Current Screens Based on the AlphaScreen™ Technology for Deciphering Cell Signalling Pathways

Global deciphering of signal transduction pathways represents a new challenge of the post-genomic era. However, for the majority of these signaling pathways the role(s), the function(s) and the interaction(s) of the signaling intermediates remain to be characterized in an integrated fashion. The global molecular study of cell signaling pathways and networks consequently requires sensitive, robust technologies which may allow in addition multi-parallel and highthroughput applications. The Alphascreen™ technology, relying on a bead-based homogenous approach, constitutes a valuable tool to detect and quantify a wide range of signaling events such as enzymatic activities or biomolecular interactions. In this article, we exhaustively review the literature and report the broad spectrum of Alphascreen™-based applications in the study of signal transduction pathways

Spadin, a Sortilin-Derived Peptide, Targeting Rodent TREK-1 Channels: A New Concept in the Antidepressant Drug Design

We found that spadin, a natural peptide derived from sortilin, blocks the mouse TREK-1 channel and might be an efficient and fast-acting antidepressant

IgA in the horse: cloning of equine polymeric Ig receptor and J chain and characterization of recombinant forms of equine IgA

As in other mammals, immunoglobulin A (IgA) in the horse has a key role in immune defense. To better dissect equine IgA function, we isolated complementary DNA (cDNA) clones for equine J chain and polymeric Ig receptor (pIgR). When coexpressed with equine IgA, equine J chain promoted efficient IgA polymerization. A truncated version of equine pIgR, equivalent to secretory component, bound with nanomolar affinity to recombinant equine and human dimeric IgA but not with monomeric IgA from either species. Searches of the equine genome localized equine J chain and pIgR to chromosomes 3 and 5, respectively, with J chain and pIgR coding sequence distributed across 4 and 11 exons, respectively. Comparisons of transcriptional regulatory sequences suggest that horse and human pIgR expression is controlled through common regulatory mechanisms that are less conserved in rodents. These studies pave the way for full dissection of equine IgA function and open up possibilities for immune-based treatment of equine diseases

Modulation pharmacologique de la réponse au stress du réticulum endoplasmique

Un déséquilibre de l’homéostasie protéique provoqué par un stress externe ou interne dans le réticulum endoplasmique déclenche l’initiation des voies de signalisation des capteurs IRE1, PERK et ATF6 vers une réponse adaptative traductionnelle ou transcriptionnelle connue sous le nom de UPR (unfolded protein response). La double fonction de l’UPR peut, selon l’intensité et la durée du stress, conduire à l’adaptation ou à la mort de la cellule. Dans les cellules cancéreuses, les voies de l’UPR sont souvent altérées et conduisent généralement vers une adaptation à un environnement hostile. La contribution de ces voies à diverses conditions pathologiques explique l’essor des stratégies de recherche visant à découvrir et concevoir de nouvelles molécules capables de moduler le stress du réticulum endoplasmique dans un contexte physiopathologique

Resistance of Rhodococcus equi to acid pH

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Induction of vap genes encoded by the virulence plasmid of Rhodococcus equi during acid tolerance response

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Using alphascreen ® to identify small-molecule inhibitors targeting a conserved host–pathogen interaction

International audienceAlphaScreen ® is a technology particularly suitable for bi-molecular inhibitor screening assays, e.g. using protein–protein interactions with purifi ed recombinant proteins. Each binding partner of the bi-molecular interaction is coupled either to donor or to acceptor beads. The technology is based on the quantifi able transfer of oxygen singlets from donor to acceptor microbeads brought together by a specifi c interaction between the partners. We identifi ed the conserved interaction between WW domains of cellular ubiquitin ligases of the Nedd4 family and a short peptide motif (PPxY) present in several structural and nonstructural viral proteins as a potential drug target. Using an AlphaScreen assay recapitulating the interaction between Nedd4.2 and the PPxY motif of the adenoviral capsid protein VI, we screened a library of small molecules and identifi ed specifi c inhibitors of this interaction. © Springer Science+Business Media New York 2016

H(2)O(2), Which Causes Macrophage-Related Stress, Triggers Induction of Expression of Virulence-Associated Plasmid Determinants in Rhodococcus equi

The response of the intracellular pathogen Rhodococcus equi to H(2)O(2) treatment, a situation potentially encountered after the oxidative burst of alveolar macrophages, was analyzed. Compared to other bacteria, including Deinococcus radiodurans, R. equi showed exceptionally high resistance to this stress. A proteomic approach showed that four polypeptides present in the wild-type strain (85F) are missing in the plasmid-cured strain 85F(P-), and by using a DNA macroarray, we identified two plasmid-encoded vap genes, vapA and vapG, whose expression was highly induced by H(2)O(2) treatment. Whereas the transcript size of vapA was compatible with a monocistronic mRNA, the transcript of vapG was considerably longer. Rapid amplification of cDNA ends PCRs showed that the transcriptional start sites of the two operons were 69 and 269 nucleotides (nt) upstream of the start codon, respectively. Analysis of these leader sequences revealed the presence of a small open reading frame named podG, which encodes a sequence of 55 amino acids preceded by a putative ribosome binding site sequence in the vapG transcript. Taking this result into account, the untranslated leader of the podG/vapG operon is 87 nt. Alignment of this sequence with the leader sequences of vapA and vapD, genes previously shown to be induced by acid, revealed significant homologies. Since our results showed that vapA, vapD, and vapG are genes highly induced by macrophage-related stresses, their gene products may, within the Vap protein family, play a dominant role inside these phagocytic cells and may be the most promising candidates for vaccination strategies

Characterization of Mutations in the rpoB Gene Associated with Rifampin Resistance in Rhodococcus equi Isolated from Foals

Treatment with a combination of erythromycin and rifampin has considerably improved survival rates of foals and immunocompromised patients suffering from severe pneumonia caused by Rhodococcus equi. Frequently, because of monotherapy, emergence of rifampin-resistant strains has been responsible for treatment failure. Using consensus oligonucleotides, we have amplified and sequenced the rifampin resistance (Rif(r))-determining regions of 12 rifampin-resistant R. equi strains isolated from three foals and of mutants selected in vitro from R. equi ATCC 3701, a rifampin-susceptible strain. The deduced amino acid sequences compared to those of four rifampin-susceptible R. equi strains showed several types of mutations. In 3 of the 10 strains isolated from one foal, His526Asn (Escherichia coli numbering) and Asp516Val mutations were associated with low-level resistance (rifampin MIC, 2 to 8 μg/ml), whereas His526Asp conferred high-level resistance (rifampin MIC, 128 μg/ml) in the 7 remaining strains. In strains from the two other foals, His526Asp and Ser531Leu mutations were found to be associated with high-level and low-level resistance, respectively. The in vitro mutants, highly resistant to rifampin, harbored His526Tyr and His526Arg substitutions. As described in other bacterial genera, His526, Ser531, and Asp516 are critical residues for rifampin resistance in R. equi, and the resistance levels are dependent on both the location and the nature of the substitution