Control of hnRNP A1 alternative splicing: an intron element represses use of the common 3' splice site.
Alternative splicing of exon 7B in the hnRNP A1 pre-mRNA produces mRNAs encoding two proteins: hnRNP A1 and the less abundant A1B. We have reported the identification of several intron elements that contribute to exon 7B skipping. In this study, we report the activity of a novel element, conserved element 9 (CE9), located in the intron downstream of exon 7B. We show that multiple copies of CE9 inhibit exon 7B-exon 8 splicing in vitro. When CE9 is inserted between two competing 3' splice sites, a single copy of CE9 decreases splicing to the distal 3' splice site. Our in vivo results also support the conclusion that CE9 is a splicing modulator. First, inserting multiple copies of CE9 into an A1 minigene compromises the production of fully spliced products. Second, one copy of CE9 stimulates the inclusion of a short internal exon in a derivative of the human beta-globin gene. In this case, in vitro splicing assays suggest that CE9 decreases splicing of intron 1, an event that improves splicing of intron 2 and decreases skipping of the short internal exon. The ability of CE9 to act on heterologous substrates, combined with the results of a competition assay, suggest that the activity of CE9 is mediated by a trans-acting factor. Our results indicate that CE9 represses the use of the common 3' splice site in the hnRNP A1 alternative splicing unit.
Simard
M J
MJ
Département de Microbiologie et d'Infectiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4.
Chabot
B
B
D017398:Alternative Splicing / Q000502:physiology*; D001483:Base Sequence; D005091:Exons / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006367:HeLa Cells; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012261:Ribonucleoproteins / Q000235:genetics*; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D015534:Trans-Activators / Q000502:physiology
D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D012322:RNA Precursors; D012261:Ribonucleoproteins; C080681:TRIM23 protein, human; D015534:Trans-Activators; D019204:GTP-Binding Proteins