOT) on LPS-activated human monocytes and macrophages. 18 We report here that Lipo/GOT blocked the production of cytokines and chemokines, such as IL1β, TNFα, IL6, and MCP1, and also inhibited activation of MAPK induced by LPS in monocytes and macrophages.…”

mentioning

confidence: 99%

Lipopolysaccharide-induced inflammation in monocytes/macrophages is blocked by liposomal delivery of G<sub>i</sub>-protein inhibitor

Pirvulescu¹,

Rebleanu²,

Constantinescu³

et al. 2017

IJN

108

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Background Lipopolysaccharide (LPS) is widely recognized as a potent activator of monocytes/macrophages, and its effects include an altered production of key mediators, such as inflammatory cytokines and chemokines. The involvement of G i protein in mediating LPS effects has been demonstrated in murine macrophages and various cell types of human origin. Purpose The aim of the present work was to evaluate the potential of a G i -protein inhibitor encapsulated in liposomes in reducing the inflammatory effects induced by LPS in monocytes/macrophages. Materials and methods Guanosine 5′- O -(2-thiodiphosphate) (GOT), a guanosine diphosphate analog that completely inhibits G-protein activation by guanosine triphosphate and its analogs, was encapsulated into liposomes and tested for anti-inflammatory effects in LPS-activated THP1 monocytes or THP1-derived macrophages. The viability of monocytes/macrophages after incubation with different concentrations of free GOT or liposome-encapsulated GOT was assessed by MTT assay. MAPK activation and production of IL1β, TNFα, IL6, and MCP1 were assessed in LPS-activated monocytes/macrophages in the presence or absence of free or encapsulated GOT. In addition, the effect of free or liposome-encapsulated GOT on LPS-stimulated monocyte adhesion to activated endothelium and on monocyte chemotaxis was evaluated. Results We report here that GOT-loaded liposomes inhibited activation of MAPK and blocked the production of the cytokines IL1β, TNFα, IL6, and MCP1 induced by LPS in monocytes and macrophages. Moreover, GOT encapsulated in liposomes reduced monocyte adhesion and chemotaxis. All demonstrated events were in contrast with free GOT, which showed reduced or no effect on monocyte/macrophage activation with LPS. Conclusion This study demonstrates the potential of liposomal GOT in blocking LPS proinflammatory effects in monocytes/macrophages.

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Involvement of a pertussis toxin-sensitive G-protein-coupled phospholipase A2 in lipopolysaccharide-stimulated prostaglandin E2 synthesis in cultured rat mesangial cells

Cited by 40 publications

References 26 publications

Involvement of tyrosine kinase in the induction of cyclo‐oxygenase and nitric oxide synthase by endotoxin in cultured cells

Involvement of tyrosine kinase in the induction of cyclo‐oxygenase and nitric oxide synthase by endotoxin in cultured cells

Bacterial lipopolysaccharide stimulates protein tyrosine phosphorylation in macrophages.

Lipopolysaccharide-induced inflammation in monocytes/macrophages is blocked by liposomal delivery of G<sub>i</sub>-protein inhibitor

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