51
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Szambowska A, Tessmer I, Prus P, Schlott B, Pospiech H, Grosse F. Cdc45-induced loading of human RPA onto single-stranded DNA. Nucleic Acids Res 2017; 45:3217-3230. [PMID: 28100698 PMCID: PMC5389570 DOI: 10.1093/nar/gkw1364] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 01/02/2017] [Indexed: 11/14/2022] Open
Abstract
Cell division cycle protein 45 (Cdc45) is an essential component of the eukaryotic replicative DNA helicase. We found that human Cdc45 forms a complex with the single-stranded DNA (ssDNA) binding protein RPA. Moreover, it actively loads RPA onto nascent ssDNA. Pull-down assays and surface plasmon resonance studies revealed that Cdc45-bound RPA complexed with ssDNA in the 8–10 nucleotide binding mode, but dissociated when RPA covered a 30-mer. Real-time analysis of RPA-ssDNA binding demonstrated that Cdc45 catalytically loaded RPA onto ssDNA. This placement reaction required physical contacts of Cdc45 with the RPA70A subdomain. Our results imply that Cdc45 controlled stabilization of the 8-nt RPA binding mode, the subsequent RPA transition into 30-mer mode and facilitated an ordered binding to ssDNA. We propose that a Cdc45-mediated loading guarantees a seamless deposition of RPA on newly emerging ssDNA at the nascent replication fork.
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Affiliation(s)
- Anna Szambowska
- Research Group Biochemistry, Leibniz Institute on Aging-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Ingrid Tessmer
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef Schneider Strasse 2, D-97080 Würzburg, Germany
| | - Piotr Prus
- Biocenter Oulu, P.O. Box 5000, 90014 University of Oulu, Finland
| | - Bernhard Schlott
- Research Group Biochemistry, Leibniz Institute on Aging-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany.,Proteomics Core Facility, Leibniz Institute on Aging-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Helmut Pospiech
- Research Group Biochemistry, Leibniz Institute on Aging-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany.,Faculty of Biochemistry and Molecular Medicine, P.O. Box 5000, 90014 University of Oulu, Finland
| | - Frank Grosse
- Research Group Biochemistry, Leibniz Institute on Aging-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany.,Center for Molecular Biomedicine, Friedrich-Schiller University, Biochemistry Department, Jena, Germany
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52
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Li Y, Li Z, Wu R, Han Z, Zhu W. And-1 is required for homologous recombination repair by regulating DNA end resection. Nucleic Acids Res 2017; 45:2531-2545. [PMID: 27940557 PMCID: PMC5389477 DOI: 10.1093/nar/gkw1241] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 11/28/2016] [Indexed: 11/29/2022] Open
Abstract
Homologous recombination (HR) is a major mechanism to repair DNA double-strand breaks (DSBs). Although tumor suppressor CtIP is critical for DSB end resection, a key initial event of HR repair, the mechanism regulating the recruitment of CtIP to DSB sites remains largely unknown. Here, we show that acidic nucleoplasmic DNA‐binding protein 1 (And‐1) forms complexes with CtIP as well as other repair proteins, and is essential for HR repair by regulating DSB end resection. Furthermore, And-1 is recruited to DNA DSB sites in a manner dependent on MDC1, BRCA1 and ATM, down-regulation of And-1 impairs end resection by reducing the recruitment of CtIP to damage sites, and considerably reduces Chk1 activation and other damage response during HR repair. These findings collectively demonstrate a hitherto unknown role of MDC1→And-1→CtIP axis that regulates CtIP-mediated DNA end resection and cellular response to DSBs.
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Affiliation(s)
- Yongming Li
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine and Health Science, 2300 Eye Street, N.W., Washington, DC 20037, USA
| | - Zongzhu Li
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine and Health Science, 2300 Eye Street, N.W., Washington, DC 20037, USA
| | - Ruiqin Wu
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine and Health Science, 2300 Eye Street, N.W., Washington, DC 20037, USA
| | - Zhiyong Han
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine and Health Science, 2300 Eye Street, N.W., Washington, DC 20037, USA
| | - Wenge Zhu
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine and Health Science, 2300 Eye Street, N.W., Washington, DC 20037, USA
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53
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Chen Y, Liu H, Zhang H, Sun C, Hu Z, Tian Q, Peng C, Jiang P, Hua H, Li X, Pei H. And-1 coordinates with CtIP for efficient homologous recombination and DNA damage checkpoint maintenance. Nucleic Acids Res 2017; 45:2516-2530. [PMID: 27940552 PMCID: PMC5389581 DOI: 10.1093/nar/gkw1212] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/25/2016] [Indexed: 12/29/2022] Open
Abstract
To prevent genomic instability, cells respond to DNA lesions by blocking cell cycle progression and initiating DNA repair. Homologous recombination repair of DNA breaks requires CtIP-dependent resection of the DNA ends, which is thought to play a key role in activation of CHK1 kinase to induce the cell cycle checkpoint. But the mechanism is still not fully understood. Here, we establish that And-1, a replisome component, promotes DNA-end resection and DNA repair by homologous recombination. Mechanistically, And-1 interacts with CtIP and regulates CtIP recruitment to DNA damage sites. And-1 localizes to sites of DNA damage dependent on MDC1-RNF8 pathway, and is required for resistance to many DNA-damaging and replication stress-inducing agents. Furthermore, we show that And-1-CtIP axis is critically required for sustained ATR-CHK1 checkpoint signaling and for maintaining both the intra-S- and G2-phase checkpoints. Our findings thus identify And-1 as a novel DNA repair regulator and reveal how the replisome regulates the DNA damage induced checkpoint and genomic stability.
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Affiliation(s)
- Yali Chen
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Hailong Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Haoxing Zhang
- School of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong Province 518060, China
| | - Changqing Sun
- Department of neurosurgery, Tianjin Baodi Hospital, Baodi Clinical College of Tianjin Medical University, Tianjin 301800, China
| | - Zhaohua Hu
- Department of Orthopedics, Renhe Hospital of Three Gorges University, Yichang 443001, China
| | - Qingsong Tian
- Department of Orthopedics, Renhe Hospital of Three Gorges University, Yichang 443001, China
| | - Changmin Peng
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Industrial Microbiology Key Lab, College of Biotechnology, Tianjin University of Science and Technology, No 29, 13ST. TEDA, Tianjin 300457, China
| | - Pei Jiang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Hui Hua
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Xinzhi Li
- Department of Orthopedics, Renhe Hospital of Three Gorges University, Yichang 443001, China
| | - Huadong Pei
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
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54
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Neves H, Kwok HF. In sickness and in health: The many roles of the minichromosome maintenance proteins. Biochim Biophys Acta Rev Cancer 2017; 1868:295-308. [DOI: 10.1016/j.bbcan.2017.06.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/29/2017] [Accepted: 06/01/2017] [Indexed: 01/09/2023]
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55
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Lin YH, Jewell BE, Gingold J, Lu L, Zhao R, Wang LL, Lee DF. Osteosarcoma: Molecular Pathogenesis and iPSC Modeling. Trends Mol Med 2017; 23:737-755. [PMID: 28735817 DOI: 10.1016/j.molmed.2017.06.004] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 06/13/2017] [Accepted: 06/15/2017] [Indexed: 12/17/2022]
Abstract
Rare hereditary disorders provide unequivocal evidence of the importance of genes in human disease pathogenesis. Familial syndromes that predispose to osteosarcomagenesis are invaluable in understanding the underlying genetics of this malignancy. Recently, patient-derived induced pluripotent stem cells (iPSCs) have been successfully utilized to model Li-Fraumeni syndrome (LFS)-associated bone malignancy, demonstrating that iPSCs can serve as an in vitro disease model to elucidate osteosarcoma etiology. We provide here an overview of osteosarcoma predisposition syndromes and review recently established iPSC disease models for these familial syndromes. Merging molecular information gathered from these models with the current knowledge of osteosarcoma biology will help us to gain a deeper understanding of the pathological mechanisms underlying osteosarcomagenesis and will potentially aid in the development of future patient therapies.
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Affiliation(s)
- Yu-Hsuan Lin
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; These authors contributed equally to this work
| | - Brittany E Jewell
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA; These authors contributed equally to this work
| | - Julian Gingold
- Women's Health Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA; These authors contributed equally to this work
| | - Linchao Lu
- Texas Children's Cancer Center, Department of Pediatrics, Section of Hematology/Oncology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ruiying Zhao
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Lisa L Wang
- Texas Children's Cancer Center, Department of Pediatrics, Section of Hematology/Oncology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dung-Fang Lee
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, The Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Precision Health, School of Biomedical Informatics and School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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56
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Izumi M, Mizuno T, Yanagi KI, Sugimura K, Okumura K, Imamoto N, Abe T, Hanaoka F. The Mcm2-7-interacting domain of human mini-chromosome maintenance 10 (Mcm10) protein is important for stable chromatin association and origin firing. J Biol Chem 2017. [PMID: 28646110 DOI: 10.1074/jbc.m117.779371] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protein mini-chromosome maintenance 10 (Mcm10) was originally identified as an essential yeast protein in the maintenance of mini-chromosome plasmids. Subsequently, Mcm10 has been shown to be required for both initiation and elongation during chromosomal DNA replication. However, it is not fully understood how the multiple functions of Mcm10 are coordinated or how Mcm10 interacts with other factors at replication forks. Here, we identified and characterized the Mcm2-7-interacting domain in human Mcm10. The interaction with Mcm2-7 required the Mcm10 domain that contained amino acids 530-655, which overlapped with the domain required for the stable retention of Mcm10 on chromatin. Expression of truncated Mcm10 in HeLa cells depleted of endogenous Mcm10 via siRNA revealed that the Mcm10 conserved domain (amino acids 200-482) is essential for DNA replication, whereas both the conserved and the Mcm2-7-binding domains were required for its full activity. Mcm10 depletion reduced the initiation frequency of DNA replication and interfered with chromatin loading of replication protein A, DNA polymerase (Pol) α, and proliferating cell nuclear antigen, whereas the chromatin loading of Cdc45 and Pol ϵ was unaffected. These results suggest that human Mcm10 is bound to chromatin through the interaction with Mcm2-7 and is primarily involved in the initiation of DNA replication after loading of Cdc45 and Pol ϵ.
