Poster abstracts
Poster number 104 submitted by Robert Patton
RIPiT-Seq analysis suggests a compositional switch between structurally and functionally distinct exon junction complexes
Robert Patton (Department of Physics, The Ohio State University), Justin Mabin (Department of Molecular Genetics, The Ohio State University), Lauren Woodward (Department of Molecular Genetics, The Ohio State University), Ralf Bundschuh (Department of Physics, Center for RNA Biology, The Ohio State University), Guramrit Singh (Department of Molecular Genetics, Center for RNA Biology, The Ohio State University)
Abstract:
The exon junction complex (EJC) is a protein complex first deposited upstream of exon splice junctions during pre-mRNA splicing. The EJC plays a vital role in shaping the fate of an mRNA by nucleating the assembly of peripheral proteins which function in diverse post-transcriptional processes, especially nonsense-mediated decay (NMD). RIPiT-Seq footprint analysis of the EJC core bound to the mutually exclusive peripheral proteins RNPS1 and CASC3 reveals that alternate EJCs similarly bind to junctions on a gene by gene basis. Further analysis of genes which are found with significantly higher levels of RNPS1 or CASC3 shows heightened levels of RNPS1 containing EJCs on transcripts associated with the nucleus and CASC3 containing EJCs in transcripts associated with the cytoplasm. Treatment with the translation inhibitor cycloheximide also causes a large increase in the number of transcripts with CASC3 containing EJCs, indicating a build up of CASC3 EJCs in the cytoplasm. We conclude that when the EJC is first assembled in the nucleus it contains the protein RNPS1, but that some time before translation goes through a compositional change in which RNPS1 is replaced with CASC3. This switch leads to two distinct EJCs with separate NMD pathways.
Keywords: nonsense-mediated decay (NMD), pre-mRNA splicing, exon junction complex (EJC)