title: Absence of an intron splicing silencer in porcine Smn1 intron 7 confers immunity to the exon skipping mutation in human SMN2.
abstract: 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.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark.
authors.forename: Thomas Koed
authors.initials: TK
authors.lastname: Doktor
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus C, Denmark.
authors.forename: Lisbeth Dahl
authors.initials: LD
authors.lastname: Schrøder
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark.
authors.forename: Henriette Skovgaard
authors.initials: HS
authors.lastname: Andersen
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Brøner
authors.affiliation: Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kitewska
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus C, Denmark.
authors.forename: Charlotte Brandt
authors.initials: CB
authors.lastname: Sørensen
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark.
authors.forename: Brage Storstein
authors.initials: BS
authors.lastname: Andresen
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D005091:Exons; D023061:Gene Order; D056426:Genetic Loci; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000378:metabolism; D006801:Humans; D007438:Introns; D009154:Mutation; D012326:RNA Splicing; D016415:Sequence Alignment; D037941:Silencer Elements, Transcriptional; D055533:Survival of Motor Neuron 1 Protein / Q000235:genetics*; D055540:Survival of Motor Neuron 2 Protein / Q000235:genetics*; D013552:Swine
chemical_list: D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein