A study of readthrough therapy for spinal muscular atrophy in a transgenic mouse model

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Spinal Muscular Atrophy (SMA) is due to the loss of the telomeric survival motor neuron gene (SMN1) and results in degeneration of motor neurons, muscle atrophy, and loss of motor function. The centromeric SMN gene (SMN2) is nearly identical to SMN1 except for one nucleotide difference in exon 7 which causes most of the transcripts to be alternatively spliced and degraded. Aminoglycosides are antibiotics that interact with ribosomes causing them to read through stop codons. When aminoglycosides destabilize ribosomes, a tRNA is read for at the stop codon instead of a release factor binding and ending translation. Ideally, aminoglycosides will extend SMN[uppercase delta]7 protein to the second stop codon in exon 8, adding 5 extra amino acids. Readthrough SMN[uppercase delta]7 protein is shown to be more stable and functional than SMN[uppercase delta]7 protein in vitro. To determine the effect of Readthrough therapy in vivo, we designed a transgenic mouse model that expresses Readthrough SMN[uppercase delta]7 protein to mimic a readthrough event. As a proof of principle, this analysis of a readthrough transgenic SMA mouse model will provide insight to the importance of further development of readthrough drugs for SMA treatment.