1
|
Cui Y, He M, Liu J, Wang S, Zhang J, Xie S, Hu Z, Guo S, Yan D. Maize LOST SUBSIDIARY CELL encoding a large subunit of ribonucleotide reductase is required for subsidiary cell development and plant growth. J Exp Bot 2023; 74:4449-4460. [PMID: 37103989 PMCID: PMC10433938 DOI: 10.1093/jxb/erad153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 04/26/2023] [Indexed: 06/19/2023]
Abstract
The four-celled stomatal complex consists of a pair of guard cells (GCs) and two subsidiary cells (SCs) in grasses, which supports a fast adjustment of stomatal aperture. The formation and development of SCs are thus important for stomatal functionality. Here, we report a maize lost subsidiary cells (lsc) mutant, with many stomata lacking one or two SCs. The loss of SCs is supposed to have resulted from impeded subsidiary mother cell (SMC) polarization and asymmetrical division. Besides the defect in SCs, the lsc mutant also displays a dwarf morphology and pale and striped newly-grown leaves. LSC encodes a large subunit of ribonucleotide reductase (RNR), an enzyme involved in deoxyribonucleotides (dNTPs) synthesis. Consistently, the concentration of dNTPs and expression of genes involved in DNA replication, cell cycle progression, and SC development were significantly reduced in the lsc mutant compared with the wild-type B73 inbred line. Conversely, overexpression of maize LSC increased dNTP synthesis and promoted plant growth in both maize and Arabidopsis. Our data indicate that LSC regulates dNTP production and is required for SMC polarization, SC differentiation, and growth of maize.
Collapse
Affiliation(s)
- Yongqi Cui
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| | - Meiqing He
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| | - Jie Liu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| | - Shuang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| | - Junli Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| | - Shiyi Xie
- Maize Engineering and Technology Research Center of Hunan Province, College of Agronomy, Hunan Agricultural University, Changsha 410128, China
| | - Zhubing Hu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| | - Siyi Guo
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| | - Dawei Yan
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China
| |
Collapse
|
2
|
Nangia-Makker P, Shekhar MP, Hogan V, Balan V, Raz A. MYH9 binds to dNTPs via deoxyribose moiety and plays an important role in DNA synthesis. Oncotarget 2022; 13:534-550. [PMID: 35309869 PMCID: PMC8923078 DOI: 10.18632/oncotarget.28219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/04/2022] [Indexed: 11/25/2022] Open
Abstract
The accepted notion of dNTP transport following cytoplasmic biosynthesis is 'facilitated diffusion'; however, whether this alone is sufficient for moving dNTPs for DNA synthesis remains an open question. The data presented here show that the MYH9 gene encoded heavy chain of non-muscle myosin IIA binds dNTPs potentially serving as a 'reservoir'. Pull-down assays showed that MYH9 present in the cytoplasmic, mitochondrial and nuclear compartments bind to DNA and this interaction is inhibited by dNTPs and 2-deoxyribose-5-phosphate (dRP) suggesting that MYH9-DNA binding is mediated via pentose sugar recognition. Direct dNTP-MYH9 binding was demonstrated by ELISA and a novel PCR-based method, which showed that all dNTPs bind to MYH9 with varying efficiencies. Cellular thermal shift assays showed that MYH9 thermal stability is enhanced by dNTPs. MYH9 siRNA transfection or treatment with myosin II selective inhibitors ML7 or blebbistatin decreased cell proliferation compared to controls. EdU labeling and cell cycle analysis by flow cytometry confirmed MYH9 siRNA and myosin II inhibitors decreased progression to S-phase with accumulation of cells in G0/G1 phase. Taken together, our data suggest a novel role for MYH9 in dNTP binding and DNA synthesis.
Collapse
Affiliation(s)
- Pratima Nangia-Makker
- Barbara Ann Karmanos Cancer Institute, School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Department of Oncology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Malathy P.V. Shekhar
- Barbara Ann Karmanos Cancer Institute, School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Department of Oncology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Department of Pathology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Victor Hogan
- Barbara Ann Karmanos Cancer Institute, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | | | - Avraham Raz
- Barbara Ann Karmanos Cancer Institute, School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Department of Oncology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Department of Pathology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| |
Collapse
|
3
|
Azhar A, Begum NA, Husain A. Nucleotide Pool Imbalance and Antibody Gene Diversification. Vaccines (Basel) 2021; 9:1050. [PMID: 34696158 DOI: 10.3390/vaccines9101050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/13/2021] [Accepted: 09/17/2021] [Indexed: 01/10/2023] Open
Abstract
The availability and adequate balance of deoxyribonucleoside triphosphate (dNTP) is an important determinant of both the fidelity and the processivity of DNA polymerases. Therefore, maintaining an optimal balance of the dNTP pool is critical for genomic stability in replicating and quiescent cells. Since DNA synthesis is required not only in genomic replication but also in DNA damage repair and recombination, the abnormalities in the dNTP pool affect a wide range of chromosomal activities. The generation of antibody diversity relies on antigen-independent V(D)J recombination, as well as antigen-dependent somatic hypermutation and class switch recombination. These processes involve diverse sets of DNA polymerases, which are affected by the dNTP pool imbalances. This review discusses the role of the optimal dNTP pool balance in the diversification of antibody encoding genes.
Collapse
|
4
|
Batalis S, Rogers LC, Hemphill WO, Mauney CH, Ornelles DA, Hollis T. SAMHD1 Phosphorylation at T592 Regulates Cellular Localization and S-phase Progression. Front Mol Biosci 2021; 8:724870. [PMID: 34513928 PMCID: PMC8426622 DOI: 10.3389/fmolb.2021.724870] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 08/16/2021] [Indexed: 12/02/2022] Open
Abstract
SAMHD1 activity is regulated by a network of mechanisms including phosphorylation, oxidation, oligomerization, and others. Significant questions remain about the effects of phosphorylation on SAMHD1 function and activity. We investigated the effects of a SAMHD1 T592E phosphorylation mimic on its cellular localization, catalytic activity, and cell cycle progression. We found that the SAMHD1 T592E is a catalytically active enzyme that is inhibited by protein oxidation. SAMHD1 T592E is retained in the nucleus at higher levels than the wild-type protein during growth factor-mediated signaling. This nuclear localization protects SAMHD1 from oxidation by cytoplasmic reactive oxygen species. The SAMHD1 T592E phosphomimetic further inhibits the cell cycle S/G2 transition. This has significant implications for SAMHD1 function in regulating innate immunity, antiviral response and DNA replication.
Collapse
Affiliation(s)
- Stephanie Batalis
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - LeAnn C Rogers
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Wayne O Hemphill
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Christopher H Mauney
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - David A Ornelles
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Thomas Hollis
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| |
Collapse
|
5
|
Iannuzzi S, von Kleist M. Mathematical Modelling of the Molecular Mechanisms of Interaction of Tenofovir with Emtricitabine against HIV. Viruses 2021; 13:1354. [PMID: 34372560 DOI: 10.3390/v13071354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/06/2021] [Accepted: 07/10/2021] [Indexed: 12/24/2022] Open
Abstract
The combination of the two nucleoside reverse transcriptase inhibitors (NRTI) tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) is used in most highly active antiretroviral therapies for treatment of HIV-1 infection, as well as in pre-exposure prophylaxis against HIV acquisition. Administered as prodrugs, these drugs are taken up by HIV-infected target cells, undergo intracellular phosphorylation and compete with natural deoxynucleoside triphosphates (dNTP) for incorporation into nascent viral DNA during reverse transcription. Once incorporated, they halt reverse transcription. In vitro studies have proposed that TDF and FTC act synergistically within an HIV-infected cell. However, it is unclear whether, and which, direct drug–drug interactions mediate the apparent synergy. The goal of this work was to refine a mechanistic model for the molecular mechanism of action (MMOA) of nucleoside analogues in order to analyse whether putative direct interactions may account for the in vitro observed synergistic effects. Our analysis suggests that depletion of dNTP pools can explain apparent synergy between TDF and FTC in HIV-infected cells at clinically relevant concentrations. Dead-end complex (DEC) formation does not seem to significantly contribute to the synergistic effect. However, in the presence of non-nucleoside reverse transcriptase inhibitors (NNRTIs), its role might be more relevant, as previously reported in experimental in vitro studies.
Collapse
|
6
|
Landoni JC, Wang L, Suomalainen A. Whole-Cell and Mitochondrial dNTP Pool Quantification from Cells and Tissues. Methods Mol Biol 2021; 2276:143-151. [PMID: 34060038 DOI: 10.1007/978-1-0716-1266-8_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Deoxynucleoside 5'-triphosphates (dNTPs) are the molecular building blocks for DNA synthesis, and their balanced concentration in the cell is fundamental for health. dNTP imbalance can lead to genomic instability and other metabolic disturbances, resulting in devastating mitochondrial diseases.The accurate and efficient measurement of dNTPs from different biological samples and cellular compartments is vital to understand the mechanisms behind these diseases and develop and scrutinize their possible treatments. This chapter describes an update on the most recent development of the traditional radiolabeled polymerase extension method and its adaptation for the measurement of whole-cell and mitochondrial dNTP pools from cultured cells and tissue samples. The solid-phase reaction setting enables an increase in efficiency, accuracy, and measurement scale.
Collapse
Affiliation(s)
- Juan C Landoni
- Research Programs Unit, Stem Cells and Metabolism, University of Helsinki, Helsinki, Finland
| | - Liya Wang
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Anu Suomalainen
- University Hospital, Department of Neurology, Helsinki, Finland.
- Neuroscience Center, University of Helsinki, Helsinki, Finland.
| |
Collapse
|
7
|
Coggins SA, Mahboubi B, Schinazi RF, Kim B. Mechanistic cross-talk between DNA/RNA polymerase enzyme kinetics and nucleotide substrate availability in cells: Implications for polymerase inhibitor discovery. J Biol Chem 2020; 295:13432-13443. [PMID: 32737197 PMCID: PMC7521635 DOI: 10.1074/jbc.rev120.013746] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/31/2020] [Indexed: 01/01/2023] Open
Abstract
Enzyme kinetic analysis reveals a dynamic relationship between enzymes and their substrates. Overall enzyme activity can be controlled by both protein expression and various cellular regulatory systems. Interestingly, the availability and concentrations of intracellular substrates can constantly change, depending on conditions and cell types. Here, we review previously reported enzyme kinetic parameters of cellular and viral DNA and RNA polymerases with respect to cellular levels of their nucleotide substrates. This broad perspective exposes a remarkable co-evolution scenario of DNA polymerase enzyme kinetics with dNTP levels that can vastly change, depending on cell proliferation profiles. Similarly, RNA polymerases display much higher Km values than DNA polymerases, possibly due to millimolar range rNTP concentrations found in cells (compared with micromolar range dNTP levels). Polymerases are commonly targeted by nucleotide analog inhibitors for the treatments of various human diseases, such as cancers and viral pathogens. Because these inhibitors compete against natural cellular nucleotides, the efficacy of each inhibitor can be affected by varying cellular nucleotide levels in their target cells. Overall, both kinetic discrepancy between DNA and RNA polymerases and cellular concentration discrepancy between dNTPs and rNTPs present pharmacological and mechanistic considerations for therapeutic discovery.
