Variant-selective stereopure oligonucleotides protect against pathologies associated with C9orf72-repeat expansion in preclinical models

AbstractA large G4C2-repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Neuronal degeneration associated with this expansion arises from a loss of C9orf72 protein, the accumulation of RNA foci, the expression of dipeptide repeat (DPR) proteins, or all these factors. We report the discovery of a new targeting sequence that is common to all C9orf72 transcripts but enables preferential knockdown of repeat-containing transcripts in multiple cellular models and C9BAC transgenic mice. We optimize stereopure oligonucleotides that act through this site, and we demonstrate that their preferential activity depends on both backbone stereochemistry and asymmetric wing design. In mice, stereopure oligonucleotides produce durable depletion of pathogenic signatures without disrupting protein expression. These oligonucleotides selectively protect motor neurons harboring C9orf72-expansion mutation from glutamate-induced toxicity. We hypothesize that targeting C9orf72 with stereopure oligonucleotides may be a viable therapeutic approach for the treatment of C9orf72-associated neurodegenerative disorders.

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The Emerging Role of DNA Damage in the Pathogenesis of the C9orf72 Repeat Expansion in Amyotrophic Lateral Sclerosis

International Journal of Molecular Sciences ◽

10.3390/ijms19103137 ◽

2018 ◽

Vol 19 (10) ◽

pp. 3137 ◽

Cited By ~ 12

Author(s):

Anna Konopka ◽

Julie Atkin

Keyword(s):

Dna Damage ◽

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Repeat Expansion ◽

Chromosome 9 ◽

Gene Encoding ◽

C9orf72 Repeat Expansion ◽

Reading Frame ◽

Early Onset Dementia ◽

Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal, rapidly progressing neurodegenerative disease affecting motor neurons, and frontotemporal dementia (FTD) is a behavioural disorder resulting in early-onset dementia. Hexanucleotide (G4C2) repeat expansions in the gene encoding chromosome 9 open reading frame 72 (C9orf72) are the major cause of familial forms of both ALS (~40%) and FTD (~20%) worldwide. The C9orf72 repeat expansion is known to form abnormal nuclei acid structures, such as hairpins, G-quadruplexes, and R-loops, which are increasingly associated with human diseases involving microsatellite repeats. These configurations form during normal cellular processes, but if they persist they also damage DNA, and hence are a serious threat to genome integrity. It is unclear how the repeat expansion in C9orf72 causes ALS, but recent evidence implicates DNA damage in neurodegeneration. This may arise from abnormal nucleic acid structures, the greatly expanded C9orf72 RNA, or by repeat-associated non-ATG (RAN) translation, which generates toxic dipeptide repeat proteins. In this review, we detail recent advances implicating DNA damage in C9orf72-ALS. Furthermore, we also discuss increasing evidence that targeting these aberrant C9orf72 confirmations may have therapeutic value for ALS, thus revealing new avenues for drug discovery for this disorder.

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Emerging Mechanisms Underpinning Neurophysiological Impairments in C9ORF72 Repeat Expansion-Mediated Amyotrophic Lateral Sclerosis/Frontotemporal Dementia

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.784833 ◽

2021 ◽

Vol 15 ◽

Author(s):

