Inhibition of Macrophage Ca2+-independent Phospholipase A2 by Bromoenol Lactone and Trifluoromethyl Ketones

Ackermann, Elizabeth J.; Conde‐Frieboes, Kilian; Dennis, Edward A.

doi:10.1074/jbc.270.1.445

Cited by 375 publications

(339 citation statements)

References 25 publications

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Section: Discussionmentioning

confidence: 72%

“…26 It would appear that, in our system, AACOCF 3 acts as a cPLA 2 inhibitor since its effects were not reproduced by HELSS, an iPLA 2 inhibitor. 26,27 The notion that cPLA 2 is specifically involved in the cytoprotective signalling opposing peroxynitrite toxicity was further established using antisense oligonucleotides downregulating either cPLA 2 ( Figure 6) or iPLA 2 ( Figure 7). Cells transfected with the respective nonsense oligonucleotides were used as a negative control and, in both toxicity and DHR oxidation studies, responded to peroxynitrite alone, or associated with various treatments, as the nontransfected cells.…”

Section: Discussionmentioning

confidence: 72%

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Hydrogen peroxide generated at the level of mitochondria in response to peroxynitrite promotes U937 cell death via inhibition of the cytoprotective signalling mediated by cytosolic phospholipase A2

et al. 2004

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We have studied the relationships existing between delayed formation of H 2 O 2 and activation of cytosolic phospholipase A 2 (cPLA 2 ), events respectively promoting toxicity or survival in U937 cells exposed to peroxynitrite. The outcome of an array of different approaches using phospholipase A 2 inhibitors, or cPLA 2 antisense oligonucleotides, as well as specific respiratory chain inhibitors and respiration-deficient cells led to the demonstration that H 2 O 2 does not mediate toxicity by producing direct molecular damage. Rather, the effects of H 2 O 2 were found to be upstream to the arachidonic acid (AA)-mediated cytoprotective signalling and in fact causally linked to inhibition of cPLA 2 . Thus, it appears that U937 cells exposed to nontoxic concentrations of peroxynitrite are nevertheless committed to death, which however is normally prevented by the activation of parallel pathways resulting in cPLA 2 -dependent release of AA. A rapid necrotic response, however, takes place when high concentrations of peroxynitrite promote formation of H 2 O 2 at levels impairing the cPLA 2 cytoprotective signalling.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 72%

Hydrogen peroxide generated at the level of mitochondria in response to peroxynitrite promotes U937 cell death via inhibition of the cytoprotective signalling mediated by cytosolic phospholipase A2

et al. 2004

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“…Exposure to 2244-TCB produced a significant increase in 3 H-AA release (Table 1). BEL, an inhibitor of the calcium-independent PLA 2 (Ackermann et al 1995), attenuated the 2244-TCB-mediated increase in 3 H-AA release. Incubation with either OP, an inhibitor of the cytosolic and secretory isoforms of PLA 2 (Magolda and Galbraith, 1989), or SB-202190, an inhibitor of p38 MAP kinase (Lee et al 1994), had no effect on 2244-TCBinduced 3 H-AA release.…”

Section: Effects Of Signal Transduction Inhibitors On 2244-tcb-mediatmentioning

confidence: 98%

2,2′,4,4′-Tetrachlorobiphenyl upregulates cyclooxygenase-2 in HL-60 cells via p38 mitogen-activated protein kinase and NF-κB

Bezdecny

Karmaus

Roth

et al. 2007

Toxicology and Applied Pharmacology

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Polychlorinated biphenyls (PCBs) are ubiquitous, persistent environmental contaminants that affect a number of cellular systems, including neutrophils. Among the effects caused by the noncoplanar PCB 2,2′,4,4′,-tetrachlorobiphenyl (2244-TCB) in granulocytic HL-60 cells are increases in superoxide anion production, activation of phospholipase A 2 with subsequent release of arachidonic acid (AA), and upregulation of the inflammatory gene cyclooxygenase-2 (COX-2). The objective of this study was to determine the signal transduction pathways involved in the upregulation of COX-2 by 2244-TCB. Treatment of HL-60 cells with 2244-TCB led to increased expression of COX-2 mRNA. This increase was prevented by the transcriptional inhibitor actinomycin D in cells pretreated with 2244-TCB for 10 minutes. The increase in COX-2 mRNA was associated with release of 3 H-AA, phosphorylation of p38 and extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinases, increased levels of nuclear NF-κB and increased superoxide anion production. Bromoenol lactone, an inhibitor of the calcium-independent phospholipase A 2 , reduced 3 H-AA release but had no effect on COX-2 mRNA, protein or activity. Pretreatment with SB-202190 or SB-203580, inhibitors of the p38 MAP kinase pathway, prevented the 2244-TCBmediated induction of COX-2 and phosphorylation of p38 and ERK MAP kinases. These inhibitors did not alter 3 H-AA release. Treatment with PD 98059 or U 0126, inhibitors of the MAP/ERK (MEK) pathway, prevented the 2244-TCB-mediated activation of ERK but had no effect on COX-2 induction or p38 phosphorylation. 2244-TCB treatment did not affect c-Jun N-terminal kinase (JNK) phosphorylation. 2244-TCB exposure increased the amount of nuclear NF-κB. This increase was prevented by pretreatment with p38 MAP kinase inhibitors, but not by pretreatment with MEK inhibitors. Pretreatment with inhibitors of NF-κB prevented the 2244-TCB-mediated induction of COX-2 mRNA. 2244-TCB-mediated increases in superoxide anion were prevented by the NADPH oxidase inhibitor apocynin or the free radical scavenger 4-hydroxy TEMPO, but neither of these inhibitors affected the 2244-TCB-induced changes in COX-2 mRNA levels or 3 H-AA release. Taken together these data suggest that p38 MAP kinase-dependent activation of NF-κB is critical for the 2244-TCB-mediated upregulation of COX-2 mRNA.

