Chx10+V2a interneurons in spinal motor regulation and spinal cord injury

Chx10-expressing V2 a(Chx10+V2 a) spinal interneurons play a large role in the excitatory drive of motoneurons. Chemogenetic ablation studies have demonstrated the essential nature of Chx10+V2 a interneurons in the regulation of locomotor initiation, maintenance, alternation, speed, and rhythmicity. The role of Chx10+V2 a interneurons in locomotion and autonomic nervous system regulation is thought to be robust, but their precise role in spinal motor regulation and spinal cord injury have not been fully explored. The present paper reviews the origin, characteristics, and functional roles of Chx10+V2 a interneurons with an emphasis on their involvement in the pathogenesis of spinal cord injury. The diverse functional properties of these cells have only been substantiated by and are due in large part to their integration in a variety of diverse spinal circuits. Chx10+V2 a interneurons play an integral role in conferring locomotion, which integrates various corticospinal, mechanosensory, and interneuron pathways. Moreover, accumulating evidence suggests that Chx10+V2 a interneurons also play an important role in rhythmic patterning maintenance, leftright alternation of central pattern generation, and locomotor pattern generation in higher order mammals, likely conferring complex locomotion. Consequently, the latest research has focused on postinjury transplantation and noninvasive stimulation of Chx10+V2 a interneurons as a therapeutic strategy, particularly in spinal cord injury. Finally, we review the latest preclinical study advances in laboratory derivation and stimulation/transplantation of these cells as a strategy for the treatment of spinal cord injury. The evidence supports that the Chx10+V2 a interneurons act as a new therapeutic target for spinal cord injury. Future optimization strategies should focus on the viability, maturity, and functional integration of Chx10+V2 a interneurons transplanted in spinal cord injury foci.

Can Hybrid Synapse be Formed between Rat Spinal Motor Neurons and Major Pelvic Ganglion Neurons in vitro?

The purpose of this study is to determine whether synapses can be formed between spinal motor neurons(SMNs)and major pelvic ganglion(MPG)neurons of a rat in vitro.The green fluorescent protein(GFP)-labelled MPG cells were cultured together with SMNs in a specific medium.The synaptic-like contacts established between SMNs and MPG neurons were studied in co-cultures using morphologic and immunocytochemistry approaches.Phase-contrast observation of co-cultures showed apparent SMNs-MPG neurons contacts as early as three or four days in vitro.We demonstrate some evidence of synaptic contacts between SMNs and MPG neurons in vitro by immunostaining with antibody directed against postsynaptic density protein 95(PSD-95).We describe the development process of a defined SMNs-MPG neurons co-culture system.The results suggest that the hybrid synapse formation that may occur between SMNs and MPG neurons in vitro played an essential role in the mechanisms of a regenerated bladder with an artificial somatic-autonomic reflex arc.

Motor neuron-specific RhoA knockout delays degeneration and promotes regeneration of dendrites in spinal ventral horn after brachial plexus injury

Dendrites play irreplaceable roles in the nerve conduction pathway and are vulnerable to various insults.Peripheral axotomy of motor neurons results in the retraction of dendritic arbors,and the dendritic arbor can be re-expanded when reinnervation is allowed.RhoA is a target that regulates the cytoskeleton and promotes neuronal survival and axon regeneration.However,the role of RhoA in dendrite degeneration and regeneration is unknown.In this study,we explored the potential role of RhoA in dendrites.A line of motor neuronal conditional knockout mice was developed by crossbreeding HB9~(Cre+)mice with RhoA~(flox/flox)mice.We established two models for assaying dendrite degeneration and regeneration,in which the brachial plexus was transection or crush injured,respectively.We found that at 28 days after brachial plexus transection,the density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice were slightly decreased compared with that in Cre mice.Dendrites underwent degeneration at 7 and 14 days after brachial plexus transection and recovered at 28–56 days.The density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice recovered compared with results in Cre mice.These findings suggest that RhoA knockout in motor neurons attenuates dendrite degeneration and promotes dendrite regeneration after peripheral nerve injury.

Effects of targeted muscle reinnervation on spinal cord motor neurons in rats following tibial nerve transection

Targeted muscle reinnervation(TMR)is a surgical procedure used to transfer residual peripheral nerves from amputated limbs to targeted muscles,which allows the target muscles to become sources of motor control information for function reconstruction.However,the effect of TMR on injured motor neurons is still unclear.In this study,we aimed to explore the effect of hind limb TMR surgery on injured motor neurons in the spinal cord of rats after tibial nerve transection.We found that the reduction in hind limb motor function and atrophy in mice caused by tibial nerve transection improved after TMR.TMR enhanced nerve regeneration by increasing the number of axons and myelin sheath thickness in the tibial nerve,increasing the number of anterior horn motor neurons,and increasing the number of choline acetyltransferase-positive cells and immunofluorescence intensity of synaptophysin in rat spinal cord.Our findings suggest that TMR may enable the reconnection of residual nerve fibers to target muscles,thus restoring hind limb motor function on the injured side.

Eph receptor A4 regulates motor neuron ferroptosis in spinal cord ischemia/reperfusion injury in rats

Previous studies have shown that the receptor tyrosine kinase Eph receptor A4(EphA4) is abundantly expressed in the nervous system. The EphA4 signaling pathway plays an important role in regulating motor neuron ferroptosis in motor neuron disease. To investigate whether EphA4 signaling is involved in ferroptosis in spinal cord ischemia/reperfusion injury, in this study we established a rat model of spinal cord ischemia/reperfusion injury by clamping the left carotid artery and the left subclavian artery. We found that spinal cord ischemia/reperfusion injury increased EphA4 expression in the neurons of anterior horn, markedly worsened ferroptosis-related indicators, substantially increased the number of mitochondria exhibiting features consistent with ferroptosis, promoted deterioration of motor nerve function, increased the permeability of the blood-spinal cord barrier, and increased the rate of motor neuron death. Inhibition of EphA4 largely rescued these effects. However, intrathecal administration of the ferroptosis inducer Erastin counteracted the beneficial effects conferred by treatment with the EphA4 inhibitor. Mass spectrometry and a PubMed search were performed to identify proteins that interact with EphA4, with the most notable being Beclin1 and Erk1/2. Our results showed that inhibition of EphA4 expression reduced binding to Beclin1, markedly reduced p-Beclin1, and reduced Beclin1-XCT complex formation. Inhibition of EphA4 also reduced binding to p-Erk1/2 and markedly decreased the expression of c-Myc, transferrin receptor 1, and p-Erk1/2. Additionally, we observed co-localization of EphA4 and p-Beclin1 and of EphA4 and p-ERK1/2 in neurons in the anterior horn. In conclusion, EphA4 participates in regulating ferroptosis of spinal motor neurons in the anterior horn in spinal cord ischemia/reperfusion injury by promoting formation of the Beclin1-XCT complex and activating the Erk1/2/c-Myc/transferrin receptor 1 axis.

Culture of Motor Neurons from Newborn Rat Spinal Cord

A protocol for the isolation, purification and culture of motor neurons from newborn rat spinal cord was described and the effect of glial cell line-derived neurotrophic factor （GDNF） on the growth of neurite of motor neurons was investigated in vitro. Spinal motor neurons （SMNs） were dissociated from ventral spinal cord of postnatal day 1 rats. The culture system for SMNs was established by density gradient centrifugation, differential adhesion, and use of serum-free defined media and addition of exogenous GDNF. After 72-h culture, the cells displayed the characteristic morphology of motor neurons, exhibited extensive neuritic processes and were positive for choline acetyl- transferase （CHAT） expression. The neurite length of SMNs in GDNF groups was significantly longer than that in control group （P〈0.05）. This protocol can be adapted for various postnatal motor neurons studies.

Preconditioning crush increases the survival rate of motor neurons after spinal root avulsion

In a previous study, heat shock protein 27 was persistently upregulated in ventral motor neurons following nerve root avulsion or crush. Here, we examined whether the upregulation of heat shock protein 27 would increase the survival rate of motor neurons. Rats were divided into two groups： an avulsion-only group （avtflsion of the L4 lumbar nerve root only） and a crush-avulsion group （the L4 lumbar nerve root was crushed 1 week prior to the avulsion）. Immunofluores- cent staining revealed that the survival rate of motor neurons was significantly greater in the crush-avulsion group than in the avulsion-only group, and this difference remained for at least 5 weeks after avulsion. The higher neuronal survival rate may be explained by the upregulation of heat shock protein 27 expression in motor neurons in the crush-avulsion group. Further- more, preconditioning crush greatly attenuated the expression of nitric oxide synthase in the motor neurons. Our findings indicate that the neuroprotective action of preconditioning crush is mediated through the upregulation of heat shock protein 27 expression and the attenuation of neuronal nitric oxide synthase upregulation following avulsion.

Protective effect of sodium valproate on motor neurons in the spinal cord following sciatic nerve injury in rats

BACKGROUND: Sodium valproate (VPA) is used to be an effective anti-epileptic drug. VPA possesses the characteristics of penetrating rapidly through the blood-brain barrier (BBB) and increasing levels of Bcl-2 and growth cone-associated protein (GAP) 43 in spinal cord. OBJECTIVE: To observe the effect of VPA on Bcl-2 expression and motor neuronal apoptosis in spinal cord of rats following sciatic nerve transection. DESIGN: Randomized controlled experiment. SETTING: Department of Hand Surgery and Microsurgery, Wuhan Puai Hospital. MATERIALS: A total of 30 male healthy SD rats of clean grade and with the body mass of 180-220 g were provided by Experimental Animal Center of Medical College of Wuhan University. Sodium Valproate Tablets were purchases from Hengrui Pharmaceutical Factory, Jiangsu. METHODS: The experiment was performed in the Central Laboratory of Wuhan Puai Hospital and Medical College of Wuhan University from February to May 2006. Totally 30 rats were randomly divided into two groups: treatment group (n =15) and model group (n =15). Longitudinal incision along backside of right hind limbs of rats was made to expose sciatic nerves, which were sharply transected 1 cm distal to the inferior margin of piriform muscle after nerve liberation under operation microscope to establish sciatic nerve injury rat models. Sodium Valproate Tablets were pulverized and diluted into 50 g/L suspension with saline. On the day of operation, the rats in the treatment group received 6 mL/kg VPA suspension by gastric perfusion, once a day, whereas model group received 10 mL/kg saline by gastric perfusion, once a day. L4-6 spinal cords were obtained at days 1, 4, 7, 14 and 28 after operation, respectively. Terminal deoxyribonucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) technique and immunohistochemical method (SP method) were used to detect absorbance (A) of neurons with positive Bcl-2 expression. Apoptotic rate of cells (number of apoptotic cells/total number of cells×100%) was calculated. MAIN OUTCOME MEASURES: A value of neurons with positive Bcl-2 expression and apoptotic rate in spinal cord of rats in the two groups. RESULTS: A total of 30 SD rats were involved in the result analysis. ①expression of positive Bcl-2 neurons: A value of positive Bcl-2 neurons were 0.71±0.02, 0.86±0.04, 1.02±0.06 at days 4, 7 and 14, respectively after operation in the treatment group, which were obviously higher than those in the model group (0.62±0.03, 0.71±0.05, 0.89±0.04, t = 3.10-4.50, P < 0.05). ②apoptotic result of motor neurons: Apoptotic rate of motor neurons in spinal cord was (6.91±0.89)% and (15.12±2.34)% at days 7 and 14 in the treatment group, which was significantly lower than those in the model group [(9.45±1.61)%, (19.35±0.92)%, t = 2.39, 3.03. P < 0.05]. CONCLUSION: VPA can increase expression of Bcl-2 in spinal cord and reduce neuronal apoptosis in rats following sciatic nerve injury, and has protective effect on motor neuron in spinal cord of rats.

Electroacupuncture promotes the recovery of motor neuron function in the anterior horn of the injured spinal cord

Acupuncture has been shown to lessen the inflammatory reaction after acute spinal cord injury and reduce secondary injury.However,the mechanism of action remains unclear.In this study,a rat model of spinal cord injury was established by compressing the T8-9 segments using a modified Nystrom method.Twenty-four hours after injury,Zusanli（ST36）,Xuanzhong（GB39）,Futu（ST32）and Sanyinjiao（SP6）were stimulated with electroacupuncture.Rats with spinal cord injury alone were used as controls.At 2,4 and 6 weeks after injury,acetylcholinesterase（ACh E）activity at the site of injury,the number of medium and large neurons in the spinal cord anterior horn,glial cell line-derived neurotrophic factor（GDNF）m RNA expression,and Basso,Beattie and Bresnahan locomotor rating scale scores were greater in the electroacupuncture group compared with the control group.These results demonstrate that electroacupuncture increases ACh E activity,up-regulates GDNF m RNA expression,and promotes the recovery of motor neuron function in the anterior horn after spinal cord injury.

Effects of cortical intermittent theta burst stimulation combined with precise root stimulation on motor function after spinal cord injury: a case series study

Activation and reconstruction of the spinal cord circuitry is important for improving motor function following spinal cord injury.We conducted a case series study to investigate motor function improvement in 14 patients with chronic spinal cord injury treated with 4 weeks of unilateral(right only)cortical intermittent theta burst stimulation combined with bilateral magnetic stimulation of L3-L4 nerve roots,five times a week.Bilateral resting motor evoked potential amplitude was increased,central motor conduction time on the side receiving cortical stimulation was significantly decreased,and lower extremity motor score,Berg balance score,spinal cord independence measure-III score,and 10 m-walking speed were all increased after treatment.Right resting motor evoked potential amplitude was positively correlated with lower extremity motor score after 4 weeks of treatment.These findings suggest that cortical intermittent theta burst stimulation combined with precise root stimulation can improve nerve conduction of the corticospinal tract and lower limb motor function recovery in patients with chronic spinal cord injury.

Expression of NF-κB in Schwann cells and its effect on motor neuron apoptosis in spinal cord following sciatic nerves injury in rats

Objective: To explore the expression of nuclear factor-kappa B (NF-κB) in Schwann cells (SCs) and its effect on motor neuron apoptosis in spinal cord following sciatic nerves injury in adult rats. Methods: Thirty-six adult Sprague-Dawley (SD) rats were divided randomly into normal control group (n=6), and sciatic nerves crushing group (n=30). and the later was further equally randomized into 5 subgroups: 1. 3. 7. 11. and 21 d post-injury groups. The expression of NF-κB of normal and injured nerves were examined by immunohistochemistry staining, and the apoptosis of motor neurons in spinal cord of lumbar 4 to lumbar 6 (L4-L6) was investigated by terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNED assay. Both were quantitated by image analysis. Results: In crushing group, except 21 d post-injury group, the expression of NF-κB was markedly higher than that in the normal control group (P<0. 05,P<0. 01). At 1 d after sciatic nerves crushing, the expression of NF-κB was obviously up-regulated, reached peak at 3 d. and recovered at 21 d. The same trend was observed in the time-course on motor neuron apoptosis after sciatic nerves injury. Correlation analyses revealed that motor neuron apoptosis was significantly and positively correlated with the expression of NF-κB following sciatic nerves injury (r=0. 976 0,P<0. 01). Conclusion: After injury of sciatic nerves, the presence and up-regulation of NF-κB in SCs may be involved in motor neuron apoptosis in L4-L6 spinal cord.

Serum response factor promotes axon regeneration following spinal cord transection injury

Studies have snown that serum response factor is beneficaial for axonar regeneration of peripheral herves.However,Its role after central nervous system injury remains unclear. In this study,we established a rat model of T9-T10 spinal cord transection injury.We found that the expression of serum response factor in injured spinal cord gray matter neurons gradually increased with time,reached its peak on the 7^(th) day,and then gradually decreased.To investigate the role of serum response factor,we used lentivirus vecto rs to ove rexpress and silence serum response factor in spinal cord tissue.We found that overexpression of serum response factor promoted motor function recovery in rats with spinal cord injury.Qualitative observation of biotinylated dextran amine anterograde tra cing showed that ove rexpression of serum response factor increased nerve fibers in the injured spinal co rd.Additionally,transmission electron microscopy showed that axon and myelin sheath morphology was restored.Silencing serum response factor had the opposite effects of ove rexpression.These findings suggest that serum response factor plays a role in the recovery of motor function after spinal cord injury.The underlying mechanism may be related to the regulation of axonal regeneration.

体感模拟训练系统联合高频重复经颅磁刺激对脑卒中后上肢偏瘫患者上肢肌张力及脊髓运动神经元兴奋性的影响

目的分析体感模拟训练系统联合高频重复经颅磁刺激对脑卒中后上肢偏瘫患者上肢肌张力及脊髓运动神经元兴奋性的影响。方法选择2019年3月至2022年4月我院收治的100例脑卒中后上肢偏瘫患者作为研究对象,以随机数字表法将其分为对照组、观察组,每组50例。对照组接受常规康复治疗,观察组在对照组基础上加施体感模拟训练系统联合高频重复经颅磁刺激。比较两组的干预效果。结果干预后,观察组的改良Ashworth评分量表(MAS)、临床痉挛指数(CSI)低于对照组,Fugl-Meyer运动功能评分量表上肢部分(U-FMA)评分高于对照组(P<0.05)。干预后,观察组的H波最大波幅(Hmax)、M波最大波幅(Mmax)及Hmax/Mmax低于对照组(P<0.05)。干预后,观察组的脑源性神经营养因子(BDNF)、神经生长因子(NGF)水平高于对照组(P<0.05)。结论体感模拟训练系统联合高频重复经颅磁刺激用于脑卒中后上肢偏瘫患者康复治疗中,可改善神经功能及脊髓运动神经元兴奋性,促进上肢肌张力及上肢功能恢复,值得临床推广。

Transplantation of neurotrophin-3-transfected bone marrow mesenchymal stem cells for the repair of spinal cord injury

Bone marrow mesenchymal stem cell transplantation has been shown to be therapeutic in the repair of spinal cord injury. However, the low survival rate of transplanted bone marrow mesen- chymal stem cells in vivo remains a problem. Neurotrophin-3 promotes motor neuron survival and it is hypothesized that its transfection can enhance the therapeutic effect. We show that in vitro transfection of neurotrophin-3 gene increases the number of bone marrow mesenchymal stem cells in the region of spinal cord injury. These results indicate that neurotrophin-3 can promote the survival of bone marrow mesenchymal stem cells transplanted into the region of spinal cord injury and potentially enhance the therapeutic effect in the repair of spinal cord injury.

A progressive compression model of thoracic spinal cord injury in mice： function assessment and pathological changes in spinal cord

Non-traumatic injury accounts for approximately half of clinical spinal cord injury, including chronic spinal cord compression. However, previous rodent spinal cord compression models are mainly designed for rats, few are available for mice. Our aim is to develop a thoracic progressive compression mice model of spinal cord injury. In this study, adult wild-type C57BL/6 mice were divided into two groups： in the surgery group, a screw was inserted at T9 lamina to compress the spinal cord, and the compression was increased by turning it further into the canal（0.2 mm） post-surgery every 2 weeks up to 8 weeks. In the control group, a hole was drilled into the lamina without inserting a screw. The results showed that Basso Mouse Scale scores were lower and gait worsened. In addition, the degree of hindlimb dysfunction in mice was consistent with the degree of spinal cord compression. The number of motor neurons in the anterior horn of the spinal cord was reduced in all groups of mice, whereas astrocytes and microglia were gradually activated and proliferated. In conclusion, this progressive compression of thoracic spinal cord injury in mice is a preferable model for chronic progressive spinal cord compression injury.

Emerging concepts underlying selective neuromuscular dysfunction in infantile-onset spinal muscular atrophy

Infantile-onset spinal muscular atrophy is the quintessential example of a disorder characterized by a predominantly neurodegenerative phenotype that nevertheless stems from perturbations in a housekeeping protein.Resulting from low levels of the Survival of Motor Neuron(SMN)protein,spinal muscular atrophy manifests mainly as a lower motor neuron disease.Why this is so and whether other cell types contribute to the classic spinal muscular atrophy phenotype continue to be the subject of intense investigation and are only now gaining appreciation.Yet,what is emerging is sometimes as puzzling as it is instructive,arguing for a careful re-examination of recent study outcomes,raising questions about established dogma in the field and making the case for a greater focus on milder spinal muscular atrophy models as tools to identify key mechanisms driving selective neuromuscular dysfunction in the disease.This review examines the evidence for novel molecular and cellular mechanisms that have recently been implicated in spinal muscular atrophy,highlights breakthroughs,points out caveats and poses questions that ought to serve as the basis of new investigations to better understand and treat this and other more common neurodegenerative disorders.

Effect of Luteolin on Biochemical,Immunohistochemical,and Morphometrical Changes in Rat Spinal Cord following Exposure to a 900 MHz Electromagnetic Field

Objective This study aimed to investigate the effect of exposure to a 900 MHz electromagnetic field(EMF)on the cervical spinal cord(CSC)of rats and the possible protective effect of luteolin(LUT)against CSC tissue damage.Methods Quantitative data were obtained via stereological,biochemical,immunohistochemical,and histopathological techniques.We investigated morphometric value,superoxide dismutase(SOD)level,and the expression of high-mobility group box 1 protein molecules,as well as histological changes.Results The total number of motor neurons in the EMF group significantly decreased in comparison with that in the control group(P<0.05).In the EMF+LUT group,we found a significant increase in the total number of motor neurons compared with that in the EMF group(P<0.05).SOD enzyme activity in the EMF group significantly increased in comparison with that in the control group(P<0.05).By contrast,the EMF+LUT group exhibited a decrease in SOD level compared with the EMF group(P<0.05).Conclusion Our results suggested that exposure to EMF could be deleterious to CSC tissues.Furthermore,the protective efficacy of LUT against SC damage might have resulted from the alleviation of oxidative stress caused by EMF.

Nusinersen,an exon 7 inclusion drug for spinal muscular atrophy:A minireview

Spinal muscular atrophy is an autosomal recessive neuromuscular disease with incidence of 1 in 5000 to 10000 live births and is produced by homozygous deletion of exons 7 and 8 in the SMN1 gene.The SMN1 and SMN2 genes encode the survival motor neuron protein,a crucial protein for the preservation of motor neurons.Use of the newer drug,Nusinersen,from early infancy has shown improvement in clinical outcomes of spinal muscular atrophy patients.

胸_(1)脊神经根切断治疗手痉挛性瘫痪的临床效果观察

目的探讨胸_(1)脊神经根切断治疗手痉挛性瘫痪的临床效果。方法回顾性分析2006年10月至2021年7月在北京积水潭医院接受胸_(1)脊神经根切断术治疗的7例手痉挛性瘫痪患者的临床资料。其中男4例,女3例;脑外伤5例,脑瘫2例;从脑外伤或脑瘫发病到手术的时间为1~18年,平均(6.7±5.9)年。所有患者均为单侧肢体受累,屈指肌肌张力3级6例、2级1例,屈指肌肌力4级4例、3级3例。观察术后患者屈指肌肌张力和肌力的恢复情况,以及手功能改良House上肢功能分级(House Functional Classification,HFC)的变化。结果所有患者手术顺利,术后随访6~36个月,平均(15.4±10.3)个月。7例患者末次随访时屈指肌肌张力均较术前降低2个等级且肌力无减弱,疗效评定均为优。术后早期屈指肌肌力均有明显降低,至末次随访时均恢复到术前水平。3例患者末次随访时手功能改良HFC分级由术前的2级增至5级或以上,恢复了手的主动抓握及日常使用功能。7例患者最终的手功能改良HFC分级由术前的(1.6±0.8)级提高到末次随访时的(4.0±1.7)级。术后第1天7例患者均有小指及前臂内侧感觉麻木,至末次随访时均恢复正常。结论胸_(1)脊神经根切断术治疗手屈指痉挛性瘫痪效果满意,值得临床应用。

脊髓性肌萎缩症中运动神经元生存蛋白缺失抑制p53泛素化降解致其积累的研究

目的探究脊髓性肌萎缩症(spinal muscular atrophy,SMA)中p53积累的分子机制。方法构建运动神经元生存基因(Survival motor neuron,Smn)敲低的稳转小鼠运动神经元细胞系NSC34,采用蛋白质印迹和荧光定量PCR检测蛋白和基因的变化;用蛋白合成抑制剂放线菌酮(Cycloheximide,CHX)抑制蛋白合成,蛋白质印迹检测p53蛋白降解情况,采用免疫共沉淀检测p53与MDM2结合情况;采用免疫荧光检测小鼠脊髓组织运动神经元数量,运用流式细胞仪分析细胞周期的分布。结果在Smn敲低的NSC34细胞中,p53蛋白水平显著增加,但是其基因水平未发生明显变化;当蛋白合成被抑制后,SMN缺失会抑制p53蛋白降解,p53积累后会调控下游MDM2表达显著增加,但是其与p53结合却显著减少;p⁃p53(Ser18)和acetyl⁃p53(K382)水平显著升高,K382乙酰化位点会影响p53泛素化结合,导致其泛素化被抑制;最终p53积累导致NSC34细胞和SMA小鼠脊髓组织中细胞周期阻滞和凋亡增加。结论SMN蛋白缺失通过抑制p53泛素化降解途径导致其积累,进而引起细胞周期阻滞和凋亡。