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Wang Z, Hazen J, Jia X, Org E, Zhao Y, Osborn LJ, Nimer N, Buffa J, Culley MK, Krajcik D, van den Born BJH, Zwinderman K, Levison BS, Nieuwdorp M, Lusis AJ, DiDonato JA, Hazen SL. The Nutritional Supplement L-Alpha Glycerylphosphorylcholine Promotes Atherosclerosis. Int J Mol Sci 2021; 22:13477. [PMID: 34948275 PMCID: PMC8708068 DOI: 10.3390/ijms222413477] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 01/14/2023] Open
Abstract
L-alpha glycerylphosphorylcholine (GPC), a nutritional supplement, has been demonstrated to improve neurological function. However, a new study suggests that GPC supplementation increases incident stroke risk thus its potential adverse effects warrant further investigation. Here we show that GPC promotes atherosclerosis in hyperlipidemic Apoe-/- mice. GPC can be metabolized to trimethylamine N-oxide, a pro-atherogenic agent, suggesting a potential molecular mechanism underlying the observed atherosclerosis progression. GPC supplementation shifted the gut microbial community structure, characterized by increased abundance of Parabacteroides, Ruminococcus, and Bacteroides and decreased abundance of Akkermansia, Lactobacillus, and Roseburia, as determined by 16S rRNA gene sequencing. These data are consistent with a reduction in fecal and cecal short chain fatty acids in GPC-fed mice. Additionally, we found that GPC supplementation led to an increased relative abundance of choline trimethylamine lyase (cutC)-encoding bacteria via qPCR. Interrogation of host inflammatory signaling showed that GPC supplementation increased expression of the proinflammatory effectors CXCL13 and TIMP-1 and activated NF-κB and MAPK signaling pathways in human coronary artery endothelial cells. Finally, targeted and untargeted metabolomic analysis of murine plasma revealed additional metabolites associated with GPC supplementation and atherosclerosis. In summary, our results show GPC promotes atherosclerosis through multiple mechanisms and that caution should be applied when using GPC as a nutritional supplement.
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Affiliation(s)
- Zeneng Wang
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
| | - Jennie Hazen
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Xun Jia
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Elin Org
- Estonian Genome Centre, Institute of Genomics, University of Tartu, 51010 Tartu, Estonia;
| | - Yongzhong Zhao
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Lucas J. Osborn
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
| | - Nisreen Nimer
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Jennifer Buffa
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Miranda K. Culley
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Daniel Krajcik
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Bert-Jan H. van den Born
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (B.-J.H.v.d.B.); (K.Z.); (M.N.)
| | - Koos Zwinderman
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (B.-J.H.v.d.B.); (K.Z.); (M.N.)
| | - Bruce S. Levison
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
| | - Max Nieuwdorp
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (B.-J.H.v.d.B.); (K.Z.); (M.N.)
| | - Aldons J. Lusis
- Department of Medicine, Division of Cardiology, University of California, Los Angeles, CA 90095, USA;
| | - Joseph A. DiDonato
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
| | - Stanley L. Hazen
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA; (J.H.); (X.J.); (Y.Z.); (L.J.O.); (N.N.); (J.B.); (M.K.C.); (D.K.); (J.A.D.); (S.L.H.)
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
- Department of Cardiovascular Medicine, Heart, Vascular and Thoracic Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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Recent progress on phospholipases: different sources, assay methods, industrial potential and pathogenicity. Appl Biochem Biotechnol 2011; 164:991-1022. [PMID: 21302142 DOI: 10.1007/s12010-011-9190-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Accepted: 01/25/2011] [Indexed: 10/18/2022]
Abstract
Significant studies on phospholipases optimization, characterization, physiological role and industrial potential have been conducted worldwide. Some of them have been directed for biotechnological advances such as gene discovery and functional enhancement by protein engineering. Others reported phospholipases as virulence factor and major cause of pathophysiological effects. A general overview on phospholipase is needed for the identification of new reliable and efficient phospholipase, which would be potentially used in number of industrial and medical applications. Phospholipases catalyse the hydrolysis of one or more ester and phosphodiester bonds of glycerophospholipids. They vary in site of action on phospholipid which can be used industrially for modification/production of new phospholipids. Catalytically active phospholipase mainly use phosphatidylcholine as major substrate, but they can also show specificity with other phospholipids. Several accurate phospholipase assay methods are known, but a rapid and reliable method for high-throughput screening is still a challenge for efficient supply of superior phospholipases and their practical applications. Major application of phospholipase is in industries like oil refinery, health food manufacturing, dairy, cosmetics etc. All types of phospholipases can be involved as virulence factor. They can also be used as diagnostic markers for microbial infection. The importance of phospholipase in virulence is proven and inhibitors of the enzyme can be used as candidate for preventing the associated disease.
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van Rossum GSAT, Drummen GPC, Verkleij AJ, Post JA, Boonstra J. Activation of cytosolic phospholipase A2 in Her14 fibroblasts by hydrogen peroxide: a p42/44MAPK-dependent and phosphorylation-independent mechanism. Biochim Biophys Acta Mol Cell Biol Lipids 2004; 1636:183-95. [PMID: 15164766 DOI: 10.1016/j.bbalip.2003.12.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2003] [Accepted: 12/03/2003] [Indexed: 11/24/2022]
Abstract
Reactive oxygen species (ROS) have been implicated in the pathogenesis of diseases as well as various normal cellular processes. It has been suggested that ROS function as mediators of signal transduction, given that they can mimic growth factor-induced signaling. The ROS H2O2 has been reported to activate phospholipase A2 (PLA2) and, therefore, we investigated if and through which pathway ROS activate cytosolic PLA2 (cPLA2) in Her14 fibroblasts. cPLA2 was activated concentration-dependently by H2O2 in a transient manner. In addition, the lipophilic cumene hydroperoxide was shown to induce cPLA2 activity in the same manner. H2O2-induced cPLA2 activity in Her14 cells was partially phosphorylation-dependent, which was mediated through the Raf-MEK-p42/44(MAPK) pathway and occurred partially through a phosphorylation-independent mechanism. ROS can lead to changes in the (micro) viscosity of membranes due to the presence oxidized lipids, thereby increasing the substrate availability for cPLA2. In support of this, treatment of Her14 cells with H2O2 induced lipid peroxidation time-dependently as determined from degradation of lipid arachidonate and linoleate and the formation of aldehydic degradation products. Furthermore, H2O2 induced translocation of cPLA2 to the membrane fraction in a calcium-independent fashion, with a concomitant increase in cPLA2 activity. Collectively, the results suggest that oxidative stress-induced cPLA2 activity is partially phosphorylation-dependent and is further increased due to increased substrate availability by the action of ROS on membranes.
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Affiliation(s)
- Gerda S A T van Rossum
- Department of Molecular Cell Biology, Institute and Graduate School of Biomembranes, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
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Tannaes T, Dekker N, Bukholm G, Bijlsma JJ, Appelmelk BJ. Phase variation in the Helicobacter pylori phospholipase A gene and its role in acid adaptation. Infect Immun 2001; 69:7334-40. [PMID: 11705905 PMCID: PMC98819 DOI: 10.1128/iai.69.12.7334-7340.2001] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Previously, we have shown that Helicobacter pylori can spontaneously and reversibly change its membrane lipid composition, producing variants with low or high content of lysophospholipids. The "lyso" variant contains a high percentage of lysophospholipids, adheres better to epithelial cells, and releases more proteins such as urease and VacA, compared to the "normal" variant, which has a low content of lysophospholipids. Prolonged growth of the normal variant at pH 3.5, but not under neutral conditions, leads to enrichment of lyso variant colonies, suggesting that the colony switch is relevant to acid adaptation. In this study we show that the change in membrane lipid composition is due to phase variation in the pldA gene. A change in the (C) tract length of this gene results in reversible frameshifts, translation of a full-length or truncated pldA, and the production of active or inactive outer membrane phospholipase A (OMPLA). The role of OMPLA in determining the colony morphology was confirmed by the construction of an OMPLA-negative mutant. Furthermore, variants with an active OMPLA were able to survive acidic conditions better than variants with the inactive form. This explains why the lyso variant is selected at low pH. Our studies demonstrate that phase variation in the pldA gene, resulting in an active form of OMPLA, is important for survival under acidic conditions. We also demonstrated the active OMPLA genotype in fresh isolates of H. pylori from patients referred to gastroscopy for dyspepsia.
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Affiliation(s)
- T Tannaes
- Institute of Medical Microbiology, University of Oslo, Oslo, Norway.
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van Rossum GS, Vlug AS, van den Bosch H, Verkleij AJ, Boonstra J. Cytosolic phospholipase A(2) activity during the ongoing cell cycle. J Cell Physiol 2001; 188:321-8. [PMID: 11473358 DOI: 10.1002/jcp.1123] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cytosolic phospholipase A(2) (cPLA(2)) is of special interest because it selectively releases arachidonic acid from membrane phospholipids. Arachidonic acid has been implicated to play an important role in various cellular responses. Recently arachidonic acid release and prostaglandin synthesis have been shown to be cell cycle dependent and therefore the activity of cPLA(2) during the ongoing cell cycle was investigated, using the mitotic shake off method for cell synchronisation. cPLA(2) activity was high in mitotic cells and decreased rapidly in the early G1 phase. A strong increase in activity was measured following the G1/S transition in both neuroblastoma and Chinese hamster ovary cells. The changes in activity were not due to a difference in cPLA(2) expression but due to phosphorylation of cPLA(2). Phosphorylation of cPLA(2) occurs through MAPK since the use of a specific MAPK kinase inhibitor and serum depletion of synchronised cells inhibited cPLA(2) activity.
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Affiliation(s)
- G S van Rossum
- Department of Molecular Cell Biology, Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands
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6
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van Rossum GS, Klooster R, van den Bosch H, Verkleij AJ, Boonstra J. Phosphorylation of p42/44(MAPK) by various signal transduction pathways activates cytosolic phospholipase A(2) to variable degrees. J Biol Chem 2001; 276:28976-83. [PMID: 11390384 DOI: 10.1074/jbc.m101361200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arachidonic acid has been implicated to play a role in physiological and pathophysiological processes and is selectively released by the 85-kDa cytosolic phospholipase A(2) (cPLA(2)). The activity of cPLA(2) is regulated by calcium, translocating the enzyme to its substrate, and by phosphorylation by a mitogen-activated protein kinase (MAPK) family member and a MAPK-activated protein kinase. In this study, the signal transduction pathways in growth factor-induced phosphorylation of p42/44(MAPK) and cPLA(2) activation were investigated in Her14 fibroblasts. p42/44(MAPK) in response to epidermal growth factor was not only phosphorylated via the Raf-MEK pathway but mainly through protein kinase C (PKC) or a related or unrelated kinase in which the phosphorylated p42/44(MAPK) corresponded with cPLA(2) activity. Serum-induced phosphorylation of p42/44(MAPK) also corresponded with cPLA(2) activity but is predominantly mediated via Raf-MEK and partly through PKC or a related or unrelated kinase. In contrast, activation of PKC by phorbol ester did not result in increased cPLA(2) activity, while p42/44(MAPK) is phosphorylated, mainly via Raf-MEK and through MEK. Moreover, p42/44(MAPK) phosphorylation is present in quiescent and proliferating cells, and p42/44(MAPK) is entirely phosphorylated via Raf-MEK, but it only corresponds to cPLA(2) activity in the former cells. Collectively, these data show that p42/44(MAPK) in proliferating, quiescent, and stimulated cells is phosphorylated by various signal transduction pathways, suggesting the activation of different populations of p42/44(MAPK) and cPLA(2).
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Affiliation(s)
- G S van Rossum
- Department of Molecular Cell Biology, Utrecht University, Utrecht 3584 CH, The Netherlands.
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Aarsman AJ, Neys FW, van der Helm HA, Kuypers FA, van den Bosch H. Sera of patients suffering from inflammatory diseases contain group IIA but not group V phospholipase A(2). BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1502:257-63. [PMID: 11040450 DOI: 10.1016/s0925-4439(00)00050-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
During recent years, the high phospholipase A(2) (PLA(2)) concentrations at sites of inflammation and in circulation in several life-threatening diseases, such as sepsis, multi-organ dysfunction and acute respiratory distress syndrome, has generally been ascribed to the non-pancreatic group IIA PLA(2). Recently the family of secreted low molecular mass PLA(2) enzymes has rapidly expanded. In some cases, a newly described enzyme appeared to be cross-reactive with antibodies against the group IIA enzyme. For this reason, reports describing the expression of group IIA PLA(2) during inflammatory conditions need to be reevaluated. Here we describe the identification of the PLA(2) activity in sera of acute chest syndrome patients and in sera of trauma victims. In both cases, the PLA(2) activity was identified as group IIA. This classification was based upon cross-reactivity with monoclonal antibodies against group IIA PLA(2) which do not recognize the recombinant human group V enzyme. Moreover, purification of the enzymatic activity from the two sera followed by N-terminal amino acid sequence analyses revealed only the presence of group IIA enzyme.
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Affiliation(s)
- A J Aarsman
- Center for Biomembranes and Lipid Enzymology, Utrecht University, Utrecht, The Netherlands.
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Pérez-Gilabert M, Veldink GA, Vliegenthart JF. Oxidation of dilinoleoyl phosphatidylcholine by lipoxygenase 1 from soybeans. Arch Biochem Biophys 1998; 354:18-23. [PMID: 9633593 DOI: 10.1006/abbi.1998.0673] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Soybean lipoxygenase-1 is able to oxidize dilinoleoyl phosphatidylcholine at pH 7.5 and 10. The reaction could be followed spectrophotometrically from the increase of the absorbance at 234 nm. An intermediate product and a final product were detected. In the intermediate product only one of the linoleoyl chains (either sn1 or sn2) was oxidized. In the final product, both linoleic acid units were converted into hydroperoxides. Apparently, oxidation of one of the linoleoyl chains leads to a disruption of the structure of the mixed bilayer disk, making the remaining fatty acid unit more accessible to the action of the enzyme. The specificity of lipoxygenase-1 when acting on phospholipids is not affected by pH. The exclusive production of 13-hydroperoxyoctadecadienoic acid derivatives of dilinoleoyl phosphatidylcholine at pH 7.5 and 10 may result from the blockage of the carboxylic end of the fatty acid.
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Affiliation(s)
- M Pérez-Gilabert
- Bijvoet Center for Biomolecular Research, Department of Bio-organic Chemistry, Utrecht University, The Netherlands
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Huwiler A, Staudt G, Kramer RM, Pfeilschifter J. Cross-talk between secretory phospholipase A2 and cytosolic phospholipase A2 in rat renal mesangial cells. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1348:257-72. [PMID: 9366243 DOI: 10.1016/s0005-2760(97)00073-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Incubation of rat glomerular mesangial cells with potent proinflammatory cytokines like interleukin 1beta, (IL- 1beta) triggers the expression of a non-pancreatic secretory phospholipase A2 (sPLA2) and increases the formation of prostaglandin E2. We show here that sPLA2 acts in an autocrine fashion on mesangial cells and induces a rapid activation of protein kinase C (PKC) isoenzymes delta and epsilon and of p42 mitogen-activated protein kinase (MAPK), two putative activators of cytosolic phospholipase A2 (cPLA2). sPLA2 also activates Raf-1 kinase in mesangial cells which integrates the signals coming from PKC for further processing along the MAPK cascade. Subsequently a phosphorylation and activation of cPLA2 is observed, thus arguing for a cross-talk between the two classes of PLA2. Pretreatment of cells with either the highly specific PKC inhibitor Ro-318220 or the highly specific MAPK kinase (MEK) inhibitor PD 98059 completely blocked the sPLA2-induced cPLA2 activation, indicating that both kinases are essential for the cross-talk between the two types of PLA2. The effect of sPLA2 is mimicked by lysophosphatidylcholine (LPC), a reaction product of sPLA2 activity. LPC stimulates PKC-epsilon, Raf-1 kinase and MAPK activation as well as cPLA2 activation with a subsequent increase in arachidonic acid release from mesangial cells. These data suggest that sPLA2 by cleaving membrane phospholipids and generating LPC and other lysophospholipids activates cPLA2 via the PKC/Raf-1/MAPK signalling pathway. Hence a network of interactions between different PLA2s is operative in mesangial cells and may contribute to the progression of glomerular inflammatory processes.
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Affiliation(s)
- A Huwiler
- Department of Pharmacology, Biozentrum, University of Basel, Switzerland
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Vervoordeldonk MJ, van Rossum GS, Sanchez RM, Neys FW, van den Bosch H. Half-life of interleukin-1 beta-induced group II phospholipase A2 in rat mesangial cells. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1355:315-22. [PMID: 9061002 DOI: 10.1016/s0167-4889(96)00142-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Group II phospholipase A2 (sPLA2) has been implicated as an important agent involved in a number of inflammatory processes. Potent pro-inflammatory cytokines, such as interleukin-1 beta (IL-1 beta) and tumor necrosis factor (TNF) have been found to induce sPLA2 synthesis and release from many cell types among which mesangial cells. Although considerable research has been devoted to unravelling the mechanisms underlying the induction of sPLA2 not much is known about the time scale at which the cytokine elicited signals for sPLA2 induction persist in target cells. In this study we addressed that question by using rat renal mesangial cells as a model target cell. We found that after removal of IL-1 beta from the culture medium, the induced-sPLA2 synthesis continues at gradually decreasing rates for approximately 8 h. This is accompanied by a decrease in sPLA2 mRNA levels. Furthermore, with pulse-chase experiments we investigated the half-life of sPLA2 disappearance from the cells. This disappearance was found to be biphasic. A rapidly disappearing pool, constituting approx. 74% of the total, exhibited a half-life of 1.6 +/- 0.2 h. The remaining pool of the induced enzyme was much more stable and its level remained constant for at least 24 h. Analysis of the appearance of newly synthesized enzyme in the culture medium indicated this process to be completed in an hour.
