An exonic splicing enhancer in human IGF-I pre-mRNA mediates recognition of alternative exon 5 by the serine-arginine protein splicing factor-2/alternative splicing factor.
The human IGF-I gene has six exons, four of which are alternatively spliced. Variations in splicing involving exon 5 may occur, depending on the tissue type and hormonal environment. To study the regulation of splicing to IGF-I exon 5, we established an in vitro splicing assay, using a model pre-mRNA containing IGF-I exons 4 and 5 and part of the intervening intron. Using a series of deletion mutants, we identified an 18-nucleotide purine-rich splicing enhancer in exon 5 that increases the splicing efficiency of the upstream intron from 6 to 35%. We show that the serine-arginine protein splicing factor-2/alternative splicing factor specifically promotes splicing in cultured cells and in vitro and is recruited to the spliceosome in an enhancer-specific manner. Our findings are consistent with a role for splicing factor-2/alternative splicing factor in the regulation of splicing of IGF-I alternative exon 5 via a purine-rich exonic splicing enhancer.
Smith
Philip J
PJ
Department of Endocrinology, St. Bartholomew's Hospital, Queen Mary, University of London, London EC1A 7BE, United Kingdom.
Spurrell
Emma L
EL
Coakley
John
J
Hinds
Charles J
CJ
Ross
Richard J M
RJ
Krainer
Adrian R
AR
Chew
Shern L
SL
D017398:Alternative Splicing / Q000502:physiology*; D004742:Enhancer Elements, Genetic / Q000502:physiology*; D005091:Exons / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D018482:Muscle, Skeletal / Q000502:physiology; D009687:Nuclear Proteins / Q000494:pharmacology / Q000502:physiology*; D012322:RNA Precursors / Q000235:genetics*; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; D017381:Spliceosomes / Q000502:physiology
D009687:Nuclear Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; D007334:Insulin-Like Growth Factor I