Genomic DNA is constantly challenged by DNA damage either spontaneously induced during cellular metabolism or generated by exogenous DNA damaging agents. During DNA replication, DNA lesions can cause the stalling or collapse of replication forks. Fork collapse results in the formation of DNA double-strand breaks (DSBs). MCM8 and MCM9 (MCM8-9) form a helicase complex that promotes the repair of DSBs by homologous recombination. We recently identified MCM8IP as a novel interactor of MCM8-9 that maintains genomic integrity after replication stress. In particular, we showed that MCM8IP promotes DSB repair by homologous recombination, facilitates the restart of replication forks arrested by DNA lesions and protects cells from DNA damage generated by replication stress-inducing agents. Despite these important preliminary findings, the precise mechanisms of action exhibited by MCM8IP, MCM8 and MCM9 during DNA recombination and replication remain to be elucidated. MCM8 or MCM9 have been reported to act as tumor suppressors and recent cancer genomic analyses have evidenced mutations in MCM8, MCM9 and MCM8IP in multiple cancer types. The goals of this proposal are to define the precise biochemical and cellular activities displayed by the MCM8IP-MCM8-9 complex for suppressing genomic instability and to examine how these activities are affected by mutations in MCM8IP, MCM8 and MCM9 identified in tumors. In particular, we propose 1) to define the biochemical activities and physical interactions exhibited by the MCM8IP-MCM8-9 complex for preserving genomic integrity; 2) to elucidate the mechanisms by which MCM8IP-MCM8-9 promotes DSB repair and ensures replication fork progression in response to DNA damage; 3) to evaluate the contribution of MCM8IP, MCM8 and MCM9 cancer-associated mutations to genomic instability. Our approach will utilize innovative proteomic methods, state-of-the-art genome editing technologies, single-molecule analyses of replication dynamics, electron microscopy and super-resolution imaging. We anticipate that our studies will define the unique mechanisms employed by the MCM8IP-MCM8-9 complex to suppress genomic instability and will provide insights into the potential contribution of MCM8IP, MCM8 and MCM9 cancer- associated mutations to cancer etiology.

Public Health Relevance

Defective repair of DNA lesions causes the accumulation of mutations and genomic rearrangements that predispose to cancer development. MCM8 and MCM9 are tumor suppressor genes that promote DNA repair. Understanding the impact of MCM8 and MCM9 cancer-associated mutations on genomic instability will provide novel and important insights into the molecular events that drive tumorigenesis.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Cancer Etiology Study Section (CE)
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Johnson, Ronald L
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Columbia University (N.Y.)
Schools of Medicine
New York
United States
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Billing, David; Horiguchi, Michiko; Wu-Baer, Foon et al. (2018) The BRCT Domains of the BRCA1 and BARD1 Tumor Suppressors Differentially Regulate Homology-Directed Repair and Stalled Fork Protection. Mol Cell 72:127-139.e8
Billon, Pierre; Bryant, Eric E; Joseph, Sarah A et al. (2017) CRISPR-Mediated Base Editing Enables Efficient Disruption of Eukaryotic Genes through Induction of STOP Codons. Mol Cell 67:1068-1079.e4
Kolinjivadi, Arun Mouli; Sannino, Vincenzo; De Antoni, Anna et al. (2017) Smarcal1-Mediated Fork Reversal Triggers Mre11-Dependent Degradation of Nascent DNA in the Absence of Brca2 and Stable Rad51 Nucleofilaments. Mol Cell 67:867-881.e7
Vujanovic, Marko; Krietsch, Jana; Raso, Maria Chiara et al. (2017) Replication Fork Slowing and Reversal upon DNA Damage Require PCNA Polyubiquitination and ZRANB3 DNA Translocase Activity. Mol Cell 67:882-890.e5
Taglialatela, Angelo; Alvarez, Silvia; Leuzzi, Giuseppe et al. (2017) Restoration of Replication Fork Stability in BRCA1- and BRCA2-Deficient Cells by Inactivation of SNF2-Family Fork Remodelers. Mol Cell 68:414-430.e8