Influence of GENE-X1 promotor methylation on the susceptibility to develop PTSD

Traumatic events are a prevalent and high risk factor to develop psychiatric disorder like post traumatic stress disorder (PTSD). However, people differ strictly in the susceptibility or resilience to develop such disorders. The exact underlying mechanisms are unknown, but epigenetic mechanisms, such as DNA methylation might play a major role. This was demonstrated by a recent study from our group, who showed significant hypomethylation of GENE-X in the blood of subjects with PTSD. To study brain methylation patterns, the protein expression in PTSD related brain areas of social defeat (SD) mice was compared to control mice (CTR). Expression was visualized by immunohistochemistry (biotin, ABC-kit, DAB), on human tissue immunofluorescence (biotin, streptavidin) was conducted too. The GENE-X antibody was demonstrated to be specific, since the signal was reduced when performing a pre-incubation with the blocking peptide. Double labelled fluorescence showed GENE-X expression in human temporal neocortex in the cytoplasm and nucleus of neurons, and to a lower extend in astrocytic cytoplasm The staining on SD and CTR mice tissue gave no results about expression sites. This problem was expected to be caused by incorrect fixation of the brain tissue. To conclude, indirect immunohistochemistry allowed visualization of specific GENE-X expression in the human brain. However, the research on the human tissue is not related to stress. Therefore, further research on SD versus CTR material is needed, to prove a causal link between GENE-X hypomethylation in the brain and increased susceptibility to develop PTSD

Myoclonin1/EFHC1 in cell division, neuroblast migration, synapse/dendrite formation in juvenile myoclonic epilepsy

peer reviewe

Importin-8 Modulates Division of Apical Progenitors, Dendritogenesis and Tangential Migration During Development of Mouse Cortex

The building of the brain is a multistep process that requires the coordinate expression of thousands of genes and an intense nucleocytoplasmic transport of RNA and proteins. This transport is mediated by karyopherins that comprise importins and exportins. Here, we investigated the role of the ß-importin, importin-8 (IPO8) during mouse cerebral corticogenesis as several of its cargoes have been shown to be essential during this process. First, we showed that Ipo8 mRNA is expressed in mouse brain at various embryonic ages with a clear signal in the sub-ventricular/ventricular zone (SVZ/VZ), the cerebral cortical plate (CP) and the ganglionic eminences. We found that acute knockdown of IPO8 in cortical progenitors reduced both their proliferation and cell cycle exit leading to the increase in apical progenitor pool without influencing the number of basal progenitors (BPs). Projection neurons ultimately reached their appropriate cerebral cortical layer, but their dendritogenesis was specifically affected, resulting in neurons with reduced dendrite complexity. IPO8 knockdown also slowed the migration of cortical interneurons. Together, our data demonstrate that IPO8 contribute to the coordination of several critical steps of cerebral cortex development. These results suggest that the impairment of IPO8 function might be associated with some diseases of neuronal migration defects

Resilience Against Traumatic Stress: Current Developments and Future Directions

Given the high prevalence of stress-related mental disorders, their impact on person, family, and society and the paucity of treatment options for most of these disorders, there is currently a pressing need for innovative approaches to deal with these issues and enhance well-being. One approach which has received increasing attention over the last decade is to shift our scientific and clinical focus from risk factors for psychopathology to factors promoting resilience and mental well-being. In order to summarize and evaluate the current state of scientific affairs on the biological basis of resilience, we provide an overview of the literature on animal and human studies of resilience. Because resilience can only truly be operationalized through longitudinal data collection and analyses, we focus primarily on longitudinal studies. This review shows that the concept of resilience is currently being operationalized, measured and even defined in widely variable manners, both within animal and human studies. We further provide an overview of existing and new strategies that could help promote resilience and which are proposed to be implemented more often in clinical situations. Finally, we summarize the challenges the field is facing and provide recommendations for future research

In vitro modeling of the neurobiological effects of glucocorticoids: A review

Hypothalamic-pituitary adrenal (HPA)axis dysregulation has long been implicated in stress-related disorders such as major depression and post-traumatic stress disorder. Glucocorticoids (GCs) are released from the adrenal glands as a result of HPA-axis activation. The release of GCs is implicated with several neurobiological changes that are associated with negative consequences of chronic stress and the onset and course of psychiatric disorders. Investigating the underlying neurobiological effects of GCs may help to better understand the pathophysiology of stress-related psychiatric disorders. GCs impact a plethora of neuronal processes at the genetic, epigenetic, cellular, and molecular levels. Given the scarcity and difficulty in accessing human brain samples, 2D and 3D in vitro neuronal cultures are becoming increasingly useful in studying GC effects. In this review, we provide an overview of in vitro studies investigating the effects of GCs on key neuronal processes such as proliferation and survival of progenitor cells, neurogenesis, synaptic plasticity, neuronal activity, inflammation, genetic vulnerability, and epigenetic alterations. Finally, we discuss the challenges in the field and offer suggestions for improving the use of in vitro models to investigate GC effects

