An in vivo reporter system for measuring increased inclusion of exon 7 in SMN2 mRNA: potential therapy of SMA.
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.
Zhang
M L
ML
Department of Dermatology, New England Medical Center and Tufts University School of Medicine, Boston, MA 02111, USA.
Lorson
C L
CL
Androphy
E J
EJ
Zhou
J
J
D019677:Artificial Gene Fusion / Q000379:methods; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005091:Exons; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D049452:Green Fluorescent Proteins; D006801:Humans; D008156:Luciferases / Q000235:genetics; D008164:Luminescent Proteins / Q000235:genetics; D009046:Motor Neurons / Q000378:metabolism*; D009134:Muscular Atrophy, Spinal / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D012326:RNA Splicing / Q000187:drug effects*; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055532:SMN Complex Proteins; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D014162:Transfection / Q000379:methods; D014638:Vanadates / Q000494:pharmacology*
D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; C526477:SMN2 protein, human; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D049452:Green Fluorescent Proteins; D014638:Vanadates; D008156:Luciferases; D010744:Phosphoric Monoester Hydrolases