Adult-onset Motor Neuron Disease Research Articles

TDP-43 regulates LC3ylation in neural tissue through ATG4B cryptic splicing inhibition

Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease with a mean survival time of three years. The 97% of the cases have TDP-43 nuclear depletion and cytoplasmic aggregation in motor neurons. TDP-43 prevents non-conserved cryptic exon splicing in certain genes, maintaining transcript stability, including ATG4B, which is crucial for autophagosome maturation and Microtubule-associated proteins 1A/1B light chain 3B (LC3B) homeostasis. In ALS mice (G93A), Atg4b depletion worsens survival rates and autophagy function. For the first time, we observed an elevation of LC3ylation in the CNS of both ALS patients and atg4b−/− mouse spinal cords. Furthermore, LC3ylation modulates the distribution of ATG3 across membrane compartments. Antisense oligonucleotides (ASOs) targeting cryptic exon restore ATG4B mRNA in TARDBP knockdown cells. We further developed multi-target ASOs targeting TDP-43 binding sequences for a broader effect. Importantly, our ASO based in peptide-PMO conjugates show brain distribution post-IV administration, offering a non-invasive ASO-based treatment avenue for neurodegenerative diseases.

The clinical practice guideline for the management of amyotrophic lateral sclerosis in Japan-update 2023.

Amyotrophic lateral sclerosis (ALS) is an adult-onset intractable motor neuron disease characterized by selective degeneration of cortical neurons in the frontotemporal lobe and motor neurons in the brainstem and spinal cord. Impairment of these neural networks causes progressive muscle atrophy and weakness that spreads throughout the body, resulting in life-threatening bulbar palsy and respiratory muscle paralysis. However, no therapeutic strategy has yet been established to halt ALS progression. Although evidence for clinical practice in ALS remains insufficient, novel research findings have steadily accumulated in recent years. To provide updated evidence-based or expert consensus recommendations for the diagnosis and management of ALS, the ALS Clinical Practice Guideline Development Committee, approved by the Japanese Society of Neurology, revised and published the Japanese clinical practice guidelines for the management of ALS in 2023. In this guideline, disease-modifying therapies that have accumulated evidence from randomized controlled trials were defined as "Clinical Questions," in which the level of evidence was determined by systematic reviews. In contrast, "Questions and Answers" were defined as issues of clinically important but insufficient evidence, according to reports of a small number of cases, observational studies, and expert opinions. Based on a literature search performed in February 2022, recommendations were reached by consensus, determined by an independent panel, reviewed by external reviewers, and submitted for public comments by Japanese Society of Neurology members before publication. In this article, we summarize the revised Japanese guidelines for ALS, highlighting the regional and cultural diversity of care processes and decision-making. The guidelines cover a broad range of essential topics such as etiology, diagnostic criteria, disease monitoring and treatments, management of symptoms, respiration, rehabilitation, nutrition, metabolism, patient instructions, and various types of care support. We believe that this summary will help improve the daily clinical practice for individuals living with ALS and their caregivers.

Probable Kennedy Disease Mimicking Hirayama Disease: A Case Report

Spinal and bulbar muscular atrophy (Kennedy disease) is an X-linked, adult-onset motor neuron disease characterized by slow, progressive weakness of the bulbar and extremity muscles with CAG triplet repeat expansion in the androgen receptor gene. Hirayama disease (HD) is characterized by the juvenile onset of asymmetric weakness and amyotrophy of the hand and is most common in males in Asia. We report a patient with atypical Kennedy disease presenting with asymmetric hand weakness and atrophy typical of HD.

Skeletal muscle in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS), the major adult-onset motor neuron disease, has been viewed almost exclusively as a disease of upper and lower motor neurons, with muscle changes interpreted as a consequence of the progressive loss of motor neurons and neuromuscular junctions. This has led to the prevailing view that the involvement of muscle in ALS is only secondary to motor neuron loss. Skeletal muscle and motor neurons reciprocally influence their respective development and constitute a single functional unit. In ALS, multiple studies indicate that skeletal muscle dysfunction might contribute to progressive muscle weakness, as well as to the final demise of neuromuscular junctions and motor neurons. Furthermore, skeletal muscle has been shown to participate in disease pathogenesis of several monogenic diseases closely related to ALS. Here, we move the narrative towards a better appreciation of muscle as a contributor of disease in ALS. We review the various potential roles of skeletal muscle cells in ALS, from passive bystanders to active players in ALS pathophysiology. We also compare ALS to other motor neuron diseases and draw perspectives for future research and treatment.

Synucleinopathy in Amyotrophic Lateral Sclerosis: A Potential Avenue for Antisense Therapeutics?

Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease classified as both a neurodegenerative and neuromuscular disorder. With a complex aetiology and no current cure for ALS, broadening the understanding of disease pathology and therapeutic avenues is required to progress with patient care. Alpha-synuclein (αSyn) is a hallmark for disease in neurodegenerative disorders, such as Parkinson’s disease, Lewy body dementia, and multiple system atrophy. A growing body of evidence now suggests that αSyn may also play a pathological role in ALS, with αSyn-positive Lewy bodies co-aggregating alongside known ALS pathogenic proteins, such as SOD1 and TDP-43. This review endeavours to capture the scope of literature regarding the aetiology and development of ALS and its commonalities with “synucleinopathy disorders”. We will discuss the involvement of αSyn in ALS and motor neuron disease pathology, and the current theories and strategies for therapeutics in ALS treatment, as well as those targeting αSyn for synucleinopathies, with a core focus on small molecule RNA technologies.

NR1D1 downregulation in astrocytes induces a phenotype that is detrimental to cocultured motor neurons.

Nuclear receptor subfamily 1 group D member 1 (NR1D1, also known as Rev‐erbα) is a nuclear transcription factor that is part of the molecular clock encoding circadian rhythms and may link daily rhythms with metabolism and inflammation. NR1D1, unlike most nuclear receptors, lacks a ligand‐dependent activation function domain 2 and is a constitutive transcriptional repressor. Amyotrophic lateral sclerosis (ALS) is the most common adult‐onset motor neuron disease, caused by the progressive degeneration of motor neurons in the spinal cord, brain stem, and motor cortex. Approximately 10%–20% of familial ALS is caused by a toxic gain‐of‐function induced by mutations of the Cu/Zn superoxide dismutase (SOD1). Dysregulated clock and clock‐controlled gene expression occur in multiple tissues from mutant hSOD1‐linked ALS mouse models. Here we explore NR1D1 dysregulation in the spinal cord of ALS mouse models and its consequences on astrocyte–motor neuron interaction. NR1D1 protein and mRNA expression are significantly downregulated in the spinal cord of symptomatic mice expressing mutant hSOD1, while no changes were observed in age‐matched animals overexpressing wild‐type hSOD1. In addition, NR1D1 downregulation in primary astrocyte cultures induces a pro‐inflammatory phenotype and decreases the survival of cocultured motor neurons. NR1D1 orchestrates the cross talk between physiological pathways identified to be disrupted in ALS (e.g., metabolism, inflammation, redox homeostasis, and circadian rhythms) and we observed that downregulation of NR1D1 alters astrocyte–motor neuron interaction. Our results suggest that NR1D1 could be a potential therapeutic target to prevent astrocyte‐mediated motor neuron toxicity in ALS.

Ultrasonographic evaluation reveals thinning of cervical nerve roots and peripheral nerves in spinal and bulbar muscular atrophy.

Ultrasonography (US) is a noninvasive and patient-friendly tool for the evaluation of peripheral nerves. In motor neuron diseases, amyotrophic lateral sclerosis (ALS) has been reported to show the atrophy of peripheral nerves on US. However, the US findings are still unclear in spinal and bulbar muscular atrophy (SBMA), an adult-onset lower motor neuron disease caused by an abnormal CAG repeat expansion in the androgen receptor gene. We prospectively recruited and evaluated 11 patients with genetically confirmed SBMA and 9 patients with ALS diagnosed according to the revised El Escorial ALS criteria or the Awaji electrodiagnostic criteria. The C5-C7 cervical nerve roots and the median and ulnar nerves were evaluated ultrasonographically. The cross-sectional areas (CSAs) of the C6 and C7 nerve roots, the median nerve in the upper arm and forearm, and the ulnar nerve in the upper arm were smaller in patients with SBMA than those in patients with ALS (p < 0.05), whereas the CSAs of the C5 nerve root and the ulnar nerve in the forearm were not smaller. US showed that the peripheral nerves in patients with SBMA were thinner than those in patients with ALS despite similar degrees of weakness and motor neuron loss. Possible causes include additional sensory nerve involvement and longer disease duration in patients with SBMA than those in patients with ALS.

