Silencing the enhancer of zeste homologue 2,Ezh2,represses axon regeneration of dorsal root ganglion neurons

Recovery from injury to the peripheral nervous system is different from that of the central nervous system in that it can lead to gene reprogramming that can induce the expression of a series of regeneration-associated genes.This eventually leads to axonal regeneration of injured neurons.Although some regeneration-related genes have been identified,the regulatory network underlying axon regeneration remains largely unknown.To explore the regulator of axon regeneration,we performed RNA sequencing of lumbar L4 and L5 dorsal root ganglion(DRG)neurons at different time points(0,3,6,12 hours,1,3 and 7 days)after rat sciatic nerve crush.The isolation of neurons was carried out by laser capture microscopy combined with NeuN immunofluorescence staining.We found 1228 differentially expressed genes in the injured sciatic nerve tissue.The hub genes within these differentially expressed genes include Atf3,Jun,Myc,Ngf,Fgf2,Ezh2,Gfap and Il6.We verified that the expression of the enhancer of zeste homologue 2 gene(Ezh2)was up-regulated in DRG neurons after injury,and this up-regulation differed between large-and small-sized dorsal root ganglion neurons.To investigate whether the up-regulation of Ezh2 impacts axonal regeneration,we silenced Ezh2 with siRNA in cultured DRG neurons and found that the growth of the newborn axons was repressed.In our investigation into the regulatory network of Ezh2 by interpretive phenomenal analysis,we found some regulators of Ezh2(including Erk,Il6 and Hif1a)and targets(including Atf3,Cdkn1a and Smad1).Our findings suggest that Ezh2,as a nerve regeneration-related gene,participates in the repair of the injured DRG neurons,and knocking down the Ezh2 in vitro inhibits the axonal growth of DRG neurons.All the experimental procedures approved by the Administration Committee of Experimental Animals of Jiangsu Province of China(approval No.S20191201-201)on March 21,2019.

Physiological relevance of soma secretion in dorsal root ganglion neurons

Dorsal root ganglion (DRG) cells are primary sensory neurons and are important in pain. Recently, a distinct type of exocytosis, Ca2+ independent but voltage-dependent, is found

Effects of Hirudin on High Glucose-Induced Oxidative Stress and Inflammatory Pathway in Rat Dorsal Root Ganglion Neurons

Objective:To investigate protective effects of hirudin on oxidative stress and apoptosis of spinal dorsal root ganglion cells in high-glucose rats at the cellular and molecular level.Methods:Dorsal root ganglion neurons(DRGn)were harvested from embryonic day in 15 SD rats,purified and identificated after primary culture.They were divided into the normal control group,high-glucose(HG)group,positive control(alpha-lipoic acid,ALA)group,low-dose hirudin group(H1),medium-dose hirudin group(H2)and high-dose hirudin group(H3).The control group was cultured by neuron specific culture medium,while the HG group was cultured by neuron specific culture medium and 20 mmol/L glucose(HG medium).The hirudin groups were cultured by HG medium+0.25 IU/mL hirudin(H1),HG medium+0.5 IU/mL hirudin(H2)and HG medium+1 IU/mL hirudin(H3).The ALA group was cultured by HG medium +100μmol/L ALA.3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylt etrazolium bromide(MTT)assay was used to explore the optimum concentration and intervention time.Flow cytometry assay was used to detect the level of reactive oxygen series(ROS).Western blot and quantificational realtime polymerase chain reaction(qRT-PCR)were used to detect the expression of protein and mRNA of nuclear factor erythroid 2-related factor 2(Nrf-2),hemeoxygence-1(HO-1),nuclear factor-κB(NF-κB)and Caspase-3.TUNEL assay was used to test the apoptosis rate of different groups.Results:After 24 h of culture,the cell activity of hirudin and ALA groups were higher than that of HG group,and there was a statistical difference between the H1 group and HG group(P<0.05).In hirudin groups,the apoptosis rate of cells,the expression of activated Caspase-3 protein and Caspase-3 mRNA were lower than those of HG group(P<0.01),higher than those of ALA group(P<0.01 or P<0.05).The ROS level of hirudin groups was higher than that of ALA group(P<0.01),lower than that of HG group(P<0.01 or P<0.05).The expression of NF-κB(P65)protein in H3 group were lower than those of HG group(P<0.05).The expression of Nrf-2 protein in hirudin groups was higher than that of HG group(P<0.01),lower than that of ALA group(P<0.01 or P<0.05).The expression of HO-1 protein in hirudin groups was lower than that of ALA group(P<0.01 or P<0.05),higher than that of HG group(P<0.01 or P<0.05).Conclusions:The activity of DRGn cells can be promoted by hirudin under HG conditions.The effects of hirudin on the inhibition of HG on DRGn cells damage mainly include scavenging ROS,up-regulating Nrf-2/HO-1 pathway,inhibiting activation of NF-κB pathway,down-regulating the expression of and Caspase-3 and reducing DRGn cell apoptosis.

Potentiation of PIEZO2 mechanically-activated currents in sensory neurons mediates vincristine-induced mechanical hypersensitivity

Vincristine,a widely used chemotherapeutic agent for treating different cancer,often induces severe peripheral neuropathic pain.A common symptom of vincristine-induced peripheral neuropathic pain is mechanical allodynia and hyperalgesia.However,mechanisms underlying vincristine-induced mechanical allodynia and hyperalgesia are not well understood.In the present study,we show with behavioral assessment in rats that vincristine induces mechanical allodynia and hyperalgesia in a PIEZO2 channel-dependent manner since gene knockdown or pharmacological inhibition of PIEZO2 channels alleviates vincristine-induced mechanical hypersensitivity.Electrophysiological results show that vincristine potentiates PIEZO2 rapidly adapting(RA)mechanically-activated(MA)currents in rat dorsal root ganglion(DRG)neurons.We have found that vincristine-induced potentiation of PIEZO2 MA currents is due to the enhancement of static plasma membrane tension(SPMT)of these cells following vincristine treatment.Reducing SPMT of DRG neurons by cytochalasin D(CD),a disruptor of the actin filament,abolishes vincristine-induced potentiation of PIEZO2 MA currents,and suppresses vincristine-induced mechanical hypersensitivity in rats.Collectively,enhancing SPMT and subsequently potentiating PIEZO2 MA currents in primary afferent neurons may be an underlying mechanism responsible for vincristineinduced mechanical allodynia and hyperalgesia in rats.Targeting to inhibit PIEZO2 channels may be an effective analgesic method to attenuate vincristine-induced mechanical hypersensitivity.