Site-specific epsilon-NH2 monoacylation of pancreatic phospholipase A2. 2. Transformation of soluble phospholipase A2 into a highly penetrating "membrane-bound" form.

Science.gov (United States)

Van der Wiele, F C; Atsma, W; Roelofsen, B; van Linde, M; Van Binsbergen, J; Radvanyi, F; Raykova, D; Slotboom, A J; De Haas, G H

1988-03-08

Long-chain lecithins present in bilayer structures like vesicles or membranes are only very poor substrates for pancreatic phospholipases A2. This is probably due to the fact that pancreatic phospholipases A2 cannot penetrate into the densely packed bilayer structures. To improve the weak penetrating properties of pancreatic phospholipases A2, we prepared and characterized a number of pancreatic phospholipase A2 mutants that have various long acyl chains linked covalently to Lys116 in porcine and to Lys10 in bovine phospholipase A2 [Van der Wiele, F.C., Atsma, W., Dijkman, R., Schreurs, A.M.M., Slotboom, A.J., & De Haas, G.H. (1988) Biochemistry (preceding paper in this issue)]. When monomolecular surface layers of L- and D-didecanoyllecithin were used, it was found that the introduction of caprinic, lauric, palmitic, and oleic acid at Lys116 in the porcine enzyme increases its penetrating power from 13 to about 17, 20, 32, and 22 dyn/cm, respectively, before long lag periods were obtained. Incorporation of a palmitoyl moiety at Lys10 in the bovine enzyme shifted the penetrating power from 11 to about 25 dyn/cm. Only the best penetrating mutant, viz., porcine phospholipase A2 having a palmitoyl moiety at Lys116, was able to cause complete leakage of 6-carboxyfluorescein entrapped in small unilamellar vesicles of egg lecithin under nonhydrolytic conditions. Similarly, only this latter palmitoylphospholipase A2 completely hydrolyzed all lecithin in the outer monolayer of the human erythrocyte at a rate much faster than Naja naja phospholipase A2, the most powerful penetrating snake venom enzyme presently known.

Cytosolic phospholipase A2 alpha amplifies early cyclooxygenase-2 expression, oxidative stress and MAP kinase phosphorylation after cerebral ischemia in mice

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Koehler Raymond C

2010-07-01

Full Text Available Abstract Background The enzyme cytosolic phospholipase A2 alpha (cPLA2α has been implicated in the progression of cerebral injury following ischemia and reperfusion. Previous studies in rodents suggest that cPLA2α enhances delayed injury extension and disruption of the blood brain barrier many hours after reperfusion. In this study we investigated the role of cPLA2α in early ischemic cerebral injury. Methods Middle cerebral artery occlusion (MCAO was performed on cPLA2α+/+ and cPLA2α-/- mice for 2 hours followed by 0, 2, or 6 hours of reperfusion. The levels of cPLA2α, cyclooxygenase-2, neuronal morphology and reactive oxygen species in the ischemic and contralateral hemispheres were evaluated by light and fluorescent microscopy. PGE2 content was compared between genotypes and hemispheres after MCAO and MCAO and 6 hours reperfusion. Regional cerebral blood flow was measured during MCAO and phosphorylation of relevant MAPKs in brain protein homogenates was measured by Western analysis after 6 hours of reperfusion. Results Neuronal cPLA2α protein increased by 2-fold immediately after MCAO and returned to pre-MCAO levels after 2 hours reperfusion. Neuronal cyclooxygenase-2 induction and PGE2 concentration were greater in cPLA2α+/+ compared to cPLA2α-/- ischemic cortex. Neuronal swelling in ischemic regions was significantly greater in the cPLA2α+/+ than in cPLA2α-/- brains (+/+: 2.2 ± 0.3 fold vs. -/-: 1.7 ± 0.4 fold increase; P 2α+/+ ischemic core than in cPLA2α-/- (+/+: 7.12 ± 1.2 fold vs. -/-: 3.1 ± 1.4 fold; P 2α+/+, but not cPLA2α-/-, had disruption of neuron morphology and decreased PGE2 content. Phosphorylation of the MAPKs-p38, ERK 1/2, and MEK 1/2-was significantly greater in cPLA2a+/+ than in cPLA2α-/- ischemic cortex 6 hours after reperfusion. Conclusions These results indicate that cPLA2α modulates the earliest molecular and injury responses after cerebral ischemia and have implications for the potential clinical

Cytosolic phospholipase A2: a member of the signalling pathway of a new G protein α subunit in Sporothrix schenckii

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González-Méndez Ricardo

2009-05-01

Full Text Available Abstract Background Sporothrix schenckii is a pathogenic dimorphic fungus, the etiological agent of sporotrichosis, a lymphocutaneous disease that can remain localized or can disseminate, involving joints, lungs, and the central nervous system. Pathogenic fungi use signal transduction pathways to rapidly adapt to changing environmental conditions and S. schenckii is no exception. S. schenckii yeast cells, either proliferate (yeast cell cycle or engage in a developmental program that includes proliferation accompanied by morphogenesis (yeast to mycelium transition depending on the environmental conditions. The principal intracellular receptors of environmental signals are the heterotrimeric G proteins, suggesting their involvement in fungal dimorphism and pathogenicity. Identifying these G proteins in fungi and their involvement in protein-protein interactions will help determine their role in signal transduction pathways. Results In this work we describe a new G protein α subunit gene in S. schenckii, ssg-2. The cDNA sequence of ssg-2 revealed a predicted open reading frame of 1,065 nucleotides encoding a 355 amino acids protein with a molecular weight of 40.9 kDa. When used as bait in a yeast two-hybrid assay, a cytoplasmic phospholipase A2 catalytic subunit was identified as interacting with SSG-2. The sspla2 gene, revealed an open reading frame of 2538 bp and encoded an 846 amino acid protein with a calculated molecular weight of 92.62 kDa. The principal features that characterize cPLA2 were identified in this enzyme such as a phospholipase catalytic domain and the characteristic invariable arginine and serine residues. A role for SSPLA2 in the control of dimorphism in S. schenckii is suggested by observing the effects of inhibitors of the enzyme on the yeast cell cycle and the yeast to mycelium transition in this fungus. Phospholipase A2 inhibitors such as AACOCF3 (an analogue of archidonic acid and isotetrandrine (an inhibitor of G protein

Secretory Phospholipase A2-IIA and Cardiovascular Disease

DEFF Research Database (Denmark)

Holmes, Michael V; Simon, Tabassome; Exeter, Holly J

2013-01-01

This study sought to investigate the role of secretory phospholipase A2 (sPLA2)-IIA in cardiovascular disease.......This study sought to investigate the role of secretory phospholipase A2 (sPLA2)-IIA in cardiovascular disease....

Inhibition of [3H]nitrendipine binding by phospholipase A2

International Nuclear Information System (INIS)

Goldman, M.E.; Pisano, J.J.

1985-01-01

Phospholipase A 2 from several sources inhibited [ 3 H]nitrendipine binding to membranes from brain, heart and ileal longitudinal muscle. The enzymes from bee venom and Russell's viper venom were most potent, having IC 50 values of approximately 5 and 14 ng/ml, respectively, in all three membrane preparations. Inhibition of binding by bee venom phospholipase A 2 was time- and dose-dependent. Mastoparan, a known facilitator of phospholipase A 2 enzymatic activity, shifted the bee venom phospholipase A 2 dose-response curve to the left. Pretreatment of brain membranes with bee venom phospholipase A 2 (10 ng/ml) for 15 min caused a 2-fold increase in the K/sub d/ without changing the B/sub max/ compared with untreated membranes. Extension of the preincubation period to 30 min caused no further increase in the K/sub d/ but significantly decreased the B/sub max/ to 71% the value for untreated membranes. [ 3 H]Nitrendipine, preincubated with bee venom phospholipase A 2 , was recovered and found to be fully active, indicating that the phospholipase A 2 did not modify the ligand. It is concluded that phospholipase A 2 acts on the membrane at or near the [ 3 H]nitrendipine binding site and that phospholipids play a key role in the interactions of 1,4 dihydropyridine calcium channel antagonists with the dihydropyridine binding site. 33 references, 3 figures, 1 table

Inhibition of cAMP-Dependent PKA Activates β2-Adrenergic Receptor Stimulation of Cytosolic Phospholipase A2 via Raf-1/MEK/ERK and IP3-Dependent Ca2+ Signaling in Atrial Myocytes.

Science.gov (United States)

Pabbidi, M R; Ji, X; Maxwell, J T; Mignery, G A; Samarel, A M; Lipsius, S L

2016-01-01

We previously reported in atrial myocytes that inhibition of cAMP-dependent protein kinase (PKA) by laminin (LMN)-integrin signaling activates β2-adrenergic receptor (β2-AR) stimulation of cytosolic phospholipase A2 (cPLA2). The present study sought to determine the signaling mechanisms by which inhibition of PKA activates β2-AR stimulation of cPLA2. We therefore determined the effects of zinterol (0.1 μM; zint-β2-AR) to stimulate ICa,L in atrial myocytes in the absence (+PKA) and presence (-PKA) of the PKA inhibitor (1 μM) KT5720 and compared these results with atrial myocytes attached to laminin (+LMN). Inhibition of Raf-1 (10 μM GW5074), phospholipase C (PLC; 0.5 μM edelfosine), PKC (4 μM chelerythrine) or IP3 receptor (IP3R) signaling (2 μM 2-APB) significantly inhibited zint-β2-AR stimulation of ICa,L in-PKA but not +PKA myocytes. Western blots showed that zint-β2-AR stimulation increased ERK1/2 phosphorylation in-PKA compared to +PKA myocytes. Adenoviral (Adv) expression of dominant negative (dn) -PKCα, dn-Raf-1 or an IP3 affinity trap, each inhibited zint-β2-AR stimulation of ICa,L in + LMN myocytes compared to control +LMN myocytes infected with Adv-βgal. In +LMN myocytes, zint-β2-AR stimulation of ICa,L was enhanced by adenoviral overexpression of wild-type cPLA2 and inhibited by double dn-cPLA2S505A/S515A mutant compared to control +LMN myocytes infected with Adv-βgal. In-PKA myocytes depletion of intracellular Ca2+ stores by 5 μM thapsigargin failed to inhibit zint-β2-AR stimulation of ICa,L via cPLA2. However, disruption of caveolae formation by 10 mM methyl-β-cyclodextrin inhibited zint-β2-AR stimulation of ICa,L in-PKA myocytes significantly more than in +PKA myocytes. We conclude that inhibition of PKA removes inhibition of Raf-1 and thereby allows β2-AR stimulation to act via PKCα/Raf-1/MEK/ERK1/2 and IP3-mediated Ca2+ signaling to stimulate cPLA2 signaling within caveolae. These findings may be relevant to the remodeling of �

40 CFR 721.4585 - Lecithins, phospholipase A2-hydrolyzed.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lecithins, phospholipase A2-hydrolyzed... Substances § 721.4585 Lecithins, phospholipase A2-hydrolyzed. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified generically as lecithins...

Quercetin modulates activities of Taiwan cobra phospholipase A 2 ...

Indian Academy of Sciences (India)

Home; Journals; Journal of Biosciences; Volume 37; Issue 2. Quercetin modulates activities of Taiwan cobra phospholipase A2 via its effects on membrane structure and membrane-bound mode of phospholipase A2. Yi-Ling Chiou Shinne-Ren Lin Wan-Ping Hu Long-Sen Chang. Articles Volume 37 Issue 2 June 2012 pp ...

Up-regulation of cytosolic phospholipase A2α expression by N,N-diethyldithiocarbamate in PC12 cells; involvement of reactive oxygen species and nitric oxide

International Nuclear Information System (INIS)

Akiyama, Nobuteru; Nabemoto, Maiko; Hatori, Yoshio; Nakamura, Hiroyuki; Hirabayashi, Tetsuya; Fujino, Hiromichi; Saito, Takeshi; Murayama, Toshihiko

2006-01-01

Disulfiram (an alcohol-aversive drug) and related compounds are known to provoke several side effects involving behavioral and neurological complications. N,N-diethyldithiocarbamate (DDC) is considered as one of the main toxic species of disulfiram and acts as an inhibitor of superoxide dismutase. Since arachidonic acid (AA) formation is regulated by reactive oxygen species (ROS) and related to toxicity in neuronal cells, we investigated the effects of DDC on AA release and expression of the α type of cytosolic phospholipase A 2 (cPLA 2 α) in PC12 cells. Treatment with 80-120 μM DDC that causes a moderate increase in ROS levels without cell toxicity stimulated cPLA 2 α mRNA and its protein expression. The expression was mediated by extracellular-signal-regulated kinase (ERK1/2), one of the mitogen-activated protein kinases. Treatment with N G nitro-L-arginine methyl ester (an inhibitor of nitric oxide synthase, 1 mM) and oxy-hemoglobin (a scavenger of nitric oxide, 2 mg/mL) abolished the DDC-induced responses (ERK1/2 phosphorylation and cPLA 2 α expression). We also showed DDC-induced up-regulation of the mRNA expression of lipocortin 1, an inhibitor of PLA 2 . Furthermore, DDC treatment of the cells enhanced Ca 2+ -ionophore-induced AA release in 30 min, although the effect was limited. Changes in AA metabolism in DDC-treated cells may have a potential role in mediating neurotoxic actions of disulfiram. In this study, we show the first to demonstrate the up-regulation of cPLA 2 α expression by DDC treatment in neuronal cells

Membrane associated phospholipase C from bovine brain

International Nuclear Information System (INIS)

Lee, K.; Ryu, S.H.; Suh, P.; Choi, W.C.; Rhee, S.G.

1987-01-01

Cytosolic fractions of bovine brain contain 2 immunologically distinct phosphoinositide-specific phospholipase (PLC), PLC-I and PLC-II, whose MW are 150,000 and 145,000 respectively, under a denaturing condition. Monoclonal antibodies were derived against each form and specific radioimmunoassays were developed. Distribution of PLC-I and PLC-II in cytosolic and particulate fractions was measured using the radioimmunoassay. More than 90% of PLC-II was found in the cytosolic fraction, while the anti-PLC-I antibody cross-reacting protein was distributed nearly equally between the soluble fraction and the 2 M KCl extract of particulate fraction. The PLC enzyme in the particulate fraction was purified to homogeneity, yielding 2 proteins of 140 KDa and 150 KDa when analyzed on SDS-PAGE. Neither of the 2 enzymes cross-reacted with anti-PLC-II antibodies, but both could be immunoblotted by all 4 different anti-PLC-I antibodies. This suggests that the 140 KDa PLC was derived from the 150 KDa form. The 150 Kda form from particulate fraction was indistinguishable from the cytosolic PLC-I when their mixture was analyzed on SDS-PAGE. In addition, the elution profile of tryptic peptides derived from the 150 KDa particulate form was identical to that of cytosolic PLC-I. This result indicates that PLC-I is reversibly associated to membranes

Purification of phospholipase A2 from Bothrops atrox venom

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B. Quevedo

1999-01-01

Full Text Available Phospholipase A2 (PLA2 from Bothrops atrox (Sensu lato venom, from Chiriguaná (Colombia was purified using exclusión chromatography on Sephadex G-75, obtaining five fractions one of which showed phospholipase A2 activity. After further purification on Mono S cationic exchange column, eight fractions with PLA2 activity, measured using the hemolytic method, were obtained.

Inhibition of (/sup 3/H)nitrendipine binding by phospholipase A/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Goldman, M.E.; Pisano, J.J.

1985-10-07

Phospholipase A/sub 2/ from several sources inhibited (/sup 3/H)nitrendipine binding to membranes from brain, heart and ileal longitudinal muscle. The enzymes from bee venom and Russell's viper venom were most potent, having IC/sub 50/ values of approximately 5 and 14 ng/ml, respectively, in all three membrane preparations. Inhibition of binding by bee venom phospholipase A/sub 2/ was time- and dose-dependent. Mastoparan, a known facilitator of phospholipase A/sub 2/ enzymatic activity, shifted the bee venom phospholipase A/sub 2/ dose-response curve to the left. Pretreatment of brain membranes with bee venom phospholipase A/sub 2/ (10 ng/ml) for 15 min caused a 2-fold increase in the K/sub d/ without changing the B/sub max/ compared with untreated membranes. Extension of the preincubation period to 30 min caused no further increase in the K/sub d/ but significantly decreased the B/sub max/ to 71% the value for untreated membranes. (/sup 3/H)Nitrendipine, preincubated with bee venom phospholipase A/sub 2/, was recovered and found to be fully active, indicating that the phospholipase A/sub 2/ did not modify the ligand. It is concluded that phospholipase A/sub 2/ acts on the membrane at or near the (/sup 3/H)nitrendipine binding site and that phospholipids play a key role in the interactions of 1,4 dihydropyridine calcium channel antagonists with the dihydropyridine binding site. 33 references, 3 figures, 1 table.

Functional interaction between Cerebratulus lacteus cytolysin A-III and phospholipase A2

International Nuclear Information System (INIS)

Liu, J.; Blumenthal, K.M.

1988-01-01

A study on the interaction between bee venom phospholipase A 2 and Cerebratulus lacteus cytolysin A-III, a major hemolysin secreted by this organism has been carried out. The hemolytic activity of A-III in phosphate-buffered saline is increased 5-fold in the presence of phospholipase A 2 from bee venom. Dansylphosphatidylethanolamine (DPE) labeled, phosphatidylcholine-containing liposomes and human erythrocyte membranes were employed to study the interaction between these two proteins. In DPE-liposomes, A-III alone had no effect on DPE fluorescence nor did it enhance either the phospholipase A 2 -dependent fluorescence increase or blue shift in emission maximum, indicating that the cytolysis is not a major phospholipase A 2 -activator. However, when DPE was incorporated into erythrocyte membranes, A-III alone induced a 40% fluorescence increase and a 5 nm blue shift, implying a transient activation of an endogenous phospholipase A 2 . Further studies using synthetic lysophosphatidylcholine and free fatty acids demonstrated that the hemolytic activity of A-III is potentiated by free fatty acids, a product of phospholipid degradation catalyzed by phospholipase A 2 . Subsequent analysis of this phenomenon by gel filtration chromatography, analytical ultracentrifugation, chemical cross-linking, and measurement of [ 14 C]oleic acid binding by the cytolysin demonstrated that binding of oleic acid to A-III causes aggregation of the toxin molecules to a tetrameric form which has a higher α-helix content and a greater activity than the monomer

Lactadherin inhibits secretory phospholipase A2 activity on pre-apoptotic leukemia cells.

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Steffen Nyegaard

Full Text Available Secretory phospholipase A2 (sPLA2 is a critical component of insect and snake venoms and is secreted by mammalian leukocytes during inflammation. Elevated secretory PLA2 concentrations are associated with autoimmune diseases and septic shock. Many sPLA2's do not bind to plasma membranes of quiescent cells but bind and digest phospholipids on the membranes of stimulated or apoptotic cells. The capacity of these phospholipases to digest membranes of stimulated or apoptotic cells correlates to the exposure of phosphatidylserine. In the present study, the ability of the phosphatidyl-L-serine-binding protein, lactadherin to inhibit phospholipase enzyme activity has been assessed. Inhibition of human secretory phospholipase A2-V on phospholipid vesicles exceeded 90%, whereas inhibition of Naja mossambica sPLA2 plateaued at 50-60%. Lactadherin inhibited 45% of activity of Naja mossambica sPLA2 and >70% of human secretory phospholipase A2-V on the membranes of human NB4 leukemia cells treated with calcium ionophore A23187. The data indicate that lactadherin may decrease inflammation by inhibiting sPLA2.

Functional interaction between Cerebratulus lacteus cytolysin A-III and phospholipase A/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Liu, J.; Blumenthal, K.M.

1988-05-15

A study on the interaction between bee venom phospholipase A/sub 2/ and Cerebratulus lacteus cytolysin A-III, a major hemolysin secreted by this organism has been carried out. The hemolytic activity of A-III in phosphate-buffered saline is increased 5-fold in the presence of phospholipase A/sub 2/ from bee venom. Dansylphosphatidylethanolamine (DPE) labeled, phosphatidylcholine-containing liposomes and human erythrocyte membranes were employed to study the interaction between these two proteins. In DPE-liposomes, A-III alone had no effect on DPE fluorescence nor did it enhance either the phospholipase A/sub 2/-dependent fluorescence increase or blue shift in emission maximum, indicating that the cytolysis is not a major phospholipase A/sub 2/-activator. However, when DPE was incorporated into erythrocyte membranes, A-III alone induced a 40% fluorescence increase and a 5 nm blue shift, implying a transient activation of an endogenous phospholipase A/sub 2/. Further studies using synthetic lysophosphatidylcholine and free fatty acids demonstrated that the hemolytic activity of A-III is potentiated by free fatty acids, a product of phospholipid degradation catalyzed by phospholipase A/sub 2/. Subsequent analysis of this phenomenon by gel filtration chromatography, analytical ultracentrifugation, chemical cross-linking, and measurement of (/sup 14/C)oleic acid binding by the cytolysin demonstrated that binding of oleic acid to A-III causes aggregation of the toxin molecules to a tetrameric form which has a higher ..cap alpha..-helix content and a greater activity than the monomer.

Some aspects of rat platelet and serum phospholipase A2 activities

NARCIS (Netherlands)

Aarsman, A.J.; Roosenboom, C.F.P.; Geffen, G.E.W. van; Bosch, H. van den

1985-01-01

Rat platelet lysate contained appreciable phospholipase A2 activity. In agreement with literature data this enzymatic activity eluted in the void volume of a Sephadex G-100 column. When the void volume peak was chromatographed over a Matrex gel blue A column, part of the phospholipase A2 activity

Piperine Inhibits the Activities of Platelet Cytosolic Phospholipase A2 and Thromboxane A2 Synthase without Affecting Cyclooxygenase-1 Activity: Different Mechanisms of Action Are Involved in the Inhibition of Platelet Aggregation and Macrophage Inflammatory Response

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Dong Ju Son

2014-08-01

Full Text Available PURPOSE: Piperine, a major alkaloid of black pepper (Piper nigrum and long pepper (Piper longum, was shown to have anti-inflammatory activity through the suppression of cyclooxygenase (COX-2 gene expression and enzyme activity. It is also reported to exhibit anti-platelet activity, but the mechanism underlying this action remains unknown. In this study, we investigated a putative anti-platelet aggregation mechanism involving arachidonic acid (AA metabolism and how this compares with the mechanism by which it inhibits macrophage inflammatory responses; METHODS: Rabbit platelets and murine macrophage RAW264.7 cells were treated with piperine, and the effect of piperine on the activity of AA-metabolizing enzymes, including cytosolic phospholipase A2 (cPLA2, COX-1, COX-2, and thromboxane A2 (TXA2 synthase, as well as its effect on AA liberation from the plasma membrane components, were assessed using isotopic labeling methods and enzyme immunoassay kit; RESULTS: Piperine significantly suppressed AA liberation by attenuating cPLA2 activity in collagen-stimulated platelets. It also significantly inhibited the activity of TXA2 synthase, but not of COX-1, in platelets. These results suggest that piperine inhibits platelet aggregation by attenuating cPLA2 and TXA2 synthase activities, rather than through the inhibition of COX-1 activity. On the other hand, piperine significantly inhibited lipopolysaccharide-induced generation of prostaglandin (PGE2 and PGD2 in RAW264.7 cells by suppressing the activity of COX-2, without effect on cPLA2; CONCLUSION: Our findings indicate that piperine inhibits platelet aggregation and macrophage inflammatory response by different mechanisms.

Secretory Phospholipase A(2) Activity toward Diverse Substrates

DEFF Research Database (Denmark)

Madsen, Jesper Jonasson; Linderoth, Lars; Subramanian, Arun Kumar

2011-01-01

We have studied secretory phospholipase A(2)-IIA (sPLA(2)) activity toward different phospholipid analogues by performing biophysical 1 characterizations and molecular dynamics simulations. The phospholipids were natural substrates, triple alkyl phospholipids, a prodrug anticancer etherlipid, and...

Phospholipases A2 in ocular homeostasis and diseases

DEFF Research Database (Denmark)

Wang, Jinmei; Kolko, Miriam; Kolko, Miriam

2010-01-01

Phospholipases A(2) (PLA(2)s) and its generation of second messengers play an important role in signal transduction, cell proliferation, cell survival and gene expression. At low concentrations mediators of PLA(2) activity have a variety of physiological effects whereas high levels of PLA(2) and ...

A rapid phospholipase A2 bioassay using 14C-oleate-labelled E. coli bacterias.

Science.gov (United States)

Meyer, T; von Wichert, P; Weins, D

1989-02-01

Two methods of phospholipase A2 determination using 14C-labelled E. coli bacterias as substrate were compared. One method works with a filter membrane for separation of cleaved 14C-oleate from remaining phospholipids, the other uses the well-known thin-layer chromatography for lipid analysis. Some features of human serum phospholipase A2 regarding pH and Ca2+ dependency were investigated. Possible sources of errors were discussed. It was shown that either method can differentiate between normal and pathologically elevated phospholipase A2 levels, but that the filter method is superior in terms of sensitivity and workload.

A nutrient-regulated, dual localization phospholipase A2 in the symbiotic fungus Tuber borchii

Science.gov (United States)

Soragni, Elisabetta; Bolchi, Angelo; Balestrini, Raffaella; Gambaretto, Claudio; Percudani, Riccardo; Bonfante, Paola; Ottonello, Simone

2001-01-01

Important morphogenetic transitions in fungi are triggered by starvation-induced changes in the expression of structural surface proteins. Here, we report that nutrient deprivation causes a strong and reversible up-regulation of TbSP1, a surface-associated, Ca2+-dependent phospholipase from the mycorrhizal fungus Tuber borchii. TbSP1 is the first phospholipase A2 to be described in fungi and identifies a novel class of phospholipid-hydrolyzing enzymes. The TbSP1 phospholipase, which is synthesized initially as a pre-protein, is processed efficiently and secreted during the mycelial phase. The mature protein, however, also localizes to the inner cell wall layer, close to the plasma membrane, in both free-living and symbiosis-engaged hyphae. It thus appears that a dual localization phospholipase A2 is involved in the adaptation of a symbiotic fungus to conditions of persistent nutritional limitation. Moreover, the fact that TbSP1-related sequences are present in Streptomyces and Neurospora, and not in wholly sequenced non-filamentous microorganisms, points to a general role for TbSP1 phospholipases A2 in the organization of multicellular filamentous structures in bacteria and fungi. PMID:11566873

Enhanced Activity and Altered Specificity of Phospholipase A2 by Deletion of a Surface Loop

NARCIS (Netherlands)

Kuipers, Oscar P.; Thunnissen, Marjolein M.G.M.; Geus, Pieter de; Dijkstra, Bauke W.; Drenth, Jan; Verheij, Hubertus M.; Haas, Gerard H. de

1989-01-01

Protein engineering and x-ray crystallography have been used to study the role of a surface loop that is present in pancreatic phospholipases but is absent in snake venom phospholipases. Removal of residues 62 to 66 from porcine pancreatic phospholipase A2 does not change the binding constant for

Secretory Phospholipase A(2)-IIA and Cardiovascular Disease

NARCIS (Netherlands)

Holmes, Michael V.; Simon, Tabassome; Exeter, Holly J.; Folkersen, Lasse; Asselbergs, Folkert W.; Guardiola, Montse; Cooper, Jackie A.; Palmen, Jutta; Hubacek, Jaroslav A.; Carruthers, Kathryn F.; Horne, Benjamin D.; Brunisholz, Kimberly D.; Mega, Jessica L.; Van Iperen, Erik P. A.; Li, Mingyao; Leusink, Maarten; Trompet, Stella; Verschuren, Jeffrey J. W.; Hovingh, G. Kees; Dehghan, Abbas; Nelson, Christopher P.; Kotti, Salma; Danchin, Nicolas; Scholz, Markus; Haase, Christiane L.; Rothenbacher, Dietrich; Swerdlow, Daniel I.; Kuchenbaecker, Karoline B.; Staines-Urias, Eleonora; Goel, Anuj; van 't Hooft, Ferdinand; Gertow, Karl; de Faire, Ulf; Panayiotou, Andrie G.; Tremoli, Elena; Baldassarre, Damiano; Veglia, Fabrizio; Holdt, Lesca M.; Beutner, Frank; Gansevoort, Ron T.; Navis, Gerjan J.; Mateo Leach, Irene; Breitling, Lutz P.; Brenner, Hermann; Thiery, Joachim; Dallmeier, Dhayana; Franco-Cereceda, Anders; Boer, Jolanda M. A.; Stephens, Jeffrey W.; Hofker, Marten H.; Tedgui, Alain; Hofman, Albert; Uitterlinden, Andre G.; Adamkova, Vera; Pitha, Jan; Onland-Moret, N. Charlotte; Cramer, Maarten J.; Nathoe, Hendrik M.; Spiering, Wilko; Klungel, Olaf H.; Kumari, Meena; Whincup, Peter H.; Morrow, David A.; Braund, Peter S.; Hall, Alistair S.; Olsson, Anders G.; Doevendans, Pieter A.; Trip, Mieke D.; Tobin, Martin D.; Hamsten, Anders; Watkins, Hugh; Koenig, Wolfgang; Nicolaides, Andrew N.; Teupser, Daniel; Day, Ian N. M.; Carlquist, John F.; Gaunt, Tom R.; Ford, Ian; Sattar, Naveed; Tsimikas, Sotirios; Schwartz, Gregory G.; Lawlor, Debbie A.; Morris, Richard W.; Sandhu, Manjinder S.; Poledne, Rudolf; Maitland-van der Zee, Anke H.; Khaw, Kay-Tee; Keating, Brendan J.; van der Harst, Pim; Price, Jackie F.; Mehta, Shamir R.; Yusuf, Salim; Witteman, Jaqueline C. M.; Franco, Oscar H.; Jukema, J. Wouter; de Knijff, Peter; Tybjaerg-Hansen, Anne; Rader, Daniel J.; Farrall, Martin; Samani, Nilesh J.; Kivimaki, Mika; Fox, Keith A. A.; Humphries, Steve E.; Anderson, Jeffrey L.; Boekholdt, S. Matthijs; Palmer, Tom M.; Eriksson, Per; Pare, Guillaume; Hingorani, Aroon D.; Sabatine, Marc S.; Mallat, Ziad; Casas, Juan P.; Talmud, Philippa J.

2013-01-01

Objectives This study sought to investigate the role of secretory phospholipase A(2) (sPLA(2))-IIA in cardiovascular disease. Background Higher circulating levels of sPLA(2)-IIA mass or sPLA(2) enzyme activity have been associated with increased risk of cardiovascular events. However, it is not

Darapladib, a lipoprotein-associated phospholipase A2 inhibitor, in diabetic macular edema

DEFF Research Database (Denmark)

Staurenghi, Giovanni; Ye, Li; Magee, Mindy H

2015-01-01

PURPOSE: To investigate the potential of lipoprotein-associated phospholipase A2 inhibition as a novel mechanism to reduce edema and improve vision in center-involved diabetic macular edema (DME). DESIGN: Prospective, multicenter, randomized, double-masked, placebo-controlled phase IIa study...... (AEs) and nonocular AEs were similar between treatment groups. CONCLUSIONS: Once-daily oral darapladib administered for 3 months demonstrated modest improvements in vision and macular edema that warrant additional investigation of this novel lipoprotein-associated phospholipase A2 inhibitory mechanism...

Synergy by secretory phospholipase A2 and glutamate on inducing cell death and sustained arachidonic acid metabolic changes in primary cortical neuronal cultures

DEFF Research Database (Denmark)

Kolko, M; DeCoster, M A; de Turco, E B

1996-01-01

glutamate and sPLA2 from bee venom. sPLA2, at concentrations eliciting low neurotoxicity (acid into triacylglycerols. Free [3H]arachidonic acid accumulated at higher enzyme concentrations......, from Taipan snake venom. The NMDA receptor antagonist MK-801 blocked glutamate effects and partially inhibited sPLA2 OS2 but not sPLA2 from bee venom-induced arachidonic acid release. Thus, the synergy with glutamate and very low concentrations of exogenously added sPLA2 suggests a potential role......Secretory and cytosolic phospholipases A2 (sPLA2 and cPLA2) may contribute to the release of arachidonic acid and other bioactive lipids, which are modulators of synaptic function. In primary cortical neuron cultures, neurotoxic cell death and [3H]arachidonate metabolism was studied after adding...

Alpha 1-adrenergic receptor-mediated phosphoinositide hydrolysis and prostaglandin E2 formation in Madin-Darby canine kidney cells. Possible parallel activation of phospholipase C and phospholipase A2

International Nuclear Information System (INIS)

Slivka, S.R.; Insel, P.A.

1987-01-01

alpha 1-Adrenergic receptors mediate two effects on phospholipid metabolism in Madin-Darby canine kidney (MDCK-D1) cells: hydrolysis of phosphoinositides and arachidonic acid release with generation of prostaglandin E2 (PGE2). The similarity in concentration dependence for the agonist (-)-epinephrine in eliciting these two responses implies that they are mediated by a single population of alpha 1-adrenergic receptors. However, we find that the kinetics of the two responses are quite different, PGE2 production occurring more rapidly and transiently than the hydrolysis of phosphoinositides. The antibiotic neomycin selectively decreases alpha 1-receptor-mediated phosphatidylinositol 4,5-bisphosphate hydrolysis without decreasing alpha 1-receptor-mediated arachidonic acid release and PGE2 generation. In addition, receptor-mediated inositol trisphosphate formation is independent of extracellular calcium, whereas release of labeled arachidonic acid is largely calcium-dependent. Moreover, based on studies obtained with labeled arachidonic acid, receptor-mediated generation of arachidonic acid cannot be accounted for by breakdown of phosphatidylinositol monophosphate, phosphatidylinositol bisphosphate, or phosphatidic acid. Further studies indicate that epinephrine produces changes in formation or turnover of several classes of membrane phospholipids in MDCK cells. We conclude that alpha 1-adrenergic receptors in MDCK cells appear to regulate phospholipid metabolism by the parallel activation of phospholipase C and phospholipase A2. This parallel activation of phospholipases contrasts with models described in other systems which imply sequential activation of phospholipase C and diacylglycerol lipase or phospholipase A2

Inventing an arsenal: adaptive evolution and neofunctionalization of snake venom phospholipase A2 genes

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Lynch Vincent J

2007-01-01

Full Text Available Abstract Background Gene duplication followed by functional divergence has long been hypothesized to be the main source of molecular novelty. Convincing examples of neofunctionalization, however, remain rare. Snake venom phospholipase A2 genes are members of large multigene families with many diverse functions, thus they are excellent models to study the emergence of novel functions after gene duplications. Results Here, I show that positive Darwinian selection and neofunctionalization is common in snake venom phospholipase A2 genes. The pattern of gene duplication and positive selection indicates that adaptive molecular evolution occurs immediately after duplication events as novel functions emerge and continues as gene families diversify and are refined. Surprisingly, adaptive evolution of group-I phospholipases in elapids is also associated with speciation events, suggesting adaptation of the phospholipase arsenal to novel prey species after niche shifts. Mapping the location of sites under positive selection onto the crystal structure of phospholipase A2 identified regions evolving under diversifying selection are located on the molecular surface and are likely protein-protein interactions sites essential for toxin functions. Conclusion These data show that increases in genomic complexity (through gene duplications can lead to phenotypic complexity (venom composition and that positive Darwinian selection is a common evolutionary force in snake venoms. Finally, regions identified under selection on the surface of phospholipase A2 enzymes are potential candidate sites for structure based antivenin design.

Crystallization and preliminary X-ray diffraction analysis of three myotoxic phospholipases A2 from Bothrops brazili venom

International Nuclear Information System (INIS)

Fernandes, Carlos A. H.; Gartuzo, Elaine C. G.; Pagotto, Ivan; Comparetti, Edson J.; Huancahuire-Vega, Salomón; Ponce-Soto, Luis Alberto; Costa, Tássia R.; Marangoni, Sergio; Soares, Andreimar M.; Fontes, Marcos R. M.

2012-01-01

Two myotoxic and noncatalytic Lys49-phospholipases A 2 (braziliantoxin-II and MT-II) and a myotoxic and catalytic phospholipase A 2 (braziliantoxin-III) from B. brazili were crystallized. X-ray diffraction data sets were collected and molecular-replacement solutions were obtained. Two myotoxic and noncatalytic Lys49-phospholipases A 2 (braziliantoxin-II and MT-II) and a myotoxic and catalytic phospholipase A 2 (braziliantoxin-III) from the venom of the Amazonian snake Bothrops brazili were crystallized. The crystals diffracted to resolutions in the range 2.56–2.05 Å and belonged to space groups P3 1 21 (braziliantoxin-II), P6 5 22 (braziliantoxin-III) and P2 1 (MT-II). The structures were solved by molecular-replacement techniques. Both of the Lys49-phospholipases A 2 (braziliantoxin-II and MT-II) contained a dimer in the asymmetric unit, while the Asp49-phospholipase A 2 braziliantoxin-III contained a monomer in its asymmetric unit. Analysis of the quaternary assemblies of the braziliantoxin-II and MT-II structures using the PISA program indicated that both models have a dimeric conformation in solution. The same analysis of the braziliantoxin-III structure indicated that this protein does not dimerize in solution and probably acts as a monomer in vivo, similar to other snake-venom Asp49-phospholipases A 2

Hydrolysis of short-chain phosphatidylcholines by bee venom phospholipase A2.

Science.gov (United States)

Raykova, D; Blagoev, B

1986-01-01

In order to find out the aggregation state of the substrate, preferred by bee venom phospholipase A2 (EC 3.1.1.4), its action on short-chain phosphatidylcholines with two identical (C6-C10) fatty acids has been tested. The rate of hydrolysis as a function of acyl chain length showed a maximum at dioctanoylphosphatidylcholine. The effects of alcohols, NaCl and Triton X-100, which affect the aggregation state of phospholipids in water, were also studied. The addition of n-alcohol led to a significant inhibition of the hydrolysis of the substrates present in micellar form and activated the hydrolysis of substrates which form liposomes. The inhibitory effect increased with increasing length of the aliphatic carbon chain of the alcohol. Triton X-100 at low Triton/phospholipid molar ratios enhanced enzyme activity. These results do not agree with the accepted idea that bee venom phospholipase A2 hydrolyzes short-chain lecithins in their molecularly dispersed form and that micelles cannot act as substrates. The data indicate that short-chain lecithins in the aggregated state are hydrolyzed and that the requirements of bee venom phospholipase A2 for the aggregation state of the substrate are not strict.

Overexpression of porcine lipoprotein-associated phospholipase A2 in swine

NARCIS (Netherlands)

Tang, Xiaochun; Wang, Gangqi; Liu, Xingxing; Han, Xiaolei; Li, Zhuang; Ran, Guangyao; Li, Zhanjun; Song, Qi; Ji, Y; Wang, Haijun; Wang, Yuhui; Ouyang, Hongsheng; Pang, Daxin

2015-01-01

Lipoprotein-associated phospholipase A 2 (Lp-PLA2) is associated with the risk of vascular disease. It circulates in human blood predominantly in association with low-density lipoprotein cholesterol (LDL-C) and hydrolyses oxidized phospholipids into pro-inflammatory products. However, in the mouse

Plasma Lipoprotein-associated Phospholipase A(2) Is Inversely Correlated with Proprotein Convertase Subtilisin-kexin Type 9

NARCIS (Netherlands)

Constantinides, Alexander; Kappelle, Paul J.W.H.; Lambert, Gilles; Dullaart, Robin P. F.

Background and Aims. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is a proatherogenic phospholipase A(2), which is predominantly complexed to low-density lipoprotein (LDL) particles. Proprotein convertase subtilisin-kexin type 9 (PCSK9) provides a key step in LDL metabolism by stimulating

PLA2G6, encoding a phospholipase A2, is mutated in neurodegenerative disorders with high brain iron

Science.gov (United States)

Morgan, Neil V; Westaway, Shawn K; Morton, Jenny E V; Gregory, Allison; Gissen, Paul; Sonek, Scott; Cangul, Hakan; Coryell, Jason; Canham, Natalie; Nardocci, Nardo; Zorzi, Giovanna; Pasha, Shanaz; Rodriguez, Diana; Desguerre, Isabelle; Mubaidin, Amar; Bertini, Enrico; Trembath, Richard C; Simonati, Alessandro; Schanen, Carolyn; Johnson, Colin A; Levinson, Barbara; Woods, C Geoffrey; Wilmot, Beth; Kramer, Patricia; Gitschier, Jane; Maher, Eamonn R; Hayflick, Susan J

2007-01-01

Neurodegenerative disorders with high brain iron include Parkinson disease, Alzheimer disease and several childhood genetic disorders categorized as neuroaxonal dystrophies. We mapped a locus for infantile neuroaxonal dystrophy (INAD) and neurodegeneration with brain iron accumulation (NBIA) to chromosome 22q12-q13 and identified mutations in PLA2G6, encoding a calcium-independent group VI phospholipase A2, in NBIA, INAD and the related Karak syndrome. This discovery implicates phospholipases in the pathogenesis of neurodegenerative disorders with iron dyshomeostasis. PMID:16783378

Moderate alcohol consumption and lipoprotein-associated phospholipase A2 activity

NARCIS (Netherlands)

Beulens, J.W.J.; Berg, R. van den; Kok, F.J.; Helander, A.; Vermunt, S.H.F.; Hendriks, H.F.J.

2008-01-01

Background and aims: To investigate the effect of moderate alcohol consumption on lipoprotein-associated phospholipase A2 activity, markers of inflammation and oxidative stress and whether these effects are modified by BMI. Methods and results: Eleven lean (BMI: 18.5-25 kg/m2) and 9 overweight (BMI

Synthesis of structured phospholipids by immobilized phospholipase A2 catalyzed acidolysis

DEFF Research Database (Denmark)

Vikbjerg, Anders Falk; Vikbjerg, Anders Falk; Xu, Xuebing

2007-01-01

Acyl modification of the sn-2 position in phospholipids (PLs) was conducted by acidolysis reaction using immobilized phospholipase A2 (PLA2) as the catalyst. In the first stage we screened different carriers for their ability to immobilize PLA2. Several carriers were able to fix the enzyme...

Secretory Phospholipase A2-IIA and Cardiovascular Disease: A Mendelian Randomization Study

NARCIS (Netherlands)

Holmes, Michael V.; Simon, Tabassome; Exeter, Holly J.; Folkersen, Lasse; Asselbergs, Folkert W.; Guardiola, Montse; Cooper, Jackie A.; Palmen, Jutta; Hubacek, Jaroslav A.; Carruthers, Kathryn F.; Horne, Benjamin D.; Brunisholz, Kimberly D.; Mega, Jessica L.; van Iperen, Erik P. A.; Li, Mingyao; Leusink, Maarten; Trompet, Stella; Verschuren, Jeffrey J. W.; Hovingh, G. Kees; Dehghan, Abbas; Nelson, Christopher P.; Kotti, Salma; Danchin, Nicolas; Scholz, Markus; Haase, Christiane L.; Rothenbacher, Dietrich; Swerdlow, Daniel I.; Kuchenbaecker, Karoline B.; Staines-Urias, Eleonora; Goel, Anuj; van 't Hooft, Ferdinand; Gertow, Karl; de Faire, Ulf; Panayiotou, Andrie G.; Tremoli, Elena; Baldassarre, Damiano; Veglia, Fabrizio; Holdt, Lesca M.; Beutner, Frank; Gansevoort, Ron T.; Navis, Gerjan J.; Mateo Leach, Irene; Breitling, Lutz P.; Brenner, Hermann; Thiery, Joachim; Dallmeier, Dhayana; Franco-Cereceda, Anders; Boer, Jolanda M. A.; Stephens, Jeffrey W.; Hofker, Marten H.; Tedgui, Alain; Hofman, Albert; Uitterlinden, André G.; Adamkova, Vera; Pitha, Jan; Onland-Moret, N. Charlotte; Cramer, Maarten J.; Nathoe, Hendrik M.; Spiering, Wilko; Klungel, Olaf H.; Kumari, Meena; Whincup, Peter H.; Morrow, David A.; Braund, Peter S.; Hall, Alistair S.; Olsson, Anders G.; Doevendans, Pieter A.; Trip, Mieke D.; Tobin, Martin D.; Hamsten, Anders; Watkins, Hugh; Koenig, Wolfgang; Nicolaides, Andrew N.; Teupser, Daniel; Day, Ian N. M.; Carlquist, John F.; Gaunt, Tom R.; Ford, Ian; Sattar, Naveed; Tsimikas, Sotirios; Schwartz, Gregory G.; Lawlor, Debbie A.; Morris, Richard W.; Sandhu, Manjinder S.; Poledne, Rudolf; Maitland-van der Zee, Anke H.; Khaw, Kay-Tee; Keating, Brendan J.; van der Harst, Pim; Price, Jackie F.; Mehta, Shamir R.; Yusuf, Salim; Witteman, Jaqueline C. M.; Franco, Oscar H.; Jukema, J. Wouter; de Knijff, Peter; Tybjaerg-Hansen, Anne; Rader, Daniel J.; Farrall, Martin; Samani, Nilesh J.; Kivimaki, Mika; Fox, Keith A. A.; Humphries, Steve E.; Anderson, Jeffrey L.; Boekholdt, S. Matthijs; Palmer, Tom M.; Eriksson, Per; Paré, Guillaume; Hingorani, Aroon D.; Sabatine, Marc S.; Mallat, Ziad; Casas, Juan P.; Talmud, Philippa J.

2013-01-01

This study sought to investigate the role of secretory phospholipase A2 (sPLA2)-IIA in cardiovascular disease. Higher circulating levels of sPLA2-IIA mass or sPLA2 enzyme activity have been associated with increased risk of cardiovascular events. However, it is not clear if this association is

Purification of lysosomal phospholipase A and demonstration of proteins that inhibit phospholipase A in a lysosomal fraction from rat kidney cortex

International Nuclear Information System (INIS)

Hostetler, K.Y.; Gardner, M.F.; Giordano, J.R.

1986-01-01

Phospholipase A has been isolated from a crude lysosomal fraction from rat kidney cortex and purified 7600-fold with a recovery of 9.8% of the starting activity. The purified enzyme is a glycoprotein having an isoelectric point of pH 5.4 and an apparent molecular weight of 30,000 by high-pressure liquid chromatography gel permeation. Naturally occurring inhibitors of lysosomal phospholipase A are present in two of the lysosomal-soluble protein fractions obtained in the purification. They inhibit hydrolysis of 1,2-di[1- 14 C]oleoylphosphatidylcholine by purified phospholipase A 1 with IC 50 values of 7-11 μg. The inhibition is abolished by preincubation with trypsin at 37 0 C, but preincubation with trypsin at 4 0 C has no effect, providing evidence that the inhibitors are proteins. The results suggest that the activity of lysosomal phospholipase A may be regulated in part by inhibitory proteins. Lysosomal phospholipase A from rat kidney hydrolyzes the sn-1 acyl group of phosphatidylcholine, does not require divalent cations for full activity, and is not inhibited by ethylenediaminetetraacetic acid. It has an acid pH optimum of 3.6-3.8. Neither rho-bromophenacyl bromide, diisopropyl fluorophosphate, nor mercuric ion inhibits phospholipase A 1 . In contrast to rat liver, which has two major isoenzymes of acid phospholipase A 1 , kidney cortex has only one isoenzyme of lysosomal phospholipase A 1

Purification of lysosomal phospholipase A and demonstration of proteins that inhibit phospholipase A in a lysosomal fraction from rat kidney cortex

Energy Technology Data Exchange (ETDEWEB)

Hostetler, K.Y.; Gardner, M.F.; Giordano, J.R.

1986-10-21

Phospholipase A has been isolated from a crude lysosomal fraction from rat kidney cortex and purified 7600-fold with a recovery of 9.8% of the starting activity. The purified enzyme is a glycoprotein having an isoelectric point of pH 5.4 and an apparent molecular weight of 30,000 by high-pressure liquid chromatography gel permeation. Naturally occurring inhibitors of lysosomal phospholipase A are present in two of the lysosomal-soluble protein fractions obtained in the purification. They inhibit hydrolysis of 1,2-di(1-/sup 14/C)oleoylphosphatidylcholine by purified phospholipase A/sub 1/ with IC/sub 50/ values of 7-11 ..mu..g. The inhibition is abolished by preincubation with trypsin at 37/sup 0/C, but preincubation with trypsin at 4/sup 0/C has no effect, providing evidence that the inhibitors are proteins. The results suggest that the activity of lysosomal phospholipase A may be regulated in part by inhibitory proteins. Lysosomal phospholipase A from rat kidney hydrolyzes the sn-1 acyl group of phosphatidylcholine, does not require divalent cations for full activity, and is not inhibited by ethylenediaminetetraacetic acid. It has an acid pH optimum of 3.6-3.8. Neither rho-bromophenacyl bromide, diisopropyl fluorophosphate, nor mercuric ion inhibits phospholipase A/sub 1/. In contrast to rat liver, which has two major isoenzymes of acid phospholipase A/sub 1/, kidney cortex has only one isoenzyme of lysosomal phospholipase A/sub 1/.

Inhibition of cytosolic Phospholipase A2 prevents prion peptide-induced neuronal damage and co-localisation with Beta III Tubulin

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Last Victoria

2012-08-01

Full Text Available Abstract Background Activation of phospholipase A2 (PLA2 and the subsequent metabolism of arachidonic acid (AA to prostaglandins have been shown to play an important role in neuronal death in neurodegenerative disease. Here we report the effects of the prion peptide fragment HuPrP106-126 on the PLA2 cascade in primary cortical neurons and translocation of cPLA2 to neurites. Results Exposure of primary cortical neurons to HuPrP106-126 increased the levels of phosphorylated cPLA2 and caused phosphorylated cPLA2 to relocate from the cell body to the cellular neurite in a PrP-dependent manner, a previously unreported observation. HuPrP106-126 also induced significant AA release, an indicator of cPLA2 activation; this preceded synapse damage and subsequent cellular death. The novel translocation of p-cPLA2 postulated the potential for exposure to HuPrP106-126 to result in a re-arrangement of the cellular cytoskeleton. However p-cPLA2 did not colocalise significantly with F-actin, intermediate filaments, or microtubule-associated proteins. Conversely, p-cPLA2 did significantly colocalise with the cytoskeletal protein beta III tubulin. Pre-treatment with the PLA2 inhibitor, palmitoyl trifluoromethyl ketone (PACOCF3 reduced cPLA2 activation, AA release and damage to the neuronal synapse. Furthermore, PACOCF3 reduced expression of p-cPLA2 in neurites and inhibited colocalisation with beta III tubulin, resulting in protection against PrP-induced cell death. Conclusions Collectively, these findings suggest that cPLA2 plays a vital role in the action of HuPrP106-126 and that the colocalisation of p-cPLA2 with beta III tubulin could be central to the progress of neurodegeneration caused by prion peptides. Further work is needed to define exactly how PLA2 inhibitors protect neurons from peptide-induced toxicity and how this relates to intracellular structural changes occurring in neurodegeneration.

Effects of a phospholipase A2 inhibitor on uptake and toxicity of liposomes containing plant phosphatidylinositol

International Nuclear Information System (INIS)

Jett, M.; Alving, C.R.

1986-01-01

Plant phosphatidylinositol (PI) has been shown by us to have a direct cytotoxic effect on cultured tumor cells but not on normal cells. Synthetic PI containing 14 C-linoleic acid in the sn-2 position, also showed the same pattern of selective cytotoxicity. When the metabolic fate of synthetic PI was examined with tumor cells, the radioactivity which no longer occurred as PI, was found as either products of phospholipase A 2 (93%, free fatty acids and phosphatidylcholine) or phospholipase C (7%, diglycerides). Uptake of liposomal PI was directly correlated with cytotoxicity. They tested a variety of inhibitors to see the effect on uptake and/or cytotoxicity of plant PI. General metabolic inhibitors such as metrizamide or sodium azide did not alter cellular uptake of the plant PI liposomes. Inhibitors of lipoxygenase formation, such as indomethacin, also did not alter the uptake or cytotoxicity induced by plant PI. Quinacrine, an inhibitor of phospholipase A 2 , decreased the uptake of the PI containing liposomes to 50% of that seen in the presence or absence of any other inhibitor. Although quinacrine is itself toxic to cells, at low concentrations of quinacrine, plant PI did not show the same degree of cytotoxicity as in the absence of quinacrine. These data are compatible with the hypothesis that plant PI exerts cytotoxicity by serving as a substrate for phospholipase A 2

Roles of phospholipase A2 isoforms in swelling- and melittin-induced arachidonic acid release and taurine efflux in NIH3T3 fibroblasts

DEFF Research Database (Denmark)

Pedersen, Stine Helene Falsig; Poulsen, Kristian Arild; Lambert, Ian H.

2006-01-01

Osmotic swelling of NIH3T3 mouse fibroblasts activates a bromoenol lactone (BEL)-sensitive taurine efflux, pointing to the involvement of a Ca2+-independent phospholipase A2 (iPLA2) (Lambert IH. J Membr Biol 192: 19-32, 2003). We report that taurine efflux from NIH3T3 cells was not only increased...... by cell swelling but also decreased by cell shrinkage. Arachidonic acid release to the cell exterior was similarly decreased by shrinkage yet not detectably increased by swelling. NIH3T3 cells were found to express cytosolic calcium-dependent cPLA2-IVA, cPLA2-IVB, cPLA2-IVC, iPLA2-VIA, iPLA2-VIB......, and secretory sPLA2-V. Arachidonic acid release from swollen cells was partially inhibited by BEL and by the sPLA2-inhibitor manoalide. Cell swelling elicited BEL-sensitive arachidonic acid release from the nucleus, to which iPLA2-VIA localized. Exposure to the bee venom peptide melittin, to increase PLA2...

A MIDGUT DIGESTIVE PHOSPHOLIPASE A2 IN LARVAL MOSQUITOES, AEDES ALBOPICTUS AND CULEX QUINQUEFASCIATUS

Science.gov (United States)

Phospholipase A2 (PLA2) is a secretory digestive enzyme that hydrolyzes ester bond at sn-2 position of dietary phospholipids, creating free fatty acid and lysophopholipid. The free fatty acids (arachidonic acid) are absorbed into midgut cells. Aedes albopictus and Culex quinquefasciatus digestive PL...

The action of cobra venom phospholipase A2 isoenzymes towards intact human erythrocytes

NARCIS (Netherlands)

Roelofsen, B.; Sibenius Trip, M.; Verheij, H.M.; Zevenbergen, J.L.

1980-01-01

1. 1. Cobra venom phospholipase A2 from three different sources has been fractionated into different isoenzymes by DEAE ion-exchange chromatography. 2. 2. Treatment of intact human erythrocytes with the various isoenzymes revealed significant differences in the degree of phosphatidylcholine

Studies of insulin secretory responses and of arachidonic acid incorporation into phospholipids of stably transfected insulinoma cells that overexpress group VIA phospholipase A2 (iPLA2beta ) indicate a signaling rather than a housekeeping role for iPLA2beta.

Science.gov (United States)

Ma, Z; Ramanadham, S; Wohltmann, M; Bohrer, A; Hsu, F F; Turk, J

2001-04-20

A cytosolic 84-kDa group VIA phospholipase A(2) (iPLA(2)beta) that does not require Ca(2+) for catalysis has been cloned from several sources, including rat and human pancreatic islet beta-cells and murine P388D1 cells. Many potential iPLA(2)beta functions have been proposed, including a signaling role in beta-cell insulin secretion and a role in generating lysophosphatidylcholine acceptors for arachidonic acid incorporation into P388D1 cell phosphatidylcholine (PC). Proposals for iPLA(2)beta function rest in part on effects of inhibiting iPLA(2)beta activity with a bromoenol lactone (BEL) suicide substrate, but BEL also inhibits phosphatidate phosphohydrolase-1 and a group VIB phospholipase A(2). Manipulation of iPLA(2)beta expression by molecular biologic means is an alternative approach to study iPLA(2)beta functions, and we have used a retroviral construct containing iPLA(2)beta cDNA to prepare two INS-1 insulinoma cell clonal lines that stably overexpress iPLA(2)beta. Compared with parental INS-1 cells or cells transfected with empty vector, both iPLA(2)beta-overexpressing lines exhibit amplified insulin secretory responses to glucose and cAMP-elevating agents, and BEL substantially attenuates stimulated secretion. Electrospray ionization mass spectrometric analyses of arachidonic acid incorporation into INS-1 cell PC indicate that neither overexpression nor inhibition of iPLA(2)beta affects the rate or extent of this process in INS-1 cells. Immunocytofluorescence studies with antibodies directed against iPLA(2)beta indicate that cAMP-elevating agents increase perinuclear fluorescence in INS-1 cells, suggesting that iPLA(2)beta associates with nuclei. These studies are more consistent with a signaling than with a housekeeping role for iPLA(2)beta in insulin-secreting beta-cells.

Cyclopentanoid analogs of phosphatidylcholine: susceptibility to phospholipase A2.

Science.gov (United States)

Lister, M D; Hancock, A J

1988-10-01

Six isomers of dipalmitoylcyclopentanetriol phosphocholine (cyclopentano-lecithin) were tested as potential substrates for phospholipase A2. Since each of these analogs possesses a configuration that mimics a narrow range of conformations of a glycerophospholipid molecule, the analogs were used to assess the enzyme's conformational requirements. Studies showed that all of the analogs containing the phosphocholine at the C-1 (or C-3) position could be hydrolyzed, while only one of the three analogs that contains the polar head group at the C-2 position was susceptible. Kinetic studies, however, revealed that only the all-trans-(1,3/2-1P)-cyclopentano-lecithin gave initial rates of hydrolysis that were measurable by pH-stat. Acyl group specificity of the enzyme towards the all-trans isomer was determined with an analog was acyl groups were distinguishable. The synthesis of this mixed-acid-cyclopentano-PC is described herein. When this analog was enzymatically assayed, results unequivocally showed the enzyme to be specific for C-2 acyl hydrolysis. This specificity, and data showing that the all-trans analog is stereospecifically hydrolyzed, indicate that it is acted on in an analogous manner to dipalmitoylphosphatidylcholine. These studies indicate that although the configuration of the analog is not necessarily a prerequisite for hydrolysis, there does appear to be an optimal spatial orientation for enzymatic activity. The analogy between the susceptibilities of all-trans-(1,3/2-1P)-cyclopentano-lecithin and glycero-lecithin suggests that the conformation of the glycero-lecithin during phospholipase A2-mediated hydrolysis may be best simulated by the all-trans orientation of C-O bonds in the artificial substrate.

Rac-mediated Stimulation of Phospholipase Cγ2 Amplifies B Cell Receptor-induced Calcium Signaling*♦

Science.gov (United States)

Walliser, Claudia; Tron, Kyrylo; Clauss, Karen; Gutman, Orit; Kobitski, Andrei Yu.; Retlich, Michael; Schade, Anja; Röcker, Carlheinz; Henis, Yoav I.; Nienhaus, G. Ulrich; Gierschik, Peter

2015-01-01

The Rho GTPase Rac is crucially involved in controlling multiple B cell functions, including those regulated by the B cell receptor (BCR) through increased cytosolic Ca2+. The underlying molecular mechanisms and their relevance to the functions of intact B cells have thus far remained unknown. We have previously shown that the activity of phospholipase Cγ2 (PLCγ2), a key constituent of the BCR signalosome, is stimulated by activated Rac through direct protein-protein interaction. Here, we use a Rac-resistant mutant of PLCγ2 to functionally reconstitute cultured PLCγ2-deficient DT40 B cells and to examine the effects of the Rac-PLCγ2 interaction on BCR-mediated changes of intracellular Ca2+ and regulation of Ca2+-regulated and nuclear-factor-of-activated-T-cell-regulated gene transcription at the level of single, intact B cells. The results show that the functional Rac-PLCγ2 interaction causes marked increases in the following: (i) sensitivity of B cells to BCR ligation; (ii) BCR-mediated Ca2+ release from intracellular stores; (iii) Ca2+ entry from the extracellular compartment; and (iv) nuclear translocation of the Ca2+-regulated nuclear factor of activated T cells. Hence, Rac-mediated stimulation of PLCγ2 activity serves to amplify B cell receptor-induced Ca2+ signaling. PMID:25903139

The correlation between anti phospholipase A 2 specific IgE and clinical symptoms after a bee sting in beekeepers

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Jan Matysiak

2016-06-01

Full Text Available Introduction: Beekeepers are a group of people with high exposure to honeybee stings and with a very high risk of allergy to bee venom. Therefore, they are a proper population to study the correlations between clinical symptoms and results of diagnostic tests. Aim: The primary aim of our study was to assess the correlations between total IgE, venom- and phospholipase A 2 -specific IgE and clinical symptoms after a bee sting in beekeepers. The secondary aim was to compare the results of diagnostic tests in beekeepers and in individuals with standard exposure to bees. Material and methods: Fifty-four individuals were divided into two groups: beekeepers and control group. The levels of total IgE (tIgE, venom-specific IgE (venom sIgE, and phospholipase A 2 -specific IgE (phospholipase A 2 sIgE were analyzed. Results: Our study showed no statistically significant correlation between the clinical symptoms after a sting and tIgE in the entire analyzed group. There was also no correlation between venom sIgE level and clinical symptoms either in beekeepers or in the group with standard exposure to bees. We observed a statistically significant correlation between phospholipase A 2 sIgE level and clinical signs after a sting in the group of beekeepers, whereas no such correlation was detected in the control group. Significantly higher venom-specific IgE levels in the beekeepers, as compared to control individuals were shown. Conclusions : In beekeepers, the severity of clinical symptoms after a bee sting correlated better with phospholipase A 2 sIgE than with venom sIgE levels.

Origin and evolution of group XI secretory phospholipase A2 from flax (Linum usitatissimum) based on phylogenetic analysis of conserved domains.

Science.gov (United States)

Gupta, Payal; Saini, Raman; Dash, Prasanta K

2017-07-01

Phospholipase A 2 (PLA 2 ) belongs to class of lipolytic enzymes (EC 3.1.1.4). Lysophosphatidic acid (LPA) and free fatty acids (FFAs) are the products of PLA 2 catalyzed hydrolysis of phosphoglycerides at sn-2 position. LPA and FFA that act as second mediators involved in the development and maturation of plants and animals. Mining of flax genome identified two phospholipase A 2 encoding genes, viz., LusPLA 2 I and LusPLA 2 II (Linum usitatissimum secretory phospholipase A 2 ). Molecular simulation of LusPLA 2 s with already characterized plant sPLA 2 s revealed the presence of conserved motifs and signature domains necessary to classify them as secretory phospholipase A 2 . Phylogenetic analysis of flax sPLA 2 with representative sPLA 2 s from other organisms revealed that they evolved rapidly via gene duplication/deletion events and shares a common ancestor. Our study is the first report of detailed phylogenetic analysis for secretory phospholipase A 2 in flax. Comparative genomic analysis of two LusPLA 2 s with earlier reported plant sPLA 2 s, based on their gene architectures, sequence similarities, and domain structures are presented elucidating the uniqueness of flax sPLA 2 .

Phospholipase B activity of a purified phospholipase A from Vipera palestinae venom.

Science.gov (United States)

Shiloah, J; Klibansky, C; de Vries, A; Berger, A

1973-05-01

Phospholipase was isolated (in two fractions) from Vipera palestinae venom and it was shown to possess phospholipase A activity (hydrolyzing diacyl-sn-glycerophosphorylcholines, e.g., lecithin, in the 2-position) as well as lysophospholipase (phospholipase B) activity (hydrolyzing 1-monoacyl-sn-glycerophosphorylcholines, e.g., lysolecithin, yielding free fatty acid and glycerophosphorylcholine). Each of the two purified enzyme fractions was homogeneous as judged by electrophoresis on acrylamide gel and by immunodiffusion and immunoelectrophoresis, and both had essentially equal activities. The ratio of the specific activity, at various purification stages, to the specific activity of the whole venom was the same for A activity (substrate lecithin) as for B activity (substrate lysolecithin). The enzyme has a molecular weight of 16,000, six S-S bridges, and no free thiol groups. At pH 7, dimerization was observed in the ultracentrifuge. A dissociation constant of about 10(-5) m was estimated. The amino acid composition for both fractions (140 amino acid residues) was found to be essentially the same. The A activity had a pH optimum at 9; B activity was low at this pH but increased steadily beyond pH 10.5. For the hydrolysis of lysolecithin the Lineweaver-Burk plot was found to be linear, giving K(m) = 1.1 mm and k(cat) = 0.55 sec(-1) at 37 degrees C and pH 10. 2-Deoxylysolecithin was also hydrolyzed by the enzyme at pH 10, with k(cat) = 0.01 sec(-1) (zero-order kinetics in the range 0.5-2.5 mm). For lecithin these constants could not be determined, but at 0.25 mm substrate the hydrolysis rate (at pH 9) of lecithin was about 1000 times the hydrolysis rate of lysolecithin (at pH 10).

Evaluation of snake venom phospholipase A{sub 2}: hydrolysis of non-natural esters

Energy Technology Data Exchange (ETDEWEB)

Pirolla, Renan A.S.; Baldasso, Paulo A.; Marangoni, Sergio; Moran, Paulo J.S.; Rodrigues, Jose Augusto R., E-mail: jaugusto@iqm.unicamp.b [University of Campinas (UNICAMP), SP (Brazil). Inst. of Chemistry. Dept. of Organic Chemistry

2011-07-01

Phospholipase A2 from the rattlesnake Crotalus durissus terrificus was employed for the first time to test its enantioselectivity on the hydrolysis of different non-natural esters. It was observed that the structure of this small enzyme is restrictive in the choice of its lipase action with non-natural substrates. Two forms of the enzyme were used; free and as its cross-linked enzyme aggregate (CLEA). With all substrates, the free enzyme showed activity similar to the CLEA preparation. The advantage of the CLEA phospholipase is the possibility to reuse it in several consecutive reactions without a decrease of activity and selectivity with good but higher yields and ee than with the free enzyme. (author)

[Inhibition of phospholipase A2 of peritoneal macrophages in rats by 1,2-di-O-hexadecyl-rac-glycero-3-phosphocholine].

Science.gov (United States)

Boucrot, P; Khettab, E N; Petit, J Y; Welin, L

1993-01-01

The 1-O-stearoyl-2-O-[3H] arachidonyl-sn-glycero-3-phosphocholine, introduced in the culture medium, was taken up by the peritoneal macrophages activated by the ionophore A 23187. After intracellular phospholipase A2 activity, the [3H] arachidonic acid was found in cells and in extracellular fluids. It also reached the eicosanoid synthesis. When it was introduced in the culture medium with the tritiated phospholipid, the 1, 2 di-O-hexadecyl-rac-glycero-3-phosphocholine, which has a non hydrolysable alkylated structure in the 2 position of the glycerol, inhibited the intracellular phospholipase A2, then contributed to lower the eicosanoid synthesis.

Effect of the environmental pollutant bisphenol A dimethacylate (BAD) on Ca2+ movement and viability in OC2 human oral cancer cells.

Science.gov (United States)

Chien, Jau-Min; Chou, Chiang-Ting; Lu, Yi-Chau; Lu, Ti; Chi, Chao-Chuan; Tseng, Li-Ling; Liu, Shiuh-Inn; Cheng, Jin-Shiung; Kuo, Chun-Chi; Liang, Wei-Zhe; Jan, Chung-Ren

2013-03-01

The environmental pollutant bisphenol A dimethacylate (BAD) has been used as a dental composite. The effect of BAD on cytosolic Ca(2+) concentrations ([Ca(2+)]i) and viability in OC2 human oral cancer cells was explored. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)]i. BAD induced [Ca(2+)]i rises in a concentration-dependent manner. The response was reduced by removing extracellular Ca(2+). BAD-evoked Ca(2+) entry was suppressed by nifedipine, econazole, and SK&F96365. In Ca(2+)-free medium, incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin abolished BAD-induced [Ca(2+)]i rise. Inhibition of phospholipase C with U73122 did not alter BAD-induced [Ca(2+)]i rise. At 10-30μM, BAD inhibited cell viability, which was not reversed by chelating cytosolic Ca(2+). BAD (20-30μM) also induced apoptosis. Collectively, in OC2 cells, BAD induced a [Ca(2+)]i rise by evoking phospholipase C-independent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via store-operated Ca(2+) channels. BAD also caused apoptosis. Copyright © 2012 Elsevier B.V. All rights reserved.

Didecanoyl phosphatidylcholine is a superior substrate for assaying mammalian phospholipase D

DEFF Research Database (Denmark)

Vinggaard, Anne Marie; Jensen, T.; Morgan, C.P.

1996-01-01

Phospholipase D (PLD) activity in crude or solubilized membranes from mammalian tissues is difficult to detect with the current assay techniques, unless a high radioactive concentration of substrate and/or long incubation times are employed. Generally, the enzyme has to be extracted and partially...... purified on one column before easy detection of activity. Furthermore, PLD activity in cultured cells can only be detected by the available assay techniques in the presence of guanosine 5'-[¿-thio]triphosphate (GTP[S]) and a cytosolic factor [usually ADP-ribosylation factor (Arf)]. In this paper we report...... that the use of didecanoyl phosphatidylcholine (C-PC) in mammalian PLD assays considerably increases the detection limit. C-PC was compared with the commonly used dipalmitoyl phosphatidylcholine (C-PC) as a substrate for PLD activity from membranes of human neutrophils, human placenta and pig brain, and from...

Lactadherin inhibits secretory phospholipase A₂ activity on pre-apoptotic leukemia cells

DEFF Research Database (Denmark)

Nyegaard, Steffen; Novakovic, Valerie A.; Rasmussen, Jan Trige

2013-01-01

Secretory phospholipase A2 (sPLA2) is a critical component of insect and snake venoms and is secreted by mammalian leukocytes during inflammation. Elevated secretory PLA2 concentrations are associated with autoimmune diseases and septic shock. Many sPLA2’s do not bind to plasma membranes of quies...

Wasp venom proteins: phospholipase A1 and B.

Science.gov (United States)

King, T P; Kochoumian, L; Joslyn, A

1984-04-01

Three major venom proteins from different species of wasps have been isolated and characterized. They are hyaluronidase, phospholipase, and antigen 5 of as yet unknown biochemical function. These three proteins are allergens in wasp venom-sensitive persons. The species of wasps studied, of the genus Polistes, were annularis, carolina, exclamans, fuscatus, and instabilis. Antigen 5 and phospholipase from wasp venoms were shown to be antigenically distinct from homologous proteins of yellowjacket venoms. The venom phospholipase from wasp, as well as that from yellowjacket (Vespula germanica), appears to have dual enzymatic specificities of the A1 and B types. That is, hydrolysis takes place at the 1-acyl residue of phosphatidylcholine and at the 1- or 2-acyl residue of lysophosphatidylcholine.

Phospholipase A2 from Bothrops alternatus (víbora de la cruz) venom. Purification and some characteristic properties.

Science.gov (United States)

Nisenbom, H E; Seki, C; Vidal, J C

1986-01-01

One single protein species with phospholipase activity has been isolated from Bothrops alternatus venom by a procedure involving gel-filtration on Sephadex G-50 (Step 1), chromatography on SP-Sephadex C-50 (Step 2) and gel-filtration on Sephadex G-75 (Step 3). The purified sample behaved as a homogeneous, monodisperse protein with a molecular weight of 15,000 and isoelectric point of 5.04. The yield in enzyme activity was 48% of the starting material and the apparent purification was 51-fold. When assayed on 1,2-diheptanoyl- or 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine, fatty acids and lysolecithins were the only reaction products, in accordance with the predicted stoichiometry. Studies on positional specificity suggested that the enzyme is a phospholipase A2. The enzyme requires Ca2+ ions for activity and exhibited stereochemical specificity, since the enantiomeric 2, 3-diheptanoyl-sn-glycero-1-phosphorylcholine was not hydrolyzed. Under the experimental conditions employed, reaction products representative of either phospholipase B or C activities could not be detected. After Step 1, the phospholipase activity recovered was higher than the total activity in the crude venom sample, which is explained by the separation of an inhibitor during enzyme purification. The inhibitor was responsible for the initial lag period that characterized the kinetics of the enzyme reaction with crude venom acting on aggregated substrates (lipoprotein, vesicles or micelles), while the rate of hydrolysis of monomeric lecithins was not affected.

EXPRESSION OF A BEE-VENOM PHOSPHOLIPASE A2 FROM APIS CERANA CERANA IN E,.qCHERICHIA COLI

Institute of Scientific and Technical Information of China (English)

Li-rongShen; Jia-anCheng; Chuan-xiZhang

2004-01-01

The venomous phospholipase A2 (AcPLA2) coding reading region of the Chinese honeybee (Apis cerana cerana), which is composed of 405 bp encoding a mature glycosylated peptide with 134 amino residues was transformed into the expression vector pETblue-1. Then the recombinant vector was introduced into Escherichia coli Tuner (DE3) plac I for expression. Analysis result of SDS-PAGE showed that the expression products had a protein band of about 15 kD. Detection of western blot using ant-European honeybee (Apis mellifera) phospholipase A2 (AmPLA2) polyclonal serum as the first antibody showed that the expression products appeared a special blot same as the native AmPLA2.The result demonstrated that the AcPLA2 peptide had been expressed in E. coli and the AcPLA2 has the similar antigenicity as the AmPLA2.

Characterization of phospholipase A2 from the pyloric ceca of two species of starfish, Coscinasterias acutispina and Plazaster borealis

OpenAIRE

Kishimura, Hideki; Hayashi, Kenji

2005-01-01

Phospholipase A (PLA) activities in the pyloric ceca and viscera from seven species of marine invertebrates (four starfish, one sea urchin, and two shellfish) were determined. Relatively high PLA specific activities were found in the pyloric ceca of two species of starfish (Coscinasterias acutispina and Plazaster borealis). Phospholipase A2s (PLA2s) were partially purified from the pyloric ceca of the starfish, C. acutispina PLA2 (C-PLA2) and P. borealis PLA2 (P-PLA2). The C-PLA2 and P-PLA2 m...

Purification and characterization of a phospholipase by Photobacterium damselae subsp. piscicida from cobia Rachycentron canadum.

Science.gov (United States)

Hsu, Po-Yuan; Lee, Kuo-Kau; Hu, Chih-Chuang; Liu, Ping-Chung

2014-09-01

Toxicity of the extracellular products (ECPs) and the lethal attributes of phospholipase secreted by pathogenic Photobacterium damselae subsp. piscicida from cobia Rachycentron canadum was studied. An extracellular lethal toxin in the ECPs was partially purified by using Fast Protein Liquid Chromatography system. A protein band (27 kDa) exhibited phospholipase activity on Native-PAGE (by 0.3% egg yolk agar-overlay), was excised and eluted. The pI value of the purified phospholipase was determined as 3.65 and was determined as a phospholipase C by using the Amplex™ Red phosphatidylcholine -Specific phospholipase C Assay kit. The phospholipase showed maximum activity at temperature around 4-40 °C and maximal activity at pH between 8 and 9. The enzyme was inhibited by ethylenediamine-tetraacetic acid (EDTA) and sodium dodecyl sulfate (SDS); but was activated by Ca(2+) and Mg(2+) and inactivated by Zn(2+) and Cu(2+) . Both the ECPs and phospholipase were hemolytic against erythrocytes of cobia and lethal to the fish with LD50 values of 3.25 and 0.91 µg protein g(-1) fish, respectively. In toxicity neutralization test, the rabbit antisera against the phospholipase could neutralize the toxicity of ECPs, indicating that the phospholipase is a major extracellular toxin produced by the bacterium. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cross-reactivity and phospholipase A2 neutralization of anti-irradiated Bothrops jararaca venom antibodies

International Nuclear Information System (INIS)

Spencer, P.J.; Nascimento, N. do; Paula, R.A. de; Cardi, B.A.; Rogero, J.R.

1995-01-01

The detoxified Bothrops jararaca venom, immunized rabbits with the toxoid obtained and investigated cross-reactivity of the antibodies obtained against autologous and heterelogous venoms was presented. It was also investigated the ability of the IgGs, purified by affinity chromatography, from those sera to neutralize phospholipase. A 2 , an ubiquous enzyme in animal venoms. Results indicate that venom irradiation leads to an attenuation of toxicity of 84%. Cross-reactivity was investigated by ELISA and Western blot and all venoms were reactive to the antibodies. On what refers to phospholipase A 2 activity neutralization, the antibodies neutralized autologous venoms efficiently and, curiously, other venoms from the same genus were not neutralized, while Lachesis muta venom, a remote related specier, was neutralized by this serum. These data suggest that irradiation preserve important epitopes for induction of neutralizing antibodies and that these epitopes are not shared by all venoms assayed. (author). 8 refs, 2 figs, 3 tabs

Glucose acutely reduces cytosolic and mitochondrial H2O2 in rat pancreatic beta-cells.

Science.gov (United States)

Deglasse, Jean-Philippe; Roma, Leticia Prates; Pastor-Flores, Daniel; Gilon, Patrick; Dick, Tobias P; Jonas, Jean-Christophe

2018-05-14

Whether H2O2 contributes to the glucose-dependent stimulation of insulin secretion by pancreatic β-cells is highly controversial. We used two H2O2-sensitive probes, roGFP2-Orp1 and HyPer with its pH-control SypHer, to test the acute effects of glucose, monomethylsuccinate, leucine with glutamine, and α-ketoisocaproate, on β-cell cytosolic and mitochondrial H2O2 concentrations. We then tested the effects of low H2O2 and menadione concentrations on insulin secretion. RoGFP2-Orp1 was more sensitive than HyPer to H2O2 (response at 2-5 vs. 10µM) and less pH-sensitive. Under control conditions, stimulation with glucose reduced mitochondrial roGFP2-Orp1 oxidation without affecting cytosolic roGFP2-Orp1 and HyPer fluorescence ratios, except for the pH-dependent effects on HyPer. However, stimulation with glucose decreased the oxidation of both cytosolic probes by 15µM exogenous H2O2. The glucose effects were not affected by overexpression of catalase, mitochondrial catalase or superoxide dismutase 1 and 2. They followed the increase in NAD(P)H autofluorescence, were maximal at 5mM glucose in the cytosol and 10mM glucose in the mitochondria, and were partly mimicked by the other nutrients. Exogenous H2O2 (1-15µM) did not affect insulin secretion. By contrast, menadione (1-5µM) did not increase basal insulin secretion but reduced the stimulation of insulin secretion by 20mM glucose. Subcellular changes in β-cell H2O2 levels are better monitored with roGFP2-Orp1 than HyPer/SypHer. Nutrients acutely lower mitochondrial H2O2 levels in β-cells and promote degradation of exogenously supplied H2O2 in both cytosolic and mitochondrial compartments. The glucose-dependent stimulation of insulin secretion occurs independently of a detectable increase in β-cell cytosolic or mitochondrial H2O2 levels.

Differential effects of phorbol 12-myristate 13-acetate and diacylglycerols on thromboxane A2-independent phospholipase A2 activation in collage-stimulated human platelets.

Science.gov (United States)

Reddy, S; Rao, G H; Murthy, M

1994-04-01

We investigated the priming effects of protein kinase C (PKC) activators such as phorbol 12-myristate 13-acetate (PMA), 1,2-DiC8 and OAG, and 1,3-DiC8 (a poor activator of PKC) on thromboxane A2 (TxA2)-independent phospholipase A2 (PLA2) activation in human platelets using collagen and A23187 as agonists. We measured PLA2 activation in collagen-stimulated platelets in the presence of BW755C, which abolished TxA2 synthesis, rise in cytosolic Ca2+, and aggregation. In the presence of PMA (50 nM), the amount of arachidonic acid (AA) released in platelets stimulated with collagen and A23187 represented 300% (13.85 nmol versus 4.5 nmol) and 400% (28 nmol versus 7 nmol) of controls (without PMA), respectively, while 1,2-DiC8, OAG, and 1,3-DiC8 increased TxA2-independent AA release by 50% in A23187-stimulated platelets and had no effect on the release of AA in collagen-stimulated platelets. Interestingly, 1,3-DiC8, which is a poor activator of PKC, was as effective as the other two DAGs (OAG and 1,2-DiC8) in priming TxA2-independent PLA2 activation, but was less effective than PMA in platelets stimulated with A23187. These results suggest that the TXA2-dependent IP3-mediated rise in cytosolic Ca2+ may not be obligatory for priming PLA2 activation in the presence of PMA in collagen-stimulated platelets. In contrast, 1,2-DiC8, OAG, and 1,3-DiC8 likely enhanced PLA2 activation via intracellular Ca2+ as they selectively affect this enzyme only in A23187-stimulated platelets. We also observed a significant increase in both saturated (palmitic and stearic acids) and unsaturated fatty acids (oleic and linoleic acids) in platelets stimulated by collagen or A23187 in the presence of PMA (50 nM), but not in the presence of DAGs. These findings imply that PMA may also affect the activation of DAG/MAG lipases, PLA1, or nonspecific PLA2. Since both 1,2-DiC8 and OAG exert no significant effect on the release of these fatty acids, the effects observed with PMA on DAG lipase/PLA1 may not

Darapladib Binds to Lipoprotein-Associated Phospholipase A2 with Meaningful Interactions

Energy Technology Data Exchange (ETDEWEB)

Do, Kyungrok; Chang, Byungha; Shin, Jae Min; No, Kyoung Tai; Lee, Jeeyoung [Bioinformatics and Molecular Design Research Center, Seoul (Korea, Republic of); Kim, Chul; Yea, Sangjun; Song, Miyoung [Korea Institute of Oriental Medicine, Daejeon (Korea, Republic of)

2014-01-15

Lipoprotein-associated phospholipase A{sub 2} (Lp-PLA{sub 2}) is a crucial enzyme in atherosclerosis as a potential drug target. The most remarkable Lp-PLA{sub 2} inhibitory drug is Darapladib. We determined the binding pose of Darapladib to Lp-PLA{sub 2} through docking study. Darapladib formed two hydrogen bonding interactions with the side chain of Tyr160 and Gln352 and several pi-pi interactions with aromatic and aliphatic hydrophobic residues of Lp-PLA{sub 2}. It is known that the dietylpropan-amine moiety of Darapladib has influence on the improvement of its oral bioavailability and we supposed this in our docking results.

Bee Venom Phospholipase A2: Yesterday’s Enemy Becomes Today’s Friend

OpenAIRE

Gihyun Lee; Hyunsu Bae

2016-01-01

Bee venom therapy has been used to treat immune-related diseases such as arthritis for a long time. Recently, it has revealed that group III secretory phospholipase A2 from bee venom (bee venom group III sPLA2) has in vitro and in vivo immunomodulatory effects. A growing number of reports have demonstrated the therapeutic effects of bee venom group III sPLA2. Notably, new experimental data have shown protective immune responses of bee venom group III sPLA2 against a wide range of diseases inc...

Synthesis of sn-1 functionalized phospholipids as substrates for secretory phospholipase A₂

DEFF Research Database (Denmark)

Linderoth, Lars; Peters, Günther H.J.; Jørgensen, K.

2007-01-01

Secretory phospholipase A2 (sPLA2) represents a family of small water-soluble enzymes that catalyze the hydrolysis of phospholipids in the sn-2 position liberating free fatty acids and lysophospholipids. Herein we report the synthesis of two new phospholipids (1 and 2) with bulky allyl-substituen......Secretory phospholipase A2 (sPLA2) represents a family of small water-soluble enzymes that catalyze the hydrolysis of phospholipids in the sn-2 position liberating free fatty acids and lysophospholipids. Herein we report the synthesis of two new phospholipids (1 and 2) with bulky allyl...... of the allyl-substituents by a zinc mediated allylation. Small unilamellar liposomes composed of phospholipids 1 and 2 were subjected to sPLA2 activity measurements. Our results show that only phospholipid 1 is hydrolyzed by the enzyme. Molecular dynamics simulations revealed that the lack of hydrolysis...

Activation of phospholipase A2 by temporin B: Formation of antimicrobial peptide-enzyme amyloid-type cofibrils

NARCIS (Netherlands)

Code, Christian; Domanov, Y.A.; Killian, J.A.; Kinnunen, P.K.J.

2009-01-01

Phospholipases A2 have been shown to be activated in a concentration dependent manner by a number of antimicrobial peptides, including melittin, magainin 2, indolicidin, and temporins B and L. Here we used fluorescently labelled bee venom PLA2 (PLA2D) and the saturated phospholipid substrate

Activities of native and tyrosine-69 mutant phospholipases A2 on phospholipid analogues. A reevaluation of the minimal substrate requirements.

Science.gov (United States)

Kuipers, O P; Dekker, N; Verheij, H M; de Haas, G H

1990-06-26

The role of Tyr-69 of porcine pancreatic phospholipase A2 in substrate binding was studied with the help of proteins modified by site-directed mutagenesis and phospholipid analogues with a changed head-group geometry. Two mutants were used containing Phe and Lys, respectively, at position 69. Modifications in the phospholipids included introduction of a sulfur at the phosphorus (thionophospholipids), removal of the negative charge at phosphorus (phosphatidic acid dimethyl ester), and reduction (phosphonolipids) or extension (diacylbutanetriol choline phosphate) of the distance between the phosphorus and the acyl ester bond. Replacement of Tyr-69 by Lys reduces enzymatic activity, but the mutant enzyme retains both the stereospecificity and positional specificity of native phospholipase A2. The Phe-69 mutant not only hydrolyzes the Rp isomer of thionophospholipids more efficiently than the wild-type enzyme, but the Sp thiono isomer is hydrolyzed too, although at a low (approximately 4%) rate. Phosphonolipids are hydrolyzed by native phospholipase A2 about 7 times more slowly than natural phospholipids, with retention of positional specificity and a (partial) loss of stereospecificity. The dimethyl ester of phosphatidic acid is degraded efficiently in a calcium-dependent and positional-specific way by native phospholipase A2 and by the mutants, indicating that a negative charge at phosphorus is not an absolute substrate requirement. The activities on the phosphatidic acid dimethyl ester of native enzyme and the Lys-69 mutant are lower than those on the corresponding lecithin, in contrast to the Phe-69 mutant, which has equal activities on both substrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular details of secretory phospholipase A2 from flax (Linum usitatissimum L.) provide insight into its structure and function.

Science.gov (United States)

Gupta, Payal; Dash, Prasanta K

2017-09-11

Secretory phospholipase A 2 (sPLA 2 ) are low molecular weight proteins (12-18 kDa) involved in a suite of plant cellular processes imparting growth and development. With myriad roles in physiological and biochemical processes in plants, detailed analysis of sPLA 2 in flax/linseed is meagre. The present work, first in flax, embodies cloning, expression, purification and molecular characterisation of two distinct sPLA 2 s (I and II) from flax. PLA 2 activity of the cloned sPLA 2 s were biochemically assayed authenticating them as bona fide phospholipase A 2 . Physiochemical properties of both the sPLA 2 s revealed they are thermostable proteins requiring di-valent cations for optimum activity.While, structural analysis of both the proteins revealed deviations in the amino acid sequence at C- & N-terminal regions; hydropathic study revealed LusPLA 2 I as a hydrophobic protein and LusPLA 2 II as a hydrophilic protein. Structural analysis of flax sPLA 2 s revealed that secondary structure of both the proteins are dominated by α-helix followed by random coils. Modular superimposition of LusPLA 2 isoforms with rice sPLA 2 confirmed monomeric structural preservation among plant phospholipase A 2 and provided insight into structure of folded flax sPLA 2 s.

AT32P-dependent estimation of nanomoles of fatty acids: Its use in the assay of phospholipase A2 activity

International Nuclear Information System (INIS)

Sarafianos, S.G.; Nair, P.P.; Kumar, S.

1990-01-01

A procedure for the assay of free fatty acids which has been adapted for the assay of phospholipase A2 is described. This consists of the conversion of long chain fatty acids to fatty acyl-CoA using the Mg2(+)-dependent fatty acyl-CoA synthetase, [alpha-32P]ATP and coenzyme A. In order to ensure the complete conversion of the acid to its CoA ester pyrophosphatase is also added to the incubation mixture. AM32P formed in stoichiometric amounts is separated from the remaining AT32P by polyethyleneimine-cellulose thin-layer chromatography and the fatty acid content is calculated from the specific radioactivity of AT32P. As little as 1 to 3 nmol of fatty acids hydrolyzed from any phospholipid using nanogram amounts of phospholipase A2 can be estimated with reliability. The real advantage of the method is that it combines the sensitivity of a radiochemical procedure without having to use radiolabeled substrates for the assay of phospholipases

Characterization of N-acyl phosphatidylethanolamine-specific phospholipase-D isoforms in the nematode Caenorhabditis elegans.

Directory of Open Access Journals (Sweden)

Neale Harrison

Full Text Available N-acylethanolamines are an important class of lipid signaling molecules found in many species, including the nematode Caenorhabditis elegans (C. elegans where they are involved in development and adult lifespan. In mammals, the relative activity of the biosynthetic enzyme N-acyl phosphatidylethanolamine-specific phospholipase-D and the hydrolytic enzyme fatty acid amide hydrolase determine N-acylethanolamine levels. C. elegans has two N-acyl phosphatidylethanolamine-specific phospholipase-D orthologs, nape-1 and nape-2, that are likely to have arisen from a gene duplication event. Here, we find that recombinant C. elegans NAPE-1 and NAPE-2 are capable of generating N-acylethanolamines in vitro, confirming their functional conservation. In vivo, they exhibit overlapping expression in the pharynx and the nervous system, but are also expressed discretely in these and other tissues, suggesting divergent roles. Indeed, nape-1 over-expression results in delayed growth and shortened lifespan only at 25°C, while nape-2 over-expression results in significant larval arrest and increased adult lifespan at 15°C. Interestingly, deletion of the N-acylethanolamine degradation enzyme faah-1 exacerbates nape-1 over-expression phenotypes, but suppresses the larval arrest phenotype of nape-2 over-expression, suggesting that faah-1 is coupled to nape-2, but not nape-1, in a negative feedback loop. We also find that over-expression of either nape-1 or nape-2 significantly enhances recovery from the dauer larval stage in the insulin signaling mutant daf-2(e1368, but only nape-1 over-expression reduces daf-2 adult lifespan, consistent with increased levels of the N-acylethanolamine eicosapentaenoyl ethanolamine. These results provide evidence that N-acylethanolamine biosynthetic enzymes in C. elegans have conserved function and suggest a temperature-dependent, functional divergence between the two isoforms.

Antimicrobial activity of apitoxin, melittin and phospholipase A2 of honey bee (Apis mellifera venom against oral pathogens

Directory of Open Access Journals (Sweden)

Luís F. Leandro

2015-03-01

Full Text Available In this work, we used the Minimum Inhibitory Concentration (MIC technique to evaluate the antibacterial potential of the apitoxin produced by Apis mellifera bees against the causative agents of tooth decay. Apitoxin was assayed in naturaand in the commercially available form. The antibacterial actions of the main components of this apitoxin, phospholipase A2, and melittin were also assessed, alone and in combination. The following bacteria were tested: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, Lactobacillus casei, and Enterococcus faecalis. The MIC results obtained for the commercially available apitoxin and for the apitoxin in natura were close and lay between 20 and 40µg / mL, which indicated good antibacterial activity. Melittin was the most active component in apitoxin; it displayed very promising MIC values, from 4 to 40µg / mL. Phospholipase A2 presented MIC values higher than 400µg / mL. Association of mellitin with phospholipase A2 yielded MIC values ranging between 6 and 80µg / mL. Considering that tooth decay affects people's health, apitoxin and its component melittin have potential application against oral pathogens.

Interplay of Mg2+, ADP, and ATP in the cytosol and mitochondria: unravelling the role of Mg2+ in cell respiration.

Science.gov (United States)

Gout, Elisabeth; Rébeillé, Fabrice; Douce, Roland; Bligny, Richard

2014-10-28

In animal and plant cells, the ATP/ADP ratio and/or energy charge are generally considered key parameters regulating metabolism and respiration. The major alternative issue of whether the cytosolic and mitochondrial concentrations of ADP and ATP directly mediate cell respiration remains unclear, however. In addition, because only free nucleotides are exchanged by the mitochondrial ADP/ATP carrier, whereas MgADP is the substrate of ATP synthase (EC 3.6.3.14), the cytosolic and mitochondrial Mg(2+) concentrations must be considered as well. Here we developed in vivo/in vitro techniques using (31)P-NMR spectroscopy to simultaneously measure these key components in subcellular compartments. We show that heterotrophic sycamore (Acer pseudoplatanus L.) cells incubated in various nutrient media contain low, stable cytosolic ADP and Mg(2+) concentrations, unlike ATP. ADP is mainly free in the cytosol, but complexed by Mg(2+) in the mitochondrial matrix, where [Mg(2+)] is tenfold higher. In contrast, owing to a much higher affinity for Mg(2+), ATP is mostly complexed by Mg(2+) in both compartments. Mg(2+) starvation used to alter cytosolic and mitochondrial [Mg(2+)] reversibly increases free nucleotide concentration in the cytosol and matrix, enhances ADP at the expense of ATP, decreases coupled respiration, and stops cell growth. We conclude that the cytosolic ADP concentration, and not ATP, ATP/ADP ratio, or energy charge, controls the respiration of plant cells. The Mg(2+) concentration, remarkably constant and low in the cytosol and tenfold higher in the matrix, mediates ADP/ATP exchange between the cytosol and matrix, [MgADP]-dependent mitochondrial ATP synthase activity, and cytosolic free ADP homeostasis.

Mitochondria-localized phospholipase A2, AoPlaA, in Aspergillus oryzae displays phosphatidylethanolamine-specific activity and is involved in the maintenance of mitochondrial phospholipid composition.

Science.gov (United States)

Kotani, Shohei; Izawa, Sho; Komai, Noriyuki; Takayanagi, Ayumi; Arioka, Manabu

2016-11-01

In mammals, cytosolic phospholipases A 2 (cPLA 2 s) play important physiological roles by releasing arachidonic acid, a precursor for bioactive lipid mediators, from the biological membranes. In contrast, fungal cPLA 2 -like proteins are much less characterized and their roles have remained elusive. AoPlaA is a cPLA 2 -like protein in the filamentous fungus Aspergillus oryzae which, unlike mammalian cPLA 2 , localizes to mitochondria. In this study, we investigated the biochemical and physiological functions of AoPlaA. Recombinant AoPlaA produced in E. coli displayed Ca 2+ -independent lipolytic activity. Mass spectrometry analysis demonstrated that AoPlaA displayed PLA 2 activity to phosphatidylethanolamine (PE), but not to other phospholipids, and generated 1-acylated lysoPE. Catalytic site mutants of AoPlaA displayed almost no or largely reduced activity to PE. Consistent with PE-specific activity of AoPlaA, AoplaA-overexpressing strain showed decreased PE content in the mitochondrial fraction. In contrast, AoplaA-disruption strain displayed increased content of cardiolipin. AoplaA-overexpressing strain, but not its counterparts overexpressing the catalytic site mutants, exhibited retarded growth at low temperature, possibly because of the impairment of the mitochondrial function caused by excess degradation of PE. These results suggest that AoPlaA is a novel PE-specific PLA 2 that plays a regulatory role in the maintenance of mitochondrial phospholipid composition. Copyright © 2016 Elsevier Inc. All rights reserved.

The secretory phospholipase A2 group IIA: a missing link between inflammation, activated renin-angiotensin system, and atherogenesis?

Directory of Open Access Journals (Sweden)

Dimitar Divchev

2008-06-01

Full Text Available Dimitar Divchev, Bernhard SchiefferDepartment of Cardiology and Angiology, Medizinische Hochschule Hannover, GermanyAbstract: Inflammation, lipid peroxidation and chronic activation of the renin–angiotensin system (RAS are hallmarks of the development of atherosclerosis. Recent studies have suggested the involvement of the pro-inflammatory secretory phospholipase A2 (sPLA2-IIA in atherogenesis. This enzyme is produced by different cell types through stimulation by proinflammatory cytokines. It is detectable in the intima and in media smooth muscle cells, not only in atherosclerotic lesions but also in the very early stages of atherogenesis. sPLA2-IIA can hydrolyse the phospholipid monolayers of low density lipoproteins (LDL. Such modified LDL show increased affinity to proteoglycans. The modified particles have a greater tendency to aggregate and an enhanced ability to insert cholesterol into cells. This modification may promote macrophage LDL uptake leading to the formation of foam cells. Furthermore, sPLA2-IIA is not only a mediator for localized inflammation but may be also used as an independent predictor of adverse outcomes in patients with stable coronary artery disease or acute coronary syndromes. An interaction between activated RAS and phospholipases has been indicated by observations showing that inhibitors of sPLA2 decrease angiotensin (Ang II-induced macrophage lipid peroxidation. Meanwhile, various interactions between Ang II and oxLDL have been demonstrated suggesting a central role of sPLA2-IIA in these processes and offering a possible target for treatment. The role of sPLA2-IIA in the perpetuation of atherosclerosis appears to be the missing link between inflammation, activated RAS and lipidperoxidation.Keywords: secretory phospholipase A2, lipoproteins, renin-angiotensin system, inflammation, atherosclerosis

Identification and characterization of phospholipase A2 (PLA2) in bovine pulmonary endothelial cells (BPEC)

International Nuclear Information System (INIS)

Martin, T.W.; Wysolmerski, R.B.; Lagunoff, D.

1986-01-01

Phosphatidylcholine labeled in the sn-2 position with 3 H-oleic acid was used to measure PLA 2 in cell sonicates (CS) prepared from confluent cultures of BPEC. Substrate at 10-200 μM was incubated with 5-30 μg of CS protein in HEPES buffer at 37 0 C. A plot of 3 H-oleic acid release vs time was linear and proportional to the amount of CS protein. Lineweaver-Burk plots of the data were linear with V/sub max/ = 22.2 nmole/mg protein/hr and K/sub d/ = 121 μM. Under these conditions, phospholipase C activity was 20-fold lower, and phospholipase A 1 activity was not detectable. PLA 2 activity was pH-dependent with optima at 4.5 and 7.5. Ca ++ was not required for activity, and addition of up to 10 mM Ca ++ to CS in EDTA increased activity by only 10-20%. After centrifugation of CS at 100,000 g for 90 min, 62% of the PLA 2 activity was recovered in the particular fraction. Triton X-100 (0.006-0.4%) inhibited PLA 2 up to 90%, whereas 2 mM deoxycholate produced nearly 3-fold activation. Of several agents tested, bromophenacylbromide (BPB) was the most effective inhibitor. Treatment of CS with BPB at 37 0 C for 30 min produced up to 9% inhibition (K/sub i/ = 5 μM). Phenylmethanesulfonyl fluoride at 200 μm produced 41% inhibition. Quinacrine at 1 mM inhibited PLA 2 by 18%. These data define characteristics of BPEC PLA 2 that should prove useful in studies of the role of this enzyme in specific cellular functions

Phospholipase A2-treated human high-density lipoprotein and cholesterol movements: exchange processes and lecithin: cholesterol acyltransferase reactivity.

Science.gov (United States)

Chollet, F; Perret, B P; Chap, H; Douste-Blazy, L

1986-02-12

Human HDL3 (d 1.125-1.21 g/ml) were treated by an exogenous phospholipase A2 from Crotalus adamenteus in the presence of albumin. Phosphatidylcholine hydrolysis ranged between 30 and 90% and the reisolated particle was essentially devoid of lipolysis products. (1) An exchange of free cholesterol was recorded between radiolabelled erythrocytes at 5-10% haematocrit and HDL3 (0.6 mM total cholesterol) from 0 to 12-15 h. Isotopic equilibration was reached. Kinetic analysis of the data indicated a constant rate of free cholesterol exchange of 13.0 microM/h with a half-time of equilibration around 3 h. Very similar values of cholesterol exchange, specific radioactivities and kinetic parameters were measured when phospholipase-treated HDL replaced control HDL. (2) The lecithin: cholesterol acyltransferase reactivity of HDL3, containing different amounts of phosphatidylcholine, as achieved by various degrees of phospholipase A2 treatment, was measured using a crude preparation of lecithin: cholesterol acyltransferase (the d 1.21-1.25 g/ml plasma fraction). The rate of esterification was determined between 0 and 12 h. Following a 15-30% lipolysis, the lecithin: cholesterol acyltransferase reactivity of HDL3 was reduced about 30-40%, and then continued to decrease, though more slowly, as the phospholipid content was further lowered in the particle. (3) The addition of the lecithin: cholesterol acyltransferase preparation into an incubation medium made of labelled erythrocytes and HDL3 promoted a movement of radioactive cholesterol out of cells, above the values of exchange, and an accumulation of cholesteryl esters in HDL. This reflected a mass consumption of free cholesterol, from both the cellular and the lipoprotein compartments upon the lecithin: cholesterol acyltransferase action. As a consequence of a decreased reactivity, phospholipase-treated HDL (with 2/3 of phosphatidylcholine hydrolyzed) proved much less effective in the lecithin: cholesterol acyltransferase

Cell Swelling Activates Phospholipase A2 in Ehrlich Ascites Tumor Cells

DEFF Research Database (Denmark)

Thoroed, S.M.; Lauritzen, L.; Lambert, I.H.

1997-01-01

Ehrlich ascites tumor cells! loaded with H-labeled arachidonic acid and C-labeled stearic acid for two hours, were washed and transferred to either isotonic or hypotonic media containing BSA to scavenge the labeled fatty acids released from the cells. During the first two minutes of hypo......-osmotic exposure the rate of H-labeled arachidonic acid release is 3.3 times higher than that observed at normal osmolality. Cell swelling also causes an increase in the production of C-stearic acid-labeled lysophosphatidylcholine. This indicates that a phospholipase A is activated by cell swelling in the Ehrlich...... cells. Within the same time frame there is no swelling-induced increase in C-labeled stearic acid release nor in the synthesis of phosphatidyl C-butanol in the presence of C-butanol. Furthermore, U7312, an inhibitor of phospholipase C, does not affect the swelling induced release of C...

Prognostic significance of cytosolic pS2 content in ovarian tumors

International Nuclear Information System (INIS)

Raigoso, P.; Allende, T.; Zeidan, N.; Llana, B.; Bernardo, L.; Roiz, C.; Tejuca, S.; Vazquez, J.; Lamelas, M.L.

2002-01-01

Aim: pS2 is an estrogen regulated peptide which has been associated with a good prognosis an with a more favorable response to treatment in breast cancer patients. In ovarian tumors, the expression of pS2 was demonstrated at both mRNA and protein levels. In addition, it has been showed significant association of pS2 with mucinous differentiation or well differentiation grade of the tumors. However, it is little know about the prognostic significance of the pS2 content in ovarian carcinomas. The aims of the present work were to analyze the cytosolic pS2 content in benign and malignant ovarian tumors, its relationship with clinico-pathologic parameters, steroid receptor status, and prognostic significance. Material and Methods: We analysed the cytosolic concentrations of pS2 in 91 specimen ovarian tissues by an immunoradiometric assay (ELSA-pS2, CIS, France). The tissues were 8 normal ovaries, 43 benign tumors and 40 malignant ovarian tumors. The same ovarian tissues processed to pS2 were analyzed to Estrogen (ER) and Progesterone (PgR) Receptor status. These steroid receptors were quantified biochemically following commercial ELISA method (ABBOTT Diagnostics, Germany). The relationship between cytosolic content and clinico-pathologic factors was examined by the Mann-Whitney or Kruskall-Wallis test. Correlation between steroid receptors and pS2 content was calculated with the Spearman test. Survival curves were calculated using the Kaplan-Meier method and compared by the log-rank test. Differences were considered significant at 5% probability level. Results: pS2 could be detected in 30 cases (32.9%) with values ranged from 0.04 to 89 ng/mg prt. Only one normal ovary showed detectable levels of pS2 and there were not differences in cytosolic content between benign and malignant ovarian tumors. The pS2 levels were only associated to mucinous differentiation in both benign and malignant ovarian tumors (p=0.029 and p=0.015, respectively). Significantly higher

Phospholipase A/sub 2/ activity towards vesicles of DPPC and DMPC-DSPC containing small amounts of SMPC

DEFF Research Database (Denmark)

Høyrup, Lise Pernille Kristine; Mouritsen, Ole G.; Jørgensen, Kent

2001-01-01

Phospholipase A/sub 2/ (PLA/sub 2/) is an interfacially active enzyme whose hydrolytic activity is known to be enhanced in one-component phospholipid bilayer substrates exhibiting dynamic micro-heterogeneity. In this study the activity of PLA/sub 2/ towards large unilamellar vesicles composed of ...

Interaction between VEGF and Calcium-Independent Phospholipase A(2) in Proliferation and Migration of Retinal Pigment Epithelium

DEFF Research Database (Denmark)

Toft-Kehler, Anne Katrine; Andersen, Emelie Cammilla; Andreasen, Jens Rovelt

2012-01-01

Purpose: Inhibition of VEGF in the eye is an important treatment modality for reducing proliferation and migration of retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). Additionally, previous studies suggest calcium-independent phospholipase A2 group VIA (iPLA2-VIA) to be...

Dissociation of bradykinin-induced prostaglandin formation from phosphatidylinositol turnover in Swiss 3T3 fibroblasts: evidence for G protein regulation of phospholipase A2

International Nuclear Information System (INIS)

Burch, R.M.; Axelrod, J.

1987-01-01

In Swiss 3T3 fibroblasts bradykinin stimulated inositol phosphate (InsP) formation and prostaglandin E 2 (PGE 2 ) synthesis. The EC 50 values for stimulation of PGE 2 synthesis and InsP formation by bradykinin were similar, 200 pM and 275 pM, respectively. Guanosine-5'-[γ-thio]triphosphate stimulated PGE 2 synthesis and InsP formation, and guanosine-5'-[β-thio]diphosphate inhibited both PGE 2 synthesis and InsP formation stimulated by bradykinin. Neither bradykinin-stimulated PGE 2 synthesis nor InsP formation was sensitive to pertussis toxin. Phorbol ester, dexamethasone, and cycloheximide distinguished between bradykinin-stimulated PGE 2 synthesis and InsP formation. Phorbol 12-myristate 13-acetate enhanced bradykinin-stimulated PGE 2 synthesis but inhibited bradykinin-stimulated InsP formation. Pretreatment of cells with dexamethasone for 24 hr inhibited bradykinin-stimulated PGE 2 synthesis but was without effect on bradykinin-stimulated InsP formation. Cycloheximide inhibited on bradykinin-stimulated InsP formation. When bradykinin was added to cells prelabeled with [ 3 H] choline, the phospholipase A 2 products lysophosphatidylcholine and glycerophosphocholine were generated. The data suggest that bradykinin receptors are coupled by GTP-binding proteins to both phospholipase C and phospholipase A 2 and that phospholipase A 2 is the enzyme that catalyzes release of arachidonate for prostaglandin synthesis

1H-NMR and photochemically-induced dynamic nuclear polarization studies on bovine pancreatic phospholipase A2

NARCIS (Netherlands)

Egmond, M.R.; Slotboom, A.J.; Haas, G.H. de; Dijkstra, Klaas; Kaptein, R.

1980-01-01

Proton-NMR resonances of trytophan 3 and tyrosine 69 in bovine pancreatic phospholipase A2, its pro-enzyme and in Ala1-transaminated protein were assigned using photochemically-induced dynamic nuclear polarization (photo-CIDNP) as such or in combination with spin-echo measurements. In addition

Activated platelets contribute to oxidized low-density lipoproteins and dysfunctional high-density lipoproteins through a phospholipase A2-dependent mechanism

NARCIS (Netherlands)

Blache, Denis; Gautier, Thomas; Tietge, Uwe J. F.; Lagrost, Laurent

Plasma activity of secretory phospholipase A2 (sPLA2) increases in patients with cardiovascular disease. The present study investigated whether platelet-released sPLA2 induces low-density lipoprotein (LDL) and high-density lipoprotein (HDL) modifications that translate into changes in lipoprotein

Gangliosides inhibit bee venom melittin cytotoxicity but not phospholipase A2-induced degranulation in mast cells

International Nuclear Information System (INIS)

Nishikawa, Hirofumi; Kitani, Seiichi

2011-01-01

Sting accident by honeybee causes severe pain, inflammation and allergic reaction through IgE-mediated anaphylaxis. In addition to this hypersensitivity, an anaphylactoid reaction occurs by toxic effects even in a non-allergic person via cytolysis followed by similar clinical manifestations. Auto-injectable epinephrine might be effective for bee stings, but cannot inhibit mast cell lysis and degranulation by venom toxins. We used connective tissue type canine mast cell line (CM-MC) for finding an effective measure that might inhibit bee venom toxicity. We evaluated degranulation and cytotoxicity by measurement of β-hexosaminidase release and MTT assay. Melittin and crude bee venom induced the degranulation and cytotoxicity, which were strongly inhibited by mono-sialoganglioside (G M1 ), di-sialoganglioside (G D1a ) and tri-sialoganglioside (G T1b ). In contrast, honeybee venom-derived phospholipase A 2 induced the net degranulation directly without cytotoxicity, which was not inhibited by G M1 , G D1a and G T1b . For analysis of distribution of Gα q and Gα i protein by western blotting, lipid rafts were isolated by using discontinuous sucrose gradient centrifuge. Melittin disrupted the localization of Gα q and Gα i at lipid raft, but gangliosides stabilized the rafts. As a result from this cell-based study, bee venom-induced anaphylactoid reaction can be explained with melittin cytotoxicity and phospholipase A 2 -induced degranulation. Taken together, gangliosides inhibit the effect of melittin such as degranulation, cytotoxicity and lipid raft disruption but not phospholipase A 2 -induced degranulation in mast cells. Our study shows a potential of gangliosides as a therapeutic tool for anaphylactoid reaction by honeybee sting.

Kinetic characterization of Escherichia coli outer membrane phospholipase A using mixed detergent-lipid micelles.

Science.gov (United States)

Horrevoets, A J; Hackeng, T M; Verheij, H M; Dijkman, R; de Haas, G H

1989-02-07

The substrate specificity of Escherichia coli outer membrane phospholipase A was analyzed in mixed micelles of lipid with deoxycholate or Triton X-100. Diglycerides, monoglycerides, and Tweens 40 and 85 in Triton X-100 are hydrolyzed at rates comparable to those of phospholipids and lysophospholipids. p-Nitrophenyl esters of fatty acids with different chain lengths and triglycerides are not hydrolyzed. The minimal substrate characteristics consist of a long acyl chain esterified to a more or less hydrophilic headgroup as is the case for the substrate monopalmitoylglycol. Binding occurs via the hydrocarbon chain of the substrate; diacyl compounds are bound three to five times better than monoacyl compounds. When acting on lecithins, phospholipase A1 activity is six times higher than phospholipase A2 activity or 1-acyl lysophospholipase activity. Activity on the 2-acyl lyso compound is about two times less than that on the 1-acyl lysophospholipid. The enzyme therefore has a clear preference for the primary ester bond of phospholipids. In contrast to phospholipase A1 activity, phospholipase A2 activity is stereospecific. Only the L isomer of a lecithin analogue in which the primary acyl chain was replaced by an alkyl ether group is hydrolyzed. The D isomer of this analogue is a competitive inhibitor, bound with the same affinity as the L isomer. On these ether analogues the enzyme shows the same preference for the primary acyl chain as with the natural diester phospholipids. Despite its broad specificity, the enzyme will initially act as a phospholipase A1 in the E. coli envelope where it is embedded in phospholipids.

Protein kinase C promotes restoration of calcium homeostasis to platelet activating factor-stimulated human neutrophils by inhibition of phospholipase C

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Anderson Ronald

2009-10-01

Full Text Available Abstract Background The role of protein kinase C (PKC in regulating the activity of phospholipase C (PLC in neutrophils activated with the chemoattractant, platelet-activating factor (PAF, 20 and 200 nM, was probed in the current study using the selective PKC inhibitors, GF10903X (0.5 - 1 μM and staurosporine (400 nM. Methods Alterations in cytosolic Ca2+, Ca2+ influx, inositol triphosphate (IP3, and leukotriene B4 production were measured using spectrofluorimetric, radiometric and competitive binding radioreceptor and immunoassay procedures, respectively. Results Activation of the cells with PAF was accompanied by an abrupt increase in cytosolic Ca2+ followed by a gradual decline towards basal levels. Pretreatment of neutrophils with the PKC inhibitors significantly increased IP3 production with associated enhanced Ca2+ release from storage vesicles, prolongation of the peak cytosolic Ca2+ transients, delayed clearance and exaggerated reuptake of the cation, and markedly increased synthesis of LTB4. The alterations in Ca2+ fluxes observed with the PKC inhibitors were significantly attenuated by U73122, a PLC inhibitor, as well as by cyclic AMP-mediated upregulation of the Ca2+-resequestering endomembrane ATPase. Taken together, these observations are compatible with a mechanism whereby PKC negatively modulates the activity of PLC, with consequent suppression of IP3 production and down-regulation of Ca2+ mediated pro-inflammatory responses of PAF-activated neutrophils. Conclusion Although generally considered to initiate and/or amplify intracellular signalling cascades which activate and sustain the pro-inflammatory activities of neutrophils and other cell types, the findings of the current study have identified a potentially important physiological, anti-inflammatory function for PKC, at least in neutrophils.

Crystallization and preliminary X-ray crystallographic studies of a Lys49-phospholipase A2 homologue from Bothrops pirajai venom complexed with rosmarinic acid

International Nuclear Information System (INIS)

Santos, Juliana I. dos; Santos-Filho, Norival A.; Soares, Andreimar M.; Fontes, Marcos R. M.

2010-01-01

PrTX-I, a noncatalytic and myotoxic Lys49-phospholipase A 2 from B. pirajai venom, was cocrystallized with the inhibitor rosmarinic acid from C. verbenacea. The crystals diffracted X-rays to 1.8 Å resolution and the structure was solved, indicating a remarkable electronic density for the ligand at the entrance to the hydrophobic channel. PrTX-I, a noncatalytic and myotoxic Lys49-phospholipase A 2 from Bothrops pirajai venom, was crystallized in the presence of the inhibitor rosmarinic acid (RA). This is the active compound in the methanolic extract of Cordia verbenacea, a plant that is largely used in Brazilian folk medicine. The crystals diffracted X-rays to 1.8 Å resolution and the structure was solved by molecular-replacement techniques, showing electron density that corresponds to RA molecules at the entrance to the hydrophobic channel. The crystals belong to space group P2 1 2 1 2 1 , indicating conformational changes in the structure after ligand binding: the crystals of all apo Lys49-phospholipase A 2 structures belong to space group P3 1 21, while the crystals of complexed structures belong to space groups P2 1 or P2 1 2 1 2 1

Hemolytic potency and phospholipase activity of some bee and wasp venoms.

Science.gov (United States)

Watala, C; Kowalczyk, J K

1990-01-01

1. The action of crude venoms of four aculeate species: Apis mellifera, Vespa crabro, Vespula germanica and Vespula vulgaris on human erythrocytes was investigated in order to determine the lytic and phospholipase activity of different aculeate venoms and their ability to induce red blood cell hemolysis. 2. Bee venom was the only extract to completely lyse red blood cells at the concentration of 2-3 micrograms/ml. 3. Phospholipase activity in all of the examined vespid venoms was similar and the highest value was recorded in V. germanica. 4. Vespid venoms exhibited phospholipase B activity, which is lacking in honeybee venom. 5. In all membrane phospholipids but lecithin, lysophospholipase activity of vespid venoms was 2-6 times lower than the relevant phospholipase activity. 6. The incubation of red blood cells with purified bee venom phospholipase A2 was not accompanied by lysis and, when supplemented with purified melittin, the increase of red blood cell lysis was approximately 30%.

Bee venom phospholipase A2 as a membrane-binding vector for cell surface display or internalization of soluble proteins.

Science.gov (United States)

Babon, Aurélie; Wurceldorf, Thibault; Almunia, Christine; Pichard, Sylvain; Chenal, Alexandre; Buhot, Cécile; Beaumelle, Bruno; Gillet, Daniel

2016-06-15

We showed that bee venom phospholipase A2 can be used as a membrane-binding vector to anchor to the surface of cells a soluble protein fused to its C-terminus. ZZ, a two-domain derivative of staphylococcal protein A capable of binding constant regions of antibodies was fused to the C-terminus of the phospholipase or to a mutant devoid of enzymatic activity. The fusion proteins bound to the surface of cells and could themselves bind IgGs. Their fate depended on the cell type to which they bound. On the A431 carcinoma cell line the proteins remained exposed on the cell surface. In contrast, on human dendritic cells the proteins were internalized into early endosomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Methylmercury-induced toxicity is mediated by enhanced intracellular calcium through activation of phosphatidylcholine-specific phospholipase C

International Nuclear Information System (INIS)

Kang, Mi Sun; Jeong, Ju Yeon; Seo, Ji Heui; Jeon, Hyung Jun; Jung, Kwang Mook; Chin, Mi-Reyoung; Moon, Chang-Kiu; Bonventre, Joseph V.; Jung, Sung Yun; Kim, Dae Kyong

2006-01-01

Methylmercury (MeHg) is a ubiquitous environmental toxicant to which humans can be exposed by ingestion of contaminated food. MeHg has been suggested to exert its toxicity through its high reactivity to thiols, generation of arachidonic acid and reactive oxygen species (ROS), and elevation of free intracellular Ca 2+ levels ([Ca 2+ ] i ). However, the precise mechanism has not been fully defined. Here we show that phosphatidylcholine-specific phospholipase C (PC-PLC) is a critical pathway for MeHg-induced toxicity in MDCK cells. D609, an inhibitor of PC-PLC, significantly reversed the toxicity in a time- and dose-dependent manner with concomitant inhibition of the diacylglycerol (DAG) generation and the phosphatidylcholine (PC)-breakdown. MeHg activated the group IV cytosolic phospholipase A 2 (cPLA 2 ) and acidic form of sphingomyelinase (A-SMase) downstream of PC-PLC, but these enzymes as well as protein kinase C (PKC) were not linked to the toxicity by MeHg. Furthermore, MeHg produced ROS, which did not affect the toxicity. Addition of EGTA to culture media resulted in partial decrease of [Ca 2+ ] i and partially blocked the toxicity. In contrast, when the cells were treated with MeHg in the presence of Ca 2+ in the culture media, D609 completely prevented cell death with parallel decrease in [Ca 2+ ] i . Our results demonstrated that MeHg-induced toxicity was linked to elevation of [Ca 2+ ] i through activation of PC-PLC, but not attributable to the signaling pathways such as cPLA 2 , A-SMase, and PKC, or to the generation of ROS

Secretory Phospholipase A₂ Hydrolysis Phospholipid Analogs is Dependent on Water Accessibility to the Active Site

DEFF Research Database (Denmark)

Peters, Günther H.J.; Møller, Martin S.; Jørgensen, Kent

2007-01-01

A new and unnatural type of phospholipids with the head group attached to the 2-position of the glycerol backbone has been synthesized and shown to be a good substrate for secretory phospholipase A2 (sPLA2). To investigate the unexpected sPLA2 activity, we have compared three different phospholip...

Purification and biochemical characterization of pancreatic phospholipase A2 from the common stingray Dasyatis pastinaca

Directory of Open Access Journals (Sweden)

Gargouri Youssef

2011-02-01

Full Text Available Abstract Background Mammalian sPLA2-IB are well characterized. In contrast, much less is known about aquatic ones. The aquatic world contains a wide variety of living species and, hence represents a great potential for discovering new lipolytic enzymes. Results A marine stingray phospholipase A2 (SPLA2 was purified from delipidated pancreas. Purified SPLA2, which is not glycosylated protein, was found to be monomeric protein with a molecular mass of 14 kDa. A specific activity of 750 U/mg for purified SPLA2 was measured at optimal conditions (pH 8.5 and 40 °C in the presence of 4 mM NaTDC and 8 mM CaCl2 using PC as substrate. The sequence of the first twenty first amino-acid residues at the N-terminal extremity of SPLA2 was determined and shows a close similarity with known mammal and bird pancreatic secreted phospholipases A2. SPLA2 stability in the presence of organic solvents, as well as in acidic and alkaline pH and at high temperature makes it a good candidate for its application in food industry. Conclusions SPLA2 has several advantageous features for industrial applications. Stability of SPLA2 in the presence of organic solvents, and its tolerance to high temperatures, basic and acidic pH, makes it a good candidate for application in food industry to treat phospholipid-rich industrial effluents, or to synthesize useful chemical compounds.

Chemoenzymatic synthesis of fluorogenic phospholipids and evaluation in assays of phospholipases A, C and D

DEFF Research Database (Denmark)

Piel, Mathilde S.; Peters, Günther H.J.; Brask, Jesper

2017-01-01

Phospholipases are ubiquitous in nature and the target of significant research aiming at both their physiological roles and technical applications in e.g. the food industry. In the search for sensitive and selective phospholipase assays, we have focused on synthetic FRET (Forster resonance energy...... lyso-(dansyl-FA)-GPE-dabcyl (6) and (dansyl-FA)2-GPE-dabcyl (7) were synthesized by a chemoenzymatic strategy, in which preparation of (6) further included a novel selective enzymatic esterification step. As proof of concept, activity of a handful of phospholipases, one from each of the PLA1, PLA2, PLC...

Gangliosides inhibit bee venom melittin cytotoxicity but not phospholipase A(2)-induced degranulation in mast cells.

Science.gov (United States)

Nishikawa, Hirofumi; Kitani, Seiichi

2011-05-01

Sting accident by honeybee causes severe pain, inflammation and allergic reaction through IgE-mediated anaphylaxis. In addition to this hypersensitivity, an anaphylactoid reaction occurs by toxic effects even in a non-allergic person via cytolysis followed by similar clinical manifestations. Auto-injectable epinephrine might be effective for bee stings, but cannot inhibit mast cell lysis and degranulation by venom toxins. We used connective tissue type canine mast cell line (CM-MC) for finding an effective measure that might inhibit bee venom toxicity. We evaluated degranulation and cytotoxicity by measurement of β-hexosaminidase release and MTT assay. Melittin and crude bee venom induced the degranulation and cytotoxicity, which were strongly inhibited by mono-sialoganglioside (G(M1)), di-sialoganglioside (G(D1a)) and tri-sialoganglioside (G(T1b)). In contrast, honeybee venom-derived phospholipase A(2) induced the net degranulation directly without cytotoxicity, which was not inhibited by G(M1), G(D1a) and G(T1b). For analysis of distribution of Gα(q) and Gα(i) protein by western blotting, lipid rafts were isolated by using discontinuous sucrose gradient centrifuge. Melittin disrupted the localization of Gα(q) and Gα(i) at lipid raft, but gangliosides stabilized the rafts. As a result from this cell-based study, bee venom-induced anaphylactoid reaction can be explained with melittin cytotoxicity and phospholipase A(2)-induced degranulation. Taken together, gangliosides inhibit the effect of melittin such as degranulation, cytotoxicity and lipid raft disruption but not phospholipase A(2)-induced degranulation in mast cells. Our study shows a potential of gangliosides as a therapeutic tool for anaphylactoid reaction by honeybee sting. Copyright © 2011 Elsevier Inc. All rights reserved.

Human eosinophils express, relative to other circulating leukocytes, large amounts of secretory 14-kD phospholipase A2

NARCIS (Netherlands)

Blom, M.; Tool, A. T.; Wever, P. C.; Wolbink, G. J.; Brouwer, M. C. [=Maria Clara; Calafat, J.; Egesten, A.; Knol, E. F.; Hack, C. E.; Roos, D.; Verhoeven, A. J.

1998-01-01

Human eosinophils perform several functions dependent on phospholipase A2 (PLA2) activity, most notably the synthesis of platelet-activating factor (PAF) and leukotriene C4 (LTC4). Several forms of PLA2 have been identified in mammalian cells. In the present study, the 14-kD, secretory form of PLA2

Crystallization and preliminary X-ray crystallographic studies of a Lys49-phospholipase A{sub 2} homologue from Bothrops pirajai venom complexed with rosmarinic acid

Energy Technology Data Exchange (ETDEWEB)

Santos, Juliana I. dos [Departamento de Física e Biofísica, Instituto de Biociências, UNESP - Universidade Estadual Paulista, Botucatu-SP (Brazil); Instituto Nacional de Ciência e Tecnologia em Toxinas, CNPq (Brazil); Santos-Filho, Norival A.; Soares, Andreimar M. [Instituto Nacional de Ciência e Tecnologia em Toxinas, CNPq (Brazil); Departamento de Análizes Clínicas, Toxicológicas e Bromatológicas, FCFRP, USP, Ribeirão Preto-SP (Brazil); Fontes, Marcos R. M., [Departamento de Física e Biofísica, Instituto de Biociências, UNESP - Universidade Estadual Paulista, Botucatu-SP (Brazil); Instituto Nacional de Ciência e Tecnologia em Toxinas, CNPq (Brazil)

2010-06-01

PrTX-I, a noncatalytic and myotoxic Lys49-phospholipase A{sub 2} from B. pirajai venom, was cocrystallized with the inhibitor rosmarinic acid from C. verbenacea. The crystals diffracted X-rays to 1.8 Å resolution and the structure was solved, indicating a remarkable electronic density for the ligand at the entrance to the hydrophobic channel. PrTX-I, a noncatalytic and myotoxic Lys49-phospholipase A{sub 2} from Bothrops pirajai venom, was crystallized in the presence of the inhibitor rosmarinic acid (RA). This is the active compound in the methanolic extract of Cordia verbenacea, a plant that is largely used in Brazilian folk medicine. The crystals diffracted X-rays to 1.8 Å resolution and the structure was solved by molecular-replacement techniques, showing electron density that corresponds to RA molecules at the entrance to the hydrophobic channel. The crystals belong to space group P2{sub 1}2{sub 1}2{sub 1}, indicating conformational changes in the structure after ligand binding: the crystals of all apo Lys49-phospholipase A{sub 2} structures belong to space group P3{sub 1}21, while the crystals of complexed structures belong to space groups P2{sub 1} or P2{sub 1}2{sub 1}2{sub 1}.

The Arabidopsis thaliana non-specific phospholipase C2 is involved in the response to Pseudomonas syringae attack

Czech Academy of Sciences Publication Activity Database

Krčková, Zuzana; Kocourková, Daniela; Daněk, Michal; Brouzdová, Jitka; Pejchar, Přemysl; Janda, Martin; Pokotylo, I.; Ott, P.G.; Valentová, O.; Martinec, Jan

2018-01-01

Roč. 121, č. 2 (2018), s. 297-310 ISSN 0305-7364 R&D Projects: GA ČR(CZ) GAP501/12/1942 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * effector-triggered immunity * flagellin * MAMP-triggered immunity * non-specific phospholipase C * phosphatidylcholine-specific phospholipase C * Pseudomonas syringae * reactive oxygen species Subject RIV: ED - Physiology OBOR OECD: Plant sciences, botany Impact factor: 4.041, year: 2016

Antioxidant activity by a synergy of redox-sensitive mitochondrial phospholipase A2 and uncoupling protein-2 in lung and spleen

Czech Academy of Sciences Publication Activity Database

Jabůrek, Martin; Ježek, Jan; Zelenka, Jaroslav; Ježek, Petr

2013-01-01

Roč. 45, č. 4 (2013), s. 816-825 ISSN 1357-2725 R&D Projects: GA ČR(CZ) GAP302/10/0346; GA ČR(CZ) GPP303/11/P320; GA MŠk(CZ) ME09018 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : mitochondrial uncoupling protein UCP2 * mitochondrial phospholipase A(2) isoform gamma * mitochondrial oxidative stress attenuation * fatty acid * antioxidant mechanism Subject RIV: ED - Physiology Impact factor: 4.240, year: 2013

Lack of genetic association between the phospholipase A2 gene and bipolar mood disorder in a European multicentre case-control study.

Science.gov (United States)

Dikeos, Dimitris G; Papadimitriou, George N; Souery, Daniel; Del-Favero, Jurgen; Massat, Isabelle; Blackwood, Douglas; Cichon, Sven; Daskalopoulou, Eugenia; Ivezic, Sladjana; Kaneva, Radka; Karadima, Georgia; Lorenzi, Cristina; Milanova, Vihra; Muir, Walter; Nöthen, Markus; Oruc, Lilijana; Rietschel, Marcella; Serretti, Alessandro; Van Broeckhoven, Christine; Soldatos, Constantin R; Stefanis, Costas N; Mendlewicz, Julien

2006-08-01

The possible association between phospholipase A2 gene and bipolar mood disorder was examined in 557 bipolar patients and 725 controls (all personally interviewed), recruited from seven countries (Belgium, Bulgaria, Croatia, Germany, Greece, Italy, and UK). The frequencies of the eight alleles that were identified did not differ between patients and control individuals in the whole population, while the power to detect an association based on our sample was relatively high. Some differences were noted among the various ethnic groups, but no significant trends existed, suggesting that population stratification by country may not be responsible for a type II error. On the basis of these results, mutations of the phospholipase A2 gene, at least in the region close to the polymorphism examined between exons 1 and 2, are not involved in the pathogenesis of bipolar mood disorder.

Mitochondrial phospholipase A2 activated by reactive oxygen species in heart mitochondria induces mild uncoupling

Czech Academy of Sciences Publication Activity Database

Ježek, Jan; Jabůrek, Martin; Zelenka, Jaroslav; Ježek, Petr

2010-01-01

Roč. 59, č. 5 (2010), s. 737-747 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA303/07/0105; GA MŠk ME09018; GA AV ČR(CZ) KJB500110902 Institutional research plan: CEZ:AV0Z50110509 Keywords : Heart mitochondrial phospholipase A2 * Fatty Acids * Adenine nucleotide translocase Subject RIV: ED - Physiology Impact factor: 1.646, year: 2010

The effects of two phospholipase A2 inhibitors on the neuromuscular blocking activities of homologous phospholipases A2 from the venom of Pseudechis australis, the Australian king brown snake.

Science.gov (United States)

Fatehi, M; Rowan, E G; Harvey, A L

1995-12-01

Previous studies have shown that homologous phospholipases A2 (PLA2) (Pa-3, Pa-9C, Pa-10F and Pa-11) from the venom of the Australian king brown snake, Pseudechis australis, significantly reduce the resting membrane potentials and quantal contents of endplate potentials recorded from endplate regions of mouse triangularis sterni nerve-muscle preparations. It is not clear whether PLA2 activity is essential for their neuromuscular activities. Therefore, pharmacological studies were carried out to determine whether neuromuscular activity of the toxins changed after treatment with the phospholipase A2 inhibitors 7,7-dimethyl-eicosadienoic acid (DEDA) and manoalide. After incubation of the toxins with manoalide (120 nM), or DEDA (50 microM), no PLA2 activity against 1-stearoyl 2-[3H]arachidonoylglycerophosphocholine was detected. After incubation with manoalide and/or DEDA, the toxins did not depolarize muscle fibre membranes up to 60 min after administration. However, manoalide and DEDA had different influences on the inhibitory effect of these toxic enzymes on acetylcholine release from nerve terminals. Manoalide abolished the inhibitory effect of the toxins on evoked release of acetylcholine. In contrast, DEDA was not able to prevent the reduction of quantal content of endplate potentials induced by the toxins. This study provides evidence that the depolarizing action and the inhibitory effect on release of acetylcholine exerted by these toxic PLA2 from king brown snake are independent phenomena. The evidence for this conclusion was that inhibition of enzymatic activity with an arachidonic acid analogue (DEDA) abolished the depolarizing effect of the toxins but not the effects on the quantal release of acetylcholine from mouse motor nerve terminals. The data suggest that the depolarizing effect of these toxins is probably due to the enzymatic activity. Since manoalide interacts with lysine residues of PLA2 polypeptides, and, as shown here, manoalide prevented

Phospholipase A2 isolated from the venom of Crotalus durissus terrificus inactivates dengue virus and other enveloped viruses by disrupting the viral envelope.

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Vanessa Danielle Muller

Full Text Available The Flaviviridae family includes several virus pathogens associated with human diseases worldwide. Within this family, Dengue virus is the most serious threat to public health, especially in tropical and sub-tropical regions of the world. Currently, there are no vaccines or specific antiviral drugs against Dengue virus or against most of the viruses of this family. Therefore, the development of vaccines and the discovery of therapeutic compounds against the medically most important flaviviruses remain a global public health priority. We previously showed that phospholipase A2 isolated from the venom of Crotalus durissus terrificus was able to inhibit Dengue virus and Yellow fever virus infection in Vero cells. Here, we present evidence that phospholipase A2 has a direct effect on Dengue virus particles, inducing a partial exposure of genomic RNA, which strongly suggests inhibition via the cleavage of glycerophospholipids at the virus lipid bilayer envelope. This cleavage might induce a disruption of the lipid bilayer that causes a destabilization of the E proteins on the virus surface, resulting in inactivation. We show by computational analysis that phospholipase A2 might gain access to the Dengue virus lipid bilayer through the pores found on each of the twenty 3-fold vertices of the E protein shell on the virus surface. In addition, phospholipase A2 is able to inactivate other enveloped viruses, highlighting its potential as a natural product lead for developing broad-spectrum antiviral drugs.

MVL-PLA2, a snake venom phospholipase A2, inhibits angiogenesis through an increase in microtubule dynamics and disorganization of focal adhesions.

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Amine Bazaa

Full Text Available Integrins are essential protagonists of the complex multi-step process of angiogenesis that has now become a major target for the development of anticancer therapies. We recently reported and characterized that MVL-PLA2, a novel phospholipase A2 from Macrovipera lebetina venom, exhibited anti-integrin activity. In this study, we show that MVL-PLA2 also displays potent anti-angiogenic properties. This phospholipase A2 inhibited adhesion and migration of human microvascular-endothelial cells (HMEC-1 in a dose-dependent manner without being cytotoxic. Using Matrigel and chick chorioallantoic membrane assays, we demonstrated that MVL-PLA2, as well as its catalytically inactivated form, significantly inhibited angiogenesis both in vitro and in vivo. We have also found that the actin cytoskeleton and the distribution of alphav beta3 integrin, a critical regulator of angiogenesis and a major component of focal adhesions, were disturbed after MVL-PLA2 treatment. In order to further investigate the mechanism of action of this protein on endothelial cells, we analyzed the dynamic instability behavior of microtubules in living endothelial cells. Interestingly, we showed that MVL-PLA2 significantly increased microtubule dynamicity in HMEC-1 cells by 40%. We propose that the enhancement of microtubule dynamics may explain the alterations in the formation of focal adhesions, leading to inhibition of cell adhesion and migration.

The first report on coagulation and phospholipase A2 activities of Persian Gulf lionfish, Pterois russelli, an Iranian venomous fish.

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Memar, Bahareh; Jamili, Shahla; Shahbazzadeh, Delavar; Bagheri, Kamran Pooshang

2016-04-01

Pterois russelli is a venomous fish belonging to scorpionidae family. Regarding to high significance value for tracing potential therapeutic molecules and special agents from venomous marine creatures, the present study was aimed to characterization of the Persian Gulf lionfish venom. Proteolytic, phospholipase, hemolytic, coagulation, edematogenic and dermonecrotic activities were determined for extracted venom. The LD50 of P. russelli venom was determined by intravenous injection in white Balb/c mice. Phospholipase A2 activity was recorded at 20 μg of total venom. Coagulation activity on human plasma was shown by Prothrombin Time (PT) and activated Partial Thromboplastin Time (APTT) assays and coagulation visualized after 7 and 14 s respectively for 60 μg of crude venom. LD50 was calculated as 10.5 mg/kg. SDS-PAGE revealed the presence of major and minor protein bands between 6 and 205 kDa. Different amounts of crude venom ranged from 1.87 to 30 μg showed proteolytic activity on casein. The highest edematic activity was detected at 20 μg. Our findings showed that the edematic activity was dose dependent and persisted for 48 h after injection. The crude venom did not induce dermonecrotic activity on rabbit skin and showed no hemolytic activity on human, mouse and rabbit erythrocytes. This is the first report for phospholipase A2 and coagulation activity in venomous fish and venomous marine animals respectively. Proteolytic activity of P. russelli venom is in accordance with the other genara of scorpionidae family. According to venom activity on intrinsic and extrinsic coagulation pathways, lionfish venom would be contained an interesting pharmaceutical agent. This study is pending to further characterization of phospholipase A2, coagulation, and protease activities and also in vivo activity on animal model of surface and internal bleeding. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bee Venom Phospholipase A2: Yesterday's Enemy Becomes Today's Friend.

