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Hambarde S, Tsai CL, Pandita RK, Bacolla A, Maitra A, Charaka V, Hunt CR, Kumar R, Limbo O, Le Meur R, Chazin WJ, Tsutakawa SE, Russell P, Schlacher K, Pandita TK, Tainer JA. EXO5-DNA structure and BLM interactions direct DNA resection critical for ATR-dependent replication restart. Mol Cell 2021; 81:2989-3006.e9. [PMID: 34197737 PMCID: PMC8720176 DOI: 10.1016/j.molcel.2021.05.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 04/09/2021] [Accepted: 05/24/2021] [Indexed: 02/07/2023]
Abstract
Stalled DNA replication fork restart after stress as orchestrated by ATR kinase, BLM helicase, and structure-specific nucleases enables replication, cell survival, and genome stability. Here we unveil human exonuclease V (EXO5) as an ATR-regulated DNA structure-specific nuclease and BLM partner for replication fork restart. We find that elevated EXO5 in tumors correlates with increased mutation loads and poor patient survival, suggesting that EXO5 upregulation has oncogenic potential. Structural, mechanistic, and mutational analyses of EXO5 and EXO5-DNA complexes reveal a single-stranded DNA binding channel with an adjacent ATR phosphorylation motif (T88Q89) that regulates EXO5 nuclease activity and BLM binding identified by mass spectrometric analysis. EXO5 phospho-mimetic mutant rescues the restart defect from EXO5 depletion that decreases fork progression, DNA damage repair, and cell survival. EXO5 depletion furthermore rescues survival of FANCA-deficient cells and indicates EXO5 functions epistatically with SMARCAL1 and BLM. Thus, an EXO5 axis connects ATR and BLM in directing replication fork restart.
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Affiliation(s)
- Shashank Hambarde
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, USA; Department of Neurosurgery, The Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Chi-Lin Tsai
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Raj K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Albino Bacolla
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Anirban Maitra
- Sheikh Ahmed Center for Pancreatic Cancer Research, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Vijay Charaka
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Clayton R Hunt
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Rakesh Kumar
- School of Biotechnology, Shri Mata Vashino Devi University, Katra, Jammu and Kashmir, 182320, India
| | - Oliver Limbo
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Remy Le Meur
- Departments of Biochemistry and Chemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Walter J Chazin
- Departments of Biochemistry and Chemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Susan E Tsutakawa
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Paul Russell
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Katharina Schlacher
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Tej K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, USA; Department of Neurosurgery, The Houston Methodist Research Institute, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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Abstract
The double-helical structure of genomic DNA is both elegant and functional in that it serves both to protect vulnerable DNA bases and to facilitate DNA replication and compaction. However, these design advantages come at the cost of having to evolve and maintain a cellular machinery that can manipulate a long polymeric molecule that readily becomes topologically entangled whenever it has to be opened for translation, replication, or repair. If such a machinery fails to eliminate detrimental topological entanglements, utilization of the information stored in the DNA double helix is compromised. As a consequence, the use of B-form DNA as the carrier of genetic information must have co-evolved with a means to manipulate its complex topology. This duty is performed by DNA topoisomerases, which therefore are, unsurprisingly, ubiquitous in all kingdoms of life. In this review, we focus on how DNA topoisomerases catalyze their impressive range of DNA-conjuring tricks, with a particular emphasis on DNA topoisomerase III (TOP3). Once thought to be the most unremarkable of topoisomerases, the many lives of these type IA topoisomerases are now being progressively revealed. This research interest is driven by a realization that their substrate versatility and their ability to engage in intimate collaborations with translocases and other DNA-processing enzymes are far more extensive and impressive than was thought hitherto. This, coupled with the recent associations of TOP3s with developmental and neurological pathologies in humans, is clearly making us reconsider their undeserved reputation as being unexceptional enzymes.
