Interdependence of calcium signaling and protein tyrosine phosphorylation in human endothelial cells.
The signal transduction cascade which initiates transmembraneous influx of Ca2+ into endothelial cells in response to the discharge of intracellular Ca2+ stores is thought to involve a step sensitive to tyrosine kinase inhibition. We investigated the interrelationship between Ca2+ signaling and protein tyrosine phosphorylation following cell stimulation with either the receptor-dependent agonist, bradykinin, or the protein-tyrosine phosphatase inhibitor, phenylarsine oxide. In cultured human endothelial cells phenylarsine oxide instigated a concentration-dependent increase in the intracellular concentration of free Ca2+ ([Ca2+]i). This increase in [Ca2+]i was not associated with the tyrosine phosphorylation of phospholipase C gamma, enhanced formation of inositol 1,4,5-trisphosphate, or the rapid depletion of intracellularly stored Ca2+ but was coincident with the enhanced and prolonged tyrosine phosphorylation of a number of cytoskeletal proteins. In bradykinin-stimulated cells the tyrosine phosphorylation of the same cytoskeletal proteins (most notably 85- and 100-kDa proteins) was transient when cells were stimulated in the presence of extracellular Ca2+, was maintained under Ca2+-free conditions, and was reversed following readdition of extracellular Ca2+. These data suggest that the tyrosine phosphorylation of 2 cytoskeletal proteins is determined by the level of Ca2+ present in intracellular stores thus indicating a critical role for tyrosine phosphorylation in the control of capacitative Ca2+ entry in endothelial cells.
Fleming
I
I
Zentrum der Physiologie, Klinikum der J.W. Goethe-Universität, Frankfurt/Main, Germany.
Fisslthaler
B
B
Busse
R
R
D000595:Amino Acid Sequence; D001152:Arsenicals / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D007527:Isoenzymes / Q000378:metabolism; D008969:Molecular Sequence Data; D051966:Phospholipase C gamma; D010766:Phosphorylation; D011092:Polyethylene Glycols; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*
D001152:Arsenicals; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D007295:Inositol Phosphates; D007527:Isoenzymes; C029341:oxophenylarsine; D011092:Polyethylene Glycols; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D001920:Bradykinin; D002118:Calcium