151
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Liu T, Ghosal G, Yuan J, Chen J, Huang J. FAN1 Acts with FANCI-FANCD2 to Promote DNA Interstrand Cross-Link Repair. Science 2010; 329:693-6. [DOI: 10.1126/science.1192656] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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152
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Genetic disruption of both Fancc and Fancg in mice recapitulates the hematopoietic manifestations of Fanconi anemia. Blood 2010; 116:2915-20. [PMID: 20606166 DOI: 10.1182/blood-2009-08-240747] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Fanconi anemia (FA) is an inherited chromosomal instability syndrome characterized by bone marrow failure, myelodysplasia (MDS), and acute myeloid leukemia (AML). Eight FA proteins associate in a nuclear core complex to monoubiquitinate FANCD2/FANCI in response to DNA damage. Additional functions have been described for some of the core complex proteins; however, in vivo genetic proof has been lacking. Here we show that double-mutant Fancc(-/-);Fancg(-/-) mice develop spontaneous hematologic sequelae including bone marrow failure, AML, MDS and complex random chromosomal abnormalities that the single-mutant mice do not. This genetic model provides evidence for unique core complex protein function independent of their ability to monoubiquitinate FANCD2/FANCI. Importantly, this model closely recapitulates the phenotypes found in FA patients and may be useful as a preclinical platform to evaluate the molecular pathogenesis of spontaneous bone marrow failure, MDS and AML in FA.
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153
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Andreson BL, Gupta A, Georgieva BP, Rothstein R. The ribonucleotide reductase inhibitor, Sml1, is sequentially phosphorylated, ubiquitylated and degraded in response to DNA damage. Nucleic Acids Res 2010; 38:6490-501. [PMID: 20566477 PMCID: PMC2965251 DOI: 10.1093/nar/gkq552] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Regulation of ribonucleotide reductase (RNR) is important for cell survival and genome integrity in the face of genotoxic stress. The Mec1/Rad53/Dun1 DNA damage response kinase cascade exhibits multifaceted controls over RNR activity including the regulation of the RNR inhibitor, Sml1. After DNA damage, Sml1 is degraded leading to the up-regulation of dNTP pools by RNR. Here, we probe the requirements for Sml1 degradation and identify several sites required for in vivo phosphorylation and degradation of Sml1 in response to DNA damage. Further, in a strain containing a mutation in Rnr1, rnr1-W688G, mutation of these sites in Sml1 causes lethality. Degradation of Sml1 is dependent on the 26S proteasome. We also show that degradation of phosphorylated Sml1 is dependent on the E2 ubiquitin-conjugating enzyme, Rad6, the E3 ubiquitin ligase, Ubr2, and the E2/E3-interacting protein, Mub1, which form a complex previously only implicated in the ubiquitylation of Rpn4.
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Affiliation(s)
- Bethany L Andreson
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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154
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Abstract
Post-translational modification by ubiquitin is best known for its role in targeting its substrates for regulated degradation. However, non-proteolytic functions of the ubiquitin system, often involving either monoubiquitylation or polyubiquitylation through Lys63-linked chains, have emerged in various cell signalling pathways. These two forms of the ubiquitin signal contribute to three different pathways related to the maintenance of genome integrity that are responsible for the processing of DNA double-strand breaks, the repair of interstrand cross links and the bypass of lesions during DNA replication.
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155
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Abstract
The study of rare genetic diseases can lead to insights into the cause and treatment of common diseases. An example is the rare chromosomal instability disorder, Fanconi Anemia (FA). Studies of this disease have elucidated general mechanisms of bone marrow failure, cancer pathogenesis, and resistance to chemotherapy. The principal features of FA are aplastic anemia in childhood, susceptibility to cancer or leukemia, and hypersensitivity of FA cells to DNA cross-linking agents. There are thirteen FA genes, and one of these genes is identical to the well known breast cancer susceptibility gene, BRCA2. The corresponding FA proteins cooperate in the recognition and repair of damaged DNA. Inactivation of FA genes occurs not only in FA patients but also in a variety of cancers in the general population. These findings have broad implications for predicting the sensitivity and resistance of tumors to conventional anti-cancer agents, to inhibitors of poly-ADP ribose polymerase 1, an enzyme involved in DNA repair, and to other inhibitors of DNA repair.
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Affiliation(s)
- Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Children's Hospital, and Harvard Medical School, Boston, MA 02115, USA.
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156
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Cui L, Li W. Role of ubiquitination in meiotic recombination repair. SCIENCE CHINA-LIFE SCIENCES 2010; 53:447-54. [PMID: 20596910 DOI: 10.1007/s11427-010-0052-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 01/04/2010] [Indexed: 11/28/2022]
Abstract
Programmed and unprogrammed double-strand breaks (DSBs) often arise from such physiological requirements as meiotic recombination, and exogenous insults, such as ionizing radiation (IR). Due to deleterious impacts on genome stability, DSBs must be appropriately processed and repaired in a regulatory manner. Recent investigations have indicated that ubiquitination is a critical factor in DNA damage response and meiotic recombination repair. This review summarizes the effects of proteins and complexes associated with ubiquitination with regard to homologous recombination (HR)-dependent DSB repair.
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Affiliation(s)
- Li Cui
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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157
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Martinon F, Chen X, Lee AH, Glimcher LH. TLR activation of the transcription factor XBP1 regulates innate immune responses in macrophages. Nat Immunol 2010; 11:411-8. [PMID: 20351694 PMCID: PMC3113706 DOI: 10.1038/ni.1857] [Citation(s) in RCA: 767] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 02/22/2010] [Indexed: 02/06/2023]
Abstract
Sensors of pathogens, such as Toll-like receptors (TLRs), detect microbes to activate transcriptional programs that orchestrate adaptive responses to specific insults. Here we report that TLR4 and TLR2 specifically activated the endoplasmic reticulum (ER) stress sensor kinase IRE1alpha and its downstream target, the transcription factor XBP1. Previously described ER-stress target genes of XBP1 were not induced by TLR signaling. Instead, TLR-activated XBP1 was required for optimal and sustained production of proinflammatory cytokines in macrophages. Consistent with that finding, activation of IRE1alpha by ER stress acted in synergy with TLR activation for cytokine production. Moreover, XBP1 deficiency resulted in a much greater bacterial burden in mice infected with the TLR2-activating human intracellular pathogen Francisella tularensis. Our findings identify an unsuspected critical function for XBP1 in mammalian host defenses.
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Affiliation(s)
- Fabio Martinon
- Dept. of Immunology and Infectious Diseases, Harvard School of Public Health, 651 Huntington Ave, Boston, MA 02115, USA
| | - Xi Chen
- Dept. of Immunology and Infectious Diseases, Harvard School of Public Health, 651 Huntington Ave, Boston, MA 02115, USA
| | - Ann-Hwee Lee
- Dept. of Immunology and Infectious Diseases, Harvard School of Public Health, 651 Huntington Ave, Boston, MA 02115, USA
- Dept of Medicine, MIT and Harvard, Harvard Medical School, 651 Huntington Ave, Boston, MA 02115, USA
| | - Laurie H. Glimcher
- Dept. of Immunology and Infectious Diseases, Harvard School of Public Health, 651 Huntington Ave, Boston, MA 02115, USA
- Dept of Medicine, MIT and Harvard, Harvard Medical School, 651 Huntington Ave, Boston, MA 02115, USA
- Ragon Institute of MGH, MIT and Harvard, Harvard Medical School, 651 Huntington Ave, Boston, MA 02115, USA
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158
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Lee KY, Chung KY, Koo HS. The involvement of FANCM, FANCI, and checkpoint proteins in the interstrand DNA crosslink repair pathway is conserved in C. elegans. DNA Repair (Amst) 2010; 9:374-82. [PMID: 20075016 DOI: 10.1016/j.dnarep.2009.12.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 11/28/2009] [Accepted: 12/17/2009] [Indexed: 10/20/2022]
Abstract
Fanconi anemia (FA) patients are specifically defective in the repair of interstrand DNA crosslinks (ICLs), a complex process involving at least 13 FA proteins and other repair/checkpoint proteins. Of the 13 FA proteins, FANCD1/BRCA2, FANCD2, and FANCJ were previously found to be functionally conserved in C. elegans. We have also identified C. elegans homologs of FANCM and FANCI, and determined their epistatic relationships with homologs of FANCD2, checkpoint proteins, and RAD51 upon DNA crosslinking. The counterparts of FANCM, FANCI, and three checkpoint proteins (RPA, ATR and CHK1) are required for focus formation and ubiquitination associated with FANCD2 in C. elegans. However, C. elegans FANCM affects neither RPA focus formation nor CHK1 phosphorylation induced by ICLs, unlike the reported role of human FANCM, which influences ATR-CHK1 signaling at stalled replication forks. Although focus formation by both FANCD2 and RAD51 requires ATR-CHK1 signaling, FANCD2 and RAD51 acted independently in the formation of their respective foci. Thus, the FANCD2 activation pathway involving FANCM, FANCI, and the checkpoint proteins is conserved in C. elegans but with distinct differences.
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Affiliation(s)
- Kyong Yun Lee
- Department of Biochemistry, Yonsei University, Seodaemun-ku, Seoul, Republic of Korea
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159
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Landais I, Hiddingh S, McCarroll M, Yang C, Sun A, Turker MS, Snyder JP, Hoatlin ME. Monoketone analogs of curcumin, a new class of Fanconi anemia pathway inhibitors. Mol Cancer 2009; 8:133. [PMID: 20043851 PMCID: PMC2807854 DOI: 10.1186/1476-4598-8-133] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 12/31/2009] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The Fanconi anemia (FA) pathway is a multigene DNA damage response network implicated in the repair of DNA lesions that arise during replication or after exogenous DNA damage. The FA pathway displays synthetic lethal relationship with certain DNA repair genes such as ATM (Ataxia Telangectasia Mutated) that are frequently mutated in tumors. Thus, inhibition of FANCD2 monoubiquitylation (FANCD2-Ub), a key step in the FA pathway, might target tumor cells defective in ATM through synthetic lethal interaction. Curcumin was previously identified as a weak inhibitor of FANCD2-Ub. The aim of this study is to identify derivatives of curcumin with better activity and specificity. RESULTS Using a replication-free assay in Xenopus extracts, we screened monoketone analogs of curcumin for inhibition of FANCD2-Ub and identified analog EF24 as a strong inhibitor. Mechanistic studies suggest that EF24 targets the FA pathway through inhibition of the NF-kB pathway kinase IKK. In HeLa cells, nanomolar concentrations of EF24 inhibited hydroxyurea (HU)-induced FANCD2-Ub and foci in a cell-cycle independent manner. Survival assays revealed that EF24 specifically sensitizes FA-competent cells to the DNA crosslinking agent mitomycin C (MMC). In addition, in contrast with curcumin, ATM-deficient cells are twofold more sensitive to EF24 than matched wild-type cells, consistent with a synthetic lethal effect between FA pathway inhibition and ATM deficiency. An independent screen identified 4H-TTD, a compound structurally related to EF24 that displays similar activity in egg extracts and in cells. CONCLUSIONS These results suggest that monoketone analogs of curcumin are potent inhibitors of the FA pathway and constitute a promising new class of targeted anticancer compounds.
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Affiliation(s)
- Igor Landais
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, USA.
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160
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Abstract
Fanconi Anemia (FA) is an inherited genomic instability disorder, caused by mutations in genes regulating replication-dependent removal of interstrand DNA crosslinks. The Fanconi Anemia pathway is thought to coordinate a complex mechanism that enlists elements of three classic DNA repair pathways, namely homologous recombination, nucleotide excision repair, and mutagenic translesion synthesis, in response to genotoxic insults. To this end, the Fanconi Anemia pathway employs a unique nuclear protein complex that ubiquitinates FANCD2 and FANCI, leading to formation of DNA repair structures. Lack of obvious enzymatic activities among most FA members has made it challenging to unravel its precise modus operandi. Here we review the current understanding of how the Fanconi Anemia pathway components participate in DNA repair and discuss the mechanisms that regulate this pathway to ensure timely, efficient, and correct restoration of chromosomal integrity.
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Affiliation(s)
- George-Lucian Moldovan
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
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161
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Knipscheer P, Räschle M, Smogorzewska A, Enoiu M, Ho TV, Schärer OD, Elledge SJ, Walter JC. The Fanconi anemia pathway promotes replication-dependent DNA interstrand cross-link repair. Science 2009; 326:1698-701. [PMID: 19965384 DOI: 10.1126/science.1182372] [Citation(s) in RCA: 392] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fanconi anemia is a human cancer predisposition syndrome caused by mutations in 13 Fanc genes. The disorder is characterized by genomic instability and cellular hypersensitivity to chemicals that generate DNA interstrand cross-links (ICLs). A central event in the activation of the Fanconi anemia pathway is the mono-ubiquitylation of the FANCI-FANCD2 complex, but how this complex confers ICL resistance remains enigmatic. Using a cell-free system, we showed that FANCI-FANCD2 is required for replication-coupled ICL repair in S phase. Removal of FANCD2 from extracts inhibits both nucleolytic incisions near the ICL and translesion DNA synthesis past the lesion. Reversal of these defects requires ubiquitylated FANCI-FANCD2. Our results show that multiple steps of the essential S-phase ICL repair mechanism fail when the Fanconi anemia pathway is compromised.
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Affiliation(s)
- Puck Knipscheer
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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162
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Kinoshita E, Kinoshita-Kikuta E, Ujihara H, Koike T. Mobility shift detection of phosphorylation on large proteins using a Phos-tag SDS-PAGE gel strengthened with agarose. Proteomics 2009; 9:4098-101. [PMID: 19658103 DOI: 10.1002/pmic.200900020] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We describe a novel technique of phosphate-affinity SDS-PAGE using Phos-tag to analyze large phosphoproteins with molecular masses of more than 200 kDa. The protein phosphoisotypes were clearly separated as up-shifted migration bands in a 3% w/v polyacrylamide gel containing 20 microM Phos-tag and 0.5% w/v agarose. In subsequent immunoblotting, the procedure permitted the determination of the phosphoisotypes of high-molecular-mass proteins, such as mTOR (289 kDa), ATM kinase (350 kDa), and 53BP1 (213 kDa).
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Affiliation(s)
- Eiji Kinoshita
- Department of Functional Molecular Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8553, Japan.
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163
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Zhi G, Wilson JB, Chen X, Krause DS, Xiao Y, Jones NJ, Kupfer GM. Fanconi anemia complementation group FANCD2 protein serine 331 phosphorylation is important for fanconi anemia pathway function and BRCA2 interaction. Cancer Res 2009; 69:8775-83. [PMID: 19861535 DOI: 10.1158/0008-5472.can-09-2312] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Fanconi anemia is a cancer-prone inherited bone marrow failure and cancer susceptibility syndrome with at least 13 complementation groups (FANCA, FANCB, FANCC, FANCD1, FANCD2, FANCE, FANCF, FANCG, FANCI, FANCJ, FANCL, FANCM, and FANCN). Our laboratory has previously described several regulatory phosphorylation events for core complex member proteins FANCG and FANCA by phosphorylation. In this study, we report a novel phosphorylation site serine 331 (S331) of FANCD2, the pivotal downstream player of the Fanconi anemia pathway. Phosphorylation of S331 is important for its DNA damage-inducible monoubiquitylation, resistance to DNA cross-linkers, and in vivo interaction with FANCD1/BRCA2. A phosphomimetic mutation at S331 restores all of these phenotypes to wild-type. In vitro and in vivo experiments show that phosphorylation of S331 is mediated by CHK1, the S-phase checkpoint kinase implicated in the Fanconi anemia DNA repair pathway.
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Affiliation(s)
- Gang Zhi
- Department of Microbiology, University of Virginia Health System, Charlottesville, Virginia, USA
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164
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Gari K, Constantinou A. The role of the Fanconi anemia network in the response to DNA replication stress. Crit Rev Biochem Mol Biol 2009; 44:292-325. [PMID: 19728769 DOI: 10.1080/10409230903154150] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Fanconi anemia is a genetically heterogeneous disorder associated with chromosome instability and a highly elevated risk for developing cancer. The mutated genes encode proteins involved in the cellular response to DNA replication stress. Fanconi anemia proteins are extensively connected with DNA caretaker proteins, and appear to function as a hub for the coordination of DNA repair with DNA replication and cell cycle progression. At a molecular level, however, the raison d'être of Fanconi anemia proteins still remains largely elusive. The thirteen Fanconi anemia proteins identified to date have not been embraced into a single and defined biological process. To help put the Fanconi anemia puzzle into perspective, we begin this review with a summary of the strategies employed by prokaryotes and eukaryotes to tolerate obstacles to the progression of replication forks. We then summarize what we know about Fanconi anemia with an emphasis on biochemical aspects, and discuss how the Fanconi anemia network, a late acquisition in evolution, may function to permit the faithful and complete duplication of our very large vertebrate chromosomes.
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Affiliation(s)
- Kerstin Gari
- DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, UK
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165
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Abstract
Each of the thirteen identified Fanconi anemia (FA) genes is required for resistance to DNA interstrand crosslinking agents, such as mitomycin C, cisplatin, and melphalan. While these agents are excellent tools for understanding the function of FA proteins in DNA repair, it is uncertain whether a defect in the removal of DNA interstrand crosslinks (ICLs) is the basis for the pathophysiology of FA. For example, DNA interstrand crosslinking agents induce other types of DNA damage, in addition to ICLs. Further, other DNA-damaging agents, such as ionizing or ultraviolet radiation, activate the FA pathway, leading to monoubiquitination of FANCD2 and FANCI. Also, FA patients display congenital abnormalities, hematologic deficiencies, and a predisposition to cancer in the absence of an environmental source of ICLs that is external to cells. Here we consider potential sources of endogenous DNA damage, or endogenous stresses, to which FA proteins may respond. These include ICLs formed by products of lipid peroxidation, and other forms of oxidative DNA damage. FA proteins may also potentially respond to telomere shortening or replication stress. Defining these endogenous sources of DNA damage or stresses is critical for understanding the pathogenesis of deficiencies for FA proteins.We propose that FA proteins are centrally involved in the response to replication stress, including replication stress arising from oxidative DNA damage.
