The control of alternative splicing by SRSF1 in myelinated afferents contributes to the development of neuropathic pain

Richard P Hulse,Robert A.R Drake,David O Bates,Lucy F Donaldson

doi:10.1016/j.nbd.2016.09.009

Richard P Hulse, Robert A.R Drake + Show 2 more

Open Access

https://doi.org/10.1016/j.nbd.2016.09.009

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Abstract

Neuropathic pain results from neuroplasticity in nociceptive neuronal networks. Here we demonstrate that control of alternative pre-mRNA splicing, through the splice factor serine-arginine splice factor 1 (SRSF1), is integral to the processing of nociceptive information in the spinal cord.Neuropathic pain develops following a partial saphenous nerve ligation injury, at which time SRSF1 is activated in damaged myelinated primary afferent neurons, with minimal found in small diameter (IB4 positive) dorsal root ganglia neurons. Serine arginine protein kinase 1 (SRPK1) is the principal route of SRSF1 activation. Spinal SRPK1 inhibition attenuated SRSF1 activity, abolished neuropathic pain behaviors and suppressed central sensitization. SRSF1 was principally expressed in large diameter myelinated (NF200-rich) dorsal root ganglia sensory neurons and their excitatory central terminals (vGLUT1+ve) within the dorsal horn of the lumbar spinal cord.Expression of pro-nociceptive VEGF-Axxxa within the spinal cord was increased after nerve injury, and this was prevented by SRPK1 inhibition. Additionally, expression of anti-nociceptive VEGF-Axxxb isoforms was elevated, and this was associated with reduced neuropathic pain behaviors. Inhibition of VEGF receptor-2 signaling in the spinal cord attenuated behavioral nociceptive responses to mechanical, heat and formalin stimuli, indicating that spinal VEGF receptor-2 activation has potent pro-nociceptive actions. Furthermore, intrathecal VEGF-A165a resulted in mechanical and heat hyperalgesia, whereas the sister inhibitory isoform VEGF-A165b resulted in anti-nociception. These results support a role for myelinated fiber pathways, and alternative pre-mRNA splicing of factors such as VEGF-A in the spinal processing of neuropathic pain. They also indicate that targeting pre-mRNA splicing at the spinal level could lead to a novel target for analgesic development.

Highlights

Insults to the peripheral nervous system usually result in pain and hypersensitivity to noxious and innocuous stimuli
Upon activation, serine-arginine splice factor 1 (SRSF1) is known to translocate from the cytoplasm to the nucleus (Amin et al, 2011; Nowak et al, 2010), where it is involved in pre-mRNA processing
There was an increase in activating transcription factor 3 (ATF3)-positive dorsal root ganglia (DRG) neurons after partial saphenous nerve ligation injury (PSNI) (Fig. 1I–K), with 43% of DRG neurons expressing ATF3 post-PSNI compared to only 1% in naïve animals (Fig. 1K)

Summary

Introduction

Insults to the peripheral nervous system usually result in pain and hypersensitivity to noxious (hyperalgesia) and innocuous (allodynia) stimuli. These abnormal sensations arise due to neuronal plasticity leading to alterations in sensory neuronal excitability. These alterations include peripheral sensitization (Djouhri et al, 2006), with enhanced evoked and on-going activity in primary afferents, and central sensitization, responsible for the generation and maintenance of chronic pain. ⁎ Correspondence to: R.P. Hulse, Cancer Biology, School of Medicine, University of Nottingham, Nottingham NG7 7UH, United Kingdom. ⁎⁎ Correspondence to: L.F. Donaldson, School of Life Sciences and Arthritis Research UK Pain Centre, University of Nottingham, Nottingham, NG7 7UH, United Kingdom

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