1
|
Stewart GS. DONSON: Slding in 2 the limelight. DNA Repair (Amst) 2024; 134:103616. [PMID: 38159447 DOI: 10.1016/j.dnarep.2023.103616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/18/2023] [Accepted: 12/19/2023] [Indexed: 01/03/2024]
Abstract
For over a decade, it has been known that yeast Sld2, Dpb11, GINS and Polε form the pre-loading complex (pre-LC), which is recruited to a CDC45-bound MCM2-7 complex by the Sld3/Sld7 heterodimer in a phospho-dependent manner. Whilst functional orthologs of Dbp11 (TOPBP1), Sld3 (TICRR) and Sld7 (MTBP) have been identified in metazoans, controversy has surrounded the identity of the Sld2 ortholog. It was originally proposed that the RECQ helicase, RECQL4, which is mutated in Rothmund-Thomson syndrome, represented the closest vertebrate ortholog of Sld2 due to a small region of sequence homology at its N-Terminus. However, there is no clear evidence that RECQL4 is required for CMG loading. Recently, new findings suggest that the functional ortholog of Sld2 is actually DONSON, a replication fork stability factor mutated in a range of neurodevelopmental disorders characterised by microcephaly, short stature and limb abnormalities. These studies show that DONSON forms a complex with TOPBP1, GINS and Polε analogous to the pre-LC in yeast, which is required to position the GINS complex on the MCM complex and initiate DNA replication. Taken together with previously published functions for DONSON, these observations indicate that DONSON plays two roles in regulating DNA replication, one in promoting replication initiation and one in stabilising the fork during elongation. Combined, these findings may help to uncover why DONSON mutations are associated with such a wide range of clinical deficits.
Collapse
Affiliation(s)
- Grant S Stewart
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
| |
Collapse
|
2
|
Hashimoto Y, Sadano K, Miyata N, Ito H, Tanaka H. Novel role of DONSON in CMG helicase assembly during vertebrate DNA replication initiation. EMBO J 2023; 42:e114131. [PMID: 37458194 PMCID: PMC10476173 DOI: 10.15252/embj.2023114131] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/27/2023] [Accepted: 06/29/2023] [Indexed: 09/05/2023] Open
Abstract
CMG (Cdc45-MCM-GINS) helicase assembly at the replication origin is the culmination of eukaryotic DNA replication initiation. This process can be reconstructed in vitro using defined factors in Saccharomyces cerevisiae; however, in vertebrates, origin-dependent CMG formation has not yet been achieved partly due to the lack of a complete set of known initiator proteins. Since a microcephaly gene product, DONSON, was reported to remodel the CMG helicase under replication stress, we analyzed its role in DNA replication using a Xenopus cell-free system. We found that DONSON was essential for the replisome assembly. In vertebrates, DONSON physically interacted with GINS and Polε via its conserved N-terminal PGY and NPF motifs, and the DONSON-GINS interaction contributed to the replisome assembly. DONSON's chromatin association during replication initiation required the pre-replicative complex, TopBP1, and kinase activities of S-CDK and DDK. Both S-CDK and DDK required DONSON to trigger replication initiation. Moreover, human DONSON could substitute for the Xenopus protein in a cell-free system. These findings indicate that vertebrate DONSON is a novel initiator protein essential for CMG helicase assembly.
Collapse
Affiliation(s)
- Yoshitami Hashimoto
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Kota Sadano
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Nene Miyata
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Haruka Ito
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| | - Hirofumi Tanaka
- School of Life SciencesTokyo University of Pharmacy and Life SciencesTokyoJapan
| |
Collapse
|
3
|
Saleh A, Noguchi Y, Aramayo R, Ivanova ME, Stevens KM, Montoya A, Sunidhi S, Carranza NL, Skwark MJ, Speck C. The structural basis of Cdc7-Dbf4 kinase dependent targeting and phosphorylation of the MCM2-7 double hexamer. Nat Commun 2022; 13:2915. [PMID: 35614055 PMCID: PMC9133112 DOI: 10.1038/s41467-022-30576-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 05/06/2022] [Indexed: 12/12/2022] Open
Abstract
The controlled assembly of replication forks is critical for genome stability. The Dbf4-dependent Cdc7 kinase (DDK) initiates replisome assembly by phosphorylating the MCM2-7 replicative helicase at the N-terminal tails of Mcm2, Mcm4 and Mcm6. At present, it remains poorly understood how DDK docks onto the helicase and how the kinase targets distal Mcm subunits for phosphorylation. Using cryo-electron microscopy and biochemical analysis we discovered that an interaction between the HBRCT domain of Dbf4 with Mcm2 serves as an anchoring point, which supports binding of DDK across the MCM2-7 double-hexamer interface and phosphorylation of Mcm4 on the opposite hexamer. Moreover, a rotation of DDK along its anchoring point allows phosphorylation of Mcm2 and Mcm6. In summary, our work provides fundamental insights into DDK structure, control and selective activation of the MCM2-7 helicase during DNA replication. Importantly, these insights can be exploited for development of novel DDK inhibitors.
Collapse
Affiliation(s)
- Almutasem Saleh
- DNA Replication Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Yasunori Noguchi
- DNA Replication Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Ricardo Aramayo
- DNA Replication Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Marina E Ivanova
- DNA Replication Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Kathryn M Stevens
- DNA Replication Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
- MRC London Institute of Medical Sciences (LMS), Du Cane Road, London, W12 0NN, UK
| | - Alex Montoya
- Proteomics and Metabolomics Facility, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - S Sunidhi
- InstaDeep Ltd, 5 Merchant Square, London, W2 1AY, UK
| | | | | | - Christian Speck
- DNA Replication Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK.
- MRC London Institute of Medical Sciences (LMS), Du Cane Road, London, W12 0NN, UK.
| |
Collapse
|
4
|
Zeraatpisheh Z, Sichani AS, Kamal N, Khamirani HJ, Zoghi S, Ehsani E, Mohammadi S, Tabei SS, Dastgheib SA, Tabei SMB, Dianatpour M. MCM2 mutation causes autosomal dominant nonsyndromic hearing loss (DFNA70): novel variant in the second family. J Genet 2022. [DOI: 10.1007/s12041-022-01364-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
5
|
Cheng J, Li N, Huo Y, Dang S, Tye BK, Gao N, Zhai Y. Structural Insight into the MCM double hexamer activation by Dbf4-Cdc7 kinase. Nat Commun 2022; 13:1396. [PMID: 35296675 PMCID: PMC8927117 DOI: 10.1038/s41467-022-29070-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 02/24/2022] [Indexed: 12/27/2022] Open
Abstract
The Dbf4-dependent kinase Cdc7 (DDK) regulates DNA replication initiation by phosphorylation of the MCM double hexamer (MCM-DH) to promote helicase activation. Here, we determine a series of cryo electron microscopy (cryo-EM) structures of yeast DDK bound to the MCM-DH. These structures, occupied by one or two DDKs, differ primarily in the conformations of the kinase core. The interactions of DDK with the MCM-DH are mediated exclusively by subunit Dbf4 straddling across the hexamer interface on the three N-terminal domains (NTDs) of subunits Mcm2, Mcm6, and Mcm4. This arrangement brings Cdc7 close to its only essential substrate, the N-terminal serine/threonine-rich domain (NSD) of Mcm4. Dbf4 further displaces the NSD from its binding site on Mcm4-NTD, facilitating an immediate targeting of this motif by Cdc7. Moreover, the active center of Cdc7 is occupied by a unique Dbf4 inhibitory loop, which is disengaged when the kinase core assumes wobbling conformations. This study elucidates the versatility of Dbf4 in regulating the ordered multisite phosphorylation of the MCM-DH by Cdc7 kinase during helicase activation.
Collapse
Affiliation(s)
- Jiaxuan Cheng
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, 100871, China.,Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, 100871, China
| | - Yunjing Huo
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Shangyu Dang
- Division of Life Science, The Hong Kong University of Science & Technology, Hong Kong, China
| | - Bik-Kwoon Tye
- Institute for Advanced Study, The Hong Kong University of Science & Technology, Hong Kong, China. .,Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY, 14853, USA.
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, 100871, China. .,National Biomedical Imaging Center, Peking University, Beijing, 100871, China.
| | - Yuanliang Zhai
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China.
| |
Collapse
|
6
|
Structural mechanism for the selective phosphorylation of DNA-loaded MCM double hexamers by the Dbf4-dependent kinase. Nat Struct Mol Biol 2022; 29:10-20. [PMID: 34963704 PMCID: PMC8770131 DOI: 10.1038/s41594-021-00698-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 11/05/2021] [Indexed: 12/04/2022]
Abstract
Loading of the eukaryotic replicative helicase onto replication origins involves two MCM hexamers forming a double hexamer (DH) around duplex DNA. During S phase, helicase activation requires MCM phosphorylation by Dbf4-dependent kinase (DDK), comprising Cdc7 and Dbf4. DDK selectively phosphorylates loaded DHs, but how such fidelity is achieved is unknown. Here, we determine the cryogenic electron microscopy structure of Saccharomyces cerevisiae DDK in the act of phosphorylating a DH. DDK docks onto one MCM ring and phosphorylates the opposed ring. Truncation of the Dbf4 docking domain abrogates DH phosphorylation, yet Cdc7 kinase activity is unaffected. Late origin firing is blocked in response to DNA damage via Dbf4 phosphorylation by the Rad53 checkpoint kinase. DDK phosphorylation by Rad53 impairs DH phosphorylation by blockage of DDK binding to DHs, and also interferes with the Cdc7 active site. Our results explain the structural basis and regulation of the selective phosphorylation of DNA-loaded MCM DHs, which supports bidirectional replication.
Collapse
|
7
|
Dolson A, Sauty SM, Shaban K, Yankulov K. Dbf4-Dependent Kinase: DDK-ated to post-initiation events in DNA replication. Cell Cycle 2021; 20:2348-2360. [PMID: 34662256 DOI: 10.1080/15384101.2021.1986999] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Dbf4-Dependent Kinase (DDK) has a well-established essential role at origins of DNA replication, where it phosphorylates and activates the replicative MCM helicase. It also acts in the response to mutagens and in DNA repair as well as in key steps during meiosis. Recent studies have indicated that, in addition to the MCM helicase, DDK phosphorylates several substrates during the elongation stage of DNA replication or upon replication stress. However, these activities of DDK are not essential for viability. Dbf4-Dependent Kinase is also emerging as a key factor in the regulation of genome-wide origin firing and in replication-coupled chromatin assembly. In this review, we summarize recent progress in our understanding of the diverse roles of DDK.
Collapse
Affiliation(s)
- Andrew Dolson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Safia Mahabub Sauty
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Kholoud Shaban
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Krassimir Yankulov
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| |
Collapse
|
8
|
Aricthota S, Haldar D. DDK/Hsk1 phosphorylates and targets fission yeast histone deacetylase Hst4 for degradation to stabilize stalled DNA replication forks. eLife 2021; 10:70787. [PMID: 34608864 PMCID: PMC8565929 DOI: 10.7554/elife.70787] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 10/01/2021] [Indexed: 01/01/2023] Open
Abstract
In eukaryotes, paused replication forks are prone to collapse, which leads to genomic instability, a hallmark of cancer. Dbf4-dependent kinase (DDK)/Hsk1Cdc7 is a conserved replication initiator kinase with conflicting roles in replication stress response. Here, we show that fission yeast DDK/Hsk1 phosphorylates sirtuin, Hst4 upon replication stress at C-terminal serine residues. Phosphorylation of Hst4 by DDK marks it for degradation via the ubiquitin ligase SCFpof3. Phosphorylation-defective hst4 mutant (4SA-hst4) displays defective recovery from replication stress, faulty fork restart, slow S-phase progression and decreased viability. The highly conserved fork protection complex (FPC) stabilizes stalled replication forks. We found that the recruitment of FPC components, Swi1 and Mcl1 to the chromatin is compromised in the 4SA-hst4 mutant, although whole cell levels increased. These defects are dependent upon H3K56ac and independent of intra S-phase checkpoint activation. Finally, we show conservation of H3K56ac-dependent regulation of Timeless, Tipin, and And-1 in human cells. We propose that degradation of Hst4 via DDK increases H3K56ac, changing the chromatin state in the vicinity of stalled forks facilitating recruitment and function of FPC. Overall, this study identified a crucial role of DDK and FPC in the regulation of replication stress response with implications in cancer therapeutics.
Collapse
Affiliation(s)
- Shalini Aricthota
- Laboratory of Chromatin Biology and Epigenetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, India
| | - Devyani Haldar
- Laboratory of Chromatin Biology and Epigenetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| |
Collapse
|
9
|
Replication initiation: Implications in genome integrity. DNA Repair (Amst) 2021; 103:103131. [PMID: 33992866 DOI: 10.1016/j.dnarep.2021.103131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 02/01/2023]
Abstract
In every cell cycle, billions of nucleotides need to be duplicated within hours, with extraordinary precision and accuracy. The molecular mechanism by which cells regulate the replication event is very complicated, and the entire process begins way before the onset of S phase. During the G1 phase of the cell cycle, cells prepare by assembling essential replication factors to establish the pre-replicative complex at origins, sites that dictate where replication would initiate during S phase. During S phase, the replication process is tightly coupled with the DNA repair system to ensure the fidelity of replication. Defects in replication and any error must be recognized by DNA damage response and checkpoint signaling pathways in order to halt the cell cycle before cells are allowed to divide. The coordination of these processes throughout the cell cycle is therefore critical to achieve genomic integrity and prevent diseases. In this review, we focus on the current understanding of how the replication initiation events are regulated to achieve genome stability.
Collapse
|
10
|
De Jesús-Kim L, Friedman LJ, Lõoke M, Ramsoomair CK, Gelles J, Bell SP. DDK regulates replication initiation by controlling the multiplicity of Cdc45-GINS binding to Mcm2-7. eLife 2021; 10:65471. [PMID: 33616038 PMCID: PMC7954526 DOI: 10.7554/elife.65471] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/21/2021] [Indexed: 01/07/2023] Open
Abstract
The committed step of eukaryotic DNA replication occurs when the pairs of Mcm2-7 replicative helicases that license each replication origin are activated. Helicase activation requires the recruitment of Cdc45 and GINS to Mcm2-7, forming Cdc45-Mcm2-7-GINS complexes (CMGs). Using single-molecule biochemical assays to monitor CMG formation, we found that Cdc45 and GINS are recruited to loaded Mcm2-7 in two stages. Initially, Cdc45, GINS, and likely additional proteins are recruited to unstructured Mcm2-7 N-terminal tails in a Dbf4-dependent kinase (DDK)-dependent manner, forming Cdc45-tail-GINS intermediates (CtGs). DDK phosphorylation of multiple phosphorylation sites on the Mcm2-7 tails modulates the number of CtGs formed per Mcm2-7. In a second, inefficient event, a subset of CtGs transfer their Cdc45 and GINS components to form CMGs. Importantly, higher CtG multiplicity increases the frequency of CMG formation. Our findings reveal the molecular mechanisms sensitizing helicase activation to DDK levels with implications for control of replication origin efficiency and timing.
Collapse
Affiliation(s)
- Lorraine De Jesús-Kim
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Larry J Friedman
- Department of Biochemistry, Brandeis UniversityWalthamUnited States
| | - Marko Lõoke
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Christian K Ramsoomair
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Jeff Gelles
- Department of Biochemistry, Brandeis UniversityWalthamUnited States
| | - Stephen P Bell
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| |
Collapse
|
11
|
Yuan Z, Li H. Molecular mechanisms of eukaryotic origin initiation, replication fork progression, and chromatin maintenance. Biochem J 2020; 477:3499-3525. [PMID: 32970141 PMCID: PMC7574821 DOI: 10.1042/bcj20200065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/29/2020] [Accepted: 09/04/2020] [Indexed: 12/13/2022]
Abstract
Eukaryotic DNA replication is a highly dynamic and tightly regulated process. Replication involves several dozens of replication proteins, including the initiators ORC and Cdc6, replicative CMG helicase, DNA polymerase α-primase, leading-strand DNA polymerase ε, and lagging-strand DNA polymerase δ. These proteins work together in a spatially and temporally controlled manner to synthesize new DNA from the parental DNA templates. During DNA replication, epigenetic information imprinted on DNA and histone proteins is also copied to the daughter DNA to maintain the chromatin status. DNA methyltransferase 1 is primarily responsible for copying the parental DNA methylation pattern into the nascent DNA. Epigenetic information encoded in histones is transferred via a more complex and less well-understood process termed replication-couple nucleosome assembly. Here, we summarize the most recent structural and biochemical insights into DNA replication initiation, replication fork elongation, chromatin assembly and maintenance, and related regulatory mechanisms.
Collapse
Affiliation(s)
- Zuanning Yuan
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, U.S.A
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, U.S.A
| |
Collapse
|
12
|
Abd Wahab S, Remus D. Antagonistic control of DDK binding to licensed replication origins by Mcm2 and Rad53. eLife 2020; 9:58571. [PMID: 32701054 PMCID: PMC7398698 DOI: 10.7554/elife.58571] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/22/2020] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic replication origins are licensed by the loading of the replicative DNA helicase, Mcm2-7, in inactive double hexameric form around DNA. Subsequent origin activation is under control of multiple protein kinases that either promote or inhibit origin activation, which is important for genome maintenance. Using the reconstituted budding yeast DNA replication system, we find that the flexible N-terminal extension (NTE) of Mcm2 promotes the stable recruitment of Dbf4-dependent kinase (DDK) to Mcm2-7 double hexamers, which in turn promotes DDK phosphorylation of Mcm4 and −6 and subsequent origin activation. Conversely, we demonstrate that the checkpoint kinase, Rad53, inhibits DDK binding to Mcm2-7 double hexamers. Unexpectedly, this function is not dependent on Rad53 kinase activity, suggesting steric inhibition of DDK by activated Rad53. These findings identify critical determinants of the origin activation reaction and uncover a novel mechanism for checkpoint-dependent origin inhibition.
Collapse
Affiliation(s)
- Syafiq Abd Wahab
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, United States.,Weill-Cornell Graduate School of Medical Sciences, New York, United States
| | - Dirk Remus
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, United States.,Weill-Cornell Graduate School of Medical Sciences, New York, United States
| |
Collapse
|
13
|
Wahab SA, Remus D. Antagonistic control of DDK binding to licensed replication origins by Mcm2 and Rad53.. [DOI: 10.1101/2020.05.04.077628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
ABSTRACTEukaryotic replication origins are licensed by the loading of the replicative DNA helicase, Mcm2-7, in inactive double hexameric form around DNA. Subsequent origin activation is under control of multiple protein kinases that either promote or inhibit origin activation, which is important for genome maintenance. Using the reconstituted budding yeast DNA replication system, we find that the flexible N-terminal tail of Mcm2 promotes the stable recruitment of Dbf4-dependent kinase (DDK) to Mcm2-7 double hexamers, which in turn promotes DDK phosphorylation of Mcm4 and -6 and subsequent origin activation. Conversely, we demonstrate that the checkpoint kinase, Rad53, inhibits DDK binding to Mcm2-7 double hexamers. Unexpectedly, this function is not dependent on Rad53 kinase activity, but requires Rad53 activation by trans-autophosphorylation, suggesting steric inhibition of DDK by activated Rad53. These findings identify critical determinants of the origin activation reaction and uncover a novel mechanism for checkpoint-dependent origin inhibition.
Collapse
|
14
|
Leturcq M, Mortuaire M, Hardivillé S, Schulz C, Lefebvre T, Vercoutter-Edouart AS. O-GlcNAc transferase associates with the MCM2-7 complex and its silencing destabilizes MCM-MCM interactions. Cell Mol Life Sci 2018; 75:4321-4339. [PMID: 30069701 PMCID: PMC6208770 DOI: 10.1007/s00018-018-2874-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 07/06/2018] [Accepted: 07/13/2018] [Indexed: 02/07/2023]
Abstract
O-GlcNAcylation of proteins is governed by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). The homeostasis of O-GlcNAc cycling is regulated during cell cycle progression and is essential for proper cellular division. We previously reported the O-GlcNAcylation of the minichromosome maintenance proteins MCM2, MCM3, MCM6 and MCM7. These proteins belong to the MCM2-7 complex which is crucial for the initiation of DNA replication through its DNA helicase activity. Here we show that the six subunits of MCM2-7 are O-GlcNAcylated and that O-GlcNAcylation of MCM proteins mainly occurs in the chromatin-bound fraction of synchronized human cells. Moreover, we identify stable interaction between OGT and several MCM subunits. We also show that down-regulation of OGT decreases the chromatin binding of MCM2, MCM6 and MCM7 without affecting their steady-state level. Finally, OGT silencing or OGA inhibition destabilizes MCM2/6 and MCM4/7 interactions in the chromatin-enriched fraction. In conclusion, OGT is a new partner of the MCM2-7 complex and O-GlcNAcylation homeostasis might regulate MCM2-7 complex by regulating the chromatin loading of MCM6 and MCM7 and stabilizing MCM/MCM interactions.
