scholarly journals Aggregate-selective antibody attenuates seeded aggregation but not spontaneously evolving disease in SOD1 ALS model mice

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Manuela Lehmann ◽  
Matthew Marklund ◽  
Anna-Lena Bolender ◽  
Elaheh E. Bidhendi ◽  
Per Zetterström ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Superoxide Dismutase 1 ◽  
Transgenic Mouse Models ◽  
Contrast Administration ◽  
Spinal Motor Neurons ◽  
Associated Proteins ◽  
Term Administration ◽  
Lateral Sclerosis

Abstract Increasing evidence suggests that propagation of the motor neuron disease amyotrophic lateral sclerosis (ALS) involves the pathogenic aggregation of disease-associated proteins that spread in a prion-like manner. We have identified two aggregate strains of human superoxide dismutase 1 (hSOD1) that arise in the CNS of transgenic mouse models of SOD1-mediated ALS. Both strains transmit template-directed aggregation and premature fatal paralysis when inoculated into the spinal cord of adult hSOD1 transgenic mice. This spread of pathogenic aggregation could be a potential target for immunotherapeutic intervention. Here we generated mouse monoclonal antibodies (mAbs) directed to exposed epitopes in hSOD1 aggregate strains and identified an aggregate selective mAb that targets the aa 143–153 C-terminal extremity of hSOD1 (αSOD1143–153). Both pre-incubation of seeds with αSOD1143–153 prior to inoculation, and weekly intraperitoneal (i.p.) administration attenuated transmission of pathogenic aggregation and prolonged the survival of seed-inoculated hSOD1G85R Tg mice. In contrast, administration of a mAb targeting aa 65–72 (αSOD165–72), which exhibits high affinity towards monomeric disordered hSOD1, had an adverse effect and aggravated seed induced premature ALS-like disease. Although the mAbs reached similar concentrations in CSF, only αSOD1143–153 was found in association with aggregated hSOD1 in spinal cord homogenates. Our results suggest that an aggregate-selective immunotherapeutic approach may suppress seeded transmission of pathogenic aggregation in ALS. However, long-term administration of αSOD1143–153 was unable to prolong the lifespan of non-inoculated hSOD1G85R Tg mice. Thus, spontaneously initiated hSOD1 aggregation in spinal motor neurons may be poorly accessible to therapeutic antibodies.

scholarly journals Perspective on SOD1 mediated toxicity in Amyotrophic Lateral Sclerosis

2016 ◽  
Vol 62 (3) ◽  
pp. 362-369
Author(s):  
Smriti Sangwan ◽  
David S Eisenberg
Keyword(s):  
Motor Neurons ◽  
Superoxide Dismutase 1 ◽  
Mutant Sod1 ◽  
Spinal Motor Neurons ◽  
Familial Cases ◽  
Progressive Degeneration ◽  
Spinal Motor ◽  
Therapeutic Development ◽  
Enzyme Superoxide Dismutase ◽  
Lateral Sclerosis

A myotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of spinal motor neurons. Although mutations in dozens of proteins have been associated with ALS, the enzyme, superoxide dismutase 1 (SOD1) was the first protein identified with the development of ALS and accounts for ~20% of familial cases. In experimental animals and patient samples, mutant SOD1 is found in cytoplasmic deposits implicating SOD1 aggregates as the toxic entities. Here we discuss the various biochemical and structure-based hypotheses proposed for mutant SOD1-associated ALS. Although much remains to be discovered about the molecular mechanism of SOD1 mediated toxicity, these hypotheses offer new avenues for therapeutic development.

scholarly journals Misfolded SOD1 inclusions in patients with mutations in C9orf72 and other ALS/FTD-associated genes

2019 ◽  
Vol 90 (8) ◽  
pp. 861-869 ◽  
Author(s):  
Karin Forsberg ◽  
Karin Graffmo ◽  
Bente Pakkenberg ◽  
Markus Weber ◽  
Martin Nielsen ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Superoxide Dismutase 1 ◽  
Wild Type ◽  
Spinal Motor Neurons ◽  
Hexanucleotide Repeat ◽  
Cortical Motor ◽  
Spinal Motor ◽  
Repeat Expansions ◽  
Misfolded Sod1 ◽  
Lateral Sclerosis

