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Papers of the Week

Papers: 29 Jul 2023 - 4 Aug 2023

2023 Jul 17



Intranasal CRMP2-Ubc9 Inhibitor Regulates Na 1.7 to Alleviate Trigeminal Neuropathic Pain.


Loya-Lopez SI, Allen HN, Duran P, Calderon-Rivera A, Gomez K, Kumar U, Shields R, Zeng R, Dwivedi A, Saurabh S, Korczeniewska OA, Khanna R


Dysregulation of voltage-gated sodium Na 1.7 channels in sensory neurons contributes to chronic pain conditions, including trigeminal neuropathic pain. We previously reported that chronic pain results in part from increased SUMOylation of collapsin response mediator protein 2 (CRMP2), leading to an increased CRMP2/Na 1.7 interaction and increased functional activity of Na 1.7. Targeting this feed-forward regulation, we developed compound , which inhibits CRMP2 SUMOylation mediated by the SUMO-conjugating enzyme Ubc9. We further demonstrated that effectively reduces the functional activity of Na 1.7 channels in dorsal root ganglia neurons and alleviated inflammatory and neuropathic pain. Here, we employed a comprehensive array of investigative approaches, encompassing biochemical, pharmacological, genetic, electrophysiological, and behavioral analyses, to assess the functional implications of Na 1.7 regulation by CRMP2 in trigeminal ganglia (TG) neurons. We confirmed the expression of , , and within TG neurons. Furthermore, we found an interaction between CRMP2 and Na 1.7, with CRMP2 being SUMOylated in these sensory ganglia. Disrupting CRMP2 SUMOylation with compound uncoupled the CRMP2/Na 1.7 interaction, impeded Na 1.7 diffusion on the plasma membrane, and subsequently diminished Na 1.7 activity. Compound also led to a reduction in TG neuron excitability. Finally, when intranasally administered to rats with chronic constriction injury of the infraorbital nerve (CCI-ION), significantly decreased nociceptive behaviors. Collectively, our findings underscore the critical role of CRMP2 in regulating Na 1.7 within TG neurons, emphasizing the importance of this indirect modulation in trigeminal neuropathic pain.