scholarly journals Phosphoinositide kinase signaling controls ER-PM cross-talk

2016 ◽  
Vol 27 (7) ◽  
pp. 1170-1180 ◽  
Author(s):  
Deike J. Omnus ◽  
Andrew G. Manford ◽  
Jakob M. Bader ◽  
Scott D. Emr ◽  
Christopher J. Stefan
Keyword(s):  
Cross Talk ◽  
Regulatory System ◽  
Membrane Lipid ◽  
Kinase Signaling ◽  
Membrane Composition ◽  
Membrane Stress ◽  
Lipid Dynamics ◽  
Cellular Integrity ◽  
Normal Cellular Function ◽  
Pi Kinase

Membrane lipid dynamics must be precisely regulated for normal cellular function, and disruptions in lipid homeostasis are linked to the progression of several diseases. However, little is known about the sensory mechanisms for detecting membrane composition and how lipid metabolism is regulated in response to membrane stress. We find that phosphoinositide (PI) kinase signaling controls a conserved PDK-TORC2-Akt signaling cascade as part of a homeostasis network that allows the endoplasmic reticulum (ER) to modulate essential responses, including Ca2+-regulated lipid biogenesis, upon plasma membrane (PM) stress. Furthermore, loss of ER-PM junctions impairs this protective response, leading to PM integrity defects upon heat stress. Thus PI kinase–mediated ER-PM cross-talk comprises a regulatory system that ensures cellular integrity under membrane stress conditions.

Abstract P404: Membrane Composition Of Cardiac-derived Extracellular Vesicles Changes With Vesicle Origin And Determines Uptake

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Sruti Bheri ◽  
Jessica R Hoffman ◽  
Hyun-Ji Park ◽  
Michael E Davis
Keyword(s):  
Extracellular Vesicles ◽  
Lipid Membrane ◽  
Recipient Cell ◽  
Donor Cell ◽  
Membrane Lipid ◽  
Least Squares Regression ◽  
Membrane Composition ◽  
Cell Type ◽  
Uptake Mechanism ◽  
Donor Cell Type

Introduction: Myocardial infarction (MI) is a leading cause of mortality worldwide. The potency of cell-based therapies for MI is increasingly attributed to the release of extracellular vesicles (EVs) which consist of a lipid/protein membrane and encapsulate RNA cargo. Specifically, EVs from ckit+ progenitor cells (CPCs) and mesenchymal stromal cells (MSCs) are shown to be pro-reparative, with clinical trials ongoing. Despite copious research into EV cargo, the role of donor cell type on EV membrane composition and its effects on EV uptake mechanism by recipient cells remain unclear. This is crucial for designing EV-based therapeutics as uptake mechanism dictates the functionality of the cargo. Thus, we hypothesized that (1) EV membrane composition varies by donor cell type and (2) this variation covaries with the mechanism of uptake. Methods: EVs were isolated using differential ultracentrifugation from four cardiac cell types: CPCs, MSCs, cardiac endothelial cells (CECs) and rat cardiac fibroblasts (RCFs) grown in normoxia (18% O 2 ) or hypoxia (1% O 2 ) to mimic ischemic conditions. EVs were characterized for size and concentration. EV lipid membrane profile was assessed through LC/MS/MS. Donor cell’s role on EV uptake mechanism was determined by inhibiting known uptake pathways (clathrin, dynamin, macropinocytosis and caveolae/lipid raft) with small molecules and quantifying CEC/RCF endocytosis of EVs with flow cytometry. Finally, partial least squares regression was used to determine the most important lipids involved in EV uptake mechanism. Results: EVs were successfully isolated and characterized. The EV membrane lipid profiles clustered by donor cell type. Uptake mechanism of EVs varied based on both donor and recipient cell type with dynamin mediated endocytosis being the most common. Further, the uptake mechanism was independent of normoxic/hypoxic conditioning. Finally, supervised learning methods revealed specific lipid classes (sphingolipids and glycerophospholipids) covaried with EV uptake mechanism. Conclusion: This work highlights the importance of the understudied EV membrane and its role in delivering therapeutic cargo. Active donor cell selection for efficient EV uptake will allow for more potent EV-based MI therapies.

scholarly journals Making connections: control of PI kinase signaling at ER‐PM junctions (351.3)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
Andrew Manford ◽  
Scott Emr ◽  
Christopher Stefan
Keyword(s):  
Kinase Signaling ◽  
Pi Kinase

scholarly journals Occurrence of cross-resistance and β-lactam seesaw effect in glycopeptide-, lipopeptide- and lipoglycopeptide-resistant MRSA correlates with membrane phosphatidylglycerol levels

