201
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Billcliff PG, Gorleku OA, Chamberlain LH, Banting G. The cytosolic N-terminus of CD317/tetherin is a membrane microdomain exclusion motif. Biol Open 2013; 2:1253-63. [PMID: 24244863 PMCID: PMC3828773 DOI: 10.1242/bio.20135793] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 08/15/2013] [Indexed: 01/17/2023] Open
Abstract
The integral membrane protein CD317/tetherin has been associated with a plethora of biological processes, including restriction of enveloped virus release, regulation of B cell growth, and organisation of membrane microdomains. CD317 possesses both a conventional transmembrane (TM) domain and a glycophosphatidylinositol (GPI) anchor. We confirm that the GPI anchor is essential for CD317 to associate with membrane microdomains, and that the TM domain of CD44 is unable to rescue proper microdomain association of a ΔGPI-CD317 construct. Additionally, we demonstrate that the cytosolic amino terminal region of CD317 can function as a ‘microdomain-excluding’ motif, when heterologously expressed as part of a reporter construct. Finally, we show that two recently described isoforms of CD317 do not differ in their affinity for membrane microdomains. Together, these data help further our understanding of the fundamental cell biology governing membrane microdomain association of CD317.
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Affiliation(s)
- Peter G Billcliff
- School of Biochemistry, University of Bristol , Bristol BS8 1TD , UK ; Present address: Faculty of Life Sciences, University of Manchester, Manchester M13 9PL, UK
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202
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Werkmüller A, Triola G, Waldmann H, Winter R. Rotational and translational dynamics of ras proteins upon binding to model membrane systems. Chemphyschem 2013; 14:3698-705. [PMID: 24115726 DOI: 10.1002/cphc.201300617] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Indexed: 01/16/2023]
Abstract
Plasma-membrane-associated Ras proteins typically control signal transduction processes. As nanoclustering and membrane viscosity sensing provide plausible signaling mechanisms, determination of the rotational and translational dynamics of membrane-bound Ras isoforms can help to link their dynamic mobility to their function. Herein, by using time-resolved fluorescence anisotropy and correlation spectroscopic measurements, we obtain the rotational-correlation time and the translational diffusion coefficient of lipidated boron-dipyrromethene-labeled Ras, both in bulk Ras and upon membrane binding. The results show that the second lipidation motif of N-Ras triggers dimer formation in bulk solution, whereas K-Ras4B is monomeric. Upon membrane binding, an essentially free rotation of the G-domain is observed, along with a high lateral mobility; the latter is essentially limited by the viscosity of the membrane and by lipid-mediated electrostatic interactions. This high diffusional mobility warrants rapid recognition-binding sequences in the membrane-bound state, thereby facilitating efficient interactions between the Ras proteins and scaffolding or effector proteins. The lipid-like rapid lateral diffusion observed here complies with in vivo data.
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Affiliation(s)
- Alexander Werkmüller
- Physical Chemistry I-Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Str. 6, 44227 Dortmund (Germany), Fax: (+49) 231 755 3901
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203
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Honigmann A, Mueller V, Hell SW, Eggeling C. STED microscopy detects and quantifies liquid phase separation in lipid membranes using a new far-red emitting fluorescent phosphoglycerolipid analogue. Faraday Discuss 2013; 161:77-89; discussion 113-50. [PMID: 23805739 DOI: 10.1039/c2fd20107k] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We have developed a bright, photostable, and far-red emitting fluorescent phosphoglycerolipid analogue to probe diffusion characteristics of lipids in membranes. The lipid analogue consists of a saturated (C18) phosphoethanolamine and a hydrophilic far-red emitting fluorescent dye (KK114) that is tethered to the head group by a long polyethylenglycol linker. In contrast to reported far-red emitting fluorescent lipid analogues, this one partitions predominantly into liquid ordered domains of phase-separated ternary bilayers. We performed fluorescence correlation spectroscopy with a super-resolution STED microscope (STED-FCS) to measure the lateral diffusion of the new lipid analogue in the liquid ordered (Lo) and disordered (Ld) phase. On a mica support, we observed micrometer large phases and found that the lipid analogue diffuses freely on all tested spatial scales (40-250 nm) in both the Ld and Lo phase with diffusion coefficients of 1.8 microm2 s(-1) and 0.7 microm2 s(-1) respectively. This indicates that the tight molecular packing of the Lo phase mainly slows down the diffusion rather than causing anomalous sub-diffusion. The same ternary mixture deposited on acid-cleaned glass forms Lo nanodomains of < 40 nm to 300 nm in diameter as only revealed by STED microscopy, which demonstrates the severe influence of interactions with the substrate on the sizes of domains in membranes. When averaging over different positions, STEd-FCS measurements on such glass supported membranes displayed anomalous sub-diffusion. This anomaly can be attributed to a transient partitioning of the lipid analogue into the nano-domains, where diffusion is slowed down. Our results suggest that STED-FCS in combination with a Lo-partitioning fluorescent lipid analogue can directly probe the presence of Lo nano-domains, which in the future should allow the study of potential lipid rafts in live-cell membranes.
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Affiliation(s)
- Alf Honigmann
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
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204
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Palmieri B, Safran SA. Hybrid lipids increase nanoscale fluctuation lifetimes in mixed membranes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:032708. [PMID: 24125295 DOI: 10.1103/physreve.88.032708] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 08/22/2013] [Indexed: 06/02/2023]
Abstract
A recently proposed ternary mixture model is used to predict fluctuation domain lifetimes in the one phase region. The membrane is made of saturated, unsaturated, and hybrid lipids that have one saturated and one unsaturated hydrocarbon chain. The hybrid lipid is a natural linactant which can reduce the packing incompatibility between saturated and unsaturated lipids. The fluctuation lifetimes are predicted as a function of the hybrid lipid fraction and the fluctuation domain size. These lifetimes can be increased by up to three orders of magnitude compared to the case of no hybrids. With hybrid, small length scale fluctuations have sizable amplitudes even close to the critical temperature and, hence, benefit from enhanced critical slowing down. The increase in lifetime is particularly important for nanometer scale fluctuation domains where the hybrid orientation and the other lipids composition are highly coupled.
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Affiliation(s)
- Benoit Palmieri
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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205
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Xia Y, Peng L. Photoactivatable Lipid Probes for Studying Biomembranes by Photoaffinity Labeling. Chem Rev 2013; 113:7880-929. [DOI: 10.1021/cr300419p] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yi Xia
- Aix-Marseille Université, Centre Interdisciplinaire de Nanoscience de Marseille, CNRS UMR 7325, Campus de Luminy, 13288 Marseille, France
| | - Ling Peng
- Aix-Marseille Université, Centre Interdisciplinaire de Nanoscience de Marseille, CNRS UMR 7325, Campus de Luminy, 13288 Marseille, France
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206
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Bhat HB, Kishimoto T, Abe M, Makino A, Inaba T, Murate M, Dohmae N, Kurahashi A, Nishibori K, Fujimori F, Greimel P, Ishitsuka R, Kobayashi T. Binding of a pleurotolysin ortholog from Pleurotus eryngii to sphingomyelin and cholesterol-rich membrane domains. J Lipid Res 2013; 54:2933-43. [PMID: 23918047 DOI: 10.1194/jlr.d041731] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A mixture of sphingomyelin (SM) and cholesterol (Chol) exhibits a characteristic lipid raft domain of the cell membranes that provides a platform to which various signal molecules as well as virus and bacterial proteins are recruited. Several proteins capable of specifically binding either SM or Chol have been reported. However, proteins that selectively bind to SM/Chol mixtures are less well characterized. In our screening for proteins specifically binding to SM/Chol liposomes, we identified a novel ortholog of Pleurotus ostreatus, pleurotolysin (Ply)A, from the extract of edible mushroom Pleurotus eryngii, named PlyA2. Enhanced green fluorescent protein (EGFP)-conjugated PlyA2 bound to SM/Chol but not to phosphatidylcholine/Chol liposomes. Cell surface labeling of PlyA2-EGFP was abolished after sphingomyelinase as well as methyl-β-cyclodextrin treatment, removing SM and Chol, respectively, indicating that PlyA2-EGFP specifically binds cell surface SM/Chol rafts. Tryptophan to alanine point mutation of PlyA2 revealed the importance of C-terminal tryptophan residues for SM/Chol binding. Our results indicate that PlyA2-EGFP is a novel protein probe to label SM/Chol lipid domains both in cell and model membranes.