Exploring subtle land use and land cover changes: a framework for future landscape studies

UMR AMAP, équipe 3International audienceLand cover and land use changes can have a wide variety of ecological effects, including significant impacts on soils and water quality. In rural areas, even subtle changes in farming practices can affect landscape features and functions, and consequently the environment. Fine-scale analyses have to be performed to better understand the land cover change processes. At the same time, models of land cover change have to be developed in order to anticipate where changes are more likely to occur next. Such predictive information is essential to propose and implement sustainable and efficient environmental policies. Future landscape studies can provide a framework to forecast how land use and land cover changes is likely to react differently to subtle changes. This paper proposes a four step framework to forecast landscape futures at fine scales by coupling scenarios and landscape modelling approaches. This methodology has been tested on two contrasting agricultural landscapes located in the United States and France, to identify possible landscape changes based on forecasting and backcasting agriculture intensification scenarios. Both examples demonstrate that relatively subtle land cover and land use changes can have a large impact on future landscapes. Results highlight how such subtle changes have to be considered in term of quantity, location, and frequency of land use and land cover to appropriately assess environmental impacts on water pollution (France) and soil erosion (US). The results highlight opportunities for improvements in landscape modelling

Characterization of EFHC1, a protein mutated in juvenile myoclonic epilepsy

L’épilepsie myoclonique juvénile (EMJ) est un syndrome épileptique très répandu qui appartient aux épilepsies idiopathiques généralisées. Il se caractérise par des secousses myocloniques et des crises tonico-cloniques débutant pendant l’adolescence, entre 12 et 18 ans. Son étiologie est génétique et impliquerait l’interaction de plusieurs gènes. Des études de liaisons géniques ont permis l’indentification, dans un gène localisé en 6p12, de cinq mutations faux-sens co-ségrégées avec le phénotype de EMJ. Ce gène code une nouvelle protéine, dénommée EFHC1, comportant un motif EF-hand, domaine potentiel de liaison au calcium et trois domaines DM10, de fonction inconnue. L'objectif de notre travail consiste à étudier les propriétés biochimiques et fonctionnelles d'EFHC1. Nous avons d’abord étudié la localisation subcellulaire d’EFHC1 dans différentes lignées cellulaires (HEK-293, HeLa et COS-7) au moyen de deux approches complèmentaires. D’une part nous avons surexprimé la protéine couplée à l’EGFP, un marqueur fluorescent permettant se visualisation et d’autre part, nous avons étudié la localisation de la protéine endogène au moyen d’un anticorps spécifique. Dans les cellules en mitose, EFHC1 montre clairement une association avec le fuseau mitotique, spécialement au niveau des pôles et du corpuscule de Fleming pendant la cytokinèse. EFHC1 co-localise également avec le centrosome dans les cellules en interphase et en mitose. Dans le but de déterminer la région d'EFHC1 impliquée dans l’association au fuseau mitotique, nous avons effectué des analyses au moyen de différentes formes tronquées de la protéine couplées à l’EGFP. Les résultats indiquent que l’extrémité N-terminale d'EFHC1, contenant les 45 premiers acides aminés de la protéine est cruciale pour l’adressage au fuseau mitotique. Nous avons démontré, au moyen d’expériences d’immunoprécipitations et de co-sédimentation de microtubules, une association directe d’EFHC1 avec l’α-tubuline, composant des microtubules. Cette interaction est médiée par un nouveau domaine d’association aux microtubules situé au niveau de l’extrémité N-terminale de la protéine, entre les acides aminés 1 et 45. D’autre part, nous avons mis en évidence un rôle important d’EFHC1 dans la régulation de la division cellulaire. En effet, la surexpression d’une forme tronquée d’EFHC1 ne contenant que les 45 premiers acides aminés de la protéine, agissant comme un dominant-négatif, ainsi que l’inhibition d’expression d’EFHC1 par expression de shRNAs induit de façon significative des fuseaux mitotiques anormaux (fuseaux unipolaires, anomalies de condensation des chromosomes au niveau de la plaque équatoriale pendant la métaphase). De plus, nous avons observé que les cellules invalidées en EFHC1 présentaient un défaut de progression mitotique résultant du blocage des cellules en prométaphase anormale, conduisant à une augmentation significative de l’index mitotique (% de cellules en mitose) et à de l’apoptose. Enfin, nous avons démontré un rôle d’EFHC1 dans la corticogenèse cérébrale. En effet, l’invalidation d’EFHC1 (shRNAs et dominants-négatifs) dans le néocortex de rat en développement au moyen des techniques d’électroporations ex vivo et in utero conduit à un défaut de migration neuronale radiaire. Nous avons montré que celui-ci résultait d’une diminution de sortie de cycle cellulaire des cellules progénitrices neuronales conduisant à une accumulation de celles-ci, d’une altération de l’architecture des prolongements de la glie radiaire, d’une augmentation de la mort cellulaire par apoptose et d’un défaut de locomotion des neurones post-mitotiques