Science.gov (United States)

Lee, Gihyun; Bae, Hyunsu

2016-02-22

Bee venom therapy has been used to treat immune-related diseases such as arthritis for a long time. Recently, it has revealed that group III secretory phospholipase A2 from bee venom (bee venom group III sPLA2) has in vitro and in vivo immunomodulatory effects. A growing number of reports have demonstrated the therapeutic effects of bee venom group III sPLA2. Notably, new experimental data have shown protective immune responses of bee venom group III sPLA2 against a wide range of diseases including asthma, Parkinson's disease, and drug-induced organ inflammation. It is critical to evaluate the beneficial and adverse effects of bee venom group III sPLA2 because this enzyme is known to be the major allergen of bee venom that can cause anaphylactic shock. For many decades, efforts have been made to avoid its adverse effects. At high concentrations, exposure to bee venom group III sPLA2 can result in damage to cellular membranes and necrotic cell death. In this review, we summarized the current knowledge about the therapeutic effects of bee venom group III sPLA2 on several immunological diseases and described the detailed mechanisms of bee venom group III sPLA2 in regulating various immune responses and physiopathological changes.

Mechanism of inhibition of human secretory phospholipase A2 by flavonoids: rationale for lead design

Science.gov (United States)

Lättig, Jens; Böhl, Markus; Fischer, Petra; Tischer, Sandra; Tietböhl, Claudia; Menschikowski, Mario; Gutzeit, Herwig O.; Metz, Peter; Pisabarro, M. Teresa

2007-08-01

The human secretory phospholipase A2 group IIA (PLA2-IIA) is a lipolytic enzyme. Its inhibition leads to a decrease in eicosanoids levels and, thereby, to reduced inflammation. Therefore, PLA2-IIA is of high pharmacological interest in treatment of chronic diseases such as asthma and rheumatoid arthritis. Quercetin and naringenin, amongst other flavonoids, are known for their anti-inflammatory activity by modulation of enzymes of the arachidonic acid cascade. However, the mechanism by which flavonoids inhibit Phospholipase A2 (PLA2) remained unclear so far. Flavonoids are widely produced in plant tissues and, thereby, suitable targets for pharmaceutical extractions and chemical syntheses. Our work focuses on understanding the binding modes of flavonoids to PLA2, their inhibition mechanism and the rationale to modify them to obtain potent and specific inhibitors. Our computational and experimental studies focused on a set of 24 compounds including natural flavonoids and naringenin-based derivatives. Experimental results on PLA2-inhibition showed good inhibitory activity for quercetin, kaempferol, and galangin, but relatively poor for naringenin. Several naringenin derivatives were synthesized and tested for affinity and inhibitory activity improvement. 6-(1,1-dimethylallyl)naringenin revealed comparable PLA2 inhibition to quercetin-like compounds. We characterized the binding mode of these compounds and the determinants for their affinity, selectivity, and inhibitory potency. Based on our results, we suggest C(6) as the most promising position of the flavonoid scaffold to introduce chemical modifications to improve affinity, selectivity, and inhibition of PLA2-IIA by flavonoids.

Characterization and structural analysis of a potent anticoagulant phospholipase A2 from Pseudechis australis snake venom.

Science.gov (United States)

Du, Qianyun Sharon; Trabi, Manuela; Richards, Renée Stirling; Mirtschin, Peter; Madaras, Frank; Nouwens, Amanda; Zhao, Kong-Nan; de Jersey, John; Lavin, Martin F; Guddat, Luke W; Masci, Paul P

2016-03-01

Pseudechis australis is one of the most venomous and lethal snakes in Australia. Numerous phospholipase A2 (PLA2) isoforms constitute a major portion of its venom, some of which have previously been shown to exhibit not only enzymatic, but also haemolytic, neurotoxic and anticoagulant activities. Here, we have purified a potent anticoagulant PLA2 (identified as PA11) from P. australis venom to investigate its phospholipase, anticoagulant, haemolytic and cytotoxic activities and shown that addition of 11 nM PA11 resulted in a doubling of the clotting time of recalcified whole blood. We have also demonstrated that PA11 has high PLA2 enzymatic activity (10.9 × 10(4) Units/mg), but low haemolytic activity (0.6% of red blood cells hydrolysed in the presence of 1 nM PA11). PA11 at a concentration lower than 600 nM is not cytotoxic towards human cultured cells. Chemical modification experiments using p-bromophenacyl bromide have provided evidence that the catalytic histidine of PA11 is critical for the anticoagulant activity of this PLA2. PA11 that was subjected to trypsin digestion without previous reduction and alkylation of the disulfide bonds maintained enzymatic and anticoagulant activity, suggesting that proteolysis alone cannot abolish these properties. Consistent with these results, administration of PA11 by gavage in a rabbit stasis thrombosis model increased the clotting time of recalcified citrated whole blood by a factor of four. These data suggest that PA11 has potential to be developed as an anticoagulant in a clinical setting. Copyright © 2015. Published by Elsevier Ltd.

Phospholipase A2 activation as a therapeutic approach for cognitive enhancement in early-stage Alzheimer disease.

Science.gov (United States)

Schaeffer, Evelin L; Forlenza, Orestes V; Gattaz, Wagner F

2009-01-01

Alzheimer disease (AD) is the leading cause of dementia in the elderly and has no known cure. Evidence suggests that reduced activity of specific subtypes of intracellular phospholipases A2 (cPLA2 and iPLA2) is an early event in AD and may contribute to memory impairment and neuropathology in the disease. The objective of this study was to review the literature focusing on the therapeutic role of PLA2 stimulation by cognitive training and positive modulators, or of supplementation with arachidonic acid (PLA2 product) in facilitating memory function and synaptic transmission and plasticity in either research animals or human subjects. MEDLINE database was searched (no date restrictions) for published articles using the keywords Alzheimer disease (mild, moderate, severe), mild cognitive impairment, healthy elderly, rats, mice, phospholipase A(2), phospholipid metabolism, phosphatidylcholine, arachidonic acid, cognitive training, learning, memory, long-term potentiation, protein kinases, dietary lipid compounds, cell proliferation, neurogenesis, and neuritogenesis. Reference lists of the identified articles were checked to select additional studies of interest. Overall, the data suggest that PLA2 activation is induced in the healthy brain during learning and memory. Furthermore, learning seems to regulate endogenous neurogenesis, which has been observed in AD brains. Finally, PLA2 appears to be implicated in homeostatic processes related to neurite outgrowth and differentiation in both neurodevelopmental processes and response to neuronal injury. The use of positive modulators of PLA2 (especially of cPLA2 and iPLA2) or supplementation with dietary lipid compounds (e.g., arachidonic acid) in combination with cognitive training could be a valuable therapeutic strategy for cognitive enhancement in early-stage AD.

Cysteine Biosynthesis Controls Serratia marcescens Phospholipase Activity.

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Anderson, Mark T; Mitchell, Lindsay A; Mobley, Harry L T

2017-08-15

Serratia marcescens causes health care-associated opportunistic infections that can be difficult to treat due to a high incidence of antibiotic resistance. One of the many secreted proteins of S. marcescens is the PhlA phospholipase enzyme. Genes involved in the production and secretion of PhlA were identified by screening a transposon insertion library for phospholipase-deficient mutants on phosphatidylcholine-containing medium. Mutations were identified in four genes ( cyaA , crp , fliJ , and fliP ) that are involved in the flagellum-dependent PhlA secretion pathway. An additional phospholipase-deficient isolate harbored a transposon insertion in the cysE gene encoding a predicted serine O -acetyltransferase required for cysteine biosynthesis. The cysE requirement for extracellular phospholipase activity was confirmed using a fluorogenic phospholipase substrate. Phospholipase activity was restored to the cysE mutant by the addition of exogenous l-cysteine or O -acetylserine to the culture medium and by genetic complementation. Additionally, phlA transcript levels were decreased 6-fold in bacteria lacking cysE and were restored with added cysteine, indicating a role for cysteine-dependent transcriptional regulation of S. marcescens phospholipase activity. S. marcescens cysE mutants also exhibited a defect in swarming motility that was correlated with reduced levels of flhD and fliA flagellar regulator gene transcription. Together, these findings suggest a model in which cysteine is required for the regulation of both extracellular phospholipase activity and surface motility in S. marcescens IMPORTANCE Serratia marcescens is known to secrete multiple extracellular enzymes, but PhlA is unusual in that this protein is thought to be exported by the flagellar transport apparatus. In this study, we demonstrate that both extracellular phospholipase activity and flagellar function are dependent on the cysteine biosynthesis pathway. Furthermore, a disruption of cysteine

Carotid intima media thickness is associated with plasma lipoprotein-associated phospholipase A(2) mass in nondiabetic subjects but not in patients with type 2 diabetes

NARCIS (Netherlands)

Constantinides, Alexander; van Pelt, L. Joost; van Leeuwen, Jeroen J. J.; de Vries, Rindert; Tio, Rene A.; van der Horst, Iwan C. C.; Sluiter, Wim J.; Dullaart, Robin P. F.

Background A recent meta-analysis showed that both plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) mass and activity independently predict cardiovascular events. Notably, Lp-PLA(2) activity but not mass was found to be a determinant of cardiovascular outcome in type 2 diabetes mellitus.

Phospholipase D1 increases Bcl-2 expression during neuronal differentiation of rat neural stem cells.

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Park, Shin-Young; Ma, Weina; Yoon, Sung Nyo; Kang, Min Jeong; Han, Joong-Soo

2015-01-01

We studied the possible role of phospholipase D1 (PLD1) in the neuronal differentiation, including neurite formation of neural stem cells. PLD1 protein and PLD activity increased during neuronal differentiation. Bcl-2 also increased. Downregulation of PLD1 by transfection with PLD1 siRNA or a dominant-negative form of PLD1 (DN-PLD1) inhibited both neurite outgrowth and Bcl-2 expression. PLD activity was dramatically reduced by a PLCγ (phospholipase Cγ) inhibitor (U73122), a Ca(2+)chelator (BAPTA-AM), and a PKCα (protein kinase Cα) inhibitor (RO320432). Furthermore, treatment with arachidonic acid (AA) which is generated by the action of PLA2 (phospholipase A2) on phosphatidic acid (a PLD1 product), increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, indicating that PLA2 is involved in the differentiation process resulting from PLD1 activation. PGE2 (prostaglandin E2), a cyclooxygenase product of AA, also increased during neuronal differentiation. Moreover, treatment with PGE2 increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, and this effect was inhibited by a PKA inhibitor (Rp-cAMP). As expected, inhibition of p38 MAPK resulted in loss of CREB activity, and when CREB activity was blocked with CREB siRNA, Bcl-2 production also decreased. We also showed that the EP4 receptor was required for the PKA/p38MAPK/CREB/Bcl-2 pathway. Taken together, these observations indicate that PLD1 is activated by PLCγ/PKCα signaling and stimulate Bcl-2 expression through PLA2/Cox2/EP4/PKA/p38MAPK/CREB during neuronal differentiation of rat neural stem cells.

Activities of Native and Tyrosine-69 Mutant Phospholipases A2 on Phospholipid Analogues. A Reevaluation of the Minimal Substrate Requirements

NARCIS (Netherlands)

Kuipers, Oscar P.; Dekker, Nicolaas; Verheij, Hubertus M.; Haas, Gerard H. de

1990-01-01

The role of Tyr-69 of porcine pancreatic phospholipase A2 in substrate binding was studied with the help of proteins modified by site-directed mutagenesis and phospholipid analogues with a changed head-group geometry. Two mutants were used containing Phe and Lys, respectively, at position 69.

Lipoprotein-associated phospholipase A(2) mass and activity in children with heterozygous familial hypercholesterolemia and unaffected siblings: Effect of pravastatin

NARCIS (Netherlands)

Ryu, Sung Kee; Hutten, Barbara A.; Vissers, Maud N.; Wiegman, Albert; Kastelein, John J. P.; Tsimikas, Sotirios

2011-01-01

BACKGROUND: Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an independent risk factor of cardiovascular disease and a target of treatment. Lp-PLA(2) levels in children have not been previously reported. The effect of statin therapy on Lp-PLA(2) mass and activity in children with familial

Structure and function of lysosomal phospholipase A2 and lecithin:cholesterol acyltransferase

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Glukhova, Alisa; Hinkovska-Galcheva, Vania; Kelly, Robert; Abe, Akira; Shayman, James A.; Tesmer, John J. G.

2015-03-01

Lysosomal phospholipase A2 (LPLA2) and lecithin:cholesterol acyltransferase (LCAT) belong to a structurally uncharacterized family of key lipid-metabolizing enzymes responsible for lung surfactant catabolism and for reverse cholesterol transport, respectively. Whereas LPLA2 is predicted to underlie the development of drug-induced phospholipidosis, somatic mutations in LCAT cause fish eye disease and familial LCAT deficiency. Here we describe several high-resolution crystal structures of human LPLA2 and a low-resolution structure of LCAT that confirms its close structural relationship to LPLA2. Insertions in the α/β hydrolase core of LPLA2 form domains that are responsible for membrane interaction and binding the acyl chains and head groups of phospholipid substrates. The LCAT structure suggests the molecular basis underlying human disease for most of the known LCAT missense mutations, and paves the way for rational development of new therapeutics to treat LCAT deficiency, atherosclerosis and acute coronary syndrome.

Silencing of the tomato phosphatidylinositol-phospholipase C2 (SlPLC2) reduces plant susceptibility to Botrytis cinerea

NARCIS (Netherlands)

Gonorazky, Gabriela; Guzzo, María Carla; Abd-El-Haliem, Ahmed M.; Joosten, Matthieu H.A.J.; Laxalt, Ana María

2016-01-01

The tomato [Solanum lycopersicum (Sl)] phosphatidylinositol-phospholipase C (PI-PLC) gene family is composed of six members, named SlPLC1 to SlPLC6, differentially regulated on pathogen attack. We have previously shown that the fungal elicitor xylanase induces a raise of SlPLC2 and SlPLC5

Effects of dexamethasone on palate mesenchymal cell phospholipase activity

International Nuclear Information System (INIS)

Bulleit, R.F.; Zimmerman, E.F.

1984-01-01

Corticosteroids will induce cleft palate in mice. One suggested mechanism for this effect is through inhibition of phospholipase activity. This hypothesis was tested by measuring the effects of dexamethasone, a synthetic corticosteroid, on phospholipase activity in cultures of palate mesenchymal cells. Palate mesenchymal cells were prelabeled with [3H]arachidonic acid. The cells were subsequently treated with various concentrations of dexamethasone. Concurrently, cultures of M-MSV-transformed 3T3 cells were prepared identically. After treatment, phospholipase activity was stimulated by the addition of serum or epidermal growth factor (EGF), and radioactivity released into the medium was taken as a measure of phospholipase activity. Dexamethasone (1 X 10(-5) or 1 X 10(-4) M) could inhibit serum-stimulated phospholipase activity in transformed 3T3 cells after 1 to 24 hr of treatment. However, no inhibition of activity was measured in palate mesenchymal cells following this period of treatment. Not until 120 hr of treatment with dexamethasone (1 X 10(-4) M) was any significant inhibition of serum-stimulated phospholipase activity observed in palate mesenchymal cells. When EGF was used to stimulate phospholipase activity, dexamethasone (1 X 10(-5) M) caused an increase in phospholipase activity in palate mesenchymal cells. These observations suggested that phospholipase in transformed 3T3 cells was sensitive to inhibition by dexamethasone. However, palate mesenchymal cell phospholipase is only minimally sensitive to dexamethasone, and in certain instances can be enhanced. These results cannot support the hypothesis that corticosteroids mediate their teratogenic effect via inhibition of phospholipase activity

Two-Phase Acto-Cytosolic Fluid Flow in a Moving Keratocyte: A 2D Continuum Model.

Science.gov (United States)

Nikmaneshi, M R; Firoozabadi, B; Saidi, M S

2015-09-01

The F-actin network and cytosol in the lamellipodia of crawling cells flow in a centripetal pattern and spout-like form, respectively. We have numerically studied this two-phase flow in the realistic geometry of a moving keratocyte. Cytosol has been treated as a low viscosity Newtonian fluid flowing through the high viscosity porous medium of F-actin network. Other involved phenomena including myosin activity, adhesion friction, and interphase interaction are also discussed to provide an overall view of this problem. Adopting a two-phase coupled model by myosin concentration, we have found new accurate perspectives of acto-cytosolic flow and pressure fields, myosin distribution, as well as the distribution of effective forces across the lamellipodia of a keratocyte with stationary shape. The order of magnitude method is also used to determine the contribution of forces in the internal dynamics of lamellipodia.

The RAB2B-GARIL5 Complex Promotes Cytosolic DNA-Induced Innate Immune Responses.

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Takahama, Michihiro; Fukuda, Mitsunori; Ohbayashi, Norihiko; Kozaki, Tatsuya; Misawa, Takuma; Okamoto, Toru; Matsuura, Yoshiharu; Akira, Shizuo; Saitoh, Tatsuya

2017-09-19

Cyclic GMP-AMP synthase (cGAS) is a cytosolic DNA sensor that induces the IFN antiviral response. However, the regulatory mechanisms that mediate cGAS-triggered signaling have not been fully explored. Here, we show the involvement of a small GTPase, RAB2B, and its effector protein, Golgi-associated RAB2B interactor-like 5 (GARIL5), in the cGAS-mediated IFN response. RAB2B-deficiency affects the IFN response induced by cytosolic DNA. Consistent with this, RAB2B deficiency enhances replication of vaccinia virus, a DNA virus. After DNA stimulation, RAB2B colocalizes with stimulator of interferon genes (STING), the downstream signal mediator of cGAS, on the Golgi apparatus. The GTP-binding activity of RAB2B is required for its localization on the Golgi apparatus and for recruitment of GARIL5. GARIL5 deficiency also affects the IFN response induced by cytosolic DNA and enhances replication of vaccinia virus. These findings indicate that the RAB2B-GARIL5 complex promotes IFN responses against DNA viruses by regulating the cGAS-STING signaling axis. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

The RAB2B-GARIL5 Complex Promotes Cytosolic DNA-Induced Innate Immune Responses

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Michihiro Takahama

2017-09-01

Full Text Available Cyclic GMP-AMP synthase (cGAS is a cytosolic DNA sensor that induces the IFN antiviral response. However, the regulatory mechanisms that mediate cGAS-triggered signaling have not been fully explored. Here, we show the involvement of a small GTPase, RAB2B, and its effector protein, Golgi-associated RAB2B interactor-like 5 (GARIL5, in the cGAS-mediated IFN response. RAB2B-deficiency affects the IFN response induced by cytosolic DNA. Consistent with this, RAB2B deficiency enhances replication of vaccinia virus, a DNA virus. After DNA stimulation, RAB2B colocalizes with stimulator of interferon genes (STING, the downstream signal mediator of cGAS, on the Golgi apparatus. The GTP-binding activity of RAB2B is required for its localization on the Golgi apparatus and for recruitment of GARIL5. GARIL5 deficiency also affects the IFN response induced by cytosolic DNA and enhances replication of vaccinia virus. These findings indicate that the RAB2B-GARIL5 complex promotes IFN responses against DNA viruses by regulating the cGAS-STING signaling axis.

Detergent organisation in crystals of monomeric outer membrane phospholipase A

NARCIS (Netherlands)

Snijder, HJ; Timmins, PA; Kalk, KH; Dijkstra, BW

The structure of the detergent in crystals of outer membrane phospholipase A (OMPLA) has been determined using neutron diffraction contrast variation. Large crystals were soaked in stabilising solutions, each containing a different H2O/D2O contrast. From the neutron diffraction at five contrasts,

Relation between various phospholipase actions on human red cell membranes and the interfacial phospholipid pressure in monolayers

NARCIS (Netherlands)

Demel, R.A.; Geurts van Kessel, W.S.M.; Zwaal, R.F.A.; Roelofsen, B.; Deenen, L.L.M. van

1975-01-01

The action of purified phospholipases on monomolecular films of various interfacial pressures is compared with the action on erythrocyte membranes. The phospholipases which cannot hydrolyse phospholipids of the intact erythrocyte membrane, phospholipase C from Bacillus cereus, phospholipase A2 from

Inhibitory effects of Swietenia macrophylla on myotoxic phospholipases A2

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Jaime A. Pereañez

Full Text Available Activity-guided fractionation of an ethanol-soluble extract of the leaves of Swietenia macrophylla King, Meliaceae, led to several fractions. As a result, sample Sm13-16, 23 had the most promising activity against phospholipases A2 (PLA2, Asp49 and Lys49 types. This fraction inhibited PLA2 activity of the Asp49 PLA2, when aggregated substrate was used. On the other hand, this activity was weakly neutralized when monodispersed substrate was used. In addition, Sm13-16, 23 inhibited, in a dose dependent manner, the cytotoxicity, myotoxicity and edema induced by PLA2s, as well as the anticoagulant activity of Asp49 PLA2. Overall, this fraction exhibited a better inhibition of the toxic activities induced by the Lys49 PLA2than those caused by the Asp49 PLA2. The spectral data of Sm13-16, 23 suggested the presence of aromatic compounds (UV λ max (nm 655, 266, and 219; IR λ max KBr (cm-1: ~ 3600-3000 (OH, 2923.07 and 1438.90 (C-H, 1656.69 (C = O, 1618.63 and 1607.67 (C-O, 1285.47772.60. We suggest that phenolic compounds could interact and inhibit the toxins by several mechanisms. Further analysis of the compounds present in the active fraction could be a relevant contribution in the treatment of accidents caused by snake envenomation.

Development of a standardized ELISA for the determination of autoantibodies against human M-type phospholipase A2 receptor in primary membranous nephropathy

NARCIS (Netherlands)

Dahnrich, C.; Komorowski, L.; Probst, C.; Seitz-Polski, B.; Esnault, V.; Wetzels, J.F.M.; Hofstra, J.M.; Hoxha, E.; Stahl, R.A.K.; Lambeau, G.; Stocker, W.; Schlumberger, W.

2013-01-01

BACKGROUND: Autoantibodies against the M-type phospholipase A2 receptor (PLA2R1) are specific markers for primary membranous nephropathy (pMN) and anti-PLA2R1 serum levels may be useful to monitor disease activity. So far, a recombinant cell-based indirect immunofluorescence assay (RC-IFA) using

Membrane Restructuring by Phospholipase A2 Is Regulated by the Presence of Lipid Domains

DEFF Research Database (Denmark)

Leidy, Chad; Ocampo, Jackson; Duelund, Lars

2011-01-01

Secretory phospholipase A2 (sPLA2) catalyzes the hydrolysis of glycerophospholipids. This enzyme is sensitive to membrane structure, and its activity has been shown to increase in the presence of liquid-crystalline/gel (Lα/Lβ) lipid domains. In this work, we explore whether lipid domains can also...... without necessarily destroying the membrane. We confirm by high-performance liquid chromatography the preferential hydrolysis of DMPC within the phase coexistence region of the DMPC/DSPC phase diagram, showing that this preferential hydrolysis is accentuated close to the solidus phase boundary...

Identification and properties of very high affinity brain membrane-binding sites for a neurotoxic phospholipase from the taipan venom

International Nuclear Information System (INIS)

Lambeau, G.; Barhanin, J.; Schweitz, H.; Qar, J.; Lazdunski, M.

1989-01-01

Four new monochain phospholipases were purified from the Oxyuranus scutellatus (taipan) venom. Three of them were highly toxic when injected into mice brain. One of these neurotoxic phospholipases, OS2, was iodinated and used in binding experiments to demonstrate the presence of two families of specific binding sites in rat brain synaptic membranes. The affinities were exceptionally high, Kd1 = 1.5 +/- 0.5 pM and Kd2 = 45 +/- 10 pM, and the maximal binding capacities were Bmax 1 = 1 +/- 0.4 and Bmax 2 = 3 +/- 0.5 pmol/mg of protein. Both binding sites were sensitive to proteolysis and demonstrated to be located on proteins of Mr 85,000-88,000 and 36,000-51,000 by cross-linking and photoaffinity labeling techniques. The binding of 125 I-OS2 to synaptic membranes was dependent on Ca2+ ions and enhanced by Zn2+ ions which inhibit phospholipase activity. Competition experiments have shown that, except for beta-bungarotoxin, a number of known toxic snake or bee phospholipases have very high affinities for the newly identified binding sites. A good correlation (r = 0.80) was observed between toxicity and affinity but not between phospholipase activity and affinity

An alternative method to isolate protease and phospholipase A2 toxins from snake venoms based on partitioning of aqueous two-phase systems

Directory of Open Access Journals (Sweden)

GN Gómez

2012-01-01

Full Text Available Snake venoms are rich sources of active proteins that have been employed in the diagnosis and treatment of health disorders and antivenom therapy. Developing countries demand fast economical downstream processes for the purification of this biomolecule type without requiring sophisticated equipment. We developed an alternative, simple and easy to scale-up method, able to purify simultaneously protease and phospholipase A2 toxins from Bothrops alternatus venom. It comprises a multiple-step partition procedure with polyethylene-glycol/phosphate aqueous two-phase systems followed by a gel filtration chromatographic step. Two single bands in SDS-polyacrylamide gel electrophoresis and increased proteolytic and phospholipase A2 specific activities evidence the homogeneity of the isolated proteins.

Molecular Characterization of Three Novel Phospholipase A2 Proteins from the Venom of Atheris chlorechis, Atheris nitschei and Atheris squamigera

Directory of Open Access Journals (Sweden)

He Wang

2016-06-01

Full Text Available Secretory phospholipase A2 (sPLA2 is known as a major component of snake venoms and displays higher-order catalytic hydrolysis functions as well as a wide range of pathological effects. Atheris is not a notoriously dangerous genus of snakes although there are some reports of fatal cases after envenomation due to the effects of coagulation disturbances and hemorrhaging. Molecular characterization of Atheris venom enzymes is incomplete and there are only a few reports in the literature. Here, we report, for the first time, the cloning and characterization of three novel cDNAs encoding phospholipase A2 precursors (one each from the venoms of the Western bush viper (Atheris chlorechis, the Great Lakes bush viper (Atheris nitschei and the Variable bush viper (Atheris squamigera, using a “shotgun cloning” strategy. Open-reading frames of respective cloned cDNAs contained putative 16 residue signal peptides and mature proteins composed of 121 to 123 amino acid residues. Alignment of mature protein sequences revealed high degrees of structural conservation and identity with Group II venom PLA2 proteins from other taxa within the Viperidae. Reverse-phase High Performance Liquid Chromatography (HPLC profiles of these three snake venoms were obtained separately and chromatographic fractions were assessed for phospholipase activity using an egg yolk suspension assay. The molecular masses of mature proteins were all identified as approximately 14 kDa. Mass spectrometric analyses of the fractionated oligopeptides arising from tryptic digestion of intact venom proteins, was performed for further structural characterization.

Regulation of brain capillary endothelial cells by P2Y receptors coupled to Ca2+, phospholipase C and mitogen-activated protein kinase.

Science.gov (United States)

Albert, J L; Boyle, J P; Roberts, J A; Challiss, R A; Gubby, S E; Boarder, M R

1997-11-01

1. The blood-brain barrier is formed by capillary endothelial cells and is regulated by cell-surface receptors, such as the G protein-coupled P2Y receptors for nucleotides. Here we investigated some of the characteristics of control of brain endothelial cells by these receptors, characterizing the phospholipase C and Ca2+ response and investigating the possible involvement of mitogen-activated protein kinases (MAPK). 2. Using an unpassaged primary culture of rat brain capillary endothelial cells we showed that ATP, UTP and 2-methylthio ATP (2MeSATP) give similar and substantial increases in cytosolic Ca2+, with a rapid rise to peak followed by a slower decline towards basal or to a sustained plateau. Removal of extracellular Ca2+ had little effect on the peak Ca2+-response, but resulted in a more rapid decline to basal. There was no response to alpha,beta-MethylATP (alpha,beta MeATP) in these unpassaged cells, but a response to this P2X agonist was seen after a single passage. 3. ATP (log EC50 -5.1+/-0.2) also caused an increase in the total [3H]-inositol (poly)phosphates ([3H]-InsPx) in the presence of lithium with a rank order of agonist potency of ATP=UTP=UDP>ADP, with 2MeSATP and alpha,beta MeATP giving no detectable response. 4. Stimulating the cells with ATP or UTP gave a rapid rise in the level of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), with a peak at 10 s followed by a decline to a sustained plateau phase. 2MeSATP gave no detectable increase in the level of Ins(1,4,5)P3. 5. None of the nucleotides tested affected basal cyclic AMP, while ATP and ATPgammaS, but not 2MeSATP, stimulated cyclic AMP levels in the presence of 5 microM forskolin. 6. Both UTP and ATP stimulated tyrosine phosphorylation of p42 and p44 mitogen-activated protein kinase (MAPK), while 2MeSATP gave a smaller increase in this index of MAPK activation. By use of a peptide kinase assay, UTP gave a substantial increase in MAPK activity with a concentration-dependency consistent with

A Genetic Screen Reveals that Synthesis of 1,4-Dihydroxy-2-Naphthoate (DHNA), but Not Full-Length Menaquinone, Is Required for Listeria monocytogenes Cytosolic Survival.

Science.gov (United States)

Chen, Grischa Y; McDougal, Courtney E; D'Antonio, Marc A; Portman, Jonathan L; Sauer, John-Demian

2017-03-21

Through unknown mechanisms, the host cytosol restricts bacterial colonization; therefore, only professional cytosolic pathogens are adapted to colonize this host environment. Listeria monocytogenes is a Gram-positive intracellular pathogen that is highly adapted to colonize the cytosol of both phagocytic and nonphagocytic cells. To identify L. monocytogenes determinants of cytosolic survival, we designed and executed a novel screen to isolate L. monocytogenes mutants with cytosolic survival defects. Multiple mutants identified in the screen were defective for synthesis of menaquinone (MK), an essential molecule in the electron transport chain. Analysis of an extensive set of MK biosynthesis and respiratory chain mutants revealed that cellular respiration was not required for cytosolic survival of L. monocytogenes but that, instead, synthesis of 1,4-dihydroxy-2-naphthoate (DHNA), an MK biosynthesis intermediate, was essential. Recent discoveries showed that modulation of the central metabolism of both host and pathogen can influence the outcome of host-pathogen interactions. Our results identify a potentially novel function of the MK biosynthetic intermediate DHNA and specifically highlight how L. monocytogenes metabolic adaptations promote cytosolic survival and evasion of host immunity. IMPORTANCE Cytosolic bacterial pathogens, such as Listeria monocytogenes and Francisella tularensis , are exquisitely evolved to colonize the host cytosol in a variety of cell types. Establishing an intracellular niche shields these pathogens from effectors of humoral immunity, grants access to host nutrients, and is essential for pathogenesis. Through yet-to-be-defined mechanisms, the host cytosol restricts replication of non-cytosol-adapted bacteria, likely through a combination of cell autonomous defenses (CADs) and nutritional immunity. Utilizing a novel genetic screen, we identified determinants of L. monocytogenes cytosolic survival and virulence and identified a role

Cytosolic iron chaperones: Proteins delivering iron cofactors in the cytosol of mammalian cells.

Science.gov (United States)

Philpott, Caroline C; Ryu, Moon-Suhn; Frey, Avery; Patel, Sarju

2017-08-04

Eukaryotic cells contain hundreds of metalloproteins that are supported by intracellular systems coordinating the uptake and distribution of metal cofactors. Iron cofactors include heme, iron-sulfur clusters, and simple iron ions. Poly(rC)-binding proteins are multifunctional adaptors that serve as iron ion chaperones in the cytosolic/nuclear compartment, binding iron at import and delivering it to enzymes, for storage (ferritin) and export (ferroportin). Ferritin iron is mobilized by autophagy through the cargo receptor, nuclear co-activator 4. The monothiol glutaredoxin Glrx3 and BolA2 function as a [2Fe-2S] chaperone complex. These proteins form a core system of cytosolic iron cofactor chaperones in mammalian cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Secreted Phospholipases A2 from Animal Venoms in Pain and Analgesia

Science.gov (United States)

Zambelli, Vanessa O.; Picolo, Gisele; Fernandes, Carlos A. H.

2017-01-01

Animal venoms comprise a complex mixture of components that affect several biological systems. Based on the high selectivity for their molecular targets, these components are also a rich source of potential therapeutic agents. Among the main components of animal venoms are the secreted phospholipases A2 (sPLA2s). These PLA2 belong to distinct PLA2s groups. For example, snake venom sPLA2s from Elapidae and Viperidae families, the most important families when considering envenomation, belong, respectively, to the IA and IIA/IIB groups, whereas bee venom PLA2 belongs to group III of sPLA2s. It is well known that PLA2, due to its hydrolytic activity on phospholipids, takes part in many pathophysiological processes, including inflammation and pain. Therefore, secreted PLA2s obtained from animal venoms have been widely used as tools to (a) modulate inflammation and pain, uncovering molecular targets that are implicated in the control of inflammatory (including painful) and neurodegenerative diseases; (b) shed light on the pathophysiology of inflammation and pain observed in human envenomation by poisonous animals; and, (c) characterize molecular mechanisms involved in inflammatory diseases. The present review summarizes the knowledge on the nociceptive and antinociceptive actions of sPLA2s from animal venoms, particularly snake venoms. PMID:29311537

Alpha 2-adrenergic receptor stimulation of phospholipase A2 and of adenylate cyclase in transfected Chinese hamster ovary cells is mediated by different mechanisms

International Nuclear Information System (INIS)

Jones, S.B.; Halenda, S.P.; Bylund, D.B.

1991-01-01

The effect of alpha 2-adrenergic receptor activation on adenylate cyclase activity in Chinese hamster ovary cells stably transfected with the alpha 2A-adrenergic receptor gene is biphasic. At lower concentrations of epinephrine forskolin-stimulated cyclic AMP production is inhibited, but at higher concentrations the inhibition is reversed. Both of these effects are blocked by the alpha 2 antagonist yohimbine but not by the alpha 1 antagonist prazosin. Pretreatment with pertussis toxin attenuates inhibition at lower concentrations of epinephrine and greatly potentiates forskolin-stimulated cyclic AMP production at higher concentrations of epinephrine. alpha 2-Adrenergic receptor stimulation also causes arachidonic acid mobilization, presumably via phospholipase A2. This effect is blocked by yohimbine, quinacrine, removal of extracellular Ca2+, and pretreatment with pertussis toxin. Quinacrine and removal of extracellular Ca2+, in contrast, have no effect on the enhanced forskolin-stimulated cyclic AMP production. Thus, it appears that the alpha 2-adrenergic receptor in these cells can simultaneously activate distinct signal transduction systems; inhibition of adenylate cyclase and stimulation of phospholipase A2, both via G1, and potentiation of cyclic AMP production by a different (pertussis toxin-insensitive) mechanism

Alpha 2-adrenergic receptor stimulation of phospholipase A2 and of adenylate cyclase in transfected Chinese hamster ovary cells is mediated by different mechanisms

Energy Technology Data Exchange (ETDEWEB)

Jones, S.B.; Halenda, S.P.; Bylund, D.B. (Univ. of Missouri-Columbia (USA))

1991-02-01

The effect of alpha 2-adrenergic receptor activation on adenylate cyclase activity in Chinese hamster ovary cells stably transfected with the alpha 2A-adrenergic receptor gene is biphasic. At lower concentrations of epinephrine forskolin-stimulated cyclic AMP production is inhibited, but at higher concentrations the inhibition is reversed. Both of these effects are blocked by the alpha 2 antagonist yohimbine but not by the alpha 1 antagonist prazosin. Pretreatment with pertussis toxin attenuates inhibition at lower concentrations of epinephrine and greatly potentiates forskolin-stimulated cyclic AMP production at higher concentrations of epinephrine. alpha 2-Adrenergic receptor stimulation also causes arachidonic acid mobilization, presumably via phospholipase A2. This effect is blocked by yohimbine, quinacrine, removal of extracellular Ca2+, and pretreatment with pertussis toxin. Quinacrine and removal of extracellular Ca2+, in contrast, have no effect on the enhanced forskolin-stimulated cyclic AMP production. Thus, it appears that the alpha 2-adrenergic receptor in these cells can simultaneously activate distinct signal transduction systems; inhibition of adenylate cyclase and stimulation of phospholipase A2, both via G1, and potentiation of cyclic AMP production by a different (pertussis toxin-insensitive) mechanism.

Inhibition of phospholipase A2 from human plasma by sodium bisulfite

International Nuclear Information System (INIS)

Wiggins, C.W.; Franson, R.C.

1987-01-01

The anti-oxidant sodium bisulfite has been shown to inhibit acid active(lysosomal), non-Ca ++ -dependent phospholipase A 2 (PLA 2 ), and to interact reversibly with unsaturated fatty acids, altering their chromatographic mobility. The authors examined the effect of bisulfite on neutral active, Ca ++ -dependent PLA 2 from human plasma. Using [1- 14 C]oleate-labelled autoclaved E. coli as substrate, PLA 2 activity was inhibited in a dose-dependent manner by bisulfite. Maximal inhibition occurred at 100μM bisulfite. Preincubation of plasma for 0-30 minutes with bisulfite resulted in a time-dependent increase in PLA 2 inhibition. Preincubation of substrate with bisulfite had no such effect. When the plasma PLA 2 was purified 25-fold by SP-Sephadex chromatography it was no longer inhibited by bisulfite. The SP-Sephadex wash through fraction, which contained greater than 95% of the applied protein but not PLA 2 activity, did not inhibit the purified enzyme. When incubated with bisulfite however, the SP-wash through fraction produced dose-dependent inhibition of the purified enzyme. These results indicate that sodium bisulfite inhibits human plasma PLA 2 , in vitro, indirectly by interaction with a factor(s) present in plasma and suggests that anti-oxidants may similarly influence expression of extracellular PLA 2 in vivo

Profiling of cytosolic and mitochondrial H2O2 production using the H2O2-sensitive protein HyPer in LPS-induced microglia cells.

Science.gov (United States)

Park, Junghyung; Lee, Seunghoon; Lee, Hyun-Shik; Lee, Sang-Rae; Lee, Dong-Seok

2017-07-27

Dysregulation of the production of pro-inflammatory mediators in microglia exacerbates the pathologic process of neurodegenerative disease. ROS actively affect microglia activation by regulating transcription factors that control the expression of pro-inflammatory genes. However, accurate information regarding the function of ROS in different subcellular organelles has not yet been established. Here, we analyzed the pattern of cytosolic and mitochondrial H 2 O 2 formation in LPS-activated BV-2 microglia using the H 2 O 2- sensitive protein HyPer targeted to specific subcellular compartments. Our results show that from an early time, cytosolic H 2 O 2 started increasing constantly, whereas mitochondrial H 2 O 2 rapidly increased later. In addition, we found that MAPK affected cytosolic H 2 O 2 , but not mitochondrial H 2 O 2 . Consequently, our study provides the basic information about subcellular H 2 O 2 generation in activated microglia, and a useful tool for investigating molecular targets that can modulate neuroinflammatory responses. Copyright © 2017 Elsevier B.V. All rights reserved.

Exosomes account for vesicle-mediated transcellular transport of activatable phospholipases and prostaglandins[S

Science.gov (United States)

Subra, Caroline; Grand, David; Laulagnier, Karine; Stella, Alexandre; Lambeau, Gérard; Paillasse, Michael; De Medina, Philippe; Monsarrat, Bernard; Perret, Bertrand; Silvente-Poirot, Sandrine; Poirot, Marc; Record, Michel

2010-01-01

Exosomes are bioactive vesicles released from multivesicular bodies (MVB) by intact cells and participate in intercellular signaling. We investigated the presence of lipid-related proteins and bioactive lipids in RBL-2H3 exosomes. Besides a phospholipid scramblase and a fatty acid binding protein, the exosomes contained the whole set of phospholipases (A2, C, and D) together with interacting proteins such as aldolase A and Hsp 70. They also contained the phospholipase D (PLD) / phosphatidate phosphatase 1 (PAP1) pathway leading to the formation of diglycerides. RBL-2H3 exosomes also carried members of the three phospholipase A2 classes: the calcium-dependent cPLA2-IVA, the calcium-independent iPLA2-VIA, and the secreted sPLA2-IIA and V. Remarkably, almost all members of the Ras GTPase superfamily were present, and incubation of exosomes with GTPγS triggered activation of phospholipase A2 (PLA2)and PLD2. A large panel of free fatty acids, including arachidonic acid (AA) and derivatives such as prostaglandin E2 (PGE2) and 15-deoxy-Δ12,14-prostaglandinJ2 (15-d PGJ2), were detected. We observed that the exosomes were internalized by resting and activated RBL cells and that they accumulated in an endosomal compartment. Endosomal concentrations were in the micromolar range for prostaglandins; i.e., concentrations able to trigger prostaglandin-dependent biological responses. Therefore exosomes are carriers of GTP-activatable phospholipases and lipid mediators from cell to cell. PMID:20424270

Evolution of a Rippled Membrane during Phospholipase A2 Hydrolysis Studied by Time-Resolved AFM

DEFF Research Database (Denmark)

Leidy, Chad; Mouritsen, Ole G.; Jørgensen, Kent

2004-01-01

The sensitivity of phospholipase A2 (PLA2) for lipid membrane curvature is explored by monitoring, through time-resolved atomic force microscopy, the hydrolysis of supported double bilayers in the ripple phase. The ripple phase presents a corrugated morphology. PLA2 is shown to have higher activity...... toward the ripple phase compared to the gel phase in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes, indicating its preference for this highly curved membrane morphology. Hydrolysis of the stable and metastable ripple structures is monitored for equimolar DMPC/1,2-distearoyl- sn-glycero-3....... This is reflected in an increase in ripple spacing, followed by a sudden flattening of the lipid membrane during hydrolysis. Hydrolysis of the ripple phase results in anisotropic holes running parallel to the ripples, suggesting that the ripple phase has strip regions of higher sensitivity to enzymatic attack. Bulk...

Identification and properties of very high affinity brain membrane-binding sites for a neurotoxic phospholipase from the taipan venom

Energy Technology Data Exchange (ETDEWEB)

Lambeau, G.; Barhanin, J.; Schweitz, H.; Qar, J.; Lazdunski, M. (Centre de Biochimie, Nice (France))

1989-07-05

Four new monochain phospholipases were purified from the Oxyuranus scutellatus (taipan) venom. Three of them were highly toxic when injected into mice brain. One of these neurotoxic phospholipases, OS2, was iodinated and used in binding experiments to demonstrate the presence of two families of specific binding sites in rat brain synaptic membranes. The affinities were exceptionally high, Kd1 = 1.5 +/- 0.5 pM and Kd2 = 45 +/- 10 pM, and the maximal binding capacities were Bmax 1 = 1 +/- 0.4 and Bmax 2 = 3 +/- 0.5 pmol/mg of protein. Both binding sites were sensitive to proteolysis and demonstrated to be located on proteins of Mr 85,000-88,000 and 36,000-51,000 by cross-linking and photoaffinity labeling techniques. The binding of {sup 125}I-OS2 to synaptic membranes was dependent on Ca2+ ions and enhanced by Zn2+ ions which inhibit phospholipase activity. Competition experiments have shown that, except for beta-bungarotoxin, a number of known toxic snake or bee phospholipases have very high affinities for the newly identified binding sites. A good correlation (r = 0.80) was observed between toxicity and affinity but not between phospholipase activity and affinity.

Antiparasitic effects induced by polyclonal IgY antibodies anti-phospholipase A2 from Bothrops pauloensis venom.

Science.gov (United States)

Borges, Isabela Pacheco; Silva, Mariana Ferreira; Santiago, Fernanda Maria; de Faria, Lucas Silva; Júnior, Álvaro Ferreira; da Silva, Rafaela José; Costa, Mônica Soares; de Freitas, Vitor; Yoneyama, Kelly Aparecida Geraldo; Ferro, Eloísa Amália Vieira; Lopes, Daiana Silva; Rodrigues, Renata Santos; de Melo Rodrigues, Veridiana

2018-06-01

Activities of phospholipases (PLAs) have been linked to pathogenesis in various microorganisms, and implicated in cell invasion and so the interest in these enzymes as potential targets that could contribute to the control of parasite survival and proliferation. Chicken eggs immunized with BnSP-7, a Lys49 phospholipase A 2 (PLA 2 ) homologue from Bothrops pauloensis snake venom, represent an excellent source of polyclonal antibodies with potential inhibitory activity on parasite PLA s. Herein, we report the production, characterization and anti-parasitic effect of IgY antibodies from egg yolks of hens immunized with BnSP-7. Produced antibodies presented increasing avidity and affinity for antigenic toxin epitopes throughout immunization, attaining a plateau after 4weeks. Pooled egg yolks-purified anti-BnSP-7 IgY antibodies were able to specifically recognize different PLA 2 s from Bothrops pauloensis and Bothrops jararacussu venom. Antibodies also neutralized BnSP-7 cytotoxic activity in C2C12 cells. Also, the antibodies recognized targets in Leishmania (Leishmania) amazonensis and Toxoplasma gondii extracts by ELISA and immunofluorescence assays. Anti-BnSP-7 IgY antibodies were cytotoxic to T. gondii tachyzoite and L. (L.) amazonensis promastigotes, and were able to decrease proliferation of both parasites treated before infection. These data suggest that the anti-BnSP-7 IgY is an important tool for discovering new parasite targets and blocking parasitic effects. Copyright © 2018 Elsevier B.V. All rights reserved.

Endogenous secreted phospholipase A2 group X regulates cysteinyl leukotrienes synthesis by human eosinophils.