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11
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Vervoordeldonk MJ, Pineda Torra IM, Aarsman AJ, van den Bosch H. Aspirin inhibits expression of the interleukin-1beta-inducible group II phospholipase A2. FEBS Lett 1996; 397:108-12. [PMID: 8941724 DOI: 10.1016/s0014-5793(96)01148-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) clearly inhibit the synthesis and release of prostaglandins. However, these actions are not sufficient to explain all the anti-inflammatory effects of these drugs. Recently, it has been shown that aspirin and sodium salicylate inhibit the activation of the transcription factor NF-kappaB. Group II phospholipase A2 (sPLA2) is expressed in rat glomerular mesangial cells upon exposure to the inflammatory cytokine interleukin-1beta (IL-1beta) and this induction is attenuated by the NF-kappaB inhibitor pyrrolidine dithiocarbamate (PDTC). We now report that aspirin inhibits the IL-1beta-induced sPLA2 activity in rat mesangial cells in a dose-dependent manner. The IC50 value of aspirin for sPLA2 inhibition was 6.5 mM. This decrease in sPLA2 activity was not due to direct inhibition of enzymatic activity but rather to the fact that aspirin inhibits the expression of IL-1beta-induced sPLA2 protein and mRNA. Furthermore, by electrophoretic mobility shift analysis we demonstrate reduced DNA binding of the nuclear factor kappaB, an essential component of the IL-1beta-dependent upregulation of sPLA2 gene transcription, after treatment of the cells with aspirin. The study described in this report indicates that the inhibition of sPLA2 expression as induced by pro-inflammatory cytokines potentially represents an additional mechanism of action for aspirin.
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Affiliation(s)
- M J Vervoordeldonk
- Centre for Biomembranes and Lipid Enzymology, Institute for Biomembranes, Utrecht, The Netherlands
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12
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Vervoordeldonk MJ, Schalkwijk CG, Pfeilschifter J, van den Bosch H. Effects of dexamethasone and transforming growth factor-beta 2 on group II phospholipase A2 mRNA and activity levels in interleukin 1 beta- and forskolin-stimulated mesangial cells. Biochem J 1996; 315 ( Pt 2):435-41. [PMID: 8615811 PMCID: PMC1217214 DOI: 10.1042/bj3150435] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The expression of 14 kDa group II phospholipase A2 [also referred to as secretory PLA2 (sPLA2)] is induced in rat glomerular mesangial cells by exposure to inflammatory cytokines and forskolin, a cAMP elevating agent. Previously we have shown that dexamethasone and transforming growth factor-beta 2 (TGF-beta 2) suppress sPLA2 protein synthesis and enzyme activity induced by cytokines and forskolin. The regulation of sPLA2 by pro-inflammatory cytokines suggests that the enzyme may play a role in glomerular inflammatory reactions. In order to understand the regulation of sPLA, in more detail, we investigated whether dexamethasone and TGF-beta 2 also suppress sPLA, mRNA after its induction by either interleukin-1 beta (IL-1 beta) or forskolin. We found that IL-1 beta-induced sPLA2 mRNA in rat mesangial cells is not down-regulated by pretreatment of the cells with dexamethasone, even at a concentration of 10 microM, which dramatically decreases sPLA2 protein levels and activity. Metabolic labelling experiments indicated that the decreased sPLA2 levels under these conditions can be explained by inhibition of the rate of sPLA2 synthesis from the elevated mRNA levels. In contrast, the forskolin-induced elevation of sPLA, mRNA is inhibited by dexamethasone in a concentration-dependent manner. Likewise, TGF-beta 2 inhibits the elevation of sPLA, mRNAs induced by either IL-1 beta or forskolin. The decrease in sPLA2 mRNA caused by TGF-beta 2 corresponds with the decrease in sPLA2 enzyme levels and activity. These data suggest that cytokine- and forskolin-induced sPLA2, expression is tightly controlled via both transcriptional and post-transcriptional mechanisms. Furthermore, we show that pretreatment of mesangial cells with epidermal growth factor prior to stimulation with IL-1 beta or forskolin had no suppressing effect on sPLA2 levels or enzyme activity, as has been reported previously for osteoblasts.
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Schalkwijk CG, van der Heijden MA, Bunt G, Maas R, Tertoolen LG, van Bergen en Henegouwen PM, Verkleij AJ, van den Bosch H, Boonstra J. Maximal epidermal growth-factor-induced cytosolic phospholipase A2 activation in vivo requires phosphorylation followed by an increased intracellular calcium concentration. Biochem J 1996; 313 ( Pt 1):91-6. [PMID: 8546715 PMCID: PMC1216914 DOI: 10.1042/bj3130091] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The 85 kDa cytosolic phospholipase A2 (cPLA2) preferentially catalyses the hydrolysis of arachidonic acid from the sn-2 position of phospholipids. cPLA2 can be activated by extracellular stimuli such as thrombin, platelet-derived growth factor and epidermal growth factor (EGF): A full activation of cPLA2 requires an increase of intracellular Ca2+ concentration and phosphorylation on Ser-505 by mitogen-activated protein (MAP) kinase. Because EGF can provoke an increase in intracellular [Ca2+] ([Ca2+]i) and activation of MAP kinase, we investigated the role of these pathways in EGF-induced activation of cPLA2. Characterization of two cell lines expressing different numbers of EGF receptors (HERc13 and HER14) revealed that both were activating MAP kinase in response to EGF, but only HER14 responded with an increase in [Ca2+]i. In this study we used both cell lines as a tool to clarify the role of each pathway in cPLA2 activation. We show that EGF stimulates cPLA2 activity in both cell lines in vitro as measured in cytosolic fractions, but only in HER14 in vivo as measured by 3H release from cells prelabelled with [3H]arachidonic acid. This latter activation can be restored in HERc13 cells by the addition of the ionophore A23187. Interestingly, this effect is only observed when EGF stimulation precedes A23187 addition. The phosphorylation of MAP kinase, however, was identical under identical conditions. We conclude that a maximal cPLA2 activation by EGF requires both, and in this order: MAP kinase activation followed by a rise in [Ca2+]i concentration.
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Affiliation(s)
- C G Schalkwijk
- Centre for Biomembranes and Lipid Enzymology, Department of Molecular Cell Biology, Utrecht University, The Netherlands
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14
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Wolbink GJ, Schalkwijk C, Baars JW, Wagstaff J, van den Bosch H, Hack CE. Therapy with interleukin-2 induces the systemic release of phospholipase-A2. Cancer Immunol Immunother 1995; 41:287-92. [PMID: 8536274 PMCID: PMC11037621 DOI: 10.1007/bf01517216] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/1995] [Accepted: 10/12/1995] [Indexed: 02/06/2023]
Abstract
Therapy with interleukin-2 (IL-2) induces remissions in some forms of cancer. This treatment however, is accompanied by side-effects which, in part, may be mediated by the formation of eicosanoids and platelet-activating factor. We investigated the systemic release of phospholipase A2 (PLA2), a rate-limiting enzyme in the formation of these lipid mediators, in patients receiving IL-2. In a pilot study of 4 patients we observed an increase in PLA2 activity in serial plasma samples obtained during the first day after a bolus infusion of IL-2, which increase closely correlated with that of antigen levels of secretory phospholipase A2 (sPLA2) as measured by enzyme-linked immunosorbent assay (r = 0.92; P < 0.001). In 20 patients, receiving 12 x 10(6)-18 x 10(6) IU IL-2/m2, we then investigated the course of antigenic levels of sPLA2 in relation to those of the cytokines tumour necrosis factor alpha (TNF) and interleukin-6 (IL-6) (both cytokines may induce sPLA2 in vivo). From 4 h on, sPLA2 levels significantly increased, reaching a peak 24 h after the IL-2 infusion. Subsequent IL-2 infusions even induced a further increase of sPLA2. This increase of sPLA2 was presumably not due to a direct effect of IL-2 on, for example, hepatocytes, since this cytokine, in contrast to IL-1, IL-6, TNF and interferon gamma, was not able to induce the synthesis of sPLA2 by Hep G2 cells in vitro. Consistent with this, plasma levels of TNF and IL-6 in the patients rose, reaching peak levels before a zenith of sPLA2 occurred, i.e. at 2 h and 4 h after the start of the IL-2 infusion respectively. sPLA2 levels significantly correlated with the development of the side-effects increase in body weight (r = 0.49; P < 0.0001) and decrease in mean arterial blood pressure (r = 0.40; P < 0.0001). Moreover, maximum sPLA2 levels induced by IL-2 were higher in patients who had progressive disease after therapy than in patients who had stable disease or a partial response.
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Affiliation(s)
- G J Wolbink
- Central Laboratory of the Netherlands Red Cross Blood Transfusion, Amsterdam, The Netherlands
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15
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Schalkwijk CG, Spaargaren M, Defize LH, Verkleij AJ, van den Bosch H, Boonstra J. Epidermal growth factor (EGF) induces serine phosphorylation-dependent activation and calcium-dependent translocation of the cytosolic phospholipase A2. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 231:593-601. [PMID: 7649158 DOI: 10.1111/j.1432-1033.1995.tb20737.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Phospholipase A2 (PLA2) is a key enzyme in the release of arachidonic acid and subsequent production of eicosanoids, which play an important role in a variety of biological processes, including mitogenic signalling by epidermal growth factor (EGF). In a previous study [Spaargaren, M. et al. (1992) Biochem J. 287, 37-43] we identified the EGF-activated PLA2 as being similar to the recently cloned high-molecular-mass cytosolic phospholipase A2 (cPLA2). In the present study we demonstrate a rapid transient EGF-induced activation of this cPLA2 and an EGF-induced increase in phosphorylation of the cPLA2. The EGF-induced activation of cPLA2 is reversed upon phosphatase treatment showing phosphorylation-dependent activation of the cPLA2. No direct association of the cPLA2 to the EGF receptor was detected under conditions where such an association with phospholipase C-gamma was demonstrated. Phosphoamino acid analysis of this cPLA2 showed that EGF induced an increase in serine phosphorylation exclusively, no tyrosine phosphorylation being observed. EGF treatment of the cells resulted in a Ca(2+)-dependent translocation of the cPLA2 from the cytosol to the membrane fraction. This is due to an EGF-induced [Ca2+]i rise which is dependent on the influx of extracellular Ca2+ via voltage-independent Ca2+ channels. It is shown that the Ca(2+)-dependent association of cPLA2 to membranes does not require accessory membrane molecules.