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Affiliation(s)
- Hema Balakrishna Bhat
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
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207
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Bennett WD, Tieleman DP. Computer simulations of lipid membrane domains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1765-76. [DOI: 10.1016/j.bbamem.2013.03.004] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/28/2013] [Accepted: 03/01/2013] [Indexed: 10/27/2022]
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208
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Prakash P, Gorfe AA. Lessons from computer simulations of Ras proteins in solution and in membrane. Biochim Biophys Acta Gen Subj 2013; 1830:5211-8. [PMID: 23906604 DOI: 10.1016/j.bbagen.2013.07.024] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND A great deal has been learned over the last several decades about the function of Ras proteins in solution and membrane environments. While much of this knowledge has been derived from a plethora of experimental techniques, computer simulations have also played a substantial role. SCOPE OF REVIEW Our goal here is to summarize the contribution of molecular simulations to our current understanding of normal and aberrant Ras function. We focus on lessons from molecular dynamics simulations in aqueous and membrane environments. MAJOR CONCLUSIONS The central message is that a close interaction between theory and simulation on the one hand and cell-biological, spectroscopic and other experimental approaches on the other has played, and will likely continue to play, a vital role in Ras research. GENERAL SIGNIFICANCE Atomistic insights emerging from detailed simulations of Ras in solution and in bilayers may be the key to unlock the secret that to date prevented development of selective anti-Ras inhibitors for cancer therapy.
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Affiliation(s)
- Priyanka Prakash
- University of Texas Health Science Center at Houston, Department of Integrative Biology and Pharmacology, 6431 Fannin St., Houston, TX 77030, USA
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209
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Sunshine JC, Green JJ. Nanoengineering approaches to the design of artificial antigen-presenting cells. Nanomedicine (Lond) 2013; 8:1173-89. [PMID: 23837856 PMCID: PMC3951141 DOI: 10.2217/nnm.13.98] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Artificial antigen-presenting cells (aAPCs) have shown great initial promise for ex vivo activation of cytotoxic T cells. The development of aAPCs has focused mainly on the choice of proteins to use for surface presentation to T cells when conjugated to various spherical, microscale particles. We review here biomimetic nanoengineering approaches that have been applied to the development of aAPCs that move beyond initial concepts about aAPC development. This article also discusses key technologies that may be enabling for the development of nano- and micro-scale aAPCs with nanoscale features, and suggests several future directions for the field.
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Affiliation(s)
- Joel C Sunshine
- Department of Biomedical Engineering & the Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Jordan J Green
- Department of Biomedical Engineering & the Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
- Wilmer Eye Institute & the Institute for Nanobiotechnology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
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210
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Zhang YH, Khanna R, Nicol GD. Nerve growth factor/p75 neurotrophin receptor-mediated sensitization of rat sensory neurons depends on membrane cholesterol. Neuroscience 2013; 248:562-70. [PMID: 23811397 DOI: 10.1016/j.neuroscience.2013.06.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 06/14/2013] [Accepted: 06/18/2013] [Indexed: 12/31/2022]
Abstract
Nerve growth factor (NGF) is an important mediator in the initiation of the inflammatory response and NGF via activation of the p75 neurotrophin receptor (p75(NTR)) and downstream sphingomyelin signaling leads to significant enhancement of the excitability of small-diameter sensory neurons. Because of the interaction between sphingomyelin and cholesterol in creating membrane liquid-ordered domains known as membrane or lipid rafts, we examined whether neuronal NGF-induced sensitization via p75(NTR) was dependent on the integrity of membrane rafts. Here, we demonstrate that the capacity of NGF to enhance the excitability of sensory neurons may result from the interaction of p75(NTR) with its downstream signaling partner(s) in membrane rafts. Two agents known to disrupt membrane rafts, edelfosine and methyl-β-cyclodextrin (MβCD), block the increase in excitability produced by NGF. In contrast, treatment with MβCD containing saturated amounts of cholesterol does not alter the capacity of NGF to augment excitability. In addition, adding back MβCD with cholesterol restored the NGF-induced sensitization in previously cholesterol-depleted neurons, suggesting that cholesterol and the structural integrity of rafts are key to promoting NGF-mediated sensitization. Using established protocols to isolate detergent-resistant membranes, both p75(NTR) and the neuronal membrane raft marker, flotillin, localize to raft fractions. These results suggest that downstream signaling partners interacting with p75(NTR) in sensory neurons are associated with membrane raft signaling platforms.
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Affiliation(s)
- Y H Zhang
- Department of Pharmacology and Toxicology, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
| | - R Khanna
- Department of Pharmacology and Toxicology, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
| | - G D Nicol
- Department of Pharmacology and Toxicology, School of Medicine, Indiana University, Indianapolis, IN 46202, USA.
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211
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Brown AC, Balashova NV, Epand RM, Epand RF, Bragin A, Kachlany SC, Walters MJ, Du Y, Boesze-Battaglia K, Lally ET. Aggregatibacter actinomycetemcomitans leukotoxin utilizes a cholesterol recognition/amino acid consensus site for membrane association. J Biol Chem 2013; 288:23607-21. [PMID: 23792963 DOI: 10.1074/jbc.m113.486654] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans produces a repeats-in-toxin (RTX) leukotoxin (LtxA) that selectively kills human immune cells. Binding of LtxA to its β2 integrin receptor (lymphocyte function-associated antigen-1 (LFA-1)) results in the clustering of the toxin·receptor complex in lipid rafts. Clustering occurs only in the presence of LFA-1 and cholesterol, and LtxA is unable to kill cells lacking either LFA-1 or cholesterol. Here, the interaction of LtxA with cholesterol was measured using surface plasmon resonance and differential scanning calorimetry. The binding of LtxA to phospholipid bilayers increased by 4 orders of magnitude in the presence of 40% cholesterol relative to the absence of cholesterol. The affinity was specific to cholesterol and required an intact secondary structure. LtxA contains two cholesterol recognition/amino acid consensus (CRAC) sites; CRAC(336) ((333)LEEYSKR(339)) is highly conserved among RTX toxins, whereas CRAC(503) ((501)VDYLK(505)) is unique to LtxA. A peptide corresponding to CRAC(336) inhibited the ability of LtxA to kill Jurkat (Jn.9) cells. Although peptides corresponding to both CRAC(336) and CRAC(503) bind cholesterol, only CRAC(336) competitively inhibited LtxA binding to this sterol. A panel of full-length LtxA CRAC mutants demonstrated that an intact CRAC(336) site was essential for LtxA cytotoxicity. The conservation of CRAC(336) among RTX toxins suggests that this mechanism may be conserved among RTX toxins.
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Affiliation(s)
- Angela C Brown
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania 19104, USA
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212
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Dhingra S, Morita M, Yoda T, Vestergaard MC, Hamada T, Takagi M. Dynamic Morphological Changes Induced By GM1 and Protein Interactions on the Surface of Cell-Sized Liposomes. MATERIALS 2013; 6:2522-2533. [PMID: 28809288 PMCID: PMC5458942 DOI: 10.3390/ma6062522] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 05/25/2013] [Accepted: 05/29/2013] [Indexed: 12/15/2022]
Abstract
It is important to understand the physicochemical mechanisms that are responsible for the morphological changes in the cell membrane in the presence of various stimuli such as osmotic pressure. Lipid rafts are believed to play a crucial role in various cellular processes. It is well established that Ctb (Cholera toxin B subunit) recognizes and binds to GM1 (monosialotetrahexosylganglioside) on the cell surface with high specificity and affinity. Taking advantage of Ctb-GM1 interaction, we examined how Ctb and GM1 molecules affect the dynamic movement of liposomes. GM1 a natural ligand for cholera toxin, was incorporated into liposome and the interaction between fluorescent Ctb and the liposome was analyzed. The interaction plays an important role in determining the various surface interaction phenomena. Incorporation of GM1 into membrane leads to an increase of the line tension leading to either rupture of liposome membrane or change in the morphology of the membrane. This change in morphology was found to be GM1 concentration specific. The interaction between Ctb-GM1 leads to fast and easy rupture or to morphological changes of the liposome. The interactions of Ctb and the glycosyl chain are believed to affect the surface and the curvature of the membrane. Thus, the results are highly beneficial in the study of signal transduction processes.
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Affiliation(s)
- Shruti Dhingra
- School of Material Science, Japan Advanced Institute of Science and Technology, Asahidai Nomi Ishikawa 923-1292, Japan.
| | - Masamune Morita
- School of Material Science, Japan Advanced Institute of Science and Technology, Asahidai Nomi Ishikawa 923-1292, Japan.
| | - Tsuyoshi Yoda
- School of Material Science, Japan Advanced Institute of Science and Technology, Asahidai Nomi Ishikawa 923-1292, Japan.
| | - Mun'delanji C Vestergaard
- School of Material Science, Japan Advanced Institute of Science and Technology, Asahidai Nomi Ishikawa 923-1292, Japan.
| | - Tsutomu Hamada
- School of Material Science, Japan Advanced Institute of Science and Technology, Asahidai Nomi Ishikawa 923-1292, Japan.
| | - Masahiro Takagi
- School of Material Science, Japan Advanced Institute of Science and Technology, Asahidai Nomi Ishikawa 923-1292, Japan.
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213
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Liu YY, Hill RA, Li YT. Ceramide glycosylation catalyzed by glucosylceramide synthase and cancer drug resistance. Adv Cancer Res 2013; 117:59-89. [PMID: 23290777 DOI: 10.1016/b978-0-12-394274-6.00003-0] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Glucosylceramide synthase (GCS), converting ceramide to glucosylceramide, catalyzes the first reaction of ceramide glycosylation in sphingolipid metabolism. This glycosylation by GCS is a critical step regulating the modulation of cellular activities by controlling ceramide and glycosphingolipids (GSLs). An increase of ceramide in response to stresses, such as chemotherapy, drives cells to proliferation arrest and apoptosis or autophagy; however, ceramide glycosylation promptly eliminates ceramide and consequently, these induced processes, thus protecting cancer cells. Further, persistently enhanced ceramide glycosylation can increase GSLs, participating in selecting cancer cells to drug resistance. GCS is overexpressed in diverse drug-resistant cancer cells and in tumors of breast, colon, and leukemia that display poor response to chemotherapy. As ceramide glycosylation by GCS is a rate-limiting step in GSL synthesis, inhibition of GCS sensitizes cancer cells to anticancer drugs and eradicates cancer stem cells. Mechanistic studies indicate that uncoupling ceramide glycosylation can modulate gene expression, decreasing MDR1 through the cSrc/β-catenin pathway and restoring p53 expression via RNA splicing. These studies not only expand our knowledge in understanding how ceramide glycosylation affects cancer cells but also provide novel therapeutic approaches for targeting refractory tumors.
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Affiliation(s)
- Yong-Yu Liu
- Department of Basic Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, LA, USA.
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214
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Konyakhina TM, Wu J, Mastroianni JD, Heberle FA, Feigenson GW. Phase diagram of a 4-component lipid mixture: DSPC/DOPC/POPC/chol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2204-14. [PMID: 23747294 DOI: 10.1016/j.bbamem.2013.05.020] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 05/20/2013] [Accepted: 05/22/2013] [Indexed: 11/15/2022]
Abstract
We report the first 4-component phase diagram for the lipid bilayer mixture, DSPC/DOPC/POPC/chol (distearoylphosphatidylcholine/dioleoylphosphatidylcholine/1-palmitoyl, 2-oleoylphosphatidylcholine/cholesterol). This phase diagram, which has macroscopic Ld+Lo phase domains, clearly shows that all phase boundaries determined for the 3-component mixture containing DOPC transition smoothly into the boundaries for the 3-component mixture containing POPC, which has nanoscopic phase domains of Ld+Lo. Our studies start from two published ternary phase diagrams, and show how these can be combined into a quaternary phase diagram by study of a few hundred samples of intermediate compositions.
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Key Words
- 1,1′-didodecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate
- 1,1′-dieicosanyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate
- 1,2-Dilauroyl-sn-glycero-3-phosphocholine
- 1,2-Dioleoyl-sn-glycero-3-phosphocholine
- 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine
- 1,2-Distearoyl-sn-glycero-3-phosphocholine
- 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
- 1-Stearoyl-2-oleoyl-sn-glycero-3-phosphocholine
- 2-(4,4-Difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine
- 3-Dye method
- 4-Component lipid phase diagram
- BoDIPY-PC
- C12:0-DiI
- C20:0-DiI
- Chol
- Cholesterol
- Competing interaction
- DHE
- DLPC
- DOPC
- DPPC
- DSPC
- Ergosta-5,7,9(11),22-tetraen-3β-ol
- FRET
- Förster resonance energy transfer
- GUV
- Giant unilamellar vesicle
- LHS
- Left hand side refers to left side of phase diagram, i.e. at lower χ(DSPC)
- Lipid raft
- Modulated phase
- PC
- POPC
- Phosphatidylcholine
- Quaternary phase diagram
- REE
- RHS
- RRE
- RSE
- Rapid solvent exchange
- Region of enhanced efficiency
- Region of reduced efficiency
- Right hand side, refers to right side of phase diagram, i.e.,, at higher χ(DSPC)
- SAE
- SM
- SOPC
- Sensitized acceptor emission
- Sphingomyelin
- T1–T6
- TLC
- TOE
- Thin-layer chromatography
- Trajectories 1–6. bSM, sphingomyelin derived from porcine brain
- Trp-Oleoyl Ester, N-oleoyl-dl-tryptophan ethyl ester
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Affiliation(s)
- Tatyana M Konyakhina
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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215
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Kwon H, Lee J, Jeong K, Jang D, Pak Y. A novel actin cytoskeleton-dependent noncaveolar microdomain composed of homo-oligomeric caveolin-2 for activation of insulin signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2176-89. [PMID: 23665048 DOI: 10.1016/j.bbamcr.2013.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 05/01/2013] [Accepted: 05/03/2013] [Indexed: 12/22/2022]
Abstract
The role of caveolin-2 (cav-2), independently of caveolin-1 (cav-1) and caveolae, has remained elusive. Our data show that cav-2 exists in the plasma membrane (PM) in cells lacking cav-1 and forms homo-oligomeric complexes. Cav-2 did not interact with cavin-1 and cavin-2 in the PM. Rab6-GTP was required for the microtubule-dependent exocytic transport of cav-2 from the Golgi to the PM independently of cav-1. The cav-2-oligomerized noncaveolar microdomain was unaffected by cholesterol depletion and protected from shearing of silica-coated PM. Activation of insulin receptor (IR) was processed in the microdomain. Actin depolymerization affected the formation and sustenance of cav-2-oligomerized noncaveolar microdomain and attenuated IR recruitment to the microdomain thereby inhibiting IR signaling activation. Cav-2 shRNA stable cells and the cells ectopically expressing an oligomerization domain truncation mutant, cav-2∆47-86 exhibited retardation of IR signaling activation via the noncaveolar microdomain. Elevation in status of cav-2 expression rendered the noncaveolar activation of IR signaling in cav-1 down-regulated or/and cholesterol-depleted cells. Our findings reveal a novel homo-oligomeric cav-2 microdomain responsible for regulating activation of IR signaling in the PM.
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Affiliation(s)
- Hayeong Kwon
- Department of Biochemistry, Gyeongsang National University, Jinju, Republic of Korea
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216
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Palmieri B, Safran SA. Hybrid lipids increase the probability of fluctuating nanodomains in mixed membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:5246-5261. [PMID: 23530895 DOI: 10.1021/la4006168] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A ternary mixture model is proposed to describe composition fluctuations in mixed membranes composed of saturated, unsaturated, and hybrid lipids (with one saturated and one unsaturated hydrocarbon chain). The hybrids are line-active and can reduce the packing incompatibility between the saturated and unsaturated lipids. We introduce a lattice model that extends previous studies by taking into account the dependence of the interactions of the hybrid lipids on their orientations in a simple way. A methodology to recast the free energy of the lattice model in terms of a continuous, isotropic field theory is proposed and used to analyze composition fluctuations in the one-phase region (above the critical temperature). The effect of hybrid lipids on fluctuation domains rich in saturated/unsaturated lipids is predicted. The correlation length of such fluctuations decreases significantly with increasing amounts of hybrids; this implies that nanoscale fluctuation domains are more probable compared to the case with no hybrids. Smaller correlated fluctuation domains arise even when the temperature is close to a critical point, where very large correlation lengths are normally expected. This decrease in the correlation length is largest as the hybrid composition tends toward a crossover value above which stripelike fluctuations are predicted. This crossover value defines the Lifshitz line. The characteristic wavelength of the stripelike fluctuations is large close to the Lifshitz point but decreases toward a molecular size in a membrane that contains only hybrids. Micrometer size, stripelike domains have recently been observed experimentally in giant unilamelar vesicles (GUVs) made of saturated, unsaturated, and hybrid lipids. These results suggest that the line activity of hybrid lipids in such mixtures may be significant only at large hybrid fractions; in that regime, the interface between domains can be diffuse and several hybrid molecules with correlated orientations can separate saturated and unsaturated lipid regions.
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Affiliation(s)
- Benoit Palmieri
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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217
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Lozano MM, Liu Z, Sunnick E, Janshoff A, Kumar K, Boxer SG. Colocalization of the ganglioside G(M1) and cholesterol detected by secondary ion mass spectrometry. J Am Chem Soc 2013; 135:5620-30. [PMID: 23514537 PMCID: PMC3639293 DOI: 10.1021/ja310831m] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The characterization of the lateral organization of components in biological membranes and the evolution of this arrangement in response to external triggers remain a major challenge. The concept of lipid rafts is widely invoked; however, direct evidence of the existence of these ephemeral entities remains elusive. We report here the use of secondary ion mass spectrometry (SIMS) to image the cholesterol-dependent cohesive phase separation of the ganglioside GM1 into nano- and microscale assemblies in a canonical lipid raft composition of lipids. This assembly of domains was interrogated in a model membrane system composed of palmitoyl sphingomyelin (PSM), cholesterol, and an unsaturated lipid (dioleoylphosphatidylcholine, DOPC). Orthogonal isotopic labeling of every lipid bilayer component and monofluorination of GM1 allowed generation of molecule specific images using a NanoSIMS. Simultaneous detection of six different ion species in SIMS, including secondary electrons, was used to generate ion ratio images whose signal intensity values could be correlated to composition through the use of calibration curves from standard samples. Images of this system provide the first direct, molecule specific, visual evidence for the colocalization of cholesterol and GM1 in supported lipid bilayers and further indicate the presence of three compositionally distinct phases: (1) the interdomain region; (2) micrometer-scale domains (d > 3 μm); (3) nanometer-scale domains (d = 100 nm to 1 μm) localized within the micrometer-scale domains and the interdomain region. PSM-rich, nanometer-scale domains prefer to partition within the more ordered, cholesterol-rich/DOPC-poor/GM1-rich micrometer-scale phase, while GM1-rich, nanometer-scale domains prefer to partition within the surrounding, disordered, cholesterol-poor/PSM-rich/DOPC-rich interdomain phase.
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Affiliation(s)
- Mónica M. Lozano
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Zhao Liu
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155-5813
| | - Eva Sunnick
- Institute of Physical Chemistry, University of Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Andreas Janshoff
- Institute of Physical Chemistry, University of Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Krishna Kumar
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155-5813
- Cancer Center, Tufts Medical Center, Boston, Massachusetts 02110
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
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218
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Davis RS, Sunil Kumar PB, Sperotto MM, Laradji M. Predictions of Phase Separation in Three-Component Lipid Membranes by the MARTINI Force Field. J Phys Chem B 2013; 117:4072-80. [DOI: 10.1021/jp4000686] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Ryan S. Davis
- Department
of Physics, The University of Memphis, Memphis,
Tennessee 38152, United States
| | - P. B. Sunil Kumar
- Department of Physics, Indian Institute of Technology Madras, Chennai- 600 036, India
and MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, 5230 Odense, Denmark
| | - Maria Maddalena Sperotto
- CBS - Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, 2800 Kgs. Lyngby,
Denmark
| | - Mohamed Laradji
- Department
of Physics, The University of Memphis, Memphis,
Tennessee 38152, United States and MEMPHYS - Center for Biomembrane
Physics, University of Southern Denmark, 5230 Odense, Denmark
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219
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Su Z, Shi Y, Xiao Y, Sun M, Ping Q, Zong L, Li S, Niu J, Huang A, You W, Chen Y, Chen X, Fei J, Tian J. Effect of octreotide surface density on receptor-mediated endocytosis in vitro and anticancer efficacy of modified nanocarrier in vivo after optimization. Int J Pharm 2013; 447:281-92. [DOI: 10.1016/j.ijpharm.2013.01.068] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 01/14/2013] [Accepted: 01/30/2013] [Indexed: 02/07/2023]
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220
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Hakobyan D, Heuer A. Phase Separation in a Lipid/Cholesterol System: Comparison of Coarse-Grained and United-Atom Simulations. J Phys Chem B 2013; 117:3841-51. [DOI: 10.1021/jp312245y] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Davit Hakobyan
- Institute of Physical Chemistry, Corrensstr. 28/30, Muenster D-48149,
Germany
| | - Andreas Heuer
- Institute of Physical Chemistry, Corrensstr. 28/30, Muenster D-48149,
Germany
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221
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Jurak M. Thermodynamic Aspects of Cholesterol Effect on Properties of Phospholipid Monolayers: Langmuir and Langmuir–Blodgett Monolayer Study. J Phys Chem B 2013; 117:3496-502. [DOI: 10.1021/jp401182c] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Małgorzata Jurak
- Department of Physical Chemistry - Interfacial Phenomena,
Faculty of Chemistry, Maria Curie-Skłodowska University, Maria Curie-Skłodowska Sq. 3, 20-031 Lublin, Poland
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222
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Biernatowska A, Podkalicka J, Majkowski M, Hryniewicz-Jankowska A, Augoff K, Kozak K, Korzeniewski J, Sikorski AF. The role of MPP1/p55 and its palmitoylation in resting state raft organization in HEL cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1876-84. [PMID: 23507198 DOI: 10.1016/j.bbamcr.2013.03.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 01/31/2013] [Accepted: 03/04/2013] [Indexed: 12/24/2022]
Abstract
Here we show the crucial role of MPP1 in lateral membrane ordering/organization in HEL cells (derived from erythroid precursors). Biochemical analyses showed that inhibition of MPP1 palmitoylation or silencing of the MPP1 gene led to a dramatic decrease in the DRM fraction. This was accompanied by a reduction of membrane order as shown by fluorescence-lifetime imaging microscopy (FLIM) analyses. Furthermore, MPP1 knockdown significantly affects the activation of MAP-kinase signaling via raft-dependent RTK (receptor tyrosine kinase) receptors, indicating the importance of MPP1 for lateral membrane organization. In conclusion, palmitoylation of MPP1 appears to be at least one of the mechanisms controlling lateral organization of the erythroid cell membrane. Thus, this study, together with our recent results on erythrocytes, reported elsewhere (Łach et al., J. Biol. Chem., 2012, 287, 18974-18984), points to a new role for MPP1 and presents a novel linkage between membrane raft organization and protein palmitoylation.
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223
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Monolayer curvature stabilizes nanoscale raft domains in mixed lipid bilayers. Proc Natl Acad Sci U S A 2013; 110:4476-81. [PMID: 23487780 DOI: 10.1073/pnas.1221075110] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
According to the lipid raft hypothesis, biological lipid membranes are laterally heterogeneous and filled with nanoscale ordered "raft" domains, which are believed to play an important role for the organization of proteins in membranes. However, the mechanisms stabilizing such small rafts are not clear, and even their existence is sometimes questioned. Here, we report the observation of raft-like structures in a coarse-grained molecular model for multicomponent lipid bilayers. On small scales, our membranes demix into a liquid ordered (lo) phase and a liquid disordered (ld) phase. On large scales, phase separation is suppressed and gives way to a microemulsion-type state that contains nanometer-sized lo domains in an ld environment. Furthermore, we introduce a mechanism that generates rafts of finite size by a coupling between monolayer curvature and local composition. We show that mismatch between the spontaneous curvatures of monolayers in the lo and ld phases induces elastic interactions, which reduce the line tension between the lo and ld phases and can stabilize raft domains with a characteristic size of the order of a few nanometers. Our findings suggest that rafts in multicomponent bilayers might be closely related to the modulated ripple phase in one-component bilayers.
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224
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Piper-Feldkamp AR, Wegner M, Brzezinski P, Reed SM. Mixtures of supported and hybrid lipid membranes on heterogeneously modified silica nanoparticles. J Phys Chem B 2013; 117:2113-22. [PMID: 23387352 PMCID: PMC3935798 DOI: 10.1021/jp308305y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Simple supported lipid bilayers do not accurately reflect the complex heterogeneity of cellular membranes; however, surface modification makes it possible to tune membrane properties to better mimic biological systems. Here, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (DETAS), a silica modifier, facilitated formation of supported lipid bilayers on silica nanoparticles. Evidence for a stable supported bilayer came from the successful entrapment of a soluble fluorophore within an interstitial water layer. A fluorescence-quenching assay that utilized a pore-forming peptide was used to demonstrate the existence of two separate lipid leaflets. In this assay, fluorescence was quenched by dithionite in roughly equal proportions prior to and after addition of melittin. When a hydrophobic modifier, octadecyltriethoxysilane, was codeposited on the nanoparticles with DETAS, there was a decrease in the amount of supported bilayer on the nanoparticles and an increase in the quantity of hybrid membrane. This allowed for a controlled mixture of two distinct types of membranes on a single substrate, one separated by a water cushion and the other anchored directly on the surface, thereby providing a new mimic of cellular membranes.
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Affiliation(s)
- Aundrea R. Piper-Feldkamp
- Department of Chemistry, University of Colorado Denver, Campus Box 194, P.O. Box 173364, Denver, CO 80217 3364, Office: 303.556.6260, Fax: 303.556.4776,
| | - Maria Wegner
- Department of Biochemistry and Biophysics, Stockholm Univ., Svante Arrhenius väg 16, SE-106 91, Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, Stockholm Univ., Svante Arrhenius väg 16, SE-106 91, Stockholm, Sweden
| | - Scott M. Reed
- Department of Chemistry, University of Colorado Denver, Campus Box 194, P.O. Box 173364, Denver, CO 80217 3364, Office: 303.556.6260, Fax: 303.556.4776,
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225
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Inder KL, Davis M, Hill MM. Ripples in the pond--using a systems approach to decipher the cellular functions of membrane microdomains. MOLECULAR BIOSYSTEMS 2013; 9:330-8. [PMID: 23322173 DOI: 10.1039/c2mb25300c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Membrane microdomains such as lipid rafts and caveolae regulate a myriad of cellular functions including cell signalling, protein trafficking, cell viability, and cell movement. They have been implicated in diseases such as cancer, diabetes and Alzheimer's disease, highlighting the essential role they play in cell processes. Despite much research and debate on the size, composition and dynamics of membrane microdomains, the molecular mechanism(s) of their action remain poorly understood. Most studies have dealt solely with the content and properties of the membrane microdomain as an entity in itself. However, recent work shows that membrane microdomain disruption has wide ranging effects on other subcellular compartments, and the cell as a whole. Hence we propose that a systems approach incorporating many cellular attributes such as subcellular localisation is required in order to understand the global impact of microdomains on cell function. Although analysis of sub-proteome changes already provides additional insight, we further propose biological network analysis of functional proteomics data to capture effects at the systems level. In this review, we highlight the use of protein-protein interactions networks and mixed networks to portray and visualize the relationships between proteins within and between subcellular fractions. Such a systems analysis will be required to improve our understanding of the full cellular function of membrane microdomains.
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226
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McKie AB, Vaughan S, Zanini E, Okon IS, Louis L, de Sousa C, Greene MI, Wang Q, Agarwal R, Shaposhnikov D, Wong JLC, Gungor H, Janczar S, El-Bahrawy M, Lam EWF, Chayen NE, Gabra H. The OPCML tumor suppressor functions as a cell surface repressor-adaptor, negatively regulating receptor tyrosine kinases in epithelial ovarian cancer. Cancer Discov 2013; 2:156-71. [PMID: 22585860 DOI: 10.1158/2159-8290.cd-11-0256] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
UNLABELLED Epithelial ovarian cancer is the leading cause of death from gynecologic malignancy, and its molecular basis is poorly understood. We previously demonstrated that opioid binding protein cell adhesion molecule (OPCML) was frequently epigenetically inactivated in epithelial ovarian cancers, with tumor suppressor function in vitro and in vivo. Here, we further show the clinical relevance of OPCML and demonstrate that OPCML functions by a novel mechanism in epithelial ovarian cancer cell lines and normal ovarian surface epithelial cells by regulating a specific repertoire of receptor tyrosine kinases: EPHA2, FGFR1, FGFR3, HER2, and HER4. OPCML negatively regulates receptor tyrosine kinases by binding their extracellular domains, altering trafficking via nonclathrin-dependent endocytosis, and promoting their degradation via a polyubiquitination-associated proteasomal mechanism leading to signaling and growth inhibition. Exogenous recombinant OPCML domain 1-3 protein inhibited the cell growth of epithelial ovarian cancers cell in vitro and in vivo in 2 murine ovarian cancer intraperitoneal models that used an identical mechanism. These findings demonstrate a novel mechanism of OPCML-mediated tumor suppression and provide a proof-of-concept for recombinant OPCML protein therapy in epithelial ovarian cancers. SIGNIFICANCE The OPCML tumor suppressor negatively regulates a specific spectrum of receptor tyrosine kinases in ovarian cancer cells by binding to their extracellular domain and altering trafficking to a nonclathrin, caveolin-1–associated endosomal pathway that results in receptor tyrosine kinase polyubiquitination and proteasomal degradation. Recombinant OPCML domain 1-3 recapitulates this mechanism and may allow for the implementation of an extracellular tumor-suppressor replacement strategy.
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Affiliation(s)
- Arthur B McKie
- Ovarian Cancer Action Research Centre, Division of Cancer, Imperial College London Hammersmith Campus, London, United Kingdom.
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227
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Baoukina S, Mendez-Villuendas E, Bennett WFD, Tieleman DP. Computer simulations of the phase separation in model membranes. Faraday Discuss 2013; 161:63-75; discussion 113-50. [DOI: 10.1039/c2fd20117h] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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228
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Mueller V, Honigmann A, Ringemann C, Medda R, Schwarzmann G, Eggeling C. FCS in STED microscopy: studying the nanoscale of lipid membrane dynamics. Methods Enzymol 2013; 519:1-38. [PMID: 23280106 DOI: 10.1016/b978-0-12-405539-1.00001-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Details of molecular membrane dynamics in living cells such as lipid-protein interactions or the incorporation of molecules into lipid "rafts" are often hidden to the observer because of the limited spatial resolution of conventional far-field optical microscopy. Fortunately, the superior spatial resolution of far-field stimulated-emission-depletion (STED) nanoscopy allows gaining new insights. Applying fluorescence correlation spectroscopy (FCS) in focal spots continuously tuned down to 30 nm in diameter distinguishes free from anomalous molecular diffusion due to transient binding, as for the diffusion of fluorescent phosphoglycero- and sphingolipid analogs in the plasma membrane of living cells. STED-FCS data recorded at different environmental conditions and on different lipid analogs reveal molecular details of the observed nanoscale trapping. Dependencies on the molecular structure of the lipids point to the distinct connectivity of the various lipids to initiate or assist cellular signaling events, but also outline strong differences to the characteristics of liquid-ordered and disordered phase separation in model membranes. STED-FCS is a highly sensitive and exceptional tool to study the membrane organization by introducing a new class of nanoscale biomolecular studies.
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Affiliation(s)
- Veronika Mueller
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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229
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Abstract
Ras proteins on the plasma membrane are laterally segregated into transient nanoclusters that are essential for high-fidelity signal transmission by the Ras/MAPK cascade. The dynamics of Ras nanocluster assembly and disassembly control MAPK signal output. BRaf inhibitors paradoxically activate CRaf and MAPK signaling in Ras-transformed cells. In our recent study, we showed that BRaf inhibition significantly enhances nanoclustering of oncogenic K- and N-Ras, but not H-Ras by increasing the frequency of Ras nanocluster formation. This disrupted spatiotemporal dynamics of Ras nanocluster fully accounts for the observed effects of Raf inhibitors on Ras signal transmission. Here together with other studies, we propose that the dynamics of Ras nanoclusters may represent a novel target for future therapeutic intervention.
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Affiliation(s)
- Kwang-Jin Cho
- Department of Integrative Biology and Pharmacology, The University of Texas Medical School, Houston, Houston, TX, USA
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230
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Computational Studies of Biomembrane Systems: Theoretical Considerations, Simulation Models, and Applications. FROM SINGLE MOLECULES TO NANOSCOPICALLY STRUCTURED MATERIALS 2013. [DOI: 10.1007/12_2013_258] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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231
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Signalling Complexes: Protein-Protein Interactions and Lipid Rafts. Mol Pharmacol 2012. [DOI: 10.1002/9781118451908.ch11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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232
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Hamada T, Yoshikawa K. Cell-Sized Liposomes and Droplets: Real-World Modeling of Living Cells. MATERIALS 2012. [PMCID: PMC5449011 DOI: 10.3390/ma5112292] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent developments in studies concerning cell-sized vesicles, such as liposomes with a lipid bilayer and water-in-oil droplets covered by a lipid monolayer, aim to realize the real-world modeling of living cells. Compartmentalization with a membrane boundary is essential for the organization of living systems. Due to the relatively large surface/volume ratio in microconfinement, the membrane interface influences phenomena related to biological functions. In this article, we mainly focus on the following subjects: (i) conformational transition of biopolymers in a confined space; (ii) molecular association on the membrane surface; and (iii) remote control of cell-sized membrane morphology.
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Affiliation(s)
- Tsutomu Hamada
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa 923-1292, Japan
- Authors to whom correspondence should be addressed; E-Mails: (T.H.); (K.Y.); Tel./Fax: +81-761-51-1670 (T.H.); +81-774-65-6243 (K.Y.)
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University, 1-3, Tatara Miyakodani, Kyotanabe, Kyoto 610-0394, Japan
- Authors to whom correspondence should be addressed; E-Mails: (T.H.); (K.Y.); Tel./Fax: +81-761-51-1670 (T.H.); +81-774-65-6243 (K.Y.)
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233
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Polley A, Vemparala S, Rao M. Atomistic Simulations of a Multicomponent Asymmetric Lipid Bilayer. J Phys Chem B 2012; 116:13403-10. [DOI: 10.1021/jp3032868] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anirban Polley
- Raman Research Institute, C. V. Raman Avenue, Bangalore 560 080, India
| | | | - Madan Rao
- Raman Research Institute, C. V. Raman Avenue, Bangalore 560 080, India
- National Centre for Biological Sciences (TIFR), Bellary Road, Bangalore
560 065, India
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234
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Cis-9,trans-11-conjugated linoleic acid affects lipid raft composition and sensitizes human colorectal adenocarcinoma HT-29 cells to X-radiation. Biochim Biophys Acta Gen Subj 2012; 1830:2233-42. [PMID: 23116821 DOI: 10.1016/j.bbagen.2012.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 09/29/2012] [Accepted: 10/18/2012] [Indexed: 11/21/2022]
Abstract
BACKGROUND Investigations concerned the mechanism of HT-29 cells radiosensitization by cis-9,trans-11-conjugated linoleic acid (c9,t11-CLA), a natural component of human diet with proven antitumor activity. METHODS The cells were incubated for 24h with 70μM c9,t11-CLA and then X-irradiated. The following methods were used: gas chromatography (incorporation of the CLA isomer), flow cytometry (cell cycle), cloning (survival), Western blotting (protein distribution in membrane fractions), and pulse-field gel electrophoresis (rejoining of DNA double-strand breaks). In parallel, DNA-PK activity, γ-H2AX foci numbers and chromatid fragmentation were estimated. Gene expression was analysed by RT-PCR and chromosomal aberrations by the mFISH method. Nuclear accumulation of the EGF receptor (EGFR) was monitored by ELISA. RESULTS AND CONCLUSIONS C9,t11-CLA sensitized HT-29 cells to X-radiation. This effect was not due to changes in cell cycle progression or DNA-repair-related gene expression. Post-irradiation DSB rejoining was delayed, corresponding with the insufficient DNA-PK activation, although chromosomal aberration frequencies did not increase. Distributions of cholesterol and caveolin-1 in cellular membrane fractions changed. The nuclear EGFR translocation, necessary to increase the DNA-PK activity in response to oxidative stress, was blocked. We suppose that c9,t11-CLA modified the membrane structure, thus disturbing the intracellular EGFR transport and the EGFR-dependent pro-survival signalling, both functionally associated with lipid raft properties. GENERAL SIGNIFICANCE The results point to the importance of the cell membrane interactions with the nucleus after injury inflicted by X -rays. Compounds like c9,t11-CLA, that specifically alter membrane properties, could be used to develop new anticancer strategies.
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235
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Li Z, Janosi L, Gorfe AA. Formation and domain partitioning of H-ras peptide nanoclusters: effects of peptide concentration and lipid composition. J Am Chem Soc 2012; 134:17278-85. [PMID: 22994893 PMCID: PMC3479155 DOI: 10.1021/ja307716z] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Experiments have shown that homologous Ras proteins containing different lipid modification, which is required for membrane binding, form nonoverlapping nanoclusters on the plasma membrane. However, the physical basis for clustering and lateral organization remains poorly understood. We have begun to tackle this issue using coarse-grained molecular dynamics simulations of the H-ras lipid anchor (tH), a triply lipid-modified heptapeptide embedded in a domain-forming mixed lipid bilayer [Janosi L. et al. Proc. Natl. Acad. Sci. U.S.A. 2012, 109, 8097]. Here we use the same simulation approach to investigate the effect of peptide concentration and bilayer composition on the clustering and lateral distribution of tH. We found no major difference in the clustering behavior of tH above a certain concentration. However, the simulations predict the existence of a critical concentration below which tH does not form nanoclusters. Moreover, our data demonstrate that cholesterol enhances the stability of tH nanoclusters but is not required for their formation. Finally, analyses of peptide distributions and partition free energies allowed us to quantitatively describe how clustering facilitates the accumulation of tH at the interface between ordered and disordered domains of the simulated bilayer systems. These thermodynamic insights represent some of the key elements for a comprehensive understanding of the molecular basis for the formation and stability of Ras signaling platforms.
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Affiliation(s)
- Zhenlong Li
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin St., Houston, Texas 77030, USA
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236
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Shi Q, Hou Y, Hou J, Pan P, Liu Z, Jiang M, Gao J, Bai G. Glycyrrhetic acid synergistically enhances β₂-adrenergic receptor-Gs signaling by changing the location of Gαs in lipid rafts. PLoS One 2012; 7:e44921. [PMID: 23028680 PMCID: PMC3459958 DOI: 10.1371/journal.pone.0044921] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/09/2012] [Indexed: 11/26/2022] Open
Abstract
Glycyrrhetic acid (GA) exerts synergistic anti-asthmatic effects via a β2-adrenergic receptor (β2AR)-mediated pathway. Cholesterol is an important component of the structure and function of lipid rafts, which play critical roles in the β2AR-Gs-adenylate cyclase (AC)-mediated signaling pathway. Owing to the structural similarities between GA and cholesterol, we investigated the possibility that GA enhances β2AR signaling by altering cholesterol distribution. Azide-terminal GA (ATGA) was synthesized and applied to human embryonic kidney 293 (HEK293) cells expressing fusion β2AR, and the electron spin resonance (ESR) technique was utilized. GA was determined to be localized predominantly on membrane and decreased their cholesterol contents. Thus, the fluidity of the hydrophobic region increased but not the polar surface of the cell membrane. The conformations of membrane proteins were also changed. GA further changed the localization of Gαs from lipid rafts to non-raft regions, resulting the binding of β2AR and Gαs, as well as in reduced β2AR internalization. Co-localization of β2AR, Gαs, and AC increased isoproterenol-induced cAMP production and cholesterol reloading attenuated this effect. A speculation wherein GA enhances beta-adrenergic activity by increasing the functional linkage between the subcomponents of the membrane β2AR-protein kinase A (PKA) signaling pathway was proposed. The enhanced efficacy of β2AR agonists by this novel mechanism could prevent tachyphylaxis.
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Affiliation(s)
- Qian Shi
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Yuanyuan Hou
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Jie Hou
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Penwei Pan
- College of Life Sciences, Nankai University, Tianjin, China
| | - Ze Liu
- College of Medicine, Nankai University, Tianjin, China
| | - Min Jiang
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Jie Gao
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
| | - Gang Bai
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, China
- * E-mail:
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237
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Sagle LB, Ruvuna LK, Bingham JM, Liu C, Cremer PS, Van Duyne RP. Single plasmonic nanoparticle tracking studies of solid supported bilayers with ganglioside lipids. J Am Chem Soc 2012; 134:15832-9. [PMID: 22938041 PMCID: PMC3526348 DOI: 10.1021/ja3054095] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-particle tracking experiments were carried out with gold nanoparticle-labeled solid supported lipid bilayers (SLBs) containing increasing concentrations of ganglioside (GM(1)). The negatively charged nanoparticles electrostatically associate with a small percentage of positively charged lipids (ethyl phosphatidylcholine) in the bilayers. The samples containing no GM(1) show random diffusion in 92% of the particles examined with a diffusion constant of 4.3(±4.5) × 10(-9) cm(2)/s. In contrast, samples containing 14% GM(1) showed a mixture of particles displaying both random and confined diffusion, with the majority of particles, 62%, showing confined diffusion. Control experiments support the notion that the nanoparticles are not associating with the GM(1) moieties but instead most likely confined to regions in between the GM(1) clusters. Analysis of the root-mean-squared displacement plots for all of the data reveals decreasing trends in the confined diffusion constant and diameter of the confining region versus increasing GM(1) concentration. In addition, a linearly decreasing trend is observed for the percentage of randomly diffusing particles versus GM(1) concentration, which offers a simple, direct way to measure the percolation threshold for this system, which has not previously been measured. The percolation threshold is found to be 22% GM(1) and the confining diameter at the percolation threshold only ∼50 nm.
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Affiliation(s)
- Laura B. Sagle
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, United Sates
| | - Laura K. Ruvuna
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, United Sates
| | - Julia M. Bingham
- Department of Chemistry, Saint Xavier University, 3700 West 103 Street, Chicago, IL 60655, United Sates
| | - Chunming Liu
- Department of Chemistry, Texas A&M University, 3255 TAMU College Station, TX 77843, United Sates
| | - Paul S. Cremer
- Department of Chemistry, Texas A&M University, 3255 TAMU College Station, TX 77843, United Sates
| | - Richard P. Van Duyne
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, United Sates
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238
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Rituper B, Flašker A, Guček A, Chowdhury HH, Zorec R. Cholesterol and regulated exocytosis: A requirement for unitary exocytotic events. Cell Calcium 2012; 52:250-8. [DOI: 10.1016/j.ceca.2012.05.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/07/2012] [Accepted: 05/15/2012] [Indexed: 11/30/2022]
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239
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Hamada T, Morita M, Miyakawa M, Sugimoto R, Hatanaka A, Vestergaard MC, Takagi M. Size-Dependent Partitioning of Nano/Microparticles Mediated by Membrane Lateral Heterogeneity. J Am Chem Soc 2012; 134:13990-6. [DOI: 10.1021/ja301264v] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tsutomu Hamada
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi,
Ishikawa 923-1292, Japan
| | - Masamune Morita
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi,
Ishikawa 923-1292, Japan
| | - Makiyo Miyakawa
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi,
Ishikawa 923-1292, Japan
| | - Ryoko Sugimoto
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi,
Ishikawa 923-1292, Japan
| | - Ai Hatanaka
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi,
Ishikawa 923-1292, Japan
| | - Mun’delanji C. Vestergaard
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi,
Ishikawa 923-1292, Japan
| | - Masahiro Takagi
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi,
Ishikawa 923-1292, Japan
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240
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241
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Petelska AD, Figaszewski ZA. The equilibria of sphingolipid-cholesterol and sphingolipid-sphingolipid in monolayers at the air-water interface. J Membr Biol 2012; 246:13-9. [PMID: 22899351 PMCID: PMC3539074 DOI: 10.1007/s00232-012-9496-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 07/31/2012] [Indexed: 11/26/2022]
Abstract
Monolayers of sphingomyelin (SM), ceramide (Cer) and cholesterol (Ch) and binary mixtures SM–Ch, SM–Cer and Cer–Ch were investigated at the air–water interface. SM, Cer and Ch were used in the experiment. The surface tension values of pure and mixed monolayers were used to calculate π-A isotherms. Surface tension measurements were carried out at 22 °C using a Teflon trough and a Nima 9000 tensiometer. Interactions between sphingolipid and Ch as well as sphingolipid and another sphingolipid result in significant deviations from the additivity rule. An equilibrium theory to describe the behavior of monolayer components at the air–water interface was developed in order to obtain the stability constants and Gibbs free energy values of SM–Ch, SM–Cer and Cer–Ch complexes. We considered the equilibrium between the individual components and the complex and established that sphingolipid and Ch as well as sphingolipid and another sphingolipid formed highly stable 1:1 complexes.
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Affiliation(s)
- Aneta Dorota Petelska
- Institute of Chemistry, University of Bialystok, Al. J. Pilsudskiego 11/4, 15-443 Białystok, Poland.
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242
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Blachutzik JO, Demir F, Kreuzer I, Hedrich R, Harms GS. Methods of staining and visualization of sphingolipid enriched and non-enriched plasma membrane regions of Arabidopsis thaliana with fluorescent dyes and lipid analogues. PLANT METHODS 2012; 8:28. [PMID: 22867517 PMCID: PMC3544639 DOI: 10.1186/1746-4811-8-28] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 07/20/2012] [Indexed: 05/19/2023]
Abstract
UNLABELLED BACKGROUND Sterols and Sphingolipids form lipid clusters in the plasma membranes of cell types throughout the animal and plant kingdoms. These lipid domains provide a medium for protein signaling complexes at the plasma membrane and are also observed to be principal regions of membrane contact at the inception of infection. We visualized different specific fluorescent lipophilic stains of the both sphingolipid enriched and non-sphingolipid enriched regions in the plasma membranes of live protoplasts of Arabidopsis thaliana. RESULTS Lipid staining protocols for several fluorescent lipid analogues in plants are presented. The most emphasis was placed on successful protocols for the single and dual staining of sphingolipid enriched regions and exclusion of sphingolipid enriched regions on the plasma membrane of Arabidopsis thaliana protoplasts. A secondary focus was placed to ensure that these staining protocols presented still maintain cell viability. Furthermore, the protocols were successfully tested with the spectrally sensitive dye Laurdan. CONCLUSION Almost all existing staining procedures of the plasma membrane with fluorescent lipid analogues are specified for animal cells and tissues. In order to develop lipid staining protocols for plants, procedures were established with critical steps for the plasma membrane staining of Arabidopsis leaf tissue and protoplasts. The success of the plasma membrane staining protocols was additionally verified by measurements of lipid dynamics by the fluorescence recovery after photobleaching technique and by the observation of new phenomena such as time dependent lipid polarization events in living protoplasts, for which a putative physiological relevance is suggested.
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Affiliation(s)
- Jörg O Blachutzik
- Institute for Molecular Plant Physiology and Biophysics, University Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
- Microscopy Group, Rudolf Virchow Center, University of Würzburg, Josef Schneider Str. 2, D15, D-97080, Würzburg, Germany
| | - Fatih Demir
- Institute for Molecular Plant Physiology and Biophysics, University Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
- Present address: Institute of Neuro- and Sensory Physiology, Düsseldorf University Hospital, Universitätsstr. 1, D-40225, Düsseldorf, Germany
| | - Ines Kreuzer
- Institute for Molecular Plant Physiology and Biophysics, University Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
| | - Gregory S Harms
- Microscopy Group, Rudolf Virchow Center, University of Würzburg, Josef Schneider Str. 2, D15, D-97080, Würzburg, Germany
- Departments of Biology and Physics, Wilkes University, 84 W. South St., Wilkes-Barre, PA 18766, USA
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243
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Kulma M, Kwiatkowska K, Sobota A. Raft coalescence and FcγRIIA activation upon sphingomyelin clustering induced by lysenin. Cell Signal 2012; 24:1641-7. [DOI: 10.1016/j.cellsig.2012.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 04/12/2012] [Accepted: 04/12/2012] [Indexed: 12/13/2022]
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244
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Yeast as a model system for studying lipid homeostasis and function. FEBS Lett 2012; 586:2858-67. [DOI: 10.1016/j.febslet.2012.07.033] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 07/11/2012] [Indexed: 12/14/2022]
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245
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Krager KJ, Sarkar M, Twait EC, Lill NL, Koland JG. A novel biotinylated lipid raft reporter for electron microscopic imaging of plasma membrane microdomains. J Lipid Res 2012; 53:2214-2225. [PMID: 22822037 DOI: 10.1194/jlr.d026468] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The submicroscopic spatial organization of cell surface receptors and plasma membrane signaling molecules is readily characterized by electron microscopy (EM) via immunogold labeling of plasma membrane sheets. Although various signaling molecules have been seen to segregate within plasma membrane microdomains, the biochemical identity of these microdomains and the factors affecting their formation are largely unknown. Lipid rafts are envisioned as submicron membrane subdomains of liquid ordered structure with differing lipid and protein constituents that define their specific varieties. To facilitate EM investigation of inner leaflet lipid rafts and the localization of membrane proteins therein, a unique genetically encoded reporter with the dually acylated raft-targeting motif of the Lck kinase was developed. This reporter, designated Lck-BAP-GFP, incorporates green fluorescent protein (GFP) and biotin acceptor peptide (BAP) modules, with the latter allowing its single-step labeling with streptavidin-gold. Lck-BAP-GFP was metabolically biotinylated in mammalian cells, distributed into low-density detergent-resistant membrane fractions, and was readily detected with avidin-based reagents. In EM images of plasma membrane sheets, the streptavidin-gold-labeled reporter was clustered in 20-50 nm microdomains, presumably representative of inner leaflet lipid rafts. The utility of the reporter was demonstrated in an investigation of the potential lipid raft localization of the epidermal growth factor receptor.
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Affiliation(s)
- Kimberly J Krager
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA 52242; Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AK 72205; and
| | - Mitul Sarkar
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Erik C Twait
- Department of Surgery, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Nancy L Lill
- Department of Pathology and the OSU Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210
| | - John G Koland
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA 52242.
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246
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Ziblat R, Fargion I, Leiserowitz L, Addadi L. Spontaneous formation of two-dimensional and three-dimensional cholesterol crystals in single hydrated lipid bilayers. Biophys J 2012; 103:255-64. [PMID: 22853903 DOI: 10.1016/j.bpj.2012.05.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 04/24/2012] [Accepted: 05/16/2012] [Indexed: 01/23/2023] Open
Abstract
Grazing incidence x-ray diffraction measurements were performed on single hydrated bilayers and monolayers of Ceramide/Cholesterol/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocyholine at varying concentrations. There are substantial differences in the phase and structure behavior of the crystalline domains formed within the bilayers relative to the corresponding monolayers, due to interactions between the opposing lipid leaflets. Depending on the lipid composition, these interactions lead to phase separation and formation of cholesterol crystals. The cholesterol and ceramide/cholesterol mixed phases were further characterized at 37°C by immunolabeling with specific antibodies recognizing ordered molecular arrays of cholesterol. Previous studies have shown that cholesterol may nucleate in artificial membranes to form thick two-dimensional bilayer crystals. The study herein demonstrates further growth of cholesterol into three-dimensional crystals. We believe that these results may provide further insight into the formation of cholesterol crystals in early stages of atherosclerosis inflammation.
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Affiliation(s)
- Roy Ziblat
- WYSS Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, USA.
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247
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Olivera-Couto A, Aguilar PS. Eisosomes and plasma membrane organization. Mol Genet Genomics 2012; 287:607-20. [DOI: 10.1007/s00438-012-0706-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 06/29/2012] [Indexed: 12/16/2022]
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248
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Hogue IB, Llewellyn GN, Ono A. Dynamic Association between HIV-1 Gag and Membrane Domains. Mol Biol Int 2012; 2012:979765. [PMID: 22830021 PMCID: PMC3399408 DOI: 10.1155/2012/979765] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Accepted: 06/01/2012] [Indexed: 12/18/2022] Open
Abstract
HIV-1 particle assembly is driven by the structural protein Gag. Gag binds to and multimerizes on the inner leaflet of the plasma membrane, eventually resulting in formation of spherical particles. During virus spread among T cells, Gag accumulates to the plasma membrane domain that, together with target cell membrane, forms a cell junction known as the virological synapse. While Gag association with plasma membrane microdomains has been implicated in virus assembly and cell-to-cell transmission, recent studies suggest that, rather than merely accumulating to pre-existing microdomains, Gag plays an active role in reorganizing the microdomains via its multimerization activity. In this paper, we will discuss this emerging view of Gag microdomain interactions. Relationships between Gag multimerization and microdomain association will be further discussed in the context of Gag localization to T-cell uropods and virological synapses.
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Affiliation(s)
- Ian B. Hogue
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - G. Nicholas Llewellyn
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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249
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Yoda T, Vestergaard MC, Hamada T, Le PTM, Takagi M. Thermo-induced Vesicular Dynamics of Membranes Containing Cholesterol Derivatives. Lipids 2012; 47:813-20. [DOI: 10.1007/s11745-012-3695-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 06/08/2012] [Indexed: 10/28/2022]
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250
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Triffo SB, Huang HH, Smith AW, Chou ET, Groves JT. Monitoring lipid anchor organization in cell membranes by PIE-FCCS. J Am Chem Soc 2012; 134:10833-42. [PMID: 22631607 PMCID: PMC3626236 DOI: 10.1021/ja300374c] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study examines the dynamic co-localization of lipid-anchored fluorescent proteins in living cells using pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS) and fluorescence lifetime analysis. Specifically, we look at the pairwise co-localization of anchors from lymphocyte cell kinase (LCK: myristoyl, palmitoyl, palmitoyl), RhoA (geranylgeranyl), and K-Ras (farnesyl) proteins in different cell types. In Jurkat cells, a density-dependent increase in cross-correlation among RhoA anchors is observed, while LCK anchors exhibit a more moderate increase and broader distribution. No correlation was detected among K-Ras anchors or between any of the different anchor types studied. Fluorescence lifetime data reveal no significant Förster resonance energy transfer in any of the data. In COS 7 cells, minimal correlation was detected among LCK or RhoA anchors. Taken together, these observations suggest that some lipid anchors take part in anchor-specific co-clustering with other existing clusters of native proteins and lipids in the membrane. Importantly, these observations do not support a simple interpretation of lipid anchor-mediated organization driven by partitioning based on binary lipid phase separation.
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Affiliation(s)
- Sara B Triffo
- Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, California 94720, USA
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