title: hnRNP A1 and hnRNP F modulate the alternative splicing of exon 11 of the insulin receptor gene.
abstract: Exon 11 of the insulin receptor gene (INSR) is alternatively spliced in a developmentally and tissue-specific manner. Linker scanning mutations in a 5' GA-rich enhancer in intron 10 identified AGGGA sequences that are important for enhancer function. Using RNA-affinity purification and mass spectrometry, we identified hnRNP F and hnRNP A1 binding to these AGGGA sites and also to similar motifs at the 3' end of the intron. The hnRNPs have opposite functional effects with hnRNP F promoting and hnRNP A1 inhibiting exon 11 inclusion, and deletion of the GA-rich elements eliminates both effects. We also observed specific binding of hnRNP A1 to the 5' splice site of intron 11. The SR protein SRSF1 (SF2/ASF) co-purified on the GA-rich enhancer and, interestingly, also competes with hnRNP A1 for binding to the splice site. A point mutation -3U→C decreases hnRNP A1 binding, increases SRSF1 binding and renders the exon constitutive. Lastly, our data point to a functional interaction between hnRNP F and SRSF1 as a mutant that eliminates SRSF1 binding to exon 11, or a SRSF1 knockdown, which prevents the stimulatory effect of hnRNP F over expression.
authors: VA San Diego Healthcare System, San Diego, California, United States of America.
authors: Indrani
authors: I
authors: Talukdar
authors: Supriya
authors: S
authors: Sen
authors: Rodolfo
authors: R
authors: Urbano
authors: James
authors: J
authors: Thompson
authors: John R
authors: JR
authors: Yates
authors: Nicholas J G
authors: NJ
authors: Webster
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D005091:Exons / Q000235:genetics*; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D056945:Hep G2 Cells; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000378:metabolism*; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000378:metabolism*; D006801:Humans; D007438:Introns / Q000235:genetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D059372:Nucleotide Motifs / Q000235:genetics; D011485:Protein Binding; D016601:RNA-Binding Proteins / Q000378:metabolism; D011972:Receptor, Insulin / Q000235:genetics*; D000068103:Serine-Arginine Splicing Factors
chemical_list: D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; D011972:Receptor, Insulin