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N-methyl-D-aspartate receptors (NMDARs) populate GABAergic interneurons, where they play a critical role in shaping circuit motifs and memory. However, we are largely ignoring whether and how NMDARs at GABAergic interneurons are gated by signals released in their surrounding microenvironment. Here we explore the dynamics of the co-agonist site occupancy by D-serine and glycine at glutamatergic synapses onto parvalbumin positive GABAergic interneurons in the adolescent prefrontal cortex, an area central to complex cognitive operation. We discovered that D-serine but not glycine is required for maintaining the activity of NMDAR at the GABAergic interneurons and that the identity of the co-agonist is not determined by the synaptic regime. Our study extends the physiological implications of D-serine in brain physiopathology by uncovering its control of inhibitory synaptic networks through NMDARs.

Brain dysfunction in myotonic dystrophy type 1 (DM1), the prototype of toxic RNA disorders, has been mainly attributed to neuronal RNA misprocessing, while little attention has been given to non-neuronal brain cells. Using a transgenic mouse model of DM1 that expresses mutant RNA in various brain cell types, we demonstrate that astrocytes exhibit impaired ramification and polarization in vivo and defects in adhesion, spreading and migration. RNA-dependent toxicity and phenotypes was also found in human transfected glial cells. In line with the cell phenotypes, molecular analyses revealed extensive expression and accumulation of toxic RNA in astrocytes, which resulted in RNA spliceopathy that was remarkably more severe than in neurons. Astrocyte missplicing affected primarily transcripts that regulate cell adhesion, cytoskeleton and morphogenesis, and it was confirmed in human brain tissue. We demonstrate for the first time that DM1 impacts astrocyte cell biology, possibly compromising their support and regulation of synaptic function.

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Fifty million people worldwide are affected by dementia, a heterogeneous neurodegenerative condition encompassing diseases such as Alzheimer’s, vascular dementia, and Parkinson’s. For them, cognitive decline is often the first marker of the pathology after irreversible brain damage has already occurred. Researchers now believe that structural and functional alterations of the brain vasculature could be early precursors of the diseases and are looking at how functional imaging could provide an early diagnosis years before irreversible clinical symptoms. In this preclinical pilot study, we proposed using functional ultrasound (fUS) on the retina to assess neurovascular alterations non-invasively, bypassing the skull limitation. We demonstrated for the first time the use of functional ultrasound in the retina and applied it to characterize the retinal hemodynamic response function in vivo in rats following a visual stimulus. We then demonstrated that retinal fUS could measure robust neurovascular coupling alterations between wild-type rats and TgF344-AD rat models of Alzheimer’s disease. We observed an average relative increase in blood volume of 21% in the WT versus 37% for the TG group (p = 0.019). As a portable, non-invasive and inexpensive technique, rfUS is a promising functional screening tool in clinics for dementia years before symptoms.

International audience; Neural computational power is determined by neuroenergetics, but how and which energy substrates are allocated to various forms of memory engram is unclear. To solve this question, we asked whether neuronal fueling by glucose or lactate scales differently upon increasing neural computation and cognitive loads. Here, using electrophysiology, two-photon imaging, cognitive tasks, and mathematical modeling, we show that both glucose and lactate are involved in engram formation, with lactate supporting long-term synaptic plasticity evoked by high-stimulation load activity patterns and high attentional load in cognitive tasks and glucose being sufficient for less demanding neural computation and learning tasks. Indeed, we show that lactate is mandatory for demanding neural computation, such as theta-burst stimulation, while glucose is sufficient for lighter forms of activity-dependent long-term potentiation (LTP), such as spike timing–dependent plasticity (STDP). We find that subtle variations of spike number or frequency in STDP are sufficient to shift the on-demand fueling from glucose to lactate. Finally, we demonstrate that lactate is necessary for a cognitive task requiring high attentional load, such as the object-in-place task, and for the corresponding in vivo hippocampal LTP expression but is not needed for a less demanding task, such as a simple novel object recognition. Overall, these results demonstrate that glucose and lactate metabolism are differentially engaged in neuronal fueling depending on the complexity of the activity-dependent plasticity and behavior.

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From the development of a neuron through morphogenesis and migration to mature stages with plasticity events, all stages of a neuron’s life requires the neuronal cytoskeleton. Actin filaments and microtubules (MT) are the main elements of the cytoskeleton. They are dynamic polymers regulated by associated proteins that helps them assemble, disassemble or stabilize and organize them in specific structures. The Microtubule Associated Protein 6 (MAP6) is known for its unique ability to stabilize neuronal MTs. MAP6 also regulate the actin cytoskeleton in dendritic spines during neuronal plasticity events. MAP6 regulation of the MT and actin cytoskeletons is required for normal neuronal development and function and affects mice behavior and cognitive abilities. As such, MAP6 knock-out mouse is a model of schizophrenia. A precise understanding of how MAP6 interacts and modulates the cytoskeleton was lacking at the molecular level. By using in vitro reconstitution systems, we showed that MAP6 is a MT stabilizer that induces MT coiling. By demonstrating that MT coiling is due to MAP6 localization in the MT lumen, we identified the first neuronal Microtubule Inner Protein (MIP). This discovery paves the way to decipher the physiological role of neuronal MIPs. It is now clear that several proteins involved in either MT or actin regulation are in fact able to regulate both cytoskeletons. By analyzing MT and actin assembly in the presence of MAP6 both in separated and simultaneous systems, we identify MAP6 as the first protein able to promote both MT and actin filament nucleation. Moreover, MT nucleation and MAP6 MIP activities are linked. MAP6 is also structuring the cytoskeleton by forming actin bundles and crosslinking actin filaments with microtubules. Finally, we show that MAP6 isoforms differentially regulate the cytoskeleton through phase separation mechanisms. Overall, the use of minimal reconstitution systems allowed us to demonstrate that MAP6 is a multifunctional regulator of the cytoskeleton., Du développement d'un neurone, en passant par la morphogenèse et la migration, jusqu'aux stades de maturité avec des événements de plasticité, toutes les étapes de la vie d'un neurone nécessitent le cytosquelette neuronal. Les filaments d'actine et les microtubules (MT) sont les principaux éléments du cytosquelette. Ce sont des polymères dynamiques régulés par des protéines associées qui les aident à s'assembler, à se désassembler ou à se stabiliser et à s'organiser en structures spécifiques. La protéine associée aux microtubules 6 (MAP6) est connue pour sa capacité unique à stabiliser les MTs neuronaux. MAP6 régule également le cytosquelette d'actine dans les épines dendritiques pendant les événements de plasticité neuronale. La régulation par MAP6 des cytosquelettes de MTs et d'actine est nécessaire au développement et au fonctionnement normal des neurones et affecte le comportement et les capacités cognitives des souris. À ce titre, la souris knock-out MAP6 est un modèle de schizophrénie. Une compréhension précise de la manière dont MAP6 interagit et module le cytosquelette faisait défaut au niveau moléculaire. En utilisant des systèmes de reconstitution in vitro, nous avons montré que MAP6 est un stabilisateur des MTs qui induit la formation de MTs hélicoïdaux. En démontrant que la formation de MTs en hélices est due à la localisation de MAP6 dans la lumière des MTs, nous avons identifié la première protéine interne des microtubules (MIP) neuronale. Cette découverte ouvre la voie au décryptage du rôle physiologique des MIPs neuronales. Il est maintenant clair que certaines protéines impliquées dans la régulation des MTs ou de l'actine sont en fait capables de réguler les deux cytosquelettes. En analysant l'assemblage des MTs et de l'actine en présence de MAP6 dans des systèmes séparés et simultanés, nous identifions MAP6 comme la première protéine capable de promouvoir la nucléation des MTs et des filaments d'actine. De plus, la nucléation des MT et les activités MIP de MAP6 sont liées. MAP6 structure également le cytosquelette en formant des faisceaux d'actine et en réticulant les filaments d'actine avec les microtubules. Enfin, nous montrons que les isoformes de MAP6 régulent de manière différentielle le cytosquelette par des mécanismes de séparation de phase. Globalement, l'utilisation de systèmes de reconstitution in vitro nous a permis de démontrer que MAP6 est un régulateur multifonctionnel du cytosquelette.

