1
|
Hwang SW, Cho H, Kwak J, Lee SY, Kang CJ, Jung J, Cho S, Min KH, Suh YG, Kim D, Oh U. Direct activation of capsaicin receptors by products of lipoxygenases: endogenous capsaicin-like substances. Proc Natl Acad Sci U S A 2000; 97:6155-60. [PMID: 10823958 PMCID: PMC18574 DOI: 10.1073/pnas.97.11.6155] [Citation(s) in RCA: 838] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Capsaicin, a pungent ingredient of hot peppers, causes excitation of small sensory neurons, and thereby produces severe pain. A nonselective cation channel activated by capsaicin has been identified in sensory neurons and a cDNA encoding the channel has been cloned recently. However, an endogenous activator of the receptor has not yet been found. In this study, we show that several products of lipoxygenases directly activate the capsaicin-activated channel in isolated membrane patches of sensory neurons. Among them, 12- and 15-(S)-hydroperoxyeicosatetraenoic acids, 5- and 15-(S)-hydroxyeicosatetraenoic acids, and leukotriene B(4) possessed the highest potency. The eicosanoids also activated the cloned capsaicin receptor (VR1) expressed in HEK cells. Prostaglandins and unsaturated fatty acids failed to activate the channel. These results suggest a novel signaling mechanism underlying the pain sensory transduction.
Collapse
|
research-article |
25 |
838 |
2
|
Kim D, Lewis DL, Graziadei L, Neer EJ, Bar-Sagi D, Clapham DE. G-protein beta gamma-subunits activate the cardiac muscarinic K+-channel via phospholipase A2. Nature 1989; 337:557-60. [PMID: 2492640 DOI: 10.1038/337557a0] [Citation(s) in RCA: 310] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Muscarinic receptors of cardiac pacemaker and atrial cells are linked to a potassium channel (IK.ACh) by a pertussis toxin-sensitive GTP-binding protein. The dissociation of G-proteins leads to the generation of two potential transducing elements, alpha-GTP and beta gamma. IK.ACh is activated by G-protein alpha- and beta gamma-subunits applied to the intracellular surface of inside-out patches of membrane. beta gamma has been shown to activate the membrane-bound enzyme phospholipase A2 in retinal rods. Arachidonic acid, which is produced from the action of phospholipase A2 on phospholipids, is metabolized to compounds which may act as second messengers regulating ion channels in Aplysia. Muscarinic receptor activation leads to the generation of arachidonic acid in some cell lines. We therefore tested the hypothesis that beta gamma activates IK.ACh by stimulation of phospholipase A2. When patches were first incubated with antibody that blocks phospholipase A2 activity, or with the lipoxygenase inhibitor, nordihydroguaiaretic acid, beta gamma failed to activate IK.ACh. Arachidonic acid and several of its metabolites derived from the 5-lipoxygenase pathway, activated the channel. Blockade of the cyclooxygenase pathway did not inhibit arachidonic acid-induced channel activation. We conclude that the beta gamma-subunit of G-proteins activates IK.ACh by stimulating the production of lipoxygenase-derived second messengers.
Collapse
|
|
36 |
310 |
3
|
Kurachi Y, Ito H, Sugimoto T, Shimizu T, Miki I, Ui M. Arachidonic acid metabolites as intracellular modulators of the G protein-gated cardiac K+ channel. Nature 1989; 337:555-7. [PMID: 2492639 DOI: 10.1038/337555a0] [Citation(s) in RCA: 261] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Arachidonic acid is released from cell membranes in response to receptor-dependent as well as receptor-independent stimulation in various cells, including cardiac myocytes. Arachidonic acid is converted to prostaglandins by cyclooxygenase and to leukotrienes by 5-lipoxygenase, metabolites which are very biologically active and modulate cellular functions such as platelet aggregation, smooth muscle contraction and neural excitation. The molecular mechanisms underlying their modulations are, however, still badly understood. Here, we report that the 5-lipoxygenase metabolites of arachidonic acid activate the pertussis toxin-sensitive G protein-gated muscarinic K+ channel (IK.ACh): arachidonic acid activation of IK.ACh was prevented by the lipoxygenase inhibitors, nordihydroguaiaretic acid and AA-861; leukotriene A4 and C4 activated IK.ACh. The activation occurred in pertussis toxin-treated atrial cells and ceased when inside-out patches were formed but the patches were still susceptible to stimulation by GTP and to inhibition by GDP-beta-S. These results indicate that arachidonic acid metabolites may stimulate the G-protein in a receptor-independent way.
