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Petry C, Huwiler A, Eberhardt W, Kaszkin M, Pfeilschifter J. Hypoxia increases group IIA phospholipase A(2) expression under inflammatory conditions in rat renal mesangial cells. J Am Soc Nephrol 2005; 16:2897-905. [PMID: 16135775 DOI: 10.1681/asn.2004121051] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Hypoxia evokes a common mechanism of oxygen sensing mediated by hypoxia-inducible transcription factors (HIF) in many mammalian cells. This study investigated the effect of hypoxia on group-IIA secretory phospholipase A(2) (sPLA(2)-IIA) expression in renal mesangial cells. Stimulation of cells with IL-1beta under normoxic conditions (21% O(2)) is known to induce expression and secretion of the group sPLA(2)-IIA. This induction is further enhanced by constantly reducing the O(2) concentration to 1% O(2), and is accompanied by increased sPLA(2) activity. To see whether hypoxia potentiates IL-1beta-induced sPLA(2)-IIA gene expression, a 2.67-kb fragment of the rat sPLA(2)-IIA promoter was fused to a luciferase reporter construct and used to transfect mesangial cells. Hypoxia alone is not able to activate the sPLA(2) promoter, whereas it significantly enhances IL-1beta-stimulated promoter activity. A deletion mutant of the promoter that lacks the two putative hypoxia responsive elements (HRE) is devoid of the potentiating effect of hypoxia. Moreover, site-directed mutagenesis of either of the two HRE is sufficient to abolish the potentiating effect of hypoxia. Electrophoretic mobility shift assays show that HIF-2alpha, which is the only HIF subtype expressed in mesangial cells, binds to both HRE in the sPLA(2)-IIA promoter. In summary, the data show that in an inflammatory setting hypoxia is able to potentiate sPLA(2)-IIA expression and activity in renal mesangial cells, and thereby may critically contribute to enhanced formation of inflammatory lipid mediators seen in a diverse range of kidney diseases.
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Affiliation(s)
- Claudia Petry
- Pharmazentrum Frankfurt, Klinikum der Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
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Petry C, Fritz G, Pfeilschifter J, Huwiler A. Inhibition of Rho modulates cytokine-induced prostaglandin E2 formation in renal mesangial cells. Biochim Biophys Acta Mol Cell Biol Lipids 2004; 1636:108-18. [PMID: 15164758 DOI: 10.1016/j.bbalip.2003.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2003] [Accepted: 11/20/2003] [Indexed: 12/21/2022]
Abstract
Stimulation of rat mesangial cells for 24 h with interleukin-1beta (IL- 1beta) plus forskolin (Fk) leads to a marked increase in prostaglandin E2 (PGE2) synthesis. This effect is further enhanced by the small G-protein Rho inhibitor toxin A. A similar increase in PGE2 formation is obtained with Y27632, a Rho-dependent kinase inhibitor, and with lovastatin, a hydroxymethylglutaryl-coenzyme A inhibitor which depletes cells from geranylgeranyl moieties and thus blocks Rho activation. In parallel to the increased PGE2 synthesis, a potentiation of IL-1beta-induced secretory group IIA phospholipases A2 (sPLA2-IIA) protein expression also occurs by Rho inhibition. However, only toxin A triggers an increased sPLA2-IIA activity consistent with the elevated levels of protein expression, whereas Y27632 and lovastatin rather reduced IL-1beta-induced sPLA2-IIA activity. In vitro activity studies reveal that Y27632 and lovastatin can directly block sPLA2-IIA enzyme activity in a concentration-dependent manner. Interestingly, in the absence of IL-1beta/Fk stimulation and the lack of sPLA2-IIA protein expression, all Rho inhibitors exert a small but significant increase in PGE2 formation suggesting that additional PLA2s or downstream enzymes like cyclooxygenases or prostaglandin synthases may be activated by Rho inhibitors. Western blot analyses of toxin A-, Y27632- and lovastatin-stimulated cells reveal that the cytosolic group IV PLA2 (cPLA2) and the cytosolic PGE2 synthase (cPGES), but not the sPLA2-IIA, cyclooxygenase-2 or the microsomal PGE2 synthase (mPGES), are upregulated compared to unstimulated cells. Furthermore, the Rho inhibitors induced arachidonic acid release from intact cells which is blocked by the cPLA2 inhibitor methyl arachidonyl fluorophosphonate (MAFP). In summary, these data show that inhibition of the small G-protein Rho, either by toxin A, lovastatin, or Y27632, exert a dual effect on mesangial cells: (i) in the absence of an inflammatory stimulus it activates the constitutive cPLA2 and cPGE2 synthase and generates low amount of PGE2. (ii) In the presence of inflammatory cytokines it potentiates sPLA2-IIA expression and subsequent PGE2 formation. In addition, we identified lovastatin and Y27632 as direct inhibitors of sPLA2-IIA in a cell-free system.
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Affiliation(s)
- Claudia Petry
- Pharmazentrum Frankfurt, Klinikum der Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590, Frankfurt am Main, Germany
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van der Helm HA, Buijtenhuijs P, van den Bosch H. Group IIA and group V secretory phospholipase A(2): quantitative analysis of expression and secretion and determination of the localization and routing in rat mesangial cells. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1530:86-96. [PMID: 11341961 DOI: 10.1016/s1388-1981(00)00171-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mesangial cells can be induced to express group IIA and group V secretory phospholipase A(2) (sPLA(2)) at the mRNA level and at the protein level. In this report we quantitatively analyze the expression of both proteins in stimulated cells by Western blot techniques. We found that 75-80% of the total amount of synthesized group IIA sPLA(2) was secreted. The synthesized group V sPLA(2), however, was present almost exclusively intracellularly. The amount of group V present in the cell was comparable to the intracellular amount of group IIA sPLA(2). We furthermore studied the localization and routing of both proteins. Using fusion proteins of the group IIA or group V pre-sPLA(2) with green fluorescent protein it was established that both presequences are able to direct the proteins to the Golgi system. In immunofluorescence studies group V sPLA(2) expressed by rat mesangial cells was located in a punctate pattern in the cytosol with an enrichment near the nucleus. Immunofluorescent confocal laser scanning microscopy revealed that the group V and IIA sPLA(2) show partial colocalization in a Golgi-like structure in the inner part in the cell, but no colocalization was seen in the vesicles in the cytoplasm. The images also showed that group IIA sPLA(2) was located throughout the cell while group V was mainly present in the inner part of the cell. After treatment of the cells with brefeldin A or monensin the group IIA enzyme could no longer be detected, while group V sPLA(2) was still present although its localization was somewhat dependent on the treatment. Collectively, these results indicate that the two enzymes differ in both localization and routing in the cell, which underscores the hypothesis that the enzymes might have different functions.