International audience; Purpose: The aim of this study was to define the role of dystrophin Dp71 in corneal angiogenesis.Methods: Inflammation-induced corneal neovascularization experiments were performed in Dp71-null mice and C57BL/6J wild-type mice.Results: The corneal neovascular area covered by neovascularization was larger in the injured corneas of the Dp71-null mice compared to the corneas of the wild-type mice: 40.72% versus 26.33%, respectively (p

International audience; Tau is a naturally disordered microtubule associated protein which forms intraneuronal aggregates in several neurodegenerative diseases including Alzheimer disease (AD). It was reported that zinc interaction with tau protein can trigger its aggregation. Recently we identified three zinc binding sites located in the N-terminal part, repeat region and the C-terminal part of tau. Here we characterized zinc binding to each of three sites using isothermal titration calorimetry (ITC) and determined the impact of each site on aggregation using dynamic light scattering (DLS) assays. First, we confirmed the presence of three zinc binding sites on tau and determined the thermodynamic parameters of binding of zinc to these sites. We found a high-affinity zinc binding site located in the repeat region of tau and two N-and C-terminus binding sites with a lower binding constant for zinc. Second, we showed that tau aggregation necessitates zinc binding to the high affinity site in the R2R3 region, while LLPS necessitates zinc binding to any two binding sites. Regarding the role of zinc ions in the aggregation of proteins in neurodegenerative diseases, these findings bring new insights to the understanding of the aggregation mechanism of tau protein induced by zinc.

Feedback connections play a major role in many theories of brain function. Previous studies of feedback connections to early visual areas have mainly concentrated on the representation of central visual fields. Here, injections of tracers at different eccentricities in areas V1 and V2 revealed retinotopically organized feedback. Peripheral injections revealed projections from 15 areas that are not labeled by central injections. Connection strengths for the majority of projections vary significantly with eccentricity in a systematic fashion with respect to distance and origin; whereas projections to central and upper visual fields are significantly stronger from ventral stream areas, peripheral and lower field projections are stronger from the dorsal stream. Non-invasive functional connectivity suggests a similar anatomical organization in humans. These features are discussed with respect to the cognitive and perceptual roles of these feedback pathways.

Antidepressants (ADs) are, for now, the best everyday treatment we have for moderate to severe major depressive episodes (MDEs). ADs are among the most prescribed drugs in the Western Hemisphere; however, the trial-and-error prescription strategy and side-effects leave a lot to be desired. More than 60% of patients suffering from major depression fail to respond to the first AD they are prescribed. For those who respond, full response is only observed after several weeks of treatment. In addition, there are no biomarkers that could help with therapeutic decisions; meanwhile, this is already true in cancer and other fields of medicine. For years, many investigators have been working to decipher the underlying mechanisms of AD response. Here, we provide the first systematic review of animal models. We thoroughly searched all the studies involving rodents, profiling transcriptomic alterations consecutive to AD treatment in naïve animals or in animals subjected to stress-induced models of depression. We have been confronted by an important heterogeneity regarding the drugs and the experimental settings. Thus, we perform a meta-analysis of the AD signature of fluoxetine (FLX) in the hippocampus, the most studied target. Among genes and pathways consistently modulated across species, we identify both old players of AD action and novel transcriptional biomarker candidates that warrant further investigation. We discuss the most prominent transcripts (immediate early genes and activity-dependent synaptic plasticity pathways). We also stress the need for systematic studies of AD action in animal models that span across sex, peripheral and central tissues, and pharmacological classes.

The surface of the central nervous system (CNS) is protected by the meninges, which contain a dense network of meningeal macrophages (MMs). Here, we examined the role of tissue-resident MM in viral infection. MHC-II� MM were abundant neonatally, whereas MHC-II+ MM appeared over time. These barrier macrophages differentially responded to in vivo peripheral challenges such as LPS, SARS-CoV-2, and lymphocytic choriomeningitis virus (LCMV). Peripheral LCMV infection, which was asymptomatic, led to a transient infection and activation of the meninges. Mice lacking macrophages but conserving brain microglia, or mice bearing macrophage-specific deletion of Stat1 or Ifnar, exhibited extensive viral spread into the CNS. Transcranial pharmacological depletion strategies targeting MM locally resulted in several areas of the meninges becoming infected and fatal meningitis. Low numbers of MHC-II+ MM, which is seen upon LPS challenge or in neonates, corelated with higher viral load upon infection. Thus, MMs protect against viral infection and may present targets for therapeutic manipulation., Authors affiliations: (1) Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, Marseille, France (2) Ecole Normale Supérieure de Lyon, Université Claude Bernard – Lyon I, Université de Lyon, Lyon, France (3)Centre d'Immunophénomique, Aix Marseille Université , Inserm, CNRS, Marseille, France (4) TERI (Tumor Escape, Resistance and Immunity) Department, Centre de Recherche en Cancérologie de Lyon, Centre Léon Bérard, Université Claude Bernard – Lyon 1, Université de Lyon, Inserm, CNRS, Lyon, France (5) Viral Immunology and Intravital Imaging Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA (6) Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai, China (7) University Paris-Saclay, Inserm U1015, Gustave Roussy Cancer Center, Villejuif, France (8) Singapore Immunology Network, A*STAR, Singapore, Singapore (9) Centre for Inflammation Biology and Cancer Immunology, Cancer Research UK King's Health Partners Centre, School of Immunology and Microbial Sciences, King's College London, London SE1 1UL, UK (10) Lead contact

International audience; Interleukin-33 (IL-33) is an immunomodulatory cytokine which plays critical roles in tissue function and immune-mediated diseases. IL-33 is abundant within the brain and spinal cord tissues where it acts as a key cytokine to coordinate the exchange between the immune and central nervous system (CNS). In this review, we report the recent advances to our knowledge regarding the role of IL-33 and of its receptor ST2 in cerebral malaria, and in particular, we highlight the pivotal role that IL-33/ST2 signaling pathway could play in brain and cerebrospinal barriers permeability. IL-33 serum levels are significantly higher in children with severe Plasmodium falciparum malaria than children without complications or noninfected children. IL-33 levels are correlated with parasite load and strongly decrease with parasite clearance. We postulate that sequestration of infected erythrocytes or merozoites liberation from schizonts could amplify IL-33 production in endothelial cells, contributing either to malaria pathogenesis or recovery.

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International audience; Erdheim-Chester disease (ECD) is a rare L-group histiocytosis. Orbital involvement is found in a third of cases, but few data are available concerning the radiological features of ECD-related orbital disease (ECD-ROD). Our aim was to characterize the initial radiological phenotype and outcome of patients with ECD-ROD. Initial and follow-up orbital magnetic resonance imaging (MRI) from the patients with histologically proven ECD at a national reference center were reviewed. Pathological orbital findings were recorded for 45 (33%) of the 137 patients included, with bilateral involvement in 38/45 (84%) cases. The mean age (± standard deviation) of these patients was 60 (±11.3) years and 78% were men. Intraconal fat infiltration around the optic nerve sheath adjacent to the eye globe (52%), with intense gadolinium uptake and a fibrous component was the most frequent phenotype described. Optic nerve signal abnormalities were observed in 47% of cases. Two patients had bilateral homogeneous extraocular muscle enlargement suggestive of a myositis-like involvement of ECD-ROD. None had isolated dacryoadenitis but in 17 eyes dacryodenitis was described in association with other types of orbital lesions. Only seven patients (15%) had normal brain MRI findings. ECD-associated paranasal sinus involvement and post-pituitary involvement were detected in 56% and 53% of patients, respectively. A decrease/disappearance of the lesions was observed in 17/24 (71%) of the patients undergoing late (>12 months) followups. Interestingly, ECD-ROD only rarely (7/45; 16%) revealed the disease, with exophthalmos being the most frequently identified feature in this subgroup (3/45; 6%). Even though ECD-ROD can be clinically silent, it comprises a broad array of lesions often resulting in optic nerve signal abnormalities, the functional outcome of which remains to be established. ECD-ROD should thus be assessed initially and subsequently monitored by orbital MRI and ophthalmological follow-up.

