Nogo Receptor Research Articles

NgR1: A Tunable Sensor Regulating Memory Formation, Synaptic, and Dendritic Plasticity.

Nogo receptor 1 (NgR1) is expressed in forebrain neurons and mediates nerve growth inhibition in response to Nogo and other ligands. Neuronal activity downregulates NgR1 and the inability to downregulate NgR1 impairs long-term memory. We investigated behavior in a serial behavioral paradigm in mice that overexpress or lack NgR1, finding impaired locomotor behavior and recognition memory in mice lacking NgR1 and impaired sequential spatial learning in NgR1 overexpressing mice. We also investigated a role for NgR1 in drug-mediated sensitization and found that repeated cocaine exposure caused stronger locomotor responses but limited development of stereotypies in NgR1 overexpressing mice. This suggests that NgR1-regulated synaptic plasticity is needed to develop stereotypies. Ex vivo magnetic resonance imaging and diffusion tensor imaging analyses of NgR1 overexpressing brains did not reveal any major alterations. NgR1 overexpression resulted in significantly reduced density of mature spines and dendritic complexity. NgR1 overexpression also altered cocaine-induced effects on spine plasticity. Our results show that NgR1 is a negative regulator of both structural synaptic plasticity and dendritic complexity in a brain region-specific manner, and highlight anterior cingulate cortex as a key area for memory-related plasticity.

Improved neurite outgrowth on central nervous system myelin substrate by siRNA-mediated knockdown of Nogo receptor

PurposeTo investigate the in vitro effect of short interfering RNAs (siRNAs) against Nogo receptor (NgR) on neurite outgrowth under an inhibitory substrate of central nervous system (CNS) myelin. MethodsThree siRNA sequences against NgR were designed and transfected into cerebellar granule cells (CGCs) to screen for the most efficient sequence of NgR siRNA by using reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence staining. NgR siRNA sequence 1 was found the most efficient which was then transfected into the CGCs grown on CNS myelin substrate to observe its disinhibition for neurite outgrowth. ResultsCompared with the scrambled control sequence of siRNA, the NgR siRNA sequence 1 significantly decreased NgR mRNA level at 24 h and 48 h (p < 0.05), which was recovered by 96 h after transfection. NgR immunoreactivity was also markedly reduced at 24 and 48 h after the transfection of siRNA sequence 1 compared with that before transfection (p < 0.05). The NgR immunoreactivity was recovered after 72 h post-transfection. Moreover, the neurite outgrowth on the myelin substrate was greatly improved within 72 h after the transfection with siRNA sequence 1 compared with the scrambled sequence-transfected group or non-transfected group (p < 0.05). Conclusion: siRNA-mediated knockdown of NgR expression contributes to neurite outgrowth in vitro.

Structural Determinants and Binding Properties of the Neurite Outgrowth Inhibitor (NOGO)

Compelling evidence indicates that repair of damage to the central nervous system (CNS) is inhibited by the presence of protein factors within myelin that prevent axonal regrowth. Myelin growth inhibitors and their common receptor have been identified as targets in the treatment of spinal cord injury, MS, ALS and stroke. We have determined the NMR structure of one of the myelin growth inhibitors, the neurite outgrowth inhibitor (Nogo). We studied the structure of this protein alone and in the presence of dodecylphosphocholine micelles to mimic the natural cell membrane environment. To understand interactions between Nogo and lipid, we hypothesize that aromatic groups and a negative charge hyperconserved among this family of proteins drive the remarkably strong association of Nogo-66 with a phosphocholine surface. We modeled the docking of dodecylphosphocholine (DPC) with Nogo-66 and found that a lipid choline group could form a stable salt bridge with Glu26 and serve as a membrane anchor point. To test the role of the Glu26 anion in binding choline, we mutated this residue to alanine and assessed the structural consequences, the association with lipid and the affinity for the Nogo receptor. Paramagnetic probes allowed us to define portions of the growth inhibitor that are accessible to solvent (and consequently the Nogo receptor). Using computational docking methods, NMR data and mutagenesis results, we calculated the optimal protein-protein interface between our structure of Nogo and the Nogo receptor. This model has inspired the development of compounds that can bind and block Nogo.

Experimental and Clinical Advances in Immunotherapy Strategies for Spinal Cord Injury Target on MAIs and Their Receptors.

