9 research outputs found
Improvement of recombinant antibodies production in the diatom Phaeodactylum tricornutum
Le marchĂ© des anticorps monoclonaux (mAbs) est en plein essor en raison de leur utilisation dans le traitement de nombreuses maladies chroniques et inflammatoires. Cependant, les systĂšmes de production utilisĂ©s prĂ©sentent des inconvĂ©nients qui incitent la communautĂ© scientifique Ă se tourner vers de nouvelles alternatives telles que les microalgues. Des Ă©tudes rĂ©centes ont dĂ©montrĂ© la capacitĂ© de la diatomĂ©e P. tricornutum Ă produire des mAbs fonctionnels dirigĂ©s contre certains virus, mais les rendements de production obtenus sont trop faibles pour prĂ©tendre Ă un passage Ă lâĂ©chelle industrielle. Afin dâĂ©tendre la preuve de concept de la production de mAbs chez la diatomĂ©e P. tricornutum, nous avons focalisĂ© nos travaux sur la production dâun anticorps anti-HER2 en utilisant un nouveau design de vecteur. Malheureusement, un problĂšme de contamination dĂ©tectĂ© en fin de thĂšse ne nous permet pas aujourdâhui de conclure dĂ©finitivement sur lâefficacitĂ© de ces vecteurs pour la production de mAbs anticancĂ©reux fonctionnels chez P. tricornutum. La deuxiĂšme partie de ce travail sâest concentrĂ©e sur le dĂ©veloppement de diffĂ©rentes approches afin dâaugmenter le rendement de production de mAbs chez cette diatomĂ©e. Nous avons dâabord caractĂ©risĂ© de nouveaux promoteurs de gĂšnes exprimĂ©s dans des conditions de faible salinitĂ© en se basant sur des donnĂ©es de transcriptomiques prĂ©cĂ©demment publiĂ©es par le laboratoire. Sur les 28 promoteurs testĂ©s, nous avons montrĂ© que 13 dâentre eux Ă©taient capables de conduire Ă lâexpression de la protĂ©ine rapportrice eGFP. Parmi eux, nous avons dĂ©montrĂ© que le promoteur VOC est une alternative prometteuse au promoteur NR, utilisĂ© jusquâĂ prĂ©sent pour la production de mAbs chez P. tricornutum. En parallĂšle, nous avons identifiĂ© des Ă©lĂ©ments spĂ©cifiques du vecteur dâexpression permettant une augmentation du rendement de sĂ©crĂ©tion des mAbs dans le milieu de culture de la diatomĂ©e. Nous avons mis en Ă©vidence que lâutilisation du terminateur du gĂšne fcpA Ă©tait plus efficace pour augmenter le rendement de production comparativement aux terminateurs endogĂšnes associĂ©s aux promoteurs testĂ©s. De plus, nous avons montrĂ© que lâutilisation de peptides signaux hĂ©tĂ©rologues augmentait de façon surprenante la sĂ©crĂ©tion des mAbs dans le milieu de culture par rapport au peptide signal de la protĂ©ine endogĂšne HASP1, la protĂ©ine la plus abondamment sĂ©crĂ©tĂ©e par la diatomĂ©e. Dans l'ensemble, ces rĂ©sultats contribuent Ă la dĂ©couverte de nouveaux outils gĂ©nĂ©tiques et d'Ă©lĂ©ments du vecteur dâexpression qui permettent d'augmenter la quantitĂ© de mAbs sĂ©crĂ©tĂ©s et accumulĂ©s dans le milieu de culture de P. tricornutum.The market share of monoclonal antibodies (mAbs) is expanded rapidly due to their increasing use in the treatment of many chronic and inflammatory diseases. However, the current production systems present several drawbacks that are prompting the scientific community to explore new alternatives such as microalgae. Recent studies have shown the ability of the diatom P. tricornutum to produce functional mAbs directed against viruses, but the production yields are too low for the production at an industrial scale. In order to extend the proof of concept, we attempted to produce an anti-Her2 antibody in P. tricornutum using a new vector design. Unfortunately, a contamination problem detected at the end of the thesis does not allow us to definitively conclude on the efficacy of these vectors for the production of functional anti-cancer mAbs in P. tricornutum. The second part of this work focused on the development of different approaches to increase the mAbs production yield in this diatom. We first characterised new promoters of genes overexpressed under low salinity conditions based on transcriptomic data previously published by the laboratory. Of the 28 promoters tested, we showed that 13 of them were capable of driving the expression of the eGFP reporter protein. Among them, we demonstrated that the VOC promoter is a promising alternative to the NR promoter used until now for the production of mAbs in P. tricornutum. In parallel, we identified specific elements of the expression vector that allow an increase in the secretion yield of mAbs in the diatom culture medium. We also demonstrated that the use of the fcpA gene terminator was more effective in increasing the production yield compared to the endogenous terminators associated with the tested promoters. Furthermore, we showed that the use of heterologous signal peptides surprisingly increased the secretion of mAbs into the culture medium compared to the signal peptide of HASP1, the most abundant secreted endogenous protein. Overall, these results contribute to the discovery of new genetic tools and vector elements that allow to increase the amount of mAbs secreted and accumulated in P. tricornutum culture medium
Transcriptomic analyses unravel differential expression of genes involved in the N-glycosylation pathway of Phaeodactylum tricornutum ecotypes
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Adaptation de bactéries entériques pathogÚnes et/ou antibiorésistantes sur des feuilles de salade
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Adaptation de bactéries entériques pathogÚnes et/ou antibiorésistantes sur des feuilles de salade
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Adaptation of enteric pathogenic bacteria on salad leaves and involvement of conjugative multiple-antibiotic resistance plasmids
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Adaptation of enteric pathogenic bacteria on salad leaves and involvement of conjugative multiple-antibiotic resistance plasmids
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Improvement of monoclonal antibodies production in the diatom using new promoters
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Towards understanding the extensive diversity of protein Nâglycan structures in eukaryotes
International audienceN-glycosylation is an important post-translational modification of proteins that has been highly conserved during evolution and is found in Eukaryota, Bacteria and Archaea. In eukaryotes, N-glycan processing is sequential, involving multiple specific steps within the secretory pathway as proteins travel through the endoplasmic reticulum and the Golgi apparatus. In this review, we first summarize the different steps of the N-glycan processing and further describe recent findings regarding the diversity of N-glycan structures in eukaryotic clades. This comparison allows us to explore the different regulation mechanisms of N-glycan processing among eukaryotic clades. Recent findings regarding the regulation of protein N-glycosylation are highlighted, especially the regulation of the biosynthesis of complex-type N-glycans through manganese and calcium homeostasis and the specific role of transmembrane protein 165 (TMEM165) for which homologous sequences have been identified in several eukaryotic clades. Further research will be required to characterize the function of TMEM165 homologous sequences in different eukaryotic clades