Thèses sur le sujet « Cellule souche neural »
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Loison-Robert, Ludwig. « Cellule souche gingivale : origine et multipotence ». Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC0083/document.
Gingiva is a natural regeneration model thanks to its "ad integrum" healing capability. Gingival fibroblasts are the main actors of this property. These cells, the main cellular component of the gingival connective tissue, regulate the inflammatory responses and healing process. This tissue contains, like many others, mesenchymal stem cells; which also partly explain these regenerative abilities. Moreover, as the gingiva is abundant and easily accessible, the use of these stem cells may interest cell therapy or in vitro model tissues responses. In this work, we demonstrated that Stem Cells Derived from Human Gingiva (SCHG) have common properties with neural crest adult stem cells. These cells can be called "stem cells" for their ability to self-renew, adhere to plastic and to differentiate. First, we have shown that the method and the culture products used for isolation of gingival fibroblasts from gingival biopsy had an influence on the obtained cells. Secondly, an analysis of in vitro clonal populations of gingival fibroblasts has shown that gingival fibroblasts are composed of subpopulations that express specific markers of stem cells and neural crests. In addition to their embryological origin, the study of their multipotency was also characterized after expansion and depending on the used additives. Finally, two examples of using these cells and dental pulp stem cells as a model to study the in vitro biocompatibility of biomaterials have been developed, mimicking oral mucosa or dentin reactions (reparative or reactional)
Katz, Shauna. « Rôle de microARN-9 dans la régulation de l'état cellule souche neural chez l'adulte ». Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS086.
Since the seminal discovery of multipotent neural stem cells (NSCs) in the adult mammalian brain, multiple studies have unravelled the importance of these cells for maintaining brain homeostasis. Notably, disturbances in NSC equilibrium have been linked to physiological aging and various neurological pathologies thus sparkling interest in harnessing them for use in regenerative medicine. NSCs reside in distinct germinal zones; in the adult rodent brain NSCs are found mainly in two well-established neurogenic niches in the telencephalon which contrasts with the situation in the adult zebrafish where NSC niches are widespread throughout the brain, including in the dorsal telencephalon or pallium. In both the rodent and zebrafish brains, adult NSCs display fundamental stem cell properties: they are multipotent, e.g. capable of generating new neurons and glia throughout adult life, and have the capacity for long-term self-renewal. Similar to stem cells in other adult tissues, and in contrast to embryonic neural progenitors, a hallmark of these adult NSCs is their relative proliferative quiescence. Quiescence is an actively maintained, reversible state of cell-cycle arrest and generally thought to protect against exhaustion of the stem cell pool. In line with this, disrupting the balance between quiescent and activated NSCs leads to a premature depletion or permanent cell-cycle exit of these cells highlighting the importance of fully deciphering the mechanisms regulating this equilibrium. microRNAs, a major class of small pleiotropic regulatory RNAs, play crucial roles in reinforcing developmental and transitional states. They are capable of reacting to environmental cues, both cell-intrinsic and -extrinsic, with varying outputs such as changing their regulatory functions and expression levels, thus enabling them to coordinating diverse cues to induce cell-state transitions. One microRNA in particular, miR-9, is a highly conserved master regulator of embryonic neurogenesis and in the embryonic zebrafish brain, it establishes a primed neural progenitor state enabling them to quickly respond to cues to differentiate or proliferate. The primary goal of this study was to investigate, for the first time, a potential role for miR-9 in influencing NSC state in a physiological context in which the majority of NSCs are quiescent – the adult zebrafish pallium. We found that miR-9 is exclusively expressed in quiescent NSCs and highlights a “sub-state” within quiescence. In part by maintaining high levels of Notch signalling, a known quiescence promoting pathway, miR-9 anchors NSCs in the quiescent state. Strikingly, we identified a conserved age-associated change in the subcellular localization of the mature miR-9 from the cytoplasm of all embryonic/juvenile neural progenitors to the nucleus of a subset of quiescent NSCs in the adult brain. Moreover, the nuclear expression of miR-9 in these quiescent NSCs is highly correlated with nuclear localization of the microRNAs effector proteins Argonaute (Agos), suggestive of a functional role for nuclear miR-9. Indeed, the elucidation of the nuclear-cytoplasmic transport mechanism of miR-9/Agos enabled us to manipulate their nuclear to cytoplasmic ratios which directly impacted NSC state. Altogether, these results identify miR-9 as a crucial regulator of NSC quiescence, provide for the first time a molecular marker for an age-associated sub-state of quiescence and suggest the involvement of a novel and unconventional microRNA-mediated mechanism to maintain homeostasis of NSC pools
Clavairoly, Adrien. « Ascl1 and Olig2 transcriptional regulations of oligodendrogenesis ». Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066316/document.
Our project aims to provide a new molecular understanding of the transcription program involved in neural stem cells differentiation into oligodendrocytes. The rational of this work relies on previous studies demonstrating that the bHLH transcription factors Olig2 and Ascl1 work in synergy to specify OPCs, the oligodendrocyte progenitor cells. One central goal of this work was to understand at a genomic and transcriptomic level, how Ascl1 and Olig2 work together to specify OPCs. We followed a strategy using genome-wide transcriptome analysis and chromatin immuno-precipitation to characterize Ascl1 and Olig2 directly regulated genes in OPCs and during oligodendrocyte differentiation.We identified new specific markers of different stage of the neural lineages and new important genes correlated to OPCs differentiation. We focused on Chd7 and Tns3, two genes which expressions are driven by Ascl1 and Olig2 and enriched in the oligodendroglial lineage at two interesting stage, the early specification stage and the transition between migrating and differentiating oligodendrocytes, respectively. Moreover, we identified the myelinating oligodendrocyte as the cell in charge of the creatine synthesis in the brain and potentially driving axonal metabolic support. We also used an approach a toxicogenomic and drug repositioning approach to identify new molecules known to modify OPCs and myelin genes but untested in the context of demyelinating diseases. As currently, most of the available treatments for demyelinating diseases are based on immuno-modulatory and anti-inflammatory drugs but none are able to directly promote myelin repair, we expect that these identified genes involved in oligodendrogenesis and whose expression are regulated in demyelinated lesions will allow the development of new therapeutic strategies promoting an efficient remyelination in demyelinating diseases such as Multiple sclerosis or leukodystrophies
Flici, Hakima. « Différenciation et plasticité des cellules souches neurales ». Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-01070644.
Terrie, Élodie. « Rôle de la signalisation calcique dépendante des Store-Operated Channels (SOC) dans les cellules souches neurales adultes et les cellules souches cancéreuses de glioblastomes ». Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2322.
Neural stem cells (NSC) persist in the brain of adult mammals and fuel the brain with new neurons and glial cells all lifelong. Recruited by brain injuries, NSC are considered with great interest by regenerative medicine. However, the development of new therapeutic approaches based on the use of NSC requires an in-depth knowledge of the mechanism regulating these cells. Glioblastomas are the most frequent and deadliest form of adult brain tumors. Within the tumor, glioblastoma stem cells (GSC) form a subpopulation of cells that is considered as responsible of tumor initiation, propagation and relapse, as these cells are particularly resistant to anti-tumoral treatments. GSC and NSC share key characteristics and numerous studies suggest that GSC arise from transformed NSC. Transcriptomic analysis of NSC and of GSC revealed an enrichment of calcium signaling transcripts in these two cell populations. Representing a major way of calcium influx into cells, Store-Operated Channels (SOC) are mobilized in response to a wide range of extracellular factors. SOC regulate many cellular processes and are often hijacked in cancer to promote tumor progression.The aim of this thesis is to evaluate potential SOC involvement in NSC and GSC regulation.The first part of this work, relying on in vitro and in vivo studies, demonstrates that NSC from adult mice express functional SOC whose inhibition by pharmacological agents reduces NSC proliferation and self-renewal. In the second part of this thesis, we demonstrate that GSC from primary cultures derived from patients express SOC, as do NSC, and that SOC inhibition reduces GSC ability to proliferate and self-renew.Accordingly, the results of this thesis demonstrate that SOC regulate NSC and GSC self-renewal, a property that is essential to maintain stem cells pool. As GSC are responsible for glioblastomas treatment resistance, our studies point to a potential new therapeutic way, via calcium channels, against this deadly pathology
Mancini, Laure. « Spatiotemporal control of Neural Stem Cell decisions in the adult zebrafish telencephalon ». Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS154.pdf.
In some regions of the adult vertebrate brain, Neural Stem Cells (NSCs) generate fully functional neurons. NSCs are found mostly in quiescence, but can shuttle from quiescence to activation (division). At the population level, the proportion of NSCs dividing at a given time remains constant throughout adulthood and perturbations of NSC activation rate correlate with pathological situations. Also, the spatiotemporal distribution of NSC activation events is expected to impact the homogeneous maintenance of the NSC pools and the locations of neuronal production. What controls the rate and spatiotemporal distribution of NSC activation events remain poorly understood. The adult zebrafish telencephalon is a good model to address these questions. The telencephalon hosts many NSCs and it allow the recording of their behaviors over weeks thanks to an intravital imaging procedure. In this thesis, we have used this model to study the regulation of adult NSCs behaviors from two perspectives. First, we assessed the existence of non-cell-autonomous mechanisms controlling the quiescence-activation balance of the NSC population in space and time. Second, we investigated the relevance of intrinsic heterogeneities on individual NSC behaviors. This work highlighted (i) the importance of NSC geometry for their fate decisions during activation and (ii) the role of their differentiated progeny to locally exert a delayed inhibition, via Notch signaling, to prevent neighboring NSC activation. Using modeling we also show how the lineage-related inhibition maintains NSCs with specific spatiotemporal correlations and can spatially homogenize the distribution of adult-born neurons
Jourdon, Alexandre. « Prss56Cre, un nouvel outil pour l'étude de la neurogenèse adulte chez la souris ». Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066082/document.
