1
|
Yengo L, Arredouani A, Marre M, Roussel R, Vaxillaire M, Falchi M, Haoudi A, Tichet J, Balkau B, Bonnefond A, Froguel P. Impact of statistical models on the prediction of type 2 diabetes using non-targeted metabolomics profiling. Mol Metab 2016; 5:918-925. [PMID: 27689004 PMCID: PMC5034686 DOI: 10.1016/j.molmet.2016.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 08/12/2016] [Accepted: 08/16/2016] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE Characterizing specific metabolites in sub-clinical phases preceding the onset of type 2 diabetes to enable efficient preventive and personalized interventions. RESEARCH DESIGN AND METHODS We developed predictive models of type 2 diabetes using two strategies. One strategy focused on the probability of incidence only and was based on logistic regression (MRS1); the other strategy accounted for the age at diagnosis of diabetes and was based on Cox regression (MRS2). We assessed 293 metabolites using non-targeted metabolomics in fasting plasma samples of 1,044 participants (including 231 incident cases over 9 years) used as training population; and fasting serum samples of 128 participants (64 incident cases versus 64 controls) used as validation population. We applied a LASSO-based variable selection aiming at maximizing the out-of-sample area under the receiver operating characteristic curve (AROC) and integrated AROC. RESULTS Sixteen and 17 metabolites were selected for MRS1 and MRS2, respectively, with AROC = 90% and 73% in the training and validation populations, respectively for MRS1. MRS2 had a similar performance and was significantly associated with a younger age of onset of type 2 diabetes (β = -3.44 years per MRS2 SD in the training population, p = 1.56 × 10(-7); β = -4.73 years per MRS2 SD in the validation population, p = 4.04 × 10(-3)). CONCLUSIONS Overall, this study illustrates that metabolomics improves prediction of type 2 diabetes incidence of 4.5% on top of known clinical and biological markers, reaching 90% in total AROC, which is considered the threshold for clinical validity, suggesting it may be used in targeting interventions to prevent type 2 diabetes.
Collapse
Affiliation(s)
- Loic Yengo
- CNRS UMR8199, Pasteur Institute of Lille, Lille, France; European Genomic Institute for Diabetes (EGID), FR-3508, Lille, France; Lille University, France
| | | | - Michel Marre
- INSERM, U1138 (équipe 2: Pathophysiology and Therapeutics of Vascular and Renal Diseases Related to Diabetes, Centre de Recherches des Cordeliers), Paris, France; University Paris 7 Denis Diderot, Sorbonne Paris Cité, France; AP-HP, DHU FIRE, Department of Endocrinology, Diabetology, Nutrition, and Metabolic Diseases, Bichat Claude Bernard Hospital, Paris, France
| | - Ronan Roussel
- INSERM, U1138 (équipe 2: Pathophysiology and Therapeutics of Vascular and Renal Diseases Related to Diabetes, Centre de Recherches des Cordeliers), Paris, France; University Paris 7 Denis Diderot, Sorbonne Paris Cité, France; AP-HP, DHU FIRE, Department of Endocrinology, Diabetology, Nutrition, and Metabolic Diseases, Bichat Claude Bernard Hospital, Paris, France
| | - Martine Vaxillaire
- CNRS UMR8199, Pasteur Institute of Lille, Lille, France; European Genomic Institute for Diabetes (EGID), FR-3508, Lille, France; Lille University, France
| | - Mario Falchi
- Department of Genomics of Common Disease, School of Public Health, Imperial College London, Hammersmith Hospital, London, UK
| | - Abdelali Haoudi
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Beverley Balkau
- INSERM U-1018, CESP, Renal and Cardiovascular Epidemiology, UVSQ-UPS, Villejuif, France
| | - Amélie Bonnefond
- CNRS UMR8199, Pasteur Institute of Lille, Lille, France; European Genomic Institute for Diabetes (EGID), FR-3508, Lille, France; Lille University, France
| | - Philippe Froguel
- CNRS UMR8199, Pasteur Institute of Lille, Lille, France; European Genomic Institute for Diabetes (EGID), FR-3508, Lille, France; Lille University, France; Department of Genomics of Common Disease, School of Public Health, Imperial College London, Hammersmith Hospital, London, UK.
| |
Collapse
|
2
|
|
3
|
Al-Othman S, Haoudi A, Alhomoud S, Alkhenizan A, Khoja T, Al-Zahrani A. Tackling cancer control in the Gulf Cooperation Council Countries. Lancet Oncol 2015; 16:e246-57. [DOI: 10.1016/s1470-2045(15)70034-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
4
|
Reebye V, Sætrom P, Mintz P, Huang K, Swiderski P, Peng L, Liu C, Liu X, Jensen S, Zacharoulis D, Kostomitsopoulos N, Kasahara N, Nicholls J, Jiao L, Pai M, Mizandari M, Chikovani T, Emara M, Haoudi A, Tomalia D, Rossi J, Habib N, Spalding D. Novel RNA oligonucleotide improves liver function and inhibits liver carcinogenesis in vivo. Hepatology 2014; 59:216-27. [PMID: 23929703 PMCID: PMC4655108 DOI: 10.1002/hep.26669] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 07/31/2013] [Indexed: 12/11/2022]
Abstract
UNLABELLED Hepatocellular carcinoma (HCC) occurs predominantly in patients with liver cirrhosis. Here we show an innovative RNA-based targeted approach to enhance endogenous albumin production while reducing liver tumor burden. We designed short-activating RNAs (saRNA) to enhance expression of C/EBPα (CCAAT/enhancer-binding protein-α), a transcriptional regulator and activator of albumin gene expression. Increased levels of both C/EBPα and albumin mRNA in addition to a 3-fold increase in albumin secretion and 50% decrease in cell proliferation was observed in C/EBPα-saRNA transfected HepG2 cells. Intravenous injection of C/EBPα-saRNA in a cirrhotic rat model with multifocal liver tumors increased circulating serum albumin by over 30%, showing evidence of improved liver function. Tumor burden decreased by 80% (P = 0.003) with a 40% reduction in a marker of preneoplastic transformation. Since C/EBPα has known antiproliferative activities by way of retinoblastoma, p21, and cyclins, we used messenger RNA (mRNA) expression liver cancer-specific microarray in C/EBPα-saRNA-transfected HepG2 cells to confirm down-regulation of genes strongly enriched for negative regulation of apoptosis, angiogenesis, and metastasis. Up-regulated genes were enriched for tumor suppressors and positive regulators of cell differentiation. A quantitative polymerase chain reaction (PCR) and western blot analysis of C/EBPα-saRNA-transfected cells suggested that in addition to the known antiproliferative targets of C/EBPα, we also observed suppression of interleukin (IL)6R, c-Myc, and reduced STAT3 phosphorylation. CONCLUSION A novel injectable saRNA-oligonucleotide that enhances C/EBPα expression successfully reduces tumor burden and simultaneously improves liver function in a clinically relevant liver cirrhosis/HCC model.
Collapse
MESH Headings
- Albumins/metabolism
- Animals
- CCAAT-Enhancer-Binding Protein-alpha/metabolism
- Carcinoma, Hepatocellular/complications
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/pathology
- Drug Evaluation, Preclinical
- Gene Expression Regulation
- Genetic Therapy
- Hep G2 Cells
- Humans
- Injections, Intravenous
- Liver/pathology
- Liver Cirrhosis/complications
- Liver Function Tests
- Liver Neoplasms, Experimental/complications
- Liver Neoplasms, Experimental/drug therapy
- Liver Neoplasms, Experimental/pathology
- Male
- Oligonucleotide Array Sequence Analysis
- Proto-Oncogene Proteins c-myc/metabolism
- RNA/therapeutic use
- Rats
- Rats, Wistar
- Receptors, Interleukin-6/metabolism
- STAT3 Transcription Factor/metabolism
Collapse
Affiliation(s)
- V. Reebye
- Department of Surgery and Cancer; Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - P. Sætrom
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7489 Trondheim, Norway
- Department of Computer and Information Science, Norwegian University of Science and Technology, NO-7489 Trondheim, Norway
| | - P.J. Mintz
- Department of Surgery and Cancer; Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - K.W. Huang
- Department of Surgery & Hepatitis Research Center. National Taiwan University Hospital, Taipei City, 10002, Taiwan
- Graduate Institute of Clinical Medicine, National Taiwan University. Taipei City, 10002, Taiwan
| | - P. Swiderski
- Department of Molecular Medicine, Beckman Research Institute of the City of Hope, CA 91010. USA
| | - L. Peng
- Centre Interdisciplinaire de Nanoscience de Marseille, 13288 Marseille, France
| | - C. Liu
- Centre Interdisciplinaire de Nanoscience de Marseille, 13288 Marseille, France
| | - X.X. Liu
- Centre Interdisciplinaire de Nanoscience de Marseille, 13288 Marseille, France
| | - S. Jensen
- Department of Surgery and Cancer; Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - D. Zacharoulis
- Department of Surgery, University Hospital of Larissa Mezourlo, Larisa, Greece
| | - N. Kostomitsopoulos
- Centre for Experimental Surgery, Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece
| | - N. Kasahara
- Department of Medicine, UCLA School of Medicine, Los Angeles, CA 90095-7019, USA
| | - J.P. Nicholls
- Department of Surgery and Cancer; Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - L.R. Jiao
- Department of Surgery and Cancer; Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - M. Pai
- Department of Surgery and Cancer; Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - M. Mizandari
- Department of Radiology. Tbilisi 1 Hospital University Clinic. High Technology Medical Center. Tbilisi, Georgia
| | - T. Chikovani
- Department of Microbiology and Immunology. Faculty of Medicine. Tbilisi State Medical University. Tbilisi, Georgia
| | - M.M. Emara
- Qatar Biomedical Research Institute, Education City, P.O BOX 5825, Doha, Qatar
| | - A. Haoudi
- Qatar Biomedical Research Institute, Education City, P.O BOX 5825, Doha, Qatar
| | - D.A. Tomalia
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - J.J. Rossi
- Division of Molecular Biology, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - N.A. Habib
- Department of Surgery and Cancer; Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | | |
Collapse
|
5
|
Huang KW, Reebye V, Mintz PJ, Saetrom P, Swiderski P, Peng L, Liu C, Liu XX, Jensen SL, Zacharoulis D, Kostomitsopoulos N, Kasahara N, Nicholls J, Jiao LR, Pai M, Spalding D, Farzaneh F, Mizandari M, Chikovani T, Emara M, Haoudi A, Tomalia D, Rossi JJ, Habib NA. Abstract B225: Short activating RNA (saRNA) targeting C/EBPA significantly inhibits cell proliferation of undifferentiated cancer cells. Mol Cancer Ther 2013. [DOI: 10.1158/1535-7163.targ-13-b225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
In general, ‘poorly’ differentiated tumours have a worse prognosis when compared to more ‘well’ differentiated ones. Therefore, the use of a biological agent that could promote differentiation might have a therapeutic advantage. CCAAT enhancer binding protein alpha (C/EBPα) is a transcription factor known to be involved in the regulation of cell differentiation in a number of tissue types. Loss of C/EBPα expression, for example, causes abnormal levels of biliary transcription factors, impaired hepatocyte maturation and liver fibrosis. In contrast C/EBPα overexpression inhibits the development of hepatocellular carcinoma, restores myeloid differentiation and prevents hyperproliferation of hematopoietic cells in acute myeloid leukemia. In this study, we tested the effect of stimulation of C/EBPα expression by a specific small activating RNA (saRNA) on a panel of cell lines representing both well-differentiated and poorly-differentiated cancer cell types. The C/EBPα-saRNA inhibited proliferation of poorly differentiated small cell lung cancer and pancreatic cancer cell lines compared to treatment with scrambled double-stranded RNA controls. However C/EBPα-saRNA was not as effective in suppressing proliferation in well-differentiated insulinoma and breast cancer (MCF7) cell lines. Comparison of endogenous levels of C/EBPα, using qPCR and Western blots, showed that undifferentiated tumour cell lines expressed lower levels of C/EBPα when compared to the well-differentiated tumor types. Gene expression analysis in tumours from xenografts and cirrhotic DEN treated HCC rats, demonstrated that saRNA mediated stimulation of C/EBPα expression, could suppress the steady-state transcript levels for KLF4, OCT3, SOX2, C-Myc and C-Kit. The inhibited expression of these transcription factors correlated with greater expression of differentiation markers and reduced epithelial mesenchymal transition by the C/EBPα saRNA treated cells. Our results suggest that saRNA mediated stimulation of C/EBPα, could be of potential therapeutic value, especially in poorly differentiated cancers. Furthermore, intracellular expression levels of C/EBPα could be an important prognostic factor for predicting the therapeutic response in poor or un-differentiated tumors.
Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B225.
Citation Format: K W. Huang, Vikash Reebye, Paul J. Mintz, Pal Saetrom, Piotr Swiderski, L Peng, C Liu, X X. Liu, Steen Lindkaer Jensen, Dimitris Zacharoulis, Nikos Kostomitsopoulos, Noriyaki Kasahara, Joanna Nicholls, Long R. Jiao, Madhava Pai, Duncan Spalding, Farzin Farzaneh, Malkhaz Mizandari, Tina Chikovani, Mohammed Emara, Abdelali Haoudi, Don Tomalia, John J. Rossi, Nagy A. Habib. Short activating RNA (saRNA) targeting C/EBPA significantly inhibits cell proliferation of undifferentiated cancer cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B225.
Collapse
Affiliation(s)
- K W. Huang
- 1National Taiwan University Hospital, Taipei City, Taiwan
| | | | | | - Pal Saetrom
- 3Norwegian University of Science & Technology, Trondheim, Norway
| | | | - L Peng
- 5Centre Interdiscipinaire de Nanoscience de Marseille, Marseille, France
| | - C Liu
- 5Centre Interdiscipinaire de Nanoscience de Marseille, Marseille, France
| | - X X. Liu
- 5Centre Interdiscipinaire de Nanoscience de Marseille, Marseille, France
| | | | | | | | | | | | - Long R. Jiao
- 2Imperial College London, London, United Kingdom
| | - Madhava Pai
- 2Imperial College London, London, United Kingdom
| | | | | | | | | | | | | | - Don Tomalia
- 12University of Pennsylvania, Philadelphia, PA
| | - John J. Rossi
- 4Beckman Research Institute of the City of Hope, Duarte, CA
| | | |
Collapse
|
6
|
|
7
|
Affiliation(s)
- Nina Luning Prak
- Department of Microbiology and Molecular Cell Biology,
Eastern Virginia Medical School, Norfolk, Virginia 23501, USA
| | - Abdelali Haoudi
- Department of Microbiology and Molecular Cell Biology,
Eastern Virginia Medical School, Norfolk, Virginia 23501, USA
- *Abdelali Haoudi:
| |
Collapse
|
8
|
Dahmani S, Haoudi A, Capet F, Essassi EM, Ng SW. 6-Bromo-1-(1,2-propadien-yl)-3-(2-propyn-yl)-1H-imidazo[4,5-b]pyridin-2(3H)-one. Acta Crystallogr Sect E Struct Rep Online 2010; 66:o755. [PMID: 21580600 PMCID: PMC2983773 DOI: 10.1107/s1600536810007695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 03/01/2010] [Indexed: 11/17/2022]
Abstract
The reaction of propargyl bromide and 6-bromo-1,3-dihydroimidazo[4,5-b]pyridin-2-one in refluxing dimethylformamide yields the title compound, C12H8BrN3O, which features nitrogen-bound propadienyl and propynyl substituents. The imidazolopyridine fused ring is planar (r.m.s. deviation = 0.012 Å); the propadienyl chain is coplanar with the fused ring as it is conjugated with it, whereas the propynyl chain is not as the nitrogen-bound C atom is a methylene linkage. The acetylenic H atom is hydrogen bonded to the carbonyl O atom of an adjacent molecule, forming a helical chain runnning along the b axis.
Collapse
|
9
|
Dahmani S, Haoudi A, Capet F, Essassi EM, Ng SW. 6-Bromo-1,3-di-2-propynyl-1H-imidazo[4,5-b]pyridin-2(3H)-one. Acta Crystallogr Sect E Struct Rep Online 2010; 66:o756. [PMID: 21580601 PMCID: PMC2983980 DOI: 10.1107/s1600536810007701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 03/01/2010] [Indexed: 11/10/2022]
Abstract
The room-temperature reaction of propargyl bromide and 6-bromo-1,3-dihydroimidazo[4,5-b]pyridin-2-one in dimethylformamide yields the title compound, C12H8BrN3O, which features nitrogen-bound propynyl substituents. The imidazopyridine fused ring is almost planar (r.m.s. deviation = 0.011 Å); the propynyl chains point in opposite directions relative to the fused ring. One acetylenic H atom is hydrogen bonded to the carbonyl O atom of an inversion-related molecule, forming a dimer; adjacent dimers are linked by a second acetylene–pyridine C—H⋯N interaction, forming a layer motif.
Collapse
|
10
|
Durkin SS, Guo X, Fryrear KA, Mihaylova VT, Gupta SK, Belgnaoui SM, Haoudi A, Kupfer GM, Semmes OJ. HTLV-1 Tax oncoprotein subverts the cellular DNA damage response via binding to DNA-dependent protein kinase. J Biol Chem 2008; 283:36311-20. [PMID: 18957425 PMCID: PMC2605996 DOI: 10.1074/jbc.m804931200] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Human T-cell leukemia virus type-1 is the causative agent for adult T-cell leukemia. Previous research has established that the viral oncoprotein Tax mediates the transformation process by impairing cell cycle control and cellular response to DNA damage. We showed previously that Tax sequesters huChk2 within chromatin and impairs the response to ionizing radiation. Here we demonstrate that DNA-dependent protein kinase (DNA-PK) is a member of the Tax.Chk2 nuclear complex. The catalytic subunit, DNA-PKcs, and the regulatory subunit, Ku70, were present. Tax-containing nuclear extracts showed increased DNA-PK activity, and specific inhibition of DNA-PK prevented Tax-induced activation of Chk2 kinase activity. Expression of Tax induced foci formation and phosphorylation of H2AX. However, Tax-induced constitutive signaling of the DNA-PK pathway impaired cellular response to new damage, as reflected in suppression of ionizing radiation-induced DNA-PK phosphorylation and gammaH2AX stabilization. Tax co-localized with phospho-DNA-PK into nuclear speckles and a nuclear excluded Tax mutant sequestered endogenous phospho-DNA-PK into the cytoplasm, suggesting that Tax interaction with DNA-PK is an initiating event. We also describe a novel interaction between DNA-PK and Chk2 that requires Tax. We propose that Tax binds to and stabilizes a protein complex with DNA-PK and Chk2, resulting in a saturation of DNA-PK-mediated damage repair response.
Collapse
Affiliation(s)
- Sarah S Durkin
- Department of Microbiology and Molecular Cell Biology, Center for Biomedical Proteomics, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Abstract
Proteomic studies involve the identification as well as qualitative and quantitative comparison of proteins expressed under different conditions, and elucidation of their properties and functions, usually in a large-scale, high-throughput format. The high dimensionality of data generated from these studies will require the development of improved bioinformatics tools and data-mining approaches for efficient and accurate data analysis of biological specimens from healthy and diseased individuals. Mining large proteomics data sets provides a better understanding of the complexities between the normal and abnormal cell proteome of various biological systems, including environmental hazards, infectious agents (bioterrorism) and cancers. This review will shed light on recent developments in bioinformatics and data-mining approaches, and their limitations when applied to proteomics data sets, in order to strengthen the interdependence between proteomic technologies and bioinformatics tools.
Collapse
Affiliation(s)
- Abdelali Haoudi
- Eastern Virginia Medical School, Department of Microbiology & Molecular Cell Biology, George L Wright Center for Biomedical Proteomics, Lewis Hall 3011, Norfolk, VA 23501, USA.
| | | |
Collapse
|
12
|
Belgnaoui SM, Gosden RG, Semmes OJ, Haoudi A. Human LINE-1 retrotransposon induces DNA damage and apoptosis in cancer cells. Cancer Cell Int 2006; 6:13. [PMID: 16670018 PMCID: PMC1464142 DOI: 10.1186/1475-2867-6-13] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Accepted: 05/02/2006] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Long interspersed nuclear elements (LINEs), Alu and endogenous retroviruses (ERVs) make up some 45% of human DNA. LINE-1 also called L1, is the most common family of non-LTR retrotransposons in the human genome and comprises about 17% of the genome. L1 elements require the integration into chromosomal target sites using L1-encoded endonuclease which creates staggering DNA breaks allowing the newly transposed L1 copies to integrate into the genome. L1 expression and retrotransposition in cancer cells might cause transcriptional deregulation, insertional mutations, DNA breaks, and an increased frequency of recombinations, contributing to genome instability. There is however little evidence on the mechanism of L1-induced genetic instability and its impact on cancer cell growth and proliferation. RESULTS We report that L1 has genome-destabilizing effects indicated by an accumulation of gamma-H2AX foci, an early response to DNA strand breaks, in association with an abnormal cell cycle progression through a G2/M accumulation and an induction of apoptosis in breast cancer cells. In addition, we found that adjuvant L1 activation may lead to supra-additive killing when combined with radiation by enhancing the radiation lethality through induction of apoptosis that we have detected through Bax activation. CONCLUSION L1 retrotransposition is sensed as a DNA damaging event through the creation DNA breaks involving L1-encoded endonuclease. The apparent synergistic interaction between L1 activation and radiation can further be utilized for targeted induction of cancer cell death. Thus, the role of retrotransoposons in general, and of L1 in particular, in DNA damage and repair assumes larger significance both for the understanding of mutagenicity and, potentially, for the control of cell proliferation and apoptosis.
Collapse
Affiliation(s)
- S Mehdi Belgnaoui
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
| | - Roger G Gosden
- Center for Reproductive Medicine and Infertility, Weill Medical College, Cornell University, New York, NY 10021, USA
| | - O John Semmes
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
| | - Abdelali Haoudi
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
| |
Collapse
|
13
|
Xie L, Yamamoto B, Haoudi A, Semmes OJ, Green PL. PDZ binding motif of HTLV-1 Tax promotes virus-mediated T-cell proliferation in vitro and persistence in vivo. Blood 2006; 107:1980-8. [PMID: 16263794 PMCID: PMC1895710 DOI: 10.1182/blood-2005-03-1333] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Accepted: 10/13/2005] [Indexed: 12/12/2022] Open
Abstract
HTLV-1 cellular transformation and disease induction is dependent on expression of the viral Tax oncoprotein. PDZ is a modular protein interaction domain used in organizing signaling complexes in eukaryotic cells through recognition of a specific binding motif in partner proteins. Tax-1, but not Tax-2, contains a PDZ-binding domain motif (PBM) that promotes the interaction with several cellular PDZ proteins. Herein, we investigate the contribution of the Tax-1 PBM in HTLV-induced proliferation and immortalization of primary T cells in vitro and viral survival in an infectious rabbit animal model. We generated several HTLV-1 and HTLV-2 Tax viral mutants, including HTLV-1deltaPBM, HTLV-2+C22(+PBM), and HTLV-2+ C18(deltaPBM). All Tax mutants maintained the ability to significantly activate the CREB/ATF or NFkappaB signaling pathways. Microtiter proliferation assays revealed that the Tax-1 PBM significantly increases both HTLV-1- and HTLV-2-induced primary T-cell proliferation. In addition, Tax-1 PBM was responsible for the micronuclei induction activity of Tax-1 relative to that of Tax-2. Viral infection and persistence were severely attenuated in rabbits inoculated with HTLV-1deltaPBM. Our results provide the first direct evidence suggesting that PBM-mediated associations between Tax-1 and cellular proteins play a key role in HTLV-induced cell proliferation and genetic instability in vitro and facilitate viral persistence in vivo.
Collapse
Affiliation(s)
- Li Xie
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Rd, Columbus, OH 43210, USA
| | | | | | | | | |
Collapse
|
14
|
Affiliation(s)
- Halima Bensmail
- Department of Statistics,
The University of Tennessee, Knoxville, TN 37996-0532,
USA
| | - Abdelali Haoudi
- Department of Microbiology and
Molecular Cell Biology, Eastern Virginia Medical
School, Norfolk, VA 23507-1696, USA
- *Abdelali Haoudi:
| |
Collapse
|
15
|
Sioud M, Haoudi A. RNA Interference. J Biomed Biotechnol 2006; 2006:89018. [PMID: 17057373 PMCID: PMC1559938 DOI: 10.1155/jbb/2006/89018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Mouldy Sioud
- Department of immunology, The Norwegian Radium Hospital, Montebello, N-310, Oslo, Norway
- *Mouldy Sioud:
| | - Abdelali Haoudi
- Department of Microbiology and Molecular Cell Biology, George L. Wright Center for Biomedical Proteomics,
Eastern Virginia Medical School, Norfolk, VA 23501, USA
| |
Collapse
|
16
|
Smith MA, Perry G, Zhu X, Haoudi A. Neurodegenerative Diseases: Mechanisms and Therapies. J Biomed Biotechnol 2006; 2006:47539. [PMID: 17047307 PMCID: PMC1698262 DOI: 10.1155/jbb/2006/47539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Mark A. Smith
- Department of Pathology, Case Western Reserve
University, Cleveland, OH 44106, USA
| | - George Perry
- Department of Pathology, Case Western Reserve
University, Cleveland, OH 44106, USA
- College of Sciences, University of Texas at San
Antonio, San Antonio, TX 78249-0661, USA
| | - Xiongwei Zhu
- Department of Pathology, Case Western Reserve
University, Cleveland, OH 44106, USA
- *Xiongwei Zhu:
| | - Abdelali Haoudi
- Department of Microbiology and Molecular Cell
Biology, George L. Wright Center for Biomedical Proteomics, Eastern Virginia Medical School, Norfolk, VA 23501, USA
| |
Collapse
|
17
|
Bensmail H, Aruna B, Semmes OJ, Haoudi A. Functional clustering algorithm for high-dimensional proteomics data. J Biomed Biotechnol 2005; 2005:80-6. [PMID: 16046812 PMCID: PMC1184055 DOI: 10.1155/jbb.2005.80] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 02/10/2005] [Accepted: 02/14/2005] [Indexed: 11/17/2022] Open
Abstract
Clustering proteomics data is a challenging problem for any traditional clustering algorithm. Usually, the number of samples is largely smaller than the number of protein peaks. The use of a clustering algorithm which does not take into consideration the number of features of variables (here the number of peaks) is needed. An innovative hierarchical clustering algorithm may be a good approach. We propose here a new dissimilarity measure for the hierarchical clustering combined with a functional data analysis. We present a specific application of functional data analysis (FDA) to a high-throughput proteomics study. The high performance of the proposed algorithm is compared to two popular dissimilarity measures in the clustering of normal and human T-cell leukemia virus type 1 (HTLV-1)-infected patients samples.
Collapse
Affiliation(s)
- Halima Bensmail
- Department of Statistic Operation and Management Sciences (SOMS),
The University of Tennessee, Knoxville, TN 37996, USA
| | - Buddana Aruna
- Department of Statistic Operation and Management Sciences (SOMS),
The University of Tennessee, Knoxville, TN 37996, USA
| | - O. John Semmes
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Abdelali Haoudi
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| |
Collapse
|
18
|
Abstract
MOTIVATION Bioinformatics clustering tools are useful at all levels of proteomic data analysis. Proteomics studies can provide a wealth of information and rapidly generate large quantities of data from the analysis of biological specimens. The high dimensionality of data generated from these studies requires the development of improved bioinformatics tools for efficient and accurate data analyses. For proteome profiling of a particular system or organism, a number of specialized software tools are needed. Indeed, significant advances in the informatics and software tools necessary to support the analysis and management of these massive amounts of data are needed. Clustering algorithms based on probabilistic and Bayesian models provide an alternative to heuristic algorithms. The number of clusters (diseased and non-diseased groups) is reduced to the choice of the number of components of a mixture of underlying probability. The Bayesian approach is a tool for including information from the data to the analysis. It offers an estimation of the uncertainties of the data and the parameters involved. RESULTS We present novel algorithms that can organize, cluster and derive meaningful patterns of expression from large-scaled proteomics experiments. We processed raw data using a graphical-based algorithm by transforming it from a real space data-expression to a complex space data-expression using discrete Fourier transformation; then we used a thresholding approach to denoise and reduce the length of each spectrum. Bayesian clustering was applied to the reconstructed data. In comparison with several other algorithms used in this study including K-means, (Kohonen self-organizing map (SOM), and linear discriminant analysis, the Bayesian-Fourier model-based approach displayed superior performances consistently, in selecting the correct model and the number of clusters, thus providing a novel approach for accurate diagnosis of the disease. Using this approach, we were able to successfully denoise proteomic spectra and reach up to a 99% total reduction of the number of peaks compared to the original data. In addition, the Bayesian-based approach generated a better classification rate in comparison with other classification algorithms. This new finding will allow us to apply the Fourier transformation for the selection of the protein profile for each sample, and to develop a novel bioinformatic strategy based on Bayesian clustering for biomarker discovery and optimal diagnosis.
Collapse
MESH Headings
- Algorithms
- Bayes Theorem
- Biomarkers/blood
- Cluster Analysis
- Databases, Protein
- Diagnosis, Computer-Assisted/methods
- Diagnosis, Differential
- Fourier Analysis
- Gene Expression Profiling/methods
- Humans
- Leukemia-Lymphoma, Adult T-Cell/blood
- Leukemia-Lymphoma, Adult T-Cell/diagnosis
- Paraparesis, Tropical Spastic/blood
- Paraparesis, Tropical Spastic/diagnosis
- Pattern Recognition, Automated/methods
- Proteome/analysis
- Proteome/metabolism
- Sequence Analysis, Protein/methods
- Signal Processing, Computer-Assisted
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
Collapse
Affiliation(s)
- Halima Bensmail
- Department of Statistics, University of Tennessee, 334 Stokely Management Building, Knoxville, TN 37996-0532, USA
| | | | | | | | | |
Collapse
|
19
|
Haoudi A, Semmes OJ, Mason JM, Cannon RE. Retrotransposition-Competent Human LINE-1 Induces Apoptosis in Cancer Cells With Intact p53. J Biomed Biotechnol 2004; 2004:185-194. [PMID: 15467158 PMCID: PMC555774 DOI: 10.1155/s1110724304403131] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Revised: 04/17/2004] [Accepted: 04/29/2004] [Indexed: 11/17/2022] Open
Abstract
Retrotransposition of human LINE-1 (L1) element, a major representative non-LTR retrotransposon in the human genome, is known to be a source of insertional mutagenesis. However, nothing is known about effects of L1 retrotransposition on cell growth and differentiation. To investigate the potential for such biological effects and the impact that human L1 retrotransposition has upon cancer cell growth, we examined a panel of human L1 transformed cell lines following a complete retrotransposition process. The results demonstrated that transposition of L1 leads to the activation of the p53-mediated apoptotic pathway in human cancer cells that possess a wild-type p53. In addition, we found that inactivation of p53 in cells, where L1 was undergoing retrotransposition, inhibited the induction of apoptosis. This suggests an association between active retrotransposition and a competent p53 response in which induction of apoptosis is a major outcome. These data are consistent with a model in which human retrotransposition is sensed by the cell as a "genetic damaging event" and that massive retrotransposition triggers signaling pathways resulting in apoptosis.
Collapse
Affiliation(s)
- Abdelali Haoudi
- Department of Microbiology and Molecular Cell Biology and Virginia Prostate Center, Eastern Virginia Medical School, Lewis Hall #3011, 700 West Olney Road Norfolk, VA 23501, USA
| | - O. John Semmes
- Department of Microbiology and Molecular Cell Biology and Virginia Prostate Center, Eastern Virginia Medical School, Lewis Hall #3011, 700 West Olney Road Norfolk, VA 23501, USA
| | - James M. Mason
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, Research Triangle Park, NC 27709-2233, USA
| | - Ronald E. Cannon
- Laboratory of Environmental Carcinogenesis and Mutagenesis, National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, Research Triangle Park, NC 27709-2233, USA
| |
Collapse
|
20
|
Haoudi A, Daniels RC, Wong E, Kupfer G, Semmes OJ. Human T-cell leukemia virus-I tax oncoprotein functionally targets a subnuclear complex involved in cellular DNA damage-response. J Biol Chem 2003; 278:37736-44. [PMID: 12842897 DOI: 10.1074/jbc.m301649200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The virally encoded oncoprotein Tax has been implicated in HTLV-1-mediated cellular transformation. The exact mechanism by which this protein contributes to the oncogenic process is not known. However, it has been hypothesized that Tax induces genomic instability via repression of cellular DNA repair. We examined the effect of de novo Tax expression upon the cell cycle, because appropriate activation of cell cycle checkpoints is essential to a robust damage-repair response. Upon induction of tax expression, Jurkat T-cells displayed a pronounced accumulation in G2/M that was reversible by caffeine. We examined the G2-specific checkpoint signaling response in these cells and found activation of the ATM/chk2-mediated pathway, whereas the ATR/chk1-mediated response was unaffected. Immunoprecipitation with anti-chk2 antibody results in co-precipitation of Tax demonstrating a direct interaction of Tax with a chk2-containing complex. We also show that Tax targets a discrete nuclear site and co-localizes with chk2 and not chk1. This nuclear site, previously identified as Tax Speckled Structures (TSS), also contains the early damage response factor 53BP1. The recruitment of 53BP1 to TSS is dependent upon ATM signaling and requires expression of Tax. Specifically, Tax expression induces redistribution of diffuse nuclear 53BP1 to the TSS foci. Taken together these data suggest that the TSS describe a unique nuclear site involved in DNA damage recognition, repair response, and cell cycle checkpoint activation. We suggest that association of Tax with this multifunctional subnuclear site results in disruption of a subset of the site-specific activities and contributes to cellular genomic instability.
Collapse
Affiliation(s)
- Abdelali Haoudi
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23501, USA
| | | | | | | | | |
Collapse
|
21
|
Haoudi A. New Forum for Innovative Research in Biomedicine and Biotechnology. J Biomed Biotechnol 2003; 2003:161. [PMID: 12975530 PMCID: PMC400213 DOI: 10.1155/s1110724303302013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Abdelali Haoudi
- Eastern Virginia Medical School,
Department of Microbiology and Molecular Cell Biology, Lewis Hall #3011, Norfolk, VA 23501, USA
| |
Collapse
|
22
|
Abstract
Transformation of cells by the human T cell leukemia virus type 1 occurs via mechanisms unique among oncogenic retroviruses. A prevailing hypothesis for HTLV-1-mediated cellular transformation is that expression of the viral transactivator, Tax, induces genomic instability. Tax-mediated failure in the cellular repair response is one possible mechanism for loss in genomic integrity. Here we have examined the in vivo repair response of Tax-expressing cells to determine the underlying defects that contribute to loss of genomic integrity. In these studies we examined the effects of de novo Tax-expression in naive "pre-neoplastic" REF52 cells. DNA-damage-induced p53 stabilization and concomitant transient stabilization of p21 were clearly evident in Tax-expressing cells. Likewise, the damage-induced apoptotic response of Tax-expressing cells was normal. However, the damage-induced G1 checkpoint was abrogated in either p53+ or p53- cellular backgrounds. Although nucleotide excision repair (NER) of asynchronous Tax-expressing cells was impaired, cell-cycle-independent assessment of NER in the global excision repair assay demonstrated comparable NER activity in Tax-expressing cells, suggesting that the failure of G1 checkpoint contributes to NER deficiency. Interestingly, we observed a dramatic increase in apoptosis and UV sensitivity of Tax-expressing p53-/- cells when compared to Tax-expressing p53+/+ cells. These data demonstrate that Tax-mediated cellular genomic instability arises from attenuation of cell-cycle checkpoint and imply a clonal dependence on p53 status separate from genomic integrity.
Collapse
Affiliation(s)
- Abdelali Haoudi
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
| | | |
Collapse
|
23
|
Abstract
Now that the human genome is completed, the characterization of
the proteins encoded by the sequence remains a challenging task.
The study of the complete protein complement of the genome, the
“proteome,” referred to as proteomics, will be essential if new
therapeutic drugs and new disease biomarkers for early diagnosis
are to be developed. Research efforts are already underway to
develop the technology necessary to compare the specific protein
profiles of diseased versus nondiseased states. These
technologies provide a wealth of information and rapidly generate
large quantities of data. Processing the large amounts of data
will lead to useful predictive mathematical descriptions of
biological systems which will permit rapid identification of
novel therapeutic targets and identification of metabolic
disorders. Here, we present an overview of the current status and
future research approaches in defining the cancer cell's proteome
in combination with different bioinformatics and computational
biology tools toward a better understanding of health and disease.
Collapse
Affiliation(s)
- Halima Bensmail
- Department of Statistics,
University of Tennessee, Knoxville, TN 37996, USA
| | - Abdelali Haoudi
- Department of
Microbiology and Molecular Cell Biology and the
Virginia Prostate Center, Eastern Virginia
Medical School, 700 West Olney Road, Norfolk,
VA 23501, USA
| |
Collapse
|
24
|
Siriaco GM, Cenci G, Haoudi A, Champion LE, Zhou C, Gatti M, Mason JM. Telomere elongation (Tel), a new mutation in Drosophila melanogaster that produces long telomeres. Genetics 2002; 160:235-45. [PMID: 11805059 PMCID: PMC1461955 DOI: 10.1093/genetics/160.1.235] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In most eukaryotes telomeres are extended by telomerase. Drosophila melanogaster, however, lacks telomerase, and telomere-specific non-LTR retrotransposons, HeT-A and TART, transpose specifically to chromosome ends. A Drosophila strain, Gaiano, that has long telomeres has been identified. We extracted the major Gaiano chromosomes into an Oregon-R genetic background and examined the resulting stocks after 60 generations. In situ hybridization using HeT-A and TART sequences showed that, in stocks carrying either the X or the second chromosome from Gaiano, only the Gaiano-derived chromosomes display long telomeres. However, in stocks carrying the Gaiano third chromosome, all telomeres are substantially elongated, indicating that the Gaiano chromosome 3 carries a factor that increases HeT-A and TART addition to the telomeres. We show that this factor, termed Telomere elongation (Tel), is dominant and localizes as a single unit to 69 on the genetic map. The long telomeres tend to associate with each other in both polytene and mitotic cells. These associations depend on telomere length rather than the presence of Tel. Associations between metaphase chromosomes are resolved during anaphase, suggesting that they are mediated by either proteinaceous links or DNA hydrogen bonding, rather than covalent DNA-DNA bonds.
Collapse
Affiliation(s)
- Giorgia M Siriaco
- Istituto Pasteur Fondazione Cenci Bolognetti, Dipartimento di Genetica e Biologia Molecolare, Universita' di Roma "La Sapienza," Rome, Italy
| | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Chromosome length in Drosophila is maintained by the targeted transposition of two families of non-LTR retrotransposons, HeT-A and TART. Although the rate of transposition to telomeres is sufficient to counterbalance loss from the chromosome ends due to incomplete DNA replication, transposition as a mechanism for elongating chromosome ends raises the possibility of damaged or deleted telomeres, because of its stochastic nature. Recent evidence suggests that HeT-A transposition is controlled at the levels of transcription and reverse transcription. HeT-A transcription is found primarily in mitotically active cells, and transcription of a w+ reporter gene inserted into the 2L telomere increases when the homologous telomere is partially or completely deleted. The terminal HeT-A array may be important as a positive regulator of this activity in cis, and the subterminal satellite appears to be an important negative regulator in cis. A third chromosome modifier has been identified that increases the level of reverse transcriptase activity on a HeT-A RNA template and greatly increases the transposition of HeT-A. Thus, the host appears to play a role in transposition of these elements. Taken together, these results suggest that control of HeT-A transposition is more complex than previously thought.
Collapse
Affiliation(s)
- J M Mason
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709-2233, USA.
| | | | | | | | | | | |
Collapse
|
26
|
Haoudi A, Dhamelincourt P, Mazzah A, Drache M, Conflant P. Vanadium and tellurium siloxane compounds as precursors of vanadium oxide and tellurium oxide silica materials. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1466-6049(01)00028-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
27
|
Haoudi A, Mason JM. Reverse transcriptase can stabilize or destabilize the genome. Genome 2000; 43:949-56. [PMID: 11195348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Telomeres, the eukaryotic chromosome termini, are deoxyribonucleoprotein structures that distinguish natural chromosome ends from broken DNA. In most organisms, telomeres are extended by a reverse transcriptase (RT) with an integrated RNA template, telomerase; in Drosophila melanogaster, however, telomere-specific retrotransposons, HeT-A and TART transpose specifically to chromosome ends. Whether telomeres are extended by a telomerase or by retrotransposons, an RT is a key component. RT has been studied extensively, both for its important role in converting RNA genomes to DNA, which has great evolutionary impact, and as a therapeutic target in human retroviral diseases. Here we discuss a few important aspects of RT usage during retrotransposition and telomere elongation.
Collapse
Affiliation(s)
- A Haoudi
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | | |
Collapse
|
28
|
Abstract
Telomeres, the eukaryotic chromosome termini, are deoxyribonucleoprotein structures that distinguish natural chromosome ends from broken DNA. In most organisms, telomeres are extended by a reverse transcriptase (RT) with an integrated RNA template, telomerase; in Drosophila melanogaster, however, telomere-specific retrotransposons, HeT-A and TART, transpose specifically to chromosome ends. Whether telomeres are extended by a telomerase or by retrotransposons, an RT is a key component. RT has been studied extensively, both for its important role in converting RNA genomes to DNA, which has great evolutionary impact, and as a therapeutic target in human retroviral diseases. Here we discuss a few important aspects of RT usage during retrotransposition and telomere elongation.Key words: telomeres, telomerase, retrotransposons, reverse transcriptase.
Collapse
|
29
|
Haoudi A, Rachidi M, Kim MH, Champion S, Best-Belpomme M, Maisonhaute C. Developmental expression analysis of the 1731 retrotransposon reveals an enhancement of Gag-Pol frameshifting in males of Drosophila melanogaster. Gene 1997; 196:83-93. [PMID: 9322744 DOI: 10.1016/s0378-1119(97)00203-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Extensive analyses of Drosophila melanogaster retrotransposon transcriptions in cultured cells or during development have been reported, but little is known about their translation during the development of the fly. Analysis of the translational products of the 1731 Drosophila melanogaster retrotransposon in Kc Drosophila cultured cells has been reported, showing the existence of primary products (Gag and Pol) and of processed polypeptides of various sizes. Study of 1731 retrotransposon expression at both levels of transcription and translation during the development of Drosophila melanogaster, is presented. 1731 transcripts were detected by in situ hybridization and 1731 proteins were detected by immunostaining and immunoblotting in embryos and in adult gonads. 1731 transcripts and proteins were detected in the mesoderm and central nervous system during embryonic development, in nurse cells and follicle cells in adult ovaries and in primary spermatocytes in adult testes. Moreover, Western blot analysis of the 1731 proteins with anti-Gag or anti-Pol antibodies in gonads revealed that the 1731 mRNA could be translated differentially according to the expressing tissue: essentially, ovarian translation and/or processing of 1731 products is different from that operating in testes, where the Gag-Pol fusion polyprotein is the most prominent product. Our results indicate that expression of the 1731 mobile element is regulated not only at the transcriptional level but also at the translational level, and that this regulation is different in the two sexes.
Collapse
Affiliation(s)
- A Haoudi
- Laboratoire de Genetique Cellulaire et Moleculaire, UA 1135 CNRS, Université Pierre and Marie Curie, Paris, France
| | | | | | | | | | | |
Collapse
|
30
|
Haoudi A, Kim MH, Champion S, Best-Belpomme M, Maisonhaute C. The Gag polypeptides of the Drosophila 1731 retrotransposon are associated to virus-like particles and to nuclei. FEBS Lett 1995; 377:67-72. [PMID: 8543022 DOI: 10.1016/0014-5793(95)01305-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
1731 is a Drosophila melanogaster retrotransposon whose nucleotide sequence shows a proviral architecture with two long terminal repeats (LTRs) framing two internal Open Reading Frames (ORFs). The pol ORF2 of this mobile genetic element was demonstrated to code for an active Reverse Transcriptase (RT) and the ORF1 is expected to code for the structural Gag proteins of the virus-like particles (VLP). Using specific anti-Gag antibodies, we have characterized the 1731 Gag polypeptides expressed either in vitro or in Kc Drosophila melanogaster cultured cells. Together with the 1731 RT, the largest, likely post-translationaly-modified Gag polypeptides are gathered into cytoplasmic virus-like particles. Moreover and consistent with the nuclear localization signal present in the Gag sequence, we observed that a short 1731 Gag polypeptide is associated to the cell nuclei.
Collapse
Affiliation(s)
- A Haoudi
- Laboratoire de Genetique Cellulaire et Moleculaire, UA 1135 CNRS, Université Pierre and Marie Curie, Paris, France
| | | | | | | | | |
Collapse
|
31
|
Haoudi A, Maisonhaute C. The drosophila melanogaster 1731 retro-transposon gag gene: Expression in an in vitro system and in drosophila cultured Kc cells. Biol Cell 1995. [DOI: 10.1016/0248-4900(96)81464-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|