FUS ALS-causative mutations impair FUS autoregulation and splicing factor networks through intron retention

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Mutations in the RNA-binding protein FUS are a known cause of amyotrophic lateral sclerosis (ALS).
• FUS is involved in RNA metabolism, including mRNA splicing, but the precise effects of ALS-linked mutations on splicing remain unclear.
• Previous disease models often involved FUS overexpression, complicating the analysis of mutation-specific effects due to FUS autoregulation.

Purpose of the Study:

• To investigate the impact of FUS mutations on RNA splicing and gene expression using accurate disease models.
• To differentiate mutation-induced changes from genuine loss-of-function effects.
• To explore the role of FUS autoregulation in ALS pathogenesis and its alteration by mutations.

Main Methods:

• Generation of FUS knockin models to avoid overexpression artifacts.
• High-depth RNA sequencing of FUS mutants and FUS knockout samples.
• Comparative analysis of mutation-specific splicing changes versus loss-of-function.

Main Results:

• FUS-ALS mutations lead to a broad loss of function in gene expression and splicing.
• Mutant FUS directly affects intron retention in other RNA-binding proteins.
• A novel FUS autoregulation mechanism involving intron retention is identified and shown to be altered by FUS mutations.
• Similar splicing alterations are observed in other genetic forms of ALS (TDP-43, VCP, SOD1 mutations).

Conclusions:

• FUS-ALS mutations cause widespread dysregulation of RNA splicing and gene expression.
• Mutations alter a novel FUS autoregulatory mechanism, contributing to disease.
• Multiple ALS-associated genes function within a shared regulatory network, suggesting common pathogenic pathways.