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Epigenetics in Amyotrophic Lateral Sclerosis
Epigenetics in Amyotrophic Lateral Sclerosis
Introduction
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive loss of upper and lower motor [neurons](/entities/neurons), leading to muscle weakness, paralysis, and typically death within 2-5 years of symptom onset. Approximately 10% of ALS cases are familial, with the remaining 90% being sporadic. While significant progress has been made in identifying genetic causes—including mutations in [SOD1](/genes/sod1), [C9orf72](/genes/c9orf72), [FUS](/genes/fus), and [TARDBP](/genes/tardbp)—the mechanisms underlying disease initiation and progression remain incompletely understood.
Epigenetic modifications have emerged as critical regulators of ALS pathogenesis, influencing gene expression patterns, cellular stress responses, RNA metabolism, and protein homeostasis. The reversible nature of epigenetic changes makes them attractive therapeutic targets, with several epigenetic therapies currently in clinical development. This page provides a comprehensive overview of epigenetic mechanisms in ALS, including [DNA methylation](/entities/dna-methylation), [histone modifications](/entities/histone-modifications), non-coding RNAs, and chromatin remodeling.
Overview of Epigenetic Dysregulation in ALS
ALS demonstrates widespread epigenetic alterations that affect multiple cellular pathways:
Epigenetics in Amyotrophic Lateral Sclerosis
Introduction
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive loss of upper and lower motor [neurons](/entities/neurons), leading to muscle weakness, paralysis, and typically death within 2-5 years of symptom onset. Approximately 10% of ALS cases are familial, with the remaining 90% being sporadic. While significant progress has been made in identifying genetic causes—including mutations in [SOD1](/genes/sod1), [C9orf72](/genes/c9orf72), [FUS](/genes/fus), and [TARDBP](/genes/tardbp)—the mechanisms underlying disease initiation and progression remain incompletely understood.
Epigenetic modifications have emerged as critical regulators of ALS pathogenesis, influencing gene expression patterns, cellular stress responses, RNA metabolism, and protein homeostasis. The reversible nature of epigenetic changes makes them attractive therapeutic targets, with several epigenetic therapies currently in clinical development. This page provides a comprehensive overview of epigenetic mechanisms in ALS, including [DNA methylation](/entities/dna-methylation), [histone modifications](/entities/histone-modifications), non-coding RNAs, and chromatin remodeling.
Overview of Epigenetic Dysregulation in ALS
ALS demonstrates widespread epigenetic alterations that affect multiple cellular pathways:
- RNA metabolism: [TDP-43](/mechanisms/tdp-43-proteinopathy) pathology is closely linked to RNA processing abnormalities [@neumann2006]
- Protein homeostasis: Epigenetic regulation of [autophagy](/entities/autophagy) and proteasome pathways [@chen2019]
- Neuroinflammation: Glial activation patterns controlled by epigenetic mechanisms [@pradhan2019]
- Metabolic dysfunction: Energy homeostasis alterations in motor neurons [@pample2019]
- Excitotoxicity: Glutamate transporter regulation [@kimel2019]
The interface between genetic mutations and epigenetic dysregulation is particularly important in ALS, as mutant proteins directly affect epigenetic machinery.
DNA Methylation in ALS
DNA methylation patterns are significantly altered in ALS, affecting both disease-specific genes and global methylation status.
C9orf72 Methylation
The [C9orf72](/genes/c9orf72) hexanucleotide repeat expansion is the most common genetic cause of familial ALS:
- Repeat-associated non-ATG (RAN) translation produces toxic dipeptide repeat proteins (DPRs) [@mori2013]
- DNA methylation at the [C9orf72](/entities/c9orf72) promoter correlates with:
- Repeat expansion size [@liu2014]
- Age of onset [@mcgann2019]
- Disease duration [@gijselinck2016]
- Hypermethylation of the C9orf72 promoter can reduce toxic expression [@russ2015]
- The methylation status varies across brain regions [@baird2018]
SOD1 Methylation
The [SOD1](/genes/sod1) gene, mutated in ~20% of familial ALS cases:
- Promoter methylation affects SOD1 expression [@kunst2017]
- Differential methylation between ALS subtypes [@coppolasegovia2019]
- Epigenetic therapy targeting SOD1 methylation is under investigation [@martinez2018]
TDP-43 Methylation
[TARDBP](/genes/tardbp) encoding [TDP-43](/proteins/tardbp-protein) is central to ALS pathogenesis:
- TDP-43 proteinopathy affects ~95% of ALS cases [@arai2006]
- Epigenetic regulation of TDP-43 expression is being characterized [@vaccaro2019]
- Methyl-CpG binding proteins interact with TDP-43 aggregates [@rohan2018]
Global DNA Methylation Changes
- Global hypomethylation has been observed in ALS motor [cortex](/brain-regions/cortex) and spinal cord [@chestnut2011]
- Region-specific patterns distinguish ALS from controls [@martin2019]
- Peripheral blood methylation shows potential as biomarker [@kadhim2019]
Epigenetic Clock in ALS
- Accelerated epigenetic aging documented in ALS [@zhang2019]
- Age-dependent methylation patterns correlate with progression [@swart2020]
- DNA methylation age differs between ALS subtypes [@bouhrara2019]
Therapeutic Implications
- DNMT inhibitors are being explored to modulate pathogenic gene expression [@rouaux2007]
- Epigenetic readers as novel therapeutic targets [@kelley2019]
Histone Modifications in ALS
Histone modifications are extensively dysregulated in ALS, affecting transcription of genes critical for motor neuron survival.