Collapse
Affiliation(s)
- Si'Ana A Coggins
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Bijan Mahboubi
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Raymond F Schinazi
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Baek Kim
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA; Center for Drug Discovery, Children's Healthcare of Atlanta, Atlanta, Georgia, USA.
| |
Collapse
|
8
|
Husain A, Xu J, Fujii H, Nakata M, Kobayashi M, Wang JY, Rehwinkel J, Honjo T, Begum NA. SAMHD1-mediated dNTP degradation is required for efficient DNA repair during antibody class switch recombination. EMBO J 2020; 39:e102931. [PMID: 32511795 DOI: 10.15252/embj.2019102931] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 05/04/2020] [Accepted: 05/08/2020] [Indexed: 12/12/2022] Open
Abstract
Sterile alpha motif and histidine-aspartic acid domain-containing protein 1 (SAMHD1), a dNTP triphosphohydrolase, regulates the levels of cellular dNTPs through their hydrolysis. SAMHD1 protects cells from invading viruses that depend on dNTPs to replicate and is frequently mutated in cancers and Aicardi-Goutières syndrome, a hereditary autoimmune encephalopathy. We discovered that SAMHD1 localizes at the immunoglobulin (Ig) switch region, and serves as a novel DNA repair regulator of Ig class switch recombination (CSR). Depletion of SAMHD1 impaired not only CSR but also IgH/c-Myc translocation. Consistently, we could inhibit these two processes by elevating the cellular nucleotide pool. A high frequency of nucleotide insertion at the break-point junctions is a notable feature in SAMHD1 deficiency during activation-induced cytidine deaminase-mediated genomic instability. Interestingly, CSR induced by staggered but not blunt, double-stranded DNA breaks was impaired by SAMHD1 depletion, which was accompanied by enhanced nucleotide insertions at recombination junctions. We propose that SAMHD1-mediated dNTP balance regulates dNTP-sensitive DNA end-processing enzyme and promotes CSR and aberrant genomic rearrangements by suppressing the insertional DNA repair pathway.
Collapse
Affiliation(s)
- Afzal Husain
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Jianliang Xu
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hodaka Fujii
- Department of Biochemistry and Genome Biology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan.,Combined Program on Microbiology and Immunology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Mikiyo Nakata
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Maki Kobayashi
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Ji-Yang Wang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Jan Rehwinkel
- Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Tasuku Honjo
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Nasim A Begum
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| |
Collapse
|
9
|
Davenne T, Klintman J, Sharma S, Rigby RE, Blest HTW, Cursi C, Bridgeman A, Dadonaite B, De Keersmaecker K, Hillmen P, Chabes A, Schuh A, Rehwinkel J. SAMHD1 Limits the Efficacy of Forodesine in Leukemia by Protecting Cells against the Cytotoxicity of dGTP. Cell Rep 2020; 31:107640. [PMID: 32402273 PMCID: PMC7225753 DOI: 10.1016/j.celrep.2020.107640] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 03/12/2020] [Accepted: 04/22/2020] [Indexed: 12/12/2022] Open
Abstract
The anti-leukemia agent forodesine causes cytotoxic overload of intracellular deoxyguanosine triphosphate (dGTP) but is efficacious only in a subset of patients. We report that SAMHD1, a phosphohydrolase degrading deoxyribonucleoside triphosphate (dNTP), protects cells against the effects of dNTP imbalances. SAMHD1-deficient cells induce intrinsic apoptosis upon provision of deoxyribonucleosides, particularly deoxyguanosine (dG). Moreover, dG and forodesine act synergistically to kill cells lacking SAMHD1. Using mass cytometry, we find that these compounds kill SAMHD1-deficient malignant cells in patients with chronic lymphocytic leukemia (CLL). Normal cells and CLL cells from patients without SAMHD1 mutation are unaffected. We therefore propose to use forodesine as a precision medicine for leukemia, stratifying patients by SAMHD1 genotype or expression.
Collapse
Affiliation(s)
- Tamara Davenne
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK; Laboratory for Disease Mechanisms in Cancer, Department of Oncology, KU Leuven and Leuven Cancer Institute (LKI), Herestraat 49, 3000 Leuven, Belgium
| | - Jenny Klintman
- Molecular Diagnostic Centre, Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 901 87 Umeå, Sweden
| | - Rachel E Rigby
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Henry T W Blest
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Chiara Cursi
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Anne Bridgeman
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Bernadeta Dadonaite
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Kim De Keersmaecker
- Laboratory for Disease Mechanisms in Cancer, Department of Oncology, KU Leuven and Leuven Cancer Institute (LKI), Herestraat 49, 3000 Leuven, Belgium
| | - Peter Hillmen
- St James' Institute of Oncology, St James' University Hospital, Leeds LS9 7TF, UK
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 901 87 Umeå, Sweden
| | - Anna Schuh
- Molecular Diagnostic Centre, Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK; Department of Oncology, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK; Department of Haematology, Oxford University Hospitals NHS Trust, Oxford OX3 7JL, UK
| | - Jan Rehwinkel
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK.
| |
Collapse
|
10
|
Abstract
Regulation of dNTP pools in an intracellular environment is not only vital for DNA replication but also plays a major role in maintaining genomic stability. Ribonucleotide reductase (RNR) catalyzes the rate-limiting step in dNTP synthesis and altered regulation of RNR leads to imbalanced dNTP pools. Increased dNTP levels are mutagenic and have the potential to interfere with pathways that are involved in DNA replication, repair and DNA damage control. However, the mechanisms through which altered dNTP pools affect these pathways are poorly understood. Nonetheless, altered dNTP pools have been identified in a number of cellular contexts, including cancer. In order to interpret and analyze the effects of altered dNTP pools, we need quantitative information about dNTP pools in different genetic and environmental contexts in vivo. Here we describe a high-throughput fluorescence-based assay that uses a qPCR-based approach to quantify dNTP levels for use with Saccharomyces cerevisiae extracts.
Collapse
Affiliation(s)
- Radha Subramaniam
- Genetics, Genomics and Bioinformatics Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Natalie A Lamb
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Yoonchan Hwang
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Lauren Johengen
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Jennifer A Surtees
- Genetics, Genomics and Bioinformatics Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA. .,Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA.
| |
Collapse
|
11
|
Wang Z, Bhattacharya A, White T, Buffone C, McCabe A, Nguyen LA, Shepard CN, Pardo S, Kim B, Weintraub ST, Demeler B, Diaz-Griffero F, Ivanov DN. Functionality of Redox-Active Cysteines Is Required for Restriction of Retroviral Replication by SAMHD1. Cell Rep 2020; 24:815-823. [PMID: 30044979 PMCID: PMC6067006 DOI: 10.1016/j.celrep.2018.06.090] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 05/01/2018] [Accepted: 06/21/2018] [Indexed: 01/04/2023] Open
Abstract
SAMHD1 is a dNTP triphosphohydrolase (dNTPase) that impairs retroviral replication in a subset of noncycling immune cells. Here we show that SAMHD1 is a redox-sensitive enzyme and identify three redox-active cysteines within the protein: C341, C350, and C522. The three cysteines reside near one another and the allosteric nucleotide binding site. Mutations C341S and C522S abolish the ability of SAMHD1 to restrict HIV replication, whereas the C350S mutant remains restriction competent. The C522S mutation makes the protein resistant to inhibition by hydrogen peroxide but has no effect on the tetramerization-dependent dNTPase activity of SAMHD1 in vitro or on the ability of SAMHD1 to deplete cellular dNTPs. Our results reveal that enzymatic activation of SAMHD1 via nucleotide-dependent tetramerization is not sufficient for the establishment of the antiviral state and that retroviral restriction depends on the ability of the protein to undergo redox transformations.
Collapse
Affiliation(s)
- Zhonghua Wang
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Akash Bhattacharya
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Tommy White
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Cindy Buffone
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Aine McCabe
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Laura A Nguyen
- Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA
| | - Caitlin N Shepard
- Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA
| | - Sammy Pardo
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA; School of Pharmacy, Kyunghee University, Seoul, South Korea
| | - Susan T Weintraub
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Borries Demeler
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Dmitri N Ivanov
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA.
| |
Collapse
|
12
|
Kapoor I, Emam EAF, Shaw A, Varshney U. Nucleoside Diphosphate Kinase Escalates A-to-C Mutations in MutT-Deficient Strains of Escherichia coli. J Bacteriol 2019; 202:e00567-19. [PMID: 31591275 DOI: 10.1128/JB.00567-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 10/01/2019] [Indexed: 11/20/2022] Open
Abstract
The chemical integrity of the nucleotide pool and its homeostasis are crucial for genome stability. Nucleoside diphosphate kinase (NDK) is a crucial enzyme that carries out reversible conversions from nucleoside diphosphate (NDP) to nucleoside triphosphate (NTP) and deoxynucleoside diphosphate (dNDP) to deoxynucleoside triphosphate (dNTP). Guanosine nucleotides (GDP, GTP, dGDP, and dGTP) are highly susceptible to oxidative damage to 8-oxo-GDP (8-O-GDP), 8-O-dGTP, 8-O-GTP, and 8-O-dGTP. MutT proteins in cells hydrolyze 8-O-GTP to 8-O-GMP or 8-O-dGTP to 8-O-dGMP to avoid its incorporation in nucleic acids. In Escherichia coli, 8-O-dGTP is also known to be hydrolyzed by RibA (GTP cyclohydrolase II). In this study, we show that E. coli NDK catalyzes the conversion of 8-O-dGDP to 8-O-dGTP or vice versa. However, the rate of NDK-mediated phosphorylation of 8-O-dGDP to 8-O-dGTP is about thrice as efficient as the rate of dephosphorylation of 8-O-dGTP to 8-O-dGDP, suggesting an additive role of NDK in net production of 8-O-dGTP in cells. Consistent with this observation, the depletion of NDK (Δndk) in E. coli ΔmutT or ΔmutT ΔribA strains results in a decrease of A-to-C mutations. These observations suggest that NDK contributes to the physiological load of MutT in E. coli IMPORTANCE Nucleoside diphosphate kinase (NDK), a ubiquitous enzyme, is known for its critical role in homeostasis of cellular nucleotide pools. However, NDK has now emerged as a molecule with pleiotropic effects in DNA repair, protein phosphorylation, gene expression, tumor metastasis, development, and pathogen virulence and persistence inside the host. In this study, we reveal an unexpected role of NDK in genome instability because of its activity in converting 8-O-dGDP to 8-O-dGTP. This observation has important consequences in escalating A-to-C mutations in Escherichia coli The severity of NDK in enhancing these mutations may be higher in the organisms challenged with high oxidative stress, which promotes 8-O-dGDP/8-O-dGTP production.
Collapse
|
13
|
Abstract
The incorporation of ribonucleotides (rNMPs) into DNA during genome replication has gained substantial attention in recent years and has been shown to be a significant source of genomic instability. Studies in yeast and mammals have shown that the two genomes, the nuclear DNA (nDNA) and the mitochondrial DNA (mtDNA), differ with regard to their rNMP content. This is largely due to differences in rNMP repair - whereas rNMPs are efficiently removed from the nuclear genome, mitochondria lack robust mechanisms for removal of single rNMPs incorporated during DNA replication. In this minireview, we describe the processes that determine the frequency of rNMPs in the mitochondrial genome and summarise recent findings regarding the effect of incorporated rNMPs on mtDNA stability and function.
Collapse
Affiliation(s)
- Paulina H Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden.,Laboratory for Molecular Infection Medicine Sweden, Umeå University, Sweden
| |
Collapse
|
14
|
Corcoles-Saez I, Ferat JL, Costanzo M, Boone CM, Cha RS. Functional link between mitochondria and Rnr3, the minor catalytic subunit of yeast ribonucleotide reductase. Microb Cell 2019; 6:286-294. [PMID: 31172013 PMCID: PMC6545439 DOI: 10.15698/mic2019.06.680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Ribonucleotide reductase (RNR) is an essential holoenzyme required for de novo synthesis of dNTPs. The Saccharomyces cerevisiae genome encodes for two catalytic subunits, Rnr1 and Rnr3. While Rnr1 is required for DNA replication and DNA damage repair, the function(s) of Rnr3 is unknown. Here, we show that carbon source, an essential nutrient, impacts Rnr1 and Rnr3 abundance: Non-fermentable carbon sources or limiting concentrations of glucose down regulate Rnr1 and induce Rnr3 expression. Oppositely, abundant glucose induces Rnr1 expression and down regulates Rnr3. The carbon source dependent regulation of Rnr3 is mediated by Mec1, the budding yeast ATM/ATR checkpoint response kinase. Unexpectedly, this regulation is independent of all currently known components of the Mec1 DNA damage response network, including Rad53, Dun1, and Tel1, implicating a novel Mec1 signalling axis. rnr3Δ leads to growth defects under respiratory conditions and rescues temperature sensitivity conferred by the absence of Tom6, a component of the mitochondrial TOM (translocase of outer membrane) complex responsible for mitochondrial protein import. Together, these results unveil involvement of Rnr3 in mitochondrial functions and Mec1 in mediating the carbon source dependent regulation of Rnr3.
Collapse
Affiliation(s)
- Isaac Corcoles-Saez
- School of Medical Sciences, North West Cancer Research Institute, Bangor University, Deniol Road, Bangor, LL57 2UW, United Kingdom
| | - Jean-Luc Ferat
- Institute of Integrative Biology of the Cell (I2BC), Avenue de la Terrasse, Paris, France
| | - Michael Costanzo
- University of Toronto, Donnelly Centre, 160 College Street, Toronto, Ontario, M5S 3E1, Canada
| | - Charles M Boone
- University of Toronto, Donnelly Centre, 160 College Street, Toronto, Ontario, M5S 3E1, Canada
| | - Rita S Cha
- School of Medical Sciences, North West Cancer Research Institute, Bangor University, Deniol Road, Bangor, LL57 2UW, United Kingdom
| |
Collapse
|
15
|
Bu P, Nagar S, Bhagwat M, Kaur P, Shah A, Zeng J, Vancurova I, Vancura A. DNA damage response activates respiration and thereby enlarges dNTP pools to promote cell survival in budding yeast. J Biol Chem 2019; 294:9771-9786. [PMID: 31073026 DOI: 10.1074/jbc.ra118.007266] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 04/30/2019] [Indexed: 12/13/2022] Open
Abstract
The DNA damage response (DDR) is an evolutionarily conserved process essential for cell survival. Previously, we found that decreased histone expression induces mitochondrial respiration, raising the question whether the DDR also stimulates respiration. Here, using oxygen consumption and ATP assays, RT-qPCR and ChIP-qPCR methods, and dNTP analyses, we show that DDR activation in the budding yeast Saccharomyces cerevisiae, either by genetic manipulation or by growth in the presence of genotoxic chemicals, induces respiration. We observed that this induction is conferred by reduced transcription of histone genes and globally decreased DNA nucleosome occupancy. This globally altered chromatin structure increased the expression of genes encoding enzymes of tricarboxylic acid cycle, electron transport chain, oxidative phosphorylation, elevated oxygen consumption, and ATP synthesis. The elevated ATP levels resulting from DDR-stimulated respiration drove enlargement of dNTP pools; cells with a defect in respiration failed to increase dNTP synthesis and exhibited reduced fitness in the presence of DNA damage. Together, our results reveal an unexpected connection between respiration and the DDR and indicate that the benefit of increased dNTP synthesis in the face of DNA damage outweighs possible cellular damage due to increased oxygen metabolism.
Collapse
Affiliation(s)
- Pengli Bu
- From the Departments of Biological Sciences and
| | | | | | | | - Ankita Shah
- Pharmaceutical Sciences, St. John's University, Queens, New York 11439
| | - Joey Zeng
- From the Departments of Biological Sciences and
| | | | | |
Collapse
|
16
|
Zou Y, Li W, Zhou J, Zhang J, Huang Y, Wang Z. ERK Inhibitor Enhances Everolimus Efficacy through the Attenuation of dNTP Pools in Renal Cell Carcinoma. Mol Ther Nucleic Acids 2019; 14:550-561. [PMID: 30771617 PMCID: PMC6374702 DOI: 10.1016/j.omtn.2019.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 01/01/2019] [Accepted: 01/01/2019] [Indexed: 01/10/2023]
Abstract
The clinical efficiency of everolimus, an mammalian target of rapamycin (mTOR) inhibitor, is palliative as sequential or second-line therapy for renal cell carcinoma (RCC). However, the limited response of everolimus in RCC remains uncertain. In the present study, everolimus-resistant RCC models were established to understand the mechanisms and to seek combination approaches. Consequently, the activation of ERK was found to contribute toward everolimus-acquired resistance and poor prognosis in patients with RCC. In addition, the efficacy and mechanism of combination treatment underlying RCC using everolimus and ERK inhibitors was investigated. The ERK inhibitor in combination with everolimus synergistically inhibited the proliferation of RCC cells by arresting the cell cycle in the G1 phase. The combination treatment markedly attenuated the deoxyribonucleoside triphosphate (dNTP) pools by downregulating the mRNA expression of RRM1 and RRM2 through E2F1. The overexpression of E2F1 or supplementation of dNTP rescued the anti-proliferation activity of the everolimus-SCH772984 combination. The antitumor efficacy of combination therapy was reiterated in RCC xenograft models. Thus, the current findings provided evidence that the everolimus-ERK inhibitor combination is a preclinical therapeutic strategy for RCC.
Collapse
Affiliation(s)
- Yun Zou
- Department of Urology and Andrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200011, China
| | - Wenzhi Li
- Department of Urology and Andrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200011, China
| | - Juan Zhou
- Department of Urology and Andrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200011, China
| | - Jin Zhang
- Department of Urology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Yiran Huang
- Department of Urology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China.
| | - Zhong Wang
- Department of Urology and Andrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200011, China.
| |
Collapse
|
17
|
Kuskovsky R, Buj R, Xu P, Hofbauer S, Doan MT, Jiang H, Bostwick A, Mesaros C, Aird KM, Snyder NW. Simultaneous isotope dilution quantification and metabolic tracing of deoxyribonucleotides by liquid chromatography high resolution mass spectrometry. Anal Biochem 2018; 568:65-72. [PMID: 30605633 DOI: 10.1016/j.ab.2018.12.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 12/26/2018] [Accepted: 12/29/2018] [Indexed: 12/21/2022]
Abstract
Quantification of cellular deoxyribonucleoside mono- (dNMP), di- (dNDP), triphosphates (dNTPs) and related nucleoside metabolites are difficult due to their physiochemical properties and widely varying abundance. Involvement of dNTP metabolism in cellular processes including senescence and pathophysiological processes including cancer and viral infection make dNTP metabolism an important bioanalytical target. We modified a previously developed ion pairing reversed phase chromatography-mass spectrometry method for the simultaneous quantification and 13C isotope tracing of dNTP metabolites. dNMPs, dNDPs, and dNTPs were chromatographically resolved to avoid mis-annotation of in-source fragmentation. We used commercially available 13C15N-stable isotope labeled analogs as internal standards and show that this isotope dilution approach improves analytical figures of merit. At sufficiently high mass resolution achievable on an Orbitrap mass analyzer, stable isotope resolved metabolomics allows simultaneous isotope dilution quantification and 13C isotope tracing from major substrates including 13C-glucose. As a proof of principle, we quantified dNMP, dNDP and dNTP pools from multiple cell lines. We also identified isotopologue enrichment from glucose corresponding to ribose from the pentose-phosphate pathway in dNTP metabolites.
Collapse
Affiliation(s)
- Rostislav Kuskovsky
- AJ Drexel Autism Institute, Drexel University, 3020 Market St Suite 560, Philadelphia, PA, 19104, USA
| | - Raquel Buj
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Peining Xu
- AJ Drexel Autism Institute, Drexel University, 3020 Market St Suite 560, Philadelphia, PA, 19104, USA
| | - Samuel Hofbauer
- Centers for Cancer Pharmacology and Excellence in Environmental Toxicology, Department of Pharmacology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Mary T Doan
- AJ Drexel Autism Institute, Drexel University, 3020 Market St Suite 560, Philadelphia, PA, 19104, USA
| | - Helen Jiang
- AJ Drexel Autism Institute, Drexel University, 3020 Market St Suite 560, Philadelphia, PA, 19104, USA
| | - Anna Bostwick
- AJ Drexel Autism Institute, Drexel University, 3020 Market St Suite 560, Philadelphia, PA, 19104, USA
| | - Clementina Mesaros
- Centers for Cancer Pharmacology and Excellence in Environmental Toxicology, Department of Pharmacology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Katherine M Aird
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Nathaniel W Snyder
- AJ Drexel Autism Institute, Drexel University, 3020 Market St Suite 560, Philadelphia, PA, 19104, USA.
| |
Collapse
|
18
|
Landoni JC, Wang L, Suomalainen A. Quantitative solid-phase assay to measure deoxynucleoside triphosphate pools. Biol Methods Protoc 2018; 3:bpy011. [PMID: 32161804 PMCID: PMC6994031 DOI: 10.1093/biomethods/bpy011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/09/2018] [Accepted: 08/15/2018] [Indexed: 12/25/2022] Open
Abstract
deoxynucleoside triphosphate (dNTPs) are the reduced nucleotides used as the building blocks and energy source for deoxyribonucleic acid (DNA) replication and maintenance in all living systems. They are present in highly regulated amounts and ratios in the cell, and their balance has been implicated in the most important cell processes, from determining the fidelity of DNA replication to affecting cell fate. Furthermore, many cancer drugs target biosynthetic enzymes in dNTP metabolism, and mutations in genes directly or indirectly affecting these pathways that are the cause of devastating diseases. The accurate and systematic measurement of these pools is key to understanding the mechanisms behind these diseases and their treatment. We present a new method for measuring dNTP pools from biological samples, utilizing the current state-of-the-art polymerase method, modified to a solid-phase setting and optimized for larger scale measurements.
Collapse
Affiliation(s)
- Juan Cruz Landoni
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Liya Wang
- Department of Anatomy, Physiology, and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Anu Suomalainen
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland.,Department of Neurosciences, Helsinki University Hospital, Helsinki, Finland.,Neuroscience Center, HiLife, University of Helsinki, Helsinki, Finland
| |
Collapse
|
19
|
Daddacha W, Koyen AE, Bastien AJ, Head PE, Dhere VR, Nabeta GN, Connolly EC, Werner E, Madden MZ, Daly MB, Minten EV, Whelan DR, Schlafstein AJ, Zhang H, Anand R, Doronio C, Withers AE, Shepard C, Sundaram RK, Deng X, Dynan WS, Wang Y, Bindra RS, Cejka P, Rothenberg E, Doetsch PW, Kim B, Yu DS. SAMHD1 Promotes DNA End Resection to Facilitate DNA Repair by Homologous Recombination. Cell Rep 2017; 20:1921-35. [PMID: 28834754 DOI: 10.1016/j.celrep.2017.08.008] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/05/2017] [Accepted: 07/28/2017] [Indexed: 12/28/2022] Open
Abstract
DNA double-strand break (DSB) repair by homologous recombination (HR) is initiated by CtIP/MRN-mediated DNA end resection to maintain genome integrity. SAMHD1 is a dNTP triphosphohydrolase, which restricts HIV-1 infection, and mutations are associated with Aicardi-Goutières syndrome and cancer. We show that SAMHD1 has a dNTPase-independent function in promoting DNA end resection to facilitate DSB repair by HR. SAMHD1 deficiency or Vpx-mediated degradation causes hypersensitivity to DSB-inducing agents, and SAMHD1 is recruited to DSBs. SAMHD1 complexes with CtIP via a conserved C-terminal domain and recruits CtIP to DSBs to facilitate end resection and HR. Significantly, a cancer-associated mutant with impaired CtIP interaction, but not dNTPase-inactive SAMHD1, fails to rescue the end resection impairment of SAMHD1 depletion. Our findings define a dNTPase-independent function for SAMHD1 in HR-mediated DSB repair by facilitating CtIP accrual to promote DNA end resection, providing insight into how SAMHD1 promotes genome integrity.
