Fluorescent sterols as tools in membrane biophysics and cell biology

Wüstner, Daniel

doi:10.1016/j.chemphyslip.2006.12.004

Cited by 130 publications

(138 citation statements)

References 149 publications

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“…However, it is well established that probes designed as cholesterol mimics usually do not satisfactorily reproduce the properties of pure cholesterol. 75,76 Small changes to the structure of cholesterol can have a significant influence on the properties, composition, and location in phase space of coexisting lipid domains, as has been demonstrated by experiments where cholesterol is replaced by structurally similar sterols as the third major constituent of ternary GUVs. 77,78 Indeed, we are aware of four different fluorescently labeled cholesterol molecules whose partitioning between coexisting liquid phases has been investigated: three of these modified cholesterols preferentially segregated into L R domains, while the fourth enriched in the L o phase.…”

Section: Resultsmentioning

confidence: 98%

Partitioning of Membrane-Anchored DNA between Coexisting Lipid Phases

Beales

Vanderlick

2009

J. Phys. Chem. B

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The partitioning of different cholesterol-modified single-stranded DNA molecules (chol-DNAs) between the domains of phase-separated lipid vesicles is investigated by laser-scanning confocal fluorescence microscopy. All chol-DNAs studied preferentially localized into the fluid phase of giant vesicles in liquid-solid phase coexistence (1:1 DLPC:DPPC, 1:1 DLPC:DMPE). Partitioning behavior of chol-DNAs into liquid-liquid phase-separated vesicles (DOPC/DPPC/cholesterol) was found to be less straightforward. Single-cholesterolanchored DNA molecules partitioned roughly equally between coexisting domains, whereas chol-DNAs with two cholesterol anchors were seen to be enriched in the liquid-ordered domains with apparent surface concentrations up to double that of the liquid-disordered phase. Quantitative analysis of the fluorescence intensity of DNA between the two phases also revealed a weaker dependence of the apparent partitioning on the initial lipid composition of the vesicles. We rationalize these observations by proposing a simple partitioning model based on the conformational entropy of insertion of a cholesterol anchor into each phase.

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Section: Resultsmentioning

confidence: 98%

Partitioning of Membrane-Anchored DNA between Coexisting Lipid Phases

Beales

Vanderlick

2009

J. Phys. Chem. B

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“…Since cholesterol itself has very few structural/chemical features suitable for UV/VIS or optical imaging, the advent of DHE with many properties mimicking or very similar to those of cholesterol, has proven to be a major asset for probing/elucidating real-time sterol dynamics by video and MPLSM imaging in living cells. For additional insights, the reader is referred to earlier reviews on DHE, synthetic fluorescent sterols, spin labeled sterols, photoreactive sterols, and chemical tags of cholesterol (65)(66)(67)(68).…”

Section: Advent Of Fluorescent Sterolsmentioning

confidence: 99%

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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“…As membranas de organelas subcelulares tais como mitocôndrias e núcleos raramente contêm colesterol (Halliwel e Gutteridge, 1999). O colesterol desempenha um papel fundamental em muitos processos biológicos tais como: permeabilidade da membrana, organização lateral de lipídios, transdução de sinais e passagem de substâncias através da membrana (Wustner, 2007). Quanto maior a quantidade de esteróis menor é a fluidez da membrana (facilidade de movimento e representa os valores recíprocos de viscosidade da membrana (Tsuda e Nishio, 2003)), devido à presença do núcleo rígido do anel esteróide, o qual diminui a liberdade de rotação das ligações carbono-carbono (Murray e Granner, 2002).…”

Section: Estrutura Da Membrana Plasmáticaunclassified

Efeitos de pesticidas sobre a fragilidade osmótica de eritrócitos – Uma breve revisão

et al. 2009

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ResumoApesar da sua aplicação em outros setores, a agricultura tem sido a maior fonte de contaminação ambiental por praguicidas. Alguns praguicidas e seus metabólitos têm sido encontrados como poluentes no fundo e superfície de águas, no solo, e na atmosfera e são prováveis responsáveis pela perda da biodiversidade e a deterioração de hábitats naturais. Dentre os herbicidas, o Roundup® (Brasil) é o mais comum. Estudos recentes têm demonstrado que o glifosato, o pesticida mais utilizado na agricultura e considerado de baixo risco pelo EPA-US gera fragilidade osmótica de eritrócitos humanos e de ratos dentro das concentrações indicadas pelos fabricantes. As características da intoxicação por esse praguicida podem ser explicadas pela hipóxia causada pela hemólise dos eritrócitos. Os pesticidas podem estar associados com a aquisição de demências, com o aumento da população de idosos no país, o contato tempo-dependente dos indivíduos com substâncias nocivas aumentam e putativamente, o aumento de demências provocadas por fatores exógenos tende a aumentar também, desse modo a contaminação do ambiente por pesticidas e as doenças assim derivadas devem ser consideradas como um problema de saúde publica. Unitermos: praguicidas, membrana, fragilidade osmótica AbstractEffects of pesticides on the osmotic fragility of erythrocytes -A brief review. Despite their applications in other fields, agriculture is the main source of environmental contamination by pesticides. Pesticides and their metabolites have been found in the oceans, soil and atmosphere, and are probably responsible for the loss of biodiversity and deterioration of the natural environment. Roundup® is the pesticide most used in Brazil. Recents studies have demonstrated that ghyphosate (the main ingredient of Roundup®), while considered to be of low risk, generates osmotic fragility at the concentrations recommended by the manufactures. The problems caused by this pesticide can be explained by hypoxia caused by hemolysis of erythrocytes. Such pesticides can be Revisão

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Fluorescent sterols as tools in membrane biophysics and cell biology

Cited by 130 publications

References 149 publications

Partitioning of Membrane-Anchored DNA between Coexisting Lipid Phases

Partitioning of Membrane-Anchored DNA between Coexisting Lipid Phases

Fluorescence Techniques Using Dehydroergosterol to Study Cholesterol Trafficking

Efeitos de pesticidas sobre a fragilidade osmótica de eritrócitos – Uma breve revisão

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