The Prss56 gene encodes a serine protease involved in eye pathologies and development in humans. Prss56 expression pattern and function in the rest of the central nervous system were however unknown. Here, I used a knock-in allele in the mouse, Prss56Cre, carrying a Cre recombinase insertion in the locus, to establish the pattern of expression of the gene and to trace the derivatives of Prss56-expressing cells. I found that, in the adult mouse, Prss56 is specifically expressed in three neurogenic niches: the dentate gyrus (DG), the subventricular zone (SVZ) and the hypothalamus ventricular zone (HVZ). In the prospective DG, Prss56 is expressed during embryogenesis in a subpopulation of radial glia. Consistently, the pattern of migration and differentiation of traced cells during development recapitulates the successive steps of DG neurogenesis, including the formation of a subpopulation of adult neural stem cells (aNSC). In the SVZ, Prss56 is expressed after birth in a subpopulation of aNSC mainly localized in the medial-ventral region of the lateral wall. This subpopulation preferentially gives rise to deep granule and calbindin-positive periglomerular cells in the olfactory bulb. Finally, Prss56 is also expressed in a subpopulation of alpha2-tanycytes, potential aNSC of the adult HVZ. My observations reveal that some traced tanycytes translocate their soma into the parenchyma and might give rise to a novel cell type in this territory. In conclusion, this study establishes the Prss56Cre line as a novel and efficient tool to study various aspects of adult neurogenesis in the mouse
Daynac, Mathieu. « Caractérisation des facteurs de régulation de la prolifération des cellules souches neurales dans le cerveau adulte ». Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00968161.
Angonin, Diane. « Lineage-specific manipulation of subventricular zone germinal activity for neonatal cortical repair ». Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1175/document.
Perinatal hypoxia leads to degeneration and delayed maturation of oligodendrocytes and cortical glutamatergic neurons. My PhD project consists in assessing the contribution of neural stem cells (NSCs) of the dorsal subventricular zone (dSVZ, i.e. the largest germinal zone of the postnatal brain) to the spontaneous regenerative attempt observed following such injury as well as its amenability to pharmacological manipulation.The results I have obtained highlight a dynamic and lineage-specific response of NSCs of the dSVZ to hypoxia that results in de novo oligodendrogenesis and cortical neurogenesis. Newborn cortical neurons express appropriate cortical layer markers, supporting their appropriate specification. A pharmacogenomics analysis allowed us to identify small molecules boosting specificly dSVZ NSCs. Pharmacological activation of Wnt/ß-catenin signalling by intranasal GSK3ß inhibitor administration during the recovery period following hypoxia indeed potentiates dorsal SVZ participation to post-hypoxia repair. Gsk3b inhibitor CHIR99021 seems to promote survival of cortical neurons from the dSVZ produced in response to hypoxia. More interestingly, CHIR99021 promotes oligodendrocyte maturation and long term integration in the cortex as well as a long term increased activity of dSVZ NSCs.Altogether, my results highlighted a dynamic and lineage-specific response of dorsal NSCs cells to hypoxia and identify the early postnatal dorsal SVZ as a malleable source of stem cells for cortical repair following trauma that occur early in life. CHIR99021 (a Gsk3b inhibitor) intranasal administration promotes this cortical cellular repair with a long term activation of dSVZ NSCs which increased their production of oligodendrocytes migrating to the cortex and a short term improvement of their maturation, and might allow the integration of cortical neurons they produce
Chaves, Vieira Lins Luanda. « Study and development of electrospun fibers for biotechnology application ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI073.
Currently, the electrospinning process is also one of the most promising routes for the design and development of polymer fibers. This technique is easy to use, unique, versatile, and low cost, which can be used to create fibers from a variety of starting materials. The structure, chemical and mechanical stability, functionality, and other properties of the fibers can be modified to match end applications. The first goal of this thesis was to develop scaffolds for the field of neural tissue engineering in order to mimic the biological, physical and mechanical properties of the native extracellular matrix. In the first time, the effect of fiber alignment of a biocompatible and fluorinated matrix denoted polyvinylidene fluoride (PVDF) was studied on the behavior of monkey neural stem cells particularly the morphology, cell adhesion and their differentiation in glial or neuronal cells. Secondly, bioabsorbable scaffolds composed of polylactide (PLA) and polyethylene glycol (PEG) polymers were synthesized to investigate the influence of the hydrophilic-hydrophobic balance on the culture of neural stem cells. Finally, an exploratory work was conducted to develop smart textiles based on poly(butylene adipate-co-terephthalate) (PBAT) containing curli as protein, well-known for its ability to chelate metals
Rigaud, Stephane Ulysse. « méthodologie de modélisation de la croissance de neurosphères sous microscope à contraste de phase ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-01001639.
Bolz, Marianne. « Régulation du destin cellulaire pendant la neurogénèse postnatale : rôle de l'innervation dopaminergique issue du mésencéphale ». Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4098.
In the postnatal and adult mammalian brain neurogenesis persists in the subgranular zone of the hippocampal dentate gyrus and the subventricular zone (SVZ). In the SVZ slowly dividing stem cells give rise to neuroblasts that migrate to the olfactory bulb (OB) where they reach the granule and glomerular cell layer of the OB and differentiate into different interneuron subtypes including a small fraction of dopaminergic interneurons. The discovery of postnatal and adult neurogenesis has changed the view of the plasticity of the brain remarkably and raised the hope for new therapeutical approaches in the field of neurodegenerative diseases. Since in Parkinson’s disease the main motor symptoms are caused by the dopaminergic denervation of the striatum adjacent to SVZ, the understanding of the generation and differentiation of OB dopaminergic neurons has received special attention. Interestingly, the neurotransmitter dopamine itself has been suggested to influence olfactory bulb neurogenesis via direct innervation of SVZ by midbrain dopaminergic neurons. However, data on this topic have been contradictory. In this study, I investigated how dopaminergic innervation influences SVZ neurogenesis and the fate of SVZ progenitors. I combined a 6-OHDA model of dopaminergic denervation in postnatal mice with in vivo forebrain electroporation to specifically label lateral and dorsal SVZ progenitors and to follow their fate in the olfactory bulb
Acuña, Mendoza Soledad. « Sources alternatives de cellules souches pour la bio-ingénierie de la dent ». Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCB101.
Neural crest cells are multipotent progenitor cells that, during embryogenic development, migrate and differentiate into diverse lineages such as melanocytes, smooth muscle, peripheral and enteric neurons, glial cells as well as craniofacial mesenchymatic components, including teeth. In the context of the development of an odontogenic model for tissue engineering, we have generated a new cell line of embryonic stem cells (ES) obtained from blastocysts from crossing Wnt1-CRE mice with fluorescent reporter Rosa26 mT/mT mice. In this Cre/Lox system the cells that have acquired a CN identity and thus expressing Wnt1, will become and remain fluorescent due to the activation of Tomato expression. We have generated a simplified protocol in a monolayer cell culture in defined serum-free medium in order to differentiate the cells into CN cells, named ES-CN cells. Second, we investigated the signals necessary for the odontogenic specification of these ES-CN cells. Our study provides evidence that the Wnt1-CRE/Tomato cell line 1) is a competent ES cell line with the expression of pluripotent markers, a stable karyotype and the ability to differentiate in vitro and in vivo into all the three embryonic germ layers, 2) acquires in vitro a CN identity after induction with our protocol, 3) expresses odontogenic markers in hypoxic culture conditions and 4) is able to interact with an oral epithelium in order to form orofacial skeletal tissues via the tissue reassociation in vitro. This novel cell model should facilitate the understanding of the mechanisms implicated in the ectomesenchymatic interaction, at the base for formation of orofacial skeletal tissues, and will provide the possibility to follow the fate of ES-CN cells tissue engineering models of wounded orofacial structures in general
Ferré, François. « Isolation et caractérisation des cellules souches gingivales : étude de leur potentiel multipotent ». Phd thesis, Université René Descartes - Paris V, 2013. http://tel.archives-ouvertes.fr/tel-01017172.
Delmouly, Karine. « Cellules Souches Neurales : modélisation et thérapie cellulaire des maladies à prions ». Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20134/document.
Transmissible Spongiform Encephalopathies (TSE) are neurodegenerative disorders with long asymptomatic incubation periods and fatal issue. They are induced by accumulation of the pathogen isoform of the prion protein (PrPSc) in the central nervous system (CNS) resulting in neuronal degeneration and astrogliosis. PrPSc, produced by the conversion of the physiological form of the prion protein (PrPC), plays a key role in the disease transmission. The mechanisms underlying the conversion of PrPC and the propagation of PrPSc are uncertain just as the molecular mechanisms giving rise to prion diseases. In the aim of creating or improving cell culture models, it has been shown that CNS Neural Stem Cells (NSC) could support PrPC conversion into PrPSc in vitro. In this project, we used NSC to improve and characterize cellular infection and hypothesized that modification of culture conditions could modulate PrPSc production in NSC. Hence, we used factors known to influence cellular identity in our culture model and showed that higher amount of prions were produced. These models also allow molecular mechanisms studies that could be at infection origin. During the course of this study, we also demonstrated that HEPES added to our culture medium could stop prion propagation in a dose-dependant manner. Moreover, to date no therapy aimed at stopping disease progression has been established in humans. We therefore used NSC with the ultimate goal to elaborate a therapeutic strategy based on the delivery of antibodies into the CNS to block prion replication. These cells will also able to repair damaged brain area thus combining cell and gene therapy
Laurenson, Anne-Sophie. « Transformation des cellules souches neurales en cellules souches cancéreuses de glioblastome : rôle de la voie de signalisation Delta-Notch ». Strasbourg, 2009. http://www.theses.fr/2009STRA6151.