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Affiliation(s)
- C G Schalkwijk
- Centre for Biomembranes and Lipid Enzymology, Utrecht University, The Netherlands
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16
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Schalkwijk CG, Vervoordeldonk M, Pfeilschifter J, van den Bosch H. Interleukin-1 beta-induced cytosolic phospholipase A2 activity and protein synthesis is blocked by dexamethasone in rat mesangial cells. FEBS Lett 1993; 333:339-43. [PMID: 8224206 DOI: 10.1016/0014-5793(93)80683-l] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Interleukin-1 beta induces gene expression and secretion of the secretory phospholipase A2 (sPLA2) and prostaglandin E2 (PGE2) release from rat mesangial cells. We have previously shown that prolonged treatment of rat mesangial cells with interleukin-1 beta (IL-1 beta) also enhances the cytosolic phospholipase A2 (cPLA2) activity. This effect of IL-1 beta on the cPLA2 activity is inhibited by actinomycin D and cycloheximide, indicating that both transcription and translation are involved. Here, we describe that IL-1 beta increases mRNA levels and protein synthesis of cPLA2 itself. In parallel with the effect of dexamethasone on the sPLA2, this glucocorticoid inhibits the IL-1 beta-enhanced cPLA2 activity as a result of the suppression of IL-1 beta-induced cPLA2 gene expression. This report suggests that the pro-inflammatory action of interleukin-1 beta may, in part, be mediated by its effects on cPLA2 activity.
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Affiliation(s)
- C G Schalkwijk
- Centre for Biomembranes and Lipid Enzymology, Utrecht, The Netherlands
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17
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Duan RD, Borgström B. Is there a specific lysophospholipase in human pancreatic juice? BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1167:326-30. [PMID: 8481395 DOI: 10.1016/0005-2760(93)90236-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The existence of a specific lysophospholipase in human pancreatic juice was evaluated. The proteins were separated by a series of chromatographic steps including Sephacryl S-200, cholate-Sepharose 4B, Sephadex G-100 and CM-Sephadex G-50. The enzyme activities against 1-palmitoyl lysolecithin (LL) as well as tributyrin (TB) and p-nitrophenyl butyrate (PNPB) were determined in all the fractions of these purification procedures. Enzyme activity against LL was always eluted in parallel with activities against TB and PNPB, and no unique activity against LL could be found. The specific activity against LL was 40-times lower than that against PNPB and 200-times lower than that against TB. It is concluded that there is no unique lysophospholipase in human pancreatic juice and that the hydrolysis of lysolecithin is most likely performed by carboxyl ester lipase.
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Affiliation(s)
- R D Duan
- Department of Medical and Physiological Chemistry, University of Lund, Sweden
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18
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Reynolds LJ, Hughes LL, Louis AI, Kramer RM, Dennis EA. Metal ion and salt effects on the phospholipase A2, lysophospholipase, and transacylase activities of human cytosolic phospholipase A2. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1167:272-80. [PMID: 8481388 DOI: 10.1016/0005-2760(93)90229-3] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Human cytosolic phospholipase A2 (cPLA2) is an arachidonic acid specific enzyme which may play a role in arachidonic acid release, eicosanoid production, and signal transduction. The PLA2 activity of this enzyme is stimulated by microM levels of Ca2+. Using a pure recombinant enzyme, we have confirmed that cPLA2 is not absolutely dependent on Ca2+, since Sr2+, Ba2+ and Mn2+ also gave full enzyme activity. Heavy metals, in contrast, inhibited enzyme catalysis suggesting the involvement of an essential cysteine residue. In the absence of Ca2+, high salt concentrations overcame the requirement for divalent metals, indicating that Ca2+ is not required for PLA2 catalytic activity. cPLA2 also displays a lysophospholipase (lyso PLA) activity with lysophosphatidylcholine micelles as a substrate. Unlike the PLA2 activity, the lyso PLA activity toward these micelles is not stimulated by Ca2+. However, upon the addition of glycerol or Triton X-100 to the assay, Ca2+ activation is observed, indicating that substrate presentation can affect the apparent Ca2+ dependence. Glycerol was found to be a potent stimulator of lyso PLA activity and specific activities up to 50 mumol min-1 mg-1 were observed. In addition to the PLA2 and lyso PLA activities, we report that cPLA2 displays a relatively low, CoA-independent transacylase activity which produces phosphatidylcholine from lysophosphatidylcholine substrate. The observation of this novel transacylase activity is consistent with the formation of an acyl-enzyme intermediate.
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Affiliation(s)
- L J Reynolds
- Department of Chemistry, University of California, San Diego, La Jolla 92093-0601
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19
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van der Klis FR, Wiersinga WM. PLA2 activity in rat liver nuclei. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1993; 25:575-9. [PMID: 8467957 DOI: 10.1016/0020-711x(93)90666-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
1. Subcellular fractions of rat liver were assayed for PLA2 activity. 2. The PLA2 assay measures the release of [3H]oleic acid from phospholipids, using labeled E. coli as substrate. 3. Nuclear fractions contained PLA2 activity, which was Ca2+ dependent and could not be explained from mitochondria, microsomal or plasma membrane contamination. 4. The Vmax value of nuclear PLA2 is 0.30 +/- 0.04 pmol oleic acid/min/mg protein; its Km value is 0.86 +/- 0.12 microM, similar to that of mitochondrial PLA2. 5. We conclude that rat liver nuclei contain PLA2 activity.
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Affiliation(s)
- F R van der Klis
- Department of Endocrinology, Academish Medisch Centrum, Amsterdam, The Netherlands
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20
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Schalkwijk CG, de Vet E, Pfeilschifter J, van den Bosch H. Interleukin-1 beta and transforming growth factor-beta 2 enhance cytosolic high-molecular-mass phospholipase A2 activity and induce prostaglandin E2 formation in rat mesangial cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 210:169-76. [PMID: 1446669 DOI: 10.1111/j.1432-1033.1992.tb17405.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Interleukin-1 beta induces gene expression and secretion of group-II phospholipase A2 and release of prostaglandin E2 from rat mesangial cells. The interleukin-1 beta-induced synthesis of group-II phospholipase A2 is prevented by transforming growth factor-beta 2, whereas transforming growth factor-beta 2 potentiated the interleukin-1 beta-evoked prostaglandin E2 production. Transforming growth factor-beta 2 itself did not induce synthesis of group-II phospholipase A2, although it stimulated prostaglandin E2 formation. Here we describe the effect of interleukin-1 beta and transforming growth factor-beta 2 on a cytosolic phospholipase A2 activity and prostaglandin E2 formation in rat mesangial cells. Based on the resistance to dithiothreitol and migration profiles on a Mono-Q anion-exchange column and a Superose 12 gel-filtration column, the cytosolic phospholipase A2 activity was assigned to a high-molecular-mass phospholipase A2. Measured with 1-stearoyl-2-[1-14C]arachidonoylglycero-phosphocholine as substrate, both interleukin-1 beta and transforming growth factor-beta 2 enhanced the high-molecular-mass phospholipase A2 activity. The stimulation of rat mesangial cells with interleukin-1 beta and transforming growth factor-beta 2 was time- and dose-dependent with maximal cytosolic phospholipase A2 activities at 10 nM and at 10 ng/ml respectively, after 24 h of stimulation. Under these conditions, interleukin-1 beta and transforming growth factor-beta 2 enhanced the cytosolic phospholipase A2 activity 2.2 +/- 0.6-fold and 2.5 +/- 0.6-fold, respectively. These results strongly suggest that an enhanced cytosolic high-molecular-mass phospholipase A2 activity is involved in the formation of prostaglandin E2 mediated by transforming growth factor-beta 2. Whether interleukin-1 beta induced group-II phospholipase A2 and/or interleukin-1 beta-enhanced cytosolic phospholipase A2 activity is involved in prostaglandin E2 formation in rat mesangial cells is discussed.
