Genomic instability is a threat to cell survival and a major factor that drives tumorigenesis. During DNA replication, cells are particularly vulnerable to accumulate genomic instability as replication forks are prone to stall or collapse when encountering replication blocks or damaged DNA templates. To properly replicate the genome, cells rely on the replication checkpoint (RC), an evolutionary conserved signaling pathway that is constantly monitoring the integrity of DNA replication forks. Based on studies with clinical specimens, the RC has been proposed to constitute an early barrier against the progression of a number of cancers, including carcinomas of the lung, breast and colon. The phosphatidyl-inositol-3-kinase-like kinase ATR plays pivotal roles in the RC. In response to replication stress, ATR is rapidly activated at sites of damaged forks to initiate an elaborate signaling network that promotes fork stabilization and repair. Despite the importance, how ATR regulates the repair of replication-induced DNA lesions is not well understood. Important insights were revealed by our recent work in S. cerevisiae showing that Mec1 (yeast ATR) mediates the association of the replication factor Dpb11 (ortholog of human TopBP1) with Slx4, a scaffold protein that coordinates the action of DNA repair factors. While our work places Dpb11 and Slx4 at the heart of RC-mediated fork repair, how these proteins coordinate the action of repair pathways at damaged forks remains a wide open question. Furthermore, as the mammalian ortholog of Slx4 was just recently identified, how this highly conserved scaffold links RC-signaling to repair pathways emerges as a fundamental problem with implications for understanding genome maintenance and cancer. With the long-term goal of elucidating how RC-signaling maintains fork integrity, in Aim 1 we use yeast genetics as a powerful tool to define how the Mec1-Slx4-Dpb11 axis of RC-signaling controls repair pathways in response to replication blocks.
In Aim 2, we use a new Slx4 gene-targeted mouse model to identify both conserved and potentially novel roles for mammalian Slx4 in repair pathways that prevent replication-induced genomic instability. We anticipate that these studies will establish Slx4 as a key RC-effector for replication fork repair in yeast and mammals.
In Aim 3 we determine how Dpb11 controls the use of Slx4 and other repair effectors for lesion-specific DNA repair, including the repair of replication-induced double stranded breaks. The results will delineate how Slx4 functions in the RC and will unmask previously unappreciated roles for Dpb11 in repair pathways. Taken together, we expect that the work being proposed here will significantly enhance our understanding of how cells respond to replication stress. Given the direct relationship of RC-signaling with cancer, and the wide-spread use of replication stress as a strategy for cancer therapy, we expect our work to have broad implications for human health.

Public Health Relevance

Our research will contribute to a better understanding of how cancer is initiated. The results could lead to more efficient strategies for cancer management by providing rationale for the development of highly specific drugs.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM097272-05
Application #
8917254
Study Section
Cellular Signaling and Regulatory Systems Study Section (CSRS)
Program Officer
Reddy, Michael K
Project Start
2011-09-01
Project End
2016-08-31
Budget Start
2015-09-01
Budget End
2016-08-31
Support Year
5
Fiscal Year
2015
Total Cost
$227,121
Indirect Cost
$77,121
Name
Cornell University
Department
Type
Organized Research Units
DUNS #
872612445
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Bastos de Oliveira, Francisco M; Kim, Dongsung; Lanz, Michael et al. (2018) Quantitative Analysis of DNA Damage Signaling Responses to Chemical and Genetic Perturbations. Methods Mol Biol 1672:645-660
Kim, Dongsung; Liu, Yi; Oberly, Susannah et al. (2018) ATR-mediated proteome remodeling is a major determinant of homologous recombination capacity in cancer cells. Nucleic Acids Res 46:8311-8325
Lanz, Michael Charles; Oberly, Susannah; Sanford, Ethan James et al. (2018) Separable roles for Mec1/ATR in genome maintenance, DNA replication, and checkpoint signaling. Genes Dev 32:822-835
Cussiol, José R; Dibitetto, Diego; Pellicioli, Achille et al. (2017) Slx4 scaffolding in homologous recombination and checkpoint control: lessons from yeast. Chromosoma 126:45-58
Liu, Yi; Cussiol, José Renato; Dibitetto, Diego et al. (2017) TOPBP1Dpb11 plays a conserved role in homologous recombination DNA repair through the coordinated recruitment of 53BP1Rad9. J Cell Biol 216:623-639
Dibitetto, Diego; Ferrari, Matteo; Rawal, Chetan C et al. (2016) Slx4 and Rtt107 control checkpoint signalling and DNA resection at double-strand breaks. Nucleic Acids Res 44:669-82
Liu, Yi; Smolka, Marcus B (2016) TOPBP1 takes RADical command in recombinational DNA repair. J Cell Biol 212:263-6
Bai, Gongshi; Smolka, Marcus B; Schimenti, John C (2016) Chronic DNA Replication Stress Reduces Replicative Lifespan of Cells by TRP53-Dependent, microRNA-Assisted MCM2-7 Downregulation. PLoS Genet 12:e1005787
Zhou, Xiaolai; Sun, Lirong; Bastos de Oliveira, Francisco et al. (2015) Prosaposin facilitates sortilin-independent lysosomal trafficking of progranulin. J Cell Biol 210:991-1002
Balint, Attila; Kim, TaeHyung; Gallo, David et al. (2015) Assembly of Slx4 signaling complexes behind DNA replication forks. EMBO J 34:2182-97

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