Protein tyrosine phosphorylation and calcium signaling in thyroid FRTL-5 cells

• Published in: Journal of cellular physiology Vol. 175; no. 2; pp. 211 - 219
• Main Authors: Törnquist, Kid, Dugué, Benoit, Ekokoski, Elina
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.05.1998
• Subjects: Adenosine Triphosphate - pharmacology; Animals; Arachidonic Acid - metabolism; Calcium - pharmacokinetics; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Cell Line; DNA - biosynthesis; Genistein - pharmacology; Pertussis Toxin; Phosphorylation; Protein-Tyrosine Kinases - physiology; Proto-Oncogene Proteins c-fos - metabolism; Rats; Signal Transduction - physiology; Tetradecanoylphorbol Acetate - pharmacology; Thapsigargin - pharmacology; Thyroid Gland - physiology; Tyrosine - metabolism; Vanadates - pharmacology; Virulence Factors, Bordetella - pharmacology
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/(SICI)1097-4652(199805)175:2<211::AID-JCP11>3.0.CO;2-B

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. J. Cell. Physiol. 175:211–219, 1998. © 1998 Wiley‐Liss, Inc.