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Affiliation(s)
- Masako Izumi
- Accelerator Applications Research Group, Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan.
| | - Takeshi Mizuno
- Cellular Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | | | - Kazuto Sugimura
- Department of Life Science, Graduate School of Bioresources, Mie University, Tsu, Mie 514-8507, Japan
| | - Katsuzumi Okumura
- Department of Life Science, Graduate School of Bioresources, Mie University, Tsu, Mie 514-8507, Japan
| | - Naoko Imamoto
- Cellular Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Tomoko Abe
- Accelerator Applications Research Group, Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
| | - Fumio Hanaoka
- Department of Life Science, Faculty of Science, Gakushuin University, Tokyo 171-8588, Japan; Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba, Ibaraki 305-8577, Japan
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57
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Guan C, Li J, Sun D, Liu Y, Liang H. The structure and polymerase-recognition mechanism of the crucial adaptor protein AND-1 in the human replisome. J Biol Chem 2017; 292:9627-9636. [PMID: 28381552 DOI: 10.1074/jbc.m116.758524] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 04/04/2017] [Indexed: 01/10/2023] Open
Abstract
DNA replication in eukaryotic cells is performed by a multiprotein complex called the replisome, which consists of helicases, polymerases, and adaptor molecules. Human acidic nucleoplasmic DNA-binding protein 1 (AND-1), also known as WD repeat and high mobility group (HMG)-box DNA-binding protein 1 (WDHD1), is an adaptor molecule crucial for DNA replication. Although structural information for the AND-1 yeast ortholog is available, the mechanistic details for how human AND-1 protein anchors the lagging-strand DNA polymerase α (pol α) to the DNA helicase complex (Cdc45-MCM2-7-GINS, CMG) await elucidation. Here, we report the structures of the N-terminal WD40 and SepB domains of human AND-1, as well as a biochemical analysis of the C-terminal HMG domain. We show that AND-1 exists as a homotrimer mediated by the SepB domain. Mutant study results suggested that a positively charged groove within the SepB domain provides binding sites for pol α. Different from its ortholog protein in budding yeast, human AND-1 is recruited to the CMG complex, mediated by unknown participants other than Go Ichi Ni San. In addition, we show that AND-1 binds to DNA in vitro, using its C-terminal HMG domain. In conclusion, our findings provide important insights into the mechanistic details of human AND-1 function, advancing our understanding of replisome formation during eukaryotic replication.
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Affiliation(s)
- Chengcheng Guan
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101 and.,the College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Li
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101 and.,the College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dapeng Sun
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101 and
| | - Yingfang Liu
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101 and
| | - Huanhuan Liang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101 and
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58
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Mcm10: A Dynamic Scaffold at Eukaryotic Replication Forks. Genes (Basel) 2017; 8:genes8020073. [PMID: 28218679 PMCID: PMC5333062 DOI: 10.3390/genes8020073] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/09/2017] [Accepted: 02/09/2017] [Indexed: 12/13/2022] Open
Abstract
To complete the duplication of large genomes efficiently, mechanisms have evolved that coordinate DNA unwinding with DNA synthesis and provide quality control measures prior to cell division. Minichromosome maintenance protein 10 (Mcm10) is a conserved component of the eukaryotic replisome that contributes to this process in multiple ways. Mcm10 promotes the initiation of DNA replication through direct interactions with the cell division cycle 45 (Cdc45)-minichromosome maintenance complex proteins 2-7 (Mcm2-7)-go-ichi-ni-san GINS complex proteins, as well as single- and double-stranded DNA. After origin firing, Mcm10 controls replication fork stability to support elongation, primarily facilitating Okazaki fragment synthesis through recruitment of DNA polymerase-α and proliferating cell nuclear antigen. Based on its multivalent properties, Mcm10 serves as an essential scaffold to promote DNA replication and guard against replication stress. Under pathological conditions, Mcm10 is often dysregulated. Genetic amplification and/or overexpression of MCM10 are common in cancer, and can serve as a strong prognostic marker of poor survival. These findings are compatible with a heightened requirement for Mcm10 in transformed cells to overcome limitations for DNA replication dictated by altered cell cycle control. In this review, we highlight advances in our understanding of when, where and how Mcm10 functions within the replisome to protect against barriers that cause incomplete replication.
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59
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Lu L, Jin W, Wang LL. Aging in Rothmund-Thomson syndrome and related RECQL4 genetic disorders. Ageing Res Rev 2017; 33:30-35. [PMID: 27287744 DOI: 10.1016/j.arr.2016.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/03/2016] [Accepted: 06/06/2016] [Indexed: 01/21/2023]
Abstract
Rothmund-Thomson Syndrome (RTS) is a rare autosomal recessive disease which manifests several clinical features of accelerated aging. These findings include atrophic skin and pigment changes, alopecia, osteopenia, cataracts, and an increased incidence of cancer for patients carrying RECQL4 germline mutations. Mutations in RECQL4 are responsible for the majority of cases of RTS. RECQL4 belongs to RECQ DNA helicase family which has been shown to participate in many aspects of DNA metabolism. In the past several years, accumulated evidence indicates that RECQL4 is important not only in cancer development but also in the aging process. In this review, based on recent research data, we summarize the common aging findings in RTS patients and propose possible mechanisms to explain the aging features in these patients.
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Affiliation(s)
- Linchao Lu
- Texas Children's Cancer Center, Department of Pediatrics, Section of Hematology/Oncology, Baylor College of Medicine, 1102 Bates Avenue, Suite 1200, Houston, TX 77030, USA
| | - Weidong Jin
- Texas Children's Cancer Center, Department of Pediatrics, Section of Hematology/Oncology, Baylor College of Medicine, 1102 Bates Avenue, Suite 1200, Houston, TX 77030, USA
| | - Lisa L Wang
- Texas Children's Cancer Center, Department of Pediatrics, Section of Hematology/Oncology, Baylor College of Medicine, 1102 Bates Avenue, Suite 1200, Houston, TX 77030, USA.
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60
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Chen Z, Tran M, Tang M, Wang W, Gong Z, Chen J. Proteomic Analysis Reveals a Novel Mutator S (MutS) Partner Involved in Mismatch Repair Pathway. Mol Cell Proteomics 2016; 15:1299-308. [PMID: 27037360 DOI: 10.1074/mcp.m115.056093] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Indexed: 01/08/2023] Open
Abstract
The mismatch repair (MMR) family is a highly conserved group of proteins that function in correcting base-base and insertion-deletion mismatches generated during DNA replication. Disruption of this process results in characteristic microsatellite instability (MSI), repair defects, and susceptibility to cancer. However, a significant fraction of MSI-positive cancers express MMR genes at normal levels and do not carry detectable mutation in known MMR genes, suggesting that additional factors and/or mechanisms may exist to explain these MSI phenotypes in patients. To systematically investigate the MMR pathway, we conducted a proteomic analysis and identified MMR-associated protein complexes using tandem-affinity purification coupled with mass spectrometry (TAP-MS) method. The mass spectrometry data have been deposited to the ProteomeXchange with identifier PXD003014 and DOI 10.6019/PXD003014. We identified 230 high-confidence candidate interaction proteins (HCIPs). We subsequently focused on MSH2, an essential component of the MMR pathway and uncovered a novel MSH2-binding partner, WDHD1. We further demonstrated that WDHD1 forms a stable complex with MSH2 and MSH3 or MSH6,i.e.the MutS complexes. The specific MSH2/WDHD1 interaction is mediated by the second lever domain of MSH2 and Ala(1123)site of WDHD1. Moreover, we showed that, just like MSH2-deficient cells, depletion of WDHD1 also led to 6-thioguanine (6-TG) resistance, indicating that WDHD1 likely contributes to the MMR pathway. Taken together, our study uncovers new components involved in the MMR pathway, which provides candidate genes that may be responsible for the development of MSI-positive cancers.
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Affiliation(s)
- Zhen Chen
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Mykim Tran
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Mengfan Tang
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Wenqi Wang
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Zihua Gong
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Junjie Chen
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
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61
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Chen Z, Tran M, Tang M, Wang W, Gong Z, Chen J. Proteomic Analysis Reveals a Novel Mutator S (MutS) Partner Involved in Mismatch Repair Pathway. Mol Cell Proteomics 2016. [PMID: 27037360 DOI: 10.1074/mcp.m115.056093+] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mismatch repair (MMR) family is a highly conserved group of proteins that function in correcting base-base and insertion-deletion mismatches generated during DNA replication. Disruption of this process results in characteristic microsatellite instability (MSI), repair defects, and susceptibility to cancer. However, a significant fraction of MSI-positive cancers express MMR genes at normal levels and do not carry detectable mutation in known MMR genes, suggesting that additional factors and/or mechanisms may exist to explain these MSI phenotypes in patients. To systematically investigate the MMR pathway, we conducted a proteomic analysis and identified MMR-associated protein complexes using tandem-affinity purification coupled with mass spectrometry (TAP-MS) method. The mass spectrometry data have been deposited to the ProteomeXchange with identifier PXD003014 and DOI 10.6019/PXD003014. We identified 230 high-confidence candidate interaction proteins (HCIPs). We subsequently focused on MSH2, an essential component of the MMR pathway and uncovered a novel MSH2-binding partner, WDHD1. We further demonstrated that WDHD1 forms a stable complex with MSH2 and MSH3 or MSH6,i.e.the MutS complexes. The specific MSH2/WDHD1 interaction is mediated by the second lever domain of MSH2 and Ala(1123)site of WDHD1. Moreover, we showed that, just like MSH2-deficient cells, depletion of WDHD1 also led to 6-thioguanine (6-TG) resistance, indicating that WDHD1 likely contributes to the MMR pathway. Taken together, our study uncovers new components involved in the MMR pathway, which provides candidate genes that may be responsible for the development of MSI-positive cancers.