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Affiliation(s)
- C G Schalkwijk
- Centre for Biomembranes and Lipid Enzymology, Utrecht, The Netherlands
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21
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Spaargaren M, Wissink S, Defize LH, de Laat SW, Boonstra J. Characterization and identification of an epidermal-growth-factor-activated phospholipase A2. Biochem J 1992; 287 ( Pt 1):37-43. [PMID: 1417788 PMCID: PMC1133120 DOI: 10.1042/bj2870037] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The production of arachidonic acid (AA), which is involved in mitogenic signalling by epidermal growth factor (EGF), is most directly accomplished by the action of phospholipase A2 (PLA2). We demonstrate that EGF treatment of intact NEF cells rapidly activates a cytosolic PLA2, as measured in cell-free extracts by the release of radiolabelled AA from exogenously added 1-stearoyl-2-[1-14C]arachidonoyl phosphatidylcholine. Activation of PLA2 by EGF resulted in an enhanced Vmax. and no change in Km. The PLA2 activity was eluted in a single peak at 0.4 M-NaCl from a Mono Q anion-exchange column, and migrated with an approximate molecular mass of 70 kDa on a Superose 12 gel-filtration column. The EGF-activated PLA2 activity co-migrated with the basal PLA2 activity upon gel filtration, and persisted after partial purification, which indicates that the activation is due to a stable modification of the enzyme. The EGF-stimulated PLA2 is Ca(2+)-dependent, with maximal activity at micromolar concentrations of Ca2+, has a pH optimum at 9, associates with the particulate cell fraction in a Ca(2+)-dependent fashion, and is selective for arachidonoyl at the sn-2 position. These data demonstrate the EGF-induced activation of a PLA2, which is similar to a recently cloned high-molecular-mass AA-selective cytosolic PLA2, thus providing a link between EGF-receptor tyrosine kinase activation and AA metabolism.
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Affiliation(s)
- M Spaargaren
- Department of Molecular Cell Biology, University of Utrecht, The Netherlands
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22
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Schalkwijk C, Pfeilschifter J, Märki F, van den Bosch H. Interleukin-1 beta- and forskolin-induced synthesis and secretion of group II phospholipase A2 and prostaglandin E2 in rat mesangial cells is prevented by transforming growth factor-beta 2. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50357-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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23
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Munford R, Hunter J. Acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides, has phospholipase, lysophospholipase, diacylglycerollipase, and acyltransferase activities in vitro. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50207-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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24
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Masuda N, Kitamura N, Saito K. Primary structure of protein moiety of Penicillium notatum phospholipase B deduced from the cDNA. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 202:783-7. [PMID: 1722456 DOI: 10.1111/j.1432-1033.1991.tb16433.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Phospholipase B has not yet been well defined. The most important points about this enzyme are its relationships with lysophospholipase and phospholipase A1. As reported [Saito, K., Sugatani, J. & Okumura, T. (1991) Methods Enzymol. 197, 446-456], Penicillium notatum phospholipase B is a glycoprotein with a molecular mass of 95 kDa and intrinsic lysophospholipase and phospholipase B activities; however, by endogenous proteolytic modification, its phospholipase B activity is lost almost completely, whereas its lysophospholipase activity remains unchanged. A cDNA library of P. notatum was screened by hybridization with two synthetic oligodeoxyribonucleotide probes, which corresponds to two different pentapeptides of the enzyme. A hybridization-positive clone, pPLB18, was isolated and its nucleotide sequence was determined. The deduced amino acid sequence was quite different from that found previously. Therefore, we rescreened the cDNA library with a Sau3AI fragment derived from pPLB18 and isolated a new clone, pPLB15. Comparison of the nucleotide sequences of pPLB15 and pPLB18 revealed that pPLB18 contained an insertion sequence of 53 bp. Consequently, the reading frame was open downstream for 603 amino acid residues. From the assigned sequence, it was deduced that the limited proteolysis occurred between Leu175 and Asp176; eight cysteine residues and 16 potential N-glycosylation sites were also found. No amino acid sequence similarity was found with other proteins, including other phospholipases.
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Affiliation(s)
- N Masuda
- Department of Medical Chemistry, Kansai Medical University, Osaka, Japan
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25
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Schalkwijk C, Vervoordeldonk M, Pfeilschifter J, Märki F, van den Bosch H. Cytokine- and forskolin-induced synthesis of group II phospholipase A2 and prostaglandin E2 in rat mesangial cells is prevented by dexamethasone. Biochem Biophys Res Commun 1991; 180:46-52. [PMID: 1930239 DOI: 10.1016/s0006-291x(05)81252-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have previously described that treatment of rat glomerular mesangial cells with interleukin-1 beta, tumor necrosis factor or forskolin stimulates the synthesis and secretion of prostaglandin E2 and group II phospholipase A2. We now report that pretreatment of the mesangial cells with dexamethasone dose-dependently suppresses the cytokines- and forskolin-induced synthesis of prostaglandin E2 as well as the induced synthesis and secretion of group II phospholipase A2. These observations implicate that the inhibition of the cellular or secreted phospholipase A2 activity by dexamethasone in rat mesangial cells is not due to induced synthesis of phospholipase A2 inhibitory proteins but caused by direct inhibition of phospholipase A2 protein expression.
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Affiliation(s)
- C Schalkwijk
- Centre for Biomembranes and Lipid Enzymology, Utrecht, The Netherlands
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26
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Garcia MC, Garcia C, Gijon MA, Fernandez-Gallardo S, Mollinedo F, Sanchez Crespo M. Metabolism of platelet-activating factor in human haematopoietic cell lines. Differences between myeloid and lymphoid cells. Biochem J 1991; 273 ( Pt 3):573-8. [PMID: 1847616 PMCID: PMC1149801 DOI: 10.1042/bj2730573] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The binding and metabolism of platelet-activating factor (PAF) was studied in human cell lines resembling myeloid cells (HL60 and U937) and B and T lymphocytes (Daudi and Jurkat). All of the cell lines were found to bind and catabolize exogenous [3H]PAF in a time- and temperature-dependent manner. PAF binding could also be demonstrated in isolated membrane fractions, which provides further evidence of the existence of true membrane receptors. Myeloid cell lines contained numbers of receptors at least 10-fold higher than in lymphoid cell lines. Biosynthesis of PAF upon challenge by ionophore A23187 could be demonstrated in HL60 and U937 cells. In contrast, lymphoid cell lines were unable to produce PAF. Incubation with [14C]acetate showed incorporation of the label into three main fractions: neutral lipids, phosphatidylcholine and PAF, but the distribution of the label varied depending on the cell line. Significant incorporation into phosphatidylcholine was observed in uninduced myeloid cell lines. A phospholipase A2 acting on 1-O-hexadecyl-2-arachidonoyl-sn-glycero-3-phosphocholine and an acetyl-CoA:lyso-PAF acetyltransferase were expressed in the HL60 cell line and showed variations in specific activity with granulocytic differentiation. In contrast, these enzyme activities were not expressed in Daudi and Jurkat cell lines. These data indicate (1) the occurrence of PAF binding and catabolism in both myeloid and lymphoid cell lines; (2) the restriction of PAF biosynthesis to myeloid cell lines, especially HL60 cells; (3) the occurrence of differentiation-elicited changes in the specific activities of the enzymes involved in PAF biosynthesis by the remodelling pathway; and (4) the central role played by the disposal of lyso-PAF, a product of the phospholipase A2 reaction, in PAF biosynthesis.
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Affiliation(s)
- M C Garcia
- Instituto de Investigaciones Médicas de la Fundación Jiménez Díaz, Centro Asociado al CSIC, Madrid, Spain
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27
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Schalkwijk C, Pfeilschifter J, Märki F, van den Bosch H. Interleukin-1 beta, tumor necrosis factor and forskolin stimulate the synthesis and secretion of group II phospholipase A2 in rat mesangial cells. Biochem Biophys Res Commun 1991; 174:268-75. [PMID: 1989605 DOI: 10.1016/0006-291x(91)90515-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Treatment of rat glomerular mesangial cells with interleukin-1 beta, tumor necrosis factor or forskolin resulted in the release of phospholipase A2 activity in the culture medium. Essentially all of this phospholipase A2 activity was bound to immobilized monoclonal antibodies raised against rat liver mitochondrial 14 kDa group II phospholipase A2. Gelfiltration confirmed the absence of higher molecular weight phospholipases A2 in the culture medium. Immunoblot experiments showed the virtual absence of this 14 kDa group II phospholipase A2 in unstimulated mesangial cells. The time-dependent increase of phospholipase A2 activity in both cells and culture medium upon stimulation with interleukin-1 beta plus forskolin is accompanied with elevated 14 kDa phospholipase A2 protein levels. These results indicate that the increased phospholipase A2 activity upon treatment of mesangial cells with these stimulators is due to increased synthesis of group II phospholipase A2. Over 85% of this newly synthesized phospholipase A2 appears to be secreted from the cells.
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Affiliation(s)
- C Schalkwijk
- Centre for Biomembranes and Lipid Enzymology, Utrecht, The Netherlands
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28
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29
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Kanoh H, Kanaho Y, Nozawa Y. Phospholipase B-like activity in rabbit brain membranes. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1991; 100:367-9. [PMID: 1799980 DOI: 10.1016/0305-0491(91)90388-t] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Phospholipase B-like activity was found in rabbit brain membranes. 2. The activity was greatly enhanced by 0.025% (w/v) Triton X-100 and was inhibited by both Ca2+ and Mg2+. 3. With increasing pH of the reaction mixture, the activity was augmented. 4. The characteristics of the enzyme activity possibly suggest that phospholipase B in rabbit brain may be distinct from those previously reported.
