Helical peptides from VEGF and Vammin hotspots for modulating the VEGF-VEGFR interaction

The design, synthesis, conformational studies and binding affinity for VEGF receptors of a collection of linear and cyclic peptide analogues of the N-terminal α-helix fragments 13-25 of VEGF and 1-13 of Vammin are described. Linear 13(14)-mer peptides were designed with the help of an AGADIR algorithm and prepared following peptide solid-phase synthetic protocols. Cyclic peptide derivatives were prepared on-resin from linear precursors with conveniently located Glu and Lys residues, by the formation of amide linkages. Conformational analysis, CD and NMR, showed that most synthesized peptides have a clear tendency to be structured as α-helices in solution. Some of the peptides were able to bind a VEGFR-1 receptor with moderate affinity. In addition to the described key residues (Phe17, Tyr21 and Tyr25), Val14 and Val20 seem to be relevant for affinity.Peer Reviewe

Biological Activities of Cyclic and Acyclic B-Type Laxaphycins in SH-SY5Y Human Neuroblastoma Cells

Laxaphycins are a family of non-ribosomal lipopeptides that have been isolated from several cyanobacteria. Some of these compounds have presented cytotoxic activities, but their mechanism of action is poorly understood. In this work, the already described laxaphycins B and B3, and acyclolaxaphycins B and B3 were isolated from the marine cyanobacteria Anabaena torulosa. Moreover, two new acyclic compounds, [des-(Ala4-Hle5)] acyclolaxaphycins B and B3, were purified from the herviborous gastropod Stylocheilus striatus, with this being the first description of biotransformed laxaphycins. The structure of these new compounds was elucidated, together with the absolute configuration of acyclolaxaphycins B and B3. The bioactivities of the six peptides were determined in SH-SY5Y human neuroblastoma cells. Laxaphycins B and B3 were cytotoxic (IC50: 1.8 and 0.8 µM, respectively) through the induction of apoptosis. In comparison, acyclic laxaphycins did not show cytotoxicity but affected mitochondrial functioning, so their effect on autophagy-related protein expression was analyzed, finding that acyclic peptides affected this process by increasing AMPK phosphorylation and inhibiting mTOR. This work confirms the pro-apoptotic properties of cyclic laxaphycins B and is the first report indicating the effects on autophagy of their acyclic analogs. Moreover, gastropod-derived compounds presented ring opening and amino-acids deletion, a biotransformation that had not been previously describedThe research leading to these results has received funding from the following FEDER cofunded-grants. From Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia, 2017 GRC GI-1682 (ED431C 2017/01). From CDTI and Technological Funds, supported by Ministerio de Economía, Industria y Competitividad, AGL2016-78728-R (AEI/FEDER, UE), ISCIII/PI16/01830 and RTC-2016-5507-2, ITC-20161072. From European Union POCTEP 0161-Nanoeaters -1-E-1, Interreg AlertoxNet EAPA-317-2016, Interreg Agritox EAPA-998-2018, and H2020 778069-EMERTOXS

20 000 molécules sous les mers et Invisible sous les toxines

International audienc

20 000 molécules sous les mers et Invisible sous les toxines

International audienc

S’adapter à un milieu toxique : l’exemple du lièvre de mer

International audienc

Conception et évaluation biologique d'antagonistes des récepteurs au VEGF à activité anti-angiogénique

L'angiogenèse est une étape nécessaire au développement des tumeurs. Elle est initiée par la libération de VEGF, facteur pro-angiogénique interagissant avec des récepteurs membranaires à activité tyrosine kinase. Dans le cadre de la thèse, nous avons développé des ligands antagonistes du domaine extracellulaire des récepteurs au VEGF. Nous avons ensuite mis au point un test de criblage chimioluminescent, permettant de tester rapidement plusieurs centaines de composés et, en se basant sur la structure RX du complexe VEGF/VEGFR-1, nous avons développé des antagonistes peptidiques des récepteurs au VEGF, mimes du VEGF. Un dérivé fluorescent a également été synthétisé à des fins d'imagerie. Un second axe des travaux a concerné la cyclisation des peptides au moyen de la chimie clic . Parallèlement, nous avons entrepris l'identification et l'optimisation de petites molécules antagonistes des VEGFR par un crible in silico. Enfin, la synthèse chimique du domaine VEGFR1 d2 a été réalisée.Angiogenesis is the formation of blood vessels from a pre-existing vasculature. Its dysregulation is implicated in cancer. It is commonly admitted that the VEGF is the most potent proangiogenic factor. VEGF activity is triggered by its binding to tyrosine kinase receptors located at the surface of endothelial cells. We searched to develop ligands of the extracellular domain of VEGF receptors, with antagonist activities. First, a competition assay based on chimioluminescence was set up. Then we rationally designed peptide antagonists of the VEGFR, mimicking the structure of the VEGF. A fluorescent peptide has also been synthesized for imaging purposes and we describe the solid phase cychzation of peptides by the Cu(I)-catalyzed Huisgen cycloaddition. A second approach consisted in performing the in silico screening of a small molecule library A few hits were identified and their optimization was undertaken. Finally, the VEGF binding domain of VEGF receptors has been produced by SPPS.PARIS-BIUP (751062107) / SudocSudocFranceF