Collapse
Affiliation(s)
- Maïté Leturcq
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Marlène Mortuaire
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Stéphan Hardivillé
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Céline Schulz
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Tony Lefebvre
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | | |
Collapse
|
15
|
Fei L, Xu H. Role of MCM2-7 protein phosphorylation in human cancer cells. Cell Biosci 2018; 8:43. [PMID: 30062004 PMCID: PMC6056998 DOI: 10.1186/s13578-018-0242-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/17/2018] [Indexed: 01/12/2023] Open
Abstract
A heterohexameric complex composed of minichromosome maintenance protein 2–7 (MCM2–7), which acts as a key replicative enzyme in eukaryotes, is crucial for initiating DNA synthesis only once per cell cycle. The MCM complex remains inactive through the G1 phase, until the S phase, when it is activated to initiate replication. During the transition from the G1 to S phase, the MCM undergoes multisite phosphorylation, an important change that promotes subsequent assembly of other replisome members. Phosphorylation is crucial for the regulation of MCM activity and function. MCMs can be phosphorylated by multiple kinases and these phosphorylation events are involved not only in DNA replication but also cell cycle progression and checkpoint response. Dysfunctional phosphorylation of MCMs appears to correlate with the occurrence and development of cancers. In this review, we summarize the currently available data regarding the regulatory mechanisms and functional consequences of MCM phosphorylation and seek the probability that protein kinase inhibitor can be used therapeutically to target MCM phosphorylation in cancer.
Collapse
Affiliation(s)
- Liangru Fei
- Department of Pathology, College of Basic Medical Sciences and the First Affiliated Hospital, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122 Liaoning Province People's Republic of China
| | - Hongtao Xu
- Department of Pathology, College of Basic Medical Sciences and the First Affiliated Hospital, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122 Liaoning Province People's Republic of China
| |
Collapse
|
16
|
Fang D, Lengronne A, Shi D, Forey R, Skrzypczak M, Ginalski K, Yan C, Wang X, Cao Q, Pasero P, Lou H. Dbf4 recruitment by forkhead transcription factors defines an upstream rate-limiting step in determining origin firing timing. Genes Dev 2018; 31:2405-2415. [PMID: 29330352 PMCID: PMC5795786 DOI: 10.1101/gad.306571.117] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 11/30/2017] [Indexed: 12/26/2022]
Abstract
Fang et al. show that Dbf4 is enriched at early origins through its interaction with forkhead transcription factors Fkh1 and Fkh2. Dbf4 interacts directly with Sld3 and promotes the recruitment of downstream limiting factors. Initiation of eukaryotic chromosome replication follows a spatiotemporal program. The current model suggests that replication origins compete for a limited pool of initiation factors. However, it remains to be answered how these limiting factors are preferentially recruited to early origins. Here, we report that Dbf4 is enriched at early origins through its interaction with forkhead transcription factors Fkh1 and Fkh2. This interaction is mediated by the Dbf4 C terminus and was successfully reconstituted in vitro. An interaction-defective mutant, dbf4ΔC, phenocopies fkh alleles in terms of origin firing. Remarkably, genome-wide replication profiles reveal that the direct fusion of the DNA-binding domain (DBD) of Fkh1 to Dbf4 restores the Fkh-dependent origin firing but interferes specifically with the pericentromeric origin activation. Furthermore, Dbf4 interacts directly with Sld3 and promotes the recruitment of downstream limiting factors. These data suggest that Fkh1 targets Dbf4 to a subset of noncentromeric origins to promote early replication in a manner that is reminiscent of the recruitment of Dbf4 to pericentromeric origins by Ctf19.
Collapse
Affiliation(s)
- Dingqiang Fang
- State Key Laboratory of Agro-Biotechnology, Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Armelle Lengronne
- Institute of Human Genetics, Centre National de la Recherche Scientifique, University of Montpellier, Equipe Labellisée Ligue Contre le Cancer, F-34396 Montpellier Cedex 5, France
| | - Di Shi
- State Key Laboratory of Agro-Biotechnology, Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Romain Forey
- Institute of Human Genetics, Centre National de la Recherche Scientifique, University of Montpellier, Equipe Labellisée Ligue Contre le Cancer, F-34396 Montpellier Cedex 5, France
| | - Magdalena Skrzypczak
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, 02-089 Warsaw, Poland
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, 02-089 Warsaw, Poland
| | - Changhui Yan
- Department of Computer Science, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Xiaoke Wang
- State Key Laboratory of Agro-Biotechnology, Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Qinhong Cao
- State Key Laboratory of Agro-Biotechnology, Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Philippe Pasero
- Institute of Human Genetics, Centre National de la Recherche Scientifique, University of Montpellier, Equipe Labellisée Ligue Contre le Cancer, F-34396 Montpellier Cedex 5, France
| | - Huiqiang Lou
- State Key Laboratory of Agro-Biotechnology, Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| |
Collapse
|
17
|
Okada T, Okabe G, Tak YS, Mimura S, Takisawa H, Kubota Y. Suppression of targeting of Dbf4-dependent kinase to pre-replicative complex in G0 nuclei. Genes Cells 2018; 23:94-104. [PMID: 29314475 DOI: 10.1111/gtc.12556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 12/01/2017] [Indexed: 12/01/2022]
Abstract
Intact G0 nuclei isolated from quiescent cells are not capable of DNA replication in interphase Xenopus egg extracts, which allow efficient replication of permeabilized G0 nuclei. Previous studies have shown multiple control mechanisms for maintaining the quiescent state, but DNA replication inhibition of intact G0 nuclei in the extracts remains poorly understood. Here, we showed that pre-RC is assembled on chromatin, but its activation is inhibited after incubating G0 nuclei isolated from quiescent NIH3T3 cells in the extracts. Concomitant with the inhibition of replication, Mcm4 phosphorylation mediated by Dbf4-dependent kinase (DDK) as well as chromatin binding of DDK is suppressed in G0 nuclei without affecting the nuclear transport of DDK. We further found that the nuclear extracts of G0 but not proliferating cells inhibit the binding of recombinant DDK to pre-RC assembled plasmids. In addition, we observed rapid activation of checkpoint kinases after incubating G0 nuclei in the egg extracts. However, specific inhibitors of ATR/ATM are unable to promote DNA replication in G0 nuclei in the egg extracts. We suggest that a novel inhibitory mechanism is functional to prevent the targeting of DDK to pre-RC in G0 nuclei, thereby suppressing DNA replication in Xenopus egg extracts.
Collapse
Affiliation(s)
- Takuya Okada
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.,Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Kyoto, Kyoto, Japan
| | - Gaku Okabe
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.,Engineering Integration Department, Air Water Inc., Osaka, Japan
| | - Yon-Soo Tak
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Satoru Mimura
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Haruhiko Takisawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Yumiko Kubota
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| |
Collapse
|
18
|
Seoane AI, Morgan DO. Firing of Replication Origins Frees Dbf4-Cdc7 to Target Eco1 for Destruction. Curr Biol 2017; 27:2849-2855.e2. [PMID: 28918948 DOI: 10.1016/j.cub.2017.07.070] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/12/2017] [Accepted: 07/31/2017] [Indexed: 12/14/2022]
Abstract
Robust progression through the cell-division cycle depends on the precisely ordered phosphorylation of hundreds of different proteins by cyclin-dependent kinases (CDKs) and other kinases. The order of CDK substrate phosphorylation depends on rising CDK activity, coupled with variations in substrate affinities for different CDK-cyclin complexes and the opposing phosphatases [1-4]. Here, we address the ordering of substrate phosphorylation by a second major cell-cycle kinase, Cdc7-Dbf4 or Dbf4-dependent kinase (DDK). The primary function of DDK is to initiate DNA replication by phosphorylating the Mcm2-7 replicative helicase [5-7]. DDK also phosphorylates the cohesin acetyltransferase Eco1 [8]. Sequential phosphorylations of Eco1 by CDK, DDK, and Mck1 create a phosphodegron that is recognized by the ubiquitin ligase SCFCdc4. DDK, despite being activated in early S phase, does not phosphorylate Eco1 to trigger its degradation until late S phase [8]. DDK associates with docking sites on loaded Mcm double hexamers at unfired replication origins [9, 10]. We hypothesized that these docking interactions sequester limiting amounts of DDK, delaying Eco1 phosphorylation by DDK until replication is complete. Consistent with this hypothesis, we find that overproduction of DDK leads to premature Eco1 degradation. Eco1 degradation also occurs prematurely if Mcm complex loading at origins is prevented by depletion of Cdc6, and Eco1 is stabilized if loaded Mcm complexes are prevented from firing by a Cdc45 mutant. We propose that the timing of Eco1 phosphorylation, and potentially that of other DDK substrates, is determined in part by sequestration of DDK at unfired replication origins during S phase.
Collapse
Affiliation(s)
- Agustin I Seoane
- Departments of Physiology and Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David O Morgan
- Departments of Physiology and Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA.
| |
Collapse
|
19
|
|
20
|
Reconstruction of pathway modification induced by nicotinamide using multi-omic network analyses in triple negative breast cancer. Sci Rep 2017; 7:3466. [PMID: 28615672 PMCID: PMC5471278 DOI: 10.1038/s41598-017-03322-7] [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: 12/21/2016] [Accepted: 04/26/2017] [Indexed: 11/08/2022] Open
Abstract
Triple negative breast cancer (TNBC) is characterized by an aggressive biological behavior in the absence of a specific target agent. Nicotinamide has recently been proven to be a novel therapeutic agent for skin tumors in an ONTRAC trial. We performed combinatory transcriptomic and in-depth proteomic analyses to characterize the network of molecular interactions in TNBC cells treated with nicotinamide. The multi-omic profiles revealed that nicotinamide drives significant functional alterations related to major cellular pathways, including the cell cycle, DNA replication, apoptosis and DNA damage repair. We further elaborated the global interaction networks of molecular events via nicotinamide-inducible expression changes at the mRNA and functional protein levels. This approach indicated that nicotinamide treatment rewires interaction networks toward dysfunction in DNA damage repair and away from a pro-growth state in TNBC. To our knowledge, the high-resolution network interactions identified in the present study provide the first evidence to comprehensively support the hypothesis of nicotinamide as a novel therapeutic agent in TNBC.
Collapse
|
21
|
Abstract
The accurate and complete replication of genomic DNA is essential for all life. In eukaryotic cells, the assembly of the multi-enzyme replisomes that perform replication is divided into stages that occur at distinct phases of the cell cycle. Replicative DNA helicases are loaded around origins of DNA replication exclusively during G1 phase. The loaded helicases are then activated during S phase and associate with the replicative DNA polymerases and other accessory proteins. The function of the resulting replisomes is monitored by checkpoint proteins that protect arrested replisomes and inhibit new initiation when replication is inhibited. The replisome also coordinates nucleosome disassembly, assembly, and the establishment of sister chromatid cohesion. Finally, when two replisomes converge they are disassembled. Studies in Saccharomyces cerevisiae have led the way in our understanding of these processes. Here, we review our increasingly molecular understanding of these events and their regulation.
Collapse
|
22
|
Parker MW, Botchan MR, Berger JM. Mechanisms and regulation of DNA replication initiation in eukaryotes. Crit Rev Biochem Mol Biol 2017; 52:107-144. [PMID: 28094588 DOI: 10.1080/10409238.2016.1274717] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cellular DNA replication is initiated through the action of multiprotein complexes that recognize replication start sites in the chromosome (termed origins) and facilitate duplex DNA melting within these regions. In a typical cell cycle, initiation occurs only once per origin and each round of replication is tightly coupled to cell division. To avoid aberrant origin firing and re-replication, eukaryotes tightly regulate two events in the initiation process: loading of the replicative helicase, MCM2-7, onto chromatin by the origin recognition complex (ORC), and subsequent activation of the helicase by its incorporation into a complex known as the CMG. Recent work has begun to reveal the details of an orchestrated and sequential exchange of initiation factors on DNA that give rise to a replication-competent complex, the replisome. Here, we review the molecular mechanisms that underpin eukaryotic DNA replication initiation - from selecting replication start sites to replicative helicase loading and activation - and describe how these events are often distinctly regulated across different eukaryotic model organisms.
Collapse
Affiliation(s)
- Matthew W Parker
- a Department of Biophysics and Biophysical Chemistry , Johns Hopkins University School of Medicine , Baltimore , MD , USA
| | - Michael R Botchan
- b Department of Molecular and Cell Biology , University of California Berkeley , Berkeley , CA , USA
| | - James M Berger
- a Department of Biophysics and Biophysical Chemistry , Johns Hopkins University School of Medicine , Baltimore , MD , USA
| |
Collapse
|
23
|
Bruck I, Dhingra N, Kaplan DL. A Positive Amplification Mechanism Involving a Kinase and Replication Initiation Factor Helps Assemble the Replication Fork Helicase. J Biol Chem 2017; 292:3062-3073. [PMID: 28082681 DOI: 10.1074/jbc.m116.772368] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 01/11/2017] [Indexed: 01/09/2023] Open
Abstract
The assembly of the replication fork helicase during S phase is key to the initiation of DNA replication in eukaryotic cells. One step in this assembly in budding yeast is the association of Cdc45 with the Mcm2-7 heterohexameric ATPase, and a second step is the assembly of the tetrameric GINS (GG-Ichi-Nii-San) complex with Mcm2-7. Dbf4-dependent kinase (DDK) and S-phase cyclin-dependent kinase (S-CDK) are two S phase-specific kinases that phosphorylate replication proteins during S phase, and Dpb11, Sld2, Sld3, Pol ϵ, and Mcm10 are factors that are also required for replication initiation. However, the exact roles of these initiation factors in assembly of the replication fork helicase remain unclear. We show here that Dpb11 stimulates DDK phosphorylation of the minichromosome maintenance complex protein Mcm4 alone and also of the Mcm2-7 complex and the dsDNA-loaded Mcm2-7 complex. We further demonstrate that Dpb11 can directly recruit DDK to Mcm4. A DDK phosphomimetic mutant of Mcm4 bound Dpb11 with substantially higher affinity than wild-type Mcm4, suggesting a mechanism to recruit Dpb11 to DDK-phosphorylated Mcm2-7. Furthermore, dsDNA-loaded Mcm2-7 harboring the DDK phosphomimetic Mcm4 mutant bound GINS in the presence of Dpb11, suggesting a mechanism for how GINS is recruited to Mcm2-7. We isolated a mutant of Dpb11 that is specifically defective for binding to Mcm4. This mutant, when expressed in budding yeast, diminished cell growth and DNA replication, substantially decreased Mcm4 phosphorylation, and decreased association of GINS with replication origins. We conclude that Dpb11 functions with DDK and Mcm4 in a positive amplification mechanism to trigger the assembly of the replication fork helicase.
