Proteinopathies as Hallmarks of Impaired Gene Expression, Proteostasis and Mitochondrial Function in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disease characterized by progressive degeneration of upper and lower motor neurons. As with the majority of neurodegenerative diseases, the pathological hallmarks of ALS involve proteinopathies which lead to the formation of various polyubiquitylated protein aggregates in neurons and glia. ALS is a highly heterogeneous disease, with both familial and sporadic forms arising from the convergence of multiple disease mechanisms, many of which remain elusive. There has been considerable research effort invested into exploring these disease mechanisms and in recent years dysregulation of RNA metabolism and mitochondrial function have emerged as of crucial importance to the onset and development of ALS proteinopathies. Widespread alterations of the RNA metabolism and post-translational processing of proteins lead to the disruption of multiple biological pathways. Abnormal mitochondrial structure, impaired ATP production, dysregulation of energy metabolism and calcium homeostasis as well as apoptosis have been implicated in the neurodegenerative process. Dysfunctional mitochondria further accumulate in ALS motor neurons and reflect a wider failure of cellular quality control systems, including mitophagy and other autophagic processes. Here, we review the evidence for RNA and mitochondrial dysfunction as some of the earliest critical pathophysiological events leading to the development of ALS proteinopathies, explore their relative pathological contributions and their points of convergence with other key disease mechanisms. This review will focus primarily on mutations in genes causing four major types of ALS (C9ORF72, SOD1, TARDBP/TDP-43, and FUS) and in protein homeostasis genes (SQSTM1, OPTN, VCP, and UBQLN2) as well as sporadic forms of the disease. Finally, we will look to the future of ALS research and how an improved understanding of central mechanisms underpinning proteinopathies might inform research directions and have implications for the development of novel therapeutic approaches.

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Microphysiological 3D model of amyotrophic lateral sclerosis (ALS) from human iPS-derived muscle cells and optogenetic motor neurons

Science Advances ◽

10.1126/sciadv.aat5847 ◽

2018 ◽

Vol 4 (10) ◽

pp. eaat5847 ◽

Cited By ~ 66

Author(s):

Tatsuya Osaki ◽

Sebastien G. M. Uzel ◽

Roger D. Kamm

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Unit ◽

Motor Neurons ◽

Neuromuscular Junctions ◽

Research Effort ◽

Muscle Contractions ◽

Drug Candidates ◽

Chip Technology ◽

Sporadic Als ◽

Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease involving loss of motor neurons (MNs) and muscle atrophy, still has no effective treatment, despite much research effort. To provide a platform for testing drug candidates and investigating the pathogenesis of ALS, we developed an ALS-on-a-chip technology (i.e., an ALS motor unit) using three-dimensional skeletal muscle bundles along with induced pluripotent stem cell (iPSC)–derived and light-sensitive channelrhodopsin-2–induced MN spheroids from a patient with sporadic ALS. Each tissue was cultured in a different compartment of a microfluidic device. Axon outgrowth formed neuromuscular junctions on the muscle fiber bundles. Light was used to activate muscle contraction, which was measured on the basis of pillar deflections. Compared to a non-ALS motor unit, the ALS motor unit generated fewer muscle contractions, there was MN degradation, and apoptosis increased in the muscle. Furthermore, the muscle contractions were recovered by single treatments and cotreatment with rapamycin (a mechanistic target of rapamycin inhibitor) and bosutinib (an Src/c-Abl inhibitor). This recovery was associated with up-regulation of autophagy and degradation of TAR DNA binding protein–43 in the MNs. Moreover, administering the drugs via an endothelial cell barrier decreased the expression of P-glycoprotein (an efflux pump that transports bosutinib) in the endothelial cells, indicating that rapamycin and bosutinib cotreatment has considerable potential for ALS treatment. This ALS-on-a-chip and optogenetics technology could help to elucidate the pathogenesis of ALS and to screen for drug candidates.

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Mitochondrial bioenergetic deficits in C9orf72 amyotrophic lateral sclerosis motor neurons cause dysfunctional axonal homeostasis

Acta Neuropathologica ◽

10.1007/s00401-020-02252-5 ◽

2021 ◽

Author(s):

Arpan R. Mehta ◽

Jenna M. Gregory ◽

Owen Dando ◽

Roderick N. Carter ◽

Karen Burr ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Mitochondrial Function ◽

Genetic Manipulation ◽

Ventral Horn ◽

Post Mortem ◽

Mitochondrial Dna Copy Number ◽

Axonal Dysfunction ◽

Lateral Sclerosis

AbstractAxonal dysfunction is a common phenotype in neurodegenerative disorders, including in amyotrophic lateral sclerosis (ALS), where the key pathological cell-type, the motor neuron (MN), has an axon extending up to a metre long. The maintenance of axonal function is a highly energy-demanding process, raising the question of whether MN cellular energetics is perturbed in ALS, and whether its recovery promotes axonal rescue. To address this, we undertook cellular and molecular interrogation of multiple patient-derived induced pluripotent stem cell lines and patient autopsy samples harbouring the most common ALS causing mutation, C9orf72. Using paired mutant and isogenic expansion-corrected controls, we show that C9orf72 MNs have shorter axons, impaired fast axonal transport of mitochondrial cargo, and altered mitochondrial bioenergetic function. RNAseq revealed reduced gene expression of mitochondrially encoded electron transport chain transcripts, with neuropathological analysis of C9orf72-ALS post-mortem tissue importantly confirming selective dysregulation of the mitochondrially encoded transcripts in ventral horn spinal MNs, but not in corresponding dorsal horn sensory neurons, with findings reflected at the protein level. Mitochondrial DNA copy number was unaltered, both in vitro and in human post-mortem tissue. Genetic manipulation of mitochondrial biogenesis in C9orf72 MNs corrected the bioenergetic deficit and also rescued the axonal length and transport phenotypes. Collectively, our data show that loss of mitochondrial function is a key mediator of axonal dysfunction in C9orf72-ALS, and that boosting MN bioenergetics is sufficient to restore axonal homeostasis, opening new potential therapeutic strategies for ALS that target mitochondrial function.

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A review: Management of motor neuron diseases

IP Indian Journal of Neurosciences ◽

10.18231/j.ijn.2021.053 ◽

2022 ◽

Vol 7 (4) ◽

pp. 292-294

Author(s):

Aarti Chopra ◽

Ravi Kumar ◽

Girendra Kumar Gautam

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neuron ◽

Motor Neurons ◽

Age At Onset ◽

Motor Neuron Diseases ◽

Progressive Degeneration ◽

Review Management ◽

The Central Nervous System ◽

Lateral Sclerosis

Motor neuron diseases are a group of chronic sporadic and hereditary neurological disorders characterized by progressive degeneration of motor neurons. These might affect the upper motor neurons, lower motor neurons, or both. The prognosis of the motor neuron disease depends upon the age at onset and the area of the central nervous system affected. Amyotrophic lateral sclerosis (ALS) has been documented to be fatal within three years of onset. This activity focuses on amyotrophic lateral sclerosis as the prototype of MND, which affects both the upper and the lower motor neurons and discusses the role of inter-professional team in the differential diagnosis, evaluation, treatment, and prognostication. It also discusses various other phenotypes of MND with an emphasis on their distinguishing features in requisite detail.

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Pathogenic Genome Signatures That Damage Motor Neurons in Amyotrophic Lateral Sclerosis

Cells ◽

10.3390/cells9122687 ◽

2020 ◽

Vol 9 (12) ◽

pp. 2687

Author(s):

Ali Yousefian-Jazi ◽

YunHee Seol ◽

Jieun Kim ◽

Hannah L. Ryu ◽

Junghee Lee ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Genetic Variants ◽