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Affiliation(s)
- Anna H Bizard
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
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Hudson DF, Amor DJ, Boys A, Butler K, Williams L, Zhang T, Kalitsis P. Loss of RMI2 Increases Genome Instability and Causes a Bloom-Like Syndrome. PLoS Genet 2016; 12:e1006483. [PMID: 27977684 PMCID: PMC5157948 DOI: 10.1371/journal.pgen.1006483] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 11/15/2016] [Indexed: 12/03/2022] Open
Abstract
Bloom syndrome is a recessive human genetic disorder with features of genome instability, growth deficiency and predisposition to cancer. The only known causative gene is the BLM helicase that is a member of a protein complex along with topoisomerase III alpha, RMI1 and 2, which maintains replication fork stability and dissolves double Holliday junctions to prevent genome instability. Here we report the identification of a second gene, RMI2, that is deleted in affected siblings with Bloom-like features. Cells from homozygous individuals exhibit elevated rates of sister chromatid exchange, anaphase DNA bridges and micronuclei. Similar genome and chromosome instability phenotypes are observed in independently derived RMI2 knockout cells. In both patient and knockout cell lines reduced localisation of BLM to ultra fine DNA bridges and FANCD2 at foci linking bridges are observed. Overall, loss of RMI2 produces a partially active BLM complex with mild features of Bloom syndrome. Cells contain specific protein complexes that are needed to correct errors during the replication and segregation of DNA. Impairment in the activity of these proteins can be detrimental to the viability of the cell and organism development. Bloom syndrome is an example of a genome instability disorder where cells cannot efficiently untangle DNA after replication. The only gene that is known to cause Bloom syndrome is the BLM helicase. In this article, we describe two affected individuals with Bloom-like features with a homozygous deletion of the RMI2 gene. The RMI2 protein has previously been shown to form a complex with BLM, topoisomerase III alpha and RMI1. Deletion of RMI2 in patient and unrelated cell lines show hyper-recombination and chromosome entanglements during cell division. Furthermore, we show that the BLM and FANCD2 proteins are diminished in the binding of DNA bridges that need to be dissolved during the late stages of cell division. Therefore, loss of RMI2 produces a milder Bloom phenotype and impairs the full activity of the BLM complex.
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Affiliation(s)
- Damien F. Hudson
- Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
- * E-mail: (PK); (DFH)
| | - David J. Amor
- Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Amber Boys
- Cytogenetics Laboratory, Victorian Clinical Genetics Services, Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne, Parkville, Victoria, Australia
| | - Kathy Butler
- Cytogenetics Laboratory, Victorian Clinical Genetics Services, Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne, Parkville, Victoria, Australia
| | - Lorna Williams
- Cytogenetics Laboratory, Victorian Clinical Genetics Services, Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne, Parkville, Victoria, Australia
| | - Tao Zhang
- Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Paul Kalitsis
- Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
- * E-mail: (PK); (DFH)
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Lopez-Martinez D, Liang CC, Cohn MA. Cellular response to DNA interstrand crosslinks: the Fanconi anemia pathway. Cell Mol Life Sci 2016; 73:3097-114. [PMID: 27094386 PMCID: PMC4951507 DOI: 10.1007/s00018-016-2218-x] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 04/04/2016] [Accepted: 04/05/2016] [Indexed: 12/22/2022]
Abstract
Interstrand crosslinks (ICLs) are a highly toxic form of DNA damage. ICLs can interfere with vital biological processes requiring separation of the two DNA strands, such as replication and transcription. If ICLs are left unrepaired, it can lead to mutations, chromosome breakage and mitotic catastrophe. The Fanconi anemia (FA) pathway can repair this type of DNA lesion, ensuring genomic stability. In this review, we will provide an overview of the cellular response to ICLs. First, we will discuss the origin of ICLs, comparing various endogenous and exogenous sources. Second, we will describe FA proteins as well as FA-related proteins involved in ICL repair, and the post-translational modifications that regulate these proteins. Finally, we will review the process of how ICLs are repaired by both replication-dependent and replication-independent mechanisms.