Histone Acetylation
HDAC Dysregulation
Histone deacetylases (HDACs) are major therapeutic targets:
- [HDAC](/entities/hdac-enzymes) inhibitor therapy has shown promise in ALS models [@rouaux2003]
- Class I HDACs (HDAC1, 2, 3): Elevated in ALS tissue [@janssen2010]
- HDAC2: Specifically upregulated in motor neurons [@kim2018]
- HDAC4/5: Redistribute in ALS, affecting nuclear-cytoplasmic transport [@jiang2019]
- HDAC6: Regulates autophagy and aggresome formation [@du2019]
Histone Acetylation Marks
- H3K9ac: Reduced at neuroprotective gene promoters [@chen2019a]
- H3K27ac: Altered at enhancer regions [@tao2019]
- H4K12ac: Dysregulated in ALS models [@lee2019]
Histone Methylation
Active Marks
- H3K4me3: Redistributed in ALS motor cortex [@liu2019]
- H3K36me3: Altered in genes involved in RNA splicing [@yuan2019]
Repressive Marks
- H3K27me3: Increased at certain gene promoters [@sanchez2019]
- H3K9me2/3: Enhanced repressive marks in ALS [@kelley2019a]
Cross-talk
- H3K4me3 and H3K27me3 modifications show complex interactions [@bernstein2006]
- Bivalent domains in stem cells are re-established in disease [@ebert2019]
Histone Modifications in ALS Genes
| Gene | Histone Modification | Effect |
|------|---------------------|--------|
| SOD1 | H3K9ac ↑ | Increased expression |
| C9orf72 | H3K27me3 ↓ | Bidirectional effects |
| FUS | H3K4me3 altered | RNA processing changes |
| TARDBP | H3K9ac ↓ | Auto-regulation affected |
HDAC Inhibitors in ALS Therapy
| Compound | Class | Status | Mechanism |
|----------|-------|--------|-----------|
| Valproic acid | Class I | Preclinical | Broad HDAC inhibition |
| SAHA (Vorinostat) | Class I/II | Preclinical | Pan-HDAC inhibitor |
| MS-275 (Entinostat) | Class I | Phase I/II | HDAC1/2/3 selective |
| Trichostatin A | Class I/II | Preclinical | Potent HDAC inhibitor |
| Ricolinostat | HDAC6 | Phase I/II | Selective HDAC6 inhibition |
Sirtuins in ALS
The [NAD+-dependent deacetylases](/proteins/sirt1-protein) (SIRT1-7):
- SIRT1: Generally neuroprotective; expression changes in ALS [@valletamayo2019]
- SIRT2: Modulates oxidative stress [@chen2019b]
- SIRT3: Mitochondrial function regulation [@liu2019a]
- NAD+ precursors are being investigated clinically [@de2019]
Non-Coding RNAs in ALS
Non-coding RNAs, particularly microRNAs, are significantly dysregulated in ALS and contribute to disease pathogenesis.
MicroRNAs in ALS
Motor Neuron-Enriched miRNAs
- miR-9: Critical for motor neuron development; dysregulated in ALS [@chang2014]
- Targets: BDNF, REST
- Functions: Neurodevelopment, stress response [@liu2019b]
- miR-124: Neuronal identity maintenance [@pincetty2019]
- Alters in ALS [@aguirre2019]
- Therapeutic potential [@davila2019]
- miR-23a: Regulates ALS-related genes [@li2019]
ALS-Associated miRNAs
| miRNA | Expression | Target Genes | Function |
|-------|------------|--------------|----------|
| miR-155 | ↑ | SOCS1, MCPIP1 | Inflammation |
| miR-146a | ↑ | TRAF6, IRAK1 | Immune response |
| miR-131 | ↑ | — | Synaptic function |
| miR-219 | ↓ | Lipid metabolism | oligodendrocyte |
| miR-219 | ↓ | DAPK1, ULK1 | Autophagy |
miRNA Dysregulation by Mutation
- SOD1 mutations: miR-155, miR-146a upregulation [@koval2013]
- C9orf72: miRNA processing alterations [@mori2019]
- FUS mutations: Direct miRNA dysregulation [@ho2019]
CSF and Blood miRNAs as Biomarkers
- miR-181a-5p: Promising ALS biomarker [@weydt2016]
- miR-124-3p: Detectable in CSF [@benigni2019]
- Panel approaches: Multiple miRNAs improve specificity [@liguori2018]
Long Non-Coding RNAs (lncRNAs)
- NEAT1: Nuclear paraspeckle formation; altered in ALS [@shan2019]
- MALAT1: Synaptic function; affected in disease [@ma2019]
- HOTAIR: Gene silencing complex; motor neuron expression [@guo2019]
- ALSINC: ALS-specific lncRNA [@aronica2019]
- SOX2OT: Motor neuron development [@zhang2019a]
Circular RNAs (circRNAs)
- circSMARCA5: Reduced in ALS [@knupp2019]
- circCFL1: Promotes neurodegeneration [@wang2019]
- circRNA sponges: miRNA sequestration effects [@liu2019c]
Small Nucleolar RNAs (snoRNAs)
- SNORD115/116: Imprinted locus; altered in ALS [@sinha2019]
- snoRNA-derived RNAs (sdRNAs): Emerging role [@mehler2019]
Chromatin Remodeling in ALS
Chromatin remodeling complexes regulate access to DNA and are affected in ALS through multiple mechanisms.
SWI/SNF Complex Dysregulation
The SWI/SNF (SWItch/Sucrose Non-Fermentable) ATP-dependent chromatin remodelers:
- BRG1 (SMARCA4): Expression changes in ALS [@kelley2019b]
- BRM (SMARCA2): Altered activity [@matsumoto2019]
- BAF subunits: Mutations in some ALS cases [@weder2019]
- Target genes: SOD1, FUS, TDP-43 regulators [@zhang2019b]
NuRD Complex
The Nucleosome Remodeling Deacetylase (NuRD) complex:
- CHD4: Elevated in ALS motor neurons [@roh2019]
- MTA1/2/3: Expression changes [@sen2019]
- Functions:
- Transcriptional repression
- DNA repair
- Response to oxidative stress [@millard2019]
ISWI Complex
- SMARCA5: Reduced in ALS [@ahmad2019]
- Impaired nucleosome spacing affects gene expression [@lorch2019]
CHD Family
- CHD7: Mutations linked to ALS [@bowers2019]
- CHD1/2: Open chromatin regulation [@park2019]
Chromatin Remodeling and ALS Genes
| Complex | Subunit | Role in ALS |
|---------|---------|-------------|
| SWI/SNF | SMARCA4 | Gene activation |
| NuRD | CHD4 | Repression |
| ISWI | SMARCA5 | Nucleosome spacing |
| CHD | CHD1/2/7 | Chromatin structure |
Epigenetic Therapy Targeting Chromatin Remodeling
- Small molecule modulators: Under development [@hohmann2019]
- BET inhibitors: Bromodomain targeting [@belkina2019]
- Chromatin assembly factors: Therapeutic potential [@liu2019d]
RNA Metabolism and Epigenetics
The intimate connection between RNA metabolism and epigenetics is particularly relevant in ALS.
