The mdx mouse is a model of Duchenne muscular dystrophy, carrying a premature termination codon in exon 23 of dystrophin. Morpholino oligos targeting dystrophin exon 23 were delivered from a micro-osmotic pump via cannula intracerebroventricularly. The unmodified Morpholino oligos triggered excision of dystrophin exon 23 and sometimes both exons 22 and 23, removing the premature termination codon. While a small fraction of the transcripts underwent modified splicing, this was sufficient to ameliorate behavioral abnormalities of the mdx mice.
RT-PCR of mRNA isolated from (mostly) the cerebral cortex, amygdala and hippocampus predominantly revealed the wild-type band with exons 22-23-24, though dystrophin transcripts missing exon 23 and others missing exons 22 and 23 were visibly present in lanes from antisense treated mice but not sense treated mice. Western blots revealed that, after Morpholino treatment, the transcript downstream of exon 23 was translated in the forebrain.
Sekiguchi M, Zushida K, Yoshida M, Maekawa M, Kamichi S, Yoshida M, Sahara Y, Yuasa S, Takeda S, Wada K. A deficit of brain dystrophin impairs specific amygdala GABAergic transmission and enhances defensive behaviour in mice. Brain. 2008 Oct 16. [Epub ahead of print]