Effects of cholesterol on sodium-potassium ATPase ATP hydrolyzing activity in bovine kidney

Yèagle, Philip L.; Young, Justin G.; Rice, D.W.

doi:10.1021/bi00417a037

Cited by 158 publications

(101 citation statements)

References 19 publications

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“…Prior treatment of the apical membrane with nystatin removed any rate limitation associated with Na ϩ entry into the cell, thus demonstrating the inhibition was most likely due to cholesterol-mediated effects on the Na ϩ pump. Cholesterol has also been shown to be critical for Na-K-ATPase activity in other cell types including renal cells (34). To verify that the effect was indeed localized to the ATPase on the basal membrane we performed a similar experiment in which we pretreated cells apically or basally with m-CD then permeabilized the apical membrane with nystatin and subsequently quantitated the amount of ouabain inhibitable current remaining.…”

Section: Resultsmentioning

confidence: 99%

The Epithelial Sodium Channel (ENaC) Traffics to Apical Membrane in Lipid Rafts in Mouse Cortical Collecting Duct Cells

Hill

Butterworth

Wang

et al. 2007

Journal of Biological Chemistry

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We previously showed that ENaC is present in lipid rafts in A6 cells, a Xenopus kidney cell line. We now demonstrate that ENaC can be detected in lipid rafts in mouse cortical collecting duct ( MPK CCD 14 ) cells by detergent insolubility, buoyancy on density gradients using two distinct approaches, and colocalization with caveolin 1. Less than 30% of ENaC subunits were found in raft fractions. The channel subunits also colocalized on sucrose gradients with known vesicle targeting and fusion proteins syntaxin 1A, Vamp 2, and SNAP23. Hormonal stimulation of ENaC activity by either forskolin or aldosterone, short or long term, did not alter the lipid raft distribution of ENaC. Methyl-␤-cyclodextrin added apically to MPK CCD 14 cells resulted in a slow decline in amiloride-sensitive sodium transport with short circuit current reductions of 38.1 ؎ 9.6% after 60 min. The slow decline in ENaC activity in response to apical cyclodextrin was identical to the rate of decline seen when protein synthesis was inhibited by cycloheximide. Apical biotinylation of MPK CCD 14 cells confirmed the loss of ENaC at the cell surface following cyclodextrin treatment. Acute stimulation of the recycling pool of ENaC was unaffected by apical cyclodextrin application. Expression of dominant negative caveolin isoforms (CAV1-eGFP and CAV3-DGV) which disrupt caveolae, reduced basal ENaC currents by 72.3 and 78.2%, respectively; but, as with cyclodextrin, the acute response to forskolin was unaffected. We conclude that ENaC is present in and regulated by lipid rafts. The data are consistent with a model in which rafts mediate the constitutive apical delivery of ENaC.

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Section: Resultsmentioning

confidence: 99%

The Epithelial Sodium Channel (ENaC) Traffics to Apical Membrane in Lipid Rafts in Mouse Cortical Collecting Duct Cells

Hill

Butterworth

Wang

et al. 2007

Journal of Biological Chemistry

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“…Numerous studies have shown that cholesterol affects the behavior of membrane inserted helices and the function of many membrane-associated proteins directly or by means of its effect on the physical properties of the phospholipid bilayer, i.e., bilayer hydrophobic thickness and material moduli (35)(36)(37)(38)(39)(40)(41)(42). For example, cholesterol can stabilize ␣-helices in membrane proteins (43,44); it also affects the function of many membrane proteins (36,39,(45)(46)(47)(48) and can alter ion channel gating (49-51).…”

Section: Quantitative Measurements Of Peptide Association In Phospholmentioning

confidence: 99%

Use of thiol-disulfide equilibria to measure the energetics of assembly of transmembrane helices in phospholipid bilayers

Cristian

Lear²,

DeGrado³

2003

Proc. Natl. Acad. Sci. U.S.A.

142

185

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Despite significant efforts and promising progress, the understanding of membrane protein folding lags behind that of soluble proteins. Insights into the energetics of membrane protein folding have been gained from biophysical studies in membrane-mimicking environments (primarily detergent micelles). However, the development of techniques for studying the thermodynamics of folding in phospholipid bilayers remains a considerable challenge. We had previously used thiol-disulfide exchange to study the thermodynamics of association of transmembrane ␣-helices in detergent micelles; here, we extend this methodology to phospholipid bilayers. The system for this study is the homotetrameric M2 proton channel protein from the influenza A virus. Transmembrane peptides from this protein specifically self-assemble into tetramers that retain the ability to bind to the drug amantadine. Thiol-disulfide exchange under equilibrium conditions was used to quantitatively measure the thermodynamics of this folding interaction in phospholipid bilayers. The effects of phospholipid acyl chain length and cholesterol on the peptide association were investigated. The association of the helices strongly depends on the thickness of the bilayer and cholesterol levels present in the phospholipid bilayer. The most favorable folding occurred when there was a good match between the width of the apolar region of the bilayer and the hydrophobic length of the transmembrane helix. Physiologically relevant variations in the cholesterol level are sufficient to strongly influence the association. Evaluation of the energetics of peptide association in the presence and absence of cholesterol showed a significantly tighter association upon inclusion of cholesterol in the lipid bilayers.

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“…These effects of cholesterol enrichment on the activity of membrane proteins have been observed in erythrocytes, 52 vascular cells, 53 and renal cells. 54 In vascular SMCs obtained from atherosclerotic plaque, calcium transport mechanisms and basal intracellular calcium levels are disrupted as a result of increased membrane cholesterol content. 55 These changes have important consequences for atherosclerosis, as calcium participates directly in signal transduction pathways that promote SMC proliferation and migration, among other changes.…”

Section: Alterations In Vascular Cell Membrane Function Due To Cholesmentioning

confidence: 99%

Effects of HMG-CoA Reductase Inhibitors on Endothelial Function

2004

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Abstract-Certain pleiotropic activities reported for 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are related to reductions in cellular cholesterol biosynthesis and isoprenoid levels. In endothelial cells, these metabolic changes contribute to favorable effects on nitric oxide (NO) bioavailability. Given the essential role of NO in preserving vascular structure and function, this effect of statins is of considerable therapeutic importance. Statins have been demonstrated to restore endothelial NO production by several mechanisms, including upregulating endothelial NO synthase (eNOS) protein expression and blocking formation of reactive oxygen species. In this article, we will discuss additional ways in which statins restore endothelial NO production and improve endothelial function.(1) Statins modulate membrane microdomain formation, resulting in reduced expression of proteins that specifically inhibit eNOS activation. (2) Statins reduce sterol biosynthesis, thus interfering with the formation of pathologic microdomains, including cholesterol crystalline structures. This observation has important implications for plaque stabilization, as these microdomains contribute to cholesterol crystal formation and endothelial apoptosis. Finally, (3) statins improve endothelial function by interfering with oxidative stress pathways through both enzymatic and nonenzymatic mechanisms. The relationships between membrane microdomains, cholesterol biosynthesis, and endothelial function will be discussed.

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Effects of cholesterol on sodium-potassium ATPase ATP hydrolyzing activity in bovine kidney

Cited by 158 publications

References 19 publications

The Epithelial Sodium Channel (ENaC) Traffics to Apical Membrane in Lipid Rafts in Mouse Cortical Collecting Duct Cells

The Epithelial Sodium Channel (ENaC) Traffics to Apical Membrane in Lipid Rafts in Mouse Cortical Collecting Duct Cells

Use of thiol-disulfide equilibria to measure the energetics of assembly of transmembrane helices in phospholipid bilayers

Effects of HMG-CoA Reductase Inhibitors on Endothelial Function

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