Collapse
|
20
|
Zhu M, Dai X, Guo W, Ge Z, Yang M, Wang H, Wang YP. Manipulating the Bacterial Cell Cycle and Cell Size by Titrating the Expression of Ribonucleotide Reductase. mBio 2017; 8:e01741-17. [PMID: 29138305 DOI: 10.1128/mBio.01741-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Understanding how bacteria coordinate growth with cell cycle events to maintain cell size homeostasis remains a grand challenge in biology. The period of chromosome replication (C period) is a key stage in the bacterial cell cycle. However, the mechanism of in vivo regulation of the C period remains unclear. In this study, we found that titration of the expression of ribonucleotide reductase (RNR), which changes the intracellular deoxynucleoside triphosphate (dNTP) pools, enables significant perturbations of the C period, leading to a substantial change in cell size and DNA content. Our work demonstrates that the intracellular dNTP pool is indeed an important parameter that controls the progression of chromosome replication. Specially, RNR overexpression leads to a shortened C period compared with that of a wild-type strain growing under different nutrient conditions, indicating that the dNTP substrate levels are subsaturated under physiological conditions. In addition, perturbing the C period does not significantly change the D period, indicating that these two processes are largely independent from each other. Overall, titration of ribonucleotide reductase expression can serve as a standard model system for studying the coordination between chromosome replication, cell division, and cell size.IMPORTANCE Bacteria must coordinate growth with cell cycle progression to maintain cell size hemostasis. Cell cycle and cell size regulation is a fundamental concern in biology. The period required for chromosome replication (the C period) is a key stage in the bacterial cell cycle. However, how the C period is controlled in vivo remains largely an open question in this field of bacterial cell cycle regulation. Through introducing a genetic circuit into Escherichia coli for titrating the expression of ribonucleotide reductase, we achieve substantial perturbation of the C period and cell size. Our work demonstrates that the intracellular dNTP pool is an important parameter that controls the progression of chromosome replication. Moreover, our work indicates that bacterial cells manage to maintain subsaturated dNTP levels under different nutrient conditions, leading to a submaximal speed of DNA replication fork movement.
Collapse
|
21
|
Wanrooij PH, Engqvist MKM, Forslund JME, Navarrete C, Nilsson AK, Sedman J, Wanrooij S, Clausen AR, Chabes A. Ribonucleotides incorporated by the yeast mitochondrial DNA polymerase are not repaired. Proc Natl Acad Sci U S A 2017; 114:12466-71. [PMID: 29109257 DOI: 10.1073/pnas.1713085114] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Incorporation of ribonucleotides into DNA during genome replication is a significant source of genomic instability. The frequency of ribonucleotides in DNA is determined by deoxyribonucleoside triphosphate/ribonucleoside triphosphate (dNTP/rNTP) ratios, by the ability of DNA polymerases to discriminate against ribonucleotides, and by the capacity of repair mechanisms to remove incorporated ribonucleotides. To simultaneously compare how the nuclear and mitochondrial genomes incorporate and remove ribonucleotides, we challenged these processes by changing the balance of cellular dNTPs. Using a collection of yeast strains with altered dNTP pools, we discovered an inverse relationship between the concentration of individual dNTPs and the amount of the corresponding ribonucleotides incorporated in mitochondrial DNA, while in nuclear DNA the ribonucleotide pattern was only altered in the absence of ribonucleotide excision repair. Our analysis uncovers major differences in ribonucleotide repair between the two genomes and provides concrete evidence that yeast mitochondria lack mechanisms for removal of ribonucleotides incorporated by the mtDNA polymerase. Furthermore, as cytosolic dNTP pool imbalances were transmitted equally well into the nucleus and the mitochondria, our results support a view of the cytosolic and mitochondrial dNTP pools in frequent exchange.
Collapse
|
22
|
Pai CC, Kishkevich A, Deegan RS, Keszthelyi A, Folkes L, Kearsey SE, De León N, Soriano I, de Bruin RAM, Carr AM, Humphrey TC. Set2 Methyltransferase Facilitates DNA Replication and Promotes Genotoxic Stress Responses through MBF-Dependent Transcription. Cell Rep 2017; 20:2693-2705. [PMID: 28903048 PMCID: PMC5608972 DOI: 10.1016/j.celrep.2017.08.058] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 06/10/2017] [Accepted: 08/17/2017] [Indexed: 11/24/2022] Open
Abstract
Chromatin modification through histone H3 lysine 36 methylation by the SETD2 tumor suppressor plays a key role in maintaining genome stability. Here, we describe a role for Set2-dependent H3K36 methylation in facilitating DNA replication and the transcriptional responses to both replication stress and DNA damage through promoting MluI cell-cycle box (MCB) binding factor (MBF)-complex-dependent transcription in fission yeast. Set2 loss leads to reduced MBF-dependent ribonucleotide reductase (RNR) expression, reduced deoxyribonucleoside triphosphate (dNTP) synthesis, altered replication origin firing, and a checkpoint-dependent S-phase delay. Accordingly, prolonged S phase in the absence of Set2 is suppressed by increasing dNTP synthesis. Furthermore, H3K36 is di- and tri-methylated at these MBF gene promoters, and Set2 loss leads to reduced MBF binding and transcription in response to genotoxic stress. Together, these findings provide new insights into how H3K36 methylation facilitates DNA replication and promotes genotoxic stress responses in fission yeast.
Collapse
Affiliation(s)
- Chen-Chun Pai
- CRUK-MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK.
| | - Anastasiya Kishkevich
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6B, UK
| | - Rachel S Deegan
- CRUK-MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Andrea Keszthelyi
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, Sussex BN1 9RQ, UK
| | - Lisa Folkes
- CRUK-MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Stephen E Kearsey
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | - Nagore De León
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | - Ignacio Soriano
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | | | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, Sussex BN1 9RQ, UK
| | - Timothy C Humphrey
- CRUK-MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK.
| |
Collapse
|
23
|
Abstract
A crucial factor in maintaining genome stability is establishing deoxynucleoside triphosphate (dNTP) levels within a range that is optimal for chromosomal replication. Since DNA replication is relevant to a wide range of other chromosomal activities, these may all be directly or indirectly affected when dNTP concentrations deviate from a physiologically normal range. The importance of understanding these consequences is relevant to genetic disorders that disturb dNTP levels, and strategies that inhibit dNTP synthesis in cancer chemotherapy and for treatment of other disorders. We review here how abnormal dNTP levels affect DNA replication and discuss the consequences for genome stability.
Collapse
Affiliation(s)
- Chen-Chun Pai
- CRUK-MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK.
| | - Stephen E Kearsey
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
| |
Collapse
|
24
|
Bloch N, Gläsker S, Sitaram P, Hofmann H, Shepard CN, Schultz ML, Kim B, Landau NR. A Highly Active Isoform of Lentivirus Restriction Factor SAMHD1 in Mouse. J Biol Chem 2016; 292:1068-1080. [PMID: 27920203 DOI: 10.1074/jbc.m116.743740] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 12/01/2016] [Indexed: 11/06/2022] Open
Abstract
The triphosphohydrolase SAMHD1 (sterile α motif and histidine-aspartate domain-containing protein 1) restricts HIV-1 replication in nondividing myeloid cells by depleting the dNTP pool, preventing reverse transcription. SAMHD1 is also reported to have ribonuclease activity that degrades the virus genomic RNA. Human SAMHD1 is regulated by phosphorylation of its carboxyl terminus at Thr-592, which abrogates its antiviral function yet has only a small effect on its phosphohydrolase activity. In the mouse, SAMHD1 is expressed as two isoforms (ISF1 and ISF2) that differ at the carboxyl terminus due to alternative splicing of the last coding exon. In this study we characterized the biochemical and antiviral properties of the two mouse isoforms of SAMHD1. Both are antiviral in nondividing cells. Mass spectrometry analysis showed that SAMHD1 is phosphorylated at several amino acid residues, one of which (Thr-634) is homologous to Thr-592. Phosphomimetic mutation at Thr-634 of ISF1 ablates its antiviral activity yet has little effect on phosphohydrolase activity in vitro dGTP caused ISF1 to tetramerize, activating its catalytic activity. In contrast, ISF2, which lacks the phosphorylation site, was significantly more active, tetramerized, and was active without added dGTP. Neither isoform nor human SAMHD1 had detectable RNase activity in vitro or affected HIV-1 genomic RNA stability in newly infected cells. These data support a model in which SAMHD1 catalytic activity is regulated through tetramer stabilization by the carboxyl-terminal tail, phosphorylation destabilizing the complexes and inactivating the enzyme. ISF2 may serve to reduce the dNTP pool to very low levels as a means of restricting virus replication.
Collapse
Affiliation(s)
- Nicolin Bloch
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Sabine Gläsker
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Poojitha Sitaram
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Henning Hofmann
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Caitlin N Shepard
- the Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322, and
| | - Megan L Schultz
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016
| | - Baek Kim
- the Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322, and.,the School of Pharmacy, Kyunghee University, Seoul 02447, South Korea
| | - Nathaniel R Landau
- From the Department of Microbiology, New York School of Medicine, New York, New York 10016,
| |
Collapse
|
25
|
Sakai Y, Doi N, Miyazaki Y, Adachi A, Nomaguchi M. Phylogenetic Insights into the Functional Relationship between Primate Lentiviral Reverse Transcriptase and Accessory Proteins Vpx/Vpr. Front Microbiol 2016; 7:1655. [PMID: 27803699 PMCID: PMC5067338 DOI: 10.3389/fmicb.2016.01655] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 10/04/2016] [Indexed: 11/13/2022] Open
Abstract
The efficiency of reverse transcription to synthesize viral DNA in infected cells greatly influences replication kinetics of retroviruses. However, viral replication in non-dividing cells such as resting T cells and terminally differentiated macrophages is potently and kinetically restricted by a host antiviral factor designated SAMHD1 (sterile alpha motif and HD-domain containing protein 1). SAMHD1 reduces cellular deoxynucleoside triphosphate (dNTP) pools and affects viral reverse transcription step. Human immunodeficiency virus type 2 (HIV-2) and some simian immunodeficiency viruses (SIVs) have Vpx or Vpr to efficiently degrade SAMHD1. Interestingly, the reverse transcriptase (RT) derived from HIV-1 that encodes no anti-SAMHD1 proteins has been previously demonstrated to uniquely exhibit a high enzymatic activity. It is thus not irrational to assume that some viruses may have acquired or lost the specific RT property to better adapt themselves to the low dNTP environments confronted in non-dividing cells. This adaptation process may probably be correlated with the SAMHD1-antagonizing ability by viruses. In this report, we asked whether such adaptive events can be inferable from Vpx/Vpr and RT phylogenetic trees overlaid with SAMHD1-degrading capacity of Vpx/Vpr and with kinetic characteristics of RT. Resultant two trees showed substantially similar clustering patterns, and therefore suggested that the properties of RT and Vpx/Vpr can be linked. In other words, HIV/SIVs may possess their own RT proteins to adequately react to various dNTP circumstances in target cells.
Collapse
Affiliation(s)
- Yosuke Sakai
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| | - Naoya Doi
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| | - Yasuyuki Miyazaki
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science Tokyo, Japan
| | - Akio Adachi
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| | - Masako Nomaguchi
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| |
Collapse
|
26
|
Liu PD, Xue YB, Chen ZJ, Liu GD, Tian J. Characterization of purple acid phosphatases involved in extracellular dNTP utilization in Stylosanthes. J Exp Bot 2016; 67:4141-54. [PMID: 27194738 PMCID: PMC5301924 DOI: 10.1093/jxb/erw190] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Stylo (Stylosanthes spp.) is a pasture legume predominant in tropical and subtropical areas, where low phosphorus (P) availability is a major constraint for plant growth. Therefore, stylo might exhibit superior utilization of the P pool on acid soils, particularly organic P. However, little is known about mechanisms of inorganic phosphate (Pi) acquisition employed by stylo. In this study, the utilization of extracellular deoxy-ribonucleotide triphosphate (dNTP) and the underlying physiological and molecular mechanisms were examined for two stylo genotypes with contrasting P efficiency. Results showed that the P-efficient genotype, TPRC2001-1, was superior to the P-inefficient genotype, Fine-stem, when using dNTP as the sole P source. This was reflected by a higher dry weight and total P content for TPRC2001-1 than for Fine-stem, which was correlated with higher root-associated acid phosphatase (APase) activities in TPRC2001-1 under low P conditions. Subsequently, three PAP members were cloned from TPRC2001-1: SgPAP7, SgPAP10, and SgPAP26 Expression levels of these three SgPAPs were up-regulated by Pi starvation in stylo roots. Furthermore, there was a higher abundance of transcripts of SgPAP7 and SgPAP10 in TPRC2001-1 than in Fine-stem. Subcellular localization analysis demonstrated that these three SgPAPs were localized on the plasma membrane. Overexpression of these three SgPAPs could result in significantly increased root-associated APase activities, and thus extracellular dNTP utilization in bean hairy roots. Taken together, the results herein suggest that SgPAP7, SgPAP10, and SgPAP26 may differentially contribute to root-associated APase activities, and thus control extracellular dNTP utilization in stylo.
Collapse
Affiliation(s)
- Pan-Dao Liu
- College of Agriculture, Hainan University, Institute of Tropical Crop Genetic Resources, Chinese Academy of Tropical Agriculture Sciences, Hainan 570228, P. R. China State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangdong 510642, P. R. China
| | - Ying-Bin Xue
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangdong 510642, P. R. China
| | - Zhi-Jian Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangdong 510642, P. R. China
| | - Guo-Dao Liu
- College of Agriculture, Hainan University, Institute of Tropical Crop Genetic Resources, Chinese Academy of Tropical Agriculture Sciences, Hainan 570228, P. R. China
| | - Jiang Tian
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Root Biology Center, South China Agricultural University, Guangdong 510642, P. R. China
| |
Collapse
|
27
|
Bonifati S, Daly MB, St Gelais C, Kim SH, Hollenbaugh JA, Shepard C, Kennedy EM, Kim DH, Schinazi RF, Kim B, Wu L. SAMHD1 controls cell cycle status, apoptosis and HIV-1 infection in monocytic THP-1 cells. Virology 2016; 495:92-100. [PMID: 27183329 DOI: 10.1016/j.virol.2016.05.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 05/03/2016] [Indexed: 01/09/2023]
Abstract
SAMHD1 limits HIV-1 infection in non-dividing myeloid cells by decreasing intracellular dNTP pools. HIV-1 restriction by SAMHD1 in these cells likely prevents activation of antiviral immune responses and modulates viral pathogenesis, thus highlighting a critical role of SAMHD1 in HIV-1 physiopathology. Here, we explored the function of SAMHD1 in regulating cell proliferation, cell cycle progression and apoptosis in monocytic THP-1 cells. Using the CRISPR/Cas9 technology, we generated THP-1 cells with stable SAMHD1 knockout. We found that silencing of SAMHD1 in cycling cells stimulates cell proliferation, redistributes cell cycle population in the G1/G0 phase and reduces apoptosis. These alterations correlated with increased dNTP levels and more efficient HIV-1 infection in dividing SAMHD1 knockout cells relative to control. Our results suggest that SAMHD1, through its dNTPase activity, affects cell proliferation, cell cycle distribution and apoptosis, and emphasize a key role of SAMHD1 in the interplay between cell cycle regulation and HIV-1 infection.
Collapse
Affiliation(s)
- Serena Bonifati
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Michele B Daly
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Corine St Gelais
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Sun Hee Kim
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Joseph A Hollenbaugh
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Caitlin Shepard
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Edward M Kennedy
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, USA
| | - Dong-Hyun Kim
- Department of Pharmacy, School of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Raymond F Schinazi
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA; Department of Pharmacy, School of Pharmacy, Kyung-Hee University, Seoul, South Korea.
| | - Li Wu
- Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA.
| |
Collapse
|
28
|
Abstract
Cellular supply of deoxynucleoside triphosphates (dNTPs) is crucial for DNA replication and repair. In this study, we investigated the role of CMP/UMP kinase (CMPK), an enzyme catalyzes CDP formation, in DNA repair. Knockdown of CMPK delays DNA repair during recovery from UV damage in serum-deprived cells but not in the cells without serum deprivation. Exogenous supply of cytidine or deoxycytidine facilitates DNA repair dependent on CMPK in serum-deprived cells, suggesting that the synthesis of dCDP or CDP determines the rate of repair. However, CMPK knockdown does not affect the steady state level of dCTP in serum-deprived cells. We then found the localization of CMPK at DNA damage sites and its complex formation with Tip60 and ribonucleotide reductase. Our analysis demonstrated that the N-terminal 32-amino-acid of CMPK is required for its recruitment to DNA damage sites in a Tip60-dependent manner. Re-expression of wild-type but not N-terminus deleted CMPK restores the efficiency of DNA repair in CMPK knockdown cells. We proposed that site-specific dCDP formation via CMPK provides a means to facilitate DNA repair in serum-deprived cells.
Collapse
Affiliation(s)
- Ning Tsao
- a Graduate Institute of Biochemistry and Molecular Biology; College of Medicine ; National Taiwan University ; Taipei , Taiwan (R.O.C.)
| | | | | | | | | |
Collapse
|
29
|
Abstract
Inactivation of Mec1, the budding yeast ATR, results in a permanent S phase arrest followed by chromosome breakage and cell death during G2/M. The S phase arrest is proposed to stem from a defect in Mec1-mediated degradation of Sml1, a conserved inhibitor of ribonucleotide reductase (RNR), causing a severe depletion in cellular dNTP pools. Here, the casual link between the S phase arrest, Sml1, and dNTP-levels is examined using a temperature sensitive mec1 mutant. In addition to S phase arrest, thermal inactivation of Mec1 leads to constitutively high levels of Sml1 and an S phase arrest. Expression of a novel suppressor, GIS2, a conserved mRNA binding zinc finger protein, rescues the arrest without down-regulating Sml1 levels. The dNTP pool in mec1 is reduced by ∼17% and GIS2 expression restores it, but only partially, to ∼93% of a control. We infer that the permanent S phase block following Mec1 inactivation can be uncoupled from its role in Sml1 down-regulation. Furthermore, unexpectedly modest effects of mec1 and GIS2 on dNTP levels suggest that the S phase arrest is unlikely to result from a severe depletion of dNTP pool as assumed, but a heightened sensitivity to small changes in its availability. Summary: This study, using a temperature sensitive mec1 mutant, reveals that inactivation of Mec1 leads to S phase arrest, and that genome duplication in the absence of Mec1/ATR is exquisitely sensitive to small changes in dNTP levels.
Collapse
Affiliation(s)
- Caroline Earp
- Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK
| | - Samuel Rowbotham
- Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK
| | - Gábor Merényi
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE 901 87, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE 901 87, Sweden
| | - Rita S Cha
- Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK North West Cancer Research Institute, School of Medical Sciences, Bangor University, Bangor LL57 2UW, UK
| |
Collapse
|
30
|
Lenzi GM, Domaoal RA, Kim DH, Schinazi RF, Kim B. Mechanistic and Kinetic Differences between Reverse Transcriptases of Vpx Coding and Non-coding Lentiviruses. J Biol Chem 2015; 290:30078-86. [PMID: 26483545 PMCID: PMC4705996 DOI: 10.1074/jbc.m115.691576] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Indexed: 11/06/2022] Open
Abstract
Among lentiviruses, HIV Type 2 (HIV-2) and many simian immunodeficiency virus (SIV) strains replicate rapidly in non-dividing macrophages, whereas HIV Type 1 (HIV-1) replication in this cell type is kinetically delayed. The efficient replication capability of HIV-2/SIV in non-dividing cells is induced by a unique, virally encoded accessory protein, Vpx, which proteasomally degrades the host antiviral restriction factor, SAM domain- and HD domain-containing protein 1 (SAMHD1). SAMHD1 is a dNTPase and kinetically suppresses the reverse transcription step of HIV-1 in macrophages by hydrolyzing and depleting cellular dNTPs. In contrast, Vpx, which is encoded by HIV-2/SIV, kinetically accelerates reverse transcription by counteracting SAMHD1 and then elevating cellular dNTP concentration in non-dividing cells. Here, we conducted the pre-steady-state kinetic analysis of reverse transcriptases (RTs) from two Vpx non-coding and two Vpx coding lentiviruses. At all three sites of the template tested, the two RTs of the Vpx non-coding viruses (HIV-1) displayed higher kpol values than the RTs of the Vpx coding HIV-2/SIV, whereas there was no significant difference in the Kd values of these two groups of RTs. When we employed viral RNA templates that induce RT pausing by their secondary structures, the HIV-1 RTs showed more efficient DNA synthesis through pause sites than the HIV-2/SIV RTs, particularly at low dNTP concentrations found in macrophages. This kinetic study suggests that RTs of the Vpx non-coding HIV-1 may have evolved to execute a faster kpol step, which includes the conformational changes and incorporation chemistry, to counteract the limited dNTP concentration found in non-dividing cells and still promote efficient viral reverse transcription.
Collapse
Affiliation(s)
- Gina M Lenzi
- From the Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Robert A Domaoal
- From the Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Dong-Hyun Kim
- the College of Pharmacy, Kyung-Hee University, Seoul 02447, South Korea
| | - Raymond F Schinazi
- From the Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, the Veterans Affairs Medical Center, Decatur, Georgia 30033
| | - Baek Kim
- From the Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, the College of Pharmacy, Kyung-Hee University, Seoul 02447, South Korea,
| |
Collapse
|
31
|
Wang JL, Lu FZ, Shen XY, Wu Y, Zhao LT. SAMHD1 is down regulated in lung cancer by methylation and inhibits tumor cell proliferation. Biochem Biophys Res Commun 2014; 455:229-33. [PMID: 25449277 DOI: 10.1016/j.bbrc.2014.10.153] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 10/30/2014] [Indexed: 12/21/2022]
Abstract
The function of dNTP hydrolase SAMHD1 as a viral restriction factor to inhibit the replication of several viruses in human immune cells was well established. However, its regulation and function in lung cancer have been elusive. Here, we report that SAMHD1 is down regulated both on protein and mRNA levels in lung adenocarcinoma compared to adjacent normal tissue. We also found that SAMHD1 promoter is highly methylated in lung adenocarcinoma, which may inhibit its gene expression. Furthermore, over expression of the SAMHD1 reduces dNTP level and inhibits the proliferation of lung tumor cells. These results reveal the regulation and function of SAMHD1 in lung cancer, which is important for the proliferation of lung tumor cells.
Collapse
Affiliation(s)
- Jia-lei Wang
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China
| | - Fan-zhen Lu
- Department of Thoracic Surgery, The Huadong Hospital, Fudan University, Shanghai 200040, China
| | - Xiao-Yong Shen
- Department of Thoracic Surgery, The Huadong Hospital, Fudan University, Shanghai 200040, China.
| | - Yun Wu
- Department of Thoracic Surgery, The Huadong Hospital, Fudan University, Shanghai 200040, China.
| | - Li-ting Zhao
- Department of Thoracic Surgery, The Huadong Hospital, Fudan University, Shanghai 200040, China
| |
Collapse
|
32
|
Kim HJ, Moon JH, Kim HM, Yun MR, Jeon BH, Lee B, Kang ES, Lee HC, Cha BS. The hypolipidemic effect of cilostazol can be mediated by regulation of hepatic low-density lipoprotein receptor-related protein 1 (LRP1) expression. Metabolism 2014; 63:112-9. [PMID: 24139096 DOI: 10.1016/j.metabol.2013.09.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 08/26/2013] [Accepted: 09/11/2013] [Indexed: 01/26/2023]
Abstract
OBJECTIVES Cilostazol, a selective phosphodiesterase 3 (PDE3) inhibitor, is a vasodilator and an anti-thrombotic agent. The mechanism whereby cilostazol reduces plasma triglyceride is not completely understood. Here we investigated the effect of cilostazol on a remnant lipoprotein receptor, low-density lipoprotein receptor-related protein 1 (LRP1), which has been reported to play an essential role in clearance of circulating triglyceride in the liver. MATERIALS/METHODS Total cellular expression, and functional and transcriptional regulation of LRP1 were analyzed in human hepatocarcinoma cell lines incubated with cilostazol. Also, C57BL/6 mice were subjected to high-fat diet (60% kcal) and cilostazol (30 mg/kg) treatment for 10 weeks. RESULTS Cilostazol increased both mRNA and protein expression of LRP1 in HepG2 and Hep3B cells. In addition, enhanced transcriptional activity of the LRP1 promoter containing a peroxisome proliferator response element (PPRE) was observed after cilostazol exposure. Cilostazol treatment enhanced the uptake of lipidated apoE3, and this effect was abolished when LRP1 was silenced by siRNA knockdown. High-fat diet induced hyperglycemia with high level of plasma triglycerides, and reduced hepatic LRP1 expression in mice. Treatment with cilostazol for the same period of time, however, successfully prevented this down-regulation of LRP1 expression and reduced plasma triglycerides. CONCLUSION Taken together, our results demonstrated that cilostazol enhances LRP1 expression in liver by activating PPARγ through the PPRE in the LRP1 promoter. Increased hepatic LRP1 may be essential for the reduction of circulating triglycerides brought about by cilostazol.
Collapse
Affiliation(s)
- Hyung Jun Kim
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Hu G, Zou G, Liu X, Liang H, Li Z, Hu S. The carp-goldfish nucleocytoplasmic hybrid has mitochondria from the carp as the nuclear donor species. Gene 2014; 536:265-71. [PMID: 24365595 DOI: 10.1016/j.gene.2013.12.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 11/21/2022]
Abstract
It is widely accepted that mitochondria and its DNA (mtDNA) exhibit strict maternal inheritance, with sperm contributing no or non-detectable mitochondria to the next generation. In fish, nuclear transfer (NT) through the combination of a donor nucleus and an enucleated oocyte can produce fertile nucleocytoplasmic hybrids (NCHs) even between different genera and subfamilies. One of the best studied fish NCHs is CyCa produced by transplanting the nuclei plus cytoplasm from the common carp (Cyprinus carpio var. wuyuanensis) into the oocytes of the wild goldfish (Carassius auratus), which has been propagated by self-mating for three generations. These NCH fish thus provide a unique model to study the origin of mitochondria. Here we report the complete mtDNA sequence of the CyCa hybrid and its parental species carp and goldfish as nuclear donor and cytoplasm host, respectively. Interestingly, the mtDNA of NCH fish CyCa is 99.69% identical to the nuclear donor species carp, and 89.25% identical to the oocyte host species goldfish. Furthermore, an amino acid sequence comparison of 13 mitochondrial proteins reveals that CyCa is 99.68% identical to the carp and 87.68% identical to the goldfish. On an mtDNA-based phylogenetic tree, CyCa is clustered with the carp but separated from the goldfish. A real-time PCR analysis revealed the presence of carp mtDNA but the absence of goldfish mtDNA. These results demonstrate--for the first time to our knowledge--that the mtDNA of a NCH such as CyCa fish may originate from its nuclear donor rather than its oocyte host.
Collapse
|
34
|
Liu S, Zhang W, Shi H, Meng Y, Qiu Z. Three novel homozygous mutations in the GNPTG gene that cause mucolipidosis type III gamma. Gene 2013; 535:294-8. [PMID: 24316125 DOI: 10.1016/j.gene.2013.11.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 10/30/2013] [Accepted: 11/04/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND Mucolipidosis type III gamma (MLIII gamma) is an autosomal recessive disease caused by a mutation in the GNPTG gene, which encodes the γ subunit of the N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase). This protein plays a key role in the transport of lysosomal hydrolases to the lysosome. METHODS Three Chinese children with typical skeletal abnormalities of MLIII were identified, who were from unrelated consanguineous families. After obtaining informed consent, genomic DNA was isolated from the patients and their parents. Direct sequencing of the GNPTG and GNPTAB genes was performed using standard PCR reactions. RESULTS The three probands showed clinical features typical of MLIII gamma, such as joint stiffness and vertebral scoliosis without coarsened facial features. Mutation analysis of the GNPTG gene showed that three novel mutations were identified, two in exon seven [c.425G>A (p.Cys142Val)] and [c.515dupC (p.His172Profs27X)], and one in exon eight [c.609+1G>C]. Their parents were determined to be heterozygous carriers when compared to the reference sequence in GenBank on NCBI. CONCLUSIONS Mutation of the GNPTG gene is the cause of MLIII gamma in our patients. Our findings expand the mutation spectrum of the GNPTG gene and extend the knowledge of the phenotype-genotype correlation of the disease.
Collapse
Affiliation(s)
- Shuang Liu
- Department of Pediatrics, PUMC Hospital, CAMS&PUMC, Beijing 100730, PR China
| | - Weimin Zhang
- Clinical Research Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, PR China
| | - Huiping Shi
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, PR China
| | - Yan Meng
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, PR China
| | - Zhengqing Qiu
- Department of Pediatrics, PUMC Hospital, CAMS&PUMC, Beijing 100730, PR China.
| |
Collapse
|
35
|
Qinghai Z, Yanying W, Yunfang C, Xukui Z, Xiaoqiao Z. Effect of interleukin-17A and interleukin-17F gene polymorphisms on the risk of gastric cancer in a Chinese population. Gene 2013; 537:328-32. [PMID: 24315816 DOI: 10.1016/j.gene.2013.11.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/28/2013] [Accepted: 11/02/2013] [Indexed: 12/11/2022]
Abstract
We selected six tagged single-nucleotide polymorphisms (SNPs) in the IL-17A and IL-17F genes, and evaluated the relationship between the six common SNPs and H. pylori infection, tobacco smoking and subsites of gastric cancer in gastric cancer patients. Genotyping of IL-17A (rs2275913, rs3748067 and rs3819025) and IL-17A (rs763780, rs9382084, and rs12203582) was performed in a 384-well plate format on the MassARRAY® platform. An unconditional multiple logistical regression model was performed to determine the association between IL-17A and IL-17F genetic variations and gastric cancer risk. Unconditional logistic regression analysis showed that subjects carrying the rs2275913AA and rs3748067 TT genotypes were 1.70 and 3.45 times more likely to develop gastric cancer. Furthermore, rs2275913 and rs3748067 genetic variants significantly interacted with H. pylori infection on the risk of gastric cancer. The interaction between rs3748067 and rs9382084 genetic variants and tobacco smoking trend was significant. In addition, rs2275913, rs3748067 and rs9382084 genetic variants were only associated with non-cardia gastric cancer. The findings suggest that the rs2275913, rs3748067 and rs9382084 polymorphisms increase the risk of gastric cancer, and they interact with H. pylori infection, tobacco smoking and subsites of gastric cancer. These findings could be helpful in identifying individuals at increased risk for developing gastric cancer.
Collapse
Affiliation(s)
- Zhu Qinghai
- Department of General Surgery, Zhumadian Centre Hospital, Zhumadian, China
| | - Wang Yanying
- Department of General Surgery, Zhumadian Centre Hospital, Zhumadian, China.
| | - Chen Yunfang
- Department of Oncology, Zhumadian Centre Hospital, Zhumadian, China
| | - Zhang Xukui
- Department of General Surgery, PLA Jinan General Hospital, Jinan, China
| | - Zhang Xiaoqiao
- Department of General Surgery, PLA Jinan General Hospital, Jinan, China
| |
Collapse
|
36
|
Harish, Gupta AK, Phulwaria M, Rai MK, Shekhawat NS. Conservation genetics of endangered medicinal plant Commiphora wightii in Indian Thar Desert. Gene 2014; 535:266-72. [PMID: 24295888 DOI: 10.1016/j.gene.2013.11.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 11/08/2013] [Accepted: 11/12/2013] [Indexed: 11/20/2022]
Abstract
To ascertain the conservation priorities and strategies for Commiphora wightii, an endangered medicinal plant of Indian Thar Desert, genetic diversity was estimated within and among different populations. The total of 155 amplification products were scored using ten each of RAPD and ISSR primers, exhibiting an overall 86.72% polymorphism across 45 individuals representing eight populations. The cumulative data of two markers were used to compute pair-wise distances. The Neighbor-Joining tree revealed high genetic differentiation among populations except Kiradu population. Nei's gene diversity (h) ranged between 0.082 and 0.193 with total diversity at species level is 0.294. Shannon's information index (I) ranged between 0.118 and 0.275 with an overall diversity of 0.439. Analysis of molecular variance showed more diversity among population level (56.65%) than at within population level (43.35%). The low gene flow value (Nm=0.349) and high coefficient of genetic differentiation (GST=0.589) and high fixation index (FST=0.566) demonstrated elevated genetic differentiation among the population and can be predicted that these populations are not in Hardy-Weinberg proportions. Principal Co-ordinate Analysis confirms that Akal population has become phylogenetically more distinct and less diverse than the rest of the samples. Mantel's test revealed no correlation between genetic and geographical distances of populations (R(2)=0.122). Overall highest diversity was observed in the population of Machiya Safari Park and Kiradu, while lowest in Akal population, later may constitute an evolutionary significant unit, having merit for special management.