International audience; Introduction: The anatomical substrate of motor disability in MS patients is not fully understood. Studyingthe distribution of corticospinal tracts (CST) lesions per side, from the brain to the end of the thoracic spinal cord (SC) couldprovide a better association with patient motor deficits evaluated per limb.Objectives: i) To describe lesion preferential location along the CST; ii) To investigate the association between CST lesionsand motor functional consequences, as measured using the EDSS, and the ASIA motor scores and electrophysiology (Centralmotor conduction time (CMCT)) per limb.Methods: 21 relapsing remitting MS (median EDSS=2.5) and 9 progressive MS patients (median EDSS=5.2) with clinicalpyramidal symptoms were scanned on a 3T Siemens MRI scanner. White matter lesions were segmented on 3D FLAIR for thebrain, on T2* for cervical SC and T2 for thoracic SC. For each patient, registration to an atlas was computed using Anima andSCT toolboxes. Lesion volume fraction along the CST (defined as "lesion volume along the CST"/"overall CST volume") wascalculated separately for the both sides on 3 regions: brain including brainstem, C1 to C7 (C1C7) and T1 to T10 (T1T10).Finally, the relationships between lesion volume fraction and the associated lateralized disability scores were assessed usingmultiple linear models, adjusting for age and disease duration.Results: In MS patients, lesion volume fraction was higher in the C1C7 portion compared to the brain and T1T10 portion (allp’s.6; all p’s

International audience; Homeostatic synaptic plasticity is a process by which neurons adjust their synaptic strength to compensate for perturbations in neuronal activity. Whether the highly diverse synapses on a neuron respond uniformly to the same perturbation remains unclear. Moreover, the molecular determinants that underlie synapse-specific homeostatic synaptic plasticity are unknown. Here, we report a synaptic tagging mechanism in which the ability of individual synapses to increase their strength in response to activity deprivation depends on the local expression of the spine-apparatus protein synaptopodin under the regulation of miR-124. Using genetic manipulations to alter synaptopodin expression or regulation by miR-124, we show that synaptopodin behaves as a "postsynaptic tag" whose translation is derepressed in a subpopulation of synapses and allows for nonuniform homeostatic strengthening and synaptic AMPA receptor stabilization. By genetically silencing individual connections in pairs of neurons, we demonstrate that this process operates in an input-specific manner. Overall, our study shifts the current view that homeostatic synaptic plasticity affects all synapses uniformly to a more complex paradigm where the ability of individual synapses to undergo homeostatic changes depends on their own functional and biochemical state.

Action potential (AP) shape is a critical electrophysiological parameter, in particular because it strongly modulates neurotransmitter release. AP shape is also used to distinguish neuronal populations, as it greatly varies between neuronal types. For instance, AP duration ranges from hundreds of microseconds in cerebellar granule cells to 2-3 milliseconds in substantia nigra pars compacta (SNc) dopaminergic (DA) neurons. While most of this variation seems to arise from differences in the subtypes of voltage- and calcium-gated ion channels expressed, a few studies suggested that dendritic morphology may also affect AP shape. However, AP duration also displays significant variability in a same neuronal type, while the determinants of these variations are poorly known. Using electrophysiological recordings, morphological reconstructions and realistic Hodgkin-Huxley modeling, we investigated the relationships between dendritic morphology and AP shape in SNc DA neurons. In this neuronal type where the axon arises from an axon-bearing dendrite (ABD), the duration of the somatic AP could be predicted from a linear combination of the complexities of the ABD and the non-ABDs. Dendrotomy simulation and experiments showed that these correlations arise from the causal influence of dendritic topology on AP duration, due in particular to a high density of sodium channels in the somato-dendritic compartment. In addition, dendritic morphology also modulated AP back-propagation efficiency in response to barrages of EPSCs in the ABD. In line with previous findings, these results demonstrate that dendritic morphology plays a major role in defining the electrophysiological properties of SNc DA neurons and their cell-to-cell variations.SIGNIFICANCE STATEMENTAction potential (AP) shape is a critical electrophysiological parameter, in particular because it strongly modulates neurotransmitter release. AP shape (e.g. duration) greatly varies between neuronal types but also within a same neuronal type. While differences in ion channel expression seem to explain most of AP shape variation across cell types, the determinants of cell-to-cell variations in a same neuronal type are mostly unknown. We used electrophysiological recordings, neuronal reconstruction and modeling to show that, due to the presence of sodium channels in the somato-dendritic compartment, a large part of cell-to-cell variations in somatic AP duration in substantia nigra pars compacta dopaminergic neurons is explained by variations in dendritic topology.

Background Perineuronal nets (PNNs) are specialized extracellular matrix structures mainly found around fast-spiking parvalbumin (FS-PV) interneurons. In the adult, their degradation alters FS-PV-driven functions, such as brain plasticity and memory, and altered PNN structures have been found in neurodevelopmental and central nervous system disorders such as Alzheimer’s disease, leading to interest in identifying targets able to modify or participate in PNN metabolism. The serine protease tissue-type plasminogen activator (tPA) plays multifaceted roles in brain pathophysiology. However, its cellular expression profile in the brain remains unclear and a possible role in matrix plasticity through PNN remodeling has never been investigated. Result By combining a GFP reporter approach, immunohistology, electrophysiology, and single-cell RT-PCR, we discovered that cortical FS-PV interneurons are a source of tPA in vivo. We found that mice specifically lacking tPA in FS-PV interneurons display denser PNNs in the somatosensory cortex, suggesting a role for tPA from FS-PV interneurons in PNN remodeling. In vitro analyses in primary cultures of mouse interneurons also showed that tPA converts plasminogen into active plasmin, which in turn, directly degrades aggrecan, a major structural chondroitin sulfate proteoglycan (CSPG) in PNNs. Conclusions We demonstrate that tPA released from FS-PV interneurons in the central nervous system reduces PNN density through CSPG degradation. The discovery of this tPA-dependent PNN remodeling opens interesting insights into the control of brain plasticity.

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the TNF ligand family involved in various diseases including brain inflammatory pathologies such as multiple sclerosis. It has been demonstrated that TWEAK can induce cerebrovascular permeability in an in vitro model of the blood–brain barrier. The molecular mechanisms playing a role in TWEAK versus TNFα signaling on cerebral microvascular endothelial cells are not well defined. Therefore, we aimed to identify gene expression changes in cultures of human brain microvascular endothelial cells (hCMEC/D3) to address changes initiated by TWEAK exposure. Taken together, our studies highlighted that gene involved in leukocyte extravasation, notably claudin-5, were differentially modulated by TWEAK and TNFα. We identified differential gene expression of hCMEC/D3 cells at three timepoints following TWEAK versus TNFα stimulation and also found distinct modulations of several canonical pathways including the actin cytoskeleton, vascular endothelial growth factor (VEGF), Rho family GTPases, and phosphatase and tensin homolog (PTEN) pathways. To our knowledge, this is the first study to interrogate and compare the effects of TWEAK versus TNFα on gene expression in brain microvascular endothelial cells.

International audience; After demyelinating insult, the neuronal progenitors of the adult mouse sub-ventricular zone (SVZ) called neuroblasts convert into oligodendrocytes that participate to the remyelination process. We use this rare example of spontaneous fate conversion to identify the molecular mechanisms governing these processes. Using in vivo cell lineage and single cell RNA-sequencing, we demonstrate that SVZ neuroblasts fate conversion proceeds through formation of a non-proliferating transient cellular state co-expressing markers of both neuronal and oligodendrocyte identities. Transition between the two identities starts immediately after demyelination and occurs gradually, by a stepwise upregulation/downregulation of key TFs and chromatin modifiers. Each step of this fate conversion involves fine adjustments of the transcription and translation machineries as well as tight regulation of metabolism and migratory behaviors. Together, these data constitute the first in-depth analysis of a spontaneous cell fate conversion in the adult mammalian CNS.

