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Willemsen M, Barber JS, Nieuwenhove EV, Staels F, Gerbaux M, Neumann J, Prezzemolo T, Pasciuto E, Lagou V, Boeckx N, Filtjens J, De Visscher A, Matthys P, Schrijvers R, Tousseyn T, O'Driscoll M, Bucciol G, Schlenner S, Meyts I, Humblet-Baron S, Liston A. Homozygous DBF4 mutation as a cause of severe congenital neutropenia. J Allergy Clin Immunol 2023; 152:266-277. [PMID: 36841265 DOI: 10.1016/j.jaci.2023.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 01/23/2023] [Accepted: 02/16/2023] [Indexed: 02/26/2023]
Abstract
BACKGROUND Severe congenital neutropenia presents with recurrent infections early in life as a result of arrested granulopoiesis. Multiple genetic defects are known to block granulocyte differentiation; however, a genetic cause remains unknown in approximately 40% of cases. OBJECTIVE We aimed to characterize a patient with severe congenital neutropenia and syndromic features without a genetic diagnosis. METHODS Whole exome sequencing results were validated using flow cytometry, Western blotting, coimmunoprecipitation, quantitative PCR, cell cycle and proliferation analysis of lymphocytes and fibroblasts and granulocytic differentiation of primary CD34+ and HL-60 cells. RESULTS We identified a homozygous missense mutation in DBF4 in a patient with mild extra-uterine growth retardation, facial dysmorphism and severe congenital neutropenia. DBF4 is the regulatory subunit of the CDC7 kinase, together known as DBF4-dependent kinase (DDK), the complex essential for DNA replication initiation. The DBF4 variant demonstrated impaired ability to bind CDC7, resulting in decreased DDK-mediated phosphorylation, defective S-phase entry and progression and impaired differentiation of granulocytes associated with activation of the p53-p21 pathway. The introduction of wild-type DBF4 into patient CD34+ cells rescued the promyelocyte differentiation arrest. CONCLUSION Hypomorphic DBF4 mutation causes autosomal-recessive severe congenital neutropenia with syndromic features.
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Affiliation(s)
- Mathijs Willemsen
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
| | - John S Barber
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
| | - Erika Van Nieuwenhove
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium; Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium
| | - Frederik Staels
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; Department of Microbiology, Immunology, and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
| | - Margaux Gerbaux
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; Pediatric Department, Academic Children Hospital Queen Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Julika Neumann
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
| | - Teresa Prezzemolo
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
| | - Emanuela Pasciuto
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
| | - Vasiliki Lagou
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
| | - Nancy Boeckx
- Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Jessica Filtjens
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven, Leuve, Belgium
| | - Amber De Visscher
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven, Leuve, Belgium
| | - Patrick Matthys
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven, Leuve, Belgium
| | - Rik Schrijvers
- Department of Microbiology, Immunology, and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium
| | - Thomas Tousseyn
- Department of Pathology, University Hospitals Leuven, Leuven, Belgium
| | - Mark O'Driscoll
- Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Giorgia Bucciol
- Department of Microbiology, Immunology, and Transplantation, Laboratory for Inborn Errors of Immunity, KU Leuven, Leuven, Belgium; Department of Pediatrics, Division of Primary Immunodeficiencies, University Hospitals Leuven, Leuven
| | - Susan Schlenner
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium
| | - Isabelle Meyts
- Department of Microbiology, Immunology, and Transplantation, Laboratory for Inborn Errors of Immunity, KU Leuven, Leuven, Belgium; Department of Pediatrics, Division of Primary Immunodeficiencies, University Hospitals Leuven, Leuven.
| | - Stephanie Humblet-Baron
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium.
| | - Adrian Liston
- Department of Microbiology, Immunology, and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium; Immunology Programme, The Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom.
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2
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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.
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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.
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3
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Murai S, Katagiri Y, Yamashita S. Maturation-associatedDbf4expression is essential for mouse zygotic DNA replication. Dev Growth Differ 2014; 56:625-39. [DOI: 10.1111/dgd.12180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 08/24/2014] [Accepted: 08/27/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Shin Murai
- Department of Biochemistry; Toho University School of Medicine; 5-21-16 Omorinishi Otaku 143-8540 Tokyo Japan
| | - Yukiko Katagiri
- Department of Obstetrics and Gynecology Reproduction Center; Omori Medical Center; Toho University; 6-11-1, Omori-Nishi Ota-ku 143-8541 Tokyo Japan
| | - Shigeru Yamashita
- Department of Biochemistry; Toho University School of Medicine; 5-21-16 Omorinishi Otaku 143-8540 Tokyo Japan
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Yamada M, Watanabe K, Mistrik M, Vesela E, Protivankova I, Mailand N, Lee M, Masai H, Lukas J, Bartek J. ATR-Chk1-APC/CCdh1-dependent stabilization of Cdc7-ASK (Dbf4) kinase is required for DNA lesion bypass under replication stress. Genes Dev 2014; 27:2459-72. [PMID: 24240236 PMCID: PMC3841735 DOI: 10.1101/gad.224568.113] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cdc7 kinase regulates DNA replication. However, its role in DNA repair and recombination is poorly understood. Here we describe a pathway that stabilizes the human Cdc7-ASK (activator of S-phase kinase; also called Dbf4), its regulation, and its function in cellular responses to compromised DNA replication. Stalled DNA replication evoked stabilization of the Cdc7-ASK (Dbf4) complex in a manner dependent on ATR-Chk1-mediated checkpoint signaling and its interplay with the anaphase-promoting complex/cyclosome(Cdh1) (APC/C(Cdh1)) ubiquitin ligase. Mechanistically, Chk1 kinase inactivates APC/C(Cdh1) through degradation of Cdh1 upon replication block, thereby stabilizing APC/C(Cdh1) substrates, including Cdc7-ASK (Dbf4). Furthermore, motif C of ASK (Dbf4) interacts with the N-terminal region of RAD18 ubiquitin ligase, and this interaction is required for chromatin binding of RAD18. Impaired interaction of ASK (Dbf4) with RAD18 disables foci formation by RAD18 and hinders chromatin loading of translesion DNA polymerase η. These findings define a novel mechanism that orchestrates replication checkpoint signaling and ubiquitin-proteasome machinery with the DNA damage bypass pathway to guard against replication collapse under conditions of replication stress.
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Affiliation(s)
- Masayuki Yamada
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, CZ-775 15 Olomouc, Czech Republic
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5
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Matthews LA, Guarné A. Dbf4: the whole is greater than the sum of its parts. Cell Cycle 2013; 12:1180-8. [PMID: 23549174 PMCID: PMC3674083 DOI: 10.4161/cc.24416] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 03/22/2013] [Indexed: 12/29/2022] Open
Abstract
Together with cyclin-dependent kinases, the Dbf4-dependent kinase (DDK) is essential to activate the Mcm2-7 helicase and, hence, initiate DNA replication in eukaryotes. Beyond its role as the regulatory subunit of the DDK complex, the Dbf4 protein also regulates the activity of other cell cycle kinases to mediate the checkpoint response and prevent premature mitotic exit under stress. Two features that are unusual in DNA replication proteins characterize Dbf4. The first is its evolutionary divergence; the second is how its conserved motifs are combined to form distinct functional units. This structural plasticity appears to be at odds with the conserved functions of Dbf4. In this review, we summarize recent genetic, biochemical and structural work delineating the multiple interactions mediated by Dbf4 and its various functions during the cell cycle. We also discuss how the limited sequence conservation of Dbf4 may be an advantage to regulate the activities of multiple cell cycle kinases.
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Affiliation(s)
- Lindsay A Matthews
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
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Ito S, Ishii A, Kakusho N, Taniyama C, Yamazaki S, Fukatsu R, Sakaue-Sawano A, Miyawaki A, Masai H. Mechanism of cancer cell death induced by depletion of an essential replication regulator. PLoS One 2012; 7:e36372. [PMID: 22574151 PMCID: PMC3344859 DOI: 10.1371/journal.pone.0036372] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 03/30/2012] [Indexed: 01/17/2023] Open
Abstract
Background Depletion of replication factors often causes cell death in cancer cells. Depletion of Cdc7, a kinase essential for initiation of DNA replication, induces cancer cell death regardless of its p53 status, but the precise pathways of cell death induction have not been characterized. Methodology/Principal Findings We have used the recently-developed cell cycle indicator, Fucci, to precisely characterize the cell death process induced by Cdc7 depletion. We have also generated and utilized similar fluorescent cell cycle indicators using fusion with other cell cycle regulators to analyze modes of cell death in live cells in both p53-positive and -negative backgrounds. We show that distinct cell-cycle responses are induced in p53-positive and -negative cells by Cdc7 depletion. p53-negative cells predominantly arrest temporally in G2-phase, accumulating CyclinB1 and other mitotic regulators. Prolonged arrest at G2-phase and abrupt entry into aberrant M-phase in the presence of accumulated CyclinB1 are followed by cell death at the post-mitotic state. Abrogation of cytoplasmic CyclinB1 accumulation partially decreases cell death. The ATR-MK2 pathway is responsible for sequestration of CyclinB1 with 14-3-3σ protein. In contrast, p53-positive cancer cells do not accumulate CyclinB1, but appear to die mostly through entry into aberrant S-phase after Cdc7 depletion. The combination of Cdc7 inhibition with known anti-cancer agents significantly stimulates cell death effects in cancer cells in a genotype-dependent manner, providing a strategic basis for future combination therapies. Conclusions Our results show that the use of Fucci, and similar fluorescent cell cycle indicators, offers a convenient assay system with which to identify cell cycle events associated with cancer cell death. They also indicate genotype-specific cell death modes induced by deficient initiation of DNA replication in cancer cells and its potential exploitation for development of efficient cancer therapies.
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Affiliation(s)
- Sayuri Ito
- Genome Dynamics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan
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7
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Kitamura R, Fukatsu R, Kakusho N, Cho YS, Taniyama C, Yamazaki S, Toh GT, Yanagi K, Arai N, Chang HJ, Masai H. Molecular mechanism of activation of human Cdc7 kinase: bipartite interaction with Dbf4/activator of S phase kinase (ASK) activation subunit stimulates ATP binding and substrate recognition. J Biol Chem 2011; 286:23031-43. [PMID: 21536671 DOI: 10.1074/jbc.m111.243311] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cdc7 is a serine/threonine kinase conserved from yeasts to human and is known to play a key role in the regulation of initiation at each replication origin. Its catalytic function is activated via association with the activation subunit Dbf4/activator of S phase kinase (ASK). It is known that two conserved motifs of Dbf4/ASK are involved in binding to Cdc7, and both are required for maximum activation of Cdc7 kinase. Cdc7 kinases possess unique kinase insert sequences (kinase insert I-III) that are inserted at defined locations among the conserved kinase domains. However, precise mechanisms of Cdc7 kinase activation are largely unknown. We have identified two segments on Cdc7, DAM-1 (Dbf4/ASK interacting motif-1; amino acids 448-457 near the N terminus of kinase insert III) and DAM-2 (C-terminal 10-amino acid segment), that interact with motif-M and motif-C of ASK, respectively, and are essential for kinase activation by ASK. The C-terminal 143-amino acid polypeptide (432-574) containing DAM-1 and DAM-2 can interact with Dbf4/ASK. Characterization of the purified ASK-free Cdc7 and Cdc7-ASK complex shows that ATP binding of the Cdc7 catalytic subunit requires Dbf4/ASK. However, the "minimum" Cdc7, lacking the entire kinase insert II and half of kinase insert III, binds to ATP and shows autophosphorylation activity in the absence of ASK. However, ASK is still required for phosphorylation of exogenous substrates by the minimum Cdc7. These results indicate bipartite interaction between Cdc7 and Dbf4/ASK subunits facilitates ATP binding and substrate recognition by the Cdc7 kinase.
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Affiliation(s)
- Ryo Kitamura
- Genome Dynamics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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8
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Day TA, Palle K, Barkley LR, Kakusho N, Zou Y, Tateishi S, Verreault A, Masai H, Vaziri C. Phosphorylated Rad18 directs DNA polymerase η to sites of stalled replication. ACTA ACUST UNITED AC 2010; 191:953-66. [PMID: 21098111 PMCID: PMC2995173 DOI: 10.1083/jcb.201006043] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cdc7 phosphorylates Rad18 to integrate S phase progression with postreplication DNA repair, ensuring genome stability. The E3 ubiquitin ligase Rad18 guides DNA Polymerase eta (Polη) to sites of replication fork stalling and mono-ubiquitinates proliferating cell nuclear antigen (PCNA) to facilitate binding of Y family trans-lesion synthesis (TLS) DNA polymerases during TLS. However, it is unclear exactly how Rad18 is regulated in response to DNA damage and how Rad18 activity is coordinated with progression through different phases of the cell cycle. Here we identify Rad18 as a novel substrate of the essential protein kinase Cdc7 (also termed Dbf4/Drf1-dependent Cdc7 kinase [DDK]). A serine cluster in the Polη-binding motif of Rad18 is phosphorylated by DDK. Efficient association of Rad18 with Polη is dependent on DDK and is necessary for redistribution of Polη to sites of replication fork stalling. This is the first demonstration of Rad18 regulation by direct phosphorylation and provides a novel mechanism for integration of S phase progression with postreplication DNA repair to maintain genome stability.
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Affiliation(s)
- Tovah A Day
- Department of Genetics and Genomics and 2 Center for Human Genetics, Boston University School of Medicine, Boston, MA 02118, USA
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9
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Hughes S, Jenkins V, Dar MJ, Engelman A, Cherepanov P. Transcriptional co-activator LEDGF interacts with Cdc7-activator of S-phase kinase (ASK) and stimulates its enzymatic activity. J Biol Chem 2009; 285:541-54. [PMID: 19864417 DOI: 10.1074/jbc.m109.036491] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Lens epithelium-derived growth factor (LEDGF) is an important co-factor of human immunodeficiency virus DNA integration; however, its cellular functions are poorly characterized. We now report identification of the Cdc7-activator of S-phase kinase (ASK) heterodimer as a novel interactor of LEDGF. Both kinase subunits co-immunoprecipitated with endogenous LEDGF from human cell extracts. Truncation analyses identified the integrase-binding domain of LEDGF as essential and minimally sufficient for the interaction with Cdc7-ASK. Reciprocally, the interaction required autophosphorylation of the kinase and the presence of 50 C-terminal residues of ASK. The kinase phosphorylated LEDGF in vitro, with Ser-206 being the major target, and LEDGF phosphorylated at this residue could be detected during S phase of the cell cycle. LEDGF potently stimulated the enzymatic activity of Cdc7-ASK, increasing phosphorylation of MCM2 in vitro by more than 10-fold. This enzymatic stimulation as well as phosphorylation of LEDGF depended on the protein-protein interaction. Intriguingly, removing the C-terminal region of ASK, involved in the interaction with LEDGF, resulted in a hyperactive kinase. Our results indicate that the interaction with LEDGF relieves autoinhibition of Cdc7-ASK kinase, imposed by the C terminus of ASK.
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Affiliation(s)
- Siobhan Hughes
- Division of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, United Kingdom and
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Sawa M, Masai H. Drug design with Cdc7 kinase: a potential novel cancer therapy target. DRUG DESIGN DEVELOPMENT AND THERAPY 2009; 2:255-64. [PMID: 19920912 PMCID: PMC2761190 DOI: 10.2147/dddt.s4303] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Identification of novel molecular targets is critical in development of new and efficient cancer therapies. Kinases are one of the most common drug targets with a potential for cancer therapy. Cell cycle progression is regulated by a number of kinases, some of which are being developed to treat cancer. Cdc7 is a serine-threonine kinase originally discovered in budding yeast, which has been shown to be necessary to initiate the S phase. Inhibition of Cdc7 in cancer cells retards the progression of the S phase, accumulates DNA damage, and induces p53-independent cell death, but the same treatment in normal cells does not significantly affect of less than viability. Low-molecular-weight compounds that inhibit Cdc7 kinase with an IC50 10 nM have been identified, and shown to be effective in the inhibition of tumor growth in animal models. Thus Cdc7 kinase can be recognized as a novel molecular target for cancer therapy.
