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 (Na v s) expressed in dorsal root ganglion (DRG) sensory neurons. The mechanisms underlying the altered expression of Na v s remain unknown. This study investigated the role of the E3 ubiquitin ligase NEDD4-2, which is known to ubiquitylate Na v s, 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 Na v 1.7-specific inhibitor, ProTxII, allowed the isolation of Na v 1.7-mediated currents. SNI decreased NEDD4-2 expression in DRG cells and increased the amplitude of Na v 1.7 and Na v 1.8 currents. The redistribution of Na v 1.7 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 Na v 1.7 and Na v 1.8 current amplitudes, but also alleviated SNI-induced mechanical allodynia. These findings demonstrate that NEDD4-2 is a potent posttranslational regulator of Na v s and that downregulation of NEDD4-2 leads to the hyperexcitability of DRG neurons and contributes to the genesis of pathological pain.

Hierarchical CRMP2 posttranslational modifications control NaV1.7 function

“…Future studies will aim to dissect if subtle tuning of the CRMP2 modifications that alter NaV1.7 currents can result in significant reduction of pain in animal models. From a mechanistic perspective, the NaV1.7 trafficking pathway identified here greatly extends the findings of Laedermann et al, who reported that the Nedd4-2 ubiquitin ligase monoubiquitinates NaV1.7 to signal the channel's endocytosis (6). Our results suggest that induction of membrane curvature by Eps15 (26,27) to trigger clathrin-mediated endocytosis is required for CRMP2-mediated endocytosis of NaV1.7 via the formation of a CRMP2/Numb/Eps15/ Nedd4-2 complex.…”

“…In neuropathic pain, NaV1.7 surface localization is augmented by loss of Nedd4-2 (neural precursor cell expressed developmentally down-regulated protein 4), an E3 ubiquitin ligase that labels NaV1.7 for endocytosis (6). Inspired by these observations, we tested the hypothesis that a cross-talk between distinct CRMP2 posttranslational modifications is a key factor in determining NaV1.7 trafficking and localization.…”

Blocking CRMP2 SUMOylation reverses neuropathic pain

“…6 In neuropathies associated with diabetes, injury or chemotherapeutic administration, chronic pain can result from upregulated NaV1.7 expression. 18 NaV1.7 is preferentially expressed in peripheral sensory neurons, where activity of this channel determines whether subthreshold stimuli will cumulatively drive action potential generation and pain signaling. 19 The exact pathways leading to the dysregulation of NaV1.7 are poorly understood but likely involve mechanisms related to its surface trafficking and regulation via protein–protein interactions.…”

“…19 The exact pathways leading to the dysregulation of NaV1.7 are poorly understood but likely involve mechanisms related to its surface trafficking and regulation via protein–protein interactions. 18,20–22 Recent studies have identified neuronal CRMP2 as a novel binding partner of NaV1.7. 21,22 Specifically, a selective reduction in NaV1.7 surface expression and current density was observed in rodent and human sensory neurons expressing a mutant CRMP2 lacking the SUMO PTM site (lysine 374) in CRMP2.…”

Ubiquitin-specific Protease 36 (USP36) Controls Neuronal Precursor Cell-expressed Developmentally Down-regulated 4-2 (Nedd4-2) Actions over the Neurotrophin Receptor TrkA and Potassium Voltage-gated Channels 7.2/3 (Kv7.2/3)

“…The in vivo relevance of Nedd4-2 has been recently highlighted. Nedd4-2 knock-out mice die perinatally because of a failure to inflate the lungs (44,45), Nedd4-2 shows a protective regulatory role against the development of cystic fibrosis in lung (45), and it has been directly implicated in the development of peripheral neuropathic pain (46). The role of TrkA on pain has been well established for a long time in mice (47) and humans (48).…”