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Mitochondria play important roles in neuronal function and survival, including ATP production, Ca2+ buffering, and apoptosis. Mitochondrial dysfunction is a common event in the pathogenesis of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD); however, what causes the mitochondrial dysfunction remains unclear. Mitochondrial fission is mediated by dynamin-related protein 1 (DRP1) and fusion by mitofusin 1/2 (MFN1/2) and optic atrophy 1 (OPA1), which are essential for mitochondrial function. Mutations in the mitochondrial fission and fusion machinery lead to neurodegeneration. Thus, whether defective mitochondrial dynamics participates in ALS and HD requires further investigation. ALS is a fatal neurodegenerative disease characterized by upper and lower motor neuron loss. Mutations in Cu/Zn superoxide dismutase (SOD1) cause the most common familiar form of ALS by mechanisms not fully understood. Here, a new motor neuron-astrocyte coculture system was created and live-cell imaging was used to evaluate mitochondrial dynamics. Excessive mitochondrial fission was observed in mutant SOD1G93A motor neurons, correlating with impaired axonal transport and neuronal cell death. Inhibition of mitochondrial fission restored mitochondrial dynamics and protected neurons against SOD1G93A -induced mitochondrial fragmentation and neuronal cell death, implicating defects in mitochondrial dynamics in ALS pathogenesis. iv HD is an inherited neurodegenerative disorder caused by glutamine (Q) expansion in the polyQ region of the huntingtin (HTT) protein. In the current work, mutant HTT caused mitochondrial fragmentation in a polyQ-dependent manner in both primary cortical neurons and fibroblasts from human patients. An abnormal interaction between DRP1 and HTT was observed in mutant HTT mice and inhibition of mitochondrial fission or promotion of mitochondrial fusion restored mitochondrial dynamics and protected neurons against mutant HTT-induced cell death. Thus, mutant HTT may increase mitochondrial fission by elevating DRP1 GTPase activity, suggesting that mitochondrial dynamics plays a causal role in HD. In summary, rebalanced mitochondrial fission and fusion rescues neuronal cell death in ALS and HD, suggesting that mitochondrial dynamics could be the molecular mechanism underlying these diseases. Furthermore, DRP1 might be a therapeutic target to delay or prevent neurodegeneration.

Matrin3 (MATR3) is an RNA binding protein involved in many roles in the nucleus, such as chromatin architecture and gene expression regulation, modulating transcriptional and post-transcriptional processes as RNA splicing and mRNA stabilization. Nevertheless, some functions of MATR3 within the cells are not entirely clear. MATR3 has been associated with Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease that damages motor neuron (MN) cells and leads to progressive muscle paralysis and respiratory failure. A better understanding of MATR3 activity within cell physiology could represent an essential breakthrough for studying MATR3-associated pathologies. Using MATR3-silenced human pluripotent stem cell (hiPSC) line model, we collected data on the MATR3 role in the pluripotency and in the neural induction and differentiation. We found that the downregulation of MATR3 alters the expression level of crucial self-renewal factors such as OCT4, NANOG, KLF4, and LIN28A. We observed MATR3 acts at multiple levels of the gene expression, i.e. regulating YTHDF1 expression, and in RNA metabolism, having a role in mRNA stabilization and translation. The reduction of stemness potential caused by MATR3 downregulation creates a defect during the neurodifferentiation process, which does not arrest motor neurons formation but induces selective alterations that may affect motor neurons functionality. Indeed, several morphological and molecular abnormalities were observed during the neuronal differentiation, such as the alterations of the formation of neuroepithelial rosettes that arise in a reduction of neurite lengths and arborization in neuronal cells. On this basis, we investigated neuronal differentiation in the brain organoids grown from iPSCs derived from ALS patients fibroblasts. We show, for the first time, that MATR3 is a critical factor in orchestrating the stemness network through transcriptional, post-transcriptional, and translational regulation, therefore affecting the differentiation of mature neurons.

Parkinson’s disease is one of the most common neurodegenerative disorders worldwide, characterized by a progressive loss of dopaminergic neurons mainly localized in the substantia nigra pars compacta. In recent years, the detailed analyses of both genetic and idiopathic forms of the disease have led to a better understanding of the molecular and cellular pathways involved in PD, pointing to the centrality of mitochondrial dysfunctions in the pathogenic process. Failure of mitochondrial quality control is now considered a hallmark of the disease. The peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1) family acts as a master regulator of mitochondrial biogenesis. Therefore, keeping PGC-1 level in a proper range is fundamental to guarantee functional neurons. Here we review the major findings that tightly bond PD and PGC-1s, raising important points that might lead to future investigations.

