Étude de la fonction anti-apoptotique de la sous-unité R1 de la ribonucléotide réductase des virus de l’herpès simplex

L’élimination des cellules infectées par apoptose constitue un mécanisme de défense antivirale. Les virus de l’herpès simplex (HSV) de type 1 et 2 encodent des facteurs qui inhibent l’apoptose induite par la réponse antivirale. La sous-unité R1 de la ribonucléotide réductase d’HSV-2 (ICP10) possède une fonction anti-apoptotique qui protège les cellules épithéliales de l’apoptose induite par les récepteurs de mort en agissant en amont ou au niveau de l’activation de la procaspase-8. Puisqu’une infection avec un mutant HSV-1 déficient pour la R1 diminue la résistance des cellules infectées vis à vis du TNFα, il a été suggéré que la R1 d’HSV-1 (ICP6) pourrait posséder une fonction anti-apoptotique. Le but principal de cette thèse est d’étudier le mécanisme et le potentiel de la fonction anti-apoptotique de la R1 d’HSV-1 et de la R1 d'HSV-2. Dans une première étude, nous avons investigué le mécanisme de la fonction anti-apoptotique de la R1 d’HSV en utilisant le TNFα et le FasL, deux inducteurs des récepteurs de mort impliqués dans la réponse immune anti-HSV. Cette étude a permis d’obtenir trois principaux résultats concernant la fonction anti-apoptotique de la R1 d’HSV. Premièrement, la R1 d’HSV-1 inhibe l’apoptose induite par le TNFα et par le FasL aussi efficacement que la R1 d’HSV-2. Deuxièmement, la R1 d’HSV-1 est essentielle à l’inhibition de l’apoptose induite par le FasL. Troisièmement, la R1 d’HSV interagit constitutivement avec la procaspase-8 d’une manière qui inhibe la dimérisation et donc l’activation de la caspase-8. Ces résultats suggèrent qu’en plus d’inhiber l’apoptose induite par les récepteurs de mort la R1 d’HSV peut prévenir l’activation de la caspase-8 induite par d’autres stimuli pro-apoptotiques. Les ARN double-brins (ARNdb) constituant un intermédiaire de la transcription du génome des HSV et activant l’apoptose par une voie dépendante de la caspase-8, nous avons testé dans une seconde étude l’impact de la R1 d’HSV sur l’apoptose induite par l’acide polyriboinosinique : polyribocytidylique (poly(I:C)), un analogue synthétique des ARNdb. Ces travaux ont montré qu’une infection avec les HSV protège les cellules épithéliales de l’apoptose induite par le poly(I:C). La R1 d’HSV-1 joue un rôle majeur dans l’inhibition de l’activation de la caspase-8 induite par le poly(I:C). La R1 d’HSV interagit non seulement avec la procaspase-8 mais aussi avec RIP1 (receptor interacting protein 1). En interagissant avec RIP1, la R1 d’HSV-2 inhibe l’interaction entre RIP1 et TRIF (Toll/interleukine-1 receptor-domain-containing adapter-inducing interferon β), l’adaptateur du Toll-like receptor 3 qui est un détecteur d’ARNdb , laquelle est essentielle pour signaler l’apoptose induite par le poly(I:C) extracellulaire et la surexpression de TRIF. Ces travaux démontrent la capacité de la R1 d’HSV à inhiber l’apoptose induite par divers stimuli et ils ont permis de déterminer le mécanisme de l’activité anti-apoptotique de la R1 d’HSV. Très tôt durant l’infection, cFLIP, un inhibiteur cellulaire de la caspase-8, est dégradé alors que la R1 d’HSV s’accumule de manière concomitante. En interagissant avec la procapsase-8 et RIP1, la R1 d’HSV se comporte comme un inhibiteur viral de l’activation de la procaspase-8 inhibant l’apoptose induite par les récepteurs de mort et les détecteurs aux ARNdb.Elimination of infected cells by apoptosis constitutes an ancestral mechanism of host defense against viral infection. Herpes simplex viruses (HSVs) encode several viral factors to counteract the apoptotic antiviral response. Among them, the R1 subunit of HSV type-2 ribonucleotide reductase (HSV-2 R1, also named ICP10), protects cells by interrupting death receptor-mediated signaling at, or upstream of, caspase-8 activation. Since protection against tumor necrosis factor alpha (TNFα)-induced apoptosis is decreased un cells infected with an HSV type-1 R1 null mutant, it has been proposed that HSV-1 R1 (ICP6) could also possess an antiapoptotic activity. The fundamental goal of this thesis is to better understand the mechanism and the potential of the HSV R1s antiapoptotic activity. In a first study, we investigated the mechanism of the antiapoptotic activity of HSV R1s by using TNFα and Fas ligand (FasL), two death-receptor inducers involved in anti-HSVs immune response. From this work, we report three main findings on the antiapoptotic activity of HSV R1s. First, HSV-1 R1 like HSV-2 R1 has the ability to protect cells against TNFα- and FasL-induced apoptosis. Second, HSV-1 R1 contributes in protecting infected cells against FasL. Third, HSV R1s and procaspase-8 interact in a way that inhibits the dimerization/activation of caspase-8. These results suggest that in addition to counteracting death receptor-induced apoptosis, HSV R1s could inhibit apoptosis induced by other signals that trigger caspase-8 activation during HSV infection. Double-stranded RNA (dsRNA) are viral intermediates notably produced by HSVs and have been shown to induce apoptosis via caspase-8 activation. We tested in a second study whether HSV R1s have the ability to counteract apoptosis triggered by polyriboinosinic : polyribocytidylic acid (poly(I:C)), a synthetic analog of dsRNA that triggers caspase-8 activation. We showed that HSVs infection protect epithelial cells from apoptosis induced by poly(I:C). We established that HSV-1 R1 is essential for the protection of HSV-1-infected cells against poly(I:C)-induced caspase-8 activation. HSV R1s interact not only with procaspase-8 but also with the receptor interacting protein 1 (RIP1). The interaction between RIP1 and HSV-2 R1 inhibits the binding of RIP1 to the Toll/interleukine-1 receptor-domain-containing adapter-inducing interferon β (TRIF), the adaptor of Toll-like receptor 3 that is an extracellular dsRNA sensor, which is required to activate caspase-8 following extracellular poly(I:C) stimulation and TRIF overexpression. Thus, HSV R1s have the ability to inhibit poly(I:C)-induced apoptosis at several levels by preventing caspase-8 dimerization/activation and TRIF RIP1 interaction. This work sheds light on the ability of HSV R1s to manipulate apoptosis. Early during the lytic cycle, protein levels of the cellular inhibitors of caspase-8 as cFLIP drop but HSV R1s accumulate concomitantly and act as a viral inhibitor of apoptosis by binding to procaspase-8 and RIP1 in a way that impairs caspase-8 activation by death-receptors and dsRNA detectors stimulation

Comparison of les and rans predictions with experimental results of the fan of a turbofan

This paper aims at validating LES capability if applied to an actual turbofan configuration at nominal regime, if compared to RANS and experimental measurements. For assessment, averaged radial profiles are compared in 3 axial planes – before the stage, between the rotor blade and stator vanes, and downstream of the stator. RANS and LES results are in very good agreement, but found to be shifted compared to the measurements and for some quantities. An analysis of the unsteady axial velocity is then proposed, investigating root-mean square of axial velocity. Tip-leakage, as well as two boundary layer transitions are evidenced in the rotor. An estimation of the integral turbulent timescale is finally proposed in the whole domain, using autocorrelation of the axial velocity. Suction- side horseshoe vortices are found to be very coherent, as well as the stator corner vortices. Regions of large timescale are moreover evidenced between rotor and stator wakes

Towards Confidential Computing: A Secure Cloud Architecture for Big Data Analytics and AI

Cloud computing provisions computer resources at a cost-effective way based on demand. Therefore it has become a viable solution for big data analytics and artificial intelligence which have been widely adopted in various domain science. Data security in certain fields such as biomedical research remains a major concern when moving their workflows to cloud, because cloud environments are generally outsourced which are more exposed to risks. We present a secure cloud architecture and describes how it enables workflow packaging and scheduling while keeping its data, logic and computation secure in transit, in use and at rest.Comment: 2023 IEEE 16th International Conference on Cloud Computing (IEEE CLOUD), Chicago, Illinois, USA, July 2-8, 202

Emission State Structure and Linewidth Broadening Mechanisms in Type-II CdSe/CdTe Core–Crown Nanoplatelets: A Combined Theoretical–Single Nanocrystal Optical Study

Type-II heterostructures are key elementary components in optoelectronic, photovoltaic, and quantum devices. The staggered band alignment of materials leads to the stabilization of indirect excitons (IXs), i.e., correlated electron–hole pairs experiencing spatial separation with novel properties, boosting optical gain and promoting strategies for the design of information storage, charge separation, or qubit manipulation devices. Planar colloidal CdSe/CdTe core–crown type-II nested structures, grown as nanoplatelets (NPLs), are the focus of the present work. By combining low temperature single NPL measurements and electronic structure calculations, we gain insights into the mechanisms impacting the emission properties. We are able to probe the sensitivity of the elementary excitations (IXs, trions) with respect to the appropriate structural parameter (core size). Neutral IXs, with binding energies reaching 50 meV, are shown to dominate the highly structured single NPL emission. The large broadening linewidth that persists at the single NPL level clearly results from strong exciton–LO phonon coupling (Eph = 21 meV) whose strength is poorly influenced by trapped charges. The spectral jumps (≈10 meV) in the photoluminescence recorded as a function of time are explained by the fluctuations in the IX electrostatic environment considering fractional variations (≈0.2 e) of the noncompensated charge defects

Green Edge ice camp campaigns : understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies

Genomic Species Are Ecological Species as Revealed by Comparative Genomics in Agrobacterium tumefaciens

The definition of bacterial species is based on genomic similarities, giving rise to the operational concept of genomic species, but the reasons of the occurrence of differentiated genomic species remain largely unknown. We used the Agrobacterium tumefaciens species complex and particularly the genomic species presently called genomovar G8, which includes the sequenced strain C58, to test the hypothesis of genomic species having specific ecological adaptations possibly involved in the speciation process. We analyzed the gene repertoire specific to G8 to identify potential adaptive genes. By hybridizing 25 strains of A. tumefaciens on DNA microarrays spanning the C58 genome, we highlighted the presence and absence of genes homologous to C58 in the taxon. We found 196 genes specific to genomovar G8 that were mostly clustered into seven genomic islands on the C58 genome—one on the circular chromosome and six on the linear chromosome—suggesting higher plasticity and a major adaptive role of the latter. Clusters encoded putative functional units, four of which had been verified experimentally. The combination of G8-specific functions defines a hypothetical species primary niche for G8 related to commensal interaction with a host plant. This supports that the G8 ancestor was able to exploit a new ecological niche, maybe initiating ecological isolation and thus speciation. Searching genomic data for synapomorphic traits is a powerful way to describe bacterial species. This procedure allowed us to find such phenotypic traits specific to genomovar G8 and thus propose a Latin binomial, Agrobacterium fabrum, for this bona fide genomic species

N-glycosylation of mouse TRAIL-R and human TRAIL-R1 enhances TRAIL-induced death.

APO2L/TRAIL (TNF-related apoptosis-inducing ligand) induces death of tumor cells through two agonist receptors, TRAIL-R1 and TRAIL-R2. We demonstrate here that N-linked glycosylation (N-glyc) plays also an important regulatory role for TRAIL-R1-mediated and mouse TRAIL receptor (mTRAIL-R)-mediated apoptosis, but not for TRAIL-R2, which is devoid of N-glycans. Cells expressing N-glyc-defective mutants of TRAIL-R1 and mouse TRAIL-R were less sensitive to TRAIL than their wild-type counterparts. Defective apoptotic signaling by N-glyc-deficient TRAIL receptors was associated with lower TRAIL receptor aggregation and reduced DISC formation, but not with reduced TRAIL-binding affinity. Our results also indicate that TRAIL receptor N-glyc impacts immune evasion strategies. The cytomegalovirus (CMV) UL141 protein, which restricts cell-surface expression of human TRAIL death receptors, binds with significant higher affinity TRAIL-R1 lacking N-glyc, suggesting that this sugar modification may have evolved as a counterstrategy to prevent receptor inhibition by UL141. Altogether our findings demonstrate that N-glyc of TRAIL-R1 promotes TRAIL signaling and restricts virus-mediated inhibition

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Thiocolchicoside a semi-synthetic derivative of the Glory Lily: a new weapon to fight metastatic bone resorption?: Thiocolchicoside to treat metastatic bone

International audienceMetastatic bone disease is a serious clinical complication for the treatment of patients with advanced cancer, but few therapeutic options are currently available. Bisphosphonates are an established standard care for these patients, but new treatments are now emerging, including the use of monoclonal antibodies targeting the RANK ligand. In this issue of the BJP, Reuter et al. provide evidence that thiocolchicoside, a semi-synthetic derivative of the naturally occurring colchicoside, extracted from the seeds of Gloriosa superba (Liliaceae), prevented osteoclactogenesis by suppressing RANK ligand-mediated NF-κB activation. Thiolcolchicoside may thus represent an attractive therapeutic option for the management of bone metastatic disease