Arf1 directly recruits the Pik1-Frq1 PI4K complex to regulate the final stages of Golgi maturation

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Golgi complex function relies on Arf1 GTPase and phosphatidylinositol 4-phosphate (PI4P).
• The precise roles of PI4P in Golgi vesicle formation are not fully understood.
• Arf1's regulation of PI4P production is known, but its direct interaction with PI4-kinases is unestablished.

Purpose of the Study:

• To investigate the direct relationship between Arf1 and PI4P production at the Golgi.
• To elucidate the role of PI4P in Arf1-mediated vesicle formation.
• To establish the regulatory and temporal context of PI4P in Golgi maturation.

Main Methods:

• Live-cell time-lapse imaging analyses.
• Acute PI4P depletion experiments.
• In vitro protein-protein interaction assays on Golgi-mimetic membranes.

Main Results:

• Arf1 directly recruits the Pik1-Frq1 PI4-kinase complex to the Golgi.
• This recruitment tightly controls PI4P production, initiating late Golgi maturation stages.
• Generated PI4P acts as a critical signal for AP-1 and secretory vesicle formation.

Conclusions:

• Arf1 directly regulates Golgi PI4P production via Pik1-Frq1 recruitment.
• PI4P is essential for AP-1 and secretory vesicle biogenesis during Golgi maturation.
• This study clarifies the mechanism linking Arf1 activity to PI4P-dependent Golgi events.