Science.gov (United States)

Hallstrand, Teal S; Lai, Ying; Hooper, Kathryn A; Oslund, Rob C; Altemeier, William A; Matute-Bello, Gustavo; Gelb, Michael H

2016-01-01

Phospholipase A2s mediate the rate-limiting step in the formation of eicosanoids such as cysteinyl leukotrienes (CysLTs). Group IVA cytosolic PLA2α (cPLA2α) is thought to be the dominant PLA2 in eosinophils; however, eosinophils also have secreted PLA2 (sPLA2) activity that has not been fully defined. To examine the expression of sPLA2 group X (sPLA2-X) in eosinophils, the participation of sPLA2-X in the formation of CysLTs, and the mechanism by which sPLA2-X initiates the synthesis of CysLTs in eosinophils. Peripheral blood eosinophils were obtained from volunteers with asthma and/or allergy. A rabbit polyclonal anti-sPLA2-X antibody identified sPLA2-X by Western blot. We used confocal microscopy to colocalize the sPLA2-X to intracellular structures. An inhibitor of sPLA2-X (ROC-0929) that does not inhibit other mammalian sPLA2s, as well as inhibitors of the mitogen-activated kinase cascade (MAPK) and cPLA2α, was used to examine the mechanism of N-formyl-methionyl-leucyl-phenylalanine (fMLP)-mediated formation of CysLT. Eosinophils express the mammalian sPLA2-X gene (PLA2G10). The sPLA2-X protein is located in the endoplasmic reticulum, golgi, and granules of eosinophils and moves to the granules and lipid bodies during fMLP-mediated activation. Selective sPLA2-X inhibition attenuated the fMLP-mediated release of arachidonic acid and CysLT formation by eosinophils. Inhibitors of p38, extracellular-signal-regulated kinases 1/2 (p44/42 MAPK), c-Jun N-terminal kinase, and cPLA2α also attenuated the fMLP-mediated formation of CysLT. The sPLA2-X inhibitor reduced the phosphorylation of p38 and extracellular-signal-regulated kinases 1/2 (p44/42 MAPK) as well as cPLA2α during cellular activation, indicating that sPLA2-X is involved in activating the MAPK cascade leading to the formation of CysLT via cPLA2α. We further demonstrate that sPLA2-X is activated before secretion from the cell during activation. Short-term priming with IL-13 and TNF/IL-1β increased the

Evidence for the presence of phospholipase A1 in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Watanabe, Yasuo; Murakami, Masako; Takakuwa, Masayoshi

1983-01-01

The cause of the autolysis of pressed Baker's yeast was examined. Softened pressed yeast cells (Saccharomyces cerevisiae), after about 10 days of storage at 30 deg C, was subjected to a series of extraction: the extraction with acetone was made to the supernatant after the centrifugation of the water-suspended yeast cell at 1000 x g for 10 min, and the obtained precipitation was mechanically (with a Potter teflon homogenizer) homogenized. After removing the residues by centrifugation, the protein was salted out with ammonium sulfate up to 0.6 saturation. An enzyme, phospholipase A 1 was thus obtained from the softened yeast cells. The activity of the enzyme thus obtained was assayed using L-α-phosphatidylethanolamine as the substrate. It was previously found that 14 C-labelled free fatty acids liberated from phosphatidylcholine (PC) accumulated in the softened yeast packed cake. The enzyme was identified as phospholipase A 1 having the optimal pH at around 8. Another evidence, obtained previously, together with the present finding suggest that the softening of the pressed Baker's yeast may be caused by the degradation of phospholipid by the combined action of phospholipase A 1 and lysophospholipase L 2 . (Yamashita, S.)

Identification of intracellular phospholipases A2 in the human eye: involvement in phagocytosis of photoreceptor outer segments

DEFF Research Database (Denmark)

Kolko, Miriam; Wang, Jinmei; Zhan, Chen

2007-01-01

PURPOSE: To identify intracellular phospholipases A(2) (PLA(2)) in the human retina and to explore the role of these enzymes in human retinal pigment epithelium (RPE) phagocytosis of photoreceptor outer segments (POS). METHODS: PCR amplification and Western blot analysis were used to identify m......)-VIA activity was found to be specifically increased 12 hours after ARPE-19 cells were fed with POS. Finally, RPE phagocytosis was inhibited by the iPLA(2)-VIA inhibitor bromoenol lactone. CONCLUSIONS: Various intracellular PLA(2) subtypes are present in the human retina. iPLA(2)-VIA may play...

Point of care testing of phospholipase A2 group IIA for serological diagnosis of rheumatoid arthritis

Science.gov (United States)

Liu, Nathan J.; Chapman, Robert; Lin, Yiyang; Mmesi, Jonas; Bentham, Andrew; Tyreman, Matthew; Abraham, Sonya; Stevens, Molly M.

2016-02-01

Secretory phospholipase A2 group IIA (sPLA2-IIA) was examined as a point of care marker for determining disease activity in rheumatoid (RA) and psoriatic (PsA) arthritis. Serum concentration and activity of sPLA2-IIA were measured using in-house antibodies and a novel point of care lateral flow device assay in patients diagnosed with varying severities of RA (n = 30) and PsA (n = 25) and found to correlate strongly with C-reactive protein (CRP). Levels of all markers were elevated in patients with active RA over those with inactive RA as well as both active and inactive PsA, indicating that sPLA2-IIA can be used as an analogue to CRP for RA diagnosis at point of care.Secretory phospholipase A2 group IIA (sPLA2-IIA) was examined as a point of care marker for determining disease activity in rheumatoid (RA) and psoriatic (PsA) arthritis. Serum concentration and activity of sPLA2-IIA were measured using in-house antibodies and a novel point of care lateral flow device assay in patients diagnosed with varying severities of RA (n = 30) and PsA (n = 25) and found to correlate strongly with C-reactive protein (CRP). Levels of all markers were elevated in patients with active RA over those with inactive RA as well as both active and inactive PsA, indicating that sPLA2-IIA can be used as an analogue to CRP for RA diagnosis at point of care. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08423g

Secretory phospholipase A₂ responsive liposomes exhibit a potent anti-neoplastic effect in vitro, but induce unforeseen severe toxicity in vivo

DEFF Research Database (Denmark)

Østrem, Ragnhild Garborg; Parhamifar, Ladan; Pourhassan, Houman

2017-01-01

The clinical use of liposomal drug delivery vehicles is often hindered by insufficient drug release. Here we present the rational design of liposomes optimized for secretory phospholipase A2 (sPLA2) triggered drug release, and test their utility in vitro and in vivo. We hypothesized...

Cytosolic adenylate changes during exercise in prawn muscle

International Nuclear Information System (INIS)

Thebault, M.T.; Raffin, J.P.; Pichon, R.

1994-01-01

31 P NMR and biochemical analysis were used to assess the effect of heavy exercise on cytosolic adenylate levels in Palaemon serratus abdominal muscle. At rest, the MgATP level corresponded to 85.5% of the total ATP content. The cytosolic adenylate concentrations of the prawn muscle are considerably different from that of vertebrates. The percentage of ADP bound to myofilaments was lower in the prawn muscle. Consequently, the level of free cytosolic AMP was greatly higher (thirty fold higher) than in vertebrate muscle. During vigorous work, the concentration of MgATP dropped and the cytosolic AMP accumulated, while the cytosolic adenine nucleotide pool decreased significantly. The phosphorylation potential value and the ATP/ADP ratio, calculated from the cytosolic adenylate, dropped acutely during the whole period of muscular contractions. On the contrary, the adenylate energy charge calculated from the cytosolic adenylate decreased slightly. Therefore, even in muscle displaying no AMP deamination, the adenylate charge is stabilized during exercise by the dynamic changes between cytosolic and bound adenylate species. (author). 21 refs., 2 tabs

Immunohistochemical localization of hepatopancreatic phospholipase A2 in Hexaplex Trunculus digestive cells

Science.gov (United States)

2011-01-01

Background Mammalian sPLA2-IB localization cell are well characterized. In contrast, much less is known about aquatic primitive ones. The aquatic world contains a wide variety of living species and, hence represents a great potential for discovering new lipolytic enzymes and the mode of digestion of lipid food. Results The marine snail digestive phospholipase A2 (mSDPLA2) has been previously purified from snail hepatopancreas. The specific polyclonal antibodies were prepared and used for immunohistochimical and immunofluorescence analysis in order to determine the cellular location of mSDPLA2. Our results showed essentially that mSDPLA2 was detected inside in specific vesicles tentatively named (mSDPLA2+) granules of the digestive cells. No immunolabelling was observed in secretory zymogene-like cells. This immunocytolocalization indicates that lipid digestion in the snail might occur in specific granules inside the digestive cells. Conclusion The cellular location of mSDPLA2 suggests that intracellular phospholipids digestion, like other food components digestion of snail diet, occurs in these digestive cells. The hepatopancreas of H. trunculus has been pointed out as the main region for digestion, absorption and storage of lipids. PMID:21631952

Liver cytosolic 1 antigen-antibody system in type 2 autoimmune hepatitis and hepatitis C virus infection.

Science.gov (United States)

Lenzi, M; Manotti, P; Muratori, L; Cataleta, M; Ballardini, G; Cassani, F; Bianchi, F B

1995-01-01

Within the multiform liver/kidney microsomal (LKM) family, a subgroup of sera that reacts with a liver cytosolic (LC) protein has been isolated and the new antigen-antibody system is called LC1. Unlike LKM antibody type 1 (anti-LKM1), anti-LC1 is said to be unrelated to hepatitis C virus (HCV) infection and has therefore been proposed as a marker of 'true' autoimmune hepatitis type 2. Altogether 100 LKM1 positive sera were tested by immunodiffusion (ID). Twenty five gave a precipitation line with human liver cytosol; 17 of the 25 also reacted with rat liver cytosol. Thirteen of the 25 sera were anti-HCV positive by second generation ELISA: anti-HCV positive patients were significantly older (p LKM1, and that it is an additional marker of juvenile autoimmune hepatitis type 2. It does not, however, discriminate between patients with and without HCV infection. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:7797126

Virtual analysis of structurally diverse synthetic analogs as inhibitors of snake venom secretory phospholipase A2.

Science.gov (United States)

Sivaramakrishnan, V; Ilamathi, M; Ghosh, K S; Sathish, S; Gowda, T V; Vishwanath, B S; Rangappa, K S; Dhananjaya, B L

2016-01-01

Due to the toxic pathophysiological role of snake venom phospholipase A2 (PLA2 ), its compelling limitations to anti-venom therapy in humans and the need for alternative therapy foster considerable pharmacological interest towards search of PLA2 specific inhibitors. In this study, an integrated approach involving homology modeling, molecular dynamics and molecular docking studies on VRV-PL-V (Vipera russellii venom phospholipase A2 fraction-V) belonging to Group II-B secretory PLA2 from Daboia russelli pulchella is carried out in order to study the structure-based inhibitor design. The accuracy of the model was validated using multiple computational approaches. The molecular docking study of this protein was undertaken using different classes of experimentally proven, structurally diverse synthetic inhibitors of secretory PLA2 whose selection is based on IC50 value that ranges from 25 μM to 100 μM. Estimation of protein-ligand contacts by docking analysis sheds light on the importance of His 47 and Asp 48 within the VRV-PL-V binding pocket as key residue for hydrogen bond interaction with ligands. Our virtual analysis revealed that compounds with different scaffold binds to the same active site region. ADME analysis was also further performed to filter and identify the best potential specific inhibitor against VRV-PL-V. Additionally, the e-pharmacophore was generated for the best potential specific inhibitor against VRV-PL-V and reported here. The present study should therefore play a guiding role in the experimental design of VRV-PL-V inhibitors that may provide better therapeutic molecular models for PLA2 recognition and anti-ophidian activity. Copyright © 2015 John Wiley & Sons, Ltd.

Substituted thiobenzoic acid S-benzyl esters as potential inhibitors of a snake venom phospholipase A2: Synthesis, spectroscopic and computational studies

Science.gov (United States)

Henao Castañeda, I. C.; Pereañez, J. A.; Jios, J. L.

2012-11-01

4-Chlorothiobenzoic acid S-benzyl ester (I), 3-nitrothiobenzoic acid S-benzyl ester (II), 4-nitrothiobenzoic acid S-benzyl ester (III) and 4-methylthiobenzoic acid S-benzyl ester (IV) were prepared and characterized by 1H and 13C NMR, Mass spectrometry and IR spectroscopy. Quantum chemical calculations were performed with Gaussian 09 to calculate the geometric parameters and vibrational spectra. Phospholipase A2 (PLA2) was purified from Crotalus durissus cumanensis venom by molecular exclusion chromatography, followed by reverse phase-high performance liquid chromatography. Two studies of the inhibition of phospholipase A2 activity were performed using phosphatidilcholine and 4-nitro-3-octanoyloxybenzoic acid as substrates, in both cases compound II showed the best inhibitory ability, with 74.89% and 69.91% of inhibition, respectively. Average percentage of inhibition was 52.49%. Molecular docking was carried out with Autodock Vina using as ligands the minimized structures of compounds (I-IV) and as protein PLA2 (PDB code 2QOG). The results suggest that compounds I-IV could interact with His48 at the active site of PLA2. In addition, all compounds showed Van der Waals interactions with residues from hydrophobic channel of the enzyme. This interaction would impede normal catalysis cycle of the PLA2.

Secretory phospholipase A2 potentiates glutamate-induced rat striatal neuronal cell death in vivo

DEFF Research Database (Denmark)

Kolko, M; Bruhn, T; Christensen, Thomas

1999-01-01

The secretory phospholipases A2 (sPLA2) OS2 (10, 20 and 50 pmol) or OS1, (50 pmol) purified from taipan snake Oxyuranus scutellatus scutellatus venom, and the excitatory amino acid glutamate (Glu) (2.5 and 5.0 micromol) were injected into the right striatum of male Wistar rats. Injection of 10...... no tissue damage or neurological abnormality. After injection of 5.0 micromol Glu, the animals initially circled towards the side of injection, and gradually developed generalized clonic convulsions. These animals showed a well demarcated striatal infarct. When non-toxic concentrations of 20 pmol OS2 and 2.......5 micromol Glu were co-injected, a synergistic neurotoxicity was observed. Extensive histological damage occurred in the entire right hemisphere, and in several rats comprising part of the contralateral hemisphere. These animals were apathetic in the immediate hours following injection, with circling towards...

Plasma phospholipase, γ-CEHC and antioxidant capacity in fibromyalgia.

Science.gov (United States)

Fais, Antonella; Cacace, Enrico; Atzori, Luigi; Era, Benedetta; Ruggiero, Valeria

2017-05-01

Recent studies have suggested a possible role of high levels of plasma lysophosphocholines (lysoPCs) in fibromyalgia syndrome (FMS). The aim of this study was to evaluate the content of plasma phospholipases (e.g., Platelet Activating Factor Acetyl Hydrolase [PAF-AH], secretory Phospholipase A 2 [sPLA 2 ], Total Antioxidant Capacity [TAOC] and 2,7,8-trimethyl-2-(2-carboxyethyl)-6-hydroxy chroman [γ-CEHC]) in FMS patients and their association with clinical status and quality of life. Thirty-six females meeting the 2011 American College of Rheumatology criteria for the classification of FMS and thirty-four healthy females were enrolled for the study. Plasma enzyme levels were quantified using commercial enzyme-linked-immunosorbent-assay (ELISA). In order to assess the disease severity and the functional status of patients, the Fibromyalgia Impact Questionnarie (FIQ) was used. Higher levels of sPLA 2 and lower PAF-AH and γ-CEHC were observed in the plasma of FMS patients compared to the controls. A decrease in PAF-AH and TAOC levels were found in severe FMS (S-FMS) compared to mild/slight (MS-FMS) forms. The results of the study indicate a possible involvement of phospholipases and γ-CEHC in fibromyalgia syndrome. © 2015 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

A Plant Phytosulfokine Peptide Initiates Auxin-Dependent Immunity through Cytosolic Ca2+ Signaling in Tomato.

Science.gov (United States)

Zhang, Huan; Hu, Zhangjian; Lei, Cui; Zheng, Chenfei; Wang, Jiao; Shao, Shujun; Li, Xin; Xia, Xiaojian; Cai, Xinzhong; Zhou, Jie; Zhou, Yanhong; Yu, Jingquan; Foyer, Christine H; Shi, Kai

2018-03-01

Phytosulfokine (PSK) is a disulfated pentapeptide that is an important signaling molecule. Although it has recently been implicated in plant defenses to pathogen infection, the mechanisms involved remain poorly understood. Using surface plasmon resonance and gene silencing approaches, we showed that the tomato ( Solanum lycopersicum ) PSK receptor PSKR1, rather than PSKR2, functioned as the major PSK receptor in immune responses. Silencing of PSK signaling genes rendered tomato more susceptible to infection by the economically important necrotrophic pathogen Botrytis cinerea Analysis of tomato mutants defective in either defense hormone biosynthesis or signaling demonstrated that PSK-induced immunity required auxin biosynthesis and associated defense pathways. Here, using aequorin-expressing tomato plants, we provide evidence that PSK perception by tomato PSKR1 elevated cytosolic [Ca 2+ ], leading to auxin-dependent immune responses via enhanced binding activity between calmodulins and the auxin biosynthetic YUCs. Thus, our data demonstrate that PSK acts as a damage-associated molecular pattern and is perceived mainly by PSKR1, which increases cytosolic [Ca 2+ ] and activates auxin-mediated pathways that enhance immunity of tomato plants to B. cinerea . © 2018 American Society of Plant Biologists. All rights reserved.

A new inhibitor of synovial phospholipase A2 from fermentations of Penicillium sp. 62-92.

Science.gov (United States)

Witter, L; Anke, T; Sterner, O

1998-01-01

Penidiamide, a new tripetide containing dehydrotryptamine, glycine and anthranilic acid linked together by two amide bonds, and oxindole were isolated from submerged cultures of Penicillium sp. 62-92. Both compounds preferentially inhibited human synovial phospholipase A2, penidiamide with an IC50 of 30 microM and oxindole of 380 microM. With the exception of U 937 cells (leukemia, human), no cytotoxic activities were detected against HL-60- (leukemia, human), HeLa S3- (epitheloid carcinoma, human), BHK 21- (kidney fibroblasts, hamster), and L1210-cells (leukemia, mouse). No antimicrobial activity was detected for oxindole, and only weak antibacterial activity for penidiamide. The structure of penidiamide was elucidated by spectroscopic methods.

Clofazimine Induced Suicidal Death of Human Erythrocytes

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Arbace Officioso

2015-08-01

Full Text Available Background/Aims: The antimycobacterial riminophenazine clofazimine has previously been shown to up-regulate cellular phospholipase A2 and to induce apoptosis. In erythrocytes phospholipase A2 stimulates eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Phospholipase A2 is in part effective by fostering formation of prostaglandin E2, which triggers Ca2+ entry. Stimulators of Ca2+ entry and eryptosis further include oxidative stress and energy depletion. The present study tested, whether and how clofazimine induces eryptosis. Methods: Phosphatidylserine exposure at the cell surface was estimated from annexin V binding, cell volume from forward scatter, hemolysis from hemoglobin release, cytosolic Ca2+ activity ([Ca2+]i from Fluo3-fluorescence, reactive oxygen species (ROS from 2′, 7′-dichlorodihydrofluorescein diacetate (DCFDA fluorescence, and cytosolic ATP level utilizing a luciferin-luciferase assay kit. Results: A 24-48 hours exposure of human erythrocytes to clofazimine (≥1.5 µg/ml significantly increased the percentage of annexin-V-binding cells without appreciably modifying forward scatter. Clofazimine significantly increased [Ca2+]i, significantly decreased cytosolic ATP, but did not significantly modify ROS. The effect of clofazimine on annexin-V-binding was significantly blunted, but not fully abolished by removal of extracellular Ca2+, and by phospholipase A2 inhibitor quinacrine (25 µM. Clofazimine further augmented the effect of Ca2+ ionophore ionomycin (0.1 µM on eryptosis. The clofazimine induced annexin-V-binding was, however, completely abrogated by combined Ca2+ removal and addition of quinacrine. Conclusion: Clofazimine stimulates phospholipid scrambling of the erythrocyte cell membrane, an effect in part dependent on entry of extracellular Ca2+, paralleled by cellular energy depletion and sensitive to

Plasma Cholesteryl Ester Transfer, But Not Cholesterol Esterification, Is Related to Lipoprotein-Associated Phospholipase A(2) : Possible Contribution to an Atherogenic Lipoprotein Profile

NARCIS (Netherlands)

Dullaart, Robin P. F.; Constantinides, Alexander; Perton, Frank G.; van Leeuwen, Jeroen J. J.; van Pelt, Joost L.; de Vries, Rindert; van Tol, Arie

Context: Plasma lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) predicts incident cardiovascular disease and is associated preferentially with negatively charged apolipoprotein B-containing lipoproteins. The plasma cholesteryl ester transfer (CET) process, which contributes to low high-density

Phospholipase D function in Saccharomyces cerevisiae.

Science.gov (United States)

Mendonsa, Rima; Engebrecht, JoAnne

2009-09-01

Phosphatidylinositol 4,5-bisphosphate-regulated phosphatidylcholine-specific phospholipase D is conserved from yeast to man. The essential role of this enzyme in yeast is to mediate the fusion of Golgi and endosome-derived vesicles to generate the prospore membrane during the developmental program of sporulation, through the production of the fusogenic lipid phosphatidic acid. In addition to recruiting proteins required for fusion, phosphatidic acid is believed to lower the energy barrier to stimulate membrane curvature. During mitotic growth, phospholipase D activity is dispensable unless the major phosphatidylinositol/phosphatidylcholine transfer protein is absent; it also appears to play a nonessential role in the mating signal transduction pathway. The regulation of phospholipase D activity during both sporulation and mitotic growth is still not fully understood and awaits further characterization.

Carvacrol attenuates serum levels of total protein, phospholipase A2 and histamine in asthmatic guinea pig

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Mohammad Hossein Boskabady

2016-11-01

Full Text Available Objective: Pharmacological effects of carvacrol such as its anti-inflammatory activities have been shows. In this study the effects of carvacrol on serum levels of total protein (TP, phospholipase A2 (PLA2 and histamine in sensitized guinea pigs was evaluated. Materials and Methods: Sensitized guinea pigs were given drinking water alone (group S, drinking water containing three concentrations of carvacrol (40, 80 and 160 µg/ml or dexamethasone. Serum levels of TP, PLA2 and histamine were examined I all sensitized groups as well as a non-sensitized control group (n=6 for each group. Results: In sensitized animals, serum levels of TP, PLA2 and histamine were significantly increased compared to control animals (p

Retargeting the Clostridium botulinum C2 toxin to the neuronal cytosol.

Science.gov (United States)

Pavlik, Benjamin J; Hruska, Elizabeth J; Van Cott, Kevin E; Blum, Paul H

2016-03-30

Many biological toxins are known to attack specific cell types, delivering their enzymatic payloads to the cytosol. This process can be manipulated by molecular engineering of chimeric toxins. Using toxins with naturally unlinked components as a starting point is advantageous because it allows for the development of payloads separately from the binding/translocation components. Here the Clostridium botulinum C2 binding/translocation domain was retargeted to neural cell populations by deleting its non-specific binding domain and replacing it with a C. botulinum neurotoxin binding domain. This fusion protein was used to deliver fluorescently labeled payloads to Neuro-2a cells. Intracellular delivery was quantified by flow cytometry and found to be dependent on artificial enrichment of cells with the polysialoganglioside receptor GT1b. Visualization by confocal microscopy showed a dissociation of payloads from the early endosome indicating translocation of the chimeric toxin. The natural Clostridium botulinum C2 toxin was then delivered to human glioblastoma A172 and synchronized HeLa cells. In the presence of the fusion protein, native cytosolic enzymatic activity of the enzyme was observed and found to be GT1b-dependent. This retargeted toxin may enable delivery of therapeutics to peripheral neurons and be of use in addressing experimental questions about neural physiology.

Crystallization and preliminary X-ray diffraction studies of BmooPLA2-I, a platelet-aggregation inhibitor and hypotensive phospholipase A2 from Bothrops moojeni venom

International Nuclear Information System (INIS)

Salvador, Guilherme H. M.; Marchi-Salvador, Daniela P.; Silveira, Lucas B.; Soares, Andreimar M.; Fontes, Marcos R. M.

2011-01-01

BmooPLA 2 -I, an acidic, catalytic and nontoxic phospholipase A 2 from B. moojeni venom that is able to inhibit platelet aggregation and induce a hypotensive effect, has been crystallized. An X-ray diffraction data set was collected to 1.6 Å resolution and a molecular-replacement solution was obtained. Phospholipases A 2 (PLA 2 s) are enzymes that cause the liberation of fatty acids and lysophospholipids by the hydrolysis of membrane phospholipids. In addition to their catalytic action, a wide variety of pharmacological activities have been described for snake-venom PLA 2 s. BmooPLA 2 -I is an acidic, nontoxic and catalytic PLA 2 isolated from Bothrops moojeni snake venom which exhibits an inhibitory effect on platelet aggregation, an immediate decrease in blood pressure, inducing oedema at a low concentration, and an effective bactericidal effect. BmooPLA 2 -I has been crystallized and X-ray diffraction data have been collected to 1.6 Å resolution using a synchrotron-radiation source. The crystals belonged to space group C222 1 , with unit-cell parameters a = 39.7, b = 53.2, c = 89.2 Å. The molecular-replacement solution of BmooPLA 2 -I indicated a monomeric conformation, which is in agreement with nondenaturing electrophoresis and dynamic light-scattering experiments. A comparative study of this enzyme with the acidic PLA 2 from B. jararacussu (BthA-I) and other toxic and nontoxic PLA 2 s may provide important insights into the functional aspects of this class of proteins

Single molecular image of cytosolic free Ca2+ of skeletal muscle cells in rats pre- and post-exercise-induced fatigue

Science.gov (United States)

Liu, Yi; Zhang, Heming; Zhao, Yanping; Liu, Zhiming

2009-08-01

A growing body of literature indicated the cytosolic free Ca2+ concentration of skeletal muscle cells changes significantly during exercise-induced fatigue. But it is confusing whether cytosolic free Ca2+ concentration increase or decrease. Furthermore, current researches mainly adopt muscle tissue homogenate as experiment material, but the studies based on cellular and subcellular level is seldom. This study is aimed to establish rat skeletal muscle cell model of exercise-induced fatigue, and confirm the change of cytosolic free Ca2+ concentration of skeletal muscle cells in rats preand post- exercise-induced fatigue. In this research, six male Wistar rats were randomly divided into two groups: control group (n=3) and exercise-induced fatigue group (n=3). The former group were allowed to freely move and the latter were forced to loaded swimming to exhaustive. Three days later, all the rats were sacrificed, the muscle tissue from the same site of skeletal muscle were taken out and digested to cells. After primary culture of the two kinds of skeletal muscle cells from tissue, a fluorescent dye-Fluo-3 AM was used to label the cytosolic free Ca2+. The fluorescent of Ca2+ was recorded by confocal laser scanning microscopy. The results indicated that, the Ca2+ fluorescence intensity of cells from the rat of exercise-induced fatigue group was significantly higher than those in control group. In conclusion, cytosolic free Ca2+ concentration of skeletal muscle cells has a close relation with exercise-induced fatigue, and the increase of cytosolic free Ca2+ concentration may be one of the important factors of exercise-induced fatigue.

Expression Analysis of cPLA2 Alpha Interacting TIP60 in Diabetic KKAy and Non-Diabetic C57BL Wild-Type Mice: No Impact of Transient and Stable TIP60 Overexpression on Glucose-Stimulated Insulin Secretion in Pancreatic Beta-Cells

DEFF Research Database (Denmark)

Nordentoft, Iver Kristiansen; Jeppesen, Per Bendix; Nielsen, Anders Lade

2007-01-01

In the present study we investigate the expression levels of cytosolic phospholipase A2 alpha (cPLA2alpha) interacting histone acetyl transferase proteins TIP60alpha and TIP60beta in non-diabetic C57BL wild-type mice and obese type 2 diabetic KKAy model mice. The aim was to test our hypothesis...

Activities of Native and Tyrosine-69 Mutant Phospholipases A2 on Phospholipid Analogues. A Reevaluation of the Minimal Substrate Requirements

OpenAIRE

Kuipers, Oscar P.; Dekker, Nicolaas; Verheij, Hubertus M.; Haas, Gerard H. de

1990-01-01

The role of Tyr-69 of porcine pancreatic phospholipase A2 in substrate binding was studied with the help of proteins modified by site-directed mutagenesis and phospholipid analogues with a changed head-group geometry. Two mutants were used containing Phe and Lys, respectively, at position 69. Modifications in the phospholipids included introduction of a sulfur at the phosphorus (thionophospholipids), removal of the negative charge at phosphorus (phosphatidic acid dimethyl ester), and reductio...

Liposomes containing alkylated methotrexate analogues for phospholipase A(2) mediated tumor targeted drug delivery

DEFF Research Database (Denmark)

Kaasgaard, Thomas; Andresen, Thomas Lars; Jensen, Simon Skøde

2009-01-01

of alkylated compounds in liposomes, it was demonstrated that the MTX-analogue partitioned into the water phase and thereby became available for cell uptake. It was concluded that liposomes containing alkylated MTX-analogues show promise as a drug delivery system, although the MTX-analogue needs to be more......Two lipophilic methotrexate analogues have been synthesized and evaluated for cytotoxicity against KATO III and HT-29 human colon cancer cells. Both analogues contained a C-16-alkyl chain attached to the gamma-carboxylic acid and one of the analogues had an additional benzyl group attached...... cytotoxicity was incorporated into liposomes that were designed to be particularly Susceptible to a liposome degrading enzyme, secretory phospholipase A(2) (sPLA(2)), which is found in high concentrations in tumors of several different cancer types. Liposome incorporation was investigated by differential...

In vitro differential activity of phospholipases and acid proteinases of clinical isolates of Candida

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Aurean D'Eça Júnior

2011-06-01

Full Text Available INTRODUCTION: Candida yeasts are commensals; however, if the balance of normal flora is disrupted or the immune defenses are compromised, Candida species can cause disease manifestations. Several attributes contribute to the virulence and pathogenicity of Candida, including the production of extracellular hydrolytic enzymes, particularly phospholipase and proteinase. This study aimed to investigate the in vitro activity of phospholipases and acid proteinases in clinical isolates of Candida spp. METHODS: Eighty-two isolates from hospitalized patients collected from various sites of origin were analyzed. Phospholipase production was performed in egg yolk medium and the production of proteinase was verified in a medium containing bovine serum albumin. The study was performed in triplicate. RESULTS: Fifty-six (68.3% of isolates tested were phospholipase positive and 16 (44.4% were positive for proteinase activity. C. tropicalis was the species with the highest number of positive isolates for phospholipase (91.7%. Statistically significant differences were observed in relation to production of phospholipases among species (p<0,0001 and among the strains from different sites of origin (p=0.014. Regarding the production of acid protease, the isolates of C. parapsilosis tested presented a larger number of producers (69.2%. Among the species analyzed, the percentage of protease producing isolates did not differ statistically (χ2=1.9 p=0.5901 (χ2=1.9 p=0.5901. CONCLUSIONS: The majority of C. non-albicans and all C. albicans isolates were great producers of hydrolytic enzymes and, consequently, might be able to cause infection under favorable conditions.

Edema toxin impairs anthracidal phospholipase A2 expression by alveolar macrophages.

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Benoit Raymond

2007-12-01

Full Text Available Bacillus anthracis, the etiological agent of anthrax, is a spore-forming gram-positive bacterium. Infection with this pathogen results in multisystem dysfunction and death. The pathogenicity of B. anthracis is due to the production of virulence factors, including edema toxin (ET. Recently, we established the protective role of type-IIA secreted phospholipase A2 (sPLA2-IIA against B. anthracis. A component of innate immunity produced by alveolar macrophages (AMs, sPLA2-IIA is found in human and animal bronchoalveolar lavages at sufficient levels to kill B. anthracis. However, pulmonary anthrax is almost always fatal, suggesting the potential impairment of sPLA2-IIA synthesis and/or action by B. anthracis factors. We investigated the effect of purified ET and ET-deficient B. anthracis strains on sPLA2-IIA expression in primary guinea pig AMs. We report that ET inhibits sPLA2-IIA expression in AMs at the transcriptional level via a cAMP/protein kinase A-dependent process. Moreover, we show that live B. anthracis strains expressing functional ET inhibit sPLA2-IIA expression, whereas ET-deficient strains induced this expression. This stimulatory effect, mediated partly by the cell wall peptidoglycan, can be counterbalanced by ET. We conclude that B. anthracis down-regulates sPLA2-IIA expression in AMs through a process involving ET. Our study, therefore, describes a new molecular mechanism implemented by B. anthracis to escape innate host defense. These pioneering data will provide new molecular targets for future intervention against this deadly pathogen.

A new view of the bacterial cytosol environment.

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Benjamin P Cossins

2011-06-01

Full Text Available The cytosol is the major environment in all bacterial cells. The true physical and dynamical nature of the cytosol solution is not fully understood and here a modeling approach is applied. Using recent and detailed data on metabolite concentrations, we have created a molecular mechanical model of the prokaryotic cytosol environment of Escherichia coli, containing proteins, metabolites and monatomic ions. We use 200 ns molecular dynamics simulations to compute diffusion rates, the extent of contact between molecules and dielectric constants. Large metabolites spend ∼80% of their time in contact with other molecules while small metabolites vary with some only spending 20% of time in contact. Large non-covalently interacting metabolite structures mediated by hydrogen-bonds, ionic and π stacking interactions are common and often associate with proteins. Mg(2+ ions were prominent in NIMS and almost absent free in solution. Κ(+ is generally not involved in NIMSs and populates the solvent fairly uniformly, hence its important role as an osmolyte. In simulations containing ubiquitin, to represent a protein component, metabolite diffusion was reduced owing to long lasting protein-metabolite interactions. Hence, it is likely that with larger proteins metabolites would diffuse even more slowly. The dielectric constant of these simulations was found to differ from that of pure water only through a large contribution from ubiquitin as metabolite and monatomic ion effects cancel. These findings suggest regions of influence specific to particular proteins affecting metabolite diffusion and electrostatics. Also some proteins may have a higher propensity for associations with metabolites owing to their larger electrostatic fields. We hope that future studies may be able to accurately predict how binding interactions differ in the cytosol relative to dilute aqueous solution.

Bee Venom Phospholipase A2: Yesterday’s Enemy Becomes Today’s Friend

Science.gov (United States)

Lee, Gihyun; Bae, Hyunsu

2016-01-01

Bee venom therapy has been used to treat immune-related diseases such as arthritis for a long time. Recently, it has revealed that group III secretory phospholipase A2 from bee venom (bee venom group III sPLA2) has in vitro and in vivo immunomodulatory effects. A growing number of reports have demonstrated the therapeutic effects of bee venom group III sPLA2. Notably, new experimental data have shown protective immune responses of bee venom group III sPLA2 against a wide range of diseases including asthma, Parkinson’s disease, and drug-induced organ inflammation. It is critical to evaluate the beneficial and adverse effects of bee venom group III sPLA2 because this enzyme is known to be the major allergen of bee venom that can cause anaphylactic shock. For many decades, efforts have been made to avoid its adverse effects. At high concentrations, exposure to bee venom group III sPLA2 can result in damage to cellular membranes and necrotic cell death. In this review, we summarized the current knowledge about the therapeutic effects of bee venom group III sPLA2 on several immunological diseases and described the detailed mechanisms of bee venom group III sPLA2 in regulating various immune responses and physiopathological changes. PMID:26907347

Calcium-dependent hydrolysis of supported planar lipids was triggered by honey bee venom phospholipase A2 with the right orientation at the interface.

Science.gov (United States)

Kai, Siqi; Li, Xu; Li, Bolin; Han, Xiaofeng; Lu, Xiaolin

2017-12-20

Hydrolysis of planar phospholipids catalyzed by honey bee venom phospholipase A 2 (bvPLA 2 ) was studied. Experiments demonstrated that Ca 2+ ions mediated between the lipids and bvPLA 2 , induced reorientation of bvPLA 2 , and activated hydrolysis. One of the hydrolysis products, fatty acids, was desorbed, and the other one, lysophospholipids, self-organized at the interface.

In Silico and In Vitro Study of the Bromelain-Phytochemical Complex Inhibition of Phospholipase A2 (Pla2

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Fatahiya Mohamed Tap

2018-01-01

Full Text Available Phospholipase A2 (Pla2 is an enzyme that induces inflammation, making Pla2 activity an effective approach to reduce inflammation. Therefore, investigating natural compounds for this Pla2 inhibitory activity has important therapeutic potential. The objective of this study was to investigate the potential in bromelain-phytochemical complex inhibitors via a combination of in silico and in vitro methods. Bromelain-amenthoflavone displays antagonistic effects on Pla2. Bromelian-asiaticoside and bromelain-diosgenin displayed synergistic effects at high concentrations of the combined compounds, with inhibition percentages of more than 70% and 90%, respectively, and antagonistic effects at low concentrations. The synergistic effect of the bromelain-asiaticoside and bromelain-diosgenin combinations represents a new application in treating inflammation. These findings not only provide significant quantitative data, but also provide an insight on valuable implications for the combined use of bromelain with asiaticoside and diosgenin in treating inflammation, and may help researchers develop more natural bioactive compounds in daily foods as anti-inflammatory agent.

Bee Venom Phospholipase A2 Alleviate House Dust Mite-Induced Atopic Dermatitis-Like Skin Lesions by the CD206 Mannose Receptor

OpenAIRE

Dasom Shin; Won Choi; Hyunsu Bae

2018-01-01

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by highly pruritic, erythematous, and eczematous skin plaques. We previously reported that phospholipase A2 (PLA2) derived from bee venom alleviates AD-like skin lesions induced by 2,4-dinitrochlorobenzene (DNCB) and house dust mite extract (Dermatophagoides farinae extract, DFE) in a murine model. However, the underlying mechanisms of PLA2 action in actopic dermatitis remain unclear. In this study, we showed that PLA...

Imidazoline NNC77-0074 stimulates Ca2+-evoked exocytosis in INS-1E cells by a phospholipase A2-dependent mechanism

DEFF Research Database (Denmark)

Olsen, Hervør L; Nørby, Peder L; Høy, Marianne

2003-01-01

We have previously demonstrated that the novel imidazoline compound (+)-2-(2-(4,5-dihydro-1H-imidazol-2-yl)-thiopene-2-yl-ethyl)-pyridine (NNC77-0074) increases insulin secretion from pancreatic beta-cells by stimulation of Ca(2+)-dependent exocytosis. Using capacitance measurements, we now show...... that NNC77-0074 stimulates exocytosis in clonal INS-1E cells. NNC77-0074-stimulated exocytosis was antagonised by the cytoplasmic phospholipase A(2) (cPLA(2)) inhibitors ACA and AACOCF(3) and in cells treated with antisense oligonucleotide against cPLA(2)alpha. NNC77-0074-evoked insulin secretion...... was likewise inhibited by ACA, AACOCF(3), and cPLA(2)alpha antisense oligonucleotide treatment. In pancreatic islets NNC77-0074 stimulated PLA(2) activity. We propose that cPLA(2)alpha plays an important role in the regulation of NNC77-0074-evoked exocytosis in insulin secreting beta-cells....

Liver/kidney microsomal antibody type 1 and liver cytosol antibody type 1 concentrations in type 2 autoimmune hepatitis

OpenAIRE

Muratori, L; Cataleta, M; Muratori, P; Lenzi, M; Bianchi, F

1998-01-01

Background—Liver/kidney microsomal antibody type 1 (LKM1) and liver cytosol antibody type 1 (LC1) are the serological markers of type 2 autoimmune hepatitis (AIH). 
Aims—Since LKM1 and LC1 react against two distinct liver specific autoantigens (cytochrome P450IID6 (CYP2D6) and a 58 kDa cytosolic polypeptide respectively), the aim was to see whether LKM1 and LC1 concentrations correlate with liver disease activity. 
Patients—Twenty one patients with type 2 AIH were studied. 
Methods—A...

Anti-phospholipase A receptor antibodies correlate with clinical status in idiopathic membranous nephropathy

NARCIS (Netherlands)

Hofstra, J.M.; Beck Jr., L.H.; Beck, D.M.; Wetzels, J.F.M.; Salant, D.J.

2011-01-01

BACKGROUND AND OBJECTIVES: Circulating autoantibodies against the M-type phospholipase A(2) receptor (anti-PLA(2)R) were recently identified in the majority of patients in the United States with idiopathic membranous nephropathy (iMN). The objectives of this study were to assess the prevalence of

Chromosomal instability drives metastasis through a cytosolic DNA response.

Science.gov (United States)

Bakhoum, Samuel F; Ngo, Bryan; Laughney, Ashley M; Cavallo, Julie-Ann; Murphy, Charles J; Ly, Peter; Shah, Pragya; Sriram, Roshan K; Watkins, Thomas B K; Taunk, Neil K; Duran, Mercedes; Pauli, Chantal; Shaw, Christine; Chadalavada, Kalyani; Rajasekhar, Vinagolu K; Genovese, Giulio; Venkatesan, Subramanian; Birkbak, Nicolai J; McGranahan, Nicholas; Lundquist, Mark; LaPlant, Quincey; Healey, John H; Elemento, Olivier; Chung, Christine H; Lee, Nancy Y; Imielenski, Marcin; Nanjangud, Gouri; Pe'er, Dana; Cleveland, Don W; Powell, Simon N; Lammerding, Jan; Swanton, Charles; Cantley, Lewis C

2018-01-25

Chromosomal instability is a hallmark of cancer that results from ongoing errors in chromosome segregation during mitosis. Although chromosomal instability is a major driver of tumour evolution, its role in metastasis has not been established. Here we show that chromosomal instability promotes metastasis by sustaining a tumour cell-autonomous response to cytosolic DNA. Errors in chromosome segregation create a preponderance of micronuclei whose rupture spills genomic DNA into the cytosol. This leads to the activation of the cGAS-STING (cyclic GMP-AMP synthase-stimulator of interferon genes) cytosolic DNA-sensing pathway and downstream noncanonical NF-κB signalling. Genetic suppression of chromosomal instability markedly delays metastasis even in highly aneuploid tumour models, whereas continuous chromosome segregation errors promote cellular invasion and metastasis in a STING-dependent manner. By subverting lethal epithelial responses to cytosolic DNA, chromosomally unstable tumour cells co-opt chronic activation of innate immune pathways to spread to distant organs.

Investigating interactions between phospholipase B-Like 2 and antibodies during Protein A chromatography.

Science.gov (United States)

Tran, Benjamin; Grosskopf, Vanessa; Wang, Xiangdan; Yang, Jihong; Walker, Don; Yu, Christopher; McDonald, Paul

2016-03-18

Purification processes for therapeutic antibodies typically exploit multiple and orthogonal chromatography steps in order to remove impurities, such as host-cell proteins. While the majority of host-cell proteins are cleared through purification processes, individual host-cell proteins such as Phospholipase B-like 2 (PLBL2) are more challenging to remove and can persist into the final purification pool even after multiple chromatography steps. With packed-bed chromatography runs using host-cell protein ELISAs and mass spectrometry analysis, we demonstrated that different therapeutic antibodies interact to varying degrees with host-cell proteins in general, and PLBL2 specifically. We then used a high-throughput Protein A chromatography method to further examine the interaction between our antibodies and PLBL2. Our results showed that the co-elution of PLBL2 during Protein A chromatography is highly dependent on the individual antibody and PLBL2 concentration in the chromatographic load. Process parameters such as antibody resin load density and pre-elution wash conditions also influence the levels of PLBL2 in the Protein A eluate. Furthermore, using surface plasmon resonance, we demonstrated that there is a preference for PLBL2 to interact with IgG4 subclass antibodies compared to IgG1 antibodies. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of Serum Phospholipase A2 Activity in Three Diverse Species of West African Crocodiles

Directory of Open Access Journals (Sweden)

Mark Merchant

2011-01-01

Full Text Available Secretory phospholipase A2, an enzyme that exhibits substantial immunological activity, was measured in the serum of three species of diverse West African crocodiles. Incubation of different volumes of crocodile serum with bacteria labeled with a fluorescent fatty acid in the sn-2 position of membrane lipids resulted in a volume-dependent liberation of fluorescent probe. Serum from the Nile crocodile (Crocodylus niloticus exhibited slightly higher activity than that of the slender-snouted crocodile (Mecistops cataphractus and the African dwarf crocodile (Osteolaemus tetraspis. Product formation was inhibited by BPB, a specific PLA2 inhibitor, confirming that the activity was a direct result of the presence of serum PLA2. Kinetic analysis showed that C. niloticus serum produced product more rapidly than M. cataphractus or O. tetraspis. Serum from all three species exhibited temperature-dependent PLA2 activities but with slightly different thermal profiles. All three crocodilian species showed high levels of activity against eight different species of bacteria.

Rac1 is essential for phospholipase C-gamma2 activation in platelets

DEFF Research Database (Denmark)

Pleines, Irina; Elvers, Margitta; Strehl, Amrei

2008-01-01

isoenzymes are activated downstream of G protein-coupled receptors (GPCRs), whereas PLCgamma2 is activated downstream of immunoreceptor tyrosine-based activation motif (ITAM)-coupled receptors, such as the major platelet collagen receptor glycoprotein (GP) VI or CLEC-2. The mechanisms underlying PLC......Platelet activation at sites of vascular injury is triggered through different signaling pathways leading to activation of phospholipase (PL) Cbeta or PLCgamma2. Active PLCs trigger Ca(2+) mobilization and entry, which is a prerequisite for adhesion, secretion, and thrombus formation. PLCbeta...... regulation are not fully understood. An involvement of small GTPases of the Rho family (Rho, Rac, Cdc42) in PLC activation has been proposed but this has not been investigated in platelets. We here show that murine platelets lacking Rac1 display severely impaired GPVI- or CLEC-2-dependent activation...

Bee venom phospholipase A2 induces a primary type 2 response that is dependent on the receptor ST2 and confers protective immunity.