Neural activity in the sensory cortex combines stimulus responses and ongoing activity, but it remains unclear whether these reflect the same underlying dynamics or separate processes. In the present study, we show in mice that, during wakefulness, the neuronal assemblies evoked by sounds in the auditory cortex and thalamus are specific to the stimulus and distinct from the assemblies observed in ongoing activity. By contrast, under three different anesthetics, evoked assemblies are indistinguishable from ongoing assemblies in the cortex. However, they remain distinct in the thalamus. A strong remapping of sensory responses accompanies this dynamic state change produced by anesthesia. Together, these results show that the awake cortex engages dedicated neuronal assemblies in response to sensory inputs, which we suggest is a network correlate of sensory perception.

BackgroundNon-ischemic cerebral enhancing (NICE) lesions are exceptionally rare following aneurysm endovascular therapy (EVT).ObjectiveTo investigate the presenting features and longitudinal follow-up of patients with NICE lesions following aneurysm EVT.MethodsPatients included in a retrospective national multicentre inception cohort were analysed. NICE lesions were defined, using MRI, as delayed onset punctate, nodular or annular foci enhancements with peri-lesion edema, distributed in the vascular territory of the aneurysm EVT, with no other confounding disease.ResultsFrom a pool of 58 815 aneurysm endovascular treatment procedures during the study sampling period (2006–2019), 21/37 centres identified 31 patients with 32 aneurysms of the anterior circulation who developed NICE lesions (mean age 45±10 years). Mean delay to diagnosis was 5±9 months, with onset occurring a month or less after the index EVT procedure in 10 out of 31 patients (32%). NICE lesions were symptomatic at time of onset in 23 of 31 patients (74%). After a mean follow-up of 25±26 months, 25 patients (81%) were asymptomatic or minimally symptomatic without disability (modified Rankin Scale (mRS) score 0–1) at last follow-up while 4 (13%) presented with mild disability (mRS score 2). Clinical follow-up data were unavailable for two patients. Follow-up MRI (available in 27 patients; mean time interval after onset of 22±22 months) demonstrated persistent enhancement in 71% of cases.ConclusionsThe clinical spectrum of NICE lesions following aneurysm EVT therapy spans a wide range of neurological symptoms. Clinical course is most commonly benign, although persistent long-term enhancement is frequent.

International audience; Neurons rely on a unique organization of their cytoskeleton to build, maintain and transform their extraordinarily intricate shapes. After decades of research on the neuronal cytoskeleton, it is exciting that novel assemblies are still discovered thanks to progress in cellular imaging methods. Indeed, super-resolution microscopy has revealed that axons are lined with a periodic scaffold of actin rings, spaced every 190 nm by spectrins. Determining the architecture, composition, dynamics, and functions of this membraneassociated periodic scaffold is a current conceptual and technical challenge, as well as a very active area of research. This short review aims at summarizing the latest research on the axonal periodic scaffold, highlighting recent progress and open questions.

International audience; BACKGROUND: Menière disease (MD) and SLC26A4 related deafness (Pendred syndrome (PS) or DFNB4) are two different inner ear disorders which present with fluctuating and progressive hearing loss, which could be a direct consequence of endolymphatic hydrops. OBJECTIVE: To present similarities between both pathologies and explore how the concept of hydrops may be applied to PS/DFNB4. METHODS: Review of the literature on MD, PS/DFNB4 and mouse model of PS/DFNB4. RESULTS: MD and PS/DFNB4 share a number of similarities such as fluctuating and progressive hearing loss, acute episodes with vertigo and tinnitus, MRI and histological evidence of endolymphatic hydrops (although with different underlying mechanisms). MD is usually diagnosed during the fourth decade of life whereas PS/DFNB4 is congenital. The PS/DFNB4 mouse models have shown that biallelic slc26a4 mutations lead to Na+ and water retention in the endolymph during the perinatal period, which in turn induces degeneration of the stria vascularis and hearing loss. Crossing clinical/imagery characteristics and animal models, evidence seems to support the hypothesis of PS being a foetal hydrops. CONCLUSIONS: When understanding PS/DFNB4 as a developmental hydrops, treatments used in MD could be repositioned to PS.

International audience; The large number of ion channels found in all nervous systems poses fundamental questions concerning how the characteristic intrinsic properties of single neurons are determined by the specific subsets of channels they express. All neurons display many different ion channels with overlapping voltage- and time-dependent properties. We speculate that these overlapping properties promote resilience in neuronal function. Individual neurons of the same cell type show variability in ion channel conductance densities even though they can generate reliable and similar behavior. This complicates a simple assignment of function to any conductance and is associated with variable responses of neurons of the same cell type to perturbations, deletions, and pharmacological manipulation. Ion channel genes often show strong positively correlated expression, which may result from the molecular and developmental rules that determine which ion channels are expressed in a given cell type.

No curative treatment is available for any deficits induced by spinal cord injury (SCI). Following injury, microglia undergo highly diverse activation processes, including proliferation, and play a critical role on functional recovery.In a translational objective, we investigated whether a transient pharmacological reduction of microglia proliferation after injury is beneficial for functional recovery after SCI in mice and nonhuman primates. The colony stimulating factor-1 receptor (CSF1R) regulates proliferation, differentiation, and survival of microglia, we thus used an oral administration of GW2580, a CSF1R inhibitor.First, transient post-injury GW2580 administration in mice improves motor function recovery, promotes tissues preservation and/or reorganization (identified by coherent anti-stokes Raman scattering microscopy), and modulates glial reactivity.Second, post-injury GW2580-treatment in nonhuman primates reduces microglia proliferation, improves functional motor function recovery, and promotes tissue protection. Notably, three months after lesion microglia reactivity returned to baseline value.Finally, to initiate the investigation on molecular mechanisms induced by a transient post-SCI GW2580-treatment, we used microglia-specific transcriptomic analysis in mice. Notably, we detected a downregulation in the expression of inflammatory-associated genes and we identified genes that were up-regulated by SCI and further downregulated by the treatment.Thus, a transient oral GW2580 treatment post-injury may provide a promising therapeutic strategy for SCI patients and may also be extended to other central nervous system disorders displaying microglia activation.

Background Myogenesis is a highly regulated process ending with the formation of myotubes, the precursors of skeletal muscle fibers. Differentiation of myoblasts into myotubes is controlled by myogenic regulatory factors (MRFs) that act as terminal effectors of signaling cascades involved in the temporal and spatial regulation of muscle development. Such signaling cascades converge and are controlled at the level of intracellular trafficking, but the mechanisms by which myogenesis is regulated by the endosomal machinery and trafficking is largely unexplored. The Endosomal Sorting Complex Required for Transport (ESCRT) machinery composed of four complexes ESCRT-0 to ESCRT-III regulates the biogenesis and trafficking of endosomes as well as the associated signaling and degradation pathways. Here, we investigate its role in regulating myogenesis. Results We uncovered a new function of the ESCRT-0 hepatocyte growth factor-regulated tyrosine kinase substrate Hrs/Hgs component in the regulation of myogenesis. Hrs depletion strongly impairs the differentiation of murine and human myoblasts. In the C2C12 murine myogenic cell line, inhibition of differentiation was attributed to impaired MRF in the early steps of differentiation. This alteration is associated with an upregulation of the MEK/ERK signaling pathway and a downregulation of the Akt2 signaling both leading to the inhibition of differentiation. The myogenic repressors FOXO1 as well as GSK3β were also found to be both activated when Hrs was absent. Inhibition of the MEK/ERK pathway or of GSK3β by the U0126 or azakenpaullone compounds respectively significantly restores the impaired differentiation observed in Hrs-depleted cells. In addition, functional autophagy that is required for myogenesis was also found to be strongly inhibited. Conclusions We show for the first time that Hrs/Hgs is a master regulator that modulates myogenesis at different levels through the control of trafficking, signaling, and degradation pathways.

Music can cause pleasant sensations in humans whereas some noises can cause discomfort. The effects of music and noise have also been somewhat studied in animals, showing different impacts. In this review we aim to illustrate the differences and similarities between animals, in terms of their sensitivity to auditory stimuli (noise or music), by first recalling some generalities about the physical characteristics of sound and the biological bases of hearing. Second, based on the studies reported in this review, we conclude that ambient noise is harmful and/or stressful, and that musical sounds can take many forms with a large range of impacts in animals. Finally, we present two practical examples of the use of music with animals (one in the context of a zoo and the other in cattle breeding) and an example of an experiment designed to understand the impact of music on neonate lambs. These three examples highlight how music can help to improve animal welfare.

The ability to extract temporal regularities at different time scales in sensory inputs and detect unexpected deviations from these regularities is a key cognitive ability. The classical auditory oddball paradigm shows that the brain responds to sequence violations at a local time scale, but such responses also occur under anesthesia and therefore seem pre-attentive. In contrast, recent studies in humans and monkeys suggest that when the violation concerns regularities occurring over longer time scales, responses to the violation appear only in conscious, attentive subjects. To investigate whether local and global sequence violation responses exist in the mouse, we recorded from layers 1 to 5 of the auditory cortex using two-photon calcium imaging while mice passively listened to repetitions of 1s-long sequences of five tones. The repeated short sequence contained either a single tone (AAAAA) or a local violation at its end (AAAAB). Purely global violations could be generated by presenting occasionally the AAAAA sequence in a block where AAAAB is repeated. We found that a population of neurons in the auditory cortex specifically responds to such purely global violations at the end of the AAAAA sequence. Although small, this population contained enough information to predict violations on single trials. A larger fraction of neurons boosted their responses to combinations of local and global violations (AAAAB presented in an AAAAA block). These global responses were resistant to a wide increase of inter-sequence interval (1.5s - 25s) ruling out that short-term adaptation causes these responses. These results establish that the mouse brain is able to detect global violations in sound sequences in a subgroup of auditory cortex neurons, paving the way for the study of circuit mechanisms underlying long-term temporal regularity detection.; La capacité d'extraire des régularités temporelles à différentes échelles de temps dans des entrées sensorielles et de détecter des déviations inattendues de ces régularités est une capacité cognitive clé. Le paradigme classique de l'oddball auditif montre que le cerveau répond aux violations de séquences à une échelle de temps locale, mais ces réponses se produisent également sous anesthésie et semblent donc pré-attentives. En revanche, des études récentes chez l'homme et le singe suggèrent que lorsque la violation concerne des régularités qui se produisant sur des échelles de temps plus longues, les réponses à la violation n'apparaissent que chez les sujets conscients et attentifs. Afin de déterminer si des réponses locales et globales à la violation de séquence existent chez la souris, nous avons effectué des enregistrements dans les couches 1 à 5 du cortex auditif en utilisant l'imagerie calcique à deux photons pendant que les souris écoutaient passivement des répétitions de séquences de cinq tons d'une durée d'une seconde. La séquence courte répétée contenait soit un seul ton (AAAAA), soit une violation locale à sa fin (AAAAB). Des violations purement globales pouvaient être générées en présentant occasionnellement la séquence AAAAA dans un bloc où AAAAB est répété. Nous avons constaté qu'une population de neurones dans le cortex auditif répond spécifiquement à de telles violations purement globales à la fin de la séquence AAAAA. Bien que petite, cette population contenait suffisamment d'information pour prédire les violations sur des essais uniques. Une fraction plus importante de neurones augmente ses réponses à des combinaisons de violations locales et globales (AAAAB présenté dans un bloc AAAAA). Ces réponses globales sont résistantes à une large augmentation de l'intervalle inter-séquence (1,5s - 25s), ce qui exclut que l'adaptation à court terme soit à l'origine de ces réponses. Ces résultats établissent que le cerveau de la souris est capable de détecter les violations globales dans les séquences sonores dans un sous-groupe de neurones du cortex auditif, ouvrant la voie à l'étude des mécanismes de circuit qui sous-tendent la détection de la régularité temporelle à long terme.

In the central nervous system, astrocytes are glial cells displaying crucial roles in the brain physiology by regulating synaptic transmission, ion homeostasis, the blood brain barrier integrity or the cerebral blood flow. These functions are sustained by morphological and molecular polarities of astrocytes with specific interfaces contacting synapses, the perisynaptic processes (PAP), and blood vessels, the perivascular processes (PvAP). Recently, my laboratory and others demonstrated the presence of mRNAs, ribosomes and local protein synthesis in PAPs and PvAPs and proposed local translation as a mechanism for setting astrocytic polarity. However, little is known about the mechanisms of translation in astrocytes. My PhD project aimed at deciphering how translation is regulated in astrocytes and their interfaces and the role of these mechanisms in brain physiology. First, to characterize the distribution of mRNAs in astrocytes, I developed AstroDot, a specific in-situ approach to quantify the density and distribution of mRNAs in astrocytes. I determined that in hippocampal astrocytes, the distribution and density of mRNAs encoding α and δ isoforms of the glial fibrillary acidic protein (GFAP) are altered and vary with the presence of amyloid plaques in APP/PS1dE9 mice, a mouse model of Alzheimer’s disease. I also demonstrated for the first time the presence of mRNAs in microglia processes, a resident glial cell involved in particular in brain immunity. Following this study, I aimed at identifying mechanisms setting translation in astrocytes and focused on proteins associated with polysomes in astrocytes. I developed a method combining translating ribosome affinity purification in astrocytes with mass spectrometry. Among immunoprecipitated proteins, I focused on RACK1, a scaffold protein known to associate with the small subunit of ribosomes. Our previous analysis of the translatome in PAPs identified Gnb2l1 encoding RACK1 as one of the most enriched translated mRNAs in PAPs, suggesting its possible role in the regulation of translation at this interface. RACK1 acts as a ribosome formation mediator, a translation regulator and takes part in RNA quality control. Its role in astrocytes was unknown. Using a restricted panel of astrocytic enriched or specific mRNAs, I showed that RACK1 preferentially associates with Kncj10 coding for the potassium channel KIR4.1, one of the main regulator of K+ homeostasis in PAPs and PvAPs, and Slc1a2 coding for a glutamate transporter GLT1 which allows glutamate recycling in PAPs. To further address the role of RACK1 in astrocytes, I developed a mouse model in which RACK1 is specifically inactivated in astrocytes (RACK1 cKO). In this model, I found the level of KIR4.1 upregulated in the brain and in PAPs, whereas GLT1 was unchanged. RACK1 can act on the ribosome and on the RNA levels to regulate translation. In vitro investigations on RACK1 KO HEK cells transfected with luciferase reporters showed that KIR4.1 upregulation does not involve ribosome stalling on the Kncj10 coding sequence but relies on a part of the 5’UTR of Kcnj10 (Collaboration with Clément Chapat, Polytechnique). We finally addressed the physiological consequences of these regulations. Performing electrophysiological recordings (Collaboration with Nathalie Rouach, CIRB), we determined that KIR4.1 increase in absence of RACK1 leads to changes in the electrophysiological properties of the hippocampal neurons with an overall protection against high synaptic activity, certainly due to a higher capacity of PAPs to uptake K+. In summary, I developed during my thesis a new method to characterize mRNA distribution in astrocytes. I identified a pool of proteins associated to polysomes in astrocytes. Finally, I focused on RACK1 and identified it as an important regulator of KIR4.1 translation and astrocytic perisynaptic K+ homeostasis., Dans le système nerveux central, les astrocytes, cellules gliales, jouent des rôles cruciaux dans la physiologie du cerveau en régulant la transmission synaptique, l’homéostasie ionique, l’intégrité de la barrière sang-cerveau et le flux sanguin cérébral. Ces fonctions sont soutenues par des polarités morphologique et moléculaire des astrocytes avec des interfaces contactant les synapses, avec les prolongements périsynaptiques (PAP), et les vaisseaux sanguins, avec les prolongements périvasculaires (PvAP). Nous et d’autres avons démontré la présence d’ARNm, de ribosomes et de synthèse protéique locale dans les PAPs et PvAPs et proposé que la traduction locale soit un mécanisme pour la mise en place de la polarité astrocytaire. Cependant, on connaît peu les mécanismes de traduction dans les astrocytes. Mon projet de thèse a eu pour but de décrypter comment la traduction dans les astrocytes est régulée et le quels sont les rôles de ces mécanismes dans la physiologie du cerveau. Nous avons d’abord caractérisé la distribution des ARNm dans les astrocytes en développant AstroDot, une approche in situ pour quantifier la densité et la distribution des ARNm. Nous avons déterminé dans les astrocytes de l’hippocampe que la distribution et la densité d’ARNm codant pour les isoformes alpha et delta de la GFAP étaient altérées et variaient avec la présence de plaques amyloïdes dans un modèle murin de la maladie d’Alzheimer. Nous avons aussi montré pour la 1ère fois la présence d’ARNm dans les prolongements de microglies, une cellule gliale impliquée dans l’immunité cérébrale. Après, j’ai voulu identifier les mécanismes de mise en place de la traduction dans les astrocytes et je me suis concentré sur les protéines associées aux polysomes de cette cellule. J’ai développé une méthode combinant le TRAP avec la spectrométrie de masse. Parmi les protéines immunoprécipitées, je me suis concentré sur RACK1, une protéine d’échafaudage connue pour s’associer avec la petite sous unité des ribosomes. Notre analyse précédente du translatome des PAPs a identifié Gnb2l1, codant pour RACK1, comme l’un des ARNm traduit les plus enrichis dans les PAPs suggérant son rôle dans la régulation de la traduction à cette interface. RACK1 agit comme un régulateur de la formation des ribosomes, de la traduction et prend part au contrôle qualité des ARNm. Son rôle dans les astrocytes était inconnu. En utilisant un panel restreint d’ARN astrocytaires spécifiques, j’ai montré que RACK1 était préférentiellement associé à Kcnj10 codant pour le canal potassique KIR4.1 et Slc1a2 codant pour le transporteur au glutamate GLT1. Pour adresser le rôle de RACK1 dans les astrocytes, j’ai développé un modèle de souris dans laquelle RACK1 est inactivé dans les astrocytes. Dans ce modèle, le niveau de KIR4.1 était augmenté dans le cerveau et dans les PAPs alors que GLT1 était inchangé. RACK1 peut agir aux niveaux du ribosome et de l’ARN pour réguler la traduction. Des expériences in vitro sur des cellules HEK RACK1 KO transfectées avec des rapporteurs luciférase ont montré que l’augmentation de KIR4.1 n’impliquait pas le blocage des ribosomes sur la séquence codante de son ARNm kcnj10 mais était lié à sa partie 5’ non codante. Nous avons adressé les conséquences physiologiques de ces régulations. Par enregistrements électrophysiologiques, nous avons déterminé que l’augmentation de KIR4.1 en l’absence de RACK1 menait à un changement dans les propriétés électriques des neurones de l’hippocampe avec une protection globale contre des activités synaptiques élevées certainement due à une plus grande capacité des PAPs à capturer le potassium. En résumé, j’ai développé une nouvelle méthode pour caractériser la distribution des ARNm dans les astrocytes. J’ai identifié un pool de protéines associées aux polyribosomes astrocytaires. Enfin, Je me suis concentré sur RACK1 et je l’ai identifié comme un régulateur de la traduction de KIR4.1 et de l’homéostasie du potassium périsynaptique.

Ethical approval: The research related to human use complies with all the relevant national regulations, institutional policies and was performed in accordance with the tenets of the Helsinki Declaration and has been approved by the authors’ institutional review board or equivalent committee.; International audience; Deep brain stimulation is widely used to alleviate symptoms of movement disorders. During intraoperative stimulation the influence of active or passive movements on the neuronal activity is often evaluated but the evaluation remains mostly subjective. The objective of this paper is to investigate the potential of a previously developed Weightedfrequency Fourier Linear combiner and Kalman filter-based algorithm to identify tremor types and to isolate the tremorous part. The method is applied to ten intraoperatively acquired accelerometer recordings from eight patients from which 186 phases were manually annotated into: rest, postural and kinetic phase without tremor, and rest, postural and kinetic phase with tremor. The overall accuracy for tremorous phases only is 89.1% and 76.3% when also non-tremorous phases are considered. Two main misclassification cases are identified and further discussed. The results demonstrate the potential of the developed algorithm for the use as an online tremorous movement classifier based on the acquired digital biomarkers.

International audience; Despite being extensively studied for several decades, the microtubule-associated protein Tau has not finished revealing its secrets. For long, Tau has been known for its ability to promote microtubule assembly. A less known feature of Tau is its capability to bind to cancer-related protein kinases, suggesting a possible role of Tau in modulating microtubule-independent cellular pathways that are associated with oncogenesis. With the intention of finding new therapeutic targets for cancer, it appears essential to examine the interaction of Tau with these kinases and their consequences. This review aims at collecting the literature data supporting the relationship between Tau and cancer with a particular focus on glioblastoma tumors in which the pathological significance of Tau remains largely unexplored. We will first treat this subject from a mechanistic point of view showing the pivotal role of Tau in oncogenic processes. Then, we will discuss the involvement of Tau in dysregulating critical pathways in glioblastoma. Finally, we will outline promising strategies to target Tau protein for the therapy of glioblastoma.

International audience; β1 integrins are important in blood vessel formation and function, finely tuning the adhesion of endothelial cells to each other and to the extracellular matrix. The role of integrins in the vascular disease, cerebral cavernous malformation (CCM) has yet to be explored in vivo. Endothelial loss of the gene KRIT1 leads to brain microvascular defects, resulting in debilitating and often fatal consequences. We tested administration of a monoclonal antibody that enforces the active β1 integrin conformation, (clone 9EG7), on a murine neonatal CCM mouse model, Krit1 flox/flox ;Pdgfb-iCreERT2 (Krit1 ECKO), and on KRIT1-silenced human umbilical vein endothelial cells (HUVECs). In addition, endothelial deletion of the master regulator of integrin activation, Talin 1 (Tln1), in Krit1 ECKO mice was performed to assess the effect of completely blocking endothelial integrin activation on CCM. Treatment with 9EG7 reduced lesion burden in the Krit1 ECKO model and was accompanied by a strong reduction in the phosphorylation of the ROCK substrate, myosin light chain (pMLC), in both retina and brain endothelial cells. Treatment of KRIT1-silenced HUVECs with 9EG7 in vitro stabilized cell-cell junctions. Overnight treatment of HUVECs with 9EG7 resulted in significantly reduced total surface expression of β1 integrin, which was associated with reduced pMLC levels, supporting our in vivo findings. Genetic blockade of integrin activation by Tln1 ECKO enhanced bleeding and did not reduce CCM lesion burden in Krit1 ECKO mice. In sum, targeting β1 integrin with an activated-specific antibody reduces acute murine CCM lesion development, which we found to be associated with suppression of endothelial ROCK activity.

International audience; Recent evidence has shown that even mild mutations in the Huntingtin gene that are associated with late-onset Huntington’s disease (HD) disrupt various aspects of human neurodevelopment. To determine whether these seemingly subtle early defects affect adult neural function, we investigated neural circuit physiology in newborn HD mice. During the first postnatal week, HD mice have less cortical layer 2/3 excitatory synaptic activity than wild-type mice, express fewer glutamatergic receptors, and show sensorimotor deficits. The circuit self-normalizes in the second postnatal week but the mice nonetheless develop HD. Pharmacologically enhancing glutamatergic transmission during the neonatal period, however, rescues these deficits and preserves sensorimotor function, cognition, and spine and synapse density as well as brain region volume in HD adult mice.

Nucleic-acid aptamers are of strong interest for diagnosis and therapy. Compared with antibodies, they are smaller, stable upon variations in temperature, easy to modify, and have higher tissue-penetration abilities. However, they have been little described as detection probes in histology studies of human tissue sections. In this study, we performed fluorescence imaging with two aptamers targeting cell-surface receptors EGFR and integrin α5β1, both involved in the aggressiveness of glioblastoma. The aptamers’ cell-binding specificities were confirmed using confocal imaging. The affinities of aptamers for glioblastoma cells expressing these receptors were in the 100–300 nM range. The two aptamers were then used to detect EGFR and integrin α5β1 in human glioblastoma tissues and compared with antibody labeling. Our aptafluorescence assays proved to be able to very easily reveal, in a one-step process, not only inter-tumoral glioblastoma heterogeneity (differences observed at the population level) but also intra-tumoral heterogeneity (differences among cells within individual tumors) when aptamers with different specificities were used simultaneously in multiplexing labeling experiments. The discussion also addresses the strengths and limitations of nucleic-acid aptamers for biomarker detection in histology.