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Affiliation(s)
- Zhen Chen
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Mykim Tran
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Mengfan Tang
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Wenqi Wang
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Zihua Gong
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
| | - Junjie Chen
- From the ‡Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, 6565 MD Anderson Boulevard, Houston, TX 77030
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62
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Cellular responses to replication stress: Implications in cancer biology and therapy. DNA Repair (Amst) 2016; 49:9-20. [PMID: 27908669 DOI: 10.1016/j.dnarep.2016.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/15/2016] [Indexed: 12/11/2022]
Abstract
DNA replication is essential for cell proliferation. Any obstacles during replication cause replication stress, which may lead to genomic instability and cancer formation. In this review, we summarize the physiological DNA replication process and the normal cellular response to replication stress. We also outline specialized therapies in clinical trials based on current knowledge and future perspectives in the field.
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63
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Distinct functions of human RecQ helicases during DNA replication. Biophys Chem 2016; 225:20-26. [PMID: 27876204 DOI: 10.1016/j.bpc.2016.11.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/13/2016] [Accepted: 11/13/2016] [Indexed: 12/31/2022]
Abstract
DNA replication is the most vulnerable process of DNA metabolism in proliferating cells and therefore it is tightly controlled and coordinated with processes that maintain genomic stability. Human RecQ helicases are among the most important factors involved in the maintenance of replication fork integrity, especially under conditions of replication stress. RecQ helicases promote recovery of replication forks being stalled due to different replication roadblocks of either exogenous or endogenous source. They prevent generation of aberrant replication fork structures and replication fork collapse, and are involved in proper checkpoint signaling. The essential role of human RecQ helicases in the genome maintenance during DNA replication is underlined by association of defects in their function with cancer predisposition.
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Xu X, Wang JT, Li M, Liu Y. TIMELESS Suppresses the Accumulation of Aberrant CDC45·MCM2-7·GINS Replicative Helicase Complexes on Human Chromatin. J Biol Chem 2016; 291:22544-22558. [PMID: 27587400 PMCID: PMC5077192 DOI: 10.1074/jbc.m116.719963] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 08/31/2016] [Indexed: 07/24/2023] Open
Abstract
The replication licensing factor CDC6 recruits the MCM2-7 replicative helicase to the replication origin, where MCM2-7 is activated to initiate DNA replication. MCM2-7 is activated by both the CDC7-Dbf4 kinase and cyclin-dependent kinase and via interactions with CDC45 and go-ichi-ni-san complex (GINS) to form the CDC45·MCM2-7·GINS (CMG) helicase complex. TIMELESS (TIM) is important for the subsequent coupling of CMG activity to DNA polymerases for efficient DNA synthesis. However, the mechanism by which TIM regulates CMG activity for proper replication fork progression remains unclear. Here we show that TIM interacts with MCM2-7 prior to the initiation of DNA replication. TIM depletion in various human cell lines results in the accumulation of aberrant CMG helicase complexes on chromatin. Importantly, the presence of these abnormal CMG helicase complexes is not restricted to cells undergoing DNA synthesis. Furthermore, even though these aberrant CMG complexes interact with the DNA polymerases on human chromatin, these complexes are not phosphorylated properly by cyclin-dependent kinase/CDC7-Dbf4 kinase and exhibit reduced DNA unwinding activity. This phenomenon coincides with a significant accumulation of the p27 and p21 replication inhibitors, reduced chromatin association of CDC6 and cyclin E, and a delay in S phase entry. Our results provide the first evidence that TIM is required for the correct chromatin association of the CMG complex to allow efficient DNA replication.
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Affiliation(s)
- Xiaohua Xu
- From the Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, California 91010-3000
| | - Jiin-Tarng Wang
- From the Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, California 91010-3000
| | - Min Li
- From the Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, California 91010-3000
| | - Yilun Liu
- From the Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, California 91010-3000
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Perez-Arnaiz P, Kaplan DL. An Mcm10 Mutant Defective in ssDNA Binding Shows Defects in DNA Replication Initiation. J Mol Biol 2016; 428:4608-4625. [PMID: 27751725 DOI: 10.1016/j.jmb.2016.10.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 09/28/2016] [Accepted: 10/07/2016] [Indexed: 11/25/2022]
Abstract
Mcm10 is an essential protein that functions to initiate DNA replication after the formation of the replication fork helicase. In this manuscript, we identified a budding yeast Mcm10 mutant (Mcm10-m2,3,4) that is defective in DNA binding in vitro. Moreover, this Mcm10-m2,3,4 mutant does not stimulate the phosphorylation of Mcm2 by Dbf4-dependent kinase (DDK) in vitro. When we expressed wild-type levels of mcm10-m2,3,4 in budding yeast cells, we observed a severe growth defect and a substantially decreased DNA replication. We also observed a substantially reduced replication protein A- chromatin immunoprecipitation signal at origins of replication, reduced levels of DDK-phosphorylated Mcm2, and diminished Go, Ichi, Ni, and San (GINS) association with Mcm2-7 in vivo. mcm5-bob1 bypasses the growth defect conferred by DDK-phosphodead Mcm2 in budding yeast. However, the growth defect observed by expressing mcm10-m2,3,4 is not bypassed by the mcm5-bob1 mutation. Furthermore, origin melting and GINS association with Mcm2-7 are substantially decreased for cells expressing mcm10-m2,3,4 in the mcm5-bob1 background. Thus, the origin melting and GINS-Mcm2-7 interaction defects we observed for mcm10-m2,3,4 are not explained by decreased Mcm2 phosphorylation by DDK, since the defects persist in an mcm5-bob1 background. These data suggest that DNA binding by Mcm10 is essential for the initiation of DNA replication.
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Affiliation(s)
- Patricia Perez-Arnaiz
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA
| | - Daniel L Kaplan
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA.
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Interaction of RECQ4 and MCM10 is important for efficient DNA replication origin firing in human cells. Oncotarget 2016; 6:40464-79. [PMID: 26588054 PMCID: PMC4747346 DOI: 10.18632/oncotarget.6342] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 11/10/2015] [Indexed: 12/17/2022] Open
Abstract
DNA replication is a highly coordinated process that is initiated at multiple replication origins in eukaryotes. These origins are bound by the origin recognition complex (ORC), which subsequently recruits the Mcm2-7 replicative helicase in a Cdt1/Cdc6-dependent manner. In budding yeast, two essential replication factors, Sld2 and Mcm10, are then important for the activation of replication origins. In humans, the putative Sld2 homolog, RECQ4, interacts with MCM10. Here, we have identified two mutants of human RECQ4 that are deficient in binding to MCM10. We show that these RECQ4 variants are able to complement the lethality of an avian cell RECQ4 deletion mutant, indicating that the essential function of RECQ4 in vertebrates is unlikely to require binding to MCM10. Nevertheless, we show that the RECQ4-MCM10 interaction is important for efficient replication origin firing.
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67
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Peng YP, Zhu Y, Yin LD, Zhang JJ, Guo S, Fu Y, Miao Y, Wei JS. The Expression and Prognostic Roles of MCMs in Pancreatic Cancer. PLoS One 2016; 11:e0164150. [PMID: 27695057 PMCID: PMC5047525 DOI: 10.1371/journal.pone.0164150] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/20/2016] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES Minichromosome maintenance (MCM) proteins play important roles in DNA replication by interacting with other factors which participate in the regulation of DNA synthesis. Abnormal over-expression of MCMs was observed in numerous malignancies, such as colorectal cancer. However, the expression of MCMs in pancreatic cancer (PC) was less investigated so far. This study was designed to analyze the expression and prognostic roles of MCM1-10 in PC based on the data provided by The Cancer Genome Atlas (TCGA). METHODS Pearson χ2 test was applied to evaluate the association of MCMs expression with clinicopathologic indicators, and biomarkers for tumor biological behaviors. Kaplan-Meier plots and log-rank tests were used to assess survival analysis, and univariate and multivariate Cox proportional hazard regression models were used to recognize independent prognostic factors. RESULTS MCM1-10 were generally expressed in PC samples. The levels of some molecules were markedly correlated with that of biomarkers for S phase, proliferation, gemcitabine resistance. And part of these molecules over-expression was significantly associated with indicators of disease progression, such as depth of tumor invasion and lymph node metastasis. Furthermore, MCM2, 4, 6, 8, and 10 over-expression was remarkably associated with shorter disease free survival time, and MCM2, 4,8, and 10 over-expression was associated with shorter overall survival time. Further multivariate analysis suggested that MCM8 was an independent prognostic factor for PC. CONCLUSION MCMs abnormal over-expression was significantly associated with PC progression and prognosis. These molecules could be regarded as prognostic and therapeutic biomarkers for PC. The roles of MCMs may be vitally important and the underlying mechanisms need to be furtherinvestigated.
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Affiliation(s)
- Yun-Peng Peng
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
| | - Yi Zhu
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
| | - Ling-Di Yin
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
| | - Jing-Jing Zhang
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
| | - Song Guo
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
| | - Yue Fu
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
| | - Yi Miao
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- * E-mail: (MY); (WJ-S)
| | - Ji-Shu Wei
- Pancreas Institute of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Pancreas Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- Department of General Surgery, The first Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People’s Republic of China
- * E-mail: (MY); (WJ-S)
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Abstract
Each time a cell duplicates, the whole genome must be accurately copied and distributed. The enormous amount of DNA in eukaryotic cells requires a high level of coordination between polymerases and other DNA and chromatin-interacting proteins to ensure timely and accurate DNA replication and chromatin formation. PCNA forms a ring that encircles the DNA. It serves as a processivity factor for DNA polymerases and as a landing platform for different proteins that interact with DNA and chromatin. It thus serves as a signaling hub and influences the rate and accuracy of DNA replication, the r-formation of chromatin in the wake of the moving fork and the proper segregation of the sister chromatids. Four different, conserved, protein complexes are in charge of loading/unloading PCNA and similar molecules onto DNA. Replication factor C (RFC) is the canonical complex in charge of loading PCNA, the replication clamp, during S-phase. The Rad24, Ctf18 and Elg1 proteins form complexes similar to RFC, with particular functions in the cell's nucleus. Here we summarize our current knowledge about the roles of these important factors in yeast.
