Justin Klassen, University of Saskatchewan

Justin Klassen, Juveriya Khan, Valeria Martinez, Anil Kumar V Ansalem

Fighting & Responding

Type I Interferons (IFN-I) are cytokines that induce an antiviral state in both infected cells and uninfected bystander cells by inducing the expression a set of genes that interfere with various stages of the viral replication cycle. The production of IFN-I's is a critical component of the innate immune system and a potent defense against viral infections. Recent efforts to explore non-canonical open reading frames (ORFs) translated in human cells have uncovered thousands of small ORFs (smORF's) encoding functional "microproteins" that are usually less than 100 amino acids in length. Several microproteins were shown to be both functional and required for cell survival, although their annotation and our understanding of their functions are still developing. We hypothesize that microproteins modulate IFN-I signaling pathway and can significantly impact the strength of the IFN-I response. We used lentiviral vectors to ectopically overexpress microprotein genes in mammalian cells and assessed the strength of the IFN-I response by measuring the induction of interferon stimulated genes (ISG's) by qRT-PCR. We identified microproteins encoded by the long non-coding RNA NNT-AS1 and by upstream ORFs in the PNRC2 and PTP4A2 mRNAs as significant upregulators of interferon stimulated genes without impacting cell viability. We are currently examining the function of these proteins and the precise step in the IFN-I pathway targeted by them. Identifying microprotein regulators of IFN-I pathway may reveal novel therapeutic targets for viral infections or immune disorders resulting from dysregulated IFN signaling.