Bouissac, Julien. « Rôle de la voie Notch dans la spécification des cellules souches neurales et dans la différenciation des précurseurs neuraux : Utilisation du système modèle des neurosphères ». Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/BOUISSAC_Julien_2005.pdf.
In our laboratory we are interested in the role of the Notch pathway on cell fate decision of neural stem cells and on their differentiation into neurons and glia in the model system of neurospheres. Neurospheres derive clonally for neural stem cells and proliferate in suspension in the adapted cell culture medium. Neurospheres prepared from Dll1 mutant embryos segregate more neurons at the expense of both oligodendrocytes and astrocytes, compared to the wild-type ones. Our results indicate that the Notch pathway is acting in two steps: (i) in a first step it inhibits the neuronal fate while promoting glial fate, (ii) in a second step Notch promotes the differentiation of astrocytes while inhibiting the differentiation of both neurons and oligodendrocytes. In parallel to this work we have tested the effects of small non peptidic molecules on the cell fate decision of neural stem cells. One of these molecules, referred to as tCFA15, increases the number of neurons at the expense of glial cells, in a manner reminiscent of that resulting from the inactivation of Notch through the Dll1 mutation. Molecular analysis has shown that tCFA15 consistently decreases the expression of Notch1 gene, and subsequently of Hes5, a downstream target gene of Notch activation. In addition, we have shown that tCFA15 causes a diminution of the tyr705 phosphorylation of STAT3, thereby suggesting a link between both Notch and STAT3 signalings. We established a functionnal hierarchy between Notch and STAT3 by experiments combining gain and loss of functions for these two pathways and we found that in the system of neurospheres STAT3 is an upstream regulator of Notch1. These results have been confirmed by molecular analysis. In parallel to this work we have also tested the neurotrophic effect of other non peptidic small molecules in the system of neurospheres
Gengatharan, Archana. « La physiologie des cellules souches dans le cerveau adulte ». Doctoral thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/68740.
Neural stem cells (NSCs) persist in the subventricular zone of adult brain and transit from the quiescent to the proliferative states to produce new neurons. The mechanisms regulating the transition froma quiescent to a proliferative state remain unclear. Since adult NSCs are enriched in genes associated with Ca2+ signalling pathways, we aimed to determine whether the transition from quiescence to aproliferative state is Ca2+ dependent. Here, we used miniature endoscopes (mini-endoscopes) to monitor NSC division and their regulation by Ca2+ signalling in freely behaving mice. Our data revealeddifferent Ca2+ dynamics and steady-state Ca2+ intracellular levels during NSC division. Pharmacological and in vivo CRISPR-Cas9 gene editing showed that IP3-sensitive intracellular stores and G-proteins regulators regulate the transition from quiescence to proliferation. We further used in vivo optogenetics to mimic Ca2+ dynamics of quiescence state to maintain NSCs in this state and prevent NSCsto transit into proliferative state. Our results demonstrate that Ca2+ dynamics and Ca2+ intracellularlevels play an important role in NSC activation. Next, we investigated NSCs microenvironmentmainly blood vessel and their role in their physiology. The NSCs contact the blood vessels by extending their basal processes. Direct cell-cell contact and the release of factors such as VEGF (vascularendothelial growth factor) by endothelial cells (EC) influence the NSC behaviour. As Notch pathwayis a key player in vasculature signalling, we inhibit in vivo the Notch signalling specifically in EC.We found that inhibition of Notch signalling in EC at early stage (P0) or later stage (P30) increasesNSC number. Morphological analysis of blood vessel reveals no alteration when Notch signalling isinhibited at later stages (P30). These finding showed that inhibition of Notch signalling in EC maintains NSC in quiescence state.
Denis, Jérôme Alexandre. « MODELISATION PATHOLOGIQUE DES MALADIES MONOGENIQUES PAR L'UTILISATION DES CELLULES SOUCHES EMBRYONNAIRES HUMAINES. PREUVE DE CONCEPT APPLIQUEE A LA DYSTROPHIE MYOTONIQUE DE TYPE 1 ». Phd thesis, Université d'Evry-Val d'Essonne, 2010. http://tel.archives-ouvertes.fr/tel-00545797.
Rousseau, Laure. « Réponse à l'irradiation in vivo des cellules souches neurales foetales ». Thesis, Paris 5, 2012. http://www.theses.fr/2012PA05T009.
Neurogenesis is a highly controlled process that allows the production of all the neurons during a limited time. Any perturbation may induce a loss of neurons and an eventually oncogenic genetic instability. Among various damages, ionizing radiation (IR) induces double strand breaks (DSB), one of the most serious damages. IR is commonly used for medical diagnosis and is produced during nuclear disaster. The developing cortex is particularly sensitive to ionizing radiation. We analyzed in vivo the different mechanisms of the DNA damage response of mouse neural stem cells and progenitors (NSCP). We showed that IR induces cell cycle arrests in G2/M and intra-S but not in G1/S, contrary to what is observed in most of the cell lines. We also determined the importance of homologous recombination (HR), the most accurate of DSB repair pathways for the survival of the cortical cells. So, irradiated in S or G2 phase NSCP need HR to survive, contrary to those irradiated in G1 or to post-mitotic neurons. We also observed the reconstruction of the pool of NSCP to the detriment of the neuron production, in the first hours after irradiation. This study allowed a better understanding of the DNA damage response mechanisms of NSCP
Rolland, Maude. « Physiopathologie de l'infection par le cytomégalovirus sur les progéniteurs neuraux humains ». Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30314/document.
Congenital infection by human cytomegalovirus (HCMV) is a leading cause of permanent sequelae of the central nervous system, including sensorineural deafness, cerebral palsies or devastating neurodevelopmental abnormalities (0.1 % of all births). To gain insight on the impact of HCMV on neuronal development, we used both neural stem cells from human embryonic stem cells (NSC) and brain sections from infected fetuses. We investigated the outcome of infection on Peroxisome Proliferator-Activated Receptor gamma (PPARg, a transcription factor critical in the developing brain. We observed that HCMV infection dramatically impaired the rate of neuronogenesis and strongly increased PPARg levels and activity. Consistent with these findings, levels of 9-hydroxyoctadecadienoic acid (9-HODE), a known PPARg agonist, were significantly increased in infected NSCs. Likewise, exposure of uninfected NSCs to 9-HODE recapitulated the effect of infection on PPARg activity. It also increased the rate of cells expressing the IE antigen in HCMV-infected NSCs. Further, we demonstrated that (1) pharmacological activation of ectopically expressed PPARg was sufficient to induce impaired neuronogenesis of uninfected NSCs, (2) treatment of uninfected NSCs with 9-HODE impaired NSC differentiation and (3) treatment of HCMV infected NSCs with the PPARg inhibitor T0070907 restored a normal rate of differentiation. The role of PPARg in the disease phenotype was strongly supported by the immunodetection of nuclear PPARg in brain germinative zones of congenitally infected fetuses (N=20), but not in control samples. We also identified LIS1 as one of the target genes for PPAR??in the infected brain. Levels of LIS1, the gene of classical lissencephaly, were strongly increased in infected NSC, presumably resulting from increased PPAR? activity. The relevance of this finding was further supported by our demonstration of a massive increase in the immunodetection in LIS1 fetal brains congenitally infected with HCMV (N = 6), relative to control cases (N = 3). Indeed, it is well known that overexpression of LIS1 is responsible for significant abnormalities of neural migration and development of a lissencephaly-like phenotype. Altogether, our findings reveal a key role for PPARg in neurogenesis and in the pathophysiology of HCMV congenital infection. They also pave the way to the identification of PPARg gene targets in the infected brain
Nassif, Ali. « Rôle des cellules orales dérivées des crêtes neurales dans la morphogenèse craniofaciale ». Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC0090.
Craniofacial morphogenesis in vertebrates is an important phenomenon, strictly regulated in space and in time. It is based on a complex series of molecular and morphogenetic events involving an interactional network of genes and transcription factors, such as the homeobox. Neural crest (NC) is at the heart of this process. The latter provides the main source of craniofacial mesenchyme. This transient population of embryonic cells will undergo epithelial-mesenchymal transition and migrate in waves to predefined sites and to differentiate into various cell types. NC is the source of several structures: a large part of the facial skeleton including the maxillary, mandibular alveolar bone around the teeth as well as connective tissue in craniofacial portion. Cells from NC are pluripotent and offer hope for bone and cartilage regeneration. These characteristics have generated particular interest to researchers for use in cell therapy to repair bone defects of the jaw. Among the craniofacial tissues, we decided to further investigate the gums and gingival cells because their access is easier and differentiation capabilities allow observation of other cellular phenotypes.The gum is a keratinized tissue around the teeth and covers the alveolar bone. This tissue is composed mainly of populations of gingival fibroblasts (GFs). Among these populations, there are gingival stem cells (GSCs) characterized by their self-renewal and pluripotency. The GSCs are easily collected in adult patients, they show significant plasticity and immunomodulatory activity that make it a tool of choice for cell therapy. In addition, the biopsy is painless and involves neither scar nor functional problem.The first part of my PhD work was to evaluate the Msx1 role in craniofacial morphogenesis and subsequently analyse the alveolar bone after tooth extraction to analyse the mechanisms involved in this process and the impact of Msx1 on bone healing.The second part of my work focuses on the gingiva and was intended to highlight the embryological origin of oral stem cells, including GSCs and determine if they come from the neural crest, mesodermal or mosaic two. Finally, to apply our knowledge of the embryological origin of gum stem cells, we studied the immune profile derived NC cells. For this, we determined the phagocytic capacity gingival murine stem cells derived from CN and compared to cells of CN other vertebrate species
Than, Trong Emmanuel. « Le rôle de la signalisation Notch3 dans le maintien des cellules souches neurales du télencéphale adulte Neural stem cell quiescence and stemness are molecularly distinct outputs of the Notch3 signaling cascade in the vertebrate adult brain her4-expressing neural stem cells are maintained through population asymmetry and embedded into a hierarchy of progenitors responsible for their life-long expansion Radial Glia and Neural Progenitors in the Adult Zebrafish Central Nervous System ». Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS541.
