scholarly journals Increase in cellular triacylglycerol content and emergence of large ER-associated lipid droplets in the absence of CDP-DG synthase function

2014 ◽  
Vol 25 (25) ◽  
pp. 4083-4095 ◽  
Author(s):  
Yue He ◽  
Candice Yam ◽  
Kyle Pomraning ◽  
Jacqueline S. R. Chin ◽  
Joanne Y. Yew ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Phosphatidic Acid ◽  
Fission Yeast ◽  
Lipid Droplets ◽  
Neutral Lipids ◽  
Sterol Esters ◽  
Triacylglycerol Synthesis ◽  
Kennedy Pathway ◽  
Triacylglycerol Content ◽  
Cellular Organelles

Excess fatty acids and sterols are stored as triacylglycerols and sterol esters in specialized cellular organelles, called lipid droplets. Understanding what determines the cellular amount of neutral lipids and their packaging into lipid droplets is of fundamental and applied interest. Using two species of fission yeast, we show that cycling cells deficient in the function of the ER-resident CDP-DG synthase Cds1 exhibit markedly increased triacylglycerol content and assemble large lipid droplets closely associated with the ER membranes. We demonstrate that these unusual structures recruit the triacylglycerol synthesis machinery and grow by expansion rather than by fusion. Our results suggest that interfering with the CDP-DG route of phosphatidic acid utilization rewires cellular metabolism to adopt a triacylglycerol-rich lifestyle reliant on the Kennedy pathway.

scholarly journals Intracellular Lipid Droplets: From Structure to Function

2017 ◽  
Vol 10 ◽  
pp. 117863531774551 ◽  
Author(s):  
Stefano Vanni
Keyword(s):  
Lipid Droplets ◽  
Neutral Lipids ◽  
Interfacial Structure ◽  
Aqueous Environment ◽  
Sterol Esters ◽  
Computational Approaches ◽  
Main Site ◽  
Natural Surfactant ◽  
Oil Emulsions ◽  
Function Relationship

Lipid droplets (LDs) are unique intracellular organelles that are mainly constituted by neutral lipids (triglycerides, sterol esters). As such they serve as the main site of energy storage in the cell and they are akin to oil emulsions in water. To prevent the direct exposure of the hydrophobic neutral lipids to the aqueous environment of the cytosol, LDs are surrounded by a monolayer of phospholipids that thus behave as a natural surfactant. This interfacial structure is rather unique inside the cell, but a molecular understanding of how the LD structure modulates its functions is still lacking, mainly due to technical challenges in both experimental and computational approaches to investigate oil-in-water emulsions. Recently, we have investigated the structure of LDs using a combination of existing and newly developed computational approaches that are optimized to study oil-water interfaces.1 Our simulations provide a comprehensive molecular characterization of the unique surface properties of LDs, suggesting structure-function relationship in several LD-related metabolic processes.

scholarly journals Spatiotemporal dynamics of triglyceride storage in unilocular adipocytes

2014 ◽  
Vol 25 (25) ◽  
pp. 4096-4105 ◽  
Author(s):  
Michael Chu ◽  
Harini Sampath ◽  
David Y. Cahana ◽  
Christoph A. Kahl ◽  
Romel Somwar ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Adipose Tissue ◽  
Free Fatty Acids ◽  
Lipid Droplets ◽  
Ex Vivo ◽  
Spatiotemporal Dynamics ◽  
Biological Features ◽  
Adipocyte Hypertrophy ◽  
Cellular Organelles

The spatiotemporal dynamics of triglyceride (TG) storage in unilocular adipocytes are not well understood. Here we applied ex vivo technology to study trafficking and metabolism of fluorescent fatty acids in adipose tissue explants. Live imaging revealed multiple cytoplasmic nodules surrounding the large central lipid droplet (cLD) of unilocular adipocytes. Each cytoplasmic nodule harbors a series of closely associated cellular organelles, including micro–lipid droplets (mLDs), mitochondria, and the endoplasmic reticulum. Exogenously added free fatty acids are rapidly adsorbed by mLDs and concurrently get esterified to TG. This process is greatly accelerated by insulin. mLDs transfer their content to the cLD, serving as intermediates that mediate packaging of newly synthesized TG in the large interior of a unilocular adipocyte. This study reveals novel cell biological features that may contribute to the mechanism of adipocyte hypertrophy.

