| Background:Spinal Cord Injury(SCI)is a kind of destructive nerve injury,which is caused by Spinal cord injury due to trauma,disease and other reasons,resulting in the injury stage and severe dysfunction of lower limbs,mostly in the elderly.SCI directly acts on the nerves,causing damage to the nervous system and thus affecting the sensory,motor and autonomic nerve functions of patients.The extent and clinical manifestations of SCI depend on the site and nature of the primary injury.At present,SCI has limited therapeutic effects and cannot effectively restore neurological functions,causing great physiological and psychological pressure on patients.Current studies show that SCI can be prevented and treated by improving nerve injury,but the mechanism of action is still unclear.MicroRNA(miRNA)is a kind of single-stranded non-coding small RNA with a length of about 22-24 nucleotides.MiRNA participates in the regulation of gene expression in eukaryotes through a complex regulatory network,and plays an important regulatory role in cells,mainly affecting the gene expression and cell function in cells.Numerous studies have shown that miRNAs play an important role in the development of a variety of diseases,including spinal cord injury.Neural stem cells(NSCs)are a kind of mother cells which exist in the nervous system and have the potential to divide and self-renew and have the potential to differentiate into neurons,oligodendrocytes and astrokeratinocytes.It exists in brain,spinal cord and other tissues.In this paper,NSCs were used as the cell model to study the pathophysiological functions of spinal neurons.In this study,bioinformatics methods were used to determine that mi R-125 b may play an important role in the recovery of neural function after spinal cord injury in rats,and its downstream molecules were also predicted.Then,in vitro and in vivo experiments were conducted to confirm the mechanism of mi R-125 b in promoting the recovery of neurological function after spinal cord injury in rats.Purposes:(1)To clarify the influence of miRNA-125 b on SCI and neurological function recovery.(2)To determine the effects of miRNA-125 b on proliferation,migration and apoptosis of NSCs.(3)To clarify the mechanism of miRNA-125 b on SCI and neurological function recovery.Methods:(1)In vivo experiment: Adult male Sprague Dawley(SD)rats were used to induce SCI model group,sham operation group and modified Allen method respectively.SCI rats were transfected with negative control(NC)-Agomir oligonucleotide,mi R-125b-agomir oligonucleotide,overexpressed(oe)-NC plasmid,short hairline(SH)-NC plasmid,sh-ATF2,oe-Smurf1 and oe-ATF2 plasmid alone or in combination.Basso-beattie-bresnahan(BBB)scoring was performed on the 3rd,7th,14 th,21st,and 28 th day after surgery.Then the spinal cord tissues were sacrificed and taken for real-time PCR,hematoxylin-eosin(HE)staining,Western Blot detection and Tunel staining.(2)In vitro experiments:NSCs were extracted from SD fetal rats,and the cells were transfected with NSCs by NC-mimics,mi R-125 b mimic,NC-inhibitor,mi R-125 b inhibitor,oe-NC plasmid,oe-Smurf1 plasmid,dimethylsulfoxide(DMSO),MG132(proteasome inhibitor),oe-KLF2 and oe-ATF2 plasmid separately or in combination.Dual-luciferase reporter gene assay and Co-immunoprecipitation(Co-IP)CCK8,etc.were used in vivo.Results:(1)miRNA-125 b inhibits SCI and promotes neurological function recovery.(2 miRNA-125 b targeting Smurf1 promotes the proliferation and migration of NSCs and inhibits cell apoptosis.(3)miRNA-125 b promoted SCI rats’ neurological function recovery by the Smurf1/KLF2/ATF2 axis.Conclusion:The results of this study shown that miRNA-125 b could inhibit SCI and promote neurological function recovery.The mechanism of action is that miRNA-125 b up-regulates KLF2 by targeting Smurf1,thereby inhibiting ATF2 and promoting SCI rat nervous system recovery. |
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