ObjectiveA hallmark of amyotrophic lateral sclerosis (ALS) caused by mutations in superoxide dismutase-1 (SOD1) are inclusions containing SOD1 in motor neurons. Here, we searched for SOD1-positive inclusions in 29 patients carrying ALS-linked mutations in six other genes.MethodsA panel of antibodies that specifically recognise misfolded SOD1 species were used for immunohistochemical investigations of autopsy tissue.ResultsThe 18 patients with hexanucleotide-repeat-expansions in C9orf72 had inclusions of misfolded wild type (WT) SOD1WT in spinal motor neurons. Similar inclusions were occasionally observed in medulla oblongata and in the motor cortex and frontal lobe. Patients with mutations in FUS, KIF5A, NEK1, ALSIN or VAPB, carried similar SOD1WT inclusions. Minute amounts of misSOD1WT inclusions were detected in 2 of 20 patients deceased from non-neurological causes and in 4 of 10 patients with other neurodegenerative diseases. Comparison was made with 17 patients with 9 different SOD1 mutations. Morphologically, the inclusions in patients with mutations in C9orf72HRE, FUS, KIF5A, NEK1, VAPB and ALSIN resembled inclusions in patients carrying the wildtype-like SOD1D90A mutation, whereas patients carrying unstable SOD1 mutations (A4V, V5M, D76Y, D83G, D101G, G114A, G127X, L144F) had larger skein-like SOD1-positive inclusions.Conclusions and relevanceAbundant inclusions containing misfolded SOD1WT are found in spinal and cortical motor neurons in patients carrying mutations in six ALS-causing genes other than SOD1. This suggests that misfolding of SOD1WT can be part of a common downstream event that may be pathogenic. The new anti-SOD1 therapeutics in development may have applications for a broader range of patients.

scholarly journals Optogenetic modulation of TDP-43 oligomerization fast-forwards ALS-related pathologies in the spinal motor neurons

2019 ◽  
Author(s):  
Kazuhide Asakawa ◽  
Hiroshi Handa ◽  
Koichi Kawakami
Keyword(s):  
Motor Neurons ◽  
Light Illumination ◽  
Short Term ◽  
Spinal Motor Neuron ◽  
Spinal Motor Neurons ◽  
Intrinsically Disordered ◽  
Spinal Motor ◽  
Lateral Sclerosis

AbstractCytoplasmic aggregation of TDP-43 characterizes degenerating neurons in most cases of amyotrophic lateral sclerosis (ALS), yet the mechanisms and cellular outcomes of TDP-43 pathology remain largely elusive. Here, we develop an optogenetic TDP-43 variant (opTDP-43), whose multimerization status can be modulated in vivo through external light illumination. Using the translucent zebrafish neuromuscular system, we demonstrate that short-term light stimulation reversibly induces cytoplasmic opTDP-43 mislocalization, but not aggregation, in the spinal motor neuron, leading to an axon outgrowth defect associated with myofiber denervation. In contrast, opTDP-43 forms pathological aggregates in the cytoplasm after longer-term illumination and seeds non-optogenetic TDP-43 aggregation. Furthermore, we find that an ALS-linked mutation in the intrinsically disordered region (IDR) exacerbates the light-dependent opTDP-43 toxicity on locomotor behavior. Together, our results propose that IDR-mediated TDP-43 oligomerization triggers both acute and long-term pathologies of motor neurons, which may be relevant to the pathogenesis and progression of ALS.

scholarly journals Acute neurotoxicant exposure induces hyperexcitability in mouse lumbar spinal motor neurons

