Étude comparative de combinaisons de peptides pour la livraison de protéines dans les cellules de mammifères

Authors: Lepetit-Stoffaes, Jean-Pascal
Advisor: Garnier, AlainGaillet, Bruno
Abstract: The expression of proteins in mammalian cells is still today mostly done by transfection of nucleic acids coding for the protein. An alternative, the direct delivery of proteins, has roused a growing interest for the past thirty years, since the discovery of peptide sequences with the capacity to penetrate the cells and destabilize the membranes. Thereby, strategies of protein delivery associating these peptides to the cargo protein differentiate from synthetic systems like cationic polymers and lipids. Among these peptides are found Cell Penetrating Peptides (CPP), which are able to bring a linked protein to the cell by endocytosis, but lack to cross the endosomal barrier. We also find peptides, which permit the endosomal escape of a cargo, the Endosomal Leakage Domains (ELD), in order to evade this bottleneck. This thesis is interested in the study of protein delivery, by means of the combination of CPP and ELD. An identified way of interest consists in co-incubating the mammalian cells with different combinations of a mix of these peptides with the protein to be delivered, without covalent link. Thereby, the CPP-ELDs permitted the delivery of the GFP fluorescent protein alone, as well as the GFP in fusion with a nuclear localization domain, which was found in the nuclei of several cellular types. In particular, the 6His-CM18-PTD4 peptide has been notably investigated for the delivery of various proteins. It enabled the delivery of the HoxB4 transcription factor, as well as the Cas9 and Cpf1 nucleases to realize their genome editing function. The properties and mechanisms of CPP-ELDs have been studied. Therefore, the endocytosis mechanism and the direct translocation to the cytoplasm have been identified and studied. The balance between these cellular pathways can vary depending on the nature of the CPP and the ELD, and on the delivery factors such as the peptide concentration. Overall, the delivery mechanisms have been studied by using GFP protein, and other fluorescent probes (calcein and FITC-Dextrans). The CPP-ELDs are able to deliver small size molecules (600 Da) to molecules with high molecular weight (250 kDa). The capacity to deliver big proteins has been confirmed by the cellular entry of the Cas9 and Cpf1 nucleases, but also with antibodies. The analysis of the biochemical properties and assumed secondary structures allowed identifying several criteria required for the efficient delivery in mammalian cells, for discovery and therapeutic applications.
Document Type: Thèse de doctorat
Issue Date: 2018
Open Access Date: 18 April 2019
Permalink: http://hdl.handle.net/20.500.11794/34493
Grantor: Université Laval
Collection:Thèses et mémoires

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