Science.gov (United States)

Palm, Noah W; Rosenstein, Rachel K; Yu, Shuang; Schenten, Dominik D; Florsheim, Esther; Medzhitov, Ruslan

2013-11-14

Venoms consist of toxic components that are delivered to their victims via bites or stings. Venoms also represent a major class of allergens in humans. Phospholipase A2 (PLA2) is a conserved component of venoms from multiple species and is the major allergen in bee venom. Here we examined how bee venom PLA2 is sensed by the innate immune system and induces a type 2 immune response in mice. We found that bee venom PLA2 induced a T helper type 2 (Th2) cell-type response and group 2 innate lymphoid cell activation via the enzymatic cleavage of membrane phospholipids and release of interleukin-33. Furthermore, we showed that the IgE response to PLA2 could protect mice from future challenge with a near-lethal dose of PLA2. These data suggest that the innate immune system can detect the activity of a conserved component of venoms and induce a protective immune response against a venom toxin. Copyright © 2013 Elsevier Inc. All rights reserved.

Glutamate signalling and secretory phospholipase A2 modulate the release of arachidonic acid from neuronal membranes

DEFF Research Database (Denmark)

Rodriguez De Turco, Elena B; Jackson, Fannie R; DeCoster, Mark A

2002-01-01

The lipid mediators generated by phospholipases A(2) (PLA(2)), free arachidonic acid (AA), eicosanoids, and platelet-activating factor, modulate neuronal activity; when overproduced, some of them become potent neurotoxins. We have shown, using primary cortical neuron cultures, that glutamate...... and secretory PLA(2) (sPLA(2)) from bee venom (bv sPLA(2)) and Taipan snake venom (OS2) elicit synergy in inducing neuronal cell death. Low concentrations of sPLA(2) are selective ligands of cell-surface sPLA(2) receptors. We investigated which neuronal arachidonoyl phospholipids are targeted by glutamate......) and in minor changes in other phospholipids. A similar profile, although of greater magnitude, was observed 20 hr posttreatment. Glutamate (80 microM) induced much less mobilization of (3)H-AA than did sPLA(2) and resulted in a threefold greater degradation of (3)H-AA PE than of (3)H-AA PC by 20 hr...

Cloning and characterization of human liver cytosolic beta-glycosidase

NARCIS (Netherlands)

De Graaf, M; Van Veen, IC; Van Der Meulen-Muileman, IH; Gerritsen, WR; Pinedo, HM; Haisma, HJ

2001-01-01

Cytosolic beta -glucosidase (EC 3.2.1.21) from mammalian liver is a member of the family 1 glycoside hydrolases and is known for its ability to hydrolyse a range of beta -D-glycosides. including beta -D-glucoside acid beta -D-galactoside. We therefore refer to this enzyme as cytosolic beta

Secreted phospholipase A2 of Clonorchis sinensis activates hepatic stellate cells through a pathway involving JNK signalling.

Science.gov (United States)

Wu, Yinjuan; Li, Ye; Shang, Mei; Jian, Yu; Wang, Caiqin; Bardeesi, Adham Sameer A; Li, Zhaolei; Chen, Tingjin; Zhao, Lu; Zhou, Lina; He, Ai; Huang, Yan; Lv, Zhiyue; Yu, Xinbing; Li, Xuerong

2017-03-16

Secreted phospholipase A2 (sPLA2) is a protein secreted by Clonorchis sinensis and is a component of excretory and secretory products (CsESPs). Phospholipase A2 is well known for its role in liver fibrosis and inhibition of tumour cells. The JNK signalling pathway is involved in hepatic stellate cells (HSCs) activation. Blocking JNK activity with SP600125 inhibits HSCs activation. In a previous study, the protein CssPLA2 was expressed in insoluble inclusion bodies. Therefore, it's necessary to express CssPLA2 in water-soluble form and determine whether the enzymatic activity of CssPLA2 or cell signalling pathways is involved in liver fibrosis caused by clonorchiasis. Balb/C mice were given an abdominal injection of MBP-CssPLA2. Liver sections with HE and Masson staining were observed to detect accumulation of collagen. Western blot of mouse liver was done to detect the activation of JNK signalling pathway. In vitro, HSCs were incubated with MBP-CssPLA2 to detect the activation of HSCs as well as the activation of JNK signalling pathway. The mutant of MBP-CssPLA2 without enzymatic activity was constructed and was also incubated with HSCs to check whether activation of the HSCs was related to the enzymatic activity of MBP-CssPLA2. The recombinant protein MBP-CssPLA2 was expressed soluble and of good enzymatic activity. A mutant of CssPLA2, without enzymatic activity, was also constructed. In vivo liver sections of Balb/C mice that were given an abdominal injection of 50 μg/ml MBP-CssPLA2 showed an obvious accumulation of collagen and a clear band of P-JNK1 could be seen by western blot of the liver tissue. In vitro, MBP-CssPLA2, as well as the mutant, was incubated with HSCs and it was proved that activation of HSCs was related to activation of the JNK signalling pathway instead of the enzymatic activity of MBP-CssPLA2. Activation of HSCs by CssPLA2 is related to the activation of the JNK signalling pathway instead of the enzymatic activity of CssPLA2. This finding

Lipoprotein profile, lipoprotein-associated phospholipase A2 and cardiovascular risk in hemodialysis patients.

Science.gov (United States)

Rolla, Roberta; De Mauri, Andreana; Valsesia, Ambra; Vidali, Matteo; Chiarinotti, Doriana; Bellomo, Giorgio

2015-12-01

Cardiovascular disease is the leading cause of morbidity and mortality in hemodialysis patients; the increased risk of cardiovascular disease is due to accelerated atherosclerosis, inflammation and impaired lipoprotein metabolism. We aimed to evaluate lipoprotein-associated phospholipase A2 (Lp-PLA2) and some pro-inflammatory aspects of the lipoprotein profile in dialyzed patients in order to evaluate the relationship with the accelerated atherosclerosis and vascular accidents. In 102 dialysis patients and 40 non-uremic controls, we investigated the lipoprotein plasma profile, high sensitivity C-reactive protein (CRP), ceruloplasmin and serum amyloid A protein (SAA), and followed patients for 1 year to analyze the risk of acute cardiovascular events. Total cholesterol, low-density lipoprotein and high-density lipoprotein plasma levels were significantly lower in uremic patients than controls, whereas CRP, SAA, ceruloplasmin, Lp-PLA2 and their ratio with apolipoprotein A1 were significantly higher. Patients with Lp-PLA2 levels >194 nmol/min/ml had more acute cardiovascular events than patients with lower values. Our results show that in dialysis subjects: (1) low-density lipoproteins show a more atherogenic phenotype than in the general population; (2) high-density lipoproteins are less anti-inflammatory; (3) Lp-PLA2 could potentially be used to evaluate cardiovascular risk.

Evaluation of different glycoforms of honeybee venom major allergen phospholipase A2 (Api m 1) produced in insect cells

DEFF Research Database (Denmark)

Blank, Simon; Seismann, Henning; Plum, Melanie

2011-01-01

Allergic reactions to hymenoptera stings are one of the major reasons for IgE-mediated anaphylaxis. However, proper diagnosis using venom extracts is severely affected by molecular cross-reactivity. In this study recombinant honeybee venom major allergen phospholipase A2 (Api m 1) was produced......-derived recombinant Api m 1 with defined CCD phenotypes might provide further insights into hymenoptera venom IgE reactivities and contribute to an improved diagnosis of hymenoptera venom allergy....

AM fungal exudates activate MAP kinases in plant cells in dependence from cytosolic Ca(2+) increase.

Science.gov (United States)

Francia, Doriana; Chiltz, Annick; Lo Schiavo, Fiorella; Pugin, Alain; Bonfante, Paola; Cardinale, Francesca

2011-09-01

The molecular dialogue occurring prior to direct contact between the fungal and plant partners of arbuscular-mycorrhizal (AM) symbioses begins with the release of fungal elicitors, so far only partially identified chemically, which can activate specific signaling pathways in the host plant. We show here that the activation of MAPK is also induced by exudates of germinating spores of Gigaspora margarita in cultured cells of the non-leguminous species tobacco (Nicotiana tabacum), as well as in those of the model legume Lotus japonicus. MAPK activity peaked about 15 min after the exposure of the host cells to the fungal exudates (FE). FE were also responsible for a rapid and transient increase in free cytosolic Ca(2+) in Nicotiana plumbaginifolia and tobacco cells, and pre-treatment with a Ca(2+)-channel blocker (La(3+)) showed that in these cells, MAPK activation was dependent on the cytosolic Ca(2+) increase. A partial dependence of MAPK activity on the common Sym pathway could be demonstrated for a cell line of L. japonicus defective for LjSym4 and hence unable to establish an AM symbiosis. Our results show that MAPK activation is triggered by an FE-induced cytosolic Ca(2+) transient, and that a Sym genetic determinant acts to modulate the intensity and duration of this activity. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

A membrane model for cytosolic calcium oscillations. A study using Xenopus oocytes.

OpenAIRE

Jafri, M S; Vajda, S; Pasik, P; Gillo, B

1992-01-01

Cytosolic calcium oscillations occur in a wide variety of cells and are involved in different cellular functions. We describe these calcium oscillations by a mathematical model based on the putative electrophysiological properties of the endoplasmic reticulum (ER) membrane. The salient features of our membrane model are calcium-dependent calcium channels and calcium pumps in the ER membrane, constant entry of calcium into the cytosol, calcium dependent removal from the cytosol, and buffering ...

Fluctuations in Cytosolic Calcium Regulate the Neuronal Malate-Aspartate NADH Shuttle

DEFF Research Database (Denmark)

Satrústegui, Jorgina; Bak, Lasse K

2015-01-01

that MAS is regulated by fluctuations in cytosolic Ca(2+) levels, and that this regulation is required to maintain a tight coupling between neuronal activity and mitochondrial respiration and oxidative phosphorylation. At cytosolic Ca(2+) fluctuations below the threshold of the mitochondrial calcium...

Deinhibition of cardiac Na+-K+-ATPase after exposure to exogenous phospholipase A2

International Nuclear Information System (INIS)

Colvin, R.A.

1987-01-01

After 2 h of exogenous phospholipase A 2 (PLA 2 ) exposure, membrane phospholipid decreased from 3.22 +/- 0.31 to 1.06 +/- 0.13 μmol/mg (33% of control). All classes of phospholipid, except sphingomyelin, were hydrolyzed, whereas total cholesterol content was unaffected. Increases in nonesterified fatty acids (NEFA) were reflected primarily in oleic (18:1), linoleic (18:2), and arachidonic (20:4). Na + -K + -adenosinetriphosphatase (ATPase) activity was inhibited to 29% of control by 2 h of PLA 2 treatment, and this inhibition was reversed (albeit, not completely after 5 min of PLA 2 treatment) by removal of the hydrolysis products with 0.1% bovine serum albumin (BSA). In contrast, the apparent binding capacity for [ 3 H]ouabain was not affected by PLA 2 treatment. Unmasking of latent [ 3 H]ouabain binding by alamethicin was utilized to estimate changes in the proportion of sealed vesicles present before and after PLA 2 treatment. PLA 2 treatment resulted in a time-dependent loss of sealed vesicles that paralleled the time course of phospholipid hydrolysis and was not reversed by washing with BSA. These studies demonstrate that cardiac Na + -K + -ATPase activity is inhibited by accumulation of endogenously produced lysophospholipids and NEFA. In contrast, loss of vesicle integrity may result from both accumulation of endogenously produced hydrolysis products and membrane phospholipid depletion

Assay strategies and methods for phospholipases

International Nuclear Information System (INIS)

Reynolds, L.J.; Washburn, W.N.; Deems, R.A.; Dennis, E.A.

1991-01-01

Of the general considerations discussed, the two issues which are most important in choosing an assay are (1) what sensitivity is required to assay a particular enzyme and (2) whether the assay must be continuous. One can narrow the options further by considering substrate availability, enzyme specificity, assay convenience, or the presence of incompatible side reactions. In addition, the specific preference of a particular phospholipase for polar head group, micellar versus vesicular substrates, and anionic versus nonionic detergents may further restrict the options. Of the many assays described in this chapter, several have limited applicability or serious drawbacks and are not commonly employed. The most commonly used phospholipase assays are the radioactive TLC assay and the pH-stat assay. The TLC assay is probably the most accurate, sensitive assay available. These aspects often outweigh the disadvantages of being discontinuous, tedious, and expensive. The radioactive E. coli assay has become popular recently as an alternative to the TLC assay for the purification of the mammalian nonpancreatic phospholipases. The assay is less time consuming and less expensive than the TLC assay, but it is not appropriate when careful kinetics are required. Where less sensitivity is needed, or when a continuous assay is necessary, the pH-stat assay is often employed. With purified enzymes, when free thiol groups are not present, a spectrophotometric thiol assay can be used. This assay is ∼ as sensitive as the pH-stat assay but is more convenient and more reproducible, although the substrate is not available commercially. Despite the many assay choices available, the search continues for a convenient, generally applicable assay that is both sensitive and continuous

Interplay between ABA and phospholipases A(2) and D in the response of citrus fruit to postharvest dehydration.

Science.gov (United States)

Romero, Paco; Gandía, Mónica; Alférez, Fernando

2013-09-01

The interplay between abscisic acid (ABA) and phospholipases A2 and D (PLA2 and PLD) in the response of citrus fruit to water stress was investigated during postharvest by using an ABA-deficient mutant from 'Navelate' orange named 'Pinalate'. Fruit from both varieties harvested at two different maturation stages (mature-green and full-mature) were subjected to prolonged water loss inducing stem-end rind breakdown (SERB) in full-mature fruit. Treatment with PLA2 inhibitor aristolochic acid (AT) and PLD inhibitor lysophosphatidylethanolamine (LPE) reduced the disorder in both varieties, suggesting that phospholipid metabolism is involved in citrus peel quality. Expression of CsPLDα and CsPLDβ, and CssPLA2α and CssPLA2β was studied by real-time RT-PCR during water stress and in response to ABA. CsPLDα expression increased in mature-green fruit from 'Navelate' but not in 'Pinalate' and ABA did not counteract this effect. ABA enhanced repression of CsPLDα in full-mature fruit. CsPLDβ gene expression decreased in mature-green 'Pinalate', remained unchanged in 'Navelate' and was induced in full-mature fruit from both varieties. CssPLA2α expression increased in mature-green fruit from both varieties whereas in full-mature fruit only increased in 'Navelate'. CssPLA2β expression increased in mature-green flavedo from both varieties, but in full-mature fruit remained steady in 'Navelate' and barely increased in 'Pinalate' fruit. ABA reduced expression in both after prolonged storage. Responsiveness to ABA increased with maturation. Our results show interplay between PLA2 and PLD and suggest that ABA action is upstream phospholipase activation. Response to ABA during water stress in citrus is regulated during fruit maturation and involves membrane phospholipid degradation. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications

OpenAIRE

Borrelli, Grazia M.; Trono, Daniela

2015-01-01

Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile bioc...

Nicotine-evoked cytosolic Ca2+ increase and cell depolarization in capillary endothelial cells of the bovine adrenal medulla

Directory of Open Access Journals (Sweden)

RAÚL VINET

2009-01-01

Full Text Available Endothelial cells are directly involved in many functions of the cardiovascular system by regulating blood flow and blood pressure through Ca2+ dependent exocitosis of vasoactive compounds. Using the Ca2+ indicator Fluo-3 and the patch-clamp technique, we show that bovine adrenal medulla capillary endothelial cells (B AMCECs respond to acetylcholine (ACh with a cytosolic Ca2+ increase and depolarization of the membrane potential (20.3±0.9 mV; n=23. The increase in cytosolic Ca2+ induced by 10µM ACh was mimicked by the same concentration of nicotine but not by muscarine and was blocked by 100 µM of hexamethonium. On the other hand, the increase in cytosolic Ca2+ could be depressed by nifedipine (0.01 -100 µM or withdrawal of extracellular Ca2+. Taken together, these results give evidence for functional nicotinic receptors (nAChRs in capillary endothelial cells of the adrenal medulla. It suggests that nAChRs in B AMCECs may be involved in the regulation of the adrenal gland's microcirculation by depolarizing the membrane potential, leading to the opening of voltage-activated Ca2+ channels, influx of external Ca2+ and liberation of vasoactive compounds.

Recognition of acidic phospholipase A2 activity in plasma membranes of resident peritoneal macrophages

International Nuclear Information System (INIS)

Shibata, Y.; Abiko, Y.; Ohno, H.; Araki, T.; Takiguchi, H.

1988-01-01

Phospholipase (PLase) activities in the plasma membrane of guinea pig peritoneal macrophages were studied, as these enzymes having such activity may be candidates for the release of arachidonic acid (AA) from phosphatidylcholine (PC). An AA release system operating at acidic pH was identified in the macrophage plasma membrane and characterized. This membrane-bound acidic PLase A 2 had an optimum pH at 4.5, and enzyme activation was observed in Ca ++ -free medium; but the maximum activity was found at 0.5 mM Ca ++ concentration. The Km value for PC of acidic PLase A 2 was 4.2 μM, and a Michaelis-Menten relationship was evident. Calcium might act as a cofactor at some intermediate step during the activation of acidic PLase A 2 in light of the uncompetitive manner of Ca ++ action. Furthermore, the release of [ 3 H]-AA from preradiolabelled macrophage plasma membranes occurred with the addition of Ca ++ at pH 4.5. These data suggest that the acid PLase A 2 is a component of the plasma membrane and is not due to lysosomal contamination since membrane-bound acidic PLase A 2 properties are opposite to those found for lysosomal PLase A 2

Alkylation of histidine residues of Bothrops jararacussu venom proteins and isolated phospholipases A2: a biotechnological tool to improve the production of antibodies.

Science.gov (United States)

Guimarães, C L S; Andrião-Escarso, S H; Moreira-Dill, L S; Carvalho, B M A; Marchi-Salvador, D P; Santos-Filho, N A; Fernandes, C A H; Fontes, M R M; Giglio, J R; Barraviera, B; Zuliani, J P; Fernandes, C F C; Calderón, L A; Stábeli, R G; Albericio, F; da Silva, S L; Soares, A M

2014-01-01

Crude venom of Bothrops jararacussu and isolated phospholipases A2 (PLA2) of this toxin (BthTX-I and BthTX-II) were chemically modified (alkylation) by p-bromophenacyl bromide (BPB) in order to study antibody production capacity in function of the structure-function relationship of these substances (crude venom and PLA2 native and alkylated). BthTX-II showed enzymatic activity, while BthTX-I did not. Alkylation reduced BthTX-II activity by 50% while this process abolished the catalytic and myotoxic activities of BthTX-I, while reducing its edema-inducing activity by about 50%. Antibody production against the native and alkylated forms of BthTX-I and -II and the cross-reactivity of antibodies to native and alkylated toxins did not show any apparent differences and these observations were reinforced by surface plasmon resonance (SPR) data. Histopathological analysis of mouse gastrocnemius muscle sections after injection of PBS, BthTX-I, BthTX-II, or both myotoxins previously incubated with neutralizing antibody showed inhibition of the toxin-induced myotoxicity. These results reveal that the chemical modification of the phospholipases A2 (PLA2) diminished their toxicity but did not alter their antigenicity. This observation indicates that the modified PLA2 may provide a biotechnological tool to attenuate the toxicity of the crude venom, by improving the production of antibodies and decreasing the local toxic effects of this poisonous substance in animals used to produce antivenom.

Calcium-independent phospholipase A2 regulates retinal pigment epithelium proliferation and may be important in the pathogenesis of retinal diseases

DEFF Research Database (Denmark)

Kolko, M; Kiilgaard, J F; Wang, J

2009-01-01

Calcium-independent phospholipase A2, group VIA (iPLA2-VIA) is involved in cell proliferation. This study aimed to evaluate the role of iPLA2-VIA in retinal pigment epithelium (RPE) cell proliferation and in retinal diseases involving RPE proliferation. A human RPE cell line (ARPE-19) was used...... the expression of iPLA2-VIA in proliferative vitreoretinopathy (PVR). PVR membranes revealed nuclear expression of iPLA2-VIA in the RPE cells which had migrated and participated in the formation of the membranes. Overall, the present results point to an important role of iPLA2-VIA in the regulation of RPE...

Assay of phospholipases A2 and their inhibitors by kinetic analysis in the scooting mode

Directory of Open Access Journals (Sweden)

Mahendra Kumar Jain

1992-01-01

Full Text Available Several cellular processes are regulated by interfacial catalysis on biomembrane surfaces. Phospholipases A2 (PLA2 are interesting not only as prototypes for interfacial catalysis, but also because they mobilize precursors for the biosynthesis of eicosanoids and platelet activating factor, and these agents ultimately control a wide range of secretory and inflammatory processes. Since PLA2 carry out their catalytic function at membrane surfaces, the kinetics of these enzymes depends on what the enzyme ‘sees’ at the interface, and thus the observed rate is profoundly influenced by the organization and dynamics of the lipidwater interface (‘quality of the interface’. In this review we elaborate the advantages of monitoring interfacial catalysis in the scooting mode, that is, under the conditions where the enzyme remains bound to vesicles for several thousand catalytic turnover cycles. Such a highly processive catalytic turnover in the scooting mode is useful for a rigorous and quantitative characterization of the kinetics of interfacial catalysis. This analysis is now extended to provide insights into designing strategy for PLA2 assays and screens for their inhibitors.

Expression of enzymatically inactive wasp venom phospholipase A1 in Pichia pastoris.

Directory of Open Access Journals (Sweden)

Irina Borodina

Full Text Available Wasp venom allergy is the most common insect venom allergy in Europe. It is manifested by large local reaction or anaphylactic shock occurring after a wasp sting. The allergy can be treated by specific immunotherapy with whole venom extracts. Wasp venom is difficult and costly to obtain and is a subject to composition variation, therefore it can be advantageous to substitute it with a cocktail of recombinant allergens. One of the major venom allergens is phospholipase A1, which so far has been expressed in Escherichia coli and in insect cells. Our aim was to produce the protein in secreted form in yeast Pichia pastoris, which can give high yields of correctly folded protein on defined minimal medium and secretes relatively few native proteins simplifying purification.Residual amounts of enzymatically active phospholipase A1 could be expressed, but the venom protein had a deleterious effect on growth of the yeast cells. To overcome the problem we introduced three different point mutations at the critical points of the active site, where serine137, aspartate165 or histidine229 were replaced by alanine (S137A, D165A and H229A. All the three mutated forms could be expressed in P. pastoris. The H229A mutant did not have any detectable phospholipase A1 activity and was secreted at the level of several mg/L in shake flask culture. The protein was purified by nickel-affinity chromatography and its identity was confirmed by MALDI-TOF mass spectrometry. The protein could bind IgE antibodies from wasp venom allergic patients and could inhibit the binding of wasp venom to IgE antibodies specific for phospholipase A1 as shown by Enzyme Allergo-Sorbent Test (EAST. Moreover, the recombinant protein was allergenic in a biological assay as demonstrated by its capability to induce histamine release of wasp venom-sensitive basophils.The recombinant phospholipase A1 presents a good candidate for wasp venom immunotherapy.

The role of a cytosolic superoxide dismutase in barley-pathogen interactions

KAUST Repository

Lightfoot, Damien; Mcgrann, Graham R. D.; Able, Amanda J.

2016-01-01

susceptible background (cv. Golden Promise), when compared with wild-type plants, suggesting that cytosolic O2-HO2 contributes to the signalling required to induce a defence response to Ptt. There was no effect of HvCSD1 knockdown on infection by the hemi

AIM2-Like Receptors Positively and Negatively Regulate the Interferon Response Induced by Cytosolic DNA

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Yuki Nakaya

2017-07-01

Full Text Available Cytosolic DNAs derived from retrotransposons serve as pathogen-associated molecular patterns for pattern recognition receptors (PRRs that stimulate the induction of interferons (IFNs and other cytokines, leading to autoimmune disease. Cyclic GMP-AMP synthase is one PRR that senses retrotransposon DNA, activating type I IFN responses through the stimulator of IFN genes (STING. Absent in melanoma 2 (AIM2-like receptors (ALRs have also been implicated in these pathways. Here we show that the mouse ALR IFI205 senses cytosolic retrotransposon DNA independently of cyclic GMP-AMP production. AIM2 antagonizes IFI205-mediated IFN induction activity by sequestering it from STING. We also found that the complement of genes located in the ALR locus in C57BL/6 and AIM2 knockout mice are different and unique, which has implications for interpretation of the sensing of pathogens in different mouse strains. Our data suggest that members of the ALR family are critical to the host IFN response to endogenous DNA.

Silencing of cytosolic NADP+-dependent isocitrate dehydrogenase gene enhances ethanol-induced toxicity in HepG2 cells.

Science.gov (United States)

Yang, Eun Sun; Lee, Su-Min; Park, Jeen-Woo

2010-07-01

It has been shown that acute and chronic alcohol administrations increase the production of reactive oxygen species, lower cellular antioxidant levels and enhance oxidative stress in many tissues. We recently reported that cytosolic NADP(+)-dependent isocitrate dehydrogenase (IDPc) functions as an antioxidant enzyme by supplying NADPH to the cytosol. Upon exposure to ethanol, IDPc was susceptible to the loss of its enzyme activity in HepG2 cells. Transfection of HepG2 cells with an IDPc small interfering RNA noticeably downregulated IDPc and enhanced the cells' vulnerability to ethanol-induced cytotoxicity. Our results suggest that suppressing the expression of IDPc enhances ethanol-induced toxicity in HepG2 cells by further disruption of the cellular redox status.

The Arabidopsis cytosolic proteome

DEFF Research Database (Denmark)

Ito, Jun; Parsons, Harriet Tempé; Heazlewood, Joshua L.

2014-01-01

compartments. However, a detailed study of enriched cytosolic fractions from Arabidopsis cell culture has been performed only recently, with over 1,000 proteins reproducibly identified by mass spectrometry. The number of proteins allocated to the cytosol nearly doubles to 1,802 if a series of targeted...

The role of a cytosolic superoxide dismutase in barley-pathogen interactions

KAUST Repository

Lightfoot, Damien

2016-03-19

Reactive oxygen species (ROS), including superoxide (O2-HO2) and hydrogen peroxide (H2O2), are differentially produced during resistance responses to biotrophic pathogens and during susceptible responses to necrotrophic and hemi-biotrophic pathogens. Superoxide dismutase (SOD) is responsible for the catalysis of the dismutation of O2-HO2 to H2O2, regulating the redox status of plant cells. Increased SOD activity has been correlated previously with resistance in barley to the hemi-biotrophic pathogen Pyrenophora teres f. teres (Ptt, the causal agent of the net form of net blotch disease), but the role of individual isoforms of SOD has not been studied. A cytosolic CuZnSOD, HvCSD1, was isolated from barley and characterized as being expressed in tissue from different developmental stages. HvCSD1 was up-regulated during the interaction with Ptt and to a greater extent during the resistance response. Net blotch disease symptoms and fungal growth were not as pronounced in transgenic HvCSD1 knockdown lines in a susceptible background (cv. Golden Promise), when compared with wild-type plants, suggesting that cytosolic O2-HO2 contributes to the signalling required to induce a defence response to Ptt. There was no effect of HvCSD1 knockdown on infection by the hemi-biotrophic rice blast pathogen Magnaporthe oryzae or the biotrophic powdery mildew pathogen Blumeria graminis f. sp. hordei, but HvCSD1 also played a role in the regulation of lesion development by methyl viologen. Together, these results suggest that HvCSD1 could be important in the maintenance of the cytosolic redox status and in the differential regulation of responses to pathogens with different lifestyles.

Phospholipases AtPLDζ1 and AtPLDζ2 function differently in hypoxia

DEFF Research Database (Denmark)

Lindberg, Sylvia; Premkumar, Albert; Rasmussen, Ulla

2018-01-01

by fluorescence microscopy and the fluorescent dyes Fura 2-AM and CM-H2 DCFDA, specific for calcium and H2 O2 , respectively, while PA production was analysed by an enzymatic method. The study reveals that AtPLDζ1 is involved in ROS signalling, whereas AtPLDζ2 is involved in cytosolic Ca(2+) signalling pathways...... during hypoxic stress. Hypoxia induces an elevation of PA level both in Wt and pldζ1, while the PA level is unchanged in pldζ2. Thus, it is likely that AtPLDζ2 is involved in PA production by a calcium signalling pathway, while AtPLDζ1 is more important in ROS signalling....

Study of association between genetic polymorphisms of phospholipase A2 enzymes and Alzheimer's disease Associação entre polimorfismos das enzimas fosfolipases A2 e doença de Alzheimer

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Quirino Cordeiro

2010-04-01

Full Text Available Several genes have been related to late-onset Alzheimer's disease (LOAD. Phospholipases A2 (PLA2 influence the processing and secretion of the amyloid precursor protein, which gives rise to the beta-amyloid peptide, the major component of the amyloid plaque in AD. Hence, in the present study, polymorphisms of three genes encoding PLA2 enzymes group (cytosolic PLA2: BanI cPLA2 polymorphism; calcium-independent PLA2: AvrII iPLA2 polymorphism; PAFAH: Val279Phe PAFAH polymorphism were analysed in a case-control sample using 58 patients with LOAD and 107 matched healthy controls. There was a genotypic association between the BanI cPLA2 polymorphism and LOAD (χ2=6.25, 2df, p=0.04, however there was no allelic association. There were no associations between AvrII iPLA2 and Val279Phe PAFAH polymorphisms and LOAD. These data suggest that the BanI cPLA2 polymorphism may play a role in the susceptibility for LOAD in our Brazilian sample.Vários genes têm sido investigados como fatores de risco para o desenvolvimento da doença de Alzheimer (DA de início tardio. As fosfolipases A2 (PLA2 influenciam o processamento e secreção da proteína precursora do amilóide, que dá origem ao peptídeo meta-amilóide, o principal componente da placa amilóide na DA. Assim, no presente estudo, foram analisados três polimorfismos genéticos que codificam enzimas do grupo das PLA2 (PLA2 citosólica: polimorfismo BanI cPLA2; PLA2 cálcio-independente: polimorfismo AvrII iPLA2; PAFAH: polimorfismo Val279Phe PAFAH em 58 pacientes com DA de início tardio e 107 controles saudáveis pareados. Houve associação genotípica entre o polimorfismo BanI cPLA2 e DA de início tardio (χ2=6,25, 2df, p=0,04; no entanto não foi observada associação alélica. Não houve associação entre os polimorfismos AvrII iPLA2 e Val279Phe PAFAH com a doença. Tais dados sugerem que o polimorfismo BanI cPLA2 pode estar envolvido como fator de susceptibilidade para DA de início tardio em

Enzymatic hydrolysis of short-chain lecithin/long-chain phospholipid unilamellar vesicles: sensitivity of phospholipases to matrix phase state.

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Gabriel, N E; Agman, N V; Roberts, M F

1987-11-17

Short-chain lecithin/long-chain phospholipid unilamellar vesicles (SLUVs), unlike pure long-chain lecithin vesicles, are excellent substrates for water-soluble phospholipases. Hemolysis assays show that greater than 99.5% of the short-chain lecithin is partitioned in the bilayer. In these binary component vesicles, the short-chain species is the preferred substrate, while the long-chain phospholipid can be treated as an inhibitor (phospholipase C) or poor substrate (phospholipase A2). For phospholipase C Bacillus cereus, apparent Km and Vmax values show that bilayer-solubilized diheptanoylphosphatidylcholine (diheptanoyl-PC) is nearly as good a substrate as pure micellar diheptanoyl-PC, although the extent of short-chain lecithin hydrolysis depends on the phase state of the long-chain lipid. For phospholipase A2 Naja naja naja, both Km and Vmax values show a greater range: in a gel-state matrix, diheptanoyl-PC is hydrolyzed with micellelike kinetic parameters; in a liquid-crystalline matrix, the short-chain lecithin becomes comparable to the long-chain component. Both enzymes also show an anomalous increase in specific activity toward diheptanoyl-PC around the phase transition temperature of the long-chain phospholipid. Since the short-chain lecithin does not exhibit a phase transition, this must reflect fluctuations in head-group area or vertical motions of the short-chain lecithin caused by surrounding long-chain lecithin molecules. These results are discussed in terms of a specific model for SLUV hydrolysis and a general explanation for the "interfacial activation" observed with water-soluble phospholipases.

Phospholipases A2: enzymatic assay for snake venom (Naja naja karachiensis) with their neutralization by medicinal plants of Pakistan.

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Asad, Muhammad H H B; Durr-E-Sabih; Yaqab, Tahir; Murtaza, Ghulam; Hussain, Muhammad S; Hussain, Muhammad S; Nasir, Muhammad T; Azhar, Saira; Khan, Shujaat A; Hussain, Izhar

2014-01-01

Phospholipases A2 (PLA2) are the most lethal and noxious component of Naja naja karachiensis venom. They are engaged to induce severe toxicities after their penetration in victims. Present study was designed to highlight hydrolytic actions of PLA. in an egg yolk mixture and to encounter their deleterious effects via medicinal plants of Pakistan. PLA2 were found to produce free fatty acids in a dose dependent manner. Venom at concentration of 0.1 mg was found to liberate 26.6 pmoles of fatty acids with a decline in pH1 of 0.2 owing to the presence of PLA2 (133 Unit/mg). When quantity of venom was increased up to 8 mg, it caused to release 133 pmoles of free fatty acids with a decrease in 1.0 pH due to abundance in PLA, (665 Unit/mg). The rest of other doses of venom (0.3-4.0 mg) was found to liberate fatty acids between these two upper and lower limits. Twenty eight medicinal plants (0.1-0.6 mg) were tried to abort PLA, hydrolytic action, however, all were found useful (50-100%) against PLA,. Bauhinia variegate L., Citrus limon (L.). Burm.f. Enicostemnma hyssopifolium (Willd.) Verdoorn, Ocimum sanctum. Psoralea corylifolia L. and Stenolobium stans (L.) D. Don were found excellent in switching off 100% phospholipases A, at their lowest concentration (0.1 mg). Three plants extract were found useful only at lower concentration (0.1 mg), however, their higher doses were seemed to aggravate venom response. Eight medicinal plants failed to neutralize PLA, rather their higher doses were found effective. Standard antidote and rest of other plants extract were able to show maximum of 50% efficiencies. Therefore, it is necessary to identify and isolate bioactive constituent(s) from above cited six medicinal plants to eradicate the problem of snake bite in the future.

Functional analysis of two PLA2G2A variants associated with secretory phospholipase A2-IIA levels.

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Holly J Exeter

Full Text Available Secretory phospholipase A2 group IIA (sPLA2-IIA has been identified as a biomarker of atherosclerosis in observational and animal studies. The protein is encoded by the PLA2G2A gene and the aim of this study was to test the functionality of two PLA2G2A non-coding SNPs, rs11573156 C>G and rs3767221 T>G where the rare alleles have been previously associated with higher and lower sPLA2-IIA levels respectively.Luciferase assays, electrophoretic mobility shift assays (EMSA, and RNA expression by RT-PCR were used to examine allelic differences. For rs3767221 the G allele showed ∼55% lower luciferase activity compared to the T allele (T = 62.1 (95% CI 59.1 to 65.1 G = 27.8 (95% CI 25.0 to 30.6, p = 1.22×10⁻³⁵, and stronger EMSA binding of a nuclear protein compared to the T-allele. For rs11573156 C >G there were no luciferase or EMSA allelic differences seen. In lymphocyte cell RNA, from individuals of known rs11573156 genotype, there was no allelic RNA expression difference for exons 5 and 6, but G allele carriers (n = 7 showed a trend to lower exon 1-2 expression compared to CC individuals. To take this further, in the ASAP study (n = 223, an rs11573156 proxy (r² = 0.91 showed ∼25% higher liver expression of PLA2G2A (1.67×10⁻¹⁷ associated with the G allele. However, considering exon specific expression, the association was greatly reduced for exon 2 (4.5×10⁻⁵ compared to exons 3-6 (10⁻¹⁰ to 10⁻²⁰, suggesting rs11573156 G allele-specific exon 2 skipping.Both SNPs are functional and provide useful tools for Mendelian Randomisation to determine whether the relationship between sPLA2-IIA and coronary heart disease is causal.

Alopecia in a viable phospholipase C delta 1 and phospholipase C delta 3 double mutant.

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Fabian Runkel

Full Text Available BACKGROUND: Inositol 1,4,5trisphosphate (IP(3 and diacylglycerol (DAG are important intracellular signalling molecules in various tissues. They are generated by the phospholipase C family of enzymes, of which phospholipase C delta (PLCD forms one class. Studies with functional inactivation of Plcd isozyme encoding genes in mice have revealed that loss of both Plcd1 and Plcd3 causes early embryonic death. Inactivation of Plcd1 alone causes loss of hair (alopecia, whereas inactivation of Plcd3 alone has no apparent phenotypic effect. To investigate a possible synergy of Plcd1 and Plcd3 in postnatal mice, novel mutations of these genes compatible with life after birth need to be found. METHODOLOGY/PRINCIPAL FINDINGS: We characterise a novel mouse mutant with a spontaneously arisen mutation in Plcd3 (Plcd3(mNab that resulted from the insertion of an intracisternal A particle (IAP into intron 2 of the Plcd3 gene. This mutation leads to the predominant expression of a truncated PLCD3 protein lacking the N-terminal PH domain. C3H mice that carry one or two mutant Plcd3(mNab alleles are phenotypically normal. However, the presence of one Plcd3(mNab allele exacerbates the alopecia caused by the loss of functional Plcd1 in Del(9olt1Pas mutant mice with respect to the number of hair follicles affected and the body region involved. Mice double homozygous for both the Del(9olt1Pas and the Plcd3(mNab mutations survive for several weeks and exhibit total alopecia associated with fragile hair shafts showing altered expression of some structural genes and shortened phases of proliferation in hair follicle matrix cells. CONCLUSIONS/SIGNIFICANCE: The Plcd3(mNab mutation is a novel hypomorphic mutation of Plcd3. Our investigations suggest that Plcd1 and Plcd3 have synergistic effects on the murine hair follicle in specific regions of the body surface.

Ca2+-mobilizing agonists increase mitochondrial ATP production to accelerate cytosolic Ca2+ removal: aberrations in human complex I deficiency.

NARCIS (Netherlands)

Visch, H.J.; Koopman, W.J.H.; Zeegers, D.; Emst-de Vries, S.E. van; Kuppeveld, F.J.M. van; Heuvel, L.W. van den; Smeitink, J.A.M.; Willems, P.H.G.M.

2006-01-01

Previously, we reported that both the bradykinin (Bk)-induced increase in mitochondrial ATP concentration ([ATP]M) and the rate of cytosolic Ca2+ removal are significantly decreased in skin fibroblasts from a patient with an isolated complex I deficiency. Here we demonstrate that the mitochondrial

Lipoprotein-Associated Phospholipase A2 Mass Level Is Increased in Elderly Subjects with Type 2 Diabetes Mellitus

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J. Fortunato

2014-01-01

Full Text Available Objective. Lipoprotein-associated phospholipase A2 (Lp-PLA2 is extensively expressed by advanced atherosclerotic lesions and may play a role in plaque instability. We selected a group of elderly subjects that underwent transcatheter aortic valve implantation (TAVI or balloon angioplasty (BA and separated them into two groups, diabetic and nondiabetic, to compare the level of Lp-PLA2 mass between them. Methods. 44 patients aged 79.6±5.6 years with symptomatic severe aortic valve stenosis underwent TAVI (n=35 or BA (n=9. 21 subjects had confirmed type 2 diabetes mellitus. Lp-PLA2 mass was measured using an enzyme-linked immunosorbent assay kit (USCN Life Science, China before and 3 days after the procedure. Results. Lp-PLA2 mass was significantly elevated in this population (1296±358 ng/mL before TAVI; 1413±268 ng/mL before BA and further increased after TAVI (1604±437 ng/mL, P<0.01 or BA (1808±303 ng/mL, P<0.01. Lp-PLA2 mass was significantly increased on the diabetic group before these interventions. Conclusion. Lp-PLA2 may be a novel biomarker for the presence of rupture-prone atherosclerotic lesions in elderly patients. Levels of Lp-PLA2 in diabetic patients may accompany the higher amount of small dense LDL particles seen in these subjects.

Structure-Guided Discovery of Novel, Potent, and Orally Bioavailable Inhibitors of Lipoprotein-Associated Phospholipase A2.

Science.gov (United States)

Liu, Qiufeng; Huang, Fubao; Yuan, Xiaojing; Wang, Kai; Zou, Yi; Shen, Jianhua; Xu, Yechun

2017-12-28

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a promising therapeutic target for atherosclerosis, Alzheimer's disease, and diabetic macular edema. Here we report the identification of novel sulfonamide scaffold Lp-PLA2 inhibitors derived from a relatively weak fragment. Similarity searching on this fragment followed by molecular docking leads to the discovery of a micromolar inhibitor with a 300-fold potency improvement. Subsequently, by the application of a structure-guided design strategy, a successful hit-to-lead optimization was achieved and a number of Lp-PLA2 inhibitors with single-digit nanomolar potency were obtained. After preliminary evaluation of the properties of drug-likeness in vitro and in vivo, compound 37 stands out from this congeneric series of inhibitors for good inhibitory activity and favorable oral bioavailability in male Sprague-Dawley rats, providing a quality candidate for further development. The present study thus clearly demonstrates the power and advantage of integrally employing fragment screening, crystal structures determination, virtual screening, and medicinal chemistry in an efficient lead discovery project, providing a good example for structure-based drug design.

Isolation and Functional Characterization of an Acidic Myotoxic Phospholipase A2 from Colombian Bothrops asper Venom

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Silvia Posada Arias

2017-10-01

Full Text Available Myotoxic phospholipases A2 (PLA2 are responsible for many clinical manifestations in envenomation by Bothrops snakes. A new myotoxic acidic Asp49 PLA2 (BaCol PLA2 was isolated from Colombian Bothrops asper venom using reverse-phase high performance liquid chromatography (RP-HPLC. BaCol PLA2 had a molecular mass of 14,180.69 Da (by mass spectrometry and an isoelectric point of 4.4. The complete amino acid sequence was obtained by cDNA cloning (GenBank accession No. MF319968 and revealed a mature product of 124 amino acids with Asp at position 49. BaCol PLA2 showed structural homology with other acidic PLA2 isolated from Bothrops venoms, including a non-myotoxic PLA2 from Costa Rican B. asper. In vitro studies showed cell membrane damage without exposure of phosphatidylserine, an early apoptosis hallmark. BaCol PLA2 had high indirect hemolytic activity and moderate anticoagulant action. In mice, BaCol PLA2 caused marked edema and myotoxicity, the latter seen as an increase in plasma creatine kinase and histological damage to gastrocnemius muscle fibers that included vacuolization and hyalinization necrosis of the sarcoplasm.

Design of group IIA secreted/synovial phospholipase A(2 inhibitors: an oxadiazolone derivative suppresses chondrocyte prostaglandin E(2 secretion.

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Jean-Edouard Ombetta

Full Text Available Group IIA secreted/synovial phospholipase A(2 (GIIAPLA(2 is an enzyme involved in the synthesis of eicosanoids such as prostaglandin E(2 (PGE(2, the main eicosanoid contributing to pain and inflammation in rheumatic diseases. We designed, by molecular modeling, 7 novel analogs of 3-{4-[5(indol-1-ylpentoxy]benzyl}-4H-1,2,4-oxadiazol-5-one, denoted C1, an inhibitor of the GIIAPLA(2 enzyme. We report the results of molecular dynamics studies of the complexes between these derivatives and GIIAPLA(2, along with their chemical synthesis and results from PLA(2 inhibition tests. Modeling predicted some derivatives to display greater GIIAPLA(2 affinities than did C1, and such predictions were confirmed by in vitro PLA(2 enzymatic tests. Compound C8, endowed with the most favorable energy balance, was shown experimentally to be the strongest GIIAPLA(2 inhibitor. Moreover, it displayed an anti-inflammatory activity on rabbit articular chondrocytes, as shown by its capacity to inhibit IL-1beta-stimulated PGE(2 secretion in these cells. Interestingly, it did not modify the COX-1 to COX-2 ratio. C8 is therefore a potential candidate for anti-inflammatory therapy in joints.

Enhanced Phospholipase A2 Group 3 Expression by Oxidative Stress Decreases the Insulin-Degrading Enzyme

Science.gov (United States)

Yui, Daishi; Nishida, Yoichiro; Nishina, Tomoko; Mogushi, Kaoru; Tajiri, Mio; Ishibashi, Satoru; Ajioka, Itsuki; Ishikawa, Kinya; Mizusawa, Hidehiro; Murayama, Shigeo; Yokota, Takanori

2015-01-01

Oxidative stress has a ubiquitous role in neurodegenerative diseases and oxidative damage in specific regions of the brain is associated with selective neurodegeneration. We previously reported that Alzheimer disease (AD) model mice showed decreased insulin-degrading enzyme (IDE) levels in the cerebrum and accelerated phenotypic features of AD when crossbred with alpha-tocopherol transfer protein knockout (Ttpa -/-) mice. To further investigate the role of chronic oxidative stress in AD pathophysiology, we performed DNA microarray analysis using young and aged wild-type mice and aged Ttpa -/- mice. Among the genes whose expression changed dramatically was Phospholipase A2 group 3 (Pla2g3); Pla2g3 was identified because of its expression profile of cerebral specific up-regulation by chronic oxidative stress in silico and in aged Ttpa -/- mice. Immunohistochemical studies also demonstrated that human astrocytic Pla2g3 expression was significantly increased in human AD brains compared with control brains. Moreover, transfection of HEK293 cells with human Pla2g3 decreased endogenous IDE expression in a dose-dependent manner. Our findings show a key role of Pla2g3 on the reduction of IDE, and suggest that cerebrum specific increase of Pla2g3 is involved in the initiation and/or progression of AD. PMID:26637123

Enhanced Phospholipase A2 Group 3 Expression by Oxidative Stress Decreases the Insulin-Degrading Enzyme.

