A lateral belt of cortical LGN and NuMA guides mitotic spindle movements and planar division in neuroepithelial cells

Knockdown or mislocalization of LGN complex components disrupts the stereotypic biphasic spindle movements regulating planar cell division and neuroepithelial structure in chick embryos

Recent developments of marine ingredients for food and nutraceutical applications: a review.

Remerciements à l'éditeur pour son accord de diffusion. L'article original est aussi accessible sur le site de l'éditeur à l'adresse : http://www.halieutique.org/23201b.htmlInternational audienceIn a global context of marine biological resource overexploitation, a better upgrading of fish and shellfish biomass is a challenge for the 21st century. One of the main and promising issues will be the production of marine bio-ingredients using enzymatic hydrolysis. This paper presents the key steps in the production of enzymatic hydrolysates, such as (i) enzymatic treatment for the bioconversion of solid discards, and more particularly, use of proteases, (ii) quantification of the proteolysis extend and procedures of quality-control and (iii) identification of biological activity, using in vitro and in vivo methods. In the last part, examples of marine, commercially available functional foods or nutraceutical ingredients carrying bioactive properties are presented in order to demonstrate the interest of biotechnological exploitation of marine resources

Understanding the role of miR-33 in brain lipid metabolism: implications for Alzheimer's disease

International audienceBecause of its incidence and devastating consequences, Alzheimer’s disease (AD) has attracted much research attention in the last decades. Intensive work led to the identification of a number of cellular and molecular pathophysiologic mechanisms including Tau alterations, β-amyloid deposition, lipid homeostasis dysregulation, excitotoxicity, neuroinflammation or autophagy defects (Di Paolo and Kim, 2011; Ittner and Gotz, 2011; Heppner et al., 2015; Menzies et al., 2015; Wang and Mandelkow, 2015). Despite of the efforts, how these different pathways interact and contribute to disease pathogenesis remains poorly understood. Nonetheless, the presence of Aβ plaques, formed by the sequential cleavage of the amyloid precursor protein (APP), is a prominent neuropathologic feature of the disease and is still thought to be central to AD development (Nhan et al., 2015)

Rôle du complexe Gai/LGN/NuMA dans la régulation de l'orientation du fuseau mitotique au cours de la neurogenèse chez les vertébrés

Tous les neurones et les cellules gliales produits au cours du développement du système nerveux des vertébrés dérivent d un réservoir initial de cellules progénitrices organisées en une monocouche cellulaire pseudostratifiée appelée neuroépithelium (NE). Les modes de division de ces cellules doivent être finement contrôlés afin de permettre l équilibre entre le maintien de cette réserve de progéniteurs neuraux mitotique et l engagement de ces progéniteurs vers une voie de différenciation. De nombreux travaux, réalisés pour la plupart dans le cortex cérébral en développement, ont conduit à proposer différents modèles corrélant les modes de divisions des progéniteurs neuraux et l orientation du fuseau mitotique. Au cours de ma thèse, je me suis intéressée à la régulation moléculaire de l orientation du fuseau mitotique des progéniteurs neuraux chez les vertébrés, ainsi qu à l importance développementale de cette régulation. Pour cela, nous avons utilisé la moelle épinière d embryon de poulet comme système modèle. Nous avons montré que LGN, ainsi que ses interacteurs moléculaires Gai et NuMA, sont exprimés au cours du développement par les progéniteurs neuraux ; dans ces progéniteurs en division, Gai localisé de façon uniforme à la membrane plasmique recrute LGN au cortex cellulaire, et en retour, LGN recrute NuMA sous forme d un anneau sous la membrane latérale. La dérégulation de ces protéines par gain et/ou perte de fonction entraîne une perturbation dans l orientation du fuseau mitotique, au cours des divisions symétriques prolifératives des progéniteurs neuraux. Cette perturbation conduit à la sortie prématurée d une des deux cellules filles du NE, qui migre dans la zone du manteau et conserve une identité de progéniteur neural prolifératif. Ainsi, nos résultats dans la moelle épinière précoce de poulet contredisent la prédiction faite par le modèle cortical, qui propose que l axe de division joue un rôle instructif dans l identité des cellules filles. Nos travaux révèlent donc le rôle central du complexe Gai/LGN/NuMA dans la régulation de l orientation du fuseau mitotique afin de maintenir la descendance de divisions symétriques prolifératives dans le NE.All neurons and glial cells that are produced during the development of the vertebrate nervous system derive from an initial reservoir of progenitors which constitute the monolayered, pseudostratified neuroepithelium (NE).The mode of division of these progenitors to be precisely controlled in order to regulate the balance between proliferation and differentiation. Several studies performed mostly in developing cerebral cortex lead to propose different models that link modes of neural progenitor divisions and mitotic spindle orientation. During my thesis, I studied the molecular regulation of mitotic spindle orientation in vertebrate neural progenitors and its developmental implication. To do so, we have used the neural tube of the chick embryo as a model ystem. We have shown that LGN, and its interactors Gai and NuMA, are expressed by neural progenitors during development; in these dividing rogenitors, Gai, located uniformly at the plasma membrane, recruits LGN at cell cortex, and in return, LGN recruits NuMA in a ring around the lateral cell cortex. Deregulation of these proteins by gain- or loss-of-function leads to perturbation in mitotic spindle orientation, during proliferative symmetric divisions of neural progenitors. This perturbation leads to one daughter cell exiting the NE prematurely and proliferating aberrantly in the mantle zone. Hence, these results in the early chick spinal cord are opposed to the cortical model, that links plane of division and cell fate. Thus, this study reveals that the key role of the Gai/LGN/NuMA complex in the regulation of mitotic spindle orientation is to maintain the progeny of proliferative symmetric divisions in the NE.AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

Deficits in Social Behavior Precede Cognitive Decline in Middle-Aged Mice

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Social isolation and enrichment induce unique microRNA signatures in the prefrontal cortex and behavioral changes in mice

International audienceAn extensive body of evidence supports the notion that exposure to an enriched/impoverished environment alters brain functions via epigenetic changes. However, how specific modifications of social environment modulate brain functions remains poorly understood. To address this issue, we investigate the molecular and behavioral consequences of briefly manipulating social settings in young and middle-aged wild-type mice. We observe that, modifications of the social context, only affect the performance in socially related tasks. Social enrichment increases sociability whereas isolation leads to the opposite effect. Our work also pointed out specific miRNA signatures associated to each social environment. These miRNA alterations are reversible and found selectively in the medial prefrontal cortex. Finally, we show that miRNA modifications linked to social enrichment or isolation might target rather different intracellular pathways. Together, these observations suggest that the prefrontal cortex may be a key brain area integrating social information via the modification of precise miRNA networks

Processing of information from the parafascicular nucleus of the thalamus through the basal ganglia

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Processing of information from the parafascicular nucleus of the thalamus through the basal ganglia

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