title: Protein tyrosine phosphorylation and calcium signaling in thyroid FRTL-5 cells.
abstract: We examined the importance of tyrosine kinase(s) on the ATP-evoked Ca2+ entry and DNA synthesis of thyroid FRTL-5 cells. ATP rapidly and transiently tyrosine phosphorylated a 72-kDa protein(s). This phosphorylation was abolished by pertussis toxin and by the tyrosine kinase inhibitor genistein, and was dependent on Ca2+ entry. Pretreatment of the cells with genistein did not affect the release of sequestered Ca2+, but the capacitative Ca2+ or Ba2+ entry evoked by ATP or thapsigargin was attenuated. Pretreatment of the cells with orthovanadate enhanced the increase in intracellular free Ca2+ ([Ca2+]i), whereas the Ba2+ entry was not increased. Phorbol 12-myristate 13-acetate (PMA) phosphorylated the same protein(s) as did ATP. Genistein inhibited the ATP-evoked phosphorylation of MAP kinase and attenuated both the ATP- and the PMA-evoked DNA synthesis. However, genistein did not inhibit the ATP-evoked expression of c-fos. Furthermore, genistein enhanced the ATP-evoked release of arachidonic acid. Thus, ATP activates a tyrosine kinase via a Ca2+-dependent mechanism. A genistein-sensitive mechanism participates, in part, in the ATP-evoked activation of DNA synthesis. Genistein inhibits only modestly capacitative Ca2+ entry in FRTL-5 cells.
authors.affiliation: Department of Biosciences, University of Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Törnquist
authors.forename: B
authors.initials: B
authors.lastname: Dugué
authors.forename: E
authors.initials: E
authors.lastname: Ekokoski
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002118:Calcium / Q000493:pharmacokinetics*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D019833:Genistein / Q000494:pharmacology; D037342:Pertussis Toxin; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D013961:Thyroid Gland / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D010566:Virulence Factors, Bordetella; D016718:Arachidonic Acid; D014638:Vanadates; D014443:Tyrosine; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D004247:DNA; D019833:Genistein; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium