FANCM-mediated attenuation of ALT requires its inherent DNA translocase activity and interaction with the BTR complex, but does not require the FA core complex, indicative of FANCM functioning to restrain excessive ALT activity by ameliorating replication stress at telomeres.
This review details our current understanding of FANCM as a facilitator of the cellular functions of caretaker proteins, including FA, Bloom syndrome, and Ataxia telangiectasia and RAD3-related proteins, which collectively ensure the maintenance of chromosome stability during DNA replication.
We uncovered a novel function of Fanconi anemia (FA) protein FANCM in the protection of CFSs that is independent of the FA core complex and the FANCI-FANCD2 complex.
Individuals with FANCM biallelic mutations do not develop Fanconi anemia, but show risk for breast cancer, chemotherapy toxicity and may display chromosome fragility.
Patient-derived cells were genetically complemented upon wild-type FANCM complementary DNA expression.ConclusionLoss-of-function mutations in FANCM cause a cancer predisposition syndrome clinically distinct from bona fide FA.
Here, we demonstrate that FANCM, a component in the Fanconi Anemia pathway, is a novel target of miR146a. miR146a suppressed FANCM expression by directly binding to the 3' untranslated region of the gene. miR146a-induced downregulation of FANCM was associated with inhibition of FANCD2 monoubiquitination, reduced DNA homologous recombination repair and checkpoint response, failed recovery from replication stress, and increased cellular sensitivity to cisplatin.
Proper execution of the FA pathway requires interaction between the FA complementation group M protein (FANCM) and the RecQ-mediated genome instability protein (RMI) complex, and mutations that disrupt FANCM/RMI interactions sensitize cells to DNA crosslinking agents.
However, one histone-fold complex, MHF, associates with Fanconi anemia (FA) protein FANCM to form a branched DNA remodeling complex that senses and repairs stalled replication forks and activates FA DNA damage response network.
Overall, our data suggest that an ATR-FANCM feedback loop is present in the FA and replication stress response pathways and that it is required for both efficient ATR/CHK1 checkpoint activation and FANCM function.
However, genetic inactivation of FANCM in mouse and DT40 cells causes only a partial defect in the FA pathway activation, suggesting the existence of redundant DNA damage sensors.
FANCM (FA complementation group M), and its binding partner, FAAP24, anchor the multisubunit FA core complex to chromatin after DNA damage and may contribute to ICL-specific cellular response.
In this review, we discuss the recent progress in the study of the FA pathway, such as the identification of new FANCM-binding partners and the identification of RAD51C and FAN1 (Fanconi-associated nuclease 1) as new FA pathway-related proteins.
Moreover, a common phenotype of BS and FA cells-an elevated frequency of sister chromatid exchanges-was due to a loss of interaction of the two complexes through FANCM.
This fact and novel data sustaining greater functional relevance of the three genes within the FA pathway prompted us to scrutinize all coding sequences and splicing sites of FANCI, FANCL and FANCM in 95 BRCA1/2-negative index cases from Spanish high-risk breast cancer families.
Moreover, we find that the DNA translocase activity of FANCM, which is dispensable for FA pathway activation, is required for its role in ATR/Chk1 signaling.