Institut de Chimie & Biologie des Membranes & des Nano-objets • Bordeaux

LIA France-Japan GEM Réseau RMN Aquitain Master AC2QMAPS IPEP master UREKA UMT FOLIES INDIA
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Christian Salesse, 8 June 2017, 4pm, ENSCBP Christina Sizun, 18 May 2017, 4 pm, ENSCBP Marisela Velez, 5 May 2017, 11am, IECB Iqbal Choudhary, 27 April 2017, 4 pm, ENSCBP Vincent Aucagne, 21 April 2017, 11 am, IECB Sophie Zinn-Justin, 14 April 2017, 11 am, IECB Cécile Feuillie, 16 February 2017, 4 PM, ENSCBP Félix M. Goñi, 8 december 2016, 4 pm, ENSCBP Félix M. Goñi, 17 november 2016, 4 pm, ENSCBP Carl Creutz, 20 october 2016, 4 pm, ENSCBP Diego Romero, 30 september 2016, 11 am, IECB A. Ciaccafava, 8 september 2016, 14h, ENSCBP A. Ramamoorthy, 16 June 2016, 16h, ENSCBP Alexandre de Brevern, 2 june 2016, ENSCBP Isabelle Landrieu, 26 May, 16h, ENSCBP Frances Sepavoric, 12 May, 16h, ENSCBP Thomas Pradeu, 7 April 2016, 9h, ENSCBP Françoise Argoul, 3 march 2016, 16h, ENSCBP Corinne Loutelier-Bourhis, 16/12/2015, 16h Aristotelis XENAKIS, 3 december 2015, 16h Fabian Kiessling, 26 november 2015, 11h Michaël Molinari, 20 november 2015, 11h Dipankar Das Sarma, 28 October 2015, 14h. Olivier Donard, 22 october 2015, 16h, ENSCBP E. Morvan & A.Grelard, 17/12/2015, 16h, ENSCBP Christophe Cullin, 10 september 2015, 14 h Brigitte Lindet, 18 June 2015, 16h, ENSCBP(B) Marion Decossas, 4 June 2015, 16h, ENSCBP(B) Pascale Schellenberger, 21 Mai 2015, 16h F. Leal-Calderon, 7 May 2015, 16h, ENSCBP(B) Ibrahim Abdulhalim, 9 April 2015, 14h, ENSCBP Manon Carré, 26 March 2015, 14h, ENSCBP(B) C. Bure & JM Schmitter, 19 March 2015, 16h T. Ogata & H. Ihara, 17 March 2015, 11h, IECB Banafshe Larijani, 12 March 2015, 16h, ENSCBP
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LIA France-Japan GEM Réseau RMN Aquitain Master AC2QMAPS IPEP master UREKA UMT FOLIES INDIA
Offres d'Emploi Plateau Technique Conseil d'Unité Animation Scientifique WEB Editorial Committee Hygiène & Sécurité Communication Administration Directoire Scientifique Direction
Chimie Biophysique Chimie Biomimétique et Thérapeuti... Biologie et Biotechnologie Administration
Christian Salesse, 8 June 2017, 4pm... Christina Sizun, 18 May 2017, 4 pm,... Marisela Velez, 5 May 2017, 11am, I... Iqbal Choudhary, 27 April 2017, 4 p... Vincent Aucagne, 21 April 2017, 11 ... Sophie Zinn-Justin, 14 April 2017, ... Cécile Feuillie, 16 February 2017,... Félix M. Goñi, 8 december 2016, 4... Félix M. Goñi, 17 november 2016, ... Carl Creutz, 20 october 2016, 4 pm,... Diego Romero, 30 september 2016, 11... A. Ciaccafava, 8 september 2016, 14... A. Ramamoorthy, 16 June 2016, 16h,... Alexandre de Brevern, 2 june 2016, ... Isabelle Landrieu, 26 May, 16h, ENS... Frances Sepavoric, 12 May, 16h, ENS... Thomas Pradeu, 7 April 2016, 9h, EN... Françoise Argoul, 3 march 2016, 1... Corinne Loutelier-Bourhis, 16/12/20... Aristotelis XENAKIS, 3 december 201... Fabian Kiessling, 26 november 2015,... Michaël Molinari, 20 november 2015... Dipankar Das Sarma, 28 October 2015... Olivier Donard, 22 october 2015, 16... E. Morvan & A.Grelard, 17/12/2015, ... Christophe Cullin, 10 september 201... Brigitte Lindet, 18 June 2015, 16h,... Marion Decossas, 4 June 2015, 16h, ... Pascale Schellenberger, 21 Mai 2015... F. Leal-Calderon, 7 May 2015, 16h, ... Ibrahim Abdulhalim, 9 April 2015, 1... Manon Carré, 26 March 2015, 14h, ... C. Bure & JM Schmitter, 19 March 20... T. Ogata & H. Ihara, 17 March 2015,... Banafshe Larijani, 12 March 2015, 1...
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1 […]
Xiang, Shengqi; Kulminskaya, Natalia; Habenstein, Birgit; Biernat, Jacek; Tepper, Katharina; Paulat, Maria; Griesinger, Christian; Becker, Stefan; Lange, Adam; Mandelkow, Eckhard; Linser, Rasmus;
A Two-Component Adhesive: Tau Fibrils Arise from a Combination of a Well-Defined Motif and Conformationally Flexible Interactions
Journal of the American Chemical Society, 2017, 139, 2639-2646
Fibrillar aggregates of A beta and Tau in the brain are the major hallmarks of Alzheimer's disease. Most Tau fibers have a twisted appearance, but the twist can be variable and even absent. This ambiguity, which has also been associated with different phenotypes of tauopathies, has led to controversial assumptions about fibril constitution, and it is unclear to-date what the molecular causes of this polymorphism are. To tackle this question, we used solid-state NMR strategies providing assignments of non-seeded three-repeat-domain Tau(3RD) with an inherent heterogeneity. This is in contrast to the general approach to characterize the most homogeneous preparations by construct truncation or intricate seeding protocols. Here, carbon and nitrogen chemical-shift conservation between fibrils revealed invariable secondary-structure properties, however, with inter-monomer interactions variable among samples. Residues with variable amide shifts are localized mostly to N- and C-terminal regions within the rigid beta structure in the repeat region of Tau(3RD). By contrast, the hexapeptide motif in repeat R3, a crucial motif for fibril formation, shows strikingly low variability of all NMR parameters: Starting as a nucleation site for monomer monomer contacts, this six-residue sequence element also turns into a well-defined structural element upon fibril formation. Given the absence of external causes in vitro, the interplay of structurally differently conserved elements in this protein likely reflects an intrinsic property of Tau fibrils.
2 […]
Wolff, Philippe; Da Veiga, Cyrielle; Ennifar, Eric; Bec, Guillaume; Guichard, Gilles; Burnouf, Dominique; Dumas, Philippe;
Native ESI Mass Spectrometry Can Help to Avoid Wrong Interpretations from Isothermal Titration Calorimetry in Difficult Situations
Journal of the American Society for Mass Spectrometry, 2017, 28, 347-357
We studied by native ESI-MS the binding of various DNA-polymerase-derived peptides onto DNA-polymerase processivity rings from Escherichia coli, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. These homodimeric rings present two equivalent specific binding sites, which leads to successive formation during a titration experiment of singly- and doubly occupied rings. By using the ESI-MS free-ring spectrum as a ruler, we derived by robust linear regression the fractions of the different ring species at each step of a titration experiment. These results led to accurate K-d values (from 0.03 to 0.5 mu M) along with the probability of peptide loss due to gas phase dissociation (GPD). We show that this good quality is due to the increased information content of a titration experiment with a homodimer. Isothermal titration calorimetry (ITC) led with the same binding model to K-d(ITC) values systematically higher than their ESI-MS counterparts and, often, to poor fit of the ITC curves. A processing with two competing modes of binding on the same site requiring determination of two (K-d, Delta H) pairs greatly improved the fits and yielded a second K-d(ITC) close to K-d(ESI-MS). The striking features are: (1) ITC detected a minor binding mode (similar to 20%) of 'low-affinity' that did not appear with ESI-MS; (2) the simplest processing of ITC data with only one (K-d, Delta H) pair led wrongly to the Kd of the low-affinity binding mode but to the Delta H of the high-affinity binding mode. Analogous misleading results might well exist in published data based on ITC experiments.
3 […]
Wadeesirisak, Kanthida; Castano, Sabine; Berthelot, Karine; Vaysse, Laurent; Bonfils, Frederic; Peruch, Frederic; Rattanaporn, Kittipong; Liengprayoon, Siriluck; Lecomte, Sophie; Bottier, Celine;
Rubber particle proteins REF1 and SRPP1 interact differently with native lipids extracted from Hevea brasiliensis latex
Biochimica Et Biophysica Acta-Biomembranes, 2017, 1859, 201-210
Rubber particle membranes from the Hevea latex contain predominantly two proteins, REF1 and SRPP1 involved in poly(cis-1,4-isoprene) synthesis or rubber quality. The repartition of both proteins on the small or large rubber particles seems to differ, but their role in the irreversible coagulation of the rubber particle is still unknown. In this study we highlighted the different modes of interactions of both recombinant proteins with different classes of lipids extracted from Hevea brasiliensis latex, and defined as phospholipids (PL), glycolipids (GL) and neutral lipids (NL). We combined two biophysical methods, polarization modulated-infrared reflection adsorption spectroscopy (PM-IRRAS) and ellipsometry to elucidate their interactions with monolayers of each class of lipids. REF1 and SRPP1 interactions with native lipids are clearly different; SRPP1 interacts mostly in surface with PI, GL or NL, without modification of its structure. In contrast REF1 inserts deeply in the lipid monolayers with all lipid classes. With NI, REF1 is even able to switch from alpha-helice conformation to beta-sheet structure, as in its aggregated form (amyloid form). Interaction between REF1 and NL may therefore have a specific role in the irreversible coagulation of rubber particles. (C) 2016 Elsevier B.V. All rights reserved.
4 […]
Vallet-Courbin, Amelie; Lariviere, Melusine; Hocquellet, Agnes; Hemadou, Audrey; Parimala, Sarjapura-Nagaraja; Laroche-Traineau, Jeanny; Santarelli, Xavier; Clofent-Sanchez, Gisele; Jacobin-Valat, Marie-Josee; Noubhani, Abdelmajid;
A Recombinant Human Anti-Platelet scFv Antibody Produced in Pichia pastoris for Atheroma Targeting
PloS one, 2017, 12, e0170305-e0170305
Cells of the innate and adaptive immune system are key factors in the progression of atherosclerotic plaque, leading to plaque instability and rupture, potentially resulting in acute atherothrombotic events such as coronary artery disease, cerebrovascular disease and peripheral arterial disease. Here, we describe the cloning, expression, purification, and immunoreactivity assessment of a recombinant single-chain variable fragment (scFv) derived from a human anti-alphaIIbbeta3 antibody (HuAb) selected to target atheromatous lesions for the presence of platelets. Indeed, platelets within atheroma plaques have been shown to play a role in inflammation, in platelet-leucocyte aggregates and in thrombi formation and might thus be considered relevant biomarkers of atherosclerotic progression. The DNA sequence that encodes the anti-alphaIIbbeta3 TEG4 scFv previously obtained from a phage-display selection on activated platelets, was inserted into the eukaryote vector (pPICZalphaA) in fusion with a tag sequence encoding 2 cysteines useable for specific probes grafting experiments. The recombinant protein was expressed at high yields in Pichia pastoris (30 mg/L culture). The advantage of P. pastoris as an expression system is the production and secretion of recombinant proteins in the supernatant, ruling out the difficulties encountered when scFv are produced in the cytoplasm of bacteria (low yield, low solubility and reduced affinity). The improved conditions allowed for the recovery of highly purified and biologically active scFv fragments ready to be grafted in a site-directed way to nanoparticles for the imaging of atherosclerotic plaques involving inflammatory processes and thus at high risk of instability.
5 […]
Smulski, Cristian R.; Decossas, Marion; Chekkat, Neila; Beyrath, Julien; Willen, Laure; Guichard, Gilles; Lorenzetti, Raquel; Rizzi, Marta; Eibel, Hermann; Schneider, Pascal; Fournel, Sylvie;
Hetero-oligomerization between the TNF receptor superfamily members CD40, Fas and TRAILR2 modulate CD40 signalling
Cell Death & Disease, 2017, 8,
TNF receptor superfamily members (TNFRSF) such as CD40, Fas and TRAIL receptor 2 (TRAILR2) participate to the adaptive immune response by eliciting survival, proliferation, differentiation and/or cell death signals. The balance between these signals determines the fate of the immune response. It was previously reported that these receptors are able to self-assemble in the absence of ligand through their extracellular regions. However, the role of this oligomerization is not well understood, and none of the proposed hypotheses take into account potential hetero-association of receptors. Using CD40 as bait in a flow cytometry Forster resonance energy transfer assay, TNFRSF members with known functions in B cells were probed for interactions. Both Fas and TRAILR2 associated with CD40. Immunoprecipitation experiments confirmed the interaction of CD40 with Fas at the endogenous levels in a BJAB B-cell lymphoma cell line deficient for TRAILR2. TRAILR2-expressing BJAB cells displayed a robust CD40-TRAILR2 interaction at the expense of the CD40-Fas interaction. The same results were obtained by proximity ligation assay, using TRAILR2-positive and -negative BJAB cells and primary human B cells. Expression of the extracellular domains of Fas or TRAILR2 with a glycolipid membrane anchor specifically reduced the intrinsic signalling pathway of CD40 in 293T cells. Conversely, BJAB cells lacking endogenous Fas or TRAILR2 showed an increased NF-kappa B response to CD40L. Finally, upregulation of TRAILR2 in primary human B cells correlated with reduced NF-kappa B activation and reduced proliferation in response to CD40L. Altogether, these data reveal that selective interactions between different TNFRSF members may modulate ligand-induced responses upstream signalling events.
6 […]
Petitdemange, Rosine; Garanger, Elisabeth; Bataille, Laure; Dieryck, Wilfrid; Bathany, Katell; Garbay, Bertrand; Deming, Timothy J.; Lecommandoux, Sebastien;
Selective Tuning of Elastin-like Polypeptide Properties via Methionine Oxidation
Biomacromolecules, 2017, 18, 544-550
We have designed and prepared a recombinant elastin-like polypeptide (ELP) containing precisely positioned methionine residues, and performed the selective and complete oxidation of its methionine thioether groups to both sulfoxide and sulfone derivatives. Since these oxidation reactions substantially increase methionine residue polarity, they were found to be a useful means to precisely adjust the temperature responsive behavior of ELPs in aqueous solutions. In particular, lower critical solution temperatures were found to be elevated in oxidized sample solutions, but were not eliminated. These transition temperatures were found to be further tunable by the use of solvents containing different Hofmeister salts. Overall, the ability to selectively and fully oxidize methionine residues in ELPs proved to be a convenient postmodification strategy for tuning their transition temperatures in aqueous media.
7 […]
Petitdemange, Rosine; Garanger, Elisabeth; Bataille, Laure; Bathany, Katell; Garbay, Bertrand; Deming, Timothy J.; Lecommandoux, Sebastien;
Tuning Thermoresponsive Properties of Cationic Elastin-like Polypeptides by Varying Counterions and Side-Chains
Bioconjugate chemistry, 2017, 0,
We report the synthesis of methionine-containing recombinant elastin-like polypeptides (ELPs) of different lengths that contain periodically spaced methionine residues. These ELPs were chemoselectively alkylated at all methionine residues to give polycationic derivatives. Some of these samples were found to possess solubility transitions in water, where the temperature of these transitions varied with ELP concentration, nature of the methionine alkylating group, and nature of the sulfonium counterions. These studies show that introduction and controlled spacing of methionine sulfonium residues into ELPs can be used as a means both to tune their solubility transition temperatures in water using a variety of different parameters and to introduce new side-chain functionality.
8 […]
Mendoza, Oscar; Houmadi, Said; Aime, Jean-Pierre; Elezgaray, Juan;
Signal replication in a DNA nanostructure
Journal of Chemical Physics, 2017, 146,
Logic circuits based on DNA strand displacement reaction are the basic building blocks of future nanorobotic systems. The circuits tethered to DNA origami platforms present several advantages over solution-phase versions where couplings are always diffusion-limited. Here we consider a possible implementation of one of the basic operations needed in the design of these circuits, namely, signal replication. We showthat with an appropriate preparation of the initial state, signal replication performs in a reproducible way. We also show the existence of side effects concomitant to the high effective concentrations in tethered circuits, such as slow leaky reactions and cross-activation. Published by AIP Publishing.
9 […]
Loquet, Antoine; Saupe, Sven J.;
Diversity of Amyloid Motifs in NLR Signaling in Fungi
Biomolecules, 2017, 7,
Amyloid folds not only represent the underlying cause of a large class of human diseases but also display a variety of functional roles both in prokaryote and eukaryote organisms. Among these roles is a recently-described activity in signal transduction cascades functioning in host defense and programmed cell death and involving Nod-like receptors (NLRs). In different fungal species, prion amyloid folds convey activation signals from a receptor protein to an effector domain by an amyloid templating and propagation mechanism. The discovery of these amyloid signaling motifs derives from the study of [Het-s], a fungal prion of the species Podospora anserina. These signaling pathways are typically composed of two basic components encoded by adjacent genes, the NLR receptor bearing an amyloid motif at the N-terminal end and a cell death execution protein with a HeLo pore-forming domain bearing a C-terminal amyloid motif. Activation of the NLR receptor allows for amyloid folding of the N-terminal amyloid motifs which then template trans-conformation of the homologous motif in the cell death execution protein. A variety of such motifs, which differ by their sequence signature, have been described in fungi. Among them, the PP-motif bears resemblance with the RHIM amyloid motif involved in the necroptosis pathway in mammals suggesting an evolutionary conservation of amyloid signaling from fungi to mammals.
10 […]
Liu, Z. W.; Hu, X. B.; Abramyan, A. M.; Meszaros, A.; Csekei, M.; Kotschy, A.; Huc, I.; Pophristic, V.;
Computational Prediction and Rationalization, and Experimental Validation of Handedness Induction in Helical Aromatic Oligoamide Foldamers
Chemistry-a European Journal, 2017, 23, 3605-3615
Metadynamics simulations were used to describe the conformational energy landscapes of several helically folded aromatic quinoline carboxamide oligomers bearing a single chiral group at either the C or Nterminus. The calculations allowed the prediction of whether a helix handedness bias occurs under the influence of the chiral group and gave insight into the interactions (sterics, electrostatics, hydrogen bonds) responsible for a particular helix sense preference. In the case of camphanyl-based and morpholine-based chiral groups, experimental data confirming the validity of the calculations were already available. New chiral groups with a proline residue were also investigated and were predicted to induce handedness. This prediction was verified experimentally through the synthesis of proline-containing monomers, their incorporation into an oligoamide sequence by solid phase synthesis and the investigation of handedness induction by NMR spectroscopy and circular dichroism.
11 […]
Linares, Romain; Tan, Sisareuth; Gounou, Celine; Brisson, Alain R.;
Imaging and Quantification of Extracellular Vesicles by Transmission Electron Microscopy
Methods in molecular biology (Clifton, N.J.), 2017, 1545, 43-54
Extracellular vesicles (EVs) are cell-derived vesicles that are present in blood and other body fluids. EVs raise major interest for their diverse physiopathological roles and their potential biomedical applications. However, the characterization and quantification of EVs constitute major challenges, mainly due to their small size and the lack of methods adapted for their study. Electron microscopy has made significant contributions to the EV field since their initial discovery. Here, we describe the use of two transmission electron microscopy (TEM) techniques for imaging and quantifying EVs. Cryo-TEM combined with receptor-specific gold labeling is applied to reveal the morphology, size, and phenotype of EVs, while their enumeration is achieved after high-speed sedimentation on EM grids.
12 […]
Legrand, Bernard; Salvetat, Jean-Paul; Walter, Benjamin; Faucher, Marc; Theron, Didier; Aime, Jean-Pierre;
Multi-MHz micro-electro-mechanical sensors for atomic force microscopy
Ultramicroscopy, 2017, 175, 46-57
Silicon ring-shaped micro-electro-mechanical resonators have been fabricated and used as probes for dynamic atomic force microscopy (AFM) experiments. They offer resotnance frequency above 10MHz, which is notably greater than that of usual cantilevers and quartz-based AFM probes. On-chip electrical actuation and readout of the tip oscillation are obtained by means of built-in capacitive transducers. Displacement and force resolutions have been determined from noise analysis at 1.5fm/Hz and 0.4 pN/Hz, respectively. Despite the high effective stiffness of the probes, the tip-surface interaction force is kept below 1 nN by using vibration amplitude significantly below 100pm and setpoint close to the free vibration conditions. Imaging capabilities in amplitude- and frequency-modulation AFM modes have been demonstrated on block copolymer surfaces. Z-spectroscopy experiments revealed that the tip is vibrating in permanent contact with the viscoelastic material, with a pinned contact line. Results are compared to those obtained with commercial AFM cantilevers driven at large amplitudes (>10nm).
13 […]
LEGERON, Rachel; XUEREB, Fabien; BREILH, Dominique; GADEAU, Alain Pierrre; BOIRON, Jean-Michel; SCHMITTER, Jean-Marie; DUPUY, Jean-William; CHAIGNEPAIN, Stéphane;
, 2017, 0,
The present invention relates to the use of an Internal Standard compound in a method for quantifying Bevacizumab in a sample by mass spectrometry, wherein the said Internal Standard compound is described in the specification.
14 […]
Lefevre, M.; Racedo, S. M.; Denayrolles, M.; Ripert, G.; Desfougeres, T.; Lobach, A. R.; Simon, R.; Pelerin, F.; Justen, P.; Urdaci, M. C.;
Safety assessment of Bacillus subtilis CU1 for use as a probiotic in humans
Regulatory Toxicology and Pharmacology, 2017, 83, 54-65
Bacillus subtilis CU1 is a recently described probiotic strain with beneficial effects on immune health in elderly subjects. The following work describes a series of studies supporting the safety of the strain for use as an ingredient in food and supplement preparations. Using a combination of 16S rDNA and gyrB nucleotide analyses, the species was identified as a member of the Bacillus subtilis complex (B. subtilis subsp. spizizenii). Further characterization of the organism at the strain level was achieved using random amplified polymorphic DNA polymerase chain reaction (RAPD PCR) and pulsed field gel electrophoresis (PFGE) analyses. B. subtilis CU1 did not demonstrate antibiotic resistance greater than existing regulatory cutoffs against clinically important antibiotics, did not induce hemolysis or produce surfactant factors, and was absent of toxigenic activity in vitro. Use of B. subtilis CU1 as a probiotic has recently been evaluated in a 16-week randomized, double-blind, placebo-controlled, parallel-arm study, in which 2 x 10(9) spores per day of B. subtilis CU1 were administered for a total 40 days to healthy elderly subjects (4 consumption periods of 10 days separated by 18-day washouts). This work describes safety related endpoints not previously reported. B. subtilis CU1 was safe and well-tolerated in the clinical subjects without undesirable physiological effects on markers of liver and kidney function, complete blood counts, hemodynamic parameters, and vital signs. (C) 2016 The Authors. Published by Elsevier Inc.
15 […]
Jewginski, Michal; Granier, Thierry; Langlois d'Estaintot, Beatrice; Fischer, Lucile; Mackereth, Cameron D.; Huc, Ivan;
Self-Assembled Protein-Aromatic Foldamer Complexes with 2:3 and 2:2:1 Stoichiometries
Journal of the American Chemical Society, 2017, 139, 2928-2931
The promotion of protein dimerization using the aggregation properties of a protein ligand was explored and shown to produce complexes with unusual stoichiometries. Helical foldamer 2 was synthesized and bound to human carbonic anhydrase (HCA) using a nanomolar active site ligand. Crystal structures show that the hydrophobicity of 2 and interactions of its side chains lead to the formation of an HCA2-23 complex in which three helices of 2 are stacked, two of them being linked to an HCA molecule. The middle foldamer in the stack can be replaced by alternate sequences 3 or 5. Solution studies by CD and NMR confirm left-handedness of the helical foldamers as well as HCA dimerization.
16 […]
Gyorgy, Bence; Sage, Cyrille; Indzhykulian, Artur A.; Scheffer, Deborah I.; Brisson, Alain R.; Tan, Sisareuth; Wu, Xudong; Volak, Adrienn; Mu, Dakai; Tamvakologos, Panos I.; Li, Yaqiao; Fitzpatrick, Zachary; Ericsson, Maria; Breakefield, Xandra O.; Corey, David P.; Maguire, Casey A.;
Rescue of Hearing by Gene Delivery to Inner-Ear Hair Cells Using Exosome-Associated AAV
Molecular therapy : the journal of the American Society of Gene Therapy, 2017, 25, 379-391
Adeno-associated virus (AAV) is a safe and effective vector for gene therapy for retinal disorders. Gene therapy for hearing disorders is not as advanced, in part because gene delivery to sensory hair cells of the inner ear is inefficient. Although AAV transduces the inner hair cells of the mouse cochlea, outer hair cells remain refractory to transduction. Here, we demonstrate that a vector, exosome-associated AAV (exo-AAV), is a potent carrier of transgenes to all inner ear hair cells. Exo-AAV1-GFP is more efficient than conventional AAV1-GFP, both in mouse cochlear explants invitro and with direct cochlear injection invivo. Exo-AAV shows no toxicity invivo, as assayed by tests of auditory and vestibular function. Finally, exo-AAV1 gene therapy partially rescues hearing in a mouse model of hereditary deafness (lipoma HMGIC fusion partner-like 5/tetraspan membrane protein of hair cell stereocilia [Lhfpl5/Tmhs-/-]). Exo-AAV is a powerful gene delivery system for hair cell research and may be useful for gene therapy for deafness.
17 […]
GUICHARD, Gilles; (FR).; COLLIE, Gavin; (GB).; PULKA-ZIACH, Karolina; (PL).; LOMBARDO, Caterina; (IT).; FREMAUX, Juliette; (FR) ;
, 2017, 0,
The present description provides compositions and methods for producing therapeutic oligomeric compounds. In another aspect the description provides methods for administering the oligomeric compounds for the treatment and prevention of disease in a mammal. In particular, the disclosure relates to medicaments comprising various novel oligomeric compounds and pharmaceutically acceptable salts thereof. The compounds of the disclosure may optionally be administered with at least one of a pharmaceutically acceptable excipient, additional pharmacologically active agent or a combination thereof.
18 […]
GUICHARD, Gilles; COLLIE, Gavin; PULKA-ZIACH, Karolina; LOMBARDO, Caterina; FREMAUX, Juliette;
, 2017, 0,
The present description provides compositions and methods for producing therapeutic oligomeric compounds. In another aspect the description provides methods for administering the oligomeric compounds for the treatment and prevention of disease in a mammal. In particular, the disclosure relates to medicaments comprising various novel oligomeric compounds and pharmaceutically acceptable salts thereof. The compounds of the disclosure may optionally be administered with at least one of a pharmaceutically acceptable excipient, additional pharmacologically active agent or a combination thereof.
19 […]
Goto, Taisei; Okazaki, Yutaka; Ueki, Masahiro; Kuwahara, Yutaka; Takafuji, Makoto; Oda, Reiko; Ihara, Hirotaka;
Induction of Strong and Tunable Circularly Polarized Luminescence of Nonchiral, Nonmetal, Low-Molecular-Weight Fluorophores Using Chiral Nanotemplates
Angewandte Chemie-International Edition, 2017, 56, 2989-2993
A new strategy is described for generating strong circularly polarized luminescence with highly tunable emission bands through chiral induction in nonchiral, totally organic, low-molecular-weight fluorescent dyes by chiral nanotemplate systems. Our approach allows the first systematic investigation to clarify the correlation between the circular dichroism and circularly polarized luminescence intensities. As a result, a dilute solution system with the highest circularly polarized luminescence intensity achieved to date and a dissymmetry factor of over 0.1 was identified.
20 […]
Goibier, Lucie; Lecomte, Sophie; Leal-Calderon, Fernando; Faure, Chrystel;
The effect of surfactant crystallization on partial coalescence in O/W emulsions
Journal of colloid and interface science, 2017, 500, 304-314
Partial coalescence is a ubiquitous instability in emulsions whose dispersed phase is partially crystallized. When emulsions are stabilized with proteins, interfacial stiffness and long-range repulsive surface forces hinder this type of instability. The addition of low molecular weight surfactants modifies the interfacial properties and surface forces, generally promoting partial coalescence. In the present work, various surfactants (Tween 80, palmitic acid and monoglycerides) differing in their crystallization temperature were probed for their ability to induce partial coalescence in model O/W emulsions stabilized by sodium caseinate. The initially fluid emulsions were submitted to a tempering cycle leading to the gelation of the system. The extent of partial coalescence was evaluated by measuring the bulk storage modulus. DSC was used to determine the melting range of the oil phase and surfactants, while polarized microscopy, Raman imaging, and surface rheology measurements were performed to characterize the oil/water interface. The experimental conditions in terms of droplet size, surfactant-to-protein molar ratio and tempering history favoring partial coalescence were first explored in presence of Tween 80. We show that partial coalescence is rather marginal when crystallizable surfactants are added, and pronounced with liquid surfactants. The phenomena underlying this result, especially interfacial crystallization of surfactants, are evidenced and discussed.
21 […]
Gan, Quan; Wang, Xiang; Kauffmann, Brice; Rosu, Frederic; Ferrand, Yann; Huc, Ivan;
Translation of rod-like template sequences into homochiral assemblies of stacked helical oligomers
Nature nanotechnology, 2017, 0,
At the molecular level, translation refers to the production of a new entity according to a template that has a different chemical composition. In this way, chemical information may be translated from one molecule to another. The process is useful to synthesize structures and thus functions that might be difficult to create otherwise, and it reaches exquisite levels of efficiency in biological systems, as illustrated by protein expression from mRNA templates or by the assembly of the tobacco mosaic virus capsid protein according to the length of its RNA. In synthetic systems, examples of template-directed syntheses are numerous, but general and versatile schemes in which a non-natural sequence actually encodes the information necessary to produce a different sequence are few and far from being optimized. Here we show a high-fidelity enzyme-free translation of long rod-like alkylcarbamate oligomers into well-defined sequences of stacked helical aromatic oligoamides. The features present in the rods, which include the number and distance between carbamate functions and stereogenic centres, template the self-assembly of complementary stacks of helices that each have a defined right (P) or left (M) handedness, length and single or double helicity. This process enables the production of very large (>20 kDa) abiotic artificial folded architectures (foldamers) that may, for example, serve as scaffolds to organize appended functional features at positions in space defined with atomic precision across nanometric distances.
22 […]
Dufour, Florent; Rattier, Thibault; Shirley, Sarah; Picarda, Gaelle; Constantinescu, Andrei Alexandru; Morle, Aymeric; Zakaria, Al Batoul; Marcion, Guillaume; Causse, Sebastien; Szegezdi, Eva; Zajonc, Dirk Michael; Seigneuric, Renaud; Guichard, Gilles; Gharbi, Tijani; Picaud, Fabien; Herlem, Guillaume; Garrido, Carmen; Schneider, Pascal; Benedict, Chris Alan; Micheau, Olivier;
N-glycosylation of mouse TRAIL-R and human TRAIL-R1 enhances TRAIL-induced death
Cell Death and Differentiation, 2017, 24, 500-510
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.
23 […]
Dufour, Florent; Rattier, Thibault; Constantinescu, Andrei Alexandru; Zischler, Luciana; Morle, Aymeric; Ben Mabrouk, Hazem; Humblin, Etienne; Jacquemin, Guillaume; Szegezdi, Eva; Delacote, Fabien; Marrakchi, Naziha; Guichard, Gilles; Pellat-Deceunynck, Catherine; Vacher, Pierre; Legembre, Patrick; Garrido, Carmen; Micheau, Olivier;
TRAIL receptor gene editing unveils TRAIL-R1 as a master player of apoptosis induced by TRAIL and ER stress
Oncotarget, 2017, 8, 9974-9985
TRAIL induces selective tumor cell death through TRAIL-R1 and TRAIL-R2. Despite the fact that these receptors share high structural homologies, induction of apoptosis upon ER stress, cell autonomous motility and invasion have solely been described to occur through TRAIL-R2. Using the TALEN gene-editing approach, we show that TRAIL-R1 can also induce apoptosis during unresolved unfolded protein response (UPR). Likewise, TRAIL-R1 was found to co-immunoprecipitate with FADD and caspase-8 during ER stress. Its deficiency conferred resistance to apoptosis induced by thaspigargin, tunicamycin or brefeldin A. Our data also demonstrate that tumor cell motility and invasion-induced by TRAIL-R2 is not cell autonomous but induced in a TRAIL-dependant manner. TRAIL-R1, on the other hand, is unable to trigger cell migration owing to its inability to induce an increase in calcium flux. Importantly, all the isogenic cell lines generated in this study revealed that apoptosis induced TRAIL is preferentially induced by TRAIL-R1. Taken together, our results provide novel insights into the physiological functions of TRAIL-R1 and TRAIL-R2 and suggest that targeting TRAIL-R1 for anticancer therapy is likely to be more appropriate owing to its lack of pro-motile signaling capability.
24 […]
Dridi, Wafa; Toutain, Jean; Sommier, Alain; Essafi, Wafa; Leal-Calderon, Fernando; Cansell, Maud;
Direct technique for monitoring lipid oxidation in water-in-oil emulsions based on micro-calorimetry
Food chemistry, 2017, 230, 563-566
An experimental device based on the measurement of the heat flux dissipated during chemical reactions, previously validated for monitoring lipid oxidation in plant oils, was extended to follow lipid oxidation in water-in-oil emulsions. Firstly, validation of the approach was performed by correlating conjugated diene concentrations measured by spectrophotometry and the heat flux dissipated by oxidation reactions and measured directly in water-in-oil emulsions, in isothermal conditions at 60°C. Secondly, several emulsions based on plant oils differing in their n-3 fatty acid content were compared. The oxidability parameter derived from the enthalpy curves reflected the alpha-linolenic acid proportion in the oils. On the whole, the micro-calorimetry technique provides a sensitive method to assess lipid oxidation in water-in-oil emulsions without requiring any phase extraction.
25 […]
Colombani, Thibault; Peuziat, Pauline; Dallet, Laurence; Haudebourg, Thomas; Mevel, Mathieu; Berchel, Mathieu; Lambert, Olivier; Habrant, Damien; Pitard, Bruno;
Self-assembling complexes between binary mixtures of lipids with different linkers and nucleic acids promote universal mRNA, DNA and siRNA delivery
Journal of controlled release : official journal of the Controlled Release Society, 2017, 249, 131-142
Protein expression and RNA interference require efficient delivery of DNA or mRNA and small double stranded RNA into cells, respectively. Although cationic lipids are the most commonly used synthetic delivery vectors, a clear need still exists for a better delivery of various types of nucleic acids molecules to improve their biological activity. To optimize the transfection efficiency, a molecular approach consisting in modifying the chemical structure of a given cationic lipid is usually performed, but an alternative strategy could rely on modulating the supramolecular assembly of lipidic lamellar phases sandwiching the nucleic acids molecules. To validate this new concept, we synthesized on one hand two paromomycin-based cationic lipids, with either an amide or a phosphoramide linker, and on the other hand two imidazole-based neutral lipids, having as well either an amide or a phosphoramide function as linker. Combinations of cationic and helper lipids containing the same amide or phosphoramide linkers led to the formation of homogeneous lamellar phases, while hybrid lamellar phases were obtained when the linkers on the cationic and helper lipids were different. Cryo-transmission electron microscopy and fluorescence experiments showed that liposomes/nucleic acids complexes resulting from the association of nucleic acids with hybrid lamellar phases led to complexes that were more stable in the extracellular compartment compared to those obtained with homogeneous systems. In addition, we observed that the most active supramolecular assemblies for the delivery of DNA, mRNA and siRNA were obtained when the cationic and helper lipids possess linkers of different natures. The results clearly show that this supramolecular strategy modulating the property of the lipidic lamellar phase constitutes a new approach for increasing the delivery of various types of nucleic acid molecules.
26 […]
Collie, Gavin W.; Bailly, Remy; Pulka-Ziach, Karolina; Lombardo, Caterina M.; Mauran, Laura; Taib-Maamar, Nada; Dessolin, Jean; Mackereth, Cameron D.; Guichard, Gilles;
Molecular Recognition within the Cavity of a Foldamer Helix Bundle: Encapsulation of Primary Alcohols in Aqueous Conditions
Journal of the American Chemical Society, 2017, 0,
Artificial synthetic molecules able to adopt well-defined stable secondary structures comparable to those found in nature ("foldamers") have considerable potential for use in a range of applications such as biomaterials, biorecognition, nanomachines and as therapeutic agents. The development of foldamers with the ability to bind and encapsulate "guest" molecules is of particular interest; as such an ability is a key step toward the development of artificial sensors, receptors and drug-delivery vectors. Although significant progress has been reported within this context, foldamer capsules reported thus far are largely restricted to organic solvent systems, and it is likely that the move to aqueous conditions will prove challenging. Toward this end, we report here structural studies into the ability of a recently reported water-soluble self-assembled foldamer helix bundle to encapsulate simple guest molecules within an internal cavity. Seven high-resolution aqueous crystal structures are reported, accompanied by molecular dynamics and high-field NMR solution data, showing for the first time that encapsulation of guests by a complex self-assembled foldamer in aqueous conditions is possible. The findings also provide ample insight for the future functional development of this system.
27 […]
Cheng, Jiaji; Le Saux, Guillaume; Gao, Jie; Buffeteau, Thierry; Battie, Yann; Barois, Philippe; Ponsinet, Virginie; Delville, Marie-Helene; Ersen, Ovidiu; Pouget, Emilie; Oda, Reiko;
GoldHelix: Gold Nanoparticles Forming 3D Helical Superstructures with Controlled Morphology and Strong Chiroptical Property
ACS nano, 2017, 0,
Plasmonic nanoparticles, particularly gold nanoparticles (GNPs) hold a great potential as structural and functional building blocks for three-dimensional (3D) nanoarchitectures with specific optical applications. However, a rational control of their assembly into nanoscale superstructures with defined positioning and overall arrangement still remains challenging. Herein, we propose a solution to this challenge by using as building blocks: (1) nanometric silica helices with tunable handedness and sizes as a matrix and (2) GNPs with diameter varying from 4 to 10 nm to prepare a collection of helical GNPs superstructures (called Goldhelices hereafter). These nanomaterials exhibit well-defined arrangement of GNPs following the helicity of the silica template. Strong chiroptical activity is evidenced by circular dichroism (CD) spectroscopy at the wavelength of the surface plasmon resonance (SPR) of the GNPs with a anisotropy factor (g-factor) of the order of 1 * 10-4, i.e., 10-fold larger than what is typically reported in the literature. Such CD signals were simulated using a coupled dipole method which fit very well the experimental data. The measured signals are 1-2 orders of magnitude lower than the simulated signals, which is explained by the disordered GNPs grafting, the polydispersity of the GNPs, and the dimension of the nanohelices. These Goldhelices based on inorganic templates are much more robust than previously reported organic-based chiroptical nanostructures, making them good candidates for complex hierarchical organization, providing a promising approach for light management and benefits in applications such as circular polarizers, chiral metamaterials, or chiral sensing in the visible range.
28 […]
Cartier, Flora; Indersie, Emilie; Lesjean, Sarah; Charpentier, Justine; Hooks, Katarzyna B.; Ghousein, Amani; Desplat, Angelique; Dugot-Senant, Nathalie; Trezeguet, Veronique; Sagliocco, Francis; Hagedorn, Martin; Grosset, Christophe F.;
New tumor suppressor microRNAs target glypican-3 in human liver cancer
Oncotarget, 2017, 0,
Glypican-3 (GPC3) is an oncogene, frequently upregulated in liver malignancies such as hepatocellular carcinoma (HCC) and hepatoblastoma and constitutes a potential molecular target for therapy in liver cancer. Using a functional screening system, we identified 10 new microRNAs controlling GPC3 expression in malignant liver cells, five of them e.g. miR-4510, miR-203a-3p, miR-548aa, miR-376b-3p and miR-548v reduce GPC3 expression. These 5 microRNAs were significantly downregulated in tumoral compared to non-tumoral liver and inhibited tumor cell proliferation. Interestingly, miR-4510 inversely correlated with GPC3 mRNA and protein in HCC samples. This microRNA also induced apoptosis of hepatoma cells and blocked tumor growth in vivo in the chick chorioallantoic membrane model. We further show that the tumor suppressive effect of miR-4510 is mediated through direct targeting of GPC3 mRNA and inactivation of Wnt/beta-catenin transcriptional activity and signaling pathway. Moreover, miR-4510 up-regulated the expression of several tumor suppressor genes while reducing the expression of other pro-oncogenes. In summary, we uncovered several new microRNAs targeting the oncogenic functions of GPC3. We provided strong molecular, cellular and in vivo evidences for the tumor suppressive activities of miR-4510 bringing to the fore the potential value of this microRNA in HCC therapy.
29 […]
Carasi, Paula; Racedo, Silvia Maria; Jacquot, Claudine; Elie, Anne Marie; de los Angeles Serradell, Maria; Urdaci, Maria C.;
Enterococcus durans EP1 a Promising Anti-inflammatory Probiotic Able to Stimulate slgA and to Increase Faecalibacterium prausnitzii Abundance
Frontiers in Immunology, 2017, 8,
Enterococcus species, principally Enterococcus faecium are used as probiotics since a long time with preference in animal applications but safety considerations were updated and also new uses as probiotics can be envisaged. Fifteen Enterococcus strains isolated from different foods were identified and analyzed for virulence factors and antibiotic resistance. Three Enterococcus durans strains were selected to study their immunomodulatory properties on PBMC and Caco2 cells. Two strains presented a profile toward a mild inflammatory Th1 response considering TNF-alpha/IL-10 and IL-1 beta/IL-10 cytokines ratios. The third strain EP1, presented an anti-inflammatory potential and was selected for in vivo studies. In mice, the strain was well tolerated and did not cause any adverse effects. EP1 administration increased the amount of IgA+ cells in mesenteric lymph node (MLN) after 7 days of administration. In fecal samples, the IgA content increased gradually and significantly from day 7 to day 21 in treated group. Additionally, IL-17, IL-6, IL-1 beta, IFN-gamma, and CXCL1 gene expression significantly decreased on day 21 in Peyer's patches and IL-17 decreased in MLN. Mice treated with the probiotic showed significant lower mRNA levels of pro-inflammatory cytokines and mucins in the ileum at day 7 while their expression was normalized at day 21. Colonic expression of il-1 beta, il6, and mucins remain diminished at day 21. Ileum and colon explants from treated mice stimulated in vitro with LPS showed a significant reduction in IL-6 and an increase in IL-10 secretion suggesting an in vivo protective effect of the probiotic treatment against a proinflammatory stimulus. Interestingly, analysis of feces microbiota demonstrated that EP1 administration increase the amount of Faecalibacterium prausnitzii, a butyrate-producing bacteria, which is known for its anti-inflammatory effects. In conclusion, we demonstrated that EP1 strain is a strong sIgA inducer and possess mucosal anti-inflammatory properties. This strain also modulates gut microbiota increasing Faecalibacterium prausnitzii, a functionally important bacterium. Thus, E. durans EP1 is not only a good candidate to increases F. prausnitzii in some cases of dysbiosis but can also be interesting in gut inflammatory disorders therapy.
30 […]
Brisson, Alain R.; Tan, Sisareuth; Linares, Romain; Gounou, Celine; Arraud, Nicolas;
Extracellular vesicles from activated platelets: a semiquantitative cryo-electron microscopy and immuno-gold labeling study
Platelets, 2017, 0, 1-9
Cells release membrane vesicles in their surrounding medium either constitutively or in response to activating signals. Two main types of extracellular vesicles (EVs) are commonly distinguished based on their mechanism of formation, membrane composition and size. According to the current model, EVs shed from the plasma membrane, often called microvesicles, expose phosphatidylserine (PS) and range in size from 100 nm to 1 m, while EVs originating from endosomal multi-vesicular bodies, called exosomes, contain tetraspanin proteins, including CD63, and range in size from 50 to 100 nm. Heijnen et al. [1] have shown that activated platelets release EVs corresponding to these two types of vesicles, using negative staining electron microscopy (EM) and immuno-gold labeling. Here, we apply cryo-EM and immuno-gold labeling to provide a quantitative analysis of EVs released by platelets activated by thrombin, TRAP and CRP-XL, as well as EVs from serum. We show that EVs activated by these three agonists present a similar size distribution, the majority of them forming a broad peak extending from 50 nm to 1 m, about 50% of them ranging from 50 to 400 nm. We show also that 60% of the EVs from TRAP or CRP-XL activation expose CD41, a majority of them exposing also PS. To explain the presence of large EVs CD41-negative or PS-negative, several alternative mechanisms of EV formation are proposed. We find also that the majority of EVs in activated platelet samples expose CD63, and distinguish two populations of CD63-positive EVs, namely large EVs with low labeling density and small EVs with high labeling density.
31 […]
Briffa, M.; Ghio, S.; Neuner, J.; Gauci, A. J.; Cacciottolo, R.; Marchal, C.; Caruana, M.; Cullin, C.; Vassallo, N.; Cauchi, R. J.;
Extracts from two ubiquitous Mediterranean plants ameliorate cellular and animal models of neurodegenerative proteinopathies
Neuroscience Letters, 2017, 638, 12-20
A signature feature of age-related neurodegenerative proteinopathies is the misfolding and aggregation of proteins, typically amyloid-beta (A beta) in Alzheimer's disease (AD) and alpha-synuclein (alpha-syn) in Parkinson's disease (PD), into soluble oligomeric structures that are highly neurotoxic. Cellular and animal models that faithfully replicate the hallmark features of these disorders are being increasing exploited to identify disease-modifying compounds. Natural compounds have been identified as a useful source of bioactive molecules with promising neuroprotective capabilities. In the present report, we investigated whether extracts derived from two ubiquitous Mediterranean plants namely, the prickly pear Opuntia ficus-indica (EOFI) and the brown alga Padina pavonica (EPP) alleviate neurodegenerative phenotypes in yeast (Saccharomyces cerevisiae) and fly (Drosophila melanogaster) models of AD and PD. Pre-treatment with EPP or EOFI in the culture medium significantly improved the viability of yeast expressing the Arctic A beta 42 (E22G) mutant. Supplementing food with EOFI or EPP dramatically ameliorated lifespan and behavioural signs of flies with brain-specific expression of wild-type A beta 42 (model of late-onset AD) or the Arctic A beta 42 variant (model of early-onset AD). Additionally, we show that either extract prolonged the survival of a PD fly model based on transgenic expression of the human alpha-syn A53T mutant. Taken together, our findings suggest that the plant-derived extracts interfere with shared mechanisms of neurodegeneration in AD and PD. This notion is strengthened by evidence demonstrating that EOFI and to a greater extent EPP, while strongly inhibiting the fibrillogenesis of both A beta 42 and alpha-syn, accumulate remodelled oligomeric aggregates that are less effective at disrupting lipid membrane integrity. Our work therefore opens new avenues for developing therapeutic applications of these natural plant extracts in the treatment of amyloidogenic neurodegenerative disorders. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
32 […]
Bonhommeau, S.; Talaga, D.; Hunel, J.; Cullin, C.; Lecomte, S.;
Tip-Enhanced Raman Spectroscopy to Distinguish Toxic Oligomers from Abeta1-42 Fibrils at the Nanometer Scale
Angew Chem Int Ed Engl, 2017, 56, 1771-1774
For the first time, natural Abeta1-42 fibrils (WT) implicated in Alzheimer's disease, as well as two synthetic mutants forming less toxic amyloid fibrils (L34T) and highly toxic oligomers (oG37C), are chemically characterized at the scale of a single structure using tip-enhanced Raman spectroscopy (TERS). While the proportion of TERS features associated with amino acid residues is similar for the three peptides, a careful examination of amide I and amide III bands allows us to clearly distinguish WT and L34T fibers organized in parallel beta-sheets from the small and more toxic oG37C oligomers organized in anti-parallel beta-sheets.
33 […]
Bobo, C.; Chaignepain, S.; Henry, S.; Vignaud, H.; Ameadan, A.; Marchal, C.; Prado, E.; Doutch, J.; Schmitter, J. M.; Nardin, C.; Lecomte, S.; Cullin, C.;
Synthetic toxic Abeta1-42 oligomers can assemble in different morphologies
Biochim Biophys Acta, 2017, 1861, 1168-1176
BACKGROUND: Alzheimer's disease is the most common neurodegenerative disease associated with aggregation of Abeta peptides. Abeta toxicity is mostly related to the capacity of intermediate oligomers to disrupt membrane integrity. We previously expressed Abeta1-42 in a eukaryotic cellular system and selected synthetic variants on their sole toxicity. The most toxic mutant G37C forms stable oligomers. METHODS: Different biophysical methods (Fluorescence spectroscopy, cross-linking, mass spectrometry (MS), Small Angle X-ray Scattering (SAXS), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), calcein leakage) were used. RESULTS: The oligomers are mostly populated by a 14mers resulting from the packing of homodimers. These homodimers come from the formation of a disulfide bridge between two monomers. This link stabilizes the multimers and prevents the assembly into amyloid fibrils. These oligomers affect the membrane integrity. The reduction of disulfide bonds leads to a rearrangement and redirects assembly of Abeta amyloid fibrils. CONCLUSION: The toxic synthetic AbetaG37C mutant can assemble into an amyloid of unusual morphology through the formation of anti-parallel beta-sheets. This pathway involves the formation of oligomers resulting from the arrangement of Abeta dimers linked by covalent di-sulfide link, being these oligomers harmful for the membranes. GENERAL SIGNIFICANCE: The capacity to produce large amount of stable oligomers without additional detergents or extrinsic cross-linkers allow further structural and biophysical studies to understand their capacity to assemble and disrupt the membranes, a key event in Alzheimer's disease.
34 […]
Bayard, Mathilde; Leal-Calderon, Fernando; Cansell, Maud;
Free fatty acids and their esters modulate isothermal crystallization of anhydrous milk fat
Food Chemistry, 2017, 218, 22-29
The effect of free fatty acids with different chain lengths or unsaturation degree on anhydrous milk fat (AMF) crystallization was evaluated. The impact of esterification was also studied using three triglycerides. Melted blends containing the additives at concentrations lower than 12 wt.% were quenched at 25 degrees C and isothermal crystallization was monitored by pulsed low-resolution nuclear magnetic resonance. In parallel, polarized light microscopy was used to observe the microstructure. Compounds based on long chain saturated fatty acids, i.e. palmitic, stearic, eicosanoic acids, tripalmitin and tristearin accelerated crystallization. Conversely, propanoic, hexanoic and oleic acids slowed down the process, while triacetin had no impact. Interestingly, above a critical concentration, the addition of palmitic, stearic or eicosanoic acids caused a transition from a one-step to two-step process. Gompertz model was used to fit the experimental data and to assess the influence of the molecular properties of the additives on the kinetic parameters. (C) 2016 Elsevier Ltd. All rights reserved.
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