CRMP2–Neurofibromin Interface Drives NF1-related Pain

Abstract

An understudied symptom of the genetic disorder Neurofibromatosis type 1 (NF1) is chronic idiopathic pain. We used targeted editing of Nf1 in rats to provide direct evidence of a causal relationship between neurofibromin, the protein product of the Nf1 gene, and pain responses. Our study data identified a protein-interaction network with collapsin response meditator protein 2 (CRMP2) as a node and neurofibromin, syntaxin 1A, and the N-type voltage-gated calcium (CaV2.2) channel as interaction edges. Neurofibromin uncouples CRMP2 from syntaxin 1A. Upon loss/mutation of neurofibromin, as seen in patients with NF1, the CRMP2/Neurofibromin interaction is uncoupled, which frees CRMP2 to interact with both syntaxin 1A and CaV2.2, culminating in increased release of the pro-nociceptive neurotransmitter calcitonin gene-related peptide (CGRP). Our work also identified the CRMP2-derived peptide CNRP1, which uncoupled CRMP2's interactions with neurofibromin, syntaxin 1A, as well as CaV2.2. Here, we tested if CRISPR/Cas9-mediated editing of the Nf1 gene, which leads to functional remodeling of peripheral nociceptors through effects on the tetrodotoxin-sensitive (TTX-S) Na voltage-gated sodium channel (NaV1.7) and CaV2.2, could be affected using CNRP1, a peptide designed to target the CRMP2-neurofibromin interface. The data presented here shows that disrupting the CRMP2-neurofibromin interface is sufficient to reverse the dysregulations of voltage-gated ion channels and neurotransmitter release elicited by Nf1 gene editing. As a consequence of these effects, the CNRP1 peptide reversed hyperalgesia to thermal stimulation of the hindpaw observed in Nf1-edited rats. Our findings support future pharmacological targeting of the CRMP2/neurofibromin interface for NF1-related pain relief.

Activity of T-type calcium channels is independent of CRMP2 in sensory neurons

“…We conclude that CRMP2 regulation of NaV1.7 [9,10,12,13,22,28] is responsible for controlling DRG neurons excitability and that CRMP2 regulation of CaV2.2 is responsible for increased neurotransmitter release at the primary afferent [11,13,17,18]. For future therapeutic targeting, the specificity of action of CRMP2 toward CaV2.2 will reduce the potential for unwanted effects of novel CRMP2-targeted compounds.…”

“…In chronic pain, proteins regulating the N-type (CaV2.2) VGCCs can modulate nociception [1]. One such protein is the collapsin response mediator protein 2 (CRMP2) [3][4][5][6][7][8][9][10][11][12][13][14][15]. Our continuing studies have established CRMP2 as a bona fide binding partner and regulator of the presynaptic trafficking of CaV2.2 [4,8,13,[15][16][17][18].…”

Overlap in synaptic neurological condition susceptibility pathways and the neural pannexin 1 interactome revealed by bioinformatics analyses

“…Moreover, some notable interactions between these proteins and other proteins of interest in the lab were missed by our bioinformatics approach. For example, NF1, a NMDA receptor-interacting protein (Husi et al, 2000) and Ras GTPase that regulates dendritic spines (Oliveira and Yasuda, 2014), interacts with and regulates the microtubuleregulating protein Crmp2 (Moutal et al, 2018), another Panx1-interacting identified by us, that itself regulates dendritic spines and NMDA receptor trafficking (Brustovetsky et al, 2014). Crmp2 also interacts with Crmp1, which was identified as a postsynaptic protein.…”

Evaluation of edonerpic maleate as a CRMP2 inhibitor for pain relief

“…Mouse paw incision and pSNL surgeries were done following published methods [13]. Allodynia was tested as described previously [3,14]. Data was analyzed as described by Chaplan et al [15] using the nonparametric method of Dixon.…”

“…Edonerpic maleate was found to disrupt CRMP2 tetramers [10]. Our previous body of work has established a role for phosphorylated and non-phosphorylated CRMP2 in control of voltage-gated calcium and sodium channels [1,[3][4][5][6][7][8][13][14][15][16][17][18][19][20][21][22]. Therefore, we tested the effect of edonerpic maleate on these channels.…”