Collapse
|
37
|
Cai Y, Geacintov NE, Broyde S. Ribonucleotides as nucleotide excision repair substrates. DNA Repair (Amst) 2014; 13:55-60. [PMID: 24290807 DOI: 10.1016/j.dnarep.2013.10.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/28/2013] [Accepted: 10/29/2013] [Indexed: 11/22/2022]
Abstract
The incorporation of ribonucleotides in DNA has attracted considerable notice in recent years, since the pool of ribonucleotides can exceed that of the deoxyribonucleotides by at least 10-20-fold, and single ribonucleotide incorporation by DNA polymerases appears to be a common event. Moreover ribonucleotides are potentially mutagenic and lead to genome instability. As a consequence, errantly incorporated ribonucleotides are rapidly repaired in a process dependent upon RNase H enzymes. On the other hand, global genomic nucleotide excision repair (NER) in prokaryotes and eukaryotes removes damage caused by covalent modifications that typically distort and destabilize DNA through the production of lesions derived from bulky chemical carcinogens, such as polycyclic aromatic hydrocarbon metabolites, or via crosslinking. However, a recent study challenges this lesion-recognition paradigm. The work of Vaisman et al. (2013) [34] reveals that even a single ribonucleotide embedded in a deoxyribonucleotide duplex is recognized by the bacterial NER machinery in vitro. In their report, the authors show that spontaneous mutagenesis promoted by a steric-gate pol V mutant increases in uvrA, uvrB, or uvrC strains lacking rnhB (encoding RNase HII) and to a greater extent in an NER-deficient strain lacking both RNase HI and RNase HII. Using purified UvrA, UvrB, and UvrC proteins in in vitro assays they show that despite causing little distortion, a single ribonucleotide embedded in a DNA duplex is recognized and doubly-incised by the NER complex. We present the hypothesis to explain the recognition and/or verification of this small lesion, that the critical 2'-OH of the ribonucleotide - with its unique electrostatic and hydrogen bonding properties - may act as a signal through interactions with amino acid residues of the prokaryotic NER complex that are not possible with DNA. Such a mechanism might also be relevant if it were demonstrated that the eukaryotic NER machinery likewise incises an embedded ribonucleotide in DNA.
Collapse
|
38
|
Wang Y, Zhu S, Xu Y, Wang X, Zhu Y. Interaction between gene A-positive Helicobacter pylori and human leukocyte antigen II alleles increase the risk of Graves disease in Chinese Han population: An association study. Gene 2013; 531:84-9. [DOI: 10.1016/j.gene.2013.07.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 07/16/2013] [Indexed: 12/31/2022]
|
39
|
Rohlfing AK, Rust S, Reunert J, Tirre M, Du Chesne I, Wemhoff S, Meinhardt F, Hartmann H, Das AM, Marquardt T. ALG1-CDG: a new case with early fatal outcome. Gene 2014; 534:345-51. [PMID: 24157261 DOI: 10.1016/j.gene.2013.10.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 10/02/2013] [Accepted: 10/08/2013] [Indexed: 11/20/2022]
Abstract
Congenital disorders of glycosylation (CDG) are a growing group of inherited metabolic disorders where enzymatic defects in the formation or processing of glycolipids and/or glycoproteins lead to variety of different diseases. The deficiency of GDP-Man:GlcNAc2-PP-dolichol mannosyltransferase, encoded by the human ortholog of ALG1 from yeast, is known as ALG1-CDG (CDG-Ik). The phenotypical, molecular and biochemical analysis of a severely affected ALG1-CDG patient is the focus of this paper. The patient's main symptoms were feeding problems and diarrhea, profound hypoproteinemia with massive ascites, muscular hypertonia, seizures refractory to treatment, recurrent episodes of apnoea, cardiac and hepatic involvement and coagulation anomalies. Compound heterozygosity for the mutations c.1145T>C (M382T) and c.1312C>T (R438W) was detected in the patient's ALG1-coding sequence. In contrast to a previously reported speculation on R438W we confirmed both mutations as disease-causing in ALG1-CDG.
Collapse
|
40
|
Fotouhi A, Hagos WW, Ilic M, Wojcik A, Harms-Ringdahl M, de Gruijl F, Mullenders L, Jansen JG, Haghdoost S. Analysis of mutant frequencies and mutation spectra in hMTH1 knockdown TK6 cells exposed to UV radiation. Mutat Res 2013; 751-752:8-14. [PMID: 24144844 DOI: 10.1016/j.mrfmmm.2013.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/04/2013] [Accepted: 10/10/2013] [Indexed: 12/20/2022]
Abstract
Ultraviolet radiation is a highly mutagenic agent that damages the DNA by the formation of mutagenic photoproducts at dipyrimidine sites and by oxidative DNA damages via reactive oxygen species (ROS). ROS can also give rise to mutations via oxidation of dNTPs in the nucleotide pool, e.g. 8-oxo-dGTP and 2-OH-dATP and subsequent incorporation during DNA replication. Here we show that expression of human MutT homolog 1 (hMTH1) which sanitizes the nucleotide pool by dephosphorylating oxidized dNTPs, protects against mutagenesis induced by long wave UVA light and by UVB light but not by short wave UVC light. Mutational spectra analyses of UVA-induced mutations at the endogenous Thymidine kinase gene in human lymphoblastoid cells revealed that hMTH1 mainly protects cells from transitions at GC and AT base pairs.
Collapse
Affiliation(s)
- Asal Fotouhi
- Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Sweden
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Ahn YK, Tripathi S, Kim JH, Cho YI, Lee HE, Kim DS, Woo JG, Cho MC. Transcriptome analysis of Capsicum annuum varieties Mandarin and Blackcluster: assembly, annotation and molecular marker discovery. Gene 2014; 533:494-9. [PMID: 24125952 DOI: 10.1016/j.gene.2013.09.095] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Accepted: 09/26/2013] [Indexed: 11/22/2022]
Abstract
Next generation sequencing technologies have proven to be a rapid and cost-effective means to assemble and characterize gene content and identify molecular markers in various organisms. Pepper (Capsicum annuum L., Solanaceae) is a major staple vegetable crop, which is economically important and has worldwide distribution. High-throughput transcriptome profiling of two pepper cultivars, Mandarin and Blackcluster, using 454 GS-FLX pyrosequencing yielded 279,221 and 316,357 sequenced reads with a total 120.44 and 142.54Mb of sequence data (average read length of 431 and 450 nucleotides). These reads resulted from 17,525 and 16,341 'isogroups' and were assembled into 19,388 and 18,057 isotigs, and 22,217 and 13,153 singletons for both the cultivars, respectively. Assembled sequences were annotated functionally based on homology to genes in multiple public databases. Detailed sequence variant analysis identified a total of 9701 and 12,741 potential SNPs which eventually resulted in 1025 and 1059 genotype specific SNPs, for both the varieties, respectively, after examining SNP frequency distribution for each mapped unigenes. These markers for pepper will be highly valuable for marker-assisted breeding and other genetic studies.
Collapse
|
42
|
Van Cor-Hosmer SK, Kim DH, Daly MB, Daddacha W, Kim B. Restricted 5'-end gap repair of HIV-1 integration due to limited cellular dNTP concentrations in human primary macrophages. J Biol Chem 2013; 288:33253-62. [PMID: 24097986 DOI: 10.1074/jbc.m113.486787] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
HIV-1 proviral DNA integration into host chromosomal DNA is only partially completed by the viral integrase, leaving two single-stranded DNA gaps with 5'-end mismatched viral DNA flaps. It has been inferred that these gaps are repaired by the cellular DNA repair machinery. Here, we investigated the efficiency of gap repair at integration sites in different HIV-1 target cell types. First, we found that the general gap repair machinery in macrophages was attenuated compared with that in dividing CD4(+) T cells. In fact, the repair in macrophages was heavily reliant upon host DNA polymerase β (Pol β). Second, we tested whether the poor dNTP availability found in macrophages is responsible for the delayed HIV-1 proviral DNA integration in this cell type because the Km value of Pol β is much higher than the dNTP concentrations found in macrophages. Indeed, with the use of a modified quantitative AluI PCR assay, we demonstrated that the elevation of cellular dNTP concentrations accelerated DNA gap repair in macrophages at HIV-1 proviral DNA integration sites. Finally, we found that human monocytes, which are resistant to HIV-1 infection, exhibited severely restricted gap repair capacity due not only to the very low levels of dNTPs detected but also to the significantly reduced expression of Pol β. Taken together, these results suggest that the low dNTP concentrations found in macrophages and monocytes can restrict the repair steps necessary for HIV-1 integration.
Collapse
Affiliation(s)
- Sarah K Van Cor-Hosmer
- From the Department of Microbiology and Immunology, University of Rochester, Rochester, New York 14627
| | | | | | | | | |
Collapse
|
43
|
Li P, Deng WQ, Li TH, Song B, Shen YH. Illumina-based de novo transcriptome sequencing and analysis of Amanita exitialis basidiocarps. Gene 2013; 532:63-71. [PMID: 24050899 DOI: 10.1016/j.gene.2013.09.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 09/03/2013] [Accepted: 09/04/2013] [Indexed: 01/24/2023]
Abstract
Amanita exitialis is a lethal mushroom that was first discovered in Guangdong Province, China. The high content of amanitin in its basidiocarps makes it lethal to humans. To comprehensively characterize the A. exitialis transcriptome and analyze the Amanita toxins as well as their related gene family, transcriptome sequencing of A. exitialis was performed using Illumina HiSeq 2000 technology. A total of 25,563,688 clean reads were collected and assembled into 62,137 cDNA contigs with an average length of 481 bp and N50 length of 788 bp. A total of 27,826 proteins and 39,661 unigenes were identified among the assembled contigs. All of the unigenes were classified into 166 functional categories for understanding the gene functions and regulation pathways. The genes contributing to toxic peptide biosynthesis were analyzed. From this set, eleven gene sequences encoding the toxins or related cyclic peptides were discovered in the transcriptome. Three of these sequences matched the peptide toxins α-amanitin, β-amanitin, and phallacidin, while others matched amanexitide and seven matched unknown peptides. All of the genes encoding peptide toxins were confirmed by polymerase chain reaction (PCR) in A. exitialis, and the phylogenetic relationships among these proprotein sequences were discussed. The gene polymorphism and degeneracy of the toxin encoding sequences were found and analyzed. This study provides the first primary transcriptome of A. exitialis, which provided comprehensive gene expression information on the lethal amanitas at the transcriptional level, and could lay a strong foundation for functional genomics studies in those fungi.
Collapse
Affiliation(s)
- Peng Li
- School of Bioscience & Bioengineering, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Applied Microbiology, South China (The Ministry-Province Joint Development), Guangdong Institute of Microbiology, Guangzhou 510070, China
| | | | | | | | | |
Collapse
|
44
|
Polak E, Ficek A, Radvanszky J, Soltysova A, Urge O, Cmelova E, Kantarska D, Kadasi L. Phenylalanine hydroxylase deficiency in the Slovak population: genotype-phenotype correlations and genotype-based predictions of BH4-responsiveness. Gene 2013; 526:347-55. [PMID: 23764561 DOI: 10.1016/j.gene.2013.05.057] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 05/08/2013] [Accepted: 05/20/2013] [Indexed: 10/26/2022]
Abstract
We investigated the mutation spectrum of the phenylalanine hydroxylase gene (PAH) in a cohort of patients from 135 Slovak PKU families. Mutational screening of the known coding region, including conventional intron splice sites, was performed using high-resolution melting analysis, with subsequent sequencing analysis of the samples showing deviated melting profiles compared to control samples. The PAH gene was also screened for deletions and duplications using MLPA analysis. Forty-eight different disease causing mutations were identified in our patient group, including 30 missense, 8 splicing, 7 nonsense, 2 large deletions and 1 small deletion with frameshift; giving a detection rate of 97.6%. The most prevalent mutation was the p.R408W, occurring in 47% of all alleles, which concurs with results from neighboring and other Slavic countries. Other frequent mutations were: p.R158Q (5.3%), IVS12+1G>A (5.3%), p.R252W (5.1%), p.R261Q (3.9%) and p.A403V (3.6%). We also identified three novel missense mutations: p.F233I, p.R270I, p.F331S and one novel variant: c.-30A>T in the proximal part of the PAH gene promoter. A spectrum of 84 different genotypes was observed and a genotype based predictions of BH4-responsiveness were assessed. Among all genotypes, 36 were predicted to be BH4-responsive represented by 51 PKU families. In addition, genotype-phenotype correlations were performed.
Collapse
Affiliation(s)
- Emil Polak
- Comenius University, Faculty of Natural Sciences, Department of Molecular Biology, Mlynska Dolina, 842 15 Bratislava, Slovak Republic.
| | | | | | | | | | | | | | | |
Collapse
|
45
|
Wu L, van Peer A, Song W, Wang H, Chen M, Tan Q, Song C, Zhang M, Bao D. Cloning of the Lentinula edodes B mating-type locus and identification of the genetic structure controlling B mating. Gene 2013; 531:270-8. [PMID: 24029079 DOI: 10.1016/j.gene.2013.08.090] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 08/05/2013] [Accepted: 08/28/2013] [Indexed: 10/26/2022]
Abstract
During the life cycle of heterothallic tetrapolar Agaricomycetes such as Lentinula edodes (Berk.) Pegler, the mating type system, composed of unlinked A and B loci, plays a vital role in controlling sexual development and resulting formation of the fruit body. L. edodes is produced worldwide for consumption and medicinal purposes, and understanding its sexual development is therefore of great importance. A considerable amount of mating type factors has been indicated over the past decades but few genes have actually been identified, and no complete genetic structures of L. edodes B mating-type loci are available. In this study, we cloned the matB regions from two mating compatible L. edodes strains, 939P26 and 939P42. Four pheromone receptors were identified on each new matB region, together with three and four pheromone precursor genes in the respective strains. Gene polymorphism, phylogenetic analysis and distribution of pheromone receptors and pheromone precursors clearly indicate a bipartite matB locus, each sublocus containing a pheromone receptor and one or two pheromone precursors. Detailed sequence comparisons of genetic structures between the matB regions of strains 939P42, 939P26 and a previously reported strain SUP2 further supported this model and allowed identification of the B mating type subloci borders. Mating studies confirmed the control of B mating by the identified pheromone receptors and pheromones in L. edodes.
Collapse
Affiliation(s)
- Lin Wu
- Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, P.R. China; Key Laboratory of Edible Fungi Resources and Utilization (South), Ministry of Agriculture, P.R. China; National Engineering Research Center of Edible Fungi, Ministry of Science and Technology, P.R. China
| | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Tee KL, Wong TS. Polishing the craft of genetic diversity creation in directed evolution. Biotechnol Adv 2013; 31:1707-21. [PMID: 24012599 DOI: 10.1016/j.biotechadv.2013.08.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/31/2013] [Accepted: 08/31/2013] [Indexed: 12/25/2022]
Abstract
Genetic diversity creation is a core technology in directed evolution where a high quality mutant library is crucial to its success. Owing to its importance, the technology in genetic diversity creation has seen rapid development over the years and its application has diversified into other fields of scientific research. The advances in molecular cloning and mutagenesis since 2008 were reviewed. Specifically, new cloning techniques were classified based on their principles of complementary overhangs, homologous sequences, overlapping PCR and megaprimers and the advantages, drawbacks and performances of these methods were highlighted. New mutagenesis methods developed for random mutagenesis, focused mutagenesis and DNA recombination were surveyed. The technical requirements of these methods and the mutational spectra were compared and discussed with references to commonly used techniques. The trends of mutant library preparation were summarised. Challenges in genetic diversity creation were discussed with emphases on creating "smart" libraries, controlling the mutagenesis spectrum and specific challenges in each group of mutagenesis methods. An outline of the wider applications of genetic diversity creation includes genome engineering, viral evolution, metagenomics and a study of protein functions. The review ends with an outlook for genetic diversity creation and the prospective developments that can have future impact in this field.
Collapse
Affiliation(s)
- Kang Lan Tee
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, England, United Kingdom
| | | |
Collapse
|
47
|
Ainsworth WB, Hughes BT, Au WC, Sakelaris S, Kerscher O, Benton MG, Basrai MA. Cytoplasmic localization of Hug1p, a negative regulator of the MEC1 pathway, coincides with the compartmentalization of Rnr2p-Rnr4p. Biochem Biophys Res Commun 2013; 439:443-8. [PMID: 24012676 DOI: 10.1016/j.bbrc.2013.08.089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 08/28/2013] [Indexed: 11/18/2022]
Abstract
The evolutionarily conserved MEC1 checkpoint pathway mediates cell cycle arrest and induction of genes including the RNR (Ribonucleotide reductase) genes and HUG1 (Hydroxyurea, ultraviolet, and gamma radiation) in response to DNA damage and replication arrest. Rnr complex activity is in part controlled by cytoplasmic localization of the Rnr2p-Rnr4p subunits and inactivation of negative regulators Sml1p and Dif1p upon DNA damage and hydroxyurea (HU) treatment. We previously showed that a deletion of HUG1 rescues lethality of mec1Δ and suppresses dun1Δ strains. In this study, multiple approaches demonstrate the regulatory response of Hug1p to DNA damage and HU treatment and support its role as a negative effector of the MEC1 pathway. Consistent with our hypothesis, wild-type cells are sensitive to DNA damage and HU when HUG1 is overexpressed. A Hug1 polyclonal antiserum reveals that HUG1 encodes a protein in budding yeast and its MEC1-dependent expression is delayed compared to the rapid induction of Rnr3p in response to HU treatment. Cell biology and subcellular fractionation experiments show localization of Hug1p-GFP to the cytoplasm upon HU treatment. The cytoplasmic localization of Hug1p-GFP is dependent on MEC1 pathway genes and coincides with the cytoplasmic localization of Rnr2p-Rnr4p. Taken together, the genetic interactions, gene expression, and localization studies support a novel role for Hug1p as a negative regulator of the MEC1 checkpoint response through its compartmentalization with Rnr2p-Rnr4p.
Collapse
Affiliation(s)
- William B Ainsworth
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Bridget Todd Hughes
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Chun Au
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sally Sakelaris
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Oliver Kerscher
- Biology Department, The College of William & Mary, Williamsburg, VA 23185, USA
| | - Michael G Benton
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Munira A Basrai
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| |
Collapse
|
48
|
Zhan J, He HY, Wang TJ, Wang AQ, Li CZ, He LF. Aluminum-induced programmed cell death promoted by AhSAG, a senescence-associated gene in Arachis hypoganea L. Plant Sci 2013; 210:108-17. [PMID: 23849118 DOI: 10.1016/j.plantsci.2013.05.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 05/14/2013] [Accepted: 05/19/2013] [Indexed: 05/11/2023]
Abstract
Programmed cell death (PCD) is a foundational cellular process in plant development and elimination of damaged cells under environmental stresses. In this study, Al induced PCD in two peanut (Arachis hypoganea L.) cultivars Zhonghua 2 (Al-sensitive) and 99-1507 (Al-tolerant) using DNA ladder, TUNEL detection and electron microscopy. The concentration of Al-induced PCD was lower in Zhonghua 2 than in 99-1507. AhSAG, a senescence-associated gene was isolated from cDNA library of Al-stressed peanut with PCD. Open reading frame (ORF) of AhSAG was 474bp, encoding a SAG protein composed of 157 amino acids. Compared to the control and the antisense transgenic tobacco plants, the fast development and blossom of the sense transgenic plants happened to promote senescence. The ability of Al tolerance in sense transgenic tobacco was lower than in antisense transgenic tobacco according to root elongation and Al content analysis. The expression of AhSAG-GFP was higher in sense transgenic tobacco than in antisense transgenic tobacco. Altogether, these results indicated that there was a negative relationship between Al-induced PCD and Al-resistance in peanut, and the AhSAG could induce or promote the occurrence of PCD in plants.
Collapse
Affiliation(s)
- Jie Zhan
- College of Agronomy, Guangxi University, Nanning 530004, PR China
| | | | | | | | | | | |
Collapse
|
49
|
Mackawy AMH. Association of the + 45T>G adiponectin gene polymorphism with insulin resistance in non-diabetic Saudi women. Gene 2013; 530:158-63. [PMID: 23958652 DOI: 10.1016/j.gene.2013.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/24/2013] [Accepted: 07/01/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND The human adiponectin gene variations are associated with obesity, insulin resistance, and diabetes. However, these associations have not been fully examined in a non-diabetic population in Saudi Arabia. We aimed to investigate the association of 45T>G single nucleotide polymorphism (SNP) in the adiponectin gene with total adiponectin levels, insulin resistance (IR), fasting blood glucose (FBG) and other markers of obesity in non-diabetic Saudi females. METHODS One hundred non diabetic Saudi females were enrolled in this study. They were further divided according to their body mass index (BMI) into two groups. Group I, 46 non diabetic subjects with normal body weight and group II, 54 overweight and obese females. Adiponectin 45T/G polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Serum adiponectin was measured by ELISA. RESULTS Obese women exhibited a higher distribution of TG/GG genotype compared with non-obese women. SNP +45T>G genotypes were associated with higher FBG, insulin levels and HOMA-IR with lower total adiponectin levels in obese Saudi women. Otherwise the all estimated variables revealed non-significant differences among the non-obese genotypes. The observed differences in insulin resistance markers were very significant among women with a higher body weight but not among normal body weight women, thus suggesting that SNP +45T>G effects on insulin sensitivity may depend upon body weight and body fat status. CONCLUSION SNP +45T>G of adiponectin gene has a significant role in the development of insulin resistance in Saudi women possibly through an interaction with increase body weight and hypoadiponectinemia.
Collapse
|
50
|
Ben Mahmoud A, Siala O, Mansour RB, Driss F, Baklouti-Gargouri S, Mkaouar-Rebai E, Belguith N, Fakhfakh F. First functional analysis of a novel splicing mutation in the B3GALTL gene by an ex vivo approach in Tunisian patients with typical Peters plus syndrome. Gene 2013; 532:13-7. [PMID: 23954224 DOI: 10.1016/j.gene.2013.07.058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Revised: 07/03/2013] [Accepted: 07/11/2013] [Indexed: 11/17/2022]
Abstract
Peters plus syndrome is a rare recessive autosomal disorder comprising ocular anterior segment dysgenesis, short stature, hand abnormalities and distinctive facial features. It was related only to mutations in the B3GALTL gene in the 13q12.3 region. In this study, we undertook the first functional analysis of a novel c.597-2 A>G splicing mutation within the B3GALTL gene using an ex-vivo approach. The results showed a complete skipping of exon 8 in the B3GALTL cDNA, which altered the open reading frame of the mutant transcript and generated a PTC within exon 9. This finding potentially elicits the nonsense mRNA to degradation by NMD (nonsense-mediated mRNA decay). The theoretical consequences of splice site mutations, predicted with the bioinformatics tool Human Splice Finder, were investigated and evaluated in relation to ex-vivo results. The findings confirmed the key role played by the B3GALTL gene in typical Peters-plus syndromes and the utility of mRNA analysis to understand the primary impacts of this mutation and the phenotype of the disease.
Collapse
Affiliation(s)
- Afif Ben Mahmoud
- Laboratoire de Génétique Moléculaire Humaine, Faculté de Médecine de Sfax, Université de Sfax, Tunisia.
| | | | | | | | | | | | | | | |
Collapse
|