TY - JOUR
T1 - Diacylglycerol generation in fluoride-treated neutrophils
T2 - Involvement of phospholipase D
AU - English, D.
AU - Taylor, G.
AU - Garcia, J. G.N.
PY - 1991
Y1 - 1991
N2 - 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 μmol/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 Ca2+-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.
AB - 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 μmol/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 Ca2+-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.
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U2 - 10.1182/blood.v77.12.2746.bloodjournal77122746
DO - 10.1182/blood.v77.12.2746.bloodjournal77122746
M3 - Article
C2 - 2043770
AN - SCOPUS:0025875856
SN - 0006-4971
VL - 77
SP - 2746
EP - 2756
JO - Blood
JF - Blood
IS - 12
ER -