Depletion of Intracellular Calcium Stores Activates Smooth Muscle Cell Calcium-independent Phospholipase A2

Wolf, Matthew J.; Wang, Jian; Turk, John; Gross, Richard W.

doi:10.1074/jbc.272.3.1522

Cited by 114 publications

(120 citation statements)

References 45 publications

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“…Paradoxically, in these cells, iPLA 2 ␤ activation seems to be regulated by protein kinase C and is Ca ϩ2 -dependent, although in this case, the authors (18) suggested that this result was due to a calcium-dependent PKC, which, in turn, activated iPLA 2 ␤. In contrast, other studies have shown ligand-stimulated eicosanoid production in cells that have been treated with calcium chelators such as BAPTA and EDTA (35). In agreement with the latter, we show here that chelating intracellular calcium with BAPTA had no significant effect on iPLA 2 ␤ translocation, phosphorylation, or AA release triggered by Fc␥RI, whereas the same BAPTA-AM treatment completely blocked the PAFinduced AA release.…”

Section: Discussioncontrasting

confidence: 41%

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FcγRI-triggered Generation of Arachidonic Acid and Eicosanoids Requires iPLA2 but Not cPLA2 in Human Monocytic Cells

Tay¹,

Melendez

2004

Journal of Biological Chemistry

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Aggregation of receptors for immunoglobulin G (Fc␥Rs) on myeloid cells activates a series of events that are key in the inflammatory response and that can ultimately lead to targeted cell killing by antibody-directed cellular cytotoxicity. Generation of lipid-derived proinflammatory mediators is an important component of the integrated cellular response mediated by receptors for the constant region of immunoglobulins (Fc). We have demonstrated previously that, in interferon-␥-primed U937 cells, the high affinity receptor for IgG, Fc␥RI, is coupled to a novel intracellular signaling pathway that involves the sequential activation of phospholipase D, sphingosine kinase, calcium transients, and protein kinase C isoforms, leading to the activation of the NADPHoxidative burst. Here, we investigate the nature of the phospholipase that regulates arachidonic acid and eicosanoid production. Our data show that Fc␥RI couples to iPLA 2 ␤ for the release of arachidonic acid and the generation of leukotriene B 4 and prostaglandin E 2 . Activation of iPLA 2 ␤ was protein kinase C-dependent; on the other hand, platelet-activating factor triggered cPLA 2 ␣ by means of the mitogen-activated protein kinase pathway. These studies demonstrate that intracellular PLA 2 s can be selectively regulated by different stimuli and suggest a critical role for iPLA 2 ␤ in the intracellular signaling cascades initiated by Fc␥RI and its functional role in the generation of key inflammatory mediators.

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Section: Discussioncontrasting

confidence: 41%

“…by sarco/endoplasmic reticulum calcium ATPase inhibitors, calcium-ionophores, or agonist stimulation; ref. 35). …”

Section: Discussionmentioning

confidence: 99%

FcγRI-triggered Generation of Arachidonic Acid and Eicosanoids Requires iPLA2 but Not cPLA2 in Human Monocytic Cells

Tay¹,

Melendez

2004

Journal of Biological Chemistry

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“…We have demonstrated previously that depletion of internal Ca 2ϩ stores causes activation of iPLA 2 ␤ in ␤-cells (23) and in vascular smooth muscle cells (24). It has been demonstrated recently that iPLA 2 ␤ participates in SOC entry from the extracellular space (25,32), and this process is required for insulin secretion (26 -31).…”

Section: Figmentioning

confidence: 99%

“…CaMKII is an important Ca 2ϩ signaling effector and serves as a gauge that temporally integrates [Ca 2ϩ ] signal intensities (39), and calmodulin participates in several Ca 2ϩ -dependent processes in insulin secretion by ␤-cells (40,41). Calmodulin and iPLA 2 ␤ interact functionally (2,8,23,24,33), and the iPLA 2 ␤ domain from residues 650 -722 contains a calmodulin binding site (2).…”

mentioning

confidence: 99%

“…Depleting intracellular Ca 2ϩ stores activates iPLA 2 ␤ in ␤-cells and vascular smooth muscle cells (23,24), and iPLA 2 ␤ participates in store-operated entry of Ca 2ϩ from the extracellular space (25), which is thought to be involved in glucoseinduced insulin secretion (26 -31). Regulating store-operated calcium (SOC) entry requires that intracellular Ca 2ϩ stores communicate with plasma membrane ion channels, and calmodulin participates in cross-talk between Ca 2ϩ stores and SOC channels (25,32).…”

