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1.
Aromatic l-amino acid decarboxylase deficiency: a patient-derived neuronal model for precision therapies.
Rossignoli, G, Krämer, K, Lugarà, E, Alrashidi, H, Pope, S, De La Fuente Barrigon, C, Barwick, K, Bisello, G, Ng, J, Counsell, J, et al
Brain : a journal of neurology. 2021;(8):2443-2456
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Abstract
Aromatic l-amino acid decarboxylase (AADC) deficiency is a complex inherited neurological disorder of monoamine synthesis which results in dopamine and serotonin deficiency. The majority of affected individuals have variable, though often severe cognitive and motor delay, with a complex movement disorder and high risk of premature mortality. For most, standard pharmacological treatment provides only limited clinical benefit. Promising gene therapy approaches are emerging, though may not be either suitable or easily accessible for all patients. To characterize the underlying disease pathophysiology and guide precision therapies, we generated a patient-derived midbrain dopaminergic neuronal model of AADC deficiency from induced pluripotent stem cells. The neuronal model recapitulates key disease features, including absent AADC enzyme activity and dysregulated dopamine metabolism. We observed developmental defects affecting synaptic maturation and neuronal electrical properties, which were improved by lentiviral gene therapy. Bioinformatic and biochemical analyses on recombinant AADC predicted that the activity of one variant could be improved by l-3,4-dihydroxyphenylalanine (l-DOPA) administration; this hypothesis was corroborated in the patient-derived neuronal model, where l-DOPA treatment leads to amelioration of dopamine metabolites. Our study has shown that patient-derived disease modelling provides further insight into the neurodevelopmental sequelae of AADC deficiency, as well as a robust platform to investigate and develop personalized therapeutic approaches.
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SIRT1 Promotes Neuronal Fortification in Neurodegenerative Diseases through Attenuation of Pathological Hallmarks and Enhancement of Cellular Lifespan.
Mishra, P, Mittal, AK, Kalonia, H, Madan, S, Ghosh, S, Sinha, JK, Rajput, SK
Current neuropharmacology. 2021;(7):1019-1037
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Abstract
Neurodegeneration is a complex neurological phenomenon characterized by disturbed coherence in neuronal efflux. Progressive neuronal loss and brain damage due to various age-related pathological hallmarks perturb the behavioral balance and quality of life. Sirtuins have been widely investigated for their neuroprotective role, with SIRT1 being the most contemplated member of the family. SIRT1 exhibits significant capabilities to enhance neurogenesis and cellular lifespan by regulating various pathways, which makes it an exciting therapeutic target to inhibit neurodegenerative disease progression. SIRT1 mediated neuronal fortification involves modulation of molecular co-factors and biochemical pathways responsible for the induction and sustenance of pro-inflammatory and pro-oxidative environment in the cellular milieu. In this review, we present the major role played by SIRT1 in maintaining cellular strength through the regulation of genomic stability, neuronal growth, energy metabolism, oxidative stress, inhibiting mechanisms and anti-inflammatory responses. The therapeutic significance of SIRT1 has been put into perspective through a comprehensive discussion about its ameliorating potential against neurodegenerative stimuli in a variety of diseases that characteristically impair cognition, memory and motor coordination. This review enhances the acquaintance concerned with the neuroprotective potential of SIRT1 and thus promotes the development of novel SIRT1 regulating therapeutic agents and strategies.
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Alteration of Flavin Cofactor Homeostasis in Human Neuromuscular Pathologies.
Tolomeo, M, Nisco, A, Barile, M
Methods in molecular biology (Clifton, N.J.). 2021;:275-295
Abstract
The aim of this short review chapter is to provide a brief summary of the relevance of riboflavin (Rf or vitamin B2) and its derived cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) for human neuromuscular bioenergetics.Therefore, as a completion of this book we would like to summarize what kind of human pathologies could derive from genetic disturbances of Rf transport, flavin cofactor synthesis and delivery to nascent apoflavoproteins, as well as by alteration of vitamin recycling during protein turnover.
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The role of Bcl-2 proteins in modulating neuronal Ca2+ signaling in health and in Alzheimer's disease.
Callens, M, Kraskovskaya, N, Derevtsova, K, Annaert, W, Bultynck, G, Bezprozvanny, I, Vervliet, T
Biochimica et biophysica acta. Molecular cell research. 2021;(6):118997
Abstract
The family of B-cell lymphoma-2 (Bcl-2) proteins exerts key functions in cellular health. Bcl-2 primarily acts in mitochondria where it controls the initiation of apoptosis. However, during the last decades, it has become clear that this family of proteins is also involved in controlling intracellular Ca2+ signaling, a critical process for the function of most cell types, including neurons. Several anti- and pro-apoptotic Bcl-2 family members are expressed in neurons and impact neuronal function. Importantly, expression levels of neuronal Bcl-2 proteins are affected by age. In this review, we focus on the emerging roles of Bcl-2 proteins in neuronal cells. Specifically, we discuss how their dysregulation contributes to the onset, development, and progression of neurodegeneration in the context of Alzheimer's disease (AD). Aberrant Ca2+ signaling plays an important role in the pathogenesis of AD, and we propose that dysregulation of the Bcl-2-Ca2+ signaling axis may contribute to the progression of AD and that herein, Bcl-2 may constitute a potential therapeutic target for the treatment of AD.
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Genetically engineered MAPT 10+16 mutation causes pathophysiological excitability of human iPSC-derived neurons related to 4R tau-induced dementia.
Kopach, O, Esteras, N, Wray, S, Abramov, AY, Rusakov, DA
Cell death & disease. 2021;(8):716
Abstract
Human iPSC lines represent a powerful translational model of tauopathies. We have recently described a pathophysiological phenotype of neuronal excitability of human cells derived from the patients with familial frontotemporal dementia and parkinsonism (FTDP-17) caused by the MAPT 10+16 splice-site mutation. This mutation leads to the increased splicing of 4R tau isoforms. However, the role of different isoforms of tau protein in initiating neuronal dementia-related dysfunction, and the causality between the MAPT 10+16 mutation and altered neuronal activity have remained unclear. Here, we employed genetically engineered cells, in which the IVS10+16 mutation was introduced into healthy donor iPSCs to increase the expression of 4R tau isoform in exon 10, aiming to explore key physiological traits of iPSC-derived MAPT IVS10+16 neurons using patch-clamp electrophysiology and multiphoton fluorescent imaging techniques. We found that during late in vitro neurogenesis (from ~180 to 230 days) iPSC-derived cortical neurons of the control group (parental wild-type tau) exhibited membrane properties compatible with "mature" neurons. In contrast, MAPT IVS10+16 neurons displayed impaired excitability, as reflected by a depolarized resting membrane potential, an increased input resistance, and reduced voltage-gated Na+- and K+-channel-mediated currents. The mutation changed the channel properties of fast-inactivating Nav and decreased the Nav1.6 protein level. MAPT IVS10+16 neurons exhibited reduced firing accompanied by a changed action potential waveform and severely disturbed intracellular Ca2+ dynamics, both in the soma and dendrites, upon neuronal depolarization. These results unveil a causal link between the MAPT 10+16 mutation, hence overproduction of 4R tau, and a dysfunction of human cells, identifying a biophysical basis of changed neuronal activity in 4R tau-triggered dementia. Our study lends further support to using iPSC lines as a suitable platform for modelling tau-induced human neuropathology in vitro.
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Nonequilibrium molecular dynamics simulations of infrared laser-induced dissociation of a tetrameric Aβ42 β-barrel in a neuronal membrane model.
Man, VH, Wang, J, Derreumaux, P, Nguyen, PH
Chemistry and physics of lipids. 2021;:105030
Abstract
Experimental studies have reported that the amyloid-β proteins can form pores in cell membranes, and this could be one possible source of toxicity in Alzheimer's disease. Dissociation of these pores could therefore be a potential therapeutic approach. It is known that high photon density free-electron laser experiments and laser-induced nonequilibrium molecular dynamics simulations (NEMD) can dissociate amyloid fibrils at specific frequencies in vitro. Our question is whether NEMD simulations can dissociate amyloid pores in a bilayer mimicking a neuronal membrane, and as an example, we select a tetrameric Aβ42 β-barrel. Our simulations shows that the resonance between the laser field and the amide I vibrational mode of the barrel destabilises all intramolecular and intermolecular hydrogen bonds of Aβ42 and converts the β-barrel to a random/coil disordered oligomer. Starting from this disordered oligomer, extensive standard MD simulations shows sampling of disordered Aβ42 states without any increase of β-sheet and reports that the orientational order of lipids is minimally disturbed. Interestingly, the frequency to be employed to dissociate this beta-barrel is specific to the amino acid sequence. Taken together with our previous simulation results, this study indicates that infrared laser irradiation can dissociate amyloid fibrils and oligomers in bulk solution and in a membrane environment without affecting the surrounding molecules, offering therefore a promising way to retard the progression of AD.
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Generation and long-term culture of advanced cerebral organoids for studying later stages of neural development.
Giandomenico, SL, Sutcliffe, M, Lancaster, MA
Nature protocols. 2021;(2):579-602
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Abstract
Cerebral organoids, or brain organoids, can be generated from a wide array of emerging technologies for modeling brain development and disease. The fact that they are cultured in vitro makes them easily accessible both genetically and for live assays such as fluorescence imaging. In this Protocol Extension, we describe a modified version of our original protocol (published in 2014) that can be used to reliably generate cerebral organoids of a telencephalic identity and maintain long-term viability for later stages of neural development, including axon outgrowth and neuronal maturation. The method builds upon earlier cerebral organoid methodology, with modifications of embryoid body size and shape to increase surface area and slice culture to maintain nutrient and oxygen access to the interior regions of the organoid, enabling long-term culture. We also describe approaches for introducing exogenous plasmid constructs and for sparse cell labeling to image neuronal axon outgrowth and maturation over time. Together, these methods allow for modeling of later events in cortical development, which are important for neurodevelopmental disease modeling. The protocols described can be easily performed by an experimenter with stem cell culture experience and take 2-3 months to complete, with long-term maturation occurring over several months.
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The effect of sodium channels on neurological/neuronal disorders: A systematic review.
Bagheri, S, Haddadi, R, Saki, S, Kourosh-Arami, M, Komaki, A
International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience. 2021;(8):669-685
Abstract
Neurological and neuronal disorders are associated with structural, biochemical, or electrical abnormalities in the nervous system. Many neurological diseases have not yet been discovered. Interventions used for the treatment of these disorders include avoidance measures, lifestyle changes, physiotherapy, neurorehabilitation, pain management, medication, and surgery. In the sodium channelopathies, alterations in the structure, expression, and function of voltage-gated sodium channels (VGSCs) are considered as the causes of neurological and neuronal diseases. Online databases, including Scopus, Science Direct, Google Scholar, and PubMed were assessed for studies published between 1977 and 2020 using the keywords of review, sodium channels blocker, neurological diseases, and neuronal diseases. VGSCs consist of one α subunit and two β subunits. These subunits are known to regulate the gating kinetics, functional characteristics, and localization of the ion channel. These channels are involved in cell migration, cellular connections, neuronal pathfinding, and neurite outgrowth. Through the VGSC, the action potential is triggered and propagated in the neurons. Action potentials are physiological functions and passage of impermeable ions. The electrophysiological properties of these channels and their relationship with neurological and neuronal disorders have been identified. Subunit mutations are involved in the development of diseases, such as epilepsy, multiple sclerosis, autism, and Alzheimer's disease. Accordingly, we conducted a review of the link between VGSCs and neurological and neuronal diseases. Also, novel therapeutic targets were introduced for future drug discoveries.
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Directly Reprogrammed Human Neurons to Understand Age-Related Energy Metabolism Impairment and Mitochondrial Dysfunction in Healthy Aging and Neurodegeneration.
Gudenschwager, C, Chavez, I, Cardenas, C, Gonzalez-Billault, C
Oxidative medicine and cellular longevity. 2021;:5586052
Abstract
Brain aging is characterized by several molecular and cellular changes grouped as the hallmarks or pillars of aging, including organelle dysfunction, metabolic and nutrition-sensor changes, stem cell attrition, and macromolecular damages. Separately and collectively, these features degrade the most critical neuronal function: transmission of information in the brain. It is widely accepted that aging is the leading risk factor contributing to the onset of the most prevalent pathological conditions that affect brain functions, such as Alzheimer's, Parkinson's, and Huntington's disease. One of the limitations in understanding the molecular mechanisms involved in those diseases is the lack of an appropriate cellular model that recapitulates the "aged" context in human neurons. The advent of the cellular reprogramming of somatic cells, i.e., dermal fibroblasts, to obtain directly induced neurons (iNs) and induced pluripotent stem cell- (iPSC-) derived neurons is technical sound advances that could open the avenues to understand better the contribution of aging toward neurodegeneration. In this review, we will summarize the commonalities and singularities of these two approaches for the study of brain aging, with an emphasis on the role of mitochondrial dysfunction and redox biology. We will address the evidence showing that iNs retain age-related features in contrast to iPSC-derived neurons that lose the aging signatures during the reprogramming to pluripotency, rendering iNs a powerful strategy to deepen our knowledge of the processes driving normal cellular function decline and neurodegeneration in a human adult model. We will finally discuss the potential utilization of these novel technologies to understand the differential contribution of genetic and epigenetic factors toward neuronal aging, to identify and develop new drugs and therapeutic strategies.
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Expression and Localization of AβPP in SH-SY5Y Cells Depends on Differentiation State.
Riegerová, P, Brejcha, J, Bezděková, D, Chum, T, Mašínová, E, Čermáková, N, Ovsepian, SV, Cebecauer, M, Štefl, M
Journal of Alzheimer's disease : JAD. 2021;(2):485-491
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Abstract
Neuroblastoma cell line SH-SY5Y, due to its capacity to differentiate into neurons, easy handling, and low cost, is a common experimental model to study molecular events leading to Alzheimer's disease (AD). However, it is prevalently used in its undifferentiated state, which does not resemble neurons affected by the disease. Here, we show that the expression and localization of amyloid-β protein precursor (AβPP), one of the key molecules involved in AD pathogenesis, is dramatically altered in SH-SY5Y cells fully differentiated by combined treatment with retinoic acid and BDNF. We show that insufficient differentiation of SH-SY5Y cells results in AβPP mislocalization.