Regulation of Viruses Through Internal G-quadruplex Stabilization
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Authors
Zareie, Andrew Roozbeh
Issue Date
2023
Type
Dissertation
Language
Keywords
Coronavirus , G-quadruplex , KSHV , LANA , Methylene Blue , Nucleolin
Alternative Title
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is a gamma-herpesvirus implicated as the causative agent for several malignancies, including Kaposi's sarcoma, primary effusion lymphoma, and certain forms of multicentric Castleman's disease. KSHV remains latently infective in its hosts by anchoring its genome to host chromosomes and judiciously modulating viral protein expression, making it elusive to immune detection. This nuanced expression, implicated in several human malignancies, is primarily orchestrated by the Latency-associated nuclear antigen (LANA), pivotal for viral genome replication and maintenance. LANA's expression is fine-tuned at multiple strata�"transcriptionally and translationally�"with the mRNA's secondary structures playing a crucial role. Among these, G-quadruplexes (G4s) emerge as highly stable and evolutionarily conserved structures, influencing vital cellular processes such as replication and transcription. These G4s liaise with cellular proteins, either bolstering or disrupting these structures, thereby regulating LANA translation. Our previous work highlighted the critical role of G4s within LANA mRNA, underscoring their influence on LANA levels in infected cells. This study elucidates the role of Nucleolin (NCL) in modulating LANA expression via its affinity for the G-quadruplexes in LANA mRNA. This liaison leads to a reduction in LANA protein expression, driven by the sequestering of its mRNA in the nucleus, a phenomenon evidenced by the colocalization of G4-rich mRNA with NCL. Intriguingly, NCL's suppression, achieved through a short hairpin RNA, precipitates a surge in LANA translation, as evidenced by altered LANA mRNA levels in the cytoplasm. Collectively, our findings spotlight the regulatory capability of G-quadruplex-mediated translational control by NCL, presenting potential avenues for therapeutically manipulating KSHV latency.