Activation of protein-tyrosine kinase Syk in human platelets stimulated with lysophosphatidic acid or sphingosine 1-phosphate.
It has been reported that not only lysophosphatidic acid (LPA) but also its sphingolipid counterpart, sphingosine 1-phosphate (Sph-1-P), induce platelet functional responses. We report here Syk activation in human platelets stimulated with these lysophospholipids. LPA rapidly induced platelet protein-tyrosine phosphorylation, including that of Syk, and Syk activation, assessed by immunoprecipitation kinase assay. Sph-1-P, although rather weaker, mimicked LPA in inducing these tyrosine kinase-related events. Pretreatment of platelets with staurosporine, a potent protein kinase inhibitor, diminished LPA-induced Syk phosphorylation and activation, but not intracellular Ca2+ mobilization. These results demonstrate that, in platelets, the bioactive lysophospholipids induce Syk activation, which, however, may not be related to Ca2+ mobilization.
Yang
L
L
Department of Laboratory Medicine, Yamanashi Medical University, Japan.
Yatomi
Y
Y
Hisano
N
N
Qi
R
R
Asazuma
N
N
Satoh
K
K
Igarashi
Y
Y
Ozaki
Y
Y
Kume
S
S
D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids / Q000494:pharmacology*; D010766:Phosphorylation; D015539:Platelet Activation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000072377:Syk Kinase; D014443:Tyrosine / Q000378:metabolism
D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D013110:Sphingosine