Bifunctional antisense oligonucleotides provide a trans-acting splicing enhancer that stimulates XXXX gene expression in @entity1 fibroblasts.

@entity1 @entity23247 @entity377 @entity74 @entity11280 @entity2057
The multiplicity of proteins compared with genes in mammals owes much to alternative splicing. Splicing signals are so subtle and complex that small perturbations may allow the production of new mRNA variants. However, the flexibility of splicing can also be a liability, and several @entity74 result from single-base changes that cause exons to be skipped during splicing. Conventional oligonucleotide strategies can block reactions but cannot restore splicing. We describe here a method by which the use of a defective exon was restored. @entity2057 ( @entity2057 ) results from mutations of the Survival Motor Neuron (SMN) gene. Mutations of @entity11280 cause @entity2057 , whereas @entity23247 acts as a modifying gene. The two genes undergo alternative splicing with @entity11280 , producing an abundance of full-length mRNA transcripts, whereas @entity23247 predominantly produces exon 7-deleted transcripts. This discrepancy is because of a single @entity377 difference in @entity23247 exon 7, which disrupts an exonic splicing enhancer containing an SF2ASF binding site. We have designed oligoribonucleotides that are complementary to exon 7 and contain exonic splicing enhancer motifs to provide trans-acting enhancers. These tailed oligoribonucleotides increased @entity23247 exon 7 splicing in vitro and rescued the incorporation of @entity23247 exon 7 in @entity2057 @entity1 fibroblasts. This treatment also resulted in the partial restoration of gems, intranuclear structures containing SMN protein that are severely reduced in @entity1 with @entity2057 . The use of tailed antisense oligonucleotides to recruit positively acting factors to stimulate a splicing reaction may have therapeutic applications for @entity74 , such as @entity2057 , in which splicing patterns are altered.
