Advisory Committee Chair
Louise T Chow
Advisory Committee Members
Thomas R Broker
Date of Award
Degree Name by School
Doctor of Philosophy (PhD) Heersink School of Medicine
Human papillomavirus are small DNA tumor viruses. The viral genome is a small circular double stranded DNA that replicates autonomously as an extrachromosomal plasmid. Occasionally infections by the high risk HPV viruses can lead to DNA integration and progression to cancer. How the HPV DNA is maintained and becomes established in the dividing host cells is not well understood. Additionally, as a double-stranded DNA virus it is likely that double-stranded DNA breaks in the viral genome, either from replication or random damage, will trigger a DNA repair response from the host cell. Such responses have been alternatively reported to be detrimental or helpful to viral DNA amplification for various DNA viruses. Interactions between HPV and the host cell’s double-stranded DNA break repair machinery have not been examined. This dissertation investigates these two subjects. The viral E2 protein is critical for viral DNA maintenance during cellular replication. The E2 proteins of HPV-11, 16 and -18 each localizes to the mitotic spindles. The first part of this research was to identify the specific regions in the carboxyl domain of HPV-11 E2 (E2C) necessary for this function. We found that a peptide of 23 residues in length which was highly conserved in HPV-11, HPV-16, 18, iii and BPV-4 E2C. Mutations or deletions of this region rendered E2C unable to localize to the mitotic spindles. In BPV-1 E2C this region is highly divergent and we observed no localization of BPV-1 E2C to the spindles. We suggest this region is necessary and sufficient for the HPV-11 E2 protein’s interactions with the spindle fibers. The second subject of this research investigates interactions between viral replication and the cellular double-stranded DNA break repair complex, MRN. Other viruses have close interactions between components of the MRN complex and viral replication centers. We show that, during active viral replication, both Mre11 and Nbs1, two components of the MRN complex, relocalized to the replication centers. This relocalization is not necessary for efficient viral replication nor does it activate downstream mediators of DNA repair, most notably ATM. It is unclear as to what function Mre11 might play at the replication center.
Dao, Luan D., "Human Papillomavirus: Segregation and Replication" (2008). All ETDs from UAB. 256.