title: Therapeutic strategies based on modified U1 snRNAs and chaperones for Sanfilippo C splicing mutations.
abstract: BACKGROUND
  Mutations affecting RNA splicing represent more than 20% of the mutant alleles in Sanfilippo syndrome type C, a rare lysosomal storage disorder that causes severe neurodegeneration. Many of these mutations are localized in the conserved donor or acceptor splice sites, while few are found in the nearby nucleotides.
  
  
  METHODS
  In this study we tested several therapeutic approaches specifically designed for different splicing mutations depending on how the mutations affect mRNA processing. For three mutations that affect the donor site (c.234 + 1G > A, c.633 + 1G > A and c.1542 + 4dupA), different modified U1 snRNAs recognizing the mutated donor sites, have been developed in an attempt to rescue the normal splicing process. For another mutation that affects an acceptor splice site (c.372-2A > G) and gives rise to a protein lacking four amino acids, a competitive inhibitor of the HGSNAT protein, glucosamine, was tested as a pharmacological chaperone to correct the aberrant folding and to restore the normal trafficking of the protein to the lysosome.
  
  
  RESULTS
  Partial correction of c.234 + 1G > A mutation was achieved with a modified U1 snRNA that completely matches the splice donor site suggesting that these molecules may have a therapeutic potential for some splicing mutations. Furthermore, the importance of the splice site sequence context is highlighted as a key factor in the success of this type of therapy. Additionally, glucosamine treatment resulted in an increase in the enzymatic activity, indicating a partial recovery of the correct folding.
  
  
  CONCLUSIONS
  We have assayed two therapeutic strategies for different splicing mutations with promising results for the future applications.
authors.affiliation: Department of Human Genetics, Research and Development Unit, INSA, Porto, Portugal. liliana.matos@insa.min-saude.pt.|Department of Biology, Faculty of Sciences, Porto, Portugal. liliana.matos@insa.min-saude.pt.
authors.forename: Liliana
authors.initials: L
authors.lastname: Matos
authors.affiliation: Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain. icanals@ub.edu.|CIBER de Enfermedades Raras (CIBERER), Madrid, Spain. icanals@ub.edu.|Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Spain. icanals@ub.edu.
authors.forename: Isaac
authors.initials: I
authors.lastname: Canals
authors.affiliation: Department of Medical Genetics, Sainte-Justine University Hospital Centre, University of Montreal, Montreal, Canada. larbidridi.stejustine@gmail.com.
authors.forename: Larbi
authors.initials: L
authors.lastname: Dridi
authors.affiliation: Department of Medical Genetics, Sainte-Justine University Hospital Centre, University of Montreal, Montreal, Canada. yoochoi0730@gmail.com.
authors.forename: Yoo
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Department of Biology, Faculty of Sciences, Porto, Portugal. mprata@ipatimup.pt.|IPATIMUP, Porto, Portugal. mprata@ipatimup.pt.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Prata
authors.affiliation: Department of Human Genetics, Research and Development Unit, INSA, Lisbon, Portugal. peter.jordan@insa.min-saude.pt.
authors.forename: Peter
authors.initials: P
authors.lastname: Jordan
authors.affiliation: CIBER de Enfermedades Raras (CIBERER), Madrid, Spain. lruiz@cbm.csic.es.|Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain. lruiz@cbm.csic.es.
authors.forename: Lourdes R
authors.initials: LR
authors.lastname: Desviat
authors.affiliation: CIBER de Enfermedades Raras (CIBERER), Madrid, Spain. bperez@cbm.uam.es.|Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa, UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain. bperez@cbm.uam.es.
authors.forename: Belén
authors.initials: B
authors.lastname: Pérez
authors.affiliation: Department of Medical Genetics, Sainte-Justine University Hospital Centre, University of Montreal, Montreal, Canada. alexei.pchejetski@umontreal.ca.|Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Canada. alexei.pchejetski@umontreal.ca.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Pshezhetsky
authors.affiliation: Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain. dgrinberg@ub.edu.|CIBER de Enfermedades Raras (CIBERER), Madrid, Spain. dgrinberg@ub.edu.|Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Spain. dgrinberg@ub.edu.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grinberg
authors.affiliation: Department of Human Genetics, Research and Development Unit, INSA, Porto, Portugal. sandra.alves@insa.min-saude.pt.
authors.forename: Sandra
authors.initials: S
authors.lastname: Alves
authors.affiliation: Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain. lvilageliu@ub.edu.|CIBER de Enfermedades Raras (CIBERER), Madrid, Spain. lvilageliu@ub.edu.|Institut de Biomedicina de la Universitat de Barcelona (IBUB), Barcelona, Spain. lvilageliu@ub.edu.
authors.forename: Lluïsa
authors.initials: L
authors.lastname: Vilageliu
mesh_terms: D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D015316:Genetic Therapy / Q000379:methods; D006801:Humans; D018832:Molecular Chaperones / Q000235:genetics*; D009084:Mucopolysaccharidosis III / Q000175:diagnosis / Q000235:genetics* / Q000628:therapy*; D009154:Mutation / Q000235:genetics*; D012326:RNA Splicing / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*
chemical_list: D018832:Molecular Chaperones; D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA