Abstract 2115: REV1, DNA polymerase ≤ and the fanconi anemia proteins FANCD2 and FANCI function together during repair

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Abstract Fanconi anemia (FA) is a chromosomal instability disorder characterized by bone marrow failure, congenital abnormalities and increased incidence of malignancies. Cells derived from FA patients exhibit cellular hypersensitivity to interstrand crosslink (ICL)-inducing agents, including mitomycin C (MMC) and cisplatin. ICLs are sensed and repaired by a complex process which involves multiple DNA repair proteins including the FA factors as well as proteins that function in nucleotide excision repair, translesion DNA synthesis and homologous recombination (HR). REV1 (a Y family translesion DNA polymerase) and DNA Polymerase ≤ (Polα, comprised of the catalytic REV3 protein and REV7 accessory subunit) play important roles in performing DNA replication across blocking lesions. Previous studies have demonstrated an epistatic relationship between Polα and genes encoding proteins comprising the Fanconi anemia core complex with regards to resistance to ICLs. Additionally, REV1, Polα, and the FANCD2/FANCI heterodimer have each been shown individually to be involved in promoting HR repair, although the reasons for their involvement remain unclear. Here, we show that human REV1 and REV3 exhibit an epistatic relationship with FANCD2 and FANCI in homology-directed repair of a defined DNA double-stranded break and cellular resistance to ICLs created by MMC. We also demonstrate that MMC-induced chromosomal anomalies are increased in REV1 or REV3-depleted cells and FANCD2 depletion does not further exacerbate this phenotype. Additionally, we demonstrate for the first time that full length human REV1 and REV3 interact with FANCD2 and FANCI in vivo as detected by co-immunoprecipitation studies. We therefore propose a model where replication fork stalling during HR repair DNA synthesis is resolved through Polα-dependent translesion DNA synthesis which is regulated by the Fanconi anemia pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2115. doi:1538-7445.AM2012-2115