scholarly journals Role of Phospholipase D in Pasteurella haemolytica Leukotoxin-Induced Increase in Phospholipase A2 Activity in Bovine Neutrophils

1999 ◽  
Vol 67 (8) ◽  
pp. 3768-3772 ◽  
Author(s):  
Zuncai Wang ◽  
Cyril R. Clarke ◽  
Kenneth D. Clinkenbeard
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Pasteurella Haemolytica ◽  
Time Dependent ◽  
Regulatory Interaction ◽  
Pneumonic Pasteurellosis ◽  
Transphosphatidylation Reaction ◽  
Bovine Neutrophils ◽  
Phospholipase A2 Activity

ABSTRACT The effects of Pasteurella haemolytica leukotoxin (LKT) on the activity of phospholipase D (PLD) and the regulatory interaction between PLD and phospholipase A2 (PLA2) were investigated in assays using isolated bovine neutrophils labeled with tritiated phospholipid substrates of the two enzymes. Exposure of [3H]lysophosphatidylcholine-labeled neutrophils to LKT caused concentration- and time-dependent production of phosphatidic acid (PA), the product of PLD. LKT-induced generation of PA was dependent on extracellular calcium. Both production of PA and metabolism of [3H]-arachidonate ([3H]AA)-labeled phospholipids by PLA2 were inhibited when ethanol was used to promote the alternative PLD-mediated transphosphatidylation reaction, resulting in the production of phosphatidylethanol rather than PA. The role of PA in regulation of PLA2 activity was then confirmed by means of an add-back experiment, whereby addition of PA in the presence of ethanol restored PLA2-mediated release of radioactivity from neutrophil membranes. Considering the involvement of chemotactic phospholipase products in the pathogenesis of pneumonic pasteurellosis, development and use of anti-inflammatory agents that inhibit LKT-induced activation of PLD and PLA2 may improve therapeutic management of the disease.

scholarly journals Pasteurella haemolyticaLeukotoxin-Induced Increase in Phospholipase A2 Activity in Bovine Neutrophils

1998 ◽  
Vol 66 (5) ◽  
pp. 1885-1890 ◽  
Author(s):  
Zuncai Wang ◽  
Cyril Clarke ◽  
Kenneth Clinkenbeard
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Phospholipase A2 ◽  
Extracellular Calcium ◽  
Pasteurella Haemolytica ◽  
Phospholipase A ◽  
Time Dependent ◽  
Type Iv ◽  
Bovine Neutrophils ◽  
Phospholipase A2 Activity

ABSTRACT Exposure of bovine neutrophils to Pasteurella haemolytica leukotoxin (LKT) stimulates the production of leukotriene B4 (LTB4), which is believed to be an important chemotactic agent in the development of acute fibrinopurulent pneumonic infection in cattle. The involvement of phospholipase A2 (PLA2) in LKT-induced synthesis of LTB4 was studied by using bovine neutrophils labeled with 3H-arachidonate ([3H]AA). Incubation of isolated neutrophils with [3H]AA resulted in incorporation of radioactivity in the PLA2 substrates phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. Exposure of radiolabeled neutrophils to LKT caused concentration- and time-dependent release of radioactivity and redistribution of radioactivity in neutrophil membranes consistent with utilization of phosphoglyceride substrate and release of free fatty acid and eicosanoid products. These LKT-induced effects could be inhibited by pretreatment with arachidonyl trifluoromethyl ketone, an inhibitor of type IV cytoplasmic PLA2, and were dependent on extracellular calcium. These results support the conclusion that LKT-induced synthesis of LTB4 involves a calcium-mediated increase in PLA2 activity.

scholarly journals Phospholipase D2 Mediates Acute Aldosterone Secretion in Response to Angiotensin II in Adrenal Glomerulosa Cells

Endocrinology ◽  
2010 ◽  
Vol 151 (5) ◽  
pp. 2162-2170 ◽  
Author(s):  
Haixia Qin ◽  
Michael A. Frohman ◽  
Wendy B. Bollag
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Cell Surface ◽  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Cell Interior ◽  
Aldosterone Secretion ◽  
Phospholipase D2 ◽  
Glomerulosa Cells

