Project

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Lipid Acetylation, Storage, Export and Degradation

English title Lipid Acetylation, Storage, Export and Degradation
Applicant Schneiter Roger
Number 134742
Funding scheme Project funding (Div. I-III)
Research institution Division de Biochimie Département de Biologie Université de Fribourg
Institution of higher education University of Fribourg - FR
Main discipline Biochemistry
Start/End 01.07.2011 - 30.09.2014
Approved amount 468'000.00
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All Disciplines (2)

Discipline
Biochemistry
Cellular Biology, Cytology

Keywords (9)

Lipid homeostasis; neutral lipid storage; lipid droplets; triacylglycerol; cholesterol; sphingolipids; long-chain base; avetylation; Saccharomyces cerevisiae

Lay Summary (English)

Lead
Lay summary

Lipids are major constituents of cell membranes and serve as important signaling molecules that allow the cell to coordinate growth and membrane expansion in response to extracellular cues, such as temperature, pH, or nutrient availability. One of the key signaling molecules required for the heat-shock response, pH homeostasis, and for nutrient uptake and endocytosis is the sphingoid long-chain base, an intermediate in the sphingolipid biosynthetic pathway. We have recently observed that cells, which accumulate high levels of long-chain base, acetylate and export the long-chain base into the culture media. Reducing the efficiency of this export pathway impairs growth and renders cells thermo sensitive, indicating that export of acetylated long-chain base serves to reduce the detrimental consequences of intracellular accumulation of the sphingoid base. This lipid acetylation and export pathway thus shares many of the properties of the sterol acetylation and export pathway that we identified before. The aim of this part of the project is to characterize this long-chain base acetylation and export pathway in more detail. In particular, we would like to identify the components that catalyze acetylation of the sphingoid base, determine how the lipid is exported from cells, and identify putative proteins that bind the acetylated lipid.
In a complementary part, we will characterize different aspects of neutral lipid storage and mobilization. Neutral lipids, particularly triacylglycerol (TAG) and steryl esters (STE) constitute a reservoir of metabolic energy that is stored in a dedicated intracellular compartment, the lipid droplet (LD). The energy stored within LDs is liberated through beta-oxidation of the fatty acids that are esterified to these neutral lipids. How exactly these neutral lipids, which are generated by ER-localized membrane-embedded enzymes, concentrate up and become packaged into the globular structure of an LD is not yet fully understood. We have studied the biogenesis of LDs in the past using a genetic system in which transcriptional induction of neutral lipid biosynthetic enzymes results in de novo formation of LDs. The data obtained in these previous studies suggest that LDs may be formed in the luminal compartment of the endoplasmic reticulum (ER) and that they do not form independent entities within the cytosol, as is postulated by one popular model of LD formation. We will now test more directly whether LDs are present inside the ER lumen, using a set of novel functional and morphological approaches. In an independent series of experiments we will characterize the fusion of lipid droplets to determine whether LD fusion is morphologically and functionally linked to fusion of the ER membrane/nuclear envelope.
We expect that the results of this basic research program will significantly advance our understanding of the fundamental cellular processes that govern key aspects of sphingoid base signaling as well as the biogenesis of LDs, which is important to understand the pathophysiology of neutral lipid accumulation, the hallmark of obesity.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Schistosoma mansoni venom allergen-like protein 4 (SmVAL4) is a novel lipid-binding SCP/TAPS protein that lacks the prototypic CAP motifs
Kelleher A., Darwiche R., Rezende W. C., Farias L. P., Leite L. C. C., Schneiter R., Asojo O. A. (2014), Schistosoma mansoni venom allergen-like protein 4 (SmVAL4) is a novel lipid-binding SCP/TAPS protein that lacks the prototypic CAP motifs, in Acta Cryst., D70, 2186-2196.
The caveolin-binding motif of the pathogen related yeast protein Pry1, a member of the CAP protein superfamily, is required for in vivo export of cholesteryl acetate.
Choudhary V., Darwiche R., Gfeller D., Zoete V., Michielin O., Schneiter R. (2014), The caveolin-binding motif of the pathogen related yeast protein Pry1, a member of the CAP protein superfamily, is required for in vivo export of cholesteryl acetate., in J. Lipid Res., 55, 883-894.
TORC1 Regulates Pah1 Phosphatidate Phosphatase Activity via the Nem1/Spo7 Protein Phosphatase Complex
Dubots E., Cottier S., Peli-Gulli M.P., Jaquenoud M., Bontron S., Schneiter R., De Virgilio C. (2014), TORC1 Regulates Pah1 Phosphatidate Phosphatase Activity via the Nem1/Spo7 Protein Phosphatase Complex, in PLoS One, 9, e104194.
A novel Sit4 phosphatase complex is involved in the response to ceramide stress in yeast.
Woodacre A., Lone M. A., Jablonowski D., Schneiter R., Giorgini F., Schaffrath R. (2013), A novel Sit4 phosphatase complex is involved in the response to ceramide stress in yeast., in Oxidative Medicine and Cellular Longevity 2013, Article ID 129645, ID 129645.
Expression of oleosin and perilipins in yeast promote formation of lipid droplets from the endoplasmatic reticulum.
Jacquier N., Mishra S., Choudhary V., Schneiter R. (2013), Expression of oleosin and perilipins in yeast promote formation of lipid droplets from the endoplasmatic reticulum., in J. Cell Sci., 126, 5198-5209.
The CAP protein superfamily: function in sterol export and fungal virulence
Schneiter R., Di Pietro A. (2013), The CAP protein superfamily: function in sterol export and fungal virulence, in BioMol Concepts , 4, 519-525.
The natural diyne-furan fatty acid EV-086 is an inhibitor of fungal delta-9 fatty acid desaturation with efficacy in a model of skin dermatophytosis.
Knechtle P., Diefenbacher M., Greve K., Brianza F., Folly Ch., Heider H., Lone M. A., Long L., Meyer J-P., Roussel P., Ghannoum M., Schneiter R., Sorensen A. (2013), The natural diyne-furan fatty acid EV-086 is an inhibitor of fungal delta-9 fatty acid desaturation with efficacy in a model of skin dermatophytosis., in Antimicrob Agents Chemother., 58, 455-466.
Mechanisms of sterol uptake and transport in yeast.
Jacquier Nicolas, Schneiter Roger (2012), Mechanisms of sterol uptake and transport in yeast., in The Journal of steroid biochemistry and molecular biology, 129(1-2), 70-8.
Pathogen-Related Yeast (PRY) proteins and members of the CAP superfamily are secreted sterol-binding proteins.
Choudhary V. and Schneiter R. (2012), Pathogen-Related Yeast (PRY) proteins and members of the CAP superfamily are secreted sterol-binding proteins., in Proc. Natl. Acad. Sci. USA, 109, 16882-16887.
Regulation of sphingolipid synthesis via Orm1 and Orm2 in yeast
2) Liu M. Huang C. Polu S. R. Schneiter R. and Chang A. (2012), Regulation of sphingolipid synthesis via Orm1 and Orm2 in yeast, in J. Cell Sci., 125, 2428-2435.
Regulation of sphingolipid synthesis via Orm1 and Orm2 in yeast.
Liu Ming, Huang Chunjuan, Polu Surendranath R, Schneiter Roger, Chang Amy (2012), Regulation of sphingolipid synthesis via Orm1 and Orm2 in yeast., in Journal of cell science, 125, 2428-2435.
Lipid droplets are functionally connected to the endoplasmic reticulum in Saccharomyces cerevisiae.
Jacquier Nicolas, Choudhary Vineet, Mari Muriel, Toulmay Alexandre, Reggiori Fulvio, Schneiter Roger (2011), Lipid droplets are functionally connected to the endoplasmic reticulum in Saccharomyces cerevisiae., in Journal of cell science, 124(Pt 14), 2424-37.
The topology of the triacylglycerol synthesizing enzyme Lro1 indicates that neutral lipids can be produced within the luminal compartment of the endoplasmatic reticulum: Implications for the biogenesis of lipid droplets.
Choudhary Vineet, Jacquier Nicolas, Schneiter Roger (2011), The topology of the triacylglycerol synthesizing enzyme Lro1 indicates that neutral lipids can be produced within the luminal compartment of the endoplasmatic reticulum: Implications for the biogenesis of lipid droplets., in Communicative & integrative biology, 4(6), 781-4.
Expression of perilipin 5 promotes lipid droplet formation in yeast
Mishra S., Schneiter R., Expression of perilipin 5 promotes lipid droplet formation in yeast, in Communicative & Integrative Biology.

