Poster abstracts
Poster number 120 submitted by Grace Eramo
Translational control by alternative splicing in the 5' untranslated region
Grace A. Eramo (Department of Pharmacology, University of Michigan), Michelle L. Hastings (Department of Pharmacology, University of Michigan), Rachel O. Niederer (Department of Biological Chemistry, University of Michigan)
Abstract:
Gene expression is controlled through many highly specialized processes including splicing and translation regulatory programs. We propose that splicing and translation regulation are interconnected through splicing of the 5′ untranslated region (5′UTR) of mRNA. Sequence features in the 5′UTR of mRNA play a critical role in translational control, including RNA-binding protein motifs, secondary structures, and upstream start codons and open reading frames. Therefore, alternative splicing events in this region may affect translation initiation and protein levels. Intriguingly, 37% of human genes produce RNA that undergoes 5′UTR splicing and 92% of those transcripts exhibit some form of alternative splicing, though the purpose of this complexity is not understood. We hypothesize that splicing in the 5′UTR is a widespread mechanism of translational control. To investigate this idea, we employed a high-throughput ribosome recruitment assay, DART (Direct Analysis of Ribosome Targeting), to quantify how splice isoforms and regulatory regions in the 5′UTR affect translation initiation. We measured ribosome recruitment to approximately 12,000 gene 5′UTR splice isoforms in both neuronal and non-neuronal lysates to capture tissue-specific regulation. Our preliminary data reveal that splice isoforms can have up to 104-fold differences in ribosome recruitment and 75% of genes tested have 5′UTR isoforms capable of driving at least a 2-fold change in ribosome recruitment. To further dissect these effects, we tested systematic scanning deletions across gene 5’UTRs to identify control elements and potential protein interactors underlying these differences. Luciferase reporter assays validate these findings. Understanding the role of introns and alternative splicing in the 5′UTR of mRNA will lead to a better understanding of the basic mechanisms of translation and will reveal potential regulatory sequences that can be targeted for therapeutic modulation of gene expression.
Keywords: mRNA untranslated region, alternative splicing, translational control