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Affiliation(s)
- H A van der Helm
- Centre for Biomembranes and Lipid Enzymology, Department Biochemistry of Lipids, Institute of Biomembranes, Utrecht University, The Netherlands
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van der Helm HA, Aarsman AJ, Janssen MJ, Neys FW, van den Bosch H. Regulation of the expression of group IIA and group V secretory phospholipases A(2) in rat mesangial cells. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1484:215-24. [PMID: 10760471 DOI: 10.1016/s1388-1981(00)00021-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rat mesangial cells synthesize and secrete a secretory phospholipase A(2) upon stimulation of the cells with cytokines, like IL-1beta and TNF and with cAMP elevating agents like forskolin. This enzyme was previously characterized to belong to group IIA sPLA(2). The discovery of several other low molecular weight phospholipases, like group IIC in murine testis and group V in human and rat heart, prompted investigations on the presence of group IIC and group V sPLA(2) in rat mesangial cells. This was done by isolating the RNA from stimulated cells and performing RT-PCR, using primers specific for group IIC and V sPLA(2). The results indicate that rat mesangial cells upon stimulation express next to group IIA also group V sPLA(2). No indications were obtained for the expression of group IIC sPLA(2). The regulation of the expression of group V sPLA(2) at the mRNA level was further investigated by examining the time-dependent expression, the influence of dexamethasone and the signaling route of the IL-1beta stimulation. The results show that the IL-1beta induced expression of group V sPLA(2) mRNA was time dependent and, similar to that of group IIA sPLA(2) mRNA, involves activation of NF-kappaB. However, in contrast to the group IIA sPLA(2), the expression of group V sPLA(2) was not influenced by the presence of dexamethasone. The expression of both phospholipases was also examined at the protein level in stimulated mesangial cells. Western blot analysis shows that stimulated mesangial cells synthesize both group IIA and group V sPLA(2) protein but the expression of group V is lower compared to that of group IIA sPLA(2). In addition, the extent of secretion into the medium appears to be considerably higher for group IIA than for group V sPLA(2).
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Affiliation(s)
- H A van der Helm
- Biochemistry Laboratory, Centre for Biomembranes and Lipid Enzymology, Institute for Biomembranes, University of Utrecht, Padualaan 8, 3584 CH, Utrecht, The Netherlands
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Bingham CO, Fijneman RJ, Friend DS, Goddeau RP, Rogers RA, Austen KF, Arm JP. Low molecular weight group IIA and group V phospholipase A(2) enzymes have different intracellular locations in mouse bone marrow-derived mast cells. J Biol Chem 1999; 274:31476-84. [PMID: 10531350 DOI: 10.1074/jbc.274.44.31476] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The subcellular location of the enzymes of eicosanoid biosynthesis is critical for their co-ordinate action in the generation of leukotrienes and prostaglandins. This activity is thought to occur predominantly at a perinuclear location. Whereas the subcellular locations of cytosolic phospholipase (PL) A(2) and each of the pathway enzymes of eicosanoid generation have been defined, the distribution of the low molecular weight species of PLA(2) has remained elusive because of the lack of antibodies that distinguish among homologous family members. We have prepared affinity-purified rabbit antipeptide IgG antibodies that distinguish mouse group IIA PLA(2) and group V PLA(2). Immunofluorescence staining and immunogold electron microscopy reveal different subcellular locations for the enzymes. Group IIA(2) PLA(2) is present in the secretory granules of mouse bone marrow-derived mast cells, consistent with its putative role in facilitating secretory granule exocytosis and its consequent extracellular action. In contrast, group V PLA(2) is associated with various membranous organelles including the Golgi apparatus, nuclear envelope, and plasma membrane. The perinuclear location of group V PLA(2) is consistent with a putative interaction with translocated cytosolic PLA(2) in supplying arachidonic acid for generation of eicosanoid products, while the location in Golgi cisternae may also reflect its action as a secreted enzyme. The spatial segregation of group IIA PLA(2) and group V PLA(2) implies that these enzymes are not functionally redundant.
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Affiliation(s)
- C O Bingham
- Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA
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Janssen MJ, Vermeulen L, Van der Helm HA, Aarsman AJ, Slotboom AJ, Egmond MR. Enzymatic properties of rat group IIA and V phospholipases A(2) compared. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1440:59-72. [PMID: 10477825 DOI: 10.1016/s1388-1981(99)00122-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Group IIA and V phospholipases A(2) (PLA(2)s) are known to play a role in inflammatory responses. We have constructed a bacterial expression vector for rat group IIA and V PLA(2)s, over-expressed, folded and purified the proteins with the aim to study and compare the properties of the enzymes in detail. For zwitterionic phospholipid micelles, both enzymes display optimum activity at pH 8. 0 and absolutely require Ca(2+) for enzymatic activity. In the presence of substrate, group V PLA(2) has a high affinity for Ca(2+) (K(Ca2+)=90 microM) while K(Ca2+) of group IIA PLA(2) was found to be 1.6 mM. The absence of substrate only marginally influences the Ca(2+) affinities. In contrast to group IIA PLA(2), group V PLA(2) does not show a jump in the activity profile at substrate concentrations around the critical micelle concentration. Direct binding studies using n-alkylphosphocholines indicate that group V PLA(2) forms protein-lipid aggregates at pre-micellar lipid concentrations in a cooperative and Ca(2+)-dependent manner. This behavior, which is comparable to that observed for the PLA(2) from Naja melanoleuca snake venom, reflects the high affinity of this enzyme for zwitterionic phospholipids. Competitive inhibition by the substrate analogues (R)-2-dodecanoylaminohexanol-1-phosphocholine and its phosphoglycol derivative was tested on zwitterionic micelles as substrate. Group IIA PLA(2) shows a preference for the phosphoglycol inhibitor whereas the phosphocholine inhibitor binds stronger to the active site of group V PLA(2). The enzymatic activity was also measured on zwitterionic liposomes which appear to be much better substrates for group V PLA(2) than for group IIA PLA(2). The overall results suggest that group V PLA(2) is better suited for action on biological membranes than group IIA PLA(2).
