replying to J. P. Kukkonen Nature Communications https://doi.org/10.1038/s41467-023-38764-3 (2023)

Kukkonen challenges our interpretation of data in Figure 5d of our paper1. In this experiment, we co-transfected HEK293 cells with CMV-driven overexpression plasmids for OX2R and Gαi1 along with a pGloSensor cAMP reporter construct, and measured diminished cAMP levels with OX2R agonists after forskolin stimulation. Results from this experiment showed a weak reduction in cAMP, without a characteristic low-nanomolar EC50 for either TAK-925 or Orexin B (in contrast to the parallel inositol phosphate accumulation assay with overexpressed OX2R and Gαq). We acknowledge the validity of Kukkonen’s arguments that the cAMP data could also be explained by a combination of signaling through different G protein subtypes and/or regulation by PDEs. We also appreciate his arguments that the G protein selectivity or promiscuity exhibited by OX2R will depend on the cell line and experimental setup, and has not been definitively established in CNS neurons.