NFAT reporter assay

The Ca²⁺ sensitive transcriptional luciferase reporter pGL4.30[luc2P/NFAT-RE/Hygro] (Promega, E8481) was transiently transfected into the 5HT_2BR stable cell line. Briefly, 3 × 10⁶ cells were plated in a Nunc Cell Culture Treated flask (25 cm², ThermoFisher) and transfected with lipofectamine 2000 (ThermoFisher) plus 1 µg of plasmid DNA according to the manufacturer’s protocol. The following day, culture media was replaced with induction media (DMEM + 10% dialyzed FBS supplemented with 1 µg/ml doxycycline), and 24 h later cells were re-plated into 96 well, solid white plates (Costar, 3917). After allowing 3 h for cells to adhere, drugs were added at 20× concentration. For antagonist experiments, cells were incubated with 5HT_2B R antagonists for 2 h prior to subsequent addition of agonist. After 18 h culture in the presence of agonist, plates were assayed using the ONE-Glo Luciferase Assay System (Promega, E6120) and read on a GloMax-Multi Detection System plate reader (Promega).