Date Approved
8-2022
Document Type
Dissertation
Degree Name
PhD in Cell and Molecular Biology
Department
Molecular Biology
College
Graduate School of Biomedical Sciences, Virtua Health College of Medicine and Life Sciences of Rowan University
Sponsor
NIH grant R03CA246009
First Advisor
Dimitri Pestov, PhD
Committee Member 1
Renee Demarest, PhD
Committee Member 2
Gary Goldberg, PhD
Committee Member 3
Venkataswar Venkataraman, PhD
Committee Member 4
Natalie Minkovsky, PhD
Subject(s)
Protein Biosynthesis, Ribosomal, RNA, Ribosomal, Oxidative Stress, Cell Nucleolus, Reactive Oxygen Species, Transcription, Genetic
Disciplines
Cell and Developmental Biology | Cell Biology | Genetics and Genomics | Life Sciences | Molecular Biology | Molecular Genetics
Abstract
Ribosomes are responsible for translating every protein in the cell and are essential in all domains of life. Ribosome biosynthesis (RB) takes place in the nucleolus and is an intricate hierarchical process involving over 200 factors, including ribosomal proteins, ribosomal RNA (rRNA), and trans-acting ribosome biogenesis factors (RBFs). Inhibiting RB can disrupt nucleolar integrity, causing ribosomal- and nucleolar-factors to delocalize. This can stabilize the transcription factor p53, which is normally degraded rapidly, ultimately causing cell cycle arrest or apoptosis, through a mechanism termed the nucleolar stress response (NSR). This thesis explores the effects of inhibiting RB post rRNA transcription and discusses its role in human diseases. Using a dominate-negative RBF mutant, this work demonstrates that targeting RB after rRNA transcription is a viable approach to increase the efficacy of the chemotherapeutic agent camptothecin (CPT) against p53-negative cancers. Importantly, this model of targeting RB is independent of DNA damage, unlike currently developed molecular inhibitors of RB.
In addition to exploring the combinational effects of CPT and post-transcriptional inhibition of RB, this thesis also investigated the impact of oxidative stress on nucleolar function. The onset of several diseases, including cancer and neurodegeneration, has been linked to both oxidative stress and nucleolar stress. However, very little has been reported on the effects of oxidative stress on the nucleolus. Using a newly generated nucleolar-specific redox sensor, this work demonstrates an increase in the oxidative state of the nucleolus and oxidative damage in nucleolar RNA when cells are challenged with a variety of chemical pro-oxidants. Additionally, rRNA processing and ribosomal subunit synthesis is inhibited by pro-oxidants. This phenotype was exacerbated when the antioxidant glutathione was depleted. The significance of this work demonstrates the susceptibility of the nucleolus to oxidative stress.
Recommended Citation
Sapio, Russell T., "The Effects Of Stress On The Mammalian Nucleolus And Ribosome Synthesis" (2022). Graduate School of Biomedical Sciences Theses and Dissertations. 42.
https://rdw.rowan.edu/gsbs_etd/42
