Molecular Characterization and Function of the Nogo-66 Receptor (NgR1) Gene in the Chinese Tree Shrew.

BACKGROUND: Nogo-66 receptor (NgR1) is a glycosylphosphatidylinositol-linked cell surface receptor with high affinity for Nogo-66. The binding of Nogo-66 to NgR1 plays a key role in inhibiting neurite growth, limiting synaptic plasticity and mediating Mammalian Reovirus (MRV) infection. The Chinese tree shrew (Tupaia belangeri chinensis) is, a new and valuable experimental animal that is widely used in biomedical research. Although susceptible to MRV, little is known about tree shrew NgR1 and its role in MRV infection. METHODS: In this study, we cloned NgR1 form the Chinese tree shrew by RACE technology and analyzed its characteristics, spatial structure and its tissue expression. We also examined the expression pattern of NgR1 in the response of tree shrew primary nerve cells (tNC) to MRV1/TS/2011 infection. RESULTS: Tree shrew NgR1 was found to have a closer relationship to human NgR1 (90.34%) than to mouse NgR1. Similar to the protein structure of human NgR1, the tree shrew NgR1 has the same leucine-rich repeat (LRR) domain structure that is capped by C-terminal and N-terminal cysteine-rich modules. The tree shrew NgR1 mRNAs were predominantly detected in the central nervous system (CNS), and tree shrew NgR1 can mediate infection by MRV1/TS/2011. CONCLUSIONS: Taken together, these results help to elucidate the function of NgR1 and provide a basis for using the tree shrew as an animal model for studies of the nervous system and infectious diseases.

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.

Nogo­66 promotes ß­amyloid protein secretion via NgR/ROCK­dependent BACE1 activation.

The generation of ß­amyloid protein (Aß) is considered a key step in the pathogenesis of Alzheimer's disease (AD) and the regulation of its production is an important therapeutic strategy. It was hypothesized in the present study that Nogo­A may be involved in AD and may regulate the generation of Aß. Nogo­A is known to act as a major inhibitor of neuron regeneration in the adult central nervous system. A recent study indicated that Nogo­A is associated with AD; however, the underlying effect and molecular mechanisms remain largely elusive. In the present study, the potential effects of Nogo­A on AD were investigated. ELISA was used to detect the levels of Aß, enzymatic activity detection kits were used to determine the activity of secretase enzymes in amyloid precursor protein (APP) metabolism, and western blot analysis was used to detect the expression levels of proteins associated with the APP processing and Nogo­A/Nogo­66 receptor (NgR) signaling pathways. The results revealed that Nogo­66, the major inhibitory region of Nogo­A, promoted neuronal Aß secretion by increasing the activity of ß­secretase 1 via the NgR/Rho­associated coiled­coil containing kinases pathway in a dose­dependent manner. The present data suggested that Nogo­A may facilitate the onset and development of AD by promoting Aß secretion, providing information on a potential novel target for AD therapy.

Nucleic Acid Vaccine Targeting Nogo-66 Receptor and Paired Immunoglobulin-Like Receptor B as an Immunotherapy Strategy for Spinal Cord Injury in Rats.

Nogo-66 receptor (NgR) and paired immunoglobulin-like receptor B (PirB) are two common receptors of various myelin-associated inhibitors (MAIs) and, thus, play an important role in MAIs-induced inhibitory signalling of regeneration following spinal cord injury (SCI). Based on the concept of protective autoimmunity, vaccine approaches could induce the production of antibodies against inhibitors in myelin, such as using purified myelin, spinal cord homogenates, or MAIs receptor NgR, in order to block the inhibitory effects and promote functional recovery in SCI models. However, due to the complication of the molecules and the mechanisms involved in MAIs-mediated inhibitory signalling, these immunotherapy strategies have yielded inconsistent outcomes. Therefore, we hypothesized that the choice and modification of self-antigens, and co-regulating multiple targets, may be more effective in repairing the injured spinal cord and improving functional recovery. In this study, NgR and PirB were selected to construct a double-targeted granulocyte-macrophage colony stimulating factor-NgR-PirB (GMCSF-NgR-PirB) nucleic acid vaccine, and investigate the efficacy of this immunotherapy in a spinal cord injury model in rats. The results showed that this vaccination could stimulate the production of antibodies against NgR and PirB, block the inhibitory effects mediated by various MAIs, and promote nerve regeneration and functional recovery after spinal cord injury. These findings suggest that nucleic acid vaccination against NgR and PirB can be a promising therapeutic strategy for SCI and other central nervous system diseases and injuries.

Soluble Nogo receptor 1 fusion protein protects neural progenitor cells in rats with ischemic stroke.

Soluble Nogo66 receptor-Fc protein (sNgR-Fc) enhances axonal regeneration following central nervous system injury. However, the underlying mechanisms remain unclear. In this study, we investigated the effects of sNgR-Fc on the proliferation and differentiation of neural progenitor cells. The photothrombotic cortical injury model of ischemic stroke was produced in the parietal cortex of Sprague-Dawley rats. The rats with photothrombotic cortical injury were randomized to receive infusion of 400 µg/kg sNgR-Fc (sNgR-Fc group) or an equal volume of phosphate-buffered saline (photothrombotic cortical injury group) into the lateral ventricle for 3 days. The effects of sNgR-Fc on the proliferation and differentiation of endogenous neural progenitor cells were examined using BrdU staining. Neurological function was evaluated with the Morris water maze test. To further examine the effects of sNgR-Fc treatment on neural progenitor cells, photothrombotic cortical injury was produced in another group of rats that received transplantation of neural progenitor cells from the hippocampus of embryonic Sprague-Dawley rats. The animals were then given an infusion of phosphate-buffered saline (neural progenitor cells group) or sNgR-Fc (sNgR-Fc + neural progenitor cells group) into the lateral ventricle for 3 days. sNgR-Fc enhanced the proliferation of cultured neural progenitor cells in vitro as well as that of endogenous neural progenitor cells in vivo, compared with phosphate-buffered saline, and it also induced the differentiation of neural progenitor cells into neurons. Compared with the photothrombotic cortical injury group, escape latency in the Morris water maze and neurological severity score were greatly reduced, and distance traveled in the target quadrant was considerably increased in the sNgR-Fc group, indicating a substantial improvement in neurological function. Furthermore, compared with phosphate-buffered saline infusion, sNgR-Fc infusion strikingly improved the survival and differentiation of grafted neural progenitor cells. Our findings show that sNgR-Fc regulates neural progenitor cell proliferation, migration and differentiation. Therefore, sNgR-Fc is a potential novel therapy for stroke and neurodegenerative diseases, The protocols were approved by the Committee on the Use of Live Animals in Teaching and Research of the University of Hong Kong (approval No. 4560-17) in November, 2015.

The Adiponectin Homolog Osmotin Enhances Neurite Outgrowth and Synaptic Complexity via AdipoR1/NgR1 Signaling in Alzheimer's Disease.

Alzheimer's disease is a major neurodegenerative disease characterized by memory loss and cognitive deficits. Recently, we reported that osmotin, which is a homolog of adiponectin, improved long-term potentiation and cognitive functions in Alzheimer's disease mice. Several lines of evidence have suggested that Nogo-A and the Nogo-66 receptor 1 (NgR1), which form a complex that inhibits long-term potentiation and cognitive function, might be associated with the adiponectin receptor 1 (AdipoR1), which is a receptor for osmotin. Here, we explore whether osmotin's effects on long-term potentiation and memory function are associated with NgR1 signaling via AdipoR1 in Alzheimer's disease. Osmotin reduced the expression of NgR1 without affecting Nogo-A expression. Furthermore, osmotin inhibited NgR1 signaling by prohibiting the formation of the Nogo-A and NgR1 ligand-receptor complex, resulting in enhanced neurite outgrowth; these effects disappeared in the presence of AdipoR1 interference. In addition, osmotin increased the expression of the pre- and postsynaptic markers synaptophysin and PSD-95, as well as the activation of the memory-associated markers AMPA receptor and CREB; these effects occurred in an AdipoR1- and NgR1-dependent manner. Osmotin was also found to enhance dendritic complexity and spine density in the hippocampal region of Alzheimer's disease mouse brains. These results suggest that osmotin can enhance neurite outgrowth and synaptic complexity through AdipoR1 and NgR1 signaling, implying that osmotin might be an effective therapeutic agent for Alzheimer's disease and that AdipoR1 might be a crucial therapeutic target for neurodegenerative diseases such as Alzheimer's.

Asynchronous therapy targeting Nogo-A enhances neurobehavioral recovery by reducing neuronal loss and promoting neurite outgrowth after cerebral ischemia in mice.

Therapeutics targeting the Nogo-A signal pathway hold promise to promote recovery following brain injury. Based on the temporal characteristics of Nogo-A expression in the process of cerebral ischemia and reperfusion, we tested a novel asynchronous treatment, in which TAT-M9 was used in the early stage to decrease neuronal loss, and TAT-NEP1-40 was used in the delayed stage to promote neurite outgrowth after bilateral common carotid artery occlusion (BCCAO) in mice. Both TAT-M9 and TAT-NEP1-40 were efficiently delivered into the brains of mice by intraperitoneal injection. TAT-M9 treatment promoted neuron survival and inhibited neuronal apoptosis. Asynchronous therapy with TAT-M9 and TAT-NEP1-40 increased the expression of Tau, GAP43 and MAP-2 proteins, and enhanced short-term and long-term cognitive functions. In conclusion, the asynchronous treatment had a long-term neuroprotective effect, which reduced neurologic injury and apoptosis, promoted neurite outgrowth and enhanced functional recovery after ischemia. It suggests that this asynchronous treatment could be a promising therapy for cerebral ischemia in humans.

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.

Oncomodulin/truncated protamine-mediated Nogo-66 receptor small interference RNA delivery promotes axon regeneration in retinal ganglion cells.

The optic nerve often suffers regenerative failure after injury, leading to serious visual impairment such as glaucoma. The main inhibitory factors, including Nogo-A, oligodendrocyte myelin glycoprotein, and myelin-associated glycoprotein, exert their inhibitory effects on axonal growth through the same receptor, the Nogo-66 receptor (NgR). Oncomodulin (OM), a calcium-binding protein with a molecular weight of an ∼12 kDa, which is secreted from activated macrophages, has been demonstrated to have high and specific affinity for retinal ganglion cells (RGC) and promote greater axonal regeneration than other known polypeptide growth factors. Protamine has been reported to effectively deliver small interference RNA (siRNA) into cells. Accordingly, a fusion protein of OM and truncated protamine (tp) may be used as a vehicle for the delivery of NgR siRNA into RGC for gene therapy. To test this hypothesis, we constructed OM and tp fusion protein (OM/tp) expression vectors. Using the indirect immunofluorescence labeling method, OM/tp fusion proteins were found to have a high affinity for RGC. The gel shift assay showed that the OM/tp fusion proteins retained the capacity to bind to DNA. Using OM/tp fusion proteins as a delivery tool, the siRNA of NgR was effectively transfected into cells and significantly down-regulated NgR expression levels. More importantly, OM/tp-NgR siRNA dramatically promoted axonal growth of RGC compared with the application of OM/tp recombinant protein or NgR siRNA alone in vitro. In addition, OM/tp-NgR siRNA highly elevated intracellular cyclic adenosine monophosphate (cAMP) levels and inhibited activation of the Ras homolog gene family, member A (RhoA). Taken together, our data demonstrated that the recombinant OM/tp fusion proteins retained the functions of both OM and tp, and that OM/tp-NgR siRNA might potentially be used for the treatment of optic nerve injury.

Altered expression of myelin-associated inhibitors and their receptors after traumatic brain injury in the mouse.

PURPOSE: When central nervous system axons are injured, regeneration is partly inhibited by myelin-associated inhibitors (MAIs). Following traumatic brain injury (TBI) in the rat, pharmacological neutralisation of the MAIs Nogo-A and myelin-associated glycoprotein (MAG) resulted in improved functional outcome. In contrast, genetic or pharmacological neutralization of the MAI receptors Nogo-66 receptor 1 (NgR1) or paired-immunoglobulin like receptor-B (PirB) showed an unaltered or impaired outcome following TBI in mice. The aim of the present study was thus to evaluate the MAI expression levels following TBI in mice. METHODS: Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure total RNA isolated from brains of young adult male C57BL/6 mice at one, three or seven days following controlled cortical impact TBI or sham injury. Hippocampal and neocortical tissue ipsi- and contralateral to the injury was analyzed for Nogo-A, oligodendrocyte-myelin glycoprotein (OMgp), MAG, and the MAI receptors PirB and NgR1, including its co-receptor Lingo1. RESULTS: Compared to sham-injured controls, PirB neocortical expression was significantly upregulated at one day and NgR1 expression downregulated at seven days post-TBI. In the hippocampus, transcriptional upregulation was observed in Nogo-A (one day post-injury), MAG and PirB at seven days post-injury. In contrast, the hippocampal transcripts of NgR1 and Lingo1 were decreased at seven days post-injury. The expression of OMgp was unaltered at all time points post-injury. CONCLUSION: These results suggest that early dynamic changes in MAI gene expression occur following TBI in the mouse, particularly in the hippocampus, which may play an inhibitory role for post-injury regeneration and plasticity.

Bone marrow mesenchymal stem cells with Nogo-66 receptor gene silencing for repair of spinal cord injury.

We hypothesized that RNA interference to silence Nogo-66 receptor gene expression in bone marrow mesenchymal stem cells before transplantation might further improve neurological function in rats with spinal cord transection injury. After 2 weeks, the number of neurons and BrdU-positive cells in the Nogo-66 receptor gene silencing group was higher than in the bone marrow mesenchymal stem cell group, and significantly greater compared with the model group. After 4 weeks, behavioral performance was significantly enhanced in the model group. After 8 weeks, the number of horseradish peroxidase-labeled nerve fibers was higher in the Nogo-66 receptor gene silencing group than in the bone marrow mesenchymal stem cell group, and significantly higher than in the model group. The newly formed nerve fibers and myelinated nerve fibers were detectable in the central transverse plane section in the bone marrow mesenchymal stem cell group and in the Nogo-66 receptor gene silencing group.

Transplantation of Nogo-66 receptor gene-silenced cells in a poly(D,L-lactic-co-glycolic acid) scaffold for the treatment of spinal cord injury.

Inhibition of neurite growth, which is in large part mediated by the Nogo-66 receptor, affects neural regeneration following bone marrow mesenchymal stem cell transplantation. The tissue engineering scaffold poly(D,L-lactide-co-glycolic acid) has good histocompatibility and can promote the growth of regenerating nerve fibers. The present study used small interfering RNA to silence Nogo-66 receptor gene expression in bone marrow mesenchymal stem cells and Schwann cells, which were subsequently transplanted with poly(D,L-lactide-co-glycolic acid) into the spinal cord lesion regions in rats. Simultaneously, rats treated with scaffold only were taken as the control group. Hematoxylin-eosin staining and immunohistochemistry revealed that at 4 weeks after transplantation, rats had good motor function of the hind limb after treatment with Nogo-66 receptor gene-silenced cells plus the poly(D,L-lactide-co-glycolic acid) scaffold compared with rats treated with scaffold only, and the number of bone marrow mesenchymal stem cells and neuron-like cells was also increased. At 8 weeks after transplantation, horseradish peroxidase tracing and transmission electron microscopy showed a large number of unmyelinated and myelinated nerve fibers, as well as intact regenerating axonal myelin sheath following spinal cord hemisection injury. These experimental findings indicate that transplantation of Nogo-66 receptor gene-silenced bone marrow mesenchymal stem cells and Schwann cells plus a poly(D,L-lactide-co-glycolic acid) scaffold can significantly enhance axonal regeneration of spinal cord neurons and improve motor function of the extremities in rats following spinal cord injury.

Multimodal exercises simultaneously stimulating cortical and brainstem pathways after unilateral corticospinal lesion.

In the context of injury to the corticospinal tract (CST), brainstem-origin circuits may provide an alternative system of descending motor influence. However, subcortical circuits are largely under subconscious control. To improve volitional control over spared fibers after CST injury, we hypothesized that a combination of physical exercises simultaneously stimulating cortical and brainstem pathways above the injury would strengthen corticobulbar connections through Hebbian-like mechanisms. We sought to test this hypothesis in mice with unilateral CST lesions. Ten days after pyramidotomy, mice were randomized to four training groups: (1) postural exercises designed to stimulate brainstem pathways (BS); (2) distal limb-grip exercises preferentially stimulating CST pathways (CST); (3) simultaneous multimodal exercises (BS+CST); or (4) no training (NT). Behavioral and anatomical outcomes were assessed after 20 training sessions over 4 weeks. Mice in the BS+CST training group showed a trend toward greater improvements in skilled limb performance than mice in the other groups. There were no consistent differences between training groups in gait kinematics. Anatomically, multimodal BS+CST training neither increased corticobulbar fiber density of the lesioned CST rostral to the lesion nor collateral sprouting of the unlesioned CST caudal to the lesion. Further studies should incorporate electrophysiological assessment to gauge changes in synaptic strength of direct and indirect pathways between the cortex and spinal cord in response to multimodal exercises.

The BAFF/APRIL system: emerging functions beyond B cell biology and autoimmunity.

The BAFF system plays a key role in the development of autoimmunity, especially in systemic lupus erythematosus (SLE). This often leads to the assumption that BAFF is mostly a B cell factor with a specific role in autoimmunity. Focus on BAFF and autoimmunity, driven by pharmaceutical successes with the recent approval of a novel targeted therapy Belimumab, has relegated other potential roles of BAFF to the background. Far from being SLE-specific, the BAFF system has a much broader relevance in infection, cancer and allergy. In this review, we provide the latest views on additional roles of the BAFF system in health and diseases, as well as an update on BAFF and autoimmunity, with particular focus on current clinical trials.

Nogo-66 receptor activation inhibits neurite outgrowth and increases ß-amyloid protein secretion of cortical neurons.

A Nogo-A to Nogo-66 receptor (NgR) pathway is well known to contribute to the inhibition of the neurite regeneration of adult central nervous system neurons after traumatic injuries. Recent evidence suggests that Nogo-A and NgR are involved in the pathology of Alzheimer's disease (AD), as evidenced by the fact that Nogo-A is overexpressed by hippocampal neurons in patients with AD and is associated with ß-amyloid protein (Aß) deposits in senile plaques. In the present experiments, we investigated the potential role of Nogo-A in both neurite outgrowth and Aß generation in cortical neurons. Our results showed that activation of NgR not only inhibited neurite outgrowth in cortical neurons by activating the rho-associated coiled coil-containing protein kinase (ROCK) and protein kinase C, but also promoted their Aß secretion, which was at least in part activated by ROCK. These findings suggest that the overexpression of Nogo-A and the activation of NgR inhibit neurite outgrowth and alter neuronal metabolism, resulting in overproduction and/or release of Aß, which in turn may trigger the onset and development of AD. Inhibition of ROCK can promote neurite outgrowth and reduce Aß production of cortical neuron, which suggests that ROCK appears to be a good target for AD therapy.

The mechanism of the NgR1 antagonist for promoting the neural precursor cells differentiate into neurons / 中华急诊医学杂志

Objective To study the effect of neuronal Nogo-66 receptor (NgR1) antagonist,soluble Nogo-66 receptor (sNgR1-Fc),on promoting the endogenous neural precursor cells (NPCs) differentiating into neurons in order to clarify the mechanism.Methods The cortical infarction was induced by photochemistry,named photothrombotic cortical injury (PCI).Twelve Sprague Dawley rats were randomly divided (random number) into three groups:Sham-operated group,PBS group,and sNgR1-Fc group.PBS (PBS group) or sNgR1-Fc (sNgR1-Fc group) was injected into the lateral ventricle of brain with a minipump.BrdU (Bromodeoxyuridine) was injected into the peritoneal cavity 4-6 days after PCI.The subdentate gyrus zone (SGZ) of brain from sacrificed rat was harvested for Immunohistochemistry to observe the ratio of NeuN +/BrdU + cells 35 days after PCI.Proteins including Nestin、Notch1 and Mash1 were detected by Western Blot.Results The cortical infarction in rat was successfully induced by photochemistry.Thirty-five days after PCI,the BrdU + cells number and theratio of NeuN +/BrdU + in the SGZ of the ipsilateral cerebrum hemisphere with PCI were significantly higher in sNgR1-Fc group than those in PBS group (P ＜ 0.05).The levels of Notch1,Mash1 and Neuro D in the sNgR1-Fc group were significantly higher than those in the PBS group (P ＜ 0.05),which were significantly higher than those in the Sham-operated group.Conclusions sNgR1-Fc could promote the endogenous NPCs differentiating into neurons in a cortical infarction model.The mechanisms may be attributed to the Notch/bHLH (proneural basic helix-loop-helix genes) signaling way.

The mechanism and protective effects of NgR1 antagonist on cortical axons after cortical infarction in rats / 中华急诊医学杂志

Objective To observe the protective effects of soluble Nogo-66 receptor (NgR1 )antagonist (sNgR1-Fc) on cortical axons after cortical infarction in rats,and to study the phenomenon and molecular mechanism of its protective effects on and regeneration of axons.Methods The cortical infarction was induced by photochemistry,termed photothrombotic cortical injury (PCI).Fifteen Sprague Dawley rats were randomly divided into three groups:Sham-operated group,PBS (phosphate buffered solution) group,and s-NgR1-Fc group.In PBS group,PBS was injected into the lateral ventricle of rats; and in sNgR1-Fc group,sNgR1-Fc was injected instead of PBS. The ipsilateral cortex with lesion was harvested for histomorphometry and transmission electron microscope observation 7 days after PCI. Proteins including GTP-RhoA,p-JNK,p-c-JUN and p-ATF-2 were detected by Western blot,as well as Total-J and Total-RhoA.Results The cortical infarction in rats was successfully induced by photochemistry.Compared with sham-operated group,the pathological changes in PBS groups were more serious,including extensive edema or disappearance of axoplasm of fiber without medulla sheath involved and extensive thickening or layer derangement in axoplasm of fiber with medulla sheath involved.These changes were improved significantly after sNgR1-Fc treatment.The levels of GTP-RhoA,p-JNK1,p-JNK2,p-c-JUN and p-ATF-2 in the PBS group were significantly higher than those in the sham-operation group ( P ＜ 0.05 ),whereas the levels of Total-RhoA,Total-JNKl and Total-JNK2 were not different significantly between these two groups (P ＞0.05 ).The sNgR1-Fc treatment up-regulated the levels of these proteins ( P ＜ 0.05 ).Conclusions There is pathological change in axon induced by cerebral hypoxia-ischemia for a long period after cortical infarction.The mechanisms may be associated with RhoA/ROCK/JNK/c-Jun signal way,which is activated by ischemia injury and related to the inhibition of regeneration in axon.Our study shows that NgR1-Fc may inhibit this pathway significantly,and then promote the regeneration of axon partially.

Construction and identification of plasmid mediated RNA interference targeting Nogo-66 receptor / 第三军医大学学报

Objective To construct and identify of a plasmid mediated high efficiency of RNA interference(RNAi) against Nogo-66 receptor(NgR).Methods After cloning of NgR by RT-PCR,the fragments were inserted into pcDNA3.1/CT-GFP-TOPO to produce plasmid expressing NgR-GFP fusion protein.Four pairs of oligonucleotide were designed according to NgR sequence and annealed.The resulting fragments were ligated into short hairpin RNA(shRNA) expressing plasmid.The plasmids expressing NgR-GFP fusion protein and shRNA were co-transfected into AAV-293 cells.RNAi efficiency against NgR was observed under fluorescent microscope and calculated by Western blotting.Results The interference efficiency of one sequence was above 90%.Conclusion A plasmid mediated high RNAi efficiency against NgR is constructed successfully.