New neurons continue to be added into discrete brain regions of most adult vertebrate species, including humans. Adult born neurons arise from precursor cells, called neural stem cells (NSCs), endowed with self-renewal potential and mostly found in a state of reversible cell cycle arrest, named quiescence. Currently, the molecular, cellular and population rules allowing NSC to balance maintenance and differentiation remain incompletely understood. At the single cell level, several factors and signalling pathways were demonstrated to be essential for NSC homeostasis. Among them, the Notch signalling pathway is critically involved in the control of NSC quiescence and stemness. However, whether these two properties represent molecularly distinct or overlapping outputs of the Notch signalling pathway remains unknown. At the cellular level, current models state that NSCs divide rarely and mostly asymmetrically, allowing both self-renewal and the generation of a more committed progeny that ultimately exits the cell cycle and fulfils neuronal differentiation. The adult zebrafish pallium harbours NSCs, called radial glia (RG), which share with their mammalian counterparts the same basic properties. Previously, our laboratory demonstrated that Notch3 was necessary to maintain RG quiescence. Here, in two different and complementary works, we took advantage of the widespread neurogenic ventricular zone (VZ) of the adult zebrafish pallium to (1) explore further the role of Notch3 signalling in RG homeostasis and (2) investigate the division pattern and dynamics allowing the RG population to be maintained on the long run. In the first study, we demonstrate that the role of Notch3 signalling extends beyond the simple maintenance of RG quiescence and that Notch3 also contributes to RG stemness. By overlapping the transcriptomic profiles of both notch3 mutant RG and adult pallial VZ progenitors, we identified different sets of Notch3 target genes potentially responsible for its pleitropic effect in RG. Notably, we show that the Notch3 signalling contribution to RG stemness critically relies on the transcriptional activation of its canonical target gene hey1 and this, independently of Notch3 action on RG quiescence. In the second study, we performed a quantitative analysis of the fates of individual her4.1(Hes5)-expressing RG. We demonstrate that these cells adopt balanced stochastic fates, which allows their population to reach homeostasis. We also report that the overall RG population of the zebrafish pallium continues to grow during adulthood and that this expansion is very likely driven by a yet undefined upstream population of progenitors. As a consequence, we propose that the adult zebrafish is organised into a hierarchy of progenitors dominated by an unknown population that fuels the ongoing production of an intrinsically homeostatic population of RG which, itself, follows neutral drift dynamics
Morizur, Lise. « Régulation de la quiescence et de la prolifération des cellules souches neurales dans le cerveau adulte ». Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS549/document.
The production of new neurons, a process called neurogenesis, persists during adulthood and is ensured by neural stem cells (NSCs) that are located in specialized niches in the mammalian brain such as the subventricular zone (SVZ). However, adult neurogenesis declines dramatically following brain damage and during aging leading to irreversible cognitive deficits. Using a flow cytometry-based cell sorting strategy, we show that the progressive age-related decline in SVZ neurogenesis is not caused by a loss of NSCs but rather by a proliferation deficit of NSCs with the lengthening of their G1 phase due to increased levels of TGFβ1. We then sorted quiescent and proliferative NSCs to characterize their functional properties and define their gene expression profiles. Comparative analysis of the two populations of NSCs reveals that the balance between quiescence and proliferation is regulated at multiple levels with the integration of external signals from the microenvironment and distinct transcriptional programs. Taken together, our results open new vistas into the potential use of endogenous quiescent NSCs as therapeutic targets to increase neurogenesis in the aged brain and to participate to the regeneration of damaged brain tissue
Vargas, Hurtado Diana. « Étude des mécanismes d’assemblage du fuseau et de la fidélité mitotique dans les cellules souches neuronales du cerveau en développement ». Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2019. https://theses.hal.science/tel-03054330.
The mammalian brain holds a peculiar vulnerability to centrosome or mitotic spindle dysfunction. Mutations in centrosome or spindle encoding genes are the leading cause of Human Primary Recessive Microcephaly (MCPH), a neurodevelopment growth disorder were the brain is drastically reduced in size yet body size is not affected. Loss of neural progenitor cells or apical Radial Glial cells (aRGCs) during brain development causes microcephaly. The lab has previously shown that the presence of supernumerary centrosomes leads to mitotic errors and consequent apoptosis of aRGCs. They also noticed a higher susceptibility to mitotic errors and cell death at early stages of neurodevelopment as compared to late stages. The underlying mechanisms that render aRGCs vulnerable are still unknown. To identify the mechanisms behind aRGC vulnerability, I characterized during my PhD mitotic spindle assembly during normal mouse brain development. Surprisingly, I found that aRGC spindle morphology changes between early and late stages of neurogenesis. At early stages, spindles are prone to interact with the cell cortex through astral MTs which comes at the expense of MT density within the spindle. In contrast, at late stages, spindles decrease astral MT numbers while reinforcing MT inner cell density. Furthermore, I identified the microtubule stabilizing and bundling factor TPX2 as one key determinant of spindle robustness and mitotic accuracy after drug treatments in aRGCs from late neurogenic stages. Indeed, by decreasing TPX2 loading on spindle MTs, which was sufficient to switch spindle morphology to an early-like architecture, I observed an increased frequency of chromosome alignment and segregation errors. The data obtained reveal unexpected modifications in the pathways used by aRGCs to build a bipolar spindle during the course of neurogenesis, which are translated into different chromosome segregation capacity. I thus propose that during mammalian neurogenesis not all aRGCs are equally competent to segregate chromosomes correctly. My work therefore provides mechanistic insights by which mutations in genes encoding centrosome or spindle components might affect specifically brain size during embryonic development
Zangiacomi, Vincent. « Exploration du potentiel neural des cellules du sang de cordon ombilical humain ». Besançon, 2008. http://www.theses.fr/2008BESA2060.
During the last decade treatment of malignancies bas involved stem cell transplantation premarity using a limited supply of bone marrow donors. The use of other sources of stem cells such as cord blood has indirectly led to the discovery that certain stem cells within this population can give rise to other non-haematopoietic lineages such as neuronal cells. The progenitors that give rise to these cells have not been fully characterized. In this study, we observed that the neuronal lineage is derived from CD133+ / CD34- cells fraction and furthermore, close contact is also needed with facilitating cells for the differentiation to proceed. We also investigated the function of the neurotransmitter gamma amino-butyric acid (GABA) no cord blood cells. The GABA receptors are widely expressed within cord blood cells and cells migrate along a GABA gradient. The migration capacity can also be used to enrich for both haematopoietic and neurogenic cells. In conclusion, our results shed light on phenotypic and functional properties of cord blood stem cells and may increase their utilisation in cellular therapy protocol
Liu, Jia Wei. « Inducteurs de différenciation des cellules souches neurales : Etudes phytochimiques et pharmacologiques ». Strasbourg 1, 2007. http://www.theses.fr/2007STR13139.
The neural stem cells (NSCs) could be a promising tool for the treatment of many neurological disorders in the central nervous system (CNS). One could use neural stem cell transplantation or, even better, induce or enhance the neurogenic potentials of NSCs in situ. We are interested particularly in screening medicinal plants, to obtain small molecules that are capable to induce the neuronal differentiation of NSCs. Bioassay-guided fractionation, combined with screening based on NSCs differentiation assay, has been used to search for active molecules from Panax notoginseng F. H. CHEN. Three panaxadiol glycosides were identified as potential neurogenic molecules. Among them, Rg5 is the most potent. Rg5 inhibits the proliferation and astrocyte differentiation of NSCs, and promotes the neuronal differentiation of NSCs. Exposure of Rg5 to NSCs trigers an increase in influx of calcium, upregulates expression of proneural bHLH transcription factor Mash1 and downregulates the repressive-type transcription factor HES5. Moreover, application of Rg5 attenuates STAT3 phosphorylation level via an increase of SOCS3. In addition, the neurogenic effects of Rg5 can be reversed by nifedipine, a Ca2+ channel antagonist and by CNTF, a STAT3 activator. The preliminary study on the structure-activity relation suggests that the double bond at C-20(21) or C-20(22), and a carbohydrate at C-3 are important and beneficial factors for the neuronal differentiation of panaxadiol glycosides. In addition, the cytotoxic extracts have been further isolated using a antiproliferative assay-guided fractionation. Seven molecules against the proliferation of neuroblastoma B104 were identified from Elephantopus mollis Kunth. Among them, two are new molecules, one is triterpene and another is sesquiterpene lacton
Dromard, Cécile. « Caractérisation des cellules souches neurales des moelles épinières murine et humaine ». Montpellier 2, 2006. http://www.theses.fr/2006MON20031.
