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Oyama T, Oka H, Mayanagi K, Shirai T, Matoba K, Fujikane R, Ishino Y, Morikawa K. Atomic structures and functional implications of the archaeal RecQ-like helicase Hjm. BMC STRUCTURAL BIOLOGY 2009; 9:2. [PMID: 19159486 PMCID: PMC2636818 DOI: 10.1186/1472-6807-9-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Accepted: 01/22/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Pyrococcus furiosus Hjm (PfuHjm) is a structure-specific DNA helicase that was originally identified by in vitro screening for Holliday junction migration activity. It belongs to helicase superfamily 2, and shares homology with the human DNA polymerase Theta (PolTheta), HEL308, and Drosophila Mus308 proteins, which are involved in DNA repair. Previous biochemical and genetic analyses revealed that PfuHjm preferentially binds to fork-related Y-structured DNAs and unwinds their double-stranded regions, suggesting that this helicase is a functional counterpart of the bacterial RecQ helicase, which is essential for genome maintenance. Elucidation of the DNA unwinding and translocation mechanisms by PfuHjm will require its three-dimensional structure at atomic resolution. RESULTS We determined the crystal structures of PfuHjm, in two apo-states and two nucleotide bound forms, at resolutions of 2.0-2.7 A. The overall structures and the local conformations around the nucleotide binding sites are almost the same, including the side-chain conformations, irrespective of the nucleotide-binding states. The architecture of Hjm was similar to that of Archaeoglobus fulgidus Hel308 complexed with DNA. An Hjm-DNA complex model, constructed by fitting the five domains of Hjm onto the corresponding Hel308 domains, indicated that the interaction of Hjm with DNA is similar to that of Hel308. Notably, sulphate ions bound to Hjm lie on the putative DNA binding surfaces. Electron microscopic analysis of an Hjm-DNA complex revealed substantial flexibility of the double stranded region of DNA, presumably due to particularly weak protein-DNA interactions. Our present structures allowed reasonable homology model building of the helicase region of human PolTheta, indicating the strong conformational conservation between archaea and eukarya. CONCLUSION The detailed comparison between our DNA-free PfuHjm structure and the structure of Hel308 complexed with DNA suggests similar DNA unwinding and translocation mechanisms, which could be generalized to all of the members in the same family. Structural comparison also implied a minor rearrangement of the five domains during DNA unwinding reaction. The unexpected small contact between the DNA duplex region and the enzyme appears to be advantageous for processive helicase activity.
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Affiliation(s)
- Takuji Oyama
- The Takara Bio Endowed Division, Institute for Protein Research, Osaka University, Open Laboratories of Advanced Bioscience and Biotechnology (OLABB), 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan
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202
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Takata M, Ishiai M, Kitao H. The Fanconi anemia pathway: insights from somatic cell genetics using DT40 cell line. Mutat Res 2009; 668:92-102. [PMID: 19622405 DOI: 10.1016/j.mrfmmm.2008.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 12/15/2008] [Accepted: 12/24/2008] [Indexed: 10/21/2022]
Abstract
The Fanconi anemia (FA) pathway is a complex phosphorylation-ubiquitination network in the DNA damage signaling, which is still poorly understood. Defects in the "FA pathway" or in the related DNA repair proteins cause FA, a hereditary disorder that accompanies compromised DNA crosslink repair, poor hematopoetic stem cell survival, genomic instability, and cancer. For molecular dissection of the FA pathway, we have been using chicken B cell line DT40 as a model system. In this review, we will summarize our current understanding of the pathway, and discuss how studies using DT40 have contributed to this rapidly evolving field.
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Affiliation(s)
- Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effect Studies, Radiation Biology Center, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan.
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203
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Cohn MA, D'Andrea AD. Chromatin recruitment of DNA repair proteins: lessons from the fanconi anemia and double-strand break repair pathways. Mol Cell 2008; 32:306-12. [PMID: 18995829 DOI: 10.1016/j.molcel.2008.10.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Indexed: 01/13/2023]
Abstract
In response to DNA damage, eukaryotic cells must rapidly load DNA repair proteins onto damaged chromatin. Chromatin recruitment often entails ubiquitination of a damage-specific DNA repair protein, interaction with a ubiquitin binding factor, assembly of a multisubunit DNA repair complex, and eventually a deubiquitination event once the DNA repair reaction has been completed. This review focuses on the recent discoveries in the Fanconi Anemia (FA) and DNA double-strand break (DSB) repair pathways, which underscore the importance of regulated chromatin loading in the DNA damage response. Interestingly, these two pathways share several features, suggesting a more general mechanism for DNA-repair regulation.
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Affiliation(s)
- Martin A Cohn
- Department of Radiation Oncology, Division of Genomic Stability and DNA Repair, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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204
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Collis SJ, Ciccia A, Deans AJ, Horejsí Z, Martin JS, Maslen SL, Skehel JM, Elledge SJ, West SC, Boulton SJ. FANCM and FAAP24 function in ATR-mediated checkpoint signaling independently of the Fanconi anemia core complex. Mol Cell 2008; 32:313-24. [PMID: 18995830 DOI: 10.1016/j.molcel.2008.10.014] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 07/19/2008] [Accepted: 10/20/2008] [Indexed: 10/21/2022]
Abstract
The Fanconi anemia (FA) pathway is implicated in DNA repair and cancer predisposition. Central to this pathway is the FA core complex, which is targeted to chromatin by FANCM and FAAP24 following replication stress. Here we show that FANCM and FAAP24 interact with the checkpoint protein HCLK2 independently of the FA core complex. In addition to defects in FA pathway activation, downregulation of FANCM or FAAP24 also compromises ATR/Chk1-mediated checkpoint signaling, leading to defective Chk1, p53, and FANCE phosphorylation; 53BP1 focus formation; and Cdc25A degradation. As a result, FANCM and FAAP24 deficiency results in increased endogenous DNA damage and a failure to efficiently invoke cell-cycle checkpoint responses. 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. Our data suggest that DNA damage recognition and remodeling activities of FANCM and FAAP24 cooperate with ATR/Chk1 to promote efficient activation of DNA damage checkpoints.
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Affiliation(s)
- Spencer J Collis
- DNA Damage Response Laboratory, Cancer Research UK, Clare Hall, EN6 3LD South Mimms, UK
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205
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ATR-dependent phosphorylation of FANCA on serine 1449 after DNA damage is important for FA pathway function. Blood 2008; 113:2181-90. [PMID: 19109555 DOI: 10.1182/blood-2008-05-154294] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Previous work has shown several proteins defective in Fanconi anemia (FA) are phosphorylated in a functionally critical manner. FANCA is phosphorylated after DNA damage and localized to chromatin, but the site and significance of this phosphorylation are unknown. Mass spectrometry of FANCA revealed one phosphopeptide, phosphorylated on serine 1449. Serine 1449 phosphorylation was induced after DNA damage but not during S phase, in contrast to other posttranslational modifications of FA proteins. Furthermore, the S1449A mutant failed to completely correct a variety of FA-associated phenotypes. The DNA damage response is coordinated by phosphorylation events initiated by apical kinases ATM (ataxia telangectasia mutated) and ATR (ATM and Rad3-related), and ATR is essential for proper FA pathway function. Serine 1449 is in a consensus ATM/ATR site, phosphorylation in vivo is dependent on ATR, and ATR phosphorylated FANCA on serine 1449 in vitro. Phosphorylation of FANCA on serine 1449 is a DNA damage-specific event that is downstream of ATR and is functionally important in the FA pathway.
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206
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Youds JL, Barber LJ, Boulton SJ. C. elegans: a model of Fanconi anemia and ICL repair. Mutat Res 2008; 668:103-16. [PMID: 19059419 DOI: 10.1016/j.mrfmmm.2008.11.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 10/09/2008] [Accepted: 11/07/2008] [Indexed: 11/29/2022]
Abstract
Fanconi anemia (FA) is a severe recessive disorder with a wide range of clinical manifestations [M. Levitus, H. Joenje, J.P. de Winter, The Fanconi anemia pathway of genomic maintenance, Cell Oncol. 28 (2006) 3-29]. In humans, 13 complementation groups have been identified to underlie FA: A, B, C, D1, D2, E, F, G, I, J, L, M, and N [W. Wang, Emergence of a DNA-damage response network consisting of Fanconi anaemia and BRCA proteins, Nat. Rev. Genet. 8 (2007) 735-748]. Cells defective for any of these genes display chromosomal aberrations and sensitivity to DNA interstrand cross-links (ICLs). It has therefore been suggested that the 13 FA proteins constitute a pathway for the repair of ICLs, and that a deficiency in this repair process causes genomic instability leading to the different clinical phenotypes. However, the exact nature of this repair pathway, or even whether all 13 FA proteins are involved at some stage of a linear repair process, remains to be defined. Undoubtedly, the recent identification and characterisation of FA homologues in model organisms, such as Caenorhabditis elegans, will help facilitate an understanding of the function of the FA proteins by providing new analytical tools. To date, sequence homologues of five FA genes have been identified in C. elegans. Three of these homologues have been confirmed: brc-2 (FANCD1/BRCA2), fcd-2 (FANCD2), and dog-1 (FANCJ/BRIP1); and two remain to be characterised: W02D3.10 (FANCI) and drh-3 (FANCM). Here we review how the nematode can be used to study FA-associated DNA repair, focusing on what is known about the ICL repair genes in C. elegans and which important questions remain for the field.
