Protein tyrosine phosphatase activity modulation by endothelin-1 in rabbit platelets.
Protein tyrosine phosphorylation, modulated by the rate of both protein tyrosine kinase and protein tyrosine phosphatase activities, is critical for cellular signal transduction cascades. We report that endothelin-1 stimulation of rabbit platelets resulted in a dose- and time-dependent tyrosine phosphorylation of four groups of proteins in the molecular mass ranges of 50, 60, 70-100 and 100-200 kDa and that one of these corresponds to focal adhesion kinase. This effect is also related to the approximately 60% decrease in protein tyrosine phosphatase activity. Moreover, this inhibited activity was less sensitive to orthovanadate. In the presence of forskolin that increases the cAMP level a dose-dependent inhibition of the endothelin-stimulated tyrosine phosphorylation of different protein substrates and a correlation with an increase in the protein tyrosine phosphatase activity (11.6-fold compared to control) have been found. Further studies by immunoblotting of immunoprecipitated soluble fraction with anti-protein tyrosine phosphatase-1C from endothelin-stimulated platelets have demonstrated that the tyrosine phosphorylation of platelet protein tyrosine phosphatase-1C is correlated with the decrease in its phosphatase activity. As a consequence, modulation and regulation by endothelin-1 in rabbit platelets can be proposed through a cAMP-dependent pathway and a tyrosine phosphorylation process that may affect some relevant proteins such as focal adhesion kinase.
Catalán
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Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Spain.
Gargiulo
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L
Martínez
A M
AM
Calcerrada
M C
MC
Liras
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A
D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D015815:Cell Adhesion Molecules / Q000097:blood; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000097:blood; D019332:Endothelin-1 / Q000494:pharmacology*; D051416:Focal Adhesion Protein-Tyrosine Kinases; D047908:Intracellular Signaling Peptides and Proteins; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000097:blood / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000097:blood; D011817:Rabbits; D015398:Signal Transduction; D014638:Vanadates / Q000494:pharmacology
D015815:Cell Adhesion Molecules; D019332:Endothelin-1; D047908:Intracellular Signaling Peptides and Proteins; D005576:Colforsin; D019000:Phosphotyrosine; D014638:Vanadates; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases