The presence of phospholipase A2 in bovine adrenal medulla: Arguments for more than one type of phospholipase A2

Petit, Koen; Miserez, Bernard; Block, Jan De; Dessel, G. Van; Potter, W.P. De

doi:10.1016/0005-2760(92)90039-x

Cited by 13 publications

(6 citation statements)

References 23 publications

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“…They have also reported that PLA2-I plays a role in the migration of vascular smooth muscles via specific binding sites [19]. PLA2-I has also been shown to be present in bovine adrenal medulla [20], rat gastric mucosa and lung [21] and rat glandular stomach [22]. PLA2s from group II (PLA2-II) are involved in cellular arachidonic acid release and inflammation [4,5,23].…”

Section: Febslettersmentioning

confidence: 99%

Enhancing factor protein from mouse small intestines belongs to the phospholipase A2 family

Mulherkar

Rao

et al. 1993

FEBS Letters

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Enhancing factor (EF), a growth regulatory molecule, isolated from mouse small intestines, has been well characterized in this laboratory. It increases the binding of epidermal growth factor in a unique manner via its own receptor. In the first 20 N-terminal amino acids sequenced, EF showed 50% homology to human Group II phospholipase A2 (PLA2). Here we propose that EF is yet another, unidentified isoform of PLA2 which regulates cell proliferation via modulation of EGF binding. To our knowledge, this is the first report implicating PLA2-II-like molecules in growth regulation.

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Section: Febslettersmentioning

confidence: 99%

Enhancing factor protein from mouse small intestines belongs to the phospholipase A2 family

Mulherkar

Rao

et al. 1993

FEBS Letters

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“…The purified PLA, reported here is thus clearly stimulated by Ca t ' . Nevertheless, the unpurified cytosolic PLA, seems not to be affected by Ca" (Petit et al, 1992) . Moreover, addition of EGTA positively influenced the unpurified enzymatic activity .…”

Section: Discussionmentioning

confidence: 84%

“…Preparation of bovine adrenal medulla total homogenate was performed as described previously (Petit et al ., 1992) . The homogenate, containing 1 mM phenylmethanesulfonyl fluoride, was centrifuged at 650 g,,x for 10 min in an MSE 6 X 300 fixed-angle rotor (Kontron) to remove cell debris and unbroken cells.…”

Section: Purification Of Plazmentioning

confidence: 99%

“…PLA2 activity was identified and characterized in brain fractions (Gray and Strickland, 1982;Baba et al, 1986;Yoshihara and Watanabe, 1990;Hirashima et al, 1992) as well as in sympathetic ganglia (Quik, 1987) . Recently, a Cytosolic PLA, was also demonstrated in bovine adrenal medulla (Petit et al, 1992) . Because chromaffin cells are often used as a model for exocytosis and in view of the possible role of PLA2 in this process, a characterization of this enzyme would be most interesting .…”

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confidence: 97%

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Isolation and Characterization of a Cytosolic Phospholipase A₂ from Bovine Adrenal Medulla

Petit

Block

Potter

1995

Journal of Neurochemistry

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We have recently demonstrated that bovine adrenal medulla contains a soluble phospholipase A2 (PLA2), which is localized in the cytosol. In the present study, this PLA2 was purified 1,097‐fold using sequential concanavalin A, hydrophobic interaction, anion exchange, gel filtration, and an additional anion exchange chromatography. The enzyme is activated over the range of 20–1,000 µM Ca2+ and has a pH optimum near 8.0. On sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, the protein has a molecular mass of 26 kDa and an isoelectric point of 4.6 as revealed by isoelectric focusing. The cytosolic PLA2 is not inhibited by NaCl, and the enzymatic activity is stimulated at low concentrations of Triton X‐100 (0.01%) and deoxycholate (1 mM) but inhibited at higher concentrations (0.1% and 3 mM, respectively) of these detergents. Furthermore, heat treatment (57°C, 5 min) reduced the enzymatic activity by 80%, whereas glycerol (30%) increased the activity. p‐Bromophenacylbromide, a frequently used irreversible inhibitor of type II PLA2, has little effect until 100 µM, and 2–10 mM dithiothreitol totally inactivated the enzyme. The purified PLA2 displays a preference for phosphatidylcholine as a substrate but hydrolyzes phospholipid substrates with arachidonic acid or linoleic acid esterified at the sn‐2 position to the same extent. It is concluded that the chromaffin cell cytosolic PLA2, which was isolated and characterized in this study, represents a type of PLA2 that has not been formerly reported in chromaffin cells. Additional research on the chromaffin cell cytosolic PLA2 will help to reveal whether the enzyme is important for exocytosis.

