TDP-43 accelerates deadenylation of target mRNAs by recruiting Caf1 deadenylase

Area of Science:

• Molecular Biology
• Neuroscience

Background:

• TAR DNA-binding protein 43 (TDP-43) is implicated in neurodegenerative diseases like ALS and FTLD.
• TDP-43 loss-of-function mutations are linked to these conditions.
• TDP-43 regulates mRNA stability, particularly through its binding to 3' untranslated regions (UTRs).

Purpose of the Study:

• To investigate the mechanism by which TDP-43 promotes mRNA instability.
• To determine TDP-43's role in mRNA deadenylation and its interaction with deadenylase complexes.
• To explore the implications for neurodegenerative disease pathogenesis.

Main Methods:

• Investigated TDP-43's interaction with deadenylase components.
• Utilized mRNA tethering assays to assess TDP-43's effect on mRNA stability and deadenylation.
• Examined the impact of TDP-43 on endogenous Progranulin (GRN) mRNA poly(A) tail length.

Main Results:

• TDP-43 recruits the Caf1 deadenylase to target mRNAs, accelerating their deadenylation.
• Tethering TDP-43 to the 3' UTR of mRNA induced destabilization and accelerated deadenylation.
• This process was inhibited by a dominant-negative Caf1 mutant, confirming Caf1's role.
• TDP-43 physically interacts with Caf1.
• TDP-43 was shown to regulate the poly(A) tail length of endogenous GRN mRNA.

Conclusions:

• TDP-43 promotes mRNA deadenylation by recruiting Caf1.
• Dysregulation of TDP-43-mediated mRNA deadenylation may contribute to the pathogenesis of neurodegenerative diseases.
• These findings provide insights into the molecular mechanisms underlying ALS and FTLD.