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Bodin S, Peuker LC, Jestin E, Alves ID, Velasco V, Ait-Arsa I, Schollhammer R, Lamare F, Vimont D, MacGrogan G, Hindié E, Beck-Sickinger AG, Morgat C. Development of Radiopharmaceuticals for NPY Receptor-5 (Y5) Nuclear Imaging in Tumors by Synthesis of Specific Agonists and Investigation of Their Binding Mode. Bioconjug Chem 2023; 34:2014-2021. [PMID: 37556437 DOI: 10.1021/acs.bioconjchem.3c00313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
The neuropeptide-Y (NPY) family acts through four G protein-coupled receptor subtypes in humans, namely, Y1, Y2, Y4, and Y5. A growing body of evidence suggest the involvement of the NPY system in several cancers, notably the Y5 subtype, thus acting as a relevant target for the development of radiopharmaceuticals for imaging or targeted radionuclide therapy (TRT). Here, the [cPP(1-7),NPY(19-23),Ala31,Aib32,Gln34]hPP scaffold, further referred to as sY5ago, was modified with a DOTA chelator and radiolabeled with 68Ga and 111In and investigated in vitro and in vivo using the MCF-7 model. For in vivo studies, MCF-7 cells were orthotopically implanted in female nude mice and imaging with small animal positron emission tomography/computed tomography (μPET/CT) was performed. At the end of imaging, the mice were sacrificed. A scrambled version of sY5ago, which was also modified with a DOTA chelator, served as a negative control (DOTA-[Nle]sY5ago_scrambled). sY5ago and DOTA-sY5ago showed subnanomolar affinity toward the Y5 (0.9 ± 0.1 and 0.8 ± 0.1 nM, respectively) and a single binding site at the Y5 was identified. [68Ga]Ga-DOTA-sY5ago and [111In]In-DOTA-sY5ago were hydrophilic and showed high specific internalization (1.61 ± 0.75%/106 cells at 1 h) and moderate efflux (55% of total binding externalized at 45 min). On μPET/CT images, most of the signal was depicted in the kidneys and the liver. MCF-7 tumors were clearly visualized. On biodistribution studies, [68Ga]Ga-DOTA-sY5ago was eliminated by the kidneys (∼60 %ID/g). The kidney uptake is Y5-mediated. A specific uptake was also noted in the liver (5.09 ± 1.15 %ID/g vs 1.13 ± 0.21 %ID/g for [68Ga]Ga-DOTA-[Nle]sY5ago_scrambled, p < 0.05), the lungs (1.03 ± 0.34 %ID/g vs 0.20 %ID/g, p < 0.05), and the spleen (0.85 ± 0.09%ID/g vs 0.16 ± 0.16%ID/g, p < 0.05). In MCF-7 tumors, [68Ga]Ga-DOTA-sY5ago showed 12-fold higher uptake than [68Ga]Ga-DOTA-[Nle]sY5ago_scrambled (3.43 ± 2.32 vs 0.27 ± 0.15 %ID/g, respectively, p = 0.0008) at 1 h post-injection. Finally, a proof-of-principle tissular micro-imaging study on a human primary cancer sample showed weak binding of [111In]In-DOTA-sY5ago in prostatic intra-neoplasia and high binding in the ISUP1 lesion while normal prostate was free of signal.
