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Academic literature on the topic 'Vésicules (cytologie)'
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Dissertations / Theses on the topic "Vésicules (cytologie)"
Le, Riche Alizée. "Etude fonctionnelle de vésicules extracellulaires sur la physiologie de la papille dermique." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC335.
Full textDermal papilla (DP) displays a pivotal role in hair follicle (HF) morphogenesis andcycling through epithelial-mesenchymal interactions. Some factors are crucial in HF development like β-catenin and bone morphogenetic protein (BMP) pathways or also growth factors such as fibroblast growth factors (FGF) or platelet derived growth factor (PDGF). Intact DP can be engrafted with epidermal cells to reconstitute hair follicle (HF) on mice. However, DP cells (DPC) gradually lost their regenerative capacity after being passaged except if they are cultivated as spheres. This micro-environmental reprogramming partially restores the inductive ability of DPCto make HF. Our objective is to study the dialogue between HF and its macro-environment through secretion of extracellular vesicles (EVs) and their potential to activate DPC and stimulate HFgrowth. To recapitulate DPC activation in vitro, human dermal fibroblasts were stimulated by both bFGF and PDGF-AA and secreted EVs were purified (2GF-EVs). Remarkably, 2GF-EVs enhance the growth of HF cultivated ex-vivo as compared with no treated or treated with ctrl-EVs. Moreover, 2GF-EVs modulate genes whose expression was restored by sphere formation, including Norrin (NDP). The increase of Norrin secretion, an agonist of the wnt/β-catenin pathway, by DPC apparently activated this pathway in HF keratinocytes whereas the soluble growth factors did not. In conclusion, EVs could be a modulator of DPC activation and a valuable tool to maintain and restore, via the protein Norrin, DPC inductive ability and HF cycling
Reynaud, Antoine. "Mécanismes de capture des nanovésicules intracellulaires par Tumor Protein D54." Electronic Thesis or Diss., Université Côte d'Azur, 2023. http://theses.univ-cotedazur.fr/2023COAZ6005.
Full textTumor Protein D54 belongs to a family of 4 proteins, TPD52, 53, 54 and 55, whose role and functions remain unknown. However, these proteins are overexpressed in many cancers including breast carcinoma, prostate, lung and ovarian cancers, hence the importance of discovering their functions and mechanisms of action.Under physiological conditions, TPD54, which is a very abundant protein in many cells, appears cytoplasmic with a perinuclear accumulation near the Golgi apparatus. It has recently been shown that this protein is associated with transport nanovesicles 30 nm in diameter in the cytoplasm (Larocque et al., 2019). This size of vesicles is smaller than those already known from the COPI, COPII and Clathrin coats (50-100nm). The very small size of these vesicles, as well as the specificity of the binding to TPD54, prompted us to study the binding mechanism and more generally the properties of this protein.First, we have elucidated the mechanism by which TPD54 binds intracellular nanovesicles, using biochemical (protein purification, flotation, limited proteolysis), biophysical (circular dichroism, spectroflurimetry) and cell biology (FRAP, STED) approaches. TPD54 binds to lipid membranes in a curvature-dependent manner through an extended amphipathic region including an ALPS Amphipathic Lipid Packing Sensor motif, a universal motif for detecting membrane curvature that was discovered in the laboratory in 2007. This amphipathic region accompanied by its ALPS region is necessary and sufficient for binding to intracellular nanovesicles and hence for the subcellular distribution of TPD54 (Reynaud et al., 2022).Second, we show by electron and optical microscopy that intracellular overexpression of TPD54 leads to the formation of biocondensates including TPD54, nanovesicles as well as lipid droplets. We have reconstituted this process using purified elements. TPD54 can segregate in liquid phases through an antiparallel coiled-coil dimerization domain and its unstructured regions, encompassing the extended amphipathic region and ALPS region, which drive the recruitment of nanovesicles and lipid droplets. We highlight the regions necessary for the different phenotypes of TPD54 as well as a probable site of regulation by phosphorylation, which inhibits the assembly of nanovesicles by phase separation. Physiological implications of this mechanisms are several fold, ranging from vesicular transport, through the intracellular proximity to multiple Rabs and more particularly Rab11a, a small G protein involved in recycling, or its localization with lysosome markers, to autophagy with the proximity of TPD54 to ATG9. This protein is involved in the initialization and formation of the autophagosome and the liquid phase phenotype during nutrient stress could help the dynamic storage of phospholipids.The function of the bio-condensates controlled by TPD54, an abundant protein, both present in the Golgi, diffused in the cytoplasm, and found overexpressed in cancers, remains to be discovered. The formation of liquid phases is an increasingly important phenomenon in cell biology but is quite rare in the case of liquid phases trapping transport vesicles
Ghigliotti, Giovanni. "Dynamique et rhéologie d'une suspension de vésicules et globules rouges." Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENY071.
Full textThe dynamics and the rheology of a suspension of vesicles (a model for red blood cells) in the limit of small Reynolds number are studied by means of two-dimensional numerical simulations, based on the boundary integral and phase field methods. The focus is on the link between the microscopic dynamics of the particles and the overall behavior of the suspension (i. E. Rheology). A dilute suspension of vesicles in a linear shear flow is analyzed in detail and the influence of the three parameters governing the dynamics of a single vesicle (reduced volume; viscosity contrast; capillary number) is extensively described. The nontrivial behavior of the rheological quantities (effective viscosity and normal stress difference) is explained and the role of the membrane of the vesicle detailed. The influence of the curvature of the flow lines on the dynamics of the vesicles is investigated for the first time, and consistent inward migration is reported. The suggested interpretation remains valid for the flow of the majority of complex fluids, like emulsions and polymer suspensions, and is thus expected to have an impact in other fields. Moreover, the behavior of a suspension of vesicles in a microscopic Taylor-Couette cell is investigated, and a transition to ordered states is reported at very low volume fraction. The behavior of sets of vesicles in a parabolic flow, a setup that mimics red blood cells in the microvasculature, is presented. Vesicles submitted to sole hydrodynamical interactions are found to form aggregates of finite size, a fact that may prove of physiological interest. Finally, the transposition to red blood cells of the results above is discussed
Wan, Bin. "Interactions Drosophiles-guêpes endoparasitoïdes : rôle des vésicules extracellulaires du venin de Leptopilina boulardi dans le transport de facteurs de virulence et la spécificité d’hôte." Electronic Thesis or Diss., Université Côte d'Azur (ComUE), 2017. http://theses.univ-cotedazur.fr/2017AZUR4143.
Full textEndoparasitoid wasps, such as Leptopilina boulardi (Figitidae), develop inside Drosophila host larvae, mainly D. melanogaster. Egg oviposition normally results in a capsule formation by specialized haemocytes, the lamellocytes, associated with a melanization reaction. The parasitic success of L. boulardi relies on injection with the egg of venom that blocks the action of lamellocytes. This venom, synthesized at the level of a specialized gland and stored in a reservoir, contains protein components and original vesicles (venosomes). I have shown that two described virulence factors, LbGAP and LbGAP2 (VFs), are embedded in venosomes during their assembly which seems to occur extracellularly in the duct connecting the venom gland to the reservoir. Microinjection of purified venosomes protects the egg from encapsulation like venom injection. Fluorescently labelled venosomes and VFs co-immunolocalize in lamellocytes after injection and their internalization involves a flotillin/raft-domain-dependent endocytosis. The venosomes internalization rate differs significantly between the Drosophila host species tested (D. melanogaster>D. simulans>D. yakuba>D. suzukii) and is correlated with the parasite success rate, suggesting the existence of specific receptor on lamellocytes of D. melanogaster. Using the HopTum-1 mutant that constitutively produces lamellocytes, I have purified these cells and performed proteomic analysis of their membrane to identify candidate receptors. My results demonstrate that venosomes are interspecies transport vehicles involved in parasite virulence that represent a new level of host specificity
Youssefian, Tayebeh. "Trafic intracellulaire dans la lignée mégacaryocyto-plaquettaire : biogenèse des granules denses et interaction avec le virus de l'immunodéficience humaine." Paris 11, 2000. http://www.theses.fr/2000PA11T041.
Full textAlmairac, Fabien. "Plasticité des cellules tumorales de glioblastomes : inter-conversion d’un phénotype différencié et souche en fonction du microenvironnement." Electronic Thesis or Diss., Nice, 2016. http://theses.unice.fr/2016NICE4045.
Full textThere is great interest but little understanding in how cancer stem cells arise. Here we show that tumor cells exhibiting stem-like properties and expression of stemness(CD133) and pluripotency markers (SOX2, NANOG, OCT4), can arise from differentiated tumor cells that are isolated from human glioblastomas. These cells could transit from a more differentiated state that cannot self-renew to a self-renewing stem-like state upon EGF/EGFR signaling. This dedifferentiation process induced expression of pluripotency markers, and restored clonal and tumorigenic properties as well as resistance to temozolomide, the chemotherapy of reference. EGF/EGFR signaling including ERK activation was crucial for this cellular reprogramming. Interestingly, expression of pluripotency markers occurred before the cells re-entered the cell cycle, demonstrating that the cells have the capacity to change and reprogram before the cell division starts. Our findings support a model of tumor homeostasis in which tumor cells driven by environmental cues such as EGF, can spontaneously acquire stem-like properties contributing thus to the enrichment in tumor propagating cells
Souibgui, Eytham. "Rôle de la clathrine dans le processus infectieux du champignon phytopathogène Botrytis cinerea." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1076.
Full textFungi are the most important plant pathogens on agricultural and horticultural crops. Study of fungal pathogens remains essential to understand pathogenic process and control plant diseases. These organisms secrete high amount of degrading enzymes involved in plant decomposition and they feed by absorption of degraded nutriments. Secretory proteins were described to be transported form Endoplasmic Reticulum and Golgi apparatus to extracellular space through intracellular vesicles. In filamentous fungi, intracellular vesicles were observed using electron microscopy but their biogenesis process is still unknown. Therefore, elucidation of the process and the identification of proteins involved in secretory vesicles biogenesis remains a challenge to understand virulence factors delivery. A nonpathogenic mutant altered in the expression of the gene coding for clathrin heavy chain was selected in a random mutant library generated in the necrotrophic pathogen Botrytis cinerea,. This gene is essential in many organisms, thus a clathrin dominant negative mutant was generated and confirming the nonpathogenic phenotype observed on several host plant. In eukaryotic cells, clathrin heavy chain is mainly described to be involved in endocytosis, but it is also essential for high density secretory vesicles formation in yeast. Characterization of the mutants using a proteomic approach revealed a secretion defect of 82 proteins including known virulence factors, as Plant Cell Wall Degrading Enzymes and elicitors. Furthermore, the clathrin mutant revealed a strong reduction of intracellular vesicles production. Clathrin was also localized in living cells using fluorescent GFP-tag protein. Endocytosis was also studied and surprisingly, any observable defect was observed for clathrin mutants. This study demonstrated for the first time the essential role of clathrin in the infectious process of a fungal pathogen and its role in virulence factors secretion
Wan, Bin. "Interactions Drosophiles-guêpes endoparasitoïdes : rôle des vésicules extracellulaires du venin de Leptopilina boulardi dans le transport de facteurs de virulence et la spécificité d’hôte." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4143/document.
Full textEndoparasitoid wasps, such as Leptopilina boulardi (Figitidae), develop inside Drosophila host larvae, mainly D. melanogaster. Egg oviposition normally results in a capsule formation by specialized haemocytes, the lamellocytes, associated with a melanization reaction. The parasitic success of L. boulardi relies on injection with the egg of venom that blocks the action of lamellocytes. This venom, synthesized at the level of a specialized gland and stored in a reservoir, contains protein components and original vesicles (venosomes). I have shown that two described virulence factors, LbGAP and LbGAP2 (VFs), are embedded in venosomes during their assembly which seems to occur extracellularly in the duct connecting the venom gland to the reservoir. Microinjection of purified venosomes protects the egg from encapsulation like venom injection. Fluorescently labelled venosomes and VFs co-immunolocalize in lamellocytes after injection and their internalization involves a flotillin/raft-domain-dependent endocytosis. The venosomes internalization rate differs significantly between the Drosophila host species tested (D. melanogaster>D. simulans>D. yakuba>D. suzukii) and is correlated with the parasite success rate, suggesting the existence of specific receptor on lamellocytes of D. melanogaster. Using the HopTum-1 mutant that constitutively produces lamellocytes, I have purified these cells and performed proteomic analysis of their membrane to identify candidate receptors. My results demonstrate that venosomes are interspecies transport vehicles involved in parasite virulence that represent a new level of host specificity
Trozzo, Roberto. "Formes d’une vésicule en géométrie confinée." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4319/document.
Full textVesicles are drops of radius of a few tens micrometers, bounded by an impermeable lipid membrane of approximately 4 nm thickness, and embedded in an external viscous fluid. The specific properties of the vesicle membrane make the system very deformable and very constrained at the same time. Vesicles represent also an interesting simplified model for red blood cells, since they also share some similar mechanical behaviours.This manuscript deals with the modeling of a vesicle subjected to external stresses of hydrodynamical origin, in the Stokes regime and in confined domains. Starting from an existing BEM model for free space flows, original numerical methods are developed to deal with the computation of interactions between the vesicle membrane and solid boundaries. A particular attention is paid to the situation of a vesicle sedimenting towards a planar wall and a vesicle submitted to a Poiseuille flow in a narrow capillary
Tahiri, Najim. "Simulation de Globules Rouges modèles, et analyse analytique de modèles de suspensions très concentrées." Phd thesis, Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-01023517.
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