Securinine enhances SMN2 exon 7 inclusion in spinal muscular atrophy cells.
Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by the degeneration of motor neurons in the spinal cord, leading to muscular atrophy. SMA is caused by deletions or mutations in the survival motor neuron gene (SMN1) on chromosome 5q13. A second copy of the SMN gene (SMN2) also exists on chromosome 5, and both genes can produce functional protein. However, due to alternative splicing of the exon 7, the majority of SMN protein produced by SMN2 is truncated and unable to compensate for the loss of SMN1. Increasing full-length SMN protein production by promoting the exon 7 inclusion in SMN2 mRNA or increasing SMN2 gene transcription could be a therapeutic approach for SMA. In this study, we screened for the compounds that enhance SMN2 exon 7 inclusion by using SMN2 minigene-luciferase reporter system. We found that securinine can increase luciferase activity, indicating that securinine promoted SMN2 exon 7 inclusion. In addition, securinine increased full-length SMN2 mRNA and SMN protein expression in SMA patient-derived lymphoid cell lines. To investigate the mechanism of securinine effect on SMN2 splicing, we compared the protein levels of relevant splicing factors between securinine-treated and untreated cells. We found that securinine downregulated hnRNP A1 and Sam68 and upregulated Tra2-β1 expression. However, securinine, unlike HDAC inhibitors, did not enhance tra2-β1 gene transcription, indicating a post-transcriptional mechanism for Tra2-β1 upregulation. Furthermore, we treated SMA-like mice with securinine by i.p. injection and found that securinine treatment increased SMN2 exon 7 inclusion and SMN protein expression in the brain and spinal cord. According to our results, securinine might have the potential to become a therapeutic drug for SMA disease.
Graduate Institute of Medicine, College of medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
Yu-Chia
YC
Chen
Epigenome Research Center, China Medical University Hospital, Taichung 40447, Taiwan; Department of Laboratory Medicine, China Medical University Hospital, Taichung 40447, Taiwan; School of Medicine, China Medical University, Taichung 40447, Taiwan.
Jan-Gowth
JG
Chang
Graduate Institute of Medicine, College of medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
Ting-Yuan
TY
Liu
Graduate Institute of Medicine, College of medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; Departments of Pediatrics and Clinical Laboratory, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan.
Yuh-Jyh
YJ
Jong
Center of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital at Taipei, Taipei 10507, Taiwan.
Wei-Lin
WL
Cheng
Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung 80708, Taiwan. Electronic address: m815006@kmu.edu.tw.
Chung-Yee
CY
Yuo
D000818:Animals; D001381:Azepines / Q000494:pharmacology*; D002460:Cell Line; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D005091:Exons / Q000235:genetics*; D006572:Heterocyclic Compounds, Bridged-Ring / Q000494:pharmacology*; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000096:biosynthesis / Q000235:genetics; D007783:Lactones / Q000494:pharmacology*; D008221:Lymphoid Tissue / Q000378:metabolism; D051379:Mice; D009134:Muscular Atrophy, Spinal / Q000235:genetics* / Q000503:physiopathology; D010880:Piperidines / Q000494:pharmacology*; D019154:Protein Splicing; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D000068103:Serine-Arginine Splicing Factors / Q000096:biosynthesis / Q000235:genetics; D055540:Survival of Motor Neuron 2 Protein / Q000235:genetics*
D001381:Azepines; D000697:Central Nervous System Stimulants; D006572:Heterocyclic Compounds, Bridged-Ring; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D007783:Lactones; D010880:Piperidines; D012333:RNA, Messenger; C000597152:SMN2 protein, mouse; D055540:Survival of Motor Neuron 2 Protein; C100345:Tra2b protein, mouse; D000068103:Serine-Arginine Splicing Factors; C000785:securinine
Securinine; Spinal muscular atrophy; Survival motor neuron gene; Tra2-beta1