scholarly journals Characterization of ATP receptor responsible for the activation of phospholipase A2 and stimulation of prostaglandin E2 production in thymic epithelial cells

1995 ◽  
Vol 308 (2) ◽  
pp. 399-404 ◽  
Author(s):  
P Liu ◽  
M Wen ◽  
J Hayashi
Keyword(s):  
Epithelial Cells ◽  
Prostaglandin E2 ◽  
Phospholipase A2 ◽  
Enzymic Activity ◽  
Pge2 Production ◽  
Thymic Epithelial Cells ◽  
Cross Linking ◽  
Atp Binding ◽  
Variant Cell ◽  
Stimulation Of

In TEA3A1 rat thymic epithelial cells, ATP stimulates prostaglandin E2 (PGE2) production through activation of phospholipase A2 (PLA2) enzymic activity. The stimulation of PGE2 production tested with other nucleotides indicated the agonist potency of adenosine 5′-[gamma-thio]triphosphate (ATP[S]) > or = UTP > ATP, with ED50 of about 10 microM for ATP[S]. In TEA3A1 cells, cross-linking studies with ATP[35S] revealed the presence of four cell-surface cross-linked bands of 42 kDa, 53 kDa, 83 kDa and 100 kDa in Triton X-100 extracts of TEA3A1 cells by fluorography. Guanosine 5′-[gamma-thio]triphosphate specifically blocked the cross-linking of ATP[35S] to the 53 kDa, 83 kDa and 100 kDa ATP-binding proteins, and inhibited the ATP[S]-mediated stimulation of PGE2 production with an ED50 of about 25 microM. On the other hand, 2-methylthioadenosine triphosphate (2MeSATP) blocked ATP[35S] cross-linking to the 42 kDa protein, but had no effect on ATP[S]-mediated stimulation of PGE2 production. In a variant cell line, TEAvarl, derived from TEA3A1 cells that lost their response to ATP in the activation of PLA2, the presence of 83 kDa ATP-binding protein was not detected. Results from our study suggest that ATP activates PLA2 enzymic activity in TEA3A1 cells by binding to an atypical ATP receptor that has not been described previously.

scholarly journals Activation of phospholipase A2 and stimulation of prostaglandin E2 production by transforming growth factor-α in rat thymic epithelial cells requires influx of calcium

1993 ◽  
Vol 293 (1) ◽  
pp. 109-113 ◽  
Author(s):  
P Liu ◽  
M Wen ◽  
L Sun ◽  
J Hayashi
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Receptor Tyrosine Kinase ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Enzymic Activity ◽  
Pge2 Production ◽  
Thymic Epithelial Cells ◽  
Factor I ◽  
Stimulation Of

The stimulation of both phospholipase A2 (PLA2) enzymic activity and the production of prostaglandin E2 (PGE2) by transforming growth factor-alpha (TGF-alpha) and Ca2+ ionophore A23187 in TEA3A1 rat thymic epithelial cells were studied. TGF-alpha by itself at various concentrations (5-200 ng/ml) had no effect on the stimulation of PGE2 production. A23187 (1 microgram/ml) by itself stimulated PGE2 production on average by 18-fold over the control. When TGF-alpha (50 ng/ml) was added to the cells in the presence of A23187, a synergistic stimulation (on average 45-fold) of PGE2 production was observed. Synergistic stimulation was also observed at the level of arachidonic acid released from phospholipid pools, suggesting the activation of PLA2 enzymic activity. We have found that this synergistic activation of PLA2 enzymic activity and subsequent stimulation of PGE2 production required the activation of epidermal growth factor (EGF) receptor tyrosine kinase and Ca2+ influx. This was shown by the fact that genistein, an inhibitor of tyrosine kinase, blocks the synergistic stimulation by TGF-alpha and A23187 and by the fact that the stimulation of PGE2 production by TGF-alpha and A23187 is dependent on the culture-medium Ca2+ concentrations. The requirement for Ca2+ influx instead of intracellular mobilization of Ca2+ was shown by the fact that PGE2 production was not stimulated when cells were treated with TGF-alpha and thapsigargin. Moreover, the synergistic stimulation of PGE2 production by TGF-alpha and A23187 was not affected in protein kinase C down-modulated cells. In addition, the synergistic stimulation was not observed in cells treated with either phorbol 12-myristate 13-acetate (PMA) and TGF-alpha or PMA and A23187, and in cells treated with TGF-alpha and thapsigargin. The requirement for the activation of receptor tyrosine kinase seems to be specific to the EGF receptor, since a synergistic stimulation of PGE2 production was not observed when cells are treated with either insulin-like growth factor-I or fibroblast growth factor-I in the presence of A23187.