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Affiliation(s)
- Jillian L Youds
- DNA Damage Response laboratory, London Research Institute, Cancer Research UK, Clare Hall Laboratories, Blanche Lane, South Mimms EN6 3LD, UK
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207
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Ishiai M, Kitao H, Smogorzewska A, Tomida J, Kinomura A, Uchida E, Saberi A, Kinoshita E, Kinoshita-Kikuta E, Koike T, Tashiro S, Elledge SJ, Takata M. FANCI phosphorylation functions as a molecular switch to turn on the Fanconi anemia pathway. Nat Struct Mol Biol 2008; 15:1138-46. [PMID: 18931676 DOI: 10.1038/nsmb.1504] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Accepted: 09/25/2008] [Indexed: 01/06/2023]
Abstract
In response to DNA damage or replication fork stress, the Fanconi anemia pathway is activated, leading to monoubiquitination of FANCD2 and FANCI and their colocalization in foci. Here we show that, in the chicken DT40 cell system, multiple alanine-substitution mutations in six conserved and clustered Ser/Thr-Gln motifs of FANCI largely abrogate monoubiquitination and focus formation of both FANCI and FANCD2, resulting in loss of DNA repair function. Conversely, FANCI carrying phosphomimic mutations on the same six residues induces constitutive monoubiquitination and focus formation of FANCI and FANCD2, and protects against cell killing and chromosome breakage by DNA interstrand cross-linking agents. We propose that the multiple phosphorylation of FANCI serves as a molecular switch in activation of the Fanconi anemia pathway. Mutational analysis of putative phosphorylation sites in human FANCI indicates that this switch is evolutionarily conserved.
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Affiliation(s)
- Masamichi Ishiai
- Laboratory of DNA Damage Signaling, Department of Late Effect Studies, Radiation Biology Center, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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208
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Wang LC, Stone S, Hoatlin ME, Gautier J. Fanconi anemia proteins stabilize replication forks. DNA Repair (Amst) 2008; 7:1973-81. [PMID: 18786657 DOI: 10.1016/j.dnarep.2008.08.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/08/2008] [Accepted: 08/15/2008] [Indexed: 10/21/2022]
Abstract
Fanconi anemia (FA) is a recessive genetic disorder characterized by hypersensitivity to crosslinking agents that has been attributed to defects in DNA repair and/or replication. FANCD2 and the FA core complex bind to chromatin during DNA replication; however, the role of FA proteins during replication is unknown. Using Xenopus cell-free extracts, we show that FANCL depletion results in defective DNA replication restart following treatment with camptothecin, a drug that results in DSBs during DNA replication. This defect is more pronounced following treatment with mitomycin C, presumably because of an additional role of the FA pathway in DNA crosslink repair. Moreover, we show that chromatin binding of FA core complex proteins during DNA replication follows origin assembly and origin firing and is dependent on the binding of RPA to ssDNA while FANCD2 additionally requires ATR, consistent with FA proteins acting at replication forks. Together, our data suggest that FA proteins play a role in replication restart at collapsed replication forks.
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Affiliation(s)
- Lily Chien Wang
- Institute for Cancer Genetics, Columbia University, New York, NY 10032, USA
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209
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Ciccia A, McDonald N, West SC. Structural and functional relationships of the XPF/MUS81 family of proteins. Annu Rev Biochem 2008; 77:259-87. [PMID: 18518821 DOI: 10.1146/annurev.biochem.77.070306.102408] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Proteins belonging to the XPF/MUS81 family play important roles in the repair of DNA lesions caused by UV-light or DNA cross-linking agents. Most eukaryotes have four family members that assemble into two distinct heterodimeric complexes, XPF-ERCC1 and MUS81-EME1. Each complex contains one catalytic and one noncatalytic subunit and exhibits endonuclease activity with a variety of 3'-flap or fork DNA structures. The catalytic subunits share a characteristic core containing an excision repair cross complementation group 4 (ERCC4) nuclease domain and a tandem helix-hairpin-helix (HhH)(2) domain. Diverged domains are present in the noncatalytic subunits and may be required for substrate targeting. Vertebrates possess two additional family members, FANCM and Fanconi anemia-associated protein 24 kDa (FAAP24), which possess inactive nuclease domains. Instead, FANCM contains a functional Superfamily 2 (SF2) helicase domain that is required for DNA translocation. Determining how these enzymes recognize specific DNA substrates and promote key repair reactions is an important challenge for the future.
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Affiliation(s)
- Alberto Ciccia
- London Research Institute, Cancer Research UK, Clare Hall Laboratories, Hertfordshire, United Kingdom
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210
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Abstract
In this issue of Blood, Kim and colleagues propose a model describing the function of FANCM in chromatin recruitment of the Fanconi anemia core complex.
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211
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Altieri F, Grillo C, Maceroni M, Chichiarelli S. DNA damage and repair: from molecular mechanisms to health implications. Antioxid Redox Signal 2008; 10:891-937. [PMID: 18205545 DOI: 10.1089/ars.2007.1830] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
DNA is subjected to several modifications, resulting from endogenous and exogenous sources. The cell has developed a network of complementary DNA-repair mechanisms, and in the human genome, >130 genes have been found to be involved. Knowledge about the basic mechanisms for DNA repair has revealed an unexpected complexity, with overlapping specificity within the same pathway, as well as extensive functional interactions between proteins involved in repair pathways. Unrepaired or improperly repaired DNA lesions have serious potential consequences for the cell, leading to genomic instability and deregulation of cellular functions. A number of disorders or syndromes, including several cancer predispositions and accelerated aging, are linked to an inherited defect in one of the DNA-repair pathways. Genomic instability, a characteristic of most human malignancies, can also arise from acquired defects in DNA repair, and the specific pathway affected is predictive of types of mutations, tumor drug sensitivity, and treatment outcome. Although DNA repair has received little attention as a determinant of drug sensitivity, emerging knowledge of mutations and polymorphisms in key human DNA-repair genes may provide a rational basis for improved strategies for therapeutic interventions on a number of tumors and degenerative disorders.
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Affiliation(s)
- Fabio Altieri
- Department of Biochemical Sciences, A. Rossi Fanelli, University La Sapienza, Rome, Italy.
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212
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Mirchandani KD, McCaffrey RM, D'Andrea AD. The Fanconi anemia core complex is required for efficient point mutagenesis and Rev1 foci assembly. DNA Repair (Amst) 2008; 7:902-11. [PMID: 18448394 DOI: 10.1016/j.dnarep.2008.03.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 02/28/2008] [Accepted: 03/03/2008] [Indexed: 11/28/2022]
Abstract
Fanconi anemia (FA) is a chromosome instability syndrome characterized by congenital abnormalities, cellular hypersensitivity to DNA crosslinking agents, and heightened cancer risk. Eight of the thirteen identified FA genes encode subunits of a nuclear FA core complex that monoubiquitinates FANCD2 and FANCI to maintain genomic stability in response to replication stress. The FA pathway has been implicated in the regulation of error-prone DNA damage tolerance via an undefined molecular mechanism. Here, we show that the FA core complex is required for efficient spontaneous and UVC-induced point mutagenesis, independently of FANCD2 and FANCI. Consistent with the observed hypomutability of cells deficient in the FA core complex, we also demonstrate that these cells are impaired in the assembly of the error-prone translesion DNA synthesis polymerase Rev1 into nuclear foci. Consistent with a role downstream of the FA core complex and like known FA proteins, Rev1 is required to prevent DNA crosslinker-induced chromosomal aberrations in human cells. Interestingly, proliferating cell nuclear antigen (PCNA) monoubiquitination, known to contribute to Rev1 recruitment, does not require FA core complex function. Our results suggest a role for the FA core complex in regulating Rev1-dependent DNA damage tolerance independently of FANCD2, FANCI, and PCNA monoubiquitination.
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Affiliation(s)
- Kanchan D Mirchandani
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
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213
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Gari K, Décaillet C, Stasiak AZ, Stasiak A, Constantinou A. The Fanconi anemia protein FANCM can promote branch migration of Holliday junctions and replication forks. Mol Cell 2008; 29:141-8. [PMID: 18206976 DOI: 10.1016/j.molcel.2007.11.032] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 08/22/2007] [Accepted: 11/16/2007] [Indexed: 10/22/2022]
Abstract
Fanconi anemia (FA) is a genetically heterogeneous cancer-prone disorder associated with chromosomal instability and cellular hypersensitivity to DNA crosslinking agents. The FA pathway is suspected to play a crucial role in the cellular response to DNA replication stress. At a molecular level, however, the function of most of the FA proteins is unknown. FANCM displays DNA-dependent ATPase activity and promotes the dissociation of DNA triplexes, but the physiological significance of this activity remains elusive. Here we show that purified FANCM binds to Holliday junctions and replication forks with high specificity and promotes migration of their junction point in an ATPase-dependent manner. Furthermore, we provide evidence that FANCM can dissociate large recombination intermediates, via branch migration of Holliday junctions through 2.6 kb of DNA. Our data suggest a direct role for FANCM in DNA processing, consistent with the current view that FA proteins coordinate DNA repair at stalled replication forks.
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Affiliation(s)
- Kerstin Gari
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges s/Lausanne, Switzerland
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214
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Hakem R. DNA-damage repair; the good, the bad, and the ugly. EMBO J 2008; 27:589-605. [PMID: 18285820 PMCID: PMC2262034 DOI: 10.1038/emboj.2008.15] [Citation(s) in RCA: 318] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 01/16/2008] [Indexed: 12/12/2022] Open
Abstract
Organisms have developed several DNA-repair pathways as well as DNA-damage checkpoints to cope with the frequent challenge of endogenous and exogenous DNA insults. In the absence or impairment of such repair or checkpoint mechanisms, the genomic integrity of the organism is often compromised. This review will focus on the functional consequences of impaired DNA-repair pathways. Although each pathway is addressed individually, it is essential to note that cross talk exists between repair pathways, and that there are instances in which a DNA-repair protein is involved in more than one pathway. It is also important to integrate DNA-repair process with DNA-damage checkpoints and cell survival, to gain a better understanding of the consequences of compromised DNA repair at both cellular and organismic levels. Functional consequences associated with impaired DNA repair include embryonic lethality, shortened life span, rapid ageing, impaired growth, and a variety of syndromes, including a pronounced manifestation of cancer.
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Affiliation(s)
- Razqallah Hakem
- Department of Medical Biophysics, Ontario Cancer Institute/UHN, University of Toronto, Toronto, Ontario, Canada.
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215
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Xue Y, Li Y, Guo R, Ling C, Wang W. FANCM of the Fanconi anemia core complex is required for both monoubiquitination and DNA repair. Hum Mol Genet 2008; 17:1641-52. [PMID: 18285517 DOI: 10.1093/hmg/ddn054] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
In response to DNA damage, the Fanconi anemia (FA) core complex functions as a signaling machine for monoubiquitination of FANCD2 and FANCI. It remains unclear whether this complex can also participate in subsequent DNA repair. We have shown previously that the FANCM constituent of the complex contains a highly conserved helicase domain and an associated ATP-dependent DNA translocase activity. Here we show that FANCM also possesses an ATP-independent binding activity and an ATP-dependent bi-directional branch-point translocation activity on a synthetic four-way junction DNA, which mimics intermediates generated during homologous recombination or at stalled replication forks. Using an siRNA-based complementation system, we found that the ATP-dependent activities of FANCM are required for cellular resistance to a DNA-crosslinking drug, mitomycin C, but not for the monoubiquitination of FANCD2 and FANCI. In contrast, monoubiquitination requires the entire helicase domain of FANCM, which has both ATP dependent and independent activities. These data are consistent with participation of FANCM and its associated FA core complex in the FA pathway at both signaling through monoubiquitination and the ensuing DNA repair.
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Affiliation(s)
- Yutong Xue
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, 333 Cassell Drive, TRIAD Center Room 3000, Baltimore, MD 21224, USA
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216
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FANCG promotes formation of a newly identified protein complex containing BRCA2, FANCD2 and XRCC3. Oncogene 2008; 27:3641-52. [PMID: 18212739 DOI: 10.1038/sj.onc.1211034] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fanconi anemia (FA) is a human disorder characterized by cancer susceptibility and cellular sensitivity to DNA crosslinks and other damages. Thirteen complementation groups and genes are identified, including BRCA2, which is defective in the FA-D1 group. Eight of the FA proteins, including FANCG, participate in a nuclear core complex that is required for the monoubiquitylation of FANCD2 and FANCI. FANCD2, like FANCD1/BRCA2, is not part of the core complex, and we previously showed direct BRCA2-FANCD2 interaction using yeast two-hybrid analysis. We now show in human and hamster cells that expression of FANCG protein, but not the other core complex proteins, is required for co-precipitation of BRCA2 and FANCD2. We also show that phosphorylation of FANCG serine 7 is required for its co-precipitation with BRCA2, XRCC3 and FANCD2, as well as the direct interaction of BRCA2-FANCD2. These results argue that FANCG has a role independent of the FA core complex, and we propose that phosphorylation of serine 7 is the signalling event required for forming a discrete complex comprising FANCD1/BRCA2-FANCD2-FANCG-XRCC3 (D1-D2-G-X3). Cells that fail to express either phospho-Ser7-FANCG, or full length BRCA2 protein, lack the interactions amongst the four component proteins. A role for D1-D2-G-X3 in homologous recombination repair (HRR) is supported by our finding that FANCG and the RAD51-paralog XRCC3 are epistatic for sensitivity to DNA crosslinking compounds in DT40 chicken cells. Our findings further define the intricate interface between FANC and HRR proteins in maintaining chromosome stability.
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217
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Abstract
Fanconi anemia (FA) is a genetic disease characterized by congenital abnormalities, bone marrow failure, and cancer susceptibility. A total of 13 FA proteins are involved in regulating genome surveillance and chromosomal stability. The FA core complex, consisting of 8 FA proteins (A/B/C/E/F/G/L/M), is essential for the monoubiquitination of FANCD2 and FANCI. FANCM is a human ortholog of the archaeal DNA repair protein Hef, and it contains a DEAH helicase and a nuclease domain. Here, we examined the effect of FANCM expression on the integrity and localization of the FA core complex. FANCM was exclusively localized to chromatin fractions and underwent cell cycle-dependent phosphorylation and dephosphorylation. FANCM-depleted HeLa cells had an intact FA core complex but were defective in chromatin localization of the complex. Moreover, depletion of the FANCM binding partner, FAAP24, disrupted the chromatin association of FANCM and destabilized FANCM, leading to defective recruitment of the FA core complex to chromatin. Our results suggest that FANCM is an anchor required for recruitment of the FA core complex to chromatin, and that the FANCM/FAAP24 interaction is essential for this chromatin-loading activity. Dysregulated loading of the FA core complex accounts, at least in part, for the characteristic cellular and developmental abnormalities in FA.
