Lipid droplet autophagy in the yeast Saccharomyces cerevisiae

Mol Biol Cell. 2014 Jan;25(2):290-301. doi: 10.1091/mbc.E13-08-0448. Epub 2013 Nov 20.

Abstract

Cytosolic lipid droplets (LDs) are ubiquitous organelles in prokaryotes and eukaryotes that play a key role in cellular and organismal lipid homeostasis. Triacylglycerols (TAGs) and steryl esters, which are stored in LDs, are typically mobilized in growing cells or upon hormonal stimulation by LD-associated lipases and steryl ester hydrolases. Here we show that in the yeast Saccharomyces cerevisiae, LDs can also be turned over in vacuoles/lysosomes by a process that morphologically resembles microautophagy. A distinct set of proteins involved in LD autophagy is identified, which includes the core autophagic machinery but not Atg11 or Atg20. Thus LD autophagy is distinct from endoplasmic reticulum-autophagy, pexophagy, or mitophagy, despite the close association between these organelles. Atg15 is responsible for TAG breakdown in vacuoles and is required to support growth when de novo fatty acid synthesis is compromised. Furthermore, none of the core autophagy proteins, including Atg1 and Atg8, is required for LD formation in yeast.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy / genetics*
  • Autophagy-Related Protein 8 Family
  • Autophagy-Related Proteins
  • Cholesterol Esters / metabolism
  • Inclusion Bodies / genetics
  • Inclusion Bodies / metabolism*
  • Lipid Metabolism / genetics*
  • Microtubule-Associated Proteins / metabolism
  • Protein Kinases / metabolism
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / metabolism
  • Triglycerides / metabolism
  • Vacuoles / genetics
  • Vacuoles / metabolism
  • Vesicular Transport Proteins / metabolism

Substances

  • ATG8 protein, S cerevisiae
  • Atg11 protein, S cerevisiae
  • Autophagy-Related Protein 8 Family
  • Autophagy-Related Proteins
  • Cholesterol Esters
  • Microtubule-Associated Proteins
  • Saccharomyces cerevisiae Proteins
  • Triglycerides
  • Vesicular Transport Proteins
  • Protein Kinases
  • ATG1 protein, S cerevisiae