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Fukumoto Y, Ikeuchi M, Nakayama Y, Ogra Y. Rad17 Translocates to Nucleolus upon UV Irradiation through Nucleolar Localization Signal in the Central Basic Domain. Int J Mol Sci 2022; 23:ijms232012300. [PMID: 36293155 PMCID: PMC9603387 DOI: 10.3390/ijms232012300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/08/2022] [Accepted: 10/12/2022] [Indexed: 11/04/2022] Open
Abstract
The nucleolus is a non-membranous structure in the nucleus and forms around ribosomal DNA repeats. It plays a major role in ribosomal biogenesis through the transcription of ribosomal DNA and regulates mRNA translation in response to cellular stress including DNA damage. Rad17 is one of the proteins that initiate and maintain the activation of the ATR pathway, one of the major DNA damage checkpoints. We have recently reported that the central basic domain of Rad17 contains a nuclear localization signal and that the nuclear translocation of Rad17 promotes its proteasomal degradation. Here, we show that the central basic domain contains the nucleolar localization signal as well as the nuclear localization signal. The nucleolar localization signal overlaps with the nuclear localization signal and is capable of transporting an exogenous protein into the nucleolus. Phosphomimetic mutations of the central basic domain inhibit nucleolar accumulation, suggesting that the post-translational modification sites regulate the nucleolar localization. Nucleolar accumulation of Rad17 is promoted by proteasome inhibition and UV irradiation. Our data show the nucleolar localization of Rad17 and suggest a possible role of Rad17 in the nucleolus upon UV irradiation.
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Affiliation(s)
- Yasunori Fukumoto
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
- Correspondence: ; Tel./Fax: +81-43-226-2945
| | - Masayoshi Ikeuchi
- Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Yuji Nakayama
- Department of Biochemistry & Molecular Biology, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Yasumitsu Ogra
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
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2
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Chen H, Han L, Tsai H, Wang Z, Wu Y, Duo Y, Cao W, Chen L, Tan Z, Xu N, Huang X, Zhuang J, Huang L. PICT-1 is a key nucleolar sensor in DNA damage response signaling that regulates apoptosis through the RPL11-MDM2-p53 pathway. Oncotarget 2018; 7:83241-83257. [PMID: 27829214 PMCID: PMC5347766 DOI: 10.18632/oncotarget.13082] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 10/19/2016] [Indexed: 12/12/2022] Open
Abstract
PICT-1 is an essential ribosome biogenesis factor whose loss induces p53 accumulation and apoptosis. Here, we show that DNA damage changes PICT-1 localization and decreases PICT-1 protein levels via the proteasome pathway. Two important phosphatidylinositol 3-kinase-like kinases (PIKKs), ataxia-telangiectasia mutated (ATM) and the Ku70 subunit of DNA-dependent protein kinase (DNA-PK), co-localize and interact with PICT-1 in the nucleolus. Computational prediction of phosphorylation sites and detection using an anti-phospho-substrate antibody suggest that PICT-1 might be a substrate of PIKKs. PICT-1 S233 and T289 were identified as the key phosphorylation sites in this pathway, as mutating both to alanine abolished UVB-induced increase of PICT-1 phosporylation. Inhibition of PIKKs or ATM (with wortmannin and KU55933, respectively) prevented the agglomeration and degradation of PICT-1, suggesting that ATM is a key regulator of PICT-1. PICT-1(S233A, T289A) demonstrated marked resistance to DNA damage-induced agglomeration and loss of PICT-1. Phosphomimetic PICT-1 (S233D, T289D) showed a different nuclear distribution and was more rapidly degraded after DNA damage than wild-type PICT-1. Furthermore, both phosphorylation and degradation of PICT-1 released RPL11 from the nucleolus to the nucleoplasm, increased binding of RPL11 to MDM2, and promoted p53 accumulation and apoptosis in an ATM-dependent manner after DNA damage. These data indicate that PICT-1 is a major nucleolar sensor of the DNA damage repair response and an important upstream regulator of p53 via the RPL11-MDM2-p53 pathway.
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Affiliation(s)
- Hongbo Chen
- The Shenzhen Key Lab of Gene and Antibody Therapy, Center for Biotechnology & Biomedicine, Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China.,Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Liqiao Han
- Department of Laboratory Science, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China.,The Shenzhen Key Lab of Gene and Antibody Therapy, Center for Biotechnology & Biomedicine, Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Hsiangi Tsai
- The Shenzhen Key Lab of Gene and Antibody Therapy, Center for Biotechnology & Biomedicine, Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhiwei Wang
- Department of Laboratory Medicine, The Fourth Affiliated Hospital of Guangzhou Medical University, Guangzhou 511447, China
| | - Yanping Wu
- The Shenzhen Key Lab of Gene and Antibody Therapy, Center for Biotechnology & Biomedicine, Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yanhong Duo
- The Shenzhen Key Lab of Gene and Antibody Therapy, Center for Biotechnology & Biomedicine, Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Wei Cao
- The Shenzhen Key Lab of Gene and Antibody Therapy, Center for Biotechnology & Biomedicine, Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lijun Chen
- Technology Center of Guangxi Entry-Exit Inspection and Quarantine Bureau, Nanning 530021, China
| | - Zhirong Tan
- Department of Laboratory Science, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
| | - Ning Xu
- Department of Laboratory Science, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
| | - Xianzhang Huang
- Department of Laboratory Science, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
| | - Junhua Zhuang
- Department of Laboratory Science, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
| | - Laiqiang Huang
- The Shenzhen Key Lab of Gene and Antibody Therapy, Center for Biotechnology & Biomedicine, Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.,School of Life Sciences, Tsinghua University, Beijing 100084, China
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3
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Berger CM, Gaume X, Bouvet P. The roles of nucleolin subcellular localization in cancer. Biochimie 2015; 113:78-85. [PMID: 25866190 DOI: 10.1016/j.biochi.2015.03.023] [Citation(s) in RCA: 154] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/29/2015] [Indexed: 01/10/2023]
Abstract
Nucleolin (NCL) is one of the most abundant non ribosomal protein of the nucleolus where it plays a central role in polymerase I transcription. NCL is also found outside of the nucleolus, in the nucleoplasm, cytoplasm as well as on the cell membrane. It acts in all cell compartments to control cellular homeostasis and therefore each cellular pool of NCL can play a different role in cancer development. NCL overexpression and its increased localization at the cell membrane is a common feature of several tumor cells. In cancer cells, NCL overexpression influences cell survival, proliferation and invasion through its action on different cellular pathways. In this review, we describe how the multiple functions of NCL that are associated to its multiple cellular localization can participate to the development of cancer.
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Affiliation(s)
- Caroline Madeleine Berger
- Département de Biologie, Master Biosciences, ENS de Lyon, Lyon, France; Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France
| | - Xavier Gaume
- Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France
| | - Philippe Bouvet
- Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France.