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218
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Abstract
Homologous recombination (HR) comprises a series of interrelated pathways that function in the repair of DNA double-stranded breaks (DSBs) and interstrand crosslinks (ICLs). In addition, recombination provides critical support for DNA replication in the recovery of stalled or broken replication forks, contributing to tolerance of DNA damage. A central core of proteins, most critically the RecA homolog Rad51, catalyzes the key reactions that typify HR: homology search and DNA strand invasion. The diverse functions of recombination are reflected in the need for context-specific factors that perform supplemental functions in conjunction with the core proteins. The inability to properly repair complex DNA damage and resolve DNA replication stress leads to genomic instability and contributes to cancer etiology. Mutations in the BRCA2 recombination gene cause predisposition to breast and ovarian cancer as well as Fanconi anemia, a cancer predisposition syndrome characterized by a defect in the repair of DNA interstrand crosslinks. The cellular functions of recombination are also germane to DNA-based treatment modalities of cancer, which target replicating cells by the direct or indirect induction of DNA lesions that are substrates for recombination pathways. This review focuses on mechanistic aspects of HR relating to DSB and ICL repair as well as replication fork support.
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Affiliation(s)
- Xuan Li
- Section of Microbiology University of California, Davis, Davis CA 95616-8665, USA
| | - Wolf-Dietrich Heyer
- Section of Microbiology University of California, Davis, Davis CA 95616-8665, USA
- Section of Molecular and Cellular Biology, University of California, Davis, Davis CA 95616-8665, USA
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219
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Grillari J, Katinger H, Voglauer R. Contributions of DNA interstrand cross-links to aging of cells and organisms. Nucleic Acids Res 2007; 35:7566-76. [PMID: 18083760 PMCID: PMC2190700 DOI: 10.1093/nar/gkm1065] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Revised: 11/11/2007] [Accepted: 11/11/2007] [Indexed: 01/05/2023] Open
Abstract
Impaired DNA damage repair, especially deficient transcription-coupled nucleotide excision repair, leads to segmental progeroid syndromes in human patients as well as in rodent models. Furthermore, DNA double-strand break signalling has been pinpointed as a key inducer of cellular senescence. Several recent findings suggest that another DNA repair pathway, interstrand cross-link (ICL) repair, might also contribute to cell and organism aging. Therefore, we summarize and discuss here that (i) systemic administration of anti-cancer chemotherapeutics, in many cases DNA cross-linking drugs, induces premature progeroid frailty in long-term survivors; (ii) that ICL-inducing 8-methoxy-psoralen/UVA phototherapy leads to signs of premature skin aging as prominent long-term side effect and (iii) that mutated factors involved in ICL repair like ERCC1/XPF, the Fanconi anaemia proteins, WRN and SNEV lead to reduced replicative life span in vitro and segmental progeroid syndromes in vivo. However, since ICL-inducing drugs cause damage different from ICL and since all currently known ICL repair factors work in more than one pathway, further work will be needed to dissect the actual contribution of ICL damage to aging.
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Affiliation(s)
- Johannes Grillari
- Institute of Applied Microbiology, Department of Biotechnology, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18 1190 Vienna, Austria.
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220
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Abstract
Fanconi anemia (FA) is a rare genetic disorder characterized by aplastic anemia, cancer/leukemia susceptibility and cellular hypersensitivity to DNA crosslinking agents, such as cisplatin. To date, 12 FA gene products have been identified, which cooperate in a common DNA damage-activated signaling pathway regulating DNA repair (the FA pathway). Eight FA proteins form a nuclear complex harboring E3 ubiquitin ligase activity (the FA core complex) that, in response to DNA damage, mediates the monoubiquitylation of the FA protein FANCD2. Monoubiquitylated FANCD2 colocalizes in nuclear foci with proteins involved in DNA repair, including BRCA1, FANCD1/BRCA2, FANCN/PALB2 and RAD51. All these factors are required for cellular resistance to DNA crosslinking agents. The inactivation of the FA pathway has also been observed in a wide variety of human cancers and is implicated in the sensitivity of cancer cells to DNA crosslinking agents. Drugs that inhibit the FA pathway may be useful chemosensitizers in the treatment of cancer. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).
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Affiliation(s)
- Céline Jacquemont
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave, N, C1-015, Seattle, WA 98109-1024, USA
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221
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UBE2T, the Fanconi anemia core complex, and FANCD2 are recruited independently to chromatin: a basis for the regulation of FANCD2 monoubiquitination. Mol Cell Biol 2007; 27:8421-30. [PMID: 17938197 DOI: 10.1128/mcb.00504-07] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Fanconi anemia (FA) nuclear core complex and the E2 ubiquitin-conjugating enzyme UBE2T are required for the S phase and DNA damage-restricted monoubiquitination of FANCD2. This constitutes a key step in the FA tumor suppressor pathway, and much attention has been focused on the regulation at this point. Here, we address the importance of the assembly of the FA core complex and the subcellular localization of UBE2T in the regulation of FANCD2 monoubiquitination. We establish three points. First, the stable assembly of the FA core complex can be dissociated of its ability to function as an E3 ubiquitin ligase. Second, the actual E3 ligase activity is not determined by the assembly of the FA core complex but rather by its DNA damage-induced localization to chromatin. Finally, UBE2T and FANCD2 access this subcellular fraction independently of the FA core complex. FANCD2 monoubiquitination is therefore not regulated by multiprotein complex assembly but by the formation of an active E2/E3 holoenzyme on chromatin.
