Locusts adopt IP₃ as a second messenger for olfactory signal transduction

Insects, unlike vertebrates, use heteromeric complexes of odorant receptors and co-receptors for olfactory signal transduction. However, the secondary messengers involved in this process are largely unknown. Here, we use the olfactory signal transduction of the aggregation pheromone 4-vinylanisole (4VA) as a model to address this question. When locusts detect 4VA, the pheromone is transported by OBP10 and OBP13 to the OR35-Orco receptor complex, thereby activating downstream pathways in the antenna. A pivotal downstream molecule, the lipid-binding protein Clvs2, facilitates phosphatidylinositol 4,5-bisphosphate transportation across the cytolemma, providing more substrates for inositol trisphosphate (IP₃) production. PLCe1, a biosynthetic enzyme, boosts IP₃ levels in the antennal lobe of the brain. IP₃ is responsible for converting chemical signals from the antenna into neural signals, confirming IP₃ as a secondary messenger in olfaction perception instead of GPCR in locusts. These findings elucidate the universal function of IP₃ in olfactory signal perception, shedding light on the key nodes of insect olfactory signal transduction.