Local membrane source gathering by p62 body drives autophagosome formation

Area of Science:

• Cell Biology
• Molecular Biology
• Autophagy Research

Background:

• Autophagosomes are crucial for cellular waste removal via autophagy.
• The precise mechanisms of p62 body's role in autophagosome formation are not fully understood.
• p62 bodies are known to be phase-separated structures involved in autophagy.

Purpose of the Study:

• To elucidate the role of p62 body in spatial membrane gathering during autophagosome biogenesis.
• To investigate the molecular mechanisms underlying p62 body's function in autophagy.
• To establish a membrane-based working model for p62 body's multifaceted role.

Main Methods:

• Mass spectrometry-based proteomics to identify p62 body-associated proteins.
• Cellular experiments, including those in Atg2ab DKO cells, to observe vesicle dynamics.
• Biochemical reconstitution assays to validate interactions and functions.
• Lipidomic profiling to determine lipid content.
• In vitro kinase assays to assess kinase complex assembly and activity.

Main Results:

• Proteomics revealed significant enrichment of vesicle trafficking components within p62 bodies.
• ATG9 and ATG16L1-positive vesicles were observed to gather around p62 bodies.
• p62 body was found to regulate intracellular trafficking of ATG9 and ATG16L vesicles.
• Lipidomic analysis identified specific lipids associated with p62 bodies.
• p62 body serves as a platform for ULK1 complex assembly and PI3KC3-C1 activation, promoting PI3P generation.

Conclusions:

• p62 body utilizes a spatial membrane gathering mechanism to facilitate autophagosome formation.
• The study proposes a model where p62 body integrates membraneless condensates with membrane vesicles for autophagosome biogenesis.
• This work highlights the critical interplay between p62 body, vesicle trafficking, and kinase signaling in autophagy.