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222
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Wang W. Emergence of a DNA-damage response network consisting of Fanconi anaemia and BRCA proteins. Nat Rev Genet 2007; 8:735-48. [PMID: 17768402 DOI: 10.1038/nrg2159] [Citation(s) in RCA: 559] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fanconi anaemia (FA) has recently become an attractive model to study breast cancer susceptibility (BRCA) genes, as three FA genes, FANCD1, FANCN and FANCJ, are identical to the BRCA genes BRCA2, PALB2 and BRIP1. Increasing evidence shows that FA proteins function as signal transducers and DNA-processing molecules in a DNA-damage response network. This network consists of many proteins that maintain genome integrity, including ataxia telangiectasia and Rad3 related protein (ATR), Bloom syndrome protein (BLM), and BRCA1. Now that the gene that is defective in the thirteenth and last assigned FA complementation group (FANCI) has been identified, I discuss what is known about FA proteins and their interactive network, and what remains to be discovered.
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Affiliation(s)
- Weidong Wang
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, 333 Cassell drive, Baltimore, Maryland 21093, USA.
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223
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Tripsianes K, Folkers GE, Zheng C, Das D, Grinstead JS, Kaptein R, Boelens R. Analysis of the XPA and ssDNA-binding surfaces on the central domain of human ERCC1 reveals evidence for subfunctionalization. Nucleic Acids Res 2007; 35:5789-98. [PMID: 17720715 PMCID: PMC2034474 DOI: 10.1093/nar/gkm503] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Human ERCC1/XPF is a structure-specific endonuclease involved in multiple DNA repair pathways. We present the solution structure of the non-catalytic ERCC1 central domain. Although this domain shows structural homology with the catalytically active XPF nuclease domain, functional investigation reveals a completely distinct function for the ERCC1 central domain by performing interactions with both XPA and single-stranded DNA. These interactions are non-competitive and can occur simultaneously through distinct interaction surfaces. Interestingly, the XPA binding by ERCC1 and the catalytic function of XPF are dependent on a structurally homologous region of the two proteins. Although these regions are strictly conserved in each protein family, amino acid composition and surface characteristics are distinct. We discuss the possibility that after XPF gene duplication, the redundant ERCC1 central domain acquired novel functions, thereby increasing the fidelity of eukaryotic DNA repair.
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Affiliation(s)
| | | | | | | | | | | | - Rolf Boelens
- *To whom correspondence should be addressed. +31 30 2534035+31 30 2537623
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224
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Hinz JM, Nham PB, Urbin SS, Jones IM, Thompson LH. Disparate contributions of the Fanconi anemia pathway and homologous recombination in preventing spontaneous mutagenesis. Nucleic Acids Res 2007; 35:3733-40. [PMID: 17517774 PMCID: PMC1920256 DOI: 10.1093/nar/gkm315] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Fanconi anemia (FA) is a chromosomal instability disorder in which DNA-damage processing defects are reported for translesion synthesis (TLS), non-homologous end joining (NHEJ) and homologous recombination (HR; both increased and decreased). To reconcile these diverse findings, we compared spontaneous mutagenesis in FA and HR mutants of hamster CHO cells. In the fancg mutant we find a reduced mutation rate accompanied by an increased proportion of deletions within the hprt gene. Moreover, in fancg cells gene amplification at the CAD and dhfr loci is elevated, another manifestation of inappropriate processing of damage during DNA replication. In contrast, the rad51d HR mutant has a greatly elevated rate of hprt mutations, >85% of which are deletions. Our analysis supports the concept that HR faithfully restores broken replication forks, whereas the FA pathway acts more globally to ensure chromosome stability by promoting efficient end joining of replication-derived breaks, as well as TLS and HR.
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Affiliation(s)
- John M Hinz
- Chemistry, Materials, & Life Sciences Directorate, L441, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, USA.
