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 4

SNS-Nedd4L–/– mice show increased Nav1.7 and Nav1.8 currents in DRG neurons and increased expression of Nav1.7 along the sciatic nerve.

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SNS-Nedd4L–/– mice show increased Nav1.7 and Nav1.8 currents in DRG neu...
(A and B) Immunofluorescence of NEDD4-2 in coronal sections of L4 DRG from Nedd4Lfl/fl and SNS-Nedd4L–/– mice. Scale bars: 30 μm. (C and D) Immunofluorescence and corresponding bright-field images of NEDD4-2 in DRG neurons from Nedd4Lfl/fl and SNS-Nedd4L–/– mice after whole-cell patch-clamp recordings (36 hours after dissociation). Scale bars: 30 μm. (E) Western blot and quantification showing NEDD4-2 decrease in the DRG (**P = 0.003) of SNS-Nedd4L–/– mice compared with control Nedd4Lfl/fl mice. (F and G) Scatter dot plots representing Navtotal, Nav1.7, Nav1.8, and NavrTTXs current densities in L4/5 DRG neurons from SNS-Nedd4L–/– and Nedd4Lfl/fl mice. Slow (F, in cyan) and fast (G, in magenta) neurons are shown. Mann-Whitney U test. See Supplemental Figure 4A for total population and Supplemental Table 3 for values and biophysical properties. (H) Left panel: Western blot analysis and quantification of Nav α subunits in the DRG of SNS-Nedd4L–/– and Nedd4Lfl/fl mice. No significant modifications in Navtotal (P = 0.054) or Nav1.7 (P = 0.646) were observed, whereas the Nav1.8 signal was increased in the SNS-Nedd4L–/– mice (*P = 0.020). Right panel: same as above, but for sciatic nerves. Nav1.7 was significantly increased (*P = 0.022), whereas the increase in Navtotal was not significant (P = 0.089). Data are expressed as the means ± SEM; n = 4 samples for each group. Student’s t test. Tubulin was used as a loading control in E and H.