ROR2 modulates neuropathic pain via phosphorylation of NMDA receptor subunit GluN2B in rats

Abstract

Background: Neuropathic pain, a type of chronic pain as a result of direct central or peripheral nerve damage, is associated with significant quality of life and functional impairment. Its underlying mechanisms remain unclear. We investigated whether ROR2, a member of the receptor tyrosine kinase-like orphan receptor (ROR) family, participates in modulation of neuropathic pain. Methods: Thermal hyperalgesia and mechanical allodynia were measured using radiant heat and von Frey filament testing. Immunofluorescence staining was used to detect expression of ROR2 in neuronal nuclei. Fos expression was determined by immunocytochemistry. Phosphorylation status was detected by western blot and immunoprecipitation. Small interfering RNA was used to knock down ROR2 expression. Results: ROR2 was upregulated and activated in spinal neurones after chronic constriction injury (CCI) in mice [1.3 (0.1) to 2.1 (0.1)-fold of sham, P<0.01] from Day 1e21. CCI induced significant demethylation of the CpG island in the ROR2 gene promoter [0.37 (0.06) vs 0.12 (0.03)% CpG methylation, P<0.001]. Knockdown of ROR2 in the spinal cord prevented and reversed CCI-induced pain behaviours and spinal neuronal sensitisation [Fos expression: 130 (12) vs 81 (8) cells, P<0.05; 120 (11) vs 70 (7) cells, P<0.05]. In contrast, activation of spinal ROR2 by intrathecal injection of Wnt5a induced pain behaviours and spinal neuronal sensitisation [Fos expression: 11 (1) vs 100 (12) cells, P<0.001] in wild-type mice. Furthermore, ROR2-mediated pain modulation required phosphorylation of N-methyl-D-aspartate receptor 2B subunit (GluN2B) at Ser 1303 and Tyr1472 by pathways involving protein kinase C (PKC) and Src family kinases. Intrathecal injection of GluN2B, PKC, or Src family kinase-specific inhibitors significantly attenuated Wnt5a-induced pain behaviours. Conclusions: ROR2 in the spinal cord regulates neuropathic pain via phosphorylation of GluN2B, suggesting a potential target for prevention and relief of neuropathic pain.

Spinal Wnt5a Plays a Key Role in Spinal Dendritic Spine Remodeling in Neuropathic and Inflammatory Pain Models and in the Proalgesic Effects of Peripheral Wnt3a

“…Technical limitations hinder us from establishing this link. Ryk and Ror2 are expressed widely in spinal neurons in chronic pain states (Liu et al, 2015;Zhou et al, 2019), and are particularly broadly found across the neuropil, rendering it likely that these receptors are indeed expressed on neurons undergoing remodeling in chronic pain states. Our data on localization of these receptors to synaptic markers further render this likely.…”

“…Wnt5a was also implicated in the pathogenesis of EAE-associated chronic pain via inducing the expression of the cytokines known mediators of neuroinflammation (Yuan et al, 2012). Wnt5a is known to bind preferentially the atypical receptors Ror2 and Ryk; interestingly, both receptors have been reported to play a role in neuropathic pain models (Liu et al, 2015;Yang et al, 2017;Zhu et al, 2018;Zhou et al, 2019).…”

<p>Role of Melatonin in the Regulation of Pain</p>

“…Interestingly, accumulated evidence shows that ROR2 is activated and upregulated after CCI, while inhibition of ROR2 reverses the nociceptive effect. 16 Therefore, we speculate that melatonin may exert painpromoting effects through activation of ROR instead of MT receptors, which needs further study.…”

“…[11][12][13] It has been suggested that melatonin regulates pain via membrane receptors, nuclear receptors, and simple diffusion. [14][15][16][17] Given these properties with few adverse side effects, melatonin has potential as a painkiller. The aim of this review is to discuss and analyze different lines of evidence for the effects of melatonin on pain modulation as well as to describe the cellular mechanisms of melatonin as a potential analgesic.…”

Stem Cell Therapy for Modulating Neuroinflammation in Neuropathic Pain

“…Following nerve injury, significant amounts of excitatory neurotransmitter glutamate are continuously released in the synaptic junctions of the spinal dorsal horn, activating the glutamate receptor (Glu-R), N -methyl- d -aspartate (NMDA) receptor (NMDAR), and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA receptor, AMPAR). Receptors then transmit pain signals to sensory brain regions [ 88 , 89 , 90 ]. Studies in various animal models have confirmed that blocking NMDAR can relieve NP [ 91 ].…”