Seven novel modulators of the analgesic target Na V 1.7 uncovered using a high‐throughput venom‐based discovery approach

Background and Purpose Chronic pain is a serious worldwide health issue, with current analgesics having limited efficacy and dose‐limiting side effects. Humans with loss‐of‐function mutations in the voltage‐gated sodium channel Na V 1.7 (h Na V 1.7) are indifferent to pain, making h Na V 1.7 a promising target for analgesic development. Since spider venoms are replete with Na V channel modulators, we examined their potential as a source of h Na V 1.7 inhibitors. Experimental Approach We developed a high‐throughput fluorescent‐based assay to screen spider venoms against h Na V 1.7 and isolate ‘hit’ peptides. To examine the binding site of these peptides, we constructed a panel of chimeric channels in which the S 3b‐S4 paddle motif from each voltage sensor domain of h Na V 1.7 was transplanted into the homotetrameric K V 2.1 channel. Key Results We screened 205 spider venoms and found that 40% contain at least one inhibitor of h Na V 1.7. By deconvoluting ‘hit’ venoms, we discovered seven novel members of the NaSpTx family 1. One of these peptides, H d1a (peptide μ‐TRTX‐Hd1a from venom of the spider Haplopelma doriae ), inhibited h Na V 1.7 with a high level of selectivity over all other subtypes, except h Na V 1.1. We showed that H d1a is a gating modifier that inhibits h Na V 1.7 by interacting with the S 3b‐ S 4 paddle motif in channel domain II. The structure of H d1a, determined using heteronuclear NMR , contains an inhibitor cystine knot motif that is likely to confer high levels of chemical, thermal and biological stability. Conclusion and Implications Our data indicate that spider venoms are a rich natural source of h Na V 1.7 inhibitors that might be useful leads for the development of novel analgesics.