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Affiliation(s)
- H Kanoh
- Department of Biochemistry, Gifu University School of Medicine, Japan
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30
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Schalkwijk CG, Märki F, Van den Bosch H. Studies on the acyl-chain selectivity of cellular phospholipases A2. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1044:139-46. [PMID: 2340304 DOI: 10.1016/0005-2760(90)90229-q] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The selective release of arachidonate, as opposed to monoenoic and dienoic fatty acids, after stimulation of cells has suggested the involvement of arachidonate-selective phospholipases A2. Supportive evidence for the existence of such enzymes has also come from in vitro experiments. We have studied the acyl-chain selectivity of phospholipase A2 preparations obtained from human polymorphonuclear leukocytes, human platelets and rat platelets using sn-2-[14C]oleoylphosphatidylcholine and sn-2-[3H]arachidonoylphosphatidylcholine either as single substrates or in doubly labeled mixtures. In either case, no evidence for acyl-chain selectivity was observed for human PMN and rat platelet phospholipase A2. Additional experiments with human PMN homogenates and derived extracts yielded no indication for the selective loss of an arachidonate-selective phospholipase A2. Results with human platelet cytosol were highly suggestive for the presence of an arachidonoyl-selective phospholipase A2 when separate phosphatidylcholine species were assayed. This apparent selectivity was progressively lost when the substrates were mixed or embedded in a membrane of 1-palmitoyl-2-linoleoylphosphatidylcholine. The implications for occurrence of arachidonate-selective phospholipase A2 are discussed.
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Affiliation(s)
- C G Schalkwijk
- Centre for Biomembranes and Lipid Enzymology, Utrecht, The Netherlands
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31
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Abstract
Phospholipases are enzymes that hydrolyze specific portions of phospholipid molecules. Their role in the digestion of exogenous phospholipids and as the active principle in snake and bee venoms has long been appreciated. Interest has increased in phospholipases recently because of new data implicating them in the inflammatory response. The ability of phospholipases to hydrolyze bacterial phospholipids has also received considerable attention. These new data have brought pertinence to studies of the physicochemical nature of potential substrates that greatly influence enzyme activity. Interest in the regulation of enzyme activity, both by physiological and pharmacological means, has increased as the importance of the phospholipases in response to various stimuli has become better appreciated. Finally, considerable interest has focused on the role of the phospholipases in response to hormones in a variety of cell systems. Data pertinent to all of these areas of interest will be discussed in this review with a view toward stimulating those with an interest in gastrointestinal physiology to apply them to their own areas of research in the gastrointestinal tract or liver.
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Affiliation(s)
- C M Mansbach
- Department of Medicine, University of Tennessee, Memphis
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32
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Sturk A, Schaap MC, Prins A, ten Cate JW, van den Bosch H. Synthesis of platelet-activating factor by human blood platelets and leucocytes. Evidence against selective utilization of cellular ether-linked phospholipids. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 993:148-56. [PMID: 2512985 DOI: 10.1016/0304-4165(89)90157-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Synthesis of platelet activating factor (PAF) in blood platelet suspensions may be due to leucocyte contamination. We therefore investigated PAF synthesis in human blood platelet suspensions and granulocyte- (PMN)-enriched leucocyte suspensions upon stimulation by thrombin and Ca2+-ionophore A23187, both in the presence and absence of the presumed PAF catabolism inhibitor phenylmethylsulfonyl fluoride (PMSF). PAF synthesis was measured by aggregation of washed rabbit platelets and by [3H]acetate incorporation. In contrast to A23187, thrombin was unable to stimulate PAF synthesis by leucocytes. As thrombin did induce PAF synthesis by platelet suspensions, this was evidently not due to leucocyte contamination. A23187 also induced PAF synthesis by platelets, but this was dependent upon the platelet isolation method and possibly associated activation. The ratio of [3H]acetate incorporation into 1-alkyl- versus 1-acyl-2-acetylglycerophosphocholine upon stimulation of non-PMSF-treated leucocytes and platelets amounted to 12.8 and 1.2, respectively. These values are at least 10-fold higher than the ratio of 1-alkyl versus 1-acyl species in the cellular phosphatidylcholine precursor for PAF. By PMSF pretreatment, the distribution of incorporated [3H]acetate between 1-ether- and 1-ester-linked species became similar to that in the precursor phosphatidylcholines of the respective cell type, due to increased recovery of [3H]acetate in the acyl compounds. Both leucocyte and platelet homogenates rapidly degraded acylacetylglycerophosphocholine to (acetyl)glycerophosphocholine, and this deacylation was inhibited by PMSF pretreatment of the cells. We conclude that upon cell stimulation a phospholipase A2 converts both alkylacylglycerophosphocholine and diacylglycerophosphocholine to the 2-lysoanalogs in a ratio similar to the occurrence of the parent compounds. The acetyltransferase subsequently acetylates both compounds to acylacetylglycerophosphocholine and alkylacetylglycerophosphocholine (PAF), respectively. Deacylation of the 1-ester-linked species, either before or after acetylation, gives the impression of selective utilization of 1-ether-linked species for PAF production. It is only after inhibition of the deacylation by pretreatment of the cells with PMSF that a mainly nondiscriminative use of 1-ether- and 1-ester-linked species by both phospholipase A2 and acetyltransferase becomes evident.
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Affiliation(s)
- A Sturk
- Department of Hematology, Academic Medical Centre, Amsterdam, The Netherlands
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33
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Kissel JA, Fontaine RN, Turck CW, Brockman HL, Hui DY. Molecular cloning and expression of cDNA for rat pancreatic cholesterol esterase. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 1006:227-36. [PMID: 2688744 DOI: 10.1016/0005-2760(89)90201-4] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A full-length cDNA complementary to the rat pancreatic cholesterol esterase mRNA was isolated by screening a rat pancreatic cDNA expression library in lambda gt11 vector with antibodies against the porcine pancreatic cholesterol esterase. The isolated cholesterol esterase cDNA is 2050 bp in length and contains an open reading frame coding for a protein of 612 amino acids. A 20-amino acid hydrophobic leader sequence is predicted, based on the position of the first ATG initiation codon upstream from the sequenced amino terminus of the isolated cholesterol esterase. The cholesterol esterase cDNA was subcloned into a mammalian expression vector, pSVL, for transfection studies. Expression of the cDNA in COS cells resulted in the production of bile salt-stimulated cholesterol esterase. Comparison of the cholesterol esterase cDNA sequence with other proteins revealed that the pancreatic cholesterol esterase is identical to rat pancreatic lysophospholipase. The primary structure of cholesterol esterase displayed no significant homology with other lipases, although the putative lipid interfacial recognition site of G-X-S-X-G is present in the cholesterol esterase sequence. However, the cholesterol esterase sequence revealed a 63-amino-acid domain which is highly homologous to the active site domain of other serine esterases. These data suggest that cholesterol esterase may be a member of the serine esterase supergene family. Analysis of the cholesterol esterase structure also revealed a repetitive sequence enriched with Pro, Asp, Glu, Ser, and Thr residues at the C-terminal end of the protein. This sequence is reminiscent of the PEST-rich sequences in short-lived proteins, suggesting that cholesterol esterase may have a short half-life in vivo. Northern blot hybridization showed that the bile salt-stimulated cholesterol esterase mRNA is present in liver suggesting that this protein may also be synthesized by liver cells.
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Affiliation(s)
- J A Kissel
- Department of Pathology, University of Cincinnati, College of Medicine, OH 45267-0529
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34
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Aarsman AJ, de Jong JGN, Arnoldussen E, Neys FW, van Wassenaar PD, Van den Bosch H. Immunoaffinity purification, partial sequence, and subcellular localization of rat liver phospholipase A2. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)81760-4] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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35
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Mobilio D, Marshall LA. Chapter 17. Recent Advances in the Design and Evaluation of Inhibitors of Phospholipase A2. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1989. [DOI: 10.1016/s0065-7743(08)60539-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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36
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Abstract
Two phospholipases B (Vx I and Vx II) were purified from the venom of the Japanese yellow hornet, Vespa xanthoptera, by sequential chromatography on Sephadex G-100, SP-Sephadex and Mono S columns. They are very similar to each other in molecular and enzymatic properties, though the specific activity of Vx I was one-fifth that of Vx II. They hydrolyze the acyl ester bonds at the 1-position of phosphatidylcholine and lysophosphatidylcholine, therefore, their enzymatic specificities were of the A1 and L1 types.
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Affiliation(s)
- C Takasaki
- Department of Chemistry, Tohoku University, Sendai, Japan
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37
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Ho CL, Ko JL. Purification and characterization of a lethal protein with phospholipase A1 activity from the hornet (Vespa basalis) venom. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 963:414-22. [PMID: 3196744 DOI: 10.1016/0005-2760(88)90309-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The hornet, Vespa basalis, is one of the most dangerous species of wasps found in Taiwan. The insect is aggressive and its venom is highly toxic. By gel filtration on a Fractogel TSK HW 50 column followed by cation-exchange chromatography on CM-Trisacryl M, a lethal protein was purified from the venom. It has a molecular mass of about 32 kDa and an i.v. LD50 value of 0.32 micrograms/g mouse. The toxin is capable of catalyzing the hydrolysis of emulsified phospholipids but not sphingomyelin. Analysis of the 1H-NMR spectra of the substrates and its hydrolytic products revealed that the toxin liberates fatty acid from the 1-position of sn-3-phosphoacylglycerols. This result indicates that the toxin possesses phospholipase A1 activity. The toxin exhibits an extremely potent hemolytic activity in washed red cells and diluted whole blood (HC50 = 0.09 micrograms/ml in mouse). The potency of direct hemolysis is about 100-times that of a basic phospholipase A2 from Naja nigricollis venom and about 1000-times that of a cardiotoxin from Naja naja atra venom. A positive correlation between the hemolytic activity and lethality of the toxin was found in three species of animals (mouse, rat and guinea pig). In the in vivo study, the toxin caused a marked increase in the plasma K+ concentration and a hyperkalemic change in the ECG of the treated rat. Hyperkalemia resulting from the hemolytic action of the toxin appears to be the main cause of death in the animal.
