HMGA1a trapping of U1 snRNP at an authentic 5' splice site induces aberrant exon skipping in sporadic Alzheimer's disease.
Overexpression of high-mobility group A protein 1a (HMGA1a) causes aberrant exon 5 skipping of the Presenilin-2 (PS2) pre-mRNA, which is almost exclusively detected in patients with sporadic Alzheimer's disease. An electrophoretic mobility shift assay confirmed aberrant U1 small nuclear ribonucleoprotein particle (snRNP)-HMGA1a complex formation (via the U1-70K component), with RNA containing a specific HMGA1a-binding site and an adjacent 5' splice site. Psoralen cross-linking analysis demonstrated that the binding of HMGA1a adjacent to the 5' splice site induces unusually extended association of U1 snRNP to the 5' splice site. As a result, spliceosome assembly across either the intron or the exon is arrested at an early ATP-independent stage. We conclude that the HMGA1a-induced aberrant exon skipping is caused by impaired dissociation of U1 snRNP from the 5' splice site, leading to a defect in exon definition. The proposed molecular mechanism has profound implications for other known posttranscriptional modulation strategies in various organisms, all of which are triggered by aberrant U1 snRNP binding.
Ohe
Kenji
K
Institute for Comprehensive Medical Science (ICMS), Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
Mayeda
Akila
A
D000544:Alzheimer Disease / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D005091:Exons / Q000235:genetics*; D025741:HMGA1a Protein / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007438:Introns / Q000235:genetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D022821:RNA Splice Sites / Q000235:genetics*; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000378:metabolism*; D017381:Spliceosomes / Q000378:metabolism
D022821:RNA Splice Sites; D017412:Ribonucleoprotein, U1 Small Nuclear; D025741:HMGA1a Protein