Acetate assimilation by the fission yeast, Schizosaccharomyces pombe

1989 ◽  
Vol 67 (8) ◽  
pp. 464-467 ◽  
Author(s):  
C. S. Tsai ◽  
Ken P. Mitton ◽  
Byron F. Johnson
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Neutral Lipids ◽  
Glyoxylate Cycle ◽  
Yeast Cells ◽  
Peptide Structure ◽  
Synthetase Activity ◽  
Sterol Esters ◽  
Acetate Utilization ◽  
Structure Of Proteins

The fission yeast Schizosaccharomyces pombe utilizes acetate at subinhibitory concentrations in the presence of D-glucose. The nonionized form of acetate is preferentially utilized, oxidized to 14CO2, and assimilated into lipids and proteins. Acetyl CoA synthetase activity greatly increases in the yeast cells grown in media containing acetate. However, glyoxylate cycle enzymes are not detectable in Schizosaccharomyces pombe. [1-14C] Acetate is incorporated into stereols, sterol esters, neutral lipids, and phospholipids. Assimilation of [1-14C]acetate into the peptide structure of proteins was confirmed by a proteolytic digestion experiment.Key words: acetate utilization, fission yeast, Schizosaccharomyces pombe.

Production of lipids and lipase activity during growth of Mucor hiemalis

1982 ◽  
Vol 28 (6) ◽  
pp. 618-622 ◽  
Author(s):  
A. Qayum Mirza ◽  
M. Waheed Akhtar ◽  
M. Nadeem Nawazish ◽  
M. I. D. Chughtai
Keyword(s):  
Fatty Acids ◽  
Carbon Source ◽  
Lipid Content ◽  
Growth Phase ◽  
Lipase Activity ◽  
Polar Lipid ◽  
Neutral Lipids ◽  
Cell Lysis ◽  
Mucor Hiemalis ◽  
Sterol Esters

Production of lipids and lipase activity by a strain of Mucor hiemalis known to have potential for high lipase activity was studied in a medium containing glucose as the carbon source. Most of the glucose was utilized by the end of the growth phase when the mycelium showed maximal lipase activity (17 U/g dry mycelium) as well as maximal lipid content (13 mg/g dr*** mycelium). Maximal broth lipase activity (76 U/100mL) was observed after cell lysis had begun. The fractions identified in the mycelial lipid extracts were sterol esters, triglycerides, fatty acids, diglycerides, sterols, monoglycerides, phosphatidylethanoamine, phosphatidylcholine, phosphatidylserine, and an unknown polar lipid. The proportion between the neutral and the polar lipids was only 0.06 at 44 h, increasing gradually to 1.51 at 164 h of fermentation. A relationship between the production of lipase and the neutral lipids appears to exist.

scholarly journals Lipid Composition of Sheffersomyces stipitis M12 Strain Grown on Glycerol as a Carbon Source

2020 ◽  
Vol 58 (2) ◽  
pp. 203-213
Author(s):  
Stela Križanović ◽  
Damir Stanzer ◽  
Gordana Čanadi Jurešić ◽  
Elizabeta Kralj ◽  
Karla Hanousek-Čiča ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Lipid Metabolism ◽  
Carbon Source ◽  
Lipid Composition ◽  
Solid Phase ◽  
Neutral Lipids ◽  
Wild Strain ◽  
Yeast Cells ◽  
Sterol Esters ◽  
Ergosterol Synthesis

