title: CAG repeats mimic CUG repeats in the misregulation of alternative splicing.
abstract: Mutant transcripts containing expanded CUG repeats in the untranslated region are a pathogenic factor in myotonic dystrophy type 1 (DM1). The mutant RNA sequesters the muscleblind-like 1 (MBNL1) splicing factor and causes misregulation of the alternative splicing of multiple genes that are linked to clinical symptoms of the disease. In this study, we show that either long untranslated CAG repeat RNA or short synthetic CAG repeats induce splicing aberrations typical of DM1. Alternative splicing defects are also caused by translated CAG repeats in normal cells transfected with a mutant ATXN3 gene construct and in cells derived from spinocerebellar ataxia type 3 and Huntington's disease patients. Splicing misregulation is unlikely to be caused by traces of antisense transcripts with CUG repeats, and the possible trigger of this misregulation may be sequestration of the MBNL1 protein with nuclear RNA inclusions containing expanded CAG repeat transcripts. We propose that alternative splicing misregulation by mutant CAG repeats may contribute to the pathological features of polyglutamine disorders.
authors.affiliation: Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704 Poznan, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Mykowska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Sobczak
authors.forename: Marzena
authors.initials: M
authors.lastname: Wojciechowska
authors.forename: Piotr
authors.initials: P
authors.lastname: Kozlowski
authors.forename: Wlodzimierz J
authors.initials: WJ
authors.lastname: Krzyzosiak
mesh_terms: D017398:Alternative Splicing; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D006367:HeLa Cells; D006801:Humans; D006816:Huntington Disease / Q000235:genetics; D017827:Machado-Joseph Disease / Q000235:genetics; D009223:Myotonic Dystrophy / Q000235:genetics; D016601:RNA-Binding Proteins / Q000032:analysis; D019680:Trinucleotide Repeat Expansion; D018911:Trinucleotide Repeats; D020506:Untranslated Regions
chemical_list: C493663:MBNL1 protein, human; D016601:RNA-Binding Proteins; D020506:Untranslated Regions