Translation control is crucial during virus-host interaction, in which the host relies on the translation machinery to mount an antiviral response or induce the inflammation response to reduce virus spread, while the virus aims to take control of this system to thwart the host defense while producing viral progeny. The field of oncolytic virus (OV) therapy relies on replicating, engineered viruses that preferentially infect tumor cells to induce direct oncolysis or promote an antitumor immune response. Despite the importance of translation control in virus-host interaction, not much has been described on the interaction at the translation level between OV and cancer cells. I propose that this knowledge gap could reveal significant improvements in OV efficacy in treating cancer. In my first study, I set out to characterize the translatome of an infection-resistant breast cancer cell line infected by three clinically advanced OVs to identify residual antiviral activity in cancer cells regulated by translation control. I found the inositol phosphatase Inpp5e to be a novel antiviral gene that is translationally induced during infection via a transcript variant shift. Mechanistically, I showed that the majority of Inpp5e transcripts in uninfected cells contain a long 5’ UTR that harbor four translationally inhibitory upstream reading frames (uORF). Yet, OV infection induced the expression of a shorter 5’ UTR with a spliced intron that removes three uORFs, derepressing the translation of Inpp5e mRNA. CRISPR-Cas9 knockout of Inpp5e also enhanced the infectivity of oncolytic HSV1 and VSV. My study suggests the existence of a class of translationally regulated antiviral genes in cancer cells. In my second study, I sought to adapt the translation of transgenes to the unique translation condition imposed by the infecting virus via the incorporation of a viral 5’UTR. I identified HSV1 5’UTRs by locating the transcription start site of most HSV1 genes using RNA-seq data, then determined the 5’UTR of US11 as a potent translation enhancer during HSV1 infection. Incorporation of this 5’UTR into the transgene expression cassette inserted into the HSV1 genome enhanced transgene expression significantly at the translation level. In my third study, I set out to explore the mechanism of miR-223 mediated inflammation inhibition. miR-223 is a protective miRNA in the context of atherogenesis via suppressing inflammatory signaling. Using transcriptome and translatome profiling (RNA-seq and Ribo-seq), I found that the inhibitory effect of miR-223 on inflammation occurs primarily at the translation level. Overall, my work highlights the importance of translation control in OV-cancer cells interaction, as well as in inflammation-related diseases.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/42410 |
| Date | 14 July 2021 |
| Creators | Hoang, Huy-Dung |
| Contributors | Alain, Tommy |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/pdf |
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