eLife (Feb 2014)

Arf1/COPI machinery acts directly on lipid droplets and enables their connection to the ER for protein targeting

  • Florian Wilfling,
  • Abdou Rachid Thiam,
  • Maria-Jesus Olarte,
  • Jing Wang,
  • Rainer Beck,
  • Travis J Gould,
  • Edward S Allgeyer,
  • Frederic Pincet,
  • Jörg Bewersdorf,
  • Robert V Farese Jr,
  • Tobias C Walther

DOI
https://doi.org/10.7554/eLife.01607
Journal volume & issue
Vol. 3

Abstract

Read online

Lipid droplets (LDs) are ubiquitous organelles that store neutral lipids, such as triacylglycerol (TG), as reservoirs of metabolic energy and membrane precursors. The Arf1/COPI protein machinery, known for its role in vesicle trafficking, regulates LD morphology, targeting of specific proteins to LDs and lipolysis through unclear mechanisms. Recent evidence shows that Arf1/COPI can bud nano-LDs (∼60 nm diameter) from phospholipid-covered oil/water interfaces in vitro. We show that Arf1/COPI proteins localize to cellular LDs, are sufficient to bud nano-LDs from cellular LDs, and are required for targeting specific TG-synthesis enzymes to LD surfaces. Cells lacking Arf1/COPI function have increased amounts of phospholipids on LDs, resulting in decreased LD surface tension and impairment to form bridges to the ER. Our findings uncover a function for Arf1/COPI proteins at LDs and suggest a model in which Arf1/COPI machinery acts to control ER-LD connections for localization of key enzymes of TG storage and catabolism.

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