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Michael H. Gelb - One of the best experts on this subject based on the ideXlab platform.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Abstract Gastric epithelial cells liberate prostaglandin E2 in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-α and interleukin-1β leads to synergistic release of Arachidonate and production of prostaglandin E2. Results with highly specific and potent phospholipase A2 inhibitors and with small interfering RNA show that cytosolic phospholipase A2-α and group IIA secreted phospholipase A2 contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A2 is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A2-α is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A2-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A2, but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A2 were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A2 work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Gastric epithelial cells liberate prostaglandin E(2) in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-alpha and interleukin-1beta leads to synergistic release of Arachidonate and production of prostaglandin E(2). Results with highly specific and potent phospholipase A(2) inhibitors and with small interfering RNA show that cytosolic phospholipase A(2)-alpha and group IIA secreted phospholipase A(2) contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A(2) is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A(2)-alpha is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A(2)-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A(2), but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A(2) were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A(2) work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

  • arachidonic acid release from mammalian cells transfected with human groups iia and x secreted phospholipase a2 occurs predominantly during the secretory process and with the involvement of cytosolic phospholipase a2 α
    Journal of Biological Chemistry, 2004
    Co-Authors: Carine M Mounier, Farideh Ghomashchi, Margaret R Lindsay, Scott E James, Alan G Singer, Robert G Parton, Michael H. Gelb
    Abstract:

    Stable expression of human groups IIA and X secreted phospholipases A(2) (hGIIA and hGX) in CHO-K1 and HEK293 cells leads to serum- and interleukin-1beta-promoted Arachidonate release. Using mutant CHO-K1 cell lines, it is shown that this Arachidonate release does not require heparan sulfate proteoglycan- or glycosylphosphatidylinositol-anchored proteins. It is shown that the potent secreted phospholipase A(2) inhibitor Me-Indoxam is cell-impermeable. By use of Me-Indoxam and the cell-impermeable, secreted phospholipase A(2) trapping agent heparin, it is shown that hGIIA liberates free Arachidonate prior to secretion from the cell. With hGX-transfected CHO-K1 cells, Arachidonate release occurs before and after enzyme secretion, whereas all of the Arachidonate release from HEK293 cells occurs prior to enzyme secretion. Immunocytochemical studies by confocal laser and electron microscopies show localization of hGIIA to the cell surface and Golgi compartment. Additional results show that the interleukin-1beta-dependent release of Arachidonate is promoted by secreted phospholipase A(2) expression and is completely dependent on cytosolic (group IVA) phospholipase A(2). These results along with additional data resolve the paradox that efficient arachidonic acid release occurs with hGIIA-transfected cells, and yet exogenously added hGIIA is poorly able to liberate arachidonic acid from mammalian cells.

  • translocation of the 85 kda phospholipase a2 from cytosol to the nuclear envelope in rat basophilic leukemia cells stimulated with calcium ionophore or ige antigen
    Journal of Biological Chemistry, 1995
    Co-Authors: Sarah Glover, Timothy Bayburt, Mechthild Jonas, Michael H. Gelb
    Abstract:

    Abstract The rat mast cell line RBL-2H3.1 contains an 85-kDa cytosolic phospholipase A2 (cPLA2) that is very likely involved in liberating Arachidonate from membrane phospholipid for the synthesis of eicosanoids following stimulation with either calcium ionophore or IgE/antigen. In this study, the intracellular location of cPLA2 was determined using immunofluorescence microscopy and immuno-gold electron microscopy. In nonstimulated cells, cPLA2 is distributed throughout the cytosol and is excluded from the nucleoplasm. Following cell activation with calcium ionophore, most of the cPLA2 translocates to the nuclear envelope, and the enzyme remains there during the entire period that ionophore is present. With IgE/antigen stimulation for 5 min, approximately 20-30% of the cPLA2 translocates to the nuclear envelope, and after 30 min of stimulation, most of the enzyme returns to the cytosol. Measurement of intracellular calcium using the dye Fura-2/AM shows that the level of calcium rises immediately after antigen is added, remains high for about 30 s, and then declines back to resting levels. Activation with calcium ionophore produces a 10-fold larger release of Arachidonate than does stimulation with IgE/antigen. Thus, the results suggest that the extent of membrane binding of cPLA2 correlates with the release of Arachidonate and that the site of Arachidonate liberation is the nuclear envelope where many of the enzymes that oxygenate this fatty acid are located.