In the injured adult mammalian central nervous system (CNS), the failure of axonal regeneration is thought to be attributed, at least in part, to various myelin-associated inhibitors (MAIs), such as Nogo, myelinassociated glycoprotein (MAG), and oligodendrocyte-myelin glycoprotein (OMgp) around the damaged site. Interestingly, these three structurally different inhibitors share two common receptors, Nogo-66 receptor (NgR) and paired immunoglobulin-like receptor B (PirB), and transduce the inhibitory signal into neurons via their complex combinant and co-receptors, such as p75 neurotrophin receptor (p75NTR), Nogo receptor-interacting protein 1 (LINGO-1), and TROY. Accordingly, targeting of the whole myelin or just portions by immunization has been proved to be neuroprotective and is able to promote regeneration in the injured spinal cords. In the past few years, vaccine approaches were initially achieved and could induce the production of antibodies against inhibitors in myelin to block the inhibitory effects and promote functional recovery in spinal cord injury (SCI) models by immunizing with MAIs, such as purified myelin, spinal cord homogenates, or their receptors with the concept of protective autoimmunity formulated. However, for safety consideration, further work is necessary before the immunotherapy strategies can be adopted to treat human injured spinal cords.

Axonal Regeneration-related Molecules as Biomarkers for Multiple Sclerosis

Abnormalities in both the nervous and immune systems are thought to be relevant to the pathogenesis of multiple sclerosis (MS). Several functional molecules closely related to axonal regeneration play an important role in not only the nervous system, but also the immune system. Many recent studies revealed that these molecules are associated with the neurological and immunological aspects of the pathogenesis of MS. Therefore, we focused on these molecules as promising biomarkers for MS. Nogo protein and its receptor (Nogo receptor-1; NgR1) are well known representative molecules that prevent axonal regeneration, and we identified lateral olfactory tract usher substance (LOTUS) as an endogenous antagonist of NgR1. We found that LOTUS expression was decreased in the spinal cord in an experimental autoimmune encephalomyelitis mouse model and that variations in LOTUS concentration in the cerebrospinal fluid correlated well with disease activity in MS patients. On the other hand, previous studies have shown that repulsive guidance molecule-a and semaphorins, known to be involved in axonal guidance and regeneration, play a role in MS pathogenesis. We review the association of these molecules with the neurological and immunological aspects of MS pathogenesis, and we show that they are promising, clinically-relevant biomarkers for MS.

Soluble LILRA3 promotes neurite outgrowth and synapses formation through a high-affinity interaction with Nogo 66.

Inhibitory proteins, particularly Nogo 66, a highly conserved 66-amino-acid loop of Nogo A (an isoform of RTN4), play key roles in limiting the intrinsic capacity of the central nervous system (CNS) to regenerate after injury. Ligation of surface Nogo receptors (NgRs) and/or leukocyte immunoglobulin-like receptor B2 (LILRB2) and its mouse orthologue the paired immunoglobulin-like receptor B (PIRB) by Nogo 66 transduces inhibitory signals that potently inhibit neurite outgrowth. Here, we show that soluble leukocyte immunoglobulin-like receptor A3 (LILRA3) is a high-affinity receptor for Nogo 66, suggesting that LILRA3 might be a competitive antagonist to these cell surface inhibitory receptors. Consistent with this, LILRA3 significantly reversed Nogo-66-mediated inhibition of neurite outgrowth and promoted synapse formation in primary cortical neurons through regulation of the ERK/MEK pathway. LILRA3 represents a new antagonist to Nogo-66-mediated inhibition of neurite outgrowth in the CNS, a function distinct from its immune-regulatory role in leukocytes. This report is also the first to demonstrate that a member of LILR family normally not expressed in rodents exerts functions on mouse neurons through the highly homologous Nogo 66 ligand.

Effect of sevoflurane anesthesia on the comprehensive mRNA expression profile of the mouse hippocampus.