In primary bovine adrenal glomerulosa cells, the signaling enzyme phospholipase D (PLD) is suggested to mediate priming, the enhancement of aldosterone secretion after pretreatment with and removal of angiotensin II (AngII), via the formation of persistently elevated diacylglycerol (DAG). To further explore PLD’s role in priming, glomerulosa cells were pretreated with an exogenous bacterial PLD. Using this approach, phosphatidic acid (PA) is generated on the outer, rather than the inner, leaflet of the plasma membrane. Although PA is not readily internalized, the PA is nonetheless rapidly hydrolyzed by cell-surface PA phosphatases to DAG, which efficiently flips to the inner leaflet and accesses the cell interior. Pretreatment with bacterial PLD resulted in priming upon subsequent AngII exposure, supporting a role of DAG in this process, because the increase in DAG persisted after exogenous PLD removal. To determine the PLD isoform mediating aldosterone secretion, and presumably priming, primary glomerulosa cells were infected with adenoviruses expressing GFP, PLD1, PLD2, or lipase-inactive mutants. Overexpressed PLD2 increased aldosterone secretion by approximately 3-fold over the GFP-infected control under basal conditions, with a significant enhancement to about 16-fold over the basal value upon AngII stimulation. PLD activity was also increased basally and upon stimulation with AngII. In contrast, PLD1 overexpression had little effect on aldosterone secretion, despite the fact that PLD activity was enhanced. In both cases, the lipase-inactive PLD mutants showed essentially no effect on PLD activity or aldosterone secretion. Our results suggest that PLD2 is the isoform that mediates aldosterone secretion and likely priming.

scholarly journals The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle

2006 ◽  
Vol 103 (12) ◽  
pp. 4741-4746 ◽  
Author(s):  
T. A. Hornberger ◽  
W. K. Chu ◽  
Y. W. Mak ◽  
J. W. Hsiung ◽  
S. A. Huang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Phosphatidic Acid ◽  
Mechanical Activation ◽  
Phospholipase D ◽  
Mtor Signaling

Diacylglycerol generation in fluoride-treated neutrophils: involvement of phospholipase D

Blood ◽  
1991 ◽  
Vol 77 (12) ◽  
pp. 2746-2756
Author(s):  
D English ◽  
G Taylor ◽  
JG Garcia
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Superoxide Anion ◽  
Second Messenger ◽  
Complete Inhibition ◽  
Fluoride Ion ◽  
Extracellular Medium ◽  
Time Points ◽  
Acid Generation ◽  
Transphosphatidylation Reaction

Neutrophils exposed to fluoride ion (F-) respond with a delayed and sustained burst of superoxide anion release that is both preceded by and dependent on the influx of Ca2+ from the extracellular medium. The results of this study demonstrate a similarly delayed and sustained generation of 1,2-diglyceride in F(-)-treated neutrophils, over 90% of which was 1,2-diacylglycerol. Diacylglycerol generation was not dependent on the presence of extracellular Ca2+. Conversely, in contrast to results obtained with other agonists, removal of extracellular Ca2+ markedly potentiated synthesis of diacylglycerol in F(-)-treated neutrophils. This effect was accompanied by a corresponding decrease in the recovery of phosphatidic acid. In either the presence or absence of extracellular Ca2+, phosphatidic acid accumulated before diacylglycerol in F(-)-treated cells, suggesting the latter was derived from the former. Consistent with this hypothesis, the phosphatidic acid phosphohydrolase inhibitor, propranolol, suppressed generation of diacylglycerol as it potentiated the accumulation of phosphatidic acid in F(-)-treated neutrophils. This effect was observed both in the presence and absence of extracellular Ca2+. Moreover, high levels of propranolol (160 mumol/L) effected complete inhibition of diacylglycerol generation in F(-)-treated neutrophils with a corresponding increase in phosphatidic acid generation. Phosphatidylethanol accumulated in neutrophils stimulated with F- in the presence of ethanol. The extent of phosphatidylethanol accumulation at all time points after addition of F- corresponded to decreased levels of both phosphatidic acid and diacylglycerol, indicating that phosphatidylethanol was derived from the phospholipase D-catalysed transphosphatidylation reaction. The results indicate that F- activates a Ca(2+)-independent phospholipase D, which appears to be the major, if not sole, catalyst for both phosphatidic acid and diacylglycerol generation in F(-)-treated neutrophils. Ca2+, mobilized as a result of F- stimulation and possibly as a consequence of phospholipase D activation, exerts a profound effect on cellular second messenger levels by modulating the conversion of phosphatidic acid to diacylglycerol.

Stimulation of phospholipase D activity and phosphatidic acid production by norepinephrine in rat aorta

1993 ◽  
Vol 264 (3) ◽  
pp. C609-C616 ◽  
Author(s):  
A. W. Jones ◽  
S. D. Shukla ◽  
B. B. Geisbuhler
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Time Course ◽  
Rat Aorta ◽  
Functional Responses ◽  
Phosphatidylinositol Bisphosphate ◽  
Phosphatidylinositol Phosphate ◽  
Transphosphatidylation Reaction ◽  
Hydrolysis Of ◽  
Stimulation Of

