Protease-Mediated TAR DNA-Binding Protein 43 (TDP-43) Pathogenesis: From Molecular Mechanisms to Therapeutic...

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• TDP-43 proteinopathy defines ~50% of frontotemporal lobar degeneration (FTLD) cases.
• The transition from nuclear proteostasis to cytoplasmic toxicity is a critical knowledge gap.
• TDP-43's role in repressing cryptic exons is established, but its pathological mechanisms require further elucidation.

Purpose of the Study:

• To explore the synergy between site-specific proteolysis and PTM-induced phase transitions in TDP-43 toxicity.
• To propose a mechanism for TDP-43's transition from nuclear to cytoplasmic toxicity.
• To highlight therapeutic drug discovery strategies targeting TDP-43.

Main Methods:

• Review of existing literature on TDP-43 proteolysis and post-translational modifications.
• Analysis of proposed mechanisms involving endoproteolytic cleavage and subsequent PTMs.
• Discussion of potential therapeutic interventions targeting TDP-43.

Main Results:

• Primary endoproteolytic cleavage by specific proteases acts as a "protease switch".
• Cleavage generates C-terminal TDP-43 fragments that disrupt nuclear import.
• Hyperphosphorylation and SUMOylation of these fragments drive transcriptome shutdown.
• Small-molecule interventions can reduce aberrant fragmentation and delocalization.

Conclusions:

• A proposed mechanism links protease cleavage and PTMs to TDP-43-mediated toxicity.
• Targeting TDP-43 at the preaggregation stage offers disease-modifying therapeutic potential.
• Interception strategies may restore TDP-43 function and mitigate FTLD progression.