Evaluation of Relationship Between Laboratory, Electrodiagnostic, and Functional Parameters in Patients With Amyotrophic Lateral Sclerosis; A Cross Sectional Study

Background: Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease which leads to limb and/or bulbar muscle degeneration with a poor prognosis. Several demographic and biological factors have prognostic importance, but little data exist on the relationship between clinical, electrodiagnostic, and laboratory markers as predictors of disease progression. We aimed to assess the relationships between different aspects of clinical, electrodiagnostic, and laboratory features of ALS patients with their level of functioning. Methods: We included 27 patients with ALS who were diagnosed within two years before enrolment. Clinical assessment and electrodiagnostic studies were done by a neurology resident. The motor unit number index (MUNIX) and compound motor action potential (CMAP) were used as measures of motor unit loss. Serum creatinine, urea, Albumin, and creatine kinase were measured as laboratory markers. We used the Persian version of ALS functional rating scale (ALS-FRS) as the main outcome measure. Data were analyzed using the SPSS software. Pearson's correlation coefficient was calculated to test for correlations. Results: None of the demographic or laboratory parameters correlated with ALS-FRS. Patients with the onset of disease in the limbs had a higher MUNIX score compared to patients with a bulbar onset. Also, increased body mass index was associated with lower CMAP and MUNIX scores (p-value:0.02). Higher serum creatinine levels were significantly associated with higher lower limb MUNIX (p value:0.04). Higher lower limb MUNIX was in turn associated with higher lower limb functional score (ALS-FRS). Conclusion: Decreased serum creatinine may possibly be an indicator of lower limb motor unit loss in patients with ALS. Also, MUNIX scores may be used as surrogates for ALS-FRS in ALS trials. Further research is needed to elucidate the clinical application of these findings.Methods: We included 27 patients with ALS who were diagnosed within two years before enrolment. Clinical assessment and electrodiagnostic studies were done by a neurology resident. The motor unit number index (MUNIX) and compound motor action potential (CMAP) were used as measures of motor unit loss. Serum creatinine, urea, Albumin, and creatine kinase were measured as laboratory markers. We used the Persian version of ALS functional rating scale (ALS-FRS) as the main outcome measure. Data were analyzed using the SPSS software. Pearson's correlation coefficient was calculated to test for correlations. Results: None of the demographic or laboratory parameters correlated with ALS-FRS. Patients with the onset of disease in the limbs had a higher MUNIX score compared to patients with a bulbar onset. Also, increased body mass index was associated with lower CMAP and MUNIX scores (p-value:0.02). Higher serum creatinine levels were significantly associated with higher lower limb MUNIX (p value:0.04). Higher lower limb MUNIX was in turn associated with higher lower limb functional score (ALS-FRS). Conclusion: Decreased serum creatinine may possibly be an indicator of lower limb motor unit loss in patients with ALS. Also, MUNIX scores may be used as surrogates for ALS-FRS in ALS trials. Further research is needed to elucidate the clinical application of these findings.

Biomolecular Modifications Linked to Oxidative Stress in Amyotrophic Lateral Sclerosis: Determining Promising Biomarkers Related to Oxidative Stress

Reduction–oxidation reactions are essential to cellular homeostasis. Oxidative stress transcends physiological antioxidative system damage to biomolecules, including nucleic acids and proteins, and modifies their structures. Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease. The cells present in the central nervous system, including motor neurons, are vulnerable to oxidative stress. Neurodegeneration has been demonstrated to be caused by oxidative biomolecular modifications. Oxidative stress has been suggested to be involved in the pathogenesis of ALS. Recent progress in research on the underlying mechanisms of oxidative stress in ALS has led to the development of disease-modifying therapies, including edaravone. However, the clinical effects of edaravone remain limited, and ALS is a heretofore incurable disease. The reason for the lack of reliable biomarkers and the precise underlying mechanisms between oxidative stress and ALS remain unclear. As extracellular proteins and RNAs present in body fluids and represent intracellular pathological neurodegenerative processes, extracellular proteins and/or RNAs are predicted to promise diagnosis, prediction of disease course, and therapeutic biomarkers for ALS. Therefore, we aimed to elucidate the underlying mechanisms between oxidative stress and ALS, and promising biomarkers indicating the mechanism to determine whether therapy targeting oxidative stress can be fundamental for ALS.

Cholesterol dyshomeostasis in amyotrophic lateral sclerosis: cause, consequence, or epiphenomenon?

Amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disease, is characterized by the selective degeneration of motor neurons leading to paralysis and eventual death. Multiple pathogenic mechanisms, including systemic dysmetabolism, have been proposed to contribute to ALS. Among them, dyslipidemia, i.e., abnormal level of cholesterol and other lipids in the circulation and central nervous system (CNS), has been reported in ALS patients, but without a consensus. Cholesterol is a constituent of cellular membranes and a precursor of steroid hormones, oxysterols, and bile acids. Consequently, optimal cholesterol levels are essential for health. Due to the blood-brain barrier (BBB), cholesterol cannot move between the CNS and the rest of the body. As such, cholesterol metabolism in the CNS is proposed to operate autonomously. Despite its importance, it remains elusive how cholesterol dyshomeostasis may contribute to ALS. In this review, we aim to describe the current state of cholesterol metabolism research in ALS, identify unresolved issues, and provide potential directions.

Reduced PHOX2B stability causes axonal growth impairment in motor neurons with TARDBP mutations.

SummaryAmyotrophic lateral sclerosis (ALS) is an adult-onset incurable motor neuron (MN) disease. The reasons for selective MN vulnerability in ALS are unknown. Axonal pathology is among the earliest signs of ALS. We searched for novel modulatory genes in human MN axon shortening affected by TARDBP mutations. In transcriptome analysis of RNA present in the axon compartment of human-derived induced pluripotent stem cell (iPSC)-derived MNs, PHOX2B (paired-like homeobox protein 2B) showed lower expression in TARDBP mutant axons, which was consistent with axon qPCR and in situ hybridization. PHOX2B mRNA stability was reduced in TARDBP mutant MNs. Furthermore, PHOX2B knockdown reduced neurite length in human MNs. Finally, phox2b knockdown in zebrafish induced short spinal axons and impaired escape response. PHOX2B is known to be highly express in other types of neurons maintained after ALS progression. Collectively, TARDBP mutations induced loss of axonal resilience, which is an important ALS-related phenotype mediated by PHOX2B downregulation.

Inflammatory-Mediated Neuron-Glia Communication Modulates ALS Pathophysiology.

Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease. It is characterized by the deposition of aggregated proteins and predominantly affects motor neurons and the motor cortex. Although ALS is a genetically heterogeneous disease, mutations in superoxide dismutase 1

Imaging and clinical data indicate considerable disease burden in 'probable' PLS: Patients with UMN symptoms for 2-4 years.

Primary lateral sclerosis (PLS) is an adult-onset upper motor neuron disease manifesting in progressive spasticity and gradually resulting in considerably motor disability. In the absence of early disease-specific diagnostic indicators, the majority of patients with PLS face a circuitous diagnostic journey. Until the recent publication of consensus diagnostic criteria, 4-year symptom duration was required to establish the diagnosis. The new diagnostic criteria introduced the category of ‘probable PLS’ for patients with a symptom duration of 2–4 years. “Evolving diagnostic criteria in primary lateral sclerosis: The clinical and radiological basis of "probable PLS" [1]. This dataset provides radiological metrics in a cohort of ‘probable PLS’ patients, ‘definite PLS’ patients and age-matched healthy controls. Region-of-interest radiological data include diffusivity metrics in the corticospinal tracts and corpus callosum as well as mean cortical thickness values in the pre- and para-central gyri in each hemisphere. Our data indicate considerable grey matter and relatively limited white matter involvement in ‘probable PLS’ which supports the rationale for this diagnostic category as a clinically useful entity. The introduction of this diagnostic category will likely facilitate the timely recruitment of PLS patients into research studies and pharmacological trials before widespread neurodegenerative change ensues.

Adenosine and Its Receptors as Potential Drug Targets in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease that involves the progressive degeneration of the motor neurons of the spinal cord and motor cortex. Severe muscle wasting...

Hochu-Ekki-To Improves Motor Function in an Amyotrophic Lateral Sclerosis Animal Model.

Hochu-ekki-to (Bojungikgi-Tang (BJIGT) in Korea; Bu-Zhong-Yi-Qi Tang in Chinese), a traditional herbal prescription, has been widely used in Asia. Hochu-ekki-to (HET) is used to enhance the immune system in respiratory disorders, improve the nutritional status associated with chronic diseases, enhance the mucosal immune system, and improve learning and memory. Amyotrophic lateral sclerosis (ALS) is pathologically characterized by motor neuron cell death and muscle paralysis, and is an adult-onset motor neuron disease. Several pathological mechanisms of ALS have been reported by clinical and in vitro/in vivo studies using ALS models. However, the underlying mechanisms remain elusive, and the critical pathological target needs to be identified before effective drugs can be developed for patients with ALS. Since ALS is a disease involving both motor neuron death and skeletal muscle paralysis, suitable therapy with optimal treatment effects would involve a motor neuron target combined with a skeletal muscle target. Herbal medicine is effective for complex diseases because it consists of multiple components for multiple targets. Therefore, we investigated the effect of the herbal medicine HET on motor function and survival in hSOD1G93A transgenic mice. HET was orally administered once a day for 6 weeks from the age of 2 months (the pre-symptomatic stage) of hSOD1G93A transgenic mice. We used the rota-rod test and foot printing test to examine motor activity, and Western blotting and H&E staining for evaluation of the effects of HET in the gastrocnemius muscle and lumbar (L4–5) spinal cord of mice. We found that HET treatment dramatically inhibited inflammation and oxidative stress both in the spinal cord and gastrocnemius of hSOD1G93A transgenic mice. Furthermore, HET treatment improved motor function and extended the survival of hSOD1G93A transgenic mice. Our findings suggest that HET treatment may modulate the immune reaction in muscles and neurons to delay disease progression in a model of ALS.

Pathogenic mutations in the ALS gene CCNF cause cytoplasmic mislocalization of Cyclin F and elevated VCP ATPase activity.

Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease characterized by a progressive decline in motor function. Genetic analyses have identified several genes mutated in ALS patients, and one of them is Cyclin F gene (CCNF), the product of which (Cyclin F) serves as the substrate-binding module of a SKP1-CUL1-F-box protein (SCF) ubiquitin ligase complex. However, the role of Cyclin F in ALS pathogenesis has remained unclear. Here, we show that Cyclin F binds to valosin-containing protein (VCP), which is also reported to be mutated in ALS, and that the two proteins colocalize in the nucleus. VCP was found to bind to the NH2-terminal region of Cyclin F and was not ubiquitylated by SCFCyclin F in transfected cells. Instead, the ATPase activity of VCP was enhanced by Cyclin F in vitro. Furthermore, whereas ALS-associated mutations of CCNF did not affect the stability of Cyclin F or disrupt formation of the SCFCyclin F complex, amino acid substitutions in the VCP binding region increased the binding ability of Cyclin F to VCP and activity of VCP as well as mislocalization of the protein in the cytoplasm. We also provided evidence that the ATPase activity of VCP promotes cytoplasmic aggregation of transactivation responsive region (TAR) DNA-binding protein 43, which is commonly observed in degenerating neurons in ALS patients. Given that mutations of VCP identified in ALS patients also increase its ATPase activity, our results suggest that Cyclin F mutations may contribute to ALS pathogenesis by increasing the ATPase activity of VCP in the cytoplasm, which in turn increases TDP-43 aggregates.

