Bivalent Inhibitor of the N-end Rule Pathway

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. Ubr1p, the recognition (E3) component of the Saccharomyces cerevisiae N-end rule pathway, contains at least two substrate-binding sites. The type 1 site is specific for N-terminal basic residues Arg, Lys, and His. The type 2 site is specific for N-terminal bulky hydrophobic residues Phe, Leu, Trp, Tyr, and Ile. Previous work has shown that dipeptides bearing either type 1 or type 2 N-terminal residues act as weak but specific inhibitors of the N-end rule pathway. We took advantage of the two-site architecture of Ubr1p to explore the feasibility of bivalent N-end rule inhibitors, whose expected higher efficacy would result from higher affinity of the cooperative (bivalent) binding to Ubr1p. The inhibitor comprised mixed tetramers of beta-galactosidase that bore both N-terminal Arg (type 1 residue) and N-terminal Leu (type 2 residue) but that were resistant to proteolysis in vivo. Expression of these constructs in S. cerevisiae inhibited the N-end rule pathway much more strongly than the expression of otherwise identical beta-galactosidase tetramers whose N-terminal residues were exclusively Arg or exclusively Leu. In addition to demonstrating spatial proximity between the type 1 and type 2 substrate-binding sites of Ubr1p, these results provide a route to high affinity inhibitors of the N-end rule pathway

Trust protocol integrating services' semantics

International audienceIn high dynamic environments such as Internet or pervasive computing, different unknown services are provided. When two services communicate, they share properties to negotiate a provided service. By introducing trust, services rely on the identity of the participants, to evaluate a trust level and adapt this provided service. However, it is not always possible to verify identity. In this paper, we propose a service-to-service trust protocol based on services' description. By exchanging their descriptions, services build trust in each other and adapt the quality of the provided service through policies

Molecular and immunological evaluation of the expression of cancer/testis gene products in human colorectal cancer

Tumor-specific gene products, such as cancer/testis (CT) antigens, constitute promising targets for the development of T cell vaccines. Whereas CT antigens are frequently expressed in melanoma, their expression in colorectal cancers (CRC) remains poorly characterized. Here, we have studied the expression of the CT antigens MAGE-A3, MAGE-A4, MAGE-A10, NY-ESO-1 and SSX2 in CRC because of the presence of well-described HLA-A2-restricted epitopes in their sequences. Our analyses of 41 primary CRC and 14 metastatic liver lesions confirmed the low frequency of expression of these CT antigens. No increased expression frequencies were observed in metastatic tumors compared to primary tumors. Histological analyses of CRC samples revealed heterogeneous expression of individual CT antigens. Finally, evidence of a naturally acquired CT antigen-specific CD8+ T cell response could be demonstrated. These results show that the expression of CT antigens in a subset of CRC patients induces readily detectable T cell response

: Anticiper les évolutions pour les accompagner et les maîtriser

Cette recherche comprend quatre volets.Le premier présente le fonctionnement d’outils numériques existants d’analyse mathématique du droit. L’intelligence artificielle permet de modéliser certains aspects de l’activité juridique. En appliquant une méthodologie rigoureuse, on peut en particulier présenter l’éventail des décisions qui seraient prises par une juridiction donnée sur un dossier caractérisé par quelques dizaines de critères. Cette quantification fine de l’aléa judiciaire, qui va bien au-delà de simples statistiques, permet de comprendre et d’analyser les pratiques et, le cas échéant, de les faire évoluer.Le deuxième volet est consacré à l’encadrement juridique de ces Modes Algorithmiques d’Analyse des Décisions (MAAD).Leur domaine de compétence identifié - les contentieux juridiquement analogues – leur cadre juridique s’articule principalement autour de quatre points :- les réutilisations des données judiciaires- l’éthique avec un principe de transparence qui s’applique aux méthodes et aux résultats- les responsabilités que le fait générateur soit constitué par une faute présumée ou qu’il provienne de l’autonomie de l’algorithme- l’intégration des MAAD à des procédures dématérialisées de règlement judiciaire et extra-judiciaire des litigesDans le troisième volet, une enquête a été menée auprès des présidents des tribunaux de grande instance et des Cours d’appel de métropole et d’outre-mer ainsi que de la Cour de cassation dans l’objectif de connaître leur perception de ces outils, leurs attentes et leurs suggestions quant à leur emploi. Elle a permis de recueillir les avis de magistrats intéressés par ces outils. Les magistrats soulignent la nécessité de réguler leur conception et d’accompagner leurs usages.Le quatrième volet, sociologique, montre que les dynamiques internes au champ juridique, qui se traduisent par l’« appropriation des nouveaux outils par les acteurs du droit », seront déterminantes dans le processus de changement qui devrait se traduire par une montée en puissance des algorithmes au sein de l’institution qu’est la Justice Si d’importantes forces de changement sont déjà à l’œuvre, elles reposent sur la mobilisation d’acteurs aux caractéristiques spécifiques plutôt « subalternes » dans lechamp juridique voire, s’agissant des dirigeants de start up , clairement périphériques. Ces derniers apparaissent atypiques par l eur trajectoire, qu’elle soit professionnelle ou profane, et leur attitude réformatrice plus ou moins « radicale » relativement au monde du droit et de la justice

Immunogenicity of the carcinoembryonic antigen derived peptide 694 in HLA-A2 healthy donors and colorectal carcinoma patients

Carcinoembryonic antigen (CEACAM5) is commonly overexpressed in human colon cancer. Several antigenic peptides recognized by cytolytic CD8+ T-cells have been identified and used in colon cancer phase-I vaccination clinical trials. The HLA-A*0201-binding CEA694-702 peptide was recently isolated from acid eluted MHC-I associated peptides from a human colon tumor cell line. However, the immunogenicity of this peptide in humans remains unknown. We found that the peptide CEA694-702 binds weakly to HLA-A*0201 molecules and is ineffective at inducing specific CD8+ T-cell responses in healthy donors. Immunogenic-altered peptide ligands with increased affinity for HLA-A*0201 were identified. Importantly, the elicited cytolytic T lymphocyte (CTL) lines and clones cross-reacted with the wild-type CEA694-702 peptide. Tumor cells expressing CEA were recognized in a peptide and HLA-A*0201 restricted fashion, but high-CEA expression levels appear to be required for CTL recognition. Finally, CEA-specific T-cell precursors could be readily expanded by in vitro stimulation of peripheral blood mononuclear cell (PBMC) from colon cancer patients with altered CEA peptide. However, the CEA-specific CD8+ T-cell clones derived from cancer patients revealed low-functional avidity and impaired tumor-cell recognition. Together, using T-cells to demonstrate the processing and presentation of the peptide CEA694-702, we were able to corroborate its presentation by tumor cells. However, the low avidity of the specific CTLs generated from cancer patients as well as the high-antigen expression levels required for CTL recognition pose serious concerns for the use of CEA694-702 in cancer immunotherap

The Production of a New MAGE-3 Peptide Presented to Cytolytic T Lymphocytes by HLA-B40 Requires the Immunoproteasome

By stimulating human CD8+ T lymphocytes with autologous dendritic cells infected with an adenovirus encoding MAGE-3, we obtained a cytotoxic T lymphocyte (CTL) clone that recognized a new MAGE-3 antigenic peptide, AELVHFLLL, which is presented by HLA-B40. This peptide is also encoded by MAGE-12. The CTL clone recognized MAGE-3–expressing tumor cells only when they were first treated with IFN-γ. Since this treatment is known to induce the exchange of the three catalytic subunits of the proteasome to form the immunoproteasome, this result suggested that the processing of this MAGE-3 peptide required the immunoproteasome. Transfection experiments showed that the substitution of β5i (LMP7) for β5 is necessary and sufficient for producing the peptide, whereas a mutated form of β5i (LMP7) lacking the catalytically active site was ineffective. Mass spectrometric analyses of in vitro digestions of a long precursor peptide with either proteasome type showed that the immunoproteasome produced the antigenic peptide more efficiently, whereas the standard proteasome more efficiently introduced cleavages destroying the antigenic peptide. This is the first example of a tumor-specific antigen exclusively presented by tumor cells expressing the immunoproteasome

Optical 3D-storage in sol-gel materials with a reading by Optical Coherence Tomography-technique

We report on the recording of 3D optical memories in sol-gel materials by using a non-linear absorption effect. This effect induces a local change of the optical properties of the material which is read and quantified with a high resolution full-field Optical Coherence Tomography setup. It is the first time that this technique is used for this purpose. Data recording was performed by focused picosecond (ps) single-pulse irradiation at 1064 nm with energy densities of 10 and 33 J/cm2 per pulse.Comment: 19 pages, 7 figure