Diagnostic Tests ◽

Neurodegenerative Disorder ◽

Therapeutic Approaches ◽

Causative Gene ◽

Disease Mechanisms ◽

Disease Modifying ◽

Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is the most frequent motor neuron disease and a neurodegenerative disorder, affecting the upper and/or lower motor neurons. Notably, it invariably leads to death within a few years of onset. Although most ALS cases are sporadic, familial amyotrophic lateral sclerosis (fALS) forms 10% of the cases. In 1993, the first causative gene (SOD1) of fALS was identified. With rapid advances in genetics, over fifty potentially causative or disease-modifying genes have been found in ALS so far. Accordingly, routine diagnostic tests should encompass the oldest and most frequently mutated ALS genes as well as several new important genetic variants in ALS. Herein, we discuss current literatures on the four newly identified ALS-associated genes (CYLD, S1R, GLT8D1, and KIF5A) and the previously well-known ALS genes including SOD1, TARDBP, FUS, and C9orf72. Moreover, we review the pathogenic implications and disease mechanisms of these genes. Elucidation of the cellular and molecular functions of the mutated genes will bring substantial insights for the development of therapeutic approaches to treat ALS.

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Amyotrophic lateral sclerosis: new perpectives and update

Neurology International ◽

10.4081/ni.2015.5885 ◽

2015 ◽

Vol 7 (2) ◽

Cited By ~ 25

Author(s):

Marco Orsini ◽

Acary Bulle Oliveira ◽

Osvaldo J.M. Nascimento ◽

Carlos Henrique Melo Reis ◽

Marco Antonio Araujo Leite ◽

...

Keyword(s):

Clinical Trials ◽

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Complex Disease ◽

Age Of Onset ◽

Effective Means ◽

Progressive Degeneration ◽

The Usa ◽

Eventual Death ◽

Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS), Charcot’s disease or Lou Gehrig’s disease, is a term used to cover the spetrum of syndromes caracterized by progressive degeneration of motor neurons, a paralytic disorder caused by motor neuron degeneration. Currently, there are approximately 25,000 patients with ALS in the USA, with an average age of onset of 55 years. The incidence and prevalence of ALS are 1-2 and 4-6 per 100,000 each year, respectively, with a lifetime ALS risk of 1/600 to 1/1000. It causes progressive and cumulative physical disabilities, and leads to eventual death due to respiratory muscle failure. ALS is diverse in its presentation, course, and progression. We do not yet fully understand the causes of the disease, nor the mechanisms for its progression; thus, we lack effective means for treating this disease. In this chapter, we will discuss the diagnosis, treatment, and how to cope with impaired function and end of life based on of our experience, guidelines, and clinical trials. Nowadays ALS seems to be a more complex disease than it did two decades – or even one decade – ago, but new insights have been plentiful. Clinical trials should be seen more as experiments on pathogenic mechanisms. A medication or combination of medications that targets more than one pathogenic pathway may slow disease progression in an additive or synergistic fashion.

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Destination Amyotrophic Lateral Sclerosis

Frontiers in Neurology ◽

10.3389/fneur.2021.596006 ◽

2021 ◽

Vol 12 ◽

Author(s):

Matt Keon ◽

Benjamin Musrie ◽

Marcel Dinger ◽

Samuel E. Brennan ◽

Jerran Santos ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Functional Convergence ◽

Progressive Degeneration ◽

Fundamental Dimension ◽

Multiple Levels ◽

Brain And Spinal Cord ◽

The Brain ◽

Lateral Sclerosis ◽

Philosophical Understanding

Amyotrophic Lateral Sclerosis (ALS) is a prototypical neurodegenerative disease characterized by progressive degeneration of motor neurons both in the brain and spinal cord. The constantly evolving nature of ALS represents a fundamental dimension of individual differences that underlie this disorder, yet it involves multiple levels of functional entities that alternate in different directions and finally converge functionally to define ALS disease progression. ALS may start from a single entity and gradually becomes multifactorial. However, the functional convergence of these diverse entities in eventually defining ALS progression is poorly understood. Various hypotheses have been proposed without any consensus between the for-and-against schools of thought. The present review aims to capture explanatory hierarchy both in terms of hypotheses and mechanisms to provide better insights on how they functionally connect. We can then integrate them within a common functional frame of reference for a better understanding of ALS and defining future treatments and possible therapeutic strategies. Here, we provide a philosophical understanding of how early leads are crucial to understanding the endpoints in ALS, because invariably, all early symptomatic leads are underpinned by neurodegeneration at the cellular, molecular and genomic levels. Consolidation of these ideas could be applied to other neurodegenerative diseases (NDs) and guide further critical thinking to unveil their roadmap of destination ALS.

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Deregulated miR-29b-3p Correlates with Tissue-Specific Activation of Intrinsic Apoptosis in An Animal Model of Amyotrophic Lateral Sclerosis

Cells ◽

10.3390/cells8091077 ◽

2019 ◽

Vol 8 (9) ◽

pp. 1077 ◽

Cited By ~ 3

Author(s):

Klatt ◽

Theis ◽

Hahn ◽

Theiss ◽

Matschke

Keyword(s):

Spinal Cord ◽

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Cervical Spinal Cord ◽

Intrinsic Apoptotic Pathway ◽

Apoptotic Pathway ◽

Tissue Specific ◽

Progressive Degeneration ◽

Lateral Sclerosis ◽

Apoptotic Cascade

Amyotrophic lateral sclerosis (ALS) is one of the most common incurable motor neuron disorders in adults. The majority of all ALS cases occur sporadically (sALS). Symptoms of ALS are caused by a progressive degeneration of motor neurons located in the motor cortex and spinal cord. The question arises why motor neurons selectively degenerate in ALS, while other cells and systems appear to be spared the disease. Members of the intrinsic apoptotic pathway are frequent targets of altered microRNA expression. Therefore, microRNAs and their effects on cell survival are subject of controversial debates. In this study, we investigated the expression of numerous members of the intrinsic apoptotic cascade by qPCR, western blot, and immunostaining in two different regions of the CNS of wobbler mice. Further we addressed the expression of miR-29b-3p targeting BMF, Bax, and, Bak, members of the apoptotic pathway. We show a tissue-specific differential expression of BMF, Bax, and cleaved-Caspase 3 in wobbler mice. An opposing regulation of miR-29b-3p expression in the cerebellum and cervical spinal cord of wobbler mice suggests different mechanisms regulating the intrinsic apoptotic pathway. Based on our findings, it could be speculated that miR-29b-3p might regulate antiapoptotic survival mechanisms in CNS areas that are not affected by neurodegeneration in the wobbler mouse ALS model.

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Emerging Evidence Highlighting the Importance of Redox Dysregulation in the Pathogenesis of Amyotrophic Lateral Sclerosis (ALS)

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2020.581950 ◽

2021 ◽

Vol 14 ◽

Author(s):

Cyril Jones Jagaraj ◽

Sonam Parakh ◽

Julie D. Atkin

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Redox Regulation ◽

Redox Homeostasis ◽

Antioxidant Defence ◽

Cellular Redox ◽

Disease Mechanisms ◽

Antioxidant Defence System ◽

Cellular Oxidation ◽

Lateral Sclerosis

The cellular redox state, or balance between cellular oxidation and reduction reactions, serves as a vital antioxidant defence system that is linked to all important cellular activities. Redox regulation is therefore a fundamental cellular process for aerobic organisms. Whilst oxidative stress is well described in neurodegenerative disorders including amyotrophic lateral sclerosis (ALS), other aspects of redox dysfunction and their contributions to pathophysiology are only just emerging. ALS is a fatal neurodegenerative disease affecting motor neurons, with few useful treatments. Hence there is an urgent need to develop more effective therapeutics in the future. Here, we discuss the increasing evidence for redox dysregulation as an important and primary contributor to ALS pathogenesis, which is associated with multiple disease mechanisms. Understanding the connection between redox homeostasis, proteins that mediate redox regulation, and disease pathophysiology in ALS, may facilitate a better understanding of disease mechanisms, and lead to the design of better therapeutic strategies.