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Daishi Yui

Full Text Available Oxidative stress has a ubiquitous role in neurodegenerative diseases and oxidative damage in specific regions of the brain is associated with selective neurodegeneration. We previously reported that Alzheimer disease (AD model mice showed decreased insulin-degrading enzyme (IDE levels in the cerebrum and accelerated phenotypic features of AD when crossbred with alpha-tocopherol transfer protein knockout (Ttpa-/- mice. To further investigate the role of chronic oxidative stress in AD pathophysiology, we performed DNA microarray analysis using young and aged wild-type mice and aged Ttpa-/- mice. Among the genes whose expression changed dramatically was Phospholipase A2 group 3 (Pla2g3; Pla2g3 was identified because of its expression profile of cerebral specific up-regulation by chronic oxidative stress in silico and in aged Ttpa-/- mice. Immunohistochemical studies also demonstrated that human astrocytic Pla2g3 expression was significantly increased in human AD brains compared with control brains. Moreover, transfection of HEK293 cells with human Pla2g3 decreased endogenous IDE expression in a dose-dependent manner. Our findings show a key role of Pla2g3 on the reduction of IDE, and suggest that cerebrum specific increase of Pla2g3 is involved in the initiation and/or progression of AD.

Localization of age-related macular degeneration-associated ARMS2 in cytosol, not mitochondria

Science.gov (United States)

Wang, Gaofeng; Spencer, Kylee L.; Court, Brenda L.; Olson, Lana M.; Scott, William K.; Haines, Jonathan L.; Pericak-Vance, Margaret A.

2010-01-01

PURPOSE To analyze the relationship between ARMS2 and HTRA1 in the association with age-related macular degeneration (AMD) in an independent case-control dataset, and to investigate the subcellular localization of the ARMS2 protein in an in vitro system. METHOD Two SNPs in ARMS2 and HTRA1 were genotyped in 685 cases and 269 controls by Taqman Assay. Allelic association was tested by a χ2 test. A likelihood ratio test (LRT) of full vs. reduced models was utilized to analyze the interaction between ARMS2 and smoking and HTRA1 and smoking, after adjusting for CFH and age. Immunofluorescence and immunoblot were applied to localize ARMS2 in retinal epithelial ARPE-19 cells and COS7 cell transfected by ARMS2 constructs. RESULT Both significantly associated SNP rs10490924 and rs11200638 (P<0.0001) are in strong linkage disequilibrium (LD) (D′=0.97, r2=0.93) that generates virtually identical association test and odds ratios. In separate logistic regression models the interaction effect for both smoking with ARMS2 and with HTRA1 was not statistically significant. Immunofluorescence and immunoblot show that both endogenous and exogenous ARMS2 are mainly distributed in the cytosol, not the mitochondria. Comparing to wild type, ARMS2 A69S is more likely to be associated with cytoskeleton in COS7 cells. CONCLUSIONS The significant associations in ARMS2 and HTRA1 are with polymorphisms in strong LD that confer virtually identical risks, preventing differentiation at the statistical level. We found that ARMS2 was mainly distributed in the cytosol, not in mitochondrial outer membrane as previously reported, suggesting that ARMS2 may not confer risk to AMD through the mitochondrial pathway. PMID:19255159

A One Pot Synthesis of Novel Bioactive Tri-Substitute-Condensed-Imidazopyridines that Targets Snake Venom Phospholipase A2

Science.gov (United States)

Anilkumar, Nirvanappa C.; Sundaram, Mahalingam S.; Mohan, Chakrabhavi Dhananjaya; Rangappa, Shobith; Bulusu, Krishna C.; Fuchs, Julian E.; Girish, Kesturu S.; Bender, Andreas; Basappa; Rangappa, Kanchugarakoppal S.

2015-01-01

Drugs such as necopidem, saripidem, alpidem, zolpidem, and olprinone contain nitrogen-containing bicyclic, condensed-imidazo[1,2-α]pyridines as bioactive scaffolds. In this work, we report a high-yield one pot synthesis of 1-(2-methyl-8-aryl-substitued-imidazo[1,2-α]pyridin-3-yl)ethan-1-onefor the first-time. Subsequently, we performed in silico mode-of-action analysis and predicted that the synthesized imidazopyridines targets Phospholipase A2 (PLA2). In vitro analysis confirmed the predicted target PLA2 for the novel imidazopyridine derivative1-(2-Methyl-8-naphthalen-1-yl-imidazo [1,2-α]pyridine-3-yl)-ethanone (compound 3f) showing significant inhibitory activity towards snake venom PLA2 with an IC50 value of 14.3 μM. Evidently, the molecular docking analysis suggested that imidazopyridine compound was able to bind to the active site of the PLA2 with strong affinity, whose affinity values are comparable to nimesulide. Furthermore, we estimated the potential for oral bioavailability by Lipinski's Rule of Five. Hence, it is concluded that the compound 3f could be a lead molecule against snake venom PLA2. PMID:26196520

A One Pot Synthesis of Novel Bioactive Tri-Substitute-Condensed-Imidazopyridines that Targets Snake Venom Phospholipase A2.

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Nirvanappa C Anilkumar

Full Text Available Drugs such as necopidem, saripidem, alpidem, zolpidem, and olprinone contain nitrogen-containing bicyclic, condensed-imidazo[1,2-α]pyridines as bioactive scaffolds. In this work, we report a high-yield one pot synthesis of 1-(2-methyl-8-aryl-substitued-imidazo[1,2-α]pyridin-3-ylethan-1-onefor the first-time. Subsequently, we performed in silico mode-of-action analysis and predicted that the synthesized imidazopyridines targets Phospholipase A2 (PLA2. In vitro analysis confirmed the predicted target PLA2 for the novel imidazopyridine derivative1-(2-Methyl-8-naphthalen-1-yl-imidazo [1,2-α]pyridine-3-yl-ethanone (compound 3f showing significant inhibitory activity towards snake venom PLA2 with an IC50 value of 14.3 μM. Evidently, the molecular docking analysis suggested that imidazopyridine compound was able to bind to the active site of the PLA2 with strong affinity, whose affinity values are comparable to nimesulide. Furthermore, we estimated the potential for oral bioavailability by Lipinski's Rule of Five. Hence, it is concluded that the compound 3f could be a lead molecule against snake venom PLA2.

Insulin stimulates phospholipase D-dependent phosphatidylcholine hydrolysis, Rho translocation, de novo phospholipid synthesis, and diacylglycerol/protein kinase C signaling in L6 myotubes.

Science.gov (United States)

Standaert, M L; Bandyopadhyay, G; Zhou, X; Galloway, L; Farese, R V

1996-07-01

Previous studies have provided conflicting findings on whether insulin activates certain, potentially important, phospholipid signaling systems in skeletal muscle preparations. In particular, insulin effects on the hydrolysis of phosphatidylcholine (PC) and subsequent activation of protein kinase C (PKC) have not been apparent in some studies. Presently, we examined insulin effects on phospholipid signaling systems, diacylglycerol (DAG) production, and PKC translocation/activation in L6 myotubes. We found that insulin provoked rapid increases in phospholipase D (PLD)-dependent hydrolysis of PC, as evidenced by increases in choline release and phosphatidylethanol production in cells incubated in the presence of ethanol. In association with PC-PLD activation, Rho, a small G protein that is known to activate PC-PLD activation, translocated from the cytosol to the membrane fraction in response to insulin treatment. PC-PLD activation was also accompanied by increases in total DAG production and increases in the translocation of both PKC enzyme activity and DAG-sensitive PKC-alpha, -beta, -delta, and -epsilon from the cytosol to the membrane fraction. A potential role for PKC or a related protein kinase in insulin action was suggested by the finding that RO 31-8220 inhibited both PKC enzyme activity and insulin-stimulated [3H]2-deoxyglucose uptake. Our findings provide the first evidence that insulin stimulates Rho translocation and activates PC-PLD in L6 skeletal muscle cells. Moreover, this signaling system appears to lead to increases in DAG/PKC signaling, which, along with other related signaling factors, may regulate certain metabolic processes, such as glucose transport, in these cells.

Crystallization and preliminary X-ray diffraction analysis of a Lys49-phospholipase A2 complexed with caffeic acid, a molecule with inhibitory properties against snake venoms

International Nuclear Information System (INIS)

Shimabuku, Patrícia S.; Fernandes, Carlos A. H.; Magro, Angelo J.; Costa, Tássia R.; Soares, Andreimar M.; Fontes, Marcos R. M.

2011-01-01

Piratoxin I, a noncatalytic and myotoxic Lys49-phospholipase A 2 from B. pirajai venom, was cocrystallized with the inhibitor caffeic acid and a data set was collected to a resolution of 1.65 Å. The electron-density map unambiguously indicated that three inhibitor molecules interact with the C-terminus of the protein. Phospholipases A 2 (PLA 2 s) are one of the main components of bothropic venoms; in addition to their phospholipid hydrolysis action, they are involved in a wide spectrum of pharmacological activities, including neurotoxicity, myotoxicity and cardiotoxicity. Caffeic acid is an inhibitor that is present in several plants and is employed for the treatment of ophidian envenomations in the folk medicine of many developing countries; as bothropic snake bites are not efficiently neutralized by conventional serum therapy, it may be useful as an antivenom. In this work, the cocrystallization and preliminary X-ray diffraction analysis of the Lys49-PLA 2 piratoxin I from Bothrops pirajai venom in the presence of the inhibitor caffeic acid (CA) are reported. The crystals diffracted X-rays to 1.65 Å resolution and the structure was solved by molecular-replacement techniques. The electron-density map unambiguously indicated the presence of three CA molecules that interact with the C-terminus of the protein. This is the first time a ligand has been observed bound to this region and is in agreement with various experiments previously reported in the literature

Synthesis of Phosphatidylcholine Containing Highly Unsaturated Fatty Acid by Phospholipase A2 and Effect on Retinoic Acid Induced Differentiation of HL-60 Cells

OpenAIRE

細川, 雅史; 大島, 宏哲; 甲野, 裕之; 高橋, 是太郎; 羽田野, 六男; 小田島, 粛夫

1993-01-01

Phosphatidylcholine containing highly unsaturated fatty acid (HUFA-PC) was prepared by porcine pancreatic phospholipase A2, which catalyzed esterification between lysophosphatidylcholine (LPC) and highly unsaturated fatty acid (HUFA), under a scaled-up reaction system. Fatty acid mixture prepared from sardine oil, purified eicosapentaenoic acid (EPA), and purified docosahexaenoic acid (DHA) were used as the substrates of HUFA. The yield of HUFA-PC was 17.0-19.9%. Synthesized phosphatidylcholi...

Deposition of lipid, protein, and secretory phospholipase A2 on hydrophilic contact lenses.

Science.gov (United States)

Mochizuki, Hiroshi; Yamada, Masakazu; Hatou, Shin; Kawashima, Motoko; Hata, Seiichiro

2008-01-01

Recent studies have shown that low tear phospholipid levels are associated with tear film instability in hydrophilic contact lens wearers. The concentration of secretory phospholipase A2 (sPLA2), the enzyme that hydrolyzes phospholipids, in tears is known to exceed the levels found in serum by four orders of magnitude. This study was performed to determine the levels of sPLA2 from the deposition on two different frequent-replacement contact lens materials. Polymacon and etafilcon A contact lenses worn for 2 weeks by 16 experienced contact lens wearers were used for the analysis. Total lipids were determined by the sulfo-phospho-vanillin reaction. Phospholipids in lipid extracts were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Total protein was measured by bicinchoninic acid analysis. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine sPLA2 concentrations. Total lipid deposition was found to be greater in the polymacon group (66.3+/-16.3 microg/lens) than in the etafilcon A group, although phospholipids were not detected in either group. The etafilcon A group had greater deposition of protein (3.7+/-0.7 mg/lens) than the polymacon group had. The etafilcon A group deposited statistically significantly more group IIa sPLA2 (1.1+/-0.3 microg/lens) than the polymacon group (0.07+/-0.04 microg/lens) did (P<0.001). There was a significant difference in the lipid and protein deposition profiles in the two lenses tested. A significant amount of sPLA2 in the deposition on contact lenses may play a role in tear film instability in hydrophilic contact lens wearers.

Cytosolic delivery of materials with endosome-disrupting colloids

Science.gov (United States)

Helms, Brett A.; Bayles, Andrea R.

2016-03-15

A facile procedure to deliver nanocrystals to the cytosol of live cells that is both rapid and general. The technique employs a unique cationic core-shell polymer colloid that directs nanocrystals to the cytosol of living cells within a few hours of incubation. The present methods and compositions enable a host of advanced applications arising from efficient cytosolic delivery of nanocrystal imaging probes: from single particle tracking experiments to monitoring protein-protein interactions in live cells for extended periods.

Effect of phospholipase A treatment of low density lipoproteins on the dextran sulfate--lipoprotein interaction.

Science.gov (United States)

Nishida, T

1968-09-01

The effect of phospholipase A on the interaction of low density lipoproteins of the S(f) 0-10 class with dextran sulfate was studied in phosphate buffer of pH 7.4, ionic strength 0.1, by chemical, spectrophotometric, and centrifugal methods. When low density lipoproteins that had been treated with phospholipase A were substituted for untreated lipoproteins, the amount of insoluble dextran sulfate-lipoprotein complex formed was greatly reduced. Hydrolysis of over 20% of the lecithin and phosphatidyl ethanolamine constituents of the lipoproteins prevented the formation of insoluble complex. However, even the lipoproteins in which almost all the phosphoglycerides were hydrolyzed produced soluble complex, which was converted to insoluble complex upon addition of magnesium sulfate. It is apparent that the lipoproteins altered extensively by treatment with phospholipase A retain many characteristic properties of native low density lipoproteins. Fatty acids, but not lysolecithin, released by the action of phospholipase A interfered with the formation of insoluble complex; this interference was due to association of the fatty acids with the lipoproteins. With increases in the concentration of the associated fatty acids, the amounts of magnesium ion required for the conversion of soluble complex to insoluble complex increased progressively. Charge interaction is evidently of paramount importance in the formation of sulfated polysaccharide-lipoprotein complexes.

Cytosolic labile zinc: a marker for apoptosis in the developing rat brain.

Science.gov (United States)

Lee, Joo-Yong; Hwang, Jung Jin; Park, Mi-Ha; Koh, Jae-Young

2006-01-01

Cytosolic zinc accumulation was thought to occur specifically in neuronal death (necrosis) following acute injury. However, a recent study demonstrated that zinc accumulation also occurs in adult rat neurons undergoing apoptosis following target ablation, and in vitro experiments have shown that zinc accumulation may play a causal role in various forms of apoptosis. Here, we examined whether intraneuronal zinc accumulation occurs in central neurons undergoing apoptosis during development. Embryonic and newborn Sprague-Dawley rat brains were double-stained for terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) detection of apoptosis and immunohistochemical detection of stage-specific neuronal markers, such as nestin, proliferating cell nuclear antigen (PCNA), TuJ1 and neuronal nuclear specific protein (NeuN). The results revealed that apoptotic cell death occurred in neurons of diverse stages (neural stem cells, and dividing, young and adult neurons) throughout the brain during the embryonic and early postnatal periods. Further staining of brain sections with acid fuchsin or zinc-specific fluorescent dyes showed that all of the apoptotic neurons were acidophilic and contained labile zinc in their cell bodies. Cytosolic zinc accumulation was also observed in cultured cortical neurons undergoing staurosporine- or sodium nitroprusside (SNP)-induced apoptosis. In contrast, zinc chelation with CaEDTA or N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) reduced SNP-induced apoptosis but not staurosporine-induced apoptosis, indicating that cytosolic zinc accumulation does not play a causal role in all forms of apoptosis. Finally, the specific cytosolic zinc accumulation may have a practical application as a relatively simple marker for neurons undergoing developmental apoptosis.

Human interleukin 1β stimulates islet insulin release by a mechanism not dependent on changes in phospholipase C and protein kinase C activities or Ca2+ handling

International Nuclear Information System (INIS)

Welsh, N.; Nilsson, T.; Hallberg, A.; Arkhammar, P.; Berggren, P.-O.; Sandler, S.

1989-01-01

Isolated islets from adult rats or obese hyperglycemic (ob/ob) mice were incubated with human recombinant interleukin 1β in order to study whether the acute effects of the cytokine on islet insulin release are associated with changes in islet phospholipase C activity, Ca 2+ handling or protein phosphorylation. The cytokine stimulated insulin release both at low and high glucose concentrations during one hour incubations. In shortterm incubations ( 2+ concentration at rest nor that observed subsequent to stimulation with a high concentration of glucose. Furthermore, the endogenous protein kinase C activity, as visualized by immunoprecipitation of a 32 P-labelled substrate for this enzyme, was not altered by interleukin 1β. Separation of 32 P-labelled proteins by means of 2-dimensional gel electrophoresis failed to reveal any specific effects of the cytokine on the total protein phosphorylation activity. These results suggest that the stimulatory effects on insulin release exerted by interleukin 1β are not caused by acute activation of phospholipase C and protein kinase C or by an alternation of islet Ca 2+ handling of the B-cells. (author)

Activation of H2O2-induced VSOR Cl- currents in HTC cells require phospholipase Cgamma1 phosphorylation and Ca2+ mobilisation

DEFF Research Database (Denmark)

Varela, Diego; Simon, Felipe; Olivero, Pablo

2007-01-01

)R) blocker 2-APB. In line with these results, manoeuvres that prevented PLCgamma1 activation and/or [Ca(2+)](i) rise, abolished H(2)O(2)-induced VSOR Cl(-) currents. Furthermore, in cells that overexpress a phosphorylation-defective dominant mutant of PLCgamma1, H(2)O(2) did not induce activation......Volume-sensitive outwardly rectifying (VSOR) Cl(-) channels participate in several physiological processes such as regulatory volume decrease, cell cycle regulation, proliferation and apoptosis. Recent evidence points to a significant role of hydrogen peroxide (H(2)O(2)) in VSOR Cl(-) channel...... activation. The aim of this study was to determine the signalling pathways responsible for H(2)O(2)-induced VSOR Cl(-) channel activation. In rat hepatoma (HTC) cells, H(2)O(2) elicited a transient increase in tyrosine phosphorylation of phospholipase Cgamma1 (PLCgamma1) that was blocked by PP2, a Src...

Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications.

Science.gov (United States)

Borrelli, Grazia M; Trono, Daniela

2015-09-01

Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes.

Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications

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Grazia M. Borrelli

2015-09-01

Full Text Available Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes.

Static magnetic field changes the activity of venom phospholipase of Vipera Lebetina snakes

International Nuclear Information System (INIS)

Garibova, L.S.; Avetisyan, T.O.; Ajrapetyan, S.N.

2000-01-01

The effect of the static magnetic field (SMF) on the phospholipid activity of the class-A snake venom is studied. The Vipera Lebetina snake venom was subjected during 10 days to 30 minute impact of the CMF daily. It is established that increase in the phospholipase A 1 and A 2 approximately by 21 and 32 % correspondingly and in the phosphodiesterase C - by 33 % was observed. The decrease in the total protein level of the snake venom by 31.6 ± 2.2 % was noted thereby. It may be assumed that the described phospholipase and phosphoesterase changes may lead to essential shifts in the total metabolic activity of cells and organism as a whole. The activity index of these ferments may serve as an indicator of changes in the environmental magnetic field [ru

The kinetics of the phospholipase A2-catalyzed hydrolysis of Egg phosphatidylcholine in unilamellar vesicles. Product inhibition and its relief by serum albumin.

Science.gov (United States)

Kupferberg, J P; Yokoyama, S; Kézdy, F J

1981-06-25

Only the lecithin in the outer leaflet (representing 70% of the total) of egg lecithin unilamellar vesicles is hydrolyzed by Crotalus atrox phospholipase A2. Hydrolyzed vesicles remain intact and impermeable to ionic solutes. The fatty acids produced in the hydrolysis remain on the vesicle and are only partially ionized at neutral pH due to electrostatic repulsions. About 40% of the lysolecithin product is desorbed from the vesicle. In the presence of a large excess of bovine serum albumin, the reaction is first order with respect to both the enzyme and the substrate. At 21 degrees C, pH 7.2, I = 0.16 M, and [Ca2+] = 7 mM, the second order rate constant is kex(2) = 1.5 X 10(6) M-1 s-1. In the absence of albumin, the reaction is inhibited competitively by both the monomeric (KIm = 4.5 X 10(-8) M) and micellar (nKIa = 3.7 X 10(-7) M) forms of lysolecithin ([critical micelle concentration] = 4.3 X 10(-6) M). Bovine serum albumin complexes two molecules of lysolecithin with a dissociation constant, Kb = 5 X 10(-8) M. With substoichiometric albumin, the reaction is biphasic, and, when the albumin is saturated with lysolecithin, the kinetics become similar to those observed in the absence of albumin. The action of phospholipase A2 shows that in unilamellar vesicles there is only one major lecithin conformation in the outer leaflet, or that all conformations are rapidly interconvertible.

Phospholipase A2 is involved in galactosylsphingosine-induced astrocyte toxicity, neuronal damage and demyelination.

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Cedric Misslin

Full Text Available Krabbe disease is a fatal rare inherited lipid storage disorder affecting 1:100,000 births. This illness is caused by mutations in the galc gene encoding for the enzyme galactosylceramidase (GALC. Dysfunction of GALC has been linked to the toxic build-up of the galactolipid, galactosylsphingosine (psychosine, which induces cell death of oligodendrocytes. Previous studies show that phospholipase A2 (PLA2 may play a role in psychosine induce cell death. Here, we demonstrate that non-selective inhibition of cPLA2/sPLA2 and selective inhibition of cPLA2, but not sPLA2, also attenuates psychosine-induced cell death of human astrocytes. This study shows that extracellular calcium is required for psychosine induced cell death, but intracellular calcium release, reactive oxygen species or release of soluble factors are not involved. These findings suggest a cell autonomous effect, at least in human astrocytes. Supporting a role for PLA2 in psychosine-induced cell death of oligodendrocytes and astrocytes, the results show inhibition of PLA2 attenuates psychosine-induced decrease in the expression of astrocyte marker vimentin as well as myelin basic protein (MBP, myelin oligodendrocyte glycoprotein (MOG and the neuronal marker SMI-32 in organotypic slice cultures. These findings provide further mechanistic details of psychosine-induced death of glia and suggest a role for PLA2 in the process. This work also supports the proposal that novel drugs for Krabbe disease may require testing on astrocytes as well as oligodendrocytes for more holistic prediction of pre-clinical and clinical efficacy.

Characterization of antigen association with accessory cells: specific removal of processed antigens from the cell surface by phospholipases

International Nuclear Information System (INIS)

Falo, L.D. Jr.; Haber, S.I.; Herrmann, S.; Benacerraf, B.; Rock, K.L.

1987-01-01

To characterize the basis for the cell surface association of processed antigen with the antigen-presenting cell (APC) the authors analyzed its sensitivity to enzymatic digestion. Antigen-exposed APC that are treated with phospholipase and then immediately fixed lose their ability to stimulate antigen-plus-Ia-specific T-T hybridomas. This effect is seen with highly purified phospholipase A 2 and phospholipase C. In addition it is observed with three distinct antigens - ovalbumin, bovine insulin, and poly(LGlu 56 LLys 35 LPhe 9 )[(GluLysPhe)/sub n/]. The effect of phospholipases is highly specific. Identically treated APC are equivalent to control in their ability to stimulate alloreactive hybridomas specific for precisely the same Ia molecule that is corecognized by antigen-plus-Ia-specific hybrids. Furthermore, the antigen-presenting function of enzyme-treated, fixed APC can be reconstituted by the addition of exogenous in vitro processed or processing independent antigens. In parallel studies 125 I-labeled avidin was shown to specifically bind to APC that were previously exposed and allowed to process biotin-insulin. Biotin-insulin-exposed APC that are pretreated with phospholipase bind significantly less 125 I-labeled avidin than do untreated, exposed APC. Identical enzyme treatment does not reduce the binding of avidin to a biotinylated antibody already bound to class II major histocompatibility complex molecules of APC. These studies demonstrate that phospholipase effectively removes processed cell surface antigen

Cytosolic PrP Can Participate in Prion-Mediated Toxicity

Science.gov (United States)

Thackray, Alana M.; Zhang, Chang; Arndt, Tina

2014-01-01

ABSTRACT Prion diseases are characterized by a conformational change in the normal host protein PrPC. While the majority of mature PrPC is tethered to the plasma membrane by a glycosylphosphatidylinositol anchor, topological variants of this protein can arise during its biosynthesis. Here we have generated Drosophila transgenic for cytosolic ovine PrP in order to investigate its toxic potential in flies in the absence or presence of exogenous ovine prions. While cytosolic ovine PrP expressed in Drosophila was predominantly detergent insoluble and showed resistance to low concentrations of proteinase K, it was not overtly detrimental to the flies. However, Drosophila transgenic for cytosolic PrP expression exposed to classical or atypical scrapie prion inocula showed a faster decrease in locomotor activity than similar flies exposed to scrapie-free material. The susceptibility to classical scrapie inocula could be assessed in Drosophila transgenic for panneuronal expression of cytosolic PrP, whereas susceptibility to atypical scrapie required ubiquitous PrP expression. Significantly, the toxic phenotype induced by ovine scrapie in cytosolic PrP transgenic Drosophila was transmissible to recipient PrP transgenic flies. These data show that while cytosolic PrP expression does not adversely affect Drosophila, this topological PrP variant can participate in the generation of transmissible scrapie-induced toxicity. These observations also show that PrP transgenic Drosophila are susceptible to classical and atypical scrapie prion strains and highlight the utility of this invertebrate host as a model of mammalian prion disease. IMPORTANCE During prion diseases, the host protein PrPC converts into an abnormal conformer, PrPSc, a process coupled to the generation of transmissible prions and neurotoxicity. While PrPC is principally a glycosylphosphatidylinositol-anchored membrane protein, the role of topological variants, such as cytosolic PrP, in prion-mediated toxicity and

Crystallization and preliminary X-ray diffraction analysis of a class II phospholipase D from Loxosceles intermedia venom

International Nuclear Information System (INIS)

Ullah, Anwar; Giuseppe, Priscila Oliveira de; Murakami, Mario Tyago; Trevisan-Silva, Dilza; Wille, Ana Carolina Martins; Chaves-Moreira, Daniele; Gremski, Luiza Helena; Silveira, Rafael Bertoni da; Sennf-Ribeiro, Andrea; Chaim, Olga Meiri; Veiga, Silvio Sanches; Arni, Raghuvir Krishnaswamy

2011-01-01

Wild-type and H12A-mutant class II phospholipase D from L. intermedia venom were crystallized; the crystals diffracted to maximum resolutions of 1.95 and 1.60 Å, respectively. Phospholipases D are the major dermonecrotic component of Loxosceles venom and catalyze the hydrolysis of phospholipids, resulting in the formation of lipid mediators such as ceramide-1-phosphate and lysophosphatidic acid which can induce pathological and biological responses. Phospholipases D can be classified into two classes depending on their catalytic efficiency and the presence of an additional disulfide bridge. In this work, both wild-type and H12A-mutant forms of the class II phospholipase D from L. intermedia venom were crystallized. Wild-type and H12A-mutant crystals were grown under very similar conditions using PEG 200 as a precipitant and belonged to space group P12 1 1, with unit-cell parameters a = 50.1, b = 49.5, c = 56.5 Å, β = 105.9°. Wild-type and H12A-mutant crystals diffracted to maximum resolutions of 1.95 and 1.60 Å, respectively

Chloride concentrations in human hepatic cytosol and mitochondria are a function of age.

Science.gov (United States)

Jahn, Stephan C; Rowland-Faux, Laura; Stacpoole, Peter W; James, Margaret O

2015-04-10

We recently reported that, in a concentration-dependent manner, chloride protects hepatic glutathione transferase zeta 1 from inactivation by dichloroacetate, an investigational drug used in treating various acquired and congenital metabolic diseases. Despite the importance of chloride ions in normal physiology, and decades of study of chloride transport across membranes, the literature lacks information on chloride concentrations in animal tissues other than blood. In this study we measured chloride concentrations in human liver samples from male and female donors aged 1 day to 84 years (n = 97). Because glutathione transferase zeta 1 is present in cytosol and, to a lesser extent, in mitochondria, we measured chloride in these fractions by high-performance liquid chromatography analysis following conversion of the free chloride to pentafluorobenzylchloride. We found that chloride concentration decreased with age in hepatic cytosol but increased in liver mitochondria. In addition, chloride concentrations in cytosol, (105.2 ± 62.4 mM; range: 24.7-365.7 mM) were strikingly higher than those in mitochondria (4.2 ± 3.8 mM; range 0.9-22.2 mM). These results suggest a possible explanation for clinical observations seen in patients treated with dichloroacetate, whereby children metabolize the drug more rapidly than adults following repeated doses, and also provide information that may influence our understanding of normal liver physiology. Copyright © 2015 Elsevier Inc. All rights reserved.

In vitro inactivation of hepatic microsomal phospholipase A2 by the marine natural product manoalide

International Nuclear Information System (INIS)

Master, M.M.; Jacobs, R.S.

1986-01-01

The effects of manoalide (MLD) and several analogs (isolated from the sponge Luffariella variabilis) on mouse hepatic microsomal phospholipase A 2 (PLA 2 ) activity was investigated. Microsomal PLA 2 , a membrane bound, Ca ++ dependent enzyme with an alkaline pH optimum, functions in intracellular phospholipid turnover. In vitro PLA 2 activity was assayed by preincubating MLD or analogs (2.5-100μM) with microsomes for 60 min. at 37 0 C, combining this mixture with 14 C-phosphatidylcholine and CaCl 2 , and incubating at 37 0 C for 40 minutes. Enzyme activity was quantitated by measurement of the extracted 14 C-arachidonic acid product. MLD inhibited PLA 2 in a dose-dependent manner, with an IC 50 = 94μM. Lineweaver-Burk analysis suggests that MLD inhibits PLA 2 noncompetitively. One of the analogs, producing a comparable dose-response curve to MLD, was found to be more potent (IC 50 = 33μM). Another analog facilitated PLA 2 activity (15%) at 25μM, followed by inactivation at higher doses (IC 50 > 100 μM). Facilitation of PLA 2 activity was seen with concentrations as low as 2.5μM of a third analog, and significant inactivation of PLA 2 was evident. These results indicate that MLD is not as potent against microsomal PLA 2 as has been shown with purified bee venom and cobra venom PLA 2 's

Genetic association between the phospholipase A2 gene and unipolar affective disorder: a multicentre case-control study.

Science.gov (United States)

Papadimitriou, George N; Dikeos, Dimitris G; Souery, Daniel; Del-Favero, Jurgen; Massat, Isabelle; Avramopoulos, Dimitrios; Blairy, Sylvie; Cichon, Sven; Ivezic, Sladjana; Kaneva, Radka; Karadima, Georgia; Lilli, Roberta; Milanova, Vihra; Nöthen, Markus; Oruc, Lilijana; Rietschel, Marcella; Serretti, Alessandro; Van Broeckhoven, Christine; Stefanis, Costas N; Mendlewicz, Julien

2003-12-01

The co-segregation in one pedigree of bipolar affective disorder with Darier's disease whose gene is on chromosome 12q23-q24.1, and findings from linkage and association studies with the neighbouring gene of phospholipase A2 (PLA2) indicate that PLA2 may be considered as a candidate gene for affective disorders. All relevant genetic association studies, however, were conducted on bipolar patients. In the present study, the possible association between the PLA2 gene and unipolar affective disorder was examined on 321 unipolar patients and 604 controls (all personally interviewed), recruited from six countries (Belgium, Bulgaria, Croatia, Germany, Greece, and Italy) participating in the European Collaborative Project on Affective Disorders. After controlling for population group and gender, one of the eight alleles of the investigated marker (allele 7) was found to be more frequent among unipolar patients with more than three major depressive episodes than among controls (P<0.01); genotypic association was also observed, under the dominant model of genetic transmission (P<0.02). In addition, presence of allele 7 was correlated with a higher frequency of depressive episodes (P<0.02). These findings suggest that structural variations at the PLA2 gene or the chromosomal region around it may confer susceptibility for unipolar affective disorder.

Redox characteristics of the eukaryotic cytosol

DEFF Research Database (Denmark)

López-Mirabal, H Reynaldo; Winther, Jakob R

2007-01-01

The eukaryotic cytoplasm has long been regarded as a cellular compartment in which the reduced state of protein cysteines is largely favored. Under normal conditions, the cytosolic low-molecular weight redox buffer, comprising primarily of glutathione, is highly reducing and reactive oxygen species...... (ROS) and glutathionylated proteins are maintained at very low levels. In the present review, recent progress in the understanding of the cytosolic thiol-disulfide redox metabolism and novel analytical approaches to studying cytosolic redox properties are discussed. We will focus on the yeast model...... organism, Saccharomyces cerevisiae, where the combination of genetic and biochemical approaches has brought us furthest in understanding the mechanisms underlying cellular redox regulation. It has been shown in yeast that, in addition to the enzyme glutathione reductase, other mechanisms may exist...

Phospholipase A2 activity of the Persian Gulf upside-down jellyfish venom (Cassiopea andromeda

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Gholamhossean Mohebbi

2017-07-01

Full Text Available Background: The venomous jellyfish Cassiopea andromeda can produce envenomation and different toxicological and biological effects by their nematocysts. The phospholipase A2 enzymes (PLA2 are toxic and induce various pharmacological effects including neurotoxicity, myotoxicity and anticoagulant activities. The main aim of the current project was to screen the in vitro PLA2 activity of the C. andromeda crude venom. To better understand the experimental result; a molecular docking study was also performed. Materials and methods: The live specimens were collected from Nayband lagoon, by a trawl net, and separation of their tentacles was done according to Bloom 's et al., method. The PLA2 activity of crude venom was performed according to the acidimetric method of Tan and Tan. The lyophilized venom was subjected to Gas Chromatography/ Mass Spectroscopy, and the obtained structures were used for docking study against PLA2. The indoxam was considered as standard control. Results: The PLA2 activity of the jellyfish crude venom was 413 ±0.08 µmol/min/mg. Analysis of the crude venom detected seven compounds (i-vii using GC-MS. Docking data was also confirmed the experimental results. According to the docking results, the highest affinity (-6.7 (kcal/mol was observed in the compound “Pregn-5-ene-3,11-dione, 17,20:20,21 bis [methylenebis(oxy]-, cyclic 3-(1,2-ethane diyl acetal”. Conclusions: A high PLA2 level was found in the venom of C. andromeda. There was a good correlation between in vitro and in silico studies.

Isolation and characterization of bioactive compounds of Clematis gouriana Roxb. ex DC against snake venom phospholipase A2 (PLA2) computational and in vitro insights.

Science.gov (United States)

Muthusamy, Karthikeyan; Chinnasamy, Sathishkumar; Nagarajan, Subbiah; Sivaraman, Thirunavukkarasu; Chinnasamy, Selvakumar

2017-07-01

Bioactive compounds were isolated from Clematis gouriana Roxb. ex DC. The compounds were separated, characterized, the structures elucidated and submitted to the PubChem Database. The PubChem Ids SID 249494134 and SID 249494135 were tested against phospholipases A 2 (PLA 2 ) of Naja naja (Indian cobra) venom for PLA 2 activity. Both the compounds showed promising inhibitory activity; computational data also substantiated the results. The two compounds underwent density functional theory calculation to observe the chemical stability and electrostatic potential profile. Molecular interactions between the compounds and PLA 2 were observed at the binding pocket of the PLA 2 protein. Further, this protein-ligand complexes were simulated for a timescale of 100 ns of molecular dynamics simulation. Experimental and computational results showed significant PLA 2 inhibition activity.

Copper, Zinc Superoxide Dismutase is Primarily a Cytosolic Protein in Human Cells

Science.gov (United States)

Crapo, James D.; Oury, Tim; Rabouille, Catherine; Slot, Jan W.; Chang, Ling-Yi

1992-11-01

The intracellular localization of human copper, zinc superoxide dismutase (Cu,Zn-SOD; superoxide:superoxide oxidoreductase, EC 1.15.1.1) was evaluated by using EM immunocytochemistry and both isolated human cell lines and human tissues. Eight monoclonal antibodies raised against either native or recombinant human Cu,Zn-SOD and two polyclonal antibodies raised against either native or recombinant human Cu,Zn-SOD were used. Fixation with 2% paraformaldehyde/0.2% glutaraldehyde was found necessary to preserve normal distribution of the protein. Monoclonal antibodies were less effective than polyclonal antibodies in recognizing the antigen after adequate fixation of tissue. Cu,Zn-SOD was found widely distributed in the cell cytosol and in the cell nucleus, consistent with it being a soluble cytosolic protein. Mitochondria and secretory compartments did not label for this protein. In human cells, peroxisomes showed a labeling density slightly less than that of cytoplasm.

Phospholipase A₂: the key to reversing long-term memory impairment in a gastropod model of aging.

Science.gov (United States)

Watson, Shawn N; Wright, Natasha; Hermann, Petra M; Wildering, Willem C

2013-02-01

Memory failure associated with changes in neuronal circuit functions rather than cell death is a common feature of normal aging in diverse animal species. The (neuro)biological foundations of this phenomenon are not well understood although oxidative stress, particularly in the guise of lipid peroxidation, is suspected to play a key role. Using an invertebrate model system of age-associated memory impairment that supports direct correlation between behavioral deficits and changes in the underlying neural substrate, we show that inhibition of phospholipase A(2) (PLA(2)) abolishes both long-term memory (LTM) and neural defects observed in senescent subjects and subjects exposed to experimental oxidative stress. Using a combination of behavioral assessments and electrophysiological techniques, we provide evidence for a close link between lipid peroxidation, provocation of phospholipase A(2)-dependent free fatty acid release, decline of neuronal excitability, and age-related long-term memory impairments. This supports the view that these processes suspend rather than irreversibly extinguish the aging nervous system's intrinsic capacity for plasticity. Copyright © 2013 Elsevier Inc. All rights reserved.

Soybean phospholipase D activity determination. A comparison of two methods

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Ré, E.

2007-09-01

Full Text Available Due to a discrepancy between previously published results, two methods to determine the soybean phospholipase D activity were evaluated. One method is based on the extraction of the enzyme from whole soybean flour, quantifying the enzyme activity on the extract. The other method quantifies the enzymatic activity on whole soybean flour without enzyme extraction. In the extraction-based-method, both the extraction time and the number of extractions were optimized. The highest phospholipase D activity values were obtained from the method without enzyme extraction. This method is less complex, requires less running-time and the conditions of the medium in which phospholipase D acts resemble the conditions found in the oil industrySe evaluaron dos métodos para determinar la actividad de la fosfolipasa D en soja debido a que existe discrepancia entre los resultados publicados. Un método se basa en la extracción de la enzima de la harina resultante de la molienda del grano de soja entero, cuantificando la actividad sobre el extracto. En el otro método, la cuantificación se realiza sobre la harina del grano entero molido, sin extraer la enzima. En el método de extracción se optimizaron tanto el tiempo como el número de extracciones. Los mayores valores de actividad de la fosfolipasa D se obtuvieron por el método sin extracción de la enzima. Este método es más simple, exige menos tiempo de ejecución y las condiciones del medio en que actúa la fosfolipasa D se asemejan a las condiciones encontradas en la industria aceitera.

A cytosolic juxtamembrane interface modulates plexin A3 oligomerization and signal transduction.

Directory of Open Access Journals (Sweden)

Rachael Barton

Full Text Available Plexins (plxns are transmembrane (TM receptors involved in the guidance of vascular, lymphatic vessel, and neuron growth as well as cancer metastasis. Plxn signaling results in cytosolic GTPase-activating protein activity, and previous research implicates dimerization as important for activation of plxn signaling. Purified, soluble plxn extracellular and cytosolic domains exhibit only weak homomeric interactions, suggesting a role for the plxn TM and juxtamembrane regions in homooligomerization. In this study, we consider a heptad repeat in the Danio rerio PlxnA3 cytosolic juxtamembrane domain (JM for its ability to influence PlxnA3 homooligomerization in TM-domain containing constructs. Site-directed mutagenesis in conjunction with the AraTM assay and bioluminescent energy transfer (BRET² suggest an interface involving a JM heptad repeat, in particular residue M1281, regulates PlxnA3 homomeric interactions when examined in constructs containing an ectodomain, TM and JM domain. In the presence of a neuropilin-2a co-receptor and semaphorin 3F ligand, disruption to PlxnA3 homodimerization caused by an M1281F mutation is eliminated, suggesting destabilization of the PlxnA3 homodimer in the JM is not sufficient to disrupt co-receptor complex formation. In contrast, enhanced homodimerization of PlxnA3 caused by mutation M1281L remains even in the presence of ligand semaphorin 3F and co-receptor neuropilin-2a. Consistent with this pattern of PlxnA3 dimerization in the presence of ligand and co-receptor, destabilizing mutations to PlxnA3 homodimerization (M1281F are able to rescue motor patterning defects in sidetracked zebrafish embryos, whereas mutations that enhance PlxnA3 homodimerization (M1281L are not. Collectively, our results indicate the JM heptad repeat, in particular residue M1281, forms a switchable interface that modulates both PlxnA3 homomeric interactions and signal transduction.

Half-of-the-sites reactivity of outer-membrane phospholipase A against an active-site-directed inhibitor.

Science.gov (United States)

Ubarretxena-Belandia, I; Cox, R C; Dijkman, R; Egmond, M R; Verheij, H M; Dekker, N

1999-03-01

The reaction of a novel active-site-directed phospholipase A1 inhibitor with the outer-membrane phospholipase A (OMPLA) was investigated. The inhibitor 1-p-nitrophenyl-octylphosphonate-2-tridecylcarbamoyl-3-et hanesulfonyl -amino-3-deoxy-sn-glycerol irreversibly inactivated OMPLA. The inhibition reaction did not require the cofactor calcium or an unprotonated active-site His142. The inhibition of the enzyme solubilized in hexadecylphosphocholine micelles was characterized by a rapid (t1/2 = 20 min) and complete loss of enzymatic activity, concurrent with the covalent modification of 50% of the active-site serines, as judged from the amount of p-nitrophenolate (PNP) released. Modification of the remaining 50% occurred at a much lower rate, indicative of half-of-the-sites reactivity against the inhibitor of this dimeric enzyme. Inhibition of monomeric OMPLA solubilized in hexadecyl-N,N-dimethyl-1-ammonio-3-propanesulfonate resulted in an equimolar monophasic release of PNP, concurrent with the loss of enzymatic activity (t1/2 = 14 min). The half-of-the-sites reactivity is discussed in view of the dimeric nature of this enzyme.

Inhibition of Secretory Phospholipase A(2) in Patients with Acute Coronary Syndromes: Rationale and Design of the Vascular Inflammation Suppression to Treat Acute Coronary Syndrome for 16 Weeks (VISTA-16) Trial

NARCIS (Netherlands)

Nicholls, Stephen J.; Cavender, Matthew A.; Kastelein, John J. P.; Schwartz, Gregory; Waters, David D.; Rosenson, Robert S.; Bash, Dianna; Hislop, Colin

2012-01-01

Background The action of secretory phospholipase A(2) (sPLA(2)) on lipoproteins may render them more susceptible to oxidation, thereby promoting vascular inflammation and increasing cardiovascular risk. Patients with acute coronary syndrome face a high risk of early, recurrent cardiovascular events

Ceruleotoxin: identification in the venom of Bungarus fasciatus, molecular properties and importance of phospholipase A2 activity for neurotoxicity.

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Bon, C; Saliou, B

1983-01-01

Ceruleotoxin is a potent neurotoxin which was originally purified from a batch of venom labelled Bungarus caeruleus, from the Pasteur Institute. Since NOBLE et al. have shown that this batch differs in its protein composition from that of B. caeruleus provided by Miami Serpentarium, we decided to clarify this point by comparing the composition of venoms from various Bungarus species of several origins. Although individual variations exist between samples of the same species, the venom from B. multicinctus, B. caeruleus and B. fasciatus possess characteristic protein compositions which allowed us to identify the batch used to purify ceruleotoxin as a B. fasciatus venom. We identified and purified ceruleotoxin from each of the five samples of B. fasciatus venoms tested. We failed to find this neurotoxin in either B. multicinctus or B. caeruleus venoms. Purified ceruleotoxin is a slightly basic protein with an isoelectric point of 7.4 which possesses a significant phospholipase A2 activity (200 mumoles lecithin hydrolyzed per min per mg) and a high lethal potency (i.v. LD50 in mice 0.03-0.07 mg/kg). It is composed of two identical subunits of 13,000 mol. wt. which resemble pancreas and snake venom phospholipases in their amino acid composition. Like crotoxin, ceruleotoxin irreversibly blocks the postsynaptic response of Torpedo and Electrophorus electroplaques to cholinergic agonists without preventing the binding of acetylcholine to its receptor. By hydrolyzing critical lipids of the postsynaptic membrane, it stabilizes the acetylcholine receptor - ionophore assembly in a desensitized state.

Accumulation of free oligosaccharides and tissue damage in cytosolic α-mannosidase (Man2c1)-deficient mice.

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Paciotti, Silvia; Persichetti, Emanuele; Klein, Katharina; Tasegian, Anna; Duvet, Sandrine; Hartmann, Dieter; Gieselmann, Volkmar; Beccari, Tommaso

2014-04-04

Free Man(7-9)GlcNAc2 is released during the biosynthesis pathway of N-linked glycans or from misfolded glycoproteins during the endoplasmic reticulum-associated degradation process and are reduced to Man5GlcNAc in the cytosol. In this form, free oligosaccharides can be transferred into the lysosomes to be degraded completely. α-Mannosidase (MAN2C1) is the enzyme responsible for the partial demannosylation occurring in the cytosol. It has been demonstrated that the inhibition of MAN2C1 expression induces accumulation of Man(8-9)GlcNAc oligosaccharides and apoptosis in vitro. We investigated the consequences caused by the lack of cytosolic α-mannosidase activity in vivo by the generation of Man2c1-deficient mice. Increased amounts of Man(8-9)GlcNAc oligosaccharides were recognized in all analyzed KO tissues. Histological analysis of the CNS revealed neuronal and glial degeneration with formation of multiple vacuoles in deep neocortical layers and major telencephalic white matter tracts. Enterocytes of the small intestine accumulate mannose-containing saccharides and glycogen particles in their apical cytoplasm as well as large clear vacuoles in retronuclear position. Liver tissue is characterized by groups of hepatocytes with increased content of mannosyl compounds and glycogen, some of them undergoing degeneration by hydropic swelling. In addition, lectin screening showed the presence of mannose-containing saccharides in the epithelium of proximal kidney tubules, whereas scattered glomeruli appeared collapsed or featured signs of fibrosis along Bowman's capsule. Except for a moderate enrichment of mannosyl compounds and glycogen, heterozygous mice were normal, arguing against possible toxic effects of truncated Man2c1. These findings confirm the key role played by Man2c1 in the catabolism of free oligosaccharides.

Action of phospholipases on the phosphatidylcholine exchange protein from beef liver

NARCIS (Netherlands)

Kamp, H.H.; Sprengers, E.D.; Westerman, J.; Wirtz, K.W.A.; Deenen, L.L.M. van

1975-01-01

Abstract The phospholipases A2, C and D have been used to investigate the localization of phosphatidylcholine in the phosphatidylcholine exchange protein from beef liver. The rate of enzymatic hydrolysis of the protein-bound phosphatidylcholine was found to be very low. Addition of deoxycholate,

Quercetin-induced downregulation of phospholipase D1 inhibits proliferation and invasion in U87 glioma cells

Energy Technology Data Exchange (ETDEWEB)

Park, Mi Hee [Department of Molecular Biology, College of Natural Science, Pusan National University, 30 Jangjeon dong, Geumjeong gu, Busan 609-735 (Korea, Republic of); Min, Do Sik, E-mail: minds@pusan.ac.kr [Department of Molecular Biology, College of Natural Science, Pusan National University, 30 Jangjeon dong, Geumjeong gu, Busan 609-735 (Korea, Republic of)

2011-09-09

Highlights: {yields} Quercetin, a bioactive flavonoid, suppresses expression and enzymatic activity of phospholipase D1. {yields} Quercetin abolishes NFkB-induced phospholipase D1 expression via inhibition of NFkB transactivation. {yields} Quercetin-induced suppression of phospholipase D1 inhibits invasion and proliferation of human glioma cells. -- Abstract: Phospholipase D (PLD) has been recognized as a regulator of cell proliferation and tumorigenesis, but little is known about the molecules regulating PLD expression. Thus, the identification of small molecules inhibiting PLD expression would be an important advance in PLD-mediated physiology. Quercetin, a ubiquitous bioactive flavonoid, is known to inhibit proliferation and induce apoptosis in a variety of cancer cells. In the present study, we examined the effect of quercetin on the expression of PLD in U87 glioma cells. Quercetin significantly suppressed the expression of PLD1 at the transcriptional level. Moreover, quercetin abolished the protein expression of PLD1 in a time and dose-dependent manner, as well as inhibited PLD activity. Quercetin suppressed NF{kappa}B-induced PLD1 expression via inhibition of NFkB transactivation. Furthermore, quercetin inhibited activation and invasion of metalloproteinase-2 (MMP-2), a key modulator of glioma cell invasion, induced by phosphatidic acid (PA), a product of PLD activity. Taken together these data demonstrate that quercetin abolishes PLD1 expression and subsequently inhibits invasion and proliferation of glioma cells.

Secretory phospholipase A2 in dromedary tears: a host defense against staphylococci and other gram-positive bacteria.

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Ben Bacha, Abir; Abid, Islem

2013-03-01

The best known physiologic function of secreted phospholipase A2 (sPLA2) group IIA (sPLA2-IIA) is defense against bacterial infection through hydrolytic degradation of bacterial membrane phospholipids. In fact, sPLA2-IIA effectively kills Gram-positive bacteria and to a lesser extent Gram-negative bacteria and is considered a major component of the eye's innate immune defense system. The antibacterial properties of sPLA2 have been demonstrated in rabbit and human tears. In this report, we have analyzed the bactericidal activity of dromedary tears and the subsequently purified sPLA2 on several Gram-positive bacteria. Our results showed that the sPLA2 displays a potent bactericidal activity against all the tested bacteria particularly against the Staphylococcus strains when tested in the ionic environment of tears. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2. Interestingly, lysozyme purified from dromedary tears showed a significant bactericidal activity against Listeria monocytogene and Staphylococcus epidermidis, whereas the one purified from human tears displayed no activity against these two strains. We have also demonstrated that Ca(2+) is crucial for the activity of dromedary tear sPLA2 and to a less extent Mg(2+) ions. Given the presence of sPLA2 in tears and intestinal secretions, this enzyme may play a substantial role in innate mucosal and systemic bactericidal defenses against Gram-positive bacteria.

Increased expression and activity of group IIA and X secretory phospholipase A2 in peritumoral versus central colon carcinoma tissue

DEFF Research Database (Denmark)

Tribler, Line; Jensen, Lotte T.; Jørgensen, Kent

2007-01-01

Secretory phospholipase A2 (sPLA2) type IIA and X was analyzed in tumors from 22 patients with colon adenocarcinomas in order to determine the involvement and activity of sPLA2 in colon cancer. Evaluation of immunoreactive sPLA2 IIA by Western blotting showed a significantly higher level...... in the periphery of the tumors, compared to central tumor regions. Increased levels of sPLA2 IIA protein correlated with a two-fold increase in sPLA2 enzymatic activity in the peripheral regions compared to central regions. Nineteen out of 22 tumors showed high levels of sPLA2 IIA, whereas 7 out of the 22 tumors...... showed sPLA2 type X. These data demonstrate that both sPLA2 type IIA and X are present in human colon cancer and suggest a role for sPLA2 in colon cancer tumor immunology and tumorigenesis....

Phospholipase and proteinase activities of Candida spp. isolates from vulvovaginitis in Iran.

Science.gov (United States)

Shirkhani, S; Sepahvand, A; Mirzaee, M; Anbari, K

2016-09-01

This study aims to characterize phospholipase and proteinase activities of Candida isolates from 82 vulvovaginal candidiasis (VVC) and to study the relationship of these activities with vulvovaginitis. Totally 82 Candida isolates from vagina samples of VVC patients were randomly collected over the period between September and December 2014 from hospitalized patients at the general hospitals of Lorestan province, Iran. Isolates were previously identified by conventional mycological methods. The phospholipase and proteinase activities were evaluated by Egg yolk agar, Tween 80 opacity medium and agar plate methods. The most common Candida species was identified Candida albicans (n=34, 41.5%), followed by Candida famata (n=13, 15.8%), Candida tropicalis (n=11, 13.4%), and Candida parapsilosis (n=9, 11%). The most phospholipase activity was observed in Candida colliculosa (40%), followed by C. famata (38.5%), and Candida krusei (33.3%). The findings revealed that the correlation between phospholipase production by Candida spp. and the presence of VVC was not found to be statistically significant (P=0.91). All Candida spp. exhibited considerable proteinase activity; so that 100% of C. colliculosa, C. parapsilosis, Candida kefyr, and Candida intermedia isolates produced high proteinase activity with Pz 4+ scores. There was a significant correlation between proteinase production by Candida spp. and the presence of VVC (P=0.009). The obtained findings revealed that Candida spp. isolates may produce both virulence factors, phospholipase and proteinase. Although the phospholipase production was only observed in <40% of the isolates; however there was a significant association between proteinase production by Candida spp. and VVC. Copyright © 2016. Published by Elsevier Masson SAS.

Effect of starvation, diabetes and insulin on the casein kinase 2 from rat liver cytosol.

OpenAIRE

Martos, C; Plana, M; Guasch, M D; Itarte, E

1985-01-01

Starvation, diabetes and insulin did not alter the concentration of casein kinases in rat liver cytosol. However, the Km for casein of casein kinase 2 from diabetic rats was about 2-fold lower than that from control animals. Administration of insulin to control rats did not alter this parameter, but increased the Km for casein of casein kinase 2 in diabetic rats. Starvation did not affect the kinetic constants of casein kinases. The effect of diabetes on casein kinase 2 persisted after partia...

Determination of germ tube, phospholipase, and proteinase production by bloodstream isolates of Candida albicans

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Antonella Souza Mattei

2013-06-01

Full Text Available Introduction Candida albicans is a commensal and opportunistic agent that causes infection in immunocompromised individuals. Several attributes contribute to the virulence and pathogenicity of this yeast, including the production of germ tubes (GTs and extracellular hydrolytic enzymes, particularly phospholipase and proteinase. This study aimed to investigate GT production and phospholipase and proteinase activities in bloodstream isolates of C. albicans. Methods One hundred fifty-three C. albicans isolates were obtained from blood samples and analyzed for GT, phospholipase, and proteinase production. The assays were performed in duplicate in egg yolk medium containing bovine serum albumin and human serum. Results Detectable amounts of proteinase were produced by 97% of the isolates, and 78% of the isolates produced phospholipase. GTs were produced by 95% of the isolates. A majority of the isolates exhibited low levels of phospholipase production and high levels of proteinase production. Conclusions Bloodstream isolates of C. albicans produce virulence factors such as GT and hydrolytic enzymes that enable them to cause infection under favorable conditions.

The mechanism of phospholipase Cγ1 activation

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Paweł Krawczyk

2011-08-01

Full Text Available Phospholipase C is an enzyme which catalyzes the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PI(4,5P2 into second messengers inositol-1,4,5-triphosphate (Ins(1,4,5P3 and diacylglycerol (DAG. These messengers then promote the activation of protein kinase C and release of Ca2 from intracellular stores, initiating numerous cellular events including proliferation, differentiation, signal transduction, endocytosis, cytoskeletal reorganization or activation of ion channels. There have been identified 14 isozymes of PLC among which PLCγ1 and PLCγ2 are of particular interest. PLC contains catalytic region XY and a few regulatory domains: PH, EF and C2. The most unique features of these two enzymes are the Src homology domains (SH2, SH3 and split PH domain within the catalytic barrel. PLC1 and PLCγ2 have an identical domain structure, but they differ in their function and occurrence. Phospholipase Cγ1 is expressed ubiquitously, especially in the brain, thymus and lungs.PLCγ1 can be activated by receptor tyrosine kinases (i.e.: PDGFR, EGFR, FGFR, Trk, as well as non-receptor protein kinases (Src, Syk, Tec or phosphatidic acid, tau protein and its analogue.The molecular mechanism of PLCγ1 activation includes membrane recruitment, phosphorylation, rearrangements and activation in the presence of growth factors.In reference to PLCγ1 regulation, a number of positive and negative modulators have been considered. The most important positive modulator is phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5P2. Protein kinase A and C, tyrosine phosphatases (SHP-1, PTP-1B and Cbl, Grb2, Jak2/PTP-1B complex proteins have been described as negative regulators of PLCγ1 activation.

Liver/kidney microsomal antibody type 1 and liver cytosol antibody type 1 concentrations in type 2 autoimmune hepatitis.

Science.gov (United States)

Muratori, L; Cataleta, M; Muratori, P; Lenzi, M; Bianchi, F B

1998-05-01

Liver/kidney microsomal antibody type 1 (LKM1) and liver cytosol antibody type 1 (LC1) are the serological markers of type 2 autoimmune hepatitis (AIH). Since LKM1 and LC1 react against two distinct liver specific autoantigens (cytochrome P450IID6 (CYP2D6) and a 58 kDa cytosolic polypeptide respectively), the aim was to see whether LKM1 and LC1 concentrations correlate with liver disease activity. Twenty one patients with type 2 AIH were studied. All sera were tested by indirect immunofluorescence, counterimmunoelectrophoresis, and immunoblotting visualised by enhanced chemiluminescence. To evaluate LKM1 and LC1 levels, the 50 kDa microsomal reactivity (corresponding to CYP2D6) and the 58 kDa cytosolic reactivity were quantified by densitometric analysis. Seven patients were positive for LKM1, nine for LC1, and five for both. Serial serum samples at onset and during immunosuppressive treatment were analysed in 13 patients (four positive for LKM1, six positive for LC1 and three positive for both). During remission, LKM1 concentration remained essentially unchanged in six of seven patients, and decreased in only one. Conversely, in two of nine patients, LC1 was completely lost, and, in the remaining seven, LC1 concentration was reduced by more than 50%. After immunosuppression tapering or withdrawal, flare ups of liver necrosis ensued with increasing LC1 concentration, but not LKM1. LC1 concentration, at variance with that of LKM1, parallels liver disease activity, and its participation in the pathogenic mechanisms of liver injury can be hypothesised.

Atomic resolution structure of the double mutant (K53,56M) of bovine pancreatic phospholipase A2

International Nuclear Information System (INIS)

Sekar, K.; Yogavel, M.; Gayathri, D.; Velmurugan, D.; Krishna, R.; Poi, M.-J.; Dauter, Z.; Dauter, M.; Tsai, M.-D.

2005-01-01

The atomic resolution crystal structure of the double mutant (K53,56M) of bovine pancreatic phospholipase A 2 is reported. The structure of the double mutant K53,56M has previously been refined at 1.9 Å resolution using room-temperature data. The present paper reports the crystal structure of the same mutant K53,56M refined against 1.1 Å data collected using synchrotron radiation. A total of 116 main-chain atoms from 29 residues and 44 side chains are modelled in alternate conformations. Most of the interfacial binding residues are found to be disordered and alternate conformations could be recognized. The second calcium ion-binding site residue Glu92 adopts two alternate conformations. The minor and major conformations of Glu92 correspond to the second calcium ion bound and unbound states

Pressurized liquid extraction-assisted mussel cytosol preparation for the determination of metals bound to metallothionein-like proteins

International Nuclear Information System (INIS)

Santiago-Rivas, Sandra; Moreda-Pineiro, Antonio; Bermejo-Barrera, Pilar; Moreda-Pineiro, Jorge; Alonso-Rodriguez, Elia; Muniategui-Lorenzo, Soledad; Lopez-Mahia, Purificacion; Prada-Rodriguez, Dario

2007-01-01

The possibilities of pressurized liquid extraction (PLE) have been novelty tested to assist the cytosol preparation from wet mussel soft tissue before the determination of metals bound to metallothionein-like proteins (MLPs). Results obtained after PLE were compared with those obtained after a classical blending procedure for mussel cytosolic preparation. Isoforms MLP-1 (retention time of 4.1 min) and MLP-2 (retention time of 7.4 min) were separated by anion exchange high-performance liquid chromatography (HPLC) and the concentrations of Ba, Cu, Mn, Sr and Zn bound to MLP isoforms were directly measured by inductively coupled plasma-atomic emission spectrometry (ICP-OES) as a multi-element detector. The optimized PLE-assisted mussel cytosol preparation has consisted of one extraction cycle at room temperature and 1500 psi for 2 min. Since separation between the solid mussel residue and the extract (cytosol) is performed by the PLE system, the cytosol preparation method is faster than conventional cytosol preparation methods by cutting/blending using Ultraturrax or Stomacher devices

Transgenic mosquitoes expressing a phospholipase A(2 gene have a fitness advantage when fed Plasmodium falciparum-infected blood.

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Ryan C Smith

Full Text Available Genetically modified mosquitoes have been proposed as an alternative strategy to reduce the heavy burden of malaria. In recent years, several proof-of-principle experiments have been performed that validate the idea that mosquitoes can be genetically modified to become refractory to malaria parasite development.We have created two transgenic lines of Anophelesstephensi, a natural vector of Plasmodium falciparum, which constitutively secrete a catalytically inactive phospholipase A2 (mPLA2 into the midgut lumen to interfere with Plasmodium ookinete invasion. Our experiments show that both transgenic lines expressing mPLA2 significantly impair the development of rodent malaria parasites, but only one line impairs the development of human malaria parasites. In addition, when fed on malaria-infected blood, mosquitoes from both transgenic lines are more fecund than non-transgenic mosquitoes. Consistent with these observations, cage experiments with mixed populations of transgenic and non-transgenic mosquitoes show that the percentage of transgenic mosquitoes increases when maintained on Plasmodium-infected blood.Our results suggest that the expression of an anti-Plasmodium effector gene gives transgenic mosquitoes a fitness advantage when fed malaria-infected blood. These findings have important implications for future applications of transgenic mosquito technology in malaria control.

Pressure Modulation of the Enzymatic Activity of Phospholipase A2, A Putative Membrane-Associated Pressure Sensor.

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Suladze, Saba; Cinar, Suleyman; Sperlich, Benjamin; Winter, Roland

2015-10-07

Phospholipases A2 (PLA2) catalyze the hydrolysis reaction of sn-2 fatty acids of membrane phospholipids and are also involved in receptor signaling and transcriptional pathways. Here, we used pressure modulation of the PLA2 activity and of the membrane's physical-chemical properties to reveal new mechanistic information about the membrane association and subsequent enzymatic reaction of PLA2. Although the effect of high hydrostatic pressure (HHP) on aqueous soluble and integral membrane proteins has been investigated to some extent, its effect on enzymatic reactions operating at the water/lipid interface has not been explored, yet. This study focuses on the effect of HHP on the structure, membrane binding and enzymatic activity of membrane-associated bee venom PLA2, covering a pressure range up to 2 kbar. To this end, high-pressure Fourier-transform infrared and high-pressure stopped-flow fluorescence spectroscopies were applied. The results show that PLA2 binding to model biomembranes is not significantly affected by pressure and occurs in at least two kinetically distinct steps. Followed by fast initial membrane association, structural reorganization of α-helical segments of PLA2 takes place at the lipid water interface. FRET-based activity measurements reveal that pressure has a marked inhibitory effect on the lipid hydrolysis rate, which decreases by 75% upon compression up to 2 kbar. Lipid hydrolysis under extreme environmental conditions, such as those encountered in the deep sea where pressures up to the kbar-level are encountered, is hence markedly affected by HHP, rendering PLA2, next to being a primary osmosensor, a good candidate for a sensitive pressure sensor in vivo.

Aluminum ions inhibit phospholipase D in a microtubule-dependent manner

Czech Academy of Sciences Publication Activity Database

Pejchar, Přemysl; Pleskot, R.; Schwarzerová, K.; Martinec, Jan; Valentová, O.; Novotná, Z.

2008-01-01

Roč. 32, č. 5 (2008), s. 554-556 ISSN 1065-6995 R&D Projects: GA ČR GA522/05/0340 Institutional research plan: CEZ:AV0Z50380511 Keywords : Aluminum toxicity * Phospholipase D * Microtubules Subject RIV: ED - Physiology Impact factor: 1.619, year: 2008

Pancreatic and snake venom presynaptically active phospholipases A2 inhibit nicotinic acetylcholine receptors.

Science.gov (United States)

Vulfius, Catherine A; Kasheverov, Igor E; Kryukova, Elena V; Spirova, Ekaterina N; Shelukhina, Irina V; Starkov, Vladislav G; Andreeva, Tatyana V; Faure, Grazyna; Zouridakis, Marios; Tsetlin, Victor I; Utkin, Yuri N

2017-01-01

Phospholipases A2 (PLA2s) are enzymes found throughout the animal kingdom. They hydrolyze phospholipids in the sn-2 position producing lysophospholipids and unsaturated fatty acids, agents that can damage membranes. PLA2s from snake venoms have numerous toxic effects, not all of which can be explained by phospholipid hydrolysis, and each enzyme has a specific effect. We have earlier demonstrated the capability of several snake venom PLA2s with different enzymatic, cytotoxic, anticoagulant and antiproliferative properties, to decrease acetylcholine-induced currents in Lymnaea stagnalis neurons, and to compete with α-bungarotoxin for binding to nicotinic acetylcholine receptors (nAChRs) and acetylcholine binding protein. Since nAChRs are implicated in postsynaptic and presynaptic activities, in this work we probe those PLA2s known to have strong presynaptic effects, namely β-bungarotoxin from Bungarus multicinctus and crotoxin from Crotalus durissus terrificus. We also wished to explore whether mammalian PLA2s interact with nAChRs, and have examined non-toxic PLA2 from porcine pancreas. It was found that porcine pancreatic PLA2 and presynaptic β-bungarotoxin blocked currents mediated by nAChRs in Lymnaea neurons with IC50s of 2.5 and 4.8 μM, respectively. Crotoxin competed with radioactive α-bungarotoxin for binding to Torpedo and human α7 nAChRs and to the acetylcholine binding protein. Pancreatic PLA2 interacted similarly with these targets; moreover, it inhibited radioactive α-bungarotoxin binding to the water-soluble extracellular domain of human α9 nAChR, and blocked acetylcholine induced currents in human α9α10 nAChRs heterologously expressed in Xenopus oocytes. These and our earlier results show that all snake PLA2s, including presynaptically active crotoxin and β-bungarotoxin, as well as mammalian pancreatic PLA2, interact with nAChRs. The data obtained suggest that this interaction may be a general property of all PLA2s, which should be proved by

Pancreatic and snake venom presynaptically active phospholipases A2 inhibit nicotinic acetylcholine receptors.

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Catherine A Vulfius

Full Text Available Phospholipases A2 (PLA2s are enzymes found throughout the animal kingdom. They hydrolyze phospholipids in the sn-2 position producing lysophospholipids and unsaturated fatty acids, agents that can damage membranes. PLA2s from snake venoms have numerous toxic effects, not all of which can be explained by phospholipid hydrolysis, and each enzyme has a specific effect. We have earlier demonstrated the capability of several snake venom PLA2s with different enzymatic, cytotoxic, anticoagulant and antiproliferative properties, to decrease acetylcholine-induced currents in Lymnaea stagnalis neurons, and to compete with α-bungarotoxin for binding to nicotinic acetylcholine receptors (nAChRs and acetylcholine binding protein. Since nAChRs are implicated in postsynaptic and presynaptic activities, in this work we probe those PLA2s known to have strong presynaptic effects, namely β-bungarotoxin from Bungarus multicinctus and crotoxin from Crotalus durissus terrificus. We also wished to explore whether mammalian PLA2s interact with nAChRs, and have examined non-toxic PLA2 from porcine pancreas. It was found that porcine pancreatic PLA2 and presynaptic β-bungarotoxin blocked currents mediated by nAChRs in Lymnaea neurons with IC50s of 2.5 and 4.8 μM, respectively. Crotoxin competed with radioactive α-bungarotoxin for binding to Torpedo and human α7 nAChRs and to the acetylcholine binding protein. Pancreatic PLA2 interacted similarly with these targets; moreover, it inhibited radioactive α-bungarotoxin binding to the water-soluble extracellular domain of human α9 nAChR, and blocked acetylcholine induced currents in human α9α10 nAChRs heterologously expressed in Xenopus oocytes. These and our earlier results show that all snake PLA2s, including presynaptically active crotoxin and β-bungarotoxin, as well as mammalian pancreatic PLA2, interact with nAChRs. The data obtained suggest that this interaction may be a general property of all PLA2s, which

Aberrant methylation of the M-type phospholipase A2 receptor gene in leukemic cells

International Nuclear Information System (INIS)

Menschikowski, Mario; Platzbecker, Uwe; Hagelgans, Albert; Vogel, Margot; Thiede, Christian; Schönefeldt, Claudia; Lehnert, Renate; Eisenhofer, Graeme; Siegert, Gabriele

2012-01-01

The M-type phospholipase A2 receptor (PLA2R1) plays a crucial role in several signaling pathways and may act as tumor-suppressor. This study examined the expression and methylation of the PLA2R1 gene in Jurkat and U937 leukemic cell lines and its methylation in patients with myelodysplastic syndrome (MDS) or acute leukemia. Sites of methylation of the PLA2R1 locus were identified by sequencing bisulfite-modified DNA fragments. Methylation specific-high resolution melting (MS-HRM) analysis was then carried out to quantify PLA2R1 methylation at 5-CpG sites identified with differences in methylation between healthy control subjects and leukemic patients using sequencing of bisulfite-modified genomic DNA. Expression of PLA2R1 was found to be completely down-regulated in Jurkat and U937 cells, accompanied by complete methylation of PLA2R1 promoter and down-stream regions; PLA2R1 was re-expressed after exposure of cells to 5-aza-2´-deoxycytidine. MS-HRM analysis of the PLA2R1 locus in patients with different types of leukemia indicated an average methylation of 28.9% ± 17.8%, compared to less than 9% in control subjects. In MDS patients the extent of PLA2R1 methylation significantly increased with disease risk. Furthermore, measurements of PLA2R1 methylation appeared useful for predicting responsiveness to the methyltransferase inhibitor, azacitidine, as a pre-emptive treatment to avoid hematological relapse in patients with high-risk MDS or acute myeloid leukemia. The study shows for the first time that PLA2R1 gene sequences are a target of hypermethylation in leukemia, which may have pathophysiological relevance for disease evolution in MDS and leukemogenesis

Monoacylated Cellular Prion Proteins Reduce Amyloid-β-Induced Activation of Cytoplasmic Phospholipase A2 and Synapse Damage

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Ewan West

2015-06-01

Full Text Available Alzheimer’s disease (AD is a progressive neurodegenerative disease characterized by the accumulation of amyloid-β (Aβ and the loss of synapses. Aggregation of the cellular prion protein (PrPC by Aβ oligomers induced synapse damage in cultured neurons. PrPC is attached to membranes via a glycosylphosphatidylinositol (GPI anchor, the composition of which affects protein targeting and cell signaling. Monoacylated PrPC incorporated into neurons bound “natural Aβ”, sequestering Aβ outside lipid rafts and preventing its accumulation at synapses. The presence of monoacylated PrPC reduced the Aβ-induced activation of cytoplasmic phospholipase A2 (cPLA2 and Aβ-induced synapse damage. This protective effect was stimulus specific, as treated neurons remained sensitive to α-synuclein, a protein associated with synapse damage in Parkinson’s disease. In synaptosomes, the aggregation of PrPC by Aβ oligomers triggered the formation of a signaling complex containing the cPLA2.a process, disrupted by monoacylated PrPC. We propose that monoacylated PrPC acts as a molecular sponge, binding Aβ oligomers at the neuronal perikarya without activating cPLA2 or triggering synapse damage.

LeftyA sensitive cytosolic pH regulation and glycolytic flux in Ishikawa human endometrial cancer cells

Energy Technology Data Exchange (ETDEWEB)

Salker, Madhuri S.; Zhou, Yuetao; Singh, Yogesh [Department of Physiology, University of Tuebingen, 72076 Tuebingen (Germany); Brosens, Jan [Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratories, University Hospital, Coventry CV2 2DX (United Kingdom); Lang, Florian, E-mail: florian.lang@uni-tuebingen.de [Department of Physiology, University of Tuebingen, 72076 Tuebingen (Germany)

2015-05-08

Objective: LeftyA, a powerful regulator of stemness, embryonic differentiation, and reprogramming of cancer cells, counteracts cell proliferation and tumor growth. Key properties of tumor cells include enhanced glycolytic flux, which is highly sensitive to cytosolic pH and thus requires export of H{sup +} and lactate. H{sup +} extrusion is in part accomplished by Na{sup +}/H{sup +} exchangers, such as NHE1. An effect of LeftyA on transport processes has, however, never been reported. The present study thus explored whether LeftyA modifies regulation of cytosolic pH (pHi) in Ishikawa cells, a well differentiated endometrial carcinoma cell model. Methods: NHE1 transcript levels were determined by qRT-PCR, NHE1 protein abundance quantified by Western blotting, pH{sub i} estimated utilizing (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein [BCECF] fluorescence, Na{sup +}/H{sup +} exchanger activity from Na{sup +} dependent realkalinization after an ammonium pulse, and lactate concentration in the supernatant utilizing an enzymatic assay and subsequent colorimetry. Results: A 2 h treatment with LeftyA (8 ng/ml) significantly decreased NHE1 transcript levels (by 99.6%), NHE1 protein abundance (by 71%), Na{sup +}/H{sup +} exchanger activity (by 55%), pHi (from 7.22 ± 0.02 to 7.05 ± 0.02), and lactate release (by 41%). Conclusions: LeftyA markedly down-regulates NHE1 expression, Na{sup +}/H{sup +} exchanger activity, pHi, and lactate release in Ishikawa cells. Those effects presumably contribute to cellular reprogramming and growth inhibition. - Highlights: • LeftyA, an inhibitor of tumor growth, reduces Na{sup +}/H{sup +}-exchanger activity by 55%. • LeftyA decreases NHE1 transcripts by 99.6% and NHE1 protein by 71%. • LeftyA decreases cytosolic pH from 7.22 ± 0.02 to 7.05 ± 0.02. • Cytosolic acidification by Lefty A decreases glycolysis by 41%. • Cytosolic acidification by Lefty A compromises energy production of tumor cells.

Antibody to liver cytosol (anti-LC1) in patients with autoimmune chronic active hepatitis type 2.

Science.gov (United States)

Martini, E; Abuaf, N; Cavalli, F; Durand, V; Johanet, C; Homberg, J C

1988-01-01

A new autoantibody was detected by immunoprecipitation in the serum of 21 patients with chronic active hepatitis. The antibody reacted against a soluble cytosolic antigen in liver. The antibody was organ specific but not species specific and was therefore called anti-liver cytosol antibody Type 1 (anti-LC1). In seven of 21 cases, no other autoantibody was found; the remaining 14 cases had anti-liver/kidney microsome antibody Type 1 (anti-LKM1). With indirect immunofluorescence, a distinctive staining pattern was observed with the seven sera with anti-LC1 and without anti-LKM1. The antibody stained the cytoplasm of hepatocytes from four different animal species and spared the cellular layer around the central veins of mouse and rat liver that we have called juxtavenous hepatocytes. The immunofluorescence pattern disappeared after absorption of sera by a liver cytosol fraction. The 14 sera with both antibodies displayed anti-LC1 immunofluorescent pattern after absorption of anti-LKM1 by the liver microsomal fraction. The anti-LC1 was found in the serum only in patients with chronic active hepatitis of unknown cause. Anti-LC1 antibody was not found in sera from 100 patients with chronic active hepatitis associated with anti-actin antibody classic chronic active hepatitis Type 1, 100 patients with primary biliary cirrhosis, 157 patients with drug-induced hepatitis and a large number of patients with liver and nonliver diseases. This new antibody was considered a second marker of chronic active hepatitis associated with anti-LKM1 (anti-LKM1 chronic active hepatitis) or autoimmune chronic active hepatitis Type 2.

Identification of a membrane-bound, glycol-stimulated phospholipase A2 located in the secretory granules of the adrenal medulla

International Nuclear Information System (INIS)

Hildebrandt, E.; Albanesi, J.P.

1991-01-01

Chromaffin granule membranes prepared from bovine adrenal medullae showed Ca 2+ -stimulated phospholipase A 2 (PLA 2 ) activity when assayed at pH 9.0 with phosphatidylcholine containing an [ 14 C]-arachidonyl group in the 2-position. However, the activity occurred in both soluble and particulate subcellular fractions, and did not codistribute with markers for the secretory granule. PLA 2 activity in the granule membrane preparation was stimulated dramatically by addition of glycerol, ethylene glycole, or poly(ethylene glycol). This glycol-stimulated PLA 2 activity codistributed with membrane-bound dopamine β-hydroxylase, a marker for the granule membranes, through the sequence of differential centrifugation steps employed to prepare the granule membrane fraction, as well as on a sucrose density gradient which resolved the granules from mitochondria, lysosomes, and plasma membrane. The glycol-stimulated PLA 2 of the chromaffin granule was membrane-bound, exhibited a pH optimum of 7.8, retained activity in the presence of EDTA, and was inactivated by p-bromophenacyl bromide. When different 14 C-labeled phospholipids were incorporated into diarachidonylphosphatidylcholine liposomes, 1-palmitoyl-2-arachidonylphosphatidylcholine was a better substrate for this enzyme than 1-palmitoyl-2-oleylphosphatidylcholine or 1-acyl-2-arachidonyl-phosphatidylethhanolamine, and distearoylphosphatidylcholine was not hydrolyzed

Role of phospholipases A2 in diabetic retinopathy: in vitro and in vivo studies.

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Lupo, Gabriella; Motta, Carla; Giurdanella, Giovanni; Anfuso, Carmelina Daniela; Alberghina, Mario; Drago, Filippo; Salomone, Salvatore; Bucolo, Claudio

2013-12-01

Diabetic retinopathy is one of the leading causes of blindness and the most common complication of diabetes with no cure available. We investigated the role of phospholipases A2 (PLA2) in diabetic retinopathy using an in vitro blood-retinal barrier model (BRB) and an in vivo streptozotocin (STZ)-induced diabetic model. Mono- and co-cultures of endothelial cells (EC) and pericytes (PC), treated with high or fluctuating concentrations of glucose, to mimic the diabetic condition, were used. PLA2 activity, VEGF and PGE2 levels and cell proliferation were measured, with or without PLA2 inhibition. Diabetes was induced in rats by STZ injection and PLA2 activity along with VEGF, TNFα and ICAM-1 levels were measured in retina. High or fluctuating glucose induced BRB breakdown, and increased PLA2 activity, PGE2 and VEGF in EC/PC co-cultures; inhibition of PLA2 in mono- or co-cultures treated with high or fluctuating glucose dampened PGE2 and VEGF production down to the levels of controls. High or fluctuating glucose increased EC number and reduced PC number in co-cultures; these effects were reversed after transfecting EC with small interfering RNA targeted to PLA2. PLA2 and COX-2 protein expressions were significantly increased in microvessels from retina of diabetic rats. Diabetic rats had also high retinal levels of VEGF, ICAM-1 and TNFα that were reduced by treatment with a cPLA2 inhibitor. In conclusion, the present findings indicate that PLA2 upregulation represents an early step in glucose-induced alteration of BRB, possibly upstream of VEGF; thus, PLA2 may be an interesting target in managing diabetic retinopathy. Copyright © 2013 Elsevier Inc. All rights reserved.

Role of calbindin-D9k in buffering cytosolic free Ca2+ ions in pig duodenal enterocytes.

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Schröder, B; Schlumbohm, C; Kaune, R; Breves, G

1996-05-01

1. The aim of the present study was to test whether the vitamin D-dependent Ca(2+)-binding protein calbindin-D9k could function as an important cytosolic Ca2+ buffer in duodenal enterocytes while facilitating transepithelial active transport of Ca2+ ions. For the investigations we used dual-wavelength, fluorescence ratio imaging, with fura-2 as the Ca(2+)-sensitive dye, to measure changes in cytosolic concentrations of free Ca2+ ions ([Ca2+]i) in isolated pig duodenal enterocytes affected by different cytosolic calbindin-D9k concentrations. 2. Epithelial cells were obtained from weaned piglets with normal calbindin-D9k concentrations (con-piglets), from piglets with low calbindin-D9k levels due to inherited calcitriol deficiency caused by defective renal 25-hydroxycholecalciferol D3-1 alpha-hydroxylase activity (def-piglets), and from piglets with reconstituted calbindin-D9k concentrations, i.e. def-animals treated with high doses of vitamin D3 which elevated plasma calcitriol levels by extrarenal production (def-D3-piglets). Basal levels of [Ca2+]i ranged between 170 and 205 nM and did not differ significantly between the groups. 3. After addition of 5 mM theophylline, the [Ca2+]i in enterocytes from con-piglets doubled during the 10 min incubation. This effect, however, was three times higher in enterocytes from def-piglets compared with those from con-piglets. Similar results were obtained after 4 min incubation of enterocytes from con- and def-piglets in the presence of 1 microM ionomycin. In preparations from def-D3-piglets, ionomycin-induced increases in [Ca2+]i were significantly lower compared with enterocytes from def-piglets and were not different from the control values. 4. From the results, substantial support is given for the hypothesis that one of the major functions of mucosal calbindin-D9k is the effective buffering of Ca2+ ions.

BmajPLA2-II, a basic Lys49-phospholipase A2 homologue from Bothrops marajoensis snake venom with parasiticidal potential.

Science.gov (United States)

Grabner, Amy N; Alfonso, Jorge; Kayano, Anderson M; Moreira-Dill, Leandro S; Dos Santos, Ana Paula de A; Caldeira, Cleópatra A S; Sobrinho, Juliana C; Gómez, Ana; Grabner, Fernando P; Cardoso, Fabio F; Zuliani, Juliana Pavan; Fontes, Marcos R M; Pimenta, Daniel C; Gómez, Celeste Vega; Teles, Carolina B G; Soares, Andreimar M; Calderon, Leonardo A

2017-09-01

Snake venoms contain various proteins, especially phospholipases A 2 (PLA 2 s), which present potential applications in diverse areas of health and medicine. In this study, a new basic PLA 2 from Bothrops marajoensis with parasiticidal activity was purified and characterized biochemically and biologically. B. marajoensis venom was fractionated through cation exchange followed by reverse phase chromatographies. The isolated toxin, BmajPLA 2 -II, was structurally characterized with MALDI-TOF (Matrix-assisted laser desorption/ionization-time of flight) mass spectrometry, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), followed by two-dimensional electrophoresis, partial amino acid sequencing, an enzymatic activity assay, circular dichroism, and dynamic light scattering assays. These structural characterization tests presented BmajPLA 2 -II as a basic Lys49 PLA 2 homologue, compatible with other basic snake venom PLA 2 s (svPLA 2 ), with a tendency to form aggregations. The in vitro anti-parasitic potential of B. marajoensis venom and of BmajPLA 2 -II was evaluated against Leishmania infantum promastigotes and Trypanosoma cruzi epimastigotes, showing significant activity at a concentration of 100μg/mL. The venom and BmajPLA 2 -II presented IC 50 of 0.14±0.08 and 6.41±0.64μg/mL, respectively, against intraerythrocytic forms of Plasmodium falciparum with CC 50 cytotoxicity values against HepG2 cells of 43.64±7.94 and >150μg/mL, respectively. The biotechnological potential of these substances in relation to leishmaniasis, Chagas disease and malaria should be more deeply investigated. Copyright © 2017. Published by Elsevier B.V.

Presenilin dependence of phospholipase C and protein kinase C signaling

DEFF Research Database (Denmark)

Dehvari, Nodi; Cedazo-Minguez, Angel; Isacsson, Ola

2007-01-01

-stimulated phospholipase C (PLC) activity which was gamma-secretase dependent. To further evaluate the dependence of PLC on PSs we measured PLC activity and the activation of variant protein kinase C (PKC) isoforms in mouse embryonic fibroblasts (MEFs) lacking either PS1, PS2, or both. PLC activity and PKCalpha...

Plasma Lipoprotein-associated Phospholipase A2 in Patients with Metabolic Syndrome and Carotid Atherosclerosis

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Mao Yong-jun

2011-01-01

Full Text Available Abstract Background Lipoprotein-associated phospholipase A2 (Lp-PLA2 is a recently identified and potentially useful plasma biomarker for cardiovascular and atherosclerotic diseases. However, the correlation between the Lp-PLA2 activity and carotid atherosclerosis remains poorly investigated in patients with metabolic syndrome (MetS. The present study aimed to evaluate the potential role of Lp-PLA2 as a comprehensive marker of metabolic syndrome in individuals with and without carotid atherosclerosis. Methods We documented 118 consecutive patients with MetS and 70 age- and sex-matched healthy subjects served as controls. The patients were further divided into two groups: 39 with carotid plaques and 79 without carotid plaques to elucidate the influence of Lp-PLA2 on carotid atherosclerosis. The plasma Lp-PLA2 activity was measured by using ELISA method and carotid intimal-media thickness (IMT was performed by ultrasound in all participants. Results Lp-PLA2 activity was significantly increased in MetS subgroups when compared with controls, and was higher in patients with carotid plaques than those without plaques (P 2 was obtained between patients with three and four disorders of metabolic syndrome (P P = 0.029, LDL-cholesterol (β = 0.401, P = 0.000 and waist-hip ratio (β = 0.410, P = 0.000 emerged as significant and independent determinants of Lp-PLA2 activity. Multiple stepwise regression analysis revealed that LDL-cholesterol (β = 0.309, P = 0.000, systolic blood pressure (β = 0.322, P = 0.002 and age (β = 0.235, P = 0.007 significantly correlated with max IMT, and Lp-PLA2 was not an independent predictor for carotid IMT. Conclusions Lp-PLA2 may be a modulating factor for carotid IMT via age and LDL-cholesterol, not independent predictor in the pathophysiological process of carotid atherosclerosis in patients with MetS.

Cytosolic cholesterol ester hydrolase in adrenal cortex

OpenAIRE

Tocher, Douglas R.

1983-01-01

Cholesterol ester hydrolase (CEH) in adrenocortical cytosol was known to be phosphorylated and activated, in response to ACTH in a cAMPdependent protein kinase mediated process. The purification of CEH from bovine adrenocortical cytosol was attempted. The use of detergents to solubilise the enzyme from lipid-rich aggregates was investigated and sodium cholate was found to be effective. A purification procedure using cholate solubilised enzyme was developed. The detergent int...

The importance of cytosolic glutamine synthetase in nitrogen assimilation and recycling

Energy Technology Data Exchange (ETDEWEB)

Bernard, S.M.; Habash, D.Z.

2009-07-02

Glutamine synthetase assimilates ammonium into amino acids, thus it is a key enzyme for nitrogen metabolism. The cytosolic isoenzymes of glutamine synthetase assimilate ammonium derived from primary nitrogen uptake and from various internal nitrogen recycling pathways. In this way, cytosolic glutamine synthetase is crucial for the remobilization of protein-derived nitrogen. Cytosolic glutamine synthetase is encoded by a small family of genes that are well conserved across plant species. Members of the cytosolic glutamine synthetase gene family are regulated in response to plant nitrogen status, as well as to environmental cues, such as nitrogen availability and biotic/abiotic stresses. The complex regulation of cytosolic glutamine synthetase at the transcriptional to post-translational levels is key to the establishment of a specific physiological role for each isoenzyme. The diverse physiological roles of cytosolic glutamine synthetase isoenzymes are important in relation to current agricultural and ecological issues.

Bee Venom Phospholipase A2 Alleviate House Dust Mite-Induced Atopic Dermatitis-Like Skin Lesions by the CD206 Mannose Receptor.

Science.gov (United States)

Shin, Dasom; Choi, Won; Bae, Hyunsu

2018-04-02

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by highly pruritic, erythematous, and eczematous skin plaques. We previously reported that phospholipase A2 (PLA2) derived from bee venom alleviates AD-like skin lesions induced by 2,4-dinitrochlorobenzene (DNCB) and house dust mite extract ( Dermatophagoides farinae extract, DFE) in a murine model. However, the underlying mechanisms of PLA2 action in actopic dermatitis remain unclear. In this study, we showed that PLA2 treatment inhibited epidermal thickness, serum immunoglobulin E (IgE) and cytokine levels, macrophage and mast cell infiltration in the ear of an AD model induced by DFE and DNCB. In contrast, these effects were abrogated in CD206 mannose receptor-deficient mice exposed to DFE and DNCB in the ear. These data suggest that bvPLA2 alleviates atopic skin inflammation via interaction with CD206.

Effect of cytosolic pH on inward currents reveals structural characteristics of the proton transport cycle in the influenza A protein M2 in cell-free membrane patches of Xenopus oocytes.

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Mattia L DiFrancesco

Full Text Available Transport activity through the mutant D44A of the M2 proton channel from influenza virus A was measured in excised inside-out macro-patches of Xenopus laevis oocytes at cytosolic pH values of 5.5, 7.5 and 8.2. The current-voltage relationships reveal some peculiarities: 1. "Transinhibition", i.e., instead of an increase of unidirectional outward current with increasing cytosolic H(+ concentration, a decrease of unidirectional inward current was found. 2. Strong inward rectification. 3. Exponential rise of current with negative potentials. In order to interpret these findings in molecular terms, different kinetic models have been tested. The transinhibition basically results from a strong binding of H(+ to a site in the pore, presumably His37. This assumption alone already provides inward rectification and exponential rise of the IV curves. However, it results in poor global fits of the IV curves, i.e., good fits were only obtained for cytosolic pH of 8.2, but not for 7.5. Assuming an additional transport step as e.g. caused by a constriction zone at Val27 resulted in a negligible improvement. In contrast, good global fits for cytosolic pH of 7.5 and 8.2 were immediately obtained with a cyclic model. A "recycling step" implies that the protein undergoes conformational changes (assigned to Trp41 and Val27 during transport which have to be reset before the next proton can be transported. The global fit failed at the low currents at pHcyt = 5.5, as expected from the interference of putative transport of other ions besides H(+. Alternatively, a regulatory effect of acidic cytosolic pH may be assumed which strongly modifies the rate constants of the transport cycle.

Key role of group v secreted phospholipase A2 in Th2 cytokine and dendritic cell-driven airway hyperresponsiveness and remodeling.

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William R Henderson

Full Text Available Previous work has shown that disruption of the gene for group X secreted phospholipase A2 (sPLA2-X markedly diminishes airway hyperresponsiveness and remodeling in a mouse asthma model. With the large number of additional sPLA2s in the mammalian genome, the involvement of other sPLA2s in the asthma model is possible - in particular, the group V sPLA2 (sPLA2-V that like sPLA2-X is highly active at hydrolyzing membranes of mammalian cells.The allergen-driven asthma phenotype was significantly reduced in sPLA2-V-deficient mice but to a lesser extent than observed previously in sPLA2-X-deficient mice. The most striking difference observed between the sPLA2-V and sPLA2-X knockouts was the significant impairment of the primary immune response to the allergen ovalbumin (OVA in the sPLA2-V(-/- mice. The impairment in eicosanoid generation and dendritic cell activation in sPLA2-V(-/- mice diminishes Th2 cytokine responses in the airways.This paper illustrates the diverse roles of sPLA2s in the immunopathogenesis of the asthma phenotype and directs attention to developing specific inhibitors of sPLA2-V as a potential new therapy to treat asthma and other allergic disorders.