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Chen X, Yang Q, Kong W, Ge Y, He J, Yan A, Li D. High spatial-resolved heat manipulating membrane heterogeneity alters cellular migration and signaling. Proc Natl Acad Sci U S A 2023; 120:e2312603120. [PMID: 37983503 PMCID: PMC10691225 DOI: 10.1073/pnas.2312603120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/23/2023] [Indexed: 11/22/2023] Open
Abstract
Plasma membrane heterogeneity is a key biophysical regulatory principle of membrane protein dynamics, which further influences downstream signal transduction. Although extensive biophysical and cell biology studies have proven membrane heterogeneity is essential to cell fate, the direct link between membrane heterogeneity regulation to cellular function remains unclear. Heterogeneous structures on plasma membranes, such as lipid rafts, are transiently assembled, thus hard to study via regular techniques. Indeed, it is nearly impossible to perturb membrane heterogeneity without changing plasma membrane compositions. In this study, we developed a high-spatial resolved DNA-origami-based nanoheater system with specific lipid heterogeneity targeting to manipulate the local lipid environmental temperature under near-infrared (NIR) laser illumination. Our results showed that the targeted heating of the local lipid environment influences the membrane thermodynamic properties, which further triggers an integrin-associated cell migration change. Therefore, the nanoheater system was further applied as an optimized therapeutic agent for wound healing. Our strategy provides a powerful tool to dynamically manipulate membrane heterogeneity and has the potential to explore cellular function through changes in plasma membrane biophysical properties.
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Affiliation(s)
- Xiaoqing Chen
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai200241, China
| | - Qianyun Yang
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai200241, China
| | - Wenyan Kong
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai201210, China
| | - Yifan Ge
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai201210, China
| | - Jie He
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai200241, China
| | - An Yan
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai200241, China
| | - Di Li
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai200241, China
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Zamora-Prieto RM, Maldonado-Serrano JF, González-Calderón W. The life of the cell membrane: A paradigmatic reading from Deleuze and Guattari. Heliyon 2023; 9:e21924. [PMID: 38045203 PMCID: PMC10692771 DOI: 10.1016/j.heliyon.2023.e21924] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 09/12/2023] [Accepted: 10/31/2023] [Indexed: 12/05/2023] Open
Abstract
While the Fluid Mosaic model (FMM) is widely accepted as an account of the cell membrane's structure-function, its inability to explain certain phenomena has led to the lipid rafts hypothesis (nanodomains) that spontaneous spatiotemporal enriched zones of sphingolipids-cholesterol-protein exist within the membrane. In this text, we propose a novel approach that conceives the cell membrane as a living entity. The questions regarding the FMM revolve around the fact that, although these molecular components are present in many cell types, the membrane does not react in the same way to every external agent; for example, a virus evokes a particular response: why is there some marked specificity of virus (or toxin) attack on one (or some) of these cell types and not to other cell types that nevertheless have a similar membrane protein constitution? The crucial question, to explain this selectivity, would be what determines the specificity of attack on some cells and not others? While FMN assumes a dynamism between macrostates at the intramolecular, intermolecular, and/or collective levels in the membrane, the approach of the lipid raft model presupposes a much greater and more complex dynamics of microstates (even nano-states) of these molecular components. In other words, it implies higher and instantaneous mobility as assemblages ("intentional") and thus, of the membrane itself (as a collective), in response to changes in the internal and external physicochemical environment over a broad spatiotemporal scale. This suggests a mechanism of membrane adaptation in the face of evolutionary constraints. In this text, we propose a paradigmatic approach, from Deleuze-Guattari's philosophy: to conceive the cell membrane as living and not as a mere molecular conglomerate with particular functions and mechanical processes between molecules. For this, we employ the functional concepts of territory and machinic assemblage, whence the vitality of the membrane would allow us to postulate instantaneous updates, within wider spatiotemporal scales in its composition in contrast with the model that dominates as a more plausible explanation nowadays, that does not include smaller spatiotemporal events. If we resort to the concept of territory and its different media components, we could offer a more plausible explanation of the vigorous dynamism in the composition of the cell membrane since it would allow more subtle and complex differentiations between media and thus make visible the constant and instant changes. We propose that the model of nanodomains, understood as a process of dynamic territorialization, offers a more complex and subtle explanation of the instantaneous changes in the cell membrane's composition. This approach expands the explanatory framework for cellular phenomena and reveals their spatiotemporal complexity in accordance with other research.
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Affiliation(s)
- Rafael Maria Zamora-Prieto
- Facultad de Ciencias de la Salud, Universidad Autónoma de Bucaramanga - UNAB, Bucaramanga, 681003, Colombia
| | | | - William González-Calderón
- Departamento de Ciencias Básicas, Universidad Autónoma de Bucaramanga - UNAB, Bucaramanga, 681003, Colombia
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Effects of periodic mechanical stress on cytoskeleton dependent lipid raft-induced integrin ɑ1 activation in rat nucleus pulposus cells. J Mol Histol 2023; 54:67-75. [PMID: 36719565 PMCID: PMC9908706 DOI: 10.1007/s10735-023-10112-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 01/05/2023] [Indexed: 02/01/2023]
Abstract
Extracellular matrix (ECM) production and nucleus pulposus (NP) cell migration increase under periodic mechanical stress (PMS), but the underpinning regulatory mechanism remains unclear. This work aimed to examine the regulatory effects of cytoskeleton-lipid raft-integrin α1 signaling in NP cells exposed to PMS. Briefly, In NP cells, cytoskeleton rearrangement, lipid raft aggregation and integrin α1 expression in the stress and control groups were assessed by immunofluorescent staining and immunoblot. In addition, cell migration and ECM gene expression were detected by a scratch test and quantitative reverse transcription polymerase chain reaction (qRT‑PCR), respectively. As a result, PMS up-regulated ECM gene expression and enhanced NP cell migration (both P < 0.05), accompanied by increased integrin α1, lipid raft, caveolin-3, F-actin and β-tubulin amounts. Pretreatment with the lipid raft inhibitor methyl-β-cyclodextrin (MβCD) or small interfering RNA (siRNA) targeting caveolin-3 resulted in decreased ECM mRNA synthesis and cell migration induced by PMS (both P < 0.05); meanwhile, integrin α1 expression was also reduced. F-actin and β-tubulin inhibition by cytochalasin D and colchicine, respectively, not only reduced ECM mRNA synthesis and cell migration (both P < 0.05), but also disrupted lipid raft and caveolin-3 amount increases induced by PMS in NP cells. In conclusion, PMS promotes ECM mRNA up-regulation and cell migration through the cytoskeleton-lipid raft-integrin α1 signaling pathway, inhibiting cytoskeleton and lipid rafts could block the cellular effects.
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Wang Y, Zhang Y, Zhang C, Hu M, Yan Q, Zhao H, Zhang X, Wu Y. Cholesterol-Rich Lipid Rafts in the Cellular Membrane Play an Essential Role in Avian Reovirus Replication. Front Microbiol 2020; 11:597794. [PMID: 33224131 PMCID: PMC7667042 DOI: 10.3389/fmicb.2020.597794] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 10/09/2020] [Indexed: 01/07/2023] Open
Abstract
Cholesterol is an essential component of lipid rafts in cellular plasma membranes. Although lipid rafts have been reported to have several functions in multiple stages of the life cycles of many different enveloped viruses, the mechanisms by which non-enveloped viruses, which lack outer lipid membranes, infect host cells remain unclear. In this study, to investigate the dependence of non-enveloped avian reovirus (ARV) infection on the integrity of cholesterol-rich membrane rafts, methyl-β-cyclodextrin (MβCD) was used to deplete cellular membrane cholesterol at the ARV attachment, entry, and post-entry stages. Treatment with MβCD significantly inhibited ARV replication at both the entry and post-entry stages in a dose-dependent manner, but MβCD had a statistically insignificant effect when it was added at the attachment stage. Moreover, MβCD treatment markedly reduced syncytium formation, which occurs at a relatively late stage of the ARV life cycle and is involved in cell-cell transmission and release. Furthermore, the addition of exogenous cholesterol reversed the effects mentioned above. Colocalization data also showed that the ARV proteins σC, μNS, and p10 prefer to localize to cholesterol-rich lipid raft regions during ARV infection. Altogether, these results suggest that cellular cholesterol in lipid rafts plays a critical role in ARV replication.
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Affiliation(s)
- Yuyang Wang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
- Testing Center, Yangzhou University, Yangzhou, China
| | - Yangyang Zhang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Chengcheng Zhang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Maozhi Hu
- Testing Center, Yangzhou University, Yangzhou, China
| | - Qiuxiang Yan
- Testing Center, Yangzhou University, Yangzhou, China
| | - Hongyan Zhao
- Testing Center, Yangzhou University, Yangzhou, China
| | - Xiaorong Zhang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Yantao Wu
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
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Hydrophobic matching of HIV-1 Vpu transmembrane helix-helix interactions is optimized for subcellular location. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:183022. [PMID: 31302078 DOI: 10.1016/j.bbamem.2019.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 06/06/2019] [Accepted: 07/09/2019] [Indexed: 11/21/2022]
Abstract
The HIV-1 accessory protein Vpu mediates the downregulation of several host cell proteins, an activity that is critical for viral replication in vivo. As the first step in directing cell-surface proteins to internal cellular compartments, and in many cases degradation, Vpu binds a subset of its target proteins through their transmembrane domains. Each of the known targets of Vpu are synthesized in the ER, and must traverse the different membrane environments found along the secretory pathway, thus it is important to consider how membrane composition might influence the interactions between Vpu and its targets. We have used Förster resonance energy transfer (FRET) to measure the oligomerization of Vpu with the transmembrane domains of target proteins in model membranes of varying lipid composition. Our data show that both lipid bilayer thickness and acyl chain order can significantly influence monomer-oligomer equilibria within the Vpu-target system. Changes in oligomerization levels were found to be non-specific with no single Vpu-target interaction being favored under any condition. Our analysis of the influence of the membrane environment on the strength of helix-helix interactions between Vpu and its targets in vitro suggests that the strength of Vpu-target interactions in vivo will be partially dependent on the membrane environment found in specific membrane compartments.