2020 ◽  
Vol 75 (5) ◽  
pp. 1182-1186 ◽  
Author(s):  
Kelly M Hines ◽  
Tianwei Shen ◽  
Nathaniel K Ashford ◽  
Adam Waalkes ◽  
Kelsi Penewit ◽  
...  
Keyword(s):  
Cell Wall ◽  
Susceptibility Testing ◽  
Membrane Lipid ◽  
Cross Resistance ◽  
Membrane Composition ◽  
Membrane Lipid Composition ◽  
Usa300 Strain ◽  
Associated Proteins ◽  
The Relationship

Abstract Background Glycopeptides (GPs), lipopeptides (LPs) and lipoglycopeptides (LGPs) are related antimicrobials important for the management of invasive MRSA infections. Cross-resistance among these antibiotics in MRSA is well documented, as is the observation that susceptibility of MRSA to β-lactams increases as susceptibility to GPs and LPs decreases (i.e. the seesaw effect). Efforts to understand the relationship between GP/LP/LGP cross-resistance and the seesaw effect have focused on the PBPs, but the role of lipid metabolism has not been investigated. Objectives Since the cell membrane is structurally and metabolically integrated with the cell wall and anchors associated proteins, including PBPs, we examined the relationship between membrane lipid composition and the phenomena of cross-resistance among GPs/LPs/LGPs and the β-lactam seesaw effect. Methods We selected for daptomycin, vancomycin and dalbavancin resistance using the USA300 strain JE2 and evaluated the resulting mutants by WGS, MS-based lipidomics and antimicrobial susceptibility testing to assess the relationship between membrane composition, cross-resistance, and the seesaw effect. Results We observed cross-resistance to GPs/LPs/LGPs among the selected strains and the seesaw effect against various β-lactams, depending on the PBP targets of the particular β-lactam. We found that modification of membrane composition occurs not only in daptomycin-selected strains, but also vancomycin- and dalbavancin-selected strains. Significantly, we observed that the abundance of most phosphatidylglycerols positively correlates with MICs of GPs/LPs/LGPs and negatively correlates with the MICs of β-lactams. Conclusions These studies demonstrate a major association between membrane remodelling, cross-resistance and the seesaw effect.

EPR study of the effect, induced by zidovudine (AZT), on the membrane lipid dynamics in leukemic cell

2002 ◽  
Vol 28 (2-3) ◽  
pp. 239-246 ◽  
Author(s):  
S. Colacicchi ◽  
V. Carnicelli ◽  
A. Di Giulio ◽  
G. Gualtieri
Keyword(s):  
Leukemic Cell ◽  
Membrane Lipid ◽  
Lipid Dynamics

scholarly journals Cholesterol Dependence of Varicella-Zoster Virion Entry into Target Cells

2007 ◽  
Vol 81 (14) ◽  
pp. 7548-7558 ◽  
Author(s):  
S. Hambleton ◽  
S. P. Steinberg ◽  
M. D. Gershon ◽  
A. A. Gershon
Keyword(s):  
Lipid Rafts ◽  
Viral Entry ◽  
Membrane Lipid ◽  
Viral Envelope ◽  
Target Cells ◽  
Cholesterol Depletion ◽  
Dependent Manner ◽  
Membrane Composition ◽  
Focus Formation ◽  
Varicella Zoster

ABSTRACT The entry of inhaled virions into airway cells is presumably the initiating step of varicella-zoster infection. In order to characterize viral entry, we studied the relative roles played by lipid rafts and clathrin-mediated transport. Virus and target cells were pretreated with agents designed to perturb selected aspects of endocytosis and membrane composition, and the effects of these perturbations on infectious focus formation were monitored. Infectivity was exquisitely sensitive to methyl-β-cyclodextrin (MβCD) and nystatin, which disrupt lipid rafts by removing cholesterol. These agents inhibited infection by enveloped, but not cell-associated, varicella-zoster virus (VZV) in a dose-dependent manner and exerted these effects on both target cell and viral membranes. Inhibition by MβCD, which could be reversed by cholesterol replenishment, rapidly declined as a function of time after exposure of target cells to VZV, suggesting that an early step in viral infection requires cholesterol. No effect of cholesterol depletion, however, was seen on viral binding; moreover, there was no reduction in the surface expression or internalization of mannose 6-phosphate receptors, which are required for VZV entry. Viral entry was energy dependent and showed concentration-dependent inhibition by chlorpromazine, which, among other actions, blocks clathrin-mediated endocytosis. These data suggest that both membrane lipid composition and clathrin-mediated transport are critical for VZV entry. Lipid rafts are likely to contribute directly to viral envelope integrity and, in the host membrane, may influence endocytosis, evoke downstream signaling, and/or facilitate membrane fusion.

scholarly journals A combined action of pulmonary surfactant proteins SP-B and SP-C modulates permeability and dynamics of phospholipid membranes

2011 ◽  
Vol 438 (3) ◽  
pp. 555-564 ◽  
Author(s):  
Elisa Parra ◽  
Lara H. Moleiro ◽  
Ivan López-Montero ◽  
Antonio Cruz ◽  
Francisco Monroy ◽  
...  
Keyword(s):  
Pulmonary Surfactant ◽  
External Medium ◽  
Nile Red ◽  
Lipid Vesicles ◽  
Membrane Lipid ◽  
Structure And Dynamics ◽  
Lipid Dynamics ◽  
Combined Action ◽  
Surface Active ◽  
Pulmonary Surfactant Proteins

Proteins SP-B and SP-C are essential to promote formation of surface-active films at the respiratory interface, but their mechanism of action is still under investigation. In the present study we have analysed the effect of the proteins on the accessibility of native, quasi-native and model surfactant membranes to incorporation of the fluorescent probes Nile Red (permeable) and FM 1-43 (impermeable) into membranes. We have also analysed the effect of single or combined proteins on membrane permeation using the soluble fluorescent dye calcein. The fluorescence of FM 1-43 was always higher in membranes containing SP-B and/or SP-C than in protein-depleted membranes, in contrast with Nile Red which was very similar in all of the materials tested. SP-B and SP-C promoted probe partition with markedly different kinetics. On the other hand, physiological proportions of SP-B and SP-C caused giant oligolamellar vesicles to incorporate FM 1-43 from the external medium into apparently most of the membranes instantaneously. In contrast, oligolamellar pure lipid vesicles appeared to be mainly labelled in the outermost membrane layer. Pure lipidic vesicles were impermeable to calcein, whereas it permeated through membranes containing SP-B and/or SP-C. Vesicles containing only SP-B were stable, but prone to vesicle–vesicle interactions, whereas those containing only SP-C were extremely dynamic, undergoing frequent fluctuations and ruptures. Differential structural effects of proteins on vesicles were confirmed by electron microscopy. These results suggest that SP-B and SP-C have different contributions to inter- and intra-membrane lipid dynamics, and that their combined action could provide unique effects to modulate structure and dynamics of pulmonary surfactant membranes and films.

Alterations in Membrane Lipid Dynamics of Leukemic Cells Undergoing Growth Arrest and Differentiation: Dependency on the Inducing Agent

1998 ◽  
Vol 239 (2) ◽  
pp. 442-446 ◽  
Author(s):  
Ilana Nathan ◽  
Itzchack Ben-Valid ◽  
Ruth Henzel ◽  
Husam Masalha ◽  
Stavanit Nemschitz Baram ◽  
...  
Keyword(s):  
Growth Arrest ◽  
Membrane Lipid ◽  
Leukemic Cells ◽  
Lipid Dynamics

scholarly journals Temperature- and Surfactant-Induced Membrane Modifications That Alter Listeria monocytogenes Nisin Sensitivity by Different Mechanisms

2002 ◽  
Vol 68 (12) ◽  
pp. 5904-5910 ◽  
Author(s):  
Jie Li ◽  
Michael L. Chikindas ◽  
Richard D. Ludescher ◽  
Thomas J. Montville
Keyword(s):  
Listeria Monocytogenes ◽  
Membrane Fluidity ◽  
Lipid Composition ◽  
Pore Formation ◽  
Membrane Lipid ◽  
Tween 20 ◽  
Membrane Composition ◽  
Cold Temperatures ◽  
Branched Chain Fatty Acids ◽  
Branched Chain

ABSTRACT Nisin interacts with target membranes in four sequential steps: binding, insertion, aggregation, and pore formation. Alterations in membrane composition might influence any of these steps. We hypothesized that cold temperatures (10°C) and surfactant (0.1% Tween 20) in the growth medium would influence Listeria monocytogenes membrane lipid composition, membrane fluidity, and, as a result, sensitivity to nisin. Compared to the membranes of cells grown at 30°C, those of L. monocytogenes grown at 10°C had increased amounts of shorter, branched-chain fatty acids, increased fluidity (as measured by fluorescence anisotropy), and increased nisin sensitivity. When 0.1% Tween 20 was included in the medium and the cells were cultured at 30°C, there were complex changes in lipid composition. They did not influence membrane fluidity but nonetheless increased nisin sensitivity. Further investigation found that these cells had an increased ability to bind radioactively labeled nisin. This suggests that the modification of the surfactant-adapted cell membrane increased nisin sensitivity at the binding step and demonstrates that each of the four steps can contribute to nisin sensitivity.

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