UBC Theses and Dissertations
Non-canonical roles of the nucleoporin Nup153 in influenza A virus infection, intracellular transport, and cellular architecture Acevedo, Maria
The nuclear pore complex (NPC) mediates the bidirectional transport of macromolecules across the nuclear envelope. Nup153 is a nucleoporin localized in the nuclear side of the NPC that was identified as a host factor required for influenza A virus (IAV) infection in two genome-wide RNA interference (RNAi) screens (Hao et al., 2008, Nature 454:890-893; König et al., 2010, Nature 463:813-817). Since IAV uses the NPC at different steps of its infective cycle, the hypothesis that Nup153 could be required for the nuclear transport of IAV mRNAs, viral proteins, and viral ribonucleoproteins (vRNPs) was tested. The main objective of this thesis was to investigate the role of Nup153 during IAV infection. This was studied by following the progression of IAV infection in HeLa cells where Nup153 was knocked down (KD) with siRNA. These cells produced less infectious particles than control cells; however, no significant changes were detected in the nuclear import of vRNPs and the influenza nucleoprotein. To explain why Nup153 KD cells produced less infectious viral particles, the sub-cellular localization of the viral proteins nucleoprotein, matrix 1, and hemagglutinin were analyzed. The results indicate deficiency in the cytoplasmic trafficking of these proteins. To understand the observed defects in IAV infected Nup153 KD cells, the cellular changes associated with transient RNAi depletion of Nup153 were studied. Strikingly, defects in the intracellular traffic of other host cell proteins and in the distribution of endocytic organelles and the cytoskeleton were found. In addition, pronounced blebbing of the plasma membrane and alterations of the nuclear and cellular architecture were observed. This is the first time that a systematic characterization of the plethora of cellular defects resulting from Nup153 RNAi has been conducted. Collectively, the results suggest that Nup153 depletion has an effect during the late stages of IAV infection and leads to defective vRNPs and/or the inadequate assembly or budding of progeny viral particles. This work adds to the cumulative evidence that nucleoporins have non-canonical roles, including roles during viral infection, and opens the possibility of considering nucleoporins as important factors for the development of future antiviral treatments.
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