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Affiliation(s)
- C L Ho
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, China
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38
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Pierik AJ, Nijssen JG, Aarsman AJ, Van den Bosch H. Calcium-independent phospholipase A2 in rat tissue cytosols. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 962:345-53. [PMID: 3167084 DOI: 10.1016/0005-2760(88)90264-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Cytosols (105,000 X g supernatant) from seven rat tissues were assayed for Ca2+-independent phospholipase A2 activity with either 1-acyl-2-[1-14C]linoleoyl-sn-glycero-3-phosphocholine, 1-acyl-2-[1-14C]linoleoyl-sn-glycero-3-phosphoethanolamine or 1-O-hexadecyl-2-[9,10-3H2]oleoyl-sn-glycero-3-phosphocholine as substrate. Low but consistent activities ranging from 10-120 pmol/min per mg protein were found in all tissues. The highest activities were present in liver, lung and brain. Total activities in mU/g wet weight were rather constant, ranging from 0.43 (heart) to 1.36 (liver). The soluble enzyme from rat lung cytosol was further investigated and was found to be capable of hydrolyzing microsomal membrane-associated substrates without exhibiting much selectivity for phosphatidylcholine species. Comparative gel filtration experiments of cytosol prepared from non-perfused and perfused lungs indicated that part of the Ca2+-independent phospholipase A2 originated from blood cells, but most of it was derived from lung cells. Lung cytosol also contained Ca2+-dependent phospholipase A2 activity, a small part of which originated from blood cells, presumably platelets. The major amount of Ca2+-dependent phospholipase A2 activity, however, came from lung cells. Neither this enzyme nor the Ca2+-independent phospholipase A2 from lung tissue showed immunological cross-reactivity with monoclonal antibodies against Ca2+-dependent phospholipase A2 isolated from rat liver mitochondria.
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Affiliation(s)
- A J Pierik
- Laboratory of Biochemistry, State University of Utrecht, The Netherlands
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39
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Lenting HB, Neys FW, van den Bosch H. Regulatory aspects of mitochondrial phospholipase A2 from rat liver: effects of proteins, phospholipids and calcium ions. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 961:129-38. [PMID: 2968122 DOI: 10.1016/0005-2760(88)90138-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This paper deals with the search for specific inhibitors or activators of the mitochondrial phospholipase A2. Convincing evidence for the existence of proteins in the mitochondrial or cytosolic fraction that function as specific regulators of this enzyme was not obtained. The enzymatic activity appeared to be inhibited at low substrate concentrations by lipocortin isolated from human monocytes. However, at higher substrate concentrations, the inhibition disappeared, suggesting either that lipocortin sequestered the phospholipid substrate or that the putative inactive complex of enzyme and lipocortin dissociated in the presence of excess phospholipids. The hydrolysis of the neutral phospholipid phosphatidylethanolamine was stimulated by the presence of cardiolipin and phosphatidylglycerol. It is unlikely that this is caused merely by the negative charge of these phospholipids, since other negatively charged phospholipids did not show this effect. Using a phospholipid extract from mitochondria as substrate, the enzymatic activity as a function of the Ca2+ concentration was determined. Only one enzyme activity plateau was observed. The calculated KCa2+ value of 0.05 mM suggests that the mitochondrial phospholipase A2 could be regulated strictly by the modulation of the free Ca2+ concentration in vivo. The two activity plateaus observed previously upon variation of the Ca2+ concentration using phosphatidylethanolamine as substrate could be explained by a Ca2+-induced transition of the phospholipid structure.
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Affiliation(s)
- H B Lenting
- Laboratory of Biochemistry, State University of Utrecht, The Netherlands
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40
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Lenting HB, Nicolay K, van den Bosch H. Regulatory aspects of mitochondrial phospholipase A2: correlation of hydrolysis rates with substrate configuration as evidenced by 31P-NMR. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 958:405-15. [PMID: 3342248 DOI: 10.1016/0005-2760(88)90226-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The influence of variation of the phospholipid composition in model membranes composed of phosphatidylcholine and phosphatidylethanolamine on the hydrolysis of these phospholipids by rat liver mitochondrial phospholipase A2 was investigated. With the pure phospholipids, phosphatidylethanolamine was hydrolyzed over 30-times faster than phosphatidylcholine. Upon increasing the mole percentage of phosphatidylethanolamine in mixtures, a gradual, though non-linear, increase in the initial rate of hydrolysis of this phospholipid was observed. By contrast, phosphatidylcholine hydrolysis remained constant up to about 50 mol% phosphatidylethanolamine, whereafter a sudden fall-off of activity was observed. This drop in the hydrolysis rate coincided with a transition of the phospholipid structure from bilayer to an as yet unidentified organization characterized by an isotropic signal in the 31P-NMR spectra recorded in the presence of Ca2+. The occurrence of this phase was clearly dependent on Ca2+, since mixtures with identical composition in the absence of Ca2+ remained largely in bilayer configuration. That the structure adopted by phospholipids is of importance for their susceptibility to attack by this intracellular phospholipase A2 became evident also in studies with the single phospholipids in the absence or presence of Triton X-100 above the critical micellar concentration. While phosphatidylcholine hydrolysis was inhibited in mixed micelles as compared to its bilayer organization, the hydrolysis of phosphatidylethanolamine in mixed micelles was 3-fold that in the hexagonal HII phase.
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Affiliation(s)
- H B Lenting
- Laboratory of Biochemistry, State University of Utrecht, The Netherlands
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41
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Reers M, Pfeiffer DR. Inhibition of mitochondrial phospholipase A2 by mono- and dilysocardiolipin. Biochemistry 1987; 26:8038-41. [PMID: 3442642 DOI: 10.1021/bi00399a002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Phospholipase A2 extracted from the acetone powder of previously frozen rat liver mitochondria is strongly inhibited compared to the activity manifest before acetone powder preparation. Activity is substantially recovered upon partial purification of the enzyme by gel filtration chromatography. Inhibitor activity elutes in the void volume from the column and is obtained in the chloroform layer when void volume fractions are subjected to a Folch extraction. Structural studies support the inhibitor being monolysocardiolipin. Under the assay conditions employed, 1 molecule of the inhibitor per 5000 substrate molecules or 40 nM on a nominal concentration basis is I50 for the mitochondrial enzyme. The agent is similarly effective against pancreatic and snake venom phospholipases A2. Monolysocardiolipin and dilysocardiolipin prepared enzymatically from bovine heart cardiolipin are less potent than the material arising from rat liver cardiolipin by factors of 10- and 30-fold, respectively, yet are still highly potent compared to the other known inhibitors of this enzyme. Differences in acyl group composition, in the degree of acyl group oxidation, or in structural isomerism between the sn-1 and sn-2 positions of the lyso compounds may account for the difference in potency between the materials derived from rat liver and bovine heart.
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Affiliation(s)
- M Reers
- Hormel Institute, University of Minnesota, Austin 55912
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42
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The purification and characterization of a phospholipase A in hamster heart cytosol for the hydrolysis of phosphatidylcholine. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45472-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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43
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de Jong JG, Amesz H, Aarsman AJ, Lenting HB, van den Bosch H. Monoclonal antibodies against an intracellular phospholipase A2 from rat liver and their cross-reactivity with other phospholipases A2. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 164:129-35. [PMID: 3830178 DOI: 10.1111/j.1432-1033.1987.tb11003.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The membrane-associated phospholipase A2 from rat liver mitochondria was solubilized and partially purified by AcA 54 gel filtration and Matrex gel blue A chromatography. The approximately 2500-fold purified preparation was injected into mice to prepare monoclonal antibodies against phospholipase A2 after fusion of spleen cells and mouse SP2/0 myeloma cells. Hybridoma supernatants were assayed for antibody production in enzyme-linked immunosorbent assay with partially purified phospholipase A2 as antigen. Positive clones were tested for their ability to bind phospholipase A2 in a specific immunoprecipitation assay involving protein-A--Sepharose to which rabbit anti-(mouse immunoglobulins) and monoclonal antibodies from hybridoma supernatants were complexed. Twelve clones producing antibodies that bound mitochondrial phospholipase A2 were identified. The binding of all of these antibodies to protein fractions eluted from AcA 54 and Matrex gel blue A columns coincided with the phospholipase A2 activity in these fractions. All monoclonal antibodies showed cross-reactivity with rat liver cytosolic and solubilized rat platelet phospholipase A2. Extracellular phospholipase A2 from rat and pig pancreas or Crotalus atrox were not recognized by the anti-(mitochondrial phospholipase A2) antibodies.
