1
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Goh MWS, Tozawa Y, Tero R. Assembly of Cell-Free Synthesized Ion Channel Molecules in Artificial Lipid Bilayer Observed by Atomic Force Microscopy. MEMBRANES 2023; 13:854. [PMID: 37999340 PMCID: PMC10673230 DOI: 10.3390/membranes13110854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 11/25/2023]
Abstract
Artificial lipid bilayer systems, such as vesicles, black membranes, and supported lipid bilayers (SLBs), are valuable platforms for studying ion channels at the molecular level. The reconstitution of the ion channels in an active form is a crucial process in studies using artificial lipid bilayer systems. In this study, we investigated the assembly of the human ether-a-go-go-related gene (hERG) channel prepared in a cell-free synthesis system. AFM topographies revealed the presence of protrusions with a uniform size in the entire SLB that was prepared with the proteoliposomes (PLs) incorporating the cell-free-synthesized hERG channel. We attributed the protrusions to hERG channel monomers, taking into consideration the AFM tip size, and identified assembled structures of the monomer that exhibited dimeric, trimeric, and tetrameric-like arrangements. We observed molecular images of the functional hERG channel reconstituted in a lipid bilayer membrane using AFM and quantitatively evaluated the association state of the cell-free synthesized hERG channel.
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Affiliation(s)
- Melvin Wei Shern Goh
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi 441-8580, Japan
| | - Yuzuru Tozawa
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan;
| | - Ryugo Tero
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi 441-8580, Japan
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2
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Koshiyama K, Nakata K. Effects of lipid saturation on bicelle to vesicle transition of a binary phospholipid mixture: a molecular dynamics simulation study. SOFT MATTER 2023; 19:7655-7662. [PMID: 37782209 DOI: 10.1039/d3sm00904a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Controlling the transition from lipid bicelles to vesicles is essential for producing engineered vesicles. We perform coarse-grained molecular dynamics (CGMD) simulations of unsaturated/saturated lipid mixtures to clarify the effects of lipid unsaturation on vesiculation at the molecular scale. The results demonstrate that vesiculation depends on the concentration of unsaturated lipids and the degree of unsaturation. The probability of vesiculation increases linearly with the apparent unsaturated lipid concentration at a low degree of unsaturation. Higher degrees of unsaturation lead to phase segregation within the binary bicelles, reducing the probability of vesiculation. A comparison between CGMD simulations and the conventional theory of vesiculation shows that the theoretical predictions of binary lipid systems must explicitly include phase segregation effects. Furthermore, simulations with biased lipid distributions reveal that vesiculation is facilitated by the preconcentration of unsaturated lipids in the core region of the bicelle but is then temporally limited as the unsaturated lipids move to the bicelle edges. These findings advance theoretical and experimental studies on binary lipid systems and promote the development of tailor-made vesicles.
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Affiliation(s)
- Kenichiro Koshiyama
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, 770-8506, Japan.
| | - Kazuki Nakata
- Graduate School of Sciences and Technology for Innovation, Tokushima University, Tokushima 770-8506, Japan.
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3
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Foley SL, Hossein A, Deserno M. Fluid-gel coexistence in lipid membranes under differential stress. Biophys J 2022; 121:2997-3009. [PMID: 35859420 PMCID: PMC9463654 DOI: 10.1016/j.bpj.2022.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/03/2022] [Accepted: 07/12/2022] [Indexed: 11/21/2022] Open
Abstract
A widely conserved property of many biological lipid bilayers is their asymmetry. In addition to having distinct compositions on its two sides, a membrane can also exhibit different tensions in its two leaflets, a state known as differential stress. Here, we examine how this stress can influence the phase behavior of the constituent lipid monolayers of a single-component membrane. For temperatures sufficiently close to, but still above, the main transition, molecular dynamics simulations show the emergence of finite gel domains within the compressed leaflet. We describe the thermodynamics of this phenomenon by adding two empirical single-leaflet free energies for the fluid-gel transition, each evaluated at its respective asymmetry-dependent lipid density. Finite size effects arising in simulation are included in the theory through a geometry-dependent interfacial term. Our model reproduces the phase coexistence observed in simulation. It could therefore be used to connect the "hidden variable" of differential stress to experimentally observable properties of the main phase transition. These ideas could be generalized to any first-order bilayer phase transition in the presence of asymmetry, including liquid-ordered/liquid-disordered phase separation.
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Affiliation(s)
- Samuel L Foley
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Amirali Hossein
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
| | - Markus Deserno
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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4
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Lee H, Moon H, Kim HR. Effects of Lipid Shape and Interactions on the Conformation, Dynamics, and Curvature of Ultrasound-Responsive Liposomes. Pharmaceutics 2022; 14:1512. [PMID: 35890407 PMCID: PMC9320727 DOI: 10.3390/pharmaceutics14071512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/10/2022] [Accepted: 07/19/2022] [Indexed: 12/10/2022] Open
Abstract
We perform coarse-grained molecular dynamics simulations of bilayers composed of various lipids and cholesterol at their different ratios. Simulations show that cholesterol-lipid interactions restrict the lateral dynamics of bilayers but also promote bilayer curvature, indicating that these opposite effects simultaneously occur and thus cannot significantly influence bilayer stability. In contrast, lyso-lipids effectively pack the vacancy in the bilayer composed of cone-shaped lipids and thus reduce bilayer dynamics and curvature, showing that bilayers are more significantly stabilized by lyso-lipids than by cholesterol, in agreement with experiments. In particular, the bilayer composed of cone-shaped lipids shows higher dynamics and curvature than does the bilayer composed of cylindrical-shaped lipids. To mimic ultrasound, a high external pressure was applied in the direction of bilayer normal, showing the formation of small pores that are surrounded by hydrophilic lipid headgroups, which can allow the release of drug molecules encapsulated into the liposome. These findings help to explain experimental observations regarding that liposomes are more significantly stabilized by lyso-lipids than by cholesterol, and that the liposome with cone-shaped lipids more effectively releases drug molecules upon applying ultrasound than does the liposome with cylindrical-shaped lipids.
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Affiliation(s)
- Hwankyu Lee
- Department of Chemical Engineering, Dankook University, Yongin-si 16890, Korea
| | - Hyungwon Moon
- R&D Center, IMGT Co., Ltd., 172, Dolma-ro, Bundang-gu, Seongnam-si 13605, Korea;
| | - Hyun-Ryoung Kim
- R&D Center, IMGT Co., Ltd., 172, Dolma-ro, Bundang-gu, Seongnam-si 13605, Korea;
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5
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Biocompatible and optically stable hydrophobic fluorescent carbon dots for isolation and imaging of lipid rafts in model membrane. Anal Bioanal Chem 2022; 414:6055-6067. [PMID: 35697813 DOI: 10.1007/s00216-022-04165-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/06/2022] [Accepted: 06/02/2022] [Indexed: 11/01/2022]
Abstract
Lateral heterogeneity in cell membranes features a variety of compositions that influence their inherent properties. One such biophysical variation is the formation of a membrane or lipid raft, which plays important roles in many cellular processes. The lipid rafts on the cell membrane are mostly identified by specific dyes and heavy metal quantum dots, which have their own drawbacks, such as cytotoxicity, photostability, and incompatibility. To this end, we synthesized special, hydrophobic, fluorescent, photostable, and non-cytotoxic carbon dots (CDs) by solvent-free thermal treatment using non-cytotoxic materials and incorporated into the lipid bilayers of giant unilamellar vesicles (GUVs) made from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC) lipids. A 2:2:1 mixture of DOPC, DPPC, and cholesterol (Chol) develops lipid rafts on the membrane by phase separation. The photophysical properties of the CDs get modulated on incorporation into the lipid rafts that identifies the membrane heterogeneity. The main attempt in this work is to develop a new, simple, cost-effective, and bio-friendly lipid raft marker, which can be used in biological applications, alongside other conventional raft markers, with more advantages.
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6
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Winslow M, Robinson D. Computational development of a phase-sensitive membrane raft probe. Phys Chem Chem Phys 2022; 24:8260-8268. [PMID: 35319559 DOI: 10.1039/d2cp00431c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Derivatives of the widely used 1,6-diphenyl-1,3,5-hexatriene molecular probe have been considered using a multiscale approach involving spin-flip time-dependent density functional theory, classical molecular dynamics and hybrid quantum mechanics/molecular mechanics. We identify a potential probe of membrane phase (i.e. to preferentially detect liquid-ordered regions of lipid bilayers), which exhibits restricted access to a conical intersection in the liquid-ordered phase but is freely accessible in less ordered molecular environments. The characteristics of this probe also mark it as a candidate for an aggregation induced emission fluorophore.
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Affiliation(s)
- Max Winslow
- Department of Chemistry and Forensics, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
| | - David Robinson
- Department of Chemistry and Forensics, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
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7
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Oliveira MC, Yusupov M, Bogaerts A, Cordeiro RM. Distribution of lipid aldehydes in phase-separated membranes: A molecular dynamics study. Arch Biochem Biophys 2022; 717:109136. [DOI: 10.1016/j.abb.2022.109136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/19/2022] [Accepted: 01/21/2022] [Indexed: 11/02/2022]
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Non-raft submicron domain formation in cholesterol-containing lipid bilayers induced by polyunsaturated phosphatidylethanolamine. Colloids Surf B Biointerfaces 2021; 210:112235. [PMID: 34891064 DOI: 10.1016/j.colsurfb.2021.112235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/08/2021] [Accepted: 11/16/2021] [Indexed: 12/13/2022]
Abstract
Domain formation in "HLC" ternary lipid bilayers, comprising a high transition temperature (High-Tm) lipid, a Low-Tm lipid, and cholesterol (Chol), has been extensively studied as raft-resembling systems. Recently, we reported the formation of submicron domains in an "LLC" lipid bilayer, encompassing Low-Tm phosphatidylethanolamine (PE), Low-Tm phosphatidylcholine (PC), and Chol. We hypothesized that the formation of this unique domain is driven by polyunsaturated PE. In this study, we explored the effects of the degree of PE unsaturation and the double bond distribution at the sn-position on the mechanism of formation and the composition of submicron domains. Supported lipid bilayers (SLBs), comprising PE with various degrees of unsaturation, monounsaturated PC (POPC), and Chol, were investigated using fluorescence microscopy, atomic force microscopy, and the force-distance curve measurement. The area fraction of submicron domains in PE+POPC+Chol-SLB increased with the PE concentration and degree of unsaturation of the PE acyl chain. The results indicated that the submicron domains were enriched with polyunsaturated PE and were in the liquid-disordered-like state, whereas their surrounding regions were in the liquid-ordered-like state. Segregation of polyunsaturated PE from the Chol-containing region generated submicron domains in the LLC lipid bilayer. We propose a mechanism for the formation of these submicron domains based on molecular interactions involving the hydrophobic and hydrophilic parts of the bilayer membrane.
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9
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Song ES, Oh Y, Sung BJ. Interdomain exchange and the flip-flop of cholesterol in ternary component lipid membranes and their effects on heterogeneous cholesterol diffusion. Phys Rev E 2021; 104:044402. [PMID: 34781553 DOI: 10.1103/physreve.104.044402] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 09/17/2021] [Indexed: 11/07/2022]
Abstract
Cell membranes are heterogeneous with a variety of lipids, cholesterol, and proteins and are composed of domains of different compositions. Such heterogeneous environments make the transport of cholesterol complicated: cholesterol not only diffuses within a particular domain but also travels between domains. Cholesterol also flip-flops between upper and lower leaflets such that cholesterol may reside both within leaflets and in the central region between two leaflets. How the presence of multiple domains and the interdomain exchange of cholesterol would affect the cholesterol transport, however, remains elusive. In this study, therefore, we perform molecular dynamics simulations up to 100μs for ternary component lipid membranes, which consist of saturated lipids (dipalmitoylphosphatidylcholine, DPPC), unsaturated lipids (dilinoleylphosphatidylcholine, DIPC), and cholesterol. The ternary component membranes in our simulations form two domains readily: DPPC and DIPC domains. We find that the diffusion of cholesterol molecules is much more heterogeneous and non-Gaussian than expected for binary component lipid membranes of lipids and cholesterol. The non-Gaussian parameter of the cholesterol molecules is about four times larger in the ternary component lipid membranes than in the binary component lipid membranes. Such non-Gaussian and heterogeneous transport of cholesterol arises from the interplay among the interdomain kinetics, the different diffusivity of cholesterol in different domains, and the flip-flop of cholesterol. This suggests that in cell membranes that consist of various domains and proteins, the cholesterol transport can be very heterogeneous. We also find that the mechanism of the interdomain exchange differs for different domains: cholesterol tends to exit the DIPC domain along the central region of the membrane for the DIPC-to-DPPC transition, while the cholesterol is likely to exit the DPPC domain within the membrane leaflet for the DPPC-to-DIPC transition. Also, the interdomain exchange kinetics of cholesterol for the DPPC-to-DIPC transition is up to 7.9 times slower than the DIPC-to-DPPC transition.
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Affiliation(s)
- Eun Sub Song
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
| | - Younghoon Oh
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
| | - Bong June Sung
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
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10
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Oh Y, Song ES, Sung BJ. The effects of the lipid type on the spatial arrangement and dynamics of cholesterol in binary component lipid membranes. J Chem Phys 2021; 154:135101. [PMID: 33832232 DOI: 10.1063/5.0043212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Intermolecular interactions between cholesterol and lipids in cell membranes, which play critical roles in cellular processes such as the formation of nano-domains, depend on the molecular structure of the lipids. The diffusion and the spatial arrangement of cholesterol within the lipid membranes also change with the type of lipids. For example, the flip-flop, an important transport mechanism for cholesterol in the membranes, can be facilitated significantly by the presence of unsaturated lipids. However, how the structure of lipids affects the spatial arrangement and the dynamics of cholesterol remains elusive at a molecular level. In this study, we investigate the effects of lipid-cholesterol interactions on the spatial arrangement and the dynamics of cholesterol. We perform molecular dynamics simulations for the binary component membranes of lipids and cholesterol. We employ seven different kinds of lipids by changing either the degree of a saturation level or the length of lipid tails. We find from our simulations that the rate of cholesterol flip-flop is enhanced as the lipids are either less saturated or shorter, which is consistent with previous studies. Interestingly, when the lipid tails are fully saturated and sufficiently long, the center in between two leaflets becomes metastable for cholesterol to stay at. Because the cholesterol at the membrane center diffuses faster than that within leaflets, regardless of the lipid type, such an emergence of the metastable state (in terms of the cholesterol position) complicates the cholesterol diffusion significantly.
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Affiliation(s)
- Younghoon Oh
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
| | - Eun Sub Song
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
| | - Bong June Sung
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
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11
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Lin X, Lin X. Surface ligand rigidity modulates lipid raft affinity of ultra-small hydrophobic nanoparticles: insights from molecular dynamics simulations. NANOSCALE 2021; 13:9825-9833. [PMID: 34032262 DOI: 10.1039/d1nr01563j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Differential preferences between lipids and proteins drive the formation of dynamical nanoscale membrane domains (lipid rafts), which play key roles in the proper functioning of cells. On the other hand, due to the potent physicochemical properties of nanoparticles (NPs), they have been widely used in drug delivery, bio-imaging and regulating various essential biological processes of the cells. Hence, in this work, we aim to design ultra-small hydrophobic NPs with tunable raft affinity, which is supposed to partition into the hydrophobic region of lipid membranes and be able to regulate the dynamics of the lipid raft domains. A series of μs-scale coarse-grained molecular dynamics simulations and umbrella sampling free energy calculations were performed to investigate the role of surface ligand rigidity of ultra-small hydrophobicNPs in their raft affinity. Our results indicated that the preferred localization of NPs can be tuned by adjusting their surface ligand rigidity. Generally, rigid NPs tended to target the raft domain, while soft NPs preferred the interface of the raft and non-raft domains. The free energy analysis further indicated that the surface ligand rigidity of NPs can enhance their targeting to lipid raft domains. Besides, we found that these ultra-small NPs had no significant effects on the phase separation of the lipid membrane although they might cause some local interference to surrounding lipids. These results indicate that the targeting to the lipid raft domain can be achieved by the surface ligand rigidity of NPs, which provides helpful insights for further regulations of lipid raft-mediated biological processes.
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Affiliation(s)
- Xiaoqian Lin
- Institute of Single Cell Engineering, Key Laboratory of Ministry of Education for Biomechanics and Mechanobiology, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China.
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12
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Goh MWS, Tero R. Cholesterol-induced microdomain formation in lipid bilayer membranes consisting of completely miscible lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183626. [PMID: 33901442 DOI: 10.1016/j.bbamem.2021.183626] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/19/2022]
Abstract
Recently, we reported that a ternary lipid bilayer comprising phosphatidylethanolamine (PE), phosphatidylcholine (PC), which were both derived from chicken egg, and cholesterol (Chol) generates microdomains that function as specific fusion sites for proteoliposomes. Chol-induced microdomain formation in a completely miscible lipid bilayer is an exceptional phenomenon. Numerous studies have elucidated the formation of domains in liquid ordered (Lo) and liquid disordered (Ld) phases of ternary bilayers, which comprise two partially miscible lipids and Chol. Herein, we investigated the composition and mechanism of formation of these unique microdomains in supported lipid bilayers (SLBs) using a fluorescence microscope and an atomic force microscope (AFM). We prepared ternary SLBs using egg-derived PC (eggPC), Chol and three different types of PE: egg-derived PE, 1-palmitoyl-2-oleoyl-PE, and 1,2-didocosahexaenoyl-PE (diDHPE). Fluorescence microscopy observations revealed that fluid and continuous SLBs were formed at PE concentrations (CPE) of ≥6 mol%. Fluorescence recovery after photobleaching measurement revealed that the microdomain was more fluid than the surrounding region that showed typical diffusion coefficient of the Lo phase. The microdomains were observed as depressions in the AFM topographies. Their area fraction (θ) increased with CPE, and diDHPE produced a significantly large θ among the three PEs. The microdomains in the PE+eggPC+Chol-SLBs were rich in polyunsaturated PE and were in the Ld-like phase. Associating eggPC and Chol caused polyunsaturated PE to segregate, resulting in a microdomain formation by conferring the umbrella effect on Chol, entropic effect of disordered acyl chains, and π-π interactions in the hydrophobic core.
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Affiliation(s)
- Melvin Wei Shern Goh
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Ryugo Tero
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.
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Yu Y, Kim H, Choi S, Yu J, Lee JY, Lee H, Yoon S, Kim WY. Targeting a Lipid Desaturation Enzyme, SCD1, Selectively Eliminates Colon Cancer Stem Cells through the Suppression of Wnt and NOTCH Signaling. Cells 2021; 10:cells10010106. [PMID: 33430034 PMCID: PMC7826607 DOI: 10.3390/cells10010106] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 12/13/2022] Open
Abstract
The elimination of the cancer stem cell (CSC) population may be required to achieve better outcomes of cancer therapy. We evaluated stearoyl-CoA desaturase 1 (SCD1) as a novel target for CSC-selective elimination in colon cancer. CSCs expressed more SCD1 than bulk cultured cells (BCCs), and blocking SCD1 expression or function revealed an essential role for SCD1 in the survival of CSCs, but not BCCs. The CSC potential selectively decreased after treatment with the SCD1 inhibitor in vitro and in vivo. The CSC-selective suppression was mediated through the induction of apoptosis. The mechanism leading to selective CSC death was investigated by performing a quantitative RT-PCR analysis of 14 CSC-specific signaling and marker genes after 24 and 48 h of treatment with two concentrations of an inhibitor. The decrease in the expression of Notch1 and AXIN2 preceded changes in the expression of all other genes, at 24 h of treatment in a dose-dependent manner, followed by the downregulation of most Wnt- and NOTCH-signaling genes. Collectively, we showed that not only Wnt but also NOTCH signaling is a primary target of suppression by SCD1 inhibition in CSCs, suggesting the possibility of targeting SCD1 against colon cancer in clinical settings.
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Affiliation(s)
- Yeongji Yu
- College of Pharmacy, Sookmyung Women’s University, Seoul 04312, Korea; (Y.Y.); (H.K.); (S.C.); (J.Y.); (J.Y.L.); (H.L.)
| | - Hyejin Kim
- College of Pharmacy, Sookmyung Women’s University, Seoul 04312, Korea; (Y.Y.); (H.K.); (S.C.); (J.Y.); (J.Y.L.); (H.L.)
| | - SeokGyeong Choi
- College of Pharmacy, Sookmyung Women’s University, Seoul 04312, Korea; (Y.Y.); (H.K.); (S.C.); (J.Y.); (J.Y.L.); (H.L.)
| | - JinSuh Yu
- College of Pharmacy, Sookmyung Women’s University, Seoul 04312, Korea; (Y.Y.); (H.K.); (S.C.); (J.Y.); (J.Y.L.); (H.L.)
| | - Joo Yeon Lee
- College of Pharmacy, Sookmyung Women’s University, Seoul 04312, Korea; (Y.Y.); (H.K.); (S.C.); (J.Y.); (J.Y.L.); (H.L.)
| | - Hani Lee
- College of Pharmacy, Sookmyung Women’s University, Seoul 04312, Korea; (Y.Y.); (H.K.); (S.C.); (J.Y.); (J.Y.L.); (H.L.)
