Date of Award
8-23-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Cell Biology, Neurobiology and Anatomy
First Advisor
Edward Campbell
Abstract
The early stages of the HIV-1 lifecycle include the trafficking of the viral capsid into the nucleus of infected cells. The viral capsid, which encloses the viral genome and accessory proteins required for reverse transcription (RT) and integration, traffics towards the nucleus and enters through the nuclear pore complex (NPC). This process is mediated through interactions between the virus and several host proteins, including cleavage and polyadenylation specificity factor 6 (CPSF6). CPSF6 is an early HIV-1 host factor which assists HIV-1 nuclear localization and post-entry integration targeting. CPSF6 contains a function nuclear localization signal (NLS), and as a result, is strongly localized into the nucleus of cells. Prior work investigating NLSs has identified that the NLS tagged on a protein can significantly alter the nuclear import pathway utilized, which refers to the cellular factors required to mediate nuclear localization. Additionally, in the context of HIV-1 infection, HIV-1 capsid mutants have been found to utilize distinct nuclear pathways. Here, we used a CPSF6 truncation mutant lacking the functional NLS found at the C-terminal end, CPSF6-358, and appended heterologous NLSs to rescue nuclear localization. We show that some, but not all, NLSs drive CPSF6-358 into the nucleus. Interestingly, we found that during HIV-1 infection, some of the nuclear localized CPSF6-NLS chimeras did not support HIV-1 infection. In these conditions, we found that HIV-1 still enters the nucleus but fails to traffic to nuclear speckle-associated domains (SPADs). Additionally, we show that HIV-1 fails to efficiently integrate in these cell lines, with decreased integration frequencies and altered integration profiles. Collectively, this study highlights the importance of the NLS in CPSF6 in dictating the NPC it associates with and its effect on HIV-1 infection. Additionally, our results demonstrate that the NLS of CPSF6 facilitates steps of HIV-1 infection subsequent to nuclear import and additionally identify the ability of canonical NLS sequences to influence cargo localization in the nucleus following nuclear import.
Recommended Citation
Rohlfes, Nick, "CPSF6's Nuclear Localization Signal Mediates HIV-1 Intranuclear Events Following Nuclear Import" (2024). Dissertations. 4114.
https://ecommons.luc.edu/luc_diss/4114
