Absence of an intron splicing silencer in porcine Smn1 intron 7 confers immunity to the exon skipping mutation in human SMN2

Spinal Muscular Atrophy is caused by homozygous loss of SMN1. All patients retain at least one copy of SMN2 which produces an identical protein but at lower levels due to a silent mutation in exon 7 which results in predominant exclusion of the exon. Therapies targeting the splicing of SMN2 exon 7 h...

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Bibliographic Details
Published in:PloS one 2014-06, Vol.9 (6), p.e98841-e98841
Main Authors: Doktor, Thomas Koed, Schrøder, Lisbeth Dahl, Andersen, Henriette Skovgaard, Brøner, Sabrina, Kitewska, Anna, Sørensen, Charlotte Brandt, Andresen, Brage Storstein
Format: Article
Language:English
Subjects:
Animal models
Animals
Atrophy
Base Sequence
Binding Sites
Biochemistry
Biology and life sciences
Consensus Sequence
Disease
Exon skipping
Exons
Gene expression
Gene Order
Genes
Genetic aspects
Genetic Loci
Heterogeneous Nuclear Ribonucleoprotein A1
Heterogeneous-Nuclear Ribonucleoprotein Group A-B - metabolism
Hogs
Humans
Immunity
In vivo methods and tests
Introns
Metabolism
Molecular biology
Mutation
Neuromuscular diseases
Physiology
Proteins
Regulatory sequences
Research and Analysis Methods
RNA Splicing
Rodents
Sequence Alignment
Silencer Elements, Transcriptional
SMN protein
Spinal muscular atrophy
Splicing
Survival of Motor Neuron 1 Protein - genetics
Survival of Motor Neuron 2 Protein - genetics
Swine
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Summary:Spinal Muscular Atrophy is caused by homozygous loss of SMN1. All patients retain at least one copy of SMN2 which produces an identical protein but at lower levels due to a silent mutation in exon 7 which results in predominant exclusion of the exon. Therapies targeting the splicing of SMN2 exon 7 have been in development for several years, and their efficacy has been measured using either in vitro cellular assays or in vivo small animal models such as mice. In this study we evaluated the potential for constructing a mini-pig animal model by introducing minimal changes in the endogenous porcine Smn1 gene to maintain the native genomic structure and regulation. We found that while a Smn2-like mutation can be introduced in the porcine Smn1 gene and can diminish the function of the ESE, it would not recapitulate the splicing pattern seen in human SMN2 due to absence of a functional ISS immediately downstream of exon 7. We investigated the ISS region and show here that the porcine ISS is inactive due to disruption of a proximal hnRNP A1 binding site, while a distal hnRNP A1 binding site remains functional but is unable to maintain the functionality of the ISS as a whole.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0098841