Asymmetric distribution of a fluorescent sterol in synaptic plasma membranes: effects of chronic ethanol consumption

Wood, W. Gibson; Schroeder, Friedhelm; Hogy, Lora; Rao, A. Muralikrishna; Nemecz, Gyorgy

doi:10.1016/0005-2736(90)90103-u

Cited by 86 publications

(86 citation statements)

References 19 publications

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“…The transbilayer migration rate of DHE in model membranes and plasma membranes is relatively fast, t 1/2 of sec-min depending on the membrane examined (rev. in (12,108,144,145). Rapid transbilayer migration of DHE is also supported by the finding that uptake of DHE into and non-vesicular transport across cultured hepatocyte-derived cells (i.e.…”

Section: Dhe Architecture In Purified Biological Membranesmentioning

confidence: 76%

Section: Dhe Architecture In Purified Biological Membranesmentioning

confidence: 99%

“…in (12,144,145). DHE revealed that the cytofacial leaflet of plasma membranes from L-cell fibroblasts (12,24,146,147), erythrocytes (144), and brain synaptosomes (145,(148)(149)(150)(151). While other methods (filipin staining, exchange, cholesterol oxidase accessibility, neutron diffraction, etc) have also been used to measure transbilayer cholesterol distribution, many have significant limitations including accessibility of membrane cholesterol (filipin, cholesterol oxidase), production of a potential perturbant (cholesterol oxidase produces cholesterone), and poor dynamic resolution (neutron diffraction) (rev.…”

Section: Dhe Architecture In Purified Biological Membranesmentioning

confidence: 99%

“…While measurements of transbilayer sterol distribution by different methods may therefore not necessarily agree, multiple methods (DHE, NBD-cholesterol quenching, and exchange assays) indicate that the cytofacial leaflet of erythrocytes has more cholesterol than the exofacial leaflet (144,152). Likewise, several methods (DHE, cholesterol oxidase) indicate that the synaptosomal plasma membrane has more cholesterol in the cytofacial leaflet than the exofacial leaflet (12,145,(148)(149)(150). The transbilayer distribution of sterol is a major determinant of the transbilayer fluidity gradient present in these membranes, the cytofacial cholesterol-rich leaflet is more rigid (less fluid) than the relatively cholesterol-poor exofacial leaflet (rev.…”

Section: Dhe Architecture In Purified Biological Membranesmentioning

confidence: 99%

“…The finding of rapid transbilayer sterol movement suggested that the asymmetric transbilayer distribution in the plasma membrane was not due to restricted movement of cholesterol from one leaflet to the other, but was instead a property of the lipid bilayer itself. DHE transbilayer distribution has broad applicability in studies of the action of anesthetics, cholesterol lowering drugs (statins), alcohol (chronic and acute), lupus erythematosus, aging, apoE, and sterol carrier proteins all of which can alter plasma membrane or synaptosomal plasma membrane transbilayer sterol distribution and/or transbilayer fluidity (26,135,136,145,149,150,154,(161)(162)(163)(164)(165)(166)(167)(168)(169)(170)(171)(172).Second, the DHE lateral distribution in both model and biological membranes was not uniform, but instead reflected sterol-rich and poor domains (rev. in (54,55).…”

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confidence: 99%

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Fluorescence Techniques Using Dehydroergosterol to Study Cholesterol Trafficking

McIntosh

Atshaves

Huang

et al. 2008

Lipids

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Cholesterol itself has very few structural/chemical features suitable for real-time imaging in living cells. Thus, the advent of dehydroergosterol [ergosta-5,7,9(11),22-tetraen-3β-ol, DHE] the fluorescent sterol most structurally and functionally similar to cholesterol to date, has proven to be a major asset for real-time probing/elucidating the sterol environment and intracellular sterol trafficking in living organisms. DHE is a naturally-occurring, fluorescent sterol analog that faithfully mimics many of the properties of cholesterol. Because these properties are very sensitive to sterol structure and degradation, such studies require the use of extremely pure (>98%) quantities of fluorescent sterol. DHE is readily bound by cholesterol-binding proteins, is incorporated into lipoproteins (from the diet of animals or by exchange in vitro), and for real-time imaging studies is easily incorporated into cultured cells where it co-distributes with endogenous sterol. Incorporation from an ethanolic stock solution to cell culture media is effective, but this process forms an aqueous dispersion of dehydroergosterol crystals which can result in endocytic cellular uptake and distribution into lysosomes which is problematic in imaging DHE at the plasma membrane of living cells. In contrast, monomeric DHE can be incorporated from unilamellar vesicles by exchange/fusion with the plasma membrane or from DHE-methyl-β-cyclodextrin (DHE-MβCD) complexes by exchange with the plasma membrane. Both of the latter techniques can deliver large quantities of monomeric dehydroergosterol with significant distribution into the plasma membrane. The properties and behavior of DHE in protein-binding, lipoproteins, model membranes, biological membranes, lipid rafts/caveolae, and real-time imaging in living cells indicate that this naturally-occurring fluorescent sterol is a useful mimic for probing the properties of cholesterol in these systems. Keywordsdehydroergosterol; cholesterol; ergosterol; fluorescent sterols; microscopy Historical PerspectiveIn order to resolve the dynamics and factors governing cholesterol trafficking within cells, it is important to recognize that the cholesterol molecule has very few polar constituents (Fig. 1A). Consequently, cholesterol is poorly soluble in aqueous environments such as cytosol as evidenced by critical micellar concentrations of cholesterol and other sterols being very low, *To whom correspondence should be addressed: Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 862-1433, FAX: (979) NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript near 20-30 nM (1-5). The physiological impact of cholesterol's low aqueous solubility is that spontaneous cholesterol desorption from the cytofacial leaflet of the plasma membrane or lysosomal membrane into the cytosol for transfer to intracellular sites for esterification, oxidation, or secretion is extremely slow (t 1/2 3 hours-days) (6-9). Therefore, it is important to resolve factors...

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Section: Dhe Architecture In Purified Biological Membranesmentioning

confidence: 76%