ABSTRACT
One of the recognized motor neuron degenerative disorders is amyotrophic lateral sclerosis (ALS). By now, several mutations have been reported and linked to ALS patients, some of which are induced by mutations in the human superoxide dismutase (hSOD1) gene. The ALS-provoking mutations are located throughout the structure of hSOD1 and promote the propensity to aggregate. Despite numerous investigations, the underlying mechanism related to the toxicity of mutant hSOD1 through the gain of a toxic function is still vague. We surveyed two mutant forms of hSOD1 by removing and adding cysteine at positions 146 and 72, respectively, to investigate the biochemical characterization and amyloid formation. Our findings predicted the harmful and destabilizing impact of two SOD1 mutants using multiple programs. The specific activity of the wild-type form was about 1.42- and 1.92-fold higher than that of C146R and G72C mutants, respectively. Comparative structural studies using CD spectropolarimetry, and intrinsic and ANS fluorescence showed alterations in secondary structure content, exposure of hydrophobic patches, and structural compactness of WT-hSOD1 vs. mutants. We demonstrated that two mutants were able to promote amyloid-like aggregates under amyloid induction circumstances (50-mM Tris-HCl pH 7.4, 0.2-M KSCN, 50-mM DTT, 37 °C, 190 rpm). Monitoring aggregates were done using an enhancement in thioflavin T fluorescence and alterations in Congo red absorption. The mutants accelerated fibrillation with subsequently greater fluorescence amplitude and a shorter lag time compared to WT-SOD1. These findings support the aggregation of ALS-associated SOD1 mutants as an integral part of ALS pathology.
Subject(s)
Amyotrophic Lateral Sclerosis , Mutation , Superoxide Dismutase-1 , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/metabolism , Humans , Superoxide Dismutase-1/genetics , Superoxide Dismutase-1/metabolism , Superoxide Dismutase-1/chemistry , Amyloid/metabolism , Protein Aggregates , Protein Aggregation, Pathological/geneticsABSTRACT
Cu, Zn superoxide dismutase (SOD1) is one of the genes implicated in the devastating neurodegenerative disorder amyotrophic lateral sclerosis (ALS). Although the precise mechanisms of SOD1 mutant (SOD1mut)-induced motoneuron toxicity are still unclear, defects in SOD1 proteostasis are known to have a critical role in ALS pathogenesis. We previously reported that the SOD1mut adopts a conformation that exposes a Derlin-1-binding region (DBR) and that DBR-exposed SOD1 interacts with Derlin-1, leading to motoneuron death. We also found that an environmental change, i.e. zinc depletion, induces a conformational change in WT SOD1 (SOD1WT) to the DBR-exposed conformation, suggesting the presence of an equilibrium state between the DBR-masked and DBR-exposed states even with SOD1WT Here, we conducted a high-throughput screening based on time-resolved FRET to further investigate the SOD1WT conformational change, and we used a genome-wide siRNA screen to search for regulators of SOD1 proteostasis. This screen yielded 30 candidate genes that maintained an absence of the DBR-exposed SOD1WT conformation. Among these genes was one encoding DDB1- and CUL4-associated factor 4 (DCAF4), a substrate receptor of the E3 ubiquitin-protein ligase complex. Of note, we found that DCAF4 mediates the ubiquitination of an ALS-associated protein and autophagy receptor, optineurin (OPTN), and facilitates autophagic degradation of DBR-exposed SOD1. In summary, our screen identifies DCAF4 as being required for proper proteostasis of DBR-exposed SOD1, which may have potential relevance for the development of therapies for managing ALS.
