A role for protein kinase C in the membrane fusion necessary for platelet granule secretion.
The addition of 1-oleoyl-2-acetylglycerol (OAG), or phorbol-12-myristate-13-acetate (PMA) to platelets induced the phosphorylation of a 47,000 dalton protein (47 Kd), fusion of granule membranes with membranes of the surface connected canalicular system, the formation of large vesicles and the secretion of serotonin. 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine (H7), and sphingosine, inhibitors of protein kinase C, significantly inhibited the ultrastructural changes and the phosphorylation of 47 Kd. N-(2-guanidinoethyl)-5-isoquinolinesulfonamide (HA1004), structurally similar to H7, but a weaker inhibitor of protein kinase C, did not attenuate these responses to OAG or to PMA. H7, but not HA1004, also markedly inhibited secretion induced by the synergistic combination of OAG and the calcium ionophore A23187. Amiloride and 5-(N,N dimethyl)-amiloride, inhibitors of the Na+/H+ transporter, did not inhibit the ultrastructural response and the protein phosphorylation induced by OAG, or the secretion induced by the combination of A23187 and OAG. The results link the activation of protein kinase C by diglycerides to the labilization and fusion of granule membranes important for secretion.
Gerrard
J M
JM
Department of Pediatrics, Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg.
Beattie
L L
LL
Park
J
J
Israels
S J
SJ
McNicol
A
A
Lint
D
D
Cragoe
E J
EJ
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000584:Amiloride / Q000494:pharmacology; D001792:Blood Platelets / Q000166:cytology / Q000502:physiology*; D000001:Calcimycin / Q000494:pharmacology; D002352:Carrier Proteins / Q000502:physiology*; D003594:Cytoplasmic Granules / Q000502:physiology; D004075:Diglycerides / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D008561:Membrane Fusion; D008564:Membrane Potentials; D010750:Phosphoproteins / Q000097:blood; D010879:Piperazines / Q000494:pharmacology; D010974:Platelet Aggregation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers; D013110:Sphingosine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002352:Carrier Proteins; D004075:Diglycerides; D007546:Isoquinolines; D010750:Phosphoproteins; D010879:Piperazines; D017923:Sodium-Hydrogen Exchangers; D000001:Calcimycin; D000584:Amiloride; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate