1
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Yasuda T, Ueura D, Nakagomi M, Hanashima S, Peter Slotte J, Murata M. Design, synthesis of ceramide 1-phosphate analogs and their affinity for cytosolic phospholipase A 2 as evidenced by surface plasmon resonance. Bioorg Med Chem Lett 2024; 107:129792. [PMID: 38734389 DOI: 10.1016/j.bmcl.2024.129792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 05/06/2024] [Accepted: 05/08/2024] [Indexed: 05/13/2024]
Abstract
Ceramide 1-phosphate (C1P) is a lipid mediator that specifically binds and activates cytosolic phospholipase A2α (cPLA2α). To elucidate the structure-activity relationship of the affinity of C1P for cPLA2α in lipid environments, we prepared a series of C1P analogs containing structural modifications in the hydrophilic parts and subjected them to surface plasmon resonance (SPR). The results suggested the presence of a specific binding site for cPLA2α on the amide, 3-OH and phosphate groups in C1P structure. Especially, dihydro-C1P exhibited enhanced affinity for cPLA2α, suggesting the hydrogen bonding ability of 3-hydroxy group is important for interactions with cPLA2α. This study helps to understand the influence of specific structural moieties of C1P on the interaction with cPLA2α at the atomistic level and may lead to the design of drugs that regulate cPLA2α activation.
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Affiliation(s)
- Tomokazu Yasuda
- Research Foundation ITSUU Laboratory, C1232, Kanagawa Science Park R&D Building, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan; Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; Forefront Research Center, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
| | - Daiki Ueura
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Madoka Nakagomi
- Research Foundation ITSUU Laboratory, C1232, Kanagawa Science Park R&D Building, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan
| | - Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Tykistökatu 6A, FIN-20520 Turku, Finland
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan; Forefront Research Center, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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2
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Murata M, Matsumori N, Kinoshita M, London E. Molecular substructure of the liquid-ordered phase formed by sphingomyelin and cholesterol: sphingomyelin clusters forming nano-subdomains are a characteristic feature. Biophys Rev 2022; 14:655-678. [PMID: 35791389 DOI: 10.1007/s12551-022-00967-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 05/26/2022] [Indexed: 11/29/2022] Open
Abstract
As a model of lipid rafts, the liquid-ordered (Lo) phase formed by sphingomyelin (SM) and cholesterol (Cho) in bilayer membranes has long attracted the attention of biophysics researchers. New approaches and methodologies have led to a better understanding of the molecular basis of the Lo domain structure. This review summarizes studies on model membrane systems consisting of SM/unsaturated phospholipid/Cho implying that the Lo phase contains SM-based nanodomains (or nano-subdomains). Some of the Lo phase properties may be attributed to these nanodomains. Several studies suggest that the nanodomains contain clustered SM molecules packed densely to form gel-phase-like subdomains of single-digit nanometer size at physiological temperatures. Cho and unsaturated lipids located in the Lo phase are likely to be concentrated at the boundaries between the subdomains. These subdomains are not readily detected in the Lo phase formed by saturated phosphatidylcholine (PC) molecules, suggesting that they are strongly stabilized by homophilic interactions specific to SM, e.g., between SM amide groups. This model for the Lo phase is supported by experiments using dihydro-SM, which is thought to have stronger homophilic interactions than SM, as well as by studies using the enantiomer of SM having opposite stereochemistry to SM at the 2 and 3 positions and by some molecular dynamics (MD) simulations of lipid bilayers containing Lo-lipids. Nanosized gel subdomains seem to play an important role in controlling membrane organization and function in biological membranes.
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Affiliation(s)
- Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, 560-0043 Japan.,ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, Graduate School of Science, Osaka University, Osaka, 560-0043 Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395 Japan
| | - Masanao Kinoshita
- ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, Graduate School of Science, Osaka University, Osaka, 560-0043 Japan.,Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395 Japan
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215 USA
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3
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Kobayashi T, Tomishige N, Inaba T, Makino A, Murata M, Yamaji-Hasegawa A, Murate M. Impact of Intrinsic and Extrinsic Factors on Cellular Sphingomyelin Imaging with Specific Reporter Proteins. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:25152564211042456. [PMID: 37366372 PMCID: PMC10259817 DOI: 10.1177/25152564211042456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Sphingomyelin (SM) is a major sphingolipid in mammalian cells. Although SM is enriched in the outer leaflet of the cell plasma membrane, lipids are also observed in the inner leaflet of the plasma membrane and intracellular organelles such as endolysosomes, the Golgi apparatus and nuclei. SM is postulated to form clusters with glycosphingolipids (GSLs), cholesterol (Chol), and other SM molecules through hydrophobic interactions and hydrogen bonding. Thus, different clusters composed of SM, SM/Chol, SM/GSL and SM/GSL/Chol with different stoichiometries may exist in biomembranes. In addition, SM monomers may be located in the glycerophospholipid-rich areas of membranes. Recently developed SM-binding proteins (SBPs) distinguish these different SM assemblies. Here, we summarize the effects of intrinsic factors regulating the lipid-binding specificity of SBPs and extrinsic factors, such as the lipid phase and lipid density, on SM recognition by SBPs. The combination of different SBPs revealed the heterogeneity of SM domains in biomembranes.
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Affiliation(s)
- Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Wako, Saitama, Japan
- Cellular Informatics Laboratory, RIKEN
CPR, Wako, Saitama, Japan
- Laboratoire de Bioimagerie et
Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg,
Illkirch, France
| | - Nario Tomishige
- Lipid Biology Laboratory, RIKEN, Wako, Saitama, Japan
- Cellular Informatics Laboratory, RIKEN
CPR, Wako, Saitama, Japan
- Laboratoire de Bioimagerie et
Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg,
Illkirch, France
| | | | - Asami Makino
- Lipid Biology Laboratory, RIKEN, Wako, Saitama, Japan
| | - Michio Murata
- Department of Chemistry, Graduate
School of Science, Osaka University, Toyonaka, Osaka, Japan
- ERATO, Lipid Active Structure Project,
Japan Science and Technology Agency, Graduate School of Science, Osaka University,
Osaka, Japan
| | | | - Motohide Murate
- Lipid Biology Laboratory, RIKEN, Wako, Saitama, Japan
- Cellular Informatics Laboratory, RIKEN
CPR, Wako, Saitama, Japan
- Laboratoire de Bioimagerie et
Pathologies, Faculté de Pharmacie, UMR 7021 CNRS, Université de Strasbourg,
Illkirch, France
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4
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Yano Y, Hanashima S, Tsuchikawa H, Yasuda T, Slotte JP, London E, Murata M. Sphingomyelins and ent-Sphingomyelins Form Homophilic Nano-Subdomains within Liquid Ordered Domains. Biophys J 2020; 119:539-552. [PMID: 32710823 PMCID: PMC7399500 DOI: 10.1016/j.bpj.2020.06.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/19/2020] [Accepted: 06/26/2020] [Indexed: 12/29/2022] Open
Abstract
Sphingomyelin (SM), a major component of small domains (or lipid rafts) in mammalian cell membranes, forms a liquid-ordered phase in the presence of cholesterol (Cho). However, the nature of molecular interactions within the ordered SM/Cho phase remains elusive. We previously revealed that stearoyl-SM (SSM) and its enantiomer (ent-SSM) separately form nano-subdomains within the liquid-ordered phase involving homophilic SSM-SSM and ent-SSM-ent-SSM interactions. In this study, the details of the subdomain formation by SSMs at the nanometer range were examined using Förster resonance energy transfer (FRET) measurements in lipid bilayers containing SSM and ent-SSM, dioleoyl-phosphatidylcholine and Cho. Although microscopy detected a stereochemical effect on partition coefficient favoring stereochemically homophilic interactions in the liquid-ordered state, it showed no significant difference in large-scale liquid-ordered domain formation by the two stereoisomers. In contrast to the uniform domains seen microscopy, FRET analysis using fluorescent donor- and acceptor-labeled SSM showed distinct differences in SM and ent-SM colocalization within nanoscale distances. Donor- and acceptor-labeled SSM showed significantly higher FRET efficiency than did donor-labeled SSM and acceptor-labeled ent-SSM in lipid vesicles composed of “racemic” (1:1) mixtures of SSM/ent-SSM with dioleoylphosphatidylcholine and Cho. The difference in FRET efficiency indicated that SSM and ent-SSM assemble to form separate nano-subdomains. The average size of the subdomains decreased as temperature increased, and at physiological temperatures, the subdomains were found to have a single-digit nanometer radius. These results suggest that (even in the absence of ent-SM) SM-SM interactions play a crucial role in forming nano-subdomains within liquid-ordered domains and may be a key feature of lipid microdomains (or rafts) in biological membranes.
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Affiliation(s)
- Yo Yano
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, Graduate School of Science, Osaka University, Osaka, Japan
| | - Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - Hiroshi Tsuchikawa
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - Tomokazu Yasuda
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York.
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, Graduate School of Science, Osaka University, Osaka, Japan.
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5
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Hanashima S, Yano Y, Murata M. Enantiomers of phospholipids and cholesterol: A key to decipher lipid‐lipid interplay in membrane. Chirality 2020; 32:282-298. [DOI: 10.1002/chir.23171] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 12/23/2019] [Accepted: 12/26/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Shinya Hanashima
- Department of Chemistry, Graduate School of ScienceOsaka University Toyonaka Japan
| | - Yo Yano
- Department of Chemistry, Graduate School of ScienceOsaka University Toyonaka Japan
| | - Michio Murata
- Department of Chemistry, Graduate School of ScienceOsaka University Toyonaka Japan
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Yano Y, Hanashima S, Yasuda T, Tsuchikawa H, Matsumori N, Kinoshita M, Al Sazzad MA, Slotte JP, Murata M. Sphingomyelin Stereoisomers Reveal That Homophilic Interactions Cause Nanodomain Formation. Biophys J 2018; 115:1530-1540. [PMID: 30274830 DOI: 10.1016/j.bpj.2018.08.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/31/2018] [Accepted: 08/27/2018] [Indexed: 01/03/2023] Open
Abstract
Sphingomyelin is an abundant lipid in some cellular membrane domains, such as lipid rafts. Hydrogen bonding and hydrophobic interactions of the lipid with surrounding components such as neighboring sphingomyelin and cholesterol (Cho) are widely considered to stabilize the raft-like liquid-ordered (Lo) domains in membrane bilayers. However, details of their interactions responsible for the formation of Lo domains remain largely unknown. In this study, the enantiomer of stearoyl sphingomyelin (ent-SSM) was prepared, and its physicochemical properties were compared with the natural SSM and the diastereomer of SSM to examine possible stereoselective lipid-lipid interactions. Interestingly, differential scanning calorimetry experiments demonstrated that palmitoyl sphingomyelin, with natural stereochemistry, exhibited higher miscibility with SSM bilayers than with ent-SSM bilayers, indicating that the homophilic sphingomyelin interactions occurred in a stereoselective manner. Solid-state 2H NMR revealed that Cho elicited its ordering effect very similarly on SSM and ent-SSM (and even on the diastereomer of SSM), suggesting that SSM-Cho interactions are not significantly affected by stereospecific hydrogen bonding. SSM and ent-SSM formed gel-like domains with very similar lateral packing in SSM/Cho/palmitoyloleoyl phosphatidylcholine membranes, as shown by fluorescence lifetime experiments. This observation can be explained by a homophilic hydrogen-bond network, which was largely responsible for the formation of gel-like nanodomains of SSMs (or ent-SSM). Our previous study revealed that Cho-poor gel-like domains contributed significantly to the formation of an Lo phase in sphingomyelin/Cho membranes. The results of the study presented here further show that SSM-SSM interactions occur near the headgroup region, whereas hydrophobic SSM-Cho interactions appeared important in the bilayer interior for Lo domain formation. The homophilic interactions of sphingomyelins could be mainly responsible for the formation of the domains of nanometer size, which may correspond to the small sphingomyelin/Cho-based rafts that temporally occur in biological membranes.
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Affiliation(s)
- Yo Yano
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, Graduate School of Science, Osaka University, Osaka, Japan
| | - Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - Tomokazu Yasuda
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - Hiroshi Tsuchikawa
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Graduate School of Science, Kyushu University, Fukuoka, Japan
| | - Masanao Kinoshita
- Department of Chemistry, Graduate School of Science, Kyushu University, Fukuoka, Japan
| | - Md Abdullah Al Sazzad
- Biochemistry, Faculty of Science Engineering, Åbo Akademi University, Turku, Finland
| | - J Peter Slotte
- Biochemistry, Faculty of Science Engineering, Åbo Akademi University, Turku, Finland.
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan; ERATO, Lipid Active Structure Project, Japan Science and Technology Agency, Graduate School of Science, Osaka University, Osaka, Japan.
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7
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Kinoshita M, Ano H, Murata M, Shigetomi K, Ikenouchi J, Matsumori N. Emphatic visualization of sphingomyelin-rich domains by inter-lipid FRET imaging using fluorescent sphingomyelins. Sci Rep 2017; 7:16801. [PMID: 29196620 PMCID: PMC5711942 DOI: 10.1038/s41598-017-16361-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/10/2017] [Indexed: 11/11/2022] Open
Abstract
Imaging the distribution of sphingomyelin (SM) in membranes is an important issue in lipid-raft research. Recently we developed novel fluorescent SM analogs that exhibit partition and dynamic behaviors similar to native SM, and succeeded in visualizing lateral domain-segregation between SM-rich liquid-ordered (Lo) and SM-poor liquid-disordered (Ld) domains. However, because the fluorescent contrast between these two domains depends directly on their partition ratio for the fluorescent SMs, domain-separation becomes indeterminate when the distribution difference is not great enough. In this study, we propose the use of inter-lipid Förster resonance energy transfer (FRET) imaging between fluorescent SMs to enhance the contrast of the two domains in cases in which the inter-domain difference in SM distribution is inadequate for conventional monochromic imaging. Our results demonstrate that inter-lipid FRET intensity was significantly higher in the Lo domain than in the Ld domain, resulting in a clear and distinguishable contrast between the two domains even in poorly phase-separated giant unilamellar vesicles. In addition, we show that inter-lipid FRET imaging is useful for selective visualization of highly condensed assemblies and/or clusters of SM molecules in living cell membranes. Thus, the inter-lipid FRET imaging technique can selectively emphasize the SM-condensed domains in both artificial and biological membranes.
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Affiliation(s)
- Masanao Kinoshita
- JST-ERATO Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan. .,Project Research Center for Fundamental Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan. .,Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
| | - Hikaru Ano
- JST-ERATO Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.,Project Research Center for Fundamental Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Michio Murata
- JST-ERATO Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.,Project Research Center for Fundamental Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.,Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Kenta Shigetomi
- Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Junichi Ikenouchi
- Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Nobuaki Matsumori
- JST-ERATO Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan. .,Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan. .,Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.
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Umegawa Y, Tanaka Y, Nobuaki M, Murata M. (13) C-TmDOTA as versatile thermometer compound for solid-state NMR of hydrated lipid bilayer membranes. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:227-233. [PMID: 26460094 DOI: 10.1002/mrc.4371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 09/03/2015] [Accepted: 09/19/2015] [Indexed: 06/05/2023]
Abstract
Recent advances in solid-state nuclear magnetic resonance (NMR) techniques, such as magic angle spinning and high-power decoupling, have dramatically increased the sensitivity and resolution of NMR. However, these NMR techniques generate extra heat, causing a temperature difference between the sample in the rotor and the variable temperature gas. This extra heating is a particularly crucial problem for hydrated lipid membrane samples. Thus, to develop an NMR thermometer that is suitable for hydrated lipid samples, thulium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (TmDOTA) was synthesized and labeled with (13) C (i.e., (13) C-TmDOTA) to increase the NMR sensitivity. The complex was mixed with a hydrated lipid membrane, and the system was subjected to solid-state NMR and differential scanning calorimetric analyses. The physical properties of the lipid bilayer and the quality of the NMR spectra of the membrane were negligibly affected by the presence of (13) C-TmDOTA, and the (13) C chemical shift of the complex exhibited a large-temperature dependence. The results demonstrated that (13) C-TmDOTA could be successfully used as a thermometer to accurately monitor temperature changes induced by (1) H decoupling pulses and/or by magic angle spinning and the temperature distribution of the sample inside the rotor. Thus, (13) C-TmDOTA was shown to be a versatile thermometer for hydrated lipid assemblies. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Yuichi Umegawa
- JST ERATO, Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Yuya Tanaka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Matsumori Nobuaki
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Michio Murata
- JST ERATO, Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
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Miyoshi T, Kato S. Detailed Analysis of the Surface Area and Elasticity in the Saturated 1,2-Diacylphosphatidylcholine/Cholesterol Binary Monolayer System. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:9086-9096. [PMID: 26255826 DOI: 10.1021/acs.langmuir.5b01775] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The surface pressure-area (π-A) isotherms of DMPC, DPPC, and DSPC/cholesterol binary monolayers were systematically measured with great care to gain insight into the lateral molecular packing in these binary monolayer systems. The average molecular area A and the area elastic modulus C(s)⁻¹ at a given surface pressure were calculated as a function of cholesterol mole fraction x(chol). As a result, data reliable enough for the analysis of detailed phase behavior were obtained. We identified several characteristic phase regions and assigned the phase state in each region on the basis of the deviation of A(x(chol)) and C(s)⁻¹(x(chol)) from ideal additivity. We also estimated the partial molecular areas of DMPC, DPPC, DSPC, and cholesterol in the single-phase regions, where C(s)⁻¹(x(chol)) values fell on an ideal additivity curve. We found that the addition of cholesterol induces the formation of a highly condensed phase where the diacylphosphatidylcholine (diacyl PC) molecule has a surface area even smaller than that in the solid phase, irrespective of the surface pressure and the chain length of diacyl PC. Here, we call the cholesterol-induced condensed phase the CC phase. Furthermore, we demonstrated that the basic features of A(x(chol)) and C(s)⁻¹(x(chol)) profiles can be explained semiquantitatively by assuming the state of vicinity lipids surrounding sparsely distributed cholesterol molecules in the low x(chol) region as a third state of the diacyl PC molecule in addition to the states in the pure diacyl PC monolayer and in the CC phase.
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Affiliation(s)
- Tsubasa Miyoshi
- Department of Physics, Graduate School of Science and Technology, Kwansei Gakuin University , 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
| | - Satoru Kato
- Department of Physics, Graduate School of Science and Technology, Kwansei Gakuin University , 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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10
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Sphingomyelin distribution in lipid rafts of artificial monolayer membranes visualized by Raman microscopy. Proc Natl Acad Sci U S A 2015; 112:4558-63. [PMID: 25825736 DOI: 10.1073/pnas.1418088112] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sphingomyelin (SM) and cholesterol (chol)-rich domains in cell membranes, called lipid rafts, are thought to have important biological functions related to membrane signaling and protein trafficking. To visualize the distribution of SM in lipid rafts by means of Raman microscopy, we designed and synthesized an SM analog tagged with a Raman-active diyne moiety (diyne-SM). Diyne-SM showed a strong peak in a Raman silent region that is free of interference from intrinsic vibrational modes of lipids and did not appear to alter the properties of SM-containing monolayers. Therefore, we used Raman microscopy to directly visualize the distribution of diyne-SM in raft-mimicking domains formed in SM/dioleoylphosphatidylcholine/chol ternary monolayers. Raman images visualized a heterogeneous distribution of diyne-SM, which showed marked variation, even within a single ordered domain. Specifically, diyne-SM was enriched in the central area of raft domains compared with the peripheral area. These results seem incompatible with the generally accepted raft model, in which the raft and nonraft phases show a clear biphasic separation. One of the possible reasons is that gradual changes of SM concentration occur between SM-rich and -poor regions to minimize hydrophobic mismatch. We believe that our technique of hyperspectral Raman imaging of a single lipid monolayer opens the door to quantitative analysis of lipid membranes by providing both chemical information and spatial distribution with high (diffraction-limited) spatial resolution.
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11
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Kinoshita M, Matsumori N, Murata M. Coexistence of two liquid crystalline phases in dihydrosphingomyelin and dioleoylphosphatidylcholine binary mixtures. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1372-81. [DOI: 10.1016/j.bbamem.2014.01.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 12/18/2013] [Accepted: 01/14/2014] [Indexed: 11/30/2022]
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