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Yes / Despite a wealth of activity across the globe in the area of longitudinal population cohorts, surprisingly little information is available on the natural biomedical history of a number of age-related neurodegenerative diseases (ND), and the scope for intervention studies based on these cohorts is only just beginning to be explored. The Joint Programming Initiative on Neurodegenerative Disease Research (JPND) recently developed a novel funding mechanism to rapidly mobilise scientists to address these issues from a broad, international community perspective. Ten expert Working Groups, bringing together a diverse range of community members and covering a wide ND landscape (Alzheimer’s, Parkinson’s, frontotemporal degeneration, amyotrophic lateral sclerosis, Lewy-body and vascular dementia) were formed to discuss and propose potential approaches to better exploiting and coordinating cohort studies. The purpose of this work is to highlight the novel funding process along with a broad overview of the guidelines and recommendations generated by the ten groups, which include investigations into multiple methodologies such as cognition/functional assessment, biomarkers and biobanking, imaging, health and social outcomes, and pre-symptomatic ND. All of these were published in reports that are now publicly available online.

Ce manuscrit détaille la stratégie utilisée par nos laboratoires pour identifier de nouvelles molécules neuroprotectrices pour le traitement curatif de la maladie de Parkinson (MP). La MP est une maladie neurodégénérative caractérisée par des symptômes moteurs invalidants qui résultent de la dégénérescence des neurones dopaminergiques (DA) des noyaux gris centraux. Précédemment, nos laboratoires ont synthétisé et identifié au cours d’un criblage 3 molécules chefs de file qui possèdent un effet neurotrophique sur les neurones DA embryonnaires. Des études préliminaires d’ADMEtox nous ont permis de sélectionner la molécule SF41, un dérivé 6-aminoquinoxaline, pour une première évaluation de l’effet neuroprotecteur in vivo de nos molécules. En effet, cette molécule est bien tolérée chez l’animal et, administrée par voie orale, elle est capable de traverser la BHE. SF41 a montré un faible effet protecteur vis-à-vis des fibres DA dans un modèle animal de la MP. Dans le but d’augmenter l’activité neurotrophique de cette molécule, une 50ène de dérivés de seconde génération ont été synthètisés et criblés in vitro dans un modèle de mort spontanée des neurones DA. Ce criblage nous a permis d’identifier 5 molécules lead plus puisssantes et efficaces que SF41. Ces molécules, qui possédent les mêmes propriétés physico-chimiques que SF41, pourraient également atteindre le système nerveux central et ainsi conduire à un effet neuroprotecteur marqué dans un modèle animal de la MP. De plus, ces molécules possèdent un profil pharmacologique intéressant car elles sont capables d’empêcher la mise en place de mécanismes qui peuvent potentiellement contribuer à la mort des neurones DA dans la MP (stress oxydant, stress médié par les astrocytes, dyshoméostasie calcique, stress médié par la diminution en facteur trophique…). Une étude préliminaire avec la molécule PAQ, l’une de ces 5 molécules, a permis d’obtenir un effet neuroprotecteur dans un modèle in vivo de la MP qui semble supérieur à celui de la molécule SF41. Ces résultats encourageants nous donnent bon espoir d’obtenir la preuve de concept de l’activité neuroprotectrice de nos dérivés 6-aminoquinoxaline. / This manuscript describes the strategy used by our laboratories to identify new neuroprotective molecules for the therapy of Parkinson disease (PD). PD is a neurodegenerative disease characterized by disabling motor symptoms resulting from the degeneration of dopaminergic (DA) neurons of the basal ganglia. Previously, our laboratories have synthesized and identified in a screening 3 lead compound which exhibited a neurotrophic effect on embryonic midbrain DA neurons. Preliminary ADMEtox studies allowed us to select the molecule SF41, a 6-aminoquinoxaline derivative, for a first in vivo evaluation of the neuroprotective effect of our molecules in an animal model of PD. Indeed, SF41 is well tolerated in animals and is able of crossing the BBB after oral treatment. SF41 showed a weak protective effect on DA fibers in an animal model of PD.In order to increase the neurotrophic activity of this molecule, around fifty second generation derivatives were synthesized and screened in vitro in a model of spontaneous death of DA neurons. This screening allowed us to identify five lead compounds more powerful and effective than SF41. These molecules, which possess the same physico-chemical properties that SF41, could also reach the central nervous system and lead to a marked neuroprotective effect in an animal model of PD. In addition, these molecules have an interesting pharmacological profile because they are able to prevent the establishment of mechanisms that can potentially contribute to the death of DA neurons in PD (oxidative stress, stress mediated by astrocytes, calcium dyshomeostasis, stress mediated by trophic factor deprivation...).A preliminary study with the molecule PAQ, one of these five molecules, yielded a neuroprotective effect in animal model of PD that seems higher than with SF41. These encouraging results give us hope to achieve proof of concept of the neuroprotective activity of our 6-aminoquinoxaline derivatives.