Collaboration

Group / person Country
Types of collaboration
Evolva SA Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Industry/business/other use-inspired collaboration
University of Fribourg Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Nebraska Medical Center United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
University of Michigan United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dartmouth Medical School, Hanover United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
University of Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
EMBO Meeting The Endoplasmic Reticulum (ER) as a hub for organelle communication, Girona, Spain Talk given at a conference Keeping the ER membrane clean 26.10.2014 Girona, Spain Schneiter Roger;
Yeast Genetics Meeting, Seattle, USA Poster The caveolin domin of the yeast CAP superfamily member Pry1 is required for sterol binding 29.07.2014 Seattle, United States of America Choudhary Vineet; Darwiche Rabih; Schneiter Roger;
11th yeast lipid conference in Halifax, Canada Poster The caveolin domain of Pry1 is required for sterol binding 29.05.2013 Halifax, Canada Choudhary Vineet; Schneiter Roger; Darwiche Rabih;
Membrane dynamics in Physiology and Disease Talk given at a conference Lipid droplet biogenesis in yeast 05.06.2012 Basel, Switzerland, Switzerland Schneiter Roger; Mishra Shirish;
Microbial Lipids Talk given at a conference A yeast sterol acetylataion and transport pathway 16.05.2012 Bern, Switzerland, Switzerland Schneiter Roger; Choudhary Vineet;
USGEB Meetin Lausanne 2012 Poster Lipid droplet biogenesis in yeast 06.02.2012 Lausanne, Switzerland Mishra Shirish; Choudhary Vineet; Schneiter Roger;
EMBO Meeting Vienna, Austria Poster Neutral Lipid metabolism in Yeast 10.09.2011 Vienna Austria, Austria Choudhary Vineet; Mishra Shirish; Schneiter Roger;


Self-organised

Title Date Place
Microbial Lipids 16.05.2012 Bern, Switzerland, Switzerland

Awards

Title Year
SNF Fellowship for advanced scientists 2012

Associated projects

Number Title Start Funding scheme
120650 Speicherung, Mobilisierung und Umsatz von Neutrallipiden 01.07.2008 Project funding (Div. I-III)
125232 Membrane topology of lipid synthesis, transport, and turnover and their role in the physiology of starvation and aging 01.08.2009 Sinergia
120650 Speicherung, Mobilisierung und Umsatz von Neutrallipiden 01.07.2008 Project funding (Div. I-III)
153416 Lipid Storage and Export 01.10.2014 Project funding (Div. I-III)

Abstract

Lipids are major constituents of cell membranes and serve as important signaling molecules that allow the cell to coordinate growth and membrane expansion in response to extracellular cues, such as temperature, pH, or nutrient availability. One of the key signaling molecules required for the heat-shock response, pH homeostasis, and for nutrient uptake and endocytosis is the sphingoid long-chain base, an intermediate in the sphingolipid biosynthetic pathway. We have recently observed that cells, which accumulate high levels of long-chain base, acetylate and export the long-chain base into the culture media. Reducing the efficiency of this export pathway impairs growth and renders cells thermo sensitive, indicating that export of acetylated long-chain base serves to reduce the detrimental consequences of intracellular accumulation of the sphingoid base. This lipid acetylation and export pathway thus shares many of the properties of the sterol acetylation and export pathway that we identified before. The aim of this part of the project is to characterize this long-chain base acetylation and export pathway in more detail. In particular, we would like to identify the components that catalyze acetylation of the sphingoid base, determine how the lipid is exported from cells, and identify putative proteins that bind the acetylated lipid.In a complementary part, we will characterize different aspects of neutral lipid storage and mobilization. Neutral lipids, particularly triacylglycerol (TAG) and steryl esters (STE) constitute a reservoir of metabolic energy that is stored in a dedicated intracellular compartment, the lipid droplet (LD). The energy stored within LDs is liberated through beta-oxidation of the fatty acids that are esterified to these neutral lipids. How exactly these neutral lipids, which are generated by ER-localized membrane-embedded enzymes, concentrate up and become packaged into the globular structure of an LD is not yet fully understood. We have studied the biogenesis of LDs in the past using a genetic system in which transcriptional induction of neutral lipid biosynthetic enzymes results in de novo formation of LDs. The data obtained in these previous studies suggest that LDs may be formed in the luminal compartment of the endoplasmic reticulum (ER) and that they do not form independent entities within the cytosol, as is postulated by one popular model of LD formation. We will now test more directly whether LDs are present inside the ER lumen, using a set of novel functional and morphological approaches. In an independent series of experiments we will characterize the fusion of lipid droplets upon cell mating/fusion to determine whether LD fusion is morphologically and functionally linked to fusion of the ER membrane/nuclear envelope. In a last set of experiments we will characterize the turnover of triacylglycerol through a lipase that is located inside the vacuole and define the signals that induce relocation of an integral membrane protein from the ER to LDs.We expect that the results of this basic research program will significantly advance our understanding of the fundamental cellular processes that govern key aspects of sphingoid base signaling as well as the biogenesis of LDs, which is important to understand the pathophysiology of neutral lipid accumulation, the hallmark of obesity.
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