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Affiliation(s)
- M J Janssen
- Department of Enzymology and Protein Engineering, Centre for Biomembranes and Lipid Enzymology (Institute of Biomembranes), Faculty of Chemistry, Utrecht University, P.O. Box 80.054, 3508 TB, Utrecht, The Netherlands
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Pruzanski W, Stefanski E, Vadas P, Kennedy BP, van den Bosch H. Regulation of the cellular expression of secretory and cytosolic phospholipases A2, and cyclooxygenase-2 by peptide growth factors. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1403:47-56. [PMID: 9622592 DOI: 10.1016/s0167-4889(98)00029-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Secretory group II (sPLA2) and cytosolic (cPLA2) phospholipases A2 and cyclooxygenase-2 (Cox-2) play a pivotal role in release of proinflammatory eicosanoids. Excessive activity of sPLA2 per se can also propagate inflammation. Endogenous control of the above enzymes has not been completely elucidated. We investigated the combined impact of promoting cytokines and inhibitory peptide growth factors on the expression of mRNA of the above enzymes, on protein content and extracellular release of sPLA2 and on PGE2 production in osteoblasts (FRCO). The synthesis and release of sPLA2 were enhanced by about 20-fold by 0.5 ng/ml IL-1beta or by 50 ng/ml of TNFalpha. Coaddition of both cytokines resulted in synergistic 150-fold increase in the release of sPLA2 implying the existence of two paths of induction. IL-1beta and TNFalpha markedly enhanced the transcription of sPLA2 mRNA. Kinetic study showed that IL-1/TNF initiated sPLA2 release after 12 h, reaching maximum at 48 h. IL-1alpha was a weak stimulator of sPLA2 release, whereas IL-6, IL-8, IGF, IFN-gamma, growth hormone, insulin and GM-CSF were not stimulatory. Peptide growth hormones TGFbeta, PDGF-BB, EGF and bFGF markedly inhibited the extracellular release of sPLA2. TGFbeta and PDGF-BB significantly reduced the level of sPLA2 mRNA, thus acting upon transcription whereas EGF and bFGF were not inhibitory, acting rather upon the translational or posttranslational steps. IL-1/TNF and growth factors had no significant effect on cPLA2 mRNA expression. Cox-2 mRNA expression was markedly enhanced by IL-1/TNF and suppressed by all growth factors tested. Cytokines enhanced the extracellular release of PGE2 and further enhancement was induced by growth factors with the exception of TGFbeta. Cycloheximide abolished completely the release of sPLA2 and markedly reduced the release of PGE2 from cytokine-stimulated FRCO, regardless of whether growth factors were present or not. NS-398, a specific inhibitor of Cox-2 abolished almost completely the release of PGE2 from cytokine-stimulated cells, regardless of the presence of growth factors. Thus, different signalling mechanisms are involved in the impact of growth factors on mRNA expression of sPLA2, cPLA2 and Cox-2. The differences between the impact on FRCO sPLA2 and that reported in other cells, imply that endogenous control of arachidonic acid cascade is cell-specific.
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Affiliation(s)
- W Pruzanski
- Inflammation Research Group, The Wellesley Central Hospital, University of Toronto, Toronto, Canada
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Walker G, Kunz D, Pignat W, Pfeilschifter J. Platelet-derived growth factor and fibroblast growth factor differentially regulate interleukin 1beta- and cAMP-induced group II phospholipase A2 expression in rat renal mesangial cells. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1391:213-22. [PMID: 9555020 DOI: 10.1016/s0005-2760(97)00204-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Expression of group II phospholipase A2 (PLA2; EC 3.1.1.4) in rat renal mesangial cells is triggered in response to two principal classes of activating signals. These two groups of activators comprise inflammatory cytokines such as interleukin 1beta (IL-1beta) or tumor necrosis factor alpha and agents that elevate cellular levels of cyclic AMP (cAMP) such as forskolin, an activator of adenylate cyclase. Treatment of mesangial cells with IL-1beta or forskolin for 24 h induces group II PLA2 activity secreted into cell culture supernatants by about 15-fold and 11-fold, respectively. Platelet-derived growth factor (PDGF)-BB potently inhibits secretion of IL-1beta- and forskolin-induced group II PLA2 activity. By Western and Northern blot analyses, we demonstrate that this is due to a reduction of PLA2 protein levels and the corresponding PLA2 mRNA steady-state levels. Basic fibroblast growth factor (bFGF) virtually does not inhibit IL-1beta-stimulated group II PLA2 activity, but markedly inhibits forskolin-induced expression of group II PLA2 activity. These effects are caused by changes in the corresponding PLA2 protein and PLA2 mRNA steady-state levels. Inhibition of protein kinase C (PKC) by the potent and selective PKC inhibitor calphostin C converted the inhibitory action of PDGF into a bFGF-type of response thus suggesting that PKC is a major effector in PDGF-induced inhibition of IL-1beta-stimulated group II sPLA2 expression. In summary, our data suggest that PDGF and bFGF differentially modulate in a stimulus-specific manner the expression of group II PLA2 in mesangial cells.