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Affiliation(s)
- David Lopez-Martinez
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Chih-Chao Liang
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Martin A Cohn
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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Root H, Larsen A, Komosa M, Al-Azri F, Li R, Bazett-Jones DP, Stephen Meyn M. FANCD2 limits BLM-dependent telomere instability in the alternative lengthening of telomeres pathway. Hum Mol Genet 2016; 25:3255-3268. [DOI: 10.1093/hmg/ddw175] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 05/02/2016] [Accepted: 06/06/2016] [Indexed: 11/12/2022] Open
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Abstract
Fanconi anemia (FA) is a rare recessive genetic disease characterized by congenital abnormalities, bone marrow failure and heightened cancer susceptibility in early adulthood. FA is caused by biallelic germ-line mutation of any one of 16 genes. While several functions for the FA proteins have been ascribed, the prevailing hypothesis is that the FA proteins function cooperatively in the FA-BRCA pathway to repair damaged DNA. A pivotal step in the activation of the FA-BRCA pathway is the monoubiquitination of the FANCD2 and FANCI proteins. Despite their importance for DNA repair, the domain structure, regulation, and function of FANCD2 and FANCI remain poorly understood. In this review, we provide an overview of our current understanding of FANCD2 and FANCI, with an emphasis on their posttranslational modification and common and unique functions.
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Key Words
- AML , acute myeloid leukemia
- APC/C, anaphase-promoting complex/cyclosome
- APH, aphidicolin
- ARM, armadillo repeat domain
- AT, ataxia-telangiectasia
- ATM, ataxia-telangiectasia mutated
- ATR, ATM and Rad3-related
- BAC, bacterial-artificial-chromosome
- BS, Bloom syndrome
- CUE, coupling of ubiquitin conjugation to endoplasmic reticulum degradation
- ChIP-seq, CHIP sequencing
- CtBP, C-terminal binding protein
- CtIP, CtBP-interacting protein
- DNA interstrand crosslink repair
- DNA repair
- EPS15, epidermal growth factor receptor pathway substrate 15
- FA, Fanconi anemia
- FAN1, FANCD2-associated nuclease1
- FANCD2
- FANCI
- FISH, fluorescence in situ hybridization
- Fanconi anemia
- HECT, homologous to E6-AP Carboxy Terminus
- HJ, Holliday junction
- HR, homologous recombination
- MCM2-MCM7, minichromosome maintenance 2–7
- MEFs, mouse embryonic fibroblasts
- MMC, mitomycin C
- MRN, MRE11/RAD50/NBS1
- NLS, nuclear localization signal
- PCNA, proliferating cell nuclear antigen
- PIKK, phosphatidylinositol-3-OH-kinase-like family of protein kinases
- PIP-box, PCNA-interacting protein motif
- POL κ, DNA polymerase κ
- RACE, rapid amplification of cDNA ends
- RING, really interesting new gene
- RTK, receptor tyrosine kinase
- SCF, Skp1/Cullin/F-box protein complex
- SCKL1, seckel syndrome
- SILAC, stable isotope labeling with amino acids in cell culture
- SLD1/SLD2, SUMO-like domains
- SLIM, SUMO-like domain interacting motif
- TIP60, 60 kDa Tat-interactive protein
- TLS, Translesion DNA synthesis
- UAF1, USP1-associated factor 1
- UBD, ubiquitin-binding domain
- UBZ, ubiquitin-binding zinc finger
- UFB, ultra-fine DNA bridges
- UIM, ubiquitin-interacting motif
- ULD, ubiquitin-like domain
- USP1, ubiquitin-specific protease 1
- VRR-nuc, virus-type replication repair nuclease
- iPOND, isolation of proteins on nascent DNA
- ubiquitin
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Affiliation(s)
- Rebecca A Boisvert
- a Department of Cell and Molecular Biology ; University of Rhode Island ; Kingston , RI USA
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Owen N, Hejna J, Rennie S, Mitchell A, Newell AH, Ziaie N, Moses RE, Olson SB. Bloom syndrome radials are predominantly non-homologous and are suppressed by phosphorylated BLM. Cytogenet Genome Res 2015; 144:255-263. [PMID: 25766002 DOI: 10.1159/000375247] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2014] [Indexed: 01/01/2023] Open
Abstract
Biallelic mutations in BLM cause Bloom syndrome (BS), a genome instability disorder characterized by growth retardation, sun sensitivity and a predisposition to cancer. As evidence of decreased genome stability, BS cells demonstrate not only elevated levels of spontaneous sister chromatid exchanges (SCEs), but also exhibit chromosomal radial formation. The molecular nature and mechanism of radial formation is not known, but radials have been thought to be DNA recombination intermediates between homologs that failed to resolve. However, we find that radials in BS cells occur over 95% between non-homologous chromosomes, and occur non-randomly throughout the genome. BLM must be phosphorylated at T99 and T122 for certain cell cycle checkpoints, but it is not known whether these modifications are necessary to suppress radial formation. We find that exogenous BLM constructs preventing phosphorylation at T99 and T122 are not able to suppress radial formation in BS cells, but are able to inhibit SCE formation. These findings indicate that BLM functions in 2 distinct pathways requiring different modifications. In one pathway, for which the phosphorylation marks appear dispensable, BLM functions to suppress SCE formation. In a second pathway, T99 and T122 phosphorylations are essential for suppression of chromosomal radial formation, both those formed spontaneously and those formed following interstrand crosslink damage.