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Affiliation(s)
- Sacha Bodin
- Department of Nuclear Medicine, University Hospital of Bordeaux, F-33076 Bordeaux, France
- CNRS, EPHE, INCIA UMR 5287, University of Bordeaux, F-33400 Talence, France
| | - Lisa C Peuker
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, 04103 Leipzig, Germany
| | - Emmanuelle Jestin
- GIP CYROI - Cyclotron Réunion Océan Indien, F-97490 Saint Clotilde, France
| | - Isabel D Alves
- CNRS UMR 248, Institute of Chemistry & Biology of Membranes & Nano-objects (CBMN), University of Bordeaux, F-33600 Pessac, France
| | - Valérie Velasco
- Surgical Pathology Unit, Department of Biopathology, Institut Bergonié, F-33076 Bordeaux, France
- ACTION U1218, INSERM, F-33076 Bordeaux, France
| | - Imade Ait-Arsa
- GIP CYROI - Cyclotron Réunion Océan Indien, F-97490 Saint Clotilde, France
| | - Romain Schollhammer
- Department of Nuclear Medicine, University Hospital of Bordeaux, F-33076 Bordeaux, France
- CNRS, EPHE, INCIA UMR 5287, University of Bordeaux, F-33400 Talence, France
| | - Frédéric Lamare
- CNRS, EPHE, INCIA UMR 5287, University of Bordeaux, F-33400 Talence, France
| | - Delphine Vimont
- CNRS, EPHE, INCIA UMR 5287, University of Bordeaux, F-33400 Talence, France
| | - Gaétan MacGrogan
- Surgical Pathology Unit, Department of Biopathology, Institut Bergonié, F-33076 Bordeaux, France
- ACTION U1218, INSERM, F-33076 Bordeaux, France
| | - Elif Hindié
- Department of Nuclear Medicine, University Hospital of Bordeaux, F-33076 Bordeaux, France
- CNRS, EPHE, INCIA UMR 5287, University of Bordeaux, F-33400 Talence, France
- Institut Universitaire de France, F-75000 Paris, France
| | - Annette G Beck-Sickinger
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, 04103 Leipzig, Germany
| | - Clément Morgat
- Department of Nuclear Medicine, University Hospital of Bordeaux, F-33076 Bordeaux, France
- CNRS, EPHE, INCIA UMR 5287, University of Bordeaux, F-33400 Talence, France
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2
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Jobin ML, De Smedt-Peyrusse V, Ducrocq F, Baccouch R, Oummadi A, Pedersen MH, Medel-Lacruz B, Angelo MF, Villette S, Van Delft P, Fouillen L, Mongrand S, Selent J, Tolentino-Cortez T, Barreda-Gómez G, Grégoire S, Masson E, Durroux T, Javitch JA, Guixà-González R, Alves ID, Trifilieff P. Impact of membrane lipid polyunsaturation on dopamine D2 receptor ligand binding and signaling. Mol Psychiatry 2023; 28:1960-1969. [PMID: 36604603 DOI: 10.1038/s41380-022-01928-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 12/05/2022] [Accepted: 12/14/2022] [Indexed: 01/07/2023]
Abstract
Increasing evidence supports a relationship between lipid metabolism and mental health. In particular, the biostatus of polyunsaturated fatty acids (PUFAs) correlates with some symptoms of psychiatric disorders, as well as the efficacy of pharmacological treatments. Recent findings highlight a direct association between brain PUFA levels and dopamine transmission, a major neuromodulatory system implicated in the etiology of psychiatric symptoms. However, the mechanisms underlying this relationship are still unknown. Here we demonstrate that membrane enrichment in the n-3 PUFA docosahexaenoic acid (DHA), potentiates ligand binding to the dopamine D2 receptor (D2R), suggesting that DHA acts as an allosteric modulator of this receptor. Molecular dynamics simulations confirm that DHA has a high preference for interaction with the D2R and show that membrane unsaturation selectively enhances the conformational dynamics of the receptor around its second intracellular loop. We find that membrane unsaturation spares G protein activity but potentiates the recruitment of β-arrestin in cells. Furthermore, in vivo n-3 PUFA deficiency blunts the behavioral effects of two D2R ligands, quinpirole and aripiprazole. These results highlight the importance of membrane unsaturation for D2R activity and provide a putative mechanism for the ability of PUFAs to enhance antipsychotic efficacy.