We sought to relate norepinephrine (NE) stimulation of phosphatidic acid (PA) production to functional responses of rat aorta and pathways for PA production. The time course for changes in PA was closely related to Ca-dependent tonic responses in 42K efflux and contraction. NE (30 microM for 1 min) increased PA and reduced phosphatidylcholine (PC) and phosphatidylinositol (PI) based on Pi analyses and 32P labeling of phospholipids. The 32P-to-Pi ratio in PA (0.8 +/- 0.2, n = 13) was similar to PC (0.8 +/- 0.1, n = 14) but was significantly lower (P < 0.001) than PI (4.6 +/- 0.5, n = 14). The 32P-to-Pi ratio in PA was also lower (P < 0.02) than phosphatidylinositol phosphate and phosphatidylinositol bisphosphate. NE also increased [3H]PA twofold (P < 0.05) when PC was selectively labeled with [3H]myristic acid. These observations are more consistent with PA being formed from the hydrolysis of PC by phospholipase D (PLD) than by the phosphorylation of diacylglycerol produced by the action of phospholipase C. PLD was assayed by the formation of phosphatidylethanol (PEt) via a transphosphatidylation reaction with ethanol (half-maximal stimulation at 0.4-0.5% vol/vol). The time course for PLD stimulation by NE was similar to PA, with significant increases (P < 0.002) during 10 s to 30 min exposure. Once formed, PEt was degraded slowly, with a half time > 3 h. It is concluded that NE stimulates PLD in rat aorta, which forms a significant amount of PA from the hydrolysis of PC.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Phospholipase D activity is essential for actin localization and actin-based motility in Dictyostelium

2005 ◽  
Vol 389 (1) ◽  
pp. 207-214 ◽  
Author(s):  
Soha ZOUWAIL ◽  
Trevor R. PETTITT ◽  
Stephen K. DOVE ◽  
Margarita V. CHIBALINA ◽  
Dale J. POWNER ◽  
...  
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Essential Role ◽  
Kinase Activity ◽  
Complete Loss ◽  
Complete Inhibition ◽  
Cellular Processes ◽  
Small Clusters ◽  
Actin Localization

PLD (phospholipase D) activity catalyses the generation of the lipid messenger phosphatidic acid, which has been implicated in a number of cellular processes, particularly the regulation of membrane traffic. In the present study, we report that disruption of PLD signalling causes unexpectedly profound effects on the actin-based motility of Dictyostelium. Cells in which PLD activity is inhibited by butan-1-ol show a complete loss of actin-based structures, accompanied by relocalization of F-actin into small clusters, and eventually the nucleus, without a visible fall in levels of F-actin. Addition of exogenous phosphatidic acid reverses the effects of butan-1-ol, confirming that these effects are caused by inhibition of PLD. Loss of motility correlates with complete inhibition of endocytosis and a reduction in phagocytosis. Inhibition of PLD caused a major decrease in the synthesis of PtdIns(4,5)P2, which could again be reversed by exogenously applied phosphatidic acid. Thus the essential role of PLD signalling in both motility and endocytosis appears to be mediated directly via regulation of PtdIns(4)P kinase activity. This implies that localized PLD-regulated synthesis of PtdIns(4,5)P2 is essential for Dictyostelium actin function.

scholarly journals Activation of phospholipase D by α-thrombin or epidermal growth factor contributes to the formation of phosphatidic acid, but not to observed increases in 1,2-diacylglycerol

1992 ◽  
Vol 285 (2) ◽  
pp. 395-400 ◽  
Author(s):  
T M Wright ◽  
S Willenberger ◽  
D M Raben
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Myristic Acid ◽  
Transient Activation ◽  
Lipid Species ◽  
Epidermal Growth

The receptor-mediated activation of a phosphatidylcholine-hydrolysing phospholipase D (PLD) has recently been described. We investigated the effect of alpha-thrombin and epidermal growth factor (EGF) on cellular PLD activity in order to determine the role of this enzyme in mitogen-induced increases in phosphatidic acid and sn-1,2-diacylglycerol. In the presence of ethanol, stimulation of [3H]myristic acid-labelled quiescent IIC9 cells with alpha-thrombin or EGF resulted in a rapid increase in radiolabelled phosphatidyl-ethanol which reached a plateau at 1 min, indicating the rapid and transient activation of PLD. We observed a concomitant decrease in the mitogen-stimulated increase of radiolabelled phosphatidic acid. In contrast, ethanol did not significantly effect the elevation of sn-1,2-diacylglycerol levels stimulated by alpha-thrombin or EGF as determined by measurement of sn-1,2-diacylglycerol mass or the appearance of [3H]1,2-diacylglycerol. A novel lipid, detected by two-dimensional t.l.c. analysis, was generated in [3H]myristic acid-labelled cells stimulated with alpha-thrombin, but not EGF, in the presence of ethanol. Treatment in vitro of cellular lipids isolated from [3H]myristic acid-labelled cultures with PLD in the presence of ethanol also resulted in the generation of this novel lipid species, supporting the role of this enzyme in its production. These data indicate that in quiescent IIC9 cells: (a) alpha-thrombin or EGF rapidly and transiently activates a PLD; (b) although this activation is responsible for part of the mitogen-induced increases in phosphatidic acid, it does not contribute to induced increases in sn-1,2-diacylglycerol; and (c) activation of this enzyme appears to be involved in the formation of a novel lipid generated in response to alpha-thrombin, but not EGF, in IIC9 fibroblasts.

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