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Affiliation(s)
- Nichole Owen
- Department of Molecular and Medical Genetics Oregon Health & Science University, 3181 SW Sam Jackson Park, Portland, OR 97239
| | - James Hejna
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501 Japan
| | - Scott Rennie
- Department of Molecular and Medical Genetics Oregon Health & Science University, 3181 SW Sam Jackson Park, Portland, OR 97239
| | - Asia Mitchell
- Department of Molecular and Medical Genetics Oregon Health & Science University, 3181 SW Sam Jackson Park, Portland, OR 97239
| | - Amy Hanlon Newell
- Department of Molecular and Medical Genetics Oregon Health & Science University, 3181 SW Sam Jackson Park, Portland, OR 97239
| | - Navid Ziaie
- Department of Molecular and Medical Genetics Oregon Health & Science University, 3181 SW Sam Jackson Park, Portland, OR 97239
| | - Robb E Moses
- Department of Molecular and Cellular Biology, Baylor College of Medicine Houston, TX 77030
| | - Susan B Olson
- Department of Molecular and Medical Genetics Oregon Health & Science University, 3181 SW Sam Jackson Park, Portland, OR 97239
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Kumari A, Owen N, Juarez E, McCullough AK. BLM protein mitigates formaldehyde-induced genomic instability. DNA Repair (Amst) 2015; 28:73-82. [PMID: 25770783 DOI: 10.1016/j.dnarep.2015.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 01/30/2015] [Accepted: 02/10/2015] [Indexed: 12/18/2022]
Abstract
Formaldehyde is a reactive aldehyde that has been classified as a class I human carcinogen by the International Agency for Cancer Research. There are growing concerns over the possible adverse health effects related to the occupational and environmental human exposures to formaldehyde. Although formaldehyde-induced DNA and protein adducts have been identified, the genomic instability mechanisms and the cellular tolerance pathways associated with formaldehyde exposure are not fully characterized. This study specifically examines the role of a genome stability protein, Bloom (BLM) in limiting formaldehyde-induced cellular and genetic abnormalities. Here, we show that in the absence of BLM protein, formaldehyde-treated cells exhibited increased cellular sensitivity, an immediate cell cycle arrest, and an accumulation of chromosome radial structures. In addition, live-cell imaging experiments demonstrated that formaldehyde-treated cells are dependent on BLM for timely segregation of daughter cells. Both wild-type and BLM-deficient formaldehyde-treated cells showed an accumulation of 53BP1 and γH2AX foci indicative of DNA double-strand breaks (DSBs); however, relative to wild-type cells, the BLM-deficient cells exhibited delayed repair of formaldehyde-induced DSBs. In response to formaldehyde exposure, we observed co-localization of 53BP1 and BLM foci at the DSB repair site, where ATM-dependent accumulation of formaldehyde-induced BLM foci occurred after the recruitment of 53BP1. Together, these findings highlight the significance of functional interactions among ATM, 53BP1, and BLM proteins as responders associated with the repair and tolerance mechanisms induced by formaldehyde.
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Affiliation(s)
- Anuradha Kumari
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239 USA; Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239 USA
| | - Nichole Owen
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239 USA
| | - Eleonora Juarez
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239 USA
| | - Amanda K McCullough
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239 USA; Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239 USA.
