Single Acetylation-mimetic Mutation in TDP-43 Nuclear Localization Signal Disrupts Importin α1/β Signaling.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Cytoplasmic aggregation of TAR-DNA binding protein of 43 kDa (TDP-43) is a defining characteristic of sporadic amyotrophic lateral sclerosis (ALS).
• Most ALS cases involve aberrant post-translational modifications of TDP-43 rather than direct gene mutations.

Purpose of the Study:

• To investigate how post-translational modifications, specifically acetylation, near the Nuclear Localization Signal (NLS) of TDP-43 contribute to its cytoplasmic mislocalization and aggregation.
• To explore the molecular mechanisms linking TDP-43 modification to neurodegeneration in sporadic ALS.

Main Methods:

• Utilized an acetylation-mimetic mutation (K82Q) in TDP-43 to simulate post-translational modification.
• Assessed TDP-43 localization and aggregation in cellular models.
• Investigated the interaction between modified TDP-43 and importin proteins (importin α1/β).

Main Results:

• A single acetylation-mimetic mutation (K82Q) near the minor NLS of TDP-43 induced cytoplasmic mislocalization and irreversible aggregation.
• The K82Q mutation disrupted the binding of TDP-43 to importins, inhibiting nuclear import.
• This disruption prevented the anti-aggregation activity of importin α1/β.

Conclusions:

• Perturbations near the TDP-43 NLS, such as acetylation, represent a novel mechanism contributing to TDP-43 aggregation in sporadic ALS.
• Understanding these mechanisms is crucial for deciphering the molecular etiology of sporadic ALS and developing therapeutic strategies.