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Growth arrest on inhibition of nonsense-mediated decay is mediated by noncoding RNA GAS5. BIOMED RESEARCH INTERNATIONAL 2013; 2013:358015. [PMID: 24319682 PMCID: PMC3844204 DOI: 10.1155/2013/358015] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 09/19/2013] [Indexed: 12/13/2022]
Abstract
Nonsense-mediated decay is a key RNA surveillance mechanism responsible for the rapid degradation of mRNAs containing premature termination codons and hence prevents the synthesis of truncated proteins. More recently, it has been shown that nonsense-mediated decay also has broader significance in controlling the expression of a significant proportion of the transcriptome. The importance of this mechanism to the mammalian cell is demonstrated by the observation that its inhibition causes growth arrest. The noncoding RNA growth arrest specific transcript 5 (GAS5) has recently been shown to play a key role in growth arrest induced by several mechanisms, including serum withdrawal and treatment with the mTOR inhibitor rapamycin. Here we show that inhibition of nonsense-mediated decay in several human lymphocyte cell lines causes growth arrest, and siRNA-mediated downregulation of GAS5 in these cells significantly alleviates the inhibitory effects observed. These observations hold true for inhibition of nonsense-mediated decay both through RNA interference and through pharmacological inhibition by aminoglycoside antibiotics gentamycin and G418. These studies have important implications for ototoxicity and nephrotoxicity caused by gentamycin and for the proposed use of NMD inhibition in treating genetic disease. This report further demonstrates the critical role played by GAS5 in the growth arrest of mammalian cells.
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Kleppe M, Levine RL. New pieces of a puzzle: the current biological picture of MPN. Biochim Biophys Acta Rev Cancer 2012; 1826:415-22. [PMID: 22824378 DOI: 10.1016/j.bbcan.2012.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Revised: 07/12/2012] [Accepted: 07/12/2012] [Indexed: 12/14/2022]
Abstract
Over the last years, we have witnessed significant improvement in our ability to elucidate the genetic events, which contribute to the pathogenesis of acute and chronic leukemias, and also in patients with myeloproliferative neoplasms (MPN). However, despite significant insight into the role of specific mutations, including the JAK2V617F mutation, in MPN pathogenesis, the precise mechanisms by which specific disease alleles contribute to leukemic transformation in MPN remain elusive. Here we review recent studies aimed at understanding the role of downstream signaling pathways in MPN initiation and phenotype, and discuss how these studies have begun to lead to novel insights with biologic, clinical, and therapeutic relevance.
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Affiliation(s)
- Maria Kleppe
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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Chen E, Staudt LM, Green AR. Janus kinase deregulation in leukemia and lymphoma. Immunity 2012; 36:529-41. [PMID: 22520846 DOI: 10.1016/j.immuni.2012.03.017] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Indexed: 12/21/2022]
Abstract
Genetic alterations affecting members of the Janus kinase (JAK) family have been discovered in a wide array of cancers and are particularly prominent in hematological malignancies. In this review, we focus on the role of such lesions in both myeloid and lymphoid tumors. Oncogenic JAK molecules can activate a myriad of canonical downstream signaling pathways as well as directly interact with chromatin in noncanonical processes, the interplay of which results in a plethora of diverse biological consequences. Deciphering these complexities is shedding unexpected light on fundamental cellular mechanisms and will also be important for improved diagnosis, identification of new therapeutic targets, and the development of stratified approaches to therapy.
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Affiliation(s)
- Edwin Chen
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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Polzikov MA, Kordyukova MY, Zavalishina LE, Magoulas C, Zatsepina OV. Development of novel mouse hybridomas producing monoclonal antibodies specific to human and mouse nucleolar protein SURF-6. Hybridoma (Larchmt) 2012; 31:48-53. [PMID: 22316485 PMCID: PMC3275798 DOI: 10.1089/hyb.2011.0078] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 10/12/2011] [Indexed: 01/09/2023]
Abstract
SURF-6 is an evolutionarily conserved nucleolar protein that is important for cell viability; however, its function in mammals still remains uncertain. The aim of this study is to generate monoclonal antibodies to human SURF-6 protein suitable for fundamental and biomedical research. The full-size human SURF-6 was expressed as a recombinant GST-fusion protein and used as an antigen to generate monoclonal antibodies, S79 and S148, specific for SURF-6. The monoclonal antibody produced by hybridoma clone S79 specifically recognizes endogenous SURF-6 by Western and immunofluorescence analyses in various cultured human cells, and by immunohistochemistry in paraffin-embedded sections of human breast cancer samples. Moreover, S79 immunoprecipitates protein complexes containing SURF-6 from HeLa cells extracts. The antibody S79 recognizes SURF-6 only in human cells; however, the antibody produced by hybridoma clone S148 can detect SURF-6 of human and mouse origin. Monoclonal antibodies to the nucleolar protein SURF-6 described in this work can be a useful tool for studies of ribosome biogenesis in normal and cancer cells.
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Affiliation(s)
- Mikhail A Polzikov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya, Moscow, Russia
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Abstract
The JAK2(V617F) mutation is present in the majority of patients with polycythemia vera and one-half of those with essential thrombocythemia and primary myelofibrosis. JAK2(V617F) is a gain-of-function mutation resulting in constitutive JAK2 signaling involved in the pathogenesis of these diseases. JAK2(V617F) has been shown to promote S-phase entry. Here, we demonstrate that the CDC25A phosphatase, a key regulator of the G1/S cell-cycle transition, is constitutively overexpressed in JAK2(V617F)-positive cell lines, JAK2-mutated patient CD36(+) progenitors, and in vitro-differentiated proerythroblasts. Accordingly, CDC25A is overexpressed in BM and spleen of Jak2(V617F) knock-in mice compared with wild-type littermates. By using murine FDC-P1-EPOR and human HEL and SET-2 cell lines, we found that JAK2(V617F)-induced CDC25A up-regulation was caused neither by increased CDC25A transcription or stability nor by the involvement of its upstream regulators Akt and MAPK. Instead, our results suggest that CDC25A is regulated at the translational level through STAT5 and the translational initiation factor eIF2α. CDC25A inhibition reduces the clonogenic and proliferative potential of JAK2(V617F)-expressing cell lines and erythroid progenitors while moderately affecting normal erythroid differentiation. These results suggest that CDC25A deregulation may be involved in hematopoietic cells expansion in JAK2(V617F) patients, making this protein an attracting potential therapeutic target.
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A critical role for non-coding RNA GAS5 in growth arrest and rapamycin inhibition in human T-lymphocytes. Biochem Soc Trans 2011; 39:482-6. [PMID: 21428924 DOI: 10.1042/bst0390482] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Non-coding RNA GAS5 (growth arrest-specific transcript 5) is a 5'-TOP (5'-terminal oligopyrimidine tract) RNA, whose translation, and consequently also stability, is controlled by the mTOR (mammalian target of rapamycin) pathway. GAS5 was identified by functional expression cloning and is necessary and sufficient for normal growth arrest in both leukaemic and untransformed human T-lymphocytes. GAS5 is also required for the inhibitory effects of rapamycin and its analogues on T-cells. The striking functional effects of GAS5 may be mediated through the snoRNAs (small nucleolar RNAs) encoded in its introns and/or through the unusual folding of the mRNA itself, which sequesters, and therefore inhibits, the glucocorticoid receptor.
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Constitutive JunB expression, associated with the JAK2 V617F mutation, stimulates proliferation of the erythroid lineage. Leukemia 2008; 23:144-52. [PMID: 18843287 DOI: 10.1038/leu.2008.275] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The JAK2 V617F mutation, present in the majority of polycythemia vera (PV) patients, causes constitutive activation of JAK2 and seems to be responsible for the PV phenotype. However, the transcriptional changes triggered by the mutation have not yet been totally characterized. In this study, we performed a large-scale gene expression study using serial analysis of gene expression in bone marrow cells of a newly diagnosed PV patient harboring the JAK2 V617F mutation and in normal bone marrow cells of healthy donors. JUNB was one of the genes upregulated in PV, and we confirmed, by quantitative real-time PCR, an overexpression of JUNB in hematopoietic cells of other JAK2 V617F PV patients. Using Ba/F3-EPOR cell lines and primary human erythroblast cultures, we found that JUNB was transcriptionally induced after erythropoietin addition and that JAK2 V617F constitutively induced JunB protein expression. Furthermore, JUNB knockdown reduced not only the growth of Ba/F3 cells by inducing apoptosis, but also the clonogenic and proliferative potential of human erythroid progenitors. These results establish a role for JunB in normal erythropoiesis and indicate that JunB may play a major role in the development of JAK2 V617F myeloproliferative disorders.
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Mourtada-Maarabouni M, Hedge VL, Kirkham L, Farzaneh F, Williams GT. Growth arrest in human T-cells is controlled by the non-coding RNA growth-arrest-specific transcript 5 (GAS5). J Cell Sci 2008; 121:939-46. [PMID: 18354083 DOI: 10.1242/jcs.024646] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The control of growth of lymphocyte populations is crucial to the physiological regulation of the immune system, and to the prevention of both leukaemic and autoimmune disease. This control is mediated through modulation of the cell cycle and regulation of cell death. During log-phase growth the rate of proliferation is high and there is a low rate of cell death. As the population density increases, the cell cycle is extended and apoptosis becomes more frequent as the population enters growth arrest. Here, we show that growth-arrest-specific transcript 5 (GAS5) plays an essential role in normal growth arrest in both T-cell lines and non-transformed lymphocytes. Overexpression of GAS5 causes both an increase in apoptosis and a reduction in the rate of progression through the cell-cycle. Consistent with this, downregulation of endogenous GAS5 inhibits apoptosis and maintains a more rapid cell cycle, indicating that GAS5 expression is both necessary and sufficient for normal growth arrest in T-cell lines as well as human peripheral blood T-cells. Control of apoptosis and the cell cycle by GAS5 has significant consequences for disease pathogenesis, because independent studies have already identified GAS5 as an important candidate gene in the development of autoimmune disease.
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Affiliation(s)
- Mirna Mourtada-Maarabouni
- Institute for Science and Technology in Medicine, Huxley Building, Keele University, Keele, ST5 5BG, UK.
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Dupont S, Massé A, James C, Teyssandier I, Lécluse Y, Larbret F, Ugo V, Saulnier P, Koscielny S, Le Couédic JP, Casadevall N, Vainchenker W, Delhommeau F. The JAK2 617V>F mutation triggers erythropoietin hypersensitivity and terminal erythroid amplification in primary cells from patients with polycythemia vera. Blood 2007; 110:1013-21. [PMID: 17389763 DOI: 10.1182/blood-2006-10-054940] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Abstract
The JAK2 617V>F mutation is frequent in polycythemia vera (PV) and essential thrombocythemia (ET). Using quantitative polymerase chain reaction (PCR), we found that high levels of JAK2 617V>F in PV correlate with increased granulocytes and high levels of hemoglobin and endogenous erythroid colony formation. We detected normal progenitors and those that were heterozygous or homozygous for the mutation by genotyping ET and PV clonal immature and committed progenitors. In PV patients, we distinguished homozygous profiles with normal, heterozygous, and homozygous progenitors from heterozygous profiles with only heterozygous and normal progenitors. PV patients with a heterozygous profile had more mutated, committed progenitors than did other PV and ET patients, suggesting a selective amplification of mutated cells in the early phases of hematopoiesis. We demonstrated that mutated erythroid progenitors were more sensitive to erythropoietin than normal progenitors, and that most homozygous erythroid progenitors were erythropoietin independent. Moreover, we observed a greater in vitro erythroid amplification and a selective advantage in vivo for mutated cells in late stages of hematopoiesis. These results suggest that, for PV, erythrocytosis can occur through two mechanisms: terminal erythroid amplification triggered by JAK2 617V>F homozygosity, and a 2-step process including the upstream amplification of heterozygous cells that may involve additional molecular events.
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Affiliation(s)
- Sabrina Dupont
- INSERM Unité 790, Universite Paris Sud, Institut Gustave Roussy, 39 rue Camille Desmoulins, 94805 Villejuif, France
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Gelsi-Boyer V, Cervera N, Bertucci F, Trouplin V, Remy V, Olschwang S, Chaffanet M, Vey N, Mozziconacci MJ, Birnbaum D. Gene expression profiling separates chronic myelomonocytic leukemia in two molecular subtypes. Leukemia 2007; 21:2359-62. [PMID: 17568812 DOI: 10.1038/sj.leu.2404805] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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