Glycogen is the sole carbohydrate storage molecule found in mammalian cells and plays an important role in cellular metabolism in nearly all tissues, including the brain. Defects in glycogen metabolism underlie the glycogen storage diseases (GSDs), genetic disorders with variable clinical phenotypes depending on the mutation type and affected gene(s). Lafora disease (LD) is a fatal form of progressive myoclonus epilepsy and a non-classical GSD. LD typically manifests in adolescence with tonic-clonic seizures, myoclonus, and a rapid, insidious progression. Patients experience increasingly severe and frequent epileptic episodes, loss of speech and muscular control, disinhibited dementia, and severe cognitive decline; death usually ensues in the second decade of life. LD, like one- third of all epilepsy disorders, is intractable and resistant to antiseizure drugs. A hallmark of LD is the accumulation of intracellular, insoluble carbohydrate aggregates known as Lafora bodies (LBs) in brain, muscle, and other tissues. LBs are a type of polyglucosan body, an insoluble aggregate of aberrant glycogen found in some GSDs and neurodegenerative disorders. Like most GSDs, LD is an autosomal recessive genetic disorder. Approximately 50% of LD patients carry mutations in the epilepsy, progressive myoclonus 2A (EPM2A) gene encoding laforin, a glycogen phosphatase. Remaining patients carry mutations in EPM2B, the gene that encodes malin, an E3 ubiquitin ligase. Laforin and malin play important roles in glycogen metabolism. In the absence of either enzyme, glycogen transforms into an insoluble, hyperphosphorylated and aberrantly branched polysaccharide reminiscent of plant starch. This abnormal polysaccharide precipitates to form LBs and has pathological consequences in the brain. Since a definitive LD diagnosis requires genetic testing, whole exome sequencing has been increasingly used to diagnose LD. As a result, numerous cases of more slowly progressing or late-onset LD have been discovered that are associated with missense mutations in EPM2A or EPM2B. Over 50 EPM2A missense mutations have been described. These mutations map to many regions of the laforin X-ray crystal structure, suggesting they produce a spectrum of effects on laforin function. In the present work, a biochemical pipeline was developed to characterize laforin patient mutations. The mutations fall into distinct classes with mild, moderate or severe effects on laforin function, providing a biochemical explanation for less severe forms of LD. LBs drive LD pathology. As a result, LBs and glycogen metabolism have become therapeutic targets. Since LBs are starch-like, and starch is degraded by amylases, these enzymes are potential therapeutics for reducing LB loads in vivo. However, amylases are normally secreted enzymes. Degradation of intracellular LBs requires a cell-penetrating delivery platform. Herein, an antibody-enzyme fusion (AEF) technology was developed to degrade LBs in vitro, in situ in cell culture, and in vivo in LD mouse models. AEFs are a now putative precision therapy for LD, potentially the first therapeutic to provide a significant clinical benefit. Prior to this work, LD was considered a homogenous disorder and treatments were only palliative. The data herein support a spectrum of clinical progression, a potential therapy for LD, and mechanistic insights into LD pathophysiology. This work illustrates how personalized medicine, both in diagnosis and treatment, can be achieved through basic biochemical approaches to human disease.

Friedreich's Ataxia (FA) is an autosomal-recessive, neurodegenerative disease characterized by progressive lower extremity muscle weakness and sensory loss, balance deficits, limb and gait ataxia, and dysarthria. FA is considered a sensory ataxia because the dorsal root ganglia and spinal cord dorsal columns are involved early in the disease, whereas the cerebellum is affected later. Balance deficits and gait ataxia are often evaluated clinically and in research using clinical rating scales. Recently, quantitative tools such as the Biodex Balance System SD and the GAITRite Walkway System have become available to objectively assess balance and gait, respectively. However, there are limited studies using instrumented measures to quantitatively assess and characterize balance and gait disturbances in FA, and longitudinal, quantitative analyses of both balance and gait have not been investigated in this patient cohort. The purpose of the present study was to characterize gait patterns of adults with FA and to identify changes in gait and balance over time using clinical rating scales and quantitative measures. Additionally, this study investigated the relationship between disease duration, clinical rating scale scores and objective measures of gait and balance. This study used a longitudinal research design to investigate changes in balance and gait in 8 adults with genetically confirmed FA and 8 healthy controls matched for gender, age, height, and weight. Subjects with FA were evaluated using the Berg Balance Scale (BBS), the Friedreich's Ataxia Rating Scale (FARS) and instrumented gait and balance measures at baseline, 6 months, 12 months and 24 months. Controls underwent the same tests at baseline and 12 months. Gait parameters were measured utilizing the GAITRite Walkway system with a focus on gait velocity, cadence, step and stride lengths, step and stride length variability and percent of the gait cycle in swing, stance and double limb support. Balance was assessed using the BBS and the Biodex Balance System; the latter included tests of postural stability and limits of stability. At baseline, there were significant differences in gait and balance parameters, BBS scores and FARS total scores between FA subjects and controls as determined using paired t-tests (p This is the first longitudinal study to demonstrate changes over time in gait and balance of adults with FA using both quantitative measures and clinical rating scales. This study provided a detailed characterization of the gait pattern and balance of adults with FA. The GAITRite Walkway system proved to be a sensitive measure, and able to detect subtle changes in gait parameters over time in adults with FA. In addition, the BBS was an appropriate and sensitive assessment to detect changes in static and dynamic balance in this patient cohort. Finally, results revealed a strong and consistent relationship between clinical rating scale scores, postural stability indices, limits of stability scores, and step and stride length variability in individuals with FA.