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Affiliation(s)
- G Walker
- Department of Pharmacology, Biozentrum, University of Basel, Klingelbergstr. 70, CH-4056 Basel, Switzerland
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Walker G, Kunz D, Pignat W, van den Bosch H, Pfeilschifter J. Suppression by cyclosporin A of interleukin 1 beta-induced expression of group II phospholipase A2 in rat renal mesangial cells. Br J Pharmacol 1997; 121:787-93. [PMID: 9208149 PMCID: PMC1564731 DOI: 10.1038/sj.bjp.0701170] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. We investigated whether cyclosporin A, a potent immunosuppressive drug, affects group II phospholipase A2. (PLA2; EC 3.1.1.4) induction in rat renal mesangial cells. 2. Previously we showed that the expression of group II PLA2 in rat renal mesangial cells is triggered by exposure of the cells to inflammatory cytokines such as interleukin 1 beta (IL-1 beta) or tumour necrosis factor alpha and agents that elevate cellular levels of cyclic AMP. Treatment of mesangial cells with IL-1 beta for 24 h induced PLA2 activity secreted into cell culture supernatants by about 16 fold. Incubation of mesangial cells with cyclosporin A inhibited IL-1 beta-induced PLA2 section in a dose-dependent fashion, with an IC50 value of 4.3 microM. Cyclosporin A did not directly inhibit enzymatic activity of PLA2. 3. Immunoprecipitation of radioactively labelled PLA2 protein from mesangial cell supernatants revealed that the inhibition of PLA2 activity is due to a suppression of PLA2 protein levels. This effect was preceded by a reduction of PLA2 mRNA steady state levels, as demonstrated by Northern blot analyses of total cellular RNA isolated from stimulated mesangial cells. 4. In order to evaluate whether cyclosporin A would affect the transcriptional activity of the PLA2 gene, we performed nuclear run on transcription experiments and provided evidence that the transcription rate of the PLA2 gene is reduced by cyclosporin A. 5. Previously we found that the nuclear transcription factor kappa B (NF kappa B) is an essential component of the IL-1 beta-dependent upregulation of PLA2 gene transcription. By electrophoretic mobility shift analysis, we demonstrated that cyclosporin A diminishes the formation of NF kappa B DNA-binding complexes, thus suggesting that this transcription factor is a target for cyclosporin A-mediated repression of PLA2 gene transcription. 6. The data presented in this study strongly suggest that the cellular mechanism involved in the IL1 beta-dependent transcriptional upregulation of the PLA2 gene in mesangial cells is a target for the action of cyclosporin A.
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Affiliation(s)
- G Walker
- 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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Walker G, Kunz D, Pignat W, Wiesenberg I, Van den Bosch H, Pfeilschifter J. Tetranactin inhibits interleukin 1 beta and cAMP induction of group II phospholipase A2 in rat renal mesangial cells. Eur J Pharmacol 1996; 306:265-70. [PMID: 8813640 DOI: 10.1016/0014-2999(96)00203-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Renal mesangial cells express secretory phospholipase A2 in response to two principal classes of activating signals that may interact in a synergistic fashion. These two groups of activators comprise inflammatory cytokines, such as interleukin 1 beta, and agents that elevate cellular levels of cAMP. Treatment of mesangial cells with tetranactin, a cyclic antibiotic produced by Streptomyces aureus with a molecular structure similar to cyclosporin A inhibits interleukin 1 beta- and cAMP-dependent group II phospholipase A2 secretion in a dose-dependent manner with IC50 values of 43 and 33 nM, respectively. However, tetranactin does not directly inhibit group II phospholipase A2 activity. Western blot analyses of mesangial cell supernatants reveal that the inhibition of phospholipase A2 activity is due to suppression of phospholipase A2 protein synthesis. This effect is preceded by the reduction of phospholipase A2 mRNA steady-state levels as shown by Northern blot analyses of total cellular RNA isolated from stimulated mesangial cells. Thus, tetranactin is a potent inhibitor of group II phospholipase A2 expression in cytokine- and cAMP-stimulated mesangial cells and represents a new class of group II phospholipase A2 inhibitors with IC50 values in the low nanomolar range. This compound may be useful in the therapy of diseases associated with increased group II phospholipase A2 secretion.
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Affiliation(s)
- G Walker
- Department of Pharmacology, Biozentrum, Universität Basel, Switzerland
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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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Vervoordeldonk MJ, Schalkwijk CG, Vishwanath BS, Aarsman AJ, van den Bosch H. Levels and localization of group II phospholipase A2 and annexin I in interleukin- and dexamethasone-treated rat mesangial cells: evidence against annexin mediation of the dexamethasone-induced inhibition of group II phospholipases A2. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1224:541-50. [PMID: 7803514 DOI: 10.1016/0167-4889(94)90292-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The mechanism by which glucocorticosteroids inhibit the synthesis and secretion of pro-inflammatory arachidonate metabolites is still controversial. Initially it was postulated that glucocorticoids can induce the formation of PLA2 inhibitory proteins termed annexins. We have previously shown that the cytokine-induced 14 kDa PLA2 activity and the synthesis of prostaglandin E2 in rat mesangial cells is dose-dependently blocked by pretreatment of the cells with dexamethasone (Schalkwijk et al. (1991) Biochem. Biophys. Res. Commun. 180, 46-52). Concurrently, the synthesis of 14 kDa group II PLA2 is suppressed. The regulation of PLA2 activity is complex and may well involve superimposable mechanisms. Thus, although the decrease in PLA2 protein levels could in itself explain the dexamethasone-induced decrease in PLA2 activity, a contribution of the glucocorticoid-induced anti-phospholipase A2 protein annexin cannot be ruled out a priori. To investigate this possibility we analyzed the level of annexin I by Western blotting and immunostaining in mesangial cells treated with interleukin-1 beta and/or dexamethasone. Under conditions where 14 kDa group II PLA2 activity and protein levels were dramatically affected by interleukin-1 and dexamethasone, the level of annexin I in the cells remained constant. Dexamethasone also did not induce the secretion of annexin I. In addition, no evidence for dexamethasone-induced translocation of annexin I from the cytosol to membranes, thereby possibly sequestering the substrates for PLA2, was obtained. Immunofluorescence studies localized the cytokine-induced PLA2 to the Golgi area and punctate structures in the cytoplasm. We have also studied the subcellular localization of annexin I in rat mesangial cells using confocal microscopy. These studies located annexin I mainly in the cytoplasma and the nucleus. We conclude from these experiments that the dexamethasone-induced inhibition of 14 kDa group II PLA2 in rat mesangial cells is not mediated by annexin I and is solely due to the suppression of PLA2 gene expression.