Collapse
|
|
36 |
261 |
4
|
Tang DG, Chen YQ, Honn KV. Arachidonate lipoxygenases as essential regulators of cell survival and apoptosis. Proc Natl Acad Sci U S A 1996; 93:5241-6. [PMID: 8643560 PMCID: PMC39229 DOI: 10.1073/pnas.93.11.5241] [Citation(s) in RCA: 249] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Arachidonic acid (AA) metabolites derived from both cyclooxygenase (COX) and lipoxygenase (LOX) pathways transduce a variety of signals related to cell growth. Here, we report that the AA LOX pathway also functions as a critical regulator of cell survival and apoptosis. Rat Walker 256 (W256) carcinosarcoma cells express 12-LOX and synthesize 12(S)- and 15(S)-hydroxyeicosatetraenoic acids as their major LOX metabolites. W256 cells transfected with 12-LOX-specific antisense oligonucleotide or antisense oligonucleotides directed to conserved regions of LOXs underwent time- and dose-dependent apoptosis. Likewise, treatment of W256 cells with various LOX but not COX inhibitors induced apoptotic cell death, which could be partially inhibited by exogenous 12(S)- or 15(S)-hydroxyeicosatetraenoic acids. The W256 cell apoptosis induced by antisense oligos and LOX inhibitors was followed by a rapid downregulation of bcl-2 protein, a dramatic decrease in the bcl-2/bax ratio, and could be suppressed by bcl-2 overexpression. In contrast, p53, which is wild type in W256 cells, did not undergo alterations during apoptosis induction. The results suggest that the LOX pathway plays an important physiological role in regulating apoptosis.
Collapse
|
research-article |
29 |
249 |
5
|
Mahipal SVK, Subhashini J, Reddy MC, Reddy MM, Anilkumar K, Roy KR, Reddy GV, Reddanna P. Effect of 15-lipoxygenase metabolites, 15-(S)-HPETE and 15-(S)-HETE on chronic myelogenous leukemia cell line K-562: reactive oxygen species (ROS) mediate caspase-dependent apoptosis. Biochem Pharmacol 2007; 74:202-14. [PMID: 17517376 DOI: 10.1016/j.bcp.2007.04.005] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 04/03/2007] [Accepted: 04/04/2007] [Indexed: 10/23/2022]
Abstract
Growth inhibitory effects of 15-lipoxygenase-1 [13-(S)-HPODE and 13-(S)-HODE] and 15-lipoxygenase-2 [15-(S)-HPETE and 15-(S)-HETE] (15-LOX-1 and LOX-2) metabolites and the underlying mechanisms were studied on chronic myeloid leukemia cell line (K-562). The hydroperoxy metabolites, 15-(S)-HPETE and 13-(S)-HPODE rapidly inhibited the growth of K-562 cells by 3h with IC(50) values, 10 and 15microM, respectively. In contrast, the hydroxy metabolite of 15-LOX-2, 15-(S)-HETE, showed 50% inhibition only at 40microM by 6h and 13-(S)-HODE, hydroxy metabolite of 15-LOX-1, showed no significant effect up to 160microM. The cells exposed to 10microM of 15-(S)-HPETE and 40microM of 15-(S)-HETE showed typical apoptotic features like release of cytochrome c, caspase-3 activation and PARP-1 (poly(ADP) ribose polymerase-1) cleavage. A flow cytometry based DCFH-DA analysis and inhibitory studies with DPI, a pharmacological inhibitor of NADPH oxidase, NAC (N-acetyl cysteine) and GSH revealed that NADPH oxidase-mediated generation of ROS is responsible for caspase-3 activation and subsequent induction of apoptosis in the K-562 cell line.
Collapse
|
Research Support, Non-U.S. Gov't |
18 |
233 |
6
|
Peppelenbosch MP, Tertoolen LG, Hage WJ, de Laat SW. Epidermal growth factor-induced actin remodeling is regulated by 5-lipoxygenase and cyclooxygenase products. Cell 1993; 74:565-75. [PMID: 8348619 DOI: 10.1016/0092-8674(93)80057-l] [Citation(s) in RCA: 197] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In a number of cell types, epidermal growth factor (EGF) evokes dramatic morphological changes, cortical actin polymerization, and stress fiber breakdown. The molecular processes by which increased EGF receptor tyrosine kinase activity results in actin reorganization and morphological changes are unresolved. Recently, we demonstrated that arachidonic acid metabolites function in EGF signal transduction. We now report that in A431 cells, HeLa cells, and rat-1 fibroblasts, the EGF-induced cortical actin polymerization is produced by lipoxygenase metabolism, whereas in these cells stress fiber breakdown is mediated by cyclooxygenase metabolites. Also, the EGF-provoked rounding up in A431 cells is dependent on arachidonic acid metabolism. We conclude that leukotrienes and prostaglandins act in concert, as second messengers, to produce morphological effects and actin reorganization, providing a novel mechanism for directing growth factor-induced cytoskeletal changes.
Collapse
|
|
32 |
197 |
7
|
Zhang Y, Ramos BF, Jakschik BA. Neutrophil recruitment by tumor necrosis factor from mast cells in immune complex peritonitis. Science 1992; 258:1957-9. [PMID: 1470922 DOI: 10.1126/science.1470922] [Citation(s) in RCA: 192] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
During generalized immune complex-induced inflammation of the peritoneal cavity, two peaks of tumor necrosis factor (TNF) were observed in the peritoneal exudate of normal mice. In mast cell-deficient mice, the first peak was undetected, and the second peak of TNF and neutrophil influx were significantly reduced. Antibody to TNF significantly inhibited neutrophil infiltration in normal but not in mast cell-deficient mice. Mast cell repletion of the latter normalized TNF, neutrophil mobilization, and the effect of the antibody to TNF. Thus, in vivo, mast cells produce the TNF that augments neutrophil emigration.