At present, no specific marker allows the identification of neural stem cells (NSC). Solely in vitro, the neurosphere model (NS, self-renewable, multipotent cellular aggregates), point them out. However, the heterogeneous composition of this model is ill-defined. We demonstrated (1) that medullar NS are composed of cells with a singular OPC/RGC phenotype (Oligodendrocyte Precursor Cell/Radial Glial Cell); (2) that “OPC-like” NG2+ NS cells are endowed with NSC properties; but (3) that, in vivo, medullar NSC are initially NG2- and acquire NG2 expression when cultured, suggesting a deregulation of the NSC phenotype in vitro. (4) This deregulation is confirmed using NS derived from the peripheral nervous system, that display similar differentiation features as spinal cord NS. Besides, the recent discovery of NSC in the adult human brain opens new ways for self-repairing treatments by stimulation of these endogeneous cells, and initiated the second objective of this work: the search for NSC in the adult human spinal cord. Immature cells were detected in the sub ependymal area, and proliferative NS could were expanded, and generated new neurons and glia. These results suggest for the first time the existence of neural progenitors in the adult human spinal cord
Marcy, Guillaume. « Etude des spécificités transcriptionnelles et de la compétence des progéniteurs neuraux postnataux du cerveau antérieur chez la souris ». Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEP070/document.
During development, a remarkable coordination of molecular and cellular events leads to the generation of the cortex, which orchestrates most sensorimotor and cognitive functions. Cortex development occurs in a stepwise manner: radial glia cells (RGs) - the neural stem cells (NSCs) of the developing brain - and progenitor cells from the ventricular zone (VZ) and the subventricular zone (SVZ) sequentially give rise to distinct waves of nascent neurons that form cortical layers in an inside-out manner. Around birth, RGs switch fate to produce glial cells. A fraction of neurogenic RGs that lose their radial morphology however persists throughout postnatal life in the subventricular zone that lines the lateral ventricles. These NSCs give rise to different subtypes of olfactory bulb interneurons and glial cells, according to their spatial origin and location within the postnatal SVZ. These observations raise important unresolved questions on 1) the transcriptional coding of postnatal SVZ regionalization, 2) the potential of postnatal NSCs for cellular regeneration and forebrain repair, and 3) the lineage relationship and transcriptional specificities of postnatal NSCs and of their progenies. My PhD work built upon a previously published comparative transcriptional study of defined microdomains of the postnatal SVZ. This study highlighted a high degree of transcriptional heterogeneity within NSCs and progenitors and revealed transcriptional regulators as major hallmarks sustaining postnatal SVZ regionalization. I developed bioinformatics approaches to explore these datasets further and relate expression of defined transcription factors (TFs) to the regional generation of distinct neural lineages. I then developed a model of targeted ablation that can be used to investigate the regenerative potential of postnatal progenitors in various contexts. Finally, I participated to the development of a pipeline for exploring and comparing select populations of pre- and postnatal progenitors at the single cell level. Objective 1: Transcriptomic as well as fate mapping were used to investigate the relationship between regional expression of TFs by NSCs and their acquisition of distinct neural lineage fates. Our results supported an early priming of NSCs to produce defined cell types depending of their spatial location in the SVZ and identified HOPX as a marker of a subpopulation biased to generate astrocytes. Objective 2: I established a cortical lesion model, which allowed the targeted ablation of neurons of defined cortical layers to investigate the regenerative capacity and appropriate specification of postnatal cortical progenitors. Quantitative assessment of surrounding brain regions, including the dorsal SVZ, revealed a transient response of defined progenitor populations. Objective 3: We developed a transgenic mouse line, i.e. Neurog2CreERT2Ai14, which allowed the conditional labeling of birth-dated cohorts of glutamatergic progenitors and their progeny. We used fate-mapping approaches to show that a large fraction of Glu progenitors persist in the postnatal forebrain after closure of the cortical neurogenesis period. Postnatal Glu progenitors do not accumulate during embryonal development but are produced by embryonal RGs that persist after birth in the dorsal SVZ and continue to give rise to cortical neurons, although with low efficiency. Single-cell RNA sequencing revealed a dysregulation of transcriptional programs, which correlates with the gradual decline in cortical neurogenesis observed in vivo. Altogether, these data highlight the potential of transcriptomic studies to unravel but also to approach fundamental questions such as transcriptional changes occurring in a population of progenitors over time and participating to changes in their fate potential. This knowledge will be key in developing innovative approaches to recruit and promote the generation of selected cell types, including neuronal subtypes in pathologies
Popa, Natalia. « RAE-1, acteur et marqueur de la prolifération de cellules neurales ». Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM5061.
Neural cells express immune molecules which roles differ from those in the immune system. Classical MHC-I molecules present peptides originated from the proteic content of each cell to patrolling immune cells. However, these molecules can also have nonimmune roles. Indeed, classical MHC-I molecules participate in the establishment of synapses and synaptic plasticity. They can also interact in cis with different membrane receptors on different cell types, and modulate the receptors' membrane stability and activity. RAE-1, a member of MHC-I family, was initially described in the embryonic central nervous system. In the immune system, RAE-1 is a ligand of the activating receptor NKG2D, expressed by NK cells and by NKT, γδT and some CD8+ T lymphocytes. RAE-1 is weakly or not expressed in most adult tissues. Its expression is induced by genotoxic stress, tumoral transformation or viral infection and triggers the elimination of transformed cells by the cytotoxic immune cells which express NKG2D. I describe here the expression of RAE-1 by neural progenitor cells and its role in cell proliferation. RAE-1 expression level is highly correlated with the rate of cell proliferation and depends on the presence of epidermal growth factor (EGF). Exposition to EGF induces the colocalization of RAE-1 and phosphorylated EGF-receptor (EGFR) inside lipid rafts and endocytosed vesicles, which supports a role of RAE-1 as a partner of EGFR. RAE-1 expression is also induced in the nervous tissue in different models of CNS pathologies. In these conditions, RAE-1 could be expressed by proliferating microglia under the control of M-CSF
Tarus, Dominte. « Hydrogels multi-fonctionnels à base d'acide hyaluronique pour le contrôle de l'adhésion, la prolifération et la différentiation de cellules souches neuronales ». Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV042/document.
AbstractDamage caused to the central nervous system (CNS) is a major medical concern. As the CNS has limited ability to regenerate its damaged cells, patients can suffer from serious and long-term disabilities and impairments, which put strains on public healthcare systems. Therapies that aim to implant neural stem cells together scaffolds that mimic the extracellular matrix of the brain are being developed. Hyaluronic acid is an important component of the brain ECM. This glycosaminoglycan possesses the required biocompatibility and bioactivity for use in neural stem cells applications.We have developed HA-based hydrogels with controlled mechanical properties and cell adhesion peptide (GRGDS) densities for the in vitro study of neural precursor cells’ differentiation into neurons. The analysis of neurite outgrowth in 3-D by two-photon microscopy showed an increased outgrowth and density of neurites in the softest hydrogels (G’ = 400 Pa), combined with the existence of an optimum in neurite outgrowth as a function of ligand density in the case of hydrogels containing GRGDS. Neurite outgrowth in these hydrogels most likely involves a combination of adhesive interactions between cell-HA, cell-GRGDS moieties, and cell-secreted extracellular molecules.The enzymatic degradability of HA hydrogels was then investigated. The HA hydrogels degrade under the effect of the Hyaluronidase enzyme following a mono-exponential model, corresponding to a homogenous population of cleavable HA polymer chains. Hydrogels with higher elastic moduli have progressively lower enzymatic degradation rates. The substitution of the PEG-bis(thiol) crosslinker by an enzymatically cleavable HA-(SH)3 polymer led to a reduction in the time required for the complete degradation of the hydrogels.Finally we developed heparosan hydrogels that are devoid of biological functions and thus provide better insight into the role of HA in NSCs differentiation and neurite outgrowth. We showed that CD44 plays a measurable role in the adhesion process of MEF cells. There are alternative processes through which cells can attach to the heparosan hydrogels however the strength of these adhesions is weaker. Heparosan is a viable biomaterial for hydrogel synthesis that does not interact with the CD44 receptor, resulting in lower cellular adhesions
Montay, gruel Pierre-Gabriel. « Réponse du cerveau sain, des cellules souches neuronales et du glioblastome à une nouvelle technique de radiothérapie Flash ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS147.
Nowadays, more than 50% of cancer patients can benefit from a radiation-therapy treatment. Despite important technological advance and dose delivery precision, encephalic radiation-therapy still induces large and irreversible side effects in pediatric and adult cancer patients, justifying the urge to develop new radiation-therapy techniques. Preclinical studies on FLASH irradiation (FLASH-RT) showed a possibility to efficiently treat the tumors, without inducing drastic side-effects on the normal tissue, by increasing the dose-rate over 40 Gy/s. This so called “FLASH effect” set off an important interest in this new irradiation technology to increase the therapeutic ratio of radiation-therapy.This PhD work aimed at investigating the antitumor effect of FLASH-RT on brain tumor models along with the assessment of the ultra-high dose-rate irradiation effects on the normal brain tissue. In this context, subcutaneous, orthotopic and transgenic glioblastoma murine models were used to investigate the curative effect of FLASH irradiation delivered with an experimental LINAC available at the CHUV, and able to deliver both conventional and FLASH irradiation. Moreover, murine models of whole brain irradiation were developed to investigate the radiation-induced cellular and functional alterations at early and late time-points post-FLASH-RT. These models were used to decipher the cellular effectors involved in the brain’s radiation response including hippocampal cell-division and neuronal responses but also more physio pathological aspects as radiation-induced reactive astrogliosis and neuroinflammation. A panel of well-defined cognitive tests was also developed to investigate the radiation-induced cognitive alterations. Eventually, the physio-chemical primary events induced by FLASH-RT, and particularly the role of dioxygen consumption, were investigated to decipher the mechanisms that underlie the FLASH effect.In all investigated tumor models, FLASH-RT displayed an efficient antitumor effect at least similar to the conventional irradiation. The whole brain irradiation models showed an innocuousness of FLASH-RT on the normal brain tissue, with an absence of cognitive deficit several months after irradiation at dose-rates above 100 Gy/s, coupled with a preservation of hippocampal cell division and neuronal structure. This protection was also observed at the physio pathological level with an absence of astrogliosis and neuroinflammation. Moreover, these results were reproduced with ultra-high dose-rate X-Rays delivered with a synchrotron light source. On the mechanistic side, the reversion of the protective effects of FLASH-RT by hyperoxia, and the absence of effect of anoxia on the antitumor effect, along with a decreased ROS production underlies the primary role of dioxygen consumption during ultra-high dose-rate irradiation.Altogether, these unique results depict the possibility to increase the therapeutic index of radiation-therapy by the use of FLASH-RT. Indeed, this new irradiation technology preserves the normal brain tissue from radiation-induced toxicities by increasing the dose-rate over 100 Gy/s, while keeping an antitumor effect equivalent to the conventional dose-rate irradiation. According to these preclinical results and an upcoming clinical translation, FLASH-RT might become a major contributor to the cancer treatment by radiation therapy
Omer, Attya. « Modeling human neural development and diseases using pluripotent stem cells ». Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS589.
Microcephaly is a neurological condition, resulting in patients having a small head circumference, intellectual impairment and brain anatomical defects. A pre-requisite for achieving a better understanding of the cellular events that contribute to the striking expansion of the human cerebral cortex is to elucidate cell-division mechanisms, which likely go awry in microcephaly. Most of the mutated genes identified in microcephaly patient encode centrosomal protein, KNL1 is the only gene that encodes a kinetochore protein, it plays a central role in kinetochore assembly and function during mitosis. While the involvement of centrosome functions is well established in the etiology of microcephaly, little is known about the contribution of KNL1.In an attempt to assess the role of KNL1 in brain development and its involvement in microcephaly, we generated isogenic human embryonic stem cell (hESC) lines bearing KNL1 patient mutations using CRISPR/Cas9-mediated gene targeting. We demonstrated that the point mutation leads to KNL1 reduction in neural progenitors. Moreover, mutant neural progenitors present aneuploidy, an increase in cell death and an abrogated spindle assembly checkpoint. Mutant fibroblasts, derived from hESC, do not have a reduced expression of KNL1 and do not present any defect in cell growth or karyotype, which highlight a brain-specific phenotype.The subsequent differentiation of mutant neural progenitors into two-dimensional neural culture leads to the depletion of neural progenitors in the favor of premature differentiation. We developed a three-dimensional neural spheroids model from neural progenitors and reported a reduced size of mutant neural spheroids, compare to control. Lastly, using knockdown and rescue assays, we proved that protein level of KNL1 is responsible of the premature differentiation and the reduced size.These data suggest that KNL1 has a brain-specific function during the development. Changes in its expression might contribute to the brain phenotypic divergence that appeared during human evolution
Foerster, Philippe. « Rôle du cil primaire des cellules souches neurales dans le développement cortical murin ». Paris 6, 2013. http://www.theses.fr/2013PA066207.
Neural stem cells acquire radial glia properties during corticogenesis. They are polarized cells with a ventricular contact where a primary cilium emanates. The role of this cellular antenna during neurogenesis remains unknown. We observed that the absence of primary cilium leads to an increase in the surface of the apical domain without affecting the total size of radial glia cells, linked to an increase in mTORC1 pathway. In addition, using inducible mouse we highlight that the expansion of the apical domain area is cell autonomous. These changes in the apical domain are associated with a slightly misoriented spindle of apical progenitors, an increase in the number of basal progenitors and premature neuronal differentiation. The increase in apical surface area can be significantly reduced by treatment with rapamycin. This study highlights a new role for radial glia cells primary cilium which regulates morphogenesis and cortical neurogenesis by acting as a brake on the mTORC1 signaling pathway
Saint-Jeannet, Jean-Pierre. « Recherches sur les étapes initiales de la détermination neurale chez un embryon de vertébré : rôle des interactions cellulaires ». Toulouse 3, 1990. http://www.theses.fr/1990TOU30033.
Ghazale, Hussein. « Human and mouse spinal cord : a territory of diverse neural stem/progenitor cells, identification and functionality ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTT012/document.
Over the last 10 years, JP Hugnot’s lab has been focusing on the different pools of progenitors and stem cells found in the adult spinal cord both in human and mouse. This is important to conduct this kind of research as the spinal cord is affected by several neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and traumatic lesions for which there is no cure. In anamniotes such as Zebrafish, the spinal cord can regenerate after lesion due to endogenous progenitors/stem cells activation. So by investigating the presence and properties of such cells in mammals especially human, one could possibly harness those cells toward regeneration including neurons. We conducted RNA profiling to compare human vs mouse stem cell niche and lesioned vs non lesioned spinal cord mouse stem cell niche. This niche is particularly interesting as in anamniotes, radial ependymoglia cells located in this region are multipotent and can generate new motoneurons after lesion. And similar, albeit non identical, cells are present in mouse. In mammals, after lesion, these niche cells actively proliferate and migrate to generate mainly astrocytic cells and few oligodendrocytes which participate to the glial scar and regeneration by providing neurotrophic factor such as CNTF, HGF, and IGF-1. This niche contains at least 5 cell types and here a new dorsal cell type expressing Msx1 and Id4 transcription factors was identified. These results indicated that the adult spinal cord niche in mouse and human is a mosaic of cells with different developmental origin and maintaining high levels of neural developmental genes. Glial-neuronal interactions supporting and keeping neurons intact can be influence neurodegenerative diseases. One of these glial cells is the satellite oligodendrocyte or so called perineuronal satellite cells (PNCs). PNCs are tightly associated to the soma of large neurons and widely spread in the grey matter of the CNS both cortex and spinal cord. However the cellular properties and functional roles of these unmyelinating oligodendrocytes are not yet discovered. In this study, nestin-GFP positive cells are associated to neurons immunostained for neuronal nuclear antigen in both cortex and spinal cord. We identified PNCs as CNPase positive cells that are neither oligodendrocyte progenitor cells (PDGFRa) nor myelinating oligodendrocytes (MBP). These data suggest that PNCs might affect neuronal survival as well as the myelination process in demyelinating conditions. Also it could be implicated in neurodegenerative diseases such as multiple sclerosis and amyotrophic lateral sclerosis due to their interaction with motor neurons
Lemkine, Gregory F. « Transfert de gène in vivo à l'aide de la polyéthylènimine : application à l'étude des cellules souches neurales ». Paris, Muséum national d'histoire naturelle, 2005. http://www.theses.fr/2002MNHN0026.
The subventricular zone (SVZ) of the adult mammalian brain harbors the neural stem cell population with potential neural regeneration and repair capacity. We describe a nonviral technique to preferentially transfect in vivo the adult neural stem cell population and its immediate progeny based on intraventricular injection of polyethyelenimines (PEl)/DNA complexes. Linear PEI is proving to be efficient, non-toxic and versatile agent for in vivo gene delivery by a number of routes. The transfected population was identified by cellular and ultra-structural evidence showing their proliferating status and expression of the specific markers GFAP and nestin. Stable activation of the lacZ reporter by cre-recombinase transfection in R26R mice demonstrated survival and migration of stem cell derivatives three months after injection. Apoptosis is thought to be the most common fate of the stem cell progeny. Introduction of a neuroprotective, antiapoptotic gene Bcl-XL can augment the number and change the histological profile of transgene-expressing cells in the SVZ. This opens up the possibility of enhancing in situ the regenerative potential of this population of cells. As well as confirming the importance of apoptosis in neural stem cell physiology, our results pave the way for further investigations of this phenomenon. This method thus provides selective targeting of the stem cell population and should allow an in-depth understanding of their biology. We thus investigated the effects of thyroid hormones on proliferation and apoptosis of stem cells in the subventricular zone as well as on migration of transgene-tagged neuroblasts out of the stem cell niche. Hypothyroidism significantly reduced all three of these processes, inhibiting generation of new cells. These data suggest that, besides the well established multiple roles of TH in early neurogenesis, TH is an essential component of the endocrine environment that activates neural stem cell growth, migration, and apoptosis. Further, the results demonstrate that the negative effects of TH on mitotic capacity have repercussion on the number of cells migrating through the RMS. Endocrine factors such as TH could be key factors to reveal regenerative potential of endogenous or grafted stem cells
Grandbarbe, Luc. « Rôle de la voie de signalisation Notch dans la différenciation des cellules souches neurales ». Université Louis Pasteur (Strasbourg) (1971-2008), 2002. http://www.theses.fr/2002STR13050.