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4
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Stixová L, Sehnalová P, Legartová S, Suchánková J, Hrušková T, Kozubek S, Sorokin DV, Matula P, Raška I, Kovařík A, Fulneček J, Bártová E. HP1β-dependent recruitment of UBF1 to irradiated chromatin occurs simultaneously with CPDs. Epigenetics Chromatin 2014; 7:39. [PMID: 25587355 PMCID: PMC4293114 DOI: 10.1186/1756-8935-7-39] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 12/12/2014] [Indexed: 11/24/2022] Open
Abstract
Background The repair of spontaneous and induced DNA lesions is a multistep process. Depending on the type of injury, damaged DNA is recognized by many proteins specifically involved in distinct DNA repair pathways. Results We analyzed the DNA-damage response after ultraviolet A (UVA) and γ irradiation of mouse embryonic fibroblasts and focused on upstream binding factor 1 (UBF1), a key protein in the regulation of ribosomal gene transcription. We found that UBF1, but not nucleolar proteins RPA194, TCOF, or fibrillarin, was recruited to UVA-irradiated chromatin concurrently with an increase in heterochromatin protein 1β (HP1β) level. Moreover, Förster Resonance Energy Transfer (FRET) confirmed interaction between UBF1 and HP1β that was dependent on a functional chromo shadow domain of HP1β. Thus, overexpression of HP1β with a deleted chromo shadow domain had a dominant-negative effect on UBF1 recruitment to UVA-damaged chromatin. Transcription factor UBF1 also interacted directly with DNA inside the nucleolus but no interaction of UBF1 and DNA was confirmed outside the nucleolus, where UBF1 recruitment to DNA lesions appeared simultaneously with cyclobutane pyrimidine dimers; this occurrence was cell-cycle-independent. Conclusions We propose that the simultaneous presence and interaction of UBF1 and HP1β at DNA lesions is activated by the presence of cyclobutane pyrimidine dimers and mediated by the chromo shadow domain of HP1β. This might have functional significance for nucleotide excision repair. Electronic supplementary material The online version of this article (doi:10.1186/1756-8935-7-39) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lenka Stixová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Petra Sehnalová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Soňa Legartová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Jana Suchánková
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Tereza Hrušková
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Stanislav Kozubek
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Dmitry V Sorokin
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic ; Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Pavel Matula
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic ; Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Ivan Raška
- Institute of Cellular Biology and Pathology, the First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague, Czech Republic
| | - Aleš Kovařík
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Jaroslav Fulneček
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Eva Bártová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
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5
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Antoniali G, Lirussi L, Poletto M, Tell G. Emerging roles of the nucleolus in regulating the DNA damage response: the noncanonical DNA repair enzyme APE1/Ref-1 as a paradigmatical example. Antioxid Redox Signal 2014; 20:621-39. [PMID: 23879289 PMCID: PMC3901381 DOI: 10.1089/ars.2013.5491] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 07/22/2013] [Indexed: 12/25/2022]
Abstract
SIGNIFICANCE An emerging concept in DNA repair mechanisms is the evidence that some key enzymes, besides their role in the maintenance of genome stability, display also unexpected noncanonical functions associated with RNA metabolism in specific subcellular districts (e.g., nucleoli). During the evolution of these key enzymes, the acquisition of unfolded domains significantly amplified the possibility to interact with different partners and substrates, possibly explaining their phylogenetic gain of functions. RECENT ADVANCES After nucleolar stress or DNA damage, many DNA repair proteins can freely relocalize from nucleoli to the nucleoplasm. This process may represent a surveillance mechanism to monitor the synthesis and correct assembly of ribosomal units affecting cell cycle progression or inducing p53-mediated apoptosis or senescence. CRITICAL ISSUES A paradigm for this kind of regulation is represented by some enzymes of the DNA base excision repair (BER) pathway, such as apurinic/apyrimidinic endonuclease 1 (APE1). In this review, the role of the nucleolus and the noncanonical functions of the APE1 protein are discussed in light of their possible implications in human pathologies. FUTURE DIRECTIONS A productive cross-talk between DNA repair enzymes and proteins involved in RNA metabolism seems reasonable as the nucleolus is emerging as a dynamic functional hub that coordinates cell growth arrest and DNA repair mechanisms. These findings will drive further analyses on other BER proteins and might imply that nucleic acid processing enzymes are more versatile than originally thought having evolved DNA-targeted functions after a previous life in the early RNA world.
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Affiliation(s)
- Giulia Antoniali
- Department of Medical and Biological Sciences, University of Udine , Udine, Italy
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6
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Best C, Calianese D, Szulak K, Cammarata G, Brum G, Carbone T, Still E, Higgins K, Ji F, DI W, Wanebo H, Wan Y. Paclitaxel disrupts polarized entry of membrane-permeable C6 ceramide into ovarian cancer cells resulting in synchronous induction of cell death. Oncol Lett 2013; 5:1854-1858. [PMID: 23833655 PMCID: PMC3701061 DOI: 10.3892/ol.2013.1305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 03/21/2013] [Indexed: 11/05/2022] Open
Abstract
Exogenous cell-permeable C6 ceramide has been demonstrated to act synergistically with chemotherapeutic drugs, including paclitaxel, cisplatin, doxorubicin and the histone deacetylase inhibitor, trichostatin A, to induce cell death in a variety of cancer cells. We previously demonstrated that C6 ceramide and paclitaxel function synergistically to induce ovarian cancer cell death via modulation of the PI3/AKT cell survival pathway. In the present study, the entry pattern of C6 ceramide into ovarian cancer cells was investigated using fluorescent short chain C6-NBD sphingomyelin (C6-NBD). Confocal microscopy revealed that C6-NBD enters the cells in a polarized pattern, characterized by marked signals at one cellular end, representing a likely mitosis initiation site. Pretreatment of the cells with filipin, an inhibitor of the lipid raft/caveolae endocytosis pathway, decreases C6-NBD entry into the cells. A pretreatment with the water channel inhibitor, CuSO4, was also found to reduce the entry of C6-NBD. Notably, the pretreatment with paclitaxel was shown to disrupt the polarized entry of C6-NBD into the cells, resulting in an even distribution of C6-NBD in the cytoplasm. In addition, the pretreatment of the cells with paclitaxel destabilized the cytoskeletal proteins, releasing an increased number of short tubulin fragments. The results of the present study indicate that C6 ceramide preferentially enters the cells via a predetermined initiation site of mitosis. In addition to diffusion, short chain C6 ceramide may also enter cells via water channels and caveolae-mediated endocytosis. Paclitaxel disrupts the cell cytoskeleton and induces an even distribution of C6 ceramide in the cytoplasm resulting in synergistic ovarian cancer cell death.