Collapse
|
|
33 |
192 |
8
|
Tomita Y, Maeda K, Tagami H. Melanocyte-stimulating properties of arachidonic acid metabolites: possible role in postinflammatory pigmentation. PIGMENT CELL RESEARCH 1992; 5:357-61. [PMID: 1292020 DOI: 10.1111/j.1600-0749.1992.tb00562.x] [Citation(s) in RCA: 160] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Normal human epidermal melanocytes became swollen and more dendritic with an increase in the amount of tyrosinase and immunoreactive b-locus protein when they were cultured for 2 days with the following arachidonic acid metabolites: prostaglandin (PG) D2, leukotriene (LT) B4, LTC4, LTD4, LTE4, thromboxane (TX) B2 and 12-hydroxy eicosatetraenoic acid (12-HETE). The effect of LTC4 was particularly strong compared to that of PGE2, about which we have previously reported. On the other hand, PGE1, PGF2 alpha and 6-ketoPGF1 alpha did not show any significant stimulatory effect. These data suggest that arachidonate-derived chemical mediators, especially LTC4, may be responsible for the induction of post-inflammatory hyperpigmentation of the skin.
Collapse
|
|
33 |
160 |
9
|
Feltenmark S, Gautam N, Brunnström Å, Griffiths W, Backman L, Edenius C, Lindbom L, Björkholm M, Claesson HE. Eoxins are proinflammatory arachidonic acid metabolites produced via the 15-lipoxygenase-1 pathway in human eosinophils and mast cells. Proc Natl Acad Sci U S A 2008; 105:680-5. [PMID: 18184802 PMCID: PMC2206596 DOI: 10.1073/pnas.0710127105] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Indexed: 12/23/2022] Open
Abstract
Human eosinophils contain abundant amounts of 15-lipoxygenase (LO)-1. The biological role of 15-LO-1 in humans, however, is unclear. Incubation of eosinophils with arachidonic acid led to formation of a product with a UV absorbance maximum at 282 nm and shorter retention time than leukotriene (LT)C4 in reverse-phase HPLC. Analysis with positive-ion electrospray tandem MS identified this eosinophil metabolite as 14,15-LTC4. This metabolite could be metabolized to 14,15-LTD4 and 14,15-LTE4 in eosinophils. Because eosinophils are such an abundant source of these metabolites and to avoid confusion with 5-LO-derived LTs, we suggest the names eoxin (EX)C4, -D4, and -E4 instead of 14,15-LTC4, -D4, and -E4, respectively. Cord blood-derived mast cells and surgically removed nasal polyps from allergic subjects also produced EXC4. Incubation of eosinophils with arachidonic acid favored the production of EXC4, whereas challenge with calcium ionophore led to exclusive formation of LTC4. Eosinophils produced EXC4 after challenge with the proinflammatory agents LTC4, prostaglandin D2, and IL-5, demonstrating that EXC4 can be synthesized from the endogenous pool of arachidonic acid. EXs induced increased permeability of endothelial cell monolayer in vitro, indicating that EXs can modulate and enhance vascular permeability, a hallmark of inflammation. In this model system, EXs were 100 times more potent than histamine and almost as potent as LTC4 and LTD4. Taken together, this article describes the formation of proinflammatory EXs, in particular in human eosinophils but also in human mast cells and nasal polyps.
Collapse
|
research-article |
17 |
134 |
10
|
Baker LMS, Poole LB. Catalytic mechanism of thiol peroxidase from Escherichia coli. Sulfenic acid formation and overoxidation of essential CYS61. J Biol Chem 2003; 278:9203-11. [PMID: 12514184 PMCID: PMC3845838 DOI: 10.1074/jbc.m209888200] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli thiol peroxidase (Tpx, p20, scavengase) is part of an oxidative stress defense system that uses reducing equivalents from thioredoxin (Trx1) and thioredoxin reductase to reduce alkyl hydroperoxides. Tpx contains three Cys residues, Cys(95), Cys(82), and Cys(61), and the latter residue aligns with the N-terminal active site Cys of other peroxidases in the peroxiredoxin family. To identify the catalytically important Cys, we have cloned and purified Tpx and four mutants (C61S, C82S, C95S, and C82S,C95S). In rapid reaction kinetic experiments measuring steady-state turnover, C61S is inactive, C95S retains partial activity, and the C82S mutation only slightly affects reaction rates. Furthermore, a sulfenic acid intermediate at Cys(61) generated by cumene hydroperoxide (CHP) treatment was detected in UV-visible spectra of 4-nitrobenzo-2-oxa-1,3-diazole-labeled C82S,C95S, confirming the identity of Cys(61) as the peroxidatic center. In stopped-flow kinetic studies, Tpx and Trx1 form a Michaelis complex during turnover with a catalytic efficiency of 3.0 x 10(6) m(-1) s(-1), and the low K(m) (9.0 microm) of Tpx for CHP demonstrates substrate specificity toward alkyl hydroperoxides over H(2)O(2) (K(m) > 1.7 mm). Rapid inactivation of Tpx due to Cys(61) overoxidation is observed during turnover with CHP and a lipid hydroperoxide, 15-hydroperoxyeicosatetraenoic acid, but not H(2)O(2). Unlike most other 2-Cys peroxiredoxins, which operate by an intersubunit disulfide mechanism, Tpx contains a redox-active intrasubunit disulfide bond yet is homodimeric in solution.