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“…In chromaffin cells, the release of arachidonic acid has been ascribed to either activation of phospholipase A2 (Petit et al, 1992) or sequential action of phospholipase C and diacylglycerol lipase (Rindlisbacher et al, 1990). As G-proteins are involved in activation of both phospholipase C and phospholipase A2, we used specific inhibitors to determine the actual pathway by which mastoparan stimulates arachidonic acid release.…”

Section: Um Ca2+mentioning

confidence: 99%

Exocytosis in chromaffin cells: evidence for a MgATP-independent step that requires a pertussis toxin-sensitive GTP-binding protein

Vitale

Thiersé

Aunis

et al. 1994

Biochemical Journal

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We have previously described that mastoparan, an amphiphilic tetradecapeptide that activates heterotrimeric G-proteins, inhibits Ca(2+)-induced MgATP-dependent secretion from streptolysin-O-permeabilized chromaffin cells [Vitale, Mukai, Rouot, Thiersé, Aunis and Bader (1993) J. Biol. Chem. 268, 14715-14723]. Our observations suggest the involvement of an inhibitory G(o)-protein, possibly located on the membrane of secretory granules, in the final stages of the exocytotic pathway in chromaffin cells. Here, we demonstrate that mastoparan is also able to stimulate the Ca(2+)-dependent secretion of catecholamines in the absence of MgATP in the medium. This MgATP-independent secretion is totally blocked by tetanus toxin, a potent inhibitor of exocytosis in all neurosecretory cells so far investigated, suggesting that the mastoparan target is a component of the exocytotic machinery. Mas17, a mastoparan analogue inactive on G-proteins, had no effect on catecholamine secretion whereas both Mas7, a highly active analogue of mastoparan, and AlF4-, which selectively activates trimeric G-proteins, triggered MgATP-independent secretion. Non-hydrolysable GTP analogues (GTP[S] and p[NH]ppG) mimicked the dual effects of mastoparan on secretion: they inhibited exocytosis in the presence of MgATP and stimulated MgATP-independent secretion. The different potencies displayed by these two analogues suggest the involvement of two distinct G-proteins. Accordingly, the mastoparan-induced MgATP-independent secretion is highly sensitive to pertussis toxin (PTX) whereas the inhibition by mastoparan of secretion in the presence of MgATP is resistant to PTX treatment. When permeabilized cells were incubated with mastoparan, the release of arachidonic acid increased in a PTX-sensitive manner. 7,7-Dimethyl-5,8-eicosadienoic acid, a potent inhibitor of intracellular phospholipase A2, inhibited both the arachidonate release and the MgATP-independent catecholamine secretion evoked by mastoparan. In contrast, neomycin, an inhibitor of phospholipase C, had no significant effect on either the release of arachidonic acid or the secretion of catecholamines provoked by mastoparan. We conclude that two distinct heterotrimeric G-proteins act in series in the exocytotic pathway in chromaffin cells: one controls an ATP-dependent priming step through an effector pathway that remains to be determined, and the second is involved in a late Ca(2+)-dependent step which does not require MgATP but possibly involves the generation of arachidonic acid.

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The presence of phospholipase A2 in bovine adrenal medulla: Arguments for more than one type of phospholipase A2

Cited by 13 publications

References 23 publications

Enhancing factor protein from mouse small intestines belongs to the phospholipase A2 family

Enhancing factor protein from mouse small intestines belongs to the phospholipase A2 family

Isolation and Characterization of a Cytosolic Phospholipase A₂ from Bovine Adrenal Medulla

Exocytosis in chromaffin cells: evidence for a MgATP-independent step that requires a pertussis toxin-sensitive GTP-binding protein

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The presence of phospholipase A2 in bovine adrenal medulla: Arguments for more than one type of phospholipase A2

Cited by 13 publications

References 23 publications

Enhancing factor protein from mouse small intestines belongs to the phospholipase A2 family

Enhancing factor protein from mouse small intestines belongs to the phospholipase A2 family

Isolation and Characterization of a Cytosolic Phospholipase A2 from Bovine Adrenal Medulla

Exocytosis in chromaffin cells: evidence for a MgATP-independent step that requires a pertussis toxin-sensitive GTP-binding protein

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Isolation and Characterization of a Cytosolic Phospholipase A₂ from Bovine Adrenal Medulla