title: Staurosporine maintains the activation of store-operated Ca²⁺ entry even after the refilling of Ca²⁺ stores.
abstract: Store-operated Ca²⁺ entry (SOCE) from the extracellular space plays a critical role in agonist-mediated Ca²⁺ signaling in non-excitable cells. Here we show that SOCE is enhanced in COS-7 cells treated with staurosporine (ST), a protein kinase inhibitor. In COS-7 cells, stimulation with ATP induced Ca²⁺ release from intracellular Ca²⁺ stores and Ca²⁺ entry from the extracellular space. Ca²⁺ release was not affected by treatment with ST, but Ca²⁺ entry continued in the ST-treated cells even after the removal of ATP. ST did not inhibit Ca²⁺ sequestration into Ca²⁺ stores. The Ca²⁺ entry induced by cyclopiazonic acid (CPA), a reversible ER Ca²⁺ pump inhibitor, was maintained in ST-treated cells even after the removal of CPA, but was not maintained in the control cells. The sustained Ca²⁺ entry in ST-treated cells was completely attenuated by the SOCE inhibitors, La³⁺ and 2-APB. The large increase in Ca²⁺ entry produced in the cells co-expressing Venus-Orai1 and STIM1-mKO1 was stabilized with ST treatment, and confocal imaging of these cells suggested that the complex between Orai1 and STIM1 did not completely dissociate following the refilling of Ca²⁺ stores. These results show that SOCE remains activated even after the refilling of Ca²⁺ stores in ST-treated cells and that the effect of ST on SOCE may result from a stabilization of the Orai1-STIM1 interaction.
authors.affiliation: Department of Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan. tojyo@hoku-iryo-u.ac.jp
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Tojyo
authors.forename: Takao
authors.initials: T
authors.lastname: Morita
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nezu
authors.forename: Akihiko
authors.initials: A
authors.lastname: Tanimura
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000603:Amino Acids, Sulfur / Q000494:pharmacology; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling; D002522:Chlorocebus aethiops; D007211:Indoles / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019311:Staurosporine / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000603:Amino Acids, Sulfur; D015220:Calcium Channels; D007211:Indoles; D047428:Protein Kinase Inhibitors; C002625:aminoethyldithioacetic acid; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D019311:Staurosporine; D002118:Calcium; C000543:cyclopiazonic acid