The goal of this proposal is to understand the role of phosphorylation of the middle subunit (RPA2) of the heterotrimeric human replication protein A (RPA;the eukaryotic single-stranded DNA-binding protein). Recent data arising from my laboratory indicates that RPA2 phosphorylation provides an important regulatory control over the cellular DNA damage response. Using a combination of approaches, we will characterize the role of RPA phosphorylation in vivo and in vitro. Specifically, we will examine the molecular basis by which hypo-phosphorylated RPA selectively associates with the replication fork, by characterization of its interaction with the MCM complex. The association of RPA with MCM will be examined, both in solution, and on synthetic DNA replication fork structures. Second, using a RPA2 replacement strategy, we will examine the effect of RPA2 phosphorylation site mutation on the loading of the recombination mediator BRCA2 and homologous recombination factors to sites of DNA replication stress and DNA damage. The effects of RPA2 mutation on BRCA2 loading in vitro and on HR rates in vivo will be determined. Third, we have found that the synergistic activity of these kinases towards RPA2 under genotoxic stress conditions modulate subsequent phosphorylation events both on the same RPA molecule (the cis pathway) and on different RPA molecules (the trans pathway). By exploring the cis pathway, we will test the hypothesis that S33 phosphorylation facilitates recruitment of cyclin A-Cdk2 to the RPA substrate in vitro. To examine the trans reaction, we will examine the effect of RPA phosphorylation on ATR dynamics in vivo. The data generated will provide insights into how cell cycle position causes DNA lesions to be channeled into different DNA repair pathways.

Public Health Relevance

We will understand the functional significance of RPA phosphorylation in the cellular response to DNA damage. The results from this work could lead to new threraputics to treat human cancers

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Molecular Genetics A Study Section (MGA)
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Hagan, Ann A
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New York University
Schools of Medicine
New York
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Murphy, Anar K; Fitzgerald, Michael; Ro, Teresa et al. (2014) Phosphorylated RPA recruits PALB2 to stalled DNA replication forks to facilitate fork recovery. J Cell Biol 206:493-507
Bhatt, Purvi; d'Avout, Claire; Kane, Naomi S et al. (2012) Specific domains of nucleolin interact with Hdm2 and antagonize Hdm2-mediated p53 ubiquitination. FEBS J 279:370-83
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Vassin, Vitaly M; Anantha, Rachel William; Sokolova, Elena et al. (2009) Human RPA phosphorylation by ATR stimulates DNA synthesis and prevents ssDNA accumulation during DNA-replication stress. J Cell Sci 122:4070-80
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