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  • 1
    Publication Date: 2014-05-30
    Description: Lymphocyte functions triggered by antigen recognition and co-stimulation signals are associated with a rapid and intense cell division, and hence with metabolism adaptation. The nucleotide cytidine 5' triphosphate (CTP) is a precursor required for the metabolism of DNA, RNA and phospholipids. CTP originates from two sources: a salvage pathway and a de novo synthesis pathway that depends on two enzymes, the CTP synthases (or synthetases) 1 and 2 (CTPS1 with CTPS2); the respective roles of these two enzymes are not known. CTP synthase activity is a potentially important step for DNA synthesis in lymphocytes. Here we report the identification of a loss-of-function homozygous mutation (rs145092287) in CTPS1 in humans that causes a novel and life-threatening immunodeficiency, characterized by an impaired capacity of activated T and B cells to proliferate in response to antigen receptor-mediated activation. In contrast, proximal and distal T-cell receptor (TCR) signalling events and responses were only weakly affected by the absence of CTPS1. Activated CTPS1-deficient cells had decreased levels of CTP. Normal T-cell proliferation was restored in CTPS1-deficient cells by expressing wild-type CTPS1 or by addition of exogenous CTP or its nucleoside precursor, cytidine. CTPS1 expression was found to be low in resting T cells, but rapidly upregulated following TCR activation. These results highlight a key and specific role of CTPS1 in the immune system by its capacity to sustain the proliferation of activated lymphocytes during the immune response. CTPS1 may therefore represent a therapeutic target of immunosuppressive drugs that could specifically dampen lymphocyte activation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Martin, Emmanuel -- Palmic, Noe -- Sanquer, Sylvia -- Lenoir, Christelle -- Hauck, Fabian -- Mongellaz, Cedric -- Fabrega, Sylvie -- Nitschke, Patrick -- Esposti, Mauro Degli -- Schwartzentruber, Jeremy -- Taylor, Naomi -- Majewski, Jacek -- Jabado, Nada -- Wynn, Robert F -- Picard, Capucine -- Fischer, Alain -- Arkwright, Peter D -- Latour, Sylvain -- G1001799/Medical Research Council/United Kingdom -- WT095219MA/Wellcome Trust/United Kingdom -- England -- Nature. 2014 Jun 12;510(7504):288-92. doi: 10.1038/nature13386. Epub 2014 May 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Laboratoire Activation Lymphocytaire et Susceptibilite a l'EBV, INSERM UMR 1163, Hopital Necker Enfants-Malades, Paris 75015, France [2] Universite Paris Descartes Sorbonne Paris Cite, Institut Imagine, Paris 75015, France. ; Laboratoire de Biochimie Metabolomique et Proteomique, Hopital Necker Enfants-Malades, Paris 75015, France. ; Hematopoiesis and Immunotherapy, CNRS-UMR 5535, Institut de Genetique Moleculaire de Montpellier, Montpellier 34293, France. ; 1] Universite Paris Descartes Sorbonne Paris Cite, Institut Imagine, Paris 75015, France [2] Plateforme Vecteurs Viraux et Transfert de Genes, IFR94, Hopital Necker Enfants-Malades, Paris 75015, France. ; 1] Universite Paris Descartes Sorbonne Paris Cite, Institut Imagine, Paris 75015, France [2] Service de Bioinformatique, Hopital Necker Enfants-Malades, Paris 75015, France. ; 1] University of Manchester, Royal Manchester Children's Hospital, Manchester M13 0WL, UK [2] Italian Institute of Technology, Genoa 16163, Italy. ; McGill University and Genome Quebec Innovation Centre, Montreal H3A 0G1, Canada. ; 1] McGill University and Genome Quebec Innovation Centre, Montreal H3A 0G1, Canada [2] Department of Pediatrics, McGill University Health Center Research Institute, Montreal H3H 1P3, Canada. ; University of Manchester, Royal Manchester Children's Hospital, Manchester M13 0WL, UK. ; 1] Universite Paris Descartes Sorbonne Paris Cite, Institut Imagine, Paris 75015, France [2] Centre d'Etude des Deficits Immunitaires, Hopital Necker Enfants-Malades, AP-HP, Paris 75015, France [3] Laboratoire Genetique Humaine des Maladies Infectieuses, INSERM UMR 1163, Hopital Necker Enfants-Malades, Paris 75015, France. ; 1] Laboratoire Activation Lymphocytaire et Susceptibilite a l'EBV, INSERM UMR 1163, Hopital Necker Enfants-Malades, Paris 75015, France [2] Universite Paris Descartes Sorbonne Paris Cite, Institut Imagine, Paris 75015, France [3] Unite d'Immunologie et Hematologie Pediatrique, Assistance Publique-Hopitaux de Paris (AP-HP), Hopital Necker Enfants-Malades, Paris 75015, France [4] College de France, Paris 75005, France. ; 1] University of Manchester, Royal Manchester Children's Hospital, Manchester M13 0WL, UK [2]. ; 1] Laboratoire Activation Lymphocytaire et Susceptibilite a l'EBV, INSERM UMR 1163, Hopital Necker Enfants-Malades, Paris 75015, France [2] Universite Paris Descartes Sorbonne Paris Cite, Institut Imagine, Paris 75015, France [3] Laboratoire de Biochimie Metabolomique et Proteomique, Hopital Necker Enfants-Malades, Paris 75015, France [4].〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24870241" target="_blank"〉PubMed〈/a〉
    Keywords: Antigens, CD3/immunology ; B-Lymphocytes/cytology/immunology/metabolism ; Carbon-Nitrogen Ligases/*deficiency/genetics/*metabolism ; Cell Proliferation ; Child, Preschool ; Cytidine Triphosphate/metabolism ; Female ; Humans ; Immunologic Deficiency Syndromes/enzymology/genetics ; Infant ; Infant, Newborn ; *Lymphocyte Activation/genetics ; Lymphocytes/*cytology/immunology/metabolism ; Male ; Mutation/genetics ; Receptors, Antigen, T-Cell/immunology ; T-Lymphocytes/cytology/immunology/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-06-18
    Description: High-resolution N -body simulations using different codes and initial condition techniques reveal two different behaviours for the rotation frequency of transient spiral arms like structures. Whereas unbarred discs present spiral arms nearly corotating with disc particles, strong barred models (bulged or bulgeless) quickly develop a bar–spiral structure dominant in density, with a pattern speed almost constant in radius. As the bar strength decreases the arm departs from bar rigid rotation and behaves similar to the unbarred case. In strong barred models, we detect in the frequency space other subdominant and slower modes at large radii, in agreement with previous studies, however, we also detect them in the configuration space. We propose that the distinctive behaviour of the dominant spiral modes can be exploited in order to constraint the nature of Galactic spiral arms by the astrometric survey Gaia and by 2D spectroscopic surveys like Calar Alto Legacy Integral Field Area Survey (CALIFA) and Mapping Nearby Galaxies at APO (MANGA) in external galaxies.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 3
    Publication Date: 2014-04-11
    Description: We map the kinematics of stars in simulated galaxy discs with spiral arms using the velocity ellipsoid vertex deviation ($l_{\rm v}$). We use test particle simulations, and for the first time, fully self-consistent high-resolution N -body models. We compare our maps with the tight winding approximation model analytical predictions. We see that for all barred models, spiral arms rotate closely to a rigid body manner and the vertex deviation values correlate with the density peak's position bounded by overdense and underdense regions. In such cases, vertex deviation sign changes from negative to positive when crossing the spiral arms in the direction of disc rotation, in regions where the spiral arms are in between corotation radius (CR) and the Outer Lindblad Resonance (OLR). By contrast, when the arm sections are inside the CR and outside the OLR, $l_{\rm v}$ changes from negative to positive. We propose that measurements of the vertex deviation's pattern can be used to trace the position of the main resonances of the spiral arms. We propose that this technique might exploit future data from Gaia and APO Galactic Evolution Experiment (APOGEE) surveys. For unbarred N -body simulations with spiral arms corotating with disc material at all radii, our analysis suggests that no clear correlation exists between $l_{\rm v}$ and density structures.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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