Collapse
Affiliation(s)
- Irina Bruck
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306
| | - Nalini Dhingra
- 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.
| |
Collapse
|
24
|
Li H, Lin Z, Bai Y, Chi X, Fu H, Sun R, Liu M, Liu X, Chen L, Shao S. Sinomenine inhibits ovarian cancer cell growth and metastasis by mediating the Wnt/β-catenin pathway via targeting MCM2. RSC Adv 2017. [DOI: 10.1039/c7ra10057d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Sinomenine (SIN), an isoquinoline isolated from the Chinese medicinal plantSinomenium acutum, is well known for its curative effect on rheumatic and arthritic diseases.
Collapse
Affiliation(s)
- Huimin Li
- Department of Histology and Embryology
- Dalian Medical University
- Dalian
- China
| | - Zhikun Lin
- The First Affiliated Hospital of Dalian Medical University
- Dalian
- China
| | - Yuxin Bai
- Department of Histology and Embryology
- Dalian Medical University
- Dalian
- China
| | - Xinming Chi
- Key Laboratory of Proteomics
- Dalian Medical University
- Dalian
- China
| | - Hailu Fu
- Department of Histology and Embryology
- Dalian Medical University
- Dalian
- China
| | - Rui Sun
- The Second Affiliated Hospital of Dalian Medical University
- Dalian
- China
| | - Meizi Liu
- The First Affiliated Hospital of Dalian Medical University
- Dalian
- China
| | - Xuan Liu
- Department of Histology and Embryology
- Dalian Medical University
- Dalian
- China
| | - Liying Chen
- Department of Histology and Embryology
- Dalian Medical University
- Dalian
- China
| | - Shujuan Shao
- Key Laboratory of Proteomics
- Dalian Medical University
- Dalian
- China
| |
Collapse
|
25
|
Duncker BP. Mechanisms Governing DDK Regulation of the Initiation of DNA Replication. Genes (Basel) 2016; 8:genes8010003. [PMID: 28025497 PMCID: PMC5294998 DOI: 10.3390/genes8010003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/13/2016] [Accepted: 12/16/2016] [Indexed: 12/14/2022] Open
Abstract
The budding yeast Dbf4-dependent kinase (DDK) complex—comprised of cell division cycle (Cdc7) kinase and its regulatory subunit dumbbell former 4 (Dbf4)—is required to trigger the initiation of DNA replication through the phosphorylation of multiple minichromosome maintenance complex subunits 2-7 (Mcm2-7). DDK is also a target of the radiation sensitive 53 (Rad53) checkpoint kinase in response to replication stress. Numerous investigations have determined mechanistic details, including the regions of Mcm2, Mcm4, and Mcm6 phosphorylated by DDK, and a number of DDK docking sites. Similarly, the way in which the Rad53 forkhead-associated 1 (FHA1) domain binds to DDK—involving both canonical and non-canonical interactions—has been elucidated. Recent work has revealed mutual promotion of DDK and synthetic lethal with dpb11-1 3 (Sld3) roles. While DDK phosphorylation of Mcm2-7 subunits facilitates their interaction with Sld3 at origins, Sld3 in turn stimulates DDK phosphorylation of Mcm2. Details of a mutually antagonistic relationship between DDK and Rap1-interacting factor 1 (Rif1) have also recently come to light. While Rif1 is able to reverse DDK-mediated Mcm2-7 complex phosphorylation by targeting the protein phosphatase glycogen 7 (Glc7) to origins, there is evidence to suggest that DDK can counteract this activity by binding to and phosphorylating Rif1.
Collapse
Affiliation(s)
- Bernard P Duncker
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L3G1, Canada.
| |
Collapse
|
26
|
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.
Collapse
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)
| |
Collapse
|
27
|
Fang D, Cao Q, Lou H. Sld3-MCM Interaction Facilitated by Dbf4-Dependent Kinase Defines an Essential Step in Eukaryotic DNA Replication Initiation. Front Microbiol 2016; 7:885. [PMID: 27375603 PMCID: PMC4901202 DOI: 10.3389/fmicb.2016.00885] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/25/2016] [Indexed: 11/16/2022] Open
Abstract
Sld3/Treslin is an evolutionarily conserved protein essential for activation of DNA helicase Mcm2-7 and replication initiation in all eukaryotes. Nevertheless, it remains elusive how Sld3 is recruited to origins. Here, we have identified the direct physical association of Sld3 with Mcm2 and Mcm6 subunits in vitro, which is significantly enhanced by DDK in vivo. The Sld3-binding domain (SBD) is mapped to the N-termini of Mcm2 and Mcm6, both of them are essential for cell viability and enriched with the DDK phosphorylation sites. Glutamic acid substitution of four conserved positively charged residues of Sld3 (sld3-4E), near the Cdc45-binding region, interrupts its interaction with Mcm2/6 and causes cell death. By using a temperature-inducible degron (td), we show that deletion of Mcm6 SBD (mcm6ΔN122) abolishes not only Sld3 enrichment at early origins in G1 phase, but also subsequent recruitment of GINS and RPA during S phase. These findings elucidate the in vivo molecular details of the DDK-dependent Sld3-MCM association, which plays a crucial role in MCM helicase activation and origin unwinding.
Collapse
Affiliation(s)
| | | | - Huiqiang Lou
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural UniversityBeijing, China
| |
Collapse
|
28
|
Knockleby J, Kim BJ, Mehta A, Lee H. Cdk1-mediated phosphorylation of Cdc7 suppresses DNA re-replication. Cell Cycle 2016; 15:1494-505. [PMID: 27105124 PMCID: PMC4934051 DOI: 10.1080/15384101.2016.1176658] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 03/23/2016] [Accepted: 04/06/2016] [Indexed: 12/18/2022] Open
Abstract
To maintain genetic stability, the entire mammalian genome must replicate only once per cell cycle. This is largely achieved by strictly regulating the stepwise formation of the pre-replication complex (pre-RC), followed by the activation of individual origins of DNA replication by Cdc7/Dbf4 kinase. However, the mechanism how Cdc7 itself is regulated in the context of cell cycle progression is poorly understood. Here we report that Cdc7 is phosphorylated by a Cdk1-dependent manner during prometaphase on multiple sites, resulting in its dissociation from origins. In contrast, Dbf4 is not removed from origins in prometaphase, nor is it degraded as cells exit mitosis. Our data thus demonstrates that constitutive phosphorylation of Cdc7 at Cdk1 recognition sites, but not the regulation of Dbf4, prevents the initiation of DNA replication in normally cycling cells and under conditions that promote re-replication in G2/M. As cells exit mitosis, PP1α associates with and dephosphorylates Cdc7. Together, our data support a model where Cdc7 (de)phosphorylation is the molecular switch for the activation and inactivation of DNA replication in mitosis, directly connecting Cdc7 and PP1α/Cdk1 to the regulation of once-per-cell cycle DNA replication in mammalian cells.
Collapse
Affiliation(s)
- James Knockleby
- Tumour Biology Group, Advanced Medical Research Institute of Canada, Health Sciences North, Sudbury, Ontario, Canada
| | - Byung Ju Kim
- Tumour Biology Group, Advanced Medical Research Institute of Canada, Health Sciences North, Sudbury, Ontario, Canada
| | - Avani Mehta
- Tumour Biology Group, Advanced Medical Research Institute of Canada, Health Sciences North, Sudbury, Ontario, Canada
| | - Hoyun Lee
- Tumour Biology Group, Advanced Medical Research Institute of Canada, Health Sciences North, Sudbury, Ontario, Canada
- Departments of Medicine, the Faculty of Medicine, the University of Ottawa, Ottawa, Ontario, Canada
- Northern Ontario School of Medicine, Sudbury, Ontario, Canada
| |
Collapse
|
29
|
Ma Y, Kanakousaki K, Buttitta L. How the cell cycle impacts chromatin architecture and influences cell fate. Front Genet 2015; 6:19. [PMID: 25691891 PMCID: PMC4315090 DOI: 10.3389/fgene.2015.00019] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 01/14/2015] [Indexed: 01/17/2023] Open
Abstract
Since the earliest observations of cells undergoing mitosis, it has been clear that there is an intimate relationship between the cell cycle and nuclear chromatin architecture. The nuclear envelope and chromatin undergo robust assembly and disassembly during the cell cycle, and transcriptional and post-transcriptional regulation of histone biogenesis and chromatin modification is controlled in a cell cycle-dependent manner. Chromatin binding proteins and chromatin modifications in turn influence the expression of critical cell cycle regulators, the accessibility of origins for DNA replication, DNA repair, and cell fate. In this review we aim to provide an integrated discussion of how the cell cycle machinery impacts nuclear architecture and vice-versa. We highlight recent advances in understanding cell cycle-dependent histone biogenesis and histone modification deposition, how cell cycle regulators control histone modifier activities, the contribution of chromatin modifications to origin firing for DNA replication, and newly identified roles for nucleoporins in regulating cell cycle gene expression, gene expression memory and differentiation. We close with a discussion of how cell cycle status may impact chromatin to influence cell fate decisions, under normal contexts of differentiation as well as in instances of cell fate reprogramming.
Collapse
Affiliation(s)
- Yiqin Ma
- Department of Molecular, Cellular and Developmental Biology, University of Michigan , Ann Arbor, MI, USA
| | - Kiriaki Kanakousaki
- Department of Molecular, Cellular and Developmental Biology, University of Michigan , Ann Arbor, MI, USA
| | - Laura Buttitta
- Department of Molecular, Cellular and Developmental Biology, University of Michigan , Ann Arbor, MI, USA
| |
Collapse
|
30
|
Sun J, Fernandez-Cid A, Riera A, Tognetti S, Yuan Z, Stillman B, Speck C, Li H. Structural and mechanistic insights into Mcm2-7 double-hexamer assembly and function. Genes Dev 2014; 28:2291-303. [PMID: 25319829 PMCID: PMC4201289 DOI: 10.1101/gad.242313.114] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Eukaryotic cells license each DNA replication origin during G1 phase by assembling a prereplication complex (pre-RC) that contains a Mcm2–7 double hexamer. In this study, Sun et al. examined the helicase loading reaction in the presence of ATP, revealing the basic architecture of a number of pre-RC assembly reaction intermediates, including a newly identified ORC–Cdc6–Mcm2–7–Mcm2–7 complex. The detailed architecture of the Mcm2–7 double hexamer was also established. Eukaryotic cells license each DNA replication origin during G1 phase by assembling a prereplication complex that contains a Mcm2–7 (minichromosome maintenance proteins 2–7) double hexamer. During S phase, each Mcm2–7 hexamer forms the core of a replicative DNA helicase. However, the mechanisms of origin licensing and helicase activation are poorly understood. The helicase loaders ORC–Cdc6 function to recruit a single Cdt1–Mcm2–7 heptamer to replication origins prior to Cdt1 release and ORC–Cdc6–Mcm2–7 complex formation, but how the second Mcm2–7 hexamer is recruited to promote double-hexamer formation is not well understood. Here, structural evidence for intermediates consisting of an ORC–Cdc6–Mcm2–7 complex and an ORC–Cdc6–Mcm2–7–Mcm2–7 complex are reported, which together provide new insights into DNA licensing. Detailed structural analysis of the loaded Mcm2–7 double-hexamer complex demonstrates that the two hexamers are interlocked and misaligned along the DNA axis and lack ATP hydrolysis activity that is essential for DNA helicase activity. Moreover, we show that the head-to-head juxtaposition of the Mcm2–7 double hexamer generates a new protein interaction surface that creates a multisubunit-binding site for an S-phase protein kinase that is known to activate DNA replication. The data suggest how the double hexamer is assembled and how helicase activity is regulated during DNA licensing, with implications for cell cycle control of DNA replication and genome stability.
Collapse
Affiliation(s)
- Jingchuan Sun
- Biosciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Alejandra Fernandez-Cid
- DNA Replication Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London W12 0NN, United Kingdom
| | - Alberto Riera
- DNA Replication Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London W12 0NN, United Kingdom
| | - Silvia Tognetti
- DNA Replication Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London W12 0NN, United Kingdom
| | - Zuanning Yuan
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794, USA
| | - Bruce Stillman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Christian Speck
- DNA Replication Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, London W12 0NN, United Kingdom;
| | - Huilin Li
- Biosciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA; Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794, USA
| |
Collapse
|
31
|
Bruck I, Kaplan DL. The Dbf4-Cdc7 kinase promotes Mcm2-7 ring opening to allow for single-stranded DNA extrusion and helicase assembly. J Biol Chem 2014; 290:1210-21. [PMID: 25471369 DOI: 10.1074/jbc.m114.608232] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The replication fork helicase in eukaryotes is composed of Cdc45, Mcm2-7, and GINS (CMG). The Dbf4-Cdc7 kinase phosphorylates Mcm2 in vitro, but the in vivo role for Dbf4-Cdc7 phosphorylation of Mcm2 is unclear. We find that budding yeast Dbf4-Cdc7 phosphorylates Mcm2 in vivo under normal conditions during S phase. Inhibiting Dbf4-Cdc7 phosphorylation of Mcm2 confers a dominant-negative phenotype with a severe growth defect. Inhibiting Dbf4-Cdc7 phosphorylation of Mcm2 under wild-type expression conditions also results in impaired DNA replication, substantially decreased single-stranded formation at an origin, and markedly disrupted interaction between GINS and Mcm2-7 during S phase. In vitro, Dbf4-Cdc7 kinase (DDK) phosphorylation of Mcm2 substantially weakens the interaction between Mcm2 and Mcm5, and Dbf4-Cdc7 phosphorylation of Mcm2 promotes Mcm2-7 ring opening. The extrusion of ssDNA from the central channel of Mcm2-7 triggers GINS attachment to Mcm2-7. Thus, Dbf4-Cdc7 phosphorylation of Mcm2 may open the Mcm2-7 ring at the Mcm2-Mcm5 interface, allowing for single-stranded DNA extrusion and subsequent GINS assembly with Mcm2-7.
Collapse
Affiliation(s)
- Irina Bruck
- From the Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306
| | - Daniel L Kaplan
- From the Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306
| |
Collapse
|
32
|
Stephenson R, Hosler MR, Gavande NS, Ghosh AK, Weake VM. Characterization of a Drosophila ortholog of the Cdc7 kinase: a role for Cdc7 in endoreplication independent of Chiffon. J Biol Chem 2014; 290:1332-47. [PMID: 25451925 DOI: 10.1074/jbc.m114.597948] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cdc7 is a serine-threonine kinase that phosphorylates components of the pre-replication complex during DNA replication initiation. Cdc7 is highly conserved, and Cdc7 orthologs have been characterized in organisms ranging from yeast to humans. Cdc7 is activated specifically during late G1/S phase by binding to its regulatory subunit, Dbf4. Drosophila melanogaster contains a Dbf4 ortholog, Chiffon, which is essential for chorion amplification in Drosophila egg chambers. However, no Drosophila ortholog of Cdc7 has yet been characterized. Here, we report the functional and biochemical characterization of a Drosophila ortholog of Cdc7. Co-expression of Drosophila Cdc7 and Chiffon is able to complement a growth defect in yeast containing a temperature-sensitive Cdc7 mutant. Cdc7 and Chiffon physically interact and can be co-purified from insect cells. Cdc7 phosphorylates the known Cdc7 substrates Mcm2 and histone H3 in vitro, and Cdc7 kinase activity is stimulated by Chiffon and inhibited by the Cdc7-specific inhibitor XL413. Drosophila egg chamber follicle cells deficient for Cdc7 have a defect in two types of DNA replication, endoreplication and chorion gene amplification. However, follicle cells deficient for Chiffon have a defect in chorion gene amplification but still undergo endocycling. Our results show that Cdc7 interacts with Chiffon to form a functional Dbf4-dependent kinase complex and that Cdc7 is necessary for DNA replication in Drosophila egg chamber follicle cells. Additionally, we show that Chiffon is a member of an expanding subset of DNA replication initiation factors that are not strictly required for endoreplication in Drosophila.
Collapse
Affiliation(s)
| | | | | | - Arun K Ghosh
- Chemistry and Medicinal Chemistry, and Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
| | - Vikki M Weake
- From the Departments of Biochemistry and Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
| |
Collapse
|
33
|
Sasi NK, Tiwari K, Soon FF, Bonte D, Wang T, Melcher K, Xu HE, Weinreich M. The potent Cdc7-Dbf4 (DDK) kinase inhibitor XL413 has limited activity in many cancer cell lines and discovery of potential new DDK inhibitor scaffolds. PLoS One 2014; 9:e113300. [PMID: 25412417 PMCID: PMC4239038 DOI: 10.1371/journal.pone.0113300] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 10/23/2014] [Indexed: 12/16/2022] Open
Abstract
Cdc7-Dbf4 kinase or DDK (Dbf4-dependent kinase) is required to initiate DNA replication by phosphorylating and activating the replicative Mcm2-7 DNA helicase. DDK is overexpressed in many tumor cells and is an emerging chemotherapeutic target since DDK inhibition causes apoptosis of diverse cancer cell types but not of normal cells. PHA-767491 and XL413 are among a number of potent DDK inhibitors with low nanomolar IC50 values against the purified kinase. Although XL413 is highly selective for DDK, its activity has not been extensively characterized on cell lines. We measured anti-proliferative and apoptotic effects of XL413 on a panel of tumor cell lines compared to PHA-767491, whose activity is well characterized. Both compounds were effective biochemical DDK inhibitors but surprisingly, their activities in cell lines were highly divergent. Unlike PHA-767491, XL413 had significant anti-proliferative activity against only one of the ten cell lines tested. Since XL413 did not effectively inhibit DDK in multiple cell lines, this compound likely has limited bioavailability. To identify potential leads for additional DDK inhibitors, we also tested the cross-reactivity of ∼400 known kinase inhibitors against DDK using a DDK thermal stability shift assay (TSA). We identified 11 compounds that significantly stabilized DDK. Several inhibited DDK with comparable potency to PHA-767491, including Chk1 and PKR kinase inhibitors, but had divergent chemical scaffolds from known DDK inhibitors. Taken together, these data show that several well-known kinase inhibitors cross-react with DDK and also highlight the opportunity to design additional specific, biologically active DDK inhibitors for use as chemotherapeutic agents.
Collapse
Affiliation(s)
- Nanda Kumar Sasi
- Laboratory of Genome Integrity and Tumorigenesis, Van Andel Research Institute (VARI), Grand Rapids, MI, United States of America
- Graduate Program in Genetics, Michigan State University, East Lansing, MI, United States of America
| | - Kanchan Tiwari
- Laboratory of Genome Integrity and Tumorigenesis, Van Andel Research Institute (VARI), Grand Rapids, MI, United States of America
| | - Fen-Fen Soon
- Laboratory of Structural Sciences, VARI, Grand Rapids, MI, United States of America
| | - Dorine Bonte
- Laboratory of Genome Integrity and Tumorigenesis, Van Andel Research Institute (VARI), Grand Rapids, MI, United States of America
| | - Tong Wang
- Translational Drug Development, Inc. (TD2), Scottsdale, AZ, United States of America
| | - Karsten Melcher
- Laboratory of Structural Biology and Biochemistry, VARI, Grand Rapids, MI, United States of America
| | - H. Eric Xu
- Laboratory of Structural Sciences, VARI, Grand Rapids, MI, United States of America
| | - Michael Weinreich
- Laboratory of Genome Integrity and Tumorigenesis, Van Andel Research Institute (VARI), Grand Rapids, MI, United States of America
- * E-mail:
| |
Collapse
|
34
|
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.
Collapse
Affiliation(s)
- Silvia Tognetti
- DNA Replication Group, Institute of Clinical Science, Imperial College, London, W12 0NN, UK
| | | | | |
Collapse
|