Browse
Submit Data
Databases
API
Help

Dataset Information

187 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Rab18 is not necessary for lipid droplet biogenesis or turnover in human mammary carcinoma cells

ABSTRACT: Rab GTPases recruit peripheral membrane proteins and can define organelle identity. Rab18 localizes to the ER but also to the surfaces of lipid droplets (LDs), where it has been implicated in effector protein recruitment and in defining LD identity. Here, we studied Rab18 localization and function in SUM159 cells. Rab18 localized to the ER and to LD membranes upon LD induction, with the latter depending on the Rab18 activation state. In cells lacking Rab18, LDs were modestly reduced in size and numbers, but we found little evidence for Rab18 function in LD formation, LD turnover upon cell starvation, or the targeting of several proteins to LDs. We conclude that Rab18 is not a general, necessary component of the protein machinery involved in LD biogenesis or turnover, but instead likely plays a specialized role in specific cell types

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Breast, Cell Culture

DISEASE(S): Breast Cancer

SUBMITTER: Zon Weng Lai

LAB HEAD: Tobias Walther

PROVIDER: PXD009683 | Pride | 2018-06-06

REPOSITORIES: Pride

ACCESS DATA

Json Xml

Similar Datasets

RAB18 impacts autophagy via lipid droplet-derived lipid transfer and is rescued by ATG9A

Project description:Autophagy is a lysosomal degradation pathway that mediates protein and organelle turnover and maintains cellular homeostasis. Autophagosomes transport cargo to lysosomes and their formation is dependent on an appropriate lipid supply. Here, we show that the knockout of the RAB GTPase RAB18 interferes with lipid droplet (LD) metabolism, resulting in an impaired fatty acid mobilization. The reduced LD-derived lipid availability influences autophagy and provokes adaptive modifications of the autophagy network, which include increased ATG2B expression and ATG12-ATG5 conjugate formation as well as enhanced ATG2B and ATG9A phosphorylation. Phosphorylation of ATG9A directs this transmembrane protein to the site of autophagosome formation and this particular modification is sufficient to rescue autophagic activity under basal conditions in the absence of RAB18. However, it is incapable of enabling an increased autophagy under inductive conditions. Thus, we illustrate the role of RAB18 in connecting LDs and autophagy, further emphasize the importance of LD-derived lipids for the degradative pathway, and characterize an ATG9A phosphorylation-dependent autophagy rescue mechanism as an adaptive response that maintains autophagy under conditions of reduced LD-derived lipid availability.

2020-01-29 | PXD013719 | Pride

Identification of molecular machinery mediating ER to lipid droplet protein targeting

Project description:Lipid droplets (LDs) are organelles that store lipids and contain important metabolic proteins at their surfaces. The pathway for membrane-embedded hydrophobic proteins to reach the LD surface from the ER is largely unknown. Here, we find that many proteins, including key lipid synthesis and degradation enzymes, are excluded from forming LDs in the ER by the seipin oligomeric complex and target LDs via ER-LD membrane continuities that are established well after LD formation. We utilized systematic, unbiased approaches to identify key components of this ER-to-LD (ERTOLD) pathway. We find that specific membrane-fusion machinery, including membrane fusion regulators (Trs20 and Rab1), a tether (Rint1), and effectors (Syx5, membrin, Bet1, Ykt6), are required for late ERTOLD targeting of GPAT4 and other proteins that utilize this pathway. The fusion machinery components localize to the interface of LDs and the ER, and within the ER, appear to be organized at ER exit sites. Our data therefore uncover a novel mechanism for membrane protein trafficking for ERTOLD targeting via heterotypic organelle fusion between the ER and LDs.

2022-06-27 | PXD027283 | Pride

Lipid droplets protect human β-cells from lipotoxic-induced stress and cell identity changes

Project description:Free fatty acids (FFAs) are often stored in lipid droplet (LD) depots for eventual metabolic and/or synthetic use in many cell types, such a muscle, liver, and fat. In pancreatic islets, overt LD accumulation was detected in humans but not mice. LD buildup in islets was principally observed after roughly 11 years of age, increasing throughout adulthood under physiologic conditions, and also enriched in type 2 diabetes. To obtain insight into the role of LDs in human islet β cell function, the levels of a key LD scaffold protein, perilipin2 (PLIN2), were manipulated by lentiviral-mediated knock-down (KD) or over-expression (OE) in EndoCβH2-Cre cells, a human cell line with adult islet β-like properties. Glucose stimulated insulin secretion was blunted in PLIN2KD cells and improved in PLIN2OE cells. An unbiased transcriptomic analysis revealed that limiting LD formation induced effectors of endoplasmic reticulum (ER) stress that compromised the expression of critical β cell function and identity genes. These changes were essentially reversed by PLIN2OE or using the ER stress inhibitor, tauroursodeoxycholic acid. These results strongly suggest that LDs are essential for adult human islet β cell activity by preserving FFA homeostasis.

2021-09-15 | GSE184016 | GEO

The large GTPase Sey1/atlastin mediates lipid droplet- and FadL-dependent intracellular fatty acid metabolism of Legionella pneumophila

Project description:The facultative intracellular bacterium Legionella pneumophila employs the Icm/Dot type IV secretion system (T4SS) to replicate in a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). The ER-resident large fusion GTPase Sey1/atlastin-3 promotes remodeling and expansion of LCVs, and the GTPase is also implicated in the formation of ER-derived lipid droplets (LDs). Here we reveal that LCVs intimately interact with palmitate-induced LDs in Dictyostelium discoideum amoeba. Comparative proteomics of LDs isolated from the D. discoideum parental strain Ax3 or sey1 revealed 192 differentially produced proteins, of which 7 or 22 were exclusively detected in LDs isolated from strain Ax3 or sey1, respectively. Using dually fluorescence-labeled amoeba producing the LCV marker P4C-GFP or AmtA-GFP and the LD marker mCherry-perilipin, we show that Sey1 and the L. pneumophila Icm/Dot T4SS as well as the effector LegG1 promote LCV-LD interactions. In vitro reconstitution of the LCV-LD interactions using purified LCVs and LDs from D. discoideum Ax3 or sey1 revealed that Sey1 and GTP promote this process. The LCV-LD interactions were impaired forsey1-derived LDs, suggesting that Sey1 regulates LD traits. Palmitate promoted the growth of L. pneumophila in D. discoideum Ax3 but not in sey1 and of wild-type but not mutant bacteria lacking a homologue of the E. coli fatty acid transporter FadL. Finally, isotopologue profiling indicated that intracellular L. pneumophila metabolizes 13C-palmitate, and its catabolism was reduced in D. discoideum sey1 and L. pneumophila fadL. Taken together, our results reveal that Sey1 mediates LD- and FadL-dependent fatty acid metabolism of intracellular L. pneumophila

2023-06-07 | PXD038200 | Pride

Systematic genome perturbation reveals coordination of lipid droplets and metabolic gene regulation

Project description:Lipid droplets (LDs) store lipids for metabolic eneergy and are central to cellular lipid homeostasis. The mechanisms coordinating lipid storage in LDs with cellular metabolism are unclear but relevant to obesity-related diseases. Here we utilized genome-wide screening to identify genes that modulate lipid storage in human macrophages, a cell type relevant to metabolic diseases. Among ~550 genes regulating lipid storage, we identify MLX, a basic helix-loop-helix leucine-zipper transcription factor that regulates multiple metabolic processes. We show that MLX and family members MLXIP/MondoA and MLXIPL/ChREBP bind LDs via C-terminal amphipathic helices. When LDs increase in cells, LD binding of MLX, MLXIP/MondoA, and MLXIPL/ChREBP reduces their transcriptional activity, whereas the absence of LDs results in hyperactivation. Our findings uncover an unexpected component to a lipid storage response, in which binding of MLX transcription factors to the LD surface modulates their activity, adjusting the expression of metabolic genes to lipid storage levels.

2021-09-08 | PXD012640 | Pride

Functional multi-organelle units control inflammatory lipid metabolism of macrophages

Project description:Eukaryotic cells contain several membrane-separated organelles to compartmentalize distinct metabolic reactions. However, it has remained unclear how these organelle systems are coordinated, when cells adapt metabolic pathways to support their development, survival or effector functions. Here we present OrgaPlexing, a multispectral organelle imaging approach for the comprehensive mapping of six key metabolic organelles and their interactions. We use this analysis on macrophages, immune cells that undergo rapid metabolic switches upon sensing bacterial and inflammatory stimuli. Our results identify lipid droplets (LDs) as primary inflammatory responder organelle, which forms three- and four-way interactions with other organelles. While clusters with endoplasmic reticulum (ER) and mitochondria (M-ER-LD unit) help supply fatty acids for LD growth, the additional recruitment of peroxisomes (M-ER-P-LD unit) supports fatty acid efflux from LDs. Interference with individual components of these units has direct functional consequences for inflammatory lipid synthesis. Together, we show that macrophages form functional multi-organellar units (MOUs) to support metabolic adaptation, and provide an experimental strategy to identify organelle-metabolic signaling hubs.

2024-05-03 | GSE235484 | GEO

BirA*-RAB18 proximity biotinylation in HeLa cells

Project description:Proximity labelling using transient expression of the same exogenous BirA*-RAB18 construct in wild-type HeLa cells and in otherwise isogenic RAB3GAP1-, RAB3GAP2- and TRAPPC9-null HeLa cell lines.

2024-01-26 | PXD016336 | Pride

Arabidopsis EARLY RESPONSIVE TO DEHYDRATION 7 associates with lipid droplets via its senescence domain

Project description:Lipid droplets (LDs) are neutral lipid-containing organelles found in all kingdoms of life and are decorated with proteins that carry out a variety of functions. Despite the similar subcellular location, the LD proteins that carry out these functions vary between kingdoms, and only a few LD proteins share obvious amino acid sequence identity between plants and mammals. To better understand the many cellular roles of LDs in plants, a more comprehensive inventory and characterization of LD proteins is required. To this end, we analyzed proteomics data of isolated LDs and identified EARLY RESPONSIVE TO DEHYDRATION 7 (ERD7) as a putative LD protein. mCherry-tagged ERD7 localized to both LDs and to the cytosol when transiently expressed in Nicotiana benthamiana leaves, whereas a fragment of ERD7 containing a “senescence domain” (SD) localized exclusively to LDs with no appreciable accumulation in the cytosol. Similarly, the SDs of the two Arabidopsis ERD7 homologs, here termed SENESCENCE-ASSOCIATED A2 (SENA2) and SENA3, localized exclusively to LDs as did the SD of a phylogenetically distant SD-containing protein, human spartin. In contrast, SDs of the Arabidopsis SENESCENCE-ASSOCIATED B (SENB) family proteins did not localize to LDs and instead localized to mitochondria. Arabidopsis erd7 mutants did not display any observable LD phenotypes in seeds, seedlings or senescent leaves, perhaps due to genetic redundancy of the SENA protein family. A yeast-two-hybrid screen revealed that the S4 family of MYB transcription factors interacts with ERD7, providing a potential avenue for the exploration of ERD7 function. In summary, we here report a previously unappreciated family of plant LD-associated proteins, SENA, which contain SDs that localize to LDs.

2021-03-29 | PXD023047 | Pride

Lipid droplet availability affects neural stem/progenitor cell metabolism and proliferation

Project description:Neural stem/progenitor cells (NSPCs) generate new neurons throughout adulthood. However, the underlying regulatory processes are still not fully understood. Lipid metabolism plays an important role in regulating NSPC activity: build-up of lipids is crucial for NSPC proliferation, whereas break-down of lipids has been shown to regulate NSPC quiescence. Despite their central role for cellular lipid metabolism, the role of lipid droplets (LDs), the lipid storing organelles, in NSPCs remains underexplored. Here we show that LDs are highly abundant in adult mouse NSPCs, and that LD accumulation is significantly altered upon fate changes such as quiescence and differentiation. NSPC proliferation is influenced by the number of LDs, inhibition of LD build-up, breakdown or usage, and the asymmetric inheritance of LDs during mitosis. Furthermore, high LD-containing NSPCs have increased metabolic activity and capacity, but do not suffer from increased oxidative damage. Together, these data indicate an instructive role for LDs in driving NSPC behaviour.

2021-11-10 | GSE187470 | GEO

Identification of a lipid droplet-plasma membrane tethering complex

Project description:Membrane contact sites (MCS) are interorganellar contacts that allow for the direct exchange of molecules such as lipids or Ca2+ between organelles, but can also be a mean for tethering of organelles. In mammals and yeast, LDs have been shown to engage in MCS with nearly all organelles in the cell, while in plants only LD-ER and LD-peroxisome contacts have been characterised. We here analyse three proteins, LD-localised SEED LIPID DROPLET PROTEIN (SLDP) 1 and 2 and PM-localised LIPID DROPLET PLASMA MEMBRANE ADAPTOR. Knockout of SLDP1 and 2, as well as knockout of LIPA lead to aberrant clustering of LDs in seedlings, while ectopic co-expression of SLDP and LIPA in Nicotiana tabacum pollen tubes is sufficient to reconstitute LD-PM tethering in this tissue, where LDs normally dynamically float in the cytosol stream. We propose a model, in which SLDP and LIPA interact and thereby form a tether to anchor a subset of LDs to the PM during post-germinative growth in Arabidopsis thaliana.

2022-06-09 | PXD022769 | Pride

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data