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confidence: 99%

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Group VIA Phospholipase A2 Forms a Signaling Complex with the Calcium/Calmodulin-dependent Protein Kinase IIβ Expressed in Pancreatic Islet β-Cells

Wang

Ramanadham

Alex

et al. 2005

Journal of Biological Chemistry

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Insulin-secreting pancreatic islet ␤-cells express a Group VIA Ca 2؉ -independent phospholipase A 2 (iPLA 2 ␤) that contains a calmodulin binding site and protein interaction domains. We identified Ca 2؉ /calmodulindependent protein kinase II␤ (CaMKII␤) as a potential iPLA 2 ␤-interacting protein by yeast two-hybrid screening of a cDNA library using iPLA 2 ␤ cDNA as bait. Cloning CaMKII␤ cDNA from a rat islet library revealed that one dominant CaMKII␤ isoform mRNA is expressed by adult islets and is not observed in brain or neonatal islets and that there is high conservation of the isoform expressed by rat and human ␤-cells. Binary two-hybrid assays using DNA encoding this isoform as bait and iPLA 2 ␤ DNA as prey confirmed interaction of the enzymes, as did assays with CaMKII␤ as prey and iPLA 2 ␤ bait. His-tagged CaMKII␤ immobilized on metal affinity matrices bound iPLA 2 ␤, and this did not require exogenous calmodulin and was not prevented by a calmodulin antagonist or the Ca 2؉ chelator EGTA. Activities of both enzymes increased upon their association, and iPLA 2 ␤ reaction products reduced CaMKII␤ activity. Both the iPLA 2 ␤ inhibitor bromoenol lactone and the CaMKII␤ inhibitor KN93 reduced arachidonate release from INS-1 insulinoma cells, and both inhibit insulin secretion. CaMKII␤ and iPLA 2 ␤ can be coimmunoprecipitated from INS-1 cells, and forskolin, which amplifies glucose-induced insulin secretion, increases the abundance of the immunoprecipitatable complex. These findings suggest that iPLA 2 ␤ and CaMKII␤ form a signaling complex in ␤-cells, consistent with reports that both enzymes participate in insulin secretion and that their expression is coinduced upon differentiation of pancreatic progenitor to endocrine progenitor cells.Phospholipases A 2 (PLA 2 ) 1 are a diverse group of enzymes that catalyze hydrolysis of sn-2 fatty acid substituents from glycerophospholipid substrates to yield a free fatty acid and a 2-lysophospholipid (1). The Group VIA PLA 2 designated iPLA 2 ␤ has a molecular mass of 84 -88 kDa and does not require Ca 2ϩ for catalysis (2). Various splice variants of iPLA 2 ␤ are expressed at high levels in testis (3), brain (4), and pancreatic islet ␤-cells (5), among other tissues.Certain nutrients, hormones, neurotransmitters, and pharmacologic agents stimulate insulin secretion from ␤-cells, and the dominant physiologic insulin secretagogue is D-glucose. A series of signals that result from glucose-induced ATP production and alterations of intracellular redox potentials trigger insulin secretion via a rise in cytosolic [Ca 2ϩ ], and Ca 2ϩ /calmodulin-dependent protein kinase II (CaMKII) is an important ␤-cell [Ca 2ϩ ] sensor and mediator of Ca 2ϩ -dependent events in insulin secretion (6 -11). Much evidence (12-22) suggests that iPLA 2 ␤ also participates in insulin secretion, including the facts that the mechanism-based bromoenol lactone (BEL) inhibitor of iPLA 2 ␤ suppresses glucose-induced hydrolysis of arachidonate from islet membrane phospholipids, the rise in ␤-cell cytosolic...

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The Generation of Free Arachidonic Acid

Dieter¹

1999

Prostaglandins, Laukotrienes and Other Eicosanoids

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Depletion of Intracellular Calcium Stores Activates Smooth Muscle Cell Calcium-independent Phospholipase A2

Abstract: Herein we present multiple lines of evidence which demonstrate that depletion of internal calcium stores is both necessary and sufficient for the activation of calcium-independent phospholipase A 2 during arginine vasopressin (

Cited by 114 publications

References 45 publications

FcγRI-triggered Generation of Arachidonic Acid and Eicosanoids Requires iPLA2 but Not cPLA2 in Human Monocytic Cells

FcγRI-triggered Generation of Arachidonic Acid and Eicosanoids Requires iPLA2 but Not cPLA2 in Human Monocytic Cells

Group VIA Phospholipase A2 Forms a Signaling Complex with the Calcium/Calmodulin-dependent Protein Kinase IIβ Expressed in Pancreatic Islet β-Cells

The Generation of Free Arachidonic Acid

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