NOVA1 promotes SMN2 exon 7 splicing by binding the UCAC motif and increases SMN protein expression

作     者：Li-Li Du Jun-Jie Sun Zhi-Heng Chen Yi-Xiang Shao Liu-Cheng Wu Li-Li Du;Jun-Jie Sun;Zhi-Heng Chen;Yi-Xiang Shao;Liu-Cheng Wu

作者机构：Institute of Comparative MedicineNantong UniversityNantongJiangsu ProvinceChina Key Laboratory of Neuroregeneration of Jiangsu and Ministry of EducationCo-Innovation Center of NeuroregenerationNantong UniversityNantongJiangsu ProvinceChina Laboratory Animal CenterNanjing University of Chinese MedicineNanjingJiangsu ProvinceChina Institute of NeuroscienceSoochow UniversitySuzhouJiangsu ProvinceChina 

出 版 物：《Neural Regeneration Research》 (中国神经再生研究（英文版）)

年 卷 期：2022年第17卷第11期

页      面：2530-2536页

核心收录：

学科分类：0710[理学-生物学] 1002[医学-临床医学] 1001[医学-基础医学(可授医学、理学学位)] 100204[医学-神经病学] 10[医学] 

基　　金：the National Natural Science Foundation of China,No.32000841(to JJS) a grant from Science and Technology Project of Nantong of Jiangsu Province,No.JC2018090(to LCW) a grant from Graduate Research and Innovation Project of Jiangsu Province,No.KYCX18-2415(to LLD)。 

主　　题：exon 7 inclusion motor neuron neuro-oncological ventral antigen 1 SMN2 splicing spinal cord spinal muscular atrophy splicing factors UCAC motif 

摘      要：Spinal muscular atrophy(SMA)is a rare hereditary neuromuscular disease with a high lethality rate in infants.Variants in the homologous genes survival of motor neuron(SMN)1 and SMN2 have been reported to be SMA pathogenic factors.Previous studies showed that a highinclusion rate of SMN2 exon 7 increased SMN expression,which in turn reduced the severity of SMA.The inclusion rate of SMN2 exon 7 was higher in neural tissues than in non-neural tissues.Neuro-oncological ventral antigen(NOVA)is a splicing factor that is specifically and highly expressed in neurons.It plays a key role in nervous system development and in the induction of nervous system diseases.Howeve r,it remains unclear whether this splicing factor affects SMA.In this study,we analyzed the inclusion of SMN2 exon 7 in different tissues in a mouse model of SMA(genotype smn^(-/-)SMN2^(2 tg/0))and litter mate controls(genotype smn^(+/-)SMN2^(2 tg/0)).We found that inclusion level of SMN2 exon 7 was high in the brain and spinal co rd tissue,and that NOVA1 was also highly expressed in nervous system tissues.In addition,SMN2 exon 7 and NOVA1 were expressed synchronously in the central nervous system.We further investigated the effects of NOVA1 on disease and found that the number of neurons in the anterior horn of spinal cord decreased in the mouse model of SMA during postnatal days 1-7,and that NOVA1 expression levels in motor neurons decreased simultaneously as spinal muscular atrophy developed.We also found that in vitro expression of NOVA1 increased the inclusion of SMN2 exon 7 and expression ofthe SMN2 protein in the U87 MG cell line,whereas the opposite was observed when NOVA1 was knocked down.Finally,point mutation and RNA pull-down showed that the UCAC motif in SMN2 exon 7 plays a critical role in NOVA1 binding and promoting the inclusion of exon 7.Moreove r,CA was more essential for the inclusion of exon 7 than the order of Y residues in the motif.Collectively,these findings indicate that NOVA1 intera cts with the UCAC motif in exon 7 of SMN2,there by enhancing inclusion of exon 7 in SMN2,which in turn increases expression of the SMN protein.