The temporal relationship between phospholipase activation, diradylglycerol formation and superoxide production in the human neutrophil.
Fluctuations in the amounts of choline, inositol 1,4,5-trisphosphate (IP3) and diradylglycerol have been used to monitor phospholipase activation in the human neutrophil. Stimulation of human neutrophils by formylmethionyl-leucylphenylalanine (fMet-Leu-Phe) resulted in a rapid activation of both phosphatidylinositol 4,5-bisphosphate breakdown by phospholipase C and phosphatidylcholine breakdown by phospholipase D. Diradylglycerol accumulation occurred more slowly than that of either choline or IP3 and was inhibited by 30 mM-butanol, suggesting that the bulk was derived from the phospholipase D pathway via phosphatidate phosphohydrolase. Consistent with this is the observation that choline and diradylglycerol are produced in similar amounts. 1,2-Diacylglycerol (DAG) and 1-O-alkyl-2-acyl-sn-glycerol species accumulated with different time courses, indicating that one or more steps in the phospholipase D pathway was selective for the diacyl species. Superoxide production by fMet-Leu-Phe-stimulated neutrophils paralleled DAG accumulation over the first 5 min, but thereafter this production stopped, despite the fact that DAG remained elevated. We conclude that DAG derived from the phospholipase D pathway is only one of the second messengers important in controlling this functional response.
Thompson
N T
NT
Biochemical Sciences, Wellcome Research Laboratories, Beckenham, Kent, U.K.
Tateson
J E
JE
Randall
R W
RW
Spacey
G D
GD
Bonser
R W
RW
Garland
L G
LG
D002794:Choline / Q000097:blood; D004075:Diglycerides / Q000097:blood*; D004789:Enzyme Activation; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000097:blood; D007700:Kinetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010739:Phospholipase D / Q000097:blood*; D010727:Phosphoric Diester Hydrolases / Q000097:blood*; D013481:Superoxides / Q000097:blood*
C011439:1,2-diacylglycerol; D004075:Diglycerides; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; C035561:diarachidonyl diglyceride; D015544:Inositol 1,4,5-Trisphosphate; D010727:Phosphoric Diester Hydrolases; D010739:Phospholipase D; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D002794:Choline