Selective Vulnerability of Tripartite Synapses in Amyotrophic Lateral Sclerosis

Broadhead, MJ; Bonthron, Calum; Waddington, Julia; Smith, WV; Lopez, MF; Burley, Sarah; Valli, Jessica; Zhu, Fei; Komiyama, NH; Smith, Colin; Grant, Sgn; Miles, Gareth B.

doi:10.1101/2021.10.28.465435

Cited by 5 publications

(9 citation statements)

References 83 publications

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“…The PSD95-eGFP mouse is a genetically engineered in-frame fusion knock-in mouse that fuses the enhanced green fluorescent protein (eGFP) to the C-terminal of the endogenous PSD95 protein, enabling the visualisation of postsynaptic densities (PSDs) of excitatory synapses throughout the nervous system. As characterised previously, SOD1 G93a x PSD95-eGFP progeny display similar weights and behavioural phenotypes as expected from 'pure' SOD1 G93a mice, with the onset of hindlimb tremors and reduced hind-limb splay by approximately 75 days of age (Broadhead et al, 2022;Mead et al, 2011).…”

Section: Animals and Ethicssupporting

confidence: 71%

“…Amyotrophic Lateral Sclerosis (ALS) is characterised by a progressive loss of motor control due to a loss of motor neurons (MNs) in the spinal cord, brain stem, and motor cortex. Prior to MN loss, structural and functional changes in synapses have been reported between neurons in both the brain and spinal cord (Bączyk et al, 2020;Broadhead et al, 2022;Fogarty et al, 2015Fogarty et al, , 2016Jiang et al, 2019). Synaptopathy in ALS is characterized by early stage hyper-excitability, that may induce excitotoxicity, and a later stage loss of vulnerable synapse subtypes (Broadhead et al, 2022;Fogarty, 2019;Van Zundert et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…MNs, for example, receive numerous different types of synaptic inputs, from excitatory, inhibitory and modulatory synapses derived from descending inputs from the brain, local spinal cord interneurons and sensory neurons. Not all synapses are equal, as some may be more selectively targeted in certain disease conditions (Bączyk et al, 2020;Broadhead et al, 2022;Herron & Miles, 2012;Mentis et al, 2011;Sunico et al, 2011). Understanding the expression of TDP-43 in different types of synapses in the spinal cord may provide insights into the selective vulnerability of certain synapses and pathways in ALS and therefore advance knowledge of the pathogenic mechanisms underlying this devastating disease.…”

Section: Introductionmentioning

confidence: 99%

“…Prior to MN loss, structural and functional changes in synapses have been reported between neurons in both the brain and spinal cord (Bączyk et al, 2020;Broadhead et al, 2022;Fogarty et al, 2015Fogarty et al, , 2016Jiang et al, 2019). Synaptopathy in ALS is characterized by early stage hyper-excitability, that may induce excitotoxicity, and a later stage loss of vulnerable synapse subtypes (Broadhead et al, 2022;Fogarty, 2019;Van Zundert et al, 2008). The molecular mechanisms of ALS synaptopathy, however, are not fully understood.…”

Section: Introductionmentioning

confidence: 99%

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Synaptic Expression of TAR-DNA-Binding Protein 43 in the Mouse Spinal Cord Determined Using Super-Resolution Microscopy

Broadhead

Doucet

Kantelberg

et al. 2022

Preprint

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Cellular inclusions of hyperphosphorylated TAR-DNA-Binding Protein 43 (TDP-43) are a key hallmark of neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS). ALS is characterised by a loss of motor neurons in the brain and spinal cord that is preceded by early-stage changes in synaptic function that may be associated with TDP-43 pathology. However, there has been little characterisation of the synaptic expression of TDP-43 in spinal cord synapses. This study utilises a range of high-resolution and super-resolution microscopy techniques with immunolabelling, as well as an aptamer-based TDP-43 labelling strategy visualised with single-molecule localisation microscopy, to characterise and quantify the presence of phosphorylated TDP-43 (pTDP-43) in spinal cord synapses. We observe that TDP-43 is expressed in the majority of spinal cord synapses as nanoscale clusters as small as 60 nm in diameter. Synaptic TDP-43 expression is more frequently associated with presynaptic terminals than postsynaptic densities, and is more enriched in VGLUT1-associated synapses, compared to VGLUT2-associated synapses. Our nanoscopy techniques showed no difference in the subsynaptic expression of pTDP-43 in the ALS mouse model, SOD1G93a compared to healthy controls. This research characterizes the basic synaptic expression of TDP-43 with nanoscale precision and provides a framework with which to investigate the potential relationship between TDP-43 pathology and synaptic pathology in neurodegenerative diseases.

