Hedieh Hashemi, University of British Columbia

Hedieh Hashemi (1), Carolina Camargo (1), Selena M. Sagan (1) 1. Department of Microbiology and Immunology, University of British Columbia

Discovering & Evolving

The recent development of mRNA-based vaccines has highlighted the potential for mRNA medicines for a variety of clinical applications, including cancer, infectious and genetic diseases. The production of mRNA medicines involves simple manufacturing infrastructure, allowing rapid development of mRNA-based therapeutics. However, the stability of mRNA inside the cell remains a key limitation, as rapid mRNA decay can reduce overall protein output and therapeutic potency. While current mRNA vaccines typically use stable 5´ and 3´ UTRs and terminal poly(A)-tails, further strategies to prevent mRNA decay have not been explored comprehensively. Fascinatingly, many viral RNAs and some cellular mRNAs have evolved novel strategies to enhance their stability, such as modified or internal poly(A)-tails and/or non-canonical 3´ termini, which inhibit 3´exoribonuclease decay. As such, the goal of the present study is to identify and validate alternative tailing strategies from viral and cellular mRNAs that provide improvements in mRNA stability for the development of more potent mRNA medicines. To do so, we have created a nanoluciferase reporter RNA system that allows us to measure both the translational output and stability of 3´-modified mRNAs, using luciferase assay and RT-qPCR analyses. Thus far, our results suggest that short terminal extensions and mixed poly(A)-tails provide a modest enhancement in mRNA stability, while terminal stem-loop structures have not provided significant stabilization to date. This study helps highlight the design features that can improve mRNA stability, and will allow us to apply the lessons learned from viral RNAs in the development of more potent mRNA medicines.