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“…Pyrrolidine-1 is a potent and selective inhibitor of cPLA 2 -α [48,49]. BEL is an inhibitor of iPLA 2 [56,57] whereas AACOCF 3 inhibits both cPLA 2 -α and iPLA 2 [56,58]. Furthermore, AACOCF 3 is known to inhibit thrombin-and calcium ionophore-induced arachidonic acid release and 12-HETE synthesis in human platelets [54,59].…”

Section: Pcb-induced Arachidonic Acid Release In Human Platelets Is Mmentioning

confidence: 99%

Polychlorinated biphenyls induce arachidonic acid release in human platelets in a tamoxifen sensitive manner via activation of group IVA cytosolic phospholipase A2-α

Forsell

Olsson

Andersson

et al. 2005

Biochemical Pharmacology

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Polychlorinated biphenyls (PCBs) are stable compounds commonly found in nature as environmental pollutants. PCBs can affect the endocrine function of hormones such as steroid-hormones. Also, PCBs are known to be inducers of arachidonic acid release in various cells. We report, here, the effects of PCBs on eicosanoid formation, arachidonic acid release and cytosolic phospholipase A 2 -α(cPLA 2 -α) activation in human platelets. Ortho-substituted PCBs induced a time and dosedependent release of arachidonic acid and the concomitant formation of 12(S)-hydroxy-5,8-cis-10-trans-14-cis-eicosatetraenoic acid (12-HETE) and 12(S)-hydroxy-5-cis-8,10-transheptadecatrienoic acid (12-HHT) in human platelets. The release of arachidonic acid and the formation of 12-HETE was completely blocked by the cPLA 2 -α inhibitors AACOCF 3 or pyrrolidine-1. PCB-treatment of platelets demonstrated that the cPLA 2 -α protein as well as PLA 2 activity translocated to the membrane fraction, independent of a rise in intracellular Ca 2+ . Furthermore, electrophoretic gel mobility shift analysis of cPLA 2 -α on SDS-PAGE demonstrated a PCB-dependent phosphorylation of cPLA 2 -α. The effects of 17β-estradiol and two structurally unrelated anti-estrogens, nafoxidin and tamoxifen on PCB-induced arachidonic acid release in platelets were also investigated. Both nafoxidin and tamoxifen inhibited PCB-induced arachidonic acid release as well as 12-HETE and 12-HHT formation. Interestingly, platelets incubated with PCBs did not aggregate despite the fact that robust release of arachidonic acid was observed. In summary, these results demonstrate that certain PCBs induce activation of cPLA 2 -α independent of a rise in intracellular calcium and a robust release of arachidonic acid release with resulting eicosanoid formation in human platelets.

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Inhibition of Macrophage Ca2+-independent Phospholipase A2 by Bromoenol Lactone and Trifluoromethyl Ketones

Cited by 375 publications

References 25 publications

Hydrogen peroxide generated at the level of mitochondria in response to peroxynitrite promotes U937 cell death via inhibition of the cytoprotective signalling mediated by cytosolic phospholipase A2

Hydrogen peroxide generated at the level of mitochondria in response to peroxynitrite promotes U937 cell death via inhibition of the cytoprotective signalling mediated by cytosolic phospholipase A2

2,2′,4,4′-Tetrachlorobiphenyl upregulates cyclooxygenase-2 in HL-60 cells via p38 mitogen-activated protein kinase and NF-κB

Polychlorinated biphenyls induce arachidonic acid release in human platelets in a tamoxifen sensitive manner via activation of group IVA cytosolic phospholipase A2-α

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