Novel roles of the U2 splicing complex in antiviral defence

Wang, Chenrui (2026) Novel roles of the U2 splicing complex in antiviral defence. MSc(R) thesis, University of Glasgow.

Abstract

Spliceosomes are essential ribonucleoprotein complexes that remove introns from nascent pre-mRNAs. Removal of introns from pre-mRNA produces mature mRNAs that are subsequently translated into proteins.
Although spliceosomes are canonically regarded as nuclear co-transcriptional complexes, emerging evidence suggests that several splicing factors also participate in cytoplasmic antiviral responses. Recent studies revealed numerous interactions between cytoplasmic viral RNAs (vRNAs) and nuclear proteins, including proteins involved in splicing.
Previous study demonstrated that specific nuclear proteins translocate to the cytoplasm during Sindbis virus (SINV) infection, which is a positive-sense RNA virus that replicates in the cytoplasm. Among those relocated proteins, the U2 snRNP complex emerged as a novel antiviral factor with activities that spanned multiple viral species and families.
Three questions motivated this study. Firstly, the triggers of the translocation of U2 snRNP and its associated proteins are unclear. Secondly, the composition of the potential antiviral complex remains unknown. It’s also unclear whether U2snRNP directly binds the viral RNA or requires an adaptor complex. Finally, it remains unknown what signatures in viral RNAs the U2 snRNP recognises. This Master’s project focused on clarifying the non-canonical antiviral roles of U2 snRNP cofactors and defining the viral RNA binding sites of these cofactors.
Throughout this thesis, U2AF1, U2AF2, and SF1 are collectively referred to as the U2AF complex. We hypothesised that the U2AF complex is the upstream adaptor complex facilitating the binding of U2 snRNP to SINV mRNAs. We investigated the anti-SINV roles of the U2AF complex using loss-of-function experiments. We also optimised iCLIP2 for SF3B1, SF1, U2AF2, and AQR to establish libraries for investigating their RNA-binding profiles during SINV infection.
U2AF1 knockdown produced the strongest and most consistent increase in SINV titre, whereas SF1 knockdown showed a similar but non-significant trend and U2AF2 knockdown produced variable effects. iCLIP2 libraries were successfully generated for SF3B1, SF1, U2AF2, and AQR under infected and uninfected conditions and were suitable for sequencing.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Subjects: Q Science > QR Microbiology > QR355 Virology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
• Supervisor's Name: Castello, Professor Alfredo, Kamel, Dr. Wael and Noerenberg, Dr. Marko
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-86226
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 15 Sep 2026 10:44
• Last Modified: 17 Sep 2026 11:33
• Thesis DOI: 10.5525/gla.thesis.86226
• URI: https://theses.gla.ac.uk/id/eprint/86226