Conformational change of RNA-helicase DHX30 by ALS/FTD-linked FUS induces mitochondrial dysfunction and cytosolic...

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Mutations in the fused in sarcoma (FUS) gene are a known cause of amyotrophic lateral sclerosis (ALS).
• Mitochondrial dysfunction and stress granule formation are implicated in FUS proteinopathies, but the underlying molecular mechanisms are not fully understood.

Purpose of the Study:

• To investigate the role of DHX30, a mitochondrial RNA granule component, in the pathogenesis of FUS-related amyotrophic lateral sclerosis (ALS-FUS).
• To elucidate the molecular interactions between FUS and DHX30 and their impact on mitochondrial function and protein aggregation.

Main Methods:

• Immunohistochemistry and immunoelectron microscopy on spinal cord tissue from ALS-FUS patients.
• Subcellular fractionation using detergent-solubility and density-gradient ultracentrifugation.
• Analysis of protein conformation via disulfide bond formation assays.
• Blue-native gel electrophoresis to assess mitochondrial protein complex assembly.

Main Results:

• Mutant FUS, unlike wild-type FUS, causes mislocalization of DHX30 from mitochondria to the cytosol, promoting FUS aggregate and stress granule colocalization.
• ALS-FUS patient spinal cord samples show decreased mitochondrial DHX30 and colocalization of cytosolic FUS aggregates with stress granule markers.
• Mutant FUS induces aberrant disulfide formation in DHX30, impairing mitochondrial translation and leading to OXPHOS assembly defects.

Conclusions:

• DHX30 is a critical molecule in ALS-FUS pathogenesis, interacting with FUS and mediating mitochondrial dysfunction.
• Disulfide-mediated conformational changes in DHX30 are a key mechanism linking mutant FUS to mitochondrial impairment and cytosolic aggregation in ALS-FUS.