GTPgammaS-stimulated phospholipase D activation in human neutrophils occurs by protein kinase C-dependent and -independent pathways but not tyrosine kinases.
Addition of GTPgammaS to saponin-permeabilised human neutrophils activated both the NADPH oxidase and phospholipase D (PLD). This PLD activation was hardly affected by staurosporine or Ro31-8220 (at concentrations which inhibited PMA stimulated PLD activity), indicating that it was largely independent of protein kinase C (PKC). This GTPgammaS stimulated PLD activity was enhanced by 1 mM ATP, but this ATP-enhanced activity was blocked by inhibitors of PKC. Addition of GTPgammaS resulted in very low levels of phosphorylation on tyrosine residues, but higher levels of phosphorylation on serine/threonine residues. Addition of pervanadate hydroperoxides stimulated phosphorylation on tyrosine residues and activated PLD which was blocked by addition of inhibitors of tyrosine kinases. Thus, GTPgammaS can stimulate PKC-dependent and -independent pathways of PLD activation. Whilst phosphorylation on tyrosine residues can result in activation of PLD, this is regulated independently of activation via G-proteins.
Lowe
G M
GM
Department of Haematology, University of Liverpool, United Kingdom.
Slupsky
J R
JR
Galvani
D W
DW
Edwards
S W
SW
D000470:Alkaloids / Q000494:pharmacology; D001597:Benzylidene Compounds / Q000494:pharmacology; D002463:Cell Membrane Permeability; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007700:Kinetics; D009247:NADH, NADPH Oxidoreductases / Q000097:blood; D019255:NADPH Oxidases; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D009570:Nitriles / Q000494:pharmacology; D010739:Phospholipase D / Q000097:blood*; D010750:Phosphoproteins / Q000097:blood / Q000302:isolation & purification; D019000:Phosphotyrosine / Q000032:analysis; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000097:blood*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000097:blood*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D020032:Tyrphostins; D014638:Vanadates / Q000494:pharmacology
D000470:Alkaloids; D001597:Benzylidene Compounds; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D007211:Indoles; D009570:Nitriles; D010750:Phosphoproteins; D020032:Tyrphostins; C095713:alpha-cyano-(3,4-dihydroxy)-N-(3-phenylpropyl)cinnamide; D019000:Phosphotyrosine; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D014638:Vanadates; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010739:Phospholipase D; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; C064758:Ro 31-8220; C048212:erbstatin