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Affiliation(s)
- Qishen Pang
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Research Foundation, Cincinnati, OH 45229, United States
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166
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Abstract
We provide a standard phosphate-affinity SDS-PAGE (Mn(2+)-Phos-tag SDS-PAGE) protocol, in which Phos-tag is used to analyze large phosphoproteins with molecular masses of more than 200 kDa. A previous protocol required a long electrophoresis time of 12 h for separation of phosphoisotypes of large proteins ( approximately 150 kDa). This protocol, which uses a 3% (wt/vol) polyacrylamide gel strengthened with 0.5% (wt/vol) agarose, permits the separation of protein phosphoisotypes larger than 200 kDa within 2 h. In subsequent immunoblotting, phosphoisotypes of high-molecular-mass proteins, such as mammalian target of rapamycin (289 kDa), ataxia telangiectasia-mutated kinase (350 kDa) and p53-binding protein 1 (213 kDa), can be clearly detected as up-shifted migration bands on the improved Mn(2+)-Phos-tag SDS-PAGE gel. The procedure from the beginning of gel preparation to the end of electrophoresis requires about 4 h in this protocol.
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167
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yFACT induces global accessibility of nucleosomal DNA without H2A-H2B displacement. Mol Cell 2009; 35:716-23. [PMID: 19683499 DOI: 10.1016/j.molcel.2009.06.034] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Revised: 03/25/2009] [Accepted: 06/19/2009] [Indexed: 12/22/2022]
Abstract
FACT has been proposed to function by displacing H2A-H2B dimers from nucleosomes to form hexasomes. Results described here with yeast FACT (yFACT) suggest instead that nucleosomes are reorganized to a form with the original composition but a looser, more dynamic structure. First, yFACT enhances hydroxyl radical accessibility and endonuclease digestion in vitro at sites throughout the nucleosome, not just in regions contacted by H2A-H2B. Accessibility increases dramatically, but the DNA remains partially protected. Second, increased nuclease sensitivity can occur without displacement of dimers from the nucleosome. Third, yFACT is required for eviction of nucleosomes from the GAL1-10 promoter during transcriptional activation in vivo, but the preferential reduction in dimer occupancy expected for hexasome formation is not observed. We propose that yFACT promotes a reversible transition between two nucleosomal forms, and that this activity contributes to the establishment and maintenance of the chromatin barrier as well as to overcoming it.
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168
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García MJ, Fernández V, Osorio A, Barroso A, Fernández F, Urioste M, Benítez J. Mutational analysis of FANCL, FANCM and the recently identified FANCI suggests that among the 13 known Fanconi Anemia genes, only FANCD1/BRCA2 plays a major role in high-risk breast cancer predisposition. Carcinogenesis 2009; 30:1898-902. [PMID: 19737859 DOI: 10.1093/carcin/bgp218] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fanconi Anemia (FA) is a rare recessive syndrome characterized by cellular hypersensitivity to DNA-cross-linking agents. To date, 13 FA complementation groups have been described and all 13 genes associated to each of these groups have been currently identified. Three of the known FA genes are also high-risk (FANCD1/BRCA2) or moderate-risk (FANCN/PALB2 and FANCJ/BRIP1) breast cancer susceptibility genes, which makes all members of the FA pathway particularly attractive breast cancer candidate genes. Most FA genes have been screened for mutations in breast cancer families negative for BRCA1/2 mutations but the role of FANCL, FANCM and the recently identified FANCI has not been evaluated to date. 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. We identified 68 sequence variants of which 24 were coding and 44 non-coding. Six exonic and 26 non-coding variants had not been described previously. None of the coding changes caused clearly pathogenic changes and computational analysis of all non-described intronic variants did not revealed major impact in splicing. With the present study, all known FA genes have been evaluated within the context of breast cancer high-risk predisposition. Our results rule out a major role of FANCI, FANCL and FANCM in familial breast cancer susceptibility, suggesting that among the 13 known FA genes, only FANCD1/BRCA2 plays a major role in high-risk breast cancer predisposition.
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Affiliation(s)
- María J García
- Group of Human Genetics, Human Cancer Genetics Program, Spanish National Cancer Centre (CNIO), C/ Melchor Fernández Almagro 3, 28029 Madrid, Spain.
