title: Bloom syndrome complex promotes FANCM recruitment to stalled replication forks and facilitates both repair and traverse of DNA interstrand crosslinks.
abstract: The recruitment of FANCM, a conserved DNA translocase and key component of several DNA repair protein complexes, to replication forks stalled by DNA interstrand crosslinks (ICLs) is a step upstream of the Fanconi anemia (FA) repair and replication traverse pathways of ICLs. However, detection of the FANCM recruitment has been technically challenging so that its mechanism remains exclusive. Here, we successfully observed recruitment of FANCM at stalled forks using a newly developed protocol. We report that the FANCM recruitment depends upon its intrinsic DNA translocase activity, and its DNA-binding partner FAAP24. Moreover, it is dependent on the replication checkpoint kinase, ATR; but is independent of the FA core and FANCD2-FANCI complexes, two essential components of the FA pathway, indicating that the FANCM recruitment occurs downstream of ATR but upstream of the FA pathway. Interestingly, the recruitment of FANCM requires its direct interaction with Bloom syndrome complex composed of BLM helicase, Topoisomerase 3α, RMI1 and RMI2; as well as the helicase activity of BLM. We further show that the FANCM-BLM complex interaction is critical for replication stress-induced FANCM hyperphosphorylation, for normal activation of the FA pathway in response to ICLs, and for efficient traverse of ICLs by the replication machinery. Epistasis studies demonstrate that FANCM and BLM work in the same pathway to promote replication traverse of ICLs. We conclude that FANCM and BLM complex work together at stalled forks to promote both FA repair and replication traverse pathways of ICLs.
authors.affiliation: Lab of Genetics, National Institute on Aging, National Institute of Health , Baltimore, MD, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Ling
authors.affiliation: Lab of Molecular Gerontology, National Institute on Aging, National Institute of Health , Baltimore, MD, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.affiliation: Lab of Genetics, National Institute on Aging, National Institute of Health , Baltimore, MD, USA.
authors.forename: Zhijiang
authors.initials: Z
authors.lastname: Yan
authors.affiliation: Lab of Genetics, National Institute on Aging, National Institute of Health , Baltimore, MD, USA.
authors.forename: Yongjiang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University , Kyoto, Japan.
authors.forename: Mioko
authors.initials: M
authors.lastname: Ohzeki
authors.affiliation: Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University , Kyoto, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Ishiai
authors.affiliation: Lab of Genetics, National Institute on Aging, National Institute of Health , Baltimore, MD, USA.
authors.forename: Dongyi
authors.initials: D
authors.lastname: Xu
authors.affiliation: Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University , Kyoto, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Takata
authors.affiliation: Lab of Molecular Gerontology, National Institute on Aging, National Institute of Health , Baltimore, MD, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Seidman
authors.affiliation: Lab of Genetics, National Institute on Aging, National Institute of Health , Baltimore, MD, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Wang
keywords: BLM; Bloom syndrome; FANCM; Fanconi anemia; RMI2; interstrand crosslinks; replication