Specific antiviral activities of the human α interferons are determined at the level of receptor (IFNAR) structure

AbstractDifferences in activity among the family of human IFNs α are much reduced if these ligands are assayed on bovine cells. In particular, the activity of IFN αD is much higher on bovine than on human cells. To examine these differences, the bovine counterpart of the human IFNAR has been cloned and expressed in a human cell line. The transfected cell line now recognizes the human IFN αD as a high-specific-activity IFN subtype, indicating that the differences in sensitivity between the bovine and human cells to the human IFN α lie in the structure of the IFNAR chain rather than in the other components of the functional receptor

Investigation of grain orientations of melt-textured HTSC with addition of uranium oxide, Y2O3 and Y2BaCuO5

Local grain orientations were studied in melt-textured YBCO samples processed with various amounts of depleted uranuim oxide (DU) and Y 2O3 by means of electron backscatter diffraction (EBSD) analysis. The addition of DU leads to the formation of Ucontaining nanoparticles (Y2Ba4CuUOx) with sizes of around 200 nm, embedded in the superconducting Y-123 matrix. The orientation of the Y 2BaCuO5 (Y-211) particles, which are also present in the YBCO bulk microstructure, is generally random as is the case in other melttextured Y-123 samples. The presence of Y-211 particles, however, also affects the orientation of the Y-123 matrix in these samples

Mycobacterium abscessus-Induced Granuloma Formation Is Strictly Dependent on TNF Signaling and Neutrophil Trafficking

Mycobacterium abscessus is considered the most common respiratory pathogen among the rapidly growing non-tuberculous mycobacteria. Infections with M. abscessus are increasingly found in patients with chronic lung diseases, especially cystic fibrosis, and are often refractory to antibiotic therapy. M. abscessus has two morphotypes with distinct effects on host cells and biological responses. The smooth (S) variant is recognized as the initial airway colonizer while the rough (R) is known to be a potent inflammatory inducer associated with invasive disease, but the underlying immunopathological mechanisms of the infection remain unsolved. We conducted a comparative stepwise dissection of the inflammatory response in S and R pathogenesis by monitoring infected transparent zebrafish embryos. Loss of TNFR1 function resulted in increased mortality with both variants, and was associated with unrestricted intramacrophage bacterial growth and decreased bactericidal activity. The use of transgenic zebrafish lines harboring fluorescent macrophages and neutrophils revealed that neutrophils, like macrophages, interact with M. abscessus at the initial infection sites. Impaired TNF signaling disrupted the IL8-dependent neutrophil mobilization, and the defect in neutrophil trafficking led to the formation of aberrant granulomas, extensive mycobacterial cording, unrestricted bacterial growth and subsequent larval death. Our findings emphasize the central role of neutrophils for the establishment and maintenance of the protective M. abscessus granulomas. These results also suggest that the TNF/IL8 inflammatory axis is necessary for protective immunity against M. abscessus and may be of clinical relevance to explain why immunosuppressive TNF therapy leads to the exacerbation of M. abscessus infections

Structure of the murine interferon alpha/beta receptor-encoding gene: high-frequency rearrangements in the interferon-resistant L1210 cell line

International audienc

Diversité des interferons et de leurs récepteurs chez le Danio rerio

Les IFNs sont un groupe de cytokines définis par leur activité antivirale. Chez les mammifères, ils sont divisés en trois groupes. Ils fixent tous des complexes récepteurs distincts et possèdent une structure génique différente. Les types I (principalement a et b) ont un seul exon, le type II (g) quatre exons et le type III ( ) cinq. Les types I et III constituent un sous-groupe connu sous le nom d'IFNs induits par les virus , car ils sont directement induits par une infection virale, alors que le type II ne l'est pas. La présence d'IFN induits par les virus et d'IFNg (possédant 4 exons) ont été signalé dans toute les études poussées chez les poissons, la plupart, sinon tous, possèdent plusieurs gènes codant pour ces IFNs. La classification des IFNs induits par les virus chez les poissons est très controversée, nous avons pris parti de les nommer IFN (possédant 5 exons). Au cours de cette thèse nous avons identifié un IFN en plus appartenant aux IFN s, nous avons caractérisé les propriétés des IFN s et IFNgs et nous avons identifié leurs complexes récepteurs in vivo. Le génome du danio code pour 4 IFN s et 2 IFNgs, nous avons montré que l'expression et le profil d'induction de ces IFNs sont différents, qu'ils possédaient une activité biologique antivirale et que les IFN s étaient capables de protéger contre l'infection virale. Finalement l'utilisation d'expériences de perte et de gain de fonction, nous ont permis d'identifier les composants transmembranaires des complexes récepteursInterferons are a group of cytokines defined by their antiviral activities. In mammals, IFNs are divided into three groups according to their receptor usage. In addition to using distinct receptor complexes, the three mammalian types of IFN also have distinct genetic structure: type I (mainly a and b ) IFN genes have a single exon, type II (g) IFNs have four exons, while type III ( ) IFNs have five. Type I and type III IFNs together constitute a distinct subgroup known as virus-induced IFNs as they are directly induced by viral infections while type II is not. Virus-induced fish IFNs and IFN g (with 4 exons) have now been reported in all deeply studied fish species; most, if not all, teleost species possess several genes encoding these IFNs. The classification of fish virus-induced IFNs remains controversial, we took advantage of naming IFN (with 5 exons). In this work we identified a fourth IFN, which belongs to IFN s, we characterized the properties of IFN s and IFNgs and we have found their receptor complexes in vivo. The danio genome encodes 4 IFN s and 2 IFNgs, we showed that the expression profile and induction of these IFNs are different, they possess antiviral biological activity and the IFN s were able to protect against the viral infection. Using loss of function and gain of function analysis, we finally identified the transmembrane components of their receptor complexesMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Holographic imaging of Zebrafish embryo blood flow with dually oriented illumination beams

International audienceAn holographic laser Doppler scheme using two illumination beams is proposed to image blood vessel in fish embryo. The coincidence of the reconstructed images made for each illumination orientation leads to an accurate z sectioning

Regard à travers le danio pour mieux comprendre les interactions hôte/pathogène

Le danio (zebrafish, poisson zèbre) offre de nombreux avantages qui ont motivé et validé son utilisation récente pour étudier la virulence de plusieurs pathogènes humains. Son système immunitaire, homologue à celui des mammifères, ainsi que la transparence de ses embryons, adaptée au suivi en temps réel des infections via l’utilisation de techniques d’imagerie, en font un modèle d’étude particulièrement innovant. Ses propriétés uniques permettent d’observer et de décrypter les interactions hôte-pathogène au niveau cellulaire, de décrire les événements physiopathologiques propres à chaque pathogène et les mécanismes de défense de l’hôte. Outre ces avantages en recherche fondamentale, ce modèle est également porteur d’applications médicales potentielles dans la découverte de nouvelles molécules anti-infectieuses

La chaperone Hsp40 Jjj1p et son rôle dans la biogenèse des ribosomes chez les Eucaryotes

Chez les Eucaryotes, deux réseaux de chaperones ont été décrits comme dédiés à la synthèse protéique et à la protection du protéome contre le stress. A coté de ces chaperonnes généralistes, d'autres sont spécifiquement impliquées dans des transitions structurales de protéines sur de larges complexes macromoléculaires. Au cours de cette thèse, nous avons identifié et caractérisé le rôle spécifique d'une chaperone Hsp40 dans la biogenèse des ribosomes. Jjj1p se lie tardivement à la particule pré-60S et permet la dissociation du récepteur d'export Arx1p. En absence de Jjj1p, le facteur pré-ribosomique Arx1p s'accumule anormalement sur les particules pré-60S cytoplasmiques, ce qui semble toxique pour la cellule. Nous avons montré que la fonction de Jjj1p dans la biogenèse des ribosomes est conservée dans l'évolution chez l'Homme et le poisson. Enfin, un crible de létalité synthétique nous a permis de mettre en évidence un lien entre Jjjp1 et la machinerie de dégradationThrough their action in protein folding, degradation, translocation across the membrane, and disassembly of complexes, molecular chaperones are very important for different cellular processes. Hsp70 and their Hsp40 partners are crucial in these processes. In eukaryotes, two chaperone networks have been described: a stress inducible network that protects the cellular proteome from stress and a stress-repressed chaperone network that is dedicated to protein biogenesis. Generally Hsp40/70 used to prevent polypeptide misfolding. But up to now, no chaperone has been shown to act specifically in ribosome biogenesis. We have shown that Jjj1p is required for the dissociation of the shuttling export receptor Arx1p from the late cytoplasmic pre-60S particles, relies on its chaperone activity. In jjj1D, Arx1p is abnormally accumulated in the cytoplasm on the pre-60S particle, which is toxic for the cell. The function of an Hsp40 chaperone in such a specific process is conserved throughout the evolutionMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Ontogenetic Changes in Blood Osmolality During the Postembryonic Development of Zebrafish ( Danio rerio )

The zebrafish Danio rerio is a teleost model species widely used in developmental genetics, biomedical studies, toxicology, and drug screening. Despite the interest of this species in research, little is known through indirect observations about its blood osmolality, which is a key parameter for diverse experiments. In this study, we directly measured blood osmolality using nano-osmometry at different stages of zebrafish postembryonic development. We found that blood osmolality is close to 240 mOsm·kg−1 in early larvae. It progressively increased to ∼270 mOsm·kg−1 during the larval development before reaching ∼300 mOsm·kg−1 after metamorphosis in juveniles and later in adults. These ontogenetic changes in blood osmolality illustrate the physiological changes in osmoregulation associated with postembryonic development, including metamorphosis. These values are of practical interest for adjusting the osmolality of fixatives and cell and tissue culture media for research using zebrafish as a model