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169
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Roques C, Coulombe Y, Delannoy M, Vignard J, Grossi S, Brodeur I, Rodrigue A, Gautier J, Stasiak AZ, Stasiak A, Constantinou A, Masson JY. MRE11-RAD50-NBS1 is a critical regulator of FANCD2 stability and function during DNA double-strand break repair. EMBO J 2009; 28:2400-13. [PMID: 19609304 PMCID: PMC2735166 DOI: 10.1038/emboj.2009.193] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 06/17/2009] [Indexed: 01/04/2023] Open
Abstract
Monoubiquitination of the Fanconi anaemia protein FANCD2 is a key event leading to repair of interstrand cross-links. It was reported earlier that FANCD2 co-localizes with NBS1. However, the functional connection between FANCD2 and MRE11 is poorly understood. In this study, we show that inhibition of MRE11, NBS1 or RAD50 leads to a destabilization of FANCD2. FANCD2 accumulated from mid-S to G2 phase within sites containing single-stranded DNA (ssDNA) intermediates, or at sites of DNA damage, such as those created by restriction endonucleases and laser irradiation. Purified FANCD2, a ring-like particle by electron microscopy, preferentially bound ssDNA over various DNA substrates. Inhibition of MRE11 nuclease activity by Mirin decreased the number of FANCD2 foci formed in vivo. We propose that FANCD2 binds to ssDNA arising from MRE11-processed DNA double-strand breaks. Our data establish MRN as a crucial regulator of FANCD2 stability and function in the DNA damage response.
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Affiliation(s)
- Céline Roques
- Genome Stability Laboratory, Laval University Cancer Research Center, Hôtel-Dieu de Québec, Québec, Canada
| | - Yan Coulombe
- Genome Stability Laboratory, Laval University Cancer Research Center, Hôtel-Dieu de Québec, Québec, Canada
| | - Mathieu Delannoy
- Department of Biochemistry, University of Lausanne, BIL Biomedical Research Center, Lausanne, Switzerland
| | - Julien Vignard
- Genome Stability Laboratory, Laval University Cancer Research Center, Hôtel-Dieu de Québec, Québec, Canada
| | - Simona Grossi
- Department of Biochemistry, University of Lausanne, BIL Biomedical Research Center, Lausanne, Switzerland
| | - Isabelle Brodeur
- Genome Stability Laboratory, Laval University Cancer Research Center, Hôtel-Dieu de Québec, Québec, Canada
| | - Amélie Rodrigue
- Genome Stability Laboratory, Laval University Cancer Research Center, Hôtel-Dieu de Québec, Québec, Canada
| | - Jean Gautier
- Columbia University, Institute for Cancer Genetics, Irving Cancer Research Center, New York, NY, USA
| | - Alicja Z Stasiak
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Andrzej Stasiak
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Angelos Constantinou
- Department of Biochemistry, University of Lausanne, BIL Biomedical Research Center, Lausanne, Switzerland
| | - Jean-Yves Masson
- Genome Stability Laboratory, Laval University Cancer Research Center, Hôtel-Dieu de Québec, Québec, Canada
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170
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de Winter JP, Joenje H. The genetic and molecular basis of Fanconi anemia. Mutat Res 2009; 668:11-19. [PMID: 19061902 DOI: 10.1016/j.mrfmmm.2008.11.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 10/28/2008] [Accepted: 11/06/2008] [Indexed: 05/27/2023]
Abstract
The capacity to maintain genomic integrity is shared by all living organisms. Multiple pathways are distinguished that safeguard genomic stability, most of which have originated in primitive life forms. In human individuals, defects in these pathways are typically associated with cancer proneness. The Fanconi anemia pathway, one of these pathways, has evolved relatively late during evolution and exists - in its fully developed form - only in vertebrates. This pathway, in which thus far 13 distinct proteins have been shown to participate, appears essential for error-free DNA replication. Inactivating mutations in the corresponding genes underlie the recessive disease Fanconi anemia (FA). In the last decade the genetic basis of this disorder has been uncovered by a variety of approaches, including complementation cloning, genetic linkage analysis and protein association studies. Here we review these approaches, introduce the encoded proteins, and discuss their possible role in ensuring genomic integrity.
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Affiliation(s)
- Johan P de Winter
- Department of Clinical Genetics, Section Oncogenetics, VU University Medical Center, Van der Boechorststraat 7, Amsterdam 1081 BT, The Netherlands.
