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Search Results: 1 - 10 of 2312 matches for " Sophie Daburon "
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Precise Mapping of the CD95 Pre-Ligand Assembly Domain
Valérie Edmond, Benoist Ghali, Aubin Penna, Jean-Luc Taupin, Sophie Daburon, Jean-Fran?ois Moreau, Patrick Legembre
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046236
Abstract: Pre-association of CD95 at the plasma membrane is mandatory for efficient death receptor signaling. This homotrimerization occurs through self-association of an extracellular domain called the pre-ligand assembly domain (PLAD). Using novel molecular and cellular tools, we confirmed that CD95-PLAD is necessary to promote CD95 multimerization and plays a pivotal role in the transmission of apoptotic signals. However, while a human CD95 mutant deleted of the previously described PLAD domain (amino acids 1 to 66) fails to interact with its wild-type counterpart and trigger autonomous cell death, deletion of amino acids 1 to 42 does not prevent homo- or hetero (human/mouse)-oligomerization of CD95, and thus does not alter transmission of the apoptotic signal. Overall, these findings indicate that the region between amino acids 43 to 66 corresponds to the minimal motif involved in CD95 homotypic interaction and is necessary to convey an efficient apoptotic signal. Interfering with this PLAD may represent a new therapeutic strategy for altering CD95-induced apoptotic and non-apoptotic signals.
Enhancing Production and Cytotoxic Activity of Polymeric Soluble FasL-Based Chimeric Proteins by Concomitant Expression of Soluble FasL
Aurore Morello, Sophie Daburon, Michel Castroviejo, Jean-Fran?ois Moreau, Julie Dechanet-Merville, Jean-Luc Taupin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073375
Abstract: Membrane FasL is the natural trigger of Fas-mediated apoptosis. A soluble homotrimeric counterpart (sFasL) also exists which is very weakly active, and needs oligomerization beyond its trimeric state to induce apoptosis. We recently generated a soluble FasL chimera by fusing the immunoglobulin-like domain of the leukemia inhibitory factor receptor gp190 to the extracellular region of human FasL, which enabled spontaneous dodecameric homotypic polymerization of FasL. This polymeric soluble human FasL (pFasL) displayed anti-tumoral activity in vitro and in vivo without systemic cytotoxicity in mouse. In the present work, we focused on the improvement of pFasL, with two complementary objectives. First, we developed more complex pFasL-based chimeras that contained a cell-targeting module. Secondly, we attempted to improve the production and/or the specific activity of pFasL and of the cell-targeting chimeras. We designed two chimeras by fusing to pFasL the extracellular portions of the HLA-A2 molecule or of a human gamma-delta TCR, and analyzed the consequences of co-expressing these molecules or pFasL together with sFasL on their heterotopic cell production. This strategy significantly enhanced the production of pFasL and of the two chimeras, as well as the cytotoxic activity of the two chimeras but not of pFasL. These results provide the proof of concept for an optimization of FasL-based chimeric proteins for a therapeutic use.
The Naturally Processed CD95L Elicits a c-Yes/Calcium/PI3K-Driven Cell Migration Pathway
Sébastien Tauzin,Benjamin Chaigne-Delalande,Eric Selva,Nadine Khadra,Sophie Daburon,Cécile Contin-Bordes,Patrick Blanco,Jacques Le Seyec,Thomas Ducret,Laurent Counillon,Jean-Fran?ois Moreau,Paul Hofman,Pierre Vacher,Patrick Legembre
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1001090
Abstract: Patients affected by chronic inflammatory disorders display high amounts of soluble CD95L. This homotrimeric ligand arises from the cleavage by metalloproteases of its membrane-bound counterpart, a strong apoptotic inducer. In contrast, the naturally processed CD95L is viewed as an apoptotic antagonist competing with its membrane counterpart for binding to CD95. Recent reports pinpointed that activation of CD95 may attract myeloid and tumoral cells, which display resistance to the CD95-mediated apoptotic signal. However, all these studies were performed using chimeric CD95Ls (oligomerized forms), which behave as the membrane-bound ligand and not as the naturally processed CD95L. Herein, we examine the biological effects of the metalloprotease-cleaved CD95L on CD95-sensitive activated T-lymphocytes. We demonstrate that cleaved CD95L (cl-CD95L), found increased in sera of systemic lupus erythematosus (SLE) patients as compared to that of healthy individuals, promotes the formation of migrating pseudopods at the leading edge of which the death receptor CD95 is capped (confocal microscopy). Using different migration assays (wound healing/Boyden Chamber/endothelial transmigration), we uncover that cl-CD95L promotes cell migration through a c-yes/Ca2+/PI3K-driven signaling pathway, which relies on the formation of a CD95-containing complex designated the MISC for Motility-Inducing Signaling Complex. These findings revisit the role of the metalloprotease-cleaved CD95L and emphasize that the increase in cl-CD95L observed in patients affected by chronic inflammatory disorders may fuel the local or systemic tissue damage by promoting tissue-filtration of immune cells.
Expression of leukemia inhibitory factor (LIF) and its receptor gp190 in human liver and in cultured human liver myofibroblasts. Cloning of new isoforms of LIF mRNA
Toru Hisaka, Alexis Desmoulière, Jean-Luc Taupin, Sophie Daburon, Véronique Neaud, Nathalie Senant, Jean-Frédéric Blanc, Jean-Fran?ois Moreau, Jean Rosenbaum
Comparative Hepatology , 2004, DOI: 10.1186/1476-5926-3-10
Abstract: LIF expression, analyzed by immunohistochemistry, was barely detectable in normal liver but was strong within cirrhotic fibrous septa and was found in spindle-shaped cells compatible with myofibroblasts. Accordingly, cultured human liver myofibroblasts expressed high levels of LIF as shown by ELISA and Northern blot. Biological assay demonstrated that myofibroblast-derived LIF was fully active. RT-PCR showed expression of the LIF-D and M isoforms, and also of low levels of new variants of LIF-D and LIF-M resulting from deletion of exon 2 through alternative splicing. LIF receptor expression was detected mainly as a continuous sinusoidal staining that was enhanced in cirrhotic liver, suggestive of endothelial cell and/or hepatocyte labeling. Immunohistochemistry, flow cytometry and STAT-3 phosphorylation assays did not provide evidence for LIF receptor expression by myofibroblasts themselves. LIF secretion by cultured myofibroblasts was down regulated by the addition of interleukin-4.We show for the first time the expression of LIF in human liver myofibroblasts, as well as of two new isoforms of LIF mRNA. Expression of LIF by myofibroblasts and of its receptor by adjacent cells suggests a potential LIF paracrine loop in human liver that may play a role in the regulation of intra-hepatic inflammation.Leukemia inhibitory factor (LIF) belongs to the interleukin (IL)-6 family of cytokines, together with IL-11, ciliary neurotrophic factor, cardiotrophin-1, oncostatin M and neurotrophin-1/B cell stimulating factor-3. LIF is widely expressed in tissues and in many isolated cells. LIF expression is commonly up-regulated during inflammation. Nevertheless, its role seems to be complex as both pro- and anti-inflammatory properties have been described for that cytokine. Although LIF, like IL-6, is able to drive a significant acute-phase reaction in non-human primates [1], this has been questioned in humans [2]. LIF exerts its biological activities through its binding to a hetero
An Exploratory Study of Altruism in Greek Children: Relations with Empathy, Resilience and Classroom Climate  [PDF]
Sophie Leontopoulou
Psychology (PSYCH) , 2010, DOI: 10.4236/psych.2010.15047
Abstract: The aims of this exploratory study were two-fold: a. to identify any relations between children’s altruism and a set of demographic and other personal and social characteristics of Greek children, such as empathy, resilience and classroom climate; and b. to examine the psychometric properties of a newly-developed measure of altruistic behaviour in children, namely the Altruistic Behaviour Questionnaire (ABQ). 232 male and female students of the 5th and 6th class of Primary School in Northern Greece participated in this study. The ABQ was found to have adequate internal consistency and concurrent and construct validity. Using a hierarchical regression analysis, altruism in children was found to be reliably predicted by participants’ gender and academic performance, by empathy and also by resilience; nevertheless, the more socially determined variable of classroom climate only marginally predicted altruism. The importance of including training in the development and manifestation of altruism in emotional education programmes and resilience interventions at school is highlighted.
The Naturally Processed CD95L Elicits a c-Yes/Calcium/PI3K-Driven Cell Migration Pathway
Sébastien Tauzin equal contributor,Benjamin Chaigne-Delalande equal contributor,Eric Selva,Nadine Khadra,Sophie Daburon,Cécile Contin-Bordes,Patrick Blanco,Jacques Le Seyec,Thomas Ducret,Laurent Counillon,Jean-Fran?ois Moreau,Paul Hofman,Pierre Vacher,Patrick Legembre
PLOS Biology , 2011, DOI: 10.1371/journal.pbio.1001090
Abstract: Patients affected by chronic inflammatory disorders display high amounts of soluble CD95L. This homotrimeric ligand arises from the cleavage by metalloproteases of its membrane-bound counterpart, a strong apoptotic inducer. In contrast, the naturally processed CD95L is viewed as an apoptotic antagonist competing with its membrane counterpart for binding to CD95. Recent reports pinpointed that activation of CD95 may attract myeloid and tumoral cells, which display resistance to the CD95-mediated apoptotic signal. However, all these studies were performed using chimeric CD95Ls (oligomerized forms), which behave as the membrane-bound ligand and not as the naturally processed CD95L. Herein, we examine the biological effects of the metalloprotease-cleaved CD95L on CD95-sensitive activated T-lymphocytes. We demonstrate that cleaved CD95L (cl-CD95L), found increased in sera of systemic lupus erythematosus (SLE) patients as compared to that of healthy individuals, promotes the formation of migrating pseudopods at the leading edge of which the death receptor CD95 is capped (confocal microscopy). Using different migration assays (wound healing/Boyden Chamber/endothelial transmigration), we uncover that cl-CD95L promotes cell migration through a c-yes/Ca2+/PI3K-driven signaling pathway, which relies on the formation of a CD95-containing complex designated the MISC for Motility-Inducing Signaling Complex. These findings revisit the role of the metalloprotease-cleaved CD95L and emphasize that the increase in cl-CD95L observed in patients affected by chronic inflammatory disorders may fuel the local or systemic tissue damage by promoting tissue-filtration of immune cells.
Bank Characteristics and Procyclicality: A Theoretical Approach  [PDF]
Marie-Sophie Gauvin
Journal of Financial Risk Management (JFRM) , 2014, DOI: 10.4236/jfrm.2014.33007
Abstract:

The 2007-2008 crisis highlighted liquidity management troubles. We witness a real estate asset price boom during the pre-crisis period and a difficulty for banks to raise funding afterwards. Consequently, bank choices in response to the conduct of the monetary policy along the cycle can be studied. Despite usual financial accelerator, the excessive (lack of) confidence of banks in the upward (down) phase explains procyclical balance sheet movements. Moreover, the monetary policy effects on bank behaviors vary according to their initial specifications. From a theoretical point of view, this paper examines the response of the banking sector to monetary authorities impulses, in function of their initial characteristics. So, the paper highlights a theoretical model, based on accounting identities, in which banks are distinguished in different categories according to their level of capitalization and liquidity. The principal result is that the less capitalized and liquid banks have more procyclical behaviors.

Manufacture of a Low Oxalate Mitsumame-Type Dessert Using Rhubarb Juice and Calcium Salts  [PDF]
Sophie Faudon, Geoffrey Savage
Food and Nutrition Sciences (FNS) , 2014, DOI: 10.4236/fns.2014.517174
Abstract: Rhubarb (Rheum rhabarbarum) juice was used to make a Japanese soft mitsumame-type dessert sweet. The dessert was prepared from extracted rhubarb juice, which was cooked with sugar, agar and guar gum, then allowed to set in sweet moulds. The total, soluble and insoluble oxalates were determined in the ingredients and the final products using HPLC chromatography. To reduce the soluble oxalate content of the dessert while retaining the colour and taste of the final product, increments of CaCl2 and CaCO3 were added to the test dessert mixes. The addition of CaCl2 reduced the pH from 3.55 ± 0.03 to pH 3.09 ± 0.02 while addition of CaCO3 increased the pH from 3.55 ± 0.03 to 4.96 ± 0.01. In both cases, the incremental addition of calcium reduced the soluble oxalate content of the sweets by converting it to insoluble oxalate.
Effective Yield Strength for Material Powder Consolidated at Stage II Compaction  [PDF]
Larbi Siad, Sophie Ganglo?
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.49028
Abstract: This work is concerned with the estimation from the outside of effective yield strength for the stage II consolidated material package of axisymmetric solid particles. Once an appropriate simple representative axisymmetric unit cell is chosen, the kinematical approach of the yield design homogenization method is used in order to obtain external estimates which has been found depending on the loading history (isostatic and closed die compactions) as well as on the relative density of the material powder. For comparison purpose, finite element simulations that describe the behavior of spherical elastic plastic particles uniformly distributed inside the material powder are carried out.
Assessing Ecotoxicity in Marine Environment Using Luminescent Microalgae: Where Are We At?  [PDF]
Sophie Sanchez-Ferandin
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.615252
Abstract: Nowadays, microalgae are particularly used to assess the environmental impact of contaminants in aquatic systems. Naturally present in some algal species, bioluminescence is highly used in application fields related to environmental monitoring. Bioluminescent dinoflagellates have played a pivotal role in this domain. When exposed to heavy metals or toxic organic compounds, bioluminescent dinoflagellates have the capacity to decrease light emission. In addition, new molecular tools allow the possibility to produce genetically modified microorganisms which are able to perform luminescence. Combined with the luciferase reporter gene, two main genetic constructions can be employed. Activation of a specific inducible promoter induces the luminescence gene transcription and this signal increases over time. Constitutive promoters result in a high basal expression level of the reporter gene. During exposure to a potential toxic pollutant, the basal expression level will decrease due to the toxic effect. Toxicity bioassays based on engineered luminescent Chlorophyta microalgae are among the most sensitive tests and are an invaluable complement to classical toxicity assays.
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