title: U1 snRNA-mediated gene therapeutic correction of splice defects caused by an exceptionally mild BBS mutation.
abstract: Bardet-Biedl syndrome (BBS) is a multisystem disorder caused by ciliary defects. To date, mutations in 15 genes have been associated with the disease and BBS1 is most frequently affected in patients with BBS. The use of homozygosity mapping in a large consanguineous family allowed us to identify the splice donor site (SD) mutation c.479G>A in exon 5 of BBS1. Clinically affected family members show symptoms of retinitis pigmentosa (RP) but lack other primary features that would clearly support the diagnosis of BBS. In agreement with this exceptionally mild BBS1-associated phenotype, we did not detect obvious ciliary defects in patient-derived cells. SDs are bound by the U1 small nuclear RNA (U1), a process that initiates exon recognition during splicing. The mutation described herein interferes with U1 binding and induces aberrant splicing of BBS1. For a gene therapeutic approach, we have adapted the sequence of U1 to increase its complementarity to the mutated SD. Lentiviral treatment of patient-derived fibroblasts with the adapted U1 partially corrected aberrant splicing of endogenously expressed BBS1 transcripts. This therapeutic effect was dose-dependent. Our results show that the adaptation of U1 can correct pathogenic effects of splice donor site mutations and suggest a high potential for gene therapy.
authors.affiliation: University of Zurich, Institute of Medical Molecular Genetics, Schorenstrasse 16, Schwerzenbach, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Schmid
authors.forename: Esther
authors.initials: E
authors.lastname: Glaus
authors.forename: Daniel
authors.initials: D
authors.lastname: Barthelmes
authors.forename: Manfred
authors.initials: M
authors.lastname: Fliegauf
authors.forename: Harald
authors.initials: H
authors.lastname: Gaspar
authors.forename: Gudrun
authors.initials: G
authors.lastname: Nürnberg
authors.forename: Peter
authors.initials: P
authors.lastname: Nürnberg
authors.forename: Heymut
authors.initials: H
authors.lastname: Omran
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Berger
authors.forename: John
authors.initials: J
authors.lastname: Neidhardt
mesh_terms: D000328:Adult; D020788:Bardet-Biedl Syndrome / Q000235:genetics* / Q000628:therapy*; D002478:Cells, Cultured; D005091:Exons; D005260:Female; D005347:Fibroblasts; D015870:Gene Expression; D008040:Genetic Linkage; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D016086:Lentivirus; D008297:Male; D008869:Microtubule-Associated Proteins; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D011485:Protein Binding / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D022821:RNA Splice Sites / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D012174:Retinitis Pigmentosa / Q000235:genetics / Q000628:therapy
chemical_list: C464790:Bbs1 protein, human; D008869:Microtubule-Associated Proteins; D011506:Proteins; D022821:RNA Splice Sites; D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA