Search results for "PHOSPHOLIPASE A(2)"
showing 10 items of 70 documents
Insulin-like growth factors counteract the effect of interleukin 1 beta on type II phospholipase A2 expression and arachidonic acid release by rabbit…
1994
International audience; Interleukin 1 beta was found to stimulate arachidonic acid release, and the synthesis and secretion of type II phospholipase A2 by rabbit articular chondrocytes in vitro. Interleukin 1 beta had no effect on the level of cytosolic phospholipase A2 mRNA. Insulin-like growth factors, which help stabilize the cartilage matrix, reduced the effect of interleukin 1 beta on type II phospholipase A2 activity and mRNA level, and decreased the Interleukin 1 beta-stimulated arachidonic acid release to the basal values. This suggests that type II phospholipase A2 plays a key role in arachidonic acid release from rabbit articular chondrocytes and that insulin-like growth factors c…
Release of canine parvovirus from endocytic vesicles
2003
Canine parvovirus (CPV) is a small nonenveloped virus with a single-stranded DNA genome. CPV enters cells by clathrin-mediated endocytosis and requires an acidic endosomal step for productive infection. Virion contains a potential nuclear localization signal as well as a phospholipase A(2) like domain in N-terminus of VP1. In this study we characterized the role of PLA(2) activity on CPV entry process. PLA(2) activity of CPV capsids was triggered in vitro by heat or acidic pH. PLA(2) inhibitors inhibited the viral proliferation suggesting that PLA(2) activity is needed for productive infection. The N-terminus of VP1 was exposed during the entry, suggesting that PLA(2) activity might have a …
Induction of apoptosis by arachidonic acid in human retinoblastoma Y79 cells: involvement of oxidative stress
2000
Arachidonic acid administration caused apoptosis in Y79 cells, as shown by typical morphological changes, phosphatidylserine externalization, chromatin condensation, processing and activation of caspase-3 and cleavage of the endogenous caspase substrate poly-(ADP-ribose)-polymerase. Arachidonic acid also caused lamin B cleavage, suggesting caspase-6 activation. Arachidonic acid treatment was accompanied by increased formation of the lipid peroxidation end products malondialdehyde and 4-hydroxy-2-nonenal, lowering in reduced glutathione content and in mitochondrial membrane potential. Inhibiting glutathione synthesis sensitized Y79 cells to apoptosis-inducing stimuli, whilst replenishing red…
Activation of bee venom phospholipase A2 through a peptide-enzyme complex
1995
AbstractPhospholipase A2 activation by membrane-bound peptides was investigated in order to understand the role of the membrane-induced conformation on activation, and to examine the occurrence of a peptide-enzyme complex at the lipid/water interface. For the peptides studies, bee venom phospholipase A2 was stimulated regardless of the membrane-bound conformation (α-helix, β-sheet or random coil). Using antisera raised against melittin, we were able to demonstrate the occurrence of a calcium-dependent complex involving the enzyme, phospholipid substrate, and peptide.
The metabolic cascade leading to eicosanoid precursors--desaturases, elongases, and phospholipases A2--is altered in Zucker fatty rats.
2010
Abstract Metabolic syndrome characterized by insulin resistance and obesity is accompanied by severe lipid metabolism perturbations and chronic low-grade inflammation. However, many unresolved questions remained regarding the regulation that underlie dyslipidemia, particularly the regulation of the metabolic cascade (synthesis and release) leading to eicosanoid precursors release. This study was undertaken to investigate the regulation of desaturases/elongases and phospholipases A2 during the establishment of metabolic syndrome. Our results showed that delta-6 desaturase as well as elongase-6 expressions were upregulated in 3-month-old Zucker fatty rats as compared to lean littermates, inde…
A lytic mechanism based on soluble phospholypases A2 (sPLA2) and b-galactoside specific lectins is exerted by Ciona intestinalis (ascidian) unilocula…
2011
Abstract Hemocytes from the ascidian Ciona intestinalis exert in vitro Ca 2+ -dependent cytotoxic activity toward mammalian erythrocytes and K562 cells. To examine the lytic mechanism, hemocyte populations were separated (B1–B6 bands) through a Percoll discontinuous density gradient, the hemocyte cytotoxic activity (HCA) and the lytic activity of the hemocyte lysate supernatant (HLS) were assayed. In addition the separated hemocytes were cultured and the cell-free culture medium (CFM) assayed after 3 h culture. Results support that unilocular refractile hemocytes (URGs), enriched in B5, are cytotoxic. The B5-HLS contains lysins and the activity of B5-CFM shows that lysins can be released in…
Characterization of Acylating and Deacylating Activities of an Extracellular Phospholipase A2 in a Water-Restricted Environment
1994
The behavior of porcine pancreatic phospholipase A2 (ppPLA2) in monophasic low-water media has been explored, for the first time, in a systematic manner. It has been investigated how a number of variables can modulate both acylating and deacylating activities of the enzyme, and several interesting, unexpected results are presented. Among the most relevant, when placing ppPLA2 in the water-restricted environment, are the following: (i) it displays a remarkable alteration of its specificity toward the substrate polar head relative to all-water medium; (ii) it is quite severely inhibited by lysophosphatidylcholine (LPC), which has important implications, particularly concerning its acylation a…
Potassium regulates IL-1 beta processing via calcium-independent phospholipase A2.
2000
Abstract We report that potassium leakage from cells leads to activation of the Ca2+-independent phospholipase A2 (iPLA2), and the latter plays a pivotal role in regulating the cleavage of pro-IL-1β by the IL-converting enzyme caspase-1 in human monocytes. K+ efflux led to increases of cellular levels of glycerophosphocholine, an unambiguous indicator of phospholipase A2 activation. Both maturation of IL-1β and formation of glycerophosphocholine were blocked by bromoenol lactone, the specific iPLA2 inhibitor. Bromoenol lactone-dependent inhibition of IL-1β processing was not due to perturbation of the export machinery for pro-IL-1β and IL-1β or to caspase-1 suppression. Conspicuously, activ…
Endogenous nitric oxide inhibits leukotriene B4 release from rat alveolar macrophages
1997
Effects of endogenous nitric oxide (NO) on the release of mediators of the lipoxygenase and cyclo-oxygenase pathway from rat alveolar macrophages were studied. Alveolar macrophages, freshly isolated or after 18-h culture, were incubated in (amino acid-free) Krebs medium and labelled with [3H]arachidonic acid. The release of [3H]leukotriene B4 and [3H]prostanoids (separated by high performance liquid chromatography) was determined. A 23187 was used as stimulus, as rising intracellular Ca2+ activates directly the phospholipase A2 and lipoxygenase pathway. A 23187 (10 microM) enhanced [3H]leukotriene B4 release from freshly prepared alveolar macrophages about 65-fold, but only 5- to 6-fold fro…
Isolation of two triterpenoids and a biflavanone with anti-Inflammatory activity from Schinus molle fruits.
2003
Three compounds with anti-inflammatory activity were isolated from Schinus molle fruits. Two of the compounds were identified as 3- epi-isomasticadienolalic acid ( 1), isomasticadienonalic acid ( 2) and chamaejasmin ( 3). Triterpenes 1 and 2, and biflavanone 3 were tested on two models of mice paw inflammation: one of acute inflammation, induced by subcutaneous injection of either phospholipase A (2) (PLA (2)) or carrageenan in the paws of mice, and one of chronic inflammation in the form of eczema, provoked by repeated administration of TPA to the ears of mice. On the PLA (2)-induced mouse paw oedema, only 2 was active (30 mg/kg, 66 % inhibition at 60 min), whereas all compounds reduced th…