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44
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Nijssen JG, Promes LW, Hardeman D, van den Bosch H. Phospholipid-protein interactions in rat lung lamellar bodies. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 917:140-7. [PMID: 3790603 DOI: 10.1016/0005-2760(87)90294-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We investigated the specificity of the cytosol-mediated phosphatidylcholine transfer between isolated rat lung microsomes and rat lung lamellar bodies. For that purpose we labeled the microsomes with 1-acyl-2-[1-14C]palmitoyl- and 1-acyl-2-[9,10-3H]oleoylphosphatidylcholine through protein-catalyzed phosphatidylcholine exchange. Incubation in buffer resulted in 3-5% transfer of label from microsomes to lamellar bodies. Lung cytosol stimulated this transfer about 2-fold and the presence of 12 micrograms/ml phosphatidylcholine-transfer protein from bovine liver resulted in a 30 to 35% recovery of radioactivity in the lamellar bodies. When microsomal donor membranes with a 3H/14C ratio of 2.6 were used, the 3H/14C ratios of the lamellar bodies were 3.9, 3.7 and 3.7, after incubation in buffer, with cytosol and with bovine liver exchange protein, respectively. Doubling the amount of lamellar body acceptor membranes resulted in 3H/14C ratios in the lamellar bodies of 4.6 and 4.1, after incubation in buffer and with cytosol, respectively. Furthermore, we isolated the protein component from rat lung lamellar bodies and performed reconstitution experiments with phospholipids. Reconstituted and non-reconstituted phospholipid and protein were separated by either Sepharose 4B gel filtration or discontinuous sucrose gradient centrifugation. The presence of lamellar body protein in the reconstitution mixture resulted in the formation of larger structures with higher density than those formed in control experiments without protein. When 1-acyl-2-[1-14C]palmitoyl- and 1-acyl-2-[9,10-3H]oleoylphosphatidylcholine were included in the reconstitution mixture, the structures containing lamellar body protein had 2- to 4-fold lower 3H/14C ratios than initially present in the incubation. These results suggest that lamellar body proteins associate preferentially with disaturated phosphatidylcholine species.
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45
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Lenting HB, Neys FW, van den Bosch H. Hydrolysis of exogenous substrates by mitochondrial phospholipase A2. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 917:178-85. [PMID: 3790605 DOI: 10.1016/0005-2760(87)90298-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Evidence is provided in this paper to indicate that hydrolysis of exogenously added phosphatidylethanolamine and phosphatidylcholine by the membrane-bound phospholipase A2 from rat-liver mitochondria is preceded by association of the substrates with the membranes. Hydrolysis of phosphatidylethanolamine after preincubation of mitochondria and substrate is nearly independent of incubation volume, indicating that substrate and mitochondria are not independently diluted. The association is greatly enhanced in the presence of Ca2+, especially for phosphatidylethanolamine. Association can be measured after sucrose-gradient centrifugation of mitochondria preincubated with phosphatidylethanolamine and can be visualized by freeze-fracture electronmicroscopy, showing substrate clusters fused with mitochondria. The association provides an explanation for the hydrolysis of exogenous substrates by a membrane-associated phospholipase A2 as well as for the high preference for phosphatidylethanolamine degradation often observed in studies on membrane-bound phospholipases A. This preference is likely to result in part from the tendency of unsaturated phosphatidylethanolamines to adopt non-bilayer lipid phases allowing a more extensive association with biomembranes in the presence of Ca2+, and does not reflect enzyme specificity per se. This phenomenon should be kept in mind when determining the substrate specificity of membrane-bound phospholipases A by the use of exogenous substrates.
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46
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Takeuchi Y, Okumura T, Sugatani J, Saito K. Molecular relationship between two types of phospholipase B from Penicillium notatum and reconstitution of active enzyme from its peptide fragments. Arch Biochem Biophys 1987; 252:206-17. [PMID: 3545077 DOI: 10.1016/0003-9861(87)90025-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Two types of phospholipase B of Penicillium notatum, the native type and the modified type that is thought to be generated by the introduction of some nicks into the native type of enzyme by the endogenous protease(s), were distinguished on a slab sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis under a nonreducing condition. The native form migrated with a rate corresponding to 95K Da, whereas the modified form migrated more slowly, corresponding to 106K Da, presumably because of its more extended conformation. That the "106K" protein was indeed a nicked product of the "95K" protein was confirmed by amino acid analysis, peptide mapping, N- and C-terminal sequence analyses, and immunoblotting. The peptide fragments (70K and 37K + 32K) comprising the modified protein were isolated by gel filtration in the presence of SDS and 2-mercaptoethanol (the 32K peptide was suggested to be a partial proteolytic product of the 37K peptide). When the "95K" protein was subjected to the same treatment under denaturing condition, it retained a low, but significant, enzymatic activity; in contrast, the separated peptide fragments did not show any significant activity. By a coincubation of these fragments, however, a restoration of enzymatic activity was observed through a reformation of the active complex, corresponding to the original modified protein. The enzymatic activity of this complex was further increased by a treatment with guanidine X HCl, followed by dialysis. The association of peptide fragments appears to occur through the formation of interpeptidal disulfide bonds.
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47
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48
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Nijssen JG, Oosting RS, Nÿkamp FP, van den Bosch H. Transfer of arachidonate from phosphatidylcholine to phosphatidylethanolamine and triacylglycerol in guinea pig alveolar macrophages. Lipids 1986; 21:623-8. [PMID: 3099114 DOI: 10.1007/bf02537210] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Guinea pig alveolar macrophages were labeled by incubation with either arachidonate or linoleate. Arachidonate labeled phosphatidylcholine (PC), phosphatidylethanolamine (PE) and triglycerides (TG) equally well, with each lipid containing about 30% of total cellular radioactivity. In comparison to arachidonate, linoleate was recovered significantly less in PE (7%) and more in TG (47%). To investigate whether redistributions of acyl chains among lipid classes took place, the macrophages were incubated with 1-acyl-2-[1-14C]arachidonoyl PC or 1-acyl-2-[1-14C]linoleoyl PC. After harvesting, the cells incubated with 1-acyl-2-[1-14C]linoleoyl PC contained 86% of the recovered cellular radioactivity in PC, with only small amounts of label being transferred to PE and TG (3 and 6%, respectively). More extensive redistributions were observed with arachidonate-labeled PC. In this case, only 60% of cellular radioactivity was still associated with PC, while 22 and 12%, respectively, had been transferred to PE and TG. Arachidonate transfer from PC to PE was unaffected by an excess of free arachidonate which inhibited this transfer to TG for over 90%, indicating that different mechanisms or arachidonoyl CoA pools were involved in the transfer of arachidonate from PC to PE and TG. Cells prelabeled with 1-acyl-2-[1-14C]arachidonoyl PC released 14C-label into the medium upon further incubation. This release was slightly stimulated by zymosan and threefold higher in the presence of the Ca2+-ionophore A23187. Labeling of macrophages with intact phospholipid molecules appears to be a suitable method for studying acyl chain redistribution and release reactions.
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49
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Nijssen JG, Roosenboom CF, van den Bosch H. Identification of a calcium-independent phospholipase A2 in rat lung cytosol and differentiation from acetylhydrolase for 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF-acether). BIOCHIMICA ET BIOPHYSICA ACTA 1986; 876:611-8. [PMID: 3707986 DOI: 10.1016/0005-2760(86)90050-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The 100 000 X g supernatant of total rat lung homogenate was found to contain at least three phospholipase A2-type activities. Gel filtration separated a low molecular weight and Ca2+-requiring phospholipase A2 from Ca2+-independent acylhydrolase peak with an apparent higher molecular weight. Upon DEAE-cellulose chromatography this fraction was separated into a Ca2+-independent acylhydrolase and a Ca2+-independent platelet-activating factor-acetylhydrolase with no apparent overlap in acyl chain length specificity. The long-chain acylhydrolase was shown to exhibit specificity for the ester bond at the sn-2-position. Ca2+-independent phospholipase A2 activity was inhibited by p-bromophenacylbromide and was resistant to diisopropylfluorophosphate. In contrast, the Ca2+-independent acetylhydrolase activity was inhibited by diisopropylfluorophosphate but was unaffected by p-bromophenacylbromide.
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50
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Nijssen JG, van den Bosch H. Coenzyme A-mediated transacylation of sn-2 fatty acids from phosphatidylcholine in rat lung microsomes. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 875:458-64. [PMID: 3081034 DOI: 10.1016/0005-2760(86)90065-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Evidence was obtained for a CoA-dependent transfer of linoleate from rat lung microsomal phosphatidylcholine to lysophosphatidylethanolamine without the intervention of a Ca2+-requiring phospholipase A2 activity and ATP. To study this CoA-mediated transacylation process, microsomes were prepared in which the endogenous phosphatidylcholine was labeled by protein-catalyzed exchange with phosphatidylcholines containing labeled fatty acids in the sn-2-position. The apparent Km for CoA in the transfer of arachidonate from phosphatidylcholine to 1-acyllysophosphatidylethanolamine was 1.5 microM. At saturating lysophosphatidylethanolamine concentrations, the transacylation was linear with the amount of microsomal protein, i.e., a fixed percentage of the labeled fatty acid was transferred independent of the amount of microsomal protein. A maximal transfer of 12.2% for arachidonate and 2.0% for linoleate from the respective phosphatidylcholines to lysophosphatidylethanolamine was observed in 30 min. With 1-acyl-2-[1-14C]arachidonoylphosphatidylcholine as acyl donor, lysophosphatidylethanolamine was the best acceptor followed by lysophosphatidylglycerol and lysophosphatidylserine. Lysophosphatidate barely functioned as acceptor. These data provide further evidence for the widespread occurrence of CoA-mediated transacylation reactions. The arachidonate transacylation from phosphatidylcholine to other phospholipids in lung tissue may contribute to the low level of arachidonate in pulmonary phosphatidylcholine.
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