| | - Sukjoon Yoon
- Research Institute of Women’s Health, Sookmyung Women’s University, Seoul 04310, Korea;
| | - Woo-Young Kim
- Research Institute of Pharmaceutical Sciences, Sookmyung Women’s University, Seoul 04312, Korea
- Correspondence: ; Tel.: +82-2-2077-7587
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14
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Ludwig J, Maibaum L. Effect of alcohol on the phase separation in model membranes. Chem Phys Lipids 2020; 233:104986. [PMID: 33080278 DOI: 10.1016/j.chemphyslip.2020.104986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/20/2020] [Accepted: 09/28/2020] [Indexed: 12/20/2022]
Abstract
The discovery of coexisting liquid-ordered and liquid-disordered phases in multicomponent lipid bilayers has received widespread attention due to its potential relevance for biological systems. One of the many open questions is how the presence of additional components affects the nature of the coexisting phases. Of particular interest is the addition of alcohols because their anesthetic properties may arise from modulating bilayer behavior. We use coarse-grained Molecular Dynamics simulations to gain insight into the partitioning preferences of linear n-alcohols into ordered and disordered bilayers alongside their effects on local membrane structure. We find that alcohols cause only small changes to membrane composition alongside a lack of significant effects on membrane thickness and lipid tail order. Cholesterol and n-alcohol trans-bilayer motion is measured and found to be near or within the range of previous atomistic results. The cholesterol flip-flop rates increase with both n-alcohol length and concentration for octanol, dodecanol, and hexadecanol, indicating a decrease in lipid order. Umbrella sampling simulations of removing cholesterol from tertiary membranes find no significant difference with or without n-alcohols at various concentrations. Simulations of a phase-separated bilayer show that octanol preferentially partitions into the liquid-disordered phase in a ratio of approximately 3:1 over the liquid-ordered phase. Furthermore, partition coefficients of alcohol in single-phase membranes show a preference for longer alcohols (dodecanol and hexadecanol) to partition preferentially into the liquid-ordered phase, while decreasing the length of the alcohol reverses this trend. Our work tests experimental results while also investigating the ability for coarse-grained MARTINI simulations to capture minute differences in model membrane spatial arrangements on the nanoscale level.
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Affiliation(s)
- James Ludwig
- Department of Chemistry, University of Washington, Seattle, WA 98195, United States
| | - Lutz Maibaum
- Department of Chemistry, University of Washington, Seattle, WA 98195, United States.
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15
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Centi A, Dutta A, Parekh SH, Bereau T. Inserting Small Molecules across Membrane Mixtures: Insight from the Potential of Mean Force. Biophys J 2020; 118:1321-1332. [PMID: 32075746 DOI: 10.1016/j.bpj.2020.01.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 01/05/2020] [Accepted: 01/27/2020] [Indexed: 11/29/2022] Open
Abstract
Small solutes have been shown to alter the lateral organization of cell membranes and reconstituted phospholipid bilayers; however, the mechanisms by which these changes happen are still largely unknown. Traditionally, both experiment and simulation studies have been restricted to testing only a few compounds at a time, failing to identify general molecular descriptors or chemical properties that would allow extrapolating beyond the subset of considered solutes. In this work, we probe the competing energetics of inserting a solute in different membrane environments by means of the potential of mean force. We show that these calculations can be used as a computationally efficient proxy to establish whether a solute will stabilize or destabilize domain phase separation. Combined with umbrella-sampling simulations and coarse-grained molecular dynamics simulations, we are able to screen solutes across a wide range of chemistries and polarities. Our results indicate that for the system under consideration, preferential partitioning and therefore effectiveness in altering membrane phase separation are strictly linked to the location of insertion in the bilayer (i.e., midplane or interface). Our approach represents a fast and simple tool for obtaining structural and thermodynamic insight into the partitioning of small molecules between lipid domains and its relation to phase separation, ultimately providing a platform for identifying the key determinants of this process.
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Affiliation(s)
- Alessia Centi
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Arghya Dutta
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Sapun H Parekh
- Max Planck Institute for Polymer Research, Mainz, Germany; Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas
| | - Tristan Bereau
- Max Planck Institute for Polymer Research, Mainz, Germany.
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16
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Hakobyan D, Heuer A. Comparing an All-Atom and a Coarse-Grained Description of Lipid Bilayers in Terms of Enthalpies and Entropies: From MD Simulations to 2D Lattice Models. J Chem Theory Comput 2019; 15:6393-6402. [DOI: 10.1021/acs.jctc.9b00390] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Davit Hakobyan
- Institute of Physical Chemistry, WWU Muenster, Corrensstr. 28/30, 48149 Muenster, Germany
- Center for Multiscale Theory and Computation (CMTC), WWU Muenster, 48149 Muenster, Germany
| | - Andreas Heuer
- Institute of Physical Chemistry, WWU Muenster, Corrensstr. 28/30, 48149 Muenster, Germany
- Center for Multiscale Theory and Computation (CMTC), WWU Muenster, 48149 Muenster, Germany
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17
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Choi S, Yoo YJ, Kim H, Lee H, Chung H, Nam MH, Moon JY, Lee HS, Yoon S, Kim WY. Clinical and biochemical relevance of monounsaturated fatty acid metabolism targeting strategy for cancer stem cell elimination in colon cancer. Biochem Biophys Res Commun 2019; 519:100-105. [PMID: 31481234 DOI: 10.1016/j.bbrc.2019.08.137] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 08/24/2019] [Indexed: 12/12/2022]
Abstract
Lipid metabolism is associated with colon cancer prognosis and incidence. Stearoyl-CoA desaturase 1 (SCD1), which converts fully saturated fatty acids (SFAs) to monounsaturated fatty acids (MUFAs), has been suggested as a vulnerable target for selective elimination of cancer stem cells (CSCs). However, the clinical significance and physiological role of SCD1 in CSCs has not been well demonstrated. Here, we showed the clinical and biochemical relevance of blocking SCD1 to target CSCs by analyzing human colon cancer data from TCGA and through lipidomic profiling of CSCs with or without SCD1 inhibition using mass spectrometry. Positive associations between SCD1 expression and colorectal cancer patient clinical status and the expression of CSC-related genes (WNT and NOTCH signaling) were found based on TCGA data analysis. Lipidomic profiling of CSCs and bulk cancer cells (BCCs) using mass spectrometry revealed that colon CSCs contained a distinctive lipid profile, with higher free MUFA and lower free SFA levels than in BCCs, suggesting that enhanced SCD1 activity generates MUFAs that may support WNT signaling in CSCs. In addition, all identified phosphatidyl-ethanolamine-containing MUFAs were found at higher levels in CSCs. Interestingly, we observed lower phosphatidyl-serine (18:1/18:0), phosphatidyl-choline (PC; p-18:0/18:1)), and sphingomyelin (SM; d18:1/20:0 or d16:1/22:0) levels in CSCs than in BCCs. Of those, SCD1 inhibition, which efficiently diminished free MUFA levels, increased those specific PC and SM and MUFAs in CSCs promptly. These results suggest that these specific lipid composition is critical for CSC stem cell maintenance. In addition, not only free MUFAs, which are known to be required for WNT signaling, but also other phospholipids, such as SM, which are important for lipid raft formation, may mediate other cell signaling pathways that support CSC maintenance. Comparison of the lipidomic profiles of colon cancer cells with those of previously reported for glioma cells further demonstrated the tissue specific characteristics of lipid metabolism in CSCs.
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Affiliation(s)
- SeokGyeong Choi
- College of Pharmacy, Sookmyung Women's University, Seoul, 04312, South Korea
| | - Young Ji Yoo
- College of Pharmacy, Sookmyung Women's University, Seoul, 04312, South Korea
| | - Hyejin Kim
- College of Pharmacy, Sookmyung Women's University, Seoul, 04312, South Korea
| | - Hani Lee
- College of Pharmacy, Sookmyung Women's University, Seoul, 04312, South Korea
| | - Hayung Chung
- Environmental Risk and Welfare Research Team, Korea Basic Science Institute, Seoul, 02841, South Korea
| | - Myung-Hee Nam
- Environmental Risk and Welfare Research Team, Korea Basic Science Institute, Seoul, 02841, South Korea
| | - Ju-Yeon Moon
- Drug Metabolism & Bioanalysis Laboratory, College of Pharmacy, The Catholic University of Korea, Bucheon, 14662, South Korea
| | - Hye Suk Lee
- Drug Metabolism & Bioanalysis Laboratory, College of Pharmacy, The Catholic University of Korea, Bucheon, 14662, South Korea
| | - Sukjoon Yoon
- Research Institute of Women's Health, Sookmyung Women's University, Seoul, 04310, South Korea
| | - Woo-Young Kim
- College of Pharmacy, Sookmyung Women's University, Seoul, 04312, South Korea; Research Institute of Pharmaceutical Sciences, Sookmyung Women's University, Seoul, 04312, South Korea.
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18
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Bandara A, Panahi A, Pantelopulos GA, Nagai T, Straub JE. Exploring the impact of proteins on the line tension of a phase-separating ternary lipid mixture. J Chem Phys 2019; 150:204702. [PMID: 31153187 DOI: 10.1063/1.5091450] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The separation of lipid mixtures into thermodynamically stable phase-separated domains is dependent on lipid composition, temperature, and system size. Using molecular dynamics simulations, the line tension between thermodynamically stable lipid domains formed from ternary mixtures of di-C16:0 PC:di-C18:2 PC:cholesterol at 40:40:20 mol. % ratio was investigated via two theoretical approaches. The line tension was found to be 3.1 ± 0.2 pN by capillary wave theory and 4.7 ± 3.7 pN by pressure tensor anisotropy approaches for coarse-grained models based on the Martini force field. Using an all-atom model of the lipid membrane based on the CHARMM36 force field, the line tension was found to be 3.6 ± 0.9 pN using capillary wave theory and 1.8 ± 2.2 pN using pressure anisotropy approaches. The discrepancy between estimates of the line tension based on capillary wave theory and pressure tensor anisotropy methods is discussed. Inclusion of protein in Martini membrane lipid mixtures was found to reduce the line tension by 25%-35% as calculated by the capillary wave theory approach. To further understand and predict the behavior of proteins in phase-separated membranes, we have formulated an analytical Flory-Huggins model and parameterized it against the simulation results. Taken together these results suggest a general role for proteins in reducing the thermodynamic cost associated with domain formation in lipid mixtures and quantifies the thermodynamic driving force promoting the association of proteins to domain interfaces.
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Affiliation(s)
- Asanga Bandara
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Afra Panahi
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - George A Pantelopulos
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Tetsuro Nagai
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - John E Straub
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
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19
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 175] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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20
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Meinhardt S, Schmid F. Structure of lateral heterogeneities in a coarse-grained model for multicomponent membranes. SOFT MATTER 2019; 15:1942-1952. [PMID: 30662989 DOI: 10.1039/c8sm02261e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We study the lateral domain structure in a coarse-grained molecular model for multicomponent lipid bilayers by semi-grandcanonical Monte Carlo simulations. The membranes are filled with liquid ordered (lo) domains surrounded by a liquid disordered (ld) matrix. Depending on the membrane composition and temperature, we identify different morphological regimes: one regime (I) where the lo domains are small and relatively compact, and two regimes (II, II') where they are larger and often interconnected. In the latter two regimes, the ld matrix forms a network of disordered trenches separating the lo domains, with a relatively high content of interdigitated line defects. Since such defects are also a structural element of the modulated ripple phase in one component membranes, we argue that the regimes II, II' may be amorphous equivalents of the ripple phase in multicomponent membranes. We also analyze the local structure and provide evidence that the domains in regime I are stabilized by a monolayer curvature mechanism postulated in earlier work [S. Meinhardt et al., PNAS, 2013, 110, 4476].
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Affiliation(s)
- Sebastian Meinhardt
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, USA
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21
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Fluorescence Turn‐on Synthetic Lipid Rafts on Supramolecular Sheets and Hierarchical Concanavalin A Assembly. Chem Asian J 2019; 14:952-957. [DOI: 10.1002/asia.201900122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/17/2019] [Indexed: 01/11/2023]
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22
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Therapeutic targeting of lipid synthesis metabolism for selective elimination of cancer stem cells. Arch Pharm Res 2018; 42:25-39. [PMID: 30536027 DOI: 10.1007/s12272-018-1098-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/01/2018] [Indexed: 02/06/2023]
Abstract
Cancer stem cells (CSCs) are believed to have an essential role in tumor resistance and metastasis; however, no therapeutic strategy for the selective elimination of CSCs has been established. Recently, several studies have shown that the metabolic regulation for ATP synthesis and biological building block generation in CSCs are different from that in bulk cancer cells and rather similar to that in normal tissue stem cells. To take advantage of this difference for CSC elimination therapy, many studies have tested the effect of blocking these metabolism. Two specific processes for lipid biosynthesis, i.e., fatty acid unsaturation and cholesterol biosynthesis, have been shown to be very effective and selective for CSC targets. In this review, lipid metabolism specific to CSCs are summarized. In addition, how monounsaturated fatty acid and cholesterol synthesis may contribute to CSC maintenance are discussed. Specifically, the molecular mechanism required for lipid synthesis and essential for stem cell biology is highlighted. The limit and preview of the lipid metabolism targeting for CSCs are also discussed.
