Muriel Amblard

MURIEL AMBLARD
Senior researcher, CNRS MONTPELLIER

Dr Muriel AMBLARD obtained her PhD in Organic Chemistry at the University of Montpellier under the supervision of Prof Jean Martinez in 1991. She joined the group of Dr Paul Anderson at Merck Sharp & Dohm in West point (Pennsylvania, USA) as a post-doctoral fellow. In 1996, she obtained a position at the Laboratory of Amino Acid Peptide and Protein in Montpellier as a CNRS researcher. She became a CNRS senior researcher and a team leader at the Institute of Biomolecules Max Mousseron in 2007. Her research interests are mainly at the interface of chemistry, biology and analysis. She developed a number of potent receptor agonists and antagonists of several peptide hormones. Related to medicinal chemistry programs, she developed new multifunctional scaffolds and focused on the design and synthesis of small molecules (diazepinones, spiroimidazolidinones, constraint dipeptide mimics) by combinatorial chemistry on solid support.

Her recent work focuses on the design and synthesis of constrained β-amino acid and dipeptide mimic oligomers as highly predictable and stable helical molecular architectures (Foldamers) applied to 1) the identification of cell penetrating compounds for the delivery of bioactive compounds inside the cells and 2) inhibitors of protein/protein interactions.

Another part of her research is devoted to the development of (1) new methodologies in peptide synthesis (the use of an O-N acyl transfer reaction for the synthesis of cyclic peptides without epimerization, new strategy for the synthesis of peptides alcohols on solid support, synthesis of stapled peptides ans peptide-polymers….) and (2) peptide-based biopolymers by new approaches relying on bottom up polymerisation of peptide-activated monomer.

Muriel is co-author of over 85 papers, 5 book chapters and 7 patents.

5 major publications :

Paramelle, G. Subra, L. Vezenkov, M. Maynadier, C. André, C. Enjalbal, M. Calmès, M. Garcia, J. Martinez, M. Amblard.A straightforward approach for cellular uptake quantification. Angew. Chem. Int. Ed. 201049, 8240-8243.

Legrand, C. André, E. Wenger, C. Didierjean, M C. Averlant-Petit, J. Martinez, M. Calmes, M. Amblard.Robust Helix Formation in a New Family of oligoureas based on a Constrained Bicyclic Building Block, Angew. Chem. Int. Ed., 2012, 51, 11267-11270

Legrand, C. André, L. Moulat, E. Wenger, C. Didierjean, E. Aubert, M C. Averlant-Petit, J. Martinez, M. Calmes, M. Amblard.Unprecedented Chain-Length Dependent Conformational Conversion Between 11/9 and 18/16 Helix inα/β-Hybrid Peptides. Angew. Chem. Int. Ed., 2014, 53, 13131-13135.

Martin, B. Legrand, L. L. Vezenkov, M. Berthet, G. Subra, M. Calmès, J.L. Bantignies, J. Martinez, M. Amblard. Turning peptide sequences into ribbon foldamers via a straightforward multi-cyclization reaction. Angew. Chem. Int. Ed., 2015, 54, 13966 –13970

Legrand, C. André, L. Moula, C. Didierjean, P. Hermet, J.L. Bantignies, J. Martinez, M. Amblard, M. Calmès, 12/14/14-Helix Formation in 2:1 α/β-Hybrid Peptides Containing Bicyclo[2.2.2]octane Ring Constraints, Chemistry: a European Journal, 2016, 22,11986 –11990

Contact:
muriel.amblard@umontpellier.fr
0033411759605

Inorganic Sol–Gel Polymerization for Hydrogel Bioprinting.

ACS Omega 2020, 5, 6, 2640-2647. doi: 10.1021/acsomega.9b03100.

Montheil T, Maumus M, Valot L, Lebrun A, Martinez J, Amblard M, Noël D, Mehdi A, Subra G.

 

 

Abstract

An inorganic sol–gel polymerization process was used as a cross-linking reaction during three-dimensional (3D) bioprinting of cell-containing hydrogel scaffolds. Hybrid hydroxypropyl methyl cellulose (HPMC), with a controlled ratio of silylation, was prepared and isolated as a 3D-network precursor. When dissolved in a biological buffer containing human mesenchymal stem cells, it yields a bioink that can be printed during polymerization by extrusion. It is worth noting that the sol–gel process proceeded at pH 7.4 using biocompatible mode of catalysis (NaF and glycine). The printing window was determined by rheology and viscosity measurements. The physicochemical properties of hydrogels were studied. Covalent functionalization of the network can be easily performed by adding a triethoxysilyl-containing molecule; a fluorescent hybrid molecule was used as a proof of concept.

Self-mineralization and assembly of a bis-silylated Phe–Phe pseudodipeptide to a structured bioorganic–inorganic material

Mater. Horiz., 2019, 6, 2040-2046   doi: 10.1039/C9MH00580C

Jebors S, Valot L, Echalier C, Legrand L, Mikhaleff R,Van Der Lee A, Arenal R, Dumy P, Amblard M, Martinez J, Mehdi A and Subra G.

Abstract

Self-mineralization of a trialkoxysilyl hybrid peptide yields in a single step a nanostructured hybrid material. A bis-silylated pseudodipeptide inspired from the Phe–Phe dipeptide was used to program the assembly by sol–gel polymerization under heterogeneous conditions, in water at pH 1.5 without any structure-directing agent. A mechanism deciphering the hybrid material assembly was proposed thanks to 1H NMR spectroscopy. First, water-insoluble hybrid building blocks were hydrolysed into their soluble silanol counterparts. Then, these transitional species, thanks to hydrogen bonding and π–π stacking, self-assembled in solution. Last, the proximity of the silanol moieties favoured their polycondensation into growing siloxane oligomers, which spontaneously precipitated to produce an ordered hybrid material.

Evolutionary Divergence of Enzymatic Mechanisms for Tubulin Detyrosination

Cell Rep. 2019 Dec 17;29(12):4159-4171.e6. doi: 10.1016/j.celrep.2019.11.074.

Van der Laan S, Lévêque MF, Marcellin G, Vezenkov L, Lannay Y, Dubra G, Bompard G, Ovejero S, Urbach S, Burgess A, Amblard M, Sterkers Y, Bastien P, Rogowski K.

Abstract

The two related members of the vasohibin family, VASH1 and VASH2, encode human tubulin detyrosinases. Here we demonstrate that, in contrast to VASH1, which requires binding of small vasohibin binding protein (SVBP), VASH2 has autonomous tubulin detyrosinating activity. Moreover, we demonstrate that SVBP acts as a bona fide activator of both enzymes. Phylogenetic analysis of the vasohibin family revealed that regulatory diversification of VASH-mediated tubulin detyrosination coincided with early vertebrate evolution. Thus, as a model organism for functional analysis, we used Trypanosoma brucei (Tb), an evolutionarily early-branched eukaryote that possesses a single VASH and encodes a terminal tyrosine on both α- and β-tubulin tails, both subject to removal. Remarkably, although detyrosination levels are high in the flagellum, TbVASH knockout parasites did not present any noticeable flagellar abnormalities. In contrast, we observed reduced proliferation associated with profound morphological and mitotic defects, underscoring the importance of tubulin detyrosination in cell division.

Stapled peptide targeting the CDK4/Cyclin D interface combined with Abemaciclib inhibits KRAS mutant lung cancer growth

Theranostics 2020; 10(5):2008-2028. doi:10.7150/thno.40971

Bouclier C*, Simon M*, Laconde G, Pellerano M, Diot S, Lantuejoul S, Busser B, Vanwonterghem L, Vollaire J, Josserand V, Legrand B, Coll JL, Amblard M, Hurbin A#, Morris MC#

* & # These authors contributed equally

Abstract

CDK4/cyclin D kinase constitutes an attractive pharmacological target for development of anticancer therapeutics, in particular in KRAS-mutant lung cancer patients, who have a poor prognosis and no targeted therapy available yet. Although several ATP-competitive inhibitors of CDK4 have been developed for anticancer therapeutics, they suffer from limited specificity and efficacy.

Methods: As an alternative to ATP-competitive inhibitors we have designed a stapled peptide to target the main interface between CDK4 and cyclin D, and have characterized its physico-chemical properties and affinity to bind cyclin D1.

Results: We have validated a positive correlation between CDK4/cyclin D level and KRAS mutation in lung cancer patients. The stapled peptide enters cells rapidly and efficiently, and inhibits CDK4 kinase activity and proliferation in lung cancer cells. Its intrapulmonary administration in mice enables its retention in orthotopic lung tumours and complete inhibition of their growth when co-administered with Abemaciclib.

Conclusion: The stapled peptide targeting the main interface between CDK4 and cyclin D provides promising therapeutic perspectives for patients with lung cancer.

Keywords: CDK4, Stapled Peptide, Inhibitor, Lung cancer (NSCLC), KRAS mutation

How are 1,2,3-triazoles accommodated in helical secondary structures?

Org Biomol Chem. 2018 May 15. doi: 10.1039/c8ob00686e

Ben Haj Salah K, Das S , Ruiz N , Andreu V , Martinez J , Wenger E , Amblard M , Didierjean C , Legrand B , Inguimbert N

Abstract

1,4-Disubstituted-1,2,3-triazole (Tz) is widely used in peptides as a trans-amide bond mimic, despite having hazardous effects on the native peptide activity. The impact of amide bond substitution by Tz on peptide secondary structures is scarcely documented. We performed a Tz scan, by systematically replacing peptide bonds following the Aib residues with Tz on two model peptaibols: alamethicin F50/5 and bergofungin D, which adopt stable α- and 310 helices, respectively. We observed that the Tz insertion, whatever its position in the peptide sequences, abolished their antimicrobial activity. The structural consequences of this insertion were further investigated using CD, NMR and X-ray diffraction. Importantly, five crystal structures that were incorporated with Tz were solved, showing various degrees of alteration of the helical structures, from minor structural perturbation of the helix to partial disorder. Together, these results showed that Tz insertions impair helical secondary structures.

12/10-Helix in Mixed β-Peptides Alternating Bicyclic and Acyclic β-Amino Acids: Probing the Relationship between Bicyclic Side Chain and Helix Stability

Chemistry. 2018 Dec 12. doi: 10.1002/chem.201804404. Epub 2018 Nov 15

Simon M, Milbeo P, Liu H, André C, Wenger E, Martinez J, Amblard M, Aubert E, Legrand B, Calmès M.

Abstract

12/10-Helices constitute suitable templates that can be used to design original structures. Nevertheless, they often suffer from a weak stability in polar solvents because they exhibit a mixed hydrogen-bond network resulting in a small macrodipole. In this work, stable and functionalizable 12/10-helices were developed by alternating a highly constrained β2, 3, 3 -trisubstituted bicyclic amino acid (S)-1-aminobicyclo[2.2.2]octane-2-carboxylic acid ((S)-ABOC) and an acyclic substituted β-homologated proteinogenic amino acid (l-β3 -hAA). Based on NMR spectroscopic analysis, it was shown that such mixed β-peptides display well-defined right-handed 12/10-helices in polar, apolar, and chaotropic solvents; that are, CD3 OH, CDCl3 , and [D6 ]DMSO, respectively. The stability of the hydrogen bonds forming the C10 and C12 pseudocycles as well as the benefit provided by the use of the constrained bicyclic ABOC versus typical acyclic β-amino acids sequences when designing 12/10-helix were investigated using NH/ND NMR exchange experiments and DFT calculations in various solvents. These studies showed that the β3 -hAA/(S)-ABOC helix displayed a more stable hydrogen-bond network through specific stabilization of the C10 pseudocycles involving the bridgehead NH of the ABOC bicyclic scaffold.

Site-specific grafting on titanium surfaces with hybrid temporin antibacterial peptides

J. Mater. Chem. B, 2018,6, 1782-1790. doi 10.1039/C8TB00051D

Abstract

Relying on a membrane-disturbing mechanism of action and not on any intracellular target, antimicrobial peptides (AMP) are attractive compounds to be grafted on the surface of implantable materials such as silicone catheters or titanium surgical implants. AMP sequences often display numerous reactive functions (e.g. amine, carboxylic acid) on their side chains and straightforward conjugation chemistries could lead to uncontrolled covalent grafting, random orientation, and non-homogenous density. To achieve an easy and site specific covalent attachment of unprotected peptides on titanium surfaces, we designed hybrid silylated biomolecules based on the temporin-SHa amphipathic helical antimicrobial sequence. With the grafting reaction being chemoselective, we designed five analogues displaying the silane anchoring function at the N-ter, C-ter or at different positions inside the sequence to get an accurate control of the orientation. Grafting density calculations were performed by XPS and the influence of the orientation of the peptide on the surface was clearly demonstrated by the measure of antimicrobial activity. Temporin amphipathic helices are described to permeabilize the bacterial membrane by interacting in a parallel orientation with it. Our results move in the direction of this mechanism as the selective grafting of hybrid temporin 2 through a lysine placed at the center of the peptide sequence, resulted in better biofilm growth inhibition of E. coli and S. epidermis than substrates in which temporins were grafted via their C- or N-terminus.

Ribbon-like Foldamers for Cellular Uptake and Drug Delivery

Chembiochem 2017 Nov 2;18(21):2110-2114. doi: 10.1002/cbic.201700455. Epub 2017 Sep 22.

Vezenkov LL, Martin V, Bettache N, Simon M, Messerschmitt A, Legrand B, Bantignies JL, Subra G, Maynadier M, Bellet V, Garcia M, Martinez J, Amblard M.

Abstract

Different intracellular delivery systems of bioactive compounds have been developed, including cell-penetrating peptides. Although usually nontoxic and biocompatible, these vectors share some of the general drawbacks of peptides, notably low bioavailability and susceptibility to protease degradation, that limit their use. Herein, the conversion of short peptide sequences into poly-α-amino-γ-lactam foldamers that adopt a ribbon-like structure is investigated. This template is used to distribute critical cationic and/or hydrophobic groups on both sides of the backbone, leading to potent short, cell-permeable foldamers with a low positive-charge content. The lead compound showed dramatically improved protease resistance and was able to efficiently deliver a biologically relevant cargo inside cells. This study provided a simple strategy to convert short peptide sequences into efficient protease-resistant cell-penetrating foldamers.

Structure-Activity Relationships of JMV4463, a Vectorized Cathepsin D Inhibitor with Antiproliferative Properties: The Unique Role of the AMPA-Based Vector

ChemMedChem, 2016, Volume: 11, Issue: 3, Pages: 302-308, DOI: 10.1002/cmdc.201500457

L. Vezenkov, C. A. Sanchez, V. Bellet, V. Martin, M. Maynadier, N. Bettache, V. Lisowski, J. Martinez, M. Garcia, M. Amblard, J. F. Hernandez

Abstract

Cathepsin D (CathD) is overexpressed and secreted by several solid tumors and stimulates their growth, the mechanism of which is still not understood.  In this context, the pepstatin bioconjugate JMV4463 [Ac-arg-O2Oc-(Val)3-Sta-Ala-Sta-(AMPA)4-NH2; O2Oc=8-amino-3,6-dioxaoctanoyl, Sta=statine, AMPA=ortho-aminomethylphenylacetyl], contg. a new kind of cell-penetrating vector, was previously shown to exhibit potent antiproliferative effects in vitro and to delay the onset of tumors in vivo.  In this study, the authors performed a structure-activity relationship anal. to evaluate the significance of the inhibitor and vector moieties of JMV4463.  By modifying both statine residues of pepstatin the authors found that the antiproliferative activity is correlated with CathD inhibition, supporting a major role of the catalytic activity of intracellular CathD in cancer cell proliferation.  Replacing the vector composed of four AMPA units with other vectors was found to abolish cytotoxicity, although all of the conjugates enabled pepstatin transport into cells.  In addn., the AMPA4 vector must be localized at the C terminus of the bioconjugate.  The unexpected importance of the vector structure and position for cytotoxic action suggests that AMPA4 enables pepstatin to inhibit the proteolysis of crit. CathD substrates involved in cell proliferation via a unique mechanism of action.

Unambiguous and Controlled One-Pot Synthesis of Multifunctional Silica Nanoparticles

Chemistry of Materials, 2016, Volume: 28, Issue: 3, Pages: 885-889, DOI: 10.1021/acs.chemmater.5b04398

J. Ciccione, T. Jia, J .L. Coll, K. Parra, M. Amblard, S. Jebors, J. Martinez, A. Mehdi, G. Subra 

Abstract

A method for obtaining in a single step well-defined tunable multifunctional fluorescent particles having their surface functionalized with multiple covalently linked ligands is reported.  The strategy relies on the synthesis of hybrid bioorg.-inorg. peptide ligands, greatly simplifying the design of multifunctional nanoparticles.  It was possible to tune the ratio of two grafted ligands on the surface of the SiNPs simply by adjusting the relative concn. of hybrid species in the starting soln.  An original fluorine NMR method was applied to the dissolved SiNPs to demonstrate our hypothesis.