VPS41 recruits biosynthetic LAMP-positive vesicles through interaction with Arl8b

Area of Science:

• Cell Biology
• Molecular Biology
• Organelle Trafficking

Background:

• Vacuolar protein sorting 41 (VPS41) is a key component of the homotypic fusion and protein sorting (HOPS) complex, crucial for lysosomal fusion.
• VPS41 mediates lysosomal membrane protein (LAMP) trafficking from the trans-Golgi network (TGN) to endo/lysosomes via specific carriers.
• The precise molecular mechanisms of VPS41 in this trafficking pathway are not fully elucidated.

Purpose of the Study:

• To investigate the role of ectopically localized VPS41 on mitochondria in regulating LAMP distribution.
• To identify molecular factors involved in LAMP carrier trafficking mediated by VPS41.
• To explore VPS41-Arl8b interactions in the context of lysosomal trafficking.

Main Methods:

• Electron microscopy was employed to visualize LAMP carriers associated with mitochondria.
• The Retention Using Selective Hooks (RUSH) system was utilized to track newly synthesized LAMPs.
• Co-immunoprecipitation and domain-binding assays were performed to study protein interactions.

Main Results:

• Mitochondrial-localized VPS41 recruited vesicles positive for LAMP1 and LAMP2A, resembling canonical LAMP carriers.
• Newly synthesized LAMPs were specifically recruited by mitochondrial VPS41, a function unique to VPS41 among HOPS subunits.
• The small GTPase Arl8b was identified as essential for LAMP carrier trafficking, binding to the VPS41 WD40 domain.

Conclusions:

• VPS41 plays a novel role in recruiting TGN-derived LAMP carriers to mitochondria.
• The interaction between VPS41 and Arl8b is critical for LAMP carrier trafficking.
• These findings expand the known functions of VPS41 and Arl8b beyond endosome-lysosome fusion, offering new insights into lysosomal trafficking.