Molecular dissection of sphingolipid and sterol homeostasis in yeast
Final Report Abstract
Sphingolipids and sterols are essential components of the plasma membranes of all eukaryotes. They play a crucial role in membrane integrity and function as signaling molecules to regulate multiple cellular processes. While both sphingolipids and sterols are most abundant in the plasma membrane, they are synthesized in the ER through multiple enzymatic reactions. The proper regulation of sphingolipid and sterol levels is critical for cells, yet how this balance is achieved remains largely unknown. To maintain sphingolipid and sterol homeostasis, cells must regulate multiple processes, including lipid biosynthesis, inter-organelle transport, recycling, and storage. This project aimed to understand these processes, focusing on sphingolipid biosynthesis in the endoplasmic reticulum, sphingolipid transport between the ER and the Golgi apparatus, and sphingolipid sorting in the endo-lysosomal pathway. We also investigated the links between sphingolipid and sterol biogenesis in the ER and employed systematic approaches to understand the sorting of lipid metabolic enzymes in the endo-lysosomal system. The results from this project can be categorized into four major areas: i) Structural and functional analysis of sphingolipid metabolic enzymes in the yeast endoplasmic reticulum, particularly serine palmitoyl-transferase and ceramide synthase. ii) Regulation of serine palmitoyl-transferase via the uptake of exogenous serine with subcellular resolution. iii) Characterization of ceramide transport between the endoplasmic reticulum and the Golgi apparatus. iv) Systematic analysis of lipids and lipid metabolic enzymes in the endo-lysosomal pathway, including the two yeast sterol transport proteins Npc2 and Ncr1. Together, these results have greatly enhanced our understanding of the co-regulation of sphingolipids and sterols in the model organism Saccharomyces cerevisiae. We discovered that the rate-limiting serine palmitoyl-transferase also binds to the yeast-specific ergosterol and forms a complex with the Sac1 phosphatase, a crucial enzyme in the forward transport of sterols between the ER and the Golgi apparatus. Additionally, we deciphered the different trafficking pathways that deliver lipid metabolic enzymes to the yeast vacuole and improved our understanding of the role of retrograde transport in these processes. In summary, this project lays the foundation for a better understanding of how cells coordinate sphingolipid and sterol levels to maintain cellular homeostasis and prevent catastrophic events that could lead to diseases.
Publications
-
A systematic approach to identify recycling endocytic cargo depending on the GARP complex. eLife, 8.
Eising, Sebastian; Thiele, Lisa & Fröhlich, Florian
-
Live imaging of intra-lysosome pH in cell lines and primary neuronal culture using a novel genetically encoded biosensor. Autophagy, 17(6), 1500-1518.
Ponsford, Amy H.; Ryan, Thomas A.; Raimondi, Andrea; Cocucci, Emanuele; Wycislo, Susanne A.; Fröhlich, Florian; Swan, Laura E. & Stagi, Massimiliano
-
Phosphorylation of the GARP Subunit Vps53 by Snf1 Leads to the Formation of a Golgi – Mitochondria Contact Site (GoMiCS) in Yeast. Cold Spring Harbor Laboratory.
Wycislo, Susanne A.; Sundag, Celine; Walter, Stefan; Schuck, Sebastian & Fröhlich, Florian
-
The role of very long chain fatty acids in yeast physiology and human diseases. Biological Chemistry, 402(1), 25-38.
Erdbrügger, Pia & Fröhlich, Florian
-
Uptake of exogenous serine is important to maintain sphingolipid homeostasis in Saccharomyces cerevisiae. PLOS Genetics, 16(8), e1008745.
Esch, Bianca M.; Limar, Sergej; Bogdanowski, André; Gournas, Christos; More, Tushar; Sundag, Celine; Walter, Stefan; Heinisch, Jürgen J.; Ejsing, Christer S.; André, Bruno & Fröhlich, Florian
-
A lysosomal biogenesis map reveals the cargo spectrum of yeast vacuolar protein targeting pathways. Journal of Cell Biology, 221(4).
Eising, Sebastian; Esch, Bianca; Wälte, Mike; Vargas Duarte, Prado; Walter, Stefan; Ungermann, Christian; Bohnert, Maria & Fröhlich, Florian
-
Compartmentation and functions of sphingolipids. Current Opinion in Cell Biology, 74, 104-111.
Körner, Carolin & Fröhlich, Florian
-
Ferroptosis-protective membrane domains in quiescence. Cell Reports, 42(12), 113561.
Megarioti, Amalia H.; Esch, Bianca M.; Athanasopoulos, Alexandros; Koulouris, Dimitrios; Makridakis, Manousos; Lygirou, Vasiliki; Samiotaki, Martina; Zoidakis, Jerome; Sophianopoulou, Vicky; André, Bruno; Fröhlich, Florian & Gournas, Christos
-
Identification of distinct active pools of yeast serine palmitoyltransferase in sub-compartments of the ER. Journal of Cell Science, 136(23).
Esch, Bianca M.; Walter, Stefan; Schmidt, Oliver & Fröhlich, Florian
-
Structure of the ceramide-bound SPOTS complex. Nature Communications, 14(1).
Schäfer, Jan-Hannes; Körner, Carolin; Esch, Bianca M.; Limar, Sergej; Parey, Kristian; Walter, Stefan; Januliene, Dovile; Moeller, Arne & Fröhlich, Florian
-
Yeast Svf1 binds ceramides and contributes to sphingolipid metabolism at the ER cis-Golgi interface. Journal of Cell Biology, 222(5).
Limar, Sergej; Körner, Carolin; Martínez-Montañés, Fernando; Stancheva, Viktoriya G.; Wolf, Verena N.; Walter, Stefan; Miller, Elizabeth A.; Ejsing, Christer S.; Galassi, Vanesa Viviana & Fröhlich, Florian
-
Structure of the yeast ceramide synthase. Nature Structural & Molecular Biology, 32(3), 441-449.
Schäfer, Jan-Hannes; Clausmeyer, Lena; Körner, Carolin; Esch, Bianca M.; Wolf, Verena N.; Sapia, Jennifer; Ahmed, Yara; Walter, Stefan; Vanni, Stefano; Januliene, Dovile; Moeller, Arne & Fröhlich, Florian
-
The structure of the Orm2-containing serine palmitoyltransferase complex reveals distinct inhibitory potentials of yeast Orm proteins. Cell Reports, 44(7), 114627.
Körner, Carolin; Schäfer, Jan-Hannes; Esch, Bianca M.; Parey, Kristian; Walter, Stefan; Teis, David; Januliene, Dovile; Schmidt, Oliver; Moeller, Arne & Fröhlich, Florian