  • tight binding inhibitors of 85 kda phospholipase a2 but not 14 kda phospholipase a2 inhibit release of free Arachidonate in thrombin stimulated human platelets
    Journal of Biological Chemistry, 1994
    Co-Authors: Fulvia Bartoli, Michael H. Gelb, Farideh Ghomashchi, Hung Kuei Lin, Mahendra K Jain, Rafael Apitzcastro
    Abstract:

    An analogue of arachidonic acid in which the COOH group is replaced by a trifluoromethyl ketone group (COCF3) has recently been shown to be a tight binding inhibitor of the 85-kDa cytosolic phospholipase A2 that is found in platelets and other cells (Street, I. P., Lin, H.-K., Laliberte, F., Ghomashchi, F. G., Wang, Z., Perrier, H., Tremblay, N. M., Huang, Z., Weech, P. K., and Gelb, M. H. (1993) Biochemistry 32, 5935-5940). This trifluoromethyl ketone inhibits most of the Arachidonate release from the phospholipid pool in thrombin-stimulated human platelets at concentrations of 0-40 microM with 4 x 10(8) platelets/ml. A structure-function analysis of related compounds reveals a good correlation between the inhibition of the purified phospholipase A2 and the blockage of Arachidonate release in platelets. A number of recently described potent inhibitors of the 14-kDa phospholipase A2 that is secreted from activated platelets have no effect on the level of free Arachidonate production. Furthermore, the addition of a large amount of recombinant 14-kDa phospholipase A2 to platelets does not produce free Arachidonate, and it does not alter the amount of Arachidonate released following platelet activation with thrombin. These studies provide strong pharmacological evidence for the role of the cytosolic phospholipase A2 in producing most, if not all, of the liberated Arachidonate in thrombin-stimulated human platelets, and they show that tight binding membrane-residing inhibitors of the cytosolic phospholipase A2 can block the eicosanoid cascade in living cells.

Zhanglin Ni - One of the best experts on this subject based on the ideXlab platform.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Abstract Gastric epithelial cells liberate prostaglandin E2 in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-α and interleukin-1β leads to synergistic release of Arachidonate and production of prostaglandin E2. Results with highly specific and potent phospholipase A2 inhibitors and with small interfering RNA show that cytosolic phospholipase A2-α and group IIA secreted phospholipase A2 contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A2 is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A2-α is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A2-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A2, but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A2 were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A2 work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Gastric epithelial cells liberate prostaglandin E(2) in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-alpha and interleukin-1beta leads to synergistic release of Arachidonate and production of prostaglandin E(2). Results with highly specific and potent phospholipase A(2) inhibitors and with small interfering RNA show that cytosolic phospholipase A(2)-alpha and group IIA secreted phospholipase A(2) contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A(2) is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A(2)-alpha is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A(2)-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A(2), but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A(2) were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A(2) work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

Brian P. Smart - One of the best experts on this subject based on the ideXlab platform.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Abstract Gastric epithelial cells liberate prostaglandin E2 in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-α and interleukin-1β leads to synergistic release of Arachidonate and production of prostaglandin E2. Results with highly specific and potent phospholipase A2 inhibitors and with small interfering RNA show that cytosolic phospholipase A2-α and group IIA secreted phospholipase A2 contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A2 is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A2-α is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A2-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A2, but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A2 were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A2 work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Gastric epithelial cells liberate prostaglandin E(2) in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-alpha and interleukin-1beta leads to synergistic release of Arachidonate and production of prostaglandin E(2). Results with highly specific and potent phospholipase A(2) inhibitors and with small interfering RNA show that cytosolic phospholipase A(2)-alpha and group IIA secreted phospholipase A(2) contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A(2) is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A(2)-alpha is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A(2)-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A(2), but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A(2) were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A(2) work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

Nicole M. Okeley - One of the best experts on this subject based on the ideXlab platform.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Abstract Gastric epithelial cells liberate prostaglandin E2 in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-α and interleukin-1β leads to synergistic release of Arachidonate and production of prostaglandin E2. Results with highly specific and potent phospholipase A2 inhibitors and with small interfering RNA show that cytosolic phospholipase A2-α and group IIA secreted phospholipase A2 contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A2 is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A2-α is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A2-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A2, but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A2 were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A2 work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

  • intracellular actions of group iia secreted phospholipase a2 and group iva cytosolic phospholipase a2 contribute to arachidonic acid release and prostaglandin production in rat gastric mucosal cells and transfected human embryonic kidney cells
    Journal of Biological Chemistry, 2006
    Co-Authors: Zhanglin Ni, Brian P. Smart, Nicole M. Okeley, Michael H. Gelb
    Abstract:

