Protein-truncating mutations in the dystrophin gene lead to the most common childhood form of muscle wasting, Duchenne muscular dystrophy. Becker muscular dystrophy, a condition that typically arises from dystrophin gene lesions that do not disrupt the reading frame, clearly indicates that substantial domains of the dystrophin protein are not essential. Potential therapeutic intervention exists during pre-mRNA splicing, whereby selected exons are excised to either remove nonsense mutations or restore the reading frame around frame-shifting mutations from the mature mRNA. Appropriately designed antisense oligonucleotides (AOs), directed at amenable splicing motifs across the dystrophin gene transcript, block exon recognition and/or spliceosome assembly so that targeted exons are removed from the mature mRNA. We describe a panel of AOs designed to induce skipping of every exon within the human dystrophin gene transcript, with the exception of the first and last exons. Every exon targeted in vitro could be removed from the dystrophin mRNA, although some exons are more efficiently excluded than others. No single motif has emerged as a universal AO annealing site for redirection of dystrophin pre-mRNA processing, although the general trend is that the most efficient compounds are directed at motifs in the first half of the target exon.
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mice were fed for 10 days with PL (300 mg/kg) or vehicle then UV-irradiated, once. By 24 hours, UVinduced Cox-2 levels were increased in vehicle-fed and PL-fed mice, whereas by 48 and 72 hours, Cox-2 levels were four-to fivefold lower in PL-fed mice (P < 0.05). p53 expression/activity was increased in PL-fed versus vehicle-fed then UV-irradiated mice. UV-induced inflammation was decreased in PL-fed mice, as shown by ϳ60% decrease (P < 0.001) in neutrophil infiltration at 24 hours, and macrophages by ϳ50% (<0.02) at 24 and 48 hours. By 72 hours, 54 ؎ 5% cyclobutane pyrimidine dimers remained in vehiclefed versus 31 ؎ 5% in PL-fed skin (P < 0.003). The number of 8-hydroxy-2-deoxyguanosine-positive cells were decreased before UV irradiation by ϳ36% (P < 0.01), suggesting that PL reduces constitutive oxidative DNA damage. By 6 and 24 hours, the number of 8-hydroxy-2-deoxyguanosine-positive cells were ϳ59% (P < 0.01) and ϳ79% (P < 0.03) lower in PL-fed versus vehicle-fed mice. Finally, UV-induced mutations in PL-fed-mice were decreased by ϳ25% when assessed 2 weeks after the single UV exposure. These data demonstrate that PL extract supplementation affords the following photoprotective effects: p53 activation and reduction of acute inflammation via Cox-2 enzyme inhibition, increased cyclobutane pyrimidine dimer removal, and reduction of oxidative DNA damage.
Background: Antisense oligonucleotides (AOs) can interfere with exon recognition and intron removal during pre-mRNA processing, and induce excision of a targeted exon from the mature gene transcript. AOs have been used in vitro and in vivo to redirect dystrophin pre-mRNA processing in human and animal cells. Targeted exon skipping of selected exons in the dystrophin gene transcript can remove nonsense or frame-shifting mutations that would otherwise have lead to Duchenne Muscular Dystrophy, the most common childhood form of muscle wasting.
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