The central nervous system comprises three major cell types: neurons, oligodendrocytes and astrocytes. All these cell-types derive from a common multipotential precursor cell, capable of self-renewing, and which is referred to as a neural stem cell. To elucidate the role of Notch signaling on the generation of neurons and glia, we made use of the in vitro neurosphère system which is clonally derived from neural stem cells through the selective action of EGF. Neurospheres prepared from Dll1lacZ mutant embryos display an increase of neurons at the expense of both oligodendrocytes and astrocytes. This mutant phenotype could be rescued when Dll1lacZ spheres were grown and/or differentiated in the presence of WT neurospheres conditioned medium. Time-dependant activation of Notch by soluble forms of ligands indicates that Notch acts in two steps. Initially, it acts on the cell fate choice by negatively regulating the neuronal fate and promoting the glial cell fate. In a second step, Notch promotes differentiation of astrocytes and inhibits differentiation of both neurons and oligodendrocytes
Nepote, Virginie. « Mécanismes moléculaires de la détermination catécholaminergique des cellules souches du sytème nerveux périphérique et central ». Paris 7, 2001. http://www.theses.fr/2001PA077224.
Segura, Stéphanie. « Contrôle des cellules-souches neurales de Rat adulte par la leptine ; application chez le Porc adulte ». Aix-Marseille 3, 2009. http://www.theses.fr/2009AIX30026.
The dorsal vagal complex (DVC) is a cerebral integrative center for autonomic functions, including the satiety reflex. The DVC of adult rat has been established by my host laboratory as a novel site of adult neurogenesis endowed with neural stem cells. I characterized in vitro a novel action of the anorexigenic hormone leptin on neural stem cells of adult rat DVC and subventricular zone (SVZ). Leptin inhibits the growth of neurospheres from DVC and SVZ, wherein I have shown ObR receptor expression by RT-PCR. This antiproliferative leptin action, as analyzed in SVZ neurospheres, involves apoptosis triggering via ERK1/2 pathway activation and cyclin D1 induction, the causal role of which I have shown using a RNAi approach. In the context of a preclinical research application aiming at improving post-injury repair of peripheral nerve, I realised the first characterization of neural stem cells from adult Pig SVZ by neurosphere culture and RT-PCR of phenotype markers. This study opens new cues for Autonomic physiology and neural stem cell biology
Cantarella, Cristina. « Promouvoir la mobilisation des cellules souches neurales adultes pour la réparation de lésions demyélinisantes : effet de l'environnement et de l'EGF ». Aix-Marseille 2, 2008. http://www.theses.fr/2008AIX22035.
The identification of neural stem cells in the adult rodent and human central nervous system opens new perspectives for self-repair of brain damage. In the adult subventricular zone (SVZ), these cells proliferate and generate progenitors that migrate along the rostral migratory stream to the olfactory bulb, where they differentiate into interneurons. These cells can also be recruited spontaneously to damaged brain areas to replace lost cells, including oligodendrocytes in demyelinated lesions. However, this process only leads to partial recovery. My Ph. D. Research has focused on the identification of conditions and factors that could enhance the self-repair capacity of endogenous SVZ cells in demyelinating lesions in the adult mouse. In a first study, I have contributed to show that exercise and environmental enrichment (EE), known to induce regional increases in neurotrophin levels in the rodent brain, promote recruitment of SVZ cells and favour recovery in demyelination models. EE also favored the oligodendrocyte fate of SVZ-recruited cells in the experimental autoimmune encephalomyelitis lesions. In a second study, I have focused on epidermal growth factor (EGF) influences on SVZ cell participation to brain repair in the context of demyelinated lesions. Indeed, previous studies have suggested that EGF is able to stimulate proliferation, migration and glial differentiation of SVZ progenitors. We induced a focal demyelinated lesion in the corpus callosum by lysolecithin injection and showed that intranasal heparinbinding epidermal growth factor (HB-EGF) administration induces a significant increase in SVZ cell proliferation together with a stronger SVZ cell mobilization towards the lesions. Besides, HB-EGF causes a shift of SVZ-derived cell differentiation towards the astrocytic lineage. These results suggest that SVZ cell proliferation and migration can be stimulated by non invasive approaches that could be part of future strategies to promote cell replacement from endogenous SVZ stem / progenitor cells, notably in demyelinated lesions
Honoré, Axel. « Effet des Cellules Gliales Olfactives issues des Bulbes Olfactifs sur les cellules souches épendymaires et leur progénie après une lésion médullaire ». Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR060/document.
The spinal cord injuries (SCI) lead to the damages of the spinal cord or nerves and often cause permanent changes in body functions leading to the death. Cell therapies have raised great hope for regenerative medicine. Clinical data showed that the olfactory ensheathing cells (OECs) enhanced functional recovery after SCI and could be a very attractive therapeutic approach. Moreover, the discovery of a new endogenous resident stem cell population, lining the central canal of the spinal cord, named ependymal stem cells, represents a new hope for the therapy. This thesis analyzed the role of OECs transplantation, on the behaviour of ependymal stem cells since these cells, together with astrocytes and pericytes significantly contribute to the recovery of SCI. The use of the mouse model hFoxJ1-CreERT2::YFP (allowing to specifically follow the ependymal stem cells ant their progeny) showed that OECs increased in vitro the self-renewal potential of spinal cord stem cells and modified their differentiation pathway towards a neural type. In vivo, OECs transplantation significantly increases the proliferation of ependymal cells and their differenciation into hypo-reactive astrocytes leading to the formation of a beneficial environment to neuronal survival and the neurogenesis establishment. Our results also showed for the first time that OECs transplantation after SCI allows the generation of new neurons by non-ependymal cell-derived progenitors. These results represent a new hope in the establishment of therapeutic strategies for the treatment of SCI in humans
Dirian, Lara. « Embryonic Origin of Adult Neural Stem Cells in the Zebrafish Pallium ». Thesis, Paris 11, 2014. http://www.theses.fr/2014PA11T061/document.
Adult neural stem cells (aNSCs) are defined by their self-Renewal and multipotency, which allow them to generate both neurons and glial cells in the adult brain. Contrary to mammals, the zebrafish brain maintains numerous neurogenic zones in the adult, among which the most characterized is the pallial ventricular zone. It is composed of radial glial cells serving as aNSCs. Which embryonic neural progenitors are at the origin of these aNSCs is still unknown. This work aims to determine the relative contributions of two embryonic neural progenitor populations, the «proneural clusters» (involved in embryonic neurogenesis) and the « progenitor pools » (characterized by a delayed neurogenesis), to the formation of aNSCs in the zebrafish pallium. First, using genetic lineage tracing techniques, we were able to identify the embryonic neural progenitor population at the origin of a subpopulation of aNSCs located in the dorso-Medial part of the pallium. The her4:ERT2CreERT2 transgenic driver line, combined with pharmacological treatments inhibiting the Notch signalling pathway, allowed showing that neural progenitors giving rise to dorso-Medial pallial aNSCs express the « Enhancer of split » her4 gene, specifically expressed in « proneural clusters » from very early stages of development. As a second step, clonal analyses as well as spatially controlled recombinations by laser highlighted that aNSCs of the zebrafish lateral pallium do not derive from her4-Positive embryonic progenitors maintained by the Notch pathway, but from a restricted population of neuroepithelial cells located in the embryonic telencephalic roof plate. These cells display « progenitor pool » specific features, as for instance the expression of non-Canonical her genes (independent of Notch signalling) such as her6 and her9, the expression of components of signalling pathways such as Wnt, BMP, FGF, and a late neurogenesis onset. These progenitors progressively generate, from juvenile stages, the vast majority of the aNSCs of the lateral pallium. Most interestingly, a small population of these neuroepithelial cells persists in the postero-Lateral pallium at adult stage and keeps generating de novo aNSCs of this brain region. In addition to identifying the origin of pallial aNSCs in the zebrafish, this study also delivers information on the progressive maturation steps that embryonic progenitors undergo to generate aNSCs, and highlights similarities and differencies existing between the dorso-Medial and lateral progenitors. Finally, this work also permits tracing the neurons generated by stem cells at different stages. This reveals for the first time the progressive formation of the different zebrafish pallial compartements, and allows appreciating their homologies with the mouse pallial regions
Mathieux, Elodie. « Propriétés immunosuppressives des cellules souches et étude de la réponse humorale en xénotransplantation intracérébrale ». Nantes, 2013. https://archive.bu.univ-nantes.fr/pollux/show/show?id=30dcfe9d-43d0-4d68-9e74-616bfc29bec3.
The intracerebral xenotransplantation of neural cells is a promising therapeutic strategy for neurodegenerative disorders such as the Parkinson's disease. However, this approach is strongly limited by a strong immune response that leads to the rejection of neural xenograft. The first part of my thesis aims at deciphering the immunosuppressive properties of multipotent stem cells and their potential utility for intracerebral transplantation. We show that the co-transplantation of rat mesenchymal stem cells with porcine neuroblasts into the rat striatum inhibits the levels of inflammatory factors, and prolongs the survival of xenotransplants up to 120 days. Neural stem/progenitor cells also have the ability to inhibit T lymphocyte proliferation, but their effects are mainly mediated by the heme oxygenase 1. Interestingly, we recently found that neural stem cells derived from induced pluripotent stem cells (iPSC) are also able to inhibit the proliferation of human mononuclear cells. The second part of my thesis aims at determining whether the host humoral response is implicated in the rejection of porcine neurons following their implantation into the rat striatum. High levels of elicited IgG directed against porcine neurons are present in the rejecting graft. These IgG are also found in the sera of host animals but predominantly, after graft rejection. The long-survival of porcine neurons in the brain of immunoglobulin-deficient rats indicates that the humoral and not only the cellular immune response should be controlled in case of intracerebral transplantation
Hadoux, Julien. « Modélisation des néoplasies endocriniennes multiples de type II par les cellules souches pluripotentes induites porteuses de mutations germinales du gène RET ». Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS389/document.