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Nakagawa T, Takahashi C, Matsuzaki H, Kuroda Y, Higashi H. Regulation of membrane raft recruitment of the bradykinin B2 receptor by close association with the ATP/UTP receptor P2Y 2. Biochem Biophys Res Commun 2018; 505:36-39. [PMID: 30236981 DOI: 10.1016/j.bbrc.2018.09.072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 09/12/2018] [Indexed: 10/28/2022]
Abstract
Several G protein-coupled receptors are present in lipid rafts. We have shown that most of the P2Y2 receptor (P2Y2R) protein is fractionated into lipid rafts in COS 7 cells. In the same cells, about 25-30% of the bradykinin B2 receptor (B2R) protein is also fractionated into lipid rafts. When both P2Y2R and B2R are co-expressed, the distribution of P2Y2R remained unchanged, but more B2R shifted into the raft fraction. This indicates that the interaction between both receptors recruited B2R into the lipid rafts. After 15 min of UTP stimulation, both receptors almost completely disappeared from the cell surface by endocytosis as observed with a confocal fluorescence microscope. Furthermore, with bradykinin stimulation for 15 min, portions of both receptors disappeared from the cell surface and were endocytosed. As we reported previously with both CHO-K1 cells and HEK 293 cells, continuous stimulation of COS7 cells with GT1b and CSC resulted in the disappearance of both P2Y2R and B2R from the cell membrane surface. Thus, both P2Y2R and B2R migrate into membrane rafts and are endocytosed in parallel with signal crosstalk, clearly indicating that both closely interact on membrane rafts. The P2Y2R N-glycosylation deficient mutant does not migrate to the cell surface. It remains predominantly in the endoplasmic reticulum and is fractionated into raft fractions. In the presence of this glycosylation mutant, most of B2R remains in the endoplasmic reticulum, and is fractionated into the raft fraction. These findings demonstrate that in the membrane rafts of the endoplasmic reticulum, both receptors are already closely associated, and B2R shifts into the rafts by affinity with P2Y2R.
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Affiliation(s)
- Tetsuto Nakagawa
- Division of Glyco-Signal Research, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981-8558, Japan
| | - Chihiro Takahashi
- Division of Glyco-Signal Research, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981-8558, Japan
| | - Hitomi Matsuzaki
- Division of Glyco-Signal Research, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981-8558, Japan
| | - Yoshiyuki Kuroda
- Division of Glyco-Signal Research, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981-8558, Japan
| | - Hideyoshi Higashi
- Division of Glyco-Signal Research, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, 981-8558, Japan.
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Sych T, Mély Y, Römer W. Lipid self-assembly and lectin-induced reorganization of the plasma membrane. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170117. [PMID: 29632269 PMCID: PMC5904303 DOI: 10.1098/rstb.2017.0117] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2018] [Indexed: 01/10/2023] Open
Abstract
The plasma membrane represents an outstanding example of self-organization in biology. It plays a vital role in protecting the integrity of the cell interior and regulates meticulously the import and export of diverse substances. Its major building blocks are proteins and lipids, which self-assemble to a fluid lipid bilayer driven mainly by hydrophobic forces. Even if the plasma membrane appears-globally speaking-homogeneous at physiological temperatures, the existence of specialized nano- to micrometre-sized domains of raft-type character within cellular and synthetic membrane systems has been reported. It is hypothesized that these domains are the origin of a plethora of cellular processes, such as signalling or vesicular trafficking. This review intends to highlight the driving forces of lipid self-assembly into a bilayer membrane and the formation of small, transient domains within the plasma membrane. The mechanisms of self-assembly depend on several factors, such as the lipid composition of the membrane and the geometry of lipids. Moreover, the dynamics and organization of glycosphingolipids into nanometre-sized clusters will be discussed, also in the context of multivalent lectins, which cluster several glycosphingolipid receptor molecules and thus create an asymmetric stress between the two membrane leaflets, leading to tubular plasma membrane invaginations.This article is part of the theme issue 'Self-organization in cell biology'.
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Affiliation(s)
- Taras Sych
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, Schänzlestraße 18, 79104 Freiburg, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch Cedex, France
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch Cedex, France
| | - Winfried Römer
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, Schänzlestraße 18, 79104 Freiburg, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
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Motegi T, Yamazaki K, Ogino T, Tero R. Substrate-Induced Structure and Molecular Dynamics in a Lipid Bilayer Membrane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:14748-14755. [PMID: 29236511 DOI: 10.1021/acs.langmuir.7b03212] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The solid-substrate-dependent structure and dynamics of molecules in a supported lipid bilayer (SLB) were directly investigated via atomic force microscopy (AFM) and single particle tracking (SPT) measurements. The appearance of either vertical or horizontal heterogeneities in the SLB was found to be strongly dependent on the underlying substrates. SLB has been widely used as a biointerface with incorporated proteins and other biological materials. Both silica and mica are popular substrates for SLB. Using single-molecule dynamics, the fluidity of the upper and lower membrane leaflets was found to depend on the substrate, undergoing coupling and decoupling on the SiO2/Si and mica substrates, respectively. The anisotropic diffusion caused by the locally destabilized structure of the SLB at atomic steps appeared on the Al2O3(0001) substrate because of the strong van der Waals interaction between the SLB and the substrate. Our finding that the well-defined surfaces of mica and sapphire result in asymmetry and anisotropy in the plasma membrane is useful for the design of new plasma-membrane-mimetic systems. The application of well-defined supporting substrates for SLBs should have similar effects as cell membrane scaffolds, which regulate the dynamic structure of the membrane.
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Affiliation(s)
| | - Kenji Yamazaki
- Division of Applied Physics, Graduate School of Engineering, Hokkaido University , Sapporo 060-8628, Japan
| | - Toshio Ogino
- Department of Engineering, Yokohama National University , Yokohama 240-8501, Japan
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Chiapparino A, Maeda K, Turei D, Saez-Rodriguez J, Gavin AC. The orchestra of lipid-transfer proteins at the crossroads between metabolism and signaling. Prog Lipid Res 2015; 61:30-9. [PMID: 26658141 DOI: 10.1016/j.plipres.2015.10.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/15/2015] [Indexed: 01/12/2023]
Abstract
Within the eukaryotic cell, more than 1000 species of lipids define a series of membranes essential for cell function. Tightly controlled systems of lipid transport underlie the proper spatiotemporal distribution of membrane lipids, the coordination of spatially separated lipid metabolic pathways, and lipid signaling mediated by soluble proteins that may be localized some distance away from membranes. Alongside the well-established vesicular transport of lipids, non-vesicular transport mediated by a group of proteins referred to as lipid-transfer proteins (LTPs) is emerging as a key mechanism of lipid transport in a broad range of biological processes. More than a hundred LTPs exist in humans and these can be divided into at least ten protein families. LTPs are widely distributed in tissues, organelles and membrane contact sites (MCSs), as well as in the extracellular space. They all possess a soluble and globular domain that encapsulates a lipid monomer and they specifically bind and transport a wide range of lipids. Here, we present the most recent discoveries in the functions and physiological roles of LTPs, which have expanded the playground of lipids into the aqueous spaces of cells.
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Affiliation(s)
- Antonella Chiapparino
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Kenji Maeda
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Denes Turei
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany; European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge CB10 1SD, UK
| | - Julio Saez-Rodriguez
- European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge CB10 1SD, UK
| | - Anne-Claude Gavin
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany; European Molecular Biology Laboratory (EMBL), Molecular Medicine Partnership Unit (MMPU), Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
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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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Le Guillou J, Ropers MH, Gaillard C, David-Briand E, Desherces S, Schmitt E, Bencharif D, Amirat-Briand L, Tainturier D, Anton M. Organization of lipids in the artificial outer membrane of bull spermatozoa reconstructed at the air–water interface. Colloids Surf B Biointerfaces 2013; 108:246-54. [DOI: 10.1016/j.colsurfb.2013.02.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 02/15/2013] [Accepted: 02/22/2013] [Indexed: 10/27/2022]
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12
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Funkhouser CM, Mayer M, Solis FJ, Thornton K. Effects of interleaflet coupling on the morphologies of multicomponent lipid bilayer membranes. J Chem Phys 2013; 138:024909. [DOI: 10.1063/1.4773856] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Picas L, Milhiet PE, Hernández-Borrell J. Atomic force microscopy: a versatile tool to probe the physical and chemical properties of supported membranes at the nanoscale. Chem Phys Lipids 2012. [PMID: 23194897 DOI: 10.1016/j.chemphyslip.2012.10.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Atomic force microscopy (AFM) was developed in the 1980s following the invention of its precursor, scanning tunneling microscopy (STM), earlier in the decade. Several modes of operation have evolved, demonstrating the extreme versatility of this method for measuring the physicochemical properties of samples at the nanoscopic scale. AFM has proved an invaluable technique for visualizing the topographic characteristics of phospholipid monolayers and bilayers, such as roughness, height or laterally segregated domains. Implemented modes such as phase imaging have also provided criteria for discriminating the viscoelastic properties of different supported lipid bilayer (SLB) regions. In this review, we focus on the AFM force spectroscopy (FS) mode, which enables determination of the nanomechanical properties of membrane models. The interpretation of force curves is presented, together with newly emerging techniques that provide complementary information on physicochemical properties that may contribute to our understanding of the structure and function of biomembranes. Since AFM is an imaging technique, some basic indications on how real-time AFM imaging is evolving are also presented at the end of this paper.
