New insights into the OSBP‒VAP cycle.

Area of Science:

• Cell Biology
• Membrane Trafficking
• Lipid Metabolism

Background:

• Vesicle-associated membrane protein-A (VAP-A) is a key endoplasmic reticulum (ER) receptor.
• VAP-A mediates membrane contact sites (MCSs) between the ER and other organelles.
• Oxysterol-binding protein (OSBP) is a lipid transfer protein that interacts with VAP-A.

Purpose of the Study:

• To review recent advancements in understanding the Oxysterol-binding protein (OSBP) cycle.
• To explore the role of VAP-A and OSBP in lipid exchange.
• To extend the OSBP lipid exchange model to various cellular contexts and conditions.

Main Methods:

• Literature review of recent studies on VAP-A and OSBP.
• Analysis of the molecular mechanisms of lipid transfer at ER-Golgi MCSs.
• Integration of findings into a broader model of cellular lipid homeostasis.

Main Results:

• Recent studies have elucidated the detailed mechanisms of the OSBP cycle.
• The VAP-A/OSBP interaction is critical for cholesterol and phosphoinositide PI(4)P counter-transport.
• The OSBP lipid exchange model is applicable to diverse cellular functions and diseases.

Conclusions:

• The VAP-A/OSBP axis is central to inter-organelle lipid transport and homeostasis.
• Understanding the OSBP cycle provides insights into cellular lipid metabolism.
• Dysregulation of this pathway may contribute to various physiological and pathological states.