Regulatory mechanisms that define precise DNA replication origin utilization Public Deposited

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Last Modified
  • March 21, 2019
Creator
  • Dorn, Elizabeth S.
    • Affiliation: School of Medicine, Department of Biochemistry and Biophysics
Abstract
  • Each time a cell divides its DNA must be replicated so that a complete genome is passed on to each daughter cell. To duplicate the entire genome within a single S phase, eukaryotic cells initiate replication at multiple sites, termed origins. All potential origins require recruitment and assembly of a pre-replication complex (preRC). ORC, Cdc6, and Cdt1 are coordinated to facilitate loading of the final preRC component, the MCM complex. Once MCM is loaded, an origin is prepared or "licensed" for replication. There are many mutually reinforcing mechanisms that regulate replication to ensure that an exact copy of DNA is created, and that genome instability is avoided. All origins share three regulatory stages: origin licensing, initiation, and inhibition of preRC assembly. Nevertheless, origins are not utilized identically; they fire asynchronously in S phase, are utilized with varying efficiencies, and are differentially prone to re-firing. This dissertation investigates the mechanisms that define precise replication at individual origins. In this work, a novel method to detect re-replication at the single molecule level was developed and this method revealed that a portion of origins in untransformed cells undergo re-replication. Furthermore, the baseline level of re-replication is increased in cancer cells. These studies also implicate the chromatin environment, most extensively H3K4me, as a critical factor in regulating origin activity. These observations provide insight into the replication program and will be valuable in understanding how the cell maintains a stable genome to avoid oncogenesis.
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  • In Copyright
Note
  • " ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biochemistry & Biophysics."
Advisor
  • Cook, Jean
Degree granting institution
  • University of North Carolina at Chapel Hill
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Place of publication
  • Chapel Hill, NC
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  • Open access
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