TNF-α mediated upregulation of NaV1.7 currents in rat dorsal root ganglion neurons is independent of CRMP2 SUMOylation

Flávio Henrique Pequeno De Macedo, Rosária Dias Aires, Esdras Guedes Fonseca, Renata Cristina Mendes Ferreira, Daniel Portela Dias Machado, Lina Chen, Fang Xiong Zhang, Ivana A. Souza, Virgínia Soares Lemos, Thiago Roberto Lima Romero, Aubin Moutal, Rajesh Khanna, Gerald W. Zamponi, Jader S. Cruz

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Clinical and preclinical studies have shown that patients with Diabetic Neuropathy Pain (DNP) present with increased tumor necrosis factor alpha (TNF-α) serum concentration, whereas studies with diabetic animals have shown that TNF-α induces an increase in NaV1.7 sodium channel expression. This is expected to result in sensitization of nociceptor neuron terminals, and therefore the development of DNP. For further study of this mechanism, dissociated dorsal root ganglion (DRG) neurons were exposed to TNF-α for 6 h, at a concentration equivalent to that measured in STZ-induced diabetic rats that developed hyperalgesia. Tetrodotoxin sensitive (TTXs), resistant (TTXr) and total sodium current was studied in these DRG neurons. Total sodium current was also studied in DRG neurons expressing the collapsin response mediator protein 2 (CRMP2) SUMO-incompetent mutant protein (CRMP2-K374A), which causes a significant reduction in NaV1.7 membrane cell expression levels. Our results show that TNF-α exposure increased the density of the total, TTXs and TTXr sodium current in DRG neurons. Furthermore, TNF-α shifted the steady state activation and inactivation curves of the total and TTXs sodium current. DRG neurons expressing the CRMP2-K374A mutant also exhibited total sodium current increases after exposure to TNF-α, indicating that these effects were independent of SUMOylation of CRMP2. In conclusion, TNF-α sensitizes DRG neurons via augmentation of whole cell sodium current. This may underlie the pronociceptive effects of TNF-α and suggests a molecular mechanism responsible for pain hypersensitivity in diabetic neuropathy patients.

Original languageEnglish (US)
Article number117
JournalMolecular Brain
Volume12
Issue number1
DOIs
StatePublished - Dec 30 2019

Keywords

  • DRG neurons
  • Diabetic neuropathic pain
  • Sodium channel Na1.7
  • Tumor necrosis factor

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

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