title: Restoration of SMN function: delivery of a trans-splicing RNA re-directs SMN2 pre-mRNA splicing.
abstract: Spinal muscular atrophy (SMA) is caused by loss of survival motor neuron-1 (SMN1). A nearly identical copy gene called SMN2 is present in all SMA patients; however SMN2 produces low levels of functional protein due to alternative splicing. Recently a therapeutic approach has been developed referred to as trans-splicing. Conceptually, this strategy relies upon pre-messenger RNA (pre-mRNA) splicing occurring between two separate molecules: (i) the endogenous target RNA and (ii) the therapeutic RNA that provides the correct RNA sequence via a trans-splicing event. SMN trans-splicing RNAs were initially examined and expressed from a plasmid-backbone and shown to re-direct splicing from a SMN2 mini-gene as well as from endogenous transcripts. Subsequently, recombinant adeno-associated viral vectors were developed that expressed and delivered trans-splicing RNAs to SMA patient fibroblasts. In the severe SMA patient fibroblasts, SMN2 splicing was redirected via trans-splicing to produce increased levels of full-length SMN mRNA and total SMN protein levels. Finally, small nuclear ribonucleoprotein (snRNP) assembly, a critical function of SMN, was restored to SMN-deficient SMA fibroblasts following treatment with the trans-splicing vector. Together these results demonstrate that the alternatively spliced SMN2 exon 7 is a tractable target for replacement by trans-splicing.
authors.affiliation: Department of Veterinary Pathobiology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211-7310, USA.
authors.forename: Tristan H
authors.initials: TH
authors.lastname: Coady
authors.forename: Monir
authors.initials: M
authors.lastname: Shababi
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Tullis
authors.forename: Christian L
authors.initials: CL
authors.lastname: Lorson
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D002470:Cell Survival; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics* / Q000378:metabolism*; D005347:Fibroblasts; D018014:Gene Transfer Techniques; D006801:Humans; D008969:Molecular Sequence Data; D009134:Muscular Atrophy, Spinal / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D055532:SMN Complex Proteins; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein; D020040:Trans-Splicing / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; 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