1
|
Moghimi S, Viktorova EG, Gabaglio S, Zimina A, Budnik B, Wynn BG, Sztul E, Belov GA. A Proximity biotinylation assay with a host protein bait reveals multiple factors modulating enterovirus replication. PLoS Pathog 2022; 18:e1010906. [PMID: 36306280 PMCID: PMC9645661 DOI: 10.1371/journal.ppat.1010906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 11/09/2022] [Accepted: 09/30/2022] [Indexed: 11/07/2022] Open
Abstract
As ultimate parasites, viruses depend on host factors for every step of their life cycle. On the other hand, cells evolved multiple mechanisms of detecting and interfering with viral replication. Yet, our understanding of the complex ensembles of pro- and anti-viral factors is very limited in virtually every virus-cell system. Here we investigated the proteins recruited to the replication organelles of poliovirus, a representative of the genus Enterovirus of the Picornaviridae family. We took advantage of a strict dependence of enterovirus replication on a host protein GBF1, and established a stable cell line expressing a truncated GBF1 fused to APEX2 peroxidase that effectively supported viral replication upon inhibition of the endogenous GBF1. This construct biotinylated multiple host and viral proteins on the replication organelles. Among the viral proteins, the polyprotein cleavage intermediates were overrepresented, suggesting that the GBF1 environment is linked to viral polyprotein processing. The proteomics characterization of biotinylated host proteins identified multiple proteins previously associated with enterovirus replication, as well as more than 200 new factors recruited to the replication organelles. RNA metabolism proteins, many of which normally localize in the nucleus, constituted the largest group, underscoring the massive release of nuclear factors into the cytoplasm of infected cells and their involvement in viral replication. Functional analysis of several newly identified proteins revealed both pro- and anti-viral factors, including a novel component of infection-induced stress granules. Depletion of these proteins similarly affected the replication of diverse enteroviruses indicating broad conservation of the replication mechanisms. Thus, our data significantly expand the knowledge of the composition of enterovirus replication organelles, provide new insights into viral replication, and offer a novel resource for identifying targets for anti-viral interventions.
Collapse
Affiliation(s)
- Seyedehmahsa Moghimi
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Ekaterina G. Viktorova
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Samuel Gabaglio
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Anna Zimina
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| | - Bogdan Budnik
- Mass Spectrometry and Proteomics Resource Laboratory (MSPRL), FAS Division of Science, Harvard University, Cambridge, Massachusetts, United States of America
| | - Bridge G. Wynn
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham; Birmingham, Alabama, United States of America
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham; Birmingham, Alabama, United States of America
| | - George A. Belov
- Department of Veterinary Medicine and Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, Maryland, United States of America
| |
Collapse
|
2
|
Spizzichino S, Boi D, Boumis G, Lucchi R, Liberati FR, Capelli D, Montanari R, Pochetti G, Piacentini R, Parisi G, Paone A, Rinaldo S, Contestabile R, Tramonti A, Paiardini A, Giardina G, Cutruzzolà F. Cytosolic localization and in vitro assembly of human de novo thymidylate synthesis complex. FEBS J 2021; 289:1625-1649. [PMID: 34694685 PMCID: PMC9299187 DOI: 10.1111/febs.16248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 10/21/2021] [Indexed: 11/27/2022]
Abstract
De novo thymidylate synthesis is a crucial pathway for normal and cancer cells. Deoxythymidine monophosphate (dTMP) is synthesized by the combined action of three enzymes: serine hydroxymethyltransferase (SHMT1), dihydrofolate reductase (DHFR) and thymidylate synthase (TYMS), with the latter two being targets of widely used chemotherapeutics such as antifolates and 5‐fluorouracil. These proteins translocate to the nucleus after SUMOylation and are suggested to assemble in this compartment into the thymidylate synthesis complex. We report the intracellular dynamics of the complex in cancer cells by an in situ proximity ligation assay, showing that it is also detected in the cytoplasm. This result indicates that the role of the thymidylate synthesis complex assembly may go beyond dTMP synthesis. We have successfully assembled the dTMP synthesis complex in vitro, employing tetrameric SHMT1 and a bifunctional chimeric enzyme comprising human thymidylate synthase and dihydrofolate reductase. We show that the SHMT1 tetrameric state is required for efficient complex assembly, indicating that this aggregation state is evolutionarily selected in eukaryotes to optimize protein–protein interactions. Lastly, our results regarding the activity of the complete thymidylate cycle in vitro may provide a useful tool with respect to developing drugs targeting the entire complex instead of the individual components.
Collapse
Affiliation(s)
- Sharon Spizzichino
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Dalila Boi
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Giovanna Boumis
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Roberta Lucchi
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | | | - Davide Capelli
- Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Roberta Montanari
- Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Giorgio Pochetti
- Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Roberta Piacentini
- Center for Life Nano & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome, Italy
| | - Giacomo Parisi
- Center for Life Nano & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome, Italy
| | - Alessio Paone
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Serena Rinaldo
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | | | - Angela Tramonti
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy.,Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche, Rome, Italy
| | | | - Giorgio Giardina
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Francesca Cutruzzolà
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy.,Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy
| |
Collapse
|
3
|
Martella M, Catalanotto C, Talora C, La Teana A, Londei P, Benelli D. Inhibition of Eukaryotic Translation Initiation Factor 5A (eIF5A) Hypusination Suppress p53 Translation and Alters the Association of eIF5A to the Ribosomes. Int J Mol Sci 2020; 21:E4583. [PMID: 32605139 PMCID: PMC7369855 DOI: 10.3390/ijms21134583] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/17/2020] [Accepted: 06/25/2020] [Indexed: 12/22/2022] Open
Abstract
The eukaryotic translation initiation factor 5A (eIF5A) is an essential protein for the viability of the cells whose proposed function is to prevent the stalling of the ribosomes during translation elongation. eIF5A activity requires a unique and functionally essential post-translational modification, the change of a lysine to hypusine. eIF5A is recognized as a promoter of cell proliferation, but it has also been suggested to induce apoptosis. To date, the precise molecular mechanism through which eIF5A affects these processes remains elusive. In the present study, we explored whether eIF5A is involved in controlling the stress-induced expression of the key cellular regulator p53. Our results show that treatment of HCT-116 colon cancer cells with the deoxyhypusine (DHS) inhibitor N1-guanyl-1,7-diamineheptane (GC7) caused both inhibition of eIF5A hypusination and a significant reduction of p53 expression in UV-treated cells, and that eIF5A controls p53 expression at the level of protein synthesis. Furthermore, we show that treatment with GC7 followed by UV-induced stress counteracts the pro-apoptotic process triggered by p53 up-regulation. More in general, the importance of eIF5A in the cellular stress response is illustrated by the finding that exposure to UV light promotes the binding of eIF5A to the ribosomes, whereas UV treatment complemented by the presence of GC7 inhibits such binding, allowing a decrease of de novo synthesis of p53 protein.
Collapse
Affiliation(s)
- Marianna Martella
- Division of Cancer Therapeutics, The Institute of Cancer Research, London SW7 3RP, UK
| | - Caterina Catalanotto
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291/324, 00161 Rome, Italy; (C.C.); (C.T.); (P.L.)
| | - Claudio Talora
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291/324, 00161 Rome, Italy; (C.C.); (C.T.); (P.L.)
| | - Anna La Teana
- Department of Life and Environmental Science, Polytechnic University of Marche, 60131 Ancona, Italy;
| | - Paola Londei
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291/324, 00161 Rome, Italy; (C.C.); (C.T.); (P.L.)
| | - Dario Benelli
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291/324, 00161 Rome, Italy; (C.C.); (C.T.); (P.L.)
| |
Collapse
|
4
|
Ghayour-Mobarhan M, Zangouei AS, Hosseinirad SM, Mojarrad M, Moghbeli M. Genetics of blood malignancies among Iranian population: an overview. Diagn Pathol 2020; 15:44. [PMID: 32375828 PMCID: PMC7201799 DOI: 10.1186/s13000-020-00968-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/29/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Blood malignancies are among the leading causes of cancer related deaths in the world. Different environmental and genetic risk factors are involved in progression of blood malignancies. It has been shown that the lifestyle changes have affected the epidemiological patterns of these malignancies. Hematologic cancers are the 5th common cancer among Iranian population. It has been observed that there is a rising trend of blood malignancies incidences during the recent decades. Therefore, it is required to design novel diagnostic methods for the early detection of such malignancies in this population. MAIN BODY In present review we have summarized all of the significant genes which have been reported among Iranian patients with blood malignancies. The reported genes were categorized based on their cell and molecular functions to clarify the molecular biology and genetics of blood malignancies among Iranian patients. CONCLUSION It was observed that the epigenetic and immune response factors were the most frequent molecular processes associated with progression of blood malignancies among Iranian population. This review paves the way of introducing a population based panel of genetic markers for the early detection of blood malignancies in this population.
Collapse
Affiliation(s)
- Majid Ghayour-Mobarhan
- Metabolic Syndrome Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Amir Sadra Zangouei
- Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | - Majid Mojarrad
- Department of Medical Genetics and Molecular Medicine, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Meysam Moghbeli
- Department of Medical Genetics and Molecular Medicine, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| |
Collapse
|
5
|
Kwan T, Thompson SR. Noncanonical Translation Initiation in Eukaryotes. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032672. [PMID: 29959190 DOI: 10.1101/cshperspect.a032672] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The vast majority of eukaryotic messenger RNAs (mRNAs) initiate translation through a canonical, cap-dependent mechanism requiring a free 5' end and 5' cap and several initiation factors to form a translationally active ribosome. Stresses such as hypoxia, apoptosis, starvation, and viral infection down-regulate cap-dependent translation during which alternative mechanisms of translation initiation prevail to express proteins required to cope with the stress, or to produce viral proteins. The diversity of noncanonical initiation mechanisms encompasses a broad range of strategies and cellular cofactors. Herein, we provide an overview and, whenever possible, a mechanistic understanding of the various noncanonical mechanisms of initiation used by cells and viruses. Despite many unanswered questions, recent advances have propelled our understanding of the scope, diversity, and mechanisms of alternative initiation.
Collapse
Affiliation(s)
- Thaddaeus Kwan
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Sunnie R Thompson
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| |
Collapse
|
6
|
Godet AC, David F, Hantelys F, Tatin F, Lacazette E, Garmy-Susini B, Prats AC. IRES Trans-Acting Factors, Key Actors of the Stress Response. Int J Mol Sci 2019; 20:ijms20040924. [PMID: 30791615 PMCID: PMC6412753 DOI: 10.3390/ijms20040924] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 02/12/2019] [Accepted: 02/14/2019] [Indexed: 12/16/2022] Open
Abstract
The cellular stress response corresponds to the molecular changes that a cell undergoes in response to various environmental stimuli. It induces drastic changes in the regulation of gene expression at transcriptional and posttranscriptional levels. Actually, translation is strongly affected with a blockade of the classical cap-dependent mechanism, whereas alternative mechanisms are activated to support the translation of specific mRNAs. A major mechanism involved in stress-activated translation is the internal ribosome entry site (IRES)-driven initiation. IRESs, first discovered in viral mRNAs, are present in cellular mRNAs coding for master regulators of cell responses, whose expression must be tightly controlled. IRESs allow the translation of these mRNAs in response to different stresses, including DNA damage, amino-acid starvation, hypoxia or endoplasmic reticulum stress, as well as to physiological stimuli such as cell differentiation or synapse network formation. Most IRESs are regulated by IRES trans-acting factor (ITAFs), exerting their action by at least nine different mechanisms. This review presents the history of viral and cellular IRES discovery as well as an update of the reported ITAFs regulating cellular mRNA translation and of their different mechanisms of action. The impact of ITAFs on the coordinated expression of mRNA families and consequences in cell physiology and diseases are also highlighted.
Collapse
Affiliation(s)
- Anne-Claire Godet
- UMR 1048-I2MC, Inserm, Université de Toulouse, UT3, 31432 Toulouse cedex 4, France.
| | - Florian David
- UMR 1048-I2MC, Inserm, Université de Toulouse, UT3, 31432 Toulouse cedex 4, France.
| | - Fransky Hantelys
- UMR 1048-I2MC, Inserm, Université de Toulouse, UT3, 31432 Toulouse cedex 4, France.
| | - Florence Tatin
- UMR 1048-I2MC, Inserm, Université de Toulouse, UT3, 31432 Toulouse cedex 4, France.
| | - Eric Lacazette
- UMR 1048-I2MC, Inserm, Université de Toulouse, UT3, 31432 Toulouse cedex 4, France.
| | - Barbara Garmy-Susini
- UMR 1048-I2MC, Inserm, Université de Toulouse, UT3, 31432 Toulouse cedex 4, France.
| | - Anne-Catherine Prats
- UMR 1048-I2MC, Inserm, Université de Toulouse, UT3, 31432 Toulouse cedex 4, France.
| |
Collapse
|
7
|
The Vitamin D⁻Folate Hypothesis as an Evolutionary Model for Skin Pigmentation: An Update and Integration of Current Ideas. Nutrients 2018; 10:nu10050554. [PMID: 29710859 PMCID: PMC5986434 DOI: 10.3390/nu10050554] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/27/2018] [Accepted: 04/27/2018] [Indexed: 12/24/2022] Open
Abstract
Vitamin D is unique in being generated in our skin following ultraviolet radiation (UVR) exposure. Ongoing research into vitamin D must therefore always consider the influence of UVR on vitamin D processes. The close relationship between vitamin D and UVR forms the basis of the “vitamin D–folate hypothesis”, a popular theory for why human skin colour has evolved as an apparent adaption to UVR environments. Vitamin D and folate have disparate sensitivities to UVR; whilst vitamin D may be synthesised following UVR exposure, folate may be degraded. The vitamin D–folate hypothesis proposes that skin pigmentation has evolved as a balancing mechanism, maintaining levels of these vitamins. There are several alternative theories that counter the vitamin D–folate hypothesis. However, there is significant overlap between these theories and the now known actions of vitamin D and folate in the skin. The focus of this review is to present an update on the vitamin D–folate hypothesis by integrating these current theories and discussing new evidence that supports associations between vitamin D and folate genetics, UVR, and skin pigmentation. In light of recent human migrations and seasonality in disease, the need for ongoing research into potential UVR-responsive processes within the body is also discussed.
Collapse
|
8
|
Lucock M, Jones P, Martin C, Yates Z, Veysey M, Furst J, Beckett E. Photobiology of vitamins. Nutr Rev 2018; 76:512-525. [DOI: 10.1093/nutrit/nuy013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Mark Lucock
- School of Environmental & Life Sciences, University of Newcastle, New South Wales, Australia
| | - Patrice Jones
- School of Environmental & Life Sciences, University of Newcastle, New South Wales, Australia
| | - Charlotte Martin
- School of Environmental & Life Sciences, University of Newcastle, New South Wales, Australia
| | - Zoe Yates
- School of Biomedical Sciences & Pharmacy, University of Newcastle, New South Wales, Australia
| | - Martin Veysey
- Hull-York Medical School, University of York, Heslington, York, United Kingdom
| | - John Furst
- School of Mathematical & Physical Sciences, University of Newcastle, Ourimbah, New South Wales, Australia
| | - Emma Beckett
- School of Environmental & Life Sciences, University of Newcastle, New South Wales, Australia
- School of Medicine & Public Health, University of Newcastle, New South Wales, Australia
| |
Collapse
|
9
|
Jones P, Lucock M, Veysey M, Jablonski N, Chaplin G, Beckett E. Frequency of folate-related polymorphisms varies by skin pigmentation. Am J Hum Biol 2017; 30. [DOI: 10.1002/ajhb.23079] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/27/2017] [Accepted: 10/29/2017] [Indexed: 12/12/2022] Open
Affiliation(s)
- Patrice Jones
- School of Environmental & Life Sciences, University of Newcastle; Ourimbah NSW Australia
| | - Mark Lucock
- School of Environmental & Life Sciences, University of Newcastle; Ourimbah NSW Australia
| | - Martin Veysey
- Hull-York Medical School; University of York; Heslington York UK
| | - Nina Jablonski
- Anthropology Department; The Pennsylvania State University; Pennsylvania
| | - George Chaplin
- Anthropology Department; The Pennsylvania State University; Pennsylvania
| | - Emma Beckett
- School of Environmental & Life Sciences, University of Newcastle; Ourimbah NSW Australia
- School of Medicine and Public Health; University of Newcastle; Ourimbah NSW Australia
| |
Collapse
|
10
|
Abstract
Protein modification with the small ubiquitin-related modifier (SUMO) can affect protein function, enzyme activity, protein-protein interactions, protein stability, protein targeting and cellular localization. SUMO influences the function and regulation of metabolic enzymes within pathways, and in some cases targets entire metabolic pathways by affecting the activity of transcription factors or by facilitating the translocation of entire metabolic pathways to subcellular compartments. SUMO modification is also a key component of nutrient- and metabolic-sensing mechanisms that regulate cellular metabolism. In addition to its established roles in maintaining metabolic homeostasis, there is increasing evidence that SUMO is a key factor in facilitating cellular stress responses through the regulation and/or adaptation of the most fundamental metabolic processes, including energy and nucleotide metabolism. This review focuses on the role of SUMO in cellular metabolism and metabolic disease.
Collapse
|
11
|
Ali MU, Ur Rahman MS, Jia Z, Jiang C. Eukaryotic translation initiation factors and cancer. Tumour Biol 2017; 39:1010428317709805. [PMID: 28653885 DOI: 10.1177/1010428317709805] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Recent technological advancements have shown tremendous mechanistic accomplishments in our understanding of the mechanism of messenger RNA translation in eukaryotic cells. Eukaryotic messenger RNA translation is very complex process that includes four phases (initiation, elongation, termination, and ribosome recycling) and diverse mechanisms involving protein and non-protein molecules. Translation regulation is principally achieved during initiation step of translation, which is organized by multiple eukaryotic translation initiation factors. Eukaryotic translation initiation factor proteins help in stabilizing the formation of the functional ribosome around the start codon and provide regulatory mechanisms in translation initiation. Dysregulated messenger RNA translation is a common feature of tumorigenesis. Various oncogenic and tumor suppressive genes affect/are affected by the translation machinery, making the components of the translation apparatus promising therapeutic targets for the novel anticancer drug. This review provides details on the role of eukaryotic translation initiation factors in messenger RNA translation initiation, their contribution to onset and progression of tumor, and how dysregulated eukaryotic translation initiation factors can be used as a target to treat carcinogenesis.
Collapse
Affiliation(s)
- Muhammad Umar Ali
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Muhammad Saif Ur Rahman
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhenyu Jia
- 2 Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, China
| | - Cao Jiang
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
12
|
Folate rescues vitamin B 12 depletion-induced inhibition of nuclear thymidylate biosynthesis and genome instability. Proc Natl Acad Sci U S A 2017; 114:E4095-E4102. [PMID: 28461497 DOI: 10.1073/pnas.1619582114] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Clinical vitamin B12 deficiency can result in megaloblastic anemia, which results from the inhibition of DNA synthesis by trapping folate cofactors in the form of 5-methyltetrahydrofolate (5-methylTHF) and subsequent inhibition of de novo thymidylate (dTMP) biosynthesis. In the cytosol, vitamin B12 functions in the remethylation of homocysteine to methionine, which regenerates THF from 5-methylTHF. In the nucleus, THF is required for de novo dTMP biosynthesis, but it is not understood how 5-methylTHF accumulation in the cytosol impairs nuclear dTMP biosynthesis. The impact of vitamin B12 depletion on nuclear de novo dTMP biosynthesis was investigated in methionine synthase-null human fibroblast and nitrous oxide-treated HeLa cell models. The nucleus was the most sensitive cellular compartment to 5-methylTHF accumulation, with levels increasing greater than fourfold. Vitamin B12 depletion decreased de novo dTMP biosynthesis capacity by 5-35%, whereas de novo purine synthesis, which occurs in the cytosol, was not affected. Phosphorylated histone H2AX (γH2AX), a marker of DNA double-strand breaks, was increased in vitamin B12 depletion, and this effect was exacerbated by folate depletion. These studies also revealed that 5-formylTHF, a slow, tight-binding inhibitor of serine hydroxymethyltransferase (SHMT), was enriched in nuclei, accounting for 35% of folate cofactors, explaining previous observations that nuclear SHMT is not a robust source of one-carbons for de novo dTMP biosynthesis. These findings indicate that a nuclear 5-methylTHF trap occurs in vitamin B12 depletion, which suppresses de novo dTMP biosynthesis and causes DNA damage, accounting for the pathophysiology of megaloblastic anemia observed in vitamin B12 and folate deficiency.
Collapse
|
13
|
Abstract
Thymidylate (dTMP) biosynthesis plays an essential and exclusive function in DNA synthesis and proper cell division, and therefore has been an attractive therapeutic target. Folate analogs, known as antifolates, and nucleotide analogs that inhibit the enzymatic action of the de novo thymidylate biosynthesis pathway and are commonly used in cancer treatment. In this review, we examine the mechanisms by which the antifolate 5-fluorouracil, as well as other dTMP synthesis inhibitors, function in cancer treatment in light of emerging evidence that dTMP synthesis occurs in the nucleus. Nuclear localization of the de novo dTMP synthesis pathway requires modification of the pathway enzymes by the small ubiquitin-like modifier (SUMO) protein. SUMOylation is required for nuclear localization of the de novo dTMP biosynthesis pathway, and disruption in the SUMO pathway inhibits cell proliferation in several cancer models. We summarize evidence that the nuclear localization of the dTMP biosynthesis pathway is a critical factor in the efficacy of antifolate-based therapies that target dTMP synthesis.
Collapse
|
14
|
Field MS, Kamynina E, Watkins D, Rosenblatt DS, Stover PJ. New insights into the metabolic and nutritional determinants of severe combined immunodeficiency. Rare Dis 2015; 3:e1112479. [PMID: 27123375 PMCID: PMC4817835 DOI: 10.1080/21675511.2015.1112479] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/20/2015] [Accepted: 10/19/2015] [Indexed: 11/07/2022] Open
Abstract
Human mutations in MTHFD1 have recently been identified in patients with severe
combined immunodeficiency (SCID). SCID results from inborn errors of metabolism
that cause impaired T- and B-cell proliferation and function. One of the most
common causes of SCID is adenosine deaminase (ADA) deficiency, which ultimately
inhibits DNA synthesis and cell division. MTHFD1 has been shown to translocate
to the nucleus during S-phase of the cell cycle; this localization is critical
for synthesis of thymidyate (dTMP or the “T” base in DNA) and
subsequent progression through the cell cycle and cell proliferation.
Identification of MTHFD1 mutations that are associated with
SCID highlights the potential importance of adequate dTMP synthesis in the
etiology of SCID.
Collapse
Affiliation(s)
- Martha S Field
- Division of Nutritional Sciences; Cornell University ; Ithaca, NY USA
| | - Elena Kamynina
- Division of Nutritional Sciences; Cornell University ; Ithaca, NY USA
| | - David Watkins
- Department of Human Genetics, McGill University; Department of Medical Genetics; McGill University Health Center ; Montreal, Quebec, Canada
| | - David S Rosenblatt
- Department of Human Genetics, McGill University; Department of Medical Genetics; McGill University Health Center ; Montreal, Quebec, Canada
| | - Patrick J Stover
- Division of Nutritional Sciences; Cornell University; Ithaca, NY USA; Graduate Field of Biochemistry; Molecular and Cell Biology; Cornell University; Ithaca, NY USA
| |
Collapse
|
15
|
Shkreta L, Chabot B. The RNA Splicing Response to DNA Damage. Biomolecules 2015; 5:2935-77. [PMID: 26529031 PMCID: PMC4693264 DOI: 10.3390/biom5042935] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 09/20/2015] [Accepted: 10/16/2015] [Indexed: 12/29/2022] Open
Abstract
The number of factors known to participate in the DNA damage response (DDR) has expanded considerably in recent years to include splicing and alternative splicing factors. While the binding of splicing proteins and ribonucleoprotein complexes to nascent transcripts prevents genomic instability by deterring the formation of RNA/DNA duplexes, splicing factors are also recruited to, or removed from, sites of DNA damage. The first steps of the DDR promote the post-translational modification of splicing factors to affect their localization and activity, while more downstream DDR events alter their expression. Although descriptions of molecular mechanisms remain limited, an emerging trend is that DNA damage disrupts the coupling of constitutive and alternative splicing with the transcription of genes involved in DNA repair, cell-cycle control and apoptosis. A better understanding of how changes in splice site selection are integrated into the DDR may provide new avenues to combat cancer and delay aging.
Collapse
Affiliation(s)
- Lulzim Shkreta
- Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
| | - Benoit Chabot
- Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
| |
Collapse
|
16
|
Knutsen JHJ, Rødland GE, Bøe CA, Håland TW, Sunnerhagen P, Grallert B, Boye E. Stress-induced inhibition of translation independently of eIF2α phosphorylation. J Cell Sci 2015; 128:4420-7. [PMID: 26493332 PMCID: PMC4712817 DOI: 10.1242/jcs.176545] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/28/2015] [Indexed: 01/21/2023] Open
Abstract
Exposure of fission yeast cells to ultraviolet (UV) light leads to inhibition of translation and phosphorylation of the eukaryotic initiation factor-2α (eIF2α). This phosphorylation is a common response to stress in all eukaryotes. It leads to inhibition of translation at the initiation stage and is thought to be the main reason why stressed cells dramatically reduce protein synthesis. Phosphorylation of eIF2α has been taken as a readout for downregulation of translation, but the role of eIF2α phosphorylation in the downregulation of general translation has not been much investigated. We show here that UV-induced global inhibition of translation in fission yeast cells is independent of eIF2α phosphorylation and the eIF2α kinase general control nonderepressible-2 protein (Gcn2). Also, in budding yeast and mammalian cells, the UV-induced translational depression is largely independent of GCN2 and eIF2α phosphorylation. Furthermore, exposure of fission yeast cells to oxidative stress generated by hydrogen peroxide induced an inhibition of translation that is also independent of Gcn2 and of eIF2α phosphorylation. Our findings show that stress-induced translational inhibition occurs through an unknown mechanism that is likely to be conserved through evolution. Summary: In contrast to textbook knowledge, the phosphorylation of translation initiation factor eIF2α is not required for UV-induced inhibition of protein synthesis, which we show in three different cell types.
Collapse
Affiliation(s)
| | - Gro Elise Rødland
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Cathrine Arnason Bøe
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Tine Weise Håland
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Per Sunnerhagen
- Department of Chemistry & Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Erik Boye
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| |
Collapse
|
17
|
Field MS, Kamynina E, Agunloye OC, Liebenthal RP, Lamarre SG, Brosnan ME, Brosnan JT, Stover PJ. Nuclear enrichment of folate cofactors and methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) protect de novo thymidylate biosynthesis during folate deficiency. J Biol Chem 2014; 289:29642-50. [PMID: 25213861 DOI: 10.1074/jbc.m114.599589] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Folate-mediated one-carbon metabolism is a metabolic network of interconnected pathways that is required for the de novo synthesis of three of the four DNA bases and the remethylation of homocysteine to methionine. Previous studies have indicated that the thymidylate synthesis and homocysteine remethylation pathways compete for a limiting pool of methylenetetrahydrofolate cofactors and that thymidylate biosynthesis is preserved in folate deficiency at the expense of homocysteine remethylation, but the mechanisms are unknown. Recently, it was shown that thymidylate synthesis occurs in the nucleus, whereas homocysteine remethylation occurs in the cytosol. In this study we demonstrate that methylenetetrahydrofolate dehydrogenase 1 (MTHFD1), an enzyme that generates methylenetetrahydrofolate from formate, ATP, and NADPH, functions in the nucleus to support de novo thymidylate biosynthesis. MTHFD1 translocates to the nucleus in S-phase MCF-7 and HeLa cells. During folate deficiency mouse liver MTHFD1 levels are enriched in the nucleus >2-fold at the expense of levels in the cytosol. Furthermore, nuclear folate levels are resistant to folate depletion when total cellular folate levels are reduced by >50% in mouse liver. The enrichment of folate cofactors and MTHFD1 protein in the nucleus during folate deficiency in mouse liver and human cell lines accounts for previous metabolic studies that indicated 5,10-methylenetetrahydrofolate is preferentially directed toward de novo thymidylate biosynthesis at the expense of homocysteine remethylation during folate deficiency.
Collapse
Affiliation(s)
- Martha S Field
- From the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853 and
| | - Elena Kamynina
- From the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853 and
| | | | - Rebecca P Liebenthal
- From the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853 and
| | - Simon G Lamarre
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada
| | - Margaret E Brosnan
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada
| | - John T Brosnan
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada
| | - Patrick J Stover
- From the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853 and
| |
Collapse
|
18
|
Hung CY, Yang WB, Wang SA, Hsu TI, Chang WC, Hung JJ. Nucleolin enhances internal ribosomal entry site (IRES)-mediated translation of Sp1 in tumorigenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2843-54. [PMID: 25173817 DOI: 10.1016/j.bbamcr.2014.08.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 07/14/2014] [Accepted: 08/20/2014] [Indexed: 11/24/2022]
Abstract
Our previous study indicated that specificity protein-1 (Sp1) is accumulated during hypoxia in an internal ribosomal entry site (IRES)-dependent manner. Herein, we found that the Sp1 was induced strongly at the protein level, but not in the mRNA level, in lung tumor tissue, indicating that translational regulation might contribute to the Sp1 accumulation during tumorigenesis. A further study showed that the translation of Sp1 was dramatically induced through an IRES-dependent pathway. RNA immunoprecipitation analysis of proteins bound to the 5'-untranslated region (5'-UTR) of Sp1 identified interacting protein - nucleolin. Knockdown of nucleolin significantly inhibited IRES-mediated translation of Sp1, suggesting that nucleolin positively facilitates Sp1 IRES activation. Further analysis of the interaction between nucleolin and the 5'-UTR of Sp1 mRNA revealed that the GAR domain was important for IRES-mediated translation of Sp1. Moreover, gefitinib, and LY294002 and MK2206 compounds inhibited IRES-mediated Sp1 translation, implying that activation of the epithelial growth factor receptor (EGFR) pathway via Akt activation triggers the IRES pathway. In conclusion, EGFR activation-mediated nucleolin phosphorylated at Thr641 and Thr707 was recruited to the 5'-UTR of Sp1 as an IRES trans-acting factor to modulate Sp1 translation during lung cancer formation.
Collapse
Affiliation(s)
- Chia-Yang Hung
- Institute of Basic Medical Sciences, College of Medicine, National Cheng-Kung University, Tainan, Taiwan
| | - Wen-Bin Yang
- Institute of Bioinformatics and Biosignal Transduction, College of Bioscience in Biotechnology, National Cheng-Kung University, Tainan, Taiwan
| | - Shao-An Wang
- Institute of Bioinformatics and Biosignal Transduction, College of Bioscience in Biotechnology, National Cheng-Kung University, Tainan, Taiwan
| | - Tsung-I Hsu
- Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan; Institute of Bioinformatics and Biosignal Transduction, College of Bioscience in Biotechnology, National Cheng-Kung University, Tainan, Taiwan; Center for Infection Disease and Signal Transduction, National Cheng-Kung University, Tainan, Taiwan
| | - Wen-Chang Chang
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Jan-Jong Hung
- Institute of Basic Medical Sciences, College of Medicine, National Cheng-Kung University, Tainan, Taiwan; Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan; Institute of Bioinformatics and Biosignal Transduction, College of Bioscience in Biotechnology, National Cheng-Kung University, Tainan, Taiwan; Center for Infection Disease and Signal Transduction, National Cheng-Kung University, Tainan, Taiwan; Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
| |
Collapse
|
19
|
Lucock M, Yates Z, Martin C, Choi JH, Boyd L, Tang S, Naumovski N, Furst J, Roach P, Jablonski N, Chaplin G, Veysey M. Vitamin D, folate, and potential early lifecycle environmental origin of significant adult phenotypes. EVOLUTION MEDICINE AND PUBLIC HEALTH 2014; 2014:69-91. [PMID: 24699387 PMCID: PMC4001294 DOI: 10.1093/emph/eou013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Solar radiation early in pregnancy interacts with light sensitive vitamins to influence an embryo's genetic profile. This influences both adult disease risk and may play a role in the evolution of skin colour. Background and objectives: Vitamin D and folate are highly UV sensitive, and critical for maintaining health throughout the lifecycle. This study examines whether solar irradiance during the first trimester of pregnancy influences vitamin D receptor (VDR) and nuclear folate gene variant occurrence, and whether affected genes influence late-life biochemical/clinical phenotypes. Methodology: 228 subjects were examined for periconceptional exposure to solar irradiance, variation in vitamin D/folate genes (polymerase chain reaction (PCR)), dietary intake (food frequency questionnaire (FFQ)) and important adult biochemical/clinical phenotypes. Results: Periconceptional solar irradiance was associated with VDR-BsmI (P = 0.0008wk7), TaqI (P = 0.0014wk7) and EcoRV (P = 0.0030wk6) variant occurrence between post-conceptional weeks 6–8, a period when ossification begins. Similar effects were detected for other VDR gene polymorphisms. Periconceptional solar irradiance was also associated with 19 bp del-DHFR (P = 0.0025wk6), and to a lesser extent C1420T-SHMT (P = 0.0249wk6), a folate-critical time during embryogenesis. These same genes were associated with several late-life phenotypes: VDR-BsmI, TaqI and ApaI determined the relationship between dietary vitamin D and both insulin (P < 0.0001/BB, 0.0007/tt and 0.0173/AA, respectively) and systolic blood pressure (P = 0.0290/Bb, 0.0299/Tt and 0.0412/AA, respectively), making them important early and late in the lifecycle. While these and other phenotype associations were found for the VDR variants, folate polymorphism associations in later-life were limited to C1420T-SHMT (P = 0.0037 and 0.0297 for fasting blood glucose and HbA1c levels, respectively). We additionally report nutrient–gene relationships with body mass index, thiol/folate metabolome, cognition, depression and hypertension. Furthermore, photoperiod at conception influenced occurrence of VDR-Tru9I and 2R3R-TS genotypes (P = 0.0120 and 0.0360, respectively). Conclusions and implications: Findings identify environmental and nutritional agents that may interact to modify gene–phenotype relationships across the lifecycle, offering new insight into human ecology. This includes factors related to both disease aetiology and the evolution of skin pigmentation.
Collapse
Affiliation(s)
- Mark Lucock
- School of Environmental and Life Sciences, Biomedical Sciences and Pharmacy, Maths and Physical Sciences, University of Newcastle, PO Box 127, Brush Road, Ourimbah, NSW 2258, Australia, The Pennsylvania State University, Anthropology Department, 409 Carpenter Building, University Park, PA 16802, USA, and Teaching and Research Unit, Central Coast Local Health District, PO Box 361, Gosford, NSW 2250, Australia
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Martínez-Salas E, Lozano G, Fernandez-Chamorro J, Francisco-Velilla R, Galan A, Diaz R. RNA-binding proteins impacting on internal initiation of translation. Int J Mol Sci 2013; 14:21705-26. [PMID: 24189219 PMCID: PMC3856030 DOI: 10.3390/ijms141121705] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/17/2013] [Accepted: 10/22/2013] [Indexed: 12/20/2022] Open
Abstract
RNA-binding proteins (RBPs) are pivotal regulators of all the steps of gene expression. RBPs govern gene regulation at the post-transcriptional level by virtue of their capacity to assemble ribonucleoprotein complexes on certain RNA structural elements, both in normal cells and in response to various environmental stresses. A rapid cellular response to stress conditions is triggered at the step of translation initiation. Two basic mechanisms govern translation initiation in eukaryotic mRNAs, the cap-dependent initiation mechanism that operates in most mRNAs, and the internal ribosome entry site (IRES)-dependent mechanism activated under conditions that compromise the general translation pathway. IRES elements are cis-acting RNA sequences that recruit the translation machinery using a cap-independent mechanism often assisted by a subset of translation initiation factors and various RBPs. IRES-dependent initiation appears to use different strategies to recruit the translation machinery depending on the RNA organization of the region and the network of RBPs interacting with the element. In this review we discuss recent advances in understanding the implications of RBPs on IRES-dependent translation initiation.
Collapse
Affiliation(s)
- Encarnación Martínez-Salas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain.
| | | | | | | | | | | |
Collapse
|
21
|
Cámara Y, González-Vioque E, Scarpelli M, Torres-Torronteras J, Martí R. Feeding the deoxyribonucleoside salvage pathway to rescue mitochondrial DNA. Drug Discov Today 2013; 18:950-7. [DOI: 10.1016/j.drudis.2013.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 05/27/2013] [Accepted: 06/19/2013] [Indexed: 12/16/2022]
|
22
|
Scotti M, Stella L, Shearer EJ, Stover PJ. Modeling cellular compartmentation in one-carbon metabolism. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2013; 5:343-65. [PMID: 23408533 DOI: 10.1002/wsbm.1209] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Folate-mediated one-carbon metabolism (FOCM) is associated with risk for numerous pathological states including birth defects, cancers, and chronic diseases. Although the enzymes that constitute the biological pathways have been well described and their interdependency through the shared use of folate cofactors appreciated, the biological mechanisms underlying disease etiologies remain elusive. The FOCM network is highly sensitive to nutritional status of several B-vitamins and numerous penetrant gene variants that alter network outputs, but current computational approaches do not fully capture the dynamics and stochastic noise of the system. Combining the stochastic approach with a rule-based representation will help model the intrinsic noise displayed by FOCM, address the limited flexibility of standard simulation methods for coarse-graining the FOCM-associated biochemical processes, and manage the combinatorial complexity emerging from reactions within FOCM that would otherwise be intractable.
Collapse
Affiliation(s)
- Marco Scotti
- The Microsoft Research-University of Trento Centre for Computational and Systems Biology (COSBI), Rovereto, Italy
| | | | | | | |
Collapse
|
23
|
Daba A, Koromilas AE, Pantopoulos K. Alternative ferritin mRNA translation via internal initiation. RNA (NEW YORK, N.Y.) 2012; 18:547-556. [PMID: 22271759 PMCID: PMC3285941 DOI: 10.1261/rna.029322.111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 12/08/2011] [Indexed: 05/31/2023]
Abstract
Ferritin stores and detoxifies an excess of intracellular iron, and thereby plays an important role in the metabolism of this metal. As unshielded iron promotes oxidative stress, ferritin is crucial in maintaining cellular redox balance and may also modulate cell growth, survival, and apoptosis. The expression of ferritin is controlled by transcriptional and post-transcriptional mechanisms. In light of the well-established transcriptional induction of ferritin by inflammatory signals, we examined how ferritin mRNA translation responds to stress conditions. We first used HT1080 fibrosarcoma cells engineered for coumermycin-inducible expression of PKR, a stress kinase that inhibits protein synthesis in virus-infected cells by phosphorylating eIF2α. In this setting, iron triggered partial ferritin mRNA translation despite a PKR-induced global shutdown in protein synthesis. Moreover, iron-mediated ferritin synthesis was evident in cells infected with an attenuated strain of poliovirus; when eIF4GI was cleaved, eIF2α was phosphorylated, and host protein synthesis was inhibited. Under global inhibition of protein synthesis or specific inhibition of ferritin mRNA translation in cells overexpressing PKR or IRP1, respectively, we demonstrate association of ferritin mRNA with heavy polysomes. Further experiments revealed that the 5' untranslated region (5' UTR) of ferritin mRNA contains a bona fide internal ribosomal entry site (IRES). Our data are consistent with the existence of an alternative, noncanonical mechanism for ferritin mRNA translation, which may primarily operate under stress conditions to protect cells from oxidative stress.
Collapse
Affiliation(s)
- Alina Daba
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montreal, Quebec H2T 1E2, Canada
- Department of Medicine, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Antonis E. Koromilas
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montreal, Quebec H2T 1E2, Canada
- Department of Oncology, McGill University, Montreal, Quebec H2W 1S6, Canada
| | - Kostas Pantopoulos
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montreal, Quebec H2T 1E2, Canada
- Department of Medicine, McGill University, Montreal, Quebec H3G 1Y6, Canada
| |
Collapse
|
24
|
Alternative Mechanisms to Initiate Translation in Eukaryotic mRNAs. Comp Funct Genomics 2012; 2012:391546. [PMID: 22536116 PMCID: PMC3321441 DOI: 10.1155/2012/391546] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 01/20/2012] [Indexed: 12/13/2022] Open
Abstract
The composition of the cellular proteome is under the control of multiple processes, one of the most important being translation initiation. The majority of eukaryotic cellular mRNAs initiates translation by the cap-dependent or scanning mode of translation initiation, a mechanism that depends on the recognition of the m(7)G(5')ppp(5')N, known as the cap. However, mRNAs encoding proteins required for cell survival under stress bypass conditions inhibitory to cap-dependent translation; these mRNAs often harbor internal ribosome entry site (IRES) elements in their 5'UTRs that mediate internal initiation of translation. This mechanism is also exploited by mRNAs expressed from the genome of viruses infecting eukaryotic cells. In this paper we discuss recent advances in understanding alternative ways to initiate translation across eukaryotic organisms.
Collapse
|
25
|
Anderson DD, Woeller CF, Chiang EP, Shane B, Stover PJ. Serine hydroxymethyltransferase anchors de novo thymidylate synthesis pathway to nuclear lamina for DNA synthesis. J Biol Chem 2012; 287:7051-62. [PMID: 22235121 DOI: 10.1074/jbc.m111.333120] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The de novo thymidylate biosynthetic pathway in mammalian cells translocates to the nucleus for DNA replication and repair and consists of the enzymes serine hydroxymethyltransferase 1 and 2α (SHMT1 and SHMT2α), thymidylate synthase, and dihydrofolate reductase. In this study, we demonstrate that this pathway forms a multienzyme complex that is associated with the nuclear lamina. SHMT1 or SHMT2α is required for co-localization of dihydrofolate reductase, SHMT, and thymidylate synthase to the nuclear lamina, indicating that SHMT serves as scaffold protein that is essential for complex formation. The metabolic complex is enriched at sites of DNA replication initiation and associated with proliferating cell nuclear antigen and other components of the DNA replication machinery. These data provide a mechanism for previous studies demonstrating that SHMT expression is rate-limiting for de novo thymidylate synthesis and indicate that de novo thymidylate biosynthesis occurs at replication forks.
Collapse
Affiliation(s)
- Donald D Anderson
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | | | | | | | | |
Collapse
|
26
|
Anderson DD, Eom JY, Stover PJ. Competition between sumoylation and ubiquitination of serine hydroxymethyltransferase 1 determines its nuclear localization and its accumulation in the nucleus. J Biol Chem 2011; 287:4790-9. [PMID: 22194612 DOI: 10.1074/jbc.m111.302174] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Serine hydroxymethyltransferase 1 (SHMT1) expression limits rates of de novo dTMP synthesis in the nucleus. Here we report that SHMT1 is ubiquitinated at the small ubiquitin-like modifier (SUMO) consensus motif and that ubiquitination at that site is required for SHMT1 degradation. SHMT1 protein levels are cell cycle-regulated, and Ub-SHMT1 levels are lowest at S phase when SHMT1 undergoes SUMO modification and nuclear transport. Mutation of the SUMO consensus motif increases SHMT1 stability. SHMT1 interacts with components of the proteasome in both the nucleus and cytoplasm, indicating that degradation occurs in both compartments. Ubc13-mediated ubiquitination is required for SHMT1 nuclear export and increases stability of SHMT1 within the nucleus, whereas Ubc9-mediated modification with Sumo2/3 is involved in nuclear degradation. These data demonstrate that SUMO and ubiquitin modification of SHMT1 occurs on the same lysine residue and determine the localization and accumulation of SHMT1 in the nucleus.
Collapse
Affiliation(s)
- Donald D Anderson
- Graduate Field of Biochemistry and Molecular and Cell Biology, DK56339, USA
| | | | | |
Collapse
|
27
|
MacFarlane AJ, Anderson DD, Flodby P, Perry CA, Allen RH, Stabler SP, Stover PJ. Nuclear localization of de novo thymidylate biosynthesis pathway is required to prevent uracil accumulation in DNA. J Biol Chem 2011; 286:44015-44022. [PMID: 22057276 DOI: 10.1074/jbc.m111.307629] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Uracil accumulates in DNA as a result of impaired folate-dependent de novo thymidylate biosynthesis, a pathway composed of the enzymes serine hydroxymethyltransferase (SHMT), thymidylate synthase (TYMS), and dihydrofolate reductase. In G1, this pathway is present in the cytoplasm and at S phase undergoes small ubiquitin-like modifier-dependent translocation to the nucleus. It is not known whether this pathway functions in the cytoplasm, nucleus, or both in vivo. SHMT1 generates 5,10-methylenetetrahydrofolate for de novo thymidylate biosynthesis, a limiting step in the pathway, but also tightly binds 5-methyltetrahydrofolate in the cytoplasm, a required cofactor for homocysteine remethylation. Overexpression of SHMT1 in cell cultures inhibits folate-dependent homocysteine remethylation and enhances thymidylate biosynthesis. In this study, the impact of increased Shmt1 expression on folate-mediated one-carbon metabolism was determined in mice that overexpress the Shmt1 cDNA (Shmt1tg+ mice). Compared with wild type mice, Shmt1tg+ mice exhibited elevated SHMT1 and TYMS protein levels in tissues and evidence for impaired homocysteine remethylation but surprisingly exhibited depressed levels of nuclear SHMT1 and TYMS, lower rates of nuclear de novo thymidylate biosynthesis, and a nearly 10-fold increase in uracil content in hepatic nuclear DNA when fed a folate- and choline-deficient diet. These results demonstrate that SHMT1 and TYMS localization to the nucleus is essential to prevent uracil accumulation in nuclear DNA and indicate that SHMT1-mediated nuclear de novo thymidylate synthesis is critical for maintaining DNA integrity.
Collapse
Affiliation(s)
- Amanda J MacFarlane
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
| | - Donald D Anderson
- Graduate Field of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853
| | - Per Flodby
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
| | - Cheryll A Perry
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
| | - Robert H Allen
- Department of Medicine and Division of Hematology, University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Sally P Stabler
- Department of Medicine and Division of Hematology, University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Patrick J Stover
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853; Graduate Field of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.
| |
Collapse
|
28
|
Identification of a de novo thymidylate biosynthesis pathway in mammalian mitochondria. Proc Natl Acad Sci U S A 2011; 108:15163-8. [PMID: 21876188 DOI: 10.1073/pnas.1103623108] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The de novo and salvage dTTP pathways are essential for maintaining cellular dTTP pools to ensure the faithful replication of both mitochondrial and nuclear DNA. Disregulation of dTTP pools results in mitochondrial dysfunction and nuclear genome instability due to an increase in uracil misincorporation. In this study, we identified a de novo dTMP synthesis pathway in mammalian mitochondria. Mitochondria purified from wild-type Chinese hamster ovary (CHO) cells and HepG2 cells converted dUMP to dTMP in the presence of NADPH and serine, through the activities of mitochondrial serine hydroxymethyltransferase (SHMT2), thymidylate synthase (TYMS), and a novel human mitochondrial dihydrofolate reductase (DHFR) previously thought to be a pseudogene known as dihydrofolate reductase-like protein 1 (DHFRL1). Human DHFRL1, SHMT2, and TYMS were localized to mitochondrial matrix and inner membrane, confirming the presence of this pathway in mitochondria. Knockdown of DHFRL1 using siRNA eliminated DHFR activity in mitochondria. DHFRL1 expression in CHO glyC, a previously uncharacterized mutant glycine auxotrophic cell line, rescued the glycine auxotrophy. De novo thymidylate synthesis activity was diminished in mitochondria isolated from glyA CHO cells that lack SHMT2 activity, as well as mitochondria isolated from wild-type CHO cells treated with methotrexate, a DHFR inhibitor. De novo thymidylate synthesis in mitochondria prevents uracil accumulation in mitochondrial DNA (mtDNA), as uracil levels in mtDNA isolated from glyA CHO cells was 40% higher than observed in mtDNA isolated from wild-type CHO cells. These data indicate that unlike other nucleotides, de novo dTMP synthesis occurs within mitochondria and is essential for mtDNA integrity.
Collapse
|
29
|
Abstract
Mandatory and discretionary fortification with folic acid is eliminating deficiency of this vitamin. Blood levels of the vitamin have never been higher, with hematologic folate values commonly exceeding the upper range of calibration. The synthetic analog (pteroylmonoglutamic acid) prevents neural tube defects and lowers homocysteine, both positive attributes, yet negative correlates of pteroylmonoglutamic acid are increasingly reported. These involve increased risk for common cancers (ie, colon, breast, prostate) and antimetabolite effects on natural killer cells and at dihydrofolate reductase, a critical gatekeeper enzyme. This review, however, takes a different, human ecological perspective, examining novel folate-related phenomena distinct from the classic metabolic role of the vitamin in maintaining health and well-being. An argument is developed that at molecular, cellular, and organism levels, folate is crucial to some important events that link light to life.
Collapse
|
30
|
p53 inhibits mRNA 3′ processing through its interaction with the CstF/BARD1 complex. Oncogene 2011; 30:3073-83. [DOI: 10.1038/onc.2011.29] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
31
|
Spriggs KA, Bushell M, Willis AE. Translational regulation of gene expression during conditions of cell stress. Mol Cell 2010; 40:228-37. [PMID: 20965418 DOI: 10.1016/j.molcel.2010.09.028] [Citation(s) in RCA: 523] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 09/10/2010] [Accepted: 09/28/2010] [Indexed: 01/17/2023]
Abstract
A number of stresses, including nutrient stress, temperature shock, DNA damage, and hypoxia, can lead to changes in gene expression patterns caused by a general shutdown and reprogramming of protein synthesis. Each of these stress conditions results in selective recruitment of ribosomes to mRNAs whose protein products are required for responding to stress. This recruitment is regulated by elements within the 5' and 3' untranslated regions of mRNAs, including internal ribosome entry segments, upstream open reading frames, and microRNA target sites. These elements can act singly or in combination and are themselves regulated by trans-acting factors. Translational reprogramming can result in increased life span, and conversely, deregulation of these translation pathways is associated with disease including cancer and diabetes.
Collapse
Affiliation(s)
- Keith A Spriggs
- Centre for Biomolecular Sciences, School of Pharmacy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | | | | |
Collapse
|
32
|
Chen YL, Eriksson S, Chang ZF. Regulation and functional contribution of thymidine kinase 1 in repair of DNA damage. J Biol Chem 2010; 285:27327-27335. [PMID: 20554529 DOI: 10.1074/jbc.m110.137042] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cellular supply of dNTPs is essential in the DNA replication and repair processes. Here we investigated the regulation of thymidine kinase 1 (TK1) in response to DNA damage and found that genotoxic insults in tumor cells cause up-regulation and nuclear localization of TK1. During recovery from DNA damage, TK1 accumulates in p53-null cells due to a lack of mitotic proteolysis as these cells are arrested in the G(2) phase by checkpoint activation. We show that in p53-proficient cells, p21 expression in response to DNA damage prohibits G(1)/S progression, resulting in a smaller G(2) fraction and less TK1 accumulation. Thus, the p53 status of tumor cells affects the level of TK1 after DNA damage through differential cell cycle control. Furthermore, it was shown that in HCT-116 p53(-/-) cells, TK1 is dispensable for cell proliferation but crucial for dTTP supply during recovery from DNA damage, leading to better survival. Depletion of TK1 decreases the efficiency of DNA repair during recovery from DNA damage and generates more cell death. Altogether, our data suggest that more dTTP synthesis via TK1 take place after genotoxic insults in tumor cells, improving DNA repair during G(2) arrest.
Collapse
Affiliation(s)
- Yen-Ling Chen
- Graduate Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-Ai Road, Taipei 100, Taiwan
| | - Staffan Eriksson
- Department of Anatomy, Physiology and Biochemistry, The Swedish University of Agricultural Sciences, Biomedical Center, S-751 23 Uppsala, Sweden
| | - Zee-Fen Chang
- Graduate Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-Ai Road, Taipei 100, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang-Ming University, No. 155, Section 2, Linong Street, Taipei 112, Taiwan.
| |
Collapse
|
33
|
Fox JT, Stover PJ. Mechanism of the internal ribosome entry site-mediated translation of serine hydroxymethyltransferase 1. J Biol Chem 2009; 284:31085-96. [PMID: 19734143 DOI: 10.1074/jbc.m109.035576] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The 5'-untranslated region (UTR) of serine hydroxymethyltransferase 1 (SHMT1) contains an internal ribosome entry site (IRES) that regulates SHMT1 expression, a rate-limiting enzyme in de novo thymidylate biosynthesis. In this study, we show that the SHMT1 IRES is the first example of a cellular IRES that is poly(A) tail-independent. Interactions between the 5'-UTR and 3'-UTR functionally replaced interactions between the poly(A) tail and the poly(A)-binding protein (PABP) to achieve maximal IRES-mediated translational efficiency. Depletion of the SHMT1 IRES-specific trans-acting factor (ITAF) CUG-binding protein 1 (CUGBP1) from in vitro translation extracts or deletion of the CUGBP1 binding site on the 3'-UTR of the SHMT1 transcript decreased the IRES activity of non-polyadenylylated biscistronic mRNAs relative to polyadenylylated biscistronic mRNAs and resulted in a requirement for PABP. We also identified a novel ITAF, heterogeneous nuclear ribonucleoprotein H2 (hnRNP H2), that stimulates SHMT1 IRES activity by binding to the 5'-UTR of the transcript and interacting with CUGBP1. Collectively, these data support a model for the IRES-mediated translation of SHMT1 whereby the circularization of the mRNA typically provided by the eukaryotic initiation factor (eIF) 4G/PABP/poly(A) tail interaction is achieved instead through the hnRNP H2/CUGBP1-mediated interaction of the 5'- and 3'-UTRs of the SHMT1 transcript. This circularization enhances the IRES activity of SHMT1 by facilitating the recruitment and/or recycling of ribosomal subunits, which bind to the transcript in the middle of the 5'-UTR and migrate to the initiation codon via eIF4A-mediated scanning.
Collapse
Affiliation(s)
- Jennifer T Fox
- Graduate Field of Biochemistry and Molecular and Cellular Biology, Cornell University, Ithaca, New York 14853, USA
| | | |
Collapse
|