Papers of the Week

Pain is the most common presenting physical symptom and a primary reason for seeking medical care, which chronically affects people's mental health and social life. Ca3.2 channel plays an essential role in the peripheral processing maintenance of pain states. This study was designed to identify novel drug candidates targeting the Ca3.2 channel. Whole-cell patch-clamp, cellular thermal shift assay, FlexStation, in vivo and in vitro Ca3.2 knock-down, site-directed mutagenesis, and double-mutant cycle analysis were employed to explore the pain-related receptors and ligand-receptor direct interaction. We found that toddaculin efficiently inhibits the Ca3.2 channel and significantly reduced the excitability of dorsal root ganglion neurons and pain behaviors. The Carbonyl group of coumarins directly interacts with the pore domain of Ca3.2 via van der Waals (VDW) force. Docking with binding pockets further led us to identify glycycoumarin, which exhibited more potent inhibition on the Ca3.2 channel and better analgesic activity than the parent compound. Toddaculin and its analog showed beneficial therapeutic effects in pain models. Toddaculin binding pocket on Ca3.2 might be a promising docking site for the design of drugs.