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Wimalasena NK, Taub DG, Shim J, Hakim S, Kawaguchi R, Chen L, El-Rifai M, Geschwind D, Dib-Hajj SD, Waxman SG, Woolf CJ. Na v1.7 gain-of-function mutation I228M triggers age-dependent nociceptive insensitivity and C-LTMR dysregulation. Exp Neurol 2023; 364:114393. [PMID: 37003485 PMCID: PMC10171359 DOI: 10.1016/j.expneurol.2023.114393] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/09/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023]
Abstract
Gain-of-function mutations in Scn9a, which encodes the peripheral sensory neuron-enriched voltage-gated sodium channel Nav1.7, cause paroxysmal extreme pain disorder (PEPD), inherited erythromelalgia (IEM), and small fiber neuropathy (SFN). Conversely, loss-of-function mutations in the gene are linked to congenital insensitivity to pain (CIP). These mutations are evidence for a link between altered sodium conductance and neuronal excitability leading to somatosensory aberrations, pain, or its loss. Our previous work in young adult mice with the Nav1.7 gain-of-function mutation, I228M, showed the expected DRG neuron hyperexcitability, but unexpectedly the mice had normal mechanical and thermal behavioral sensitivity. We now show that with aging both male and female mice with this mutation unexpectedly develop a profound insensitivity to noxious heat and cold, as well skin lesions that span the body. Electrophysiology demonstrates that, in contrast to young mice, aged I228M mouse DRGs have a profound loss of sodium conductance and changes in activation and slow inactivation dynamics, representing a loss-of-function. Through RNA sequencing we explored how these age-related changes may produce the phenotypic changes and found a striking and specific decrease in C-low threshold mechanoreceptor- (cLTMR) associated gene expression, suggesting a potential contribution of this DRG neuron subtype to Nav1.7 dysfunction phenotypes. A GOF mutation in a voltage-gated channel can therefore produce over a prolonged time, highly complex and unexpected alterations in the nervous system beyond excitability changes.
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Affiliation(s)
- Nivanthika K Wimalasena
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Daniel G Taub
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jaehoon Shim
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Sara Hakim
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Riki Kawaguchi
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Lubin Chen
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA; Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Mahmoud El-Rifai
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Dan Geschwind
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Sulayman D Dib-Hajj
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA; Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA; Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Clifford J Woolf
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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