Nonbactericidal secreted phospholipase A2s are potential anti-inflammatory factors in the mammary gland.

The recent burst of duplication and divergence of the bovine PLA2G2D genes is considered typical of immune response genes, and it was recently shown that PLA2G2D is abundantly expressed in mouse leukocytes and acts as an immunosuppressive phospholipase. Analysis of 1,143 Holstein bulls indicated that the four common haplotypes spanning PLA2G2D display copy number variation ranging from 1 to 4 per haploid genome. Association of the fourth haplotype with negative total merit remained significant (P < 0.002) when corrected for population relatedness. We compared the lipase and bactericidal activities of bovine pancreatic PLA2G1B with human PLA2G2A and G2D and bovine PLA2G2D1 and G2D4 proteins, which had been subcloned, expressed, and refolded by us, and the impact of point mutations in the calcium binding site was investigated. All tested phospholipases were ineffective bactericides of Escherichia coli isolated from bovine mastitis. However, in lactating mice treated with E. coli or lipopolysaccharide (LPS), intramammary injection of bovine PLA2G1B relieved visual and histological inflammation and reduced blood levels of infiltrating lactose. Further studies are warranted to determine whether the observed anti-inflammatory effect involves competitive binding of the receptor Pla2r1 which may mimic the LPS resistance effect in Pla2r1-deficient mice.

Subcellular localization and lysophospholipase/transacylation activities of human group IVC phospholipase A2 (cPLA2gamma).

cPLA2gamma was identified as an ortholog of cPLA2alpha, which is a key enzyme in eicosanoid production. cPLA2gamma was reported to be located in endoplasmic reticulum (ER) and mitochondria and to have lysophospholipase activity beside phospholipase A2 (PLA2) activity. However, subcellular localization, mechanism of membrane binding, regulation and physiological function have not been fully established. In the present study, we examined the subcellular localization and enzymatic properties of cPLA2gamma with C-terminal FLAG-tag. We found that cPLA2gamma was located not only in ER but also mitochondria even in the absence of the prenylation. Purified recombinant cPLA2gamma catalyzed an acyltransferase reaction from one molecule of lysophosphatidylcholine (LPC) to another, forming phosphatidylcholine (PC). LPC or lysophosphatidylethanolamine acted as acyl donor and acceptor, but lysophosphatidylserine, lysophosphatidylinositol and lysophosphatidic acid (LPA) did not. PC and phosphatidylethanolamine (PE) also acted as weak acyl donors. Reaction conditions changed the balance of lysophospholipase and transacylation activities, with addition of LPA/PA, pH>8, and elevated temperature markedly increasing transacylation activity; this suggests that lysophospholipase/transacylation activities of cPLA2gamma may be regulated by various factors. As lysophospholipids are known to accumulate in ischemia heart and to induce arryhthmia, the cPLA2gamma that is abundant in heart may have a protective role through clearance of lysophospholipids by its transacylation activity.

1-Indol-1-yl-propan-2-ones and related heterocyclic compounds as dual inhibitors of cytosolic phospholipase A(2)alpha and fatty acid amide hydrolase.

Cytosolic phospholipase A(2)alpha (cPLA(2)alpha) and fatty acid amide hydrolase (FAAH) are enzymes, which have emerged as attractive targets for the development of analgetic and anti-inflammatory drugs. We recently reported that 1-[3-(4-octylphenoxy)-2-oxopropyl]indole-5-carboxylic acid (10) and related compounds are inhibitors of cPLA(2)alpha. Since cPLA(2)alpha and FAAH possess several common structural features, we now screened this substance series together with some new derivatives for FAAH inhibition. Some of the assayed compounds proved to be selective cPLA(2)alpha inhibitors, while others showed high FAAH and moderate cPLA(2)alpha inhibitory potency. Furthermore, several derivatives were favorably active against both enzymes and, therefore, could represent agents, which have improved analgetic and anti-inflammatory qualities in comparison with selective cPLA(2)alpha and FAAH inhibitors.

Antimyotoxic Activity of Synthetic Peptides Derived from Bothrops atrox Snake Gamma Phospholipase A2 Inhibitor Selected by Virtual Screening.

