63 results on '"E. Le Rouzic"'
Search Results
2. Structural Basis for E. coli Penicillin Binding Protein (PBP) 2 Inhibition, a Platform for Drug Design
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Damien Bonnard, Sophie Chasset, Jean-Michel Bruneau, François Moreau, Julien Barbion, Audrey Caravano, Francis Chevreuil, Marc Ruff, Benoit Ledoussal, E. Le Rouzic, F. Le Strat, Nicolas Levy, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg (UNISTRA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Les Laboratoires Biodim-Mutabilis, and Biocitech
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Drug ,Penicillin binding proteins ,Sequence analysis ,medicine.drug_class ,Avibactam ,media_common.quotation_subject ,Antibiotics ,Microbial Sensitivity Tests ,Ligands ,01 natural sciences ,03 medical and health sciences ,chemistry.chemical_compound ,Structure-Activity Relationship ,Catalytic Domain ,Drug Discovery ,polycyclic compounds ,medicine ,Escherichia coli ,Penicillin-Binding Proteins ,Homology modeling ,Amino Acid Sequence ,Gene ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,media_common ,0303 health sciences ,biology ,Molecular Structure ,Chemistry ,Escherichia coli Proteins ,Active site ,biochemical phenomena, metabolism, and nutrition ,[SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology ,0104 chemical sciences ,3. Good health ,Anti-Bacterial Agents ,010404 medicinal & biomolecular chemistry ,Biochemistry ,Drug Design ,Pseudomonas aeruginosa ,biology.protein ,Molecular Medicine ,Azabicyclo Compounds ,Sequence Alignment ,Protein Binding - Abstract
Penicillin-binding proteins (PBPs) are the targets of the β-lactams, the most successful class of antibiotics ever developed against bacterial infections. Unfortunately, the worldwide and rapid spread of large spectrum β-lactam resistance genes such as carbapenemases is detrimental to the use of antibiotics in this class. New potent PBP inhibitors are needed, especially compounds that resist β-lactamase hydrolysis. Here we describe the structure of the E. coli PBP2 in its Apo form and upon its reaction with 2 diazabicyclo derivatives, avibactam and CPD4, a new potent PBP2 inhibitor. Examination of these structures shows that unlike avibactam, CPD4 can perform a hydrophobic stacking on Trp370 in the active site of E. coli PBP2. This result, together with sequence analysis, homology modeling, and SAR, allows us to propose CPD4 as potential starting scaffold to develop molecules active against a broad range of bacterial species at the top of the WHO priority list.
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- 2019
3. Demonstration of a Multivendor Path Computation with Optical Feasibility Combining GMPLS and Open Source
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Julien Meuric, Cédric Ware, Jean-Luc Auge, E. Le Rouzic, K. Ndiaye, and Luay Alahdab
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Optical amplifier ,Computer science ,Computation ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,02 engineering and technology ,01 natural sciences ,010309 optics ,020210 optoelectronics & photonics ,Open source ,0103 physical sciences ,Path (graph theory) ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Protocol (object-oriented programming) - Abstract
Openness and interoperability are a challenge in optical networks, especially when it comes to lightpath optical performance estimation. We propose to use a vendor-agnostic open-source tool and extend the OSPF-TE protocol with the required parameters.
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- 2019
4. Easy Optical Defragmentation with SDN Controlled Tunable Transmitter
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Patricia Layec, B. Haentjens, E. Le Rouzic, L. Brameriet, Arnaud Carer, Dominique Verchere, Arnaud Dupas, Q. Pham Van, Nokia Bell Labs [Nozay], Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Algorithmes et architectures adaptatifs pour les systèmes sans-fils efficaces en énergie (GRANIT), ARCHITECTURE (IRISA-D3), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure - Rennes (ENS Rennes)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Vectrawave, Orange Labs, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)
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Service (systems architecture) ,Computer science ,business.industry ,Transmitter ,020206 networking & telecommunications ,02 engineering and technology ,01 natural sciences ,010309 optics ,[INFO.INFO-NI]Computer Science [cs]/Networking and Internet Architecture [cs.NI] ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Defragmentation ,business ,Computer hardware - Abstract
International audience; To ease automatic optical spectrum defragmentation, we present a programmable SDN controlled 100Gbit/s transmitter prototype with a fast wavelength and bitrate switching capabilities. It can be tuned in 0.5 ms over all C-band and used for service hitless defragmentation application.
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- 2018
5. Datarate Adaptation for Night-Time Energy Savings in Core Networks
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E. Le Rouzic, Annalisa Morea, Olivier Rival, and Nicolas Brochier
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Energy conservation ,Engineering ,Core (game theory) ,Signal processing ,Backbone network ,business.industry ,Bandwidth (computing) ,Electronic engineering ,Transceiver ,business ,Adaptation (computer science) ,Atomic and Molecular Physics, and Optics ,Energy (signal processing) - Abstract
We examine how datarate-adaptive transceivers can be used to follow the pronounced variations in requested bandwidth in core networks and therefore allow significant energy savings compared to static networks configured to support the peak traffic all the times. We investigate two schemes for datarate adaptation in optical transceivers: modulation-format adaptation and symbol-rate adaptation, and show how they yield comparable energy savings but through very different mechanisms. We quantify these energy savings with respect to static networks for the case of a European backbone network and find potential for up to 30% of savings when the two schemes are combined.
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- 2013
6. Optical Power Control to Efficiently Handle Flex-Grid Spectrum Gain over Existing Fixed-Grid Network Infrastructures
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Djamel Amar, E. Le Rouzic, Bernard Cousin, Jean-Luc Auge, Nicolas Brochier, Mohamad Kanj, Institut de Recherche Technologique b-com (IRT b-com), Orange Labs [Lannion], France Télécom, Advanced technologies for operated networks (ADOPNET), Université de Rennes (UR)-Télécom Bretagne-RÉSEAUX, TÉLÉCOMMUNICATION ET SERVICES (IRISA-D2), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Télécom Bretagne-RÉSEAUX, TÉLÉCOMMUNICATION ET SERVICES (IRISA-D2), CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure - Rennes (ENS Rennes)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure - Rennes (ENS Rennes)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), and Université de Rennes (UNIV-RENNES)
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Engineering ,Optical power budget ,Grid network ,Optical power ,02 engineering and technology ,01 natural sciences ,010309 optics ,Networking ,[INFO.INFO-NI]Computer Science [cs]/Networking and Internet Architecture [cs.NI] ,020210 optoelectronics & photonics ,Path Computation Algorithm ,Optical networks ,0103 physical sciences ,Power Control ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Optical amplifier ,business.industry ,Amplifier ,Spectral efficiency ,Optical performance monitoring ,Link Design ,Flex-Grid ,GMPLS ,business ,Power control - Abstract
International audience; The exponential traffic growth in optical networks has triggered the evolution from Fixed-Grid to Flex-Grid technology. This evolution allows better spectral efficiency and spectrum usage over current networks in order to facilitate dynamic and huge traffic demands. The integration of Flex-Grid technology increases the number of optical channels established over optical links, leading, however, to an increase in amplification power and possibly saturating optical amplifiers. In this work, we propose a power adaptation process that takes advantage of link optical signal to noise ratio (OSNR) margins to allow network operators to support this power increase while maintaining the use of legacy amplifiers. Results show that controlling channel optical power benefits from the Flex-Grid in terms of spectrum and capacity gain using in-place amplifier infrastructure.
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- 2016
7. An integrated view on monitoring and compensation for dynamic optical networks: from management to physical layer
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E. Le Rouzic, Jose A. Lazaro, Antônio Lúcio Teixeira, Lourena E. Costa, Carmen Vázquez, Ioannis Tomkos, Kyriakos Vlachos, Siamak Azodolmolky, Philippe Gravey, Szilard Zsigmond, T. Loukina, Julio Montalvo, Gerald Franzl, G.M. Tosi-Beleffi, and Tibor Cinkler
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Dynamic network analysis ,Dynamic networks ,Computer Networks and Communications ,Computer science ,Reliability (computer networking) ,Network management and routing ,02 engineering and technology ,Optical performance monitoring ,020210 optoelectronics & photonics ,0202 electrical engineering, electronic engineering, information engineering ,Network performance ,Electrical and Electronic Engineering ,Network architecture ,business.industry ,Physical layer ,020206 networking & telecommunications ,Network layer ,Impairment compensation ,Atomic and Molecular Physics, and Optics ,Reliability engineering ,Network management ,Hardware and Architecture ,Electrónica ,business ,Software ,Computer network - Abstract
A vertical perspective, ranging from management and routing to physical layer options, concerning dynamic network monitoring and compensation of impairments (M&C), is given. Feasibility, reliability, and performance improvements on reconfigurable transparent networks are expected to arise from the consolidated assessment of network management and control specifications, as a more accurate evaluation of available M&C techniques. In the network layer, physical parameters aware algorithms are foreseen to pursue reliable network performance. In the physical layer, some new M&C methods were developed and rating of the state-of-the-art reported in literature is given. Optical monitoring implementation and viability is discussed. Publicado
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- 2009
8. Electrical v/s optical aggregation in multi-layer optical transport networks
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Jose Manuel Rivas-Moscoso, E. Le Rouzic, Dimitrios Klonidis, Erwan Pincemin, Christophe Betoule, Pouria Sayyad Khodashenas, and Gilles Thouenon
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Multiwavelength optical networking ,Engineering ,business.industry ,Optical engineering ,Physics::Optics ,Context (language use) ,Optical performance monitoring ,Traffic grooming ,Optical Transport Network ,Optical networking ,Electronic engineering ,Granularity ,business ,Computer network - Abstract
With optical technology evolution, it becomes possible to perform all optical traffic grooming (AOTG) with a very fine granularity. In the context of flexible optical networking, AOTG paves the way to new possibilities in future transport networks. Finding the best trade-off between electrical and optical aggregation in intrinsically multi-layer transport networks is a complex challenge for operators. This paper compares CAPEX results and resource fill-in performances of electrical and optical aggregation solutions, through a real multilayer transport network case study.
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- 2015
9. Optimization of wavelength division multiplexing in N×160Gbit/s terrestrial transmission systems
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P. Tchofo Dinda, Michel Joindot, Guy Millot, Alessandro Tonello, E. Le Rouzic, Stéphane Pitois, Benjamin Cuenot, and Stephane Gosselin
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Physics ,Optical fiber ,business.industry ,Single-mode optical fiber ,Transmission system ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,Transmission (telecommunications) ,law ,Wavelength-division multiplexing ,Dispersion (optics) ,Dispersion-shifted fiber ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,business ,Self-phase modulation - Abstract
We analyze, from an engineering viewpoint, the prospects of an exploitable upgrade of terrestrial fiber systems based on standard monomode fiber and dispersion compensating units, for future N × 160 Gbit/s transmission systems. We show that dispersion swing, average dispersion and input pulse power are the key parameters that govern the system performances. We show that whenever the dispersion swing is arranged in a symmetrical setup and the compensation ratio is optimized accordingly, one may obtain a significant improvement of the transmission performances.
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- 2005
10. 160-Gb/s optical networking: a prospective techno-economical analysis
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Stephane Gosselin and E. Le Rouzic
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Circuit switching ,Engineering ,business.industry ,Data_CODINGANDINFORMATIONTHEORY ,Network topology ,Optical switch ,Telecommunications network ,Atomic and Molecular Physics, and Optics ,Wavelength-division multiplexing ,Optical networking ,Electronic engineering ,business ,Dimensioning ,Communication channel ,Computer network - Abstract
This paper reports on a network dimensioning analysis of N /spl times/ 160-Gb/s wavelength-division-multiplexed (WDM) networks based on the optical time-division-multiplexing (OTDM) technique. The need for different transmission and networking functions based on innovative circuit-switched scenarios for optical core networks is quantified, and the economical interest of such high-wavelength channel bit rates in the chosen scenarios is evaluated.
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- 2005
11. Alteration of C-MYB DNA binding to cognate responsive elements in HL-60 variant cells
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C Créminon, Bernard Perbal, E Le Rouzic, and C Gaillard
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animal structures ,Genes, myb ,Cellular differentiation ,Blotting, Western ,Electrophoretic Mobility Shift Assay ,HL-60 Cells ,Biology ,DNA-binding protein ,Monocytes ,Pathology and Forensic Medicine ,Proto-Oncogene Proteins c-myb ,Transcriptional regulation ,Humans ,Electrophoretic mobility shift assay ,MYB ,Cloning, Molecular ,Gene ,fungi ,Cell Differentiation ,DNA, Neoplasm ,Original Articles ,Molecular biology ,Neoplasm Proteins ,DNA-Binding Proteins ,Gene Expression Regulation, Neoplastic ,Cell culture ,Tetradecanoylphorbol Acetate ,Cell Division - Abstract
Aims: To establish whether the MYB protein expressed in HL-60 variant cells, which are cells resistant to 12-O-tetradecanoylphorbol-13-acetate (TPA) induced differentiation, is able to bind MYB recognition elements (MREs) involved in the transcriptional regulation of myb target genes. In addition, to determine whether alterations in the binding of the MYB protein to MREs affects HL-60 cell proliferation and differentiation. Methods: Nuclear extracts of HL-60 variant cells exhibiting different degrees of resistance to TPA induced monocytic differentiation were used in electrophoretic mobility shift experiments (EMSAs), bandshift experiments performed with labelled oliogonucleotides containing the MYB consensus binding sequences. Results: The MYB protein contained in nuclear extracts from HL-60 variant cells did not bind efficiently to the MYB recognition elements identified in the mim-1 and PR264 promoters. Molecular cloning of the myb gene and analysis of the MYB protein expressed in the HL-60 variant cells established that the lack of binding did not result from a structural alteration of MYB in these cells. The lack of MRE binding did not abrogate the ability of variant HL-60s to proliferate and to undergo differentiation. Furthermore, the expression of the PR264/SC35 splicing factor was not affected as a result of the altered MYB DNA binding activity. Conclusions: Because the MYB protein expressed in HL-60 variant cells did not appear to be structurally different from the MYB protein expressed in parental HL-60 cells, it is possible that the HL-60 variant cells contain a MYB binding inhibitory factor (MBIF) that interferes with MYB binding on MREs. The increased proliferation rate of HL-60 variant cells and their reduced serum requirement argues against the need for direct MYB binding in the regulation of cell growth.
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- 2002
12. Building a low-energy, transparent optical wide areanetwork with multipaths
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R-M Indre, James Roberts, E. Le Rouzic, Davide Cuda, Télécom ParisTech, Orange Labs [Meylan], Orange Labs, Networks, Algorithms and Probabilities (RAP), Inria Paris-Rocquencourt, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Laboratory of Information, Network and Communication Sciences (LINCS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Recherche en Informatique et en Automatique (Inria)-Institut Mines-Télécom [Paris] (IMT)
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Circuit switching ,Engineering ,Dynamic bandwidth allocation ,Computer Networks and Communications ,business.industry ,Distributed computing ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Overlay network ,020206 networking & telecommunications ,02 engineering and technology ,Optical burst switching ,Network traffic control ,[INFO.INFO-NI]Computer Science [cs]/Networking and Internet Architecture [cs.NI] ,020210 optoelectronics & photonics ,Packet switching ,Burst switching ,Wide area network ,0202 electrical engineering, electronic engineering, information engineering ,Computer Science::Networking and Internet Architecture ,business ,Computer network - Abstract
International audience; We propose an all-optical networking solution for a wide area network built on shared multipoint-to-multipoint lightpaths that, for short, we call "multipaths." A multipath concentrates the traffic of a group of source nodes on a wavelength channel using an adapted medium access control protocol and multicasts this traffic to a group of destination nodes that extract their own data from the confluent stream. The proposed network can be built using existing components and appears less complex and more efficient in terms of energy consumption than alternatives like optical packet switching and optical burst switching. The paper presents the multipath architecture and compares its energy consumption to that of a classical router-based Internet service provider network. A flow-aware dynamic bandwidth allocation algorithm is proposed and shown to have excellent performance in terms of throughput and delay.
- Published
- 2013
13. Alternate architectures for an all-optical core network based on new subwavelength switching paradigms
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E. Le Rouzic, Bernard Arzur, Ramon Aparicio-Pardo, F. Guillemin, Ahmed Triki, and Erwan Pincemin
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Engineering ,Burst switching ,Optical Transport Network ,business.industry ,Network packet ,Label switching ,Core network ,Internet traffic ,Optical IP Switching ,Optical burst switching ,business ,Computer network - Abstract
New time-slotted subwavelength switching paradigms have been proposed as promising solutions to exploit the subwavelength bandwidth overcoming many limitations of traditional optical burst switching (OBS) schemes. Since these new paradigms are based on fix-sized bursts transmitted during time slots, the efficient assembly of IP packets into optical bursts is the first mile stone to reach in the way of the real deployment of all-optical transport networks based on them. Then, in this paper, we propose alternate architectures for implementing such networks and we assess them by studying the efficiency of several burst assembly policies. The study is performed by analyzing real internet traffic extracted from the national transport network of Orange. This is the first time to our knowledge that such study is performed. In this paper we identify the architectures that are viable, in terms of assembly process, for the deployment of such new paradigms in an all-optical core network.
- Published
- 2013
14. Experimental Demonstration of a Contentionless GMPLS-based Light Path Setup using Colourless and Directionless ROADMs
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Julien Meuric, A. Frikha, M.D. Mbaye, and E. Le Rouzic
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Computer science ,business.industry ,Path (graph theory) ,Routing control plane ,business ,Computer network - Abstract
We implement a GMPLS-based control plane that solves the contention problem of Colourless and Directionless (CD) ROADMs. The method is simpler than implementing CD and Contentionless (CD&C) ROADMs and avoids the complex extension of OSPF-TE.
- Published
- 2013
15. Effectiveness of Fiber Lines With Symmetric Dispersion Swing for 160-Gb/s Terrestrial Transmission Systems
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Guy Millot, Stephane Gosselin, J. Fatome, Erwan Pincemin, Stéphane Pitois, Benjamin Cuenot, E. Le Rouzic, and Patrice Tchofo Dinda
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Physics ,Multi-mode optical fiber ,business.industry ,Single-mode optical fiber ,Polarization-maintaining optical fiber ,Graded-index fiber ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Fiber-optic communication ,Optics ,Dispersion (optics) ,Dispersion-shifted fiber ,Electrical and Electronic Engineering ,business ,Plastic optical fiber - Abstract
We demonstrate theoretically and experimentally that a fiber line with a symmetric dispersion swing can substantially improve the performance of 160-Gb/s optical transmissions. The improvement lies in an increased transmission distance and reduction of the optimum input signal power by one order of magnitude compared with that of a conventional system.
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- 2004
16. Physical layer aware network architecture for the future internet
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Antonio Serrador, T. Frantti, Luis M. Correia, E. Le Rouzic, P. Mannersalo, G. Nunzi, Filipe D. Cardoso, and N. Genay
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Computer Networks and Communications ,Network security ,Computer science ,050801 communication & media studies ,02 engineering and technology ,computer.software_genre ,0508 media and communications ,0202 electrical engineering, electronic engineering, information engineering ,Wireless ,Electrical and Electronic Engineering ,Internet ,Network architecture ,Access network ,business.industry ,Physical layer aware ,05 social sciences ,Physical layer ,020206 networking & telecommunications ,Virtualization ,Computer Science Applications ,Information and Communications Technology ,The Internet ,business ,Telecommunications ,computer ,Computer network - Abstract
In this article, physical layer awareness inaccess, core, and metro networks is addressed,and a Physical Layer Aware Network Architec-ture Framework for the Future Internet is pre-sented and discussed, as proposed within theframework of the European ICT Project4WARD. Current limitations and shortcomingsof the Internet architecture are driving researchtrends at a global scale toward a novel, secure,and flexible architecture. This Future Internetarchitecture must allow for the co-existence andcooperation of multiple networks on commonplatforms, through the virtualization of networkresources. Possible solutions embrace a fullrange of technologies, from fiber backbones towireless access networks. The virtualization ofphysical networking resources will enhance thepossibility of handling different profiles, whileproviding the impression of mutual isolation.This abstraction strategy implies the use of wellelaborated mechanisms in order to deal withchannel impairments and requirements, in bothwireless (access) and optical (core) environ-ments. info:eu-repo/semantics/publishedVersion
- Published
- 2012
17. Physical impairment awareness in the context of an operator infrastructure
- Author
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E. Le Rouzic
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Operator (computer programming) ,Risk analysis (engineering) ,Telecommunication network reliability ,business.industry ,Computer science ,Physical layer ,Optical networking ,Context (language use) ,Transparency (human–computer interaction) ,business ,Physical modelling ,Computer network - Abstract
The design and operation of optical transparent networks requires some physical layer awareness that is obtained through physical modelling. We show in this paper that the operator context adds some constraints for the design and use of these models.
- Published
- 2009
18. Enhancing GMPLS Signaling Protocol for Encompassing Quality of Transmission (QoT) in All-Optical Networks
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Nicola Sambo, Alessio Giorgetti, E. Le Rouzic, Filippo Cugini, Piero Castoldi, J. Poirrier, Nicola Andriolli, and Luca Valcarenghi
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Routing protocol ,Computer science ,Resource Reservation Protocol ,computer.internet_protocol ,business.industry ,Distributed computing ,Quality of service ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,020206 networking & telecommunications ,Multiprotocol Label Switching ,02 engineering and technology ,Network topology ,Blocking (statistics) ,Atomic and Molecular Physics, and Optics ,Signaling protocol ,020210 optoelectronics & photonics ,Transmission (telecommunications) ,0202 electrical engineering, electronic engineering, information engineering ,business ,computer ,Computer network - Abstract
In this paper, quality of transmission (QoT)-aware lightpath provisioning schemes for transparent optical networks are proposed and assessed. The main idea is to overcome lightpath blocking due to excessive physical impairments (i.e., unacceptable QoT) by means of successive lightpath set up attempts performed by generalized multiprotocol label switching (GMPLS) signaling protocol along alternate routes. The schemes are enabled by the introduction into current GMPLS signaling protocol [i.e., resource reservation protocol with traffic engineering (RSVP-TE)] of extensions which encompass the QoT parameters that characterize the optical layer. Differently from previous approaches, the proposed GMPLS-based schemes are still distributed but they do not imply the introduction of additional extensions into the routing protocol (e.g., OSPF-TE). The QoT-aware provisioning schemes are first validated by simulations performed on a WDM mesh network. Results show that only few successive set up attempts are required to complete the lightpath establishment. In addition, an experimental demonstration where the proposed RSVP-TE extensions are implemented in the control plane of a transparent metro network is reported showing that impairment-aware lightpath provisioning is achieved on a time scale of few milliseconds.
- Published
- 2008
19. Probe-based schemes to guarantee lightpath quality of transmission (QoT) in transparent optical networks
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E. Le Rouzic, Piero Castoldi, J. Poirrier, Isabella Cerutti, Nicola Sambo, Filippo Cugini, C. Pinart, and Luca Valcarenghi
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Routing protocol ,Engineering ,business.industry ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,020206 networking & telecommunications ,Data_CODINGANDINFORMATIONTHEORY ,02 engineering and technology ,Blocking (statistics) ,020210 optoelectronics & photonics ,Atmospheric measurements ,Quality (physics) ,Transmission (telecommunications) ,0202 electrical engineering, electronic engineering, information engineering ,Bit error rate ,business ,Computer network - Abstract
Two probe-based schemes are proposed to dynamically guarantee lightpath QoT in transparent optical networks. Low blocking and fast set up times are achieved within few lightpath set up attempts.
- Published
- 2008
- Full Text
- View/download PDF
20. GMPLS extensions to encompass shared regenerators in transparent optical networks
- Author
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Piero Castoldi, J. Poirrier, Luca Valcarenghi, Alessio Giorgetti, Filippo Cugini, Nicola Sambo, and E. Le Rouzic
- Subjects
Computer science - Published
- 2007
21. Field trials with channel bit rates of 160 Gbit/s
- Author
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E. Le Rouzic, Sascha Vorbeck, S. Salaiin, Malte Schneiders, K. Sanapi, E. Lach, Michael Schmidt, W. Weiershausen, Ralph Leppla, Fred Buchali, M. Witte, and S.B. Papernyi
- Subjects
Optical amplifier ,Injection locking ,Physics ,Time-division multiplexing ,Polarization mode dispersion ,Gigabit ,Wavelength-division multiplexing ,Electronic engineering ,Terabit ,Forward error correction - Abstract
We present two 8/spl times/170 Gbit/s DWDM/OTDM (1.28 Tbit/s) field transmission experiment both over more than 400 km in commercially operated legacy networks of France Telecom (FT) and Deutsche Telekom (DT), respectively. Conventional EDFA based amplification schemes as well as distributed Raman amplified systems are tested. For different levels of polarization mode dispersion due to different quality of the installed fibre infrastructure adaptive PMD compensation and polarization de-multiplexing is tested.
- Published
- 2006
22. PMD tolerance of 8/spl times/170 Gbit/s field transmission experiment over 430 km SSMF with and without PMDC
- Author
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Fred Buchali, Sascha Vorbeck, Michael Schmidt, Ralph Leppla, Suzanne Salaun, M. Witte, E. Hold, and E. Le Rouzic
- Subjects
Optical amplifier ,Physics ,Optics ,Transmission (telecommunications) ,business.industry ,Gigabit ,Polarization mode dispersion ,Wavelength-division multiplexing ,Bit error rate ,Electronic engineering ,Optical communication ,Optical performance monitoring ,business - Abstract
We report on the impact of PMD in a 8/spl times/170 Gbit/s DWDM transmission experiment over 430 km field installed SSMF with and without PMD compensation. Stable performance is only achieved when using PMDC.
- Published
- 2005
23. Impact of the reach of WDM systems and traffic volume on the network resources and cost of translucent optical transport networks
- Author
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H. Nakajima, B. Decocq, L. Chacon, J.-P. Sebille, E. Le Rouzic, and Annalisa Morea
- Subjects
Cost reduction ,Optical amplifier ,Engineering ,Network element ,Opacity ,business.industry ,Traffic volume ,Wavelength-division multiplexing ,Wdm transmission systems ,Data_CODINGANDINFORMATIONTHEORY ,business ,Computer network - Abstract
The paper studies the impact of ultra long haul WDM transmission systems and traffic volume on the cost of translucent (or hybrid) optical transport networks. The cost of translucent networks is evaluated as a function of the reach of WDM systems using the prices of commercially available network elements and is compared with the cost of the corresponding opaque networks. The results show that a translucent network is approximately 50% cheaper than the opaque counterpart and a further cost reduction can be expected by extending the reach of WDM systems from 1150 km to 2500 km.
- Published
- 2004
24. Alterations of the MDV oncogenic regions in an MDV transformed lymphoblastoid cell line
- Author
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P Thoraval, E Le Rouzic, Y Cherel, M Afanassieff, G Dambrine, Bernard Perbal, Station de Pathologie aviaire et parasitologie [Nouzilly] (PAP), Institut National de la Recherche Agronomique (INRA), Immuno-Endocrinologie Cellulaire et Moléculaire (IECM), and Ecole Nationale Vétérinaire de Nantes-Université de Nantes (UN)-Institut National de la Recherche Agronomique (INRA)
- Subjects
animal structures ,Genes, myb ,T cell ,animal diseases ,viruses ,[SDV]Life Sciences [q-bio] ,Genome, Viral ,medicine.disease_cause ,Lymphoma, T-Cell ,Polymerase Chain Reaction ,Virus ,Pathology and Forensic Medicine ,Transforming Growth Factor beta1 ,03 medical and health sciences ,Viral Proteins ,immune system diseases ,hemic and lymphatic diseases ,medicine ,Marek Disease ,Tumor Cells, Cultured ,Gammaherpesvirinae ,Animals ,Protein Precursors ,Gene ,Herpesvirus 2, Gallid ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,0303 health sciences ,biology ,Virulence ,030306 microbiology ,Lymphoblast ,Nuclear Proteins ,Oncogenes ,Original Articles ,biology.organism_classification ,Cell Transformation, Viral ,Virology ,Peptide Fragments ,medicine.anatomical_structure ,Cell culture ,Trans-Activators ,Carcinogenesis ,Chickens ,Oncovirus - Abstract
Aims: Lymphoblastoid cell lines derived from Marek’s disease virus (MDV) induced tumours have served as models of MDV latency and transformation. They are stable and can be cultured with no detectable MDV genomic alterations upon repeated passaging. An MDV transformed lymphoblastoid T cell line (T9 cell line) has been reported to contain a disrupted MDV BamHI-H fragment and a Rous associated virus insertional activation of the c-myb protooncogene. In an attempt to define the respective participation of c-myb and MDV in the transformed phenotype of T9 cells, an analysis of MDV oncogenic sequences (BamHI-H, BamHI-A, and EcoQ fragments) was performed in these cells. Methods: Using two different passages of the T9 cell line (late and early passages), the organisation of the MDV oncogenic regions and their expression in these cells were analysed. In vivo assessment of the oncogenicity of the virus contained within these cells was assessed by injecting them into 1 day old chickens. Results: In T9 cells maintained in culture for up to six months (late T9), the MDV ICP4 gene was disrupted, whereas the meq gene was actively transcribed. The alterations of the MDV genome in these cells correlated with the inability of the virus to induce the classic signs of Marek’s disease in 1 day old chickens. However, early T9 cells submitted to a limited number of passages induced classic MDV pathogenicity, as efficiently as the MDV control cell line (T5), and did not show gross structural changes in the oncogenic MDV sequences. Conclusions: Although the expression pattern of the MDV oncogenes in early T9 cells was identical to the one reported for other MDV transformed cells, longterm culture of an MDV transformed cell line containing a RAV insertional activation of the c-myb protooncogene led to the disruption of the MDV BamHI-H and BamHI-A oncogenic regions. In the late T9 cells MEQ was the only detected MDV oncoprotein. These results suggest that in the late T9 cells the truncated MYB protein compensates for the loss of MDV oncoproteins and reinforce the possibility that MEQ and MYB cooperate in the maintenance of the transformed state and the tumorigenic potential of these cells.
- Published
- 2002
25. HIV auxiliary proteins: an interface between the virus and the host
- Author
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K, Janvier, C, Petit, E, Le Rouzic, O, Schwartz, S, Benichou, Institut Cochin (UMR_S567 / UMR 8104), Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Rétrovirus et Transfert Génétique, Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), Laboratoire Rétrovirus et Transfert Génétique, Institut Pasteur, Institut Pasteur [Paris], Université Paris Descartes - Paris 5 (UPD5) - Institut National de la Santé et de la Recherche Médicale (INSERM) - Centre National de la Recherche Scientifique (CNRS), Institut Pasteur [Paris] - Centre National de la Recherche Scientifique (CNRS), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)
- Subjects
CD4-Positive T-Lymphocytes ,[SDV] Life Sciences [q-bio] ,Viral Proteins ,Virulence ,[SDV]Life Sciences [q-bio] ,HIV-1 ,Humans ,HIV Infections ,Virus Replication ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 1999
26. Algorithms for the Multi-Period Power-Aware Logical Topology Design With Reconfiguration Costs
- Author
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Luca Chiaraviglio, Edoardo Bonetto, E. Le Rouzic, and Filip Idzikowski
- Subjects
Engineering ,Optimization problem ,Computer Networks and Communications ,business.industry ,Distributed computing ,Logical topology ,Control reconfiguration ,020206 networking & telecommunications ,02 engineering and technology ,Network topology ,Passive optical network ,Power (physics) ,Set (abstract data type) ,020210 optoelectronics & photonics ,0202 electrical engineering, electronic engineering, information engineering ,Heuristics ,business ,Algorithm - Abstract
We tackle the problem of reducing power consumption in IP-over-WDM networks, targeting the power-aware logical topology design (LTD). Unlike the previous work in the literature, our solution reduces the power consumption with consideration of the cost (in terms of reconfigured traffic) incurred when the network is reconfigured. We first formulate the LTD with reconfiguration costs as an optimization problem. Then, we present three heuristics to effectively solve it. We compare our algorithms over an extensive set of networks and scenarios. Results indicate that our algorithms are effective in reducing power consumption while limiting the amount of traffic that is reconfigured. Moreover, we show that the input parameters are intuitive and easy to set, which makes our algorithms more practical.
- Published
- 2013
27. Retroviral insertional activation of the c-myb proto-oncogene in a Marek's disease T-lymphoma cell line
- Author
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E Le Rouzic and Bernard Perbal
- Subjects
animal structures ,viruses ,Virus Integration ,Immunology ,Gene Expression ,Biology ,Lymphoma, T-Cell ,Transfection ,Microbiology ,Virus ,Malignant transformation ,Exon ,Proto-Oncogene Proteins c-myb ,immune system diseases ,Virology ,hemic and lymphatic diseases ,Proto-Oncogene Proteins ,medicine ,Tumor Cells, Cultured ,MYB ,RNA, Messenger ,Herpesvirus 2, Gallid ,Alleles ,Gene Rearrangement ,Marek's disease ,Avian Leukosis Virus ,Deoxyribonuclease BamHI ,medicine.disease ,biology.organism_classification ,Phenotype ,Molecular biology ,Long terminal repeat ,Lymphoma ,Insect Science ,embryonic structures ,DNA, Viral ,Trans-Activators ,Research Article - Abstract
Marek's disease virus (MDV) is an avian herpesvirus that causes, in chickens, a lymphoproliferative disease characterized by malignant transformation of T lymphocytes. The rapid onset of polyclonal tumors indicates the existence of MDV-encoded oncogenic products. However, the molecular basis of MDV-induced lymphoproliferative disease and latency remains largely unclear. Several lines of evidence suggest that MDV and Rous-associated virus (RAV) might cooperate in the development of B-cell lymphomas induced by RAV. Our present results indicate for the first time that MDV and RAV might also act synergistically in the development of T-cell lymphomas. We report an example of an MDV-transformed T-lymphoblastoid cell line (T9) expressing high levels of a truncated C-MYB protein as a result of RAV integration within one c-myb allele. The chimeric RAV-c-myb mRNA species initiated in the 5' long terminal repeat of RAV are deprived of sequences corresponding to c-myb exons 1 to 3. The attenuation of MDV oncogenicity has been strongly related to structural changes in the MDV BamHI-D and BamHI-H DNA fragments. We have established that both DNA restriction fragments are rearranged in the T9 MDV-transformed cells. Our results suggest that retroviral insertional activation of the c-myb proto-oncogene is a critical factor involved in the maintenance of the transformed phenotype and the tumorigenic potential of this T-lymphoma cell line.
- Published
- 1996
28. Effectiveness of fiber lines with symmetric dispersion swing for 160-Gb/s terrestrial transmission systems.
- Author
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J. Fatome, S. Pitois, P.T. Dinda, G. Millot, E. Le Rouzic, B. Cuenot, E. Pincemin, and S. Gosselin
- Abstract
We demonstrate theoretically and experimentally that a fiber line with a symmetric dispersion swing can substantially improve the performance of 160-Gb/s optical transmissions. The improvement lies in an increased transmission distance and reduction of the optimum input signal power by one order of magnitude compared with that of a conventional system. [ABSTRACT FROM PUBLISHER]
- Published
- 2004
- Full Text
- View/download PDF
29. Centralized vs. distributed approaches for encompassing physical impairments in transparent optical networks
- Author
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Alessio Giorgetti, Piero Castoldi, Luca Valcarenghi, Filippo Cugini, E. Le Rouzic, M. J. Poirrier, Francesco Paolucci, Nicola Andriolli, and Nicola Sambo
- Subjects
Routing protocol ,Signaling protocol ,Computer science ,business.industry ,Path computation element ,Distributed computing ,Convergence (routing) ,Scalability ,Transparency (human–computer interaction) ,Routing (electronic design automation) ,business ,Optical mesh network ,Computer network - Abstract
Transparent optical mesh networks are an appealing solution to provide cost-effective high bandwidth connections eliminating the need of expensive intermediate electronic regenerators. However, the implementation of transparent optical networks requires to take into account physical impairment information for effective lightpath set-up. In this paper, we present two distributed solutions to encompass physical impairments based on enhancements of the GMPLS protocol suite. Specifically, both GMPLS routing protocol and signaling protocol extensions are presented and discussed. An alternative centralized approach based on an impairment-aware Path Computation Element (PCE) is also proposed. The distributed routing approach exhibits convergence limitations, while the distributed signaling approach is scalable and effective. The latter is then compared against the centralized PCE approach through simulations considering both a metro network and a more complex WDM network scenario. In addition, experimental implementations of the two approaches are presented. Results show the trade-off of the two approaches, demonstrating the general good performance in terms of lightpath set up time for both approaches.
30. Biological and Structural Analyses of New Potent Allosteric Inhibitors of HIV-1 Integrase.
- Author
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Bonnard D, Le Rouzic E, Singer MR, Yu Z, Le Strat F, Batisse C, Batisse J, Amadori C, Chasset S, Pye VE, Emiliani S, Ledoussal B, Ruff M, Moreau F, Cherepanov P, and Benarous R
- Subjects
- Humans, Virus Replication, Antiviral Agents pharmacology, Allosteric Regulation, HIV Integrase Inhibitors pharmacology, HIV Integrase Inhibitors therapeutic use, HIV Integrase metabolism, HIV Infections drug therapy
- Abstract
HIV-1 integrase-LEDGF allosteric inhibitors (INLAIs) share the binding site on the viral protein with the host factor LEDGF/p75. These small molecules act as molecular glues promoting hyper-multimerization of HIV-1 IN protein to severely perturb maturation of viral particles. Herein, we describe a new series of INLAIs based on a benzene scaffold that display antiviral activity in the single digit nanomolar range. Akin to other compounds of this class, the INLAIs predominantly inhibit the late stages of HIV-1 replication. A series of high-resolution crystal structures revealed how these small molecules engage the catalytic core and the C-terminal domains of HIV-1 IN. No antagonism was observed between our lead INLAI compound BDM-2 and a panel of 16 clinical antiretrovirals. Moreover, we show that compounds retained high antiviral activity against HIV-1 variants resistant to IN strand transfer inhibitors and other classes of antiretroviral drugs. The virologic profile of BDM-2 and the recently completed single ascending dose phase I trial (ClinicalTrials.gov identifier: NCT03634085) warrant further clinical investigation for use in combination with other antiretroviral drugs. Moreover, our results suggest routes for further improvement of this emerging drug class.
- Published
- 2023
- Full Text
- View/download PDF
31. Structural Basis for E. coli Penicillin Binding Protein (PBP) 2 Inhibition, a Platform for Drug Design.
- Author
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Levy N, Bruneau JM, Le Rouzic E, Bonnard D, Le Strat F, Caravano A, Chevreuil F, Barbion J, Chasset S, Ledoussal B, Moreau F, and Ruff M
- Subjects
- Amino Acid Sequence, Anti-Bacterial Agents chemical synthesis, Anti-Bacterial Agents metabolism, Azabicyclo Compounds chemical synthesis, Azabicyclo Compounds metabolism, Catalytic Domain, Drug Design, Escherichia coli chemistry, Escherichia coli Proteins isolation & purification, Escherichia coli Proteins metabolism, Ligands, Microbial Sensitivity Tests, Molecular Structure, Penicillin-Binding Proteins isolation & purification, Penicillin-Binding Proteins metabolism, Protein Binding, Pseudomonas aeruginosa drug effects, Sequence Alignment, Structure-Activity Relationship, Anti-Bacterial Agents pharmacology, Azabicyclo Compounds pharmacology, Escherichia coli drug effects, Escherichia coli Proteins antagonists & inhibitors, Penicillin-Binding Proteins antagonists & inhibitors
- Abstract
Penicillin-binding proteins (PBPs) are the targets of the β-lactams, the most successful class of antibiotics ever developed against bacterial infections. Unfortunately, the worldwide and rapid spread of large spectrum β-lactam resistance genes such as carbapenemases is detrimental to the use of antibiotics in this class. New potent PBP inhibitors are needed, especially compounds that resist β-lactamase hydrolysis. Here we describe the structure of the E. coli PBP2 in its Apo form and upon its reaction with 2 diazabicyclo derivatives, avibactam and CPD4, a new potent PBP2 inhibitor. Examination of these structures shows that unlike avibactam, CPD4 can perform a hydrophobic stacking on Trp370 in the active site of E. coli PBP2. This result, together with sequence analysis, homology modeling, and SAR, allows us to propose CPD4 as potential starting scaffold to develop molecules active against a broad range of bacterial species at the top of the WHO priority list.
- Published
- 2019
- Full Text
- View/download PDF
32. Structure-function analyses unravel distinct effects of allosteric inhibitors of HIV-1 integrase on viral maturation and integration.
- Author
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Bonnard D, Le Rouzic E, Eiler S, Amadori C, Orlov I, Bruneau JM, Brias J, Barbion J, Chevreuil F, Spehner D, Chasset S, Ledoussal B, Moreau F, Saïb A, Klaholz BP, Emiliani S, Ruff M, Zamborlini A, and Benarous R
- Subjects
- Allosteric Regulation, Binding Sites, Cell Line, HIV Integrase Inhibitors chemistry, Humans, Molecular Structure, Pyridines chemistry, Pyridines pharmacology, Structure-Activity Relationship, Thiophenes chemistry, Thiophenes pharmacology, HIV Integrase drug effects, HIV Integrase Inhibitors pharmacology, HIV-1 physiology, Virus Assembly drug effects, Virus Integration drug effects
- Abstract
Recently, a new class of HIV-1 integrase (IN) inhibitors with a dual mode of action, called IN-LEDGF/p75 allosteric inhibitors (INLAIs), was described. Designed to interfere with the IN-LEDGF/p75 interaction during viral integration, unexpectedly, their major impact was on virus maturation. This activity has been linked to induction of aberrant IN multimerization, whereas inhibition of the IN-LEDGF/p75 interaction accounts for weaker antiretroviral effect at integration. Because these dual activities result from INLAI binding to IN at a single binding site, we expected that these activities co-evolved together, driven by the affinity for IN. Using an original INLAI, MUT-A, and its activity on an Ala-125 (A125) IN variant, we found that these two activities on A125-IN can be fully dissociated: MUT-A-induced IN multimerization and the formation of eccentric condensates in viral particles, which are responsible for inhibition of virus maturation, were lost, whereas inhibition of the IN-LEDGF/p75 interaction and consequently integration was fully retained. Hence, the mere binding of INLAI to A125 IN is insufficient to promote the conformational changes of IN required for aberrant multimerization. By analyzing the X-ray structures of MUT-A bound to the IN catalytic core domain (CCD) with or without the Ala-125 polymorphism, we discovered that the loss of IN multimerization is due to stabilization of the A125-IN variant CCD dimer, highlighting the importance of the CCD dimerization energy for IN multimerization. Our study reveals that affinity for the LEDGF/p75-binding pocket is not sufficient to induce INLAI-dependent IN multimerization and the associated inhibition of viral maturation., (© 2018 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2018
- Full Text
- View/download PDF
33. The HIV-1 integrase-LEDGF allosteric inhibitor MUT-A: resistance profile, impairment of virus maturation and infectivity but without influence on RNA packaging or virus immunoreactivity.
- Author
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Amadori C, van der Velden YU, Bonnard D, Orlov I, van Bel N, Le Rouzic E, Miralles L, Brias J, Chevreuil F, Spehner D, Chasset S, Ledoussal B, Mayr L, Moreau F, García F, Gatell J, Zamborlini A, Emiliani S, Ruff M, Klaholz BP, Moog C, Berkhout B, Plana M, and Benarous R
- Subjects
- Cell Line, HIV Antibodies immunology, HIV Integrase Inhibitors chemistry, HIV-1 immunology, Humans, Pyridines chemistry, Thiophenes chemistry, Virus Assembly drug effects, Virus Integration drug effects, Virus Replication drug effects, HIV Integrase metabolism, HIV Integrase Inhibitors pharmacology, HIV-1 drug effects, HIV-1 enzymology, Intercellular Signaling Peptides and Proteins metabolism, Pyridines pharmacology, Thiophenes pharmacology
- Abstract
Background: HIV-1 Integrase (IN) interacts with the cellular co-factor LEDGF/p75 and tethers the HIV preintegration complex to the host genome enabling integration. Recently a new class of IN inhibitors was described, the IN-LEDGF allosteric inhibitors (INLAIs). Designed to interfere with the IN-LEDGF interaction during integration, the major impact of these inhibitors was surprisingly found on virus maturation, causing a reverse transcription defect in target cells., Results: Here we describe the MUT-A compound as a genuine INLAI with an original chemical structure based on a new type of scaffold, a thiophene ring. MUT-A has all characteristics of INLAI compounds such as inhibition of IN-LEDGF/p75 interaction, IN multimerization, dual antiretroviral (ARV) activities, normal packaging of genomic viral RNA and complete Gag protein maturation. MUT-A has more potent ARV activity compared to other INLAIs previously reported, but similar profile of resistance mutations and absence of ARV activity on SIV. HIV-1 virions produced in the presence of MUT-A were non-infectious with the formation of eccentric condensates outside of the core. In studying the immunoreactivity of these non-infectious virions, we found that inactivated HIV-1 particles were captured by anti-HIV-specific neutralizing and non-neutralizing antibodies (b12, 2G12, PGT121, 4D4, 10-1074, 10E8, VRC01) with efficiencies comparable to non-treated virus. Autologous CD4
+ T lymphocyte proliferation and cytokine induction by monocyte-derived dendritic cells (MDDC) pulsed either with MUT-A-inactivated HIV or non-treated HIV were also comparable., Conclusions: Although strongly defective in infectivity, HIV-1 virions produced in the presence of the MUT-A INLAI have a normal protein and genomic RNA content as well as B and T cell immunoreactivities comparable to non-treated HIV-1. These inactivated viruses might form an attractive new approach in vaccine research in an attempt to study if this new type of immunogen could elicit an immune response against HIV-1 in animal models.- Published
- 2017
- Full Text
- View/download PDF
34. The allosteric HIV-1 integrase inhibitor BI-D affects virion maturation but does not influence packaging of a functional RNA genome.
- Author
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van Bel N, van der Velden Y, Bonnard D, Le Rouzic E, Das AT, Benarous R, and Berkhout B
- Subjects
- Acetates chemistry, Allosteric Regulation, Cell Line, Dimerization, Genome, Viral, HEK293 Cells, HIV Integrase metabolism, HIV Integrase Inhibitors chemistry, HIV Reverse Transcriptase chemistry, HIV Reverse Transcriptase metabolism, HIV-1 enzymology, HIV-1 genetics, Humans, Quinolines chemistry, RNA, Transfer metabolism, RNA, Viral isolation & purification, Virus Assembly drug effects, Acetates pharmacology, HIV Integrase chemistry, HIV Integrase Inhibitors pharmacology, HIV-1 physiology, Quinolines pharmacology, RNA, Viral metabolism, Virus Replication drug effects
- Abstract
The viral integrase (IN) is an essential protein for HIV-1 replication. IN inserts the viral dsDNA into the host chromosome, thereby aided by the cellular co-factor LEDGF/p75. Recently a new class of integrase inhibitors was described: allosteric IN inhibitors (ALLINIs). Although designed to interfere with the IN-LEDGF/p75 interaction to block HIV DNA integration during the early phase of HIV-1 replication, the major impact was surprisingly found on the process of virus maturation during the late phase, causing a reverse transcription defect upon infection of target cells. Virus particles produced in the presence of an ALLINI are misformed with the ribonucleoprotein located outside the virus core. Virus assembly and maturation are highly orchestrated and regulated processes in which several viral proteins and RNA molecules closely interact. It is therefore of interest to study whether ALLINIs have unpredicted pleiotropic effects on these RNA-related processes. We confirm that the ALLINI BI-D inhibits virus replication and that the produced virus is non-infectious. Furthermore, we show that the wild-type level of HIV-1 genomic RNA is packaged in virions and these genomes are in a dimeric state. The tRNAlys3 primer for reverse transcription was properly placed on this genomic RNA and could be extended ex vivo. In addition, the packaged reverse transcriptase enzyme was fully active when extracted from virions. As the RNA and enzyme components for reverse transcription are properly present in virions produced in the presence of BI-D, the inhibition of reverse transcription is likely to reflect the mislocalization of the components in the aberrant virus particle.
- Published
- 2014
- Full Text
- View/download PDF
35. Dual inhibition of HIV-1 replication by integrase-LEDGF allosteric inhibitors is predominant at the post-integration stage.
- Author
-
Le Rouzic E, Bonnard D, Chasset S, Bruneau JM, Chevreuil F, Le Strat F, Nguyen J, Beauvoir R, Amadori C, Brias J, Vomscheid S, Eiler S, Lévy N, Delelis O, Deprez E, Saïb A, Zamborlini A, Emiliani S, Ruff M, Ledoussal B, Moreau F, and Benarous R
- Subjects
- Cell Line, Crystallography, X-Ray, HIV Integrase chemistry, HIV Integrase Inhibitors chemistry, Humans, Intercellular Signaling Peptides and Proteins chemistry, Protein Binding, Protein Conformation, HIV Integrase metabolism, HIV Integrase Inhibitors pharmacology, HIV-1 drug effects, HIV-1 physiology, Intercellular Signaling Peptides and Proteins metabolism, Virus Integration drug effects, Virus Replication drug effects
- Abstract
Background: LEDGF/p75 (LEDGF) is the main cellular cofactor of HIV-1 integrase (IN). It acts as a tethering factor for IN, and targets the integration of HIV in actively transcribed gene regions of chromatin. A recently developed class of IN allosteric inhibitors can inhibit the LEDGF-IN interaction., Results: We describe a new series of IN-LEDGF allosteric inhibitors, the most active of which is Mut101. We determined the crystal structure of Mut101 in complex with IN and showed that the compound binds to the LEDGF-binding pocket, promoting conformational changes of IN which explain at the atomic level the allosteric effect of the IN/LEDGF interaction inhibitor on IN functions. In vitro, Mut101 inhibited both IN-LEDGF interaction and IN strand transfer activity while enhancing IN-IN interaction. Time of addition experiments indicated that Mut101 behaved as an integration inhibitor. Mut101 was fully active on HIV-1 mutants resistant to INSTIs and other classes of anti-HIV drugs, indicative that this compound has a new mode of action. However, we found that Mut101 also displayed a more potent antiretroviral activity at a post-integration step. Infectivity of viral particles produced in presence of Mut101 was severely decreased. This latter effect also required the binding of the compound to the LEDGF-binding pocket., Conclusion: Mut101 has dual anti-HIV-1 activity, at integration and post-integration steps of the viral replication cycle, by binding to a unique target on IN (the LEDGF-binding pocket). The post-integration block of HIV-1 replication in virus-producer cells is the mechanism by which Mut101 is most active as an antiretroviral. To explain this difference between Mut101 antiretroviral activity at integration and post-integration stages, we propose the following model: LEDGF is a nuclear, chromatin-bound protein that is absent in the cytoplasm. Therefore, LEDGF can outcompete compound binding to IN in the nucleus of target cells lowering its antiretroviral activity at integration, but not in the cytoplasm where post-integration production of infectious viral particles takes place.
- Published
- 2013
- Full Text
- View/download PDF
36. AT2 Receptor-Interacting Proteins ATIPs in the Brain.
- Author
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Rodrigues-Ferreira S, le Rouzic E, Pawlowski T, Srivastava A, Margottin-Goguet F, and Nahmias C
- Abstract
A complete renin-angiotensin system (RAS) is locally expressed in the brain and fulfills important functions. Angiotensin II, the major biologically active peptide of the RAS, acts via binding to two main receptor subtypes designated AT1 and AT2. The present paper focuses on AT2 receptors, which have been reported to have neuroprotective effects on stroke, degenerative diseases, and cognitive functions. Our group has identified a family of AT2 receptor interacting proteins (ATIPs) comprising three major members (ATIP1, ATIP3, and ATIP4) with different intracellular localization. Of interest, all ATIP members are expressed in brain tissues and carry a conserved domain able to interact with the AT2 receptor intracellular tail, suggesting a role in AT2-mediated brain functions. We summarize here current knowledge on the ATIP family of proteins, and we present new experimental evidence showing interaction defects between ATIP1 and two mutant forms of the AT2 receptor identified in cases of mental retardation. These studies point to a functional role of the AT2/ATIP1 axis in cognition.
- Published
- 2013
- Full Text
- View/download PDF
37. Recruitment of the nuclear form of uracil DNA glycosylase into virus particles participates in the full infectivity of HIV-1.
- Author
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Guenzel CA, Hérate C, Le Rouzic E, Maidou-Peindara P, Sadler HA, Rouyez MC, Mansky LM, and Benichou S
- Subjects
- Cell Line, DNA Glycosylases genetics, HIV Infections virology, HIV-1 genetics, Humans, Protein Binding, Virion genetics, Virus Replication, vpr Gene Products, Human Immunodeficiency Virus genetics, vpr Gene Products, Human Immunodeficiency Virus metabolism, DNA Glycosylases metabolism, HIV Infections enzymology, HIV-1 physiology, Virion physiology
- Abstract
The HIV-1 Vpr protein participates in the early steps of the virus life cycle by influencing the accuracy of reverse transcription. This role of Vpr was related to the recruitment of the nuclear form of the uracil DNA glycosylase (UNG2) enzyme into virus particles, but several conflicting findings have been reported regarding the role of UNG2 encapsidation on viral infectivity. Here, we report that the catalytic activity of UNG2 was not required for influencing HIV-1 mutation, and this function of UNG2 was mapped within a 60-amino-acid domain located in the N-terminal region of the protein required for direct interaction with the p32 subunit of the replication protein A (RPA) complex. Importantly, enforced recruitment of overexpressed UNG2 into virions resulted in a net increase of virus infectivity, and this positive effect on infectivity was also independent of the UNG2 enzymatic activity. In contrast, virus infectivity and replication, as well as the efficiency of the viral DNA synthesis, were significantly reduced when viruses were produced from cells depleted of either endogenous UNG2 or RPA p32. Taken together, these results demonstrate that incorporation of UNG2 into virions has a positive impact on HIV-1 infectivity and replication and positively influences the reverse transcription process through a nonenzymatic mechanism involving the p32 subunit of the RPA complex.
- Published
- 2012
- Full Text
- View/download PDF
38. Molecular insight into how HIV-1 Vpr protein impairs cell growth through two genetically distinct pathways.
- Author
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Maudet C, Bertrand M, Le Rouzic E, Lahouassa H, Ayinde D, Nisole S, Goujon C, Cimarelli A, Margottin-Goguet F, and Transy C
- Subjects
- Amino Acid Motifs, Carrier Proteins genetics, Cell Death genetics, Cullin Proteins genetics, Cullin Proteins metabolism, HEK293 Cells, HIV-1 genetics, HeLa Cells, Humans, Mutation, Protein Serine-Threonine Kinases, Ubiquitin-Protein Ligases, vpr Gene Products, Human Immunodeficiency Virus genetics, Carrier Proteins metabolism, Cell Cycle, HIV-1 metabolism, Models, Biological, vpr Gene Products, Human Immunodeficiency Virus metabolism
- Abstract
Vpr, a small HIV auxiliary protein, hijacks the CUL4 ubiquitin ligase through DCAF1 to inactivate an unknown cellular target, leading to cell cycle arrest at the G(2) phase and cell death. Here we first sought to delineate the Vpr determinants involved in the binding to DCAF1 and to the target. On the one hand, the three α-helices of Vpr are necessary and sufficient for binding to DCAF1; on the other hand, nonlinear determinants in Vpr are required for binding to the target, as shown by using protein chimeras. We also underscore that a SRIG motif conserved in the C-terminal tail of Vpr proteins from HIV-1/SIVcpz and HIV-2/SIVsmm lineages is critical for G(2) arrest. Our results suggest that this motif may be predictive of the ability of Vpr proteins from other SIV lineages to mediate G(2) arrest. We took advantage of the characterization of a subset of G(2) arrest-defective, but DCAF1 binding-proficient mutants, to investigate whether Vpr interferes with cell viability independently of its ability to induce G(2) arrest. These mutants inhibited cell colony formation in HeLa cells and are cytotoxic in lymphocytes, unmasking a G(2) arrest-independent cytopathic effect of Vpr. Furthermore these mutants do not block cell cycle progression at the G(1) or S phases but trigger apoptosis through caspase 3. Disruption of DCAF1 binding restored efficiency of colony formation. However, DCAF1 binding per se is not sufficient to confer cytopathicity. These data support a model in which Vpr recruits DCAF1 to induce the degradation of two host proteins independently required for proper cell growth.
- Published
- 2011
- Full Text
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39. The CDK inhibitor p21Cip1/WAF1 is induced by FcgammaR activation and restricts the replication of human immunodeficiency virus type 1 and related primate lentiviruses in human macrophages.
- Author
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Bergamaschi A, David A, Le Rouzic E, Nisole S, Barré-Sinoussi F, and Pancino G
- Subjects
- Animals, Cells, Cultured, Cyclin-Dependent Kinase Inhibitor p21 antagonists & inhibitors, Cyclin-Dependent Kinase Inhibitor p21 genetics, Gene Knockdown Techniques, HIV-1 immunology, HIV-2 growth & development, HIV-2 immunology, Humans, Lentiviruses, Primate immunology, Primates, Simian Immunodeficiency Virus growth & development, Simian Immunodeficiency Virus immunology, Virus Integration immunology, Virus Replication immunology, Cyclin-Dependent Kinase Inhibitor p21 biosynthesis, HIV-1 growth & development, Lentiviruses, Primate growth & development, Macrophages immunology, Macrophages virology, Receptors, IgG immunology
- Abstract
Macrophages are major targets of human immunodeficiency virus type 1 (HIV-1). We have previously shown that aggregation of activating immunoglobulin G Fc receptors (FcgammaR) by immune complexes inhibits reverse transcript accumulation and integration of HIV-1 and related lentiviruses in monocyte-derived macrophages. Here, we show that FcgammaR-mediated restriction of HIV-1 is not due to enhanced degradation of incoming viral proteins or cDNA and is associated to the induction of the cyclin-dependent kinase inhibitor p21(Cip1/WAF1) (p21). Small interfering RNA-mediated p21 knockdown rescued viral replication in FcgammaR-activated macrophages and enhanced HIV-1 infection in unstimulated macrophages by increasing reverse transcript and integrated DNA levels. p21 induction by other stimuli, such as phorbol myristate acetate and the histone deacetylase inhibitor MS-275, was also associated with preintegrative blocks of HIV-1 replication in macrophages. Binding of p21 to reverse transcription/preintegration complex-associated HIV-1 proteins was not detected in yeast two-hybrid, pulldown, or coimmunoprecipitation assays, suggesting that p21 may affect viral replication independently of a specific interaction with an HIV-1 component. Consistently, p21 silencing rescued viral replication from the FcgammaR-mediated restriction also in simian immunodeficiency virus SIV(mac)- and HIV-2-infected macrophages. Our results point to a role of p21 as an inhibitory factor of lentiviral infection in macrophages and to its implication in FcgammaR-mediated restriction.
- Published
- 2009
- Full Text
- View/download PDF
40. Characterization of the molecular determinants of primary HIV-1 Vpr proteins: impact of the Q65R and R77Q substitutions on Vpr functions.
- Author
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Jacquot G, Le Rouzic E, Maidou-Peindara P, Maizy M, Lefrère JJ, Daneluzzi V, Monteiro-Filho CM, Hong D, Planelles V, Morand-Joubert L, and Benichou S
- Subjects
- Alleles, Amino Acid Sequence, Apoptosis, Genetic Variation, Humans, Leukocytes, Mononuclear cytology, Models, Genetic, Molecular Sequence Data, Mutation, Protein Binding, Ubiquitin-Protein Ligases metabolism, Gene Products, vpr genetics, Genes, vpr, Terminal Repeat Sequences, vpr Gene Products, Human Immunodeficiency Virus genetics
- Abstract
Although HIV-1 Vpr displays several functions in vitro, limited information exists concerning their relevance during infection. Here, we characterized Vpr variants isolated from a rapid and a long-term non-progressor (LTNP). Interestingly, vpr alleles isolated from longitudinal samples of the LTNP revealed a dominant sequence that subsequently led to diversity similar to that observed in the progressor patient. Most of primary Vpr proteins accumulated at the nuclear envelope and interacted with host-cell partners of Vpr. They displayed cytostatic and proapoptotic activities, although a LTNP allele, harboring the Q65R substitution, failed to bind the DCAF1 subunit of the Cul4a/DDB1 E3 ligase and was inactive. This Q65R substitution correlated with impairment of Vpr docking at the nuclear envelope, raising the possibility of a functional link between this property and the Vpr cytostatic activity. In contradiction with published results, the R77Q substitution, found in LTNP alleles, did not influence Vpr proapoptotic activity.
- Published
- 2009
- Full Text
- View/download PDF
41. The human immunodeficiency virus type 2 Vpx protein usurps the CUL4A-DDB1 DCAF1 ubiquitin ligase to overcome a postentry block in macrophage infection.
- Author
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Bergamaschi A, Ayinde D, David A, Le Rouzic E, Morel M, Collin G, Descamps D, Damond F, Brun-Vezinet F, Nisole S, Margottin-Goguet F, Pancino G, and Transy C
- Subjects
- CD4-Positive T-Lymphocytes virology, Cullin Proteins metabolism, DNA-Binding Proteins metabolism, Gene Knockdown Techniques, Gene Silencing, HIV-2 genetics, HIV-2 physiology, HeLa Cells, Humans, Simian Immunodeficiency Virus metabolism, Simian Immunodeficiency Virus physiology, Virus Replication, HIV Infections virology, HIV-2 metabolism, Macrophages virology, Ubiquitin-Protein Ligases metabolism, Viral Regulatory and Accessory Proteins metabolism
- Abstract
The human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) genomes encode several auxiliary proteins that have increasingly shown their importance in the virus-host relationship. One of these proteins, Vpx, is unique to the HIV-2/SIVsm lineage and is critical for viral replication in macrophages. The functional basis for this requirement, as well as the Vpx mode of action, has remained unexplained, and it is all the more enigmatic that HIV type 1 (HIV-1), which has no Vpx counterpart, can infect macrophages. Here, we underscore DCAF1 as a critical host effector of Vpx in its ability to mediate infection and long-term replication of HIV-2 in human macrophages. Vpx assembles with the CUL4A-DDB1 ubiquitin ligase through DCAF1 recruitment. Precluding Vpx present in the incoming virions from recruiting DCAF1 in target macrophages leads to a postentry block characterized by defective accumulation of HIV-2 reverse transcripts. In addition, Vpx from SIVsm functionally complements Vpx-defective HIV-2 in a DCAF1-binding-dependent manner. Altogether, our data point to a mechanism in which Vpx diverts the Cul4A-DDB1(DCAF1) ligase to inactivate an evolutionarily conserved factor, which restricts macrophage infection by HIV-2 and closely related simian viruses.
- Published
- 2009
- Full Text
- View/download PDF
42. Assembly with the Cul4A-DDB1DCAF1 ubiquitin ligase protects HIV-1 Vpr from proteasomal degradation.
- Author
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Le Rouzic E, Morel M, Ayinde D, Belaïdouni N, Letienne J, Transy C, and Margottin-Goguet F
- Subjects
- Cell Cycle, Cell Line, DNA-Binding Proteins metabolism, G2 Phase, Gene Silencing, HeLa Cells, Humans, Models, Biological, Mutation, RNA, Small Interfering metabolism, Virus Replication, Cullin Proteins metabolism, HIV-1 metabolism, Proteasome Endopeptidase Complex metabolism, vpr Gene Products, Human Immunodeficiency Virus metabolism
- Abstract
Many viruses subvert the host ubiquitin-proteasome system to optimize their life cycle. We recently documented such a mechanism for the human immunodeficiency virus type 1 Vpr protein, which promotes cell cycle arrest by recruiting the DCAF1 adaptor of the Cul4A-DDB1 ubiquitin ligase, a finding now confirmed by several groups. Here we examined the impact of Cul4A-DDB1(DCAF1) on Vpr stability. We show that the Vpr(Q65R) mutant, which is defective in DCAF1 binding, undergoes proteasome-mediated degradation at a higher rate than wild-type Vpr. DCAF1 overexpression stabilizes wild-type Vpr and leads to its cytoplasmic accumulation, whereas it has no effect on the Vpr(Q65R) mutant. Conversely, small interfering RNA-mediated silencing of DCAF1 decreases the steady state amount of the viral protein. Stabilization by DCAF1, which is conserved by Vpr species from human immunodeficiency virus type 2 and the SIVmac strain, results in increased G(2) arrest and requires the presence of DDB1, indicating that it occurs through assembly of Vpr with a functional Cul4A-DDB1(DCAF1) complex. Furthermore, in human immunodeficiency virus type 1-infected cells, the Vpr protein, issued from the incoming viral particle, is destabilized under DCAF1 or DDB1 silencing. Together with our previous findings, our data suggest that Cul4A-DDB1(DCAF1) acts at a dual level by providing Vpr with the equipment for the degradation of specific host proteins and by counter-acting its proteasome targeting by another cellular E3 ubiquitin ligase. This protection mechanism may represent an efficient way to optimize the activity of Vpr molecules that are delivered by the incoming virus before neosynthesis takes place. Targeting the Vpr-DCAF1 interaction might therefore present therapeutic interest.
- Published
- 2008
- Full Text
- View/download PDF
43. HIV-1 Vpr: mechanisms of G2 arrest and apoptosis.
- Author
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Andersen JL, Le Rouzic E, and Planelles V
- Subjects
- Humans, vpr Gene Products, Human Immunodeficiency Virus chemistry, vpr Gene Products, Human Immunodeficiency Virus genetics, Apoptosis, G2 Phase, HIV Infections pathology, HIV Infections virology, HIV-1 physiology, vpr Gene Products, Human Immunodeficiency Virus physiology
- Abstract
Since the first isolation of HIV-1 from a patient with generalized lymphadenopathy in 1983, great progress has been made in understanding the viral life cycle and the functional nuances of each of the nine genes encoded by HIV-1. Considerable attention has been paid to four small HIV-1 open reading frames, vif, vpr, vpu and nef. These genes were originally termed "accessory" because their deletion failed to completely disable viral replication in vitro. More than twenty years after the cloning and sequencing of HIV-1, a great deal of information is available regarding the multiple functions of the accessory proteins and it is well accepted that, collectively, these gene products modulate the host cell biology to favor viral replication, and that they are largely responsible for the pathogenesis of HIV-1. Expression of Vpr, in particular, leads to cell cycle arrest in G(2), followed by apoptosis. Here we summarize our current understanding of Vpr biology with a focus on Vpr-induced G(2) arrest and apoptosis.
- Published
- 2008
- Full Text
- View/download PDF
44. Localization of HIV-1 Vpr to the nuclear envelope: impact on Vpr functions and virus replication in macrophages.
- Author
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Jacquot G, Le Rouzic E, David A, Mazzolini J, Bouchet J, Bouaziz S, Niedergang F, Pancino G, and Benichou S
- Subjects
- Active Transport, Cell Nucleus physiology, Cell Cycle, HIV-1 chemistry, HIV-1 metabolism, HeLa Cells, Humans, Two-Hybrid System Techniques, vpr Gene Products, Human Immunodeficiency Virus biosynthesis, vpr Gene Products, Human Immunodeficiency Virus genetics, vpr Gene Products, Human Immunodeficiency Virus metabolism, Cell Nucleus virology, HIV-1 physiology, Macrophages virology, Nuclear Envelope metabolism, Virus Replication, vpr Gene Products, Human Immunodeficiency Virus physiology
- Abstract
Background: HIV-1 Vpr is a dynamic protein that primarily localizes in the nucleus, but a significant fraction is concentrated at the nuclear envelope (NE), supporting an interaction between Vpr and components of the nuclear pore complex, including the nucleoporin hCG1. In the present study, we have explored the contribution of Vpr accumulation at the NE to the Vpr functions, including G2-arrest and pro-apoptotic activities, and virus replication in primary macrophages., Results: In order to define the functional role of Vpr localization at the NE, we have characterized a set of single-point Vpr mutants, and selected two new mutants with substitutions within the first alpha-helix of the protein, Vpr-L23F and Vpr-K27M, that failed to associate with hCG1, but were still able to interact with other known relevant host partners of Vpr. In mammalian cells, these mutants failed to localize at the NE resulting in a diffuse nucleocytoplasmic distribution both in HeLa cells and in primary human monocyte-derived macrophages. Other mutants with substitutions in the first alpha-helix (Vpr-A30L and Vpr-F34I) were similarly distributed between the nucleus and cytoplasm, demonstrating that this helix contains the determinants required for localization of Vpr at the NE. All these mutations also impaired the Vpr-mediated G2-arrest of the cell cycle and the subsequent cell death induction, indicating a functional link between these activities and the Vpr accumulation at the NE. However, this localization is not sufficient, since mutations within the C-terminal basic region of Vpr (Vpr-R80A and Vpr-R90K), disrupted the G2-arrest and apoptotic activities without altering NE localization. Finally, the replication of the Vpr-L23F and Vpr-K27M hCG1-binding deficient mutant viruses was also affected in primary macrophages from some but not all donors., Conclusion: These results indicate that the targeting of Vpr to the nuclear pore complex may constitute an early step toward Vpr-induced G2-arrest and subsequent apoptosis; they also suggest that Vpr targeting to the nuclear pore complex is not absolutely required, but can improve HIV-1 replication in macrophages.
- Published
- 2007
- Full Text
- View/download PDF
45. Regulated degradation of the HIV-1 Vpu protein through a betaTrCP-independent pathway limits the release of viral particles.
- Author
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Estrabaud E, Le Rouzic E, Lopez-Vergès S, Morel M, Belaïdouni N, Benarous R, Transy C, Berlioz-Torrent C, and Margottin-Goguet F
- Subjects
- Animals, Cell Cycle Proteins metabolism, Cell Line, Chlorocebus aethiops, F-Box Proteins metabolism, HIV-1 pathogenicity, Human Immunodeficiency Virus Proteins, Humans, Molecular Sequence Data, Phosphorylation, Ubiquitin metabolism, cdc25 Phosphatases metabolism, Gene Expression Regulation, Viral, HIV-1 genetics, Viral Regulatory and Accessory Proteins metabolism, Virus Replication physiology, beta-Transducin Repeat-Containing Proteins genetics, beta-Transducin Repeat-Containing Proteins metabolism
- Abstract
Viral protein U (Vpu) of HIV-1 has two known functions in replication of the virus: degradation of its cellular receptor CD4 and enhancement of viral particle release. Vpu binds CD4 and simultaneously recruits the betaTrCP subunit of the SCF(betaTrCP) ubiquitin ligase complex through its constitutively phosphorylated DS52GXXS56 motif. In this process, Vpu was found to escape degradation, while inhibiting the degradation of betaTrCP natural targets such as beta-catenin and IkappaBalpha. We further addressed this Vpu inhibitory function with respect to the degradation of Emi1 and Cdc25A, two betaTrCP substrates involved in cell-cycle progression. In the course of these experiments, we underscored the importance of a novel phosphorylation site in Vpu. We show that, especially in cells arrested in early mitosis, Vpu undergoes phosphorylation of the serine 61 residue, which lies adjacent to the betaTrCP-binding motif. This phosphorylation event triggers Vpu degradation by a betaTrCP-independent process. Mutation of Vpu S61 in the HIV-1 provirus extends the half-life of the protein and significantly increases the release of HIV-1 particles from HeLa cells. However, the S61 determinant of regulated Vpu turnover is highly conserved within HIV-1 isolates. Altogether, our results highlight a mechanism where differential phosphorylation of Vpu determines its fate as an adaptor or as a substrate of distinct ubiquitin ligases. Conservation of the Vpu degradation determinant, despite its negative effect on virion release, argues for a role in overall HIV-1 fitness.
- Published
- 2007
- Full Text
- View/download PDF
46. RASSF1C, an isoform of the tumor suppressor RASSF1A, promotes the accumulation of beta-catenin by interacting with betaTrCP.
- Author
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Estrabaud E, Lassot I, Blot G, Le Rouzic E, Tanchou V, Quemeneur E, Daviet L, Margottin-Goguet F, and Benarous R
- Subjects
- Amino Acid Motifs, Cell Nucleus metabolism, Cytoplasm metabolism, Gene Silencing, HeLa Cells, Humans, Protein Binding, RNA, Small Interfering genetics, Tumor Suppressor Proteins genetics, beta Catenin antagonists & inhibitors, beta Catenin biosynthesis, beta Catenin genetics, Tumor Suppressor Proteins metabolism, beta Catenin metabolism, beta-Transducin Repeat-Containing Proteins metabolism
- Abstract
The Ras-association domain family 1 (RASSF1) gene has seven different isoforms; isoform A is a tumor-suppressor gene (RASSF1A). The promoter of RASSF1A is inactivated in many cancers, whereas the expression of another major isoform, RASSF1C, is not affected. Here, we show that RASSF1C, but not RASSF1A, interacts with betaTrCP. Binding of RASSF1C to betaTrCP involves serine 18 and serine 19 of the SS(18)GYXS(19) motif present in RASSF1C but not in RASSF1A. This motif is reminiscent of the canonical phosphorylation motif recognized by betaTrCP; however, surprisingly, the association between RASSF1C and betaTrCP does not occur via the betaTrCP substrate binding domain, the WD40 repeats. Overexpression of RASSF1C, but not of RASSF1A, resulted in accumulation and transcriptional activation of the beta-catenin oncogene, due to inhibition of its betaTrCP-mediated degradation. Silencing of RASSF1A by small interfering RNA was sufficient for beta-catenin to accumulate, whereas silencing of both RASSF1A and RASSF1C had no effect. Thus, RASSF1A and RASSF1C have opposite effects on beta-catenin degradation. Our results suggest that RASSF1C expression in the absence of RASSF1A could play a role in tumorigenesis.
- Published
- 2007
- Full Text
- View/download PDF
47. HIV1 Vpr arrests the cell cycle by recruiting DCAF1/VprBP, a receptor of the Cul4-DDB1 ubiquitin ligase.
- Author
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Le Rouzic E, Belaïdouni N, Estrabaud E, Morel M, Rain JC, Transy C, and Margottin-Goguet F
- Subjects
- Amino Acid Sequence, Cullin Proteins physiology, Cytotoxins physiology, Cytotoxins toxicity, DNA-Binding Proteins physiology, Gene Products, vpr toxicity, HeLa Cells, Humans, Molecular Sequence Data, Protein Transport physiology, Receptor-Interacting Protein Serine-Threonine Kinases physiology, Ubiquitin-Protein Ligases physiology, vpr Gene Products, Human Immunodeficiency Virus, Cell Cycle physiology, Cullin Proteins metabolism, DNA-Binding Proteins metabolism, Gene Products, vpr physiology, HIV-1 physiology, Receptor-Interacting Protein Serine-Threonine Kinases metabolism, Ubiquitin-Protein Ligases metabolism
- Abstract
How the HIV1 Vpr protein initiates the host cell response leading to cell cycle arrest in G(2) has remained unknown. Here, we show that recruitment of DCAF1/VprBP by Vpr is essential for its cytostatic activity, which can be abolished either by single mutations of Vpr that impair DCAF1 binding, or by siRNA-mediated silencing of DCAF1. Furthermore, DCAF1 bridges Vpr to DDB1, a core subunit of Cul4 ubiquitin ligases. Altogether these results point to a mechanism where Vpr triggers G(2) arrest by hijacking the Cul4/DDB1(DCAF1) ubiquitin ligase. We further show that, Vpx, a non-cytostatic Vpr-related protein acquired by HIV2 and SIV, also binds DCAF1 through a conserved motif. Thus, Vpr from HIV1 and Vpx from SIV recruit DCAF1 with different physiological outcomes for the host cell. This in turn suggests that both proteins have evolved to preserve interaction with the same Cul4 ubiquitin ligase while diverging in the recognition of host substrates targeted for proteasomal degradation.
- Published
- 2007
- Full Text
- View/download PDF
48. Development and characterization of ten monoclonal anti-Vpr antibodies.
- Author
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Sabbah EN, Delaunay T, Varin A, Le-Rouzic E, Benichou S, Herbein G, Druillennec S, and Roques BP
- Subjects
- Animals, Antibodies, Monoclonal immunology, Epitope Mapping methods, Female, Humans, Immunoprecipitation methods, Mice, Mice, Inbred BALB C, Surface Plasmon Resonance, vpr Gene Products, Human Immunodeficiency Virus, Antibodies, Monoclonal biosynthesis, Gene Products, vpr immunology, HIV-1 immunology, Leukocytes, Mononuclear virology
- Abstract
HIV-1 Vpr is a 96-amino acid auxiliary protein that performs numerous activities during viral infection. In the present study, 10 antibodies were generated after mice immunization with either the N- or the C-terminus domain of Vpr, respectively, Vpr(1-51) and Vpr(52-96). ELISA and immunoblot experiments using pure synthetic overlapping Vpr peptides suggested that these anti-Vpr antibodies could be classified into five groups and that they recognized conformational or linear Vpr epitopes. Further analysis revealed the effect of C-terminal arginine mutations on the antibody binding. Two of the antibodies precipitated Vpr expressed after transfection of a Vpr-encoding vector in human cells. More importantly, one of them was able to detect Vpr in HIV-1-infected U1 cells and in HIV-1-infected human PBMC. Surface plasmon resonance experiments demonstrated that some of these antibodies prevented the interaction between Vpr and one of its cellular partners, the adenine nucleotide translocator. Thus, these anti-Vpr monoclonal antibodies may be useful to any laboratory working on the molecular mechanism of HIV-1 infection.
- Published
- 2006
- Full Text
- View/download PDF
49. Human immunodeficiency virus type 1 KK26-27 matrix mutants display impaired infectivity, circularization and integration but not nuclear import.
- Author
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Mannioui A, Nelson E, Schiffer C, Felix N, Le Rouzic E, Benichou S, Gluckman JC, and Canque B
- Subjects
- Cell Cycle, Cell Line, Chromatin metabolism, DNA, Viral metabolism, Gene Products, gag genetics, HIV Antigens genetics, HIV-1 metabolism, Humans, Mutation, T-Lymphocytes virology, Viral Proteins genetics, Virus Integration, Virus Replication, gag Gene Products, Human Immunodeficiency Virus, Gene Products, gag physiology, HIV Antigens physiology, HIV-1 physiology, Viral Proteins physiology
- Abstract
We analyzed the role of human immunodeficiency virus (HIV)-1 matrix protein (MA) during the virus replication afferent phase. Single-round infection of H9 T lymphocytes showed that the combined mutation of MA Lys residues 26-27 in MA reported nuclear localization signal (NLS)-1 impaired infectivity, abrogated 2-LTR-circle formation and significantly reduced integration. However, the mutation did not affect viral DNA docking to chromatin in either interphasic or mitotic cells, indicating that MA N-terminal basic domain should not represent a major determinant of HIV-1 nuclear import in T lymphocytes. These data point to a previously unreported role of MA in the late, post-chromatin-binding, afferent phase of HIV-1 replication cycle.
- Published
- 2005
- Full Text
- View/download PDF
50. The Vpr protein from HIV-1: distinct roles along the viral life cycle.
- Author
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Le Rouzic E and Benichou S
- Subjects
- Gene Products, vpr chemistry, Gene Products, vpr genetics, Genes, vpr, HIV-1 genetics, HIV-1 pathogenicity, Humans, Models, Molecular, vpr Gene Products, Human Immunodeficiency Virus, Gene Products, vpr metabolism, HIV-1 physiology, Virus Replication
- Abstract
The genomes of human and simian immunodeficiency viruses (HIV and SIV) encode the gag, pol and env genes and contain at least six supplementary open reading frames termed tat, rev, nef, vif, vpr, vpx and vpu. While the tat and rev genes encode regulatory proteins absolutely required for virus replication, nef, vif, vpr, vpx and vpu encode for small proteins referred to "auxiliary" (or "accessory"), since their expression is usually dispensable for virus growth in many in vitro systems. However, these auxiliary proteins are essential for viral replication and pathogenesis in vivo. The two vpr- and vpx-related genes are found only in members of the HIV-2/SIVsm/SIVmac group, whereas primate lentiviruses from other lineages (HIV-1, SIVcpz, SIVagm, SIVmnd and SIVsyk) contain a single vpr gene. In this review, we will mainly focus on vpr from HIV-1 and discuss the most recent developments in our understanding of Vpr functions and its role during the virus replication cycle.
- Published
- 2005
- Full Text
- View/download PDF
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