Poster abstracts
Poster number 36 submitted by Paul Russell
Determining how open reading frame length regulates translation re-initiation and mRNA stability
Paul Russell (Cellular, Molecular, and Biochemical Sciences Program, Department of Biological Chemistry and Pharmacology, Center for RNA Biology, The Ohio State University, Columbus, OH 43210), Michael G. Kearse (Cellular, Molecular, and Biochemical Sciences Program, Department of Biological Chemistry and Pharmacology, Center for RNA Biology, The Ohio State University, Columbus, OH 43210)
Abstract:
Approximately 50% of all mammalian transcripts contain major regulatory elements known as upstream open reading frames (uORFs). Since uORFs exist in the 5’ untranslated region (UTR) and are very commonly encoded by an AUG start codon, they directly compete against the downstream primary open reading frame (ORF) for the scanning ribosome. Previous studies have shown that uORFs do not completely inhibit translation of the functional gene product as ribosomes, after translating uORFs, can re-initiate. Additionally, uORFs have been implicated in regulating the stability of the mRNA. Despite these observations in vitro and in vivo, the factors that drive these regulatory mechanisms remain poorly defined. Here we use re-initiation specific luciferase reporters with different length uORFs in rabbit reticulocyte lysate and in HeLa cells to assess uORF length dependency on re-initiation and mRNA stability. Our data shows re-initiation is more favorable after translating short uORFs and that mRNA stability is decreased with increasing uORF length. These findings suggest that uORF length influences alterations in the composition of ribosomal-bound proteins and that retention of specific initiation factors is essential for mediating re-initiation and mRNA stability. Future studies will need to be performed to determine the identification of the critical factors.
Keywords: translational control, uORF, ribosome