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Thrombopoietin, c‐Mpl ligand, induces tyrosine phosphorylation of Tyk2, JAK2, and STAT3, and enhances agonists‐induced aggregation in platelets in vitro
Author(s) -
Ezumi Yasuharu,
Takayama Hiroshi,
Okuma Minoru
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01072-m
Subject(s) - tyrosine phosphorylation , thrombopoietin , phosphorylation , chemistry , protein tyrosine phosphatase , tyrosine , janus kinase 2 , microbiology and biotechnology , receptor tyrosine kinase , tyrosine kinase , stat3 , signal transduction , biochemistry , biology , stem cell , haematopoiesis
We investigated in vitro effects of recombinant human thrombopoietin (TPO), or c‐Mpl ligand, on human platelets. TPO induced rapid dose‐dependent tyrosine phosphorylation of several proteins. We identified Janus tyrosine kinases, Tyk2 and JAK2, and a member of STAT (signal transducers and activators of transcription) family, STAT3, as the tyrosine‐phosphorylated proteins in response to TPO. TPO by itself did not cause platelet aggregation and shape change, but augmented ADP‐induced aggregation in a dose‐dependent manner. Acetylsalicylic acid inhibited the secondary aggregation enhanced by TPO, but not the TPO‐induced potentiation of the primary aggregation. TPO modulates platelet activation possibly through protein‐tyrosine phosphorylation.