A novel phospholipase A2 from human placenta

Buhl, W J; Eisenlohr, Liisa M.; Preuss, Ilka; Gehring, Ulrich

doi:10.1042/bj3110147

Cited by 13 publications

(7 citation statements)

References 46 publications

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“…Indeed, there are actually three groups of PLA # that can be distinguished according to their sensitivity to Ca# + \EGTA, DTT, pBPB, heat, H # SO % , nucleotides and different substrates [9][10][11][12][13]18] : sPLA # (subgroups I, II and III), cPLA # and iPLA # (subgroups I, II and III). In the future, this operational classification will have to be refined as more PLA # enzymes are cloned and characterized and other groups (or subgroups) delineated [14][15][16]. When we compare the characteristics of RPE-PLA # with those of sPLA # , cPLA # and iPLA # (Table 4), we conclude that the RPE-PLA # enzymes are…”

Section: Rpe Probably Contains Two Different Pla 2 Enzymesmentioning

confidence: 97%

“…This is an operational classification which is widely accepted and used to characterize PLA # , as well as to define procedures to purify them from new sources. In the future, this classification will certainly be refined, since recent results from Thomson and Clark [14], Buhl et al [15] and Soubeyrand et al [16] suggest that other groups or subgroups could be needed to describe newly discovered and cloned PLA # . We have recently demonstrated [17] that PLA # activity is present in bovine retinal pigment epithelium (RPE), a subretinal fraction that is enriched with RPE cells.…”

Section: Introductionmentioning

confidence: 99%

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Bovine retinal pigment epithelium contains novel types of phospholipase A2

Jacob

Weech

Salesse

1997

Biochemical Journal

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We have recently demonstrated the presence of phospholipase A2 (PLA2) activity in cells from bovine retinal pigment epithelium (RPE) [Jacob et al. (1996) J. Biol. Chem. 271, 19209-19218]. We report here our results on the characterization of this RPE-PLA2 activity. We show that RPE probably contains two types of PLA2 enzyme, as indicated by the results obtained with different PLA2-active fractions eluted from cation-exchange columns and treated with Ca2+/EGTA, dithiothreitol, p-bromophenacyl bromide or heat. These results, in addition to those from PLA2 assays using different substrates, also suggest that RPE-PLA2 enzymes are different from the well-known secretory, cytoplasmic and Ca2+-independent forms. Sequential extraction of RPE with (1) isotonic, (2) hypertonic and (3) detergent-containing PBS argues for the presence of weakly membrane-associated enzymes. Control experiments using 'back and forth' TLC allowed us to discriminate between PLA2 and phospholipase C/diacylglycerol lipase activity and confirmed that, in our assay conditions, the release of fatty acids was indeed due to PLA2 enzymes. These results, together with those obtained by treating RPE homogenates with H2SO4, guanosine 5'-[gamma-thio]triphosphate, ATP and different protease inhibitors, permitted us to make the first characterization of these RPE-PLA2 enzymes. We conclude that RPE contains novel types of PLA2 that are different from the secretory, cytoplasmic and Ca2+-independent forms.

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Section: Rpe Probably Contains Two Different Pla 2 Enzymesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Bovine retinal pigment epithelium contains novel types of phospholipase A2

Jacob

Weech

Salesse

1997

Biochemical Journal

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“…The iPLA2 class is very heterogeneous and has been further divided into three groups, based on their biochemical characteristics (Ackermann and Dennis 1995). Interestingly, novel types of mammalian PLA2s have also been recently characterized, suggesting that the PLA2 classification will have to be refined and that new classes or groups of PLA2s might be needed (Buhl et al 1995;Jacob et al 1997;Soubeyrand et al 1997;Thomson and Clark 1995).…”

Section: Introductionmentioning

confidence: 99%

Human retinal pigment epithelium secretes a phospholipase A2 and contains two novel intracellular phospholipases A2

Themsche¹,

Jacob²,

Salesse³

2001

Biochem. Cell Biol.