Endocytosis by cultured mesangial cells and associated changes in prostaglandin E2 synthesis

1987 ◽  
Vol 252 (4) ◽  
pp. F627-F634
Author(s):  
P. C. Singhal ◽  
G. H. Ding ◽  
S. DeCandido ◽  
N. Franki ◽  
R. M. Hays ◽  
...  
Keyword(s):  
Prostaglandin E2 ◽  
Cytochalasin B ◽  
Mesangial Cells ◽  
Pge2 Production ◽  
Receptor Interaction ◽  
Coated Pits ◽  
Pge2 Synthesis ◽  
Gold Particles ◽  
Fresh Serum ◽  
Stimulation Of

The mechanism of macromolecule uptake by cultured mesangial cells was studied by use of transmission electron microscopy. In parallel, we investigated the effect of macromolecular uptake on prostaglandin E2 (PGE2) formation. Cultured rat mesangial cells were studied in their third passage. As model molecules, we used colloidal gold particles (10 nm diameter) coated either with polyethylene glycol (PEG) or fresh serum (SCG). Mesangial cells were incubated from 1 to 60 min and up to 12 h with either PEG or SCG particles. Endocytosis of SCG significantly exceeded that of PEG particles. The mechanism involved binding to coated pits, followed by formation of coated vesicles (endosomes), and eventually delivery of particles to lysosomes. Pretreatment with cytochalasin B virtually prevented endocytosis of SCG particles, indicating active participation of the cytoskeleton. Determination of PGE2 production in parallel showed that SCG significantly stimulated PGE2 synthesis within minutes, whereas PEG-coated gold had no effect. When gold particles were coated with decomplemented serum instead of fresh serum, the stimulation of PGE2 was partially, but not completely, prevented, indicating that complement may be one, but not the only ligand responsible for enhanced PGE2 production. Stimulation of PGE2 synthesis by SCG was not dependent on actual endocytosis, as it was not altered by cytochalasin B pretreatment. Thus, surface ligand-receptor interaction may be sufficient to trigger PGE2 synthesis. The interaction between mesangial endocytosis and PGE2 production may be important for glomerular pathophysiology.

scholarly journals Distinct phospholipase A2 enzymes regulate prostaglandin E2 and F2alpha production by bovine endometrial epithelial cells

2007 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Patricia K Tithof ◽  
Mary P Roberts ◽  
Wei Guan ◽  
Mona Elgayyar ◽  
James D Godkin
Keyword(s):  
Epithelial Cells ◽  
Prostaglandin E2 ◽  
Phospholipase A2 ◽  
Endometrial Epithelial Cells

Angiotensin II stimulates phospholipases C and A2 in cultured rat mesangial cells

1987 ◽  
Vol 253 (1) ◽  
pp. C113-C120 ◽  
Author(s):  
D. Schlondorff ◽  
S. DeCandido ◽  
J. A. Satriano
Keyword(s):  
Arachidonic Acid ◽  
Angiotensin Ii ◽  
Phospholipase A2 ◽  
Phospholipase C ◽  
Mesangial Cells ◽  
Inositol Trisphosphate ◽  
Pge2 Production ◽  
Diacylglycerol Lipase ◽  
Stimulation Of ◽  
In Cells

Angiotensin II stimulates prostaglandin (PG) E2 formation in mesangial cells cultured from rat renal glomeruli. The interactions between angiotensin II and PGE2 are important in modulating glomerular function. We examined the mechanism for stimulation of PGE2 production in mesangial cells using the putative diacylglycerol-lipase inhibitor RHC 80267 and trifluoperazine (TFP), an agent interfering with Ca2+-CaM-mediated processes. Although RHC 80267 inhibited diacylglycerol-lipase activity in mesangial cells, it did not influence PGE2 production in response to either angiotensin II or A23187. In contrast, TFP (50 microM) inhibited basal PGE2 production and stimulation by angiotensin II and A23187. TFP also decreased 14C release in response to angiotensin from cells prelabeled with [14C]arachidonic acid, which was associated with inhibition of 14C loss from phosphatidylinositol. In cells prelabeled with 32P, orthophosphate angiotensin II caused a rapid hydrolysis of phosphatidylinositol 4,5-bisphospate. TFP enhanced 32P labeling of phosphatidylinositides, but did not prevent the loss of phosphatidylinositol 4,5-bisphosphate in response to angiotensin. This was verified in cells prelabeled with myo-[3H]inositol where angiotensin stimulated formation of [3H]inositol trisphosphate. TFP enhanced formation of [3H]inositol trisphosphate both under basal- and angiotensin II-stimulated conditions. Thus TFP did not inhibit phospholipase C activation by angiotensin. Angiotensin II caused marked increases in [32P]lysophospholipids, indicating activation of also phospholipase A2. This process was inhibited by TFP. Taken together, these results are consistent with stimulation of both phospholipase C and A2 by angiotensin, the latter step responsible for the release of arachidonic acid and PGE2 formation. The activation of phospholipase A2, but not that of phospholipase C, is inhibited by TFP, perhaps by interference with calmodulin-dependent steps.

