Phospholipase D and phosphatidic acid enhance the hydrolysis of phospholipids in vesicles and in cell membranes by human secreted phospholipase A2

Author(s):  
Adrian R Kinkaid ◽  
Roohaida Othman ◽  
Joanne Voysey ◽  
David C Wilton
1997 ◽  
Vol 326 (1) ◽  
pp. 227-233 ◽  
Author(s):  
Kamen KOUMANOV ◽  
Claude WOLF ◽  
Gilbert BÉREZIAT

Conjectural results have been reported on the capacity of inflammatory secreted phospholipase A2 (sPLA2) to hydrolyse mammalian membrane phospholipids. Development of an assay based on the release of non-esterified fatty acids by the enzyme acting on the organized phospholipid mixture constituting the membrane matrix has led to the identification of two prominent effectors, sphingomyelin (SPH) and annexin. Recombinant human type II sPLA2 hydrolyses red-cell membrane phospholipids with a marked preference for the inner leaflet. This preference is apparently related to the high content of SPH in the outer leaflet, which inhibits sPLA2. This inhibition by SPH is specific for sPLA2. Cholesterol counteracts the inhibition of sPLA2 by SPH, suggesting that the SPH-to-cholesterol ratio accounts in vivo for the variable susceptibility of cell membranes to sPLA2. Different effects were observed of the presence of the non-hydrolysable D-α-dipalmitoyl phosphatidylcholine (D-DPPC), which renders the membranes rigid but does not inhibit sPLA2. Annexin VI was shown, along with other annexins, to inhibit sPLA2 activity by sequestering the phospholipid substrate. The present study has provided the first evidence that annexin VI, in concentrations that inhibit hydrolysis of purified phospholipid substrates, stimulated the hydrolysis of membrane phospholipids by sPLA2. The activation requires the presence of membrane proteins. The effect is specific for type II sPLA2 and is not reproducible with type I PLA2. The activation by annexin VI of sPLA2 acting on red cell membranes results in the preferential release of polyunsaturated fatty acids. It suggests that type II sPLA2, in conjunction with annexin VI, might be involved in the final step of endocytosis and/or exocytosis providing the free polyunsaturated fatty acids acting synergistically to cause membrane fusion.


2015 ◽  
Vol 194 (7) ◽  
pp. 3327-3339 ◽  
Author(s):  
Julio M. Rubio ◽  
Juan P. Rodríguez ◽  
Luis Gil-de-Gómez ◽  
Carlos Guijas ◽  
María A. Balboa ◽  
...  

Biochemistry ◽  
1996 ◽  
Vol 35 (29) ◽  
pp. 9375-9384 ◽  
Author(s):  
Joseph Rogers ◽  
Bao-Zhu Yu ◽  
Spyros V. Serves ◽  
Gerasimos M. Tsivgoulis ◽  
Demetrios N. Sotiropoulos ◽  
...  

1992 ◽  
Vol 70 (1) ◽  
pp. 43-48 ◽  
Author(s):  
S. S. Ghosh ◽  
Richard C. Franson

Autoclaved Escherichia coli labelled with [1-14C]oleate in the 2-acyl position have been used extensively to measure phospholipase A2 activity in vitro. The present study demonstrates that this membranous substrate is also useful for the measurement of in vitro phospholipase D activity. Phospholipase D from Streptomyces chromofuscus catalyzed the hydrolysis of [1-14C]oleate labelled, autoclaved E. coli optimally at pH 7.0–8.0 to generate [14C]phosphatidic acid in the presence of 5 mM added Ca2+. Other divalent cations would not substitute for Ca2+. Activity was linear with time and protein up to 30% of the hydrolysis of substrate. Phospholipase D activity was stimulated in a dose-dependent manner by the addition of Triton X-100. The activity was increased 5.5-fold with 0.05% Triton, a concentration that totally inhibited hydrolysis of E. coli by human synovial fluid phospholipase A2. Accumulation of [14C]diglyceride was observed after 10 min of incubation. This accumulation was inhibited by NaF (IC50 = 18 μM) or propanolol (IC50 = 180 μM) suggesting the S. chromofuscus phospholipase D was contaminated with phosphatidate phosphohydrolase. Phosphatidic acid released by the action of cabbage phospholipase D was converted to phosphatidylethanol in an ethanol concentration dependent manner. These results demonstrate that [1-14C]oleate labelled, autoclaved E. coli can be used to measure phospholipase D activity by monitoring accumulation of either [14C]phosphatidic acid or [14C]phosphatidylethanol.Key words: Escherichia coli, substrate, phospholipase D, Streptomyces chromofuscus, sodium fluoride, propranolol.


