A Rab1 interactome illuminates a dual role in autophagy and membrane trafficking

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• The small GTPase Rab1 is a conserved protein involved in ER-to-Golgi transport and autophagy.
• While Rab1 effectors are known, its precise orchestration of these distinct cellular processes is not fully understood.

Purpose of the Study:

• To identify novel Rab1 interactors using proximity biotinylation.
• To elucidate the broader role of Rab1 in selective autophagy and membrane trafficking.

Main Methods:

• Application of MitoID, a proximity-dependent biotinylation technique, to map Rab1A and Rab1B interactomes.
• In vitro validation of identified protein-protein interactions.
• In vivo assessment of Rab1's role in mitophagy.

Main Results:

• Identification of new Rab1 interactors, including known membrane traffic and autophagy proteins, and uncharacterized proteins.
• Discovery that Rab1 interacts with cargo receptors for selective autophagy, suggesting an expanded role in this process.
• Validation of Rab1 interaction with optineurin, crucial for mitophagy, and Rab1 interaction with FHIP2A, a dynein adaptor, in a membrane-dependent manner.

Conclusions:

• Rab1 has a more extensive role in selective autophagy than previously recognized.
• Rab1's interaction with dynein adaptors is critical for ER-Golgi intermediate compartment dynamics.
• Proximity biotinylation methods can uncover effectors missed by conventional approaches.