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171
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Thompson LH, Hinz JM. Cellular and molecular consequences of defective Fanconi anemia proteins in replication-coupled DNA repair: mechanistic insights. Mutat Res 2009; 668:54-72. [PMID: 19622404 PMCID: PMC2714807 DOI: 10.1016/j.mrfmmm.2009.02.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 01/20/2009] [Accepted: 02/10/2009] [Indexed: 12/13/2022]
Abstract
The Fanconi anemia (FA) molecular network consists of 15 "FANC" proteins, of which 13 are associated with mutations in patients with this cancer-prone chromosome instability disorder. Whereas historically the common phenotype associated with FA mutations is marked sensitivity to DNA interstrand crosslinking agents, the literature supports a more global role for FANC proteins in coping with diverse stresses encountered by replicative polymerases. We have attempted to reconcile and integrate numerous observations into a model in which FANC proteins coordinate the following physiological events during DNA crosslink repair: (a) activating a FANCM-ATR-dependent S-phase checkpoint, (b) mediating enzymatic replication-fork breakage and crosslink unhooking, (c) filling the resulting gap by translesion synthesis (TLS) by error-prone polymerase(s), and (d) restoring the resulting one-ended double-strand break by homologous recombination repair (HRR). The FANC core subcomplex (FANCA, B, C, E, F, G, L, FAAP100) promotes TLS for both crosslink and non-crosslink damage such as spontaneous oxidative base damage, UV-C photoproducts, and alkylated bases. TLS likely helps prevent stalled replication forks from breaking, thereby maintaining chromosome continuity. Diverse DNA damages and replication inhibitors result in monoubiquitination of the FANCD2-FANCI complex by the FANCL ubiquitin ligase activity of the core subcomplex upon its recruitment to chromatin by the FANCM-FAAP24 heterodimeric translocase. We speculate that this translocase activity acts as the primary damage sensor and helps remodel blocked replication forks to facilitate checkpoint activation and repair. Monoubiquitination of FANCD2-FANCI is needed for promoting HRR, in which the FANCD1/BRCA2 and FANCN/PALB2 proteins act at an early step. We conclude that the core subcomplex is required for both TLS and HRR occurring separately for non-crosslink damages and for both events during crosslink repair. The FANCJ/BRIP1/BACH1 helicase functions in association with BRCA1 and may remove structural barriers to replication, such as guanine quadruplex structures, and/or assist in crosslink unhooking.
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Affiliation(s)
- Larry H Thompson
- Biology and Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States.
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172
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Longerich S, San Filippo J, Liu D, Sung P. FANCI binds branched DNA and is monoubiquitinated by UBE2T-FANCL. J Biol Chem 2009; 284:23182-6. [PMID: 19589784 DOI: 10.1074/jbc.c109.038075] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FANCI is integral to the Fanconi anemia (FA) pathway of DNA damage repair. Upon the occurrence of DNA damage, FANCI becomes monoubiquitinated on Lys-523 and relocalizes to chromatin, where it functions with monoubiquitinated FANCD2 to facilitate DNA repair. We show that FANCI and its C-terminal fragment possess a DNA binding activity that prefers branched structures. We also demonstrate that FANCI can be ubiquitinated on Lys-523 by the UBE2T-FANCL pair in vitro. These findings should facilitate future efforts directed at elucidating molecular aspects of the FA pathway.
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Affiliation(s)
- Simonne Longerich
- Department of Molecular Biophysics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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173
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Yuan F, El Hokayem J, Zhou W, Zhang Y. FANCI protein binds to DNA and interacts with FANCD2 to recognize branched structures. J Biol Chem 2009; 284:24443-52. [PMID: 19561358 PMCID: PMC2782037 DOI: 10.1074/jbc.m109.016006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In this study, we report that the purified wild-type FANCI (Fanconi anemia complementation group I) protein directly binds to a variety of DNA substrates. The DNA binding domain roughly encompasses residues 200–1000, as suggested by the truncation study. When co-expressed in insect cells, a small fraction of FANCI forms a stable complex with FANCD2 (Fanconi anemia complementation group D2). Intriguingly, the purified FANCI-FANCD2 complex preferentially binds to the branched DNA structures when compared with either FANCI or FANCD2 alone. Co-immunoprecipitation with purified proteins indicates that FANCI interacts with FANCD2 through its C-terminal amino acid 1001–1328 fragment. Although the C terminus of FANCI is dispensable for direct DNA binding, it seems to be involved in the regulation of DNA binding activity. This notion is further enhanced by two C-terminal point mutations, R1285Q and D1301A, which showed differentiated DNA binding activity. We also demonstrate that FANCI forms discrete nuclear foci in HeLa cells in the absence or presence of exogenous DNA damage. The FANCI foci are colocalized perfectly with FANCD2 and partially with proliferating cell nuclear antigen irrespective of mitomycin C treatment. An increased number of FANCI foci form and become resistant to Triton X extraction in response to mitomycin C treatment. Our data suggest that the FANCI-FANCD2 complex may participate in repair of damaged replication forks through its preferential recognition of branched structures.