Collapse
|
research-article |
22 |
127 |
11
|
Serezani CHC, Aronoff DM, Jancar S, Mancuso P, Peters-Golden M. Leukotrienes enhance the bactericidal activity of alveolar macrophages against Klebsiella pneumoniae through the activation of NADPH oxidase. Blood 2005; 106:1067-75. [PMID: 15718414 PMCID: PMC1895163 DOI: 10.1182/blood-2004-08-3323] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Leukotrienes (LTs) are lipid mediators that participate in inflammatory diseases and innate immune function. We sought to investigate the importance of LTs in regulating the microbicidal activity of alveolar macrophages (AMs) and the molecular mechanisms by which this occurs. The role of LTs in enhancing AM microbicidal activity was evaluated pharmacologically and genetically using in vitro challenge with Klebsiella pneumoniae. Exogenous LTs increased AM microbicidal activity in a dose- and receptor-dependent manner, and endogenous production of LTs was necessary for optimal killing. Leukotriene B4 (LTB4) was more potent than cysteinyl LTs. An important role for nicotinamide adenine dinucleotide (NADPH) oxidase in LT-induced microbicidal activity was indicated by the fact that bacterial killing was abrogated by the NADPH oxidase inhibitor diphenyleneiodonium (DPI; 10 microM) and in AMs derived from gp91phox-deficient mice. By contrast, LT-induced microbicidal activity was independent of the generation of nitric oxide. LTs increased H2O2 production, and LTB4 was again the more potent agonist. Both classes of LTs elicited translocation of p47phox to the cell membrane, and LTB4 induced phosphorylation of p47phox in a manner dependent on protein kinase C-delta (PKC-delta) activity. In addition, the enhancement of microbicidal activity by LTs was also dependent on PKC-delta activity. Our results demonstrate that LTs, especially LTB4, enhanceAM microbicidal activity through the PKC-delta-dependent activation of NADPH oxidase.
Collapse
|
Research Support, U.S. Gov't, P.H.S. |
20 |
125 |
12
|
Mellor EA, Austen KF, Boyce JA. Cysteinyl leukotrienes and uridine diphosphate induce cytokine generation by human mast cells through an interleukin 4-regulated pathway that is inhibited by leukotriene receptor antagonists. J Exp Med 2002; 195:583-92. [PMID: 11877481 PMCID: PMC2193768 DOI: 10.1084/jem.20020044] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We previously reported that interleukin (IL)-4 upregulates the expression of leukotriene C(4) synthase (LTC(4)S) by human cord blood--derived mast cells (hMCs), augments their high-affinity Fc receptor for IgE (Fc(epsilon)RI)-dependent generation of eicosanoids and cytokines, and induces a calcium flux in response to cysteinyl leukotrienes (cys-LTs) and uridine diphosphate (UDP) that is blocked by cys-LT receptor antagonists. We speculated that this IL-4-dependent, receptor-mediated response to the cys-LTs and UDP might induce cytokine generation by hMCs without concomitant exocytosis. Unlike hMCs maintained in cytoprotective stem cell factor (SCF) alone, hMCs primed for 5 d with IL-4 responded to UDP (1microM), LTC(4) (100 nM), and LTD(4) (100 nM) by producing IL-5, tumor necrosis factor (TNF)-alpha, and especially large quantities of macrophage inflammatory protein (MIP)-1beta de novo at 6 h, preceded by the induced expression of the corresponding mRNAs. Cys-LT- and UDP-mediated cytokine production by the primed hMCs occurred without histamine release or PGD(2) generation and was inhibited by the CysLT1 receptor antagonist MK571. Additionally, pretreatment of hMCs with MK571 or with the cys-LT biosynthetic inhibitor MK886 decreased IL-5 and TNF-alpha production in response to IgE receptor cross-linkage, implying a positive feedback by endogenously produced cys-LTs. Cys-LTs and UDP thus orchestrate a novel, IL-4-regulated, non-IgE-dependent hMC activation for cytokine gene induction that could be initiated by microbes, cellular injury, or neurogenic or inflammatory signals; and this pathobiologic event would not be recognized in tissue studies where hMC activation is classically defined by exocytosis.
Collapse
|
research-article |
23 |
118 |
13
|
Jiang Y, Borrelli LA, Kanaoka Y, Bacskai BJ, Boyce JA. CysLT2 receptors interact with CysLT1 receptors and down-modulate cysteinyl leukotriene dependent mitogenic responses of mast cells. Blood 2007; 110:3263-70. [PMID: 17693579 PMCID: PMC2200919 DOI: 10.1182/blood-2007-07-100453] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cysteinyl leukotrienes (cys-LTs) induce inflammation through 2 G protein-coupled receptors (GPCRs), CysLT(1) and CysLT(2), which are coexpressed by most myeloid cells. Cys-LTs induce proliferation of mast cells (MCs), transactivate c-Kit, and phosphorylate extracellular signal-regulated kinase (ERK). Although MCs express CysLT(2), their responses to cys-LTs are blocked by antagonists of CysLT(1). We demonstrate that CysLT(2) interacts with CysLT(1), and that knockdown of CysLT(2) increases CysLT(1) surface expression and CysLT(1)-dependent proliferation of cord blood-derived human MCs (hMCs). Cys-LT-mediated responses were absent in MCs from mice lacking CysLT(1) receptors, but enhanced by the absence of CysLT(2) receptors. CysLT(1) and CysLT(2) receptors colocalized to the plasma membranes and nuclei of a human MC line, LAD2. Antibody-based fluorescent lifetime imaging microscopy confirmed complexes containing both receptors based on fluorescence energy transfer. Negative regulation of CysLT(1)-induced mitogenic signaling responses of MCs by CysLT(2) demonstrates physiologically relevant functions for GPCR heterodimers on primary cells central to inflammation.
