Effects of Cholesterol and Saturated Sphingolipids on Acyl Chain Order in 1-Palmitoyl-2-oleoyl-<i>sn</i>-glycero-3-phosphocholine Bilayers—A Comparative Study with Phase-Selective Fluorophores

Engberg, Oskar; Nurmi, Henrik; Nyholm, Thomas K.M.; Slotte, J. Peter

doi:10.1021/acs.langmuir.5b00403

Cited by 20 publications

(24 citation statements)

References 51 publications

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“…The measurements were conducted at 37 C, a temperature at the end of the native surfactant phase transition (2), where surfactant membranes are extremely dynamic. DPH-PC partitions preferentially into Ld phases (27), where both SP-B and SP-C are also preferentially located, whereas CTL would likely be distributed into Lo domains. It is expected that a nonselective perturbation of the membrane by the proteins would affect both probes with a similar magnitude, and therefore the changes observed for CTL anisotropy could be mirrored by the effects on DPH-PC.…”

Section: Ctl Partitioning Between Mbcd and Ls-derived Membranesmentioning

confidence: 99%

Effect of Lung Surfactant Protein SP-C and SP-C-Promoted Membrane Fragmentation on Cholesterol Dynamics

Roldán

Nyholm

Slotte

et al. 2016

Biophysical Journal

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To allow breathing and prevent alveolar collapse, lung surfactant (LS) develops a complex membranous system at the respiratory surface. LS is defined by a specific protein and lipid composition, including saturated and unsaturated phospholipid species and cholesterol. Surfactant protein C (SP-C) has been suggested to be an essential element for sustaining the presence of cholesterol in surfactant without functional impairment. In this work, we used a fluorescent sterol-partitioning assay to assess the effect of the surfactant proteins SP-B and SP-C on cholesterol distribution in membranes. Our results suggest that in the LS context, the combined action of SP-B and SP-C appears to facilitate cholesterol dynamics, whereas SP-C does not seem to establish a direct interaction with cholesterol that could increase the partition of free cholesterol into membranes. Interestingly, SP-C exhibits a membrane-fragmentation behavior, leading to the conversion of large unilamellar vesicles into highly curved vesicles ∼25 nm in diameter. Sterol partition was observed to be sensitive to the bending of bilayers, indicating that the effect of SP-C to mobilize cholesterol could be indirectly associated with SP-C-mediated membrane remodeling. Our results suggest a potential role for SP-C in generating small surfactant structures that may participate in cholesterol mobilization and pulmonary surfactant homeostasis at the alveolar interfaces.

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Section: Ctl Partitioning Between Mbcd and Ls-derived Membranesmentioning

confidence: 99%

Effect of Lung Surfactant Protein SP-C and SP-C-Promoted Membrane Fragmentation on Cholesterol Dynamics

Roldán

Nyholm

Slotte

et al. 2016

Biophysical Journal

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“…The excited-state lifetime of tPA is very sensitive to changes in acyl chain order in its immediate vicinity (32,33). Thus, tPA appears to be a very valuable tool for studying the formation and properties of lateral domains, at least in model membrane systems (32)(33)(34)(35). 2 H NMR has been very useful for elucidating the behavior of lipids in bilayer membranes (36), and the advantage is the use of deuterated lipids whose behavior is very similar to that of native lipids (37,38).…”

Section: Introductionmentioning

confidence: 99%

Lipid Interactions and Organization in Complex Bilayer Membranes

Engberg

Yasuda

Hautala

et al. 2016

Biophysical Journal

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Bilayer lipids influence the lateral structure of the membranes, but the relationship between lipid properties and the lateral structure formed is not always understood. Model membrane studies on bilayers containing cholesterol and various phospholipids (PLs) suggest that high and low temperature melting PLs may segregate, especially in the presence of cholesterol. The effect of different PL headgroups on lateral structure of bilayers is also not clear. Here, we have examined the formation of lateral heterogeneity in increasingly complex (up to five-component) multilamellar bilayers. We have used time-resolved fluorescence spectroscopy with domain-selective fluorescent probes (PL-conjugated trans-parinaric acid), and (2)H NMR spectroscopy with site or perdeuterated PLs. We have measured changes in bilayer order using such domain-selective probes both as a function of temperature and composition. Our results from time-resolved fluorescence and (2)H NMR showed that in ternary bilayers, acyl chain order and thermostability in sphingomyelin-rich domains were not affected to any greater extent by the headgroup structure of the monounsaturated PLs (phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine) in the bilayer. In the complex five-component bilayers, we could not detect major differences between the different monounsaturated PLs regarding cholesterol-induced ordering. However, cholesterol clearly influenced deuterated N-palmitoyl sphingomyelin differently than the other deuterated PLs, suggesting that cholesterol favored N-palmitoyl sphingomyelin over the other PLs. Taken together, both the fluorescence spectroscopy and (2)H NMR data suggest that the complex five-component membranes displayed lateral heterogeneity, at least in the lower temperature regimen examined.

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“…Therefore, we examined the membrane packing properties using 10 mol% GlcCer in POPC vesicles and a trans-parinaric acid (TPA) probe, which shows sensitivity to membrane packing. The TPA lifetime is short in fluid membranes (<5 ns), intermediate in a liquid-ordered phase, and long (30 ns and longer) in gel and solid membranes [37, 51, 52]. TPA shows a preference for partitioning into ordered/gel-phase domains.…”

Section: Resultsmentioning

confidence: 99%

“…The ability of tPA to partition into ordered domains was used to determine the formation of ordered phases in POPC with various lengths of GlcCers (10 mol%). The excited state lifetime of tPA is stabilized in gel phases, in part because of less diffusion-induced quenching by water and oxygen [37]. The samples contained 1 mol% tPA and measurements were performed at a constant temperature (23°C) with a FluoTime 100 instrument (PicoQuant GmbH, Berlin, Germany) using a PLS LED laser source for excitation (298 nm).…”

Section: Methodsmentioning

confidence: 99%

Glucosylceramide acyl chain length is sensed by the glycolipid transfer protein

et al. 2018

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The glycolipid transfer protein, GLTP, can be found in the cytoplasm, and it has a FFAT-like motif (two phenylalanines in an acidic tract) that targets it to the endoplasmic reticulum (ER). We have previously shown that GLTP can bind to a transmembrane ER protein, vesicle-associated membrane protein-associated protein A (VAP-A), which is involved in a wide range of ER functions. We have addressed the mechanisms that might regulate the association between GLTP and the VAP proteins by studying the capacity of GLTP to recognize different N-linked acyl chain species of glucosylceramide. We used surface plasmon resonance and a lipid transfer competition assay to show that GLTP prefers shorter N-linked fully saturated acyl chain glucosylceramides, such as C8, C12, and C16, whereas long C18, C20, and C24-glucosylceramides are all bound more weakly and transported more slowly than their shorter counterparts. Changes in the intrinsic GLTP tryptophan fluorescence blueshifts, also indicate a break-point between C16- and C18-glucosylceramide in the GLTP sensing ability. It has long been postulated that GLTP would be a sensor in the sphingolipid synthesis machinery, but how this mechanistically occurs has not been addressed before. It is unclear what proteins the GLTP VAP association would influence. Here we found that if GLTP has a bound GlcCer the association with VAP-A is weaker. We have also used a formula for identifying putative FFAT-domains, and we identified several potential VAP-interactors within the ceramide and sphingolipid synthesis pathways that could be candidates for regulation by GLTP.

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Effects of Cholesterol and Saturated Sphingolipids on Acyl Chain Order in 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine Bilayers—A Comparative Study with Phase-Selective Fluorophores

Cited by 20 publications

References 51 publications

Effect of Lung Surfactant Protein SP-C and SP-C-Promoted Membrane Fragmentation on Cholesterol Dynamics

Effect of Lung Surfactant Protein SP-C and SP-C-Promoted Membrane Fragmentation on Cholesterol Dynamics

Lipid Interactions and Organization in Complex Bilayer Membranes

Glucosylceramide acyl chain length is sensed by the glycolipid transfer protein

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