Disordered but effective: short linear motifs as gene therapy targets for hyperexcitability disorders

Sensory neuron-specific block of multifaceted sodium channels mitigates neuropathic pain behaviors of osteoarthritis

Objective

Multiple voltage-gated sodium channels (NaVs) in the peripheral sensory neurons (PSNs) regulate action potentials and their dysfunction contributes to the pain pathogenesis of osteoarthritis (OA). A combined block of multiple NaV subtypes selectively in the PSNs may, therefore, represent an effective analgesic approach in OA painful neuropathy.

Methods

To test this hypothesis, we generated recombinant adeno-associated virus (AAV) encoding a potent NaV inhibitory peptide aptamer, termed NaViPA1, that has a multipronged feature of inhibiting tetrodotoxin-sensitive NaV1.7, 1.6, 1.1, and 1.3, characterized in our recent report. Adeno-associated virus-encoded NaViPA1 was delivered into the ipsilateral lumbar 4/5 dorsal root ganglia of rats 2 weeks after induction of knee monoiodoacetate-OA (MIA-OA) and evoked and spontaneous sensory behaviors were followed in 6 weeks.

Results

Expression of NaViPA1 selective in the PSNs produced significant and comparable mitigations of evoked and spontaneous pain behavior and reversal of weight-bearing asymmetry in both male and female MIA-OA rats. Whole-cell current-clamp recordings showed that AAV-mediated NaViPA1 expression normalized action potential firing of the PSNs from MIA animals, suggesting that NaViPA1 attenuated pain behavior by, at least in part, reversing neuronal hyperexcitability.

Conclusion

Together, these results support that (1) NaVs in peripheral sensory pathways contribute to MIA-OA pain pathogenesis and (2) NaViPA1 is a promising analgesic lead that, combined with AAV-targeted delivery to pathological sensory ganglia, may be a viable peripherally selective PSN-targeting strategy in mitigating chronic MIA-OA pain behaviors.

Beyond single targets: leveraging degeneracy in sodium channels for osteoarthritis analgesia

Commentary on: Shin SM, Itson-Zoske B, Xu H, Xiang H, Fan F, Hogan QH, Yu H. Sensory neuron-specific block of multifaceted sodium channels mitigates neuropathic pain behaviors of osteoarthritis. Pain Rep 2025. DOI: 10.1097/PR9.0000000000001288.

Voltage-gated sodium channels in excitable cells as drug targets

Excitable cells - including neurons, muscle cells and cardiac myocytes - are unique in expressing high densities of voltage-gated sodium (NaV) channels. This molecular adaptation enables these cells to produce action potentials, and is essential to their function. With the advent of the molecular revolution, the concept of 'the' sodium channel has been supplanted by understanding that excitable cells in mammals can express any of nine different forms of sodium channels (NaV1.1-NaV1.9). Selective expression in particular types of cells, together with a key role in controlling action potential firing, makes some of these NaV subtypes especially attractive molecular targets for drug development. Although these different channel subtypes display a common overall structure, differences in their amino acid sequences have provided a basis for the development of subtype-specific drugs. This approach has resulted in exciting progress in the development of drugs for epilepsy, cardiac disorders and pain. In this Review, we discuss recent progress in the development of drugs that selectively target each of the sodium channel subtypes.