RT Journal Article SR Electronic T1 Capacitative Ca2+ Entry via Orai1 and Stromal Interacting Molecule 1 (STIM1) Regulates Adenylyl Cyclase Type 8 JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 830 OP 842 DO 10.1124/mol.108.051748 VO 75 IS 4 A1 Martin, Agnes C. L. A1 Willoughby, Debbie A1 Ciruela, Antonio A1 Ayling, Laura-Jo A1 Pagano, Mario A1 Wachten, Sebastian A1 Tengholm, Anders A1 Cooper, Dermot M. F. YR 2009 UL http://molpharm.aspetjournals.org/content/75/4/830.abstract AB Capacitative Ca2+ entry (CCE), which occurs through the plasma membrane as a result of Ca2+ store depletion, is mediated by stromal interacting molecule 1 (STIM1), a sensor of intracellular Ca2+ store content, and the pore-forming component Orai1. However, additional factors, such as C-type transient receptor potential (TRPC) channels, may also participate in the CCE apparatus. To explore whether the store-dependent Ca2+ entry reconstituted by coexpression of Orai1 and STIM1 has the functional properties of CCE, we used the Ca2+-calmodulin stimulated adenylyl cyclase type 8 (AC8), which responds selectively to CCE, whereas other modes of Ca2+ entry, including those activated by arachidonate and the ionophore ionomycin, are ineffective. In addition, the Ca2+ entry mediated by previous CCE candidates, diacylglycerol-activated TRPC channels, does not activate AC8. Here, we expressed Orai1 and STIM1 in HEK293 cells and saw a robust increment in CCE, and a proportional increase in CCE-stimulated AC8 activity. Inhibitors of the CCE assembly process ablated the effects on cyclase activity in both AC8-overexpressing HEK293 cells and insulin-secreting MIN6 cells endogenously expressing Ca2+-sensitive AC isoforms. AC8 is believed to be closely associated with the source of CCE; indeed, not only were AC8, Orai1, and STIM1 colocalized at the plasma membrane but also all three proteins occurred in lipid rafts. Together, our data indicate that Orai1 and STIM1 can be integral components of the cAMP and CCE microdomain associated with adenylyl cyclase type 8. The American Society for Pharmacology and Experimental Therapeutics