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Affiliation(s)
- Marie-Lise Jobin
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, 33000, Bordeaux, France
| | | | - Fabien Ducrocq
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, 33000, Bordeaux, France
| | - Rim Baccouch
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS UMR 5248, Université de Bordeaux, Bordeaux INP, 33600, Pessac, France
| | - Asma Oummadi
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, 33000, Bordeaux, France
| | - Maria Hauge Pedersen
- Department of Psychiatry, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
| | - Brian Medel-Lacruz
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM)-Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), 08003, Barcelona, Spain
| | | | - Sandrine Villette
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS UMR 5248, Université de Bordeaux, Bordeaux INP, 33600, Pessac, France
| | - Pierre Van Delft
- Laboratory of Membrane Biogenesis (LBM), Research Mix Unity (UMR) 5200, National Scientific Research Center (CNRS), University of Bordeaux, Bordeaux, France
| | - Laetitia Fouillen
- Laboratory of Membrane Biogenesis (LBM), Research Mix Unity (UMR) 5200, National Scientific Research Center (CNRS), University of Bordeaux, Bordeaux, France
| | - Sébastien Mongrand
- Laboratory of Membrane Biogenesis (LBM), Research Mix Unity (UMR) 5200, National Scientific Research Center (CNRS), University of Bordeaux, Bordeaux, France
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM)-Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), 08003, Barcelona, Spain
| | | | - Gabriel Barreda-Gómez
- Research Department, IMG Pharma Biotech S.L., BIC Bizkaia (612), 48160, Derio, Spain
| | - Stéphane Grégoire
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRAE, Université Bourgogne Franche-Comté, 21000, Dijon, France
| | - Elodie Masson
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRAE, Université Bourgogne Franche-Comté, 21000, Dijon, France
| | - Thierry Durroux
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Jonathan A Javitch
- Department of Psychiatry, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
- Department of Molecular Pharmacology and Therapeutics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, 10032, USA
| | - Ramon Guixà-González
- Condensed Matter Theory Group, Paul Scherrer Institute (PSI), 5232, Villigen, PSI, Switzerland.
| | - Isabel D Alves
- Institute of Chemistry & Biology of Membranes & Nanoobjects, CNRS UMR 5248, Université de Bordeaux, Bordeaux INP, 33600, Pessac, France.
| | - Pierre Trifilieff
- Université de Bordeaux, INRAE, Bordeaux INP, NutriNeuro, 33000, Bordeaux, France.
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Ma L, Li X, Petersen RB, Peng A, Huang K. Probing the interactions between amyloidogenic proteins and bio-membranes. Biophys Chem 2023; 296:106984. [PMID: 36889133 DOI: 10.1016/j.bpc.2023.106984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/11/2023] [Accepted: 02/22/2023] [Indexed: 03/01/2023]
Abstract
Protein misfolding diseases (PMDs) in humans are characterized by the deposition of protein aggregates in tissues, including Alzheimer's disease, Parkinson's disease, type 2 diabetes, and amyotrophic lateral sclerosis. Misfolding and aggregation of amyloidogenic proteins play a central role in the onset and progression of PMDs, and these processes are regulated by multiple factors, especially the interaction between proteins and bio-membranes. Bio-membranes induce conformational changes in amyloidogenic proteins and affect their aggregation; on the other hand, the aggregates of amyloidogenic proteins may cause membrane damage or dysfunction leading to cytotoxicity. In this review, we summarize the factors that affect the binding of amyloidogenic proteins and membranes, the effects of bio-membranes on the aggregation of amyloidogenic proteins, mechanisms of membrane disruption by amyloidogenic aggregates, technical approaches for detecting these interactions, and finally therapeutic strategies targeting membrane damage caused by amyloidogenic proteins.