Subject(s)
Autophagy , Carrier Proteins/metabolism , Cell Cycle Proteins/metabolism , Membrane Transport Proteins/metabolism , Superoxide Dismutase-1/metabolism , Carrier Proteins/antagonists & inhibitors , Carrier Proteins/genetics , Fluorescence Resonance Energy Transfer , HEK293 Cells , HeLa Cells , High-Throughput Screening Assays , Humans , Membrane Proteins/metabolism , Mutagenesis, Site-Directed , Proteostasis/drug effects , RNA Interference , RNA, Small Interfering/metabolism , Superoxide Dismutase-1/genetics , Ubiquitination , Wortmannin/pharmacologyABSTRACT
Aberrant structural formations of Cu/Zn superoxide dismutase enzyme (SOD1) are the probable mechanism by which circumscribed mutations in the SOD1 gene cause familial amyotrophic lateral sclerosis (ALS1). SOD1 forms aberrant structures which can proceed by nucleation to insoluble aggregates. Here, the SOD1 aggregation reaction was investigated predominantly by time-course studies on ALS1 variants G85R, G37R, D101G, and D101N in human embryonic kidney cells (HEK293FT), with analysis by detergent ultracentrifugation extractions and high-resolution PAGE methodologies. Nucleation was found to be pseudo-zeroth order and dependent on time and concentration at constant 37.0 °C and pH 7.4. The predominant subsets of the total SOD1 expression set which comprised the nucleation phase were both soluble and insoluble inactive monomers, trimers, and hexamers with reduced intra-disulfide bonds. Superoxide exposure via paraquat initiated the formation of SOD1 trimers in untransfected SH-SY5Y cells and increased the aggregation propensity of G85R in HEK293FT. These data show the kinetic formation of aberrant SOD1 subsets implicated in ALS1 and indicate that superoxide substrate may initiate its radical polymerization. In an instance of the utility of methodological reductionism in molecular theory: though many ALS1 variants retain their global enzymatic activity, the SOD1 subsets most implicated in causing ALS1 do not retain their specific activity.
Subject(s)
Mutation, Missense , Protein Aggregation, Pathological/metabolism , Superoxide Dismutase-1/metabolism , Amino Acid Substitution , Amyotrophic Lateral Sclerosis/genetics , Animals , Cell Line, Tumor , HEK293 Cells , Humans , Mice , NIH 3T3 Cells , Protein Aggregation, Pathological/genetics , Superoxide Dismutase-1/chemistry , Superoxide Dismutase-1/geneticsABSTRACT
The goal of this study was to compare dysphagia phenotypes in low and high copy number (LCN and HCN) transgenic superoxide dismutase 1 (SOD1) mouse models of ALS to accelerate the discovery of novel and effective treatments for dysphagia and early amyotrophic lateral sclerosis (ALS) diagnosis. Clinicopathological features of dysphagia were characterized in individual transgenic mice and age-matched controls utilizing videofluoroscopy in conjunction with postmortem assays of the tongue and hypoglossal nucleus. Quantitative PCR accurately differentiated HCN-SOD1 and LCN-SOD1 mice and nontransgenic controls. All HCN-SOD1 mice developed stereotypical paralysis in both hindlimbs. In contrast, LCN-SOD1 mice displayed wide variability in fore- and hindlimb involvement. Lick rate, swallow rate, inter-swallow interval, and pharyngeal transit time were significantly altered in both HCN-SOD1 and LCN-SOD1 mice compared to controls. Tongue weight, tongue dorsum surface area, total tongue length, and caudal tongue length were significantly reduced only in the LCN-SOD1 mice compared to age-matched controls. LCN-SOD1 mice with lower body weights had smaller/lighter weight tongues, and those with forelimb paralysis and slower lick rates died at a younger age. LCN-SOD1 mice had a 32% loss of hypoglossal neurons, which differed significantly when compared to age-matched control mice. These novel findings for LCN-SOD1 mice are congruent with reported dysphagia and associated tongue atrophy and hypoglossal nucleus pathology in human ALS patients, thus highlighting the translational potential of this mouse model in ALS research.
Subject(s)
Amyotrophic Lateral Sclerosis/genetics , Deglutition Disorders/genetics , Deglutition/genetics , Superoxide Dismutase-1 , Amyotrophic Lateral Sclerosis/complications , Amyotrophic Lateral Sclerosis/physiopathology , Animals , Autopsy , Cineradiography , Deglutition Disorders/physiopathology , Disease Models, Animal , Female , Forelimb/physiopathology , Gastrointestinal Transit , Gene Dosage , Hindlimb/physiopathology , Humans , Hypoglossal Nerve/physiopathology , Male , Mice , Mice, Transgenic , Paralysis/genetics , Paralysis/physiopathology , Pharynx/physiopathology , Tongue/physiopathology , Translational Research, BiomedicalABSTRACT
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the progressive demise of motor neurons. One of the causes of familial ALS is the mutation of the gene encoding superoxide dismutase 1 (SOD1), which leads to abnormal protein aggregates. How SOD1 aggregation drives ALS is still poorly understood. Recently, ALS pathogenesis has been functionally implicated in mitophagy, specifically the clearance of damaged mitochondria. Here, to understand this mechanism, we investigated the relationship between the mitophagy receptor optineurin and SOD1 aggregates. We found that mutant SOD1 (mSOD1) proteins associate with and then sequester optineurin, which is required to form the mitophagosomes, to aggregates in N2a cells. Optineurin recruitment into mSOD1 aggregates resulted in a reduced mitophagy flux. Furthermore, we observed that an exogenous augmentation of optineurin alleviated the cellular cytotoxicity induced by mSOD1. Taken together, these studies demonstrate that ALS-linked mutations in SOD1 interfere with the mitophagy process through optineurin sequestration, suggesting that the accumulation of damaged mitochondria may play a crucial role in the pathophysiological mechanisms contributing to ALS.
Subject(s)
Amyotrophic Lateral Sclerosis/metabolism , Cell Cycle Proteins/metabolism , Membrane Transport Proteins/metabolism , Mitophagy , Protein Aggregation, Pathological/metabolism , Superoxide Dismutase-1/genetics , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/pathology , Animals , Cell Line, Tumor , Mice , Mutation , Protein Aggregation, Pathological/genetics , Superoxide Dismutase-1/metabolismABSTRACT
Glia cells are involved in upper motor neuron degeneration in amyotrophic lateral sclerosis (ALS). Protease activated receptor 1 (PAR1) pathway is related to brain pathologies. Brain PAR1 is located on peri-synaptic astrocytes, adjacent to pyramidal motor neurons, suggesting possible involvement in ALS. Brain thrombin activity in superoxide dismutase 1 (SOD1) mice was measured using a fluorometric assay, and PAR1 levels by western blot. PAR1 was localized using immunohistochemistry staining. Treatment targeted PAR1 pathway on three levels; thrombin inhibitor TLCK (N-Tosyl-Lys-chloromethylketone), PAR1 antagonist SCH-79797 and the Ras intracellular inhibitor FTS (S-trans-trans-farnesylthiosalicylic acid). Mice were weighed and assessed for motor function and survival. SOD1 brain thrombin activity was increased (p < 0.001) particularly in the posterior frontal lobe (p = 0.027) and hindbrain (p < 0.01). PAR1 levels were decreased (p < 0.001, brain, spinal cord, p < 0.05). PAR1 and glial fibrillary acidic protein (GFAP) staining decreased in the cerebellum and cortex. SOD1 mice lost weight (≥17 weeks, p = 0.047), and showed shorter rotarod time (≥14 weeks, p < 0.01). FTS 40mg/kg significantly improved rotarod scores (p < 0.001). Survival improved with all treatments (p < 0.01 for all treatments). PAR1 antagonism was the most efficient, with a median survival improvement of 10 days (p < 0.0001). Our results support PAR1 pathway involvement in ALS.
Subject(s)
Amyotrophic Lateral Sclerosis/metabolism , Brain/metabolism , Disease Models, Animal , Receptor, PAR-1/metabolism , Superoxide Dismutase-1/metabolism , Amyotrophic Lateral Sclerosis/genetics , Animals , Astrocytes/metabolism , Body Weight/drug effects , Farnesol/analogs & derivatives , Farnesol/pharmacology , Glial Fibrillary Acidic Protein/metabolism , Humans , Mice , Mice, Transgenic , Motor Neurons/metabolism , Mutation , Pyrroles/pharmacology , Quinazolines/pharmacology , Salicylates/pharmacology , Signal Transduction/drug effects , Superoxide Dismutase-1/genetics , Survival Analysis , Tosyllysine Chloromethyl Ketone/pharmacologyABSTRACT
We have previously shown that knockout of fibroblast growth factor-2 (FGF-2) and potential compensatory effects of other growth factors result in amelioration of disease symptoms in a transgenic mouse model of amyotrophic lateral sclerosis (ALS). ALS is a rapidly progressive neurological disorder leading to degeneration of cortical, brain stem, and spinal motor neurons followed by subsequent denervation and muscle wasting. Mutations in the superoxide dismutase 1 (SOD1) gene are responsible for approximately 20% of familial ALS cases and SOD1 mutant mice still are among the models best mimicking clinical and neuropathological characteristics of ALS. The aim of the present study was a thorough characterization of FGF-2 and other growth factors and signaling effectors in vivo in the SOD1G93A mouse model. We observed tissue-specific opposing gene regulation of FGF-2 and overall dysregulation of other growth factors, which in the gastrocnemius muscle was associated with reduced downstream extracellular-signal-regulated kinases (ERK) and protein kinase B (AKT) activation. To further investigate whether the effects of FGF-2 on motor neuron death are mediated by glial cells, astrocytes lacking FGF-2 were cocultured together with mutant SOD1 G93A motor neurons. FGF-2 had an impact on motor neuron maturation indicating that astrocytic FGF-2 affects motor neurons at a developmental stage. Moreover, neuronal gene expression patterns showed FGF-2- and SOD1 G93A -dependent changes in ciliary neurotrophic factor, glial-cell-line-derived neurotrophic factor, and ERK2, implying a potential involvement in ALS pathogenesis before the onset of clinical symptoms.
Subject(s)
Amyotrophic Lateral Sclerosis/enzymology , Astrocytes/enzymology , Fibroblast Growth Factor 2/metabolism , Motor Neurons/enzymology , Muscle, Skeletal/enzymology , Superoxide Dismutase-1/metabolism , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/pathology , Animals , Astrocytes/pathology , Cell Death , Cells, Cultured , Disease Models, Animal , Enzyme Activation , Extracellular Signal-Regulated MAP Kinases/metabolism , Fibroblast Growth Factor 2/deficiency , Fibroblast Growth Factor 2/genetics , Gene Expression Regulation, Developmental , Mice, Inbred C57BL , Mice, Knockout , Motor Neurons/pathology , Mutation , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction , Superoxide Dismutase-1/geneticsABSTRACT
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the loss of upper and lower motor neurons, which manifests clinically as progressive weakness. Although several epidemiological studies have found an association between traumatic brain injury (TBI) and ALS, there is not a consensus on whether TBI is an ALS risk factor. It may be that it can cause ALS in a subset of susceptible patients, based on a history of repetitive mild TBI and genetic predisposition. This cannot be determined based on clinical observational studies alone. Better preclinical models are necessary to evaluate the effects of TBI on ALS onset and progression. To date, only a small number of preclinical studies have been performed, mainly in the superoxide dismutase 1 transgenic rodents, which, taken together, have mixed results and notable methodological limitations. The more recent incorporation of additional animal models such as Drosophila flies, as well as patient-induced pluripotent stem cell-derived neurons, should facilitate a better understanding of a potential functional interaction between TBI and ALS.
Subject(s)
Amyotrophic Lateral Sclerosis , Brain Concussion , DNA-Binding Proteins , Induced Pluripotent Stem Cells , Superoxide Dismutase-1 , Amyotrophic Lateral Sclerosis/etiology , Amyotrophic Lateral Sclerosis/metabolism , Amyotrophic Lateral Sclerosis/physiopathology , Animals , Brain Concussion/complications , Brain Concussion/metabolism , Brain Concussion/physiopathology , HumansABSTRACT
Mutations in superoxide dismutase 1 (SOD1) cause amyotrophic lateral sclerosis (ALS). Disease pathogenesis is linked to destabilization, disorder and aggregation of the SOD1 protein. However, the non-genetic factors that promote disorder and the subsequent aggregation of SOD1 have not been studied. Mainly located to the reducing cytosol, mature SOD1 contains an oxidized disulfide bond that is important for its stability. Since O2 is required for formation of the bond, we reasoned that low O2 tension might be a risk factor for the pathological changes associated with ALS development. By combining biochemical approaches in an extensive range of genetically distinct patient-derived cell lines, we show that the disulfide bond is an Achilles heel of the SOD1 protein. Culture of patient-derived fibroblasts, astrocytes, and induced pluripotent stem cell-derived mixed motor neuron and astrocyte cultures (MNACs) under low O2 tensions caused reductive bond cleavage and increases in disordered SOD1. The effects were greatest in cells derived from patients carrying ALS-linked mutations in SOD1. However, significant increases also occurred in wild-type SOD1 in cultures derived from non-disease controls, and patients carrying mutations in other common ALS-linked genes. Compared to fibroblasts, MNACs showed far greater increases in SOD1 disorder and even aggregation of mutant SOD1s, in line with the vulnerability of the motor system to SOD1-mediated neurotoxicity. Our results show for the first time that O2 tension is a principal determinant of SOD1 stability in human patient-derived cells. Furthermore, we provide a mechanism by which non-genetic risk factors for ALS, such as aging and other conditions causing reduced vascular perfusion, could promote disease initiation and progression.