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Affiliation(s)
- Martin Kupiec
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
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69
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Chadha GS, Gambus A, Gillespie PJ, Blow JJ. Xenopus Mcm10 is a CDK-substrate required for replication fork stability. Cell Cycle 2016; 15:2183-2195. [PMID: 27327991 PMCID: PMC4993430 DOI: 10.1080/15384101.2016.1199305] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/01/2016] [Accepted: 06/03/2016] [Indexed: 12/17/2022] Open
Abstract
During S phase, following activation of the S phase CDKs and the DBF4-dependent kinases (DDK), double hexamers of Mcm2-7 at licensed replication origins are activated to form the core replicative helicase. Mcm10 is one of several proteins that have been implicated from work in yeasts to play a role in forming a mature replisome during the initiation process. Mcm10 has also been proposed to play a role in promoting replisome stability after initiation has taken place. The role of Mcm10 is particularly unclear in metazoans, where conflicting data has been presented. Here, we investigate the role and regulation of Mcm10 in Xenopus egg extracts. We show that Xenopus Mcm10 is recruited to chromatin late in the process of replication initiation and this requires prior action of DDKs and CDKs. We also provide evidence that Mcm10 is a CDK substrate but does not need to be phosphorylated in order to associate with chromatin. We show that in extracts depleted of more than 99% of Mcm10, the bulk of DNA replication still occurs, suggesting that Mcm10 is not required for the process of replication initiation. However, in extracts depleted of Mcm10, the replication fork elongation rate is reduced. Furthermore, the absence of Mcm10 or its phosphorylation by CDK results in instability of replisome proteins on DNA, which is particularly important under conditions of replication stress.
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Affiliation(s)
- Gaganmeet Singh Chadha
- a Centre for Gene Regulation & Expression, School of Life Sciences, University of Dundee , Dundee , UK
| | - Agnieszka Gambus
- a Centre for Gene Regulation & Expression, School of Life Sciences, University of Dundee , Dundee , UK
| | - Peter J Gillespie
- a Centre for Gene Regulation & Expression, School of Life Sciences, University of Dundee , Dundee , UK
| | - J Julian Blow
- a Centre for Gene Regulation & Expression, School of Life Sciences, University of Dundee , Dundee , UK
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70
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Fenwick AL, Kliszczak M, Cooper F, Murray J, Sanchez-Pulido L, Twigg SRF, Goriely A, McGowan SJ, Miller KA, Taylor IB, Logan C, Bozdogan S, Danda S, Dixon J, Elsayed SM, Elsobky E, Gardham A, Hoffer MJV, Koopmans M, McDonald-McGinn DM, Santen GWE, Savarirayan R, de Silva D, Vanakker O, Wall SA, Wilson LC, Yuregir OO, Zackai EH, Ponting CP, Jackson AP, Wilkie AOM, Niedzwiedz W, Bicknell LS. Mutations in CDC45, Encoding an Essential Component of the Pre-initiation Complex, Cause Meier-Gorlin Syndrome and Craniosynostosis. Am J Hum Genet 2016; 99:125-38. [PMID: 27374770 PMCID: PMC5005452 DOI: 10.1016/j.ajhg.2016.05.019] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/09/2016] [Indexed: 11/19/2022] Open
Abstract
DNA replication precisely duplicates the genome to ensure stable inheritance of genetic information. Impaired licensing of origins of replication during the G1 phase of the cell cycle has been implicated in Meier-Gorlin syndrome (MGS), a disorder defined by the triad of short stature, microtia, and a/hypoplastic patellae. Biallelic partial loss-of-function mutations in multiple components of the pre-replication complex (preRC; ORC1, ORC4, ORC6, CDT1, or CDC6) as well as de novo stabilizing mutations in the licensing inhibitor, GMNN, cause MGS. Here we report the identification of mutations in CDC45 in 15 affected individuals from 12 families with MGS and/or craniosynostosis. CDC45 encodes a component of both the pre-initiation (preIC) and CMG helicase complexes, required for initiation of DNA replication origin firing and ongoing DNA synthesis during S-phase itself, respectively, and hence is functionally distinct from previously identified MGS-associated genes. The phenotypes of affected individuals range from syndromic coronal craniosynostosis to severe growth restriction, fulfilling diagnostic criteria for Meier-Gorlin syndrome. All mutations identified were biallelic and included synonymous mutations altering splicing of physiological CDC45 transcripts, as well as amino acid substitutions expected to result in partial loss of function. Functionally, mutations reduce levels of full-length transcripts and protein in subject cells, consistent with partial loss of CDC45 function and a predicted limited rate of DNA replication and cell proliferation. Our findings therefore implicate the preIC as an additional protein complex involved in the etiology of MGS and connect the core cellular machinery of genome replication with growth, chondrogenesis, and cranial suture homeostasis.
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Affiliation(s)
- Aimee L Fenwick
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Maciej Kliszczak
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK; Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Fay Cooper
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Jennie Murray
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Luis Sanchez-Pulido
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Stephen R F Twigg
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Anne Goriely
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Simon J McGowan
- Computational Biology Research Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Kerry A Miller
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Indira B Taylor
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Clare Logan
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Sevcan Bozdogan
- Department of Medical Genetics, Mersin University, Mersin, 33343 Cukurova, Turkey
| | - Sumita Danda
- Department of Clinical Genetics, Christian Medical College and Hospital, Vellore, Tamil Nadu 632004, India
| | - Joanne Dixon
- Genetic Health Service NZ-South Island Hub, Christchurch Hospital, Christchurch, Canterbury 8140, New Zealand
| | - Solaf M Elsayed
- Children's Hospital, Ain Shams University, Cairo 11566, Egypt
| | - Ezzat Elsobky
- Children's Hospital, Ain Shams University, Cairo 11566, Egypt
| | - Alice Gardham
- North East Thames Regional Genetics Service, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Mariette J V Hoffer
- Department of Clinical Genetics, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Marije Koopmans
- Department of Clinical Genetics, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Donna M McDonald-McGinn
- Clinical Genetics, The Children's Hospital of Philadelphia, 34th & Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Gijs W E Santen
- Department of Clinical Genetics, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Ravi Savarirayan
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Deepthi de Silva
- Department of Physiology, Faculty of Medicine, University of Kelaniya, Ragama, Gampaha GQ 11010, Sri Lanka
| | - Olivier Vanakker
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
| | - Steven A Wall
- Craniofacial Unit, Department of Plastic and Reconstructive Surgery, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Louise C Wilson
- North East Thames Regional Genetics Service, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Ozge Ozalp Yuregir
- Genetic Diagnosis Center, Adana Numune Training and Research Hospital, Cukurova, Adana, 01170, Turkey
| | - Elaine H Zackai
- Clinical Genetics, The Children's Hospital of Philadelphia, 34th & Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Chris P Ponting
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Andrew P Jackson
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Andrew O M Wilkie
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK; Craniofacial Unit, Department of Plastic and Reconstructive Surgery, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Wojciech Niedzwiedz
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK.
| | - Louise S Bicknell
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK; Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, Otago 9016, New Zealand.
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71
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Villa F, Simon AC, Ortiz Bazan MA, Kilkenny ML, Wirthensohn D, Wightman M, Matak-Vinkovíc D, Pellegrini L, Labib K. Ctf4 Is a Hub in the Eukaryotic Replisome that Links Multiple CIP-Box Proteins to the CMG Helicase. Mol Cell 2016; 63:385-96. [PMID: 27397685 PMCID: PMC4980431 DOI: 10.1016/j.molcel.2016.06.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 05/12/2016] [Accepted: 06/06/2016] [Indexed: 11/26/2022]
Abstract
Replisome assembly at eukaryotic replication forks connects the DNA helicase to DNA polymerases and many other factors. The helicase binds the leading-strand polymerase directly, but is connected to the Pol α lagging-strand polymerase by the trimeric adaptor Ctf4. Here, we identify new Ctf4 partners in addition to Pol α and helicase, all of which contain a “Ctf4-interacting-peptide” or CIP-box. Crystallographic analysis classifies CIP-boxes into two related groups that target different sites on Ctf4. Mutations in the CIP-box motifs of the Dna2 nuclease or the rDNA-associated protein Tof2 do not perturb DNA synthesis genome-wide, but instead lead to a dramatic shortening of chromosome 12 that contains the large array of rDNA repeats. Our data reveal unexpected complexity of Ctf4 function, as a hub that connects multiple accessory factors to the replisome. Most strikingly, Ctf4-dependent recruitment of CIP-box proteins couples other processes to DNA synthesis, including rDNA copy-number regulation. Ctf4 is a hub that links factors with diverse functions to the eukaryotic replisome Multiple Ctf4 partners bind via short sequences called “CIP-boxes” The CIP-boxes of Dna2 and Tof2 bind to distinct sites on Ctf4 Interaction of Dna2 and Tof2 with Ctf4 is important for rDNA copy number maintenance
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Affiliation(s)
- Fabrizio Villa
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Aline C Simon
- Department of Biochemistry, University of Cambridge, 80, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Maria Angeles Ortiz Bazan
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Mairi L Kilkenny
- Department of Biochemistry, University of Cambridge, 80, Tennis Court Road, Cambridge CB2 1GA, UK
| | - David Wirthensohn
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Mel Wightman
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Dijana Matak-Vinkovíc
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, 80, Tennis Court Road, Cambridge CB2 1GA, UK.
| | - Karim Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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72
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Lu H, Shamanna RA, Keijzers G, Anand R, Rasmussen LJ, Cejka P, Croteau DL, Bohr VA. RECQL4 Promotes DNA End Resection in Repair of DNA Double-Strand Breaks. Cell Rep 2016; 16:161-173. [PMID: 27320928 DOI: 10.1016/j.celrep.2016.05.079] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/25/2016] [Accepted: 05/19/2016] [Indexed: 01/01/2023] Open
Abstract
The RecQ helicase RECQL4, mutated in Rothmund-Thomson syndrome, regulates genome stability, aging, and cancer. Here, we identify a crucial role for RECQL4 in DNA end resection, which is the initial and an essential step of homologous recombination (HR)-dependent DNA double-strand break repair (DSBR). Depletion of RECQL4 severely reduces HR-mediated repair and 5' end resection in vivo. RECQL4 physically interacts with MRE11-RAD50-NBS1 (MRN), which senses DSBs and initiates DNA end resection with CtIP. The MRE11 exonuclease regulates the retention of RECQL4 at laser-induced DSBs. RECQL4 also directly interacts with CtIP via its N-terminal domain and promotes CtIP recruitment to the MRN complex at DSBs. Moreover, inactivation of RECQL4's helicase activity impairs DNA end processing and HR-dependent DSBR without affecting its interaction with MRE11 and CtIP, suggesting an important role for RECQL4's unwinding activity in the process. Thus, we report that RECQL4 is an important participant in HR-dependent DSBR.
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Affiliation(s)
- Huiming Lu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Raghavendra A Shamanna
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Guido Keijzers
- Center for Healthy Aging and Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Roopesh Anand
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Lene Juel Rasmussen
- Center for Healthy Aging and Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Petr Cejka
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; Center for Healthy Aging and Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark.
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73
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Devlin R, Marques CA, Paape D, Prorocic M, Zurita-Leal AC, Campbell SJ, Lapsley C, Dickens N, McCulloch R. Mapping replication dynamics in Trypanosoma brucei reveals a link with telomere transcription and antigenic variation. eLife 2016; 5:e12765. [PMID: 27228154 PMCID: PMC4946898 DOI: 10.7554/elife.12765] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 05/26/2016] [Indexed: 01/14/2023] Open
Abstract
Survival of Trypanosoma brucei depends upon switches in its protective Variant Surface Glycoprotein (VSG) coat by antigenic variation. VSG switching occurs by frequent homologous recombination, which is thought to require locus-specific initiation. Here, we show that a RecQ helicase, RECQ2, acts to repair DNA breaks, including in the telomeric site of VSG expression. Despite this, RECQ2 loss does not impair antigenic variation, but causes increased VSG switching by recombination, arguing against models for VSG switch initiation through direct generation of a DNA double strand break (DSB). Indeed, we show DSBs inefficiently direct recombination in the VSG expression site. By mapping genome replication dynamics, we reveal that the transcribed VSG expression site is the only telomeric site that is early replicating - a differential timing only seen in mammal-infective parasites. Specific association between VSG transcription and replication timing reveals a model for antigenic variation based on replication-derived DNA fragility.
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Affiliation(s)
- Rebecca Devlin
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Catarina A Marques
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Daniel Paape
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Marko Prorocic
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Andrea C Zurita-Leal
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Samantha J Campbell
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Craig Lapsley
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Nicholas Dickens
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Richard McCulloch
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
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74
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Nguyen BCQ, Tawata S. The Chemistry and Biological Activities of Mimosine: A Review. Phytother Res 2016; 30:1230-42. [PMID: 27213712 DOI: 10.1002/ptr.5636] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 04/05/2016] [Accepted: 04/12/2016] [Indexed: 12/14/2022]
Abstract
Mimosine [β-[N-(3-hydroxy-4-oxypyridyl)]-α-aminopropionic acid] is a non-protein amino acid found in the members of Mimosoideae family. There are a considerable number of reports available on the chemistry, methods for estimation, biosynthesis, regulation, and degradation of this secondary metabolite. On the other hand, over the past years of active research, mimosine has been found to have various biological activities such as anti-cancer, antiinflammation, anti-fibrosis, anti-influenza, anti-virus, herbicidal and insecticidal activities, and others. Mimosine is a leading compound of interest for use in the development of RAC/CDC42-activated kinase 1 (PAK1)-specific inhibitors for the treatment of various diseases/disorders, because PAK1 is not essential for the growth of normal cells. Interestingly, the new roles of mimosine in malignant glioma treatment, regenerative dentistry, and phytoremediation are being emerged. These identified properties indicate an exciting future for this amino acid. The present review is focused on the chemistry and recognized biological activities of mimosine in an attempt to draw a link between these two characteristics. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Binh Cao Quan Nguyen
- Department of Bioscience and Biotechnology, The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, 890-0065, Japan.,PAK Research Center, Okinawa, 903-0213, Japan
| | - Shinkichi Tawata
- PAK Research Center, Okinawa, 903-0213, Japan.,Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, Senbaru 1, Nishihara-cho, Okinawa, 903-0213, Japan
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75
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Hutchins JRA, Aze A, Coulombe P, Méchali M. Characteristics of Metazoan DNA Replication Origins. DNA REPLICATION, RECOMBINATION, AND REPAIR 2016. [PMCID: PMC7120227 DOI: 10.1007/978-4-431-55873-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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76
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Sanuki Y, Kubota Y, Kanemaki MT, Takahashi TS, Mimura S, Takisawa H. RecQ4 promotes the conversion of the pre-initiation complex at a site-specific origin for DNA unwinding in Xenopus egg extracts. Cell Cycle 2015; 14:1010-23. [PMID: 25602506 DOI: 10.1080/15384101.2015.1007003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Eukaryotic DNA replication is initiated through stepwise assembly of evolutionarily conserved replication proteins onto replication origins, but how the origin DNA is unwound during the assembly process remains elusive. Here, we established a site-specific origin on a plasmid DNA, using in vitro replication systems derived from Xenopus egg extracts. We found that the pre-replicative complex (pre-RC) was preferentially assembled in the vicinity of GAL4 DNA-binding sites of the plasmid, depending on the binding of Cdc6 fused with a GAL4 DNA-binding domain in Cdc6-depleted extracts. Subsequent addition of nucleoplasmic S-phase extracts to the GAL4-dependent pre-RC promoted initiation of DNA replication from the origin, and components of the pre-initiation complex (pre-IC) and the replisome were recruited to the origin concomitant with origin unwinding. In this replication system, RecQ4 is dispensable for both recruitment of Cdc45 onto the origin and stable binding of Cdc45 and GINS to the pre-RC assembled plasmid. However, both origin binding of DNA polymerase α and unwinding of DNA were diminished upon depletion of RecQ4 from the extracts. These results suggest that RecQ4 plays an important role in the conversion of pre-ICs into active replisomes requiring the unwinding of origin DNA in vertebrates.
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Affiliation(s)
- Yosuke Sanuki
- a Department of Biological Sciences; Graduate School of Science ; Osaka University ; Toyonaka , Osaka , Japan
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77
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Bruck I, Perez-Arnaiz P, Colbert MK, Kaplan DL. Insights into the Initiation of Eukaryotic DNA Replication. Nucleus 2015; 6:449-54. [PMID: 26710261 DOI: 10.1080/19491034.2015.1115938] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The initiation of DNA replication is a highly regulated event in eukaryotic cells to ensure that the entire genome is copied once and only once during S phase. The primary target of cellular regulation of eukaryotic DNA replication initiation is the assembly and activation of the replication fork helicase, the 11-subunit assembly that unwinds DNA at a replication fork. The replication fork helicase, called CMG for Cdc45-Mcm2-7, and GINS, assembles in S phase from the constituent Cdc45, Mcm2-7, and GINS proteins. The assembly and activation of the CMG replication fork helicase during S phase is governed by 2 S-phase specific kinases, CDK and DDK. CDK stimulates the interaction between Sld2, Sld3, and Dpb11, 3 initiation factors that are each required for the initiation of DNA replication. DDK, on the other hand, phosphorylates the Mcm2, Mcm4, and Mcm6 subunits of the Mcm2-7 complex. Sld3 recruits Cdc45 to Mcm2-7 in a manner that depends on DDK, and recent work suggests that Sld3 binds directly to Mcm2-7 and also to single-stranded DNA. Furthermore, recent work demonstrates that Sld3 and its human homolog Treslin substantially stimulate DDK phosphorylation of Mcm2. These data suggest that the initiation factor Sld3/Treslin coordinates the assembly and activation of the eukaryotic replication fork helicase by recruiting Cdc45 to Mcm2-7, stimulating DDK phosphorylation of Mcm2, and binding directly to single-stranded DNA as the origin is melted.
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Affiliation(s)
- Irina Bruck
- a Department of Biomedical Science; Florida State University College of Medicine ; Tallahassee , FL USA
| | - Patricia Perez-Arnaiz
- a Department of Biomedical Science; Florida State University College of Medicine ; Tallahassee , FL USA
| | - Max K Colbert
- a Department of Biomedical Science; Florida State University College of Medicine ; Tallahassee , FL USA
| | - Daniel L Kaplan
- a Department of Biomedical Science; Florida State University College of Medicine ; Tallahassee , FL USA
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78
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Im JS, Park SY, Cho WH, Bae SH, Hurwitz J, Lee JK. RecQL4 is required for the association of Mcm10 and Ctf4 with replication origins in human cells. Cell Cycle 2015; 14:1001-9. [PMID: 25602958 DOI: 10.1080/15384101.2015.1007001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Though RecQL4 was shown to be essential for the initiation of DNA replication in mammalian cells, its role in initiation is poorly understood. Here, we show that RecQL4 is required for the origin binding of Mcm10 and Ctf4, and their physical interactions and association with replication origins are controlled by the concerted action of both CDK and DDK activities. Although RecQL4-dependent binding of Mcm10 and Ctf4 to chromatin can occur in the absence of pre-replicative complex, their association with replication origins requires the presence of the pre-replicative complex and CDK and DDK activities. Their association with replication origins and physical interactions are also targets of the DNA damage checkpoint pathways which prevent initiation of DNA replication at replication origins. Taken together, the RecQL4-dependent association of Mcm10 and Ctf4 with replication origins appears to be the first important step controlled by S phase promoting kinases and checkpoint pathways for the initiation of DNA replication in human cells.