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11
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Martin L. The Replicon Initiation Burst Released by Reoxygenation of Hypoxic T24 Cells is Accompanied by Changes of MCM2 and Cdc7. BMB Rep 2007; 40:805-13. [DOI: 10.5483/bmbrep.2007.40.5.805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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12
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Gabrielse C, Miller CT, McConnell KH, DeWard A, Fox CA, Weinreich M. A Dbf4p BRCA1 C-terminal-like domain required for the response to replication fork arrest in budding yeast. Genetics 2006; 173:541-55. [PMID: 16547092 PMCID: PMC1526507 DOI: 10.1534/genetics.106.057521] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Dbf4p is an essential regulatory subunit of the Cdc7p kinase required for the initiation of DNA replication. Cdc7p and Dbf4p orthologs have also been shown to function in the response to DNA damage. A previous Dbf4p multiple sequence alignment identified a conserved approximately 40-residue N-terminal region with similarity to the BRCA1 C-terminal (BRCT) motif called "motif N." BRCT motifs encode approximately 100-amino-acid domains involved in the DNA damage response. We have identified an expanded and conserved approximately 100-residue N-terminal region of Dbf4p that includes motif N but is capable of encoding a single BRCT-like domain. Dbf4p orthologs diverge from the BRCT motif at the C terminus but may encode a similar secondary structure in this region. We have therefore called this the BRCT and DBF4 similarity (BRDF) motif. The principal role of this Dbf4p motif was in the response to replication fork (RF) arrest; however, it was not required for cell cycle progression, activation of Cdc7p kinase activity, or interaction with the origin recognition complex (ORC) postulated to recruit Cdc7p-Dbf4p to origins. Rad53p likely directly phosphorylated Dbf4p in response to RF arrest and Dbf4p was required for Rad53p abundance. Rad53p and Dbf4p therefore cooperated to coordinate a robust cellular response to RF arrest.
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Affiliation(s)
- Carrie Gabrielse
- Laboratory of Chromosome Replication, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
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Masai H, You Z, Arai KI. Control of DNA replication: regulation and activation of eukaryotic replicative helicase, MCM. IUBMB Life 2005; 57:323-35. [PMID: 16036617 DOI: 10.1080/15216540500092419] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
DNA replication is a key event of cell proliferation and the final target of signal transduction induced by growth factor stimulation. It is also strictly regulated during the ongoing cell cycle so that it occurs only once during S phase and that all the genetic materials are faithfully duplicated. DNA replication may be arrested or temporally inhibited due to a varieties of internal and external causes. Cells have developed intricate mechanisms to cope with the arrested replication forks to minimize the adversary effect on the stable maintenance of genetic materials. Helicases play a central role in DNA replication. In eukaryotes, MCM (minichromosome maintenance) protein complex plays essential roles as a replicative helicase. MCM4-6-7 complex possesses intrinsic DNA helicase activity which translocates on single-stranded DNA form 3' to 5'. Mammalian MCM4-6-7 helicase and ATPase activities are specifically stimulated by the presence of thymine-rich single-stranded DNA sequences onto which it is loaded. The activation appears to depend on the thymine content of this single-strand, and sequences derived from human replication origins can serve as potent activators of the MCM helicase. MCM is a prime target of Cdc7 kinase, known to be essential for activation of replication origins. We will discuss how the MCM may be activated at the replication origins by template DNA, phosphorylation, and interaction with other replicative proteins, and will present a model of how activation of MCM helicase by specific sequences may contribute to selection of replication initiation sites in higher eukaryotes.
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Affiliation(s)
- Hisao Masai
- Department of Cell Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
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