Recent understanding of Autism Spectrum Disorder (ASD) showed that peripheral primary mechanosensitive neurons involved in touch sensation and central neurons affected in ASD share transcriptional regulators. Mutant mice for ASD-associated transcription factors exhibit impaired primary tactile perception, and restoring those genes specifically in primary sensory neurons rescue some of the anxiety-like behavior and social interaction defects.Interestingly, peripheral mechanosensitive sensory neurons also project to internal organs including the cardio-vascular system, and an imbalance of the cardio-vascular sympatho-vagal regulation is evidenced in ASD and intellectual disability. ASD patients have decreased vagal tone, suggesting dysfunction of sensory neurons involved in cardio-vascular sensing.In light of our previous finding that the ASD-associated Meis2 gene is necessary for normal touch neurons development and function, we investigated here if its inactivation in mouse peripheral sensory neurons also affects cardio-vascular sympatho-vagal regulation and baroreflex. Combining echocardiography, pharmacological challenge, blood pressure monitoring and heart rate variability analysis, we found that Meis2 mutant mice exhibited a blunted vagal response independently of any apparent cardiac malformation. These results suggest that defects in primary sensory neurons with mechanosensitive identity could participate in the imbalanced cardio-vascular sympatho-vagal tone found in ASD patients, reinforcing current hypotheses on the role of primary sensory neurons in the etiology of ASD.

International audience; Objective: MicroRNAs are promising biomarkers of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), but discrepant results between studies have so far hampered their use in clinical trials. We aim to assess all previously identified circulating microRNA signatures as potential biomarkers of genetic FTD and/or ALS, using homogeneous, independent validation cohorts of C9orf72 and GRN mutation carriers. Methods: 104 individuals carrying a C9orf72 or a GRN mutation, along with 31 controls, were recruited through the French research network on FTD/ALS. All subjects underwent blood sampling, from which circulating microRNAs were extracted. We measured differences in the expression levels of 65 microRNAs, selected from 15 published studies about FTD or ALS, between 31 controls, 17 C9orf72 presymptomatic subjects, and 29 C9orf72 patients. We also assessed differences in the expression levels of 30 microRNAs, selected from five studies about FTD, between 31 controls, 30 GRN presymptomatic subjects, and 28 GRN patients. Results: More than half (35/65) of the selected microRNAs were differentially expressed in the C9orf72 cohort, while only a small proportion (5/30) of micro-RNAs were differentially expressed in the GRN cohort. In multivariate analyses, only individuals in the C9orf72 cohort could be adequately classified (ROC AUC up to 0.98 for controls versus presymptomatic subjects, 0.94 for controls versus patients, and 0.77 for presymptomatic subjects versus patients) with some of the signatures. Interpretation: Our results suggest that previously identified microRNAs using sporadic or mixed cohorts of FTD and ALS patients could potentially serve as biomarkers of C9orf72-associated disease, but not GRN-associated disease.

International audience; Psychostimulant drugs, such as cocaine, d-amphetamine and methylphenidate, alter a wide range of behaviors including locomotor activity and somatosensory perception. These altered behaviors are accompanied by the activation of specific neuronal populations within reward-, emotion- and locomotion-related circuits. However, whether such regulation occurs at the level of the spinal cord, a key node for neural circuits integrating and coordinating sensory and motor functions has never been addressed. By evaluating the temporal and spatial expression pattern of the phosphorylated form of the immediate early gene cFos at Ser32 (pS32-cFos), used as a proxy of neuronal activation, we demonstrate that, in adult male mice, d-amphetamine increases pS32-cFos expression in both inhibitory and excitatory neurons in dorsal and ventral horns at the lumbar spinal cord level. Interestingly, a fraction of neurons activated by a first exposure to d-amphetamine can be re-activated following d-amphetamine re-exposure. Similar expression patterns were observed in response to cocaine and methylphenidate, but not following morphine and dozilcipine administration. Finally, the blockade of dopamine reuptake was sufficient to recapitulate the increase in pS32-cFos expression induced by psychostimulant drugs. Our work provides evidence that cFos expression can be activated in lumbar spinal cord in response to acute psychostimulants administration. Running title: Psychostimulant-evoked neuronal ensembles in spinal cord.

Purpose FDOPA PET shows good performance for the diagnosis of striatal dopaminergic denervation, making it a valuable tool for the differential diagnosis of Parkinsonism. Textural features are image biomarkers that could potentially improve the early diagnosis and monitoring of neurodegenerative parkinsonian syndromes. We explored the performances of textural features for binary classification of FDOPA scans. Methods We used two FDOPA PET datasets: 443 scans for feature selection, and 100 scans from a different PET/CT system for model testing. Scans were labelled according to expert interpretation (dopaminergic denervation versus no dopaminergic denervation). We built LASSO logistic regression models using 43 biomarkers including 32 textural features. Clinical data were also collected using a shortened UPDRS scale. Results The model built from the clinical data alone had a mean area under the receiver operating characteristics (AUROC) of 63.91. Conventional imaging features reached a maximum score of 93.47 but the addition of textural features significantly improved the AUROC to 95.73 (p p Conclusion A simple model with three radiomic features can identify pathologic FDOPA PET scans with excellent sensitivity and specificity. Textural features show promise for the diagnosis of parkinsonian syndromes.

International audience; The hypothalamus is a large brain region made of nuclei and areas involved in the control of behaviors and physiological regulations. Among them, the arcuate nucleus (ARH) and the lateral hypothalamic area (LHA) contain key neuronal populations expressing the pro-opiomelanocortin (POMC), the agouti-related peptide (AgRP), and the melanin-concentrating hormone (MCH), respectively, that are involved in goal-oriented behaviors (such as feeding behavior) and glucose homeostasis. These neuronal populations are generated from distinct parts of the germinative neuroepithelium during embryonic life, and acquire their cell fate under the influence of morphogen proteins, specific transcription factors, and epigenetic modulators. POMC and MCH neuronal development continues by sending long descending axonal projections before birth under the control of axon guidance molecules such as Netrin1 and Slit2. Later, during the postnatal period, POMC and AgRP neurons develop intra-hypothalamic projections notably to the paraventricular nucleus of the hypothalamus through the influence of other axon guidance cues such as the class3 Semaphorins. Other cellular processes, such as autophagy and primary cilia function, and hormonal cues also appear critical for the proper development of POMC neurons.

Authorized uncorrected proof; International audience; Myotonic dystrophy type 1 (DM1) exhibits highly heterogeneous clinical manifestations caused by an unstable CTG repeat expansion reaching up to 4000 CTG. The clinical variability depends on CTG repeat number, CNG repeat interruptions, and somatic mosaicism. Currently, none of these factors are simultaneously and accurately determined due to the limitations of gold standard methods used in clinical and research laboratories. An amplicon method for targeting the DMPK locus using singlemolecule real-time sequencing was recently developed to accurately analyze expanded alleles. However, amplicon-based sequencing still depends on PCR, and the inherent bias toward preferential amplification of smaller repeats can be problematic in DM1. Thus, an amplification-free long-read sequencing method was developed by using CRISPR/Cas9 technology in DM1. This method was used to sequence the DMPK locus in patients with CTG repeat expansion ranging from 130 to >1000 CTG. We showed that elimination of PCR amplification improves the accuracy of measurement of inherited repeat number and somatic repeat variations, two key factors in DM1 severity and age at onset. For the first time, an expansion composed of >85% CCG repeats was identified by using this innovative method in aDM1 family with an atypical clinical profile. No-amplification targeted sequencing represents a promising method that can overcome research and diagnosis shortcomings, with translational implications for clinical and genetic counseling in DM1

International audience; Slowness of movement initiation is a cardinal motor feature of Parkinson’s disease (PD) and is not fully reverted by current dopaminergic treatments. This trouble could be due to the dysfunction of executive processes and, in particular, of inhibitory control of response initiation, a function possibly associated with the noradrenergic (NA) system. The implication of NA in the network supporting proactive inhibition remains to be elucidated using pharmacological protocols. For that purpose, we administered 150 μg of clonidine to 15 healthy subjects and 12 parkinsonian patients in a double-blind, randomized, placebo-controlled design. Proactive inhibition was assessed by means of a Go/noGo task, while pre-stimulus brain activity was measured by event-related functional MRI. Acute reduction in noradrenergic transmission induced by clonidine enhanced difficulties initiating movements reflected by an increase in omission errors and modulated the activity of the anterior node of the proactive inhibitory network (dorsomedial prefrontal and anterior cingulate cortices) in PD patients. We conclude that NA contributes to movement initiation by acting on proactive inhibitory control via the α2-adrenoceptor. We suggest that targeting noradrenergic dysfunction may represent a new treatment approach in some of the movement initiation disorders seen in Parkinson’s disease

