Chemistry-Driven Polybodies : Toward Modular Conception of Nanotherapeutics – POLYTHER

Nowadays, engineered biomolecules are often used in different therapeutic strategies. The goal of this project is to develop a new type of targeting ligands. Specifically, we aim to develop therapeutic polybodies (PB), i.e. multivalent macromolecules composed of small specific bodies (peptides, affibodies (AfB), nanobodies (NB)) anchored on a smart molecular platform in a radial configuration. The controlled architecture of PB will allow optimal multivalent interactions of ligands with receptors. PB offer several advantages over existing strategies: PB modular design can mix both synthetic and bio produced building blocks, PB can control multivalent ligand symmetry, PB contain a fluorophore unit for reliable detection without the need for additional steps. PB are conceived for interacting with two important families of cell surface proteins to prove their efficiency G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) which we know well. These poly-AfB and poly-NB are designed as versatile homo- or heterotopic constructs, where we aim to optimize their molecular scaffold, in particular the length and flexibility of the synthetic linker between bodies for bivalent interactions on the same cell (cis binding), and for intercellular binding to connect different cells (trans binding). Our project is based on our previous work and expertise on AfB design, peptide synthesis and, knowledge of GPCRs and RTKs. We will provide detailed architecture-activity relationships. Indeed, the binding affinities of PBs to related free receptors as well as binding kinetics (kON, kOFF) will be evaluated with several complementary biophysical tools (FIDA, BLI, switchSense, and MST). In parallel, the binding of PBs to living cells expressing GPCRs and RTKs receptors will be carried out with cytometry or RT-IC to get a reliable picture of interactions in real conditions. This will be completed by a functional evaluation in cellular models to confirm signal transduction after cell receptor engagement. Finally, the obtained data will be rationalized with respect to the PB structures in order to predict the best topologies for innovative nanotherapeutics implying our receptors, but easily extendable to other targets (e.g. infectious diseases).