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

✍ Scribed by Kid Törnquist; Benoit Dugué; Elina Ekokoski

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 249 KB
• Volume: 175
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/(sici)1097-4652(199805)175:2<211::aid-jcp11>3.0.co;2-b

✦ Synopsis

We examined the importance of tyrosine kinase(s) on the ATP-evoked Ca 2/ 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 Ca 2/ entry. Pretreatment of the cells with genistein did not affect the release of sequestered Ca 2/ , but the capacitative Ca 2/ or Ba 2/ entry evoked by ATP or thapsigargin was attenuated. Pretreatment of the cells with orthovanadate enhanced the increase in intracellular free Ca 2/ ([Ca 2/ ] i ), whereas the Ba 2/ 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 Ca 2/ -dependent mechanism. A genistein-sensitive mechanism participates, in part, in the ATP-evoked activation of DNA synthesis. Genistein inhibits only modestly capacitative Ca 2/ entry in FRTL-5 cells.