Subject(s)
Amyotrophic Lateral Sclerosis/pathology , Fibroblasts/pathology , Motor Neurons/pathology , Oxygen/metabolism , Amyotrophic Lateral Sclerosis/metabolism , Fibroblasts/metabolism , Humans , Mutation/genetics , Superoxide Dismutase-1/genetics , Superoxide Dismutase-1/metabolismABSTRACT
Misfolded Cu/Zn superoxide dismutase enzyme (SOD1) shows prion-like propagation in neuronal cells leading to neurotoxic aggregates that are implicated in amyotrophic lateral sclerosis (ALS). Tryptophan-32 (W32) in SOD1 is part of a potential site for templated conversion of wild type SOD1. This W32 binding site is located on a convex, solvent exposed surface of the SOD1 suggesting that hydration effects can play an important role in ligand recognition and binding. A recent X-ray crystal structure has revealed that 5-Fluorouridine (5-FUrd) binds at the W32 binding site and can act as a pharmacophore scaffold for the development of anti-ALS drugs. In this study, a new protocol is developed to account for structural (non-displaceable) water molecules in docking simulations and successfully applied to predict the correct docked conformation binding modes of 5-FUrd at the W32 binding site. The docked configuration is within 0.58 Å (RMSD) of the observed configuration. The docking protocol involved calculating a hydration structure around SOD1 using molecular theory of solvation (3D-RISM-KH, 3D-Reference Interaction Site Model-Kovalenko-Hirata) whereby, non-displaceable water molecules are identified for docking simulations. This protocol was also used to analyze the hydrated structure of the W32 binding site and to explain the role of solvation in ligand recognition and binding to SOD1. Structural water molecules mediate hydrogen bonds between 5-FUrd and the receptor, and create an environment favoring optimal placement of 5-FUrd in the W32 binding site.
Subject(s)
Models, Theoretical , Molecular Docking Simulation , Molecular Dynamics Simulation , Superoxide Dismutase-1/metabolism , Uridine/analogs & derivatives , Water/chemistry , Binding Sites , Humans , Mutation , Protein Conformation , Quantum Theory , Solvents , Superoxide Dismutase-1/chemistry , Superoxide Dismutase-1/genetics , Uridine/chemistry , Uridine/metabolism , Water/metabolismABSTRACT
Mutations in superoxide dismutase 1 (SOD1) cause familial amyotrophic lateral sclerosis (FALS), while wild-type SOD1 has been implicated in sporadic ALS (SALS). SOD1 mutants are now recognized to acquire one or more toxicities that include their association with mitochondrial and endoplasmic reticulum membranes but the underlying structural mechanism remains unknown. Here we determine NMR conformations of both wild-type and a truncation mutant (L126Z) of SOD1 in aqueous solution and a membrane environment. The truncation mutant (which causes FALS at very low levels, indicating its elevated toxicity) is highly unstructured in solution, failing to adopt the ß-barrel SOD1 native structure. Wild-type SOD1 is also highly unstructured upon reduction of disulfides and depletion of zinc. Most remarkably, both mutant and wild type adopt similar, highly-helical conformations in a membrane environment. Thus, either truncation or depletion of zinc is sufficient to eliminate the native ß-barrel structure, and transform cytosolic SOD1 into membrane proteins energetically driven by forming amphiphilic helices in membranes. That zinc-deficiency is sufficient to produce a similar transformation in wild-type SOD1 implies that the wild-type and FALS-linked SOD1 mutants may trigger ALS by a common mechanism.
Subject(s)
Amyotrophic Lateral Sclerosis/genetics , Intracellular Membranes/enzymology , Membrane Proteins/genetics , Mutation , Organelles/enzymology , Superoxide Dismutase/genetics , Amino Acid Sequence , Amyotrophic Lateral Sclerosis/enzymology , Cytosol/enzymology , Disulfides/chemistry , Disulfides/metabolism , Humans , Magnetic Resonance Spectroscopy , Membrane Proteins/chemistry , Membrane Proteins/metabolism , Models, Molecular , Molecular Sequence Data , Oxidation-Reduction , Protein Conformation , Protein Multimerization , Protein Structure, Secondary , Superoxide Dismutase/chemistry , Superoxide Dismutase/metabolism , Superoxide Dismutase-1 , Zinc/chemistry , Zinc/metabolismABSTRACT
Myeloid leukemia cells maintain a high intracellular ROS level and use redox signals for survival. The metabolism of ROS also affects cell fate, including cell death and differentiation. Superoxide dismutases (SODs) are major antioxidant enzymes that have high levels of expression in myeloid leukemia cells. However, the role of SODs in the regulation of myeloid leukemia cells' biological function is still unclear. To investigate the function of SODs in myeloid leukemia cell death and differentiation, we used myeloid leukemia cell lines K562, MEG-01, TF-1, and HEL cells for this study. We found that PMA-induced megakaryocytic differentiation in myeloid leukemia cells is accompanied by cell death and SOD1 down-regulation, while SOD2 expression is not affected. The role of SOD1 is verified when ATN-224, a SOD1 specific inhibitor, inhibits cell proliferation and promotes cell death in myeloid leukemia cells without PMA treatment. Moreover, inhibition or silencing of SODs further increases cell death and decreases polyploidization induced by PMA while they were partially reversed by SOD1 overexpression. Thus, SOD1 expression is required for myeloid leukemia cell fate determination. In addition, the knockdown of PKD2 reduces cell death and promotes polyploidization induced by PMA. PMA/PKD2-mediated necrosis via PARP cleavage involves both SOD1-dependent and -independent pathways. Finally, ATN-224 enhanced the inhibition of cell proliferation by Ara-C. Taken together, the results demonstrate that SOD1 regulates cell death and differentiation in myeloid leukemia cells. ATN-224 may be beneficial for myeloid leukemia therapy.
Subject(s)
Carcinogens/pharmacology , Down-Regulation/drug effects , Gene Expression Regulation, Enzymologic/drug effects , Gene Expression Regulation, Leukemic/drug effects , Leukemia, Myeloid/enzymology , Neoplasm Proteins/biosynthesis , Protein Kinases/metabolism , Signal Transduction/drug effects , Superoxide Dismutase/biosynthesis , Tetradecanoylphorbol Acetate/pharmacology , Humans , K562 Cells , Leukemia, Myeloid/genetics , Leukemia, Myeloid/pathology , Molybdenum/pharmacology , Neoplasm Proteins/genetics , Poly(ADP-ribose) Polymerases/genetics , Poly(ADP-ribose) Polymerases/metabolism , Protein Kinase D2 , Protein Kinases/genetics , Signal Transduction/genetics , Superoxide Dismutase/antagonists & inhibitors , Superoxide Dismutase/genetics , Superoxide Dismutase-1ABSTRACT
Prions, self-proliferating infectious agents consisting of misfolded protein, are most often associated with aggressive neurodegenerative diseases in animals and humans. Akin to the contiguous spread of a living pathogen, the prion paradigm provides a mechanism by which a mutant or wild-type misfolded protein can dominate pathogenesis through self-propagating protein misfolding, and subsequently spread from region to region through the central nervous system. The prion diseases, along with more common neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and the tauopathies belong to a larger group of protein misfolding disorders termed proteinopathies that feature aberrant misfolding and aggregation of specific proteins. Amyotrophic lateral sclerosis (ALS), a lethal disease characterized by progressive degeneration of motor neurons is currently understood as a classical proteinopathy; the disease is typified by the formation of inclusions consisting of aggregated protein within motor neurons that contribute to neurotoxicity. It is well established that misfolded/aggregated proteins such as SOD1 and TDP-43 contribute to the toxicity of motor neurons and play a prominent role in the pathology of ALS. Recent work has identified propagated protein misfolding properties in both mutant and wild-type SOD1, and to a lesser extent TDP-43, which may provide the molecular basis for the clinically observed contiguous spread of the disease through the neuroaxis. In this review we examine the current state of knowledge regarding the prion-like properties of proteins associated with ALS pathology as well as their possible mechanisms of transmission.
Subject(s)
Amyotrophic Lateral Sclerosis , Prions/metabolism , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/metabolism , Amyotrophic Lateral Sclerosis/pathology , Animals , DNA-Binding Proteins/metabolism , Humans , Protein Folding , Superoxide Dismutase/metabolism , Superoxide Dismutase-1ABSTRACT
Amyotrophic lateral sclerosis (ALS) is a severe and incurable neurodegenerative disease. Human motor neurons generated from induced pluripotent stem cells (iPSc) offer new perspectives for disease modeling and drug testing in ALS. In standard iPSc-derived cultures, however, the two major phenotypic alterations of ALS--degeneration of motor neuron cell bodies and axons--are often obscured by cell body clustering, extensive axon criss-crossing and presence of unwanted cell types. Here, we succeeded in isolating 100% pure and standardized human motor neurons by a novel FACS double selection based on a p75(NTR) surface epitope and an HB9::RFP lentivirus reporter. The p75(NTR)/HB9::RFP motor neurons survive and grow well without forming clusters or entangled axons, are electrically excitable, contain ALS-relevant motor neuron subtypes and form functional connections with co-cultured myotubes. Importantly, they undergo rapid and massive cell death and axon degeneration in response to mutant SOD1 astrocytes. These data demonstrate the potential of FACS-isolated human iPSc-derived motor neurons for improved disease modeling and drug testing in ALS and related motor neuron diseases.
Subject(s)
Amyotrophic Lateral Sclerosis , Flow Cytometry/methods , Induced Pluripotent Stem Cells , Motor Neurons , Adult , Amyotrophic Lateral Sclerosis/pathology , Amyotrophic Lateral Sclerosis/physiopathology , Astrocytes/pathology , Astrocytes/physiology , Axons/pathology , Axons/physiology , Cell Survival , Cells, Cultured , Child , Coculture Techniques , Genes, Reporter , Humans , Induced Pluripotent Stem Cells/physiology , Lentivirus , Motor Neurons/pathology , Motor Neurons/physiology , Mutation , Nerve Degeneration/pathology , Nerve Degeneration/physiopathology , Nerve Tissue Proteins/metabolism , Receptors, Nerve Growth Factor/metabolism , Superoxide Dismutase/genetics , Superoxide Dismutase/metabolism , Superoxide Dismutase-1ABSTRACT
INTRODUCTION/OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which genetic variants can significantly influence clinical presentation and prognosis. This study aims to describe the demographic and clinical characteristics of ALS patients carrying the SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant, as treated at a national reference center in Colombia. METHODS: A descriptive study was conducted on patients identified with the SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant, selected from the database of a neuromuscular disease center in Colombia. Demographic and clinical data were collected through medical records and patient interviews. Molecular analysis was performed using PCR and automated sequencing to confirm the presence of the variant. RESULTS: Eleven patients with SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant were identified. The mean age at onset was 48.4 years, with a mean disease duration of 76.7 months. The majority (90.9%) exhibited a slowly progressive course, predominantly with spinal onset and no cognitive impairment. Bulbar symptoms developed in 72.2% of the patients, and 81.8% required noninvasive ventilation. A family history of ALS or other neurodegenerative disorders was present in 54.5% of the patients. CONCLUSIONS: The SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant is associated with a slowly progressive ALS phenotype, characterized by predominant lower motor neuron involvement and delayed onset of bulbar and respiratory symptoms. This variant appears to be predominantly distributed in central Colombia. Early detection of this variant may enable timely interventions and personalized care plans. Further research is required to establish a definitive causal relationship between this variant and the observed clinical course.
ABSTRACT
Amyotrophic lateral sclerosis (ALS) is a refractory neurodegenerative disease characterized by the degeneration and loss of motor neurons, typically resulting in death within five years of onset. There have been few effective treatments, making the development of robust therapies an urgent challenge. Genetic mutations have been identified as contributors to ALS, with mutations in superoxide dismutase 1 (SOD1), which neutralizes the harmful reactive oxygen species superoxide, accounting for approximately 2% of all ALS cases. To counteract the toxic gain of function caused by SOD1 mutations, therapeutic strategies aimed at suppressing SOD1 gene expression have shown promise. Antisense oligonucleotide (ASO) is an artificially synthesized, short, single-stranded DNA/RNA molecule that binds to target RNA to alter gene expression, representing a next-generation therapeutic approach. In 2023, tofersen became the first ASO drug approved by the FDA for ALS. Administered intrathecally, tofersen specifically binds to SOD1 mRNA, inhibiting the production of toxic SOD1 protein, thereby improving biomarkers of ALS. The long-term efficacy and safety of tofersen require further validation, and the development of more optimized treatment protocols is essential. A series of studies and therapeutic developments related to SOD1 mutations have advanced the understanding of ALS pathophysiology and significantly contributed to treatment strategies for central nervous system disorders. This review focuses on an overview of SOD1 mutations and the development process of tofersen, aiming to deepen the understanding of advancements in ALS research and discuss future challenges and directions for ASO therapy.