2020 ◽  
Vol 123 (4) ◽  
pp. 1448-1459 ◽  
Author(s):  
Michael P. Sceniak ◽  
Jake B. Spitsbergen ◽  
Shasta L. Sabo ◽  
Yukun Yuan ◽  
William D. Atchison
Keyword(s):  
Spinal Cord ◽  
Motor Neurons ◽  
Normal Function ◽  
Mehg Exposure ◽  
Toxicant Exposure ◽  
Spinal Motor Neurons ◽  
Spinal Motor ◽  
Sporadic Als ◽  
Lumbar Spinal ◽  
Lateral Sclerosis

Spinal motor neurons (MNs) are susceptible to glutamatergic excitotoxicity, an effect associated with lumbar MN degeneration in amyotrophic lateral sclerosis (ALS). MN susceptibility to environmental toxicant exposure, one prospective contributor to sporadic ALS, has not been systematically studied. The goal of this study was to test the ability of a well-known environmental neurotoxicant to induce hyperexcitability in mouse lumbar MNs. Methylmercury (MeHg) causes neurotoxicity through mechanisms involving elevated intracellular Ca2+ concentration ([Ca2+]i), a hallmark of excitotoxicity. We tested whether acute exposure to MeHg induces hyperexcitability in MNs by altering synaptic transmission, using whole cell patch-clamp recordings of lumbar spinal MNs in vitro. Acute MeHg exposure (20 μM) led to an increase in the frequency of both spontaneous excitatory postsynaptic currents (EPSCs) and miniature EPSCs. The frequency of inhibitory postsynaptic currents (IPSCs) was also increased by MeHg. Action potential firing rates, both spontaneous and evoked, were increased by MeHg, despite increases in both EPSCs and IPSCs, indicating a shift toward hyperexcitability. Also consistent with hyperexcitability, fluo 4-AM microfluorimetry indicated that MeHg exposure induced an increase in [Ca2+]i. Spinal cord hyperexcitability is partially mediated by Ca2+-permeable AMPA receptors, as MeHg-dependent increases in EPSCs were blocked by 1-napthyl spermine. Therefore, spinal MNs appear highly susceptible to MeHg exposure, leading to significant increases in spontaneous network excitability and disruption of normal function. Prolonged hyperexcitability could lead to eventual neurodegeneration and loss of motor function as observed in spinal cord after MeHg exposure in vivo and may contribute to MeHg-induced acceleration of ALS symptoms. NEW & NOTEWORTHY Spinal motor neurons (MN) are susceptible to glutamatergic excitotoxicity, an effect associated with lumbar MN degeneration in amyotrophic lateral sclerosis (ALS). This study investigated MN susceptibility to environmental toxicant exposure, one prospective contributor to sporadic ALS. Spinal MNs appear highly susceptible to methylmercury exposure, leading to significant increases in spontaneous network excitability and disruption of normal function. Prolonged hyperexcitability could lead to neurodegeneration and loss of motor function as observed in ALS spinal cord symptoms.

scholarly journals Transfer of pathogenic and nonpathogenic cytosolic proteins between spinal cord motor neurons in vivo in chimeric mice

2017 ◽  
Vol 114 (15) ◽  
pp. E3139-E3148 ◽  
Author(s):  
Eleanor V. Thomas ◽  
Wayne A. Fenton ◽  
James McGrath ◽  
Arthur L. Horwich
Keyword(s):  
Spinal Cord ◽  
Amyotrophic Lateral Sclerosis ◽  
Motor Neurons ◽  
Small Cells ◽  
Superoxide Dismutase 1 ◽  
Temporal Development ◽  
Chimeric Mice ◽  
Cytosolic Proteins ◽  
Lateral Sclerosis

