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Updated: Mar 31, 2026
10:23
Lipid Droplet Isolation for Quantitative Mass Spectrometry Analysis
Published on: April 17, 2017
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CARTS biogenesis requires VAP-lipid transfer protein complexes functioning at the endoplasmic reticulum-Golgi
Yuichi Wakana1, Richika Kotake1, Nanako Oyama1
1School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
Molecular Biology of the Cell
|October 23, 2015
Summary
Vesicle-associated membrane protein-associated protein (VAP) is crucial for lipid transfer and the formation of transport carriers from the Golgi. VAP depletion impairs lipid levels and carrier biogenesis, highlighting the role of ER-Golgi contacts.
Area of Science:
- Cell Biology
- Membrane Trafficking
- Lipid Metabolism
Background:
- Vesicle-associated membrane protein-associated protein (VAP) is an ER-resident protein involved in lipid transfer.
- VAP interacts with OSBP and CERT to mediate ceramide and cholesterol transport.
- VAP is implicated in the secretion of pancreatic adenocarcinoma up-regulated factor (UPF).
Purpose of the Study:
- To investigate the role of VAP and ER-Golgi contacts in UPF secretion and transport carrier formation.
- To elucidate the mechanism by which VAP regulates lipid levels at the trans-Golgi network (TGN).
- To determine the importance of ER-Golgi membrane apposition dynamics in CARTS biogenesis.
Main Methods:
- VAP depletion using siRNA.
- Analysis of diacylglycerol levels at the TGN.
- Assessment of CARTS formation and UPF secretion.
- Immunofluorescence microscopy to visualize ER-Golgi contacts and protein localization.
Main Results:
- VAP depletion decreased diacylglycerol levels at the TGN and impaired CARTS formation.
- VAP forms complexes with OSBP and Sac1 at ER subdomains apposed to the TGN.
- Immobilization of ER-Golgi contacts significantly reduced CARTS production.
Conclusions:
- ER-Golgi contacts are essential for regulating lipid metabolism and controlling the biogenesis of transport carriers from the TGN.
- VAP plays a critical role in establishing and maintaining these functional ER-Golgi membrane contact sites.
- The dynamic association and dissociation of ER-Golgi membranes are vital for CARTS production and UPF secretion.
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