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Affiliation(s)
- Laura Picas
- Institut Curie, CNRS UMR 144, 26 rue d'Ulm, 75248 Paris, France
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Simonsson L, Höök F. Formation and diffusivity characterization of supported lipid bilayers with complex lipid compositions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10528-10533. [PMID: 22703549 DOI: 10.1021/la301878r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The moving edge of a hydrodynamically manipulated supported lipid bilayer (SLB) can be used to catalyze SLB formation of adsorbed lipid vesicles that do not undergo spontaneous SLB formation upon adsorption on SiO(2). By removing the lipid reservoir of an initially formed SLB, we show how a hydrodynamically moved SLB patch composed of POPC can be used to form isolated SLBs with compositions that to at least 95% represent that of the adsorbed lipid vesicles. The concept is used to investigate the diffusivity of lissamine rhodamine B 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (rhodamine-DHPE) in SLBs made from complex lipid compositions, revealing a decrease in diffusivity by a factor of 2 when the cholesterol content was increased from 0% to 50%. We also demonstrate how the concept can be used to induce stationary domains in SLBs containing 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and cholesterol (39:21:40 mol %, respectively). Because the method serves as a means to form SLBs with lipid compositions that hamper SLB formation via spontaneous rupture of adsorbed lipid vesicles, it opens up the possibility for new biophysical investigations of SLBs with more nativelike compositions.
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Affiliation(s)
- Lisa Simonsson
- Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden
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15
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Chemical–Physical Changes in Cell Membrane Microdomains of Breast Cancer Cells After Omega-3 PUFA Incorporation. Cell Biochem Biophys 2012; 64:45-59. [DOI: 10.1007/s12013-012-9365-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Palestini P, Botto L, Rivolta I, Miserocchi G. Remodelling of membrane rafts expression in lung cells as an early sign of mechanotransduction-signalling in pulmonary edema. J Lipids 2011; 2011:695369. [PMID: 21785732 PMCID: PMC3139192 DOI: 10.1155/2011/695369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 03/22/2011] [Indexed: 11/17/2022] Open
Abstract
Membrane rafts (MRs) are clusters of lipids, organized in a "quasicrystalline" liquid-order phase, organized on the cell surface and whose pattern of molecules and physicochemical properties are distinct from those of the surrounding plasma membrane. MRs may be considered an efficient and fairly rapid cell-activated mechanism to express or mask surface receptors aimed at triggering specific response pathways. This paper reports observations concerning the role of MRs in the control of lung extravascular water that ought to be kept at minimum to assure gas diffusion, supporting the hypothesis that MRs expression is a potential mechanism of sensing minor changes in the volume of extravascular water. We present the evidence that MRs expression specifically relates to signal-transduction processes evoked by mechanical stimuli arising in the interstitial lung compartment when a small increase in extravascular volume occurs. We further hypothesize that a differential expression of MRs might also reflect the damage to precise components of the extracellular matrix caused by the perturbation in water balance and thus can trigger a molecule-oriented specific matrix remodelling.
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Affiliation(s)
- Paola Palestini
- Department of Experimental Medicine, University of Milano-Bicocca, 48 Via Cadore, 20052 Monza, Italy
| | - Laura Botto
- Department of Experimental Medicine, University of Milano-Bicocca, 48 Via Cadore, 20052 Monza, Italy
| | - Ilaria Rivolta
- Department of Experimental Medicine, University of Milano-Bicocca, 48 Via Cadore, 20052 Monza, Italy
| | - Giuseppe Miserocchi
- Department of Experimental Medicine, University of Milano-Bicocca, 48 Via Cadore, 20052 Monza, Italy
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Dasgupta S, Cushman I, Kpetemey M, Casey PJ, Vishwanatha JK. Prenylated c17orf37 induces filopodia formation to promote cell migration and metastasis. J Biol Chem 2011; 286:25935-46. [PMID: 21628459 DOI: 10.1074/jbc.m111.254599] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Post-translational modification by covalent attachment of isoprenoid lipids (prenylation) regulates the functions and biological activities of several proteins implicated in the oncogenic transformation and metastatic progression of cancer. The largest group of prenylated proteins contains a CAAX motif at the C-terminal that serves as a substrate for a series of post-translational modifications that convert these otherwise hydrophilic proteins to lipidated proteins, thus facilitating membrane association. C17orf37 (chromosome 17 open reading frame 37), also known as C35/Rdx12/MGC14832, located in the 17q12 amplicon, is overexpressed in human cancer, and its expression correlates with the migratory and invasive phenotype of cancer cells. Here we show that C17orf37 contains a functional CAAX motif and is post-translationally modified by protein geranylgeranyltransferase-I (GGTase-I). Geranylgeranylation of C17orf37 at the CAAX motif facilitates association of the protein to the inner leaflet of plasma membrane, enhances migratory phenotype of cells by inducing increased filopodia formation, and potentiates directional migration. A prenylation-deficient mutant of C17orf37 is functionally inactive and fails to trigger dissemination of tail vein-injected cells in a mouse model of metastasis. These findings demonstrate that prenylation is required for the function of the C17orf37 protein in cancer cells and imply that the post-translational modification may functionally regulate metastatic progression of disease.
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Affiliation(s)
- Subhamoy Dasgupta
- Department of Biomedical Sciences and Institute for Cancer Research, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
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18
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Soft X-ray Laser Microscopy of Lipid Rafts towards GPCR-Based Drug Discovery Using Time-Resolved FRET Spectroscopy. Pharmaceuticals (Basel) 2011. [PMCID: PMC4053801 DOI: 10.3390/ph4030524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Many signaling molecules involved in G protein-mediated signal transduction, which are present in the lipid rafts and believed to be controlled spatially and temporally, influence the potency and efficacy of neurotransmitter receptors and transporters. This has focus interest on lipid rafts and the notion that these microdomains acts as a kind of signaling platform and thus have an important role in the expression of membrane receptor-mediated signal transduction, cancer, immune responses, neurotransmission, viral infections and various other phenomena due to specific and efficient signaling according to extracellular stimuli. However, the real structure of lipid rafts has not been observed so far due to its small size and a lack of sufficiently sophisticated observation systems. A soft X-ray microscope using a coherent soft X-ray laser in the water window region (2.3–4.4 nm) should prove to be a most powerful tool to observe the dynamic structure of lipid rafts of several tens of nanometers in size in living cells. We have developed for the X-ray microscope a new compact soft X-ray laser using strongly induced plasma high harmonic resonance. We have also developed a time-resolved highly sensitive fluorescence resonance energy transfer (FRET) system and confirmed protein-protein interactions coupled with ligands. The simultaneous use of these new tools for observation of localization of G-protein coupled receptors (GPCRs) in rafts has become an important and optimum tool system to analyze the dynamics of signal transduction through rafts as signaling platform. New technology to visualize rafts is expected to lead to the understanding of those dynamics and innovative development of drug discovery that targets GPCRs localized in lipid rafts.
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19
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Zeki AA, Kenyon NJ, Goldkorn T. Statin drugs, metabolic pathways, and asthma: a therapeutic opportunity needing further research. Drug Metab Lett 2011; 5:40-4. [PMID: 21198438 PMCID: PMC6082624 DOI: 10.2174/187231211794455217] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 12/14/2010] [Indexed: 01/01/2023]
Abstract
The chance discovery of hydroxymethylglutaryl (HMG)-CoA reductase inhibitors has revolutionized the care of patients with cardiovascular disease. The unexpected finding that these cholesterol-lowering drugs (or 'statins') also possess pleiotropic immunomodulatory properties, has opened a new area of research which investigates the anti-inflammatory and anti-proliferative properties of statins. In this brief commentary, we discuss the potential application of these drugs in asthma, where metabolic pathways pertinent to lung inflammation, in addition to the mevalonate cascade, may be targeted. We review mechanisms of action, discuss the potential therapeutic use of statins in asthma, share some preliminary data from our laboratory, discuss results from recent clinical trials in asthma, and propose a new target asthma subpopulation that could potentially benefit. We conclude our essay by highlighting the mevalonate-dependent and -independent pathways that may be modulated by statins, including the emerging area of cholesterol, sphingolipid, and lipid raft biology in lung disease. In this is an opportunity to develop new treatments for asthma, where innovative therapies are urgently needed to prevent acute exacerbations and alter disease progression.