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Section: Animals and Ethicssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Synaptic Expression of TAR-DNA-Binding Protein 43 in the Mouse Spinal Cord Determined Using Super-Resolution Microscopy

Broadhead

Doucet

Kantelberg

et al. 2022

Preprint

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“…We also observed increased expression of GFAP in BA4 (Figure 2F), highlighting complex bidirectional changes in astrocytic proteins around ALS synapses. This has gained added significance following a recent study highlighting GFAP-containing tripartite synapses as the most vulnerable subtype in ALS spinal cord [64].…”

Section: A Heatmap Showing the Protein Expression Differences Between...mentioning

confidence: 99%

Synaptic proteomics reveal distinct molecular signatures of cognitive change andC9ORF72repeat expansion in the human ALS cortex

László

Hindley

Avila

et al. 2022

Preprint

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The two major hypotheses of Amyotrophic Lateral Sclerosis (ALS) pathogenesis (dying-forward and dying-back) have synapses at their core. Furthermore, increasing evidence suggests synaptic dysfunction is a central and possibly triggering factor in ALS. Despite this, we still know very little about the molecular profile of an ALS synapse. To address this gap, we designed a synaptic proteomics experiment to perform an unbiased assessment of the synaptic proteome in the ALS brain. We isolated synaptoneurosomes from fresh-frozen post-mortem human cortex (11 controls and 18 ALS) and stratified the ALS group based on cognitive profile (Edinburgh Cognitive and Behavioural ALS Screen (ECAS score)) and presence of a C9ORF72 hexanucleotide repeat expansion (C9ORF72-RE). This allowed us to assess regional differences and the impact of phenotype and genotype on the synaptic proteome, using Tandem Mass Tagging-based proteomics. We identified over 6000 proteins in our synaptoneurosomes and using robust bioinformatics analysis we validated the strong enrichment of synapses. We found more than 30 ALS-associated proteins at the synapse, including TDP-43, FUS, SOD1 and C9ORF72. We identified almost 500 proteins with altered expression levels in ALS synapses, with region-specific changes highlighting proteins and pathways with intriguing links to neurophysiology and pathology. Stratifying the ALS cohort by cognitive status revealed almost 150 specific alterations in cognitively impaired ALS synapses, highlighting novel synaptic proteins that may underlie the synaptic vulnerability in these patients. Stratifying by C9ORF72-RE status revealed 330 protein alterations in the C9ORF72-RE+ve group, with KEGG pathway analysis highlighting strong enrichment for postsynaptic dysfunction, related to glutamatergic receptor signalling. We have validated some of these changes by western blot and at a single synapse level using array tomography imaging. In summary, we have generated the first unbiased map of the human ALS synaptic proteome, revealing novel insight into this key compartment in ALS pathophysiology and highlighting the influence of cognitive decline and C9ORF72-RE on synaptic composition.

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Cytoplasmic TDP-43 accumulation drives changes in C-bouton number and size in a mouse model of sporadic Amyotrophic Lateral Sclerosis

Bak

Djukic

Kadlecova

et al. 2023

Molecular and Cellular Neuroscience

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Selective Vulnerability of Tripartite Synapses in Amyotrophic Lateral Sclerosis

Cited by 5 publications

References 83 publications

Synaptic Expression of TAR-DNA-Binding Protein 43 in the Mouse Spinal Cord Determined Using Super-Resolution Microscopy

Synaptic Expression of TAR-DNA-Binding Protein 43 in the Mouse Spinal Cord Determined Using Super-Resolution Microscopy

Synaptic proteomics reveal distinct molecular signatures of cognitive change andC9ORF72repeat expansion in the human ALS cortex

Cytoplasmic TDP-43 accumulation drives changes in C-bouton number and size in a mouse model of sporadic Amyotrophic Lateral Sclerosis

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