The overall goal of this project is to understand how telomere proteins, DNA damage response factors and replication factors cooperate to replicate and protect telomeres. Telomeres exist as protective DNA-protein complexes that are essential to maintain genome stability. Failure of the complex to reform after telomere replication leads to chromosome fusions, aneuploidy and cell death;defects that lead to human disease. Replication of a telomere involves a number of steps beyond simple duplication of the double-stranded telomeric DNA. These include processing of the DNA to generate an overhang on the 3'G-rich strand and G-strand extension by telomerase. During replication, the telomere is transiently recognized as DNA damage and it recruits proteins such as ATM, ATR, MRN and the Rad9/Rad1/Hus1 checkpoint clamp. These damage response factors seem to play an important, but poorly understood role in telomere replication. Likewise, while the steps involved in telomere replication are well established, the mechanistic details are far from clear. The proposed research addresses how the Pot1/Tpp1 heterodimer, the replication protein A (RPA) and the Rad9/Rad/1/Hus1 clamp interface with each other and with telomerase to ensure that a functional telomere is reassembled after DNA replication. The role of ATR signaling in this process is also explored. During the previous grant period we made a conditional chicken DT40 cell line (Er-Pot1) and found that a key function of the telomere protein Pot1 is to prevent the telomere from activating a DNA damage checkpoint during late S/G2 of the cell cycle. We also showed that Pot1 is required to restrict telomere growth. We will now build on these findings by using a mix of in vivo and in vitro approaches to: (1) Dissect the contribution of Pot1/Tpp1 dimerization, shelterin binding and Tpp1/telomerase interactions to telomere protection and length regulation. (2) Explore RPA function at vertebrate telomeres. (3) Determine the role of the Rad9/Rad1/Hus1 clamp and ATR in telomere maintenance. The common theme is how the presence of these three single-strand binding proteins at the G-overhang coordinates and regulates telomere replication. Telomeres are the protective DNA-protein caps at chromosomes ends that prevent chromosome fusions and degradation of the terminal DNA sequence. When a chromosome is duplicated, it takes a series of specialized steps beyond simple DNA replication to ensure that a functional, fully protected telomere is regenerated. The proposed research seeks to understand how specialized telomere proteins cooperate with DNA repair factors and replication proteins to ensure that these steps occur correctly.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Molecular Genetics C Study Section (MGC)
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Carter, Anthony D
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University of Cincinnati
Schools of Medicine
United States
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Feng, Xuyang; Hsu, Shih-Jui; Bhattacharjee, Anukana et al. (2018) CTC1-STN1 terminates telomerase while STN1-TEN1 enables C-strand synthesis during telomere replication in colon cancer cells. Nat Commun 9:2827
Wang, Feng; Stewart, Jason; Price, Carolyn M (2014) Human CST abundance determines recovery from diverse forms of DNA damage and replication stress. Cell Cycle 13:3488-98
Kasbek, Christopher; Wang, Feng; Price, Carolyn M (2013) Human TEN1 maintains telomere integrity and functions in genome-wide replication restart. J Biol Chem 288:30139-50
Wang, Feng; Stewart, Jason A; Kasbek, Christopher et al. (2012) Human CST has independent functions during telomere duplex replication and C-strand fill-in. Cell Rep 2:1096-103
Stewart, Jason A; Chaiken, Mary F; Wang, Feng et al. (2012) Maintaining the end: roles of telomere proteins in end-protection, telomere replication and length regulation. Mutat Res 730:12-9
Stewart, Jason A; Wang, Feng; Chaiken, Mary F et al. (2012) Human CST promotes telomere duplex replication and general replication restart after fork stalling. EMBO J 31:3537-49
Price, Carolyn M (2011) Telomere flip-flop: an unfolding passage to senescence. EMBO Rep 13:5-6
Baumann, Peter; Price, Carolyn (2010) Pot1 and telomere maintenance. FEBS Lett 584:3779-84
Price, Carolyn M; Boltz, Kara A; Chaiken, Mary F et al. (2010) Evolution of CST function in telomere maintenance. Cell Cycle 9:3157-65
Linger, Benjamin R; Price, Carolyn M (2009) Conservation of telomere protein complexes: shuffling through evolution. Crit Rev Biochem Mol Biol 44:434-46

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