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Affiliation(s)
- Jun-Sub Im
- a Department of Biology Education; Seoul National University ; Seoul , Korea
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79
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Perez-Arnaiz P, Bruck I, Kaplan DL. Mcm10 coordinates the timely assembly and activation of the replication fork helicase. Nucleic Acids Res 2015; 44:315-29. [PMID: 26582917 PMCID: PMC4705653 DOI: 10.1093/nar/gkv1260] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/02/2015] [Indexed: 11/12/2022] Open
Abstract
Mcm10 is an essential replication factor that is required for DNA replication in eukaryotes. Two key steps in the initiation of DNA replication are the assembly and activation of Cdc45–Mcm2–7-GINS (CMG) replicative helicase. However, it is not known what coordinates helicase assembly with helicase activation. We show in this manuscript, using purified proteins from budding yeast, that Mcm10 directly interacts with the Mcm2–7 complex and Cdc45. In fact, Mcm10 recruits Cdc45 to Mcm2–7 complex in vitro. To study the role of Mcm10 in more detail in vivo we used an auxin inducible degron in which Mcm10 is degraded upon addition of auxin. We show in this manuscript that Mcm10 is required for the timely recruitment of Cdc45 and GINS recruitment to the Mcm2–7 complex in vivo during early S phase. We also found that Mcm10 stimulates Mcm2 phosphorylation by DDK in vivo and in vitro. These findings indicate that Mcm10 plays a critical role in coupling replicative helicase assembly with helicase activation. Mcm10 is first involved in the recruitment of Cdc45 to the Mcm2–7 complex. After Cdc45–Mcm2–7 complex assembly, Mcm10 promotes origin melting by stimulating DDK phosphorylation of Mcm2, which thereby leads to GINS attachment to Mcm2–7.
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Affiliation(s)
- Patricia Perez-Arnaiz
- Florida State University College of Medicine, Department of Biomedical Sciences, Tallahassee, FL 32306, USA
| | - Irina Bruck
- Florida State University College of Medicine, Department of Biomedical Sciences, Tallahassee, FL 32306, USA
| | - Daniel L Kaplan
- Florida State University College of Medicine, Department of Biomedical Sciences, Tallahassee, FL 32306, USA
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80
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Bruck I, Kaplan DL. The Replication Initiation Protein Sld3/Treslin Orchestrates the Assembly of the Replication Fork Helicase during S Phase. J Biol Chem 2015; 290:27414-27424. [PMID: 26405041 DOI: 10.1074/jbc.m115.688424] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Indexed: 11/06/2022] Open
Abstract
The initiation of DNA replication is a highly regulated process in eukaryotic cells, and central to the process of initiation is the assembly and activation of the replication fork helicase. The replication fork helicase is comprised of CMG (Cdc45, Mcm2-7, and GINS) in eukaryotic cells, and the mechanism underlying assembly of the CMG during S phase was studied in this article. We identified a point mutation of Sld3 that is specifically defective for Mcm3 and Mcm5 interaction (sld3-m10), and also identified a point mutation of Sld3 that is specifically defective for single-stranded DNA (ssDNA) interaction (sld3-m9). Expression of wild-type levels of sld3-m9 resulted in a severe DNA replication defect with no recruitment of GINS to Mcm2-7, whereas expression of wild-type levels of sld3-m10 resulted in a severe replication defect with no Cdc45 recruitment to Mcm2-7. We propose a model for Sld3-mediated control of replication initiation, wherein Sld3 manages the proper assembly of the CMG during S phase. We also find that the biochemical functions identified for Sld3 are conserved in human Treslin, suggesting that Treslin orchestrates assembly of the CMG in human cells.
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Affiliation(s)
- Irina Bruck
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306
| | - Daniel L Kaplan
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306.
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81
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Reubens MC, Biller MD, Bedsole SE, Hopkins LT, Ables ET, Christensen TW. Mcm10 is required for oogenesis and early embryogenesis in Drosophila. Mech Dev 2015; 138 Pt 3:291-9. [PMID: 26369283 DOI: 10.1016/j.mod.2015.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 08/27/2015] [Accepted: 09/08/2015] [Indexed: 01/05/2023]
Abstract
Efficient replication of the genome and the establishment of endogenous chromatin states are processes that are essential to eukaryotic life. It is well documented that Mcm10 is intimately linked to both of these important biological processes; therefore, it is not surprising that Mcm10 is commonly misregulated in many human cancers. Most of the research regarding the biological roles of Mcm10 has been performed in single-cell or cell-free in-vitro systems. Though these systems are informative, they are unable to provide information on the cell-specific function of Mcm10 in the context of the tissue and organ systems that comprise multicellular eukaryotes. We therefore sought to identify the potential biological functions of Mcm10 in the context of a complex multicellular organism by continuing our analysis in Drosophila using three novel hypomorphic alleles. Observation of embryonic nuclear morphology and quantification of embryo hatch rates reveal that maternal loading of Mcm10 is required for embryonic nuclear stability, and suggest a role for Mcm10 post zygotic transition. Contrary to the essential nature of Mcm10 depicted in the literature, it does not appear to be required for adult viability in Drosophila if embryonic requirements are met. Although not required for adult somatic viability, analysis of fecundity and ovarian morphology in mutant females suggest that Mcm10 plays a role in maintenance of the female germline. Taken together, our results demonstrate critical roles for Mcm10 during early embryogenesis, and mark the first data linking Mcm10 to female specific reproduction in multicellular eukaryotes.
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Affiliation(s)
- Michael C Reubens
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Megan D Biller
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Sidney E Bedsole
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Lucas T Hopkins
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Elizabeth T Ables
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Tim W Christensen
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
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82
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Akhmedov AT, Marín-García J. Mitochondrial DNA maintenance: an appraisal. Mol Cell Biochem 2015; 409:283-305. [DOI: 10.1007/s11010-015-2532-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/06/2015] [Indexed: 12/13/2022]
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83
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Abstract
DNA replication begins with the assembly of pre-replication complexes (pre-RCs) at thousands of DNA replication origins during the G1 phase of the cell cycle. At the G1-S-phase transition, pre-RCs are converted into pre-initiation complexes, in which the replicative helicase is activated, leading to DNA unwinding and initiation of DNA synthesis. However, only a subset of origins are activated during any S phase. Recent insights into the mechanisms underlying this choice reveal how flexibility in origin usage and temporal activation are linked to chromosome structure and organization, cell growth and differentiation, and replication stress.
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84
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Lee KY, Dutta A. Initiation of replication in Xenopus egg extracts at a spatially defined origin. Cell Cycle 2015; 14:2391. [PMID: 26091433 DOI: 10.1080/15384101.2015.1063306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Kyung Yong Lee
- a Department of Biochemistry and Molecular Genetics ; University of Virginia ; Charlottesville , VA USA
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85
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Hao J, de Renty C, Li Y, Xiao H, Kemp MG, Han Z, DePamphilis ML, Zhu W. And-1 coordinates with Claspin for efficient Chk1 activation in response to replication stress. EMBO J 2015; 34:2096-110. [PMID: 26082189 DOI: 10.15252/embj.201488016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 05/08/2015] [Indexed: 11/09/2022] Open
Abstract
The replisome is important for DNA replication checkpoint activation, but how specific components of the replisome coordinate with ATR to activate Chk1 in human cells remains largely unknown. Here, we demonstrate that And-1, a replisome component, acts together with ATR to activate Chk1. And-1 is phosphorylated at T826 by ATR following replication stress, and this phosphorylation is required for And-1 to accumulate at the damage sites, where And-1 promotes the interaction between Claspin and Chk1, thereby stimulating efficient Chk1 activation by ATR. Significantly, And-1 binds directly to ssDNA and facilitates the association of Claspin with ssDNA. Furthermore, And-1 associates with replication forks and is required for the recovery of stalled forks. These studies establish a novel ATR-And-1 axis as an important regulator for efficient Chk1 activation and reveal a novel mechanism of how the replisome regulates the replication checkpoint and genomic stability.
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Affiliation(s)
- Jing Hao
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical School, Washington, DC, USA
| | | | - Yongming Li
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical School, Washington, DC, USA
| | - Haijie Xiao
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical School, Washington, DC, USA
| | - Michael G Kemp
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL, USA
| | - Zhiyong Han
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical School, Washington, DC, USA
| | | | - Wenge Zhu
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical School, Washington, DC, USA
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86
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Ding L, Liu Y. Borrowing nuclear DNA helicases to protect mitochondrial DNA. Int J Mol Sci 2015; 16:10870-87. [PMID: 25984607 PMCID: PMC4463680 DOI: 10.3390/ijms160510870] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 05/09/2015] [Accepted: 05/11/2015] [Indexed: 01/20/2023] Open
Abstract
In normal cells, mitochondria are the primary organelles that generate energy, which is critical for cellular metabolism. Mitochondrial dysfunction, caused by mitochondrial DNA (mtDNA) mutations or an abnormal mtDNA copy number, is linked to a range of human diseases, including Alzheimer's disease, premature aging and cancer. mtDNA resides in the mitochondrial lumen, and its duplication requires the mtDNA replicative helicase, Twinkle. In addition to Twinkle, many DNA helicases, which are encoded by the nuclear genome and are crucial for nuclear genome integrity, are transported into the mitochondrion to also function in mtDNA replication and repair. To date, these helicases include RecQ-like helicase 4 (RECQ4), petite integration frequency 1 (PIF1), DNA replication helicase/nuclease 2 (DNA2) and suppressor of var1 3-like protein 1 (SUV3). Although the nuclear functions of some of these DNA helicases have been extensively studied, the regulation of their mitochondrial transport and the mechanisms by which they contribute to mtDNA synthesis and maintenance remain largely unknown. In this review, we attempt to summarize recent research progress on the role of mammalian DNA helicases in mitochondrial genome maintenance and the effects on mitochondria-associated diseases.
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Affiliation(s)
- Lin Ding
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
| | - Yilun Liu
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
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87
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RECQ4 selectively recognizes Holliday junctions. DNA Repair (Amst) 2015; 30:80-9. [PMID: 25769792 DOI: 10.1016/j.dnarep.2015.02.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 02/20/2015] [Accepted: 02/21/2015] [Indexed: 12/23/2022]
Abstract
The RECQ4 protein belongs to the RecQ helicase family, which plays crucial roles in genome maintenance. Mutations in the RECQ4 gene are associated with three insidious hereditary disorders: Rothmund-Thomson, Baller-Gerold, and RAPADILINO syndromes. These syndromes are characterized by growth deficiency, radial ray defects, red rashes, and higher predisposition to malignancy, especially osteosarcomas. Within the RecQ family, RECQ4 is the least characterized, and its role in DNA replication and repair remains unknown. We have identified several DNA binding sites within RECQ4. Two are located at the N-terminus and one is located within the conserved helicase domain. N-terminal domains probably cooperate with one another and promote the strong annealing activity of RECQ4. Surprisingly, the region spanning 322-400aa shows a very high affinity for branched DNA substrates, especially Holliday junctions. This study demonstrates biochemical activities of RECQ4 that could be involved in genome maintenance and suggest its possible role in processing replication and recombination intermediates.