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Affiliation(s)
- Amir A. Zeki
- University of California, Davis, Department of Internal Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Center for Comparative Respiratory Biology and Medicine (CCRBM)
| | - Nicholas J. Kenyon
- University of California, Davis, Department of Internal Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Center for Comparative Respiratory Biology and Medicine (CCRBM)
| | - Tzipora Goldkorn
- Respiratory Signal Transduction, Genome and Biomedical Sciences Facility (GBSF)
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20
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Ramos J, Cruz VL, Martínez-Salazar J, Campillo NE, Páez JA. Dissimilar interaction of CB1/CB2 with lipid bilayers as revealed by molecular dynamics simulation. Phys Chem Chem Phys 2011; 13:3660-8. [DOI: 10.1039/c0cp01456g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Anbazhagan V, Schneider D. The membrane environment modulates self-association of the human GpA TM domain--implications for membrane protein folding and transmembrane signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1899-907. [PMID: 20603102 DOI: 10.1016/j.bbamem.2010.06.027] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 06/02/2010] [Accepted: 06/25/2010] [Indexed: 10/19/2022]
Abstract
The influence of lipid bilayer properties on a defined and sequence-specific transmembrane helix-helix interaction is not well characterized yet. To study the potential impact of changing bilayer properties on a sequence-specific transmembrane helix-helix interaction, we have traced the association of fluorescent-labeled glycophorin A transmembrane peptides by fluorescence spectroscopy in model membranes with varying lipid compositions. The observed changes of the glycophorin A dimerization propensities in different lipid bilayers suggest that the lipid bilayer thickness severely influences the monomer-dimer equilibrium of this transmembrane domain, and dimerization was most efficient under hydrophobic matching conditions. Moreover, cholesterol considerably promotes self-association of transmembrane helices in model membranes by affecting the lipid acyl chain ordering. In general, the order of the lipid acyl chains appears to be an important factor involved in determining the strength and stability of transmembrane helix-helix interactions. As discussed, the described influences of membrane properties on transmembrane helix-helix interactions are highly important for understanding the mechanism of transmembrane protein folding and functioning as well as for gaining a deeper insight into the regulation of signal transduction via membrane integral proteins by bilayer properties.
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Affiliation(s)
- Veerappan Anbazhagan
- Institut für Pharmazie und Biochemie, Johannes Gutenberg-Universität Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
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22
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Lipid order and molecular assemblies in the plasma membrane of eukaryotic cells. Biochem Soc Trans 2009; 37:1056-60. [PMID: 19754451 DOI: 10.1042/bst0371056] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Multimolecular assemblies on the plasma membrane exhibit dynamic nature and are often generated during the activation of eukaryotic cells. The role of lipids and their physical properties in helping to control the existence of these structures is discussed. Technological improvements for live cell imaging of membrane components are also reviewed.
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23
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Gupta G, Surolia A. Glycosphingolipids in microdomain formation and their spatial organization. FEBS Lett 2009; 584:1634-41. [PMID: 19941856 DOI: 10.1016/j.febslet.2009.11.070] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 11/17/2009] [Accepted: 11/19/2009] [Indexed: 10/20/2022]
Abstract
Plasma membranes regulate the influx and efflux of molecules across themselves and are also responsible for primary signal transduction between cells or within the same cell. Presence of lateral heterogeneity and the ability of reorganization are essential requirements for effective functioning of biomembranes. Lipid rafts are small, heterogeneous, dynamic domains enriched in glycosphingolipids, sphingomyelin and cholesterol, and profoundly influence membrane organization. Glycosphingolipids are inclined towards formation of liquid-ordered phases in membranes, both with and without cholesterol; they are therefore prime players in domain formation. Here, we discuss the role of glycosphingolipids in microdomain formation and their spatial organization within these rafts.
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Affiliation(s)
- Garima Gupta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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24
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Capron A, Gourgues M, Neiva LS, Faure JE, Berger F, Pagnussat G, Krishnan A, Alvarez-Mejia C, Vielle-Calzada JP, Lee YR, Liu B, Sundaresan V. Maternal control of male-gamete delivery in Arabidopsis involves a putative GPI-anchored protein encoded by the LORELEI gene. THE PLANT CELL 2008; 20:3038-49. [PMID: 19028964 PMCID: PMC2613666 DOI: 10.1105/tpc.108.061713] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 10/01/2008] [Accepted: 11/04/2008] [Indexed: 05/18/2023]
Abstract
In Angiosperms, the male gametes are delivered to the female gametes through the maternal reproductive tissue by the pollen tube. Upon arrival, the pollen tube releases the two sperm cells, permitting double fertilization to take place. Although the critical role of the female gametophyte in pollen tube reception has been demonstrated, the underlying mechanisms remain poorly understood. Here, we describe lorelei, an Arabidopsis thaliana mutant impaired in sperm cell release, reminiscent of the feronia/sirène mutant. Pollen tubes reaching lorelei embryo sacs frequently do not rupture but continue to grow in the embryo sac. Furthermore, lorelei embryo sacs continue to attract additional pollen tubes after arrival of the initial pollen tube. The LORELEI gene is expressed in the synergid cells prior to fertilization and encodes a small plant-specific putative glucosylphosphatidylinositol-anchored protein (GAP). These results provide support for the concept of signaling mechanisms at the synergid cell membrane by which the female gametophyte recognizes the arrival of a compatible pollen tube and promotes sperm release. Although GAPs have previously been shown to play critical roles in initiation of fertilization in mammals, flowering plants appear to have independently evolved reproductive mechanisms that use the unique features of these proteins within a similar biological context.
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Affiliation(s)
- Arnaud Capron
- Department of Plant Biology, University of California, Davis, California 95616, USA
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25
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Di Girolamo F, Raggi C, Birago C, Pizzi E, Lalle M, Picci L, Pace T, Bachi A, de Jong J, Janse CJ, Waters AP, Sargiacomo M, Ponzi M. Plasmodium lipid rafts contain proteins implicated in vesicular trafficking and signalling as well as members of the PIR superfamily, potentially implicated in host immune system interactions. Proteomics 2008; 8:2500-13. [PMID: 18563749 DOI: 10.1002/pmic.200700763] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Plasmodium parasites, the causal agents of malaria, dramatically modify the infected erythrocyte by exporting parasite proteins into one or multiple erythrocyte compartments, the cytoplasm and the plasma membrane or beyond. Despite advances in defining signals and specific cellular compartments implicated in protein trafficking in Plasmodium-infected erythrocytes, the contribution of lipid-mediated sorting to this cellular process has been poorly investigated. In this study, we examined the proteome of cholesterol-rich membrane microdomains or lipid rafts, purified from erythrocytes infected by the rodent parasite Plasmodium berghei. Besides structural proteins associated with invasive forms, we detected chaperones, proteins implicated in vesicular trafficking, membrane fusion events and signalling. Interestingly, the raft proteome of mixed P. berghei blood stages included proteins encoded by members of a large family (bir) of putative variant antigens potentially implicated in host immune system interactions and targeted to the surface of the host erythrocytes. The generation of transgenic parasites expressing BIR/GFP fusions confirmed the dynamic association of members of this protein family with membrane microdomains. Our results indicated that lipid rafts in Plasmodium-infected erythrocytes might constitute a route to sort and fold parasite proteins directed to various host cell compartments including the cell surface.
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Affiliation(s)
- Francesco Di Girolamo
- Dipartimento di Malattie Infettive Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Roma, Italy
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26
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Patra SK. Dissecting lipid raft facilitated cell signaling pathways in cancer. Biochim Biophys Acta Rev Cancer 2007; 1785:182-206. [PMID: 18166162 DOI: 10.1016/j.bbcan.2007.11.002] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 11/24/2007] [Accepted: 11/29/2007] [Indexed: 01/09/2023]
Abstract
Cancer is one of the most devastating disorders in our lives. Higher rate of proliferation than death of cells is one of the essential factors for development of cancer. The dynamicity of cell membrane plays some vital roles in cell survival and cell death, including protection, endocytosis, signaling, and increases in mechanical stability during cell division, as well as decrease of shear forces during separation of two cells after division, and cell separation from tissues for cancer metastasis. Within the membrane, there are specialized domains, known as lipid rafts. A raft can coordinate various signaling pathways. Recent data on the proteomics of lipid rafts/caveolae have highlighted the enigmatic role of various signaling proteins in cancer development. Analysis of these data of raft proteome from various tumors, cancer tissues, and cell lines cultured without and with therapeutic agents, as well as from model rafts revealed that there may be two subsets of raft assemblage in cell membrane. One subset of raft is enriched with cholesterol-sphingomyeline-ganglioside-cav-1/Src/EGFR (hereafter, "chol-raft") that is involved in normal cell signaling, and when dysregulated promotes cell transformation and tumor progression; another subset of raft is enriched with ceramide-sphingomyeline-ganglioside-FAS/Ezrin (hereafter, "cer-raft") that generally promotes apoptosis. In view of this, and to focus insight into the cancer cell physiology caused by the lipid rafts mediated signals and their receptors, and the downstream transmitters, either proliferative (for example, EGF and EGFR) or death-inducing (for example, FASL and FAS), and the precise roles of some therapeutic drugs and endogenous acid sphingomylenase in this scenario in in situ transformation of "chol-raft" into "cer-raft" are summarized and discussed in this contribution.