Induced pluripotent stem cell (iPSC) offer major perspectives in disease modelling and, in the oncology field, can be used for modelling cancer predisposition syndromes. We generated IPSC lines from somatic cells of patients with multiple endocrine neoplasia type 2 (MEN2) who harboured germline mutations in the RET gene: RETC620R, RETC634Y et RETM918T. We have also generated an isogenic RETY634C iPSC control line by genome engineering using CRSPR/Cas9-mediated method to "correct” C634Y mutation. All iPSC lines exhibited all markers of pluripotency with a normal karyotype and expressed Ret. A thorough histological study of teratomas from these iPSC highlighted the development of C cells and Chromogranin A-expressing neuroendocrine cells within them but without C-cell hyperplasia, medullary thyroid carcinoma or neuroendocrine tumours reminiscent of MEN2 phenotype. Comparative gene expression analysis revealed an activation of the EGR1 transcriptional network, at the pluripotent stem cell stage which could be one of the molecular effector of the phenotype. Neural crest stem cell (NCSC), the cell of origin of some of the tumoral features of MEN2, could be differentiated in vitro from all our RET-mutated iPSC lines effectively. Gene expression analysis revealed an activation of cell invasion program in RETC634Y and RETM918T–mutated NCSC and a deregulation of integrin network causing a strong deregulation of cell adhesion which was confirmed with increased migration capabilities in vitro. Thus, the generation of the first RET-mutated iPSCs allowed the identification of signalling pathways potentially implicated in the pathophysiology of MEN2 and constitute a first step in modelling these tumours in vitro
Seminatore, Christine. « Transplantation de dérivés neuraux de cellules souches embryonnaires humaines dans un modèle de lésion cérébrale ischémique ». Paris 6, 2009. http://www.theses.fr/2009PA066554.
Bonnamain, Virginie. « Interactions cellules souches/progénitrices neurales – lymphocytes T : étude in vitro et perspectives pour la transplantation ». Nantes, 2009. http://www.theses.fr/2009NANT36VS.
Despite its status of immune privileged organ, the central nervous system (CNS) maintains a close bidirectional communication with the immune system. This parameter must be taken into account to optimize the therapeutic strategies aiming at restoring the neuronal loss in case of lesions or degenerative diseases in the CNS. Indeed, in the absence of immunosuppression, pig neural cells xenografted into the CNS are systematically rejected, this rejection being primarily mediated by T lymphocytes (TL). In this context, neural stem/progenitor cells (NSPC) described as having reduced immunogenicity and a potent suppressive effect on T cell responses appear as a suitable alternative cell source to fetal neuroblasts. The prolonged survival of xenografts and the low T cell infiltration following the transplantation of NSPC in the brain of non-immunosuppressed rats prompted us to study the in vitro interactions between NSPC and TL. We showed by co-culture experiments that pig and rat NSPC inhibit the proliferation of rat TL through the release of soluble factors. The mechanisms triggering the immunoregulatory effects of porcine NSPC remain to be determined, but we clearly demonstrated a role for the heme oxygenase 1 (HO-1) in the suppressive activity of rat NSPC. Interestingly, we also found that Interleukin-2 (IL-2), a proinflammatory cytokine secreted by activated TL, directs the in vitro fate of NSPC rat towards a neuronal phenotype. These results confirm the bidirectional communication between the CNS and the immune system, and highlight the interest of NSPC for cell transplantation
Radreau, Félicie. « Cellules souches embryonnaires et neurales humaines : quand la PrP et l'APP "s'en mêlent" ou "s’emmêlent" ». Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT045/document.
The cellular Prion Protein (PrPc) is a ubiquitary protein mainly expressed in the central nervous system. It is particularly known for its conformational conversion in PrPSc in Prion diseases, which are proteinopathies such as Alzheimer’s disease (AD). AD is associated with extracellular deposits of aggregated beta-amyloid peptides (Aβ) derived from successive β- and the γ-secretase cleavages of the amyloid precursor protein (APP) expressed by neurons. PrPc and APP share some common functions and proteolytic pathways (α- or β-secretase), involving them in proliferation, differentiation, synaptogenesis and cellular survival. PrPc is involved in the regulation of proliferation and differentiation of many stem cells: adult neural (NSC), hematopoietic (HSC) and human embryonic (hESC). Several publications also show that PrP downregulates the cleavage of APP in Aβ and positively regulates the cleavage of APP in sAPPα suggesting an anti-amyloïdogenic role of PrPc. PrP could also act as a receptor of Aβ at the neuronal surface inducing LTP inhibition and synaptic alteration. In this context, the specific objectives of my thesis were:- Study of the expression of PrP, APP and its cleavage residues during neural induction of hESC in NSC and neuronal differentiation.- Impact of the modulation of PrP expression on APP cleavages as well as on stem cells properties (survival, proliferation, differentiation). 1. Neural induction of hESC in NSCFor this project, we have used Human Embryonic Stem Cells (hESC) for which the laboratory has an authorization from the “Agence de la Biomédecine”.For the neural induction, we have tested two protocols, the first one allows the obtention of neurospheres in suspension and then figures of “rosettes” composed of NSC, and a “monolayer” protocol that mimics the beginning of corticogenesis. An optimization of these protocols has been necessary (starting cell density, cell fixation methods to improve PrP detection). We have also determined the best conditions to analyze the expression of PrP, APP and its derived peptides (Aß, sAPPα/β). 2. Differentiation of NSCNSC derived from hESC were amplified and differentiated into neurons and/or astrocytes. Cells were characterized in particular by immunofluorescence and RT-qPCR for the expression of the major astrocytic (GFAP) and neuronal markers (BIII-tubulin, doublecortin, synaptophysin) and the progressive decrease of NSC markers. Again we have determined the best conditions for cell density and kinetic time points for our analysis.3. Modulation of PrPC expression We have used lentiviral vectors allowing the expression of an anti-PrP shRNA, human PrP and respective controls. To achieve this task, lentiviral transductions of hESC and NSC were optimized: cell density, size of the seeding culture wells or MOI of lentivirus. Finaly, samples collected allowed us to evaluate the impact of PrPc modulation on the APP cleavages as well as on stem cells properties (survival, proliferation, differentiation)
Sabourin, Jean-Charles. « Les cellules souches neurales médullaires : Organisation de la niche et rôle de la molécule d’adhérence OCAM dans le contrôle de leurs propriétés ». Montpellier 2, 2009. http://www.theses.fr/2009MON20143.
Domenichini, Florence. « Neurogenèse adulte et déficience intellectuelle : analyse du rôle de la kinase PAK3 dans deux modèles murins représentatifs de la pathologie ». Thesis, Paris 11, 2014. http://www.theses.fr/2014PA11T038.
The group I p21-activated kinases (PAK) are involved in many cellular processes such as proliferation, cell movement, adhesion and apoptosis. These kinases are effectors of Rho GTPases Rac1 and Cdc42, and participate in the regulation of the actin cytoskeleton. Both neuronal kinase PAK1 and PAK3, which exhibit high sequence identities, regulate the actin cytoskeleton, thereby controlling the dynamics of dendritic spines and synaptic plasticity. Mutations of the X-linked pak3 are responsible for intellectual disability (ID) in humans, and the molecular and cellular mechanisms associated with cognitive defects are poorly described. It was shown that PAK3 participates in the proneural pathway during early Xenopus embryogenic development, by promoting cell cycle exit and neuronal differentiation of neural precursors. However, the role of PAK3 in the adult neurogenesis has not been studied in mammals. It is now generally accepted that neurogenesis persists during human adulthood and is involved in learning and memory. We are therefore interested in the involvement of PAK3 in the regulation of adult neurogenesis, on the assumption that defects in neurogenesis may be responsible, at least in part, for cognitive defects in ID patients.We showed that PAK3 is not expressed in proliferative neural stem/progenitor cells but its expression increased significantly upon growth factor removal, suggesting a role in adult neurogenesis. We showed that the invalidation of pak3 gene causes an increase in the frequency and in size of primary neurospheres. However Pak3 invalidation does not affect the size of the stem cell reservoir nor the NCS cardinal properties (pluripotency, self-renewal and proliferation). However, the pak3- progenitor cells continue their proliferation in culture conditions normally inducing differentiation, suggesting a defect in cell cycle exit. We then asked whether pak3 ID mutations affect adult neurogenesis. We created a knock-in model expressing the pak3-R67C mutation responsible in humans for a severe form of intellectual impairment. We observed in the knock-in mice, a significant decrease in the number of newborn cells in both neurogenic areas of the brain (the subventricular zone inforebrain, and the dentate gyrus of the hippocampus) and an increase in the proportion of immature newborn neurons. These data suggest that the R67C mutation does not induce a loss of function of the kinase but a change of a function dependent on preferential activation by the Rac1 GTPase.In conclusion, we show that PAK3 play an important role in the regulation of adult neurogenesis in mammals by controlling the cell cycle exit of neural progenitors. The R67C ID mutation impacts both newborn cell proliferation and their maturation. Taken together, these data suggest that defects in adult neurogenesis caused by ID mutations in the pak3 gene may be involved in some cognitive dysfunctions