Proximity labeling reveals dynamic changes in the SQSTM1 protein network

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Sequestosome1 (SQSTM1) is a crucial autophagy receptor involved in degrading intracellular components.
• Its function relies on a complex protein interaction network mediated by specific domains (LIR, PB1, UBA, KIR).
• Understanding the SQSTM1 network is vital for comprehending cellular physiology and disease pathogenesis.

Purpose of the Study:

• To investigate the SQSTM1 protein interaction network using proximity labeling.
• To identify novel SQSTM1 interactors and understand how aggregated tau protein influences this network.
• To elucidate the role of SQSTM1 domains (PB1, UBA) in binding network members and tau.

Main Methods:

• Proximity-dependent biotinylation using a TurboID::SQSTM1 fusion protein.
• Characterization of the chimeric protein's cellular localization and interaction capabilities.
• Analysis of SQSTM1 interactome changes in the presence of aggregated tau.

Main Results:

• The TurboID::SQSTM1 chimera successfully recapitulated known SQSTM1 functions and identified novel interactors.
• Aggregated tau protein significantly altered the SQSTM1 network, incorporating stress-associated proteins.
• The PB1 and UBA domains of SQSTM1 were confirmed as critical for binding network members, including tau's K18 domain.

Conclusions:

• This study provides a dynamic view of the SQSTM1 protein network.
• The findings reveal tau's impact on the SQSTM1 interactome, implicating stress responses.
• The research offers a valuable resource for studying SQSTM1 in health and disease contexts.