1969 ◽  
Vol 113 (4) ◽  
pp. 697-705 ◽  
Author(s):  
R. H. Quarles ◽  
R. M. C. Dawson

1. The hydrolysis of monolayers of phosphatidyl[Me−14C]choline at the air/water interface by phospholipase D (phosphatidylcholine phosphatidohydrolase) was investigated by a surface-radioactivity technique by using a flow counter. 2. Phosphatidylcholine of high specific radioactivity was prepared biosynthetically in good yield from [Me−14C]choline by using Saccharomyces cerevisiae. 3. At initial monolayer pressures between 12 and 25 dynes/cm. the hydrolysis occurred in two stages, an initial slow hydrolysis followed by a rapid hydrolysis. Below 3dynes/cm. and above 28dynes/cm. no enzymic hydrolysis of pure phosphatidylcholine monolayers could be detected. 4. The rapid hydrolysis was proportional to the enzyme concentration in the subphase, its pH optimum was 6·6, and 0·2mm-Ca2+ was required for maximal activity. 5. Hydrolysis of the film was accompanied by a pronounced fall in the surface pressure even though the phosphatidic acid formed did not leave the film. When the pressure fell to low values the hydrolysis ceased even if the film was only partially hydrolysed. 6. Above monolayer pressures of 28dynes/cm. enzymic hydrolysis could be initiated by inclusion of phosphatidic acid (and less effectively stearyl hydrogen sulphate) in the film, although the rates were not appreciably higher than those observed at 25dynes/cm. with a pure phosphatidylcholine film. 7. The initiation of the hydrolysis by phosphatidic acid was facilitated by the inclusion of high Ca2+ concentrations and certain carboxylic acid buffer anions in the subphase, although these did not activate by themselves. 8. The initiation of the hydrolysis at high pressures could not be related to any change in the surface potential brought about by the addition of the long-chain anions to the film, nor could it be ascribed to a surface dilution effect. 9. The results are discussed in relation to previous studies on the hydrolysis of phosphatidylcholine particles by the enzyme and also similar investigations on phosphatidylcholine monolayers with other phospholipases.


1993 ◽  
Vol 264 (3) ◽  
pp. C609-C616 ◽  
Author(s):  
A. W. Jones ◽  
S. D. Shukla ◽  
B. B. Geisbuhler

We sought to relate norepinephrine (NE) stimulation of phosphatidic acid (PA) production to functional responses of rat aorta and pathways for PA production. The time course for changes in PA was closely related to Ca-dependent tonic responses in 42K efflux and contraction. NE (30 microM for 1 min) increased PA and reduced phosphatidylcholine (PC) and phosphatidylinositol (PI) based on Pi analyses and 32P labeling of phospholipids. The 32P-to-Pi ratio in PA (0.8 +/- 0.2, n = 13) was similar to PC (0.8 +/- 0.1, n = 14) but was significantly lower (P < 0.001) than PI (4.6 +/- 0.5, n = 14). The 32P-to-Pi ratio in PA was also lower (P < 0.02) than phosphatidylinositol phosphate and phosphatidylinositol bisphosphate. NE also increased [3H]PA twofold (P < 0.05) when PC was selectively labeled with [3H]myristic acid. These observations are more consistent with PA being formed from the hydrolysis of PC by phospholipase D (PLD) than by the phosphorylation of diacylglycerol produced by the action of phospholipase C. PLD was assayed by the formation of phosphatidylethanol (PEt) via a transphosphatidylation reaction with ethanol (half-maximal stimulation at 0.4-0.5% vol/vol). The time course for PLD stimulation by NE was similar to PA, with significant increases (P < 0.002) during 10 s to 30 min exposure. Once formed, PEt was degraded slowly, with a half time > 3 h. It is concluded that NE stimulates PLD in rat aorta, which forms a significant amount of PA from the hydrolysis of PC.(ABSTRACT TRUNCATED AT 250 WORDS)