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Affiliation(s)
- Samir Kumar Patra
- Cancer Epigenetics Research, Kalyani (B-7/183), Nadia, West Bengal, India-741235.
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27
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28
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Okada T, Wakabayashi M, Ikeda K, Matsuzaki K. Formation of Toxic Fibrils of Alzheimer’s Amyloid β-Protein-(1–40) by Monosialoganglioside GM1, a Neuronal Membrane Component. J Mol Biol 2007; 371:481-9. [PMID: 17582434 DOI: 10.1016/j.jmb.2007.05.069] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 05/08/2007] [Accepted: 05/21/2007] [Indexed: 10/23/2022]
Abstract
A pathological hallmark of Alzheimer's disease (AD) is the deposition of amyloid beta-protein (Abeta) in fibrillar form on neuronal cells. However, the role of Abeta fibrils in neuronal dysfunction is highly controversial. This study demonstrates that monosialoganglioside GM1 (GM1) released from damaged neurons catalyzes the formation of Abeta fibrils, the toxicity and the cell affinity of which are much stronger than those of Abeta fibrils formed in phosphate-buffered saline. Abeta-(1-40) was incubated with equimolar GM1 at 37 degrees C. After a lag period of 6-12 h, amyloid fibrils were formed, as confirmed by circular dichroism, thioflavin-T fluorescence, size-exclusion chromatography, and transmission electron microscopy. The fibrils showed significant cytotoxicity against PC12 cells differentiated with nerve growth factor. Trisialoganglioside GT1b also facilitated the fibrillization, although the effect was weaker than that of GM1. Our study suggests an exacerbation mechanism of AD and an importance of polymorphisms in Abeta fibrils during the pathogenesis of the disease.
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Affiliation(s)
- Takuma Okada
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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29
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Yuyama K, Sekino-Suzuki N, Sanai Y, Kasahara K. Translocation of activated heterotrimeric G protein Galpha(o) to ganglioside-enriched detergent-resistant membrane rafts in developing cerebellum. J Biol Chem 2007; 282:26392-400. [PMID: 17623667 DOI: 10.1074/jbc.m705046200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The association of gangliosides with specific proteins in the central nervous system was examined by co-immunoprecipitation with an anti-ganglioside antibody. The monoclonal antibody to the ganglioside GD3 immunoprecipitated phosphoproteins of 40, 53, 56, and 80 kDa from the rat cerebellum. Of these proteins, the 40-kDa protein was identified as the alpha-subunit of a heterotrimeric G protein, G(o) (Galpha(o)). Using sucrose density gradient analysis of cerebellar membranes, Galpha(o), but not Gbetagamma, was observed in detergent-resistant membrane (DRM) raft fractions in which GD3 was abundant after the addition of guanosine 5'-O-(thiotriphosphate) (GTPgammaS), which stabilizes G(o) in its active form. On the other hand, both Galpha(o) and Gbetagamma were excluded from the DRM raft fractions in the presence of guanyl-5'-yl thiophosphate, which stabilizes G(o) in its inactive form. Only Galpha(o) was observed in the DRM fractions from the cerebellum on postnatal day 7, but not from that in adult. After pertussis toxin treatment, Galpha(o) was not observed in the DRM fractions, even from the cerebellum on postnatal day 7. These results indicate the activation-dependent translocation of Galpha(o) into the DRM rafts. Furthermore, Galpha(o) was concentrated in the neuronal growth cones. Treatment with stromal cell-derived factor-1alpha, a physiological ligand for the G protein-coupled receptor, stimulated [(35)S]GTPgammaS binding to Galpha(o) and caused Galpha(o) translocation to the DRM fractions and RhoA translocation to the membrane fraction, leading to the growth cone collapse of cerebellar granule neurons. The collapse was partly prevented by pretreatment with the cholesterol-sequestering and raft-disrupting agent methyl-beta-cyclodextrin. These results demonstrate the involvement of signal-dependent Galpha(o) translocation to the DRM in the growth cone behavior of cerebellar granule neurons.
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Affiliation(s)
- Kohei Yuyama
- Biomembrane Signaling Project 2, Tokyo Metropolitan Institute of Medical Science, Tokyo Metropolitan Organization for Medical Research, 3-18-22 Honkomagome Bunkyo-ku, Tokyo, 113-8613 Japan
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30
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Zipp F, Waiczies S, Aktas O, Neuhaus O, Hemmer B, Schraven B, Nitsch R, Hartung HP. Impact of HMG-CoA reductase inhibition on brain pathology. Trends Pharmacol Sci 2007; 28:342-9. [PMID: 17573124 DOI: 10.1016/j.tips.2007.05.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 04/03/2007] [Accepted: 05/25/2007] [Indexed: 11/16/2022]
Abstract
Over the past two decades, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (HMGCRIs), originally designed to lower cholesterol blood levels, have been found to affect GTPase signaling during normal intracellular tasks. This finding has prompted use of these drugs in pathological situations, where such signaling processes need to be manipulated. Here, we review recent progress on the outcome of modulating GTPase signaling after inhibition of protein prenylation by HMGCRIs. We also discuss current controversies over the direct implications of these cholesterol-lowering agents on cholesterol-rich membrane lipid rafts and associated signaling. By reviewing these two different cellular events and the evidence from clinical studies, an overall assessment can be made of the concept of interfering with the HMG-CoA reductase pathway in different brain pathologies. We thereby provide a rational link between the benefit of applying HMGCRIs in brain pathologies, such as multiple sclerosis, Alzheimer's disease and stroke, and the impact on signaling in specific cell types crucial to disease pathogenesis.
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Affiliation(s)
- Frauke Zipp
- Cecilie-Vogt-Clinic for Molecular Neurology, Charité - Universitaetsmedizin Berlin, and Max-Delbrueck-Center for Molecular Medicine, 10117 Berlin, Germany.
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31
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Souza CM, Pichler H. Lipid requirements for endocytosis in yeast. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:442-54. [PMID: 16997624 DOI: 10.1016/j.bbalip.2006.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Revised: 08/10/2006] [Accepted: 08/10/2006] [Indexed: 01/19/2023]
Abstract
Endocytosis is, besides secretion, the most prominent membrane transport pathway in eukaryotic cells. In membrane transport, defined areas of the donor membranes engulf solutes of the compartment they are bordering and bud off with the aid of coat proteins to form vesicles. These transport vehicles are guided along cytoskeletal paths, often matured and, finally, fuse to the acceptor membrane they are targeted to. Lipids and proteins are equally important components in membrane transport pathways. Not only are they the structural units of membranes and vesicles, but both classes of molecules also participate actively in membrane transport processes. Whereas proteins form the cytoskeleton and vesicle coats, confer signals and constitute attachment points for membrane-membrane interaction, lipids modulate the flexibility of bilayers, carry protein recognition sites and confer signals themselves. Over the last decade it has been realized that all classes of bilayer lipids, glycerophospholipids, sphingolipids and sterols, actively contribute to functional membrane transport, in particular to endocytosis. Thus, abnormal bilayer lipid metabolism leads to endocytic defects of different severity. Interestingly, there seems to be a great deal of interdependence and interaction among lipid classes. It will be a challenge to characterize this plenitude of interactions and find out about their impact on cellular processes.
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32
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Su Y, Li Q, Chen L, Yu Z. Condensation effect of cholesterol, stigmasterol, and sitosterol on dipalmitoylphosphatidylcholine in molecular monolayers. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2006.07.016] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Abstract
Smooth muscle cell (SMC) caveolae have been investigated by quantitative and qualitative analysis of transmission electron microscopy (TEM) images of rat stomach, bladder and myometrium, guinea pig taenia coli, human ileum, and rat aortic SMCs. Ultrathin (below 30 nm) serial sections were used for examination of caveolar morphology and their connections with SMC organelles. Average caveolar diameter was smaller in vascular SMCs (70 nm, n=50) than in visceral SMCs (77 nm, n=100), but with the same morphology. Most of the caveolae, featured as flask-shaped plasma membrane (PM) invaginations, opened to the extracellular space through a 20 nm stoma (21, 3nm) having a 7 nm thick diaphragm. A small percentage of caveolae (3%), gathered as grape-like clusters, did not open directly to the extracellular space, but to irregular PM pockets having a 20-30 nm opening to the extracellular space. In visceral SMCs, caveolae were disposed in 4 - 6 rows, parallel to myofilaments, whilst aortic SMCs caveolae were arranged as clusters. This caveolar organization in rows or clusters minimizes the occupied volume, providing more space for the contractile machinery. The morphometric analysis of relative volumes (% of cell volume) showed that caveolae were more conspicuous in visceral than in vascular SMCs (myometrium - 2.40%; bladder - 3.66%, stomach - 2.61%, aorta - 1.43%). We also observed a higher number of caveolae per length unit of cell membrane in most visceral SMCs compared to vascular SMCs (myometrium - 1.06/μm, bladder - 0.74/μm, aorta - 0.57/μm, stomach - 0.48/μm). Caveolae increase the cellular perimeter up to 15% and enlarge the surface area of the plasma membrane about 80% in SMCs. Three-dimensional reconstructions (15μ3) showed that most caveolae, in both visceral and vascular SMCs, have nanocontacts with SR (87%), or with mitochondria (10%), and only 3%, apparently, have no contact with these organelles. Usually, 15 nm wide junctional spaces exist between caveolae and SR, some of them with nanostructural links between each other or with mitochondria: direct contacts (space < 2 nm or none) and molecular links, so called ‘feet’ (about 12 nm electron dense structures between organellar membranes). Direct contacts possibly allow molecular translocation between the two membranes. Electron-dense ‘feet’-like structures suggest a molecular link between these organelles responsible for intracellular Ca2+ homeostasis (excitation-contraction coupling or pharmaco-mechan-ical coupling). Close appositions (∼15 nm) have also been observed between caveolae and perinuclear SR cisterna, suggesting that caveolae might be directly implicated in excitation-transcription coupling.
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Affiliation(s)
- L M Popescu
- Department of Cellular and Molecular Medicine, 'Carol Davila' University of Medicine and Pharmacy, Bucharest, Romania.
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34
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Sitrin RG, Emery SL, Sassanella TM, Blackwood RA, Petty HR. Selective localization of recognition complexes for leukotriene B4 and formyl-Met-Leu-Phe within lipid raft microdomains of human polymorphonuclear neutrophils. THE JOURNAL OF IMMUNOLOGY 2007; 177:8177-84. [PMID: 17114494 DOI: 10.4049/jimmunol.177.11.8177] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neutrophilic polymorphonuclear leukocytes contain glycosphingolipid- and cholesterol-enriched lipid raft microdomains within the plasma membrane. Although there is evidence that lipid rafts function as signaling platforms for CXCR chemokine receptors, their role in recognition systems for other chemotaxins such as leukotriene B4 (LTB4) and fMLP is unknown. To address this question, human neutrophils were extracted with 1% Brij-58 and fractionated on sucrose gradients. B leukotriene receptor-1 (BLT-1), the primary LTB4 receptor, partitioned to low density fractions, co-isolating with the lipid raft marker, flotillin-1. By contrast, formyl peptide receptor (FPR), the primary fMLP receptor, partitioned to high density fractions, co-isolating with a non-raft marker, Cdc42. This pattern was preserved after the cells were stimulated with LTB4 or fMLP. Fluorescence resonance energy transfer (FRET) was performed to confirm the proximity of BLT-1 and FPR with these markers. FRET was detected between BLT1 and flotillin-1 but not Cdc42, whereas FRET was detected between FPR and Cdc42, but not flotillin-1. Pretreating neutrophils with methyl-beta-cyclodextrin, a lipid raft-disrupting agent, suppressed intracellular Ca(2+) mobilization and ERK1/2 phosphorylation in response to LTB4 but had no effect on either of these responses to fMLP. We conclude that BLT-1 is physically located within lipid raft microdomains of human neutrophils and that disrupting lipid raft integrity suppresses LTB4-induced activation. By contrast, FPR is not associated with lipid rafts, and fMLP-induced signaling does not require lipid raft integrity. These findings highlight the complexity of chemotaxin signaling pathways and offer one mechanism by which neutrophils may spatially organize chemotaxin signaling within the plasma membrane.
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Affiliation(s)
- Robert G Sitrin
- Pulmonary and Critical Care Medicine Division, Department of Internal Medicine, University of Michigan, 1150 West Medical Drive, Ann Arbor, MI 48109, USA.
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35
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Sillence DJ. New insights into glycosphingolipid functions--storage, lipid rafts, and translocators. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 262:151-89. [PMID: 17631188 DOI: 10.1016/s0074-7696(07)62003-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glycosphingolipids are key components of eukaryotic cellular membranes. Through their propensity to form lipid rafts, they are important in membrane transport and signaling. At the cell surface, they are required for caveolar-mediated endocytosis, a process required for the action of many glycosphingolipid-binding toxins. Glycosphingolipids also exist intracellularly, on both leaflets of organelle membranes. It is expected that dissecting the mechanisms of cell pathology seen in the glycosphingolipid storage diseases, where lysosomal glycosphingolipid degradation is defective, will reveal their functions. Disrupted cation gradients in Mucolipidosis type IV disease are interlinked with glycosphingolipid storage, defective rab 7 function, and the activation of autophagy. Relationships between drug translocators and glycosphingolipid synthesis are also discussed. Mass spectrometry of cell lines defective in drug transporters reveal clear differences in glycosphingolipid mass and fatty acid composition. The potential roles of glycosphingolipids in lipid raft formation, endocytosis, and cationic gradients are discussed.
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Affiliation(s)
- Dan J Sillence
- Leicester School of Pharmacy, Hawthorne Building, De Montfort University, Leicester, LE1 9BH, United Kingdom
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Yuyama K, Sekino-Suzuki N, Kasahara K. Signal Transduction of Heterotrimeric G Proteins in Lipid Rafts. TRENDS GLYCOSCI GLYC 2007. [DOI: 10.4052/tigg.19.19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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37
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Yi L, Fang J, Isik N, Chim J, Jin T. HIV gp120-induced interaction between CD4 and CCR5 requires cholesterol-rich microenvironments revealed by live cell fluorescence resonance energy transfer imaging. J Biol Chem 2006; 281:35446-53. [PMID: 16963439 DOI: 10.1074/jbc.m607302200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Binding of the human immunodeficiency virus (HIV) envelope gp120 glycoprotein to CD4 and CCR5 receptors on the plasma membrane initiates the viral entry process. Although plasma membrane cholesterol plays an important role in HIV entry, its modulating effect on the viral entry process is unclear. Using fluorescence resonance energy transfer imaging, we have provided evidence here that CD4 and CCR5 localize in different microenvironments on the surface of resting cells. Binding of the third variable region V3-containing gp120 core to CD4 and CCR5 induced association between these receptors, which could be directly monitored by fluorescence resonance energy transfer on the plasma membrane of live cells. Depletion of cholesterol from the plasma membrane abolished the gp120 core-induced associations between CD4 and CCR5, and reloading cholesterol restored the associations in live cells. Our studies suggest that, during the first step of the HIV entry process, gp120 binding alters the microenvironments of unbound CD4 and CCR5, with plasma membrane cholesterol required for the formation of the HIV entry complex.
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Affiliation(s)
- Ling Yi
- Laboratory of Immunogenetics, Twinbrook II Facility, NIAID, National Institutes of Health, Rockville, Maryland 20852, USA
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38
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Windschiegl B, Steinem C. Influence of alpha-hydroxylation of glycolipids on domain formation in lipid monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:7454-7. [PMID: 16922519 DOI: 10.1021/la060146x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
By means of fluorescence and scanning force microscopy (SFM), we investigated the phase behavior of lipid monolayers composed of a mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, sphingomyelin, and cholesterol (5/2/3) with either alpha-hydroxylated or nonhydroxylated galactocerebroside. Fluorescence images of lipid monolayers at the air-water interface demonstrate that, independent of the lipid mixture, phase separation occurs at low surface pressure up to 4-6 mN m(-1), while an almost homogeneous phase is observed at larger surface pressures. However, by means of SFM of lipid monolayers transferred by the Langmuir-Blodgett technique at around 30 mN m(-1), nanometer-sized domains became discernible in those lipid mixtures that contained galactocerebroside, while, in that without a glycolipid, no such domain formation was visible. Moreover, the alpha-hydroxy group of the galactocerebroside alters the size and the total area of the domains significantly.
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Affiliation(s)
- Barbara Windschiegl
- Institut für Analytische Chemie, Chemo- und Biosensorik, Universität Regensburg, 93040 Regensburg, Germany
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39
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Babiychuk EB, Draeger A. Biochemical characterization of detergent-resistant membranes: a systematic approach. Biochem J 2006; 397:407-16. [PMID: 16608442 PMCID: PMC1533311 DOI: 10.1042/bj20060056] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Lateral segregation of cholesterol- and sphingomyelin-rich rafts and glycerophospholipid-containing non-raft microdomains has been proposed to play a role in a variety of biological processes. The most compelling evidence for membrane segregation is based on the observation that extraction with non-ionic detergents leads to solubilization of a subset of membrane components only. However, one decade later, a large body of inconsistent detergent-extraction data is threatening the very concept of membrane segregation. We have assessed the validity of the existing paradigms and we show the following. (i) The localization of a membrane component within a particular fraction of a sucrose gradient cannot be taken as a yardstick for its solubility: a variable localization of the DRMs (detergent-resistant membranes) in sucrose gradients is the result of complex associations between the membrane skeleton and the lipid bilayer. (ii) DRMs of variable composition can be generated by using a single detergent, the increasing concentration of which gradually extracts one protein/lipid after another. Therefore any extraction pattern obtained by a single concentration experiment is bound to be 'investigator-specific'. It follows that comparison of DRMs obtained by different detergents in a single concentration experiment is prone to misinterpretations. (iii) Depletion of cholesterol has a graded effect on membrane solubility. (iv) Differences in detergent solubility of the members of the annexin protein family arise from their association with chemically different membrane compartments; however, these cannot be attributed to the 'brick-like' raft-building blocks of fixed size and chemical composition. Our findings demonstrate a need for critical re-evaluation of the accumulated detergent-extraction data.
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Affiliation(s)
- Eduard B Babiychuk
- Department of Cell Biology, Institute of Anatomy, University of Bern, Bern 9, CH 3000, Switzerland.