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Affiliation(s)
- Charles Best
- Department of Biology, Providence College, Providence, RI 02918, USA
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7
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Lindsey-Boltz LA, Reardon JT, Wold MS, Sancar A. In vitro analysis of the role of replication protein A (RPA) and RPA phosphorylation in ATR-mediated checkpoint signaling. J Biol Chem 2012; 287:36123-31. [PMID: 22948311 DOI: 10.1074/jbc.m112.407825] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Replication protein A (RPA) plays essential roles in DNA metabolism, including replication, checkpoint, and repair. Recently, we described an in vitro system in which the phosphorylation of human Chk1 kinase by ATR (ataxia telangiectasia mutated and Rad3-related) is dependent on RPA bound to single-stranded DNA. Here, we report that phosphorylation of other ATR targets, p53 and Rad17, has the same requirements and that RPA is also phosphorylated in this system. At high p53 or Rad17 concentrations, RPA phosphorylation is inhibited and, in this system, RPA with phosphomimetic mutations cannot support ATR kinase function, whereas a non-phosphorylatable RPA mutant exhibits full activity. Phosphorylation of these ATR substrates depends on the recruitment of ATR and the substrates by RPA to the RPA-ssDNA complex. Finally, mutant RPAs lacking checkpoint function exhibit essentially normal activity in nucleotide excision repair, revealing RPA separation of function for checkpoint and excision repair.
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Affiliation(s)
- Laura A Lindsey-Boltz
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7260, USA
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8
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Moore HM, Bai B, Boisvert FM, Latonen L, Rantanen V, Simpson JC, Pepperkok R, Lamond AI, Laiho M. Quantitative proteomics and dynamic imaging of the nucleolus reveal distinct responses to UV and ionizing radiation. Mol Cell Proteomics 2011; 10:M111.009241. [PMID: 21778410 DOI: 10.1074/mcp.m111.009241] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The nucleolus is a nuclear organelle that coordinates rRNA transcription and ribosome subunit biogenesis. Recent proteomic analyses have shown that the nucleolus contains proteins involved in cell cycle control, DNA processing and DNA damage response and repair, in addition to the many proteins connected with ribosome subunit production. Here we study the dynamics of nucleolar protein responses in cells exposed to stress and DNA damage caused by ionizing and ultraviolet (UV) radiation in diploid human fibroblasts. We show using a combination of imaging and quantitative proteomics methods that nucleolar substructure and the nucleolar proteome undergo selective reorganization in response to UV damage. The proteomic responses to UV include alterations of functional protein complexes such as the SSU processome and exosome, and paraspeckle proteins, involving both decreases and increases in steady state protein ratios, respectively. Several nonhomologous end-joining proteins (NHEJ), such as Ku70/80, display similar fast responses to UV. In contrast, nucleolar proteomic responses to IR are both temporally and spatially distinct from those caused by UV, and more limited in terms of magnitude. With the exception of the NHEJ and paraspeckle proteins, where IR induces rapid and transient changes within 15 min of the damage, IR does not alter the ratios of most other functional nucleolar protein complexes. The rapid transient decrease of NHEJ proteins in the nucleolus indicates that it may reflect a response to DNA damage. Our results underline that the nucleolus is a specific stress response organelle that responds to different damage and stress agents in a unique, damage-specific manner.
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Affiliation(s)
- Henna M Moore
- Molecular Cancer Biology Program and Haartman Institute, University of Helsinki, FIN-00014 Helsinki, Finland
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9
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Abstract
Claspin is a mediator of the ATR-dependent DNA replication checkpoint in human cells and also promotes DNA replication fork progression and stability. Though Claspin has been shown to bind DNA and co-immunoprecipitate with other replication fork-associated proteins, the specific protein-protein and protein-DNA interactions that are important for Claspin function are not known. We therefore purified several domains of human Claspin and then tested for direct interactions of these fragments with several replication fork-associated proteins and with DNA. Our data show that the N terminus of Claspin binds to the replicative helicase co-factor Cdc45, the Timeless protein and a branched, replication fork-like DNA structure. In contrast, the C terminus of Claspin associates with DNA polymerase epsilon and Rad17-Replication Factor C (RFC). We conclude that multiple protein-DNA and protein-protein interactions may be important for Claspin function during DNA replication and DNA replication checkpoint signaling.
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Affiliation(s)
- Ozdemirhan Serçin
- University of North Carolina School of Medicine, Chapel Hill, NC USA
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10
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Young JL, Koon EC, Kwong J, Welch WR, Muto MG, Berkowitz RS, Mok SC. Differential hRad17 expression by histologic subtype of ovarian cancer. J Ovarian Res 2011; 4:6. [PMID: 21450056 PMCID: PMC3077316 DOI: 10.1186/1757-2215-4-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 03/30/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the search for unique ovarian cancer biomarkers, ovarian specific cDNA microarray analysis identified hRad17, a cell cycle checkpoint protein, as over-expressed in ovarian cancer. The aim of this study was to validate this expression. METHODS Immunohistochemistry was performed on 72 serous, 19 endometrioid, 10 clear cell, and 6 mucinous ovarian cancers, 9 benign ovarian tumors, and 6 normal ovarian tissue sections using an anti-hRad17 antibody. Western blot analysis and quantitative PCR were performed using cell lysates and total RNA prepared from 17 ovarian cancer cell lines and 6 normal ovarian epithelial cell cultures (HOSE). RESULTS Antibody staining confirmed upregulation of hRad17 in 49.5% of ovarian cancer cases. Immunohistochemistry demonstrated that only 42% of serous and 47% of endometrioid subtypes showed overexpression compared to 80% of clear cell and 100% of mucinous cancers. Western blot confirmed overexpression of hRad17 in cancer cell lines compared to HOSE. Quantitative PCR demonstrated an upregulation of hRad17 RNA by 1.5-7 fold. hRad17 RNA expression differed by subtype. CONCLUSIONS hRad17 is over-expressed in ovarian cancer. This over-expression varies by subtype suggesting a role in the pathogenesis of these types. Functional studies are needed to determine the potential role of this protein in ovarian cancer.
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Affiliation(s)
- Jennifer L Young
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC, USA.
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11
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Sihn CR, Lee YS, Jeong JS, Park K, Kim SH. CANu1, a novel nucleolar protein, accumulated on centromere in response to DNA damage. Genes Cells 2008; 13:787-96. [DOI: 10.1111/j.1365-2443.2008.01205.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Tembe V, Henderson BR. Protein trafficking in response to DNA damage. Cell Signal 2007; 19:1113-20. [PMID: 17391916 DOI: 10.1016/j.cellsig.2007.03.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2007] [Accepted: 03/02/2007] [Indexed: 11/29/2022]
Abstract
Human cells are prone to a range of natural environmental stresses and administered agents that damage or modify DNA, resulting in a cellular response typified by either cell death, or a cell cycle arrest, to permit repair of the genomic damage. DNA damage often elicits movement of proteins from one subcellular location to another, and the redistribution of proteins involved in genomic maintenance into distinct nuclear DNA repair foci is well documented. In this review, we discuss the DNA damage-induced trafficking of proteins to and from other distinct subcellular organelles including the nucleolus, mitochondria, Golgi complex and centrosome. The extent of intracellular transport suggests a dynamic and possibly co-ordinated role for protein trafficking in the DNA damage response.
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Affiliation(s)
- Varsha Tembe
- Westmead Institute for Cancer Research, Westmead Millennium Institute at Westmead Hospital, University of Sydney, NSW 2145, Australia
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13
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Pick R, Badura S, Bösser S, Zörnig M. Upon intracellular processing, the C-terminal death domain-containing fragment of the p53-inducible PIDD/LRDD protein translocates to the nucleoli and interacts with nucleolin. Biochem Biophys Res Commun 2006; 349:1329-38. [PMID: 16982033 DOI: 10.1016/j.bbrc.2006.08.176] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Accepted: 08/30/2006] [Indexed: 11/28/2022]
Abstract
The p53-inducible and death domain-containing PIDD/LRDD protein has been described as an adaptor protein, which forms large protein complexes with RAIDD, another death domain-containing protein, leading to recruitment, and activation of the initiator caspase-2, and p53-mediated apoptosis. Here, we describe in further detail the proteolytic processing of PIDD/LRDD that occurs in healthy cells before induction of apoptosis. We could demonstrate that the C-terminal fragment containing the PIDD death domain shuttles into the nucleoli. This translocation is mediated by or leads to the interaction of the PIDD death domain with nucleolin, a protein important for rRNA processing within nucleoli and possibly involved in the DNA damage response. Ectopically expressed LRDD and endogenous nucleolin co-localized within the nucleoli, and overexpression of both full-length LRDD and the LRDD death domain sensitized cells for UV-induced apoptosis. When expressed alone, the PIDD/LRDD death domain tended to form large filamentous structures resembling so-called death filaments. The functional consequences of the identified PIDD/nucleolin interaction remain to be elucidated, but may be related to a recently discovered new role for PIDD in the activation of NF-kappaB upon genotoxic stress.
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Affiliation(s)
- Robert Pick
- Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus, Paul-Ehrlich-Strasse 42-44, D-60596 Frankfurt, Germany
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14
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Wang HL, Wang H, Zhu ZM, Yerle M, Wu X, Yang SL, Li K. Radiation hybrid mapping of five genes isolated from a porcine fetus skeletal muscle cDNA library. Anim Genet 2006; 36:529-30. [PMID: 16293138 DOI: 10.1111/j.1365-2052.2005.01374.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- H L Wang
- Department of Gene and Cell Engineering, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100094, China
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15
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Latonen L, Laiho M. Cellular UV damage responses--functions of tumor suppressor p53. Biochim Biophys Acta Rev Cancer 2005; 1755:71-89. [PMID: 15921859 DOI: 10.1016/j.bbcan.2005.04.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Revised: 04/07/2005] [Accepted: 04/21/2005] [Indexed: 02/06/2023]
Abstract
DNA damage, provoked by ultraviolet (UV) radiation, evokes a cellular damage response composed of activation of stress signaling and DNA checkpoint functions. These are translated to responses of replicative arrest, damage repair, and apoptosis aimed at cellular recovery from the damage. p53 tumor suppressor is a central stress response protein, activated by multiple endogenous and environmental insults, including UV radiation. The significance of p53 in the DNA damage responses has frequently been reviewed in the context of ionizing radiation or other double strand break (DSB)-inducing agents. Despite partly similar patterns, the molecular events following UV radiation are, however, distinct from the responses induced by DSBs and are profoundly coupled with transcriptional stress. These are illustrated, e.g., by the UV damage-specific translocations of Mdm2, promyelocytic leukemia protein, and nucleophosmin and their interactions with p53. In this review, we discuss UV damage-provoked cellular responses and the functions of p53 in damage recovery and cell death.
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Affiliation(s)
- Leena Latonen
- Molecular and Cancer Biology Program and Haartman Institute, University of Helsinki, PO Box 63, FIN-00014 Helsinki, Finland
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16
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Tsao CC, Geisen C, Abraham RT. Interaction between human MCM7 and Rad17 proteins is required for replication checkpoint signaling. EMBO J 2004; 23:4660-9. [PMID: 15538388 PMCID: PMC533049 DOI: 10.1038/sj.emboj.7600463] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Accepted: 10/06/2004] [Indexed: 01/09/2023] Open
Abstract
Human Rad17 (hRad17) is centrally involved in the activation of cell-cycle checkpoints by genotoxic agents or replication stress. Here we identify hMCM7, a core component of the DNA replication apparatus, as a novel hRad17-interacting protein. In HeLa cells, depletion of either hRad17 or hMCM7 with small-interfering RNA suppressed ultraviolet (UV) light- or aphidicolin-induced hChk1 phosphorylation, and abolished UV-induced S-phase checkpoint activation. Similar results were obtained after transfection of these cells with a fusion protein containing the hMCM7-binding region of hRad17. The hMCM7-depleted cells were also defective for the formation of ATR-containing nuclear foci after UV irradiation, suggesting that hMCM7 is required for stable recruitment of ATR to damaged DNA. These results demonstrate that hMCM7 plays a direct role in the transmission of DNA damage signals from active replication forks to the S-phase checkpoint machinery in human cells.
