ADAR2-Mediated RNA Editing Promotes TDP-43 Nuclear Export and Alters RNA Binding.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• TDP-43 nuclear loss is a hallmark of ALS and FTD.
• Mechanisms driving TDP-43 mislocalization are poorly understood.
• Altered ADAR2 in ALS/FTD tissues prompted investigation into RNA editing's role.

Purpose of the Study:

• Investigate if dysregulated RNA editing contributes to TDP-43 mislocalization.
• Determine the impact of ADAR2 activity on TDP-43 nucleocytoplasmic trafficking.
• Explore the relationship between RNA editing and TDP-43-RNA interactions.

Main Methods:

• Co-overexpression of ADAR2 and TDP-43 in cell lines and Drosophila models.
• Interspecies heterokaryon and HeLa cell assays for TDP-43 localization.
• Electrophoretic mobility shift assays (EMSAs) for TDP-43 RNA binding.
• RNA immunoprecipitation followed by sequencing (RIP-seq) and eCLIP-seq to analyze RNA interactions and expression.

Main Results:

• ADAR2 overexpression reduced TDP-43's nuclear ratio, dependent on ADAR2 activity and TDP-43 binding.
• TDP-43 preferentially bound to inosine-containing (edited) RNAs.
• RNA editing altered gene expression and TDP-43 binding profiles.

Conclusions:

• A-to-I RNA editing regulates TDP-43 localization and RNA interactions.
• Altered RNA editing promotes TDP-43 nuclear export, potentially contributing to TDP-43 proteinopathies.
• RNA editing dysregulation is a novel factor in early pathogenic mechanisms of neurodegeneration.