1995 ◽  
Vol 308 (2) ◽  
pp. 507-512 ◽  
Author(s):  
A R Kinkaid ◽  
D C Wilton

The extracellular concentration of the Group II human non-pancreatic secreted phospholipase A2 (hnpsPLA2) is elevated in a variety of inflammatory disorders. This enzyme is remarkable because it demonstrates almost zero activity with egg phosphatidylcholine (PC) or synthetic dioleoyl-phosphatidylcholine (DOPC) as substrate, but expresses high activity with the anionic phospholipid dioleoyl-phosphatidylglycerol (DOPG), a feature shared with the Group II enzyme from rat liver. The presence of certain membrane-bound anions can enhance hydrolysis of PC by the mammalian secreted PLA2S. In this study the ability of various non-polar anions to stimulate DOPC hydrolysis by secreted PLA2S has been investigated. The naturally occurring membrane anion, cholesterol sulphate, was particularly effective in stimulating the hydrolysis of both DOPC and also 1-stearoyl-2-arachidonyl phosphatidylcholine by hnpsPLA2. Activation of DOPC hydrolysis was also achieved with dioleoyl-phosphatidylserine (DOPS); however, DOPS was less effective than cholesterol sulphate. In contrast, the dianion dioleoyl-phosphatidic acid, a known activator of pig pancreatic PLA2, failed to activate the human enzyme. It remains to be established whether cell plasma-membrane hydrolysis by extracellular hnpsPLA2 can be activated in vivo by the presence of suitable membrane anions such as cholesterol sulphate and thus promote an inflammatory response within the cell.


1993 ◽  
Vol 264 (2) ◽  
pp. C402-C410 ◽  
Author(s):  
J. Ortmeyer ◽  
V. Mohsenin

In neutrophils, N-formyl-Met-Leu-Phe (FMLP) stimulates a respiratory burst with subsequent generation of superoxide anion (O2-.) by NADPH oxidase. Signal transduction involved in this process includes FMLP receptor stimulation of phosphoinositide hydrolysis with formation of inositol 1,4,5-trisphosphate and diacylglycerol and phosphatidylcholine hydrolysis with formation of phosphatidic acid. Generation of these second messengers would lead to activation of NADPH oxidase and generation of O2-.. Neutrophils from diabetic subjects and normal neutrophils exposed to glucose have diminished ability to activate the respiratory burst in response to various agonists. The mechanism of this suppression remains unknown. We report herein that treatment of neutrophils with 15 and 50 mM glucose significantly suppresses the O2-. formation in response to receptor-mediated stimulation. The decreased O2-. generation is associated with marked inhibition of phospholipase D (PLD) activity, with limited hydrolysis of phosphatidylcholine and formation of phosphatidic acid. Sorbitol (50 mM), a nonmetabolizable sugar with a similar osmotic effect, has no influence on O2-. generation or PLD activation. The 4 beta-phorbol 12-myristate 13-acetate (PMA)-induced O2-. generation as well as PLD activation are unaffected by glucose. Furthermore, the intracellular Ca2+ transient in response to FMLP is not influenced by glucose. Taken together, these data suggest that glucose differentially interferes with activation of PLD but not phospholipase C. And, the fact that PMA-induced activation of PLD is not altered by glucose further suggests that a protein kinase C independent step leading to the activation of PLD may be altered by glucose.


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