Collapse
|
Research Support, N.I.H., Extramural |
18 |
116 |
14
|
Wang X, Walsh LP, Reinhart AJ, Stocco DM. The role of arachidonic acid in steroidogenesis and steroidogenic acute regulatory (StAR) gene and protein expression. J Biol Chem 2000; 275:20204-9. [PMID: 10777507 DOI: 10.1074/jbc.m003113200] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study was conducted to examine the mechanism for arachidonic acid (AA) regulation of steroidogenic acute regulatory (StAR) protein expression and the relationship between AA and cAMP in hormone-induced steroidogenesis. Dibutyryl cyclic AMP (Bt(2)cAMP)-stimulated MA-10 Leydig cells were treated with AA and/or the phospholipase A(2) inhibitor, dexamethasone. Dexamethasone significantly reduced Bt(2)cAMP-stimulated progesterone production, StAR promoter activity, StAR mRNA, and StAR protein. The inhibitory effects of dexamethasone were reversed by the addition of 150 microm AA to MA-10 cells. In addition, MA-10 cells were treated with the lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA), the 5-lipoxygenase inhibitor, AA861, the epoxygenase inhibitor, miconazole, and the cyclooxygenase inhibitor, indomethacin. Both NDGA and AA861 inhibited progesterone production and StAR protein expression. AA861-inhibited progesterone synthesis and StAR protein were partially reversed by addition of the 5- lipoxygenase metabolite, 5(S)-hydroperoxy-(6E,8Z,11Z, 14Z)-eicosatetraenoic acid. Inhibition of epoxygenase activity inhibited progesterone production significantly, but StAR protein was only slightly reduced. Indomethacin enhanced StAR protein expression and significantly increased progesterone production. Inhibition of AA release or lipoxygenase activities did not affect protein kinase A activity, whereas inhibition of protein kinase A activity using H89 reduced Bt(2)cAMP-induced StAR protein. AA alone did not induce StAR protein expression nor steroid production. These results demonstrate the essential role of AA in steroid biosynthesis and StAR gene transcription and suggest the possible involvement of the lipoxygenase pathway in steroidogenesis. This study further indicates that AA and cAMP transduce signals from trophic hormone receptors to the nucleus through two separate pathways and act to co-regulate steroid production and StAR gene expression and indicates that both pathways are required for trophic hormone-stimulated steroidogenesis.
Collapse
|
|
25 |
113 |
15
|
Lynch MA, Voss KL. Arachidonic acid increases inositol phospholipid metabolism and glutamate release in synaptosomes prepared from hippocampal tissue. J Neurochem 1990; 55:215-21. [PMID: 1972388 DOI: 10.1111/j.1471-4159.1990.tb08841.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have been interested in the possibility that arachidonic acid or one of its 12-lipoxygenase metabolites may function as a retrograde messenger in long-term potentiation (LTP) in the dentate gyrus of the hippocampus. One criterion required of a retrograde messenger is that it stimulates presynaptic changes. Here, two possible presynaptic actions of arachidonic acid and its 12-lipoxygenase metabolites, 12-hydroxyeicosatetraenoic acid (HETE) and 12-hydroperoxyeicosatetraenoic acid (HPETE), are examined. We report that arachidonic acid, HETE, and HPETE significantly increase both K(+)-stimulated release of [3H]glutamate and [3H]inositol labelling of inositol phosphates in synaptosomes, whereas other biologically important fatty acids (oleic, palmitic, and stearic) failed to induce a similar response. The findings of these experiments are consistent with the hypothesis that arachidonic acid, HETE, or HPETE may play the role of a retrograde messenger in LTP.
Collapse
|
|
35 |
111 |
16
|
Vargaftig BB, Singer M. Leukotrienes mediate murine bronchopulmonary hyperreactivity, inflammation, and part of mucosal metaplasia and tissue injury induced by recombinant murine interleukin-13. Am J Respir Cell Mol Biol 2003; 28:410-9. [PMID: 12654629 DOI: 10.1165/rcmb.2002-0032oc] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Interleukin (IL)-13 induces bronchopulmonary hyperreactivity (BHR), eosinophilic inflammation, and mucus accumulation in the murine airways. To investigate the potential role of leukotrienes (LT) in mediating these effects, we studied the ability of IL-13 to induce the expression of 5-lipoxygenase (5-LO), we compared the effects of IL-13 and of various leukotrienes on different biological parameters and the interference by the 5-LO inhibitor zileuton (orally, 50 mg/kg, 3 times a day for 3 days), and by some antagonists. The cysteinyl (Cys)-LTs LTC4, LTD4, LTE4, and LTB4, (1 microg/d for 3 d, instilled intratracheally) induced BHR, cell recruitment, fibroblast growth, and mucus production and release into the airways. After the intratracheal instillation of recombinant murine (rm) IL-13, Cys-LT increased in the bronchoalveolar lavage fluid (BALF) at 15 min, followed by lower amounts at 3-6 h. Zileuton inhibited LT production in the BALF, eosinophil and neutrophil sequestration in the lungs, and their passage into the BALF. Zileuton and the Cys-LT-receptor antagonist (ra) LY171883 or MK-571, or the LTB4-ra PH-163 (at 3-10, 5-15, and 10 mg/kg, respectively, administered intratracheally), inhibited BHR by recombinant murine IL-13. Airways mucus after recombinant murine IL-13-challenge was reduced by zileuton and by LY171883, MK-571, and PH-163. LT also induced the vascular endothelium remodelling and collagen deposition. Overall, our results demonstrate the major involvement of LT in the effects of IL-13 on the lung.