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Affiliation(s)
- Cheng-Chung Tsao
- Program in Signal Transduction Research, Cancer Research Center, The Burnham Institute, La Jolla, CA, USA
| | - Christoph Geisen
- Program in Signal Transduction Research, Cancer Research Center, The Burnham Institute, La Jolla, CA, USA
| | - Robert T Abraham
- Program in Signal Transduction Research, Cancer Research Center, The Burnham Institute, La Jolla, CA, USA
- Program in Signal Transduction Research, Cancer Research Center, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA. Tel.: +1 858 646 3182; Fax: +1 858 713 6274; E-mail:
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17
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He GHY, Helbing CC, Wagner MJ, Sensen CW, Riabowol K. Phylogenetic analysis of the ING family of PHD finger proteins. Mol Biol Evol 2004; 22:104-16. [PMID: 15356280 DOI: 10.1093/molbev/msh256] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Since the discovery of ING1 class II tumor suppressors in 1996, five different ING genes (ING1 to ING5) encoding proteins with highly conserved plant homeodomain (PHD) motifs and several splicing isoforms of the ING1 and ING2 gene have been identified. The ING family functions in DNA repair and apoptosis in response to UV damage through binding to proliferating cell nuclear antigen (PCNA); chromatin remodeling and regulation of gene expression through regulating and/or targeting histone acetyltransferase/deacetylase (HAT/HDAC) activities; binding targets of rare phosphatidylinositol phosphates (PtdInsPs) that function in DNA damage-initiated stress signaling; and regulating brain tumor angiogenesis through transcriptional repression of NF-KB-responsive genes. To elucidate the evolutionary history of ING proteins and summarize what is known about regions highly conserved in the ING family members, we have examined the sequences and phylogenetic relationships of ING proteins across taxonomically diverse organisms. We have identified novel ING family members in rats, frogs, fish, mosquitoes, fruit flies, worms, fungi, and plants. We have also clarified the naming and classification of ING proteins based on our phylogenetic analysis to allow better understanding of the ING protein family. Using sequence similarities, we have identified novel regions and motifs of unknown function that are conserved across family members. An evolutionary history for the ING family of PHD finger proteins is presented that indicates that five ING genes are present in vertebrates. Three of these may be paralogs of ING genes found in arthropods, whereas nematodes, fungi, and green plants contain ING genes that have general features of the vertebrate ING family.
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Affiliation(s)
- Gordon H Y He
- Department of Biochemistry and Molecular Biology, Health Science Complex, The University of Calgary, Calgary, Alberta, Canada
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18
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Kurki S, Peltonen K, Latonen L, Kiviharju TM, Ojala PM, Meek D, Laiho M. Nucleolar protein NPM interacts with HDM2 and protects tumor suppressor protein p53 from HDM2-mediated degradation. Cancer Cell 2004; 5:465-75. [PMID: 15144954 DOI: 10.1016/s1535-6108(04)00110-2] [Citation(s) in RCA: 321] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2003] [Revised: 02/12/2004] [Accepted: 03/17/2004] [Indexed: 01/23/2023]
Abstract
Nucleophosmin (NPM, B23) is an abundant nucleolar phosphoprotein involved in ribosome biogenesis, and interacts with tumor suppressor proteins p53 and Rb. Here we show that NPM is a UV damage response protein that undergoes nucleoplasmic redistribution and regulates p53 and HDM2 levels and their interaction. By utilizing RNAi approaches and analyses of endogenous and ectopically expressed proteins, we demonstrate that NPM binds HDM2 and acts as a negative regulator of p53-HDM2 interaction. Viral stress, enforced by expression of Kaposi's sarcoma virus K cyclin, causes NPM redistribution, K cyclin-NPM association, and p53 stabilization by dissociation of HDM2-p53 complexes. The results demonstrate novel associations of HDM2 and K cyclin with NPM and implicate NPM as a crucial controller of p53 through inhibition of HDM2.
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Affiliation(s)
- Sari Kurki
- Haartman Institute and Molecular Cancer Biology Research Program, Biomedicum Helsinki, University of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Helsinki, Finland
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19
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Leung AKL, Andersen JS, Mann M, Lamond AI. Bioinformatic analysis of the nucleolus. Biochem J 2004; 376:553-69. [PMID: 14531731 PMCID: PMC1223824 DOI: 10.1042/bj20031169] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Accepted: 10/08/2003] [Indexed: 02/02/2023]
Abstract
The nucleolus is a plurifunctional, nuclear organelle, which is responsible for ribosome biogenesis and many other functions in eukaryotes, including RNA processing, viral replication and tumour suppression. Our knowledge of the human nucleolar proteome has been expanded dramatically by the two recent MS studies on isolated nucleoli from HeLa cells [Andersen, Lyon, Fox, Leung, Lam, Steen, Mann and Lamond (2002) Curr. Biol. 12, 1-11; Scherl, Coute, Deon, Calle, Kindbeiter, Sanchez, Greco, Hochstrasser and Diaz (2002) Mol. Biol. Cell 13, 4100-4109]. Nearly 400 proteins were identified within the nucleolar proteome so far in humans. Approx. 12% of the identified proteins were previously shown to be nucleolar in human cells and, as expected, nearly all of the known housekeeping proteins required for ribosome biogenesis were identified in these analyses. Surprisingly, approx. 30% represented either novel or uncharacterized proteins. This review focuses on how to apply the derived knowledge of this newly recognized nucleolar proteome, such as their amino acid/peptide composition and their homologies across species, to explore the function and dynamics of the nucleolus, and suggests ways to identify, in silico, possible functions of the novel/uncharacterized proteins and potential interaction networks within the human nucleolus, or between the nucleolus and other nuclear organelles, by drawing resources from the public domain.
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Affiliation(s)
- Anthony K L Leung
- Division of Gene Regulation and Expression, School of Life Sciences, Wellcome Trust Biocentre, University of Dundee, Scotland, UK.
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20
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Libby BJ, Reinholdt LG, Schimenti JC. Positional cloning and characterization of Mei1, a vertebrate-specific gene required for normal meiotic chromosome synapsis in mice. Proc Natl Acad Sci U S A 2003; 100:15706-11. [PMID: 14668445 PMCID: PMC307632 DOI: 10.1073/pnas.2432067100] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mouse meiotic mutant Mei1 was isolated in a screen for infertile mice descended from chemically mutagenized embryonic stem cells. Homozygotes of both sexes are sterile due to meiotic arrest caused by defects in chromosome synapsis. Notably, RAD51 protein does not load onto Mei1 mutant meiotic chromosomes, suggesting that there is a defect in either recombinational repair or the production of double-strand breaks (DSBs) that require such repair. Here, we show that treatment of mutant males with cisplatin restores RAD51 loading, suggesting that mutant spermatocytes have intact recombinational repair mechanisms. Levels of histone H2AX phosphorylation (gammaH2AX) at leptonema are significantly reduced compared with wild-type controls but comparable to that seen in animals deficient for SPO11, the molecule required for catalyzing DSB formation during meiosis. These observations provide evidence that genetically programmed DSB induction is defective in Mei1 leptotene spermatocytes. We also report the positional cloning of Mei1, which encodes a product without significant homology to any known protein. Expressed almost exclusively in gonads, Mei1 has no apparent homologs in yeast, worms, or flies. However, Mei1 orthologs are present in the genomes of mammals, chickens, and zebrafish. Thus, Mei1 is required for vertebrate meiosis. To our knowledge, Mei1 is the first meiosis-specific mutation identified by forward genetic approaches in mammals.
