Specific RNA interactions promote TDP-43 multivalent phase separation and maintain liquid properties.

Area of Science:

• Molecular Biology
• Neuroscience
• Biochemistry

Background:

• TDP-43 is an RNA-binding protein involved in gene expression.
• TDP-43 dysfunction and loss of homeostasis are linked to neurodegenerative diseases, including ALS and frontotemporal dementia.
• Alterations in TDP-43 liquid-liquid phase separation (LLPS) properties may contribute to protein aggregation.

Purpose of the Study:

• To investigate the mechanisms regulating TDP-43 LLPS.
• To clarify how TDP-43's association with specific RNA targets influences its condensation.
• To determine the role of RNA binding in maintaining TDP-43 protein solubility and liquid-like condensate properties.

Main Methods:

• In vitro studies demonstrating RNA binding-induced TDP-43 LLPS.
• Analysis of sequence-specific RNA interactions and multivalent interactions involving TDP-43 domains.
• Experiments in mammalian cellular lysates to assess physiological relevance.
• Investigation of TDP-43-RNA association effects on condensate properties, particularly in the presence of ALS-linked mutations.

Main Results:

• RNA binding strongly promotes TDP-43 LLPS via sequence-specific interactions.
• TDP-43 condensation is enhanced by the number of adjacent binding sites and multivalent domain interactions.
• RNA-driven TDP-43 condensation was observed in mammalian cellular lysates.
• TDP-43-RNA association preserves the liquid-like properties of condensates, which are compromised by ALS-linked mutations.

Conclusions:

• RNA binding is a key regulator of TDP-43 condensation, promoting LLPS and maintaining protein solubility.
• Defects in RNA-mediated TDP-43 condensation may be a significant factor in the pathogenesis of TDP-43-associated neurodegenerative diseases.
• Understanding RNA's role in TDP-43 LLPS offers insights into potential therapeutic strategies for ALS and related disorders.