International audience

International audience; OBJECTIVES: Amyotrophic lateral sclerosis (ALS) is a rare disease with heterogenous progression rates ranging from slow to rapid progression. Studies aiming to characterize the factors associated with the progression rate have focused on survival but few concerned the functional decline trajectory [1].METHODS: Using PROACT database (8,569 patients), we select spinal and bulbar patients with at least a baseline and a second follow-up visit. We randomly select spinal patients to get two balanced groups of 1,380 patients. The following steps were performed: 1) We built a multimodal ALS course map that grasped long-term disease progression in a mixed-effects fashion [2] with Leaspy. We used 6 features: the four subscores of ALSFRS-R, forced vital capacity (FVC) and BMI. 2) We extracted the progression rate and onset age, and the relative progression of each feature of each patient from the parameters of the model. 3) We also computed from the disease course, the conversion age to a progression threshold for each feature: 8 points for ALSFRS-R subscores in reference to FT9 score, 18.5 for the BMI and 2.43 litres for FVC. Finally, we compared the distributions of the extracted parameters and conversion ages using independent t-test.RESULTS: We found that ALS starts 2.84 years later for bulbar patients, but progresses 1.36 times faster. We observed, for bulbar patients, that ALSFRS-R fine and gross motor progress 3.7 and 4.4 months later than the spinal patients but ALSFRS-R bulbar progression starts almost 8 months before. Bulbar patients reached endpoint thresholds define above, in average after spinal patients for: ALSFRS-R fine motor (8 points, 49.7 months), gross motor (44 months), bulbar (7.5 months) and respiratory (23.3 months), FVC (24 months).CONCLUSIONS: We build a modelling framework for describing ALS subtypes effect on functional endpoints from multimodal screening assessments. This model also allows describing and predicting individual progression which can pave the way to discriminate fast and slow progressor for stratification of clinical trial. This methodology could also be applied in clinical trial to compare treated and placebo arms.REFERENCES:[1] Grollemund, Vincent, et al. Frontiers in neuroscience 13 (2019): 135.[2] Schiratti, Jean-Baptiste, et al. The Journal of Machine Learning Research 18.1 (2017): 4840-487

International audience; Parkinson's disease (PD) is a progressive, neurodegenerative disorder characterised by the abnormal accumulation of α-synuclein (α-syn) aggregates. Central to disease progression is the gradual spread of pathological α-syn. α-syn aggregation is closely linked to progressive neuron loss. As such, clearance of α-syn aggregates may slow the progression of PD and lead to less severe symptoms. Evidence is increasing that non-neuronal cells play a role in PD and other synucleinopathies such as Lewy body dementia and multiple system atrophy. Our previous work has shown that pericytes-vascular mural cells that regulate the blood-brain barrier-contain α-syn aggregates in human PD brains. Here, we demonstrate that pericytes efficiently internalise fibrillar α-syn irrespective of being in a monoculture or mixed neuronal cell culture. Pericytes cleave fibrillar α-syn aggregates (Fibrils, Ribbons, fibrils65, fibrils91 and fibrils110), with cleaved α-syn remaining present for up to 21 days. The number of α-syn aggregates/cell and average aggregate size depends on the type of strain, but differences disappear within 5 five hours of treatment. Our results highlight the role brain vasculature may play in reducing α-syn aggregate burden in PD.

Spectrins are large, evolutionarily well-conserved proteins that form highly organized scaffolds on the inner surface of eukaryotic cells. Their organization in different cell types or cellular compartments helps cells withstand mechanical challenges with unique strategies depending on the cell type. This Review discusses our understanding of the mechanical properties of spectrins, their very distinct organization in red blood cells and neurons as two examples, and the contribution of the scaffolds they form to the mechanical properties of these cells.

Alzheimer's disease (AD) is characterized by intracerebral accumulations of extracellular amyloid-β (Aβ) plaques and intracellular tau pathology that spread in the brain. Three types of tau lesions occur in the form of neuropil threads, neurofibrillary tangles, and neuritic plaques i.e. tau aggregates within neurites surrounding Aβ deposits. The cascade of events linking these lesions and synaptic or memory impairments are still debated. Intracerebral infusion of human AD brain extracts in Aβ plaque-bearing mice that do not overexpress pathological tau proteins induces tau pathologies following heterotopic seeding of mouse tau protein. There is however little information regarding the downstream events including synaptic or cognitive repercussions of tau pathology induction in these models. In the present study, human AD brain extracts (ADbe) and control-brain extracts (Ctrlbe) were infused into the hippocampus of Aβ plaque-bearing APPswe/PS1dE9 mice. Memory, synaptic density, as well as Aβ plaque and tau aggregate loads, microgliosis, astrogliosis at the inoculation site and in connected regions (perirhinal/entorhinal cortex) were evaluated 4 and 8 months post-inoculation. ADbe inoculation produced the following effects: (i) memory deficit; (ii) increased Aβ plaque deposition in proximity to the inoculation site; (iii) tau pathology induction; (iv) appearance of neuropil threads and neurofibrillary tangles next to the inoculation site with a spreading to connected regions. Neuritic plaque pathology was detected in both ADbe- and Ctrlbe-inoculated animals but ADbe inoculation increased the severity close to and at distance of the inoculation site. (v) Finally, ADbe inoculation reduced synaptic density in the vicinity to the inoculation site and in connected regions as the perirhinal/entorhinal cortex. Synaptic impairments were correlated with increased severity of neuritic plaques but not to other tau lesions or Aβ lesions, suggesting that neuritic plaques are a culprit for synaptic loss. Synaptic density was also associated with microglial load. Graphical abstract

International audience; Neuronal calcium sensors (NCSs) are the family of EF-hand proteins mediating Ca2+-dependent signaling pathways in healthy neurons and neurodegenerative diseases. It was hypothesized that the calcium sensor activity of NCSs can be complemented by sensing fluctuation of intracellular zinc, which could further diversify their function. Here, using a set of biophysical techniques, we analyzed the Zn2+-binding properties of five proteins belonging to three different subgroups of the NCS family, namely, VILIP1 and neurocalcin-δ/NCLD (subgroup B), recoverin (sub-group C), as well as GCAP1 and GCAP2 (subgroup D). We demonstrate that each of these proteins is capable of coordinating Zn2+ with a different affinity, stoichiometry, and structural outcome. In the absence of calcium, recoverin and VILIP1 bind two zinc ions with submicromolar affinity, and the binding induces pronounced conformational changes and regulates the dimeric state of these proteins without significant destabilization of their structure. In the presence of calcium, recoverin binds zinc with slightly decreased affinity and moderate conformational outcome, whereas VILIP1 becomes 2+ 2+ insensitive to Zn . NCALD binds Zn with micromolar affinity, but the binding induces dramatic destabilization and aggregation of the protein. In contrast, both GCAPs demonstrate low-affinity binding of zinc independent of calcium, remaining relatively stable even at submillimolar Zn2+ concentrations. Based on these data, and the results of structural bioinformatics analysis, NCSs can be divided into three categories: (1) physiological Ca2+/Zn2+ sensor proteins capable of binding exchangeable (signaling) zinc (recoverin and VILIP1), (2) pathological Ca2+/Zn2+ sensors responding only to aberrantly high free zinc concentrations by denaturation and aggregation (NCALD), and (3) Zn2+-resistant, Ca2+ sensor proteins (GCAP1, GCAP2). We suggest that NCS proteins may there- fore govern the interconnection between Ca2+ dependent and Zn2+-dependent signaling pathways in healthy neurons and zinc cytotoxicity-related neurodegenerative diseases, such as Alzheimer’s disease and glaucoma.