A rationally designed peptidomimetic modulator of CaV2.2 (N-type) voltage-gated calcium channels for chronic pain

Abstract

Background and Purpose Transmembrane Cav2.2 (N-type) voltage-gated calcium channels are genetically and pharmacologically validated pain targets. Clinical block of Cav2.2 (e.g., with Prialt) or indirect modulation (e.g., with gabapentinoids) mitigates chronic pain but is constrained by side effects. The cytosolic auxiliary subunit collapsin response mediator protein 2 (CRMP2) targets Cav2.2 to the sensory neuron membrane and regulates their function. A CRMP2-derived peptide (CBD3) uncouples the Cav2.2-CRMP2 interaction to inhibit calcium influx, transmitter release and pain. Homology-guided mutagenesis of CBD3 revealed an antinociceptive core at A1RSR4. Here, the A1R2 CBD3 dipeptide was identified as critical for Cav2.2 molecular recognition and served as a scaffold for identification of small molecule peptidomimetic allosteric regulators of Cav2.2. Experimental Approach We developed and applied a novel molecular dynamics approach to identify the Cav2.2 recognition motif of the core CBD3 peptide as the A1R2 dipeptide and used its presenting motif to design pharmacophore models to screen 27 million compounds in the open access server ZincPharmer. Of 200 curated hits, 77 compounds were assessed using depolarization‐evoked calcium influx in rat dorsal root ganglion (DRG) neurons. Nine compounds were tested using electrophysiology and one compound (CBD3063) was evaluated biochemically, electrophysiologically, and behaviorally effects in a model of experimental pain: Key Results CBD3063 reduced membrane Cav2.2 expression and currents, inhibited neuronal excitability, uncoupled the Cav2.2-CRMP2 interaction, and reversed mechanical allodynia in rats with spared nerve injury. Conclusions and Implications These results identify CBD3063, as a selective, first-in-class, CRMP2-based peptidomimetic, which allosterically regulates Cav2.2 to achieve analgesia.