Publications by authors named "Marie Pourcelot"

9 Publications

  • Page 1 of 1

The VP3 Protein of Bluetongue Virus Associates with the MAVS Complex and Interferes with the RIG-I-Signaling Pathway.

Viruses 2021 02 2;13(2). Epub 2021 Feb 2.

UMR 1161 Virologie, Laboratory for Animal Health, INRAE, Department of Animal Health, Ecole Nationale Vétérinaire d'Alfort, ANSES, Université Paris-Est, 94700 Maisons-Alfort, France.

Bluetongue virus (BTV), an arbovirus transmitted by biting midges, is a major concern of wild and domestic ruminants. While BTV induces type I interferon (alpha/beta interferon [IFN-α/β]) production in infected cells, several reports have described evasion strategies elaborated by this virus to dampen this intrinsic, innate response. In the present study, we suggest that BTV VP3 is a new viral antagonist of the IFN-β synthesis. Indeed, using split luciferase and coprecipitation assays, we report an interaction between VP3 and both the mitochondrial adapter protein MAVS and the IRF3-kinase IKKε. Overall, this study describes a putative role for the BTV structural protein VP3 in the control of the antiviral response.
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http://dx.doi.org/10.3390/v13020230DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7913109PMC
February 2021

Bovine Organospecific Microvascular Endothelial Cell Lines as New and Relevant In Vitro Models to Study Viral Infections.

Int J Mol Sci 2020 Jul 24;21(15). Epub 2020 Jul 24.

Center for Molecular Biophysics UPR4301 CNRS, 45000 Orléans, France.

Microvascular endothelial cells constitute potential targets for exogenous microorganisms, in particular for vector-borne pathogens. Their phenotypic and functional variations according to the organs they are coming from provide an explanation of the organ selectivity expressed in vivo by pathogens. In order to make available relevant tools for in vitro studies of infection mechanisms, our aim was to immortalize bovine organospecific endothelial cells but also to assess their permissivity to viral infection. Using transfection with SV40 large T antigen, six bovine microvascular endothelial cell lines from various organs and one macrovascular cell line from an umbilical cord were established. They display their own panel of endothelial progenitor/mature markers, as assessed by flow cytometry and RT-qPCR, as well as the typical angiogenesis capacity. Using both Bluetongue and foot-and-mouth disease viruses, we demonstrate that some cell lines are preferentially infected. In addition, they can be transfected and are able to express viral proteins such as BTV8-NS3. Such microvascular endothelial cell lines bring innovative tools for in vitro studies of infection by viruses or bacteria, allowing for the study of host-pathogen interaction mechanisms with the actual in vivo target cells. They are also suitable for applications linked to microvascularization, such as anti-angiogenic and anti-tumor research, growing fields in veterinary medicine.
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http://dx.doi.org/10.3390/ijms21155249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7432920PMC
July 2020

Novel Function of Bluetongue Virus NS3 Protein in Regulation of the MAPK/ERK Signaling Pathway.

J Virol 2019 08 30;93(16). Epub 2019 Jul 30.

UMR Virologie, INRA, École Nationale Vétérinaire d'Alfort, ANSES, Université Paris-Est, Maisons-Alfort, France

Bluetongue virus (BTV) is an arbovirus transmitted by blood-feeding midges to a wide range of wild and domestic ruminants. In this report, we showed that BTV, through its nonstructural protein NS3 (BTV-NS3), is able to activate the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, as assessed by phosphorylation levels of ERK1/2 and the translation initiation factor eukaryotic translation initiation factor 4E (eIF4E). By combining immunoprecipitation of BTV-NS3 and mass spectrometry analysis from both BTV-infected and NS3-transfected cells, we identified the serine/threonine-protein kinase B-Raf (BRAF), a crucial player in the MAPK/ERK pathway, as a new cellular interactor of BTV-NS3. BRAF silencing led to a significant decrease in the MAPK/ERK activation by BTV, supporting a model wherein BTV-NS3 interacts with BRAF to activate this signaling cascade. This positive regulation acts independently of the role of BTV-NS3 in counteracting the induction of the alpha/beta interferon response. Furthermore, the intrinsic ability of BTV-NS3 to bind BRAF and activate the MAPK/ERK pathway is conserved throughout multiple serotypes/strains but appears to be specific to BTV compared to other members of genus. Inhibition of MAPK/ERK pathway with U0126 reduced viral titers, suggesting that BTV manipulates this pathway for its own replication. Altogether, our data provide molecular mechanisms that unravel a new essential function of NS3 during BTV infection. Bluetongue virus (BTV) is responsible of the arthropod-borne disease bluetongue (BT) transmitted to ruminants by blood-feeding midges. In this report, we found that BTV, through its nonstructural protein NS3 (BTV-NS3), interacts with BRAF, a key component of the MAPK/ERK pathway. In response to growth factors, this pathway promotes cell survival and increases protein translation. We showed that BTV-NS3 enhances the MAPK/ERK pathway, and this activation is BRAF dependent. Treatment of MAPK/ERK pathway with the pharmacologic inhibitor U0126 impairs viral replication, suggesting that BTV manipulates this pathway for its own benefit. Our results illustrate, at the molecular level, how a single virulence factor has evolved to target a cellular function to increase its viral replication.
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http://dx.doi.org/10.1128/JVI.00336-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6675888PMC
August 2019

The Role of Optineurin in Antiviral Type I Interferon Production.

Front Immunol 2018 26;9:853. Epub 2018 Apr 26.

INSERM, UMR_S 1197, Hôpital Paul Brousse, Villejuif, France.

After a viral infection and the stimulation of some pattern-recognition receptors as the toll-like receptor 3 in the endosomes or the RIG-I-like receptors in the cytosol, activation of the IKK-related kinase TBK1 leads to the production of type I interferons (IFNs) after phosphorylation of the transcription factors IRF3 and IRF7. Recent findings indicate an involvement of K63-linked polyubiquitination and of the Golgi-localized protein optineurin (OPTN) in the activation of this crucial kinase involved in innate antiviral immunity. This review summarizes the sensing of viruses and the signaling leading to type I IFN production following TBK1 activation through its ubiquitination and the sensing of ubiquitin chains by OPTN at the Golgi apparatus.
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http://dx.doi.org/10.3389/fimmu.2018.00853DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5932347PMC
June 2019

The Golgi apparatus acts as a platform for TBK1 activation after viral RNA sensing.

BMC Biol 2016 08 18;14:69. Epub 2016 Aug 18.

INSERM, UMR_S 1197, Hôpital Paul Brousse, Villejuif, France.

Background: After viral infection and the stimulation of some pattern-recognition receptors, TANK-binding kinase I (TBK1) is activated by K63-linked polyubiquitination followed by trans-autophosphorylation. While the activated TBK1 induces type I interferon production by phosphorylating the transcription factor IRF3, the precise molecular mechanisms underlying TBK1 activation remain unclear.

Results: We report here the localization of the ubiquitinated and phosphorylated active form of TBK1 to the Golgi apparatus after the stimulation of RIG-I-like receptors (RLRs) or Toll-like receptor-3 (TLR3), due to TBK1 K63-linked ubiquitination on lysine residues 30 and 401. The ubiquitin-binding protein optineurin (OPTN) recruits ubiquitinated TBK1 to the Golgi apparatus, leading to the formation of complexes in which TBK1 is activated by trans-autophosphorylation. Indeed, OPTN deficiency in various cell lines and primary cells impairs TBK1 targeting to the Golgi apparatus and its activation following RLR or TLR3 stimulation. Interestingly, the Bluetongue virus NS3 protein binds OPTN at the Golgi apparatus, neutralizing its activity and thereby decreasing TBK1 activation and downstream signaling.

Conclusions: Our results highlight an unexpected role of the Golgi apparatus in innate immunity as a key subcellular gateway for TBK1 activation after RNA virus infection.
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http://dx.doi.org/10.1186/s12915-016-0292-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4991008PMC
August 2016

The TBK1-binding domain of optineurin promotes type I interferon responses.

FEBS Lett 2016 05 4;590(10):1498-508. Epub 2016 May 4.

Laboratory of Immune Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.

Pathogen-associated molecular pattern (PAMP) recognition leads to TANK-binding kinase (TBK1) polyubiquitination and activation by transautophosphorylation, resulting in IFN-β production. Here, we describe a mouse model of optineurin insufficiency (OptnΔ(157) ) in which the TBK1-interacting N-terminus of optineurin was deleted. PAMP-stimulated cells from OptnΔ(157) mice had reduced TBK1 activity, no phosphorylation of optineurin Ser(187) , and mounted low IFN-β responses. In contrast to pull-down assays where the presence of N-terminus was sufficient for TBK1 binding, both the N-terminal and the ubiquitin-binding regions of optineurin were needed for PAMP-induced binding. This report establishes optineurin as a positive regulator TBK1 via a bipartite interaction between these molecules.
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http://dx.doi.org/10.1002/1873-3468.12176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4879041PMC
May 2016

The E3 ubiquitin ligase RNF121 is a positive regulator of NF-κB activation.

Cell Commun Signal 2014 Nov 12;12:72. Epub 2014 Nov 12.

INSERM, UMR_S 1014, Hôpital Paul Brousse, Villejuif, 94800, France.

Background: The nuclear factor κB (NF-κB) family members regulate several biological processes as cell proliferation and differentiation, inflammation, immunity and tumor progression. Ubiquitination plays a key role in NF-κB activation and the ubiquitylated transmitters of the NF-κB signaling cascade accumulate in close proximity to endomembranes.

Findings: We performed an unbiased siRNA library screen targeting the 46 E3 ubiquitin ligases bearing transmembrane domains to uncover new modulators of NF-κB activation, using tumor necrosis factor-α (TNF-α) receptor (TNFR) stimulation as a model. We report here the identification of a new Golgi Apparatus-resident protein, RNF121, as an enhancer of NF-κB promoter activity through the catalytic function of its RING domain. From a molecular standpoint, while knocking down RNF121 did not alter RIP1 ubiquitination and IKK activation, the proteasomal degradation of IκBα was impaired suggesting that this E3 ubiquitin ligase regulates this process. However, RNF121 did not directly ubiquitinate IκBα While they were found in the same complex. Finally, we discovered that RNF121 acts as a broad regulator of NF-κB signaling since its silencing also dampens NF-κB activation following stimulation of Toll-Like Receptors (TLRs), Nod-Like Receptors (NLRs), RIG-I-Like Receptors (RLRs) or after DNA damages.

Conclusions: These results unveil an unexpected role of Golgi Apparatus and reveal RNF121 as a new player involved in the signaling leading to NF-κB activation.
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http://dx.doi.org/10.1186/s12964-014-0072-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4232610PMC
November 2014

Mitochondrial dynamics and the innate antiviral immune response.

FEBS J 2014 Sep 11;281(17):3791-802. Epub 2014 Aug 11.

INSERM UMR_S 1014, Hôpital Paul Brousse, Villejuif, France; Université Paris-Sud P11, Orsay, France; Equipe Labellisée Ligue contre le Cancer, Villejuif, France.

The innate immune system has a key role in the mammalian immune response. In the cytosol, RNA viruses are sensed by the retinoic acid-inducible gene-I-like receptors, which trigger a complex signaling cascade in which mitochondrial antiviral signaling protein plays a central role in mediating the innate host response through the induction of antiviral and inflammatory responses. Hence, the mitochondrion is now emerging as a fundamental hub for innate antiviral immunity beyond its known roles in metabolic processes and the control of programmed cell death. This review summarizes the findings related to mitochondrial antiviral signaling protein, and mitochondria and their dynamics, in the innate immune response to RNA viruses.
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http://dx.doi.org/10.1111/febs.12940DOI Listing
September 2014

Mitochondrial hyperfusion promotes NF-κB activation via the mitochondrial E3 ligase MULAN.

FEBS J 2014 Jul 2;281(14):3095-112. Epub 2014 Jun 2.

INSERM, UMR_S 1014, Hôpital Paul Brousse, Villejuif, France; Université Paris-Sud P11, Orsay, France; Equipe Labellisée Ligue contre le Cancer, Villejuif, France.

Mitochondria are dynamic organelles with a morphology resulting from the balance between two opposing processes: fusion and fission. Little is known about the function of mitochondrial fusion, beside its role in the maintenance of mitochondrial DNA. We report here that enforced mitochondrial hyperfusion, due to the expression of a dominant-negative mutant of Drp1 or of MARCH5, promotes NF-κB activation in a TAK1- and IKK-dependent manner, through the mitochondrial E3 ubiquitin ligase MULAN. The capability of MULAN to activate NF-κB depends on its RING domain and on the E3 ubiquitin ligase TRAF2. Under physiological conditions, stress-induced mitochondrial hyperfusion (SIMH) is also accompanied by NF-κB activation, and the prevention of SIMH or the knockdown of MULAN impairs NF-κB activation. During SIMH, MULAN forms a complex with TRAF2 and modulates its ubiquitylation, signifying that TRAF2 may serve as an ubiquitylated transmitter of NF-κB signaling in this pathway. Our results suggest that mitochondria, through their dynamics, convert stress signals into a cell response leading to NF-κB activation.
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http://dx.doi.org/10.1111/febs.12846DOI Listing
July 2014