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Kumar C, Mylavarapu SVS. Nucleolin is required for multiple centrosome-associated functions in early vertebrate mitosis. Chromosoma 2023; 132:305-315. [PMID: 37615728 DOI: 10.1007/s00412-023-00808-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 06/10/2023] [Accepted: 08/11/2023] [Indexed: 08/25/2023]
Abstract
Nucleolin is a multifunctional RNA-binding protein that resides predominantly not only in the nucleolus, but also in multiple other subcellular pools in the cytoplasm in mammalian cells, and is best known for its roles in ribosome biogenesis, RNA stability, and translation. During early mitosis, nucleolin is required for equatorial mitotic chromosome alignment prior to metaphase. Using high resolution fluorescence imaging, we reveal that nucleolin is required for multiple centrosome-associated functions at the G2-prophase boundary. Nucleolin depletion led to dissociation of the centrosomes from the G2 nuclear envelope, a delay in the onset of nuclear envelope breakdown, reduced inter-centrosome separation, and longer metaphase spindles. Our results reveal novel roles for nucleolin in early mammalian mitosis, establishing multiple important functions for nucleolin during mammalian cell division.
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Affiliation(s)
- Chandan Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, -121001, India
| | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, -121001, India.
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2
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Ofir R, Kriecherbauer T, Grüne L, Margaliot M. On the gain of entrainment in the n-dimensional ribosome flow model. J R Soc Interface 2023; 20:20220763. [PMID: 36751928 PMCID: PMC9905980 DOI: 10.1098/rsif.2022.0763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 01/11/2023] [Indexed: 02/09/2023] Open
Abstract
The ribosome flow model (RFM) is a phenomenological model for the flow of particles along a one-dimensional chain of n sites. It has been extensively used to study ribosome flow along the mRNA molecule during translation. When the transition rates along the chain are time-varying and jointly T-periodic the RFM entrains, i.e. every trajectory of the RFM converges to a unique T-periodic solution that depends on the transition rates, but not on the initial condition. In general, entrainment to periodic excitations like the 24 h solar day or the 50 Hz frequency of the electric grid is important in numerous natural and artificial systems. An interesting question, called the gain of entrainment (GOE) in the RFM, is whether proper coordination of the periodic translation rates along the mRNA can lead to a larger average protein production rate. Analysing the GOE in the RFM is non-trivial and partial results exist only for the RFM with dimensions n = 1, 2. We use a new approach to derive several results on the GOE in the general n-dimensional RFM. Perhaps surprisingly, we rigorously characterize several cases where there is no GOE, so to maximize the average production rate in these cases, the best choice is to use constant transition rates all along the chain.
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Affiliation(s)
- Ron Ofir
- Andrew and Erna Viterbi Faculty of Electrical and Computer Engineering, Technion—Israel Institute of Technology, Haifa 3200003, Israel
| | | | - Lars Grüne
- Mathematical Institute, University of Bayreuth, Bayreuth, Germany
| | - Michael Margaliot
- School of Electrical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
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3
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Ribosome-Directed Therapies in Cancer. Biomedicines 2022; 10:biomedicines10092088. [PMID: 36140189 PMCID: PMC9495564 DOI: 10.3390/biomedicines10092088] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/22/2022] [Accepted: 08/22/2022] [Indexed: 12/29/2022] Open
Abstract
The human ribosomes are the cellular machines that participate in protein synthesis, which is deeply affected during cancer transformation by different oncoproteins and is shown to provide cancer cell proliferation and therefore biomass. Cancer diseases are associated with an increase in ribosome biogenesis and mutation of ribosomal proteins. The ribosome represents an attractive anti-cancer therapy target and several strategies are used to identify specific drugs. Here we review the role of different drugs that may decrease ribosome biogenesis and cancer cell proliferation.
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4
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Ambaru B, Gangadharan GM, Subramanya HS, Gupta CM. Profilin is involved in G1 to S phase progression and mitotic spindle orientation during Leishmania donovani cell division cycle. PLoS One 2022; 17:e0265692. [PMID: 35316283 PMCID: PMC8939790 DOI: 10.1371/journal.pone.0265692] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 03/04/2022] [Indexed: 11/27/2022] Open
Abstract
Profilin is a multi-ligand binding protein, which is a key regulator of actin dynamics and involved in regulating several cellular functions. It is present in all eukaryotes, including trypanosomatids such as Leishmania. However, not much is known about its functions in these organisms. Our earlier studies have shown that Leishmania parasites express a single homologue of profilin (LdPfn) that binds actin, phosphoinositides and poly- L- proline motives, and depletion of its intracellular pool to 50%of normal levels affects the cell growth and intracellular trafficking. Here, we show, employing affinity pull-down and mass spectroscopy, that LdPfn interacted with a large number of proteins, including those involved in mRNA processing and protein translation initiation, such as eIF4A1. Further, we reveal, using mRNA Seq analysis, that depletion of LdPfn in Leishmania cells (LdPfn+/-) resulted in significantly reduced expression of genes which encode proteins involved in cell cycle regulation, mRNA translation initiation, nucleosides and amino acids transport. In addition, we show that in LdPfn+/- cells, cellular levels of eIF4A1 protein were significantly decreased, and during their cell division cycle, G1-to-S phase progression was delayed and orientation of mitotic spindle altered. These changes were, however, reversed to normal by episomal expression of GFP-LdPfn in LdPfn+/- cells. Taken together, our results indicate that profilin is involved in regulation of G1-to-S phase progression and mitotic spindle orientation in Leishmania cell cycle, perhaps through its interaction with elF4A1 protein.
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Affiliation(s)
- Bindu Ambaru
- Institute of Bioinformatics and Applied Biotechnology, Bengaluru, Karnataka, India
- Manipal Academy of Higher Education, Manipal, Karnataka, India
| | | | | | - Chhitar M. Gupta
- Institute of Bioinformatics and Applied Biotechnology, Bengaluru, Karnataka, India
- * E-mail:
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5
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A single-cell analysis of the Arabidopsis vegetative shoot apex. Dev Cell 2021; 56:1056-1074.e8. [PMID: 33725481 DOI: 10.1016/j.devcel.2021.02.021] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/06/2020] [Accepted: 02/19/2021] [Indexed: 01/13/2023]
Abstract
The shoot apical meristem allows for reiterative formation of new aerial structures throughout the life cycle of a plant. We use single-cell RNA sequencing to define the cellular taxonomy of the Arabidopsis vegetative shoot apex at the transcriptome level. We find that the shoot apex is composed of highly heterogeneous cells, which can be partitioned into 7 broad populations with 23 transcriptionally distinct cell clusters. We delineate cell-cycle continuums and developmental trajectories of epidermal cells, vascular tissue, and leaf mesophyll cells and infer transcription factors and gene expression signatures associated with cell fate decisions. Integrative analysis of shoot and root apical cell populations further reveals common and distinct features of epidermal and vascular tissues. Our results, thus, offer a valuable resource for investigating the basic principles underlying cell division and differentiation in plants at single-cell resolution.
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6
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Hayek H, Gross L, Janvier A, Schaeffer L, Martin F, Eriani G, Allmang C. eIF3 interacts with histone H4 messenger RNA to regulate its translation. J Biol Chem 2021; 296:100578. [PMID: 33766559 PMCID: PMC8102920 DOI: 10.1016/j.jbc.2021.100578] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/15/2021] [Accepted: 03/21/2021] [Indexed: 11/23/2022] Open
Abstract
In eukaryotes, various alternative translation initiation mechanisms have been unveiled for the translation of specific mRNAs. Some do not conform to the conventional scanning-initiation model. Translation initiation of histone H4 mRNA combines both canonical (cap-dependent) and viral initiation strategies (no-scanning, internal recruitment of initiation factors). Specific H4 mRNA structures tether the translation machinery directly onto the initiation codon and allow massive production of histone H4 during the S phase of the cell cycle. The human eukaryotic translation initiation factor 3 (eIF3), composed of 13 subunits (a-m), was shown to selectively recruit and control the expression of several cellular mRNAs. Whether eIF3 mediates H4 mRNA translation remains to be elucidated. Here, we report that eIF3 binds to a stem-loop structure (eIF3-BS) located in the coding region of H4 mRNA. Combining cross-linking and ribonucleoprotein immunoprecipitation experiments in vivo and in vitro, we also found that eIF3 binds to H1, H2A, H2B, and H3 histone mRNAs. We identified direct contacts between eIF3c, d, e, g subunits, and histone mRNAs but observed distinct interaction patterns to each histone mRNA. Our results show that eIF3 depletion in vivo reduces histone mRNA binding and modulates histone neosynthesis, suggesting that synthesis of histones is sensitive to the levels of eIF3. Thus, we provide evidence that eIF3 acts as a regulator of histone translation.
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Affiliation(s)
- Hassan Hayek
- Architecture et Réactivité de l'ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Lauriane Gross
- Architecture et Réactivité de l'ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Aurélie Janvier
- Architecture et Réactivité de l'ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Laure Schaeffer
- Architecture et Réactivité de l'ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Franck Martin
- Architecture et Réactivité de l'ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Gilbert Eriani
- Architecture et Réactivité de l'ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France.
| | - Christine Allmang
- Architecture et Réactivité de l'ARN, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France.
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7
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Ruan T, Zhang Y, Liu W, Li Y, Wang D, Du Z, Tao K, Wu C. Expression of DCP1a in gastric cancer and its biological function and mechanism in chemotherapy resistance in gastric cancer cells. Dig Liver Dis 2020; 52:1351-1358. [PMID: 32646734 DOI: 10.1016/j.dld.2020.06.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 12/11/2022]
Abstract
AIMS To detect the role of DCP1a in gastric cancer. To estimate the effect of DCP1a in gastric cancer cells on proliferation, invasion, migration and anti-drug behavior in vitro by down-regulating its expression. METHODS Using IHC staining and Western blot to check the expression of DCP1a in tissues and the cell lines. SGC7901 and BGC823 cells were transfected with DCP1a siRNA, and the expression of DCP1a protein and mRNA were detected. The cell proliferation rate was detected by MTT assay and plate cloning assay. Transwell assay was used to detect the change of cell metastasis. The inhibition rates of cells to chemotherapy were detected by MTT assay. And signal pathways were also detected. RESULTS The expression of DCP1a in cancer tissues is higher (p < 0.05), and higher expression of DCP1a is related to poor prognosis. After down-regulating the expression of DCP1a in cells, the proliferation rates, migration abilities and chemotherapy resistance decrease. We find that the expression of MRP-1 and the activation of AKT and STAT3 pathways might be involved in regulation. CONCLUSION The high expression of DCP1a might be associated with cancer development and prognosis. Down-regulating the expression of DCP1a will help to reduce chemotherapy resistance, which will help with further improvement of chemotherapy in gastric cancer.
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Affiliation(s)
- Tuo Ruan
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China
| | - Yazhi Zhang
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China
| | - Weizhen Liu
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China
| | - Yuan Li
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China
| | - Dianshi Wang
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China
| | - Zhouyuan Du
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China
| | - Kaixiong Tao
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China.
| | - Chuanqing Wu
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan 430022, Hubei, PR China.
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8
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Barrera A, Olguín V, Vera-Otarola J, López-Lastra M. Cap-independent translation initiation of the unspliced RNA of retroviruses. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194583. [PMID: 32450258 DOI: 10.1016/j.bbagrm.2020.194583] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/12/2020] [Accepted: 05/18/2020] [Indexed: 12/12/2022]
Abstract
Retroviruses are a unique family of RNA viruses that utilize a virally encoded reverse transcriptase (RT) to replicate their genomic RNA (gRNA) through a proviral DNA intermediate. The provirus is permanently integrated into the host cell chromosome and is expressed by the host cell transcription, RNA processing, and translation machinery. Retroviral messenger RNAs (mRNAs) entirely resemble a cellular mRNA as they have a 5'cap structure, 5'untranslated region (UTR), an open reading frame (ORF), 3'UTR, and a 3'poly(A) tail. The primary transcription product interacts with the cellular RNA processing machinery and is spliced, exported to the cytoplasm, and translated. However, a proportion of the pre-mRNA subverts typical RNA processing giving rise to the full-length RNA. In the cytoplasm, the full-length retroviral RNA fulfills a dual role acting as mRNA and as the gRNA. Simple retroviruses generate two pools of full-length RNA, one for each purpose. However, complex retroviruses have a single pool of full-length RNA, which is destined for translation or encapsidation. As for eukaryotic mRNAs, translational control of retroviral protein synthesis is mostly exerted at the step of initiation. Interestingly, some retroviral mRNAs, both simple and complex, use a dual mechanism to initiate protein synthesis, a cap-dependent initiation mechanism, or via internal initiation using an internal ribosome entry site (IRES). In this review, we describe and discuss data regarding the molecular mechanism driving the canonical cap-dependent and IRES-mediated translation initiation for retroviral mRNA, focusing the discussion mainly on the most studied retroviral mRNA, the HIV-1 mRNA.
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Affiliation(s)
- Aldo Barrera
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Valeria Olguín
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Jorge Vera-Otarola
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
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9
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Targeting the Human 80S Ribosome in Cancer: From Structure to Function and Drug Design for Innovative Adjuvant Therapeutic Strategies. Cells 2020; 9:cells9030629. [PMID: 32151059 PMCID: PMC7140421 DOI: 10.3390/cells9030629] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 12/12/2022] Open
Abstract
The human 80S ribosome is the cellular nucleoprotein nanomachine in charge of protein synthesis that is profoundly affected during cancer transformation by oncogenic proteins and provides cancerous proliferating cells with proteins and therefore biomass. Indeed, cancer is associated with an increase in ribosome biogenesis and mutations in several ribosomal proteins genes are found in ribosomopathies, which are congenital diseases that display an elevated risk of cancer. Ribosomes and their biogenesis therefore represent attractive anti-cancer targets and several strategies are being developed to identify efficient and specific drugs. Homoharringtonine (HHT) is the only direct ribosome inhibitor currently used in clinics for cancer treatments, although many classical chemotherapeutic drugs also appear to impact on protein synthesis. Here we review the role of the human ribosome as a medical target in cancer, and how functional and structural analysis combined with chemical synthesis of new inhibitors can synergize. The possible existence of oncoribosomes is also discussed. The emerging idea is that targeting the human ribosome could not only allow the interference with cancer cell addiction towards protein synthesis and possibly induce their death but may also be highly valuable to decrease the levels of oncogenic proteins that display a high turnover rate (MYC, MCL1). Cryo-electron microscopy (cryo-EM) is an advanced method that allows the visualization of human ribosome complexes with factors and bound inhibitors to improve our understanding of their functioning mechanisms mode. Cryo-EM structures could greatly assist the foundation phase of a novel drug-design strategy. One goal would be to identify new specific and active molecules targeting the ribosome in cancer such as derivatives of cycloheximide, a well-known ribosome inhibitor.
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10
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An T, Liu Y, Gourguechon S, Wang CC, Li Z. CDK Phosphorylation of Translation Initiation Factors Couples Protein Translation with Cell-Cycle Transition. Cell Rep 2019; 25:3204-3214.e5. [PMID: 30540951 PMCID: PMC6350937 DOI: 10.1016/j.celrep.2018.11.063] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/18/2018] [Accepted: 11/15/2018] [Indexed: 01/17/2023] Open
Abstract
Protein translation in eukaryotes is cell-cycle dependent, with translation rates more robust in G1 phase of the cell cycle than in mitosis. However, whether the fundamental cell-cycle control machinery directly activates protein translation during the G1/S cell-cycle transition remains unknown. Using the early divergent eukaryote Trypanosoma brucei as a model organism, we report that the G1 cyclin-dependent kinase CRK1 phosphorylates two translation initiation factors, eIF4E4 and PABP1, to promote the G1/S cell-cycle transition and global protein translation. Phosphorylation of eIF4E4 by CRK1 enhances binding to the m7G cap structure and interaction with eIF4E4 and eIF4G3, and phosphorylation of PABP1 by CRK1 promotes association with the poly(A) sequence, self-interaction, and interaction with eIF4E4. These findings demonstrate that cyclin-dependent kinase-mediated regulation of translation initiation factors couples global protein translation with the G1/S cell-cycle transition. Protein translation is cell-cycle dependent, with more robust translation rates in the G1 phase of the cell cycle than in mitosis. An et al. show that the G1 cyclin-dependent kinase CRK1 phosphorylates translation initiation factors eIF4E4 and PABP1 to couple protein translation initiation with the G1/S cell-cycle transition.
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Affiliation(s)
- Tai An
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Yi Liu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Stéphane Gourguechon
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ching C Wang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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11
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Vincent HA, Ziehr B, Lenarcic EM, Moorman NJ. Human cytomegalovirus pTRS1 stimulates cap-independent translation. Virology 2019; 537:246-253. [PMID: 31539772 PMCID: PMC8281606 DOI: 10.1016/j.virol.2019.08.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 08/28/2019] [Accepted: 08/28/2019] [Indexed: 01/08/2023]
Abstract
Human cytomegalovirus (HCMV) manipulates multiple cellular processes to facilitate virus replication, including the control of mRNA translation. We previously showed that the HCMV TRS1 protein (pTRS1) promotes cap-dependent mRNA translation independent of its ability to antagonize the antiviral protein PKR. Here we find that pTRS1 enhances internal ribosome entry site (IRES) activity using a novel circular RNA reporter that lacks an mRNA cap and poly(A) tail. Additionally, pTRS1 expression increases the activity of cellular IRESs that control the expression of proteins needed for efficient HCMV replication. We find that the ability of pTRS1 to enhance cap-independent translation is separable from its ability to antagonize PKR, but requires the pTRS1 RNA binding domain. Together these data show that pTRS1 stimulates cap-independent translation and suggest a role for pTRS1 in alternative translation initiation pathways during HCMV infection.
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Affiliation(s)
- Heather A Vincent
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Benjamin Ziehr
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Erik M Lenarcic
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Nathaniel J Moorman
- Department of Microbiology & Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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12
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Boye E, Grallert B. eIF2α phosphorylation and the regulation of translation. Curr Genet 2019; 66:293-297. [PMID: 31485739 DOI: 10.1007/s00294-019-01026-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/13/2019] [Accepted: 08/16/2019] [Indexed: 12/27/2022]
Abstract
We discuss novel insight into the role and consequences of the phosphorylation of the translation initiation factor eIF2α in the context of stress responses and cell-cycle regulation. eIF2α is centrally located to regulate translation and its phosphorylation in response to different environmental challenges is one of the best characterized stress-response pathways. In addition to its role in stress management, eIF2α phosphorylation is also linked to cell-cycle progression and memory consolidation in the nervous system. The best known consequences of eIF2α phosphorylation are downregulation of global translation and stimulation of translation of some mRNAs. However, recent evidence shows that (i) eIF2α phosphorylation is not always required for the downregulation of global translation after exposure to stress and (ii) eIF2α phosphorylation does not necessarily lead to the downregulation of global translation. These results suggest that the textbook view of eIF2α phosphorylation needs to be revised and that there must be additional regulatory mechanisms at play.
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Affiliation(s)
- Erik Boye
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
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13
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Anda S, Grallert B. Cell-Cycle-Dependent Regulation of Translation: New Interpretations of Old Observations in Light of New Approaches. Bioessays 2019; 41:e1900022. [PMID: 31210378 DOI: 10.1002/bies.201900022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/29/2019] [Indexed: 12/22/2022]
Abstract
It is a long-standing view that global translation varies during the cell cycle and is much lower in mitosis than in other cell-cycle phases. However, the central papers in the literature are not in agreement about the extent of downregulation in mitosis, ranging from a dramatic decrease to only a marginal reduction. Herein, it is argued that the discrepancy derives from technical challenges. Cell-cycle-dependent variations are most conveniently studied in synchronized cells, but the synchronization methods by themselves often evoke stress responses that, in turn, affect translation rates. Further, it is argued that previously reported cell-cycle-dependent changes in the global translation rate to a large extent reflect responses to the synchronization methods. Recent findings strongly suggest that the global translation rate is not regulated in a cell-cycle-dependent manner. Novel techniques allowing a genome-wide analysis of translational profiles suggest that the extent and importance of selective translational regulation associated with cell-cycle transitions have been underestimated. Therefore, the main question is which messenger RNAs (mRNAs) are translated, rather than whether the global translation rate is decreased.
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Affiliation(s)
- Silje Anda
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
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14
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Miettinen TP, Kang JH, Yang LF, Manalis SR. Mammalian cell growth dynamics in mitosis. eLife 2019; 8:44700. [PMID: 31063131 PMCID: PMC6534395 DOI: 10.7554/elife.44700] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 05/05/2019] [Indexed: 12/20/2022] Open
Abstract
The extent and dynamics of animal cell biomass accumulation during mitosis are unknown, primarily because growth has not been quantified with sufficient precision and temporal resolution. Using the suspended microchannel resonator and protein synthesis assays, we quantify mass accumulation and translation rates between mitotic stages on a single-cell level. For various animal cell types, growth rates in prophase are commensurate with or higher than interphase growth rates. Growth is only stopped as cells approach metaphase-to-anaphase transition and growth resumes in late cytokinesis. Mitotic arrests stop growth independently of arresting mechanism. For mouse lymphoblast cells, growth in prophase is promoted by CDK1 through increased phosphorylation of 4E-BP1 and cap-dependent protein synthesis. Inhibition of CDK1-driven mitotic translation reduces daughter cell growth. Overall, our measurements counter the traditional dogma that growth during mitosis is negligible and provide insight into antimitotic cancer chemotherapies.
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Affiliation(s)
- Teemu P Miettinen
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom.,Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Joon Ho Kang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States.,Department of Physics, Massachusetts Institute of Technology, Cambridge, United States
| | - Lucy F Yang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Scott R Manalis
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States.,Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, United States
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15
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Sabi R, Tuller T. Novel insights into gene expression regulation during meiosis revealed by translation elongation dynamics. NPJ Syst Biol Appl 2019; 5:12. [PMID: 30962948 PMCID: PMC6449359 DOI: 10.1038/s41540-019-0089-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 03/20/2019] [Indexed: 01/14/2023] Open
Abstract
The ability to dynamically control mRNA translation has a great impact on many intracellular processes. Whereas it is believed that translational control in eukaryotes occurs mainly at initiation, the condition-specific changes at the elongation level and their potential regulatory role remain unclear. Using computational approaches applied to ribosome profiling data, we show that elongation rate is dynamic and can change considerably during the yeast meiosis to facilitate the selective translation of stage-specific transcripts. We observed unique elongation changes during meiosis II, including a global inhibition of translation elongation at the onset of anaphase II accompanied by a sharp shift toward increased elongation for genes required at this meiotic stage. We also show that ribosomal proteins counteract the global decreased elongation by maintaining high initiation rates. Our findings provide new insights into gene expression regulation during meiosis and demonstrate that codon usage evolved, among others, to optimize timely translation.
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Affiliation(s)
- Renana Sabi
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
- The Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
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16
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Xie D, Zhou Y, Luo X. Amorphous silica nanoparticles induce tumorigenesis via regulating ATP5H/SOD1-related oxidative stress, oxidative phosphorylation and EIF4G2/PABPC1-associated translational initiation. PeerJ 2019; 7:e6455. [PMID: 30863671 PMCID: PMC6404658 DOI: 10.7717/peerj.6455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/16/2019] [Indexed: 12/23/2022] Open
Abstract
Background Recent studies indicate amorphous silica nanoparticles (SiNPs), one of the widely applied nanomaterials, have potential toxicity in humans and induces cell malignant transformation. However, its carcinogenic mechanisms remain poorly understood. This study’s purpose was to investigate the underlying toxic mechanisms of amorphous SiNPs on human lung epithelial cells model by using microarray data. Methods Microarray dataset GSE82062 was collected from Gene Expression Omnibus database, including three repeats of Beas-2B exposed to amorphous SiNPs for 40 passages and three repeats of passage-matched control Beas-2B cells. Differentially expressed genes (DEGs) were identified using linear models for microarray data method. Protein–protein interaction (PPI) network was constructed using data from the STRING database followed by module analysis. The miRwalk2 database was used to predict the underlying target genes of differentially miRNAs. Function enrichment analysis was performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) online tool. Results A total of 323 genes were identified as DEGs, including 280 downregulated (containing 12 pre-miRNAs) and 43 upregulated genes (containing 29 pre-miRNAs). Function enrichment indicated these genes were involved in translational initiation (i.e., eukaryotic translation initiation factor 4 gamma 2 (EIF4G2), poly (A) binding protein cytoplasmic 1 (PABPC1)), response to reactive oxygen species (i.e., superoxide dismutase 1 (SOD1)) and oxidative phosphorylation (i.e., ATP5H). PABPC1 (degree = 15), ATP5H (degree = 11) and SOD1 (degree = 8)] were proved to be hub genes after PPI-module analyses. ATP5H/SOD1 and EIF4G2/PABPC1 were overlapped with the target genes of differentially expressed pre-miR-3648/572/661 and pre-miR-4521. Conclusions Amorphous SiNPs may induce tumorigenesis via influencing ATP5H/SOD1-related oxidative stress, oxidative phosphorylation and EIF4G2/PABPC1-associated translational initiation which may be regulated by miR-3648/572/661 and miR-4521, respectively.
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Affiliation(s)
- Dongli Xie
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, China
| | - Yang Zhou
- School of Textile Science and Engineering/National Engineering Laboratory for Advanced Yarn and Clean Production, Wuhan Textile University, Wuhan, China
| | - Xiaogang Luo
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, China
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Legionella pneumophila translocated translation inhibitors are required for bacterial-induced host cell cycle arrest. Proc Natl Acad Sci U S A 2019; 116:3221-3228. [PMID: 30718423 PMCID: PMC6386690 DOI: 10.1073/pnas.1820093116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The cell cycle machinery controls diverse cellular pathways and is tightly regulated. Misregulation of cell division plays a central role in the pathogenesis of many disease processes. Various microbial pathogens interfere with the cell cycle machinery to promote host cell colonization. Although cell cycle modulation is a common theme among pathogens, the role this interference plays in promoting diseases is unclear. Previously, we demonstrated that the G1 and G2/M phases of the host cell cycle are permissive for Legionella pneumophila replication, whereas S phase provides a toxic environment for bacterial replication. In this study, we show that L. pneumophila avoids host S phase by blocking host DNA synthesis and preventing cell cycle progression into S phase. Cell cycle arrest upon Legionella contact is dependent on the Icm/Dot secretion system. In particular, we found that cell cycle arrest is dependent on the intact enzymatic activity of translocated substrates that inhibits host translation. Moreover, we show that, early in infection, the presence of these translation inhibitors is crucial to induce the degradation of the master regulator cyclin D1. Our results demonstrate that the bacterial effectors that inhibit translation are associated with preventing entry of host cells into a phase associated with restriction of L. pneumophila Furthermore, control of cyclin D1 may be a common strategy used by intracellular pathogens to manipulate the host cell cycle and promote bacterial replication.
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IMOTO Y, ABE Y, OKUMOTO K, OHNUMA M, KUROIWA H, KUROIWA T, FUJIKI Y. Dynamics of the nucleoside diphosphate kinase protein DYNAMO2 correlates with the changes in the global GTP level during the cell cycle of Cyanidioschyzon merolae. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2019; 95:75-85. [PMID: 30745504 PMCID: PMC6403433 DOI: 10.2183/pjab.95.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 12/17/2018] [Indexed: 06/09/2023]
Abstract
GTP is an essential source of energy that supports a large array of cellular mechanochemical structures ranging from protein synthesis machinery to cytoskeletal apparatus for maintaining the cell cycle. However, GTP regulation during the cell cycle has been difficult to investigate because of heterogenous levels of GTP in asynchronous cell cycles and genetic redundancy of the GTP-generating enzymes. Here, in the unicellular red algae Cyanidioschyzon merolae, we demonstrated that the ATP-GTP-converting enzyme DYNAMO2 is an essential regulator of global GTP levels during the cell cycle. The cell cycle of C. merolae can be highly synchronized by light/dark stimulations to examine GTP levels at desired time points. Importantly, the genome of C. merolae encodes only two isoforms of the ATP-GTP-converting enzyme, namely DYNAMO1 and DYNAMO2. DYNAMO1 regulates organelle divisions, whereas DYNAMO2 is entirely localized in the cytoplasm. DYNAMO2 protein levels increase during the S-M phases, and changes in GTP levels are correlated with these DYNAMO2 protein levels. These results indicate that DYNAMO2 is a potential regulator of global GTP levels during the cell cycle.
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Affiliation(s)
- Yuuta IMOTO
- Division of Organelle Homeostasis, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Yuichi ABE
- Division of Organelle Homeostasis, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Kanji OKUMOTO
- Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Mio OHNUMA
- Institute of Technology, Hiroshima College, Hiroshima, Japan
| | - Haruko KUROIWA
- Department of Chemical and Biological Science, Faculty of Science, Japan Women’s University, Tokyo, Japan
| | - Tsuneyoshi KUROIWA
- Department of Chemical and Biological Science, Faculty of Science, Japan Women’s University, Tokyo, Japan
| | - Yukio FUJIKI
- Division of Organelle Homeostasis, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
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Bowling HL, Nayak S, Deinhardt K. Proteomic Approaches to Dissect Neuronal Signalling Pathways. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1140:469-475. [PMID: 31347065 DOI: 10.1007/978-3-030-15950-4_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
With an increasing awareness of mental health issues and neurological disorders, "understanding the brain" is one of the biggest current challenges in biological research. This has been recognised by both governments and funding agencies, and it includes the need to understand connectivity of brain regions and coordinated network activity, as well as cellular and molecular mechanisms at play. In this chapter, we will describe how we have taken advantage of different proteomic techniques to unravel molecular mechanisms underlying two modulators of neuronal function: Neurotrophins and antipsychotics.
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Affiliation(s)
| | - Shruti Nayak
- Proteomics Laboratory, Alexandria Center for Life Science, NYU Langone, New York, NY, USA
| | - Katrin Deinhardt
- Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK.
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20
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Myc, Oncogenic Protein Translation, and the Role of Polyamines. Med Sci (Basel) 2018; 6:medsci6020041. [PMID: 29799508 PMCID: PMC6024823 DOI: 10.3390/medsci6020041] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/19/2018] [Accepted: 05/22/2018] [Indexed: 01/21/2023] Open
Abstract
Deregulated protein synthesis is a common feature of cancer cells, with many oncogenic signaling pathways directly augmenting protein translation to support the biomass needs of proliferating tissues. MYC’s ability to drive oncogenesis is a consequence of its essential role as a governor linking cell cycle entry with the requisite increase in protein synthetic capacity, among other biomass needs. To date, direct pharmacologic inhibition of MYC has proven difficult, but targeting oncogenic signaling modules downstream of MYC, such as the protein synthetic machinery, may provide a viable therapeutic strategy. Polyamines are essential cations found in nearly all living organisms that have both direct and indirect roles in the control of protein synthesis. Polyamine metabolism is coordinately regulated by MYC to increase polyamines in proliferative tissues, and this is further augmented in the many cancer cells harboring hyperactivated MYC. In this review, we discuss MYC-driven regulation of polyamines and protein synthetic capacity as a key function of its oncogenic output, and how this dependency may be perturbed through direct pharmacologic targeting of components of the protein synthetic machinery, such as the polyamines themselves, the eukaryotic translation initiation factor 4F (eIF4F) complex, and the eukaryotic translation initiation factor 5A (eIF5A).
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21
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ATP depletion during mitotic arrest induces mitotic slippage and APC/C Cdh1-dependent cyclin B1 degradation. Exp Mol Med 2018; 50:1-14. [PMID: 29700288 PMCID: PMC5938023 DOI: 10.1038/s12276-018-0069-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 12/18/2017] [Accepted: 01/29/2018] [Indexed: 01/08/2023] Open
Abstract
ATP depletion inhibits cell cycle progression, especially during the G1 phase and the G2 to M transition. However, the effect of ATP depletion on mitotic progression remains unclear. We observed that the reduction of ATP after prometaphase by simultaneous treatment with 2-deoxyglucose and NaN3 did not arrest mitotic progression. Interestingly, ATP depletion during nocodazole-induced prometaphase arrest resulted in mitotic slippage, as indicated by a reduction in mitotic cells, APC/C-dependent degradation of cyclin B1, increased cell attachment, and increased nuclear membrane reassembly. Additionally, cells successfully progressed through the cell cycle after mitotic slippage, as indicated by EdU incorporation and time-lapse imaging. Although degradation of cyclin B during normal mitotic progression is primarily regulated by APC/CCdc20, we observed an unexpected decrease in Cdc20 prior to degradation of cyclin B during mitotic slippage. This decrease in Cdc20 was followed by a change in the binding partner preference of APC/C from Cdc20 to Cdh1; consequently, APC/CCdh1, but not APC/CCdc20, facilitated cyclin B degradation following ATP depletion. Pulse-chase analysis revealed that ATP depletion significantly abrogated global translation, including the translation of Cdc20 and Cdh1. Additionally, the half-life of Cdh1 was much longer than that of Cdc20. These data suggest that ATP depletion during mitotic arrest induces mitotic slippage facilitated by APC/CCdh1-dependent cyclin B degradation, which follows a decrease in Cdc20 resulting from reduced global translation and the differences in the half-lives of the Cdc20 and Cdh1 proteins. An investigation into the effects of cellular energy depletion reveals a potential mechanism by which tumors evade chemotherapy. Adenosine triphosphate (ATP) is the primary energetic currency for many biological processes, and ATP depletion generally stalls the cell cycle that regulates proliferation. However, researchers led by Jae-Ho Lee of South Korea’s Ajou University School of Medicine discovered that ATP-depleted cells can sometimes bypass roadblocks in the cell division process. Before dividing, cells synthesize duplicates of every chromosome, and Lee’s team treated cells with chemotherapy agents that stall cell division by preventing separation of these duplicates. Surprisingly, subsequent ATP depletion allowed these cells to bypass this arrested state and re-enter the cell cycle, albeit with twice as much DNA as normal. Since many cancerous cells experience ATP depletion, this ‘escape hatch’ could help tumors survive treatment.
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Piserà A, Campo A, Campo S. Structure and functions of the translation initiation factor eIF4E and its role in cancer development and treatment. J Genet Genomics 2018; 45:13-24. [DOI: 10.1016/j.jgg.2018.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/22/2022]
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23
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Deforges J, de Breyne S, Ameur M, Ulryck N, Chamond N, Saaidi A, Ponty Y, Ohlmann T, Sargueil B. Two ribosome recruitment sites direct multiple translation events within HIV1 Gag open reading frame. Nucleic Acids Res 2017; 45:7382-7400. [PMID: 28449096 PMCID: PMC5499600 DOI: 10.1093/nar/gkx303] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/12/2017] [Indexed: 02/06/2023] Open
Abstract
In the late phase of the HIV virus cycle, the unspliced genomic RNA is exported to the cytoplasm for the necessary translation of the Gag and Gag-pol polyproteins. Three distinct translation initiation mechanisms ensuring Gag production have been described with little rationale for their multiplicity. The Gag-IRES has the singularity to be located within Gag ORF and to directly interact with ribosomal 40S. Aiming at elucidating the specificity and the relevance of this interaction, we probed HIV-1 Gag-IRES structure and developed an innovative integrative modelling strategy to take into account all the gathered information. We propose a novel Gag-IRES secondary structure strongly supported by all experimental data. We further demonstrate the presence of two regions within Gag-IRES that independently and directly interact with the ribosome. Importantly, these binding sites are functionally relevant to Gag translation both in vitro and ex vivo. This work provides insight into the Gag-IRES molecular mechanism and gives compelling evidence for its physiological importance. It allows us to propose original hypotheses about the IRES physiological role and conservation among primate lentiviruses.
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Affiliation(s)
- Jules Deforges
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Sylvain de Breyne
- CIRI (International Center for Infectiology Research), INSERM U1111, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5308, 46 allée d'Italie, 69364 Lyon Cedex 07, France
| | - Melissa Ameur
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Nathalie Ulryck
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Nathalie Chamond
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Afaf Saaidi
- CNRS UMR 7161, Laboratoire de Recherche en Informatique de l'Ecole Polytechnique (LIX), Ecole Polytechnique, 1 rue Estienne d'Orves, 91120 Palaiseau, France.,AMIB, Inria Saclay, bat Alan Turing, 1 rue Estienne d'Orves, 91120 Palaiseau, France
| | - Yann Ponty
- CNRS UMR 7161, Laboratoire de Recherche en Informatique de l'Ecole Polytechnique (LIX), Ecole Polytechnique, 1 rue Estienne d'Orves, 91120 Palaiseau, France.,AMIB, Inria Saclay, bat Alan Turing, 1 rue Estienne d'Orves, 91120 Palaiseau, France
| | - Theophile Ohlmann
- CIRI (International Center for Infectiology Research), INSERM U1111, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5308, 46 allée d'Italie, 69364 Lyon Cedex 07, France
| | - Bruno Sargueil
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
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Beaujois R, Ottoni E, Zhang X, Gagnon C, Hassine S, Mollet S, Viranaicken W, DesGroseillers L. The M-phase specific hyperphosphorylation of Staufen2 involved the cyclin-dependent kinase CDK1. BMC Cell Biol 2017; 18:25. [PMID: 28705199 PMCID: PMC5513041 DOI: 10.1186/s12860-017-0142-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/10/2017] [Indexed: 01/21/2023] Open
Abstract
Background Staufen2 (STAU2) is an RNA-binding protein involved in the post-transcriptional regulation of gene expression. This protein was shown to be required for organ formation and cell differentiation. Although STAU2 functions have been reported in neuronal cells, its role in dividing cells remains deeply uncharacterized. Especially, its regulation during the cell cycle is completely unknown. Results In this study, we showed that STAU2 isoforms display a mitosis-specific slow migration pattern on SDS-gels in all tested transformed and untransformed cell lines. Deeper analyses in hTert-RPE1 and HeLa cells further indicated that the slow migration pattern of STAU2 isoforms is due to phosphorylation. Time course studies showed that STAU2 phosphorylation occurs before prometaphase and terminates as cells exit mitosis. Interestingly, STAU2 isoforms were phosphorylated on several amino acid residues in the C-terminal half via the cyclin-dependent kinase 1 (Cdk1), an enzyme known to play crucial roles during mitosis. Introduction of phospho-mimetic or phospho-null mutations in STAU2 did not impair its RNA-binding capacity, its stability, its interaction with protein co-factors or its sub-cellular localization, suggesting that STAU2 phosphorylation in mitosis does not regulate these functions. Similarly, STAU2 phosphorylation is not likely to be crucial for cell cycle progression since expression of phosphorylation mutants in hTert-RPE1 cells did not impair cell proliferation. Conclusions Altogether, these results indicate that STAU2 isoforms are phosphorylated during mitosis and that the phosphorylation process involves Cdk1. The meaning of this post-translational modification is still elusive. Electronic supplementary material The online version of this article (doi:10.1186/s12860-017-0142-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rémy Beaujois
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Elizabeth Ottoni
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Xin Zhang
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Christina Gagnon
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Sami Hassine
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Stéphanie Mollet
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Wildriss Viranaicken
- Present address: UMR PIMIT, Processus Infectieux en Milieu Insulaire Tropical, Université de la Réunion, 97490 Sainte Clotilde, La Réunion, France
| | - Luc DesGroseillers
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada.
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Yang G, Yu L, Wang Y, Wang C, Gao C. The Translation Initiation Factor 1A ( TheIF1A) from Tamarix hispida Is Regulated by a Dof Transcription Factor and Increased Abiotic Stress Tolerance. FRONTIERS IN PLANT SCIENCE 2017; 8:513. [PMID: 28439284 PMCID: PMC5383729 DOI: 10.3389/fpls.2017.00513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 03/23/2017] [Indexed: 05/02/2023]
Abstract
Eukaryotic translation initiation factor 1A (eIF1A) functions as an mRNA scanner and AUG initiation codon locator. However, few studies have clarified the role of eIF1A in abiotic stress. In this study, we cloned eIF1A (TheIF1A) from Tamarix hispida and found its expression to be induced by NaCl and polyethylene glycol (PEG) in roots, stems, and leaves. Compared to control, TheIF1A root expression was increased 187.63-fold when exposed to NaCl for 6 h, suggesting a potential abiotic stress response for this gene. Furthermore, transgenic tobacco plants overexpressing TheIF1A exhibited enhanced seed germination and a higher total chlorophyll content under salt and mannitol stresses. Increased superoxide dismutase, peroxidase, glutathione transferase and glutathione peroxidase activities, as well as decreased electrolyte leakage rates and malondialdehyde contents, were observed in TheIF1A-transgenic tobacco and T. hispida seedlings under salt and mannitol stresses. Histochemical staining suggested that TheIF1A improves reactive oxygen species (ROS) scavenging in plants. Moreover, TheIF1A may regulate expression of stress-related genes, including TOBLTP, GST, MnSOD, NtMPK9, poxN1, and CDPK15. Moreover, a 1352-bp promoter fragment of TheIF1A was isolated, and cis-elements were identified. Yeast one-hybrid assays showed that ThDof can specifically bind to the Dof motif present in the promoter. In addition, ThDof showed expression patterns similar to those of TheIF1A under NaCl and PEG stresses. These findings suggest the potential mechanism and physiological roles of TheIF1A. ThDof may be an upstream regulator of TheIF1A, and TheIF1A may function as a stress response regulator to improve plant salt and osmotic stress tolerance via regulation of associated enzymes and ROS scavenging, thereby reducing cell damage under stress conditions.
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Affiliation(s)
| | | | | | | | - Caiqiu Gao
- State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry UniversityHarbin, China
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26
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Abstract
The mRNA cap structure, which is added to nascent RNA pol II transcripts, recruits the protein complexes required for pre-mRNA transcript processing, mRNA export and translation initiation. The enzymes which catalyze mRNA cap synthesis are regulated by cellular signaling pathways which impact on their expression, localization and activity. Here we discuss the recent observation that the mRNA cap methyltransferase, RNMT, is phosphorylated on Thr-77 by CDK1-cyclin B1, which regulates its activity and the proteins with which it interacts. RNMT Thr-77 phosphorylation provides a burst of mRNA cap methyltransferase activity during early G1 phase at a time when transcription is reactivated following completion of the cell cycle. This co-ordination of transcription and mRNA capping makes an important contribution to gene expression in the cell; preventing RNMT Thr-77 phosphorylation inhibits cell proliferation. Here we discuss these findings and how mRNA cap synthesis may be regulated in other scenarios.
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Affiliation(s)
- Michael Aregger
- a Centre for Gene Regulation and Expression , School of Life Sciences, University of Dundee , Dundee , UK
| | - Victoria H Cowling
- a Centre for Gene Regulation and Expression , School of Life Sciences, University of Dundee , Dundee , UK
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Wu KX, Phuektes P, Kumar P, Goh GYL, Moreau D, Chow VTK, Bard F, Chu JJH. Human genome-wide RNAi screen reveals host factors required for enterovirus 71 replication. Nat Commun 2016; 7:13150. [PMID: 27748395 PMCID: PMC5071646 DOI: 10.1038/ncomms13150] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 09/08/2016] [Indexed: 12/31/2022] Open
Abstract
Enterovirus 71 (EV71) is a neurotropic enterovirus without antivirals or vaccine, and its host-pathogen interactions remain poorly understood. Here we use a human genome-wide RNAi screen to identify 256 host factors involved in EV71 replication in human rhabdomyosarcoma cells. Enrichment analyses reveal overrepresentation in processes like mitotic cell cycle and transcriptional regulation. We have carried out orthogonal experiments to characterize the roles of selected factors involved in cell cycle regulation and endoplasmatic reticulum-associated degradation. We demonstrate nuclear egress of CDK6 in EV71 infected cells, and identify CDK6 and AURKB as resistance factors. NGLY1, which co-localizes with EV71 replication complexes at the endoplasmatic reticulum, supports EV71 replication. We confirm importance of these factors for EV71 replication in a human neuronal cell line and for coxsackievirus A16 infection. A small molecule inhibitor of NGLY1 reduces EV71 replication. This study provides a comprehensive map of EV71 host factors and reveals potential antiviral targets. Enterovirus 71 (EV71) infection causes a spectrum of symptoms including neurological disease. To improve our understanding of EV71-host interactions, Wu et al. here perform a genome-wide RNAi screen, which implicates cell cycle regulation and ER-associated degradation as important factors in EV71 replication.
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Affiliation(s)
- Kan Xing Wu
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Patchara Phuektes
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Pankaj Kumar
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore
| | - Germaine Yen Lin Goh
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore
| | - Dimitri Moreau
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore
| | - Vincent Tak Kwong Chow
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore
| | - Frederic Bard
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore
| | - Justin Jang Hann Chu
- Department of Microbiology and Immunology, National University of Singapore, Singapore 117597, Singapore.,Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore
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28
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Abstract
Progression of the Caulobacter cell cycle requires temporal and spatial control of gene expression, culminating in an asymmetric cell division yielding distinct daughter cells. To explore the contribution of translational control, RNA-seq and ribosome profiling were used to assay global transcription and translation levels of individual genes at six times over the cell cycle. Translational efficiency (TE) was used as a metric for the relative rate of protein production from each mRNA. TE profiles with similar cell cycle patterns were found across multiple clusters of genes, including those in operons or in subsets of operons. Collections of genes associated with central cell cycle functional modules (e.g., biosynthesis of stalk, flagellum, or chemotaxis machinery) have consistent but different TE temporal patterns, independent of their operon organization. Differential translation of operon-encoded genes facilitates precise cell cycle-timing for the dynamic assembly of multiprotein complexes, such as the flagellum and the stalk and the correct positioning of regulatory proteins to specific cell poles. The cell cycle-regulatory pathways that produce specific temporal TE patterns are separate from-but highly coordinated with-the transcriptional cell cycle circuitry, suggesting that the scheduling of translational regulation is organized by the same cyclical regulatory circuit that directs the transcriptional control of the Caulobacter cell cycle.
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29
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Smylla TK, Preiss A, Maier D. In vivo analysis of internal ribosome entry at the Hairless locus by genome engineering in Drosophila. Sci Rep 2016; 6:34881. [PMID: 27713501 PMCID: PMC5054391 DOI: 10.1038/srep34881] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/21/2016] [Indexed: 12/23/2022] Open
Abstract
Cell communication in metazoans requires the highly conserved Notch signaling pathway, which is subjected to strict regulation of both activation and silencing. In Drosophila melanogaster, silencing involves the assembly of a repressor complex by Hairless (H) on Notch target gene promoters. We previously found an in-frame internal ribosome entry site in the full length H transcript resulting in two H protein isoforms (Hp120 and Hp150). Hence, H may repress Notch signalling activity in situations where cap-dependent translation is inhibited. Here we demonstrate the in vivo importance of both H isoforms for proper fly development. To this end, we replaced the endogenous H locus by constructs specifically affecting translation of either Hp150 or Hp120 isoforms using genome engineering. Our findings indicate the functional relevance of both H proteins. Based on bristle phenotypes, the predominant isoform Hp150 appears to be of particular importance. In contrast, growth regulation and venation of the wing require the concomitant activity of both isoforms. Finally, the IRES dependent production of Hp120 during mitosis was verified in vivo. Together our data confirm IRES mediated translation of H protein in vivo, supporting strict regulation of Notch in different cellular settings.
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Affiliation(s)
- Thomas K Smylla
- Universität Hohenheim, Institut für Genetik (240), Garbenstr. 30, 70599 Stuttgart, Germany
| | - Anette Preiss
- Universität Hohenheim, Institut für Genetik (240), Garbenstr. 30, 70599 Stuttgart, Germany
| | - Dieter Maier
- Universität Hohenheim, Institut für Genetik (240), Garbenstr. 30, 70599 Stuttgart, Germany
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30
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Siracusa R, Paterniti I, Bruschetta G, Cordaro M, Impellizzeri D, Crupi R, Cuzzocrea S, Esposito E. The Association of Palmitoylethanolamide with Luteolin Decreases Autophagy in Spinal Cord Injury. Mol Neurobiol 2016; 53:3783-3792. [PMID: 26143261 PMCID: PMC4937098 DOI: 10.1007/s12035-015-9328-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/26/2015] [Indexed: 12/28/2022]
Abstract
Spinal cord injury (SCI) is a devastating condition of the central nervous system (CNS) often resulting in severe functional impairment and for which there are not yet restorative therapies. In the present study, we performed a widely used model of SCI to determine the neuroprotective propriety of palmitoylethanolamide (PEA) and the antioxidant effect of a flavonoid luteolin (Lut), given as a co-ultramicronized compound co-ultraPEALut. In particular, by western blot analysis and immunofluorescence staining, we investigated whether this compound (at the dose of 1 mg/kg) was able to modulate autophagy. Our results showed that treatment with co-ultraPEALut after SCI reduced the expression of proteins promoter of autophagy such as Beclin-1 and microtubule-associated protein 1A/1B-light chain 3 (MAP-LC3). In contrast, this compound decreased the levels of mammalian target of rapamycin (mTOR), p-Akt, and p-70S6K which are proteins that inhibit autophagy. These data confirmed that the protective role of co-ultraPEALut is associated with inhibition of excessive autophagy and regulation of protein degradation. Therefore, treatment with co-ultraPEALut could be considered as a possible therapeutic approach in an acute traumatic lesion like SCI.
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Affiliation(s)
- Rosalba Siracusa
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy
| | - Irene Paterniti
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy
| | - Giuseppe Bruschetta
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy
| | - Marika Cordaro
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy
| | - Daniela Impellizzeri
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy
| | - Rosalia Crupi
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy
| | - Salvatore Cuzzocrea
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, 1402 South Grand Blvd, St Louis, MO, 63104, USA
| | - Emanuela Esposito
- Department of Biological and Environmental Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres, 31, 98166, Messina, Italy.
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31
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Aregger M, Kaskar A, Varshney D, Fernandez-Sanchez ME, Inesta-Vaquera FA, Weidlich S, Cowling VH. CDK1-Cyclin B1 Activates RNMT, Coordinating mRNA Cap Methylation with G1 Phase Transcription. Mol Cell 2016; 61:734-746. [PMID: 26942677 PMCID: PMC4781437 DOI: 10.1016/j.molcel.2016.02.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 12/11/2015] [Accepted: 02/05/2016] [Indexed: 12/22/2022]
Abstract
The creation of translation-competent mRNA is dependent on RNA polymerase II transcripts being modified by addition of the 7-methylguanosine (m7G) cap. The factors that mediate splicing, nuclear export, and translation initiation are recruited to the transcript via the cap. The cap structure is formed by several activities and completed by RNMT (RNA guanine-7 methyltransferase), which catalyzes N7 methylation of the cap guanosine. We report that CDK1-cyclin B1 phosphorylates the RNMT regulatory domain on T77 during G2/M phase of the cell cycle. RNMT T77 phosphorylation activates the enzyme both directly and indirectly by inhibiting interaction with KPNA2, an RNMT inhibitor. RNMT T77 phosphorylation results in elevated m7G cap methyltransferase activity at the beginning of G1 phase, coordinating mRNA capping with the burst of transcription that occurs following nuclear envelope reformation. RNMT T77 phosphorylation is required for the production of cohort of proteins, and inhibiting T77 phosphorylation reduces the cell proliferation rate.
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Affiliation(s)
- Michael Aregger
- Centre for Gene Regulation and Expression/MRC Phosphorylation and Ubiquitylation, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Aneesa Kaskar
- Centre for Gene Regulation and Expression/MRC Phosphorylation and Ubiquitylation, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Dhaval Varshney
- Centre for Gene Regulation and Expression/MRC Phosphorylation and Ubiquitylation, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Maria Elena Fernandez-Sanchez
- Centre for Gene Regulation and Expression/MRC Phosphorylation and Ubiquitylation, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Francisco A Inesta-Vaquera
- Centre for Gene Regulation and Expression/MRC Phosphorylation and Ubiquitylation, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Simone Weidlich
- Division of Signal Transduction Therapy, University of Dundee, Dundee DD1 5EH, UK
| | - Victoria H Cowling
- Centre for Gene Regulation and Expression/MRC Phosphorylation and Ubiquitylation, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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32
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Cordaro M, Impellizzeri D, Paterniti I, Bruschetta G, Siracusa R, De Stefano D, Cuzzocrea S, Esposito E. Neuroprotective Effects of Co-UltraPEALut on Secondary Inflammatory Process and Autophagy Involved in Traumatic Brain Injury. J Neurotrauma 2016; 33:132-46. [DOI: 10.1089/neu.2014.3460] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Marika Cordaro
- Department of Biological and Environmental Sciences, University of Messina, Messina, Italy
| | - Daniela Impellizzeri
- Department of Biological and Environmental Sciences, University of Messina, Messina, Italy
| | - Irene Paterniti
- Department of Biological and Environmental Sciences, University of Messina, Messina, Italy
| | - Giuseppe Bruschetta
- Department of Biological and Environmental Sciences, University of Messina, Messina, Italy
| | - Rosalba Siracusa
- Department of Biological and Environmental Sciences, University of Messina, Messina, Italy
| | - Daniela De Stefano
- Department of Experimental Pharmacology, University of Naples Federico II, Naples, Italy
| | - Salvatore Cuzzocrea
- Department of Biological and Environmental Sciences, University of Messina, Messina, Italy
- Manchester Biomedical Research Centre, Manchester Royal Infirmary, School of Medicine, University of Manchester, Manchester, United Kingdom
| | - Emanuela Esposito
- Department of Biological and Environmental Sciences, University of Messina, Messina, Italy
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33
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Silva RC, Dautel M, Di Genova BM, Amberg DC, Castilho BA, Sattlegger E. The Gcn2 Regulator Yih1 Interacts with the Cyclin Dependent Kinase Cdc28 and Promotes Cell Cycle Progression through G2/M in Budding Yeast. PLoS One 2015; 10:e0131070. [PMID: 26176233 PMCID: PMC4503747 DOI: 10.1371/journal.pone.0131070] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Accepted: 05/28/2015] [Indexed: 12/01/2022] Open
Abstract
The Saccharomyces cerevisiae protein Yih1, when overexpressed, inhibits the eIF2 alpha kinase Gcn2 by competing for Gcn1 binding. However, deletion of YIH1 has no detectable effect on Gcn2 activity, suggesting that Yih1 is not a general inhibitor of Gcn2, and has no phenotypic defect identified so far. Thus, its physiological role is largely unknown. Here, we show that Yih1 is involved in the cell cycle. Yeast lacking Yih1 displays morphological patterns and DNA content indicative of a delay in the G2/M phases of the cell cycle, and this phenotype is independent of Gcn1 and Gcn2. Accordingly, the levels of phosphorylated eIF2α, which show a cell cycle-dependent fluctuation, are not altered in cells devoid of Yih1. We present several lines of evidence indicating that Yih1 is in a complex with Cdc28. Yih1 pulls down endogenous Cdc28 in vivo and this interaction is enhanced when Cdc28 is active, suggesting that Yih1 modulates the function of Cdc28 in specific stages of the cell cycle. We also demonstrate, by Bimolecular Fluorescence Complementation, that endogenous Yih1 and Cdc28 interact with each other, confirming Yih1 as a bona fide Cdc28 binding partner. Amino acid substitutions within helix H2 of the RWD domain of Yih1 enhance Yih1-Cdc28 association. Overexpression of this mutant, but not of wild type Yih1, leads to a phenotype similar to that of YIH1 deletion, supporting the view that Yih1 is involved through Cdc28 in the regulation of the cell cycle. We further show that IMPACT, the mammalian homologue of Yih1, interacts with CDK1, the mammalian counterpart of Cdc28, indicating that the involvement with the cell cycle is conserved. Together, these data provide insights into the cellular function of Yih1/IMPACT, and provide the basis for future studies on the role of this protein in the cell cycle.
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Affiliation(s)
- Richard C. Silva
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Martina Dautel
- Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand
| | - Bruno M. Di Genova
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - David C. Amberg
- Department of Biochemistry and Molecular Biology, Upstate Medical University, State University of New York, Syracuse, New York, United States of America
| | - Beatriz A. Castilho
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Evelyn Sattlegger
- Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand
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34
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Polymenis M, Aramayo R. Translate to divide: сontrol of the cell cycle by protein synthesis. MICROBIAL CELL 2015; 2:94-104. [PMID: 28357283 PMCID: PMC5348972 DOI: 10.15698/mic2015.04.198] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Protein synthesis underpins much of cell growth and, consequently, cell multiplication. Understanding how proliferating cells commit and progress into the cell cycle requires knowing not only which proteins need to be synthesized, but also what determines their rate of synthesis during cell division.
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Affiliation(s)
- Michael Polymenis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Rodolfo Aramayo
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
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35
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Avdulov S, Herrera J, Smith K, Peterson M, Gomez-Garcia JR, Beadnell TC, Schwertfeger KL, Benyumov AO, Manivel JC, Li S, Bielinsky AK, Yee D, Bitterman PB, Polunovsky VA. eIF4E threshold levels differ in governing normal and neoplastic expansion of mammary stem and luminal progenitor cells. Cancer Res 2014; 75:687-97. [PMID: 25524901 DOI: 10.1158/0008-5472.can-14-2571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Translation initiation factor eIF4E mediates normal cell proliferation, yet induces tumorigenesis when overexpressed. The mechanisms by which eIF4E directs such distinct biologic outputs remain unknown. We found that mouse mammary morphogenesis during pregnancy and lactation is accompanied by increased cap-binding capability of eIF4E and activation of the eIF4E-dependent translational apparatus, but only subtle oscillations in eIF4E abundance. Using a transgenic mouse model engineered so that lactogenic hormones stimulate a sustained increase in eIF4E abundance in stem/progenitor cells of lactogenic mammary epithelium during successive pregnancy/lactation cycles, eIF4E overexpression increased self-renewal, triggered DNA replication stress, and induced formation of premalignant and malignant lesions. Using complementary in vivo and ex vivo approaches, we found that increasing eIF4E levels rescued cells harboring oncogenic c-Myc or H-RasV12 from DNA replication stress and oncogene-induced replication catastrophe. Our findings indicate that distinct threshold levels of eIF4E govern its biologic output in lactating mammary glands and that eIF4E overexpression in the context of stem/progenitor cell population expansion can initiate malignant transformation by enabling cells to evade DNA damage checkpoints activated by oncogenic stimuli. Maintaining eIF4E levels below its proneoplastic threshold is an important anticancer defense in normal cells, with important implications for understanding pregnancy-associated breast cancer.
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Affiliation(s)
- Svetlana Avdulov
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Jeremy Herrera
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Karen Smith
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Mark Peterson
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | | | - Thomas C Beadnell
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota
| | - Kathryn L Schwertfeger
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Alexey O Benyumov
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - J Carlos Manivel
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota
| | - Shunan Li
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Anja-Katrin Bielinsky
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota. Departament of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Douglas Yee
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Peter B Bitterman
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota.
| | - Vitaly A Polunovsky
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota. Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota.
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36
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Djakbarova U, Marzluff WF, Köseoğlu MM. Translation regulation and proteasome mediated degradation cooperate to keep stem-loop binding protein low in G1-phase. J Cell Biochem 2014; 115:523-30. [PMID: 24122909 DOI: 10.1002/jcb.24686] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 09/26/2013] [Indexed: 12/28/2022]
Abstract
Histone mRNA levels are cell cycle regulated, and the major regulatory steps are at the posttranscriptional level. A major regulatory mechanism is S-phase restriction of Stem-loop binding protein (SLBP) which binds to the 3' end of histone mRNA and participates in multiple steps of histone mRNA metabolism, including 3' end processing, translation and regulation of mRNA stability. SLBP expression is cell cycle regulated without significant change in its mRNA level. SLBP expression is low in G1 until just before S phase where it functions and at the end of S phase SLBP is degraded by proteasome complex depending on phosphorylations on Thr60 and Thr61. Here using synchronized HeLa cells we showed that SLBP production rate is low in early G1 and recovers back to S phase level somewhere between early and mid-G1. Further, we showed that SLBP is unstable in G1 due to proteasome mediated degradation as a novel mechanism to keep SLBP low in G1. Finally, the S/G2 stable mutant form of SLBP is degraded by proteasome in G1, indicating that indicating that the SLBP degradation in G1 is independent of the previously identified SLBP degradation at S/G2. In conclusion, as a mechanism to limit histone production to S phase, SLBP is kept low in G1 phase due to cooperative action of translation regulation and proteasome mediated degradation which is independent of previously known S/G2 degradation.
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Affiliation(s)
- Umidahan Djakbarova
- Department of Genetics and Bioengineering, Fatih University Istanbul, Istanbul, Turkey; Bionanotechnology Center, Fatih University Istanbul, Istanbul, Turkey
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37
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Bitterman PB, Polunovsky VA. eIF4E-mediated translational control of cancer incidence. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:774-80. [PMID: 25263391 DOI: 10.1016/j.bbagrm.2014.09.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 09/03/2014] [Accepted: 09/10/2014] [Indexed: 11/16/2022]
Abstract
Mitogen activated translation initiation factor eIF4E mediates normal cell proliferation, yet induces tumorigenesis when deregulated and overexpressed. It remains unknown, how activated eIF4E directs such distinct biological outputs. Our experimental data provide evidence that distinct threshold levels of eIF4E govern its biological output in lactating mammary glands and that eIF4E overexpression in the context of cell population expansion can initiate malignant transformation by enabling cells to evade DNA damage checkpoints caused by hyperproliferative oncogenic stimuli. These findings point at the cellular level of eIF4E as an important sensor for normal or pro-neoplastic propagation of cells. Here, we describe a model that links the pro-neoplastic function of eIF4F to its ability to disable oncogene-activated tumor surveillance programs; and propose a novel therapeutic strategy for cancer prevention based upon targeting aberrant eIF4E with safe doses of small-molecule antagonists to ensure the maintenance of eIF4E levels below the pro-neoplastic threshold. This article is part of a Special Issue entitled: Translation and Cancer.
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Affiliation(s)
- Peter B Bitterman
- Department of Medicine, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA.
| | - Vitaly A Polunovsky
- Department of Medicine, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, 420 Delaware Street S.E., MMC 276, Minneapolis, MN 55455, USA.
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38
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Long-term in vivo imaging of translated RNAs for gene therapy. Gene Ther 2014; 21:434-9. [DOI: 10.1038/gt.2013.89] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 11/27/2013] [Accepted: 12/19/2013] [Indexed: 01/13/2023]
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39
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Bowling HL, Deinhardt K. Proteomic approaches to dissect neuronal signaling pathways. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 806:499-508. [PMID: 24952199 DOI: 10.1007/978-3-319-06068-2_24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
With an increasing awareness of mental health issues and neurological disorders, "understanding the brain" is one of the biggest current challenges in biological research. This has been recognized by both governments and funding agencies, and includes the need to understand connectivity of brain regions and coordinated network activity, as well as cellular and molecular mechanisms at play. In this chapter, we will describe how we have taken advantage of different proteomic techniques to unravel molecular mechanisms underlying two modulators of neuronal function: Neurotrophins and antipsychotics.
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Affiliation(s)
- Heather L Bowling
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA,
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40
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Cuyàs E, Corominas-Faja B, Joven J, Menendez JA. Cell cycle regulation by the nutrient-sensing mammalian target of rapamycin (mTOR) pathway. Methods Mol Biol 2014; 1170:113-44. [PMID: 24906312 DOI: 10.1007/978-1-4939-0888-2_7] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell division involves a series of ordered and controlled events that lead to cell proliferation. Cell cycle progression implies not only demanding amounts of cell mass, protein, lipid, and nucleic acid content but also a favorable energy state. The mammalian target of rapamycin (mTOR), in response to the energy state, nutrient status, and growth factor stimulation of cells, plays a pivotal role in the coordination of cell growth and the cell cycle. Here, we review how the nutrient-sensing mTOR-signaling cascade molecularly integrates nutritional and mitogenic/anti-apoptotic cues to accurately coordinate cell growth and cell cycle. First, we briefly outline the structure, functions, and regulation of the mTOR complexes (mTORC1 and mTORC2). Second, we concisely evaluate the best known ability of mTOR to control G1-phase progression. Third, we discuss in detail the recent evidence that indicates a new genome stability caretaker function of mTOR based on the specific ability of phosphorylated forms of several mTOR-signaling components (AMPK, raptor, TSC, mTOR, and S6K1), which spatially and temporally associate with essential mitotic regulators at the mitotic spindle and at the cytokinetic cleavage furrow.
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Affiliation(s)
- Elisabet Cuyàs
- Metabolism & Cancer Group, Translational Research Laboratory, Catalan Institute of Oncology, Girona (ICO-Girona), Hospital Dr. Josep Trueta de Girona, Ctra. França s/n, E-17007, Girona, Catalonia, Spain
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41
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Coldwell MJ, Cowan JL, Vlasak M, Mead A, Willett M, Perry LS, Morley SJ. Phosphorylation of eIF4GII and 4E-BP1 in response to nocodazole treatment: a reappraisal of translation initiation during mitosis. Cell Cycle 2013; 12:3615-28. [PMID: 24091728 DOI: 10.4161/cc.26588] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Translation mechanisms at different stages of the cell cycle have been studied for many years, resulting in the dogma that translation rates are slowed during mitosis, with cap-independent translation mechanisms favored to give expression of key regulatory proteins. However, such cell culture studies involve synchronization using harsh methods, which may in themselves stress cells and affect protein synthesis rates. One such commonly used chemical is the microtubule de-polymerization agent, nocodazole, which arrests cells in mitosis and has been used to demonstrate that translation rates are strongly reduced (down to 30% of that of asynchronous cells). Using synchronized HeLa cells released from a double thymidine block (G 1/S boundary) or the Cdk1 inhibitor, RO3306 (G 2/M boundary), we have systematically re-addressed this dogma. Using FACS analysis and pulse labeling of proteins with labeled methionine, we now show that translation rates do not slow as cells enter mitosis. This study is complemented by studies employing confocal microscopy, which show enrichment of translation initiation factors at the microtubule organizing centers, mitotic spindle, and midbody structure during the final steps of cytokinesis, suggesting that translation is maintained during mitosis. Furthermore, we show that inhibition of translation in response to extended times of exposure to nocodazole reflects increased eIF2α phosphorylation, disaggregation of polysomes, and hyperphosphorylation of selected initiation factors, including novel Cdk1-dependent N-terminal phosphorylation of eIF4GII. Our work suggests that effects on translation in nocodazole-arrested cells might be related to those of the treatment used to synchronize cells rather than cell cycle status.
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Affiliation(s)
- Mark J Coldwell
- Centre for Biological Sciences; University of Southampton; Southampton, UK
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42
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Nobs L, Nestel S, Kulik A, Nitsch C, Atanasoski S. Cyclin D1 is required for proliferation of Olig2-expressing progenitor cells in the injured cerebral cortex. Glia 2013; 61:1443-55. [PMID: 23839966 DOI: 10.1002/glia.22533] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 04/10/2013] [Accepted: 05/07/2013] [Indexed: 01/13/2023]
Abstract
Little is known about the molecular mechanisms driving proliferation of glial cells after an insult to the central nervous system (CNS). To test the hypothesis that the G1 regulator cyclin D1 is critical for injury-induced cell division of glial cells, we applied an injury model that causes brain damage within a well-defined region. For this, we injected the neurotoxin ibotenic acid into the prefrontal cortex of adult mice, which leads to a local nerve cell loss but does not affect the survival of glial cells. Here, we show that cyclin D1 immunoreativity increases drastically after neurotoxin injection. We find that the cyclin D1-immunopositive (cyclin D1+) cell population within the lesioned area consists to a large extent of Olig2+ oligodendrocyte progenitor cells. Analysis of cyclin D1-deficient mice demonstrates that the proliferation rate of Olig2+ cells diminishes upon loss of cyclin D1. Further, we show that cyclin-dependent kinase (cdk) 4, but not cdk6 or cdk2, is essential for driving cell division of Olig2-expressing cells in our injury model. These data suggest that distinct cell cycle proteins regulate proliferation of Olig2+ progenitor cells following a CNS insult.
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Affiliation(s)
- Lionel Nobs
- Institute of Physiology, Department of Biomedicine, University of Basel, Basel, Switzerland
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The translational factor eIF3f: the ambivalent eIF3 subunit. Cell Mol Life Sci 2013; 70:3603-16. [PMID: 23354061 PMCID: PMC3771369 DOI: 10.1007/s00018-013-1263-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/18/2012] [Accepted: 01/07/2013] [Indexed: 11/15/2022]
Abstract
The regulation of the protein synthesis has a crucial role in governing the eukaryotic cell growth. Subtle changes of proteins involved in the translation process may alter the rate of the protein synthesis and modify the cell fate by shifting the balance from normal status into a tumoral or apoptotic one. The largest eukaryotic initiation factor involved in translation regulation is eIF3. Amongst the 13 factors constituting eIF3, the f subunit finely regulates this balance in a cell-type-specific manner. Loss of this factor causes malignancy in several cells, and atrophy in normal muscle cells. The intracellular interacting partners which influence its physiological significance in both cancer and muscle cells are detailed in this review. By delineating the global interaction network of this factor and by clarifying its intracellular role, it becomes apparent that the f subunit represents a promising candidate molecule to use for biotherapeutic applications.
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Aizer A, Kafri P, Kalo A, Shav-Tal Y. The P body protein Dcp1a is hyper-phosphorylated during mitosis. PLoS One 2013; 8:e49783. [PMID: 23300942 PMCID: PMC3534667 DOI: 10.1371/journal.pone.0049783] [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: 06/13/2012] [Accepted: 10/15/2012] [Indexed: 01/18/2023] Open
Abstract
Processing bodies (PBs) are non-membranous cytoplasmic structures found in all eukaryotes. Many of their components such as the Dcp1 and Dcp2 proteins are highly conserved. Using live-cell imaging we found that PB structures disassembled as cells prepared for cell division, and then began to reassemble during the late stages of cytokinesis. During the cell cycle and as cells passed through S phase, PB numbers increased. However, there was no memory of PB numbers between mother and daughter cells. Examination of hDcp1a and hDcp1b proteins by electrophoresis in mitotic cell extracts showed a pronounced slower migrating band, which was caused by hyper-phosphorylation of the protein. We found that hDcp1a is a phospho-protein during interphase that becomes hyper-phosphorylated in mitotic cells. Using truncations of hDcp1a we localized the region important for hyper-phosphorylation to the center of the protein. Mutational analysis demonstrated the importance of serine 315 in the hyper-phosphorylation process, while other serine residues tested had a minor affect. Live-cell imaging demonstrated that serine mutations in other regions of the protein affected the dynamics of hDcp1a association with the PB structure. Our work demonstrates the control of PB dynamics during the cell cycle via phosphorylation.
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Affiliation(s)
- Adva Aizer
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, Israel
| | - Pinhas Kafri
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, Israel
| | - Alon Kalo
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, Israel
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, Israel
- * E-mail:
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45
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Phosphorylation of eukaryotic elongation factor 2 (eEF2) by cyclin A-cyclin-dependent kinase 2 regulates its inhibition by eEF2 kinase. Mol Cell Biol 2012. [PMID: 23184662 DOI: 10.1128/mcb.01270-12] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Protein synthesis is highly regulated via both initiation and elongation. One mechanism that inhibits elongation is phosphorylation of eukaryotic elongation factor 2 (eEF2) on threonine 56 (T56) by eEF2 kinase (eEF2K). T56 phosphorylation inactivates eEF2 and is the only known normal eEF2 functional modification. In contrast, eEF2K undergoes extensive regulatory phosphorylations that allow diverse pathways to impact elongation. We describe a new mode of eEF2 regulation and show that its phosphorylation by cyclin A-cyclin-dependent kinase 2 (CDK2) on a novel site, serine 595 (S595), directly regulates T56 phosphorylation by eEF2K. S595 phosphorylation varies during the cell cycle and is required for efficient T56 phosphorylation in vivo. Importantly, S595 phosphorylation by cyclin A-CDK2 directly stimulates eEF2 T56 phosphorylation by eEF2K in vitro, and we suggest that S595 phosphorylation facilitates T56 phosphorylation by recruiting eEF2K to eEF2. S595 phosphorylation is thus the first known eEF2 modification that regulates its inhibition by eEF2K and provides a novel mechanism linking the cell cycle machinery to translational control. Because all known eEF2 regulation is exerted via eEF2K, S595 phosphorylation may globally couple the cell cycle machinery to regulatory pathways that impact eEF2K activity.
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46
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Kiburu IN, LaRonde-LeBlanc N. Interaction of Rio1 kinase with toyocamycin reveals a conformational switch that controls oligomeric state and catalytic activity. PLoS One 2012; 7:e37371. [PMID: 22629386 PMCID: PMC3358306 DOI: 10.1371/journal.pone.0037371] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 04/19/2012] [Indexed: 01/07/2023] Open
Abstract
Rio1 kinase is an essential ribosome-processing factor required for proper maturation of 40 S ribosomal subunit. Although its structure is known, several questions regarding its functional remain to be addressed. We report that both Archaeoglobus fulgidus and human Rio1 bind more tightly to an adenosine analog, toyocamycin, than to ATP. Toyocamycin has antibiotic, antiviral and cytotoxic properties, and is known to inhibit ribosome biogenesis, specifically the maturation of 40 S. We determined the X-ray crystal structure of toyocamycin bound to Rio1 at 2.0 Å and demonstrated that toyocamycin binds in the ATP binding pocket of the protein. Despite this, measured steady state kinetics were inconsistent with strict competitive inhibition by toyocamycin. In analyzing this interaction, we discovered that Rio1 is capable of accessing multiple distinct oligomeric states and that toyocamycin may inhibit Rio1 by stabilizing a less catalytically active oligomer. We also present evidence of substrate inhibition by high concentrations of ATP for both archaeal and human Rio1. Oligomeric state studies show both proteins access a higher order oligomeric state in the presence of ATP. The study revealed that autophosphorylation by Rio1 reduces oligomer formation and promotes monomerization, resulting in the most active species. Taken together, these results suggest the activity of Rio1 may be modulated by regulating its oligomerization properties in a conserved mechanism, identifies the first ribosome processing target of toyocamycin and presents the first small molecule inhibitor of Rio1 kinase activity.
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Affiliation(s)
- Irene N. Kiburu
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, and the University of Maryland Marlene and Stewart Greenebaum Cancer Center, University of Maryland, College Park, Maryland, United States of America
| | - Nicole LaRonde-LeBlanc
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, and the University of Maryland Marlene and Stewart Greenebaum Cancer Center, University of Maryland, College Park, Maryland, United States of America
- * E-mail:
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Martineau Y, Azar R, Bousquet C, Pyronnet S. Anti-oncogenic potential of the eIF4E-binding proteins. Oncogene 2012; 32:671-7. [DOI: 10.1038/onc.2012.116] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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48
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Rannou Y, Salaun P, Benaud C, Khan J, Dutertre S, Giet R, Prigent C. MNK1 kinase activity is required for abscission. J Cell Sci 2012; 125:2844-52. [PMID: 22454512 DOI: 10.1242/jcs.058081] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MNK1 is a serine/threonine kinase identified as a target for MAP kinase pathways. Using chemical drug, kinase-dead expression or knockdown by RNA interference, we show that inhibition of MNK1 induces the formation of multinucleated cells, which can be rescued by expressing a form of MNK1 that is resistant to RNA interference. We found that the active human form of MNK1 localises to centrosomes, spindle microtubules and the midbody. Time-lapse recording of MNK1-depleted cells displays cytokinesis defects, as daughter cells fuse back together. When MNK1 activity was inhibited, no microtubule defect at the midbody was detected, however, anchorage of the membrane vesicle at the midbody was impaired as lumenal GFP-positive vesicles did not accumulate at the midbody. At the molecular level, we found that centriolin localisation was impaired at the midbody in MNK1-depleted cells. As a consequence, endobrevin - a v-SNARE protein implicated in the abscission step - was not properly localised to the midbody. Altogether, our data show that MNK1 activity is required for abscission.
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Affiliation(s)
- Yoann Rannou
- CNRS UMR 6290, IGDR, Rennes, CS34317, 35043 Rennes, France
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Sharma A, Yilmaz A, Marsh K, Cochrane A, Boris-Lawrie K. Thriving under stress: selective translation of HIV-1 structural protein mRNA during Vpr-mediated impairment of eIF4E translation activity. PLoS Pathog 2012; 8:e1002612. [PMID: 22457629 PMCID: PMC3310836 DOI: 10.1371/journal.ppat.1002612] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 02/14/2012] [Indexed: 12/23/2022] Open
Abstract
Translation is a regulated process and is pivotal to proper cell growth and homeostasis. All retroviruses rely on the host translational machinery for viral protein synthesis and thus may be susceptible to its perturbation in response to stress, co-infection, and/or cell cycle arrest. HIV-1 infection arrests the cell cycle in the G2/M phase, potentially disrupting the regulation of host cell translation. In this study, we present evidence that HIV-1 infection downregulates translation in lymphocytes, attributable to the cell cycle arrest induced by the HIV-1 accessory protein Vpr. The molecular basis of the translation suppression is reduced accumulation of the active form of the translation initiation factor 4E (eIF4E). However, synthesis of viral structural proteins is sustained despite the general suppression of protein production. HIV-1 mRNA translation is sustained due to the distinct composition of the HIV-1 ribonucleoprotein complexes. RNA-coimmunoprecipitation assays determined that the HIV-1 unspliced and singly spliced transcripts are predominantly associated with nuclear cap binding protein 80 (CBP80) in contrast to completely-spliced viral and cellular mRNAs that are associated with eIF4E. The active translation of the nuclear cap binding complex (CBC)-bound viral mRNAs is demonstrated by ribosomal RNA profile analyses. Thus, our findings have uncovered that the maintenance of CBC association is a novel mechanism used by HIV-1 to bypass downregulation of eIF4E activity and sustain viral protein synthesis. We speculate that a subset of CBP80-bound cellular mRNAs contribute to recovery from significant cellular stress, including human retrovirus infection. Retroviruses are intracellular parasites that utilize the host translation machinery to catalyze viral protein synthesis. The activity of the translation machinery fluctuates during cell cycle progression and is reduced in the G2/M phase. HIV-1 infection causes the cells to arrest in the G2/M phase, which has the potential to alter the activity of the translation machinery. Herein several lines of evidence demonstrated that lymphocyte mRNA translation is suppressed by the action of HIV-1 accessory protein Vpr. The molecular basis of translation suppression is reduced activity of the rate-limiting translation intitation factor, eIF4E. However, synthesis of the viral structural proteins is sustained and is due to the difference in composition of the viral and cellular mRNA-ribonucleoprotein complexes. Both cellular and completely spliced viral mRNAs are predominantly associated with the cytoplasmic cap binding protein, eIF4E. In contrast, unspliced HIV-1 mRNAs are predominantly associated with the components of the nuclear cap binding complex (CBC). The retention of CBC on the viral mRNAs provides a mechanism to sustain viral protein synthesis. This newly characterized interface of the virus-host-protein synthesis machinery is likely a cellular adaptation used to enable synthesis of proteins that reengage the cell cycle and facilitate recovery from stress.
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Affiliation(s)
- Amit Sharma
- Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, United States of America
- Center for Retrovirus Research, Ohio State University, Columbus, Ohio, United States of America
- Center for RNA Biology, Ohio State University, Columbus, Ohio, United States of America
- Comprehensive Cancer Center, Ohio State University, Columbus, Ohio, United States of America
| | - Alper Yilmaz
- Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, United States of America
- Center for Retrovirus Research, Ohio State University, Columbus, Ohio, United States of America
- Center for RNA Biology, Ohio State University, Columbus, Ohio, United States of America
- Comprehensive Cancer Center, Ohio State University, Columbus, Ohio, United States of America
| | - Kim Marsh
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Alan Cochrane
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Kathleen Boris-Lawrie
- Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, United States of America
- Center for Retrovirus Research, Ohio State University, Columbus, Ohio, United States of America
- Center for RNA Biology, Ohio State University, Columbus, Ohio, United States of America
- Comprehensive Cancer Center, Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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50
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Bitterman PB, Polunovsky VA. Translational control of cell fate: from integration of environmental signals to breaching anticancer defense. Cell Cycle 2012; 11:1097-107. [PMID: 22356766 DOI: 10.4161/cc.11.6.19610] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Despite their genetic diversity, different cancers manifest common features at the protein pathway level. They share a core group of perturbed pathways that converge upon a few regulatory hubs linking the cellular signaling network with the basic metabolic machinery. Available evidence indicates that one such hub is the eIF4F-mediated cap-dependent mRNA translation initiation apparatus, whose integrity is required for physiological control of growth, proliferation and viability. However, when hyperactivated by upstream oncogenic signaling, eIF4F selectively stimulates the translation of a group of mRNAs required for cancer genesis and progression. Here, we describe a model that links the pro-neoplastic function of eIF4F to its ability to disable oncogene-activated tumor surveillance programs and propose a novel therapeutic strategy for cancer based upon targeting aberrant eIF4F with small-molecule antagonists.
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Affiliation(s)
- Peter B Bitterman
- Department of Medicine and Masonic Cancer Center, University of Minnesota; Minneapolis, MN, USA
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