Modeling the early phenotype at the neuromuscular junction of spinal muscular atrophy using patient-derived iPSCs.
Bottom Line: We generated NMJ-like structures using MNs derived from SMA patient-specific induced pluripotent stem cells (iPSCs), and found that the clustering of the acetylcholine receptor (AChR) is significantly impaired.Valproic acid and antisense oligonucleotide treatment ameliorated the AChR clustering defects, leading to an increase in the level of full-length SMN transcripts.Thus, the current in vitro model of AChR clustering using SMA patient-derived iPSCs is useful to dissect the pathophysiological mechanisms underlying the development of SMA, and to evaluate the efficacy of new therapeutic approaches.
Affiliation: Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan; Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.Show MeSH
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Mentions: To further explore the validity of NMJ-LSs, we next evaluated the effects of splicing modification on SMN2. Recently, the application of antisense oligonucleotides to promote SMN2 exon 7 retention has been proposed as an alternative therapeutic approach for SMA (Mitrpant et al., 2013). For this purpose, we introduced phosphorodiamidate morpholino oligonucleotides (PMOs) targeting the intronic silencing motif in SMN2 intron 7. Consequently, the SMN-specific PMO treatment dramatically improved AChR clustering with the patient-derived MNs (Figures 4A, 4B, and S3D). The PMO treatment also recovered the expression of SMN-FL (Figure 4C) and improved, at least partially, the abnormal NF accumulation (Figure 4A). We consider that these data indicate the potential therapeutic advantages of PMO for SMA patients. Overall, the NMJ-LS morphology could be useful for evaluating new therapeutic approaches for SMA.
Affiliation: Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan; Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.