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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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 3

Increase in Nav1.7 and Nav1.8 currents in DRG neurons and increased expression of Nav1.7 along the sciatic nerve after SNI.

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Increase in Nav1.7 and Nav1.8 currents in DRG neurons and increased expr...
(A) Typical recordings of INa in DRG neurons using the V-I protocol and pharmacological isolation of Navtotal, Nav1.7, Nav1.8, and NavrTTXs currents with ProTxII and TTX (see Methods). (B and C) Scatter dot plot representing Navtotal, Nav1.7, Nav1.8, and NavrTTXs current densities in contralateral and ipsilateral sides recorded in L4/5 DRG neurons 1 week after SNI. Slow (B, in cyan) and fast (C, in magenta) neurons are shown. Mann-Whitney U test. See Supplemental Figure 3A for the total population and see Supplemental Table 2 for values and biophysical properties. (D) Left panel: representative Western blot analysis and quantification of Nav α subunits: Navtotal, Nav1.7, and Nav1.8 in DRG 7 days after SNI. No modifications in Navtotal (P = 0.496), Nav1.7 (P = 0.690), or Nav1.8 (P = 0.311) were observed in sham- and SNI-operated mice. Right panel: same as above, but for sciatic nerve preparation. Nav1.7 (*P = 0.045) and Navtotal (*P = 0.021) were significantly increased in SNI compared with the sham samples. The Nav1.8 signal in the SNI sample did not reach significance compared with the background signal in the sham-operated group (P = 0.105) (see Supplemental Figure 3B). The 2 open arrowheads correspond to a distinct band of Nav1.8, with lower molecular weight than the band observed at 250 kDa. Data are expressed as the means ± SEM; n = 4 samples for each group. Student’s t test. Tubulin was used as a loading control. Int., intensity.