| First Author | Wang L | Year | 2023 |
| Journal | Hum Mol Genet | Volume | 32 |
| Issue | 6 | Pages | 971-983 |
| PubMed ID | 36255739 | Mgi Jnum | J:355041 |
| Mgi Id | MGI:7446911 | Doi | 10.1093/hmg/ddac260 |
| Citation | Wang L, et al. (2023) A splicing silencer in SMN2 intron 6 is critical in spinal muscular atrophy. Hum Mol Genet 32(6):971-983 |
| abstractText | Spinal muscular atrophy (SMA) is a fatal neuromuscular disease caused by homozygous deletions or mutations of the SMN1 gene. SMN2 is a paralogous gene of SMN1 and a modifying gene of SMA. A better understanding of how SMN2 exon 7 splicing is regulated helps discover new therapeutic targets for SMA therapy. Based on an antisense walk method to map exonic and intronic splicing silencers (ESSs and ISSs) in SMN2 exon 7 and the proximal regions of its flanking introns, we identified one ISS (ISS6-KH) at upstream of the branch point site in intron 6. By using mutagenesis-coupled RT-PCR with SMN1/2 minigenes, immunochromatography, overexpression and siRNA-knockdown, we found this ISS consists of a bipartite hnRNP A1 binding cis-element and a poly-U sequence located between the proximal hnRNP A1 binding site (UAGCUA) and the branch site. Both HuR and hnRNP C1 proteins promote exon 7 skipping through the poly-U stretch. Mutations or deletions of these motifs lead to efficient SMN2 exon 7 inclusion comparable to SMN1 gene. Furthermore, we identified an optimal antisense oligonucleotide that binds the intron six ISS and causes striking exon 7 inclusion in the SMN2 gene in patient fibroblasts and SMA mouse model. Our findings demonstrate that this novel ISS plays an important role in SMN2 exon 7 skipping and highlight a new therapeutic target for SMA therapy. |