Iris-Stefania Pasniceanu ◽

Manpreet Singh Atwal ◽

Cleide Dos Santos Souza ◽

Laura Ferraiuolo ◽

Matthew R. Livesey

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Frontotemporal Dementia ◽

Motor Neurons ◽

Molecular Mechanisms ◽

Repeat Expansion ◽

Neuronal Function ◽

Repeat Expansion Mutation ◽

Expansion Mutation ◽

The Impact ◽

Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are characterized by degeneration of upper and lower motor neurons and neurons of the prefrontal cortex. The emergence of the C9ORF72 hexanucleotide repeat expansion mutation as the leading genetic cause of ALS and FTD has led to a progressive understanding of the multiple cellular pathways leading to neuronal degeneration. Disturbances in neuronal function represent a major subset of these mechanisms and because such functional perturbations precede degeneration, it is likely that impaired neuronal function in ALS/FTD plays an active role in pathogenesis. This is supported by the fact that ALS/FTD patients consistently present with neurophysiological impairments prior to any apparent degeneration. In this review we summarize how the discovery of the C9ORF72 repeat expansion mutation has contributed to the current understanding of neuronal dysfunction in ALS/FTD. Here, we discuss the impact of the repeat expansion on neuronal function in relation to intrinsic excitability, synaptic, network and ion channel properties, highlighting evidence of conserved and divergent pathophysiological impacts between cortical and motor neurons and the influence of non-neuronal cells. We further highlight the emerging association between these dysfunctional properties with molecular mechanisms of the C9ORF72 mutation that appear to include roles for both, haploinsufficiency of the C9ORF72 protein and aberrantly generated dipeptide repeat protein species. Finally, we suggest that relating key pathological observations in C9ORF72 repeat expansion ALS/FTD patients to the mechanistic impact of the C9ORF72 repeat expansion on neuronal function will lead to an improved understanding of how neurophysiological dysfunction impacts upon pathogenesis.

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Type I PRMT inhibition protects against C9ORF72 arginine-rich dipeptide repeat toxicity

10.1101/2020.05.20.106260 ◽

2020 ◽

Cited By ~ 2

Author(s):

Alan S. Premasiri ◽

Anna L. Gill ◽

Fernando G. Vieira

Keyword(s):

Repeat Expansion ◽

Type I ◽

Arginine Methyltransferase ◽

Repeat Proteins ◽

C9orf72 Gene ◽

Expansion Mutation ◽

Determining Factor ◽

Lateral Sclerosis ◽

Ran Translation ◽

Dipeptide Repeat

ABSTRACTThe most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a repeat expansion mutation in the C9orf72 gene. Repeat-associated non-AUG (RAN) translation of this expansion produces five species of dipeptide repeat proteins (DRPs). The arginine containing DRPs, polyGR and polyPR, are consistently reported to be the most toxic. Here, we uncover Type I protein arginine methyltransferase (PRMT) inhibitors as possible therapeutics for polyGR- and polyPR- related toxicity. Furthermore, we reveal data that suggest that asymmetric dimethylation (ADMe) of polyGR is a determining factor in its pathogenesis.

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Targeting RNA Foci in iPSC-Derived Motor Neurons from ALS Patients with a C9ORF72 Repeat Expansion

Science Translational Medicine ◽

10.1126/scitranslmed.3007529 ◽

2013 ◽

Vol 5 (208) ◽

pp. 208ra149-208ra149 ◽

Cited By ~ 408

Author(s):

D. Sareen ◽

J. G. O'Rourke ◽

P. Meera ◽

A. K. M. G. Muhammad ◽

S. Grant ◽

...

Keyword(s):

Motor Neurons ◽

Repeat Expansion ◽

C9orf72 Repeat Expansion ◽

Rna Foci ◽

Als Patients

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Coexistence of neuronal intranuclear inclusion disease and amyotrophic lateral sclerosis: an autopsy case

BMC Neurology ◽

10.1186/s12883-021-02306-5 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Atsuhiko Sugiyama ◽

Takahiro Takeda ◽

Mizuho Koide ◽

Hajime Yokota ◽

Hiroki Mukai ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neurons ◽

Brain Mri ◽

Brain Magnetic Resonance Imaging ◽

Repeat Expansion ◽

Cerebellar Hemisphere ◽

Intranuclear Inclusions ◽

Intranuclear Inclusion ◽

Neuronal Intranuclear Inclusion ◽

Lateral Sclerosis

Abstract Background Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease. Pathologically, it is characterized by eosinophilic hyaline intranuclear inclusions in the cells of the visceral organs as well as central, peripheral, and autonomic nervous system cells. Recently, a GGC repeat expansion in the NOTCH2NLC gene has been identified as the etiopathological agent of NIID. Interestingly, this GGC repeat expansion was also reported in some patients with a clinical diagnosis of amyotrophic lateral sclerosis (ALS). However, there are no autopsy-confirmed cases of concurrent NIID and ALS. Case presentation A 60-year-old Taiwanese woman reported a four-month history of progressive weakness beginning in the right foot that spread to all four extremities. She was diagnosed with ALS because she met the revised El Escorial diagnostic criteria for definite ALS with upper and lower motor neuron involvement in the cervical, thoracic, and lumbosacral regions. She died of respiratory failure at 22 months from ALS onset, at the age of 62 years. Brain magnetic resonance imaging (MRI) revealed lesions in the medial part of the cerebellar hemisphere, right beside the vermis (paravermal lesions). The subclinical neuropathy, indicated by a nerve conduction study (NCS), prompted a potential diagnosis of NIID. Antemortem skin biopsy and autopsy confirmed the coexistence of pathology consistent with both ALS and NIID. We observed neither eccentric distribution of p62-positive intranuclear inclusions in the areas with abundant large motor neurons nor cytopathological coexistence of ALS and NIID pathology in motor neurons. This finding suggested that ALS and NIID developed independently in this patient. Conclusions We describe a case of concurrent NIID and ALS discovered during an autopsy. Abnormal brain MRI findings, including paravermal lesions, could indicate the coexistence of NIID even in patients with ALS showing characteristic clinical phenotypes.

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The nuclear ubiquitin ligase adaptor SPOP is a conserved regulator of C9orf72 dipeptide toxicity

10.1101/2021.03.09.434618 ◽

2021 ◽

Author(s):

Carley Snoznik ◽

Valentina Medvedeva ◽

Jelena Mojsilovic-Petrovic ◽

Paige Rudich ◽

James Oosten ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Nuclear Localization ◽

Ubiquitin Ligase ◽

E3 Ubiquitin Ligase ◽

Repeat Expansion ◽

Dipeptide Repeat Proteins ◽

C Elegans ◽

Repeat Proteins ◽

Lateral Sclerosis ◽

Dipeptide Repeat

AbstractA hexanucleotide repeat expansion in the C9orf72 gene is the most common cause of inherited amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Unconventional translation of the C9orf72 repeat produces dipeptide repeat proteins (DPRs). Previously, we showed that the DPRs (PR)50 and (GR)50 are highly toxic when expressed in C. elegans and this toxicity depends on nuclear localization of the DPR. In an unbiased genome-wide RNAi screen for suppressors of (PR)50 toxicity, we identified 12 genes that consistently suppressed either the developmental arrest and/or paralysis phenotype evoked by (PR)50 expression. All of these genes have vertebrate homologs and 7/12 contain predicted nuclear localization signals. One of these genes was spop-1, the C. elegans homolog of SPOP, a nuclear localized E3 ubiquitin ligase adaptor only found in metazoans. SPOP is also required for (GR)50 toxicity and functions in a genetic pathway that includes cul-3, which is the canonical E3 ligase partner for SPOP. Genetic or pharmacological inhibition of SPOP in mammalian primary spinal cord motor neurons suppressed DPR toxicity without affecting DPR expression levels. Finally, we find that genetic inhibition of bet-1, the C. elegans homolog of the known SPOP ubiquitination targets BRD2/3/4, suppresses the protective effect of SPOP mutations. Together, these data suggest a model in which SPOP promotes the DPR-dependent ubiquitination and degradation of BRD proteins. We speculate the pharmacological manipulation of this pathway, which is currently underway for multiple cancer subtypes, could also represent a novel entry point for therapeutic intervention to treat C9 FTD/ALS.Significance statementThe G4C2 repeat expansion in the C9orf72 gene is a major cause of Fronto-Temporal Dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS). Unusual translation of the repeat sequence produces two highly toxic dipeptide repeat proteins, PRX and GRX, which accumulate in the brain tissue of individuals with these diseases. Here, we show that PR and GR toxicity in both C. elegans and mammalian neurons depends on the E3 ubiquitin ligase adaptor SPOP. SPOP acts through the bromodomain protein BET-1 to mediate dipeptide toxicity. SPOP inhibitors, which are currently being developed to treat SPOP-dependent renal cancer, also protect neurons against DPR toxicity. Our findings identify a highly conserved and ‘druggable’ pathway that may represent a new strategy for treating these currently incurable diseases.

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C9ORF72 Repeat Expansion Affects the Proteome of Primary Skin Fibroblasts in ALS

International Journal of Molecular Sciences ◽

10.3390/ijms221910385 ◽

2021 ◽

Vol 22 (19) ◽

pp. 10385

Author(s):

Marta Lualdi ◽

Adeena Shafique ◽

Edoardo Pedrini ◽

Luisa Pieroni ◽

Viviana Greco ◽

...

Keyword(s):

Motor Neurons ◽

Interaction Network ◽

Enrichment Analysis ◽

Repeat Expansion ◽

Skin Fibroblasts ◽

Chromosome 9 ◽

Functional Enrichment ◽

Molecular Pathways ◽

C9orf72 Repeat Expansion ◽

Als Patients

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive degeneration of the corticospinal motor neurons, which ultimately leads to death. The repeat expansion in chromosome 9 open reading frame 72 (C9ORF72) represents the most common genetic cause of ALS and it is also involved in the pathogenesis of other neurodegenerative disorders. To offer insights into C9ORF72-mediated pathogenesis, we quantitatively analyzed the proteome of patient-derived primary skin fibroblasts from ALS patients carrying the C9ORF72 mutation compared with ALS patients who tested negative for it. Differentially expressed proteins were identified, used to generate a protein-protein interaction network and subjected to a functional enrichment analysis to unveil altered molecular pathways. ALS patients were also compared with patients affected by frontotemporal dementia carrying the C9ORF72 repeat expansion. As a result, we demonstrated that the molecular pathways mainly altered in fibroblasts (e.g., protein homeostasis) mirror the alterations observed in C9ORF72-mutated neurons. Moreover, we highlighted novel molecular pathways (nuclear and mitochondrial transports, vesicle trafficking, mitochondrial bioenergetics, glucose metabolism, ER-phagosome crosstalk and Slit/Robo signaling pathway) which might be further investigated as C9ORF72-specific pathogenetic mechanisms. Data are available via ProteomeXchange with the identifier PXD023866.

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C9ORF72 Repeat Expansion in Amyotrophic Lateral Sclerosis in the Kii Peninsula of Japan

Archives of Neurology ◽

10.1001/archneurol.2012.1219 ◽

2012 ◽

Vol 69 (9) ◽

Cited By ~ 69

Author(s):

Hiroyuki Ishiura ◽

Yuji Takahashi ◽

Jun Mitsui ◽

Sohei Yoshida ◽

Tameko Kihira ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Repeat Expansion ◽

Kii Peninsula ◽

C9orf72 Repeat Expansion ◽

Lateral Sclerosis

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Selective neuronal degeneration in MATR3 S85C knock-in mouse model of early-stage ALS

Nature Communications ◽

10.1038/s41467-020-18949-w ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Ching Serena Kao ◽

Rebekah van Bruggen ◽

Jihye Rachel Kim ◽

Xiao Xiao Lily Chen ◽

Cadia Chan ◽

...

Keyword(s):

Spinal Cord ◽

Mouse Model ◽

Motor Neurons ◽

Neuronal Degeneration ◽

Early Stage ◽

Motor Impairment ◽

Preclinical Research ◽

Cell Degeneration ◽

Promising Tool ◽

Lateral Sclerosis

Abstract A missense mutation, S85C, in the MATR3 gene is a genetic cause for amyotrophic lateral sclerosis (ALS). It is unclear how the S85C mutation affects MATR3 function and contributes to disease. Here, we develop a mouse model that harbors the S85C mutation in the endogenous Matr3 locus using the CRISPR/Cas9 system. MATR3 S85C knock-in mice recapitulate behavioral and neuropathological features of early-stage ALS including motor impairment, muscle atrophy, neuromuscular junction defects, Purkinje cell degeneration and neuroinflammation in the cerebellum and spinal cord. Our neuropathology data reveals a loss of MATR3 S85C protein in the cell bodies of Purkinje cells and motor neurons, suggesting that a decrease in functional MATR3 levels or loss of MATR3 function contributes to neuronal defects. Our findings demonstrate that the MATR3 S85C mouse model mimics aspects of early-stage ALS and would be a promising tool for future basic and preclinical research.

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