Subject(s)
Amyotrophic Lateral Sclerosis , Mutation , Oligonucleotides, Antisense , Superoxide Dismutase-1 , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/drug therapy , Amyotrophic Lateral Sclerosis/therapy , Humans , Superoxide Dismutase-1/genetics , Oligonucleotides, Antisense/therapeutic use , Oligonucleotides, Antisense/genetics , Animals , Oligonucleotides/therapeutic use , Oligonucleotides/geneticsABSTRACT
We report the first Italian kindred with Familial Amyotrophic Lateral Sclerosis (FALS) due to c.149T>C mutation in the exon 5 of superoxide dismutase-1 (SOD1) gene. The proband was a 49-year-old woman who came to our observation because of an history of progressive limbs weakness and gait impairment. She belonged to a family of 24 affected members. The prevalent phenotype of the affected members was characterized by slowly progressive spinal impairment with proximal distribution of weakness, and bulbar involvement in advanced stages. We briefly reviewed the few previous reports about the same SOD1 mutation and discussed the hypothesis that structural instability of the mutant codon 149 protein may underlie some toxic effects significantly involved in FALS pathogenesis.
Subject(s)
Amyotrophic Lateral Sclerosis/genetics , DNA/genetics , Family , Genetic Predisposition to Disease , Mutation , Superoxide Dismutase/genetics , Amyotrophic Lateral Sclerosis/metabolism , DNA Mutational Analysis , Exons , Female , Genotype , Humans , Middle Aged , Pedigree , Superoxide Dismutase/metabolism , Superoxide Dismutase-1ABSTRACT
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with few therapeutic options. While several gene mutations have been implicated in ALS, the exact cause of neuronal dysfunction is unknown and motor neurons of affected individuals display numerous cellular abnormalities. Ongoing efforts to develop novel ALS treatments involve the identification of small molecules targeting specific mechanisms of neuronal pathology, including glutamate excitotoxicity, mutant protein aggregation, endoplasmic reticulum (ER) stress, loss of trophic factors, oxidative stress, or neuroinflammation. Herein, we review recent advances in the discovery and preclinical characterization of lead compounds that may ultimately provide novel drugs to treat patients suffering from ALS.
ABSTRACT
The study was conducted to assess nano zinc (ZnN) as a feed supplement with an aim to compare the supplemental dose of inorganic zinc (ZnI). ZnN was synthesized from 0.45 molar (M) zinc nitrate [Zn(NO3)2.6H2O] and 0.9 M sodium hydroxide (NaOH) and was confirmed to be of ZnN by TEM-EDAX measurements. Wister albino rats (rats; 84, 53.6 ± 0.65 g) were divided into seven groups (4 replicate with 3 rats each) and given feed supplemented with zinc for 60 days with either of the following diets: (1) normal control (NC): basal diet (BD) + no supplemental Zn; (2) ZnI-25: BD + 25 mg/kg Zn from inorganic ZnO; (3) ZnN-25: BD + 25 mg/kg of ZnN; (4) ZnN-12.5: BD + 12.5 mg/kg of ZnN; (5) ZnN-6.25: BD + 6.25 mg/kg of ZnN; (6) ZnN-3.125: BD + 3.125 mg/kg of ZnN; (7) ZnN-50: BD + 50 mg/kg of ZnN. T3 and insulin-like growth factor-1 (IGF-1) hormone levels were similar among groups (P > 0.05), whereas T4 and testosterone were significantly affected, based on supplemented dose. Zn supplementation improved both cell-mediated and humoral immunity. However, both cell-mediated immunity at 24 h and humoral immunity were statistically similar in ZnI-25 and ZnN-6.25 groups. Superoxide dismutase 1 gene expression was found to be similar in all experimental groups. The vascular degeneration were found in liver tissues moderately in NC, mildly in ZnN-6.25 and ZnN-3.125 groups, and no observable changes were noticed in kidney and spleen tissues. However, there was a mild damage in intestinal epithelium of ZnN-25 group rats, hyperplasia of goblet cells, and moderate damage in intestinal villi were observed in ZnN-50 group rats. From the study, it can be concluded that ZnN at half the dose of ZnI showed similar or better responses in terms of immunity, SOD-1 expression, hormonal profiles, and the tissue architecture of vital organs in rats, i.e., 25 mg/kg of Zn from ZnI and 12.5 mg/kg of ZnN impacted similar biological responses like immunity, SOD-1 expression, hormonal profiles, and the tissue architecture of vital organs in rats.
Subject(s)
Dietary Supplements , Zinc , Animals , Rats , Zinc/pharmacology , Zinc/metabolism , Superoxide Dismutase-1/genetics , Superoxide Dismutase-1/metabolism , Rats, Wistar , Gene Expression , Liver/metabolism , Superoxide Dismutase/metabolism , DietABSTRACT
[This corrects the article DOI: 10.3389/fncel.2022.1045647.].