scholarly journals Stimulation of Ca2+-activated human platelet phospholipase A2 by diacylglycerol

1987 ◽  
Vol 248 (3) ◽  
pp. 779-783 ◽  
Author(s):  
R M Kramer ◽  
G C Checani ◽  
D Deykin
Keyword(s):  
Phospholipase A2 ◽  
Human Platelet ◽  
Human Platelets ◽  
Enzymic Activity ◽  
Stable Form ◽  
Maximal Stimulation ◽  
Octyl Glucoside ◽  
Snake Venom Phospholipase ◽  
Phospholipase A2 Activity ◽  
Stimulation Of

We examined the effect of diacylglycerol on Ca2+-dependent phospholipase A2 from human platelets. Phospholipase A2 was solubilized and partially purified to a stable form in the presence of n-octyl beta-D-glucopyranoside (octyl glucoside), and its enzymic activity was determined with sonicated 2.5 microM-1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (arachidonoyl-PC) as substrate. Phospholipase A2 activity was increased when diacylglycerol was incorporated into the substrate arachidonoyl-PC. Stimulation was maximal in the presence of greater than or equal to 29 mol% (1 microM) diacylglycerol, and was greater than 4-fold for both 1,2-dioleoylglycerol and 1-stearoyl-2-arachidonoylglycerol. 1-Stearoyl-2-arachidonoylglycerol at concentrations of 2-5 mol% increased phospholipase A2 activity 1.3-1.8-fold. Exogenously added 1-oleoyl-2-acetylglycerol also enhanced phospholipase A2 activity, producing a maximal stimulation of 1.6-fold at a concentration of 25 microM. Comparative studies conducted with pancreatic, bee-venom and snake-venom phospholipase A2 showed that the activity of these extracellular phospholipases towards the arachidonoyl-PC substrate was also increased by diacylglycerol, but stimulation was less than observed for platelet phospholipase A2. Our results suggest that diacylglycerol, known to be generated in stimulated platelets, may enhance Ca2+-activated phospholipase A2.

Defective stimulation of cyclic AMP by prostaglandin E2 in colonic epithelial cells in colitis

1993 ◽  
Vol 238 (2-3) ◽  
pp. 387-390 ◽  
Author(s):  
Jon Goldhill ◽  
Liming Zhao ◽  
Yung Xu ◽  
Virginia Donovan ◽  
Robert Burakoff
Keyword(s):  
Epithelial Cells ◽  
Cyclic Amp ◽  
Prostaglandin E2 ◽  
Colonic Epithelial Cells ◽  
Stimulation Of

Prostaglandin E2 production in rat IMCD cells. II. Possible role for locally formed dopamine

1991 ◽  
Vol 261 (4) ◽  
pp. F655-F662 ◽  
Author(s):  
T. L. Huo ◽  
A. Grenader ◽  
P. Blandina ◽  
D. P. Healy
Keyword(s):  
Prostaglandin E2 ◽  
Collecting Duct ◽  
Pge2 Production ◽  
Acid Decarboxylase ◽  
Natriuretic Hormone ◽  
Amino Acid Decarboxylase ◽  
Maximal Stimulation ◽  
Medullary Collecting Duct ◽  
Da2 Receptor ◽  
Stimulation Of

Dopamine has been proposed as an intrarenal natriuretic hormone. We reported previously that inner medullary collecting duct (IMCD) cells express a novel DA2-like dopamine receptor (namely, DA2K) that is linked to stimulation of prostaglandin E2 (PGE2) production. In this study we examined whether locally formed dopamine could stimulate PGE2 production in cultured IMCD cells. L-Dopa stimulated PGE2 production dose dependently in cultured IMCD cells (concentration for half-maximal stimulation, 54.3 microM; maximal stimulation, 212.7% of basal), with the maximal stimulation similar to that obtained with dopamine. This effect was blocked by aromatic L-amino acid decarboxylase (AADC) inhibitors and DA2-receptor antagonists. IMCD cells also had measurable AADC activity and produced dopamine from exogenously added L-dopa. AADC inhibitors and DA2 antagonists also lowered basal PGE2 levels, suggesting that dopamine was being formed constitutively in culture. These results suggest that cultured IMCD cells have the capacity to take up and convert L-dopa to dopamine, which then stimulates PGE2 production via DA2K receptors. These results further suggest that locally formed dopamine could act as an autocrine/paracrine hormone in the kidney inner medulla to regulate PGE2 synthesis and water and electrolyte excretion.

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