Postoperative nausea and vomiting (PONV) is a common complication after general anesthesia. Recent studies suggested that the hippocampus is involved in PONV. Hypothesising that hippocampal dopaminergic neurons are related to PONV, we examined the comprehensive mRNA profile of the hippocampus, using a sevoflurane-treated mouse model to confirm this. This study was conducted after approval from our institutional animal ethics committee, the Animal Research Center of Sapporo Medical University School of Medicine (project number: 12-033). Eight mice were assigned to two groups: a naïve group and a sevoflurane group (Sev group). In the Sev group, four mice were anesthetised with 3.5% sevoflurane for 1 hour. Subsequently, mRNA was isolated from their hippocampal cells and RNA sequencing was performed on an Illumina HiSeq 2500 platform. Mapping of the quality-controlled, filtered paired-end reads to mouse genomes and quantification of the expression levels of each gene were performed using R software. The Rtn4rl2 gene that encodes the Nogo receptor was the most up-regulated gene in the present study. The expression levels of dopamine receptor genes and the tachykinin gene were increased by sevoflurane exposure, while the genes related to serotonin receptors were not altered by sevoflurane exposure. The expression levels of LIM-homeodomain-related genes were highly down-regulated by sevoflurane. These findings suggest that sevoflurane exposure induces dopaminergic stimulation of hippocampal neurons and triggers PONV, while neuronal inflammation caused by LIM-homeodomain-related genes is down-regulated by sevoflurane.

A novel Nogo-66 receptor antagonist peptide promotes neurite regeneration in vitro.

The Nogo-66 receptor (NgR1), a receptor for Nogo-A, contributes to the inhibition of axonal regeneration in the adult central nervous system after traumatic injuries. Thus, NgR1 has been considered a critical target in axon regeneration therapy. Here, we identified a specific NgR1 antagonist peptide (HIYTALV, named NAP2) which promotes neurite regeneration in vitro from a phage display heptapeptide library. NAP2 was co-localized with NgR1 on the surface of PC12 cells and cerebellar granule cells (CGCs) by immunofluorescence assay. Horseradish peroxidase (HRP)-streptavidin-biotin assay further showed that NAP2 binds to NgR1 and the dissociation constant (Kd) was 0.45 μM Functional analyses indicated that NAP2 could reduce the inhibitory effects of Nogo-66 on neurite outgrowth in differentiated PC12 cells and CGCs by blocking the Nogo-66-induced activation of Rho-associated coiled coil-containing protein kinase (ROCK), collapsin response mediator protein 2 (CRMP2) and myosin light chain (MLC). Taken together, the small molecule NgR1 antagonist peptide NAP2 (MW: 815.98Da) has a potential ability in crossing blood brain barrier and will be a promising therapeutic agent for the treatment of spinal cord injury and neurodegenerative diseases.

Erasure of fear memories is prevented by Nogo Receptor 1 in adulthood.

Critical periods are temporary windows of heightened neural plasticity early in development. For example, fear memories in juvenile rodents are subject to erasure following extinction training, while after closure of this critical period, extinction training only temporarily and weakly suppresses fear memories. Persistence of fear memories is important for survival, but the inability to effectively adapt to the trauma is a characteristic of post-traumatic stress disorder. We examined whether Nogo Receptor 1 (NgR1) regulates the plasticity associated with fear extinction. Loss of NgR1 function in adulthood eliminates spontaneous fear recovery and fear renewal, with a restoration of fear reacquisition rate to equal that of naïve mice; thus mimicking the phenotype observed in juvenile rodents. Regional gene disruption demonstrates that NgR1 expression is required in both the basolateral amygdala (BLA) and infralimbic (IL) cortex to prevent fear erasure. NgR1 expression by parvalbumin expressing interneurons is essential for limiting extinction-dependent plasticity. NgR1 gene deletion enhances anatomical changes of inhibitory synapse markers after extinction training. Thus, NgR1 robustly inhibits elimination of fear expression in the adult brain and could serve as a therapeutic target for anxiety disorders, such as post-traumatic stress disorder (PTSD).

Association of multiple sclerosis with lateral olfactory tract usher substance (LOTUS), a possible endogenous inhibitor of axonal degeneration

AbstractNeuronal regeneration in the adult mammalian central nervous system (CNS) is restricted after brain injury, and some of myelin components and their common receptor, Nogo receptor‐1 (NgR1), have been identified as the key molecules for limiting axonal regeneration in the CNS. They have been widely studied as therapeutic targets to overcome the limitation of neuronal regeneration, and strategies using antagonism to NgR1 are expected for the development of the most promising therapies. Recently signaling through NgR1 was shown to be an underlying mechanism of axonal degeneration in multiple sclerosis (MS). Although MS is generally considered an autoimmune demyelinating disorder, axonal degeneration has recently attracted attention as an important pathological feature and one of the mechanisms leading to progressive neurological disability. These pathological and clinical features of MS suggest that molecules involved in limitation of axonal growth can be potential candidates for MS biomarker and therapeutic target, and recent studies have supported these hypotheses. We have previously identified a novel endogenous NgR1 antagonist and named it lateral olfactory tract usher substance (LOTUS). Our data showed that LOTUS promotes axonal growth through blocking of NgR1 signaling, suggesting that LOTUS could be an endogenous inhibitor of axonal degeneration. Furthermore, our recent study demonstrated an interesting variation of LOTUS level in the cerebrospinal fluid of MS patients that was well correlated with disease activity. Here, we review the association of MS with the molecules related to axonal growth including LOTUS, and discuss the clinical application of LOTUS as a promising biomarker and therapeutic target.