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Rao GN, Lassègue B, Alexander RW, Griendling KK. Angiotensin II stimulates phosphorylation of high-molecular-mass cytosolic phospholipase A2 in vascular smooth-muscle cells. Biochem J 1994; 299 ( Pt 1):197-201. [PMID: 8166641 PMCID: PMC1138041 DOI: 10.1042/bj2990197] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Phospholipase A2 (PLA2) may be one of the major components involved in cell signalling and proliferation, as suggested by recent studies. In this paper we show that the potent vasoconstrictor and hypertrophic agent angiotensin II (AngII) activates cytosolic PLA2 (cPLA2) in vascular smooth-muscle cells. AngII induced a rapid time-dependent release of [3H]arachidonic acid from prelabelled cells that was inhibited by mepacrine, a PLA2 inhibitor. AngII treatment of intact cells also activated a cPLA2, as measured in cell-free extracts by the release of radiolabelled arachidonic acid from exogenously added 1-stearoyl-2-[1-14C]arachidonoyl phosphatidylcholine. This AngII-stimulated cPLA2 activity was also significantly inhibited by mepacrine. AngII induced a rapid and time-dependent increase in cPLA2 phosphorylation. Protein kinase C (PKC) depletion inhibited both AngII-induced [3H]arachidonic acid release and cPLA2 phosphorylation. Together, these results suggest strongly that (1) AngII phosphorylates and activates cPLA2 in a PKC-dependent manner, and that (2) cPLA2 mediates the AngII-induced [3H]arachidonic acid release in vascular smooth-muscle cells.
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Affiliation(s)
- G N Rao
- Division of Cardiology, Emory University School of Medicine, Atlanta, GA 30322
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15
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Pfeilschifter J, Schalkwijk C, Briner VA, van den Bosch H. Cytokine-stimulated secretion of group II phospholipase A2 by rat mesangial cells. Its contribution to arachidonic acid release and prostaglandin synthesis by cultured rat glomerular cells. J Clin Invest 1993; 92:2516-23. [PMID: 8227364 PMCID: PMC288437 DOI: 10.1172/jci116860] [Citation(s) in RCA: 183] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Potent pro-inflammatory cytokines, such as interleukin 1 (IL-1) or tumor necrosis factor (TNF) alpha have been found to increase group II phospholipase A2 (PLA2) synthesis and secretion by mesangial cells. In all cases 85-90% of the enzyme is secreted from the cells and a parallel increase in prostaglandin (PG)E2 synthesis is observed. We report here that co-incubation with a monoclonal antibody that specifically binds and neutralizes rat group II PLA2 attenuates IL-1 beta and TNF alpha-stimulated PGE2 production by 45% and 52%, respectively. CGP43182, a specific inhibitor of group II PLA2, potently blocks mesangial cell group II PLA2 in vitro with a half-maximal inhibitory concentration (IC50) of 1.5 microM, while only slightly affecting mesangial cell high molecular weight PLA2. CGP 43182 markedly attenuates IL-1 beta- and TNF alpha-stimulated PGE2 synthesis in intact mesangial cells with IC50's of 1.3 and 1.0 microM, respectively. PLA2 secreted from cytokine-stimulated mesangial cells was purified to homogeneity. Addition of the purified enzyme to unstimulated mesangial cells causes a marked release of arachidonic acid and a subsequent increased synthesis of PGE2. Moreover, addition of purified PLA2 to a cloned rat glomerular epithelial cell line and cultured bovine glomerular endothelial cells augmented both arachidonic acid release and PGE2 synthesis, with the endothelial cells being especially sensitive. Thus, cytokine-triggered synthesis and secretion of group II PLA2 by mesangial cells contributes, at least in part, to the observed synthesis of PGE2 that occurs in parallel to the enzyme secretion. Furthermore, extracellular PLA2 secreted by mesangial cells is able to stimulate arachidonic acid release and PGE2 synthesis by the adjacent endothelial and epithelial cells. These data suggest that expression and secretion of group II PLA2 triggered by pro-inflammatory cytokines may crucially participate in the pathogenesis of inflammatory processes within the glomerulus.
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Affiliation(s)
- J Pfeilschifter
- Department of Pharmacology, University of Basel, Switzerland
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16
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Sánchez RM, Vervoordeldonk MJ, Schalkwijk CG, van den Bosch H. Prevention of the induced synthesis and secretion of group II phospholipase A2 by brefeldin A. FEBS Lett 1993; 332:99-104. [PMID: 8405456 DOI: 10.1016/0014-5793(93)80492-d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Brefeldin A (BFA) has previously been shown to block protein secretion and to cause dismantling of the Golgi cisternae in many cultured cell lines. BFA was found to prevent the induced synthesis and secretion of 14 kDa group II phospholipase A2 (PLA2) in rat mesangial cells. Furthermore, BFA inhibited total protein synthesis although PLA2 appeared to be more sensitive to the effect of this compound than total protein synthesis assessed by amino acid incorporation. BFA was unable to block protein synthesis or PLA2 activity in the cell completely but secretion of enzymatic activity and PLA2 protein into the cell culture media was totally inhibited.
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Affiliation(s)
- R M Sánchez
- Centre for Biomembranes and Lipid Enzymology, Utrecht University, The Netherlands
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17
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Van Schaik RH, Verhoeven NM, Neijs FW, Aarsman AJ, Van den Bosch H. Cloning of the cDNA coding for 14 kDa group II phospholipase A2 from rat liver. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1169:1-11. [PMID: 7916625 DOI: 10.1016/0005-2760(93)90075-k] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The amino acid sequence of rat liver phospholipase A2 was partially elucidated using peptide fragments generated by enzymatic or chemical cleavage. Based on this sequence information, two oligonucleotide probes were constructed which were applied in a polymerase chain reaction on cDNA generated from rat liver total RNA. This resulted in cloning of the cDNA corresponding to the coding region of the mature phospholipase A2. The deduced amino acid sequence showed the enzyme belongs to the group II phospholipases, and is almost completely identical to rat platelet and spleen membrane-associated phospholipase A2. However, in the cDNA isolated one codon was different as compared to the platelet and spleen enzymes, resulting in the substitution of Ala94 by Arg94 in the liver enzyme. In Northern blot analyses the mRNA for rat group II phospholipase A2 could not be detected in rat liver, neither in total RNA nor in poly(A)+ RNA. However, a polymerase chain reaction using total RNA originating from freshly isolated hepatocytes resulted in the amplification of the described phospholipase A2 cDNA. This indicates that group II PLA2 mRNA is present in these cells, but presumably at very low abundance. The observed increase in rat group II phospholipase A2 secretion in rat mesangial cells upon stimulation with interleukin-1 beta (Pfeilschifter et al. (1989), Biochem. Biophys. Res. Commun. 159, 385-394) was shown to be accompanied by an increased transcription of the rat group II phospholipase A2 gene, indicating interleukin exerts its effect via increased phospholipase A2 mRNA synthesis. Based on Northern blot analyses of stimulated rat mesangial cells, the size of the mRNA for rat group II phospholipase A2 was determined to be 0.9 kb.
