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An in vivo reporter system for measuring increased inclusion of exon 7 in SMN2 mRNA: potential therapy of SMA

Gene Therapy volume 8, pages 1532–1538 (2001)Cite this article

Abstract

Spinal muscular atrophy (SMA) is a degenerative motor neuron disorder resulting from homozygous loss of the SMN1 gene. SMN2, a nearly identical copy gene, is preserved in SMA patients. A single nucleotide difference between SMN1 and SMN2 causes exon 7 skipping in the majority of SMN2 mRNA. Gene therapy through modulation of SMN2 gene transcription in SMA patients may be possible. We constructed a series of SMN mini-genes comprised of SMN exon 6 to exon 8 sequences fused to green fluorescence protein (GFP) or luciferase reporters, to monitor SMN exon 7 splicing. These reporters recapitulated the splicing patterns of the endogenous SMN gene in stable cell lines. The SMN1-luciferase reporter was approximately 3.5-fold more active than SMN2-luciferase and SMN1-GFP intensities were visually distinguishable from SMN2-GFP. We have screened chemical inducers and inhibitors of kinase pathways using stable SMN-reporter lines and found that the phosphatase inhibitor sodium vanadate specifically stimulated exon 7 inclusion within SMN2 mRNAs. This is the first compound identified that can stimulate exon 7 inclusion into transcripts derived from the endogenous SMN2 gene. These results demonstrate that this system can be utilized to identify small molecules that regulate the splicing of SMN exon 7.

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Acknowledgements

We thank Adrian Krainer for the Tra2β1 expression constructs. Funding for these studies was provided by the Muscular Dystrophy Association, and NIH R01 NS40275 to EJA. JZ was supported by Andrew's Buddies and Families of SMA. CLL was supported by a New Investigator Development Award from the Muscular Dystrophy Association.

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Authors and Affiliations

  1. Department of Dermatology, New England Medical Center and Tufts University School of Medicine, Boston, MA, USA

    ML Zhang, EJ Androphy & J Zhou

  2. Department of Biology, Arizona State University, Tempe, AZ, USA

    CL Lorson

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  1. ML Zhang
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  2. CL Lorson
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  3. EJ Androphy
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  4. J Zhou
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Zhang, M., Lorson, C., Androphy, E. et al. An in vivo reporter system for measuring increased inclusion of exon 7 in SMN2 mRNA: potential therapy of SMA. Gene Ther 8, 1532–1538 (2001). https://doi.org/10.1038/sj.gt.3301550

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