Recent studies have reported spread of pathogenic proteins in the mammalian nervous system, but whether nonpathogenic ones spread is unknown. We initially investigated whether spread of a mutant amyotrophic lateral sclerosis-associated cytosolic superoxide dismutase 1 (SOD1) protein between motor neurons could be detected in intact chimeric mice. Eight-cell embryos from G85R SOD1YFP and G85R SOD1CFP mice were aggregated, and spinal cords of adult chimeric progeny were examined for motor neurons with cytosolic double fluorescence. By 3 mo of age, we observed extensive double fluorescence, including in amyotrophic lateral sclerosis-affected cranial nerve motor nuclei but not in the relatively spared extraocular nuclei. Chimeras of nonpathogenic wtSOD1YFP and G85R SOD1CFP also exhibited double fluorescence. In a third chimera, mitochondrial mCherry did not transfer to G85R SOD1YFP motor neurons, suggesting that neither RNA nor organelles transfer, but mito-mCherry neurons received G85R SOD1YFP. In a chimera of ChAT promoter-EGFP and mito-mCherry, EGFP efficiently transferred to mito-mCherry+ cells. Thus, nonpathogenic cytosolic proteins appear capable of transfer. During study of both the SOD1FP and EGFP chimeras, we observed fluorescence also in small cells neighboring the motor neurons, identified as mature gray matter oligodendrocytes. Double fluorescence in the G85R SOD1FP chimera and observation of the temporal development of fluorescence first in motor neurons and then in these oligodendrocytes suggest that they may be mediators of transfer of cytosolic proteins between motor neurons.

scholarly journals Restoration of breathing after opioid overdose and spinal cord injury using temporal interference stimulation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Michael D. Sunshine ◽  
Antonino M. Cassarà ◽  
Esra Neufeld ◽  
Nir Grossman ◽  
Thomas H. Mareci ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Motor Neurons ◽  
Drug Overdose ◽  
Cervical Spinal Cord ◽  
Opioid Overdose ◽  
Electrode Position ◽  
Spinal Motor Neurons ◽  
Cord Injury ◽  
Low Amplitude

AbstractRespiratory insufficiency is a leading cause of death due to drug overdose or neuromuscular disease. We hypothesized that a stimulation paradigm using temporal interference (TI) could restore breathing in such conditions. Following opioid overdose in rats, two high frequency (5000 Hz and 5001 Hz), low amplitude waveforms delivered via intramuscular wires in the neck immediately activated the diaphragm and restored ventilation in phase with waveform offset (1 Hz or 60 breaths/min). Following cervical spinal cord injury (SCI), TI stimulation via dorsally placed epidural electrodes uni- or bilaterally activated the diaphragm depending on current and electrode position. In silico modeling indicated that an interferential signal in the ventral spinal cord predicted the evoked response (left versus right diaphragm) and current-ratio-based steering. We conclude that TI stimulation can activate spinal motor neurons after SCI and prevent fatal apnea during drug overdose by restoring ventilation with minimally invasive electrodes.

scholarly journals RBM45 Modulates the Antioxidant Response in Amyotrophic Lateral Sclerosis through Interactions with KEAP1

2015 ◽  
Vol 35 (14) ◽  
pp. 2385-2399 ◽  
Author(s):  
Nadine Bakkar ◽  
Arianna Kousari ◽  
Tina Kovalik ◽  
Yang Li ◽  
Robert Bowser
Keyword(s):  
Oxidative Stress ◽  
Spinal Cord ◽  
Amyotrophic Lateral Sclerosis ◽  
Motor Neurons ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Antioxidant Response ◽  
Cytoplasmic Inclusions ◽  
Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the selective loss of motor neurons. Various factors contribute to the disease, including RNA binding protein dysregulation and oxidative stress, but their exact role in pathogenic mechanisms remains unclear. We have recently linked another RNA binding protein, RBM45, to ALS via increased levels of protein in the cerebrospinal fluid of ALS patients and its localization to cytoplasmic inclusions in ALS motor neurons. Here we show RBM45 nuclear exit in ALS spinal cord motor neurons compared to controls, a phenotype recapitulatedin vitroin motor neurons treated with oxidative stressors. We find that RBM45 binds and stabilizes KEAP1, the inhibitor of the antioxidant response transcription factor NRF2. ALS lumbar spinal cord lysates similarly show increased cytoplasmic binding of KEAP1 and RBM45. Binding of RBM45 to KEAP1 impedes the protective antioxidant response, thus contributing to oxidative stress-induced cellular toxicity. Our findings thus describe a novel link between a mislocalized RNA binding protein implicated in ALS (RBM45) and dysregulation of the neuroprotective antioxidant response seen in the disease.

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