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The sensitivity of different phospholipase A2 (PLA2)-active fractions eluted from cation-exchange chromatography to para-bromophenacylbromide (pBPB), Ca2+-EGTA, DTT, heat, and H2SO4 indicates that human cultured retinal pigment epithelial (hRPE) cells probably contain two different intracellular PLA2 enzymes. Control experiments using "back-and-forth" thin-layer chromatography confirmed that, in our assay conditions, the generation of free fatty acids originated solely from PLA2 activity. Together with immunoblot experiments where no cross-reactivity was observed between the hRPE cytosolic PLA2 enzymes and several antisera directed against secretory PLA2s (sPLA2s) and cytosolic PLA2 (cPLA2), these findings suggest that intracellular hRPE PLA2s are different from well-known sPLA2s, cPLA2, and Ca2+-independent PLA2s. We also report an additional hRPE-PLA2 enzyme that is secreted and that exhibits sensitivity to pBPB, Ca2+-EGTA, DTT, heat, and H2SO4, which is characteristic of sPLA2 enzymes. This approximately 22-kDa PLA2 cross-reacted weakly with an antiserum directed against porcine pancreatic group I sPLA2 but strongly with an antiserum directed against N-terminal residues 1-14 of human synovial group II sPLA2, suggesting that this extracellular enzyme is a member of the sPLA2 class of enzymes. We thus conclude that there are three distinct PLA2 enzymes in cultured hRPE cells, including two novel intracellular PLA2s and a 22-kDa secreted sPLA2 enzyme.

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“…Of major importance are the reaction by-products of PLA 2 activity, a free fatty acid and a lysophospholipid. The fatty acid is often arachidonic acid, one of the main constituents of the cell membrane in several tissues (15)(16)(17). Arachidonic acid is the precursor for inflammatory mediators such as thromboxanes, leukotrienes, and prostaglandins (18,19).…”

mentioning

confidence: 99%

Functional Characteristics of a Phospholipase A2Inhibitor from Notechis ater Serum

Hains

Sung

Tseng

et al. 2000

Journal of Biological Chemistry

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A phospholipase A 2 inhibitor has been purified from the serum of Notechis ater using DEAE-Sephacel chromatography. The inhibitor was found to be composed of two protein subunits (␣ and ␤) that form the intact complex of approximately 110 kDa. The ␣-chain is a 30-kDa glycoprotein and the ␤-chain a nonglycosylated, 25-kDa protein. N-terminal sequence analysis reveals a high level of homology to other snake phospholipase A 2 inhibitors. The inhibitor was shown to be extremely pH and temperature stable. The inhibitor was tested against a wide variety of phospholipase A 2 enzymes and inhibited the enzymatic activity of all phospholipase A 2 enzymes tested, binding with micromole to nanomole affinity. Furthermore, the inhibitor was compared with the Eli-Lilly compound LY311727 and found to have a higher affinity for human secretory nonpancreatic phospholipase A 2 than this chemical inhibitor. The role of the carbohydrate moiety was investigated and found not to affect the in vitro function of the inhibitor.For many years research on PLA 2 1 enzymes has centred on snake venom PLA 2 s, largely because of the fact that PLA 2 enzymes are extremely abundant in snake venoms and are easily purified. PLA 2 enzymes have also been identified and purified from bovine, porcine, and human pancreas (1-3) and in human synovial fluid aspirates from rheumatoid and osteoarthritis patients (4, 5). PLA 2 enzymes have been grouped according to structural and sequence characteristics. Pancreatic PLA 2 enzymes belong to group I, whereas the human secretory nonpancreatic PLA 2 is a group II enzyme. PLA 2 enzymes from snake venom belong to group I or II (6 -8).Recently PLA 2 enzymes have been implicated as playing a role in a range of diseases including rheumatoid and osteoarthritis, asthma, acute pancreatitis, psoriasis, multiple organ failure, septic shock, and adult respiratory distress syndrome (9 -11). Several review articles (9,10,(12)(13)(14) have examined the physiological and potential disease role of hsPLA 2 -II. Of major importance are the reaction by-products of PLA 2 activity, a free fatty acid and a lysophospholipid. The fatty acid is often arachidonic acid, one of the main constituents of the cell membrane in several tissues (15)(16)(17). Arachidonic acid is the precursor for inflammatory mediators such as thromboxanes, leukotrienes, and prostaglandins (18,19). Lysophospholipids are the precursor of platelet activating factor (20).The suggestion that PLA 2 enzymes play a role in diseases process has intensified research on PLA 2 inhibitors. Many investigators have purified and characterized PLIs from numerous sources including plant, fungi, and bacteria (21-28). A large research effort has gone into the design of synthetic compounds, such as the Eli-Lilly compound LY311727, which specifically inhibits hsPLA 2 -II (29). Additionally, a number of PLIs have been purified from the serum of elapid and crotalid snakes. These PLIs have all been shown to be homologous or heterologous complexes that interact with PLA 2 enzymes to inhib...

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A novel phospholipase A2 from human placenta

Cited by 13 publications

References 46 publications

Bovine retinal pigment epithelium contains novel types of phospholipase A2

Bovine retinal pigment epithelium contains novel types of phospholipase A2

Human retinal pigment epithelium secretes a phospholipase A2 and contains two novel intracellular phospholipases A2

Functional Characteristics of a Phospholipase A2Inhibitor from Notechis ater Serum

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