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Dev Cell. 2015 Dec 7;35(5):584-599. doi: 10.1016/j.devcel.2015.11.010.

Role for Lipid Droplet Biogenesis and Microlipophagy in Adaptation to Lipid Imbalance in Yeast.

Author information

1
Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, 630 West 168(th) Street, New York, NY 10032, USA.
2
Integrated Imaging Center, Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
3
Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, 630 West 168(th) Street, New York, NY 10032, USA. Electronic address: lap5@cumc.columbia.edu.

Abstract

The immediate responses to inhibition of phosphatidylcholine (PC) biosynthesis in yeast are altered phospholipid levels, slow growth, and defects in the morphology and localization of ER and mitochondria. With chronic lipid imbalance, yeast adapt. Lipid droplet (LD) biogenesis and conversion of phospholipids to triacylglycerol are required for restoring some phospholipids to near-wild-type levels. We confirmed that the unfolded protein response is activated by this lipid stress and find that Hsp104p is recruited to ER aggregates. We also find that LDs form at ER aggregates, contain polyubiquitinated proteins and an ER chaperone, and are degraded in the vacuole by a process resembling microautophagy. This process, microlipophagy, is required for restoration of organelle morphology and cell growth during adaptation to lipid stress. Microlipophagy does not require ATG7 but does requires ESCRT components and a newly identified class E VPS protein that localizes to ER and is upregulated by lipid imbalance.

PMID:
26651293
PMCID:
PMC4679156
DOI:
10.1016/j.devcel.2015.11.010
[Indexed for MEDLINE]
Free PMC Article

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