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88
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Petojevic T, Pesavento JJ, Costa A, Liang J, Wang Z, Berger JM, Botchan MR. Cdc45 (cell division cycle protein 45) guards the gate of the Eukaryote Replisome helicase stabilizing leading strand engagement. Proc Natl Acad Sci U S A 2015; 112:E249-58. [PMID: 25561522 PMCID: PMC4311868 DOI: 10.1073/pnas.1422003112] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
DNA replication licensing is now understood to be the pathway that leads to the assembly of double hexamers of minichromosome maintenance (Mcm2-7) at origin sites. Cell division control protein 45 (Cdc45) and GINS proteins activate the latent Mcm2-7 helicase by inducing allosteric changes through binding, forming a Cdc45/Mcm2-7/GINS (CMG) complex that is competent to unwind duplex DNA. The CMG has an active gate between subunits Mcm2 and Mcm5 that opens and closes in response to nucleotide binding. The consequences of inappropriate Mcm2/5 gate actuation and the role of a side channel formed between GINS/Cdc45 and the outer edge of the Mcm2-7 ring for unwinding have remained unexplored. Here we uncover a novel function for Cdc45. Cross-linking studies trace the path of the DNA with the CMG complex at a fork junction between duplex and single strands with the bound CMG in an open or closed gate conformation. In the closed state, the lagging strand does not pass through the side channel, but in the open state, the leading strand surprisingly interacts with Cdc45. Mutations in the recombination protein J fold of Cdc45 that ablate this interaction diminish helicase activity. These data indicate that Cdc45 serves as a shield to guard against occasional slippage of the leading strand from the core channel.
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Affiliation(s)
- Tatjana Petojevic
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720; Department of Biology, Chemistry and Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - James J Pesavento
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720
| | - Alessandro Costa
- Clare Hall Laboratories, London Research Institute, South Mimms, Herts EN6 3LD, United Kingdom; and
| | - Jingdan Liang
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720
| | - Zhijun Wang
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720
| | - James M Berger
- Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205
| | - Michael R Botchan
- Department of Molecular and Cell Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94720;
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89
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Zegerman P. Evolutionary conservation of the CDK targets in eukaryotic DNA replication initiation. Chromosoma 2015; 124:309-21. [PMID: 25575982 DOI: 10.1007/s00412-014-0500-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 11/27/2014] [Accepted: 12/01/2014] [Indexed: 10/24/2022]
Abstract
A fundamental requirement for all organisms is the faithful duplication and transmission of the genetic material. Failure to accurately copy and segregate the genome during cell division leads to loss of genetic information and chromosomal abnormalities. Such genome instability is the hallmark of the earliest stages of tumour formation. Cyclin-dependent kinase (CDK) plays a vital role in regulating the duplication of the genome within the eukaryotic cell cycle. Importantly, this kinase is deregulated in many cancer types and is an emerging target of chemotherapeutics. In this review, I will consider recent advances concerning the role of CDK in replication initiation across eukaryotes. The implications for strict CDK-dependent regulation of genome duplication in the context of the cell cycle will be discussed.
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Affiliation(s)
- Philip Zegerman
- Department of Biochemistry, Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, The Henry Wellcome Building of Cancer and Developmental Biology, Cambridge, CB2 1QN, UK,
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90
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Elg1, a central player in genome stability. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 763:267-79. [PMID: 25795125 DOI: 10.1016/j.mrrev.2014.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/15/2014] [Accepted: 11/17/2014] [Indexed: 11/20/2022]
Abstract
ELG1 is a conserved gene uncovered in a number of genetic screens in yeast aimed at identifying factors important in the maintenance of genome stability. Elg1's activity prevents gross chromosomal rearrangements, maintains proper telomere length regulation, helps repairing DNA damage created by a number of genotoxins and participates in sister chromatid cohesion. Elg1 is evolutionarily conserved, and its mammalian ortholog (also known as ATAD5) is embryonic lethal when lost in mice, acts as a tumor suppressor in mice and humans, exhibits physical interactions with components of the human Fanconi Anemia pathway and may be responsible for some of the phenotypes associated with neurofibromatosis. In this review, we summarize the information available on Elg1-related activities in yeast and mammals, and present models to explain how the different phenotypes observed in the absence of Elg1 activity are related.
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91
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Keller H, Kiosze K, Sachsenweger J, Haumann S, Ohlenschläger O, Nuutinen T, Syväoja JE, Görlach M, Grosse F, Pospiech H. The intrinsically disordered amino-terminal region of human RecQL4: multiple DNA-binding domains confer annealing, strand exchange and G4 DNA binding. Nucleic Acids Res 2014; 42:12614-27. [PMID: 25336622 PMCID: PMC4227796 DOI: 10.1093/nar/gku993] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/20/2014] [Accepted: 10/06/2014] [Indexed: 01/01/2023] Open
Abstract
Human RecQL4 belongs to the ubiquitous RecQ helicase family. Its N-terminal region represents the only homologue of the essential DNA replication initiation factor Sld2 of Saccharomyces cerevisiae, and also participates in the vertebrate initiation of DNA replication. Here, we utilized a random screen to identify N-terminal fragments of human RecQL4 that could be stably expressed in and purified from Escherichia coli. Biophysical characterization of these fragments revealed that the Sld2 homologous RecQL4 N-terminal domain carries large intrinsically disordered regions. The N-terminal fragments were sufficient for the strong annealing activity of RecQL4. Moreover, this activity appeared to be the basis for an ATP-independent strand exchange activity. Both activities relied on multiple DNA-binding sites with affinities to single-stranded, double-stranded and Y-structured DNA. Finally, we found a remarkable affinity of the N-terminus for guanine quadruplex (G4) DNA, exceeding the affinities for other DNA structures by at least 60-fold. Together, these findings suggest that the DNA interactions mediated by the N-terminal region of human RecQL4 represent a central function at the replication fork. The presented data may also provide a mechanistic explanation for the role of elements with a G4-forming propensity identified in the vicinity of vertebrate origins of DNA replication.
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Affiliation(s)
- Heidi Keller
- Research Group Biochemistry, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Kristin Kiosze
- Research Group Biochemistry, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Juliane Sachsenweger
- Research Group Biochemistry, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Sebastian Haumann
- Research Group Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Oliver Ohlenschläger
- Research Group Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Tarmo Nuutinen
- Department of Biology, University of Eastern Finland, PO Box 111, FI-80101 Joensuu, Finland
| | - Juhani E Syväoja
- Institute of Biomedicine, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
| | - Matthias Görlach
- Research Group Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Frank Grosse
- Research Group Biochemistry, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany Center for Molecular Biomedicine, Friedrich-Schiller University, Jena, Germany
| | - Helmut Pospiech
- Research Group Biochemistry, Leibniz Institute for Age Research-Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany Faculty of Biochemistry and Molecular Medicine, PO Box 5000, FI-90014 University of Oulu, Finland
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92
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MCM Paradox: Abundance of Eukaryotic Replicative Helicases and Genomic Integrity. Mol Biol Int 2014; 2014:574850. [PMID: 25386362 PMCID: PMC4217321 DOI: 10.1155/2014/574850] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 09/30/2014] [Indexed: 12/03/2022] Open
Abstract
As a crucial component of DNA replication licensing system, minichromosome maintenance (MCM) 2–7 complex acts as the eukaryotic DNA replicative helicase. The six related MCM proteins form a heterohexamer and bind with ORC, CDC6, and Cdt1 to form the prereplication complex. Although the MCMs are well known as replicative helicases, their overabundance and distribution patterns on chromatin present a paradox called the “MCM paradox.” Several approaches had been taken to solve the MCM paradox and describe the purpose of excess MCMs distributed beyond the replication origins. Alternative functions of these MCMs rather than a helicase had also been proposed. This review focuses on several models and concepts generated to solve the MCM paradox coinciding with their helicase function and provides insight into the concept that excess MCMs are meant for licensing dormant origins as a backup during replication stress. Finally, we extend our view towards the effect of alteration of MCM level. Though an excess MCM constituent is needed for normal cells to withstand stress, there must be a delineation of the threshold level in normal and malignant cells. This review also outlooks the future prospects to better understand the MCM biology.
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93
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Tognetti S, Riera A, Speck C. Switch on the engine: how the eukaryotic replicative helicase MCM2-7 becomes activated. Chromosoma 2014; 124:13-26. [PMID: 25308420 DOI: 10.1007/s00412-014-0489-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 09/24/2014] [Accepted: 09/25/2014] [Indexed: 12/17/2022]
Abstract
A crucial step during eukaryotic initiation of DNA replication is the correct loading and activation of the replicative DNA helicase, which ensures that each replication origin fires only once. Unregulated DNA helicase loading and activation, as it occurs in cancer, can cause severe DNA damage and genomic instability. The essential mini-chromosome maintenance proteins 2-7 (MCM2-7) represent the core of the eukaryotic replicative helicase that is loaded at DNA replication origins during G1-phase of the cell cycle. The MCM2-7 helicase activity, however, is only triggered during S-phase once the holo-helicase Cdc45-MCM2-7-GINS (CMG) has been formed. A large number of factors and several kinases interact and contribute to CMG formation and helicase activation, though the exact mechanisms remain unclear. Crucially, upon DNA damage, this reaction is temporarily halted to ensure genome integrity. Here, we review the current understanding of helicase activation; we focus on protein interactions during CMG formation, discuss structural changes during helicase activation, and outline similarities and differences of the prokaryotic and eukaryotic helicase activation process.