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40
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Abstract
Caveolae, specialized membrane nanodomains, have a key role in signaling processes, including calcium handling in smooth muscle cells (SMC). We explored the three-dimensional (3D) architecture of peripheral cytoplasmic space at the nanoscale level and the close spatial relationships between caveolae, sarcoplasmic reticulum (SR), and mitochondria, as ultrastructural basis for an excitation-contraction coupling system and, eventually, for excitation - transcription coupling. About 150 electron micrographs of SMC showed that superficial SR and peripheral mitochondria are rigorously located along the caveolar domains of plasma membrane, alternating with plasmalemmal dense plaques. Electron micrographs made on serial ultrathin sections were digitized, then computer-assisted organellar profiles were traced on images, and automatic 3D reconstruction was obtained using the ‘Reconstruct’ software. The reconstruction was made for 1 μm3 in rat stomach (muscularis mucosae) and 10 μm3 in rat urinary bladder (detrusor smooth muscle). The close appositions (about 15 nm distance) of caveolae, peripheral SR, and mitochondria create coherent cytoplasmic nanoscale subdomains. Apparently, 80% of caveolae establish close contacts with SR and about 10% establish close contacts with mitochondria in both types of SMC. Thus, our results show that caveolae and peripheral SR build Ca2+release units in which mitochondria often could play a part. The caveolae-SR couplings occupy 4.19% of the cellular volume in stomach and 3.10% in rat urinary bladder, while caveolae-mitochondria couplings occupy 3.66% and 3.17%, respectively. We conclude that there are strategic caveolae-SR or caveolae-mitochondria contacts at the nanoscale level in the cortical cytoplasm of SMC, presumably responsible for a vectorial control of free Ca2+ cytoplasmic concentrations in definite nanospaces. This may account for slective activation of specific Ca2+ signaling pathways.
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Affiliation(s)
| | - L M Popescu
- “Victor Babe” National Institute of PathologyBucharest, Romania
- Department of Cellular and Molecular Medicine, “Carol Davila” University of Medicine and PharmacyBucharest, Romania
- * Correspondence to: L.M. POPESCU, M.D., Ph.D. P.O. Box 35-29, Bucharest 35, Romania. E-mail:
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41
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Kiessling V, Crane JM, Tamm LK. Transbilayer effects of raft-like lipid domains in asymmetric planar bilayers measured by single molecule tracking. Biophys J 2006; 91:3313-26. [PMID: 16905614 PMCID: PMC1614489 DOI: 10.1529/biophysj.106.091421] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Cell membranes have complex lipid compositions, including an asymmetric distribution of phospholipids between the opposing leaflets of the bilayer. Although it has been demonstrated that the lipid composition of the outer leaflet of the plasma membrane is sufficient for the formation of raft-like liquid-ordered (l(o)) phase domains, the influence that such domains may have on the lipids and proteins of the inner leaflet remains unknown. We used tethered polymer supports and a combined Langmuir-Blodgett/vesicle fusion (LB/VF) technique to build asymmetric planar bilayers that mimic plasma membrane asymmetry in many ways. We show that directly supported LB monolayers containing cholesterol-rich l(o) phases are inherently unstable when exposed to water or vesicle suspensions. However, tethering the LB monolayer to the solid support with the lipid-anchored polymer 1,2-dimyristoyl phophatidylethanolamine-N-[poly(ethylene glycol)-triethoxysilane] significantly improves stability and allows for the formation of complex planar-supported bilayers that retain >90% asymmetry for 1-2 h. We developed a single molecule tracking (SPT) system for the study of lipid diffusion in asymmetric bilayers with coexisting liquid phases. SPT allowed us to study in detail the diffusion of individual lipids inside, outside, or directly opposed to l(o) phase domains. We show here that l(o) phase domains in one monolayer of an asymmetric bilayer do not induce the formation of domains in the opposite leaflet when this leaflet is composed of palmitoyl-oleoyl phosphatidylcholine and cholesterol but do induce domains when this leaflet is composed of porcine brain phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and cholesterol. The diffusion of lipids is similar in l(o) and liquid-disordered phase domains and is not affected by transbilayer coupling, indicating that lateral and transverse lipid interactions that give rise to the domain structure are weak in the biological lipid mixtures that were employed in this work.
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Affiliation(s)
- Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, 22908-0736, USA
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42
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Li D, Weisinger HS, Weisinger RS, Mathai M, Armitage JA, Vingrys AJ, Sinclair AJ. Omega 6 to omega 3 fatty acid imbalance early in life leads to persistent reductions in DHA levels in glycerophospholipids in rat hypothalamus even after long-term omega 3 fatty acid repletion. Prostaglandins Leukot Essent Fatty Acids 2006; 74:391-9. [PMID: 16716580 DOI: 10.1016/j.plefa.2006.03.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2005] [Revised: 03/07/2006] [Accepted: 03/28/2006] [Indexed: 11/23/2022]
Abstract
Failure to provide omega 3 fatty acids in the perinatal period results in alterations in nerve growth factor levels, dopamine production and permanent elevations in blood pressure. The present study investigated whether changes in brain (i.e., hypothalamus) glycerophospholipid fatty acid profiles induced by a diet rich in omega 6 fatty acids and very low in alpha-linolenic acid (ALA) during pregnancy and the perinatal period could be reversed by subsequent feeding of a diet containing ALA. Female rats (6 per group) were mated and fed either a low ALA diet or a control diet containing ALA throughout pregnancy and until weaning of the pups at 3 weeks. At weaning, the pups (20 per group) remained on the diet of their mothers until 9 weeks, when half the pups were switched onto the other diet, thus generating four groups of animals. At 33 weeks, pups were killed, the hypothalamus dissected from the male rats and analysed for glycerophospholipid fatty acids. In the animals fed the diet with very little ALA and then re-fed the control diet containing high levels of ALA for 24 weeks, the DHA levels were still significantly less than the control values in PE, PS and PI fractions, by 9%, 18% and 34%, respectively. In this group, but not in the other dietary groups, ALA was detected in all glycerophospholipid classes at 0.2-1.7% of the total fatty acids. The results suggest that omega 6-3 PUFA imbalance early in life leads to irreversible changes in hypothalamic composition. The increased ALA and reduced DHA proportions in the animals re-fed ALA in later life are consistent with a dysfunction or down-regulation of the conversion of ALA to 18:4n-3 by the delta-6 desaturase.
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Affiliation(s)
- Duo Li
- Department of Food Science & Nutrition, Zhejiang University, Hangzhou 310029, China
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43
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Coltel N, Combes V, Wassmer SC, Chimini G, Grau GE. Cell vesiculation and immunopathology: implications in cerebral malaria. Microbes Infect 2006; 8:2305-16. [PMID: 16829152 DOI: 10.1016/j.micinf.2006.04.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 04/05/2006] [Indexed: 11/24/2022]
Abstract
Microparticles are plasma membrane fragments that are generated and released under physiological conditions. They are also released when tissue and/or systemic homeostasis is disrupted. These microparticles display different physiological features of the cells from which they originate. They are detected in some pathological conditions, but rarely suspected of participating in the disease's pathogenesis. In the present review, we summarise data about the production of the microparticles, their biological significance and potential role during microorganism-driven processes, especially in cerebral malaria.
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Affiliation(s)
- Nicolas Coltel
- CNRS UMR 6020-Immunopathology Group, Faculty of Medicine-IFR48, 27, bd. Jean Moulin, F-13385 Marseille Cedex 5, France
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44
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Batada NN, Shepp LA, Siegmund DO, Levitt M. Spatial regulation and the rate of signal transduction activation. PLoS Comput Biol 2006; 2:e44. [PMID: 16699596 PMCID: PMC1458967 DOI: 10.1371/journal.pcbi.0020044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Accepted: 03/21/2006] [Indexed: 11/18/2022] Open
Abstract
Of the many important signaling events that take place on the surface of a mammalian cell, activation of signal transduction pathways via interactions of cell surface receptors is one of the most important. Evidence suggests that cell surface proteins are not as freely diffusible as implied by the classic fluid mosaic model and that their confinement to membrane domains is regulated. It is unknown whether these dynamic localization mechanisms function to enhance signal transduction activation rate or to minimize cross talk among pathways that share common intermediates. To determine which of these two possibilities is more likely, we derive an explicit equation for the rate at which cell surface membrane proteins interact based on a Brownian motion model in the presence of endocytosis and exocytosis. We find that in the absence of any diffusion constraints, cell surface protein interaction rate is extremely high relative to cytoplasmic protein interaction rate even in a large mammalian cell with a receptor abundance of a mere two hundred molecules. Since a larger number of downstream signaling events needs to take place, each occurring at a much slower rate than the initial activation via association of cell surface proteins, we conclude that the role of co-localization is most likely that of cross-talk reduction rather than coupling efficiency enhancement.
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Affiliation(s)
- Nizar N Batada
- Program in Biophysics, Stanford University, Stanford, California, USA.
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45
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Wallace EJ, Hooper NM, Olmsted PD. Effect of hydrophobic mismatch on phase behavior of lipid membranes. Biophys J 2006; 90:4104-18. [PMID: 16533859 PMCID: PMC1459530 DOI: 10.1529/biophysj.105.062778] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
We investigate the competing effects of hydrophobic mismatch and chain stretching on the morphology and evolution of domains in lipid membranes via Monte Carlo techniques. We model the membrane as a binary mixture of particles that differ in their preferred lengths, with the shorter particles mimicking unsaturated nonraft lipids and the longer particles mimicking saturated raft lipids. We find that phase separation can be induced upon increasing either the ratio J/kappa of the hydrophobic surface tension J to the compressibility modulus kappa. J/kappa determines the decay length for thickness changes. When this decay length is larger than the system size the membrane remains mixed. Furthermore, increasing the thickness relaxation time can induce transient phase separation.
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Affiliation(s)
- Elizabeth J Wallace
- School of Biochemistry & Microbiology, Institute of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
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46
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Draeger A, Wray S, Babiychuk E. Domain architecture of the smooth-muscle plasma membrane: regulation by annexins. Biochem J 2005; 387:309-14. [PMID: 15537390 PMCID: PMC1134958 DOI: 10.1042/bj20041363] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Individual signalling events are processed in distinct, spatially segregated domains of the plasma membrane. In a smooth muscle, the sarcolemma is divided into domains of focal adhesions alternating with caveolae-rich zones, both harbouring a specific subset of membrane-associated proteins. Recently, we have demonstrated that the sarcolemmal lipids are similarly segregated into domains of cholesterol-rich lipid rafts and glycerophospholipid-rich non-raft regions. In the present study, we provide a detailed structural analysis of the relationship between these proteinaceous and lipid domains. We demonstrate that the segregation of plasmalemmal protein constituents is intimately linked to that of the membrane lipids. Our results imply that lipid segregation is critical for the preservation of membrane protein architecture and essential for directional translocation of proteins to the sarcolemma. We show that the membrane lipid segregation is supported by the annexin protein family in a Ca2+-dependent manner. Eukaryotic cells harbour numerous, tissue-specific subsets of annexins. By examining the significance of this variety in a smooth muscle, we demonstrate that four different annexins target membrane sites of distinct lipid composition and that each annexin requires a different [Ca2+] for its translocation to the sarcolemma. Our results suggest that the interactions of annexins with distinct plasma membrane regions promote membrane segregation and, in combination with their individual Ca2+ sensitivity, might allow a spatially confined, graded response to a multitude of extra- or intracellular stimuli.
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Affiliation(s)
- Annette Draeger
- *Department of Cell Biology, Institute of Anatomy, University of Bern, Bern 9, CH 3000, Switzerland
| | - Susan Wray
- †Department of Physiology, The University of Liverpool, Liverpool L69 3BX, U.K
| | - Eduard B. Babiychuk
- *Department of Cell Biology, Institute of Anatomy, University of Bern, Bern 9, CH 3000, Switzerland
- To whom correspondence should be addressed (email )
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47
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Fujitani M, Kawai H, Proia RL, Kashiwagi A, Yasuda H, Yamashita T. Binding of soluble myelin-associated glycoprotein to specific gangliosides induces the association of p75NTR to lipid rafts and signal transduction. J Neurochem 2005; 94:15-21. [PMID: 15953345 DOI: 10.1111/j.1471-4159.2005.03121.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Myelin-associated glycoprotein (MAG) is a potent inhibitor of neurite outgrowth from a variety of neurons. Here we show that gangliosides, GT1b and GD1a, as well as the Nogo receptor, are functional binding partners for soluble MAG-Fc. Postnatal cerebellar neurons from mice deficient in the GalNAcT gene are insensitive to MAG with regard to neurite outgrowth and lack in the activation of RhoA. MAG-Fc or the antibody to GT1b and GD1a elicits recruitment of p75(NTR.) to lipid rafts, specialized microdomain for signal transduction. Disruption of lipid rafts results in abolishment of inhibitory effects of MAG-Fc and the Nogo peptide. These findings establish gangliosides as functional binding partners for soluble MAG. Gangliosides may play a role in translocation of p75(NTR.) to lipid rafts for initiation of the signal transduction.
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Affiliation(s)
- Masashi Fujitani
- Department of Neurobiology, Graduate School of Medicine, Chiba University, Inohana, Chuo-ku, Japan
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48
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Jiao X, Zhang N, Xu X, Oppenheim JJ, Jin T. Ligand-induced partitioning of human CXCR1 chemokine receptors with lipid raft microenvironments facilitates G-protein-dependent signaling. Mol Cell Biol 2005; 25:5752-62. [PMID: 15964828 PMCID: PMC1156970 DOI: 10.1128/mcb.25.13.5752-5762.2005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Ligand binding to a chemokine receptor triggers signaling events through heterotrimeric G-proteins. The mechanisms underlying receptor-mediated G-protein activation in the heterogeneous microenvironments of the plasma membrane are unclear. Here, using live-cell fluorescence resonance energy transfer imaging to detect the proximity between CXCR1-cyan fluorescent protein (CFP) and fluorescence probes that label lipid raft or non-lipid raft microdomains and using fluorescence recovery after photobleaching analysis to measure the lateral diffusion of CXCR1-CFP, we found that interleukin-8 induces association between the receptors and lipid raft microenvironments. Disruption of lipid rafts impaired G-protein-dependent signaling, such as Ca2+ responses and phosphatidylinositol 3-kinase activation, but had no effect on ligand-binding function and did not completely abolish ligand-induced receptor phosphorylation. Our results suggest a novel mechanism by which ligand binding to CXCR1 promotes lipid raft partitioning of receptors and facilitates activation of heterotrimeric G-proteins.
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Affiliation(s)
- Xuanmao Jiao
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, 12441 Parklawn Drive, Twinbrook II, Rockville, Maryland 20852, USA
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49
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Yi SX, Lee RE. Changes in gut and Malpighian tubule transport during seasonal acclimatization and freezing in the gall flyEurosta solidaginis. J Exp Biol 2005; 208:1895-904. [PMID: 15879070 DOI: 10.1242/jeb.01596] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYSince few studies have examined cold tolerance at the organ level in insects, our primary objective was to characterize the functional responses of the gut and Malpighian tubules (MT) to seasonal acclimatization, chilling and freezing in larvae of the goldenrod gall fly Eurosta solidaginisFitch (Diptera, Tephritidae). From September to December, hemolymph osmolality(455-926 mOsmol kg l-1) and freezing tolerance increased markedly in field-collected larvae. Chlorophenol Red was readily transported into the lumen of the foregut, the posterior portion of the midgut, the ureter, the proximal region of the anterior pair of MT, and entire posterior pair of MT. Ouabain and KCN inhibited transport of Chlorophenol Red in the gut and MT. Transport was readily detected at 0°C and the rate of transport was directly related to temperature. The rate of fluid transport by the MT decreased steadily from a monthly high in September (10.7±0.8 nl min-1 for the anterior pair; 12.7±1.0 nl min-1for the posterior pair) until secretion was no longer detectable in December;this decrease parallels entry into diapause for this species. Even in larvae that died following freezing for 40 days at -20°C, individual organ function was retained to a limited extent. Through the autumn, cholesterol concentrations in the hemolymph increased nearly fourfold. In contrast, the ratio of cholesterol to protein content (nmol mg l-1) in the MT membrane remained relatively constant (22∼24 nmol mg l-1protein) during this period. Freezing of larvae for 20 days at -20°C caused a significant decrease in cholesterol levels in the hemolymph and the MT membranes compared to unfrozen controls. These results suggest that cholesterol plays a role in seasonal cold hardening and freeze tolerance in insects.
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Affiliation(s)
- Shu-Xia Yi
- Department of Zoology, Miami University, Oxford, Ohio 45056, USA
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50
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Bassi AM, Romano P, Mangini S, Colombo M, Canepa C, Nanni G, Casu A. Protein and m-RNA expression of farnesyl-transferases, RhoA and RhoB in rat liver hepatocytes: action of perillyl alcohol and vitamin A in vivo. J Biomed Sci 2005; 12:457-66. [PMID: 15959631 DOI: 10.1007/s11373-005-3728-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Accepted: 02/18/2005] [Indexed: 10/25/2022] Open
Abstract
We analysed the action, in rats in vivo, of the protein isoprenylation inhibitor perillyl alcohol (POH) and that of vitamin A, alone or in association, on m-RNA and protein expression of farnesyltransferases (FTases alpha and beta subunits) and their protein substrates RhoA and RhoB, in isolated hepatocytes. Combined administration of POH and vitamin A induced a sharp decrease in FTase alpha protein after 96 h, suggesting an involvement not only of farnesyltransferases but also of geranylgeranyltransferases, which share the FTase alpha protein. FTase beta protein did not decrease. POH plus vitamin A, in contrast with POH or vitamin A alone, induced a decrease in RhoB protein, probably because of different cleavages. No modification was observed in RhoA protein. Vitamin A alone increased RhoB m-RNA and protein expression. As one of the functions of RhoB is cell polarisation, these data support our previous hypothesis of a polarised transport of vitamin A from hepatocytes to hepatic stellate cells. As the behaviours of m-RNAs and proteins in this study were often different, cytoplasmic metabolic pathways must be considered for the parameters studied. The behaviour of Rho B, which is thought to have an antioncogene function, is discussed in view of its isoprenylated forms in the membranes. These preliminary findings stress the need, when studying the association of two isoprenoids in cancer therapy, to consider normal as well as tumour-bearing animals.
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Affiliation(s)
- A M Bassi
- Department of Experimental Medicine, Section of General Pathology, University of Genoa, Via L.B. Alberti 2, 16132, Genoa, Italy.
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