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23
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Friedman R, Khalid S, Aponte-Santamaría C, Arutyunova E, Becker M, Boyd KJ, Christensen M, Coimbra JTS, Concilio S, Daday C, van Eerden FJ, Fernandes PA, Gräter F, Hakobyan D, Heuer A, Karathanou K, Keller F, Lemieux MJ, Marrink SJ, May ER, Mazumdar A, Naftalin R, Pickholz M, Piotto S, Pohl P, Quinn P, Ramos MJ, Schiøtt B, Sengupta D, Sessa L, Vanni S, Zeppelin T, Zoni V, Bondar AN, Domene C. Understanding Conformational Dynamics of Complex Lipid Mixtures Relevant to Biology. J Membr Biol 2018; 251:609-631. [PMID: 30350011 PMCID: PMC6244758 DOI: 10.1007/s00232-018-0050-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/03/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Ran Friedman
- Department of Chemistry and Biomedical Sciences and Centre of Excellence "Biomaterials Chemistry", Linnæus University, Kalmar, Sweden.
| | - Syma Khalid
- University of Southampton, Southampton, SO17 1BJ, UK
| | - Camilo Aponte-Santamaría
- Max Planck Tandem Group in Computational Biophysics, University of Los Andes, Bogotá, Colombia.,Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Elena Arutyunova
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | | | - Kevin J Boyd
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Mikkel Christensen
- Department of Chemistry, Aarhus University, Aarhus, Denmark.,Interdisciplinary Nanoscience center (iNANO), Aarhus University, Aarhus, Denmark.,Sino-Danish Center for Education and Research, Beijing, China
| | - João T S Coimbra
- UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
| | - Simona Concilio
- Department of Industrial Engineering, University of Salerno, Fisciano, SA, Italy
| | - Csaba Daday
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
| | | | - Pedro A Fernandes
- UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
| | - Frauke Gräter
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany.,Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
| | | | | | - Konstantina Karathanou
- Department of Physics, Theoretical Molecular Biophysics Group, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | | | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | | | - Eric R May
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Antara Mazumdar
- GBB Institute, University of Groningen, Groningen, The Netherlands
| | - Richard Naftalin
- Physiology and Vascular Biology Departments, King's College London School of Medicine, London, UK
| | - Mónica Pickholz
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, IFIBA, Buenos Aires, Argentina
| | - Stefano Piotto
- Department of Pharmacy, University of Salerno, Fisciano, SA, Italy
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | - Peter Quinn
- Biochemistry Department, King's College London, London, UK
| | - Maria J Ramos
- UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
| | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Aarhus, Denmark.,Interdisciplinary Nanoscience center (iNANO), Aarhus University, Aarhus, Denmark
| | - Durba Sengupta
- Physical Chemistry Division, National Chemical Laboratory, Pune, India
| | - Lucia Sessa
- Department of Pharmacy, University of Salerno, Fisciano, SA, Italy
| | - Stefano Vanni
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Talia Zeppelin
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Valeria Zoni
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Ana-Nicoleta Bondar
- Department of Physics, Theoretical Molecular Biophysics Group, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Carmen Domene
- Department of Chemistry, University of Bath, Claverton Down Bath, BA2 7AY, UK.,Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
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24
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Parameterization of a coarse-grained model of cholesterol with point-dipole electrostatics. J Comput Aided Mol Des 2018; 32:1259-1271. [DOI: 10.1007/s10822-018-0164-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 09/12/2018] [Indexed: 12/14/2022]
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25
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Carpenter TS, López CA, Neale C, Montour C, Ingólfsson HI, Di Natale F, Lightstone FC, Gnanakaran S. Capturing Phase Behavior of Ternary Lipid Mixtures with a Refined Martini Coarse-Grained Force Field. J Chem Theory Comput 2018; 14:6050-6062. [DOI: 10.1021/acs.jctc.8b00496] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Timothy S. Carpenter
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | | | | | - Cameron Montour
- Biochemistry and Molecular Biology Department, Georgetown University, Washington, DC 20057, United States
| | - Helgi I. Ingólfsson
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Francesco Di Natale
- Applications, Simulations, and Quality Division, Computation Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Felice C. Lightstone
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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26
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López Martí JM, English NJ, Del Pópolo MG. Elucidating mysteries of phase-segregated membranes: mobile-lipid recruitment facilitates pores' passage to the fluid phase. Phys Chem Chem Phys 2018; 20:19234-19239. [PMID: 29989117 DOI: 10.1039/c8cp00958a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Phase segregation of multicomponent lipid bilayers leads to, under phase-coexistence conditions, domain formation, featuring delimitation by essentially one-dimensional borders. (Micro-)phase segregation of bilayers is proposed to influence the physiological behaviour of cell membranes and provides the driving force for lipid-raft formation. Experiments show a maximum in the electrical-conductivity of membranes at the phase-transition point, which has been conjectured to arise from border-nucleated transmembrane-conducting defects or pores. However, recent electroporation experiments on phase-segregated bilayers demonstrate electro-pore detection in the liquid disordered phase (Ld), wherein they diffuse over macroscopic periods without absorption into the liquid ordered phase (Lo). Here, we scrutinise transmembrane-pore formation via molecular dynamics simulations on a multicomponent phase-segregated bilayer. We find that pores created in Lo domains always migrate spontaneously to the Ld phase, via 'recruitment' of unsaturated lipids to the pore's rim to transport the pore to the fluid phase under a large stress-field driving force. Once in Ld domains, pores migrate towards their centre, never returning or pinning to Lo. These findings are explained by thermodynamics. By comparing the free-energy cost for creating pores in the bulk of Ld and Lo membranes, and in the phase-segregated system, we show that it is always more energetically tractable to create pores in Ld domains, independent of the pore size.
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Affiliation(s)
- Jesús M López Martí
- CONICET & Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Padre Jorge Contreras 1300, CP5500, Mendoza, Argentina.
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27
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Baoukina S, Rozmanov D, Tieleman DP. Composition Fluctuations in Lipid Bilayers. Biophys J 2018; 113:2750-2761. [PMID: 29262367 PMCID: PMC5770567 DOI: 10.1016/j.bpj.2017.10.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 02/06/2023] Open
Abstract
Cell membranes contain multiple lipid and protein components having heterogeneous in-plane (lateral) distribution. Nanoscale rafts are believed to play an important functional role, but their phase state—domains of coexisting phases or composition fluctuations—is unknown. As a step toward understanding lateral organization of cell membranes, we investigate the difference between nanoscale domains of coexisting phases and composition fluctuations in lipid bilayers. We simulate model lipid bilayers with the MARTINI coarse-grained force field on length scales of tens of nanometers and timescales of tens of microseconds. We use a binary and a ternary mixture: a saturated and an unsaturated lipid, or a saturated lipid, an unsaturated lipid, and cholesterol, respectively. In these mixtures, the phase behavior can be tuned from a mixed state to a coexistence of a liquid-crystalline and a gel, or a liquid-ordered and a liquid-disordered phase. Transition from a two-phase to a one-phase state is achieved by raising the temperature and adding a hybrid lipid (with a saturated and an unsaturated chain). We analyze the evolution of bilayer properties along this transition: domains of two phases transform to fluctuations with local ordering and compositional demixing. Nanoscale domains and fluctuations differ in several properties, including interleaflet overlap and boundary length. Hybrid lipids show no enrichment at the boundary, but decrease the difference between the coexisting phases by ordering the disordered phase, which could explain their role in cell membranes.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - Dmitri Rozmanov
- Department of Information Technologies, University of Calgary, Calgary, Alberta, Canada
| | - D Peter Tieleman
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada.
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28
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Nawae W, Hannongbua S, Ruengjitchatchawalya M. Molecular dynamics exploration of poration and leaking caused by Kalata B1 in HIV-infected cell membrane compared to host and HIV membranes. Sci Rep 2017; 7:3638. [PMID: 28620219 PMCID: PMC5472625 DOI: 10.1038/s41598-017-03745-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 05/05/2017] [Indexed: 12/21/2022] Open
Abstract
The membrane disruption activities of kalata B1 (kB1) were investigated using molecular dynamics simulations with membrane models. The models were constructed to mimic the lipid microdomain formation in membranes of HIV particle, HIV-infected cell, and host cell. The differences in the lipid ratios of these membranes caused the formation of liquid ordered (lo) domains of different sizes, which affected the binding and activity of kB1. Stronger kB1 disruptive activity was observed for the membrane with small sized lo domain. Our results show that kB1 causes membrane leaking without bilayer penetration. The membrane poration mechanism involved in the disorganization of the lo domain and in cholesterol inter-leaflet translocation is described. This study enhances our understanding of the membrane activity of kB1, which may be useful for designing novel and potentially therapeutic peptides based on the kB1 framework.
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Affiliation(s)
- Wanapinun Nawae
- Pilot Plant Development and Training Institution, King Mongkut's University of Technology Thonburi (Bang Khun Thian Campus), 49 Soi Thian Thale 25, Bang Khun Thian Chai Thale Rd., Tha Kham, Bang Khun Thian, Bangkok, 10150, Thailand
| | - Supa Hannongbua
- Department of Chemistry, Kasetsart University, 50 Phaholyothin Rd., Ladyao, Chatuchak, Bangkok, Thailand, 10900
| | - Marasri Ruengjitchatchawalya
- Biotechnology Program, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi (Bang KhunThian Campus), 49 Soi Thian Thale 25, Bang Khun Thian Chai Thale Rd., Tha Kham, Bang Khun Thian, Bangkok, 10150, Thailand.
- Bioinformatics and Systems Biology Program, King Mongkut's University of Technology Thonburi (Bang Khun Thian Campus), 49 Soi Thian Thale 25, Bang Khun Thian Chai Thale Rd., Tha Kham, Bang Khun Thian, Bangkok, 10150, Thailand.
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29
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Hakobyan D, Heuer A. 2D lattice model of a lipid bilayer: Microscopic derivation and thermodynamic exploration. J Chem Phys 2017; 146:064305. [DOI: 10.1063/1.4975163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Davit Hakobyan
- Institute of Physical Chemistry, WWU Münster, Corrensstr. 28/30, 48149 Münster, Germany and Center for Multiscale Theory and Computation (CMTC), WWU Münster, 48149 Münster, Germany
| | - Andreas Heuer
- Institute of Physical Chemistry, WWU Münster, Corrensstr. 28/30, 48149 Münster, Germany and Center for Multiscale Theory and Computation (CMTC), WWU Münster, 48149 Münster, Germany
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30
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Gorai B, Sivaraman T. Delineating residues for haemolytic activities of snake venom cardiotoxin 1 from Naja naja as probed by molecular dynamics simulations and in vitro validations. Int J Biol Macromol 2017; 95:1022-1036. [DOI: 10.1016/j.ijbiomac.2016.10.091] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 10/26/2016] [Indexed: 02/05/2023]
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31
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Gaibelet G, Tercé F, Allart S, Lebrun C, Collet X, Jamin N, Orlowski S. Fluorescent probes for detecting cholesterol-rich ordered membrane microdomains: entangled relationships between structural analogies in the membrane and functional homologies in the cell. AIMS BIOPHYSICS 2017. [DOI: 10.3934/biophy.2017.1.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Schmid F. Physical mechanisms of micro- and nanodomain formation in multicomponent lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:509-528. [PMID: 27823927 DOI: 10.1016/j.bbamem.2016.10.021] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/19/2016] [Accepted: 10/27/2016] [Indexed: 12/17/2022]
Abstract
This article summarizes a variety of physical mechanisms proposed in the literature, which can generate micro- and nanodomains in multicomponent lipid bilayers and biomembranes. It mainly focusses on lipid-driven mechanisms that do not involve direct protein-protein interactions. Specifically, it considers (i) equilibrium mechanisms based on lipid-lipid phase separation such as critical cluster formation close to critical points, and multiple domain formation in curved geometries, (ii) equilibrium mechanisms that stabilize two-dimensional microemulsions, such as the effect of linactants and the effect of curvature-composition coupling in bilayers and monolayers, and (iii) non-equilibrium mechanisms induced by the interaction of a biomembrane with the cellular environment, such as membrane recycling and the pinning effects of the cytoplasm. Theoretical predictions are discussed together with simulations and experiments. The presentation is guided by the theory of phase transitions and critical phenomena, and the appendix summarizes the mathematical background in a concise way within the framework of the Ginzburg-Landau theory. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Friederike Schmid
- Institute of Physics, Johannes Gutenberg University, 55099 Mainz, Germany
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Ackerman DG, Feigenson GW. Effects of Transmembrane α-Helix Length and Concentration on Phase Behavior in Four-Component Lipid Mixtures: A Molecular Dynamics Study. J Phys Chem B 2016; 120:4064-77. [PMID: 27081858 DOI: 10.1021/acs.jpcb.6b00611] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We used coarse-grained molecular dynamics simulations to examine the effects of transmembrane α-helical WALP peptides on the behavior of four-component lipid mixtures. These mixtures contain a high-melting temperature (high-Tm) lipid, a nanodomain-inducing low-Tm lipid, a macrodomain-inducing low-Tm lipid and cholesterol to model the outer leaflet of cell plasma membranes. In a series of simulations, we incrementally replace the nanodomain-inducing low-Tm lipid by the macrodomain-inducing low-Tm lipid and measure how lipid and phase properties are altered by the addition of WALPs of different length. Regardless of the ratio of the two low-Tm lipids, shorter WALPs increase domain size and all WALPs increase domain alignment between the two leaflets. These effects are smallest for the longest WALP tested, and increase with increasing WALP concentration. Thus, our simulations explain the experimental observation that WALPs induce macroscopic domains in otherwise nanodomain-forming lipid-only mixtures (unpublished). Since the cell plasma membrane contains a large fraction of transmembrane proteins, these findings link the behavior of lipid-only model membranes in vitro to phase behavior in vivo.
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Affiliation(s)
- David G Ackerman
- Department of Molecular Biology and Genetics, Cornell University , Ithaca, New York 14853, United States
| | - Gerald W Feigenson
- Department of Molecular Biology and Genetics, Cornell University , Ithaca, New York 14853, United States
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Huang JY, Lin CY. Exploring the stochastic dynamics of correlated movement of receptor proteins in plasma membranes in vivo. J Chem Phys 2015; 143:225101. [PMID: 26671403 DOI: 10.1063/1.4936963] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ligand-induced receptor dimerization plays a crucial role in the signaling process of living cells. In this study, we developed a theoretical model and performed single-molecule tracking to explore the correlated diffusion processes of liganded epidermal growth factor receptors prior to dimer formation. We disclosed that both an attractive potential between liganded receptor proteins in proximity and correlated fluctuations in the local environments of the proteins play an important role to produce the observed correlated movement of the receptors. This result can serve as the foundation to shed light on the way in which receptor functions are regulated in plasma membranes in vivo.
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Affiliation(s)
- Jung Y Huang
- The T.K.B. Research Center of Photonics, Chiao Tung University, Hsinchu 300, Taiwan
| | - Chien Y Lin
- Department of Photonics, Chiao Tung University, Hsinchu 300, Taiwan
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Ackerman DG, Feigenson GW. Multiscale modeling of four-component lipid mixtures: domain composition, size, alignment, and properties of the phase interface. J Phys Chem B 2015; 119:4240-50. [PMID: 25564922 DOI: 10.1021/jp511083z] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Simplified lipid mixtures are often used to model the complex behavior of the cell plasma membrane. Indeed, as few as four components-a high-melting lipid, a nandomain-inducing low-melting lipid, a macrodomain-inducing low-melting lipid, and cholesterol (chol)-can give rise to a wide range of domain sizes and patterns that are highly sensitive to lipid compositions. Although these systems are studied extensively with experiments, the molecular-level details governing their phase behavior are not yet known. We address this issue by using molecular dynamics simulations to analyze how phase separation evolves in a four-component system as it transitions from small domains to large domains. To do so, we fix concentrations of the high-melting lipid 16:0,16:0-phosphatidylcholine (DPPC) and chol, and incrementally replace the nanodomain-inducing low-melting lipid 16:0,18:2-PC (PUPC) by the macrodomain-inducing low-melting lipid 18:2,18:2-PC (DUPC). Coarse-grained simulations of this four-component system reveal that lipid demixing increases as the amount of DUPC increases. Additionally, we find that domain size and interleaflet alignment change sharply over a narrow range of replacement of PUPC by DUPC, indicating that intraleaflet and interleaflet behaviors are coupled. Corresponding united atom simulations show that only lipids within ∼2 nm of the phase interface are significantly perturbed regardless of domain composition or size. Thus, whereas the fraction of interface-perturbed lipids is negligible for large domains, it is significant for smaller ones. Together, these results reveal characteristic traits of bilayer thermodynamic behavior in four-component mixtures, and provide a baseline for investigation of the effects of proteins and other lipids on membrane phase properties.
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Affiliation(s)
- David G Ackerman
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, United States
| | - Gerald W Feigenson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, United States
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Vertical ordering sensitivity of solid supported DPPC membrane to alamethicin and the related loss of cell viability. Biochim Biophys Acta Gen Subj 2015; 1850:759-68. [PMID: 25597953 DOI: 10.1016/j.bbagen.2015.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 12/23/2014] [Accepted: 01/08/2015] [Indexed: 11/23/2022]
Abstract
BACKGROUND Experimental studies of antimicrobial peptides interacting with lipid membranes recently attracted growing interest due to their numerous biomedical applications. However, the influence of such peptides on the structural organisation of lipid membranes in connection with the actual cell response still remains an elusive issue. METHODS X-ray diffraction was employed on detecting the sensitivity of the periodical spacing of dipalmitoyl-phosphatidyl-choline stacked as solid-supported bilayers to the presence of varying amounts of the peptide alamethicin in a wide range of peptide-to-lipid molar ratios. These results were then correlated with the effects of alamethicin on biological membranes in vitro as observed by optical microscopy and microculture tetrazolium assay on the tumour cells HeLa to provide a comprehensive and quantitative analysis of these effects, based on a dose-response relationship. RESULTS The experiments allowed correlating the periodical spacing and the peptide-to-lipid molar ratio on alamethicin-dipalmitoyl-phosphatidyl-choline samples. Two different trends of periodical spacing vs. peptide-to-lipid molar ratio clearly appeared at low and high hydration levels, showing intriguing non-linear profiles. Unexpected correspondences were observed between the peptide-to-lipid molar ratio range where the changes in dipalmitoyl-phosphatidyl-choline structure occur and the alamethicin doses which alter the viability and the plasma membrane morphology of HeLa. CONCLUSIONS Alamethicin might induce either mechanical or phase changes on dipalmitoyl-phosphatidyl-choline bilayers. Such easily accessible ordering information was well-calibrated to predict the alamethicin doses necessary to trigger cell death through plasma membrane alterations. GENERAL SIGNIFICANCE This benchmark combined study may be valuable to predict bioeffects of several antimicrobial peptides of biomedical relevance.
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Parker JA, Mattos C. The Ras-Membrane Interface: Isoform-specific Differences in The Catalytic Domain. Mol Cancer Res 2015; 13:595-603. [PMID: 25566993 DOI: 10.1158/1541-7786.mcr-14-0535] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/11/2014] [Indexed: 11/16/2022]
Abstract
The small GTPase Ras is mutated in about 20% of human cancers, primarily at active site amino acid residues G12, G13, and Q61. Thus, structural biology research has focused on the active site, impairment of GTP hydrolysis by oncogenic mutants, and characterization of protein-protein interactions in the effector lobe half of the protein. The C-terminal hypervariable region has increasingly gained attention due to its importance in H-Ras, N-Ras, and K-Ras differences in membrane association. A high-resolution molecular view of the Ras-membrane interaction involving the allosteric lobe of the catalytic domain has lagged behind, although evidence suggests that it contributes to isoform specificity. The allosteric lobe has recently gained interest for harboring potential sites for more selective targeting of this elusive "undruggable" protein. The present review reveals critical insight that isoform-specific differences appear prominently at these potentially targetable sites and integrates these differences with knowledge of Ras plasma membrane localization, with the intent to better understand the structure-function relationships needed to design isoform-specific Ras inhibitors.
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Affiliation(s)
- Jillian A Parker
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts
| | - Carla Mattos
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts.
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Baoukina S, Tieleman DP. Computer simulations of phase separation in lipid bilayers and monolayers. Methods Mol Biol 2015; 1232:307-322. [PMID: 25331143 DOI: 10.1007/978-1-4939-1752-5_21] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Studying phase coexistence in lipid bilayers and monolayers is important for understanding lipid-lipid interactions underlying lateral organization in biological membranes. Computer simulations follow experimental approaches and use model lipid mixtures of simplified composition. Atomistic simulations give detailed information on the specificity of intermolecular interactions, while coarse-grained simulations achieve large time and length scales and provide a bridge towards state-of-the-art experimental techniques. Computer simulations allow characterizing the structure and composition of domains during phase transformations at Angstrom and picosecond resolution, and bring new insights into phase behavior of lipid membranes.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, 2500 University Dr. NW, Calgary, AB, Canada, T2N 1N4,
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Róg T, Vattulainen I. Cholesterol, sphingolipids, and glycolipids: what do we know about their role in raft-like membranes? Chem Phys Lipids 2014; 184:82-104. [PMID: 25444976 DOI: 10.1016/j.chemphyslip.2014.10.004] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 10/24/2014] [Accepted: 10/25/2014] [Indexed: 12/14/2022]
Abstract
Lipids rafts are considered to be functional nanoscale membrane domains enriched in cholesterol and sphingolipids, characteristic in particular of the external leaflet of cell membranes. Lipids, together with membrane-associated proteins, are therefore considered to form nanoscale units with potential specific functions. Although the understanding of the structure of rafts in living cells is quite limited, the possible functions of rafts are widely discussed in the literature, highlighting their importance in cellular functions. In this review, we discuss the understanding of rafts that has emerged based on recent atomistic and coarse-grained molecular dynamics simulation studies on the key lipid raft components, which include cholesterol, sphingolipids, glycolipids, and the proteins interacting with these classes of lipids. The simulation results are compared to experiments when possible.
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Affiliation(s)
- Tomasz Róg
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology, Tampere, Finland; MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark.
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