Tau/DDX6 interaction increases microRNA activity.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Tauopathies, including Alzheimer's disease, involve abnormal Tau protein aggregation.
• Tau's known role as a microtubule-binding protein belies its broader cellular functions.
• Understanding Tau's diverse roles is crucial for deciphering tauopathy mechanisms.

Purpose of the Study:

• To identify novel Tau interaction partners and elucidate Tau's function in cellular processes.
• To investigate the interaction between Tau and DEAD box RNA helicase 6 (DDX6).
• To determine the impact of Tau and its mutations on microRNA (miRNA) activity.

Main Methods:

• Tandem-affinity purification coupled with mass spectrometry to identify Tau-interacting proteins.
• Assays to measure the effect of Tau on miRNA let-7a, miR-21, and miR-124 activity via DDX6.
• Analysis of Tau mutations (P301S, P301L) associated with frontotemporal dementia and parkinsonism.

Main Results:

• Tau was identified to interact with DDX6, an RNA helicase involved in miRNA pathways.
• Tau enhances the gene silencing activity of specific miRNAs (let-7a, miR-21, miR-124) through its interaction with DDX6.
• Pathogenic Tau mutations disrupt the Tau/DDX6 interaction and compromise let-7a-mediated gene silencing.

Conclusions:

• Tau plays a novel and significant role in regulating miRNA activity.
• The Tau/DDX6 interaction is critical for proper miRNA-dependent gene silencing.
• Disruption of this interaction by disease-associated Tau mutations contributes to tauopathy pathogenesis.