Collapse
|
|
22 |
93 |
17
|
Abstract
This review describes the aspects of leukotriene (LT) pharmacology and biology that are relevant to their important role in asthma. The biosynthesis and metabolism, including transcellular metabolism, of LTB4 and the cysteinyl-LTs (i.e. LTC4, LTD4 and LTE4) are described, and their transport is briefly outlined. The existence, distribution and pharmacological characterization of the receptors (BLT, CysLT1, CysLT2), as well as the transduction mechanisms triggered, are discussed in detail. We also describe their effects on airway smooth muscle tone, hyperresponsiveness and proliferation, on vascular tone and permeability, on mucus secretion, on neural fibers and inflammatory cell functions. Finally, the evidence supporting their role as asthma mediators is reviewed, including the effects of anti LT drugs (both biosynthesis inhibitors and receptor antagonists) in experimental and clinical asthma.
Collapse
|
Review |
24 |
89 |
18
|
Garcia C, Boyce BF, Gilles J, Dallas M, Qiao M, Mundy GR, Bonewald LF. Leukotriene B4 stimulates osteoclastic bone resorption both in vitro and in vivo. J Bone Miner Res 1996; 11:1619-27. [PMID: 8915769 DOI: 10.1002/jbmr.5650111105] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Upon activation, the enzyme 5-lipoxygenase converts arachidonic acid into principally three products, the peptidoleukotrienes, 5-hydroperoxyeicosatetraenoic acid (5-HETE) or the leukotriene B4. We have shown that the peptido-leukotrienes (known as LTC4, LTD4, or LTE4) and 5-HETE induce osteoclastic bone resorption and that receptors for LTD4 are present on isolated avian osteoclast-like cells. Here, we show the effects of the third metabolic product of the 5-lipoxygenase (5-LO) pathway of arachidonic acid metabolism, the leukotriene LTB4, on osteoclastic bone resorption both in vivo and in vitro. Because LTB4 production is increased in a number of inflammatory conditions, it may be an important contributor to the bone loss which occurs in these disorders. LTB4 increased osteoclastic bone resorption in vivo following local administration over the calvariae of normal mice and in vitro in organ cultures of neonatal mouse calvariae. When LTB4 was injected over the calvaria of mice, there was a significant increase in bone resorption, osteoclast numbers, and eroded surfaces. LTB4 also increased the formation of resorption lacunae by isolated neonatal rat osteoclasts. Greater potency was observed with LTB4 compared with the peptido-leukotriene LTD4. This is in contrast to prostaglandins of the E series, which are reported to inhibit isolated osteoclasts. Experiments using marrow cultures suggest that LTB4 stimulates bone resorption in part by enhancing the formation of osteoclasts.
Collapse
|
Comparative Study |
29 |
88 |
19
|
Nonaka Y, Hiramoto T, Fujita N. Identification of endogenous surrogate ligands for human P2Y12 receptors by in silico and in vitro methods. Biochem Biophys Res Commun 2005; 337:281-8. [PMID: 16185654 DOI: 10.1016/j.bbrc.2005.09.052] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Accepted: 09/09/2005] [Indexed: 10/25/2022]
Abstract
Endogenous ligands acting on a human P2Y12 receptor, one of the G-protein coupled receptors, were searched by in silico screening against our own database, which contains more than 500 animal metabolites. The in silico screening using the docking software AutoDock resulted in selection of cysteinylleukotrienes (CysLTs) and 5-phosphoribosyl 1-pyrophosphate (PRPP), with high free energy changes, in addition to the known P2Y12 ligands such as 2MeSADP and ADP. These candidates were subjected to an in vitro Ca2+ assay using the CHO cells stably expressing P2Y12-G16alpha fusion proteins. We found that CysLTE4 and PRPP acted on the P2Y12 receptor as agonists with the EC50 values of 1.3 and 7.8 nM, respectively. Furthermore, we analyzed the phylogenetic relationship of the P2Y, P2Y-like, and CysLT receptors based on sequence alignment followed by evolutionary analyses. The analyses showed that the P2Y12, P2Y13, P2Y14, GPR87, CysLT-1, and CysLT-2 receptors formed a P2Y-related receptor subfamily with common sequence motifs in the transmembrane regions.