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Affiliation(s)
- R H Van Schaik
- Centre for Biomembranes and Lipid Enzymology, Utrecht University, The Netherlands
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18
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Tojo H, Ono T, Okamoto M. Reverse-phase high-performance liquid chromatographic assay of phospholipases: application of spectrophotometric detection to rat phospholipase A2 isozymes. J Lipid Res 1993. [DOI: 10.1016/s0022-2275(20)39704-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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19
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van Schaik RH, van den Koeduk CD, Neijs FW, Aarsman AJ, van den Bosch H. Monoclonal antibodies against rat liver mitochondrial phospholipase A2: epitope analysis and application in western blotting. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1993; 25:433-9. [PMID: 7681788 DOI: 10.1016/0020-711x(93)90636-s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
1. Eight cell-lines producing monoclonal antibodies, raised against rat liver mitochondrial phospholipase A2, were investigated with respect to epitope-recognition. It was shown that all antibodies tested were directed to an identical epitope. 2. This epitope is a conformational one, since treatment of phospholipase A2 with the reducing agent dithiothreitol lowered the antibody binding significantly. 3. To increase sensitivity, Western blot analyses have to be performed on protein samples lacking dithiothreitol or beta-mercaptoethanol. The conditions described in this report allow the detection of the phospholipase A2 in rat liver homogenates. 4. When rat liver mitochondrial phospholipase A2 was purified by Ultrogel AcA 54 gel filtration, a nearly homogeneous protein preparation was obtained, as judged by SDS-PAGE. Western blot analysis of this preparation, however, clearly indicated the phospholipase A2 to correspond to a hardly visible protein band.
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Affiliation(s)
- R H van Schaik
- Center for Biomembranes and Lipid Enzymology, University Utrecht, 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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Rönkkö S. Immunohistochemical localization of phospholipase A2 in the bovine seminal vesicle and on the surface of the ejaculated spermatozoa. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1992; 24:869-76. [PMID: 1612177 DOI: 10.1016/0020-711x(92)90091-e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. Approximately 150-fold purified phospholipase A2 (PLA2) from bovine seminal vesicle fluid was injected into rabbit to prepare antibodies. 2. Produced antisera blocked PLA2 activity in bovine seminal plasma, seminal vesicles and its fluid and it gave single precipitation lines with the same samples. No cross-reactivity was detected with other reproductive tissues of bull as well as human seminal plasma. 3. Using indirect peroxidase technique PLA2 was localized in the apical part of epithelia cells of the bull seminal vesicle and also some minor immunohistochemical reactions were observed in the tubular lumen. Indirect peroxidase staining gave weak or no reaction at all to seminal vesicles of immature bulls. This suggests that the enzyme may be under hormonal control. 4. By indirect immunofluorescence method ejaculated spermatozoa of bull revealed immunoreaction which was not uniform and it was restricted to the middle piece, acrosome as well as postacrosomal region, but no specific immunostaining could be found on the surface of the epididymal spermatozoa. 5. Enzyme visualization by immunoelectron microscopic labelling showed a predominant localization in membrane particles inside the lumen of bovine seminal vesicle but some gold particles were also seen in granules, larger vacuoles and in cytoplasm of epithelia cells.
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Affiliation(s)
- S Rönkkö
- Department of Anatomy, University of Kuopio, Finland
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23
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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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24
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Kortesuo PT, Nevalainen TJ, Büchler M, Uhl W. Characterization of two phospholipases A2 in serum of patients with sepsis and acute pancreatitis. EUROPEAN JOURNAL OF CLINICAL CHEMISTRY AND CLINICAL BIOCHEMISTRY : JOURNAL OF THE FORUM OF EUROPEAN CLINICAL CHEMISTRY SOCIETIES 1992; 30:263-9. [PMID: 1627722 DOI: 10.1515/cclm.1992.30.5.263] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pancreatic phospholipase A2 and non-pancreatic ascitic phospholipases A2 were studied in sera of healthy individuals and of patients suffering from sepsis or acute pancreatitis. In gel filtration experiments, immunoreactive ascitic phospholipase A2, as determined in serum by a time-resolved fluoroimmunoassay, eluted either unassociated with an apparent M(r) of 10,000-14,000 or associated with proteins of high molecular mass. Catalytically active ascitic phospholipase A2 was associated with high molecular weight proteins. In acute pancreatitis the catalytically active and immunoreactive pancreatic phospholipase A2 eluted mainly as a protein of M(r) of 14,000. The results of the gel filtration experiments indicate that pancreatic phospholipase A2 is not associated with other proteins in human serum, whereas ascitic phospholipase A2 is associated with protein(s) of relative high molecular weight, or exists in different polymeric forms. We also purified phospholipase A2 from sera of healthy individuals by ion exchange chromatography and HPLC. The enzyme was homogenous, displayed an M(r) of approximately 13,500 as judged by SDS-polyacrylamide gel electrophoresis, and reacted with an antibody raised against ascitic phospholipase A2.
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Affiliation(s)
- P T Kortesuo
- Department of Pathology, University of Turku, Finland
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25
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van den Bosch H, Schalkwijk C, Pfeilschifter J, Märki F. The induction of cellular group II phospholipase A2 by cytokines and its prevention by dexamethasone. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1992; 318:1-10. [PMID: 1636484 DOI: 10.1007/978-1-4615-3426-6_1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Treatment of rat glomerular mesangial cells with interleukin-1 beta, tumor necrosis factor or forskolin resulted in the secretion of phospholipase A2 activity into the culture medium. Essentially all of this secreted phospholipase A2 activity was recognized by monoclonal antibodies elicited against rat liver mitochondrial 14 kDa group II phospholipase A2. Immunoblot analysis and gel filtration confirmed the presence of only 14 kDa phospholipase A2 in the culture supernatant. This enzyme could hardly be detected in unstimulated mesangial cells and after a lag period of 6 to 8 hours becomes detectable in both cells and culture medium. The results indicate that the increased phospholipase A2 activity upon treatment of the cells with cytokines is not due to activation of an existing cellular pool of enzyme but is caused by induced synthesis of group II phospholipase A2. Pretreatment of the cells with dexamethasone, a known inhibitor of prostaglandin synthesis, dose-dependently inhibits cytokine-induced phospholipase A2 activity. Western immunoblot analysis of cells and culture medium demonstrates that this is not due to inhibition of existing phospholipase A2 but because dexamethasone prevents the cytokine-induced synthesis of phospholipase A2 protein.
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Affiliation(s)
- H van den Bosch
- Centre for Biomembranes and Lipid Enzymology, Utrecht, The Netherlands
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26
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Stoner CR, Reik LM, Donohue M, Levin W, Crowl RM. Human group II phospholipase A2. Characterization of monoclonal antibodies and immunochemical quantitation of the protein in synovial fluid. J Immunol Methods 1991; 145:127-36. [PMID: 1722494 DOI: 10.1016/0022-1759(91)90318-a] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Murine monoclonal and rabbit polyclonal antibodies were generated against human group II phospholipase A2 (PLA2) in order to study the role of this enzyme in inflammatory disease, the source of its synthesis, and the interaction of PLA2 with its substrate. Monoclonal antibody PLA187 exhibits potent inhibitory activity toward human PLA2 using autoclaved E. coli membranes as the substrate. Three other monoclonal antibodies (PLA184, PLA185, and PLA186) also inhibit enzyme activity, but with about 50-fold less potency. Based on the results of double-antibody competition experiments and enzyme inhibition profiles, PLA184 and PLA185 appear to recognize the same epitope. Monoclonal antibody PLA186 recognizes an epitope which is spatially distinct from that recognized by PLA184/185. The results also suggest that the epitope recognized by PLA187 may overlap with both epitopes recognized by PLA186 and PLA184/185. A double-antibody sandwich ELISA was developed using a combination of PLA185 and rabbit polyclonal antibody against PLA2. The ELISA provides a sensitive and quantitative method for monitoring specifically group II PLA2 in various biological sources, independent of factors which may affect enzyme activity. We have utilized this assay to quantitate PLA2 levels in synovial fluid from the joints of individuals with rheumatoid arthritis as well as from non-arthritic joints. Our results indicate that elevated levels of group II PLA2 in synovial fluid are not necessarily associated with arthritis.
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Affiliation(s)
- C R Stoner
- Department of Molecular Genetics, Hoffmann-La Roche Inc., Nutley, NJ 07110-1199
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27
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Mühl H, Geiger T, Pignat W, Märki F, van den Bosch H, Vosbeck K, Pfeilschifter J. PDGF suppresses the activation of group II phospholipase A2 gene expression by interleukin 1 and forskolin in mesangial cells. FEBS Lett 1991; 291:249-52. [PMID: 1936271 DOI: 10.1016/0014-5793(91)81295-j] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Treatment of rat mesangial cells with interleukin 1 beta (IL-1 beta) and forskolin greatly enhanced the expression of group II phospholipase A2 (PLA2) mRNA, with subsequent increased synthesis and secretion of PLA2, as detected by PLA2 activity measurements and immunoprecipitation of culture media of [35S]methionine-labelled mesangial cells. PDGF-BB dose-dependently suppressed the IL-1 beta- and forskolin-induced elevation of PLA2 mRNA, as well as PLA2 synthesis and secretion. In contrast, PDGF-AA had no inhibitory effect. The tyrosine kinase inhibitor genistein dose-dependently antagonized the inhibitory effect of PDGF-BB on IL-1 beta-stimulated PLA2 secretion, thus suggesting that tyrosine phosphorylation may be required for PDGF-BB inhibition of PLA2 gene expression in mesangial cells.
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Affiliation(s)
- H Mühl
- Research Department, Ciba-Geigy Ltd., Basel, Switzerland
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28
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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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29
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Inada M, Tojo H, Kawata S, Tarui S, Okamoto M. Preferential distribution of group-II-like phospholipase A2 in mononuclear phagocytic cells in rat spleen and liver. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 197:323-9. [PMID: 2026155 DOI: 10.1111/j.1432-1033.1991.tb15914.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The localization of calcium-dependent phospholipase A2, (PLA2) immunochemically closely related to the enzyme of the viperid and crotalid type (group II), in cells isolated from rat spleen and liver was examined using a polyclonal antibody directed against rat spleen group II, PLA2 (PLA2M). In isolated spleen cells, the monocyte/macrophage fraction had the highest PLA2 activity (1.28 +/- 0.35.min-1.10(6) cells-1) which was almost completely inhibited by the anti-PLA2M antibody. An immunoblot analysis confirmed the presence of the enzyme in this fraction. An immunocytochemical study revealed that the PLA2 was present in spleen macrophages. In the isolated liver cells, Kupffer cells (0.92 +/- 0.22 nmol.min-1.10(6) cells-1) contained higher anti-PLA2M-antibody-inhibitable PLA2 activity than parenchymal cells (0.26 +/- 0.06.min-1.10(6) cells-1). The immunocytochemical study showed that cells immunopositive with anti PLA2M antibody were Kupffer cells. These results suggest that the mononuclear phagocytic cells in rat spleen and liver have relatively high activity of group-II-like PLA2. Subcellular distribution patterns of the anti-PLA2M-antibody-inhibitable phospholipase A2 activity in different cell populations from spleen and liver were compared. A mode of the distribution of the enzyme in the spleen macrophages was essentially similar to that in the spleen lymphocytes. The distribution in Kupffer cells was similar to that in parenchymal cells.
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Affiliation(s)
- M Inada
- Second Department of Internal Medicine School, Osaka University Medical School, Japan
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30
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Affiliation(s)
- J V Bonventre
- Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Boston
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31
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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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32
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33
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Aulikki Santavuori S, Kortesuo PT, Eskola JU, Nevalainen TJ. Application of a New Monoclonal Antibody for Time-resolved Fluoroimmunoassay of Human Pancreatic Phospholipase A2. Clin Chem Lab Med 1991. [DOI: 10.1515/cclm.1991.29.12.819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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34
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Gronich JH, Bonventre JV, Nemenoff RA. Purification of a high-molecular-mass form of phospholipase A2 from rat kidney activated at physiological calcium concentrations. Biochem J 1990; 271:37-43. [PMID: 2121134 PMCID: PMC1149511 DOI: 10.1042/bj2710037] [Citation(s) in RCA: 154] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Rat kidney contains a soluble phospholipase A2 (PLA2), which is chromatographically identical with a previously identified hormonally regulated form of the enzyme in rat renal mesangial cells. This kidney enzyme has been purified by sequential column fractionation. The purified enzyme is a 110 kDa polypeptide which can hydrolyse arachidonoyl phosphatidylcholine and arachidonoyl phosphatidylethanolamine, but has low activity towards arachidonoyl phosphatidylinositol. The enzyme is considerably larger than most previously isolated forms of secretory or intracellular PLA2, and is stimulated by physiological concentrations of Ca2+, with half-maximal activation occurring at 500 nM-Ca2+. The hormonal regulation and Ca2(+)-dependency of this enzyme strongly suggest that it plays a role in hormonally regulated arachidonic acid release and prostaglandin production in the kidney.
