An exon that prevents transport of a mature mRNA.
In Caenorhabditis elegans, pre-mRNA for the essential splicing factor U2AF65 sometimes is spliced to produce an RNA that includes an extra 216-bp internal exon, exon 3. Inclusion of exon 3 inserts an in-frame stop codon, yet this RNA is not subject to SMG-mediated RNA surveillance. To test whether exon 3 causes RNA to remain nuclear and thereby escape decay, we inserted it into the 3' untranslated region of a gfp reporter gene. Although exon 3 did not affect accumulation or processing of the mRNA, it dramatically suppressed expression of green fluorescent protein (GFP). We showed by in situ hybridization that exon 3-containing gfp RNA is retained in the nucleus. Intriguingly, exon 3 contains 10 matches to the 8-bp 3' splice-site consensus. We hypothesized that U2AF might recognize this octamer and thereby prevent export. This idea is supported by RNA interference experiments in which reduced levels of U2AF resulted in a small burst of gfp expression.
MacMorris
M A
MA
Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
Zorio
D A
DA
Blumenthal
T
T
D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000502:physiology; D005091:Exons; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D009687:Nuclear Proteins; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D012261:Ribonucleoproteins / Q000235:genetics*; D000072668:Splicing Factor U2AF; D014158:Transcription, Genetic
D008164:Luminescent Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D000072668:Splicing Factor U2AF; D049452:Green Fluorescent Proteins