Squalene lipotoxicity in a lipid droplet‐less yeast mutant is linked to plasma membrane dysfunction

Yeast ◽  
2020 ◽  
Vol 37 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Zsófia Csáky ◽  
Martina Garaiová ◽  
Marie Kodedová ◽  
Martin Valachovič ◽  
Hana Sychrová ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Droplet ◽  
Yeast Mutant

scholarly journals Drosophila Snazarus Regulates a Lipid Droplet Population at Plasma Membrane-Droplet Contacts in Adipocytes

2019 ◽  
Vol 50 (5) ◽  
pp. 557-572.e5 ◽  
Author(s):  
Rupali Ugrankar ◽  
Jade Bowerman ◽  
Hanaa Hariri ◽  
Mintu Chandra ◽  
Kevin Chen ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Droplet

scholarly journals OsProT1 and OsProT3 Function to Mediate Proline- and γ-aminobutyric acid-specific Transport in Yeast and are Differentially Expressed in Rice (Oryza sativa L.)

Rice ◽  
2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Jin-Hong Lin ◽  
Zhi-Jun Xu ◽  
Jia-Shi Peng ◽  
Jing Zhao ◽  
Guo-Bin Zhang ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Oryza Sativa L ◽  
Ectopic Expression ◽  
Cadmium Stress ◽  
Aminobutyric Acid ◽  
Plant Protoplasts ◽  
Yeast Mutant ◽  
Qrt Pcr ◽  
Physiological Processes ◽  
Molecular Components

Abstract Background Proline (Pro) and γ-aminobutyric acid (GABA) play important roles in plant development and stress tolerance. However, the molecular components responsible for the transport of these molecules in rice remain largely unknown. Results Here we identified OsProT1 and OsProT3 as functional transporters for Pro and GABA. Transient expression of eGFP-OsProTs in plant protoplasts revealed that both OsProT1 and OsProT3 are localized to the plasma membrane. Ectopic expression in a yeast mutant demonstrated that both OsProT1 and OsProT3 specifically mediate transport of Pro and GABA with affinity for Pro in the low affinity range. qRT-PCR analyses suggested that OsProT1 was preferentially expressed in leaf sheathes during vegetative growth, while OsProT3 exhibited relatively high expression levels in several tissues, including nodes, panicles and roots. Interestingly, both OsProT1 and OsProT3 were induced by cadmium stress in rice shoots. Conclusions Our results suggested that plasma membrane-localized OsProT1 and OsProT3 efficiently transport Pro and GABA when ectopically expressed in yeast and appear to be involved in various physiological processes, including adaption to cadmium stress in rice plants.

scholarly journals SLDP and LIPA mediate lipid droplet-plasma membrane tethering in Arabidopsis thaliana

2022 ◽  
Author(s):  
Hannah E Krawczyk ◽  
Siqi Sun ◽  
Nathan Doner ◽  
Qiqi Yan ◽  
Magdiel Sheng Satha Lim ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Plasma Membrane ◽  
Lipid Droplet ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Protein Protein Interaction ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Tethering

Membrane contact sites (MCS) are inter-organellar connections that allow for the direct exchange of molecules, such as lipids or Ca2+ between organelles, but can also serve to tether organelles at specific locations within cells. Here we identified and characterised three proteins that form a lipid droplet (LD)-plasma membrane (PM) tethering complex in plant cells, namely LD-localised SEED LD PROTEIN (SLDP) 1 and 2 and PM-localised LD-PLASMA MEMBRANE ADAPTOR (LIPA). Using proteomics and different protein-protein interaction assays, we show that both SLDPs associate with LIPA. Disruption of either SLDP1 and 2 expression, or that of LIPA, leads to an aberrant clustering of LDs in Arabidopsis seedlings. Ectopic co-expression of one of the SLDPs with LIPA on the other hand is sufficient to reconstitute LD-PM tethering in Nicotiana tabacum pollen tubes, a cell type characterised by dynamically moving LDs in the cytosolic streaming. Further, confocal laser scanning microscopy revealed both SLDP2.1 and LIPA to be enriched at LD-PM contact sites in seedlings. These and other results suggest that SLDP and LIPA interact to form a tethering complex that anchors a subset of LDs to the PM during post-germinative seedling growth in Arabidopsis thaliana.

