Sterol metabolism differentially contributes to maintenance and exit of quiescenceShow others and affiliations
2022 (English)In: Frontiers in Cell and Developmental Biology, E-ISSN 2296-634X, Vol. 10, article id 788472Article in journal (Refereed) Published
Abstract [en]
Nutrient starvation initiates cell cycle exit and entry into quiescence, a reversible, non-proliferative state characterized by stress tolerance, longevity and large-scale remodeling of subcellular structures. Depending on the nature of the depleted nutrient, yeast cells are assumed to enter heterogeneous quiescent states with unique but mostly unexplored characteristics. Here, we show that storage and consumption of neutral lipids in lipid droplets (LDs) differentially impacts the regulation of quiescence driven by glucose or phosphate starvation. Upon prolonged glucose exhaustion, LDs were degraded in the vacuole via Atg1-dependent lipophagy. In contrast, yeast cells entering quiescence due to phosphate exhaustion massively over-accumulated LDs that clustered at the vacuolar surface but were not engulfed via lipophagy. Excessive LD biogenesis required contact formation between the endoplasmic reticulum and the vacuole at nucleus-vacuole junctions and was accompanied by a shift of the cellular lipid profile from membrane towards storage lipids, driven by a transcriptional upregulation of enzymes generating neutral lipids, in particular sterol esters. Importantly, sterol ester biogenesis was critical for long-term survival of phosphate-exhausted cells and supported rapid quiescence exit upon nutrient replenishment, but was dispensable for survival and regrowth of glucose-exhausted cells. Instead, these cells relied on de novo synthesis of sterols and fatty acids for quiescence exit and regrowth. Phosphate-exhausted cells efficiently mobilized storage lipids to support several rounds of cell division even in presence of inhibitors of fatty acid and sterol biosynthesis. In sum, our results show that neutral lipid biosynthesis and mobilization to support quiescence maintenance and exit is tailored to the respective nutrient scarcity.
Place, publisher, year, edition, pages
Frontiers Media S.A., 2022. Vol. 10, article id 788472
Keywords [en]
lipid droplets, membrane contact sites, NVJ, yeast, quiescence, lipophagy, sterol ester, sterols
National Category
Biochemistry Molecular Biology
Identifiers
URN: urn:nbn:se:umu:diva-215006DOI: 10.3389/fcell.2022.788472ISI: 000761993600001PubMedID: 35237594Scopus ID: 2-s2.0-85125340822OAI: oai:DiVA.org:umu-215006DiVA, id: diva2:1802781
Funder
Swedish Research Council, 2015-05468Knut and Alice Wallenberg Foundation, 2017.009Olle Engkvists stiftelse, 194-0681German Research Foundation (DFG), 390939984Olle Engkvists stiftelse, 207-0527German Research Foundation (DFG), 403222702German Research Foundation (DFG), 423813989Swedish Research Council, 2019-052492023-10-052023-10-052025-02-20Bibliographically approved