Comprehensive Corticospinal Labeling with mu-crystallin Transgene Reveals Axon Regeneration after Spinal Cord Trauma in ngr1-/- Mice.

Axon regeneration fails in the adult CNS, resulting in permanent functional deficits. Traditionally, inefficient extrinsic tracers such a biotinylated dextran amine (BDA) are used to label regenerating fibers after therapeutic intervention. We introduce crym-green fluorescent protein (GFP) transgenic mice as a comprehensive and specific tool with which to study the primary descending motor tract, the corticospinal tract (CST). CST labeling with crym-GFP is 10 times more efficient compared with BDA. The enhanced sensitivity afforded by crym-GFP revealed significant CST regeneration in NgR1 knock-out mice. Therefore, crym-GFP can be used as a standardized tool for future CST spinal cord injury studies.

The Nogo/Nogo Receptor (NgR) Signal Is Involved in Neuroinflammation through the Regulation of Microglial Inflammatory Activation

Microglia have been proposed to play a pivotal role in the inflammation response of the CNS by expressing a range of proinflammatory enzymes and cytokines under pathological stimulus. Our previous study has confirmed that Nogo receptor (NgR), an axon outgrowth inhibition receptor, is also expressed on microglia and regulates cell adhesion and migration behavior in vitro. In the present study, we further investigated the proinflammatory effects and possible mechanisms of Nogo on microglia in vitro. In this study, Nogo peptide, Nogo-P4, a 25-amino acid core inhibitory peptide sequence of Nogo-66, was used. We found that Nogo-P4 was able to induce the expression of inducible nitric-oxide synthase and cyclooxygenase-2 and the release of proinflammatory cytokines, including IL-1β, TNF-α, NO, and prostaglandin E2 in microglia, which could be reversed by NEP1-40 (Nogo-66(1-40) antagonist peptide), phosphatidylinositol-specificphospholipase C, or NgR siRNA treatment. After Nogo-P4 stimulated microglia, the phosphorylation levels of NF-κB and STAT3 were increased obviously, which further mediated microglia expressing proinflammatory factors induced by Nogo-P4. Taken together, we concluded that Nogo peptide could directly take part in CNS inflammatory process by influencing the expression of proinflammatory factors in microglia, which were related to the NF-κB and STAT3 signal pathways. Besides neurite outgrowth restriction, the Nogo/NgR signal might be involved in multiple processes in various inflammation-associated CNS diseases.

Nogo Receptor Signaling Restricts Adult Neural Plasticity by Limiting Synaptic AMPA Receptor Delivery.

Experience-dependent plasticity is limited in the adult brain, and its molecular and cellular mechanisms are poorly understood. Removal of the myelin-inhibiting signaling protein, Nogo receptor (NgR1), restores adult neural plasticity. Here we found that, in NgR1-deficient mice, whisker experience-driven synaptic α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) insertion in the barrel cortex, which is normally complete by 2 weeks after birth, lasts into adulthood. In vivo live imaging by two-photon microscopy revealed more AMPAR on the surface of spines in the adult barrel cortex of NgR1-deficient than on those of wild-type (WT) mice. Furthermore, we observed that whisker stimulation produced new spines in the adult barrel cortex of mutant but not WT mice, and that the newly synthesized spines contained surface AMPAR. These results suggest that Nogo signaling limits plasticity by restricting synaptic AMPAR delivery in coordination with anatomical plasticity.

LINGO-1 antibody ameliorates myelin impairment and spatial memory deficits in experimental autoimmune encephalomyelitis mice.

More than 50% of multiple sclerosis patients develop cognitive impairment. However, the underlying mechanisms are still unclear, and there is no effective treatment. LINGO-1 (LRR and Ig domain containing NOGO receptor interacting protein 1) has been identified as an inhibitor of oligodendrocyte differentiation and myelination. Using the experimental autoimmune encephalomyelitis (EAE) mouse model, we assessed cognitive function at early and late stages of EAE, determined brain expression of myelin basic protein (MBP) and investigated whether the LINGO-1 antibody could restore deficits in learning and memory and ameliorate any loss of MBP. We found that deficits in learning and memory occurred in late EAE and identified decreased expression of MBP in the parahippocampal cortex (PHC) and fimbria-fornix. Moreover, the LINGO-1 antibody significantly improved learning and memory in EAE and partially restored MBP in PHC. Furthermore, the LINGO-1 antibody activated the AKT/mTOR signaling pathway regulating myelin growth. Our results suggest that demyelination in the PHC and fimbria-fornix might contribute to cognitive deficits and the LINGO-1 antibody could ameliorate these deficits by promoting myelin growth in the PHC. Our research demonstrates that LINGO-1 antagonism may be an effective approach to the treatment of the cognitive impairment of multiple sclerosis patients.

Expression of Nogo receptor 1 in microglia during development and following traumatic brain injury

As the receptor of myelin associated inhibitory factors Nogo receptor 1 (NgR1) plays an important role in central nervous system (CNS) injury and regeneration. It is found that NgR1 complex acts in neurons to transduce the signals intracelluarly including induction of growth cone collapse, inhibition of axonal regeneration and regulation of nerve inflammation. In recent studies, NgR1 has also been found to be expressed in the microglia. However, NgR1 expressed in microglia in the developing nervous systems and following CNS injury have not been widely investigated. In this study, we detected the expression and cellular localization of NgR1 in microglia during development and following traumatic brain injury (TBI) in mice. The results showed that NgR1 was mainly expressed in microglia during embryonic and postnatal periods. The expression levels peaked at P4 and decreased thereafter into adulthood, while increased significantly with aging representatively at 17 mo. On the other hand, there was no significant difference in the number of double positive NgR1+Iba1+ cells between normal and TBI group. In summary, we first detected the expression of NgR1 in microglia during development and found that NgR1 protein expression increased significantly in microglia with aging. These findings will contribute to make a foundation for subsequent study about the role of NgR1 expressed in microglia on the CNS disorders.

Sugar-dependent modulation of neuronal development, regeneration, and plasticity by chondroitin sulfate proteoglycans

Chondroitin sulfate proteoglycans (CSPGs) play important roles in the developing and mature nervous system, where they guide axons, maintain stable connections, restrict synaptic plasticity, and prevent axon regeneration following CNS injury. The chondroitin sulfate glycosaminoglycan (CS GAG) chains that decorate CSPGs are essential for their functions. Through these sugar chains, CSPGs are able to bind and regulate the activity of a diverse range of proteins. CSPGs have been found both to promote and inhibit neuronal growth. They can promote neurite outgrowth by binding to various growth factors such as midkine (MK), pleiotrophin (PTN), brain-derived neurotrophic factor (BDNF) and other neurotrophin family members. CSPGs can also inhibit neuronal growth and limit plasticity by interacting with transmembrane receptors such as protein tyrosine phosphatase σ (PTPσ), leukocyte common antigen-related (LAR) receptor protein tyrosine phosphatase, and the Nogo receptors 1 and 3 (NgR1 and NgR3). These CS–protein interactions depend on specific sulfation patterns within the CS GAG chains, and accordingly, particular CS sulfation motifs are upregulated during development, in the mature nervous system, and in response to CNS injury. Thus, spatiotemporal regulation of CS GAG biosynthesis may provide an important mechanism to control the functions of CSPGs and to modulate intracellular signaling pathways. Here, we will discuss these sulfation-dependent processes and highlight how the CS sugars on CSPGs contribute to neuronal growth, axon guidance, and plasticity in the nervous system.

An in vitro study of peptide-loaded alginate nanospheres for antagonizing the inhibitory effect of Nogo-A protein on axonal growth

The adult mammalian central nervous system has limited ability to regenerate after injury. This is due, in part, to the presence of myelin-associated axon growth inhibitory proteins such as Nogo-A that bind and activate the Nogo receptor, leading to profound inhibition of actin-based motility within the growing axon tip. This paper presents an in vitro study of the use of a Nogo receptor-blocking peptide to antagonize the inhibitory effect of Nogo-A on axon growth. Alginate nanospheres were fabricated using an emulsion technique and loaded with Nogo receptor-blocking peptide, or with other model proteins. Protein release profiles were studied, and retention of the bioactivity of released proteins was verified. Primary dorsal root ganglion neurons were cultured and their ability to grow neurites was challenged with Nogo-A chimeric protein in the absence or presence of Nogo receptor antagonist peptide-loaded alginate nanospheres. Our results demonstrate that peptide released from alginate nanospheres could overcome the growth inhibitory effect of Nogo-A, suggesting that a similar peptide delivery strategy using alginate nanospheres might be used to improve axon regeneration within the injured central nervous system.

Sustained dual drug delivery of anti-inhibitory molecules for treatment of spinal cord injury

Myelin-associated inhibitors (MAIs) and chondroitin sulfate proteoglycans (CSPGs) are major contributors to axon growth inhibition following spinal cord injury and limit functional recovery. The NEP1-40 peptide competitively binds the Nogo receptor and partially blocks inhibition from MAIs, while chondroitinase ABC (ChABC) enzymatically digests CSPGs, which are upregulated at the site of injury. In vitro studies showed that the combination of ChABC and NEP1-40 increased neurite extension compared to either treatment alone when dissociated embryonic dorsal root ganglia were seeded onto inhibitory substrates containing both MAIs and CSPGs. Furthermore, the ability to provide sustained delivery of biologically active ChABC and NEP1-40 from biomaterial scaffolds was achieved by loading ChABC into lipid microtubes and NEP1-40 into poly (lactic-co-glycolic acid) (PLGA) microspheres, obviating the need for invasive intrathecal pumps or catheters. Fibrin scaffolds embedded with the drug delivery systems (PLGA microspheres and lipid microtubes) were capable of releasing active ChABC for up to one week and active NEP1-40 for over two weeks in vitro. In addition, the loaded drug delivery systems in fibrin scaffolds decreased CSPG deposition and development of a glial scar, while also increasing axon growth after spinal cord injury in vivo. Therefore, the sustained, local delivery of ChABC and NEP1-40 within the injured spinal cord may block both myelin and CSPG-associated inhibition and allow for improved axon growth.

Polymorphism within a Neuronal Activity-Dependent Enhancer of NgR1 Is Associated with Corpus Callosum Morphology in Humans

The human Nogo-66 receptor 1 (NgR1) gene, also termed Nogo receptor 1 or reticulon 4 receptor (RTN4R) and located within 22q11.2, inhibits axonal growth and synaptic plasticity. Patients with the 22q11.2 deletion syndrome show multiple changes in brain morphology, with corpus callosum (CC) abnormalities being among the most prominent and frequently reported. Thus, we hypothesized that, in humans, NgR1 may be involved in CC formation. We focused on rs701428, a single nucleotide polymorphism of NgR1, which is associated with schizophrenia. We investigated the effects of the rs701428 genotype on CC structure in 50 healthy participants using magnetic resonance imaging. Polymorphism of rs701428 was associated with CC structural variation in healthy participants; specifically, minor A allele carriers had larger whole CC volumes and lower radial diffusivity in the central CC region compared with major G allele homozygous participants. Furthermore, we showed that the NgR1 3′ region, which contains rs701428, is a neuronal activity-dependent enhancer, and that the minor A allele of rs701428 is susceptible to regulation of enhancer activity by MYBL2. Our results suggest that NgR1 can influence the macro- and microstructure of the white matter of the human brain.

A common functional allele of the Nogo receptor gene, reticulon 4 receptor (RTN4R), is associated with sporadic amyotrophic lateral sclerosis in a French population

Amyotrophic lateral sclerosis is sporadic (SALS) in 90% of cases and has complex environmental and genetic influences. Nogo protein inhibits neurite outgrowth and is overexpressed in muscle in ALS. Our aims were to study the reticulon 4 receptor gene RTN4R which encodes Nogo 1 receptor (NgR1) in SALS, to test if the variants were associated with variable expression of the gene and whether NgR1 protein expression was modified in a transgenic mouse model of ALS. We genotyped three single nucleotide polymorphisms (SNPs; rs701421, rs701427, and rs1567871) of the RTN4R gene in 364 SALS French patients and 430 controls. We examined expression of RTN4R mRNA by quantitative PCR in control post mortem human brain tissue. We determined the expression of NgR1 protein in spinal motor neurons from a SOD1 G86R ALS mouse model. We observed significant associations between SALS and RTN4R alleles. Messenger RNA expression from RTN4R in human cortical brain tissue correlated significantly with the genotypes of rs701427. NgR1 protein expression was reduced in Nogo A positive motor neurons from diseased transgenic animals. In conclusion, these observations suggest that a functional RTN4R gene variant is associated with SALS. This variant may act in concert with other genetic variants or environmental influences.