    Gastric epithelial cells liberate prostaglandin E(2) in response to cytokines as part of the process of healing of gastric lesions. Treatment of the rat gastric epithelial cell line RGM1 with transforming growth factor-alpha and interleukin-1beta leads to synergistic release of Arachidonate and production of prostaglandin E(2). Results with highly specific and potent phospholipase A(2) inhibitors and with small interfering RNA show that cytosolic phospholipase A(2)-alpha and group IIA secreted phospholipase A(2) contribute to Arachidonate release from cytokine-stimulated RGM1 cells. In the late phase of Arachidonate release, group IIA secreted phospholipase A(2) is induced (detected at the mRNA and protein levels), and the action of cytosolic phospholipase A(2)-alpha is required for this induction. Results with RGM1 cells and group IIA secreted phospholipase A(2)-transfected HEK293 cells show that the group IIA phospholipase acts prior to externalization from the cells. RGM1 cells also express group XIIA secreted phospholipase A(2), but this enzyme is not regulated by cytokines nor does it contribute to Arachidonate release. The other eight secreted phospholipases A(2) were not detected in RGM1 cells at the mRNA level. These results clearly show that cytosolic and group IIA secreted phospholipases A(2) work together to liberate Arachidonate from RGM1 cell phospholipids in response to cytokines.

Yuri D Ivashchenko - One of the best experts on this subject based on the ideXlab platform.

  • activation of cytosolic phospholipase a2 by basic fibroblast growth factor via a p42 mitogen activated protein kinase dependent phosphorylation pathway in endothelial cells
    Journal of Biological Chemistry, 1995
    Co-Authors: Gaurisankar Sa, Gurunathan Murugesan, Michael Jaye, Yuri D Ivashchenko
    Abstract:

    Abstract Basic fibroblast growth factor (FGF) stimulates the proliferation, differentiation, and motility of multiple cell types. Signal transduction by FGF is mediated by high affinity FGF receptors that have autophosphorylating tyrosine kinase activity and also elicit the release of low molecular weight signaling molecules, including inositol 1,4,5-trisphosphate, diacylglycerol, and Arachidonate. We have shown previously that basic FGF-stimulated, phospholipase A2 (PLA2)-mediated Arachidonate release regulates endothelial cell (EC) motility (Sa, G., and Fox, P. L.(1994) J. Biol. Chem. 269, 3219-3225). Here we identify the phospholipase responsible for basic FGF-mediated Arachidonate release as cytosolic PLA2 (cPLA2) by demonstrating in EC lysates a requirement for micromolar Ca, dithiothreitol insensitivity, and inactivation by anti-cPLA2 antiserum. The role of cPLA2 is also indicated by the observed mechanisms of activation which show a requirement for p42 mitogen-activated protein kinase activity, cPLA2 phosphorylation, and cPLA2 translocation from cytosol to membranes. Phosphorylation of cPLA2, Arachidonate release from prelabeled intact cells, and cell motility all have similar concentration dependencies on basic FGF. Since Arachidonate release is required for basic FGF-stimulated motility of EC, our results show that p42 mitogen-activated protein kinase activation of cPLA2 may be a regulatory event in stimulation of cellular release of this important eicosanoid precursor during cellular responses to basic FGF.

  • activation of cytosolic phospholipase a by basic fibroblast growth factor via a p42 mitogen activated protein kinase dependent phosphorylation pathway in endothelial cells
    Journal of Biological Chemistry, 1995
    Co-Authors: Gurunathan Murugesan, Michael Jaye, Yuri D Ivashchenko, Paul L Fox
    Abstract:

    Basic fibroblast growth factor (FGF) stimulates the proliferation, differentiation, and motility of multiple cell types. Signal transduction by FGF is mediated by high affinity FGF receptors that have autophosphorylating tyrosine kinase activity and also elicit the release of low molecular weight signaling molecules, including inositol 1,4,5-trisphosphate, diacylglycerol, and Arachidonate. We have shown previously that basic FGF-stimulated, phospholipase A2 (PLA2)-mediated Arachidonate release regulates endothelial cell (EC) motility (Sa, G., and Fox, P.L. (1994) J. Biol. Chem. 269, 3219-3225). Here we identify the phospholipase responsible for basic FGF-mediated Arachidonate release as cytosolic PLA2 (cPLA2) by demonstrating in EC lysates a requirement for micromolar Ca2+, dithiothreitol insensitivity, and inactivation by anti-cPLA2 antiserum. The role of cPLA2 is also indicated by the observed mechanisms of activation which show a requirement for p42 mitogen-activated protein kinase activity, cPLA2 phosphorylation, and cPLA2 translocation from cytosol to membranes. Phosphorylation of cPLA2, Arachidonate release from prelabeled intact cells, and cell motility all have similar concentration dependencies on basic FGF. Since Arachidonate release is required for basic FGF-stimulated motility of EC, our results show that p42 mitogen-activated protein kinase activation of cPLA2 may be a regulatory event in stimulation of cellular release of this important eicosanoid precursor during cellular responses to basic FGF.