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Exploring molecular approaches in Amyotrophic lateral sclerosis: Drug targets from clinical and pre-clinical findings

Current Molecular Pharmacology ◽

10.2174/1566524020666200427214356 ◽

2020 ◽

Vol 13 ◽

Author(s):

Mamtaj Alam ◽

Rajeshwar Kumar Yadav ◽

Elizabeth Minj ◽

Aarti Tiwari ◽

Sidharth Mehan

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Drug Targets ◽

Therapeutic Index ◽

Experimental Models ◽

Clinical Findings ◽

Adenyl Cyclase ◽

Molecular Approaches ◽

Pharmacologically Active ◽

Lateral Sclerosis

: Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease (MND) characterised by the death of upper and lower motor neurons (corticospinal tract) in the motor cortex, basal ganglia, brain stem, and spinal cord. The patient experiences the sign and symptoms between 55 to 75 years of age included impaired motor movement, difficulty in speaking and swallowing, grip loss, muscle atrophy, spasticity and sometimes associated with memory and cognitive impairments. Median survival is 3 to 5 years after diagnosis and 5 to 10% beyond 10 years of age. The limited intervention of pharmacologically active compounds that are used clinically is majorly associated with the narrow therapeutic index. Pre-clinically established experimental models where neurotoxin methyl mercury mimics the ALS like behavioural and neurochemical alterations in rodents associated with neuronal mitochondrial dysfunctions and downregulation of adenyl cyclase mediated cAMP/CREB is the main pathological hallmark for the progression of ALS in central as well in the peripheral nervous system. Despite the considerable investigation into neuroprotection, it still constrains treatment choices to strong care and organization of ALS complications. Therefore, current review specially targeted in the investigation of clinical and pre-clinical features available for ALS to understand the pathogenic mechanisms and to explore the pharmacological interventions associated with up-regulation of intracellular adenyl cyclase/cAMP/CREB and mitochondrial-ETC coenzyme-Q10 activation as a future drug target in the amelioration of ALS mediated motor neuronal dysfunctions.

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Riluzole Exhibits No Therapeutic Efficacy on a Transgenic Rat model of Amyotrophic Lateral Sclerosis

Current Neurovascular Research ◽

10.2174/1567202617666200409125227 ◽

2020 ◽

Vol 17 (3) ◽

pp. 275-285 ◽

Cited By ~ 5

Author(s):

Si Chen ◽

Qiao Liao ◽

Ke Lu ◽

Jinxia Zhou ◽

Cao Huang ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Rat Model ◽

Microglial Activation ◽

Transgenic Rat ◽

Intragastric Administration ◽

Behavioral Deficits ◽

Als Patients ◽

Lateral Sclerosis ◽

Transgenic Rat Model

Background: Amyotrophic lateral sclerosis (ALS) is a neurological disorder clinically characterized by motor system dysfunction, with intraneuronal accumulation of the TAR DNAbinding protein 43 (TDP-43) being a pathological hallmark. Riluzole is a primarily prescribed medicine for ALS patients, while its therapeutical efficacy appears limited. TDP-43 transgenic mice are existing animal models for mechanistic/translational research into ALS. Methods: We developed a transgenic rat model of ALS expressing a mutant human TDP-43 transgene (TDP-43M337V) and evaluated the therapeutic effect of Riluzole on this model. Relative to control, rats with TDP-43M337V expression promoted by the neurofilament heavy subunit (NEF) gene or specifically in motor neurons promoted by the choline acetyltransferase (ChAT) gene showed progressive worsening of mobility and grip strength, along with loss of motor neurons, microglial activation, and intraneuronal accumulation of TDP-43 and ubiquitin aggregations in the spinal cord. Results: Compared to vehicle control, intragastric administration of Riluzole (30 mg/kg/d) did not mitigate the behavioral deficits nor alter the neuropathologies in the transgenics. Conclusion: These findings indicate that transgenic rats recapitulate the basic neurological and neuropathological characteristics of human ALS, while Riluzole treatment can not halt the development of the behavioral and histopathological phenotypes in this new transgenic rodent model of ALS.

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