Subcellular localization and RNAs determine FUS architecture in different cellular compartments

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Mutations in the Fused in sarcoma (FUS) gene are implicated in familial amyotrophic lateral sclerosis (ALS).
• In healthy cells, FUS protein is primarily nuclear, while in ALS, mutant FUS aggregates in the cytoplasm.
• The precise role of nuclear FUS depletion versus cytoplasmic aggregation in motor neuron death remains unclear.

Purpose of the Study:

• To investigate the distinct structural patterns of nuclear and cytoplasmic FUS proteins.
• To determine the influence of subcellular localization and RNA binding on FUS protein oligomerization and inclusion formation.
• To elucidate the role of RNA interactions in FUS protein architecture and function in the context of ALS.

Main Methods:

• Confocal microscopy to visualize FUS protein localization and structure.
• Analysis of wild-type and mutant FUS protein behavior in different subcellular compartments.
• Investigating the impact of nuclear and cytoplasmic RNAs on FUS oligomerization and inclusion formation.

Main Results:

• Nuclear FUS forms granular oligomers, while cytoplasmic FUS forms non-oligomeric inclusions.
• These distinct patterns are determined by FUS's subcellular location, irrespective of its wild-type or mutant status.
• Both nuclear FUS oligomerization and cytoplasmic inclusion formation are critically dependent on RNA binding.

Conclusions:

• Subcellular localization dictates FUS protein's structural state (oligomeric vs. inclusion).
• RNA molecules interacting with FUS in the nucleus or cytoplasm are essential for its distinct structural properties.
• This suggests that localized RNA interactions play a key role in FUS protein function and its contribution to ALS pathogenesis.