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Sato K, Ishiai M, Takata M, Kurumizaka H. Defective FANCI binding by a fanconi anemia-related FANCD2 mutant. PLoS One 2014; 9:e114752. [PMID: 25489943 PMCID: PMC4260917 DOI: 10.1371/journal.pone.0114752] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 11/13/2014] [Indexed: 12/24/2022] Open
Abstract
FANCD2 is a product of one of the genes associated with Fanconi anemia (FA), a rare recessive disease characterized by bone marrow failure, skeletal malformations, developmental defects, and cancer predisposition. FANCD2 forms a complex with FANCI (ID complex) and is monoubiquitinated, which facilitates the downstream interstrand crosslink (ICL) repair steps, such as ICL unhooking and nucleolytic end resection. In the present study, we focused on the chicken FANCD2 (cFANCD2) mutant harboring the Leu234 to Arg (L234R) substitution. cFANCD2 L234R corresponds to the human FANCD2 L231R mutation identified in an FA patient. We found that cFANCD2 L234R did not complement the defective ICL repair in FANCD2−/− DT40 cells. Purified cFANCD2 L234R did not bind to chicken FANCI, and its monoubiquitination was significantly deficient, probably due to the abnormal ID complex formation. In addition, the histone chaperone activity of cFANCD2 L234R was also defective. These findings may explain some aspects of Fanconi anemia pathogenesis by a FANCD2 missense mutation.
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Affiliation(s)
- Koichi Sato
- Laboratory of Structural Biology, Graduate School of Advanced Science & Engineering, Waseda University, Tokyo, Japan
| | - Masamichi Ishiai
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science & Engineering, Waseda University, Tokyo, Japan
- * E-mail:
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Chaudhury I, Sareen A, Raghunandan M, Sobeck A. FANCD2 regulates BLM complex functions independently of FANCI to promote replication fork recovery. Nucleic Acids Res 2013; 41:6444-59. [PMID: 23658231 PMCID: PMC3711430 DOI: 10.1093/nar/gkt348] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Fanconi Anemia (FA) and Bloom Syndrome share overlapping phenotypes including spontaneous chromosomal abnormalities and increased cancer predisposition. The FA protein pathway comprises an upstream core complex that mediates recruitment of two central players, FANCD2 and FANCI, to sites of stalled replication forks. Successful fork recovery depends on the Bloom’s helicase BLM that participates in a larger protein complex (‘BLMcx’) containing topoisomerase III alpha, RMI1, RMI2 and replication protein A. We show that FANCD2 is an essential regulator of BLMcx functions: it maintains BLM protein stability and is crucial for complete BLMcx assembly; moreover, it recruits BLMcx to replicating chromatin during normal S-phase and mediates phosphorylation of BLMcx members in response to DNA damage. During replication stress, FANCD2 and BLM cooperate to promote restart of stalled replication forks while suppressing firing of new replication origins. In contrast, FANCI is dispensable for FANCD2-dependent BLMcx regulation, demonstrating functional separation of FANCD2 from FANCI.
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Affiliation(s)
- Indrajit Chaudhury
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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11
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Hinz JM. Role of homologous recombination in DNA interstrand crosslink repair. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:582-603. [PMID: 20658649 DOI: 10.1002/em.20577] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Homologous recombination repair (HRR) encompasses mechanisms that employ homologous DNA sequences as templates for repair or tolerance of a wide range of DNA lesions that inhibit DNA replication in S phase. Arguably the most imposing of these DNA lesions is that of the interstrand crosslink (ICL), consisting of a covalently attached chemical bridge between opposing DNA strands. ICL repair requires the coordinated activities of HRR and a number of proteins from other DNA repair and damage response systems, including nucleotide excision repair, base excision repair, mismatch repair, and translesion DNA synthesis (TLS). Interestingly, different organisms favor alternative methods of HRR in the ICL repair process. E. coli perform ICL repair using a homology-driven damage bypass mechanism analogous to daughter strand gap repair. Eukaryotes from yeast to humans initiate ICL repair primarily during DNA replication, relying on HRR activity to restart broken replication forks associated with double-strand break intermediates induced by nucleolytic activities of other excision repair factors. Higher eukaryotes also employ several additional factors, including members of the Fanconi anemia damage-response network, which further promote replication-associated ICL repair through the activation and coordination of various DNA excision repair, TLS, and HRR proteins. This review focuses on the proteins and general mechanisms of HRR associated with ICL repair in different model organisms.
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Affiliation(s)
- John M Hinz
- School of Molecular Biosciences, Washington State University, Pullman, Washington, USA.
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