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225
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Sobeck A, Stone S, Hoatlin ME. DNA structure-induced recruitment and activation of the Fanconi anemia pathway protein FANCD2. Mol Cell Biol 2007; 27:4283-92. [PMID: 17420278 PMCID: PMC1900049 DOI: 10.1128/mcb.02196-06] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Fanconi anemia (FA) pathway proteins are thought to be involved in the repair of irregular DNA structures including those encountered by the moving replication fork. However, the nature of the DNA structures that recruit and activate the FA proteins is not known. Because FA proteins function within an extended network of proteins, some of which are still unknown, we recently established cell-free assays in Xenopus laevis egg extracts to deconstruct the FA pathway in a fully replication-competent context. Here we show that the central FA pathway protein, xFANCD2, is monoubiquitinated (xFANCD2-L) rapidly in the presence of linear and branched double-stranded DNA (dsDNA) structures but not single-stranded or Y-shaped DNA. xFANCD2-L associates with dsDNA structures in an FA core complex-dependent manner but independently of xATRIP, the regulatory subunit of xATR. Formation of xFANCD2-L is also triggered in response to circular dsDNA, suggesting that dsDNA ends are not required to trigger monoubiquitination of FANCD2. The induction of xFANCD2-L in response to circular dsDNA is replication and checkpoint independent. Our results provide new evidence that the FA pathway discriminates among DNA structures and demonstrate that triggering the FA pathway can be uncoupled from DNA replication and ATRIP-dependent activation.
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Affiliation(s)
- A Sobeck
- Biochemistry and Molecular Biology and Molecular and Medical Genetics, Oregon Health and Science University, Medical Research Building, Portland, OR 97239, USA
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226
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Ling C, Ishiai M, Ali AM, Medhurst AL, Neveling K, Kalb R, Yan Z, Xue Y, Oostra AB, Auerbach AD, Hoatlin ME, Schindler D, Joenje H, de Winter JP, Takata M, Meetei AR, Wang W. FAAP100 is essential for activation of the Fanconi anemia-associated DNA damage response pathway. EMBO J 2007; 26:2104-14. [PMID: 17396147 PMCID: PMC1852792 DOI: 10.1038/sj.emboj.7601666] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 03/06/2007] [Indexed: 01/17/2023] Open
Abstract
The Fanconi anemia (FA) core complex plays a central role in the DNA damage response network involving breast cancer susceptibility gene products, BRCA1 and BRCA2. The complex consists of eight FA proteins, including a ubiquitin ligase (FANCL) and a DNA translocase (FANCM), and is essential for monoubiquitination of FANCD2 in response to DNA damage. Here, we report a novel component of this complex, termed FAAP100, which is essential for the stability of the core complex and directly interacts with FANCB and FANCL to form a stable subcomplex. Formation of this subcomplex protects each component from proteolytic degradation and also allows their coregulation by FANCA and FANCM during nuclear localization. Using siRNA depletion and gene knockout techniques, we show that FAAP100-deficient cells display hallmark features of FA cells, including defective FANCD2 monoubiquitination, hypersensitivity to DNA crosslinking agents, and genomic instability. Our study identifies FAAP100 as a new critical component of the FA-BRCA DNA damage response network.
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Affiliation(s)
- Chen Ling
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Masamichi Ishiai
- Department of Immunology and Molecular Genetics, Kawasaki Medical School, Kurashiki, Okayama, Japan
| | - Abdullah Mahmood Ali
- Division of Experimental Hematology, Cincinnati Children's Hospital Research Foundation and University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Annette L Medhurst
- Department of Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | - Kornelia Neveling
- Department of Human Genetics, University of Wurzburg, Wurzburg, Germany
| | - Reinhard Kalb
- Department of Human Genetics, University of Wurzburg, Wurzburg, Germany
| | - Zhijiang Yan
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Yutong Xue
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Anneke B Oostra
- Department of Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | - Arleen D Auerbach
- Laboratory of Human Genetics and Hematology, The Rockefeller University, New York, NY, USA
| | - Maureen E Hoatlin
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR, USA
| | - Detlev Schindler
- Department of Human Genetics, University of Wurzburg, Wurzburg, Germany
| | - Hans Joenje
- Department of Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | - Johan P de Winter
- Department of Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | - Minoru Takata
- Department of Immunology and Molecular Genetics, Kawasaki Medical School, Kurashiki, Okayama, Japan
- Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
| | - Amom Ruhikanta Meetei
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
- Division of Experimental Hematology, Cincinnati Children's Hospital Research Foundation and University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Experimental Hematology, Cincinnati Children's Hospital Research Foundation and University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229, USA. Tel.: +1 513 636 1768; Fax: +1 513 636 3768; E-mail:
| | - Weidong Wang
- Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
- Laboratory of Genetics, National Institute on Aging, NIH, 333 Cassell Drive, TRIAD Center Room 3000, Baltimore, MD 21224, USA. Tel.: +1 410 558 8334; Fax: +1 410 558 8331; E-mail:
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227
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Abstract
FAAP24, a new XPF endonuclease family member identified by in a recent issue of Molecular Cell, heterodimerizes with FANCM, binds unwound DNA, and reveals how the Fanconi anemia core complex concentrates DNA repair proteins at stalled replication forks.
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Affiliation(s)
- Laura J Niedernhofer
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine and Cancer Institute, Pittsburgh, PA 15213, USA.
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