Talk abstracts
Talk on Saturday 11:15-11:30am submitted by Kristen Nedza
Investigating the interactome and functions of the UPF3 paralogs in Nonsense Mediated Decay
Rene Arvola (Department of Molecular Genetics, The Ohio State University; Center for RNA Biology, The Ohio State University), Kristen Nedza (Department of Molecular Genetics, The Ohio State University; Center for RNA Biology, The Ohio State University), Guramrit Singh (Department of Molecular Genetics, The Ohio State University; Center for RNA Biology, The Ohio State University)
Abstract:
Nonsense Mediated mRNA Decay (NMD) degrades both aberrant transcripts containing Premature Termination Codons (PTCs) and “normal” transcripts with specific features that cause translation termination to resemble premature termination. Regulation by NMD is pervasive and estimated to impact around 10% of the transcriptome. In multicellular organisms, UPF3 is a central NMD factor that engages with the mRNA bound Exon Junction Complex (EJC) and the rest of the NMD machinery and aids in PTC recognition. In mammals, there are two paralogs of UPF3, UPF3A and UPF3B. In mice, Upf3A knockout is embryonic lethal [1], whereas Upf3B knockouts are viable, but exhibit neurodevelopmental defects [2]. Moreover, mutations in UPF3B are linked to various forms of intellectual disability in humans (summarized in [3]). We and others previously found that UPF3A can compensate for UPF3B in NMD, albeit as a weaker activator [4]. To better understand the functions of the human UPF3 paralogs in NMD, we performed immunoprecipitation followed by mass spectrometry from a human colorectal carcinoma cell line (HCT116) to identify proteins associated with UPF3A and UPF3B. In addition to EJC and NMD components, we identified transcriptional regulators and nucleocytoplasmic shuttling factors to be highly enriched in UPF3A and UPF3B immunoprecipitation. Ongoing work includes investigating the role of these nuclear and shuttling factors in UPF3-mediated NMD. Moreover, we aim to determine whether disruption of UPF3 nuclear-cytoplasmic shuttling impacts NMD. Taken together, this work will deepen our understanding of how mRNA decay processes such as NMD can become dysregulated in development and disease.
References:
[1] Shum EY, et al. The Antagonistic Gene Paralogs Upf3a and Upf3b Govern Nonsense-Mediated RNA Decay. Cell. 2016 Apr 7;165(2):382-95.
[2]Huang L, et al. A Upf3b-mutant mouse model with behavioral and neurogenesis defects. Mol Psychiatry. 2018 Aug;23(8):1773-1786.
[3] Deka B, Chandra P, Singh KK. Functional roles of human Up-frameshift suppressor 3 (UPF3) proteins: From nonsense-mediated mRNA decay to neurodevelopmental disorders. Biochimie. 2021 Jan;180:10-22
[4] Yi Z, et al. Mammalian UPF3A and UPF3B can activate nonsense-mediated mRNA decay independently of their exon junction complex binding. EMBO J. 2022 May 16;41(10):e109202.
Keywords: Nonsense Mediated mRNA decay, UPF3