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21
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Ellison V, Stillman B. Biochemical characterization of DNA damage checkpoint complexes: clamp loader and clamp complexes with specificity for 5' recessed DNA. PLoS Biol 2003; 1:E33. [PMID: 14624239 PMCID: PMC261875 DOI: 10.1371/journal.pbio.0000033] [Citation(s) in RCA: 266] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2003] [Accepted: 08/23/2003] [Indexed: 11/18/2022] Open
Abstract
The cellular pathways involved in maintaining genome stability halt cell cycle progression in the presence of DNA damage or incomplete replication. Proteins required for this pathway include Rad17, Rad9, Hus1, Rad1, and Rfc-2, Rfc-3, Rfc-4, and Rfc-5. The heteropentamer replication factor C (RFC) loads during DNA replication the homotrimer proliferating cell nuclear antigen (PCNA) polymerase clamp onto DNA. Sequence similarities suggest the biochemical functions of an RSR (Rad17–Rfc2–Rfc3–Rfc4–Rfc5) complex and an RHR heterotrimer (Rad1–Hus1–Rad9) may be similar to that of RFC and PCNA, respectively. RSR purified from human cells loads RHR onto DNA in an ATP-, replication protein A-, and DNA structure-dependent manner. Interestingly, RSR and RFC differed in their ATPase activities and displayed distinct DNA substrate specificities. RSR preferred DNA substrates possessing 5′ recessed ends whereas RFC preferred 3′ recessed end DNA substrates. Characterization of the biochemical loading reaction executed by the checkpoint clamp loader RSR suggests new insights into the mechanisms underlying recognition of damage-induced DNA structures and signaling to cell cycle controls. The observation that RSR loads its clamp onto a 5′ recessed end supports a potential role for RHR and RSR in diverse DNA metabolism, such as stalled DNA replication forks, recombination-linked DNA repair, and telomere maintenance, among other processes. A cell cycle checkpoint complex is shown to bind preferentially to DNA with 5'recessed ends. This activity suggests that the complex might be involved in various DNA maintenance pathways
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Affiliation(s)
- Viola Ellison
- 1Cold Spring Harbor Laboratory, Cold Spring HarborNew YorkUnited States of America
| | - Bruce Stillman
- 1Cold Spring Harbor Laboratory, Cold Spring HarborNew YorkUnited States of America
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22
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Wang C, Query CC, Meier UT. Immunopurified small nucleolar ribonucleoprotein particles pseudouridylate rRNA independently of their association with phosphorylated Nopp140. Mol Cell Biol 2002; 22:8457-66. [PMID: 12446766 PMCID: PMC139890 DOI: 10.1128/mcb.22.24.8457-8466.2002] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The isomerization of up to 100 uridines to pseudouridines (Psis) in eukaryotic rRNA is guided by a similar number of box H/ACA small nucleolar RNAs (snoRNAs), each forming a unique small nucleolar ribonucleoprotein particle (snoRNP) with the same four core proteins, NAP57 (also known as dyskerin or Cbf5p), GAR1, NHP2, and NOP10. Additionally, the nucleolar and Cajal body protein Nopp140 (Srp40p) associates with the snoRNPs. To understand the role of these factors in pseudouridylation, we established an in vitro assay system. Short site-specifically (32)P-labeled rRNA substrates were incubated with subcellular fractions, and the conversion of uridine to Psi was monitored by thin-layer chromatography after digestion to single nucleotides. Immunopurified box H/ACA core particles were sufficient for the reaction. SnoRNPs associated quantitatively and reversibly with Nopp140. However, pseudouridylation activity was independent of Nopp140, consistent with a chaperoning role for this highly phosphorylated protein. Although up to 14 bp between the snoRNA and rRNA were required for the in vitro reaction, rRNA pseudouridylation and release occurred in the absence of ATP and magnesium. These data suggest that substrate release takes place without RNA helicase activity but may be aided by the snoRNP core proteins.
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Affiliation(s)
- Chen Wang
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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23
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Dahm K, Hübscher U. Colocalization of human Rad17 and PCNA in late S phase of the cell cycle upon replication block. Oncogene 2002; 21:7710-9. [PMID: 12400013 DOI: 10.1038/sj.onc.1205872] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2002] [Revised: 07/11/2002] [Accepted: 07/15/2002] [Indexed: 12/22/2022]
Abstract
In response to replication block or DNA damage in S phase the DNA replication and DNA damage checkpoints are activated. The current model in human predicts, that a Rad17/Replication factor C (RF-C) complex might serve as a recruitment complex for the Rad9/Hus1/Rad1 complex to sites of replication block or DNA damage. In this study we have investigated the fate of the Rad17/RF-C complex after treatment of synchronized Hela cells with the replication inhibitor hydroxyurea. In hydroxyurea treated cells the RF-C p37 subunit became more resistant to extraction. Moreover, co-immunoprecipitation studies with extracts of hydroxyurea treated cells showed an interaction of RF-C p37 with Rad17 and of PCNA with Rad9 and RF-C p37. An enhanced colocalization of Rad17 and PCNA in late S phase after hydroxyurea treatment was observed. Our data suggested, that upon replication block a Rad17/RF-C complex is recruited to sites of DNA lesions in late S phase, binds the Rad9/Hus1/Rad1 complex and enables it to interact with PCNA. An interaction of Rad17/RF-C with PCNA appears to be mediated by the small RF-C p37 subunit, suggesting that PCNA might provide communication between replication checkpoint control and DNA replication and repair.
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Affiliation(s)
- Kirsten Dahm
- Institute of Veterinary Biochemistry and Molecular Biology, University Zürich-Irchel, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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24
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Daniely Y, Dimitrova DD, Borowiec JA. Stress-dependent nucleolin mobilization mediated by p53-nucleolin complex formation. Mol Cell Biol 2002; 22:6014-22. [PMID: 12138209 PMCID: PMC133981 DOI: 10.1128/mcb.22.16.6014-6022.2002] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2002] [Accepted: 05/08/2002] [Indexed: 01/10/2023] Open
Abstract
We recently discovered that heat shock causes nucleolin to relocalize from the nucleolus to the nucleoplasm, whereupon it binds replication protein A and inhibits DNA replication initiation. We report that nucleolin mobilization also occurs following exposure to ionizing radiation (IR) and treatment with camptothecin. Mobilization was selective in that another nucleolar marker, upstream binding factor, did not relocalize in response to IR. Nucleolin relocalization was dependent on p53 and stress, the latter initially stimulating nucleolin-p53 complex formation. Nucleolin relocalization and complex formation in vivo were independent of p53 transactivation but required the p53 C-terminal regulatory domain. Nucleolin and p53 also interact directly in vitro, with a similar requirement for p53 domains. These data indicate a novel p53-dependent mechanism in which cell stress mobilizes nucleolin for transient replication inhibition and DNA repair.