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Affiliation(s)
- Silvia Tognetti
- DNA Replication Group, Institute of Clinical Science, Imperial College, London, W12 0NN, UK
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94
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Zhang X, Weissman SM, Newburger PE. Long intergenic non-coding RNA HOTAIRM1 regulates cell cycle progression during myeloid maturation in NB4 human promyelocytic leukemia cells. RNA Biol 2014; 11:777-87. [PMID: 24824789 DOI: 10.4161/rna.28828] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
HOTAIRM1 is a long intergenic non-coding RNA encoded in the human HOXA gene cluster, with gene expression highly specific for maturing myeloid cells. Knockdown of HOTAIRM1 in the NB4 acute promyelocytic leukemia cell line retarded all-trans retinoid acid (ATRA)-induced granulocytic differentiation, resulting in a significantly larger population of immature and proliferating cells that maintained cell cycle progression from G1 to S phases. Correspondingly, HOTAIRM1 knockdown resulted in retained expression of many otherwise ATRA-suppressed cell cycle and DNA replication genes, and abated ATRA induction of cell surface leukocyte activation, defense response, and other maturation-related genes. Resistance to ATRA-induced cell cycle arrest at the G1/S phase transition in knockdown cells was accompanied by retained expression of ITGA4 (CD49d) and decreased induction of ITGAX (CD11c). The coupling of cell cycle progression with temporal dynamics in the expression patterns of these integrin genes suggests a regulated switch to control the transit from the proliferative phase to granulocytic maturation. Furthermore, ITGAX was among a small number of genes showing perturbation in transcript levels upon HOTAIRM1 knockdown even without ATRA treatment, suggesting a direct pathway of regulation. These results indicate that HOTAIRM1 provides a regulatory link in myeloid maturation by modulating integrin-controlled cell cycle progression at the gene expression level.
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Affiliation(s)
- Xueqing Zhang
- Department of Pediatrics; University of Massachusetts Medical School; Worcester, MA USA
| | | | - Peter E Newburger
- Department of Pediatrics; University of Massachusetts Medical School; Worcester, MA USA; Department of Cancer Biology; University of Massachusetts Medical School; Worcester, MA USA
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95
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Wang JT, Xu X, Alontaga AY, Chen Y, Liu Y. Impaired p32 regulation caused by the lymphoma-prone RECQ4 mutation drives mitochondrial dysfunction. Cell Rep 2014; 7:848-58. [PMID: 24746816 DOI: 10.1016/j.celrep.2014.03.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 01/06/2014] [Accepted: 03/12/2014] [Indexed: 10/25/2022] Open
Abstract
Mitochondrial DNA (mtDNA) encodes proteins that are important for ATP biogenesis. Therefore, changes in mtDNA copy number will have profound consequences on cell survival and proliferation. RECQ4 DNA helicase participates in both nuclear DNA and mtDNA synthesis. However, the mechanism that balances the distribution of RECQ4 in the nucleus and mitochondria is unknown. Here, we show that RECQ4 forms protein complexes with Protein Phosphatase 2A (PP2A), nucleophosmin (NPM), and mitochondrial p32 in different cellular compartments. Critically, the interaction with p32 negatively controls the transport of both RECQ4 and its chromatin-associated replication factor, MCM10, from the nucleus to mitochondria. Amino acids that are deleted in the most common cancer-associated RECQ4 mutation are required for the interaction with p32. Hence, this RECQ4 mutant, which is no longer regulated by p32 and is enriched in the mitochondria, interacts with the mitochondrial replication helicase PEO1 and induces abnormally high levels of mtDNA synthesis.
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Affiliation(s)
- Jiin-Tarng Wang
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA
| | - Xiaohua Xu
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA
| | - Aileen Y Alontaga
- Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA
| | - Yuan Chen
- Department of Molecular Medicine, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA
| | - Yilun Liu
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
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96
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The RBBP6/ZBTB38/MCM10 axis regulates DNA replication and common fragile site stability. Cell Rep 2014; 7:575-587. [PMID: 24726359 DOI: 10.1016/j.celrep.2014.03.030] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 01/17/2014] [Accepted: 03/09/2014] [Indexed: 11/23/2022] Open
Abstract
Faithful DNA replication is essential for the maintenance of genome integrity. Incomplete genome replication leads to DNA breaks and chromosomal rearrangements, which are causal factors in cancer and other human diseases. Despite their importance, the molecular mechanisms that control human genome stability are incompletely understood. Here, we report a pathway that is required for human genome replication and stability. This pathway has three components: an E3 ubiquitin ligase, a transcriptional repressor, and a replication protein. The E3 ubiquitin ligase RBBP6 ubiquitinates and destabilizes the transcriptional repressor ZBTB38. This repressor negatively regulates transcription and levels of the MCM10 replication factor on chromatin. Cells lacking RBBP6 experience reduced replication fork progression and increased damage at common fragile sites due to ZBTB38 accumulation and MCM10 downregulation. Our results uncover a pathway that ensures genome-wide DNA replication and chromosomal stability.
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97
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Gaggioli V, Zeiser E, Rivers D, Bradshaw CR, Ahringer J, Zegerman P. CDK phosphorylation of SLD-2 is required for replication initiation and germline development in C. elegans. ACTA ACUST UNITED AC 2014; 204:507-22. [PMID: 24535824 PMCID: PMC3926958 DOI: 10.1083/jcb.201310083] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Timely phosphorylation of SLD-2 by CDK is essential for proper replication initiation and cell proliferation in the germline of C. elegans. Cyclin-dependent kinase (CDK) plays a vital role in proliferation control across eukaryotes. Despite this, how CDK mediates cell cycle and developmental transitions in metazoa is poorly understood. In this paper, we identify orthologues of Sld2, a CDK target that is important for DNA replication in yeast, and characterize SLD-2 in the nematode worm Caenorhabditis elegans. We demonstrate that SLD-2 is required for replication initiation and the nuclear retention of a critical component of the replicative helicase CDC-45 in embryos. SLD-2 is a CDK target in vivo, and phosphorylation regulates the interaction with another replication factor, MUS-101. By mutation of the CDK sites in sld-2, we show that CDK phosphorylation of SLD-2 is essential in C. elegans. Finally, using a phosphomimicking sld-2 mutant, we demonstrate that timely CDK phosphorylation of SLD-2 is an important control mechanism to allow normal proliferation in the germline. These results determine an essential function of CDK in metazoa and identify a developmental role for regulated SLD-2 phosphorylation.
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Affiliation(s)
- Vincent Gaggioli
- Wellcome Trust/Cancer Research UK Gurdon Institute, 2 Department of Genetics, and 3 Department of Zoology, University of Cambridge, Cambridge CB2 1QN, England, UK
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98
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Leman AR, Noguchi E. The replication fork: understanding the eukaryotic replication machinery and the challenges to genome duplication. Genes (Basel) 2014; 4:1-32. [PMID: 23599899 PMCID: PMC3627427 DOI: 10.3390/genes4010001] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Eukaryotic cells must accurately and efficiently duplicate their genomes during each round of the cell cycle. Multiple linear chromosomes, an abundance of regulatory elements, and chromosome packaging are all challenges that the eukaryotic DNA replication machinery must successfully overcome. The replication machinery, the “replisome” complex, is composed of many specialized proteins with functions in supporting replication by DNA polymerases. Efficient replisome progression relies on tight coordination between the various factors of the replisome. Further, replisome progression must occur on less than ideal templates at various genomic loci. Here, we describe the functions of the major replisome components, as well as some of the obstacles to efficient DNA replication that the replisome confronts. Together, this review summarizes current understanding of the vastly complicated task of replicating eukaryotic DNA.
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Affiliation(s)
- Adam R. Leman
- Authors to whom correspondence should be addressed; E-Mails: (A.R.L.); (E.N.); Tel.: +1-215-762-4825 (E.N.); Fax: +1-215-762-4452 (E.N.)
| | - Eishi Noguchi
- Authors to whom correspondence should be addressed; E-Mails: (A.R.L.); (E.N.); Tel.: +1-215-762-4825 (E.N.); Fax: +1-215-762-4452 (E.N.)
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99
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Croteau DL, Popuri V, Opresko PL, Bohr VA. Human RecQ helicases in DNA repair, recombination, and replication. Annu Rev Biochem 2014; 83:519-52. [PMID: 24606147 DOI: 10.1146/annurev-biochem-060713-035428] [Citation(s) in RCA: 404] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
RecQ helicases are an important family of genome surveillance proteins conserved from bacteria to humans. Each of the five human RecQ helicases plays critical roles in genome maintenance and stability, and the RecQ protein family members are often referred to as guardians of the genome. The importance of these proteins in cellular homeostasis is underscored by the fact that defects in BLM, WRN, and RECQL4 are linked to distinct heritable human disease syndromes. Each human RecQ helicase has a unique set of protein-interacting partners, and these interactions dictate its specialized functions in genome maintenance, including DNA repair, recombination, replication, and transcription. Human RecQ helicases also interact with each other, and these interactions have significant impact on enzyme function. Future research goals in this field include a better understanding of the division of labor among the human RecQ helicases and learning how human RecQ helicases collaborate and cooperate to enhance genome stability.
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Affiliation(s)
- Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, Maryland 21224;
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100
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Abstract
The RECQ family of DNA helicases is a conserved group of enzymes that are important for maintaining genomic integrity. In humans, there are five RECQ helicase genes, and mutations in three of them-BLM, WRN, and RECQL4-are associated with the genetic disorders Bloom syndrome, Werner syndrome, and Rothmund-Thomson syndrome (RTS), respectively. Importantly all three diseases are cancer predisposition syndromes. Patients with RTS are highly and uniquely susceptible to developing osteosarcoma; thus, RTS provides a good model to study the pathogenesis of osteosarcoma. The "tumor suppressor" role of RECQL4 and the other RECQ helicases is an area of active investigation. This chapter reviews what is currently known about the cellular functions of RECQL4 and how these may relate to tumorigenesis, as well as ongoing efforts to understand RECQL4's functions in vivo using animal models. Understanding the RECQ pathways may provide insight into avenues for novel cancer therapies in the future.
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