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Affiliation(s)
- Liang Ma
- Department of Pharmacy, Wuhan Mental Health Center, Wuhan, China; Department of Pharmacy, Wuhan Hospital for Psychotherapy, Wuhan, China
| | - Xi Li
- Tongji School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Robert B Petersen
- Foundational Sciences, Central Michigan University College of Medicine, Mount Pleasant, MI, USA
| | - Anlin Peng
- Department of Pharmacy, The Third Hospital of Wuhan, Tongren Hospital of Wuhan University, Wuhan, China.
| | - Kun Huang
- Tongji School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Joliot A. Role of PI(4,5)P2 and Cholesterol in Unconventional Protein Secretion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:381-392. [PMID: 36988889 DOI: 10.1007/978-3-031-21547-6_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Besides its protective role in the maintenance of cell homeostasis, the plasma membrane is the site of exchanges between the cell interior and the extracellular medium. To circumvent the hydrophobic barrier formed by the acyl chains of the lipid bilayer, protein channels and transporters are key players in the exchange of small hydrophilic compounds such as ions or nutrients, but they hardly account for the transport of larger biological molecules. Exchange of proteins usually relies on membrane-fusion events between vesicles and the plasma membrane. In recent years, several alternative unconventional protein secretion (UPS) pathways across the plasma membrane have been characterised for a specific set of secreted substrates, some of them excluding any membrane-fusion events (Dimou and Nickel, Curr Biol 28:R406-R410, 2018). One of thesbe pathways, referred as type I UPS, relies on the direct translocation of the protein across the plasma membrane and not surprisingly, lipids are essential players in this process. In this chapter, we discuss the roles of phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2) and cholesterol in unconventional pathways involving Engrailed-2 homeoprotein and fibroblast growth factor 2.
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Affiliation(s)
- Alain Joliot
- INSERM U932, Institut Curie Centre de Recherche, PSL Research University, Paris, France.
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5
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Jin R, Cao R, Baumgart T. Curvature dependence of BAR protein membrane association and dissociation kinetics. Sci Rep 2022; 12:7676. [PMID: 35538113 PMCID: PMC9091223 DOI: 10.1038/s41598-022-11221-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 04/18/2022] [Indexed: 11/09/2022] Open
Abstract
BAR (Bin/Amphiphysin/Rvs) domain containing proteins function as lipid bilayer benders and curvature sensors, and they contribute to membrane shaping involved in cell signaling and metabolism. The mechanism for their membrane shape sensing has been investigated by both equilibrium binding and kinetic studies. In prior research, stopped-flow spectroscopy has been used to deduce a positive dependence on membrane curvature for the binding rate constant, kon, of a BAR protein called endophilin. However, the impact of bulk diffusion of endophilin, on the kinetic binding parameters has not been thoroughly considered. Employing similar methods, and using lipid vesicles of multiple sizes, we obtained a linear dependence of kon on vesicle curvature. However, we found that the observed relation can be explained without considering the local curvature sensing ability of endophilin in the membrane association process. In contrast, the diffusion-independent unbinding rate constant (koff) obtained from stopped-flow measurements shows a negative dependence on membrane curvature, which is controlled/mediated by endophilin-membrane interactions. This latter dependency, in addition to protein-protein interactions on the membrane, explains the selective binding of BAR proteins to highly curved membranes in equilibrium binding experiments.
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Affiliation(s)
- Rui Jin
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Rui Cao
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.,Division of Biostatistics, University of Minnesota, Minneapolis, MN, USA
| | - Tobias Baumgart
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
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Rascol E, Villette S, Harté E, Alves ID. Plasmon Waveguide Resonance: Principles, Applications and Historical Perspectives on Instrument Development. Molecules 2021; 26:molecules26216442. [PMID: 34770851 PMCID: PMC8588475 DOI: 10.3390/molecules26216442] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/15/2021] [Accepted: 10/20/2021] [Indexed: 11/16/2022] Open
Abstract
Plasmon waveguide resonance (PWR) is a variant of surface plasmon resonance (SPR) that was invented about two decades ago at the University of Arizona. In addition to the characterization of the kinetics and affinity of molecular interactions, PWR possesses several advantages relative to SPR, namely, the ability to monitor both mass and structural changes. PWR allows anisotropy information to be obtained and is ideal for the investigation of molecular interactions occurring in anisotropic-oriented thin films. In this review, we will revisit main PWR applications, aiming at characterizing molecular interactions occurring (1) at lipid membranes deposited in the sensor and (2) in chemically modified sensors. Among the most widely used applications is the investigation of G-protein coupled receptor (GPCR) ligand activation and the study of the lipid environment’s impact on this process. Pioneering PWR studies on GPCRs were carried out thanks to the strong and effective collaboration between two laboratories in the University of Arizona leaded by Dr. Gordon Tollin and Dr. Victor J. Hruby. This review provides an overview of the main applications of PWR and provides a historical perspective on the development of instruments since the first prototype and continuous technological improvements to ongoing and future developments, aiming at broadening the information obtained and expanding the application portfolio.