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Affiliation(s)
- Yaron Daniely
- Department of Biochemistry and Kaplan Comprehensive Cancer Center, New York University School of Medicine, New York, New York 10016, USA
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25
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Leung AKL, Lamond AI. In vivo analysis of NHPX reveals a novel nucleolar localization pathway involving a transient accumulation in splicing speckles. J Cell Biol 2002; 157:615-29. [PMID: 12011111 PMCID: PMC2173864 DOI: 10.1083/jcb.200201120] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The NHPX protein is a nucleolar factor that binds directly to a conserved RNA target sequence found in nucleolar box C/D snoRNAs and in U4 snRNA. Using enhanced yellow fluorescent protein (EYFP)- and enhanced cyan fluorescent protein-NHPX fusions, we show here that NHPX is specifically accumulated in both nucleoli and Cajal bodies (CBs) in vivo. The fusion proteins display identical localization patterns and RNA binding specificities to the endogenous NHPX. Analysis of a HeLa cell line stably expressing EYFP-NHPX showed that the nucleolar accumulation of NHPX was preceded by its transient accumulation in splicing speckles. Only newly expressed NHPX accumulated in speckles, and the nucleolar pool of NHPX did not interchange with the pool in speckles, consistent with a unidirectional pathway. The transient accumulation of NHPX in speckles prior to nucleoli was observed in multiple cell lines, including primary cells that lack CBs. Inhibitor studies indicated that progression of newly expressed NHPX from speckles to nucleoli was dependent on RNA polymerase II transcription, but not on RNA polymerase I activity. The data show a specific temporal pathway involving the sequential and directed accumulation of NHPX in distinct subnuclear compartments, and define a novel mechanism for nucleolar localization.
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Affiliation(s)
- Anthony K L Leung
- Wellcome Trust Biocentre, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, Scotland, UK
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26
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Libby BJ, De La Fuente R, O'Brien MJ, Wigglesworth K, Cobb J, Inselman A, Eaker S, Handel MA, Eppig JJ, Schimenti JC. The mouse meiotic mutation mei1 disrupts chromosome synapsis with sexually dimorphic consequences for meiotic progression. Dev Biol 2002; 242:174-87. [PMID: 11820814 DOI: 10.1006/dbio.2001.0535] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
mei1 (meiosis defective 1) is the first meiotic mutation in mice derived by phenotype-driven mutagenesis. It was isolated by using a novel technology in which embryonic stem (ES) cells were chemically mutagenized and used to generate families of mice that were screened for infertility. We report here that mei1/mei1 spermatocytes arrest at the zygotene stage of meiosis I, exhibiting failure of homologous chromosomes to properly synapse. Notably, RAD51 failed to associate with meiotic chromosomes in mutant spermatocytes, despite evidence for the presence of chromosomal breaks. Transcription of genes that are markers for the leptotene and zygotene stages, but not genes that are markers for the pachytene stage, was observed. mei1/mei1 females are sterile, and their oocytes also show severe synapsis defects. Nevertheless, unlike arrested spermatocytes, a small number of mutant oocytes proved capable of progressing to metaphase I and attempting the first meiotic division. However, their chromosomes were unpaired and were not organized properly at the metaphase plate or along the spindle fibers during segregation. mei1 was genetically mapped to chromosome (Chr) 15 in an interval that is syntenic to human Chr 22q13. This region, which has been completely sequenced, contains no known homologs of genes specifically required for meiosis in model organisms. Thus, mei1 may be a novel meiotic gene.
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Affiliation(s)
- Brian J Libby
- The Jackson Laboratory, Bar Harbor, Maine, 04609, USA
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27
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Lindsey-Boltz LA, Bermudez VP, Hurwitz J, Sancar A. Purification and characterization of human DNA damage checkpoint Rad complexes. Proc Natl Acad Sci U S A 2001; 98:11236-41. [PMID: 11572977 PMCID: PMC58713 DOI: 10.1073/pnas.201373498] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Checkpoint Rad proteins function early in the DNA damage checkpoint signaling cascade to arrest cell cycle progression in response to DNA damage. This checkpoint ensures the transmission of an intact genetic complement to daughter cells. To learn about the damage sensor function of the human checkpoint Rad proteins, we purified a heteropentameric complex composed of hRad17-RFCp36-RFCp37-RFCp38-RFCp40 (hRad17-RFC) and a heterotrimeric complex composed of hRad9-hHus1-hRad1 (checkpoint 9-1-1 complex). hRad17-RFC binds to DNA, with a preference for primed DNA and possesses weak ATPase activity that is stimulated by primed DNA and single-stranded DNA. hRad17-RFC forms a complex with the 9-1-1 heterotrimer reminiscent of the replication factor C/proliferating cell nuclear antigen clamp loader/sliding clamp complex of the replication machinery. These findings constitute biochemical support for models regarding the roles of checkpoint Rads as damage sensors in the DNA damage checkpoint response of human cells.
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Affiliation(s)
- L A Lindsey-Boltz
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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28
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Abstract
Cells are constantly under threat from the cytotoxic and mutagenic effects of DNA damaging agents. These agents can either be exogenous or formed within cells. Environmental DNA-damaging agents include UV light and ionizing radiation, as well as a variety of chemicals encountered in foodstuffs, or as air- and water-borne agents. Endogenous damaging agents include methylating species and the reactive oxygen species that arise during respiration. Although diverse responses are elicited in cells following DNA damage, this review focuses on three aspects: DNA repair mechanisms, cell cycle checkpoints, and apoptosis. Because the areas of nucleotide excision repair and mismatch repair have been covered extensively in recent reviews, we restrict our coverage of the DNA repair field to base excision repair and DNA double-strand break repair.
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Affiliation(s)
- C J Norbury
- Imperial Cancer Research Fund Laboratories, Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, United Kingdom.
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29
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Zhang H, Zhu Z, Vidanes G, Mbangkollo D, Liu Y, Siede W. Characterization of DNA damage-stimulated self-interaction of Saccharomyces cerevisiae checkpoint protein Rad17p. J Biol Chem 2001; 276:26715-23. [PMID: 11356855 DOI: 10.1074/jbc.m103682200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Saccharomyces cerevisiae Rad17p is necessary for cell cycle checkpoint arrests in response to DNA damage. Its known interactions with the checkpoint proteins Mec3p and Ddc1p in a PCNA-like complex indicate a sensor role in damage recognition. In a novel application of the yeast two-hybrid system and by immunoprecipitation, we show here that Rad17p is capable of increased self-interaction following DNA damage introduced by 4-nitroquinoline-N-oxide, camptothecin or partial inactivation of DNA ligase I. Despite overlap of regions required for Rad17p interactions with Rad17p or Mec3p, single amino acid substitutions revealed that Rad17p x Rad17p complex formation is independent of Mec3p. E128K (rad17-1) was found to inhibit Rad17p interaction with Mec3p but not with Rad17p. On the other hand, Phe-121 is essential for Rad17p self-interaction, and its function in checkpoint arrest but not for Mec3p interaction. These differential effects indicate that Rad17p-Rad17p interaction plays a role that is independent of the Rad17p x Mec3p x Ddc1p complex, although our results are also compatible with Rad17p-mediated supercomplex formation of the Rad17p x Mec3p x Ddc1p heterotrimer in response to DNA damage.
