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Fijalkowska D, Verbruggen S, Ndah E, Jonckheere V, Menschaert G, Van Damme P. eIF1 modulates the recognition of suboptimal translation initiation sites and steers gene expression via uORFs. Nucleic Acids Res 2017; 45:7997-8013. [PMID: 28541577 PMCID: PMC5570006 DOI: 10.1093/nar/gkx469] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 05/11/2017] [Indexed: 12/25/2022] Open
Abstract
Alternative translation initiation mechanisms such as leaky scanning and reinitiation potentiate the polycistronic nature of human transcripts. By allowing for reprogrammed translation, these mechanisms can mediate biological responses to stimuli. We combined proteomics with ribosome profiling and mRNA sequencing to identify the biological targets of translation control triggered by the eukaryotic translation initiation factor 1 (eIF1), a protein implicated in the stringency of start codon selection. We quantified expression changes of over 4000 proteins and 10 000 actively translated transcripts, leading to the identification of 245 transcripts undergoing translational control mediated by upstream open reading frames (uORFs) upon eIF1 deprivation. Here, the stringency of start codon selection and preference for an optimal nucleotide context were largely diminished leading to translational upregulation of uORFs with suboptimal start. Interestingly, genes affected by eIF1 deprivation were implicated in energy production and sensing of metabolic stress.
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Affiliation(s)
- Daria Fijalkowska
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
| | - Steven Verbruggen
- Lab of Bioinformatics and Computational Genomics, Department of Mathematical Modelling, Statistics and Bioinformatics, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
| | - Elvis Ndah
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium.,Lab of Bioinformatics and Computational Genomics, Department of Mathematical Modelling, Statistics and Bioinformatics, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
| | - Veronique Jonckheere
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
| | - Gerben Menschaert
- Lab of Bioinformatics and Computational Genomics, Department of Mathematical Modelling, Statistics and Bioinformatics, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
| | - Petra Van Damme
- VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
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Abstract
A large body of evidence indicates that genome annotation pipelines have biased our view of coding sequences because they generally undersample small proteins and peptides. The recent development of genome-wide translation profiling reveals the prevalence of small/short open reading frames (smORFs or sORFs), which are scattered over all classes of transcripts, including both mRNAs and presumptive long noncoding RNAs. Proteomic approaches further confirm an unexpected variety of smORF-encoded peptides (SEPs), representing an overlooked reservoir of bioactive molecules. Indeed, functional studies in a broad range of species from yeast to humans demonstrate that SEPs can harbor key activities for the control of development, differentiation, and physiology. Here we summarize recent advances in the discovery and functional characterization of smORF/SEPs and discuss why these small players can no longer be ignored with regard to genome function.
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Affiliation(s)
- Serge Plaza
- Laboratoire de Recherches en Sciences Végétales, Université de Toulouse, Université Paul Sabatier, 31326 Castanet Tolosan, France; .,CNRS, UMR5546, Laboratoire de Recherches en Sciences Végétales, 31326 Castanet Tolosan, France
| | - Gerben Menschaert
- Department of Mathematical Modeling, Statistics and Bioinformatics, University of Ghent, 9000 Gent, Belgium
| | - François Payre
- Centre de Biologie du Développement, Centre de Biologie Intégrative, Université de Toulouse, CNRS, Université Paul Sabatier, 31062 Toulouse, France;
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C/EBPα deregulation as a paradigm for leukemogenesis. Leukemia 2017; 31:2279-2285. [PMID: 28720765 DOI: 10.1038/leu.2017.229] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/19/2017] [Accepted: 06/27/2017] [Indexed: 12/21/2022]
Abstract
Myeloid master regulator CCAAT enhancer-binding protein alpha (C/EBPα) is deregulated by multiple mechanisms in leukemia. Inhibition of C/EBPα function plays pivotal roles in leukemogenesis. While much is known about how C/EBPα orchestrates granulopoiesis, our understanding of molecular transformation events, the role(s) of cooperating mutations and clonal evolution during C/EBPα deregulation in leukemia remains elusive. In this review, we will summarize the latest research addressing these topics with special emphasis on CEBPA mutations. We conclude by describing emerging therapeutic strategies to restore C/EBPα function.
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Translation Initiation from Conserved Non-AUG Codons Provides Additional Layers of Regulation and Coding Capacity. mBio 2017; 8:mBio.00844-17. [PMID: 28655822 PMCID: PMC5487733 DOI: 10.1128/mbio.00844-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Neurospora crassa cpc-1 and Saccharomyces cerevisiae GCN4 are homologs specifying transcription activators that drive the transcriptional response to amino acid limitation. The cpc-1 mRNA contains two upstream open reading frames (uORFs) in its >700-nucleotide (nt) 5′ leader, and its expression is controlled at the level of translation in response to amino acid starvation. We used N. crassa cell extracts and obtained data indicating that cpc-1 uORF1 and uORF2 are functionally analogous to GCN4 uORF1 and uORF4, respectively, in controlling translation. We also found that the 5′ region upstream of the main coding sequence of the cpc-1 mRNA extends for more than 700 nucleotides without any in-frame stop codon. For 100 cpc-1 homologs from Pezizomycotina and from selected Basidiomycota, 5′ conserved extensions of the CPC1 reading frame are also observed. Multiple non-AUG near-cognate codons (NCCs) in the CPC1 reading frame upstream of uORF2, some deeply conserved, could potentially initiate translation. At least four NCCs initiated translation in vitro. In vivo data were consistent with initiation at NCCs to produce N-terminally extended N. crassa CPC1 isoforms. The pivotal role played by CPC1, combined with its translational regulation by uORFs and NCC utilization, underscores the emerging significance of noncanonical initiation events in controlling gene expression. There is a deepening and widening appreciation of the diverse roles of translation in controlling gene expression. A central fungal transcription factor, the best-studied example of which is Saccharomyces cerevisiae GCN4, is crucial for the response to amino acid limitation. Two upstream open reading frames (uORFs) in the GCN4 mRNA are critical for controlling GCN4 synthesis. We observed that two uORFs in the corresponding Neurospora crassa cpc-1 mRNA appear functionally analogous to the GCN4 uORFs. We also discovered that, surprisingly, unlike GCN4, the CPC1 coding sequence extends far upstream from the presumed AUG start codon with no other in-frame AUG codons. Similar extensions were seen in homologs from many filamentous fungi. We observed that multiple non-AUG near-cognate codons (NCCs) in this extended reading frame, some conserved, initiated translation to produce longer forms of CPC1, underscoring the significance of noncanonical initiation in controlling gene expression.
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55
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Collier AE, Wek RC, Spandau DF. Human Keratinocyte Differentiation Requires Translational Control by the eIF2α Kinase GCN2. J Invest Dermatol 2017; 137:1924-1934. [PMID: 28528168 DOI: 10.1016/j.jid.2017.04.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/29/2017] [Accepted: 04/26/2017] [Indexed: 10/19/2022]
Abstract
Appropriate and sequential differentiation of keratinocytes is essential for all functions of the human epidermis. Although transcriptional regulation has proven to be important for keratinocyte differentiation, little is known about the role of translational control. A key mechanism for modulating translation is through phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2). A family of different eIF2α kinases function in the integrative stress response to inhibit general protein synthesis coincident with preferential translation of select mRNAs that participate in stress alleviation. Here we demonstrate that translational control through eIF2α phosphorylation is required for normal keratinocyte differentiation. Analyses of polysome profiles revealed that key differentiation genes, including involucrin, are bound to heavy polysomes during differentiation, despite decreased general protein synthesis. Induced eIF2α phosphorylation by the general control nonderepressible 2 (GCN2) protein kinase facilitated translational control and differentiation-specific protein expression during keratinocyte differentiation. Furthermore, loss of GCN2 thwarted translational control, normal epidermal differentiation, and differentiation gene expression in organotypic skin culture. These findings underscore a previously unknown function for GCN2 phosphorylation of eIF2α and translational control in the formation of an intact human epidermis.
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Affiliation(s)
- Ann E Collier
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ronald C Wek
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| | - Dan F Spandau
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
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A tumor suppressor role for C/EBPα in solid tumors: more than fat and blood. Oncogene 2017; 36:5221-5230. [PMID: 28504718 DOI: 10.1038/onc.2017.151] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/29/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022]
Abstract
The transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα) plays a critical role during embryogenesis and is thereafter required for homeostatic glucose metabolism, adipogenesis and myeloid development. Its ability to regulate the expression of lineage-specific genes and induce growth arrest contributes to the terminal differentiation of several cell types, including hepatocytes, adipocytes and granulocytes. CEBPA loss of-function mutations contribute to the development of ~10% of acute myeloid leukemia (AML), stablishing a tumor suppressor role for C/EBPα. Deregulation of C/EBPα expression has also been reported in a variety of additional human neoplasias, including liver, breast and lung cancer. However, functional CEBPA mutations have not been found in solid tumors, suggesting that abrogation of C/EBPα function in non-hematopoietic tissues is regulated by alternative mechanisms. Here we review the function of C/EBPα in solid tumors and focus on the molecular mechanisms underlying its tumor suppressive role.
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Falkenberg KD, Jakobs A, Matern JC, Dörner W, Uttarkar S, Trentmann A, Steinmann S, Coulibaly A, Schomburg C, Mootz HD, Schmidt TJ, Klempnauer KH. Withaferin A, a natural compound with anti-tumor activity, is a potent inhibitor of transcription factor C/EBPβ. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1349-1358. [PMID: 28476645 DOI: 10.1016/j.bbamcr.2017.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 04/27/2017] [Accepted: 05/01/2017] [Indexed: 02/07/2023]
Abstract
Recent work has shown that deregulation of the transcription factor Myb contributes to the development of leukemia and several other human cancers, making Myb and its cooperation partners attractive targets for drug development. By employing a myeloid Myb-reporter cell line we have identified Withaferin A (WFA), a natural compound that exhibits anti-tumor activities, as an inhibitor of Myb-dependent transcription. Analysis of the inhibitory mechanism of WFA showed that WFA is a significantly more potent inhibitor of C/EBPβ, a transcription factor cooperating with Myb in myeloid cells, than of Myb itself. We show that WFA covalently modifies specific cysteine residues of C/EBPβ, resulting in the disruption of the interaction of C/EBPβ with the co-activator p300. Our work identifies C/EBPβ as a novel direct target of WFA and highlights the role of p300 as a crucial co-activator of C/EBPβ. The finding that WFA is a potent inhibitor of C/EBPβ suggests that inhibition of C/EBPβ might contribute to the biological activities of WFA.
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Affiliation(s)
- Kim D Falkenberg
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Anke Jakobs
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Julian C Matern
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Wolfgang Dörner
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Sagar Uttarkar
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Amke Trentmann
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Simone Steinmann
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Anna Coulibaly
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Caroline Schomburg
- Institute for Pharmaceutical Biology and Phytochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Henning D Mootz
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Thomas J Schmidt
- Institute for Pharmaceutical Biology and Phytochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany
| | - Karl-Heinz Klempnauer
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149 Münster, Germany.
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58
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Woo MY, Yun SJ, Lee MJ, Kim K, Lee ES, Park S. Transcription Factors Regulating Inflammatory Cytokine Production Are Differentially Expressed in Peripheral Blood Mononuclear Cells of Behçet Disease Depending on Disease Activity. Ann Dermatol 2017; 29:173-179. [PMID: 28392644 PMCID: PMC5383742 DOI: 10.5021/ad.2017.29.2.173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/10/2016] [Accepted: 07/13/2016] [Indexed: 11/26/2022] Open
Abstract
Background Behçet disease (BD) is a relapsing inflammatory disease with increased production of inflammatory cytokines in peripheral blood mononuclear cells (PBMCs); however, the underlying molecular mechanisms are not well known. Objective To analyze whether the differential expression of transcription factors is involved in the increased tumor necrosis factor (TNF)-α and interleukin (IL)-6 production by PBMCs of BD patients compared to healthy controls (HCs). Methods Expression of transcription factors was examined by real-time reverse transcriptase-polymerase chain reaction and western blotting. Cytokine production by CD11b+ cells transfected with siRNAs against transcription factors was measured by enzyme-linked immunosorbent assay. Results In the absence of lipopolysaccharide stimulation, the transcript level of CCAAT-enhancer-binding proteins (C/EBP) β was increased in PBMCs from patients with active BD compared to that in PBMCs from patients with stable BD. The C/EBPδ transcript level was higher in PBMCs from patients with active BD than in those from HCs. The activating transcription factor 3 (ATF3) transcript level was increased in PBMCs from patients with stable BD compared to that in PBMCs from HCs. siRNAs targeting C/EBPβ and C/EBPδ significantly reduced the production of IL-6 and TNF-α in lipopolysaccharide-stimulated CD11b+ cells from patients with BD as well as from HCs. Conclusion We found differential expression of C/EBPβ, C/EBPδ, and ATF3 in PBMCs from patients with BD depending on disease activity, indicating the involvement of these molecules in BD pathogenesis.
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Affiliation(s)
- Min-Yeong Woo
- Department of Microbiology, Ajou University School of Medicine, Suwon, Korea.; Department of Biomedical Sciences, The Graduate School, Ajou University, Suwon, Korea
| | - Su Jin Yun
- Department of Microbiology, Ajou University School of Medicine, Suwon, Korea.; Department of Biomedical Sciences, The Graduate School, Ajou University, Suwon, Korea
| | - Mi Jin Lee
- Department of Microbiology, Ajou University School of Medicine, Suwon, Korea
| | - Kyongmin Kim
- Department of Microbiology, Ajou University School of Medicine, Suwon, Korea.; Department of Biomedical Sciences, The Graduate School, Ajou University, Suwon, Korea
| | - Eun-So Lee
- Department of Dermatology, Ajou University School of Medicine, Suwon, Korea
| | - Sun Park
- Department of Microbiology, Ajou University School of Medicine, Suwon, Korea.; Department of Biomedical Sciences, The Graduate School, Ajou University, Suwon, Korea
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60
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A screening strategy for the discovery of drugs that reduce C/EBPβ-LIP translation with potential calorie restriction mimetic properties. Sci Rep 2017; 7:42603. [PMID: 28198412 PMCID: PMC5309760 DOI: 10.1038/srep42603] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 01/11/2017] [Indexed: 11/09/2022] Open
Abstract
An important part of the beneficial effects of calorie restriction (CR) on healthspan and lifespan is mediated through regulation of protein synthesis that is under control of the mechanistic target of rapamycin complex 1 (mTORC1). As one of its activities, mTORC1 stimulates translation into the metabolic transcription factor CCAAT/Enhancer Binding Protein β (C/EBPβ) isoform Liver-specific Inhibitory Protein (LIP). Regulation of LIP expression strictly depends on a translation re-initiation event that requires a conserved cis-regulatory upstream open reading frame (uORF) in the C/EBPβ-mRNA. We showed before that suppression of LIP in mice, reflecting reduced mTORC1-signaling at the C/EBPβ level, results in CR-type of metabolic improvements. Hence, we aim to find possibilities to pharmacologically down-regulate LIP in order to induce CR-mimetic effects. We engineered a luciferase-based cellular reporter system that acts as a surrogate for C/EBPβ-mRNA translation, emulating uORF-dependent C/EBPβ-LIP expression under different translational conditions. By using the reporter system in a high-throughput screening (HTS) strategy we identified drugs that reduce LIP. The drug Adefovir Dipivoxil passed all counter assays and increases fatty acid β-oxidation in a hepatoma cell line in a LIP-dependent manner. Therefore, these drugs that suppress translation into LIP potentially exhibit CR-mimetic properties.
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61
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Hansberg-Pastor V, González-Arenas A, Camacho-Arroyo I. CCAAT/enhancer binding protein β negatively regulates progesterone receptor expression in human glioblastoma cells. Mol Cell Endocrinol 2017; 439:317-327. [PMID: 27663075 DOI: 10.1016/j.mce.2016.09.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/29/2016] [Accepted: 09/19/2016] [Indexed: 12/12/2022]
Abstract
Many progesterone (P4) actions are mediated by its intracellular receptor (PR), which has two isoforms (PR-A and PR-B) differentially transcribed from separate promoters of a single gene. In glioblastomas, the most frequent and aggressive brain tumors, PR-B is the predominant isoform. In an in silico analysis we showed putative CCAAT/Enhancer Binding Protein (C/EBP) binding sites at PR-B promoter. We evaluated the role of C/EBPβ in PR-B expression regulation in glioblastoma cell lines, which expressed different ratios of PR and C/EBPβ isoforms (LAP1, LAP2, and LIP). ChIP assays showed a significant basal binding of C/EBPβ, specific protein 1 (Sp1) and estrogen receptor alpha (ERα) to PR-B promoter. C/EBPβ knockdown increased PR-B expression and treatment with estradiol (E2) reduced C/EBPβ binding to the promoter and up-regulated PR-B expression. P4 induced genes were differently regulated when CEBP/β was silenced. These data show that C/EBPβ negatively regulates PR-B expression in glioblastoma cells.
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Affiliation(s)
- Valeria Hansberg-Pastor
- Facultad de Química, Departamento de Biología, Universidad Nacional Autónoma de México (UNAM), Mexico
| | - Aliesha González-Arenas
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, UNAM, Mexico
| | - Ignacio Camacho-Arroyo
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, UNAM, Ciudad de México, Mexico.
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Masuda M, Miyazaki-Anzai S, Keenan AL, Shiozaki Y, Okamura K, Chick WS, Williams K, Zhao X, Rahman SM, Tintut Y, Adams CM, Miyazaki M. Activating transcription factor-4 promotes mineralization in vascular smooth muscle cells. JCI Insight 2016; 1:e88646. [PMID: 27812542 DOI: 10.1172/jci.insight.88646] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Emerging evidence indicates that upregulation of the ER stress-induced pro-osteogenic transcription factor ATF4 plays an important role in vascular calcification, a common complication in patients with aging, diabetes, and chronic kidney disease (CKD). In this study, we demonstrated the pathophysiological role of ATF4 in vascular calcification using global Atf4 KO, smooth muscle cell-specific (SMC-specific) Atf4 KO, and transgenic (TG) mouse models. Reduced expression of ATF4 in global ATF4-haplodeficient and SMC-specific Atf4 KO mice reduced medial and atherosclerotic calcification under normal kidney and CKD conditions. In contrast, increased expression of ATF4 in SMC-specific Atf4 TG mice caused severe medial and atherosclerotic calcification. We further demonstrated that ATF4 transcriptionally upregulates the expression of type III sodium-dependent phosphate cotransporters (PiT1 and PiT2) by interacting with C/EBPβ. These results demonstrate that the ER stress effector ATF4 plays a critical role in the pathogenesis of vascular calcification through increased phosphate uptake in vascular SMCs.
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Affiliation(s)
- Masashi Masuda
- Division of Renal Diseases and Hypertension, Department of Medicine, and
| | | | - Audrey L Keenan
- Division of Renal Diseases and Hypertension, Department of Medicine, and
| | - Yuji Shiozaki
- Division of Renal Diseases and Hypertension, Department of Medicine, and
| | - Kayo Okamura
- Division of Renal Diseases and Hypertension, Department of Medicine, and
| | - Wallace S Chick
- Department of Cell and Developmental Biology, University of Colorado Denver, Aurora, Colorado, USA
| | - Kristina Williams
- Department of Cell and Developmental Biology, University of Colorado Denver, Aurora, Colorado, USA
| | - Xiaoyun Zhao
- Department of Cell and Developmental Biology, University of Colorado Denver, Aurora, Colorado, USA
| | | | - Yin Tintut
- Division of Cardiology, Department of Medicine, University of California, Los Angeles, California, USA
| | | | - Makoto Miyazaki
- Division of Renal Diseases and Hypertension, Department of Medicine, and
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Jakobs A, Steinmann S, Henrich SM, Schmidt TJ, Klempnauer KH. Helenalin Acetate, a Natural Sesquiterpene Lactone with Anti-inflammatory and Anti-cancer Activity, Disrupts the Cooperation of CCAAT Box/Enhancer-binding Protein β (C/EBPβ) and Co-activator p300. J Biol Chem 2016; 291:26098-26108. [PMID: 27803164 DOI: 10.1074/jbc.m116.748129] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 10/27/2016] [Indexed: 11/06/2022] Open
Abstract
Recent work has demonstrated pro-oncogenic functions of the transcription factor CCAAT box/enhancer-binding protein β (C/EBPβ) in various tumors, implicating C/EBPβ as an interesting target for the development of small-molecule inhibitors. We have previously discovered that the sesquiterpene lactone helenalin acetate, a natural compound known to inhibit NF-κB, is a potent C/EBPβ inhibitor. We have now examined the inhibitory mechanism of helenalin acetate in more detail. We demonstrate that helenalin acetate is a significantly more potent inhibitor of C/EBPβ than of NF-κB. Our work shows that helenalin acetate inhibits C/EBPβ by binding to the N-terminal part of C/EBPβ, thereby disrupting the cooperation of C/EBPβ with the co-activator p300. C/EBPβ is expressed in several isoforms from alternative translational start codons. We have previously demonstrated that helenalin acetate selectively inhibits only the full-length (liver-enriched activating protein* (LAP*)) isoform but not the slightly shorter (LAP) isoform. Consistent with this, helenalin acetate binds to the LAP* but not to the LAP isoform, explaining why its inhibitory activity is selective for LAP*. Although helenalin acetate contains reactive groups that are able to interact covalently with cysteine residues, as exemplified by its effect on NF-κB, the inhibition of C/EBPβ by helenalin acetate is not due to irreversible reaction with cysteine residues of C/EBPβ. In summary, helenalin acetate is the first highly active small-molecule C/EBPβ inhibitor that inhibits C/EBPβ by a direct binding mechanism. Its selectivity for the LAP* isoform also makes helenalin acetate an interesting tool to dissect the functions of the LAP* and LAP isoforms.
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Affiliation(s)
| | | | | | - Thomas J Schmidt
- the Institute for Pharmaceutical Biology and Phytochemistry, Westfälische Wilhelms-Universität, D-48149 Münster, Germany
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64
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Hernandez-Encinas E, Aguilar-Morante D, Morales-Garcia JA, Gine E, Sanz-SanCristobal M, Santos A, Perez-Castillo A. Complement component 3 (C3) expression in the hippocampus after excitotoxic injury: role of C/EBPβ. J Neuroinflammation 2016; 13:276. [PMID: 27769255 PMCID: PMC5073972 DOI: 10.1186/s12974-016-0742-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 10/04/2016] [Indexed: 02/08/2023] Open
Abstract
Background The CCAAT/enhancer-binding protein β (C/EBPβ) is a transcription factor implicated in the control of proliferation, differentiation, and inflammatory processes mainly in adipose tissue and liver; although more recent results have revealed an important role for this transcription factor in the brain. Previous studies from our laboratory indicated that CCAAT/enhancer-binding protein β is implicated in inflammatory process and brain injury, since mice lacking this gene were less susceptible to kainic acid-induced injury. More recently, we have shown that the complement component 3 gene (C3) is a downstream target of CCAAT/enhancer-binding protein β and it could be a mediator of the proinflammatory effects of this transcription factor in neural cells. Methods Adult male Wistar rats (8–12 weeks old) were used throughout the study. C/EBPβ+/+ and C/EBPβ–/– mice were generated from heterozygous breeding pairs. Animals were injected or not with kainic acid, brains removed, and brain slices containing the hippocampus analyzed for the expression of both CCAAT/enhancer-binding protein β and C3. Results In the present work, we have further extended these studies and show that CCAAT/enhancer-binding protein β and C3 co-express in the CA1 and CA3 regions of the hippocampus after an excitotoxic injury. Studies using CCAAT/enhancer-binding protein β knockout mice demonstrate a marked reduction in C3 expression after kainic acid injection in these animals, suggesting that indeed this protein is regulated by C/EBPβ in the hippocampus in vivo. Conclusions Altogether these results suggest that CCAAT/enhancer-binding protein β could regulate brain disorders, in which excitotoxic and inflammatory processes are involved, at least in part through the direct regulation of C3. Electronic supplementary material The online version of this article (doi:10.1186/s12974-016-0742-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elena Hernandez-Encinas
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Diana Aguilar-Morante
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain.,Present Address: Departamento de Fisiología Médica y Biofísica, Instituto de Biomedicina de Sevilla, IBiS, (Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla), 41013, Sevilla, Spain
| | - Jose A Morales-Garcia
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Elena Gine
- Departamento de Biología Celular, Facultad de Medicina, UCM, 28040, Madrid, Spain
| | - Marina Sanz-SanCristobal
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain
| | - Angel Santos
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain. .,Departamento de Bioquímica y Biologia Molecular, Facultad de Medicina, UCM, 28040, Madrid, Spain.
| | - Ana Perez-Castillo
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain.
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65
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Selagea L, Mishra A, Anand M, Ross J, Tucker-Burden C, Kong J, Brat DJ. EGFR and C/EBP-β oncogenic signaling is bidirectional in human glioma and varies with the C/EBP-β isoform. FASEB J 2016; 30:4098-4108. [PMID: 27572958 DOI: 10.1096/fj.201600550r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/15/2016] [Indexed: 01/06/2023]
Abstract
We investigated the intersection of epidermal growth factor receptor (EGFR) and CCAAT enhancer binding protein (C/EBP)-β signaling in glioblastoma (GBM), given that both gene products strongly influence neoplastic behavior. C/EBP-β is known to drive the mesenchymal transcriptional signature in GBM, likely through strong microenvironmental influences, whereas the genetic contributions to its up-regulation in this disease are not well described. We demonstrated that stable overexpression and activation of WT EGFR (U87MG-WT) led to elevated C/EBP-β expression, as well as enhanced nuclear translocation and DNA-binding activity, leading to up-regulation of C/EBP-β transcription and translation. Deeper investigation identified bidirectional regulation, with C/EBP-β also causing up-regulation of EGFR that was at least partially dependent on the STAT3. Based on ChIP-based studies, we also found that that the translational isoforms of C/EBP-β [liver-enriched transcription-activating protein (LAP)-1/2 and liver inhibitory protein (LIP)] have differential occupancy on STAT3 promoter and opposing roles in transcriptional regulation of STAT3 and EGFR. We further demonstrated that the shorter C/EBP-β isoform, LIP, promoted proliferation and migration of U87MG glioma cells, potentially via induction of cytokine IL-6. Our molecular dissection of EGFR and C/EBP-β pathway interactions uncovered a complex signaling network in which increased activity of either EGFR or C/EBP-β leads to the up-regulation of the other, enhancing oncogenic signaling. Disrupting the EGFR-C/EBP-β signaling axis could attenuate malignant behavior of glioblastoma.-Selagea, L., Mishra, A., Anand, M., Ross, J., Tucker-Burden, C., Kong, J., Brat, D. J. EGFR and C/EBP-β oncogenic signaling is bidirectional in human glioma and varies with the C/EBP-β isoform.
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Affiliation(s)
- Ligia Selagea
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia.,Department of Biology, Agnes Scott College, Decatur, Georgia
| | - Alok Mishra
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia
| | - Monika Anand
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia
| | - James Ross
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia.,Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, Georgia; and
| | - Carol Tucker-Burden
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia
| | - Jun Kong
- Department of Biomedical Informatics, Winship Cancer Institute, Emory University, Atlanta, Georgia
| | - Daniel J Brat
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia; .,Department of Biomedical Informatics, Winship Cancer Institute, Emory University, Atlanta, Georgia
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66
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Prolonged treatment with 3-isobutyl-1-methylxanthine improves the efficiency of differentiating 3T3-L1 cells into adipocytes. Anal Biochem 2016; 507:18-20. [DOI: 10.1016/j.ab.2016.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 04/08/2016] [Accepted: 05/10/2016] [Indexed: 01/24/2023]
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67
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Young SK, Wek RC. Upstream Open Reading Frames Differentially Regulate Gene-specific Translation in the Integrated Stress Response. J Biol Chem 2016; 291:16927-35. [PMID: 27358398 DOI: 10.1074/jbc.r116.733899] [Citation(s) in RCA: 243] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Translation regulation largely occurs during initiation, which features ribosome assembly onto mRNAs and selection of the translation start site. Short, upstream ORFs (uORFs) located in the 5'-leader of the mRNA can be selected for translation. Multiple transcripts associated with stress amelioration are preferentially translated through uORF-mediated mechanisms during activation of the integrated stress response (ISR) in which phosphorylation of the α subunit of eIF2 results in a coincident global reduction in translation initiation. This review presents key features of uORFs that serve to optimize translational control that is essential for regulation of cell fate in response to environmental stresses.
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Affiliation(s)
- Sara K Young
- From the Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5126
| | - Ronald C Wek
- From the Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5126
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68
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Stein SJ, Mack EA, Rome KS, Pajcini KV, Ohtani T, Xu L, Li Y, Meijerink JPP, Faryabi RB, Pear WS. Trib2 Suppresses Tumor Initiation in Notch-Driven T-ALL. PLoS One 2016; 11:e0155408. [PMID: 27191957 PMCID: PMC4871414 DOI: 10.1371/journal.pone.0155408] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 04/28/2016] [Indexed: 12/31/2022] Open
Abstract
Trib2 is highly expressed in human T cell acute lymphoblastic leukemia (T-ALL) and is a direct transcriptional target of the oncogenic drivers Notch and TAL1. In human TAL1-driven T-ALL cell lines, Trib2 is proposed to function as an important survival factor, but there is limited information about the role of Trib2 in primary T-ALL. In this study, we investigated the role of Trib2 in the initiation and maintenance of Notch-dependent T-ALL. Trib2 had no effect on the growth and survival of murine T-ALL cell lines in vitro when expression was blocked by shRNAs. To test the function of Trib2 on leukemogenesis in vivo, we generated Trib2 knockout mice. Mice were born at the expected Mendelian frequencies without gross developmental anomalies. Adult mice did not develop pathology or shortened survival, and hematopoiesis, including T cell development, was unperturbed. Using a retroviral model of Notch-induced T-ALL, deletion of Trib2 unexpectedly decreased the latency and increased the penetrance of T-ALL development in vivo. Immunoblotting of primary murine T-ALL cells showed that the absence of Trib2 increased C/EBPα expression, a known regulator of cell proliferation, and did not alter AKT or ERK phosphorylation. Although Trib2 was suggested to be highly expressed in T-ALL, transcriptomic analysis of two independent T-ALL cohorts showed that low Trib2 expression correlated with the TLX1-expressing cortical mature T-ALL subtype, whereas high Trib2 expression correlated with the LYL1-expressing early immature T-ALL subtype. These data indicate that Trib2 has a complex role in the pathogenesis of Notch-driven T-ALL, which may vary between different T-ALL subtypes.
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Affiliation(s)
- Sarah J. Stein
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
| | - Ethan A. Mack
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
| | - Kelly S. Rome
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
| | - Kostandin V. Pajcini
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Takuya Ohtani
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
| | - Lanwei Xu
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
| | - Yunlei Li
- The Department of Pediatric Oncology/Hematology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Jules P. P. Meijerink
- The Department of Pediatric Oncology/Hematology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Robert B. Faryabi
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
| | - Warren S. Pear
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute of Medicine and Engineering, Institute for Immunology, Center for Personalized Diagnostics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States of America
- * E-mail:
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69
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Li S, Fu J, Lu C, Mapara MY, Raza S, Hengst U, Lentzsch S. Elevated Translation Initiation Factor eIF4E Is an Attractive Therapeutic Target in Multiple Myeloma. Mol Cancer Ther 2016; 15:711-9. [PMID: 26939700 DOI: 10.1158/1535-7163.mct-15-0798] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 02/08/2016] [Indexed: 11/16/2022]
Abstract
eIF4E is the key regulator of protein translation and critical for translation. The oncogenic potential of tumorigenesis, which is highly contingent on cap-dependent eIF4E, also arises from the critical role in the nuclear export and cytosolic translation of oncogenic transcripts. Inhibition of Exportin1 (XPO1), which is the major nuclear export protein for eIF4E-bound oncoprotein mRNAs, results in decreased tumor cell growth in vitro and in vivo, suggesting that eIF4E is critical in multiple myeloma. Indeed, we found that eIF4E is overexpressed in myeloma cell lines and primary myeloma cells compared with normal plasma cells. Although stable overexpression of eIF4E in multiple myeloma cells significantly increases tumorigenesis, knockdown of eIF4E impairs multiple myeloma tumor progression in a human xenograft mouse model. Using a tet-on-inducible eIF4E-knockdown system, eIF4E downregulation blocks multiple myeloma tumor growth in vivo, correlating with decreased eIF4E expression. Further overexpression and knockdown of eIF4E revealed that eIF4E regulates translation of mRNAs with highly complex 5'-untranslated regions, such as c-MYC and C/EBPβ, and subsequently proliferation in multiple myeloma cells, but not in nonmalignant bone marrow stromal cells. Because many transcription factors that are critical for multiple myeloma proliferation exhibit a higher dependency on protein translation, eIF4E is an ideal and selective tool to target multiple myeloma cell growth. Mol Cancer Ther; 15(4); 711-9. ©2016 AACR.
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Affiliation(s)
- Shirong Li
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Jing Fu
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Caisheng Lu
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Markus Y Mapara
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Shahzad Raza
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Ulrich Hengst
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York
| | - Suzanne Lentzsch
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York.
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70
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Abstract
The daily production of up to 1011 erythrocytes is tightly controlled to maintain the number of erythrocytes in peripheral blood between narrow boundaries. Availability of growth factors and nutrients, particularly iron, control the proliferation and survival of precursor cells partly through control of mRNA translation. General translation initiation mechanisms can selectively control translation of transcripts that carry specific structures in the UTRs. This selective mRNA translation is an important layer of gene expression regulation in erythropoiesis. Ribosome profiling is a recently developed high throughput sequencing technique for global mapping of translation initiation sites across the transcriptome. Here we describe what is known about control of mRNA translation in erythropoiesis and how ribosome profiling will help to further our knowledge. Ribosome footprinting will give insight in transcript-specific translation at codon resolution, which is of great value to understand many cellular processes during erythropoiesis. It will be of particular interest to understand responses to iron availability and reactive oxygen species (ROS), which affects translation initiation of transcripts harbouring upstream ORFs (uORF) and potential alternative downstream ORFs (aORF).
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71
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Johnstone TG, Bazzini AA, Giraldez AJ. Upstream ORFs are prevalent translational repressors in vertebrates. EMBO J 2016; 35:706-23. [PMID: 26896445 DOI: 10.15252/embj.201592759] [Citation(s) in RCA: 230] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 01/08/2016] [Indexed: 12/20/2022] Open
Abstract
Regulation of gene expression is fundamental in establishing cellular diversity and a target of natural selection. Untranslated mRNA regions (UTRs) are key mediators of post-transcriptional regulation. Previous studies have predicted thousands of ORFs in 5'UTRs, the vast majority of which have unknown function. Here, we present a systematic analysis of the translation and function of upstream open reading frames (uORFs) across vertebrates. Using high-resolution ribosome footprinting, we find that (i)uORFs are prevalent within vertebrate transcriptomes, (ii) the majority show signatures of active translation, and (iii)uORFs act as potent regulators of translation and RNA levels, with a similar magnitude to miRNAs. Reporter experiments reveal clear repression of downstream translation by uORFs/oORFs. uORF number, intercistronic distance, overlap with the CDS, and initiation context most strongly influence translation. Evolution has targeted these features to favor uORFs amenable to regulation over constitutively repressive uORFs/oORFs. Finally, we observe that the regulatory potential of uORFs on individual genes is conserved across species. These results provide insight into the regulatory code within mRNA leader sequences and their capacity to modulate translation across vertebrates.
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Affiliation(s)
- Timothy G Johnstone
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Ariel A Bazzini
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Antonio J Giraldez
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA Yale Stem Cell Center, Yale University School of Medicine, New Haven, CT, USA Yale Cancer Center, Yale University School of Medicine, New Haven, CT, USA
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72
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Zhang XF, Li KK, Gao L, Li SZ, Chen K, Zhang JB, Wang D, Tu RF, Zhang JX, Tao KX, Wang G, Zhang XD. miR-191 promotes tumorigenesis of human colorectal cancer through targeting C/EBPβ. Oncotarget 2016; 6:4144-58. [PMID: 25784653 PMCID: PMC4414178 DOI: 10.18632/oncotarget.2864] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 12/07/2014] [Indexed: 12/13/2022] Open
Abstract
MicroRNA-191 (miR-191), a small non-coding RNA, is involved in disease development and cancer diagnosis and prognosis. However, how miR-191 functions in colorectal cancer remains largely unclear. In this study, we show that miR-191 is highly expressed in colon tumor tissues, and that inhibition of miR-191 leads to decreased cell growth, proliferation and tumorigenicity in a xenograft model. Overexpression of miR-191 in colorectal cancer cell lines alters cell cycle progression and cell resistance to 5-Fu induced cell apoptosis. Mechanistic studies demonstrated that miR-191 directly binds to the 3′UTR of the C/EBPβ mRNA and mediates a decrease in the mRNA and protein expression of C/EBPβ. We further showed that C/EBPβ induces growth arrest in a colorectal cancer cell line and that its expression is negatively correlated with the miR-191 level in patient samples. Our findings suggest that miR-191 may be a potential gene therapy target for the treatment of colorectal cancer.
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Affiliation(s)
- Xiao-Fei Zhang
- College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Ke-ke Li
- College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Lu Gao
- Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Shang-Ze Li
- College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Ke Chen
- Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Jun-Bin Zhang
- Department of Emergency, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Di Wang
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Rong-Fu Tu
- College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Jin-Xiang Zhang
- Department of General Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Kai-Xiong Tao
- Department of General Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Guobin Wang
- Department of General Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430000, PR China
| | - Xiao-Dong Zhang
- College of Life Sciences, Wuhan University, Wuhan 430072, PR China
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73
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Jakobs A, Uttarkar S, Schomburg C, Steinmann S, Coulibaly A, Schlenke P, Berdel WE, Müller-Tidow C, Schmidt TJ, Klempnauer KH. An isoform-specific C/EBPβ inhibitor targets acute myeloid leukemia cells. Leukemia 2016; 30:1612-5. [PMID: 26854027 DOI: 10.1038/leu.2016.16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- A Jakobs
- Institute for Biochemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - S Uttarkar
- Institute for Biochemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - C Schomburg
- Institute for Pharmaceutical Biology and Phytochemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - S Steinmann
- Institute for Biochemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - A Coulibaly
- Institute for Biochemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - P Schlenke
- Department of Blood Group Serology and Transfusion Medicine, Medical University Graz, Graz, Austria
| | - W E Berdel
- Department of Medicine A, Hematology and Oncology, Westfälische Wilhelms-Universität, Münster, Germany
| | - C Müller-Tidow
- Department of Medicine, Hematology and Oncology, University of Halle, Halle, Germany
| | - T J Schmidt
- Institute for Pharmaceutical Biology and Phytochemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - K-H Klempnauer
- Institute for Biochemistry, Westfälische Wilhelms-Universität, Münster, Germany
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74
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Shimada H, Otero M, Tsuchimochi K, Yamasaki S, Sakakima H, Matsuda F, Sakasegawa M, Setoguchi T, Xu L, Goldring MB, Tanimoto A, Komiya S, Ijiri K. CCAAT/enhancer binding protein β (C/EBPβ) regulates the transcription of growth arrest and DNA damage-inducible protein 45 β (GADD45β) in articular chondrocytes. Pathol Res Pract 2016; 212:302-9. [PMID: 26896926 DOI: 10.1016/j.prp.2016.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 01/09/2016] [Accepted: 01/24/2016] [Indexed: 01/29/2023]
Abstract
Osteoarthritis (OA) is a whole joint disease characterized by cartilage degradation, which causes pain and disability in older adults. Our previous work showed that growth arrest and DNA damage-inducible protein 45 β (GADD45β) is upregulated in chondrocyte clusters in OA cartilage, especially in the early stage of this disease. CCAAT/enhancer binding protein β (C/EBPβ) is expressed in the hypertrophic growth plate chondrocytes and functions in synergy with GADD45β. Here, the presence and localization of these proteins was assessed by immunohistochemistry using articular cartilage from OA patients, revealing colocalization of C/EBPβ and GADD45β in OA chondrocytes. GADD45β promoter analysis was performed to determine whether C/EBPβ directly regulates GADD45β transcription. Furthermore, we analyzed the effect of C/EBPβ on Gadd45β gene regulation in articular chondrocytes in vivo and in vitro. Immunohistochemical analysis of C/ebpβ-haploinsufficient mice (C/ebpβ(+/-)) cartilage showed that C/ebpβ haploinsufficiency led to reduced Gadd45β gene expression in these cells. In vitro, we evaluated the effects of conditional C/EBPβ overexpression driven by the cartilage oligomeric matrix protein (Comp) promoter in mComp-tTA;pTRE-Tight-BI-DsRed-mC/ebpβ transgenic mice. C/EBPβ overexpression significantly stimulated Gadd45β gene expression in articular chondrocytes. Taken together, our data demonstrate that C/EBPβ plays a central role in controlling Gadd45β gene expression in these cells.
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Affiliation(s)
- Hirofumi Shimada
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
| | - Miguel Otero
- Laboratory for Cartilage Biology, Research Division, Hospital for Special Surgery, Weill Cornell Medical College, New York, NY, USA
| | - Kaneyuki Tsuchimochi
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan; Onga Nakama Medical Association, Onga Hospital, Fukuoka, Japan
| | - Satoshi Yamasaki
- Department of Clinical Immunology and Rheumatology, Hiroshima University, Hiroshima, Japan
| | - Harutoshi Sakakima
- Course of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Fumiyo Matsuda
- Course of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Megumi Sakasegawa
- Course of Physical Therapy, School of Health Sciences, Faculty of Medicine, Kagoshima University, Kagoshima, Japan
| | - Takao Setoguchi
- The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Lin Xu
- Department of Developmental Biology, Harvard School of Dental Medicine And Faculty of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Mary B Goldring
- Laboratory for Cartilage Biology, Research Division, Hospital for Special Surgery, Weill Cornell Medical College, New York, NY, USA
| | - Akihide Tanimoto
- Department of Human Pathology, Field of Oncology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Setsuro Komiya
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Kosei Ijiri
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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75
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In K, Zaini MA, Müller C, Warren AJ, von Lindern M, Calkhoven CF. Shwachman-Bodian-Diamond syndrome (SBDS) protein deficiency impairs translation re-initiation from C/EBPα and C/EBPβ mRNAs. Nucleic Acids Res 2016; 44:4134-46. [PMID: 26762974 PMCID: PMC4872075 DOI: 10.1093/nar/gkw005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/31/2015] [Indexed: 01/24/2023] Open
Abstract
Mutations in the Shwachman–Bodian–Diamond Syndrome (SBDS) gene cause Shwachman–Diamond Syndrome (SDS), a rare congenital disease characterized by bone marrow failure with neutropenia, exocrine pancreatic dysfunction and skeletal abnormalities. The SBDS protein is important for ribosome maturation and therefore SDS belongs to the ribosomopathies. It is unknown, however, if loss of SBDS functionality affects the translation of specific mRNAs and whether this could play a role in the development of the clinical features of SDS. Here, we report that translation of the C/EBPα and -β mRNAs, that are indispensible regulators of granulocytic differentiation, is altered by SBDS mutations or knockdown. We show that SBDS function is specifically required for efficient translation re-initiation into the protein isoforms C/EBPα-p30 and C/EBPβ-LIP, which is controlled by a single cis-regulatory upstream open reading frame (uORF) in the 5′ untranslated regions (5′ UTRs) of both mRNAs. Furthermore, we show that as a consequence of the C/EBPα and -β deregulation the expression of MYC is decreased with associated reduction in proliferation, suggesting that failure of progenitor proliferation contributes to the haematological phenotype of SDS. Therefore, our study provides the first indication that disturbance of specific translation by loss of SBDS function may contribute to the development of the SDS phenotype.
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Affiliation(s)
- Kyungmin In
- Leibniz Institute on Aging - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Mohamad A Zaini
- Leibniz Institute on Aging - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany European Institute for the Biology of Ageing (ERIBA), University Medical Center Groningen, University of Groningen, 9700 AD, Groningen, The Netherlands
| | - Christine Müller
- Leibniz Institute on Aging - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany European Institute for the Biology of Ageing (ERIBA), University Medical Center Groningen, University of Groningen, 9700 AD, Groningen, The Netherlands
| | - Alan J Warren
- Cambridge Institute for Medical Research, Wellcome Trust-Medical Research Council Stem Cell Institute, the Department of Haematology, University of Cambridge, CB2 0XY, Cambridge, UK
| | - Marieke von Lindern
- Sanquin Research and Landsteiner Laboratory, Department of Hematopoiesis, 1066 CX Amsterdam, The Netherlands
| | - Cornelis F Calkhoven
- Leibniz Institute on Aging - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany European Institute for the Biology of Ageing (ERIBA), University Medical Center Groningen, University of Groningen, 9700 AD, Groningen, The Netherlands
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Huber R, Panterodt T, Welz B, Christmann M, Friesenhagen J, Westphal A, Pietsch D, Brand K. C/EBPβ-LAP*/LAP Expression Is Mediated by RSK/eIF4B-Dependent Signalling and Boosted by Increased Protein Stability in Models of Monocytic Differentiation. PLoS One 2015; 10:e0144338. [PMID: 26646662 PMCID: PMC4672875 DOI: 10.1371/journal.pone.0144338] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 11/17/2015] [Indexed: 11/30/2022] Open
Abstract
The transcription factor C/EBPβ plays a key role in monocytic differentiation and inflammation. Its small isoform LIP is associated with proliferation at early premonocytic developmental stages and regulated via mTOR-dependent signalling. During later stages of (pre)monocytic differentiation there is a considerable increase in the large C/EBPβ isoforms LAP*/LAP which inhibit proliferation thus supporting terminal differentiation. Here, we showed in different models of monocytic differentiation that this dramatic increase in the LAP*/LAP protein and LAP/LIP ratio was accompanied by an only modest/retarded mRNA increase suggesting an important role for (post)translational mechanisms. We found that LAP*/LAP formation was induced via MEK/RSK-dependent cascades, whereas mTOR/S6K1 were not involved. Remarkably, LAP*/LAP expression was dependent on phosphorylated eIF4B, an acceleratory protein of RNA helicase eIF4A. PKR inhibition reduced the expression of eIF4B and C/EBPβ in an eIF2α-independent manner. Furthermore, under our conditions a marked stabilisation of LAP*/LAP protein occurred, accompanied by reduced chymotrypsin-like proteasome/calpain activities and increased calpastatin levels. Our study elucidates new signalling pathways inducing LAP*/LAP expression and indicates new alternative PKR functions in monocytes. The switch from mTOR- to RSK-mediated signalling to orchestrate eIF4B-dependent LAP*/LAP translation, accompanied by increased protein stability but only small mRNA changes, may be a prototypical example for the regulation of protein expression during selected processes of differentiation/proliferation.
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Affiliation(s)
- René Huber
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Thomas Panterodt
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Bastian Welz
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Martin Christmann
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Judith Friesenhagen
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Andreas Westphal
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Daniel Pietsch
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Korbinian Brand
- Institute of Clinical Chemistry, Hannover Medical School, 30625 Hannover, Germany
- * E-mail:
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77
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The multifaceted functions of C/EBPα in normal and malignant haematopoiesis. Leukemia 2015; 30:767-75. [PMID: 26601784 DOI: 10.1038/leu.2015.324] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 11/08/2015] [Accepted: 11/16/2015] [Indexed: 02/06/2023]
Abstract
The process of blood formation, haematopoiesis, depends upon a small number of haematopoietic stem cells (HSCs) that reside in the bone marrow. Differentiation of HSCs is characterised by decreased expression of genes associated with self-renewal accompanied by a stepwise activation of genes promoting differentiation. Lineage branching is further directed by groups of cooperating and counteracting genes forming complex networks of lineage-specific transcription factors. Imbalances in such networks can result in blockage of differentiation, lineage reprogramming and malignant transformation. CCAAT/enhancer-binding protein-α (C/EBPα) was originally identified 30 years ago as a transcription factor that binds both promoter and enhancer regions. Most of the early work focused on the role of C/EBPα in regulating transcriptional processes as well as on its functions in key differentiation processes during liver, adipogenic and haematopoietic development. Specifically, C/EBPα was shown to control differentiation by its ability to coordinate transcriptional output with cell cycle progression. Later, its role as an important tumour suppressor, mainly in acute myeloid leukaemia (AML), was recognised and has been the focus of intense studies by a number of investigators. More recent work has revisited the role of C/EBPα in normal haematopoiesis, especially its function in HSCs, and also started to provide more mechanistic insights into its role in normal and malignant haematopoiesis. In particular, the differential actions of C/EBPα isoforms, as well as its importance in chromatin remodelling and cellular reprogramming, are beginning to be elucidated. Finally, recent work has also shed light on the dichotomous function of C/EBPα in AML by demonstrating its ability to act as both a tumour suppressor and promoter. In the present review, we will summarise the current knowledge on the functions of C/EBPα during normal and malignant haematopoiesis with special emphasis on the recent work.
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78
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Putlyaeva LV, Schwartz AM, Korneev KV, Covic M, Uroshlev LA, Makeev VY, Dmitriev SE, Kuprash DV. Upstream open reading frames regulate translation of the long isoform of SLAMF1 mRNA that encodes costimulatory receptor CD150. BIOCHEMISTRY (MOSCOW) 2015; 79:1405-11. [PMID: 25716736 DOI: 10.1134/s0006297914120165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
More than 40% of human genes contain upstream open reading frames (uORF) in their 5'-untranslated regions (5'-UTRs) and at the same time express at least one truncated mRNA isoform containing no uORF. We studied translational regulation by four uORFs found in the 5'-UTR of full-length mRNA for SLAMF1, the gene encoding CD150 membrane protein. CD150 is a member of the CD2 superfamily, a costimulatory lymphocyte receptor, a receptor for measles virus, and a microbial sensor on macrophages. The SLAMF1 gene produces at least two mRNA isoforms that differ in their 5'-UTRs. In the long isoform of the SLAMF1 mRNA that harbors four uORFs in the 5'-UTR, the stop codon of uORF4 overlaps with the AUG codon of the main ORF forming a potential termination-reinitiation site UGAUG, while uORF2 and uORF3 start codons flank a sequence identical to Motif 1 from the TURBS regulatory element. TURBS was shown to be required for a coupled termination-reinitiation event during translation of polycistronic RNAs of some viruses. In a model cell system, reporter mRNA based on the 5'-UTR of SLAMF1 short isoform, which lacks any uORF, is translated 5-6 times more efficiently than the mRNA with 5'-UTR from the long isoform. Nucleotide substitutions disrupting start codons in either uORF2-4 result in significant increase in translation efficiency, while substitution of two nucleotides in TURBS Motif 1 leads to a 2-fold decrease in activity. These data suggest that TURBS-like elements can serve for translation control of certain cellular mRNAs containing uORFs.
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Affiliation(s)
- L V Putlyaeva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
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79
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Molecular Mechanism of CCAAT-Enhancer Binding Protein Recruitment by the TRIB1 Pseudokinase. Structure 2015; 23:2111-21. [PMID: 26455797 DOI: 10.1016/j.str.2015.08.017] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/23/2015] [Accepted: 08/28/2015] [Indexed: 01/18/2023]
Abstract
CCAAT-enhancer binding proteins (C/EBPs) are transcription factors that play a central role in the differentiation of myeloid cells and adipocytes. Tribbles pseudokinases govern levels of C/EBPs by recruiting them to the COP1 ubiquitin ligase for ubiquitination. Here, we present the first crystal structure of a Tribbles protein, which reveals a catalytically inactive TRIB1 pseudokinase domain with a unique adaptation in the αC helix. A second crystal structure and biophysical studies of TRIB1 with its C-terminal extension, which includes the COP1-binding motif, show that the C-terminal extension is sequestered at a site formed by the modified TRIB1 αC helix. In addition, we have identified and characterized the TRIB1 substrate-recognition sequence within C/EBPα, which is evolutionarily conserved in C/EBP transcription factors. Binding studies indicate that C/EBPα recruitment is weaker in the presence of the C-terminal COP1-binding motif, but the magnitude of this effect suggests that the two bind distinct rather directly overlapping binding sites.
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80
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Shi Z, Barna M. Translating the genome in time and space: specialized ribosomes, RNA regulons, and RNA-binding proteins. Annu Rev Cell Dev Biol 2015; 31:31-54. [PMID: 26443190 DOI: 10.1146/annurev-cellbio-100814-125346] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A central question in cell and developmental biology is how the information encoded in the genome is differentially interpreted to generate a diverse array of cell types. A growing body of research on posttranscriptional gene regulation is revealing that both global protein synthesis rates and the translation of specific mRNAs are highly specialized in different cell types. How this exquisite translational regulation is achieved is the focus of this review. Two levels of regulation are discussed: the translation machinery and cis-acting elements within mRNAs. Recent evidence shows that the ribosome itself directs how the genome is translated in time and space and reveals surprising functional specificity in individual components of the core translation machinery. We are also just beginning to appreciate the rich regulatory information embedded in the untranslated regions of mRNAs, which direct the selective translation of transcripts. These hidden RNA regulons may interface with a myriad of RNA-binding proteins and specialized translation machinery to provide an additional layer of regulation to how transcripts are spatiotemporally expressed. Understanding this largely unexplored world of translational codes hardwired in the core translation machinery is an exciting new research frontier fundamental to our understanding of gene regulation, organismal development, and evolution.
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Affiliation(s)
- Zhen Shi
- Department of Developmental Biology and Department of Genetics, Stanford University, Stanford, California 94305;
| | - Maria Barna
- Department of Developmental Biology and Department of Genetics, Stanford University, Stanford, California 94305;
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81
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82
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Zhao M, Chen X. Effect of lipopolysaccharides on adipogenic potential and premature senescence of adipocyte progenitors. Am J Physiol Endocrinol Metab 2015; 309:E334-44. [PMID: 26105007 PMCID: PMC4537924 DOI: 10.1152/ajpendo.00601.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 06/22/2015] [Indexed: 01/13/2023]
Abstract
The elevation of circulating LPS has been associated with obesity and aging. However, whether and how LPS contributes to adipose tissue dysfunction is unclear. In this study, we investigated the effect of LPS on the adipogenic capacity and cellular senescence of adipocyte progenitors. Stromal-vascular cells were isolated from inguinal adipose tissue of C57BL/6 mice and treated with LPS during the different time periods of adipocyte differentiation. We found that LPS treatment for 24 h prior to the induction of differentiation led to the most profound effect on the inhibition of adipogenesis, as evidenced by the morphological changes and the decreased mRNA expression of adipocyte marker genes. In addition, LPS induced features of premature senescence of SV cells, including the activation of p53, the elevation of SA-β-gal activity, and increased hydrogen peroxide production, but not telomere length. Upon LPS treatment, SV cells also developed senescence-associated secretory phenotype (SASP), as demonstrated by the increased expression of TNFα, IL-1β, IL-6, MCP-1, and VEGFα. Blocking LPS-induced NF-κB activation and cytokine production by Bay 11-7082 failed to rescue the impaired adipogenesis and the reduction in PPARγ and Zfp423 expression. On the contrary, rosiglitazone had little effect on cytokine production but corrected the defective adipogenic potential. In conclusion, we demonstrate that LPS inhibits adipogenesis by disrupting the differentiation of adipocyte progenitors in a NF-κB-independent manner; LPS also induces premature senescence of adipocyte progenitors. Our data suggest that LPS could be a potential contributor to the defective adipogenesis and the development of cellular senescence in adipose tissue during obesity and aging.
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Affiliation(s)
- Ming Zhao
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, Minnesota
| | - Xiaoli Chen
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, Minnesota
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83
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Abstract
Viral genomes harbor a variety of unusual translational phenomena that allow them to pack coding information more densely and evade host restriction mechanisms imposed by the cellular translational apparatus. Annotating translated sequences within these genomes thus poses particular challenges, but identifying the full complement of proteins encoded by a virus is critical for understanding its life cycle and defining the epitopes it presents for immune surveillance. Ribosome profiling is an emerging technique for global analysis of translation that offers direct and experimental annotation of viral genomes. Ribosome profiling has been applied to two herpesvirus genomes, those of human cytomegalovirus and Kaposi's sarcoma-associated herpesvirus, revealing translated sequences within presumptive long noncoding RNAs and identifying other micropeptides. Synthesis of these proteins has been confirmed by mass spectrometry and by identifying T cell responses following infection. Ribosome profiling in other viruses will likely expand further our understanding of viral gene regulation and the proteome.
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Affiliation(s)
- Noam Stern-Ginossar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel;
| | - Nicholas T Ingolia
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720;
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84
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Sahlberg AS, Ruuska M, Colbert RA, Granfors K, Penttinen MA. Altered PKR Signalling and C / EBPβ Expression is Associated with HLA-B27 Expression in Monocytic Cells. Scand J Immunol 2015; 75:184-92. [PMID: 21988375 DOI: 10.1111/j.1365-3083.2011.02648.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Infection caused by certain gram-negative bacteria, e.g. Salmonella, can trigger inflammatory joint disease reactive arthritis (ReA). It is suggested that the disease-triggering bacteria or bacterial components persist in patients for an abnormally long time. Development of ReA is strongly associated with tissue antigen HLA-B27. Previously, we reported an enhanced replication of Salmonella enteritidis and altered p38 MAP kinase signalling in HLA-B27-expressing monocytic cells. Here we aimed to investigate the role of HLA-B27 in regulation of double-stranded RNA-activated kinase (PKR)-related signalling in Salmonella-infected or Salmonella lipopolysaccharide (LPS)-stimulated human U937 monocytic cells, as PKR has been reported to modify p38 signalling in Salmonella-infected cells. In cells expressing HLA-B27, PKR is overexpressed and hypophosphorylated, and the expression of transcription factor CCAAT enhancer binding protein beta (C/EBPβ) is increased upon Salmonella infection and LPS stimulation. The expression of C/EBPβ is PKR-dependent in LPS-stimulated mock cells, whereas in LPS-stimulated B27 cells the majority of C/EBPβ is expressed in a PKR-independent manner. Our results show that the expression of HLA-B27 disturbs the PKR-mediated signalling pathway. Moreover, altered signalling is related to misfolding-linked Glu45 in the B pocket of the HLA-B27 heavy chain. We suggest that the expression of HLA-B27 HCs modulates the intracellular environment of monocyte/macrophages and the mechanisms that are important in eliminating intracellular S. enteritidis by altering the intracellular signalling. This phenomenon is at least partly dependent on the misfolding feature of the B27 molecule. These observations offer a novel mechanism by which HLA-B27 may modulate inflammatory response induced by ReA-triggering bacteria.
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Affiliation(s)
- A S Sahlberg
- National Institute for Health and Welfare, Turku, FinlandNIAMS, National Institutes of Health, Bethesda, MD, USADepartment of Medical Microbiology, University of Turku, Turku, Finland
| | - M Ruuska
- National Institute for Health and Welfare, Turku, FinlandNIAMS, National Institutes of Health, Bethesda, MD, USADepartment of Medical Microbiology, University of Turku, Turku, Finland
| | - R A Colbert
- National Institute for Health and Welfare, Turku, FinlandNIAMS, National Institutes of Health, Bethesda, MD, USADepartment of Medical Microbiology, University of Turku, Turku, Finland
| | - K Granfors
- National Institute for Health and Welfare, Turku, FinlandNIAMS, National Institutes of Health, Bethesda, MD, USADepartment of Medical Microbiology, University of Turku, Turku, Finland
| | - M A Penttinen
- National Institute for Health and Welfare, Turku, FinlandNIAMS, National Institutes of Health, Bethesda, MD, USADepartment of Medical Microbiology, University of Turku, Turku, Finland
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85
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Abstract
Herpesviral mRNAs are produced and translated by cellular machinery, rendering them susceptible to the network of regulatory events that impact translation. In response, these viruses have evolved to infiltrate and hijack translational control pathways as well as to integrate specialized host translation strategies into their own repertoire. They are robust systems to dissect mechanisms of mammalian translational regulation and continue to offer insight into cis-acting mRNA features that impact assembly and activity of the translation apparatus. Here, I discuss recent advances revealing the extent to which the three herpesvirus subfamilies regulate both host and viral translation, thereby dramatically impacting the landscape of protein synthesis in infected cells.
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Affiliation(s)
- Britt A Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720;
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86
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Pulido-Salgado M, Vidal-Taboada JM, Saura J. C/EBPβ and C/EBPδ transcription factors: Basic biology and roles in the CNS. Prog Neurobiol 2015; 132:1-33. [PMID: 26143335 DOI: 10.1016/j.pneurobio.2015.06.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 05/08/2015] [Accepted: 06/16/2015] [Indexed: 02/01/2023]
Abstract
CCAAT/enhancer binding protein (C/EBP) β and C/EBPδ are transcription factors of the basic-leucine zipper class which share phylogenetic, structural and functional features. In this review we first describe in depth their basic molecular biology which includes fascinating aspects such as the regulated use of alternative initiation codons in the C/EBPβ mRNA. The physical interactions with multiple transcription factors which greatly opens the number of potentially regulated genes or the presence of at least five different types of post-translational modifications are also remarkable molecular mechanisms that modulate C/EBPβ and C/EBPδ function. In the second part, we review the present knowledge on the localization, expression changes and physiological roles of C/EBPβ and C/EBPδ in neurons, astrocytes and microglia. We conclude that C/EBPβ and C/EBPδ share two unique features related to their role in the CNS: whereas in neurons they participate in memory formation and synaptic plasticity, in glial cells they regulate the pro-inflammatory program. Because of their role in neuroinflammation, C/EBPβ and C/EBPδ in microglia are potential targets for treatment of neurodegenerative disorders. Any strategy to reduce C/EBPβ and C/EBPδ activity in neuroinflammation needs to take into account its potential side-effects in neurons. Therefore, cell-specific treatments will be required for the successful application of this strategy.
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Affiliation(s)
- Marta Pulido-Salgado
- Biochemistry and Molecular Biology Unit, School of Medicine, University of Barcelona, IDIBAPS, Casanova 143, planta 3, 08036 Barcelona, Spain
| | - Jose M Vidal-Taboada
- Biochemistry and Molecular Biology Unit, School of Medicine, University of Barcelona, IDIBAPS, Casanova 143, planta 3, 08036 Barcelona, Spain
| | - Josep Saura
- Biochemistry and Molecular Biology Unit, School of Medicine, University of Barcelona, IDIBAPS, Casanova 143, planta 3, 08036 Barcelona, Spain.
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87
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Albert V, Hall MN. Reduced C/EBPβ-LIP translation improves metabolic health. EMBO Rep 2015; 16:881-2. [PMID: 26113367 DOI: 10.15252/embr.201540757] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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88
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Zidek LM, Ackermann T, Hartleben G, Eichwald S, Kortman G, Kiehntopf M, Leutz A, Sonenberg N, Wang ZQ, von Maltzahn J, Müller C, Calkhoven CF. Deficiency in mTORC1-controlled C/EBPβ-mRNA translation improves metabolic health in mice. EMBO Rep 2015; 16:1022-36. [PMID: 26113365 PMCID: PMC4552494 DOI: 10.15252/embr.201439837] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 05/21/2015] [Indexed: 01/17/2023] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is a central regulator of physiological adaptations in response to changes in nutrient supply. Major downstream targets of mTORC1 signalling are the mRNA translation regulators p70 ribosomal protein S6 kinase 1 (S6K1p70) and the 4E-binding proteins (4E-BPs). However, little is known about vertebrate mRNAs that are specifically controlled by mTORC1 signalling and are engaged in regulating mTORC1-associated physiology. Here, we show that translation of the CCAAT/enhancer binding protein beta (C/EBPβ) mRNA into the C/EBPβ-LIP isoform is suppressed in response to mTORC1 inhibition either through pharmacological treatment or through calorie restriction. Our data indicate that the function of 4E-BPs is required for suppression of LIP. Intriguingly, mice lacking the cis-regulatory upstream open reading frame (uORF) in the C/EBPβ-mRNA, which is required for mTORC1-stimulated translation into C/EBPβ-LIP, display an improved metabolic phenotype with features also found under calorie restriction. Thus, our data suggest that translational adjustment of C/EBPβ-isoform expression is one of the key processes that direct metabolic adaptation in response to changes in mTORC1 activity.
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Affiliation(s)
- Laura M Zidek
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Tobias Ackermann
- European Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Götz Hartleben
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany European Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Sabrina Eichwald
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Gertrud Kortman
- European Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Michael Kiehntopf
- Department of Clinical Chemistry and Laboratory Diagnostics, University Hospital Jena, Jena, Germany
| | - Achim Leutz
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Nahum Sonenberg
- Department of Biochemistry & Goodman Cancer Research Center, McGill University, Montreal, QC, Canada
| | - Zhao-Qi Wang
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Julia von Maltzahn
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Christine Müller
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany European Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Cornelis F Calkhoven
- Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany European Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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89
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Wethmar K, Schulz J, Muro EM, Talyan S, Andrade-Navarro MA, Leutz A. Comprehensive translational control of tyrosine kinase expression by upstream open reading frames. Oncogene 2015; 35:1736-42. [PMID: 26096937 PMCID: PMC4820681 DOI: 10.1038/onc.2015.233] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 04/02/2015] [Accepted: 05/10/2015] [Indexed: 12/24/2022]
Abstract
Post-transcriptional control has emerged as a major regulatory event in gene expression and often occurs at the level of translation initiation. Although overexpression or constitutive activation of tyrosine kinases (TKs) through gene amplification, translocation or mutation are well-characterized oncogenic events, current knowledge about translational mechanisms of TK activation is scarce. Here, we report the presence of translational cis-regulatory upstream open reading frames (uORFs) in the majority of transcript leader sequences of human TK mRNAs. Genetic ablation of uORF initiation codons in TK transcripts resulted in enhanced translation of the associated downstream main protein-coding sequences (CDSs) in all cases studied. Similarly, experimental removal of uORF start codons in additional non-TK proto-oncogenes, and naturally occurring loss-of-uORF alleles of the c-met proto-oncogene (MET) and the kinase insert domain receptor (KDR), was associated with increased CDS translation. Based on genome-wide sequence analyses we identified polymorphisms in 15.9% of all human genes affecting uORF initiation codons, associated Kozak consensus sequences or uORF-related termination codons. Together, these data suggest a comprehensive role of uORF-mediated translational control and delineate how aberrant induction of proto-oncogenes through loss-of-function mutations at uORF initiation codons may be involved in the etiology of cancer. We provide a detailed map of uORFs across the human genome to stimulate future research on the pathogenic role of uORFs.
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Affiliation(s)
- K Wethmar
- Department of Cell Differentiation and Tumorigenesis, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany.,Department of Hematology, Oncology and Pneumology, University Hospital Muenster, Muenster, Germany
| | - J Schulz
- Department of Cell Differentiation and Tumorigenesis, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany
| | - E M Muro
- Department of Computational Biology and Data Mining, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany.,Department of Biology, Institute of Molecular Biology, Johannes-Gutenberg University, Mainz, Germany
| | - S Talyan
- Department of Biology, Institute of Molecular Biology, Johannes-Gutenberg University, Mainz, Germany
| | - M A Andrade-Navarro
- Department of Computational Biology and Data Mining, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany.,Department of Biology, Institute of Molecular Biology, Johannes-Gutenberg University, Mainz, Germany
| | - A Leutz
- Department of Cell Differentiation and Tumorigenesis, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany.,Department of Biology, Humboldt-University, Berlin, Germany
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90
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Yu H, He K, Wang L, Hu J, Gu J, Zhou C, Lu R, Jin Y. Stk40 represses adipogenesis through translational control of CCAAT/enhancer-binding proteins. J Cell Sci 2015; 128:2881-90. [PMID: 26065429 DOI: 10.1242/jcs.170282] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 06/04/2015] [Indexed: 01/08/2023] Open
Abstract
A better understanding of molecular regulation in adipogenesis might help the development of efficient strategies to cope with obesity-related diseases. Here, we report that CCAAT/enhancer-binding protein (C/EBP) β and C/EBPδ, two crucial pro-adipogenic transcription factors, are controlled at a translational level by serine/threonine kinase 40 (Stk40). Genetic knockout (KO) or knockdown (KD) of Stk40 leads to increased protein levels of C/EBP proteins and adipocyte differentiation in mouse embryonic fibroblasts (MEFs), fetal liver stromal cells, and mesenchymal stem cells (MSCs). In contrast, overexpression of Stk40 abolishes the enhanced C/EBP protein translation and adipogenesis observed in Stk40-KO and -KD cells. Functionally, knockdown of C/EBPβ eliminates the enhanced adipogenic differentiation in Stk40-KO and -KD cells substantially. Mechanistically, deletion of Stk40 enhances phosphorylation of eIF4E-binding protein 1, leading to increased eIF4E-dependent translation of C/EBPβ and C/EBPδ. Knockdown of eIF4E in MSCs decreases translation of C/EBP proteins. Moreover, Stk40-KO fetal livers display an increased adipogenic program and aberrant lipid and steroid metabolism. Collectively, our study uncovers a new repressor of C/EBP protein translation as well as adipogenesis and provides new insights into the molecular mechanism underpinning the adipogenic program.
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Affiliation(s)
- Hongyao Yu
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Ke He
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Lina Wang
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Jing Hu
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Junjie Gu
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Chenlin Zhou
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Rui Lu
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Ying Jin
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
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91
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Hansberg-Pastor V, Piña-Medina AG, González-Arenas A, Camacho-Arroyo I. C/EBPβ Isoforms Expression in the Rat Brain during the Estrous Cycle. Int J Endocrinol 2015; 2015:674915. [PMID: 26064112 PMCID: PMC4429186 DOI: 10.1155/2015/674915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 04/02/2015] [Accepted: 04/02/2015] [Indexed: 01/10/2023] Open
Abstract
The CCAAT/enhancer-binding protein beta (C/EBPβ) is a transcription factor expressed in different areas of the brain that regulates the expression of several genes involved in cell differentiation and proliferation. This protein has three isoforms (LAP1, LAP2, and LIP) with different transcription activation potential. The role of female sex hormones in the expression pattern of C/EBPβ isoforms in the rat brain has not yet been described. In this study we demonstrate by western blot that the expression of the three C/EBPβ isoforms changes in different brain areas during the estrous cycle. In the cerebellum, LAP2 content diminished on diestrus and proestrus and LIP content diminished on proestrus and estrus days. In the prefrontal cortex, LIP content was higher on proestrus and estrus days. In the hippocampus, LAP isoforms presented a switch on diestrus day, since LAP1 content was the highest while that of LAP2 was the lowest. The LAP2 isoform was the most abundant one in all the three brain areas. The LAP/LIP ratio changed throughout the cycle and was tissue specific. These results suggest that C/EBPβ isoforms expression changes in a tissue-specific manner in the rat brain due to the changes in sex steroid hormone levels presented during the estrous cycle.
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Affiliation(s)
- Valeria Hansberg-Pastor
- Departamento de Biología, Facultad de Química, Universidad Nacional Autónoma de México, DF, Mexico
| | - Ana Gabriela Piña-Medina
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Avenida Universidad 3000, Coyoacán, 04510 Ciudad de México, DF, Mexico
| | - Aliesha González-Arenas
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, DF, Mexico
| | - Ignacio Camacho-Arroyo
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Avenida Universidad 3000, Coyoacán, 04510 Ciudad de México, DF, Mexico
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92
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de Klerk E, Fokkema IFAC, Thiadens KAMH, Goeman JJ, Palmblad M, den Dunnen JT, von Lindern M, 't Hoen PAC. Assessing the translational landscape of myogenic differentiation by ribosome profiling. Nucleic Acids Res 2015; 43:4408-28. [PMID: 25873627 PMCID: PMC4482065 DOI: 10.1093/nar/gkv281] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 03/21/2015] [Indexed: 01/08/2023] Open
Abstract
The formation of skeletal muscles is associated with drastic changes in protein requirements known to be safeguarded by tight control of gene transcription and mRNA processing. The contribution of regulation of mRNA translation during myogenesis has not been studied so far. We monitored translation during myogenic differentiation of C2C12 myoblasts, using a simplified protocol for ribosome footprint profiling. Comparison of ribosome footprints to total RNA showed that gene expression is mostly regulated at the transcriptional level. However, a subset of transcripts, enriched for mRNAs encoding for ribosomal proteins, was regulated at the level of translation. Enrichment was also found for specific pathways known to regulate muscle biology. We developed a dedicated pipeline to identify translation initiation sites (TISs) and discovered 5333 unannotated TISs, providing a catalog of upstream and alternative open reading frames used during myogenesis. We identified 298 transcripts with a significant switch in TIS usage during myogenesis, which was not explained by alternative promoter usage, as profiled by DeepCAGE. Also these transcripts were enriched for ribosomal protein genes. This study demonstrates that differential mRNA translation controls protein expression of specific subsets of genes during myogenesis. Experimental protocols, analytical workflows, tools and data are available through public repositories (http://lumc.github.io/ribosome-profiling-analysis-framework/).
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Affiliation(s)
- Eleonora de Klerk
- Department of Human Genetics, Leiden University Medical Center, Postzone S4-P, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Ivo F A C Fokkema
- Department of Human Genetics, Leiden University Medical Center, Postzone S4-P, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Klaske A M H Thiadens
- Department of Hematopoiesis, Sanquin Research and Landsteiner Laboratory, AMC/UvA, 1066CX 125 Amsterdam, The Netherlands
| | - Jelle J Goeman
- Biostatistics, Department for Health Evidence, Radboud University Medical Center, Postzone 133, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Magnus Palmblad
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Johan T den Dunnen
- Department of Human Genetics, Leiden University Medical Center, Postzone S4-P, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Marieke von Lindern
- Department of Hematopoiesis, Sanquin Research and Landsteiner Laboratory, AMC/UvA, 1066CX 125 Amsterdam, The Netherlands
| | - Peter A C 't Hoen
- Department of Human Genetics, Leiden University Medical Center, Postzone S4-P, PO Box 9600, 2300 RC Leiden, The Netherlands
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93
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Gocek E, Studzinski GP. The Potential of Vitamin D-Regulated Intracellular Signaling Pathways as Targets for Myeloid Leukemia Therapy. J Clin Med 2015; 4:504-34. [PMID: 26239344 PMCID: PMC4470153 DOI: 10.3390/jcm4040504] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 01/06/2015] [Accepted: 03/06/2015] [Indexed: 02/06/2023] Open
Abstract
The current standard regimens for the treatment of acute myeloid leukemia (AML) are curative in less than half of patients; therefore, there is a great need for innovative new approaches to this problem. One approach is to target new treatments to the pathways that are instrumental to cell growth and survival with drugs that are less harmful to normal cells than to neoplastic cells. In this review, we focus on the MAPK family of signaling pathways and those that are known to, or potentially can, interact with MAPKs, such as PI3K/AKT/FOXO and JAK/STAT. We exemplify the recent studies in this field with specific relevance to vitamin D and its derivatives, since they have featured prominently in recent scientific literature as having anti-cancer properties. Since microRNAs also are known to be regulated by activated vitamin D, this is also briefly discussed here, as are the implications of the emerging acquisition of transcriptosome data and potentiation of the biological effects of vitamin D by other compounds. While there are ongoing clinical trials of various compounds that affect signaling pathways, more studies are needed to establish the clinical utility of vitamin D in the treatment of cancer.
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Affiliation(s)
- Elzbieta Gocek
- Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw 50-383, Poland.
| | - George P Studzinski
- Department of Pathology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Ave., Newark, NJ 17101, USA.
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94
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Barakat DJ, Zhang J, Barberi T, Denmeade SR, Friedman AD, Paz-Priel I. CCAAT/Enhancer binding protein β controls androgen-deprivation-induced senescence in prostate cancer cells. Oncogene 2015; 34:5912-22. [PMID: 25772238 PMCID: PMC4573387 DOI: 10.1038/onc.2015.41] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 12/19/2014] [Accepted: 01/06/2015] [Indexed: 12/17/2022]
Abstract
The processes associated with transition to castration independent prostate cancer growth are not well understood. Cellular senescence is a stable cell cycle arrest that occurs in response to sublethal stress. It is often overcome in malignant transformation to confer a survival advantage. CCAAT/Enhancer Binding Protein (C/EBP) β function is frequently deregulated in human malignancies and interestingly, androgen dependent prostate cancer cells express primarily the LIP isoform. We found that C/EBPβ expression is negatively regulated by androgen receptor activity and that treatment of androgen dependent cell lines with anti-androgens increases C/EBPβ mRNA and protein levels. Accordingly, we also find that C/EBPβ levels are significantly elevated in primary prostate cancer samples from castration resistant compared with therapy naive patients. Chromatin immunoprecipitation demonstrated enhanced binding of the androgen receptor to the proximal promoter of the CEBPB gene in the presence of dihydroxytestosterone. Upon androgen deprivation, induction of C/EBPβ is facilitated by active transcription as evident by increased histone 3 acetylation at the C/EBPβ promoter. Also, the androgen agonist R1881 suppresses the activity of a CEBPB promoter reporter. Loss of C/EBPβ expression prevents growth arrest following androgen deprivation or anti-androgen challenge. Accordingly, suppression of C/EBPβ under low androgen conditions results in reduced expression of senescence-associated secretory genes, significantly decreased number of cells displaying heterochromatin foci, and increased numbers of Ki67 positive cells. Ectopic expression of C/EBPβ caused pronounced morphological changes, reduced PC cell growth, and increased the number of senescent LNCaP cells. Lastly, we found that senescence contributes to prostate cancer cell survival under androgen deprivation, and C/EBPβ deficient cells were significantly more susceptible to killing by cytotoxic chemotherapy following androgen deprivation. Our data demonstrate that up-regulation of C/EBPβ is critical for complete maintenance of androgen deprivation induced senescence and that targeting C/EBPβ expression may synergize with anti-androgen or chemotherapy in eradicating prostate cancer.
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Affiliation(s)
- D J Barakat
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - J Zhang
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - T Barberi
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - S R Denmeade
- Division of Medical Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - A D Friedman
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
| | - I Paz-Priel
- Division of Pediatric Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
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95
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Friedman AD. C/EBPα in normal and malignant myelopoiesis. Int J Hematol 2015; 101:330-41. [PMID: 25753223 DOI: 10.1007/s12185-015-1764-6] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 02/18/2015] [Accepted: 02/19/2015] [Indexed: 12/22/2022]
Abstract
CCAAT/enhancer binding protein α (C/EBPα) dimerizes via its leucine zipper (LZ) domain to bind DNA via its basic region and activate transcription via N-terminal trans-activation domains. The activity of C/EBPα is modulated by several serine/threonine kinases and via sumoylation, its gene is activated by RUNX1 and additional transcription factors, its mRNA stability is modified by miRNAs, and its mRNA is subject to translation control that affects AUG selection. In addition to inducing differentiation, C/EBPα inhibits cell cycle progression and apoptosis. Within hematopoiesis, C/EBPα levels increase as long-term stem cells progress to granulocyte-monocyte progenitors (GMP). Absence of C/EBPα prevents GMP formation, and higher levels are required for granulopoiesis compared to monopoiesis. C/EBPα interacts with AP-1 proteins to bind hybrid DNA elements during monopoiesis, and induction of Gfi-1, C/EBPε, KLF5, and miR-223 by C/EBPα enables granulopoiesis. The CEBPA ORF is mutated in approximately 10 % of acute myeloid leukemias (AML), leading to expression of N-terminally truncated C/EBPαp30 and C-terminal, in-frame C/EBPαLZ variants, which inhibit C/EBPα activities but also play additional roles during myeloid transformation. RUNX1 mutation, CEBPA promoter methylation, Trib1 or Trib2-mediated C/EBPαp42 degradation, and signaling pathways leading to C/EBPα serine 21 phosphorylation reduce C/EBPα expression or activity in additional AML cases.
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Affiliation(s)
- Alan D Friedman
- Division of Pediatric Oncology, Johns Hopkins University, Cancer Research Building I, Room 253, 1650 Orleans Street, Baltimore, MD, 21231, USA,
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96
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Hernandez-Encinas E, Aguilar-Morante D, Cortes-Canteli M, Morales-Garcia JA, Gine E, Santos A, Perez-Castillo A. CCAAT/enhancer binding protein β directly regulates the expression of the complement component 3 gene in neural cells: implications for the pro-inflammatory effects of this transcription factor. J Neuroinflammation 2015; 12:14. [PMID: 25617152 PMCID: PMC4348118 DOI: 10.1186/s12974-014-0223-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 12/16/2014] [Indexed: 11/10/2022] Open
Abstract
Background The CCAAT/enhancer-binding protein β (C/EBPβ) is a transcription factor, which was first identified as a regulator of differentiation and inflammatory processes mainly in adipose tissue and liver; however, its function in the brain was largely unknown for many years. Previous studies from our laboratory indicated that C/EBPβ is implicated in inflammatory process and brain injury, since mice lacking this gene were less susceptible to kainic acid-induced injury. Methods We first performed cDNA microarrays analysis using hippocampal RNA isolated from C/EBPβ+/+ and C/EBPβ−/− mice. Immunocytochemical and immunohistochemical studies were done to evaluate C/EBPβ and C3 levels. Transient transfection experiments were made to analyze transcriptional regulation of C3 by C/EBPβ. To knockdown C/EBPβ and C3 expression, mouse astrocytes were infected with lentiviral particles expressing an shRNA specific for C/EBPβ or an siRNA specific for C3. Results Among the genes displaying significant changes in expression was complement component 3 (C3), which showed a dramatic decrease in mRNA content in the hippocampus of C/EBPβ−/− mice. C3 is the central component of the complement and is implicated in different brain disorders. In this work we have found that C/EBPβ regulates C3 levels in rodents glial in vitro and in the rat Substantia nigra pars compacta (SNpc) in vivo following an inflammatory insult. Analysis of the mouse C3 promoter showed that it is directly regulated by C/EBPβ through a C/EBPβ consensus site located at position −616/-599 of the gene. In addition, we show that depletion of C/EBPβ by a specific shRNA results in a significant decrease in the levels of C3 together with a reduction in the increased levels of pro-inflammatory agents elicited by lipopolysaccharide treatment. Conclusions Altogether, these results indicate that C3 is a downstream target of C/EBPβ, and it could be a mediator of the pro-inflammatory effects of this transcription factor in neural cells.
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Affiliation(s)
- Elena Hernandez-Encinas
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain.
| | - Diana Aguilar-Morante
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain.
| | - Marta Cortes-Canteli
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain. .,Present address: Laboratory of Neurobiology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
| | - Jose A Morales-Garcia
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain.
| | - Elena Gine
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain. .,Departamento de Bioquímica y Biologia Molecular, Facultad de Medicina, UCM, Plaza Ramón y Cajal s/n, 28040, Madrid, Spain.
| | - Angel Santos
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain. .,Departamento de Bioquímica y Biologia Molecular, Facultad de Medicina, UCM, Plaza Ramón y Cajal s/n, 28040, Madrid, Spain.
| | - Ana Perez-Castillo
- Instituto de Investigaciones Biomédicas, (CSIC-UAM), Arturo Duperier, 4, 28029, Madrid, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031, Madrid, Spain.
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97
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Li HY, Deng DH, Huang Y, Ye FH, Huang LL, Xiao Q, Zhang B, Ye BB, Lai YR, Mo ZN, Liu ZF. Favorable prognosis of biallelic CEBPA gene mutations in acute myeloid leukemia patients: a meta-analysis. Eur J Haematol 2015; 94:439-48. [PMID: 25227715 DOI: 10.1111/ejh.12450] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2014] [Indexed: 01/21/2023]
Abstract
OBJECTIVES Increasing number of studies suggested that biallelic CEBPA (bi CEBPA) mutations were associated with favorable prognosis in patients with acute myeloid leukemia (AML), but the results remain inconclusive. We therefore present a meta-analysis to evaluate the prognostic value of bi CEBPA mutations in patients with AML. METHODS A comprehensive literature search was undertaken through August 2014 looking for eligible studies. Pooled hazard ratios (HRs) estimates and 95% confidence intervals (95% CIs) in overall survival (OS) and event-free survival (EFS) were used to calculate estimated effect. RESULTS Ten studies covering a total of 6219 subjects were included in this analysis. Overall, bi CEBPA mutations were associated with favorable clinical outcome in patients with AML (HR for EFS: 0.41, 95% CI: 0.32-0.52; for OS: 0.37, 95% CI: 0.27-0.50), in cytogenetically normal (CN)-AML (HR for EFS: 0.38, 95% CI: 0.29-0.49; for OS: 0.32, 95% CI: 0.23-0.43). When took the cohort of monoallelic CEBPA (mo CEBPA) mutated and wild-type CEBPA (wt CEBPA) AML as a reference group, bi CEBPA mutated AML also shown beneficial outcomes (HR for OS: 0.52, 95% CI: 0.37-0.72). No significant difference was found between mo CEBPA mutation and wt CEBPA in patients with AML or CN-AML (P > 0.05). CONCLUSION Bi CEBPA mutations in patients with AML are strongly associated with a favorable prognosis, which suggested that bi CEBPA mutations would potentially serve as a novel prognostic marker in AML.
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Affiliation(s)
- Hong-Ying Li
- Hematology Department, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
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98
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Abstract
Over the past decade, high-throughput studies have identified many novel transcripts. While their existence is undisputed, their coding potential and functionality have remained controversial. Recent computational approaches guided by ribosome profiling have indicated that translation is far more pervasive than anticipated and takes place on many transcripts previously assumed to be non-coding. Some of these newly discovered translated transcripts encode short, functional proteins that had been missed in prior screens. Other transcripts are translated, but it might be the process of translation rather than the resulting peptides that serves a function. Here, we review annotation studies in zebrafish to discuss the challenges of placing RNAs onto the continuum that ranges from functional protein-encoding mRNAs to potentially non-functional peptide-producing RNAs to non-coding RNAs. As highlighted by the discovery of the novel signaling peptide Apela/ELABELA/Toddler, accurate annotations can give rise to exciting opportunities to identify the functions of previously uncharacterized transcripts.
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Affiliation(s)
- Andrea Pauli
- Department of Molecular and Cellular Biology, Harvard University, MA, USA
| | - Eivind Valen
- Department of Molecular and Cellular Biology, Harvard University, MA, USA
| | - Alexander F. Schier
- Department of Molecular and Cellular Biology, Harvard University, MA, USA
- The Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
- FAS Center for Systems Biology, Harvard University, Cambridge, MA, USA
- Center for Brain Science, Harvard University, Cambridge, MA, USA
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99
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Chen FC. Alternative RNA structure-coupled gene regulations in tumorigenesis. Int J Mol Sci 2014; 16:452-75. [PMID: 25551597 PMCID: PMC4307256 DOI: 10.3390/ijms16010452] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/16/2014] [Indexed: 12/11/2022] Open
Abstract
Alternative RNA structures (ARSs), or alternative transcript isoforms, are critical for regulating cellular phenotypes in humans. In addition to generating functionally diverse protein isoforms from a single gene, ARS can alter the sequence contents of 5'/3' untranslated regions (UTRs) and intronic regions, thus also affecting the regulatory effects of these regions. ARS may introduce premature stop codon(s) into a transcript, and render the transcript susceptible to nonsense-mediated decay, which in turn can influence the overall gene expression level. Meanwhile, ARS can regulate the presence/absence of upstream open reading frames and microRNA targeting sites in 5'UTRs and 3'UTRs, respectively, thus affecting translational efficiencies and protein expression levels. Furthermore, since ARS may alter exon-intron structures, it can influence the biogenesis of intronic microRNAs and indirectly affect the expression of the target genes of these microRNAs. The connections between ARS and multiple regulatory mechanisms underline the importance of ARS in determining cell fate. Accumulating evidence indicates that ARS-coupled regulations play important roles in tumorigenesis. Here I will review our current knowledge in this field, and discuss potential future directions.
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Affiliation(s)
- Feng-Chi Chen
- Institute of Population Health Sciences, National Health Research Institutes, Miaoli County 350, Taiwan.
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100
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Bégay V, Smink JJ, Loddenkemper C, Zimmermann K, Rudolph C, Scheller M, Steinemann D, Leser U, Schlegelberger B, Stein H, Leutz A. Deregulation of the endogenous C/EBPβ LIP isoform predisposes to tumorigenesis. J Mol Med (Berl) 2014; 93:39-49. [PMID: 25401168 DOI: 10.1007/s00109-014-1215-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/17/2014] [Accepted: 10/17/2014] [Indexed: 12/25/2022]
Abstract
UNLABELLED Two long and one truncated isoforms (termed LAP*, LAP, and LIP, respectively) of the transcription factor CCAAT enhancer binding protein beta (C/EBPβ) are expressed from a single intronless Cebpb gene by alternative translation initiation. Isoform expression is sensitive to mammalian target of rapamycin (mTOR)-mediated activation of the translation initiation machinery and relayed through an upstream open reading frame (uORF) on the C/EBPβ mRNA. The truncated C/EBPβ LIP, initiated by high mTOR activity, has been implied in neoplasia, but it was never shown whether endogenous C/EBPβ LIP may function as an oncogene. In this study, we examined spontaneous tumor formation in C/EBPβ knockin mice that constitutively express only the C/EBPβ LIP isoform from its own locus. Our data show that deregulated C/EBPβ LIP predisposes to oncogenesis in many tissues. Gene expression profiling suggests that C/EBPβ LIP supports a pro-tumorigenic microenvironment, resistance to apoptosis, and alteration of cytokine/chemokine expression. The results imply that enhanced translation reinitiation of C/EBPβ LIP promotes tumorigenesis. Accordingly, pharmacological restriction of mTOR function might be a therapeutic option in tumorigenesis that involves enhanced expression of the truncated C/EBPβ LIP isoform. KEY MESSAGE Elevated C/EBPβ LIP promotes cancer in mice. C/EBPβ LIP is upregulated in B-NHL. Deregulated C/EBPβ LIP alters apoptosis and cytokine/chemokine networks. Deregulated C/EBPβ LIP may support a pro-tumorigenic microenvironment.
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Affiliation(s)
- Valérie Bégay
- Department of Tumorigenesis and Cell Differentiation, Max Delbrueck Center for Molecular Medicine, Robert-Roessle-Str.10, 13125, Berlin, Germany
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