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Affiliation(s)
- Fenghua Yuan
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
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174
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Rosado IV, Niedzwiedz W, Alpi AF, Patel KJ. The Walker B motif in avian FANCM is required to limit sister chromatid exchanges but is dispensable for DNA crosslink repair. Nucleic Acids Res 2009; 37:4360-70. [PMID: 19465393 PMCID: PMC2715236 DOI: 10.1093/nar/gkp365] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
FANCM, the most highly conserved component of the Fanconi Anaemia (FA) pathway can resolve recombination intermediates and remodel synthetic replication forks. However, it is not known if these activities are relevant to how this conserved protein activates the FA pathway and promotes DNA crosslink repair. Here we use chicken DT40 cells to systematically dissect the function of the helicase and nuclease domains of FANCM. Our studies reveal that these domains contribute distinct roles in the tolerance of crosslinker, UV light and camptothecin-induced DNA damage. Although the complete helicase domain is critical for crosslink repair, a predicted inactivating mutation of the Walker B box domain has no impact on FA pathway associated functions. However, this mutation does result in elevated sister chromatid exchanges (SCE). Furthermore, our genetic dissection indicates that FANCM functions with the Blm helicase to suppress spontaneous SCE events. Overall our results lead us to reappraise the role of helicase domain associated activities of FANCM with respect to the activation of the FA pathway, crosslink repair and in the resolution of recombination intermediates.
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Affiliation(s)
- Ivan V Rosado
- MRC Laboratory of Molecular Biology, Hills Rd, Cambridge CB20QH, UK
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175
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Impaired FANCD2 monoubiquitination and hypersensitivity to camptothecin uniquely characterize Fanconi anemia complementation group M. Blood 2009; 114:174-80. [PMID: 19423727 DOI: 10.1182/blood-2009-02-207811] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
FANCM is a component of the Fanconi anemia (FA) core complex and one FA patient (EUFA867) with biallelic mutations in FANCM has been described. Strikingly, we found that EUFA867 also carries biallelic mutations in FANCA. After correcting the FANCA defect in EUFA867 lymphoblasts, a "clean" FA-M cell line was generated. These cells were hypersensitive to mitomycin C, but unlike cells defective in other core complex members, FANCM(-/-) cells were proficient in monoubiquitinating FANCD2 and were sensitive to the topoisomerase inhibitor camptothecin, a feature shared only with the FA subtype D1 and N. In addition, FANCM(-/-) cells were sensitive to UV light. FANCM and a C-terminal deletion mutant rescued the cross-linker sensitivity of FANCM(-/-) cells, whereas a FANCM ATPase mutant did not. Because both mutants restored the formation of FANCD2 foci, we conclude that FANCM functions in an FA core complex-dependent and -independent manner.
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176
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A Phos-tag-based fluorescence resonance energy transfer system for the analysis of the dephosphorylation of phosphopeptides. Anal Biochem 2009; 388:235-41. [DOI: 10.1016/j.ab.2009.02.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 01/27/2009] [Accepted: 02/28/2009] [Indexed: 11/19/2022]
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177
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Abstract
Fanconi anemia (FA) is an autosomal and X-linked recessive disorder characterized by bone marrow failure, acute myelogenous leukemia, solid tumors, and developmental abnormalities. Recent years have seen a dramatic improvement in FA patient treatment, resulting in a greater survival of children into adulthood. These improvements have been made despite the fact that a definitive cellular function for the proteins in the FA pathway has yet to be elucidated. Delineating the cellular functions of the FA pathway could help further improve the treatment options for FA patients and further reduce the probability of succumbing to the disease. This article reviews the current clinical aspects of FA including presentation, diagnosis, and treatment followed by a review of the molecular aspects of FA as they are currently understood.
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Affiliation(s)
- Allison M Green
- Section of Pediatric Hematology-Oncology, Department of Pathology, Yale University School of Medicine, 333 Cedar Street LMP 2073, PO Box 208064, New Haven, CT 06520-8064, USA
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178
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Abstract
The small protein ubiquitin is a central regulator of a cell's life and death. Ubiquitin is best known for targeting protein destruction by the 26S proteasome. In the past few years, however, nonproteolytic functions of ubiquitin have been uncovered at a rapid pace. These functions include membrane trafficking, protein kinase activation, DNA repair, and chromatin dynamics. A common mechanism underlying these functions is that ubiquitin, or polyubiquitin chains, serves as a signal to recruit proteins harboring ubiquitin-binding domains, thereby bringing together ubiquitinated proteins and ubiquitin receptors to execute specific biological functions. Recent advances in understanding ubiquitination in protein kinase activation and DNA repair are discussed to illustrate the nonproteolytic functions of ubiquitin in cell signaling.
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Affiliation(s)
- Zhijian J Chen
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
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179
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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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Mechanistic Insight into Site-Restricted Monoubiquitination of FANCD2 by Ube2t, FANCL, and FANCI. Mol Cell 2008; 32:767-77. [DOI: 10.1016/j.molcel.2008.12.003] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 09/12/2008] [Accepted: 12/03/2008] [Indexed: 11/24/2022]
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