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Affiliation(s)
- J H Gronich
- Medical Services, Massachusetts General Hospital, Boston
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35
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Murakami M, Kudo I, Natori Y, Inoue K. Immunochemical detection of 'platelet type' phospholipase A2 in the rat. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1043:34-42. [PMID: 2310758 DOI: 10.1016/0005-2760(90)90107-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Polyclonal antibodies were raised against rat platelet phospholipase A2. One of them, designated as R377 was prepared by immunizing a rabbit with the intact enzyme. The other antibody, designated as R385, was prepared by immunizing with the enzyme treated with 2-mercaptoethanol. The antibody R377 bound to rat platelet phospholipase A2 almost exclusively, while the antibody R385 reacted not only with rat platelet phospholipase A2 but with the enzymes obtained from snake venom or mammalian pancreas. The antibody R377 bound to the non-reduced rat platelet phospholipase A2 bearing intact intramolecular disulfide bonds, but not to the reduced enzyme. In contrast, the antibody R385 reacted with both non-reduced and reduced enzymes. R377 may recognize the conformational structure of the enzyme. Both antibodies inhibited the enzyme activity. The antibody R377, but not R385, interfered with the interaction of the enzyme with heparin, which is one of the characteristic properties of rat platelet phospholipase A2. The antibody R377 reacted with phospholipases A2 of bone-marrow cells and of peritoneal exudated cells prepared from caseinate-treated rats, indicating that some myeloid cells other than platelets also contain 'platelet type' phospholipase A2. An immunochemical method for measurement of rat 'platelet type' phospholipase A2 was developed. The sensitivity of this method was 10 ng/ml of phospholipase A2 in the preparation. One of the advantages of the present immunochemical method is that the measurement was not affected by the presence of an endogenous inhibitor(s) of enzymatic activity.
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Affiliation(s)
- M Murakami
- Department of Health Chemistry, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan
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36
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Osthoff G, Nel AJ. Far-UV CD spectroscopy, IR spectroscopy, and immunological properties of synthetic peptides, including an amphipathic alpha-helical peptide from bovine phospholipase A2. Biopolymers 1990; 29:311-6. [PMID: 1691928 DOI: 10.1002/bip.360290203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The immunological properties of bovine phospholipase A2 were investigated in order to locate possible sequential epitopes. Polyvalent antiserum raised against the enzyme was tested for its interaction with synthetic peptides derived from regions adopting hydrogen-bonded secondary structures within the tertiary structure of phospholipase A2. The conformations of each peptide in various solvents were determined by CD and ir spectroscopy in order to relate immunological to structural properties. It was found that sequential epitopes are absent in this enzyme, but that region 90-109 could be a possible T-cell epitope through the formation of an amphipathic alpha-helix.
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Affiliation(s)
- G Osthoff
- Division of Processing and Chemical Manufacturing Technology, CSIR, Pretoria, Republic of South Africa
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37
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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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38
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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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39
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Danse JM, Kempf J. Preparation and characterization of monoclonal antibodies against beta-bungarotoxin and its A- and B-chains. Toxicon 1989; 27:1011-9. [PMID: 2799834 DOI: 10.1016/0041-0101(89)90152-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Splenocytes from Balb/c mice immunized with beta-bungarotoxin, a protein neurotoxin that exhibits phospholipase A2 activity, were fused with SP2/0 murine myeloma cells. Eighty-seven stable hybridoma cell lines were established which secrete monoclonal antibodies of the subclass IgG1 and K light chain and react with intact neurotoxin. Some antibodies were further analyzed. These recognize at least two immuno-dominant regions located on the A- and B-chains of the toxin, and the native toxin but show no crossreactivity with a protein homologous to chain A (porcine pancreas phospholipase A2) nor to chain B (toxin 1 from Dendroaspis polylepis). Two monoclonal antibodies inhibit phospholipase A2 activity of the neurotoxin but only one partially neutralizes its biological activity when injected together with the toxin, delaying the time of death.
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Affiliation(s)
- J M Danse
- INSERM U-184, Institut de Chimie Biologique, Faculté de Médecine, Strasbourg, France
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40
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Identification and characterization of a hormonally regulated form of phospholipase A2 in rat renal mesangial cells. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37439-8] [Citation(s) in RCA: 142] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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41
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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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42
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43
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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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Purification and characterization of a membrane-associated phospholipase A2 from rat spleen. Its comparison with a cytosolic phospholipase A2 S-1. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)60626-x] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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45
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Masliah J, Kadiri C, Pepin D, Rybkine T, Etienne J, Chambaz J, Bereziat G. Antigenic relatedness between phospholipases A2 from Naja naja venom and from mammalian cells. FEBS Lett 1987; 222:11-6. [PMID: 2443388 DOI: 10.1016/0014-5793(87)80182-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Polyclonal antiserum was prepared against phospholipase A2 from Naja naja and used to prepare a purified antibody. It cross-reacted with the antigen, and with intracellular mammalian PLA2. This antibody was immunoreactive and inhibited the PLA2 activity of Naja naja and of guinea pig alveolar macrophages or rat lymphocytes. By immunoblotting, this antiserum revealed one band of PLA2 from Naja naja (14 kDa) and 3 bands for guinea pig alveolar macrophages and rat lymphocytes (30, 45 kDa and a minor band of 14 kDa). These results show an antigenic relatedness between an extracellular PLA2 and membrane-bound PLA2 from two different mammalian species and cell types.
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Affiliation(s)
- J Masliah
- UA 524 CNRS, CHU Saint-Antoine, Paris, France
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