Spinal Cord Imaging in Amyotrophic Lateral Sclerosis: Historical Concepts-Novel Techniques.

Amyotrophic lateral sclerosis (ALS) is the most common adult onset motor neuron disease with no effective disease modifying therapies at present. Spinal cord degeneration is a hallmark feature of ALS, highlighted in the earliest descriptions of the disease by Lockhart Clarke and Jean-Martin Charcot. The anterior horns and corticospinal tracts are invariably affected in ALS, but up to recently it has been notoriously challenging to detect and characterize spinal pathology in vivo. With recent technological advances, spinal imaging now offers unique opportunities to appraise lower motor neuron degeneration, sensory involvement, metabolic alterations, and interneuron pathology in ALS. Quantitative spinal imaging in ALS has now been used in cross-sectional and longitudinal study designs, applied to presymptomatic mutation carriers, and utilized in machine learning applications. Despite its enormous clinical and academic potential, a number of physiological, technological, and methodological challenges limit the routine use of computational spinal imaging in ALS. In this review, we provide a comprehensive overview of emerging spinal cord imaging methods and discuss their advantages, drawbacks, and biomarker potential in clinical applications, clinical trial settings, monitoring, and prognostic roles.

Isoform-selective as opposed to complete depletion of fibroblast growth factor 2 (FGF-2) has no major impact on survival and gene expression in SOD1G93A amyotrophic lateral sclerosis mice.

We have previously shown that total knockout of fibroblast growth factor-2 (FGF-2) results in prolonged survival and improved motor performance in superoxide dismutase 1 (SOD1G93A ) mutant mice, the most widely used animal model of the fatal adult onset motor neuron disease amyotrophic lateral sclerosis (ALS). Moreover, we found differential expression of growth factors in SOD1G93A mice, with distinct regulation patterns of FGF-2 in spinal cord and muscle tissue. Within the present study we aimed to characterize FGF-2-isoform specific effects on survival, motor performance as well as gene expression patterns predominantly in muscle tissue by generating double mutant SOD1G93A FGF-2 high molecular weight- and SOD1G93A FGF-2 low molecular weight-knockout mice. While isoform specific depletion was not beneficial regarding survival or motor performance of double mutant mice, we found isoform-dependent differential gene expression of epidermal growth factor (EGF) in the muscle of SOD1G93A FGF-2 low molecular weight knockout mice compared to single mutant SOD1G93A mice. This significant downregulation of EGF in the muscle tissue of double mutant SOD1G93A FGF-2 low molecular weight knockout mice implies that FGF-2 low molecular weight knockout (or the presence of the FGF-2 high molecular weight isoform) selectively impacts EGF gene expression in ALS muscle tissue.

Diagnostic Challenge and Neuromuscular Junction Contribution to ALS Pathogenesis.

Amyotrophic lateral sclerosis (ALS) represents the major adult-onset motor neuron disease. Both human and animal studies reveal the critical implication of muscle and neuromuscular junctions (NMJs) in the initial phase of this disease. Despite the common efforts, ALS diagnosis remains particularly challenging since many other disorders can overlap yielding similar clinical phenotypic features. A combination of further research on the NMJ parameters that are specific for this disease and laboratory tests are crucial for the early determination of specific changes in the muscle, as well as in motor neuron and the prediction of ALS progression. Also, it could provide a powerful tool in the discrimination of particular ALS and ALS-mimic cases and increase the efficacy of therapeutic treatments.

RNA Dysregulation in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease and is characterized by the degeneration of upper and lower motor neurons. It has become increasingly clear that RNA dysregulation is a key contributor to ALS pathogenesis. The major ALS genes SOD1, TARDBP, FUS, and C9orf72 are involved in aspects of RNA metabolism processes such as mRNA transcription, alternative splicing, RNA transport, mRNA stabilization, and miRNA biogenesis. In this review, we highlight the current understanding of RNA dysregulation in ALS pathogenesis involving these major ALS genes and discuss the potential of therapeutic strategies targeting disease RNAs for treating ALS.