Research background. In this study the content and composition of lipids in ergosterol-reduced Sheffersomyces stipitis M12 strain grown on glycerol as a carbon source is determined. Blocking the ergosterol synthesis route in yeast cells is a recently proposed method for increasing S-adenosyl-L-methionine (SAM) production. Experimental approach. The batch cultivation of M12 yeast was carried out under aerobic conditions in a laboratory bioreactor with glycerol as carbon source, and with pulsed addition of methionine. Glycerol and SAM content were monitored by high-performance liquid chromatography, while fatty acid composition of different lipid classes, separated by solid phase extraction, was determined by gas chromatography. Results and conclusion. Despite the reduced amount of ergosterol in yeast cells, thanks to the reorganized lipid metabolism, M12 strain achieved high biomass yield and SAM production. Neutral lipids prevailed (making more than 75 % of total lipids), but their content and composition differed significantly in the two tested types of yeast. Unsaturated and C18 fatty acids prevailed in both the M12 strain and wild type. In all fractions except free fatty acids, the index of unsaturation in M12 strain was lower than in the wild strain. Our tested strain adjusts itself by changing the content of lipids (mainly phospholipids, sterols and sterol esters), and with desaturation adjustments, to maintain proper functioning and fulfil increased energy needs.Novelty and scientific contribution. Reorganization of S. stipitis lipid composition caused by blocking the metabolic pathway of ergosterol synthesis was presented. A simple scheme of actual lipid metabolism during active SAM production in S. stipitis, grown on glycerol was constructed and shown. This fundamental knowledge of lipid metabolic pathways will be a helpful tool in improving S. stipitis as an expression host and a model organism, opening new perspectives for its applied research.

scholarly journals Lipid-associated PML structures assemble nuclear lipid droplets containing CCTα and Lipin1

2020 ◽  
Vol 3 (8) ◽  
pp. e202000751 ◽  
Author(s):  
Jonghwa Lee ◽  
Jayme Salsman ◽  
Jason Foster ◽  
Graham Dellaire ◽  
Neale D Ridgway
Keyword(s):  
Fatty Acids ◽  
Lipid Droplets ◽  
Promyelocytic Leukemia ◽  
Nuclear Bodies ◽  
High Resolution Imaging ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Pml Nuclear Bodies ◽  
Triacylglycerol Synthesis ◽  
Phosphatidic Acid Phosphatase ◽  
Resolution Imaging

Nuclear lipid droplets (nLDs) form on the inner nuclear membrane by a mechanism involving promyelocytic leukemia (PML), the protein scaffold of PML nuclear bodies. We report that PML structures on nLDs in oleate-treated U2OS cells, referred to as lipid-associated PML structures (LAPS), differ from canonical PML nuclear bodies by the relative absence of SUMO1, SP100, and DAXX. These nLDs were also enriched in CTP:phosphocholine cytidylyltransferase α (CCTα), the phosphatidic acid phosphatase Lipin1, and DAG. Translocation of CCTα onto nLDs was mediated by its α-helical M-domain but was not correlated with its activator DAG. High-resolution imaging revealed that CCTα and LAPS occupied distinct polarized regions on nLDs. PML knockout U2OS (PML KO) cells lacking LAPS had a 40–50% reduction in nLDs with associated CCTα, and residual nLDs were almost devoid of Lipin1 and DAG. As a result, phosphatidylcholine and triacylglycerol synthesis was inhibited in PML KO cells. We conclude that in response to excess exogenous fatty acids, LAPS are required to assemble nLDs that are competent to recruit CCTα and Lipin1.

Fettsäuren und Lipide in farblosen Algen / Fatty Acids and Lipids in Colourless Algae

1974 ◽  
Vol 29 (7-8) ◽  
pp. 399-406 ◽  
Author(s):  
H Glasl ◽  
P Pohl
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fresh Water ◽  
Green Algae ◽  
Acid Content ◽  
Neutral Lipids ◽  
Fatty Acid Content ◽  
Sterol Esters

Abstract The colourless algae, Prototheca portoricensis, Polytoma oviforme, Chlorella variegata (Chlorophyta), and Chilomonas paramecium (Pyrrhophyta) mainly synthesize the 16 : 0, 18 : 1, and partly also 1 8 : 2 and 18 : 3 fatty acids. The major lipids formed were neutral lipids (glycerides and sterol esters) and phospholipids. In their fatty acid content, these organisms resembled fresh water green algae. They differed from the photosynthesizing fresh water green algae, however, in containing none or very low amounts of polyunsaturated C16 acids (16 : 2 , 16 : 3) and glycolipids.

scholarly journals Dictyostelium Lipid Droplets Host Novel Proteins

2013 ◽  
Vol 12 (11) ◽  
pp. 1517-1529 ◽  
Author(s):  
Xiaoli Du ◽  
Caroline Barisch ◽  
Peggy Paschke ◽  
Cornelia Herrfurth ◽  
Oliver Bertinetti ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Unsaturated Fatty Acids ◽  
Neutral Lipids ◽  
Saturated Fatty Acids ◽  
Endoplasmic Reticulum Membrane ◽  
Hydrophobic Core ◽  
Content Type

ABSTRACT Across all kingdoms of life, cells store energy in a specialized organelle, the lipid droplet. In general, it consists of a hydrophobic core of triglycerides and steryl esters surrounded by only one leaflet derived from the endoplasmic reticulum membrane to which a specific set of proteins is bound. We have chosen the unicellular organism Dictyostelium discoideum to establish kinetics of lipid droplet formation and degradation and to further identify the lipid constituents and proteins of lipid droplets. Here, we show that the lipid composition is similar to what is found in mammalian lipid droplets. In addition, phospholipids preferentially consist of mainly saturated fatty acids, whereas neutral lipids are enriched in unsaturated fatty acids. Among the novel protein components are LdpA, a protein specific to Dictyostelium , and Net4, which has strong homologies to mammalian DUF829/Tmem53/NET4 that was previously only known as a constituent of the mammalian nuclear envelope. The proteins analyzed so far appear to move from the endoplasmic reticulum to the lipid droplets, supporting the concept that lipid droplets are formed on this membrane.

scholarly journals ORP5 AND ORP8 ORCHESTRATE LIPID DROPLET BIOGENESIS AND MAINTENANCE AT ER-MITOCHONDRIA CONTACT SITES

2021 ◽  
Author(s):  
Valentin Guyard ◽  
Vera F Monteiro-Cardoso ◽  
Mohyeddine Omrane ◽  
Cecile Sauvanet ◽  
Audrey Houcine ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Phosphatidic Acid ◽  
Lipid Droplets ◽  
Neutral Lipids ◽  
Nucleation And Growth ◽  
Lipid Transfer ◽  
Lipid Transfer Proteins ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact

Lipid droplets (LDs) are the primary organelles of lipid storage, buffering energy fluctuations of the cell. They store neutral lipids in their core that is surrounded by a protein-decorated phospholipid monolayer. LDs arise from the Endoplasmic Reticulum (ER). The ER-protein seipin, localizing at ER-LD junctions, controls LD nucleation and growth. However, how LD biogenesis is spatially and temporally coordinated remains elusive. Here, we show that the lipid transfer proteins ORP5 and ORP8 control LD biogenesis at Mitochondria-Associated ER Membrane (MAM) subdomains, enriched in phosphatidic acid. We found that ORP5/8 regulate seipin recruitment to these MAM-LD contacts, and their loss impairs LD biogenesis. Importantly, the integrity of ER-mitochondria contact sites is crucial for the ORP5/8 function in regulating seipin-mediated LD biogenesis. Our study uncovers an unprecedented ORP5/8 role in orchestrating LD biogenesis at MAMs and brings novel insights into the metabolic crosstalk between mitochondria, ER, and LDs at membrane contact sites.

A Molecular Logic Gate Enables Super-Resolved Imaging of Intracellular Lipid Droplets

2019 ◽  
Author(s):  
Adam Eördögh ◽  
Carolina Paganini ◽  
Dorothea Pinotsi ◽  
Paolo Arosio ◽  
Pablo Rivera-Fuentes
Keyword(s):  
Single Molecule ◽  
Lipid Droplets ◽  
Neutral Lipids ◽  
Logic Gate ◽  
Living Cells ◽  
Three Dimensions ◽  
Single Molecule Imaging ◽  
Molecular Logic Gate ◽  
Molecular Logic ◽  
Cellular Compartments

<div>Photoactivatable dyes enable single-molecule imaging in biology. Despite progress in the development of new fluorophores and labeling strategies, many cellular compartments remain difficult to image beyond the limit of diffraction in living cells. For example, lipid droplets, which are organelles that contain mostly neutral lipids, have eluded single-molecule imaging. To visualize these challenging subcellular targets, it is necessary to develop new fluorescent molecular devices beyond simple on/off switches. Here, we report a fluorogenic molecular logic gate that can be used to image single molecules associated with lipid droplets with excellent specificity. This probe requires the subsequent action of light, a lipophilic environment and a competent nucleophile to produce a fluorescent product. The combination of these requirements results in a probe that can be used to image the boundary of lipid droplets in three dimensions with resolutions beyond the limit of diffraction. Moreover, this probe enables single-molecule tracking of lipids within and between droplets in living cells.</div>

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