Electron Spin Resonance Characterization of Liquid Ordered Phase of Detergent-Resistant Membranes from RBL-2H3 Cells

Ge, Mingtao; Field, Kenneth A.; Aneja, R.; Holowka, David; Baird, Barbara; Freed, Jack H.

doi:10.1016/s0006-3495(99)76943-2

Cited by 119 publications

(131 citation statements)

References 53 publications

(72 reference statements)

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“…This value is slightly lower than the order parameter obtained for 5-PC (0.42) in plasma membrane vesicles derived from the RBL-2H3 mast cells at 23°C , 51 and significantly lower than the order parameter of 5-PC in sphingomyelin model membranes at 20°C in the gel phase (0.46) and in detergent-resistant membranes at 22°C (0.52). 51,53 Interestingly, the order parameter of 5-PC in native hippocampal membranes is comparable to the order parameter of 0.38 obtained for the same spin label in the liquid-ordered component of live RBL-2H3 cells at 25°C. 48 This is in agreement with our previous results on native hippocampal membranes using fluorescence approaches.…”

Section: ■ Results and Discussionsupporting

confidence: 68%

Organization and Dynamics of Hippocampal Membranes in a Depth-Dependent Manner: An Electron Spin Resonance Study

Singh

Tarafdar²,

Swamy³

et al. 2012

J. Phys. Chem. B

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Organization and dynamics of neuronal membranes represent crucial determinants for the function of neuronal receptors and signal transduction. Previous work from our laboratory has established hippocampal membranes as a convenient natural source for studying neuronal receptors. In this work, we have monitored the organization and dynamics of hippocampal membranes and their modulation by cholesterol and protein content utilizing location (depth)-specific spin-labeled phospholipids by ESR spectroscopy. The choice of ESR spectroscopy is appropriate due to slow diffusion encountered in crowded environments of neuronal membranes. Analysis of ESR spectra shows that cholesterol increases hippocampal membrane order while membrane proteins increase lipid dynamics resulting in disordered membranes. These results are relevant in understanding the complex organization and dynamics of hippocampal membranes. Our results are significant in the overall context of membrane organization under low cholesterol conditions and could have implications in neuronal diseases characterized by low cholesterol conditions due to defective cholesterol metabolism. ■ INTRODUCTIONBiological membranes are complex noncovalent assemblies of a diverse variety of lipids and proteins that allow cellular compartmentalization, thereby imparting an identity to the cell. The lipid composition of cells that makes up the nervous system is unique and has been correlated with increased complexity in the organization of the nervous system during evolution.1 The nervous system characteristically contains a very high concentration of lipids and displays remarkable lipid diversity.2 Cholesterol is an important lipid in this context since it is known to regulate the function of neuronal receptors, 3−5 thereby affecting neurotransmission and giving rise to mood and anxiety disorders. 6 Cholesterol is often found distributed nonrandomly in domains in biological and model membranes.7−9 Many of these domains (sometimes termed as 'lipid rafts' 10 ) are thought to be important for the maintenance of membrane structure and function, although characterizing the spatiotemporal resolution of these domains has proven to be challenging. 11−13 A unique property of cholesterol that contributes to its capacity to form membrane domains is its ability to form a liquid-ordered-like phase in higher eukaryotic plasma membranes.14 The idea of such specialized membrane domains assumes significance in cell biology since physiologically important functions such as membrane sorting and trafficking, signal transduction processes, and the entry of pathogens have been attributed to these domains. 15,16 Interestingly, a number of neurological diseases share a common etiology of defective cholesterol metabolism in the brain, 17 yet the organization and dynamics of neuronal membranes as a consequence of alterations in membrane cholesterol is poorly understood. 18−20Previous work from our laboratory has established native hippocampal membranes as a convenient natural source for expl...

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Section: ■ Results and Discussionsupporting

confidence: 68%

Organization and Dynamics of Hippocampal Membranes in a Depth-Dependent Manner: An Electron Spin Resonance Study

Singh

Tarafdar²,

Swamy³

et al. 2012

J. Phys. Chem. B

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“…As the cholesterol content is increased to a FC: phospholipid molar ratio of 0.33, the order parameter S 0 increases significantly. The S 0 of 16-doxyl-PC in ER membranes loaded with these high levels of cholesterol is close to the S 0 of 16-doxyl-PC in the liquid-ordered phase of lipid bilayers consist- ing of dipalmitoyl phosphatidylcholine (DPPC) and cholesterol at a molar ratio of 1:1, which is 0.22 at 25-35°C (49). The S 0 values are also similar to those obtained in detergent-resistant membranes from rat basophilic leukemia (RBL) cells, which is 0.20 at 37°C (49).…”

Section: Discussionmentioning

confidence: 59%

“…The S 0 of 16-doxyl-PC in ER membranes loaded with these high levels of cholesterol is close to the S 0 of 16-doxyl-PC in the liquid-ordered phase of lipid bilayers consist- ing of dipalmitoyl phosphatidylcholine (DPPC) and cholesterol at a molar ratio of 1:1, which is 0.22 at 25-35°C (49). The S 0 values are also similar to those obtained in detergent-resistant membranes from rat basophilic leukemia (RBL) cells, which is 0.20 at 37°C (49). These changes in the order parameter indicate that the ER membrane undergoes a significant extent of ordering with FC enrichment, with its properties becoming similar to liquid-ordered membranes.…”

Section: Discussionmentioning

confidence: 59%

Enrichment of Endoplasmic Reticulum with Cholesterol Inhibits Sarcoplasmic-Endoplasmic Reticulum Calcium ATPase-2b Activity in Parallel with Increased Order of Membrane Lipids

Li¹,

Ciani

et al. 2004

Journal of Biological Chemistry

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258

219

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Macrophages in advanced atherosclerotic lesions accumulate large amounts of unesterified, or "free," cholesterol (FC). FC accumulation induces macrophage apoptosis, which likely contributes to plaque destabilization. Apoptosis is triggered by the enrichment of the endoplasmic reticulum (ER) with FC, resulting in depletion of ER calcium stores, and induction of the unfolded protein response. To explain the mechanism of ER calcium depletion, we hypothesized that FC enrichment of the normally cholesterol-poor ER membrane inhibits the macrophage ER calcium pump, sarcoplasmic-endoplasmic reticulum calcium ATPase-2b (SERCA2b). FC enrichment of ER membranes to a level similar to that occuring in vivo inhibited both the ATPase activity and calcium sequestration function of SERCA2b. Enrichment of ER with ent-cholesterol or 14:0 -18:0 phosphatidylcholine, which possess the membrane-ordering properties of cholesterol, also inhibited SERCA2b. Moreover, at various levels of FC enrichment of ER membranes, there was a very close correlation between increasing membrane lipid order, as monitored by 16-doxyl-phosphatidycholine electron spin resonance, and SERCA2b inhibition. In view of these data, we speculate that SERCA2b, a conformationally active protein with 11 membrane-spanning regions, loses function due to decreased conformational freedom in FC-ordered membranes. This biophysical model may underlie the critical connection between excess cholesterol, unfolded protein response induction, macrophage death, and plaque destabilization in advanced atherosclerosis.

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“…In addition to caveolin, caveolae are characterized by being highly enriched in cholesterol, sphingomyelin, and glycosphingolipids (70,184; also reviewed in Ref. 27).…”

Section: Lpp In Signaling Platformsmentioning

confidence: 99%

Pulmonary phosphatidic acid phosphatase and lipid phosphate phosphohydrolase

Nanjundan

Possmayer

2003

American Journal of Physiology-Lung Cellular and Molecular Phys

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The lung contains two distinct forms of phosphatidic acid phosphatase (PAP). PAP1 is a cytosolic enzyme that is activated through fatty acid-induced translocation to the endoplasmic reticulum, where it converts phosphatidic acid (PA) to diacylglycerol (DAG) for the biosynthesis of phospholipids and neutral lipids. PAP1 is Mg2+ dependent and sulfhydryl reagent sensitive. PAP2 is a six-transmembrane-domain integral protein localized to the plasma membrane. Because PAP2 degrades sphingosine-1-phosphate (S1P) and ceramide-1-phosphate in addition to PA and lyso-PA, it has been renamed lipid phosphate phosphohydrolase (LPP). LPP is Mg2+independent and sulfhydryl reagent insensitive. This review describes LPP isoforms found in the lung and their location in signaling platforms (rafts/caveolae). Pulmonary LPPs likely function in the phospholipase D pathway, thereby controlling surfactant secretion. Through lowering the levels of lyso-PA and S1P, which serve as agonists for endothelial differentiation gene receptors, LPPs regulate cell division, differentiation, apoptosis, and mobility. LPP activity could also influence transdifferentiation of alveolar type II to type I cells. It is considered likely that these lipid phosphohydrolases have critical roles in lung morphogenesis and in acute lung injury and repair.

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Electron Spin Resonance Characterization of Liquid Ordered Phase of Detergent-Resistant Membranes from RBL-2H3 Cells

Cited by 119 publications

References 53 publications

Organization and Dynamics of Hippocampal Membranes in a Depth-Dependent Manner: An Electron Spin Resonance Study

Organization and Dynamics of Hippocampal Membranes in a Depth-Dependent Manner: An Electron Spin Resonance Study

Enrichment of Endoplasmic Reticulum with Cholesterol Inhibits Sarcoplasmic-Endoplasmic Reticulum Calcium ATPase-2b Activity in Parallel with Increased Order of Membrane Lipids

Pulmonary phosphatidic acid phosphatase and lipid phosphate phosphohydrolase

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