Pathogenic Proteins TDP-43, SOD1, FUS, and C9orf72 DPRs Drive ALS Pathogenesis via Converging Mechanisms
Background
Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease characterized by progressive motor neuron degeneration, leading to muscle weakness and paralysis. Current treatments like riluzole and edaravone offer limited symptomatic relief or target specific mutations, failing to halt disease progression for most patients. A central pathological hallmark in ALS is the aggregation of specific proteins, which disrupts vital cellular processes and contributes to neuronal death. Understanding these proteinopathies and their converging mechanisms is crucial for developing effective disease-modifying therapies.
Study Design
This comprehensive review synthesizes current understanding of the molecular mechanisms by which key pathogenic proteins drive Amyotrophic Lateral Sclerosis (ALS) progression. It systematically examines the roles of TDP-43, SOD1, FUS, and C9orf72 dipeptide repeat proteins (DPRs), detailing their contributions to protein aggregation, RNA processing disruption, and cellular stress responses. The review also explores the propagation of these proteins between neurons and glia, and discusses emerging translational therapeutic strategies focused on inhibiting aggregation or enhancing clearance.
Results
The review identifies TDP-43 proteinopathy as a central hallmark in nearly all ALS cases, involving cytoplasmic mislocalization, misfolding, and aggregation that disrupt RNA processing, protein transport, and DNA repair. Similarly, mutations in SOD1 and FUS are shown to promote toxic protein aggregation, leading to impaired cellular homeostasis and neuronal dysfunction. C9orf72-derived DPRs exert toxicity by interfering with nucleocytoplasmic transport. > The propagation of these pathogenic proteins between neurons and glia, often via prion-like mechanisms, is highlighted as a key driver of ALS pathology spread. Cellular protective responses, such as molecular chaperones and the ubiquitin-proteasome system, are often overwhelmed. Furthermore, mitochondrial dysfunction, oxidative stress, and disturbances in calcium homeostasis are implicated, with SOD1 mutations specifically altering redox balance. Impaired DNA repair mechanisms, involving proteins like NEK1 and VCP, link protein aggregation to genomic instability.
Key Findings
- TDP-43 proteinopathy, involving mislocalization and aggregation, disrupts
RNA processing,protein transport, andDNA repairin nearly all ALS cases. - Mutations in SOD1 and FUS promote toxic protein aggregation, impairing cellular homeostasis and neuronal function.
- C9orf72-derived dipeptide repeat proteins (DPRs) interfere with
nucleocytoplasmic transport, contributing to toxicity. - Pathogenic proteins propagate between neurons and glia via prion-like mechanisms, driving the spread of ALS pathology.
- Converging mechanisms include
mitochondrial dysfunction,oxidative stress, and impairedDNA repair, overwhelming cellular protective responses.
Why It Matters
This review consolidates the complex interplay of pathogenic proteins in ALS, providing a clearer roadmap for therapeutic development. Understanding the shared and distinct mechanisms of TDP-43, SOD1, FUS, and C9orf72 DPRs is critical for designing targeted interventions. The insights into protein propagation and cellular stress responses suggest that multi-modal strategies, potentially combining small molecules, peptides, or antisense oligonucleotides to inhibit aggregation or enhance clearance, hold promise. This work underscores the need for therapies that address the fundamental proteinopathy, moving beyond symptomatic treatment towards disease modification, though specific protocols remain in preclinical stages.
als
neurodegeneration
protein-aggregation
tdp-43
sod1
fus