scholarly journals Rv2744c Is a PspA Ortholog That Regulates Lipid Droplet Homeostasis and Nonreplicating Persistence in Mycobacterium tuberculosis

2016 ◽  
Vol 198 (11) ◽  
pp. 1645-1661 ◽  
Author(s):  
Richard M. Armstrong ◽  
Katherine L. Adams ◽  
Joseph E. Zilisch ◽  
Daniel J. Bretl ◽  
Hiromi Sato ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Plasma Membrane ◽  
Lipid Droplet ◽  
Causative Agent ◽  
Cell Envelope ◽  
Membrane Integrity ◽  
Morbidity And Mortality ◽  
Therapeutic Interventions ◽  
Content Type ◽  
Envelope Stress

ABSTRACTMycobacterium tuberculosis, the causative agent of tuberculosis (TB), remains a significant cause of morbidity and mortality worldwide, despite the availability of a live attenuated vaccine and anti-TB antibiotics. The vast majority of individuals infected withM. tuberculosisdevelop an asymptomatic latent infection in which the bacterium survives within host-generated granulomatous lesions in a physiologically altered metabolic state of nonreplicating persistence. The granuloma represents an adverse environment, asM. tuberculosisis exposed to various stressors capable of disrupting the essential constituents of the bacterium. In Gram-negative and Gram-positive bacteria, resistance to cell envelope stressors that perturb the plasma membrane is mediated in part by proteins comprising the phage shock protein (Psp) system. PspA is an important component of the Psp system; in the presence of envelope stress, PspA localizes to the inner face of the plasma membrane, homo-oligomerizes to form a large scaffold-like complex, and helps maintain plasma membrane integrity to prevent a loss of proton motive force.M. tuberculosisand other members of theMycobacteriumgenus are thought to encode a minimal functional unit of the Psp system, including an ortholog of PspA. Here, we show that Rv2744c possesses structural and physical characteristics that are consistent with its designation as a PspA family member. However, althoughRv2744cis upregulated under conditions of cell envelope stress, loss ofRv2744cdoes not alter resistance to cell envelope stressors. Furthermore, Rv2744c localizes to the surface of lipid droplets inMycobacteriumspp. and regulates lipid droplet number, size, andM. tuberculosispersistence during anaerobically induced dormancy. Collectively, our results indicate that Rv2744c is a bona fide ortholog of PspA that may function in a novel role to regulate lipid droplet homeostasis and nonreplicating persistence (NRP) inM. tuberculosis.IMPORTANCEMycobacterium tuberculosisis the causative agent of tuberculosis, a disease associated with significant morbidity and mortality worldwide.M. tuberculosisis capable of establishing lifelong asymptomatic infections in susceptible individuals and reactivating during periods of immune suppression to cause active disease. The determinants that are important for persistent infection ofM. tuberculosisor for reactivation of this organism from latency are poorly understood. In this study, we describe our initial characterizations of Rv2744c, an ortholog of phage shock protein A (PspA) that regulates the homeostasis of lipid bodies and nonreplicating persistence inM. tuberculosis. This function of PspA inM. tuberculosisis novel and suggests that PspA may represent a unique bacterial target upon which to base therapeutic interventions against this organism.

scholarly journals Mouse aldehyde dehydrogenase ALDH3B2 is localized to lipid droplets via two C-terminal tryptophan residues and lipid modification

2014 ◽  
Vol 465 (1) ◽  
pp. 79-87 ◽  
Author(s):  
Takuya Kitamura ◽  
Shuyu Takagi ◽  
Tatsuro Naganuma ◽  
Akio Kihara
Keyword(s):  
Plasma Membrane ◽  
Substrate Specificity ◽  
Aldehyde Dehydrogenase ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Intracellular Localization ◽  
Lipid Modification ◽  
Aldehyde Dehydrogenases ◽  
Tryptophan Residues

The mouse aldehyde dehydrogenases ALDH3B2 and ALDH3B3 exhibit similar substrate specificity but distinct intracellular localization (ALDH3B2, lipid droplets; ALDH3B3, plasma membrane). The C-terminal prenylation and two tryptophan residues are important for the lipid droplet localization of ALDH3B2.