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Affiliation(s)
- Estelle Rascol
- Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France; (E.R.); (S.V.)
| | - Sandrine Villette
- Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France; (E.R.); (S.V.)
| | - Etienne Harté
- Université de Bordeaux and CNRS, LOMA, UMR 5798, F-33400 Talence, France;
| | - Isabel D. Alves
- Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France; (E.R.); (S.V.)
- Correspondence: ; Tel.: +33-5400-06-8949
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7
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Amblard I, Dupont E, Alves I, Miralvès J, Queguiner I, Joliot A. Bidirectional transfer of homeoprotein EN2 across the plasma membrane requires PIP 2. J Cell Sci 2020; 133:jcs244327. [PMID: 32434869 DOI: 10.1242/jcs.244327] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/05/2020] [Indexed: 01/21/2023] Open
Abstract
Homeoproteins are a class of transcription factors sharing the unexpected property of intercellular trafficking that confers to homeoproteins a paracrine mode of action. Homeoprotein paracrine action participates in the control of patterning processes, including axonal guidance, brain plasticity and boundary formation. Internalization and secretion, the two steps of intercellular transfer, rely on unconventional mechanisms, but the cellular mechanisms at stake still need to be fully characterized. Thanks to the design of new quantitative and sensitive assays dedicated to the study of homeoprotein transfer within HeLa cells in culture, we demonstrate a core role of phosphatidylinositol (4,5)-bisphosphate (PIP2) together with cholesterol in the translocation of the homeobox protein engrailed-2 (EN2) across the plasma membrane. By using drug and enzyme treatments, we show that both secretion and internalization are regulated according to PIP2 levels. The requirement for PIP2 and cholesterol in EN2 trafficking correlates with their selective affinity for this protein in artificial bilayers, which is drastically decreased in a paracrine-deficient mutant of EN2. We propose that the bidirectional plasma membrane translocation events that occur during homeoprotein secretion and internalization are parts of a common process.
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Affiliation(s)
- Irène Amblard
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
- Sorbonne University, Paris, France
| | - Edmond Dupont
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Isabel Alves
- CBMN, UMR 5248 CNRS, University of Bordeaux, 33600 Pessac, France
| | - Julie Miralvès
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Isabelle Queguiner
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Alain Joliot
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
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8
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Interaction of the Anti-Proliferative GPER Inverse Agonist ERα17p with the Breast Cancer Cell Plasma Membrane: From Biophysics to Biology. Cells 2020; 9:cells9020447. [PMID: 32075246 PMCID: PMC7072814 DOI: 10.3390/cells9020447] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 02/03/2020] [Accepted: 02/11/2020] [Indexed: 01/02/2023] Open
Abstract
The peptide ERα17p, which corresponds to the 295-311 fragment of the hinge/AF2 domains of the human estrogen receptor α (ERα), exerts apoptosis in breast cancer cells through a mechanism involving the G protein-coupled estrogen-dependent receptor GPER. Besides this receptor-mediated mechanism, we have detected a direct interaction (Kd value in the micromolar range) of this peptide with lipid vesicles mimicