Gilles Subra

Gilles Subra

Gilles Subra
Professor, Faculty of Pharmacy of Montpellier

Gilles leads his researches in the Institute of Biomolécules Max Mousseron (IBMM) in the field of peptide science. His main research topics are at the interface of chemistry and biology and notably concern methodologies for solid phase and combinatorial chemistry, design of chemical tools to enhance detection and quantification by mass spectrometry in biological media. More recently, he is interested in the design of peptide-based materials and polymers. The main applications concern the conception of multi-ligand nanoparticles for cancer targeting, the functionalisation of silicone medical devices and dressings. His most recent research is related to the design of biomimetic peptide based hydrogel used for 3D biofabrication and cell-based therapies.

Gilles Subra founded the solid phase and automated synthesis platform (SynBio3) of the IBMM whose mission is to develop solid supported reagents, linkers and methodologies for the synthesis of biomolecules.

Contact:
gilles.subra@umontpellier.fr
+33 411 75 96 06

5 major publications :

Ciccione, J., Jia, T., Coll, J.-L., Parra, K., Amblard, M., Jebors, S., Martinez, J., Mehdi, A., and Subra, G. (2016). Unambiguous and Controlled One-Pot Synthesis of Multifunctional Silica Nanoparticles. Chem. Mater. 28, 885–889.

Echalier, C., Pinese, C., Garric, X., Van Den Berghe, H., Jumas Bilak, E., Martinez, J., Mehdi, A., and Subra, G. (2016). Easy Synthesis of Tunable Hybrid Bioactive Hydrogels. Chem. Mater. 28, 1261–1265.

Jebors, S., Ciccione, J., Al-Halifa, S., Nottelet, B., Enjalbal, C., M’Kadmi, C., Amblard, M., Mehdi, A., Martinez, J., and Subra, G. (2015). A New Way to Silicone-Based Peptide Polymers. Angew. Chem. Int. Ed. 54, 3778–3782.

Paramelle, D., Subra, G., Vezenkov, L.L., Maynadier, M., André, C., Enjalbal, C., Calmès, M., Garcia, M., Martinez, J., and Amblard, M. (2010). A Straightforward Approach for Cellular-Uptake Quantification. Angewandte Chemie International Edition 49, 8240–8243.

Paramelle, D., Enjalbal, C., Amblard, M., Forest, E., Heymann, M., Cantel, S., Geourjon, C., Martinez, J., and Subra, G. (2011). Solid-Phase Cross-Linking (SPCL): A new tool for protein structure studies. PROTEOMICS 11, 1277–1286.

Turning peptides into bioactive nylons

European Polymer Journal 2020. doi: 10.1016/j.eurpolymj.2020.109886

Said Jebors, Coline Pinese, Titouan Montheil, Audrey Bethry, Simon Verquin, Louise Plais, Marie Moulin, Chloé Dupont, Xavier Garric, Ahmad Mehdi, Jean Martineza and Gilles Subra.

 

 

Abstract

New synthetic textiles with physical and/or biological properties are increasingly used in medical applications.While a simple textile coating is usually carried out to obtain biological properties, covalent grafting should be considered for long-term applications. Herein, we have developed a new hybrid bioactive nylon whose synthesis involves a peptide sequence with a diacyl derivative. Numerous types of peptide-nylons were prepared by varying the molar percentage (0.1 %, 1 % and 10%) and orientation of the peptide in the polymer backbone. Nylons incorporating antibacterial peptides significantly inhibited S. aureus proliferation whereas nylons functionalized with cell-adhesive peptide enhanced the proliferation of L929 fibroblast. These results show that the incorporation of the peptides directly into the nylon skeleton is efficient and provides biological properties that suggest new ways of functionalizing biomedical textiles

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.

Biocompatible Glycine-Assisted Catalysis of the Sol-Gel Process: Development of Cell-Embedded Hydrogels.

Chempluschem. 2019 Nov;84(11):1720-1729. doi: 10.1002/cplu.201900509.

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

 

Abstract

The sol‐gel process can be used for hydrogel cross‐linking, thus opening an attractive route for the design of biocompatible hydrogels under soft conditions. The sol‐gel process can be catalysed at basic or acidic pH values, under neutral conditions with the addition of a nucleophile. Therefore, working around pH 7 unlocks the possibility of direct cell embedment and the preparation of bioinks. We aimed to propose a generic method for sol‐gel 3D bioprinting, and first screened different nucleophilic catalysts using bis‐silylated polyethylene glycol (PEG) as a model hydrogel. A synergistic effect of glycine and NaF, used in low concentrations to avoid any toxicity, was observed. Biocompatibility of the approach was demonstrated by embedding primary mouse mesenchymal stem cells. The measure of viscosity as a function of time showed the impact of reaction parameters, such as temperature, complexity of the medium, pH and cell addition, on the kinetics of the sol‐gel process, and allowed prediction of the gelation time.

Chemical cross-linking methods for cell encapsulation in hydrogels

Mater Today Comm., 2019, 20, 100536. doi: 10.1016/j.mtcomm.2019.05.012

Echalier C, Valot L, Martinez J, Mehdi A and Subra G.

 

Abstract

Cell-encapsulating hydrogels are of tremendous interest in regenerative medicine. Tissue engineering relies on biomaterials able to act as artificial extracellular matrices to guide cells towards the development of new tissues. Therefore, considerable efforts have been made to design biomaterials which mimic cells’ native environment, thus encouraging natural behavior. The choice of biomaterial in which cells are embedded is crucial for their survival, proliferation and differentiation. Being more stable, chemical hydrogels are preferred over physical hydrogels as cell-laden substrates. When designing chemical hydrogels, scientists must choose not only the nature of the network (synthetic and/or bio-polymers) but also the type of cross-link bridging hydrogel constituents. For that purpose, numerous chemistries have been used (i) to introduce reactive functions on the hydrogel precursors and (ii) to form covalent bonds in the presence of living cells. The review will discuss the advantages and limitations of each strategy.

Chemical insights into bioinks for 3D printing

Chem. Soc. Rev., 2019, 48, 15, 4049-4086   doi: 10.1039/C7CS00718C

Valot L, Martinez J, Mehdi A and Subra G.

 

Abstract

3D printing has triggered the acceleration of numerous research areas in health sciences, which traditionally used cells as starting materials, in particular tissue engineering, regenerative medicine and also in the design of more relevant bioassays for drug discovery and development. While cells can be successfully printed in 2D layers without the help of any supporting biomaterial, the obtainment of more complex 3D architectures requires a specific bioink, i.e. a material in which the cells are embedded during and after the printing process helping to support them while they are arranged in superimposed layers. The bioink plays a critical role in bioprinting: first, it must be adapted to the 3D printing technology; then, it must fulfil the physicochemical and mechanical characteristics of the target construct (e.g. stiffness, elasticity, robustness, transparency); finally it should guarantee cell viability and eventually induce a desired behaviour. This review focuses on the nature of bioink components of natural or synthetic origin, and highlights the chemistry required for the establishment of the 3D network in conditions compatible with the selected 3D printing technique and cell survival.

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.

Synthesis of Peptide–Adenine Conjugates as a New Tool for Monitoring Protease Activity

Eur. J. Org. Chem. January 2019: 176-183. doi:10.1002/ejoc.201801490.

Masurier, N. , Soualmia, F. , Sanchez, P. , Lefort, V. , Roué, M. , Maillard, L. T., Subra, G. , Percot, A. and El Amri, C.

Abstract

We took advantage of the powerful adenine SERS (Surface Enhanced Raman Spectroscopy) probe to design peptide–adenine conjugates as candidates for use as serine protease substrates. Whereas the direct introduction of the peptide sequence on the adenine exocyclic N6 amine gave an imidazopurinone derivative, the introduction of an aminoethyl linker between the adenine group and the peptide chain led to the expected candidate probes. These potential substrates were then evaluated for monitoring the hydrolytic activity of trypsin, used as a model protease, by HPLC and by SERS. We demonstrated that the Boc–VPR–adenine conjugate is a substrate of trypsin and constitutes a good starting point to design optimized substrates to monitor protease activity by SERS.

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.

Inorganic polymerization: an attractive route to biocompatible hybrid hydrogels

J. Mater. Chem. B, 2018,6, 3434-3448,  doi 10.1039/C8TB00456K

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Abstract

As an intermediate state between liquid and solid materials, hydrogels display unique properties, opening a wide scope of applications, especially in the biomedical field. Organic hydrogels are composed of an organic network cross-linked via chemical or physical reticulation nodes. In contrast, hybrid hydrogels are defined by the coexistence of organic and inorganic moieties in water. Inorganic polymerization, i.e. the sol–gel process, is one of the main techniques leading to hybrid hydrogels. The chemoselectivity of this method proceeds through hydrolysis and condensation reactions of metal oxide moieties. In addition, the mild reaction conditions make this process very promising for the preparation of water-containing materials and their bio-applications.

Heteromultivalent targeting of integrin αvβ3 and neuropilin 1 promotes cell survival via the activation of the IGF-1/insulin receptors

Biomaterials 2018 Feb;155:64-79. doi: 10.1016/j.biomaterials.2017.10.042. Epub 2017 Oct 29.

Jia T, Choi J, Ciccione J, Henry M, Mehdi A, Martinez J, Eymin B, Subra G, Coll JL.

Abstract

Angiogenesis strongly depends on the activation of integrins, especially integrin αvβ3, and of neuropilin-1 (NRP-1), a co-receptor of VEGFR2. Dual-targeted molecules that simultaneously block both of them are expected have increased anti-angiogenic and antitumor activity. Toward this goal, we generated bifunctional 40 nm-sized silica nanoparticles (NPs) coated with controlled amounts of cRGD and ATWLPPR peptides and studied their affinity, selectivity and biological activity in HUVECs. Sub-nanomolar concentrations of NPs grafted either with ATWLPPR alone or in combination with cRGD exhibit potent and specific antagonist activity against VEGFR2/AKT signaling. However, a 1 nM concentration of the cRGD/ATWLPPR-heteromultivalent particles (RGD/ATW-NPs) also blocks the phosphorylation of VEGFR2 while co-inducing an unexpected long-lasting activation of AKT via IGF-1R/IR-AKT/GSK3β/eNOS signaling that stimulates cell survival and abrogates the intrinsic toxicity of silica-NPs to serum-starved HUVECs. We also showed that their repeated intravenous administration was associated with the proliferation of human U87MG tumor cells engrafted in nude mice and a dilatation of the tumor blood vessels. We present biochemical evidence for the complex cross-talk generated by the binding of the heteromultivalent NPs with αvβ3-integrin and with NRP1. In particular, we show for the first time that such heteromultivalent NPs can trans-activate IGF-1/insulin receptors and exert dose-dependent pro-survival activity. This study demonstrates the difficulties in designing targeted silica-based NPs for antiangiogenic therapies and the possible risks posed by undesirable side effects.