Collapse
|
|
20 |
88 |
20
|
Parameswaran K, Cox G, Radford K, Janssen LJ, Sehmi R, O'Byrne PM. Cysteinyl leukotrienes promote human airway smooth muscle migration. Am J Respir Crit Care Med 2002; 166:738-42. [PMID: 12204874 DOI: 10.1164/rccm.200204-291oc] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cysteinyl leukotrienes promote airway smooth muscle (ASM) contraction and proliferation. Little is known about their role in ASM migration. We investigated this using cultured human ASMs (between the second and fifth passages) obtained from the large airways of resected nonasthmatic lung. Platelet-derived growth factor-BB (1 ng/ml) promoted significant (3.5-fold) ASM migration of myocytes across collagen-coated 8- micro m polycarbonate membranes in Transwell culture plates. Leukotriene E(4) (10(-7), 10(-8), 10(-9) M) did not demonstrate a chemotactic effect; it did promote chemokinesis. Priming by leukotriene E(4) (10(-7) M) significantly augmented the directional migratory response to platelet-derived growth factor (1.5-fold, p < 0.05). This was blocked by montelukast (10(-6) M), demonstrating the effect to be mediated by the cysteinyl leukotriene receptor. The "priming effect" was also partially attenuated by prostaglandin E(2) (10(-7) M). Whereas both the chemokinetic and the chemotactic "primed" responses were equally attenuated by a p38 mitogen-activated protein kinase inhibitor (SB203580, 25 micro M) and by a Rho-kinase inhibitor (Y27632, 10 micro M), the chemotactic response showed greater inhibition than chemokinesis by a phosphatidylinositol-3 kinase inhibitor (LY294002, 50 micro M). These experiments suggest that cysteinyl leukotrienes play an augmentary role in human ASM migration. The phosphatidylinositol-3 kinase pathway is a key signaling mechanism in the chemotactic migration of ASM cells in response to cysteinyl leukotrienes.
Collapse
|
Comparative Study |
23 |
85 |
21
|
Coulon L, Calzada C, Moulin P, Véricel E, Lagarde M. Activation of p38 mitogen-activated protein kinase/cytosolic phospholipase A2 cascade in hydroperoxide-stressed platelets. Free Radic Biol Med 2003; 35:616-25. [PMID: 12957654 DOI: 10.1016/s0891-5849(03)00386-1] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
12-Hydroperoxy-eicosatetraenoic acid (12-HpETE), the main hydroperoxide formed in platelets from arachidonic acid (AA) by 12-lipoxygenase, has been shown to increase the sensitivity of platelets to agonists resulting in increased aggregation. The aim of the present study was to determine the direct effect of low concentrations of 12-HpETE on the signaling pathways leading to AA release from membrane phospholipids and thromboxane A2 (TxA2) formation. Exogenous 12-HpETE activated platelet p38 mitogen-activated protein kinase (p38 MAPK), as assessed by its phosphorylation, at a concentration as low as 100 nM and was much more potent than hydrogen peroxide. Moreover, the incubation of platelets with 100 nM 12-HpETE for 2 min led to the phosphorylation of cytosolic phospholipase A2 (cPLA2). It was associated with a significant decrease in the concentration of AA esterified in phospholipids and an increased concentration of thromboxane B2, the stable catabolite of TxA2. Additionally, decreasing glutathione peroxidase activity pharmacologically favored endogenous 12-HpETE formation and led to an increase in phosphorylated p38 MAPK, while a thiol-reducing agent such as N-acetyl-cysteine fully prevented it. Finally, significant activation of p38 MAPK was also observed in platelets from type 2 diabetic patients with mild hyperglycemia. In conclusion, our data provide a new insight into the mechanism of 12-HpETE-induced platelet priming, suggesting that hydroperoxide-induced p38 MAPK activation could play a relevant role in the exacerbated platelet activation associated with oxidative stress as found in diabetes.
Collapse
|
|
22 |
85 |
22
|
Serezani CH, Perrela JH, Russo M, Peters-Golden M, Jancar S. Leukotrienes are essential for the control of Leishmania amazonensis infection and contribute to strain variation in susceptibility. THE JOURNAL OF IMMUNOLOGY 2006; 177:3201-8. [PMID: 16920959 DOI: 10.4049/jimmunol.177.5.3201] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Leukotrienes (LTs) are known to be produced by macrophages when challenged with Leishmania, but it is not known whether these lipid mediators play a role in host defense against this important protozoan parasite. In this study, we investigated the involvement of LTs in the in vitro and in vivo response to Leishmania amazonensis infection in susceptible (BALB/c) and resistant (C3H/HePAS) mice. Pharmacologic or genetic deficiency of LTs resulted in impaired leishmanicidal activity of peritoneal macrophages in vitro. In contrast, addition of LTB4 increased leishmanicidal activity and this effect was dependent on the BLT1 receptor. LTB4 augmented NO production in response to L. amazonensis challenge, and studies with a NO synthesis inhibitor revealed that NO was critical for the enhancement of macrophage leishmanicidal activity. Interestingly, macrophages from resistant mice produced higher levels of LTB4 upon L. amazonensis challenge than did those from susceptible mice. In vivo infection severity, as assessed by footpad swelling following s.c. promastigote inoculation, was increased when endogenous LT synthesis was abrogated either pharmacologically or genetically. Taken together, these results for the first time reveal an important role for LTB4 in the protective response to L. amazonensis, identify relevant leishmanicidal mechanisms, and suggest that genetic variation in LTB4 synthesis might influence resistance and susceptibility patterns to infection.
