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 clearing intracellular cargo, including protein aggregates.
• Its function relies on a complex protein interaction network mediated by specific functional domains (LIR, PB1, UBA, KIR).
• Understanding the SQSTM1 network is vital for insights into cellular physiology and disease.

Purpose of the Study:

• To investigate the SQSTM1 protein interaction network using proximity labeling.
• To characterize the dynamic changes in the SQSTM1 network, particularly in the context of aggregated tau protein.
• To identify the roles of specific SQSTM1 domains in mediating these interactions.

Main Methods:

• Fusion of TurboID enzyme with human SQSTM1 to create a chimeric protein (TurboID::SQSTM1).
• Application of proximity profile labeling to map protein interactions.
• Analysis of SQSTM1 network alterations induced by aggregated tau protein.

Main Results:

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

Conclusions:

• The SQSTM1 protein network is dynamic and responsive to cellular conditions like the presence of aggregated tau.
• Proximity labeling with TurboID::SQSTM1 is an effective tool for exploring these dynamic interactions.
• This study provides a valuable resource for understanding SQSTM1's role in health and disease.