Abstract
The phagocytosis of beta-glucan particles by human neutrophils and the associated activation of NADPH O2- forming oxidase were accompanied by an increased hydrolysis of phosphoinositides by phospholipase C, hydrolysis of phosphatidylcholine by phospholipase D, accumulation of diglyceride (DG) mass, and [Ca2+]i rise. The reaction of phospholipid hydrolysis played a minor role in the formation of DG, which was mainly formed by de novo synthesis from glucose. The activation of this pathway was shown by the stimulation of the incorporation of [U-14C]glucose into DG, which occurred very rapidly after the challenge of neutrophils with beta-glucan particles. This DG derived from glucose was found almost completely as 1-acyl-2-acyl-glycerol (DAG). On the basis of the finding that phosphatidic acid was the precursor of DAG, an increase in the incorporation of [U-14C]acetate into DAG did not occur, and the [14C]radioactivity was in the glycerol backbone, the synthesis of DAG from [U-14C]glucose occurred very likely via dihydroxyacetone phosphate and glycerol 3-phosphate, stepwise acylation to phosphatidic acid, and dephosphorylation by phosphatidate phosphatase.
Highlights
From the Institute of General Pathology and the §Institute of Human Anatomy and Histology, University of Verona, Strada Le Grazie,37134 Verona, Italy
By de novo synthesis from glucose. The activation of this pathway was shown by the stimulation of the incorporation of [U-'4C]glucose into DG, which oc- Reagents-Bovine cardiolipin, octyl-&glucoside, 1,2-dioleoylcurred very rapidly after the challenge of neutrophils glycerol, propranolol, and Baker's yeast-derived glucanwere purwith 8-glucan particles
Was the main reactionforming PA in neutrophils stimulated by P-glucan particles, we have investigated the effect of ethanol
Summary
The activation of this pathway was shown by the stimulation of the incorporation of [U-'4C]glucose into DG, which oc- Reagents-Bovine cardiolipin, octyl-&glucoside, 1,2-dioleoylcurred very rapidly after the challenge of neutrophils glycerol, propranolol, and Baker's yeast-derived glucanwere purwith 8-glucan particles. It canbe concluded that thede novo synthesis from glucose represents the main source of DG in neutrophils activated by P-glucan
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