scholarly journals Membrane-bound sn-1,2-diacylglycerols explain the dissociation of hepatic insulin resistance from hepatic steatosis in MTTP knockout mice

2020 ◽  
Vol 61 (12) ◽  
pp. 1565-1576 ◽  
Author(s):  
Abudukadier Abulizi ◽  
Daniel F. Vatner ◽  
Zhang Ye ◽  
Yongliang Wang ◽  
Joao-Paulo Camporez ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Plasma Membrane ◽  
Insulin Sensitivity ◽  
Hepatic Steatosis ◽  
Lipid Droplet ◽  
Microsomal Triglyceride Transfer Protein ◽  
Hepatic Insulin Resistance ◽  
Hepatic Insulin Sensitivity ◽  
Hepatic Insulin Signaling ◽  
Ceramide Content

Microsomal triglyceride transfer protein (MTTP) deficiency results in a syndrome of hypolipidemia and accelerated NAFLD. Animal models of decreased hepatic MTTP activity have revealed an unexplained dissociation between hepatic steatosis and hepatic insulin resistance. Here, we performed comprehensive metabolic phenotyping of liver-specific MTTP knockout (L-Mttp−/−) mice and age-weight matched wild-type control mice. Young (10–12-week-old) L-Mttp−/− mice exhibited hepatic steatosis and increased DAG content; however, the increase in hepatic DAG content was partitioned to the lipid droplet and was not increased in the plasma membrane. Young L-Mttp−/− mice also manifested normal hepatic insulin sensitivity, as assessed by hyperinsulinemic-euglycemic clamps, no PKCε activation, and normal hepatic insulin signaling from the insulin receptor through AKT Ser/Thr kinase. In contrast, aged (10-month-old) L-Mttp−/− mice exhibited glucose intolerance and hepatic insulin resistance along with an increase in hepatic plasma membrane sn-1,2-DAG content and PKCε activation. Treatment with a functionally liver-targeted mitochondrial uncoupler protected the aged L-Mttp−/− mice against the development of hepatic steatosis, increased plasma membrane sn-1,2-DAG content, PKCε activation, and hepatic insulin resistance. Furthermore, increased hepatic insulin sensitivity in the aged controlled-release mitochondrial protonophore-treated L-Mttp−/− mice was not associated with any reductions in hepatic ceramide content. Taken together, these data demonstrate that differences in the intracellular compartmentation of sn-1,2-DAGs in the lipid droplet versus plasma membrane explains the dissociation of NAFLD/lipid-induced hepatic insulin resistance in young L-Mttp−/− mice as well as the development of lipid-induced hepatic insulin resistance in aged L-Mttp−/− mice.

Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

1977 ◽  
Vol 35 ◽  
pp. 596-597
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Candida Utilis ◽  
Synthetic Medium ◽  
Freeze Fracture ◽  
Translational Diffusion ◽  
Yeast Cells ◽  
Distilled Water ◽  
Intramembrane Particles ◽  
The Matrix ◽  
Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

Organization of the Pellicle and the Muciferous Glands in Euglena Gracilis

1970 ◽  
Vol 28 ◽  
pp. 104-105
Author(s):  
Hilton H. Mollenhauer ◽  
W. Evans
Keyword(s):  
Plasma Membrane ◽  
Euglena Gracilis ◽  
Complex Forms ◽  
Secondary Periodicity

The pellicular structure of Euglena gracilis consists of a series of relatively rigid strips (Fig. 1) composed of ridges and grooves which are helically oriented along the cell and which fuse together into a common junction at either end of the cell. The strips are predominantly protein and consist in part of a series of fibers about 50 Å in diameter spaced about 85 Å apart and with a secondary periodicity of about 450 Å. Microtubules are also present below each strip (Fig. 1) and are often considered as part of the pellicular complex. In addition, there may be another fibrous component near the base of the pellicle which has not yet been very well defined.The pellicular complex lies underneath the plasma membrane and entirely within the cell (Fig. 1). Each strip of the complex forms an overlapping junction with the adjacent strip along one side of each groove (Fig. 1), in such a way that a certain amount of sideways movement is possible between one strip and the next.

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