TDP-43 and Epigenetics
- TDP-43 binds to DNA and RNA [@ratti2019]
- Chromatin regulation by TDP-43 [@sephton2019]
- HDAC6 and TDP-43 clearance [@xia2019]
FUS and Epigenetic Regulators
- [FUS](/genes/fus) protein interacts with:
- Histone modifiers [@bertolin2019]
- Chromatin remodelers [@dambrogio2019]
- Transcription factors [@kapeli2019]
RNA Methylation
- N6-methyladenosine (m6A): RNA modification dysregulated in ALS [@donello2019]
- m6A writers: METTL3/14 expression changes [@wong2019]
- m6A readers: YTHDF2 alterations [@zhang2019c]
Neuroinflammation and Epigenetics
Epigenetic regulation of neuroinflammation in ALS:
- Microglial activation: HDAC-dependent [@ponomarev2019]
- [NF-κB](/entities/nf-kb) pathway: Epigenetic control [@liu2019e]
- [TREM2](/proteins/trem2): Epigenetic regulation in [microglia](/cell-types/microglia-neuroinflammation) [@yeh2019]
Metabolic Epigenetics
Metabolic dysfunction in ALS:
- AMPK: Epigenetic regulation [@rong2019]
- Sirtuins: Metabolic sensors [@song2019]
- NAD+ metabolism: Therapeutic target [@yoshino2019]
Therapeutic Approaches
Clinical Trials
| Agent | Target | Phase | Status |
|-------|--------|-------|--------|
| Valproic acid | HDACs | Phase I/II | Completed |
| Ricolinostat | HDAC6 | Phase I/II | Recruiting |
| ASO (tofersen) | SOD1 | Approved | Completed |
| ASO (C9orf72) | C9orf72 | Phase I/II | Ongoing |
Emerging Strategies
- Epigenetic editing: CRISPR-dCas9 fusions [@choudhury2019]
- Combination therapy: HDAC + ASO [@kelley2019c]
- Repurposing: Existing epigenetic drugs [@lattante2019]
Biomarkers
DNA Methylation Biomarkers
- Peripheral blood patterns: Diagnostic potential [@kadhim2019a]
- Disease progression markers: Longitudinal changes [@miller2019]
miRNA Biomarkers
| miRNA | Sample | Use |
|-------|--------|-----|
| miR-181a-5p | CSF | Diagnostic |
| miR-124-3p | CSF | Diagnostic |
| miR-155 | Blood | Progression |
| miR-146a | Blood | Inflammatory |
See Also
- [DNA Methylation in Neurodegeneration](/mechanisms/dna-methylation-neurodegeneration)
- [Histone Modification Pathways in Neurodegeneration](/mechanisms/histone-modification-pathway-neurodegeneration)
- [Non-coding RNAs in Neurodegeneration](/mechanisms/non-coding-rna-neurodegeneration)
- [Chromatin Remodeling in Neurodegeneration](/mechanisms/chromatin-remodeling-neurodegeneration)
- [Epigenetics in Alzheimer's Disease](/mechanisms/epigenetics-ad)
- [Epigenetics in Parkinson's Disease](/mechanisms/epigenetics-parkinsons)
- [Epigenetic Therapies for Neurodegeneration](/therapeutics/epigenetic-therapies-neurodegeneration)
- [SOD1 Pathway in ALS](/mechanisms/als-sod1-pathway)
- [C9orf72 Hexanucleotide Repeat Expansion](/mechanisms/c9orf72-expansion)
- [TDP-43 Proteinopathy in ALS](/mechanisms/als-tdp43-pathology)
- [ALS Therapeutic Approaches](/therapeutics/als-therapeutics)
Confidence Assessment
- Evidence quality: High (extensive human post-mortem studies, iPSC models, and clinical data)
- Therapeutic translatability: High (multiple clinical trials ongoing)
- Biarker potential: Moderate to High (several candidates under validation)
References
Pathway Diagram
The following diagram shows key molecular relationships for Epigenetics in Amyotrophic Lateral Sclerosis based on knowledge graph edges:
Related Hypotheses
From the [SciDEX Exchange](/exchange) — scored by multi-agent debate
- [Stress Granule Phase Separation Modulators](/hypothesis/h-97aa8486) — <span style="color:#81c784;font-weight:600">0.71</span> · Target: G3BP1
- [Heat Shock Protein 70 Disaggregase Amplification](/hypothesis/h-5dbfd3aa) — <span style="color:#81c784;font-weight:600">0.71</span> · Target: HSPA1A
- [PARP1 Inhibition Therapy](/hypothesis/h-69919c49) — <span style="color:#81c784;font-weight:600">0.67</span> · Target: PARP1
- [Cryptic Exon Silencing Restoration](/hypothesis/h-4fabd9ce) — <span style="color:#81c784;font-weight:600">0.66</span> · Target: TARDBP
- [Arginine Methylation Enhancement Therapy](/hypothesis/h-19003961) — <span style="color:#81c784;font-weight:600">0.65</span> · Target: PRMT1
- [Cross-Seeding Prevention Strategy](/hypothesis/h-eea667a9) — <span style="color:#81c784;font-weight:600">0.65</span> · Target: TARDBP
- [RNA Granule Nucleation Site Modulation](/hypothesis/h-fffd1a74) — <span style="color:#81c784;font-weight:600">0.64</span> · Target: G3BP1
- [Axonal RNA Transport Reconstitution](/hypothesis/h-8196b893) — <span style="color:#81c784;font-weight:600">0.63</span> · Target: HNRNPA2B1
Related Analyses:
- [TDP-43 phase separation therapeutics for ALS-FTD](/analysis/SDA-2026-04-01-gap-006) 🔄
- [RNA binding protein dysregulation across ALS FTD and AD](/analysis/SDA-2026-04-01-gap-v2-68d9c9c1) 🔄
Pathway Diagram
The following diagram shows the key molecular relationships involving Epigenetics in Amyotrophic Lateral Sclerosis discovered through SciDEX knowledge graph analysis:
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