403 Specific targeting of cutaneous antigen-presenting cells by Chikungunya virus envelope protein E2

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Enzyme‐Cleavable Linkers for Protein Chemical Synthesis through Solid‐Phase Ligations

International audienceThe total synthesis of long proteins requires the assembly of multiple fragments through successive ligations. The need for intermediate purification steps is a strong limitation, particularly in terms of overall yield. One solution to this problem would be solid-supported chemical ligation (SPCL), for which a first peptide segment must be immobilized on a SPCL-compatible solid support through a linker that can be cleaved under very mild conditions to release the assembled protein. The cleavage of SPCL linkers has previously required chemical conditions sometimes incompatible with sensitive protein targets. Herein, we describe an alternative enzymatic approach to trigger cleavage under extremely mild and selective conditions. Optimization of the linker structure and use of a small enzyme able to diffuse into the solid support were key to the success of the strategy. We demonstrated its utility by the assembly of three peptide segments on the basis of native chemical ligation to afford a 15 kDa polypeptide

La kisspeptine : une nouvelle voie pour maitriser l’ovulation chez les petits ruminants ?

National audienceLa découverte de la kisspeptine (KP) à été une avancée majeur pour comprendre les mécanismes qui sous-tendent le contrôle central de la reproduction. Plusieurs formes de la KP (KP54, KP16, KP14, KP13 et KP10), toutes dérivées de la forme la plus longue (KP54) ont été détectées dans le cerveau et sont toutes capables d’activer le même récepteur (KISS1R), mais la forme la plus étudiées est la KP10 (H-YNWNSFGLRY-NH 2 ). Chez les mammifères l’injection périphérique de la KP10 induit une augmentation de la sécrétion de la GnRH (gonadotropin releasing hormone) suivie par une augmentation de la concentration plasmatique de la LH. Nous avons démontré qu’une infusion continue de la KP10 pendent l’anoestrus est capable de réactiver l’axe hypothalamo-hypophyse-gonade et d’induire une ovulation

Design and functional profiling of new KISS1R agonists

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Monitoring Human Neutrophil Activation by a Proteinase 3 Near-Infrared Fluorescence Substrate-Based Probe

International audienceA near-infrared fluorescent (NIRF) substrate-based probe (SBP) was conceived to monitor secreted human proteinase 3 (hPR3) activity. This probe, called pro3-SBP, is shaped by a fused peptide hairpin loop structure, which associates a hPR3 recognition domain (Val-Ala-Asp-Nva-Ala-Asp-Tyr-Gln, where Nva is norvaline) and an electrostatic zipper (consisting of complementary polyanionic (d-Glu)5 and polycationic (d-Arg)5 sequences) in close vicinity of the N- and C-terminal FRET couple (fluorescent donor, sulfoCy5.5; dark quencher, QSY21). Besides its subsequent stability, no intermolecular fluorescence quenching was detected following its complete hydrolysis by hPR3, advocating that pro3-SBP could further afford unbiased imaging. Pro3-SBP was specifically hydrolyzed by hPR3 (kcat/Km= 440 000 ± 5500 M–1·s–1) and displayed a sensitive detection threshold for hPR3 (subnanomolar concentration range), while neutrophil elastase showed a weaker potency. Conversely, pro3-SBP was not cleaved by cathepsin G. Pro3-SBP was successfully hydrolyzed by conditioned media of activated human neutrophils but not by quiescent neutrophils. Moreover, unlike unstimulated neutrophils, a strong NIRF signal was specifically detected by confocal microscopy following neutrophil ionomycin-induced degranulation. Fluorescence release was abolished in the presence of a selective hPR3 inhibitor, indicating that pro3-SBP is selectively cleaved by extracellular hPR3. Taken together, the present data support that pro3-SBP could be a convenient tool, allowing straightforward monitoring of human neutrophil activation