Targeting intrinsically disordered regions facilitates discovery of calcium channels 3.2 inhibitory peptides for adeno-associated virus-mediated peripheral analgesia

Pain. 2022 Dec 1;163(12):2466-2484. doi: 10.1097/j.pain.0000000000002650. Epub 2022 Apr 14.

Abstract

Ample data support a prominent role of peripheral T-type calcium channels 3.2 (Ca V 3.2) in generating pain states. Development of primary sensory neuron-specific inhibitors of Ca V 3.2 channels is an opportunity for achieving effective analgesic therapeutics, but success has been elusive. Small peptides, especially those derived from natural proteins as inhibitory peptide aptamers (iPAs), can produce highly effective and selective blockade of specific nociceptive molecular pathways to reduce pain with minimal off-target effects. In this study, we report the engineering of the potent and selective iPAs of Ca V 3.2 from the intrinsically disordered regions (IDRs) of Ca V 3.2 intracellular segments. Using established prediction algorithms, we localized the IDRs in Ca V 3.2 protein and identified several Ca V 3.2iPA candidates that significantly reduced Ca V 3.2 current in HEK293 cells stably expressing human wide-type Ca V 3.2. Two prototype Ca V 3.2iPAs (iPA1 and iPA2) derived from the IDRs of Ca V 3.2 intracellular loops 2 and 3, respectively, were expressed selectively in the primary sensory neurons of dorsal root ganglia in vivo using recombinant adeno-associated virus (AAV), which produced sustained inhibition of calcium current conducted by Ca V 3.2/T-type channels and significantly attenuated both evoked and spontaneous pain behavior in rats with neuropathic pain after tibial nerve injury. Recordings from dissociated sensory neurons showed that AAV-mediated Ca V 3.2iPA expression suppressed neuronal excitability, suggesting that Ca V 3.2iPA treatment attenuated pain by reversal of injury-induced neuronal hypersensitivity. Collectively, our results indicate that Ca V 3.2iPAs are promising analgesic leads that, combined with AAV-mediated delivery in anatomically targeted sensory ganglia, have the potential to be a selective peripheral Ca V 3.2-targeting strategy for clinical treatment of pain.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Analgesia*
  • Analgesics / therapeutic use
  • Animals
  • Aptamers, Peptide* / pharmacology
  • Calcium Channels / metabolism
  • Calcium Channels, T-Type* / metabolism
  • Dependovirus
  • Ganglia, Spinal / metabolism
  • HEK293 Cells
  • Humans
  • Neuralgia* / drug therapy
  • Pain Management
  • Peptides / therapeutic use
  • Rats
  • Rats, Sprague-Dawley
  • Sensory Receptor Cells / metabolism

Substances

  • Analgesics
  • Aptamers, Peptide
  • Peptides
  • Calcium Channels
  • Calcium Channels, T-Type