Selective association of the tyrosine kinases Src, Fyn, and Lyn with integrin-rich actin cytoskeletons of activated, nonaggregated platelets.
Integrin-mediated interactions between cytoskeletal proteins and extracellular fibrinogen are required for platelet adhesion. We have previously demonstrated that the major platelet integrin, alpha(IIb)beta(3), becomes incorporated into the actin cytoskeleton of platelets in an activation-dependent, aggregation-independent manner. To determine if regulatory molecules are also associated with these integrin-rich cytoskeletal complexes, we examined actin cytoskeletons for the presence of kinases and phosphoproteins. Western immunoblot analysis revealed that the tyrosine kinases Src, Fyn, and Lyn are specifically associated with actin cytoskeletons of activated, nonaggregated platelets. However, as noted by others, the cytoskeletal association of focal adhesion kinase depends on platelet aggregation. Actin cytoskeletons isolated from (32)P-labeled platelets also contain a number of phosphorylated proteins. Interestingly, an approximately 18-kDa phosphoprotein was uniquely present in activated platelet cytoskeletons. Collectively, our results demonstrate that actin cytoskeletons of activated, nonaggregated platelets contain not only integrins, but also kinases and phosphoproteins that could regulate platelet adhesion and transmembrane communication.
Department of Chemistry, Gonzaga University, Spokane, Washington, 99258, USA. bertagnolli@gonzaga.edu
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Bertagnolli
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Hudson
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Stetsenko
D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D008970:Molecular Weight; D010750:Phosphoproteins / Q000032:analysis / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D015539:Platelet Activation / Q000187:drug effects; D010974:Platelet Aggregation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D011108:Polymers / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D015398:Signal Transduction / Q000187:drug effects; D013917:Thrombin / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism
D000199:Actins; D015815:Cell Adhesion Molecules; D010750:Phosphoproteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D011108:Polymers; D011518:Proto-Oncogene Proteins; D000255:Adenosine Triphosphate; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D051076:Proto-Oncogene Proteins c-fyn; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D013917:Thrombin