BAF45D Downregulation In Spinal Cord Ependymalcells Following Spinal Cord Injury In Adult Rats And Itspotential Role In The Development Of Neuronal Lesions

Backgroud:The endogenous spinal cord ependymal cells(SCECs),which form the central canal(CC),are critically involved in proliferation,differentiation and migration after spinal cord injury(SCI)and represents a repair cell source in treating SCI.Previously,we reported that BAF45 D is expressed in the SCECs and the spinal cord neurons in adult mice and knockdown of BAF45 D fail to induce expression of PAX6,a neurogenic fate determinant,during early neural differentiation of human embryonic stem cells.However,the effects of SCI on expression of BAF45 D have not been reported.Objective:The aim of this study is to explore the expression and potential role of BAF45 D in rat SCI model.Main research aspects:1)We first explored expression of BAF45 D in the SCECs in intact adult rats;2)We then explored SCI-induced loss of motor neurons and lesion of neurites in the anterior horns induced by the SCI;3)We also investigated whether the SCI-induced lesions in SCECs are accompanied by the motor neuron lesions;4)Finally,we examined the effect of BAF45 D knockdown on cell growth in neuro2 a cells.Methods: 1)Adult SD rats(8 weeks old,weight 220-250g)were randomly divided into the normal sham operation group and the SCI group,Spinal cord sections were prepared and the expression of BAF45 D,BETA-III-tubulin,NEUN,MBP,NESTIN,GFAP protein in the spinal cord was detected by immunohistochemistry(IHC)or immunohistochemistry(IF);2)Protein suspensions from adult SD rat spinal cord was prepared and the expressions of BAF45D?BETA-III-tubulin?NEUN?GFAP?GAPDH were detected by western blotting(IB);3)Neuro2a cells were transfected with BAF45 D small interference RNA(si RNA),and the effect of BAF45 D on the growth of Neuro2 a cells was observed by IB technique and cell count.Results:1)BAF45D was Expressed in the SCECs and Neurons in Intact Adult Rat Spinal Cords;2)Spinal Cord Oligodendrocytes Expressed BAF45 D While Astrocytes Expressed Little or No BAF45D;3)The expression of BAF45 D,beta-III-tubulin and NEUN in adult rat spinal cord lesions decreased and the expression of GFAP increased;4)At the site of myelopathy,the central tube proliferated and migrated to produce many non-neuronal cells;5)BAF45D was weakly expressed in non-neuron cells in the damaged area;6)BAF45D was Downregulated in SCECs After SCI in Adult Rats;7)SCI Exerted Deleterious Effects on SCECs and the Structure of the CC,Induced Neurite Lesions,and Led to a Loss of Motor Neurons;8)Knockdown of BAF45 D Inhibited Cell Growth in Neuro2 a Cells.Conclusion:1)BAF45D is expressed in SCEC and neuron cells of spinal cord of intact rats.2)The expression of BAF45 D,beta-III-tubulin and NEUN in adult rat spinal cord lesions decreased and the expression of GFAP increased;3)BAF45D was decreased in SCI-injured SCECs and BAF45 D downregulation may play a potential role in development of neuronal lesion after SCI in adult rats.