Kimberly Gomez

and 17 more

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.

Paz Duran

and 21 more

Background and purpose: Postoperative pain occurs in as many as 70% of the over 230 million surgeries performed annually worldwide. Postoperative pain management still relies on opioids despite their negative consequences, resulting in a public health crisis. Therefore, it is of utmost importance to develop alternative therapies to treat chronic pain. Natural products derived from medicinal plants are potential sources of novel and are potential sources biologically active compounds for development of novel analgesics safe analgesics. Experimental approach: Hence, in this study, we screened a library of natural products to identify small molecules that target the activity of voltage-gated sodium and calcium channels due to their important roles in nociceptive sensory processing. Key Results: We found that fractions derived from the Native American medicinal plant, Parthenium incanum, inhibited depolarization-evoked calcium influx in rat dorsal root ganglion (DRG) neurons. Further separation of these fractions yielded a cycloartane-type triterpene identified as argentatin C which blocked the activity of both voltage-gated sodium and calcium channels in calcium imaging assays. Docking analysis predicted that argentatin C may bind to NaV1.7-1.9 and CaV3.1-3.3 channels. Furthermore, voltage and current clamp electrophysiology experiments showed that argentatin C decreased Na+ and T-type Ca2+ currents as well as excitability in rat and macaque DRG neurons. Consistent with these observations, argentatin C treatment reversed mechanical allodynia in a mouse model of postsurgical pain. Conclusions & Implications: The dual effect of argentatin C on voltage-gated sodium and calcium channels supports its potential as a novel treatment for painful conditions.