BACKGROUND: Several studies have aimed to identify molecules that inhibit the toxic actions of snake venom phospholipases A2 (PLA2s). Studies carried out with PLA2 inhibitors (PLIs) have been shown to be efficient in this assignment. OBJECTIVE: This work aimed to analyze the interaction of peptides derived from Bothrops atrox PLIγ (atPLIγ) with a PLA2 and to evaluate the ability of these peptides to reduce phospholipase and myotoxic activities. METHODS: Peptides were subjected to molecular docking with a homologous Lys49 PLA2 from B. atrox venom modeled by homology. Phospholipase activity neutralization assay was performed with BthTX-II and different ratios of the peptides. A catalytically active and an inactive PLA2 were purified from the B. atrox venom and used together in the in vitro myotoxic activity neutralization experiments with the peptides. RESULTS: The peptides interacted with amino acids near the PLA2 hydrophobic channel and the loop that would be bound to calcium in Asp49 PLA2. They were able to reduce phospholipase activity and peptides DFCHNV and ATHEE reached the highest reduction levels, being these two peptides the best that also interacted in the in silico experiments. The peptides reduced the myotubes cell damage with a highlight for the DFCHNV peptide, which reduced by about 65%. It has been suggested that myotoxic activity reduction is related to the sites occupied in the PLA2 structure, which could corroborate the results observed in molecular docking. CONCLUSION: This study should contribute to the investigation of the potential of PLIs to inhibit the toxic effects of PLA2s.

D609, an inhibitor of phosphatidylcholine-specific phospholipase C, inhibits group IV cytosolic phospholipase A2.

As an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), D609 has been widely used to explain the role of PC-PLC in various signal transduction pathways. This study shows that D609 inhibits group IV cytosolic phospholipase A2 (cPLA2), but neither secretory PLA2 nor a Ca2+ -dependent PLA2. Dixon plot analysis shows a mixed pattern of noncompetitive and uncompetitive inhibition with Ki = 86.25 microM for the cPLA2 purified from bovine spleen. D609 also time- and dose-dependently reduces the release of arachidonic acid from a Ca2+- ionophore A23187-stimulated MDCK cells. In the AA release experiment, IC50 of D609 was approximately 375 microM, suggesting that this reagent may not enter the cells easily. The present study indicates that the inhibitory effects of D609 on various cellular responses may be partially attributable to the inhibition of cPLA2.

Structural and functional characterization of a γ-type phospholipase A2 inhibitor from bothrops jararacussu snake plasma.

Phospholipases A2 (PLA2s) from snake venoms comprise a group of 14-18 kDa proteins, responsible for several toxic effects induced by the whole venom. Considering this, studies aiming at the search for natural inhibitors of these proteins are very important. The present work had as objectives the isolation and functional/structural characterization of a γ-type phospholipase A2 inhibitor (PLI) from Bothrops jararacussu snake plasma, named γBjussuMIP. This acidic glycoprotein was isolated in a high purity level through affinity chromatography on CNBr-Sepharose 4B coupled with BthTXII, showing a pI ∼ 5.5 and molecular weight of 23,500 for the monomer (determined by SDS-PAGE), and 160,000 for the oligomer (determined by molecular exclusion chromatography on Sephacryl S-200). The interaction between γBjussuMIP (MIP) and Phospholipase A2 (PLA2) was confirmed using circular dichroism (CD) and emission fluorescence techniques. The helical content of the 1:1 molar mixture was higher than that calculated for the addition of the spectra of the unbound proteins indicating binding. The emission fluorescence experiments pointed that Trp residues in PLA2 participate in proteins interaction as blue shift of 4 nm was observed. The γBjussuMIP cDNA, obtained by PCR of the liver of B. jararacussu snake, revealed 543 bp codifying for a mature protein of 181 amino acid residues. Alignment of its amino acid sequence with those of other snake γPLIs showed 89-94% of similarity. γBjussuMIP mainly inhibited the pharmacological properties of Asp49 PLA2s, such as phospholipase, anticoagulant, myotoxic, edema inducing, cytotoxic, bactericidal and lethal activities. In addition, it showed to be able to supplement Bothrops antivenom, potentiating its antimyotoxic effect. The aspects broached in this work will be able to provide complementary information on possible mechanisms of action, relating structure and function, which could result in a better understanding of the inhibitory effects induced by γBjussuMIP.