Collapse
|
Research Support, Non-U.S. Gov't |
19 |
80 |
23
|
Canals S, Casarejos MJ, de Bernardo S, Rodríguez-Martín E, Mena MA. Nitric oxide triggers the toxicity due to glutathione depletion in midbrain cultures through 12-lipoxygenase. J Biol Chem 2003; 278:21542-9. [PMID: 12679339 DOI: 10.1074/jbc.m213174200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glutathione (GSH) depletion is the earliest biochemical alteration shown to date in brains of Parkinson's disease patients. However, data from animal models show that GSH depletion by itself is not sufficient to induce nigral degeneration. We have previously shown that non-toxic inhibition of GSH synthesis with l-buthionine-(S,R)-sulfoximine in primary midbrain cultures transforms a nitric oxide (NO) neurotrophic effect, selective for dopamine neurons, into a toxic effect with participation of guanylate cyclase (GC) and cGMP-dependent protein kinase (PKG) (Canals, S., Casarejos, M. J., de Bernardo, S., Rodríguez-Martín, E., and Mena, M. A. (2001) J. Neurochem. 79, 1183-1195). Here we demonstrate that arachidonic acid (AA) metabolism through the 12-lipoxygenase (12-LOX) pathway is also central for this GSH-NO interaction. LOX inhibitors (nordihydroguaiaretic acid and baicalein), but not cyclooxygenase (indomethacin) or epoxygenase (clotrimazole) ones, prevent cell death in the culture, even when added 10 h after NO treatment. Furthermore, the addition of AA to GSH-depleted cultures precipitates a cell death process that is indistinguishable from that initiated by NO in its morphology, time course, and 12-LOX, GC, and PKG dependence. The first AA metabolite through the 12-LOX enzyme, 12-hydroperoxyeicosatetraenoic acid, induces cell death in the culture, and its toxicity is greatly enhanced by GSH depletion. In addition we show that if GSH synthesis inhibition persists for up to 4 days without any additional treatment, it will induce a cell death process that also depends on 12-LOX, GC, and PKG activation. In this study, therefore, we show that the signaling pathway AA/12-LOX/12-HPETE/GC/PKG may be important in several pathologies in which GSH decrease has been documented, such as Parkinson's disease. The potentiating effect of NO over such a signaling pathway may be of relevance as part of the cascade of events leading to and sustaining nerve cell death.
Collapse
|
|
22 |
79 |
24
|
Knani J, Campbell A, Enander I, Peterson CG, Michel FB, Bousquet J. Indirect evidence of nasal inflammation assessed by titration of inflammatory mediators and enumeration of cells in nasal secretions of patients with chronic rhinitis. J Allergy Clin Immunol 1992; 90:880-9. [PMID: 1334102 DOI: 10.1016/0091-6749(92)90460-j] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Pathophysiologic mechanisms of perennial rhinitis are poorly understood. The characterization of inflammation was studied in nasal lavage of patients with perennial rhinitis by the enumeration of cells involved in the allergic inflammation and the measurement of six mediators released in nasal secretions to determine whether some mediators were relevant for the etiologic diagnosis and the occurrence of symptoms. Ten healthy subjects and 57 patients with perennial rhinitis were placed into four groups according to the symptoms they presented at the time of the study and the origin of the allergy. Allergy was characterized by the history, skin prick tests to standardized allergens, and RAST. Eosinophil protein X (EPX), tryptase, histamine, myeloperoxidase, prostaglandin D2, and leukotriene C4/D4 (LTC4/D4) were measured in nasal lavage by enzyme assay or radioimmunoassay. Eosinophils and neutrophils were enumerated after cytocentrifugation of the lavage fluid and May Grunwald Giemsa staining. Tryptase, myeloperoxidase and EPX but not histamine levels were increased in all four patient groups. Eosinophils, LTC4/D4, and prostaglandin D2 were significantly (p < 0.001, p < 0.03, and p < 0.01) increased in allergic and symptomatic patients. EPX was significantly increased in symptomatic allergic and nonallergic patients. This study suggests the involvement of mast cells, neutrophils, and eosinophils, but the latter cells appear to have a more prominent role. The importance of EPX and LTC4/D4 in the characterization of chronic symptomatic rhinitis was also observed.
Collapse
|
|
33 |
79 |
25
|
Meghji S, Sandy JR, Scutt AM, Harvey W, Harris M. Stimulation of bone resorption by lipoxygenase metabolites of arachidonic acid. PROSTAGLANDINS 1988; 36:139-49. [PMID: 2847250 DOI: 10.1016/0090-6980(88)90301-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have studied the effect of leukotrienes, (LT): B4, C4, D4 and E4 and the hydroxyeicosatetraenoic acids (HETEs) 5-HETE and 12-HETE on bone resorption in vitro. Resorption was measured by colorimetric assay of calcium released from neonatal mouse calvaria maintained in organ culture for 72h. All the LTs and HETEs stimulated bone resorption, with optimum responses at picomolar or nanomolar concentrations. The responses were biphasic, with a decreasing effect at higher concentrations. In contrast, prostaglandin E2 (PGE2) stimulated resorption only at 10nM and above. Indomethacin partially inhibited resorption by LTB4, LTC4 and LTD4, but did not affect resorption stimulated by LTE4, 5-HETE and 12-HETE. These results indicate that lipoxygenase products of arachidonic acid are highly potent bone resorbing factors and may play an important role in the localised bone loss associated with inflammatory lesions.
Collapse
|
|
37 |
78 |