Dysregulation of voltage-gated sodium channels by ubiquitin ligase NEDD4-2 in neuropathic pain
Cédric J. Laedermann, … , Hugues Abriel, Isabelle Decosterd
Cédric J. Laedermann, … , Hugues Abriel, Isabelle Decosterd
Published June 17, 2013
Citation Information: J Clin Invest. 2013;123(7):3002-3013. https://doi.org/10.1172/JCI68996.
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Research Article Neuroscience

Dysregulation of voltage-gated sodium channels by ubiquitin ligase NEDD4-2 in neuropathic pain

Abstract

Peripheral neuropathic pain is a disabling condition resulting from nerve injury. It is characterized by the dysregulation of voltage-gated sodium channels (Navs) expressed in dorsal root ganglion (DRG) sensory neurons. The mechanisms underlying the altered expression of Navs remain unknown. This study investigated the role of the E3 ubiquitin ligase NEDD4-2, which is known to ubiquitylate Navs, in the pathogenesis of neuropathic pain in mice. The spared nerve injury (SNI) model of traumatic nerve injury–induced neuropathic pain was used, and an Nav1.7-specific inhibitor, ProTxII, allowed the isolation of Nav1.7-mediated currents. SNI decreased NEDD4-2 expression in DRG cells and increased the amplitude of Nav1.7 and Nav1.8 currents. The redistribution of Nav1.7 channels toward peripheral axons was also observed. Similar changes were observed in the nociceptive DRG neurons of Nedd4L knockout mice (SNS-Nedd4L–/–). SNS-Nedd4L–/– mice exhibited thermal hypersensitivity and an enhanced second pain phase after formalin injection. Restoration of NEDD4-2 expression in DRG neurons using recombinant adenoassociated virus (rAAV2/6) not only reduced Nav1.7 and Nav1.8 current amplitudes, but also alleviated SNI-induced mechanical allodynia. These findings demonstrate that NEDD4-2 is a potent posttranslational regulator of Navs and that downregulation of NEDD4-2 leads to the hyperexcitability of DRG neurons and contributes to the genesis of pathological pain.

Authors

Cédric J. Laedermann, Matthieu Cachemaille, Guylène Kirschmann, Marie Pertin, Romain-Daniel Gosselin, Isabelle Chang, Maxime Albesa, Chris Towne, Bernard L. Schneider, Stephan Kellenberger, Hugues Abriel, Isabelle Decosterd

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Figure 1

Peripheral nerve injury reduces NEDD4-2 expression in DRG.

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Peripheral nerve injury reduces NEDD4-2 expression in DRG. (A and B) Imm...
(A and B) Immunofluorescence of NEDD4-2 in coronal sections of L4 DRG from sham-operated and SNI mice. Scale bars: 30 μm. (C) Representative Western blot analysis showing the decrease in NEDD4-2 at days 7, 21, and 42 after SNI in L4/5 DRG and its associated quantification. Data are expressed as the means ± SEM; n = 4 samples for each time point per group. ***P < 0.001 by 1-way ANOVA with Bonferroni’s post-hoc test. GAPDH was used as a loading control. Lanes were run on the same gel but were noncontiguous. (D) Effect of SNI and SNL on Nedd4-1 and Nedd4L transcripts in L4/5 DRG 7 days after SNI or SNL (injury of L5 spinal nerve). Bar graph showing transcriptional levels of Nedd4-1 and Nedd4L normalized to GAPDH in SNI and SNL groups over the control group (sham for SNI and L4 DRG for SNL). Data represent the mean ± SEM; n = 4 samples per group. Isolated L4/5, L5, or L4 DRG from 2 mice were pooled for each sample and run in triplicate. *P = 0.011, **P = 0.004, Student’s t test. (E) Constitutive transcript levels of Nedd4/Nedd4-like E3 subfamily members in L4/5 DRG 7 days after sham and SNI surgery. Transcript levels were normalized using HPRT as a reference gene and further normalized to Nedd4L levels in sham-operated mice. Data are expressed as the means ± SEM; n = 3–4 samples per group, which were run in triplicate. **P = 0.005, Student’s t test. We detected no amplification of NedL1 in the DRG samples.