Effects of different detachment procedures on viability, nitroxide reduction kinetics and plasma membrane heterogeneity of V-79 cells

Plasma membrane heterogeneity is implicit in the existence of specialized cell surface organelles which are necessary for cellular function; coated pits, post and pre-synaptic terminals, microvillae, caveolae, tight junctions, focal contacts and endothelial polarization are examples. The persistence of these discrete molecular aggregates depends on localized restraint of the constituent molecules within specific domaines in the cell surface by strong intermolecular bonds and/or anchorage to extended cytoskeleton. The observed plasticity of many of organelles and the dynamical modulation of domaines induced by cellular signaling evidence evanescent intermolecular interactions even in conspicuous aggregates. There is also strong evidence that universal restraints on the mobility of cell surface proteins persist virtually everywhere in cell surfaces, not only in the discrete organelles. Diffusion of cell surface proteins is slowed by several orders of magnitude relative to corresponding protein diffusion coefficients in isolated lipid membranes as has been determined by various ensemble average methods of measurement such as fluorescence photobleaching recovery(FPR).

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Stabilizing membrane domains antagonizes n-alcohol anesthesia

10.1101/057257 ◽

2016 ◽

Author(s):

B.B. Machta ◽

E. Grey ◽

M. Nouri ◽

N.L.C. McCarthy ◽

E.M. Gray ◽

...

Keyword(s):

Plasma Membrane ◽

Phase Separation ◽

Critical Temperature ◽

Hydrostatic Pressure ◽

General Anesthesia ◽

Membrane Domains ◽

Strongly Correlated ◽

Membrane Heterogeneity ◽

Anesthetic Potency ◽

Better Than

AbstractDiverse molecules induce general anesthesia with potency strongly correlated both with their hydrophobicity and their effects on certain ion channels. We recently observed that several n-alcohol anesthetics inhibit heterogeneity in plasma membrane derived vesicles by lowering the critical temperature (Tc) for phase separation. Here we exploit conditions that stabilize membrane heterogeneity to further test the correlation between the anesthetic potency of n-alcohols and effects on Tc. First we show that hexadecanol acts oppositely to n-alcohol anesthetics on membrane mixing and antagonizes ethanol induced anesthesia in a tadpole behavioral assay. Second, we show that two previously described ‘intoxication reversers’ raise Tc and counter ethanol’s effects in vesicles, mimicking the findings of previous electrophysiological and behavioral measurements. Third, we find that hydrostatic pressure, long known to reverse anesthesia, also raises Tc in vesicles with a magnitude that counters the effect of butanol at relevant concentrations and pressures. Taken together,these results demonstrate that ΔTc predicts anesthetic potency for n-alcohols better than hydrophobicity in a range of contexts, supporting a mechanistic role for membrane heterogeneity in general anesthesia.

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Membrane Heterogeneity Beyond the Plasma Membrane

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.580814 ◽

2020 ◽

Vol 8 ◽

Author(s):

Hong-Yin Wang ◽

Deepti Bharti ◽

Ilya Levental

Keyword(s):

Plasma Membrane ◽

Membrane Heterogeneity

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A study of the Interaction Between Cetirizine and Plasma Membrane of Eosinophils, Neutrophils, Platelets and Lymphocytes using A fluorescence Technique

Mediators of Inflammation ◽

10.1155/s0962935194000335 ◽

1994 ◽

Vol 3 (3) ◽

pp. 229-234 ◽

Cited By ~ 11

Author(s):

A. Kantar ◽

N. Oggiano ◽

P. L. Giorgi ◽

J-P. Rihoux

Keyword(s):

Plasma Membrane ◽

Membrane Fluidity ◽

Fluorescence Anisotropy ◽

Inflammatory Cell ◽

Fluorescence Decay ◽

Fluorescence Technique ◽

Membrane Heterogeneity ◽

Plasma Membrane Fluidity ◽

Steady State Fluorescence ◽

Induced Changes

The effect of cetirizine on plasma membrane fluidity and heterogeneity of human eosinophils, neutrophils, platelets and lymphocytes was investigated using a fluorescence technique. Membrane fluidity and heterogeneity were studied by measuring the steady-state fluorescence anisotropy and fluorescence decay of 1-(4- trimethylammonium-phenyl)-6-phenyl-1, 3, 5-hexatriene (TMA-DPH) incorporated in the membrane. The results demonstrate that cetirizine (1 μg/ml) induced a significant increase in the Hpid order in the exterior part of the membrane and a decrease in membrane heterogeneity in eosinophils, neutrophils and platelets. Moreover, cetirizine blocked the PAF induced changes in membrane fluidity in these cells. Cetirizine did not influence significantly the plasma membrane of lymphocytes. These data may partially explain the effect ofcetirizine on inflammatory cell activities.

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Direct quantification of ligand-induced lipid and protein microdomains with distinctive signaling properties

10.1101/2021.09.28.462247 ◽

2021 ◽

Author(s):

Daniel Wirth ◽

Michael Paul ◽

Elena B Pasquale ◽

Kalina Hristova

Keyword(s):

Plasma Membrane ◽

Lipid Rafts ◽

Receptor Tyrosine Kinase ◽

Mammalian Cells ◽

Dissociation Constants ◽

Live Cells ◽

Downstream Effector ◽

Plasma Membrane Heterogeneity ◽

Signaling Components ◽

Insight Into

Lipid rafts are known as highly ordered lipid domains that are enriched in saturated lipids such as the ganglioside GM1. While lipid rafts are believed to exist in cells and to serve as signaling platforms through their enrichment in signaling components, they have never been directly observed in the plasma membrane without treatments that artificially cluster GM1 into large lattices. Here we report that microscopic GM1-enriched domains can form, without lipid crosslinking, in the plasma membrane of live mammalian cells expressing the EphA2 receptor tyrosine kinase in response to its ligand ephrinA1-Fc. The GM1-enriched microdomains form concomitantly with EphA2-enriched microdomains, but only partially co-localize with them. To gain insight into how plasma membrane heterogeneity controls signaling, we quantify the degree of EphA2 segregation and study initial EphA2 signaling steps in both EphA2-enriched and EphA2-depleted domains. By measuring dissociation constants, we demonstrate that EphA2 oligomerization is the same in EphA2-enriched and -depleted domains. However, EphA2 interacts preferentially with its downstream effector SRC in EphA2-depleted domains. The ability to induce microscopic GM1-enriched domains in live cells using a ligand for a transmembrane receptor will give us unprecedented opportunities to study the biology of lipid rafts.

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