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Affiliation(s)
- H Zhang
- Department of Radiation Oncology and the Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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30
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Mayer ML, Gygi SP, Aebersold R, Hieter P. Identification of RFC(Ctf18p, Ctf8p, Dcc1p): an alternative RFC complex required for sister chromatid cohesion in S. cerevisiae. Mol Cell 2001; 7:959-70. [PMID: 11389843 DOI: 10.1016/s1097-2765(01)00254-4] [Citation(s) in RCA: 262] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have identified and characterized an alternative RFC complex RFC(Ctf18p, Ctf8p, Dcc1p) that is required for sister chromatid cohesion and faithful chromosome transmission. Ctf18p, Ctf8p, and Dcc1p interact physically in a complex with Rfc2p, Rfc3p, Rfc4p, and Rfc5p but not with Rfc1p or Rad24p. Deletion of CTF18, CTF8, or DCC1 singly or in combination (ctf18Deltactf8Deltadcc1Delta) leads to sensitivity to microtubule depolymerizing drugs and a severe sister chromatid cohesion defect. Furthermore, temperature-sensitive mutations in RFC4 result in precocious sister chromatid separation. Our results highlight a novel function of the RFC proteins and support a model in which sister chromatid cohesion is established at the replication fork via a polymerase switching mechanism and a replication-coupled remodeling of chromatin.
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Affiliation(s)
- M L Mayer
- Graduate Program in Biochemistry, Cellular and Molecular Biology, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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31
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San-Segundo PA, Roeder GS. Role for the silencing protein Dot1 in meiotic checkpoint control. Mol Biol Cell 2000; 11:3601-15. [PMID: 11029058 PMCID: PMC15018 DOI: 10.1091/mbc.11.10.3601] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
During the meiotic cell cycle, a surveillance mechanism called the "pachytene checkpoint" ensures proper chromosome segregation by preventing meiotic progression when recombination and chromosome synapsis are defective. The silencing protein Dot1 (also known as Pch1) is required for checkpoint-mediated pachytene arrest of the zip1 and dmc1 mutants of Saccharomyces cerevisiae. In the absence of DOT1, the zip1 and dmc1 mutants inappropriately progress through meiosis, generating inviable meiotic products. Other components of the pachytene checkpoint include the nucleolar protein Pch2 and the heterochromatin component Sir2. In dot1, disruption of the checkpoint correlates with the loss of concentration of Pch2 and Sir2 in the nucleolus. In addition to its checkpoint function, Dot1 blocks the repair of meiotic double-strand breaks by a Rad54-dependent pathway of recombination between sister chromatids. In vegetative cells, mutation of DOT1 results in delocalization of Sir3 from telomeres, accounting for the impaired telomeric silencing in dot1.
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Affiliation(s)
- P A San-Segundo
- Howard Hughes Medical Institute, Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
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Franchini KG, Torsoni AS, Soares PH, Saad MJ. Early activation of the multicomponent signaling complex associated with focal adhesion kinase induced by pressure overload in the rat heart. Circ Res 2000; 87:558-65. [PMID: 11009560 DOI: 10.1161/01.res.87.7.558] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mechanical overload elicits functional and structural adaptive mechanisms in cardiac muscle. Signaling pathways linked to integrin/cytoskeleton complexes may have a function in mediation of the effects of mechanical stimulus in myocardial cells. We investigated the tyrosine phosphorylation and the assembly of the multicomponent signaling complex associated with focal adhesion kinase (Fak) and the actin cytoskeleton in the overloaded myocardium of rats. Pressure overload induced a 3-fold increase in Fak tyrosine phosphorylation within 3 minutes after a 60-mm Hg rise in aortic pressure. A pressure stimulus that lasted for 60 minutes was accompanied by a 5-fold increase in the amount of tyrosine-phosphorylated Fak, and a stimulus as low as 10 mm Hg doubled the amount of tyrosine-phosphorylated Fak in the myocardium within 10 minutes. Pressure overload also induced a time-dependent association of actin with Fak and an increase in the amount of Fak detected in the cytoskeletal fraction of the myocardium. These events were paralleled by c-Src activation and binding to Fak and by an association of Grb2 and p85 subunit of phosphatidylinositol 3-kinase with Fak. Erk1/2 and Akt, two possible downstream effectors of Fak via Grb2 and phosphatidylinositol 3-kinase, were also shown to be activated in parallel with Fak. These findings show that pressure overload induced a rapid activation of the Fak multiple signaling complex in the myocardium of rats, which suggests that this mechanism may have a role in mechanotransduction in the myocardium.
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Affiliation(s)
- K G Franchini
- Department of Internal Medicine, School of Medicine, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
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Venclovas C, Thelen MP. Structure-based predictions of Rad1, Rad9, Hus1 and Rad17 participation in sliding clamp and clamp-loading complexes. Nucleic Acids Res 2000; 28:2481-93. [PMID: 10871397 PMCID: PMC102700 DOI: 10.1093/nar/28.13.2481] [Citation(s) in RCA: 209] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The repair of damaged DNA is coupled to the completion of DNA replication by several cell cycle checkpoint proteins, including, for example, in fission yeast Rad1(Sp), Hus1(Sp), Rad9(Sp) and Rad17(Sp). We have found that these four proteins are conserved with protein sequences throughout eukaryotic evolution. Using computational techniques, including fold recognition, comparative modeling and generalized sequence profiles, we have made high confidence structure predictions for the each of the Rad1, Hus1 and Rad9 protein families (Rad17(Sc), Mec3(Sc) and Ddc1(Sc) in budding yeast, respectively). Each of these families was found to share a common protein fold with that of PCNA, the sliding clamp protein that tethers DNA polymerase to its template. We used previously reported genetic and biochemical data for these proteins from yeast and human cells to predict a heterotrimeric PCNA-like ring structure for the functional Rad1/Rad9/Hus1 complex and to determine their exact order within it. In addition, for each individual protein family, contact regions with neighbors within the PCNA-like ring were identified. Based on a molecular model for Rad17(Sp), we concluded that members of this family, similar to the subunits of the RFC clamp-loading complex, are capable of coupling ATP binding with conformational changes required to load a sliding clamp onto DNA. This model substantiates previous findings regarding the behavior of Rad17 family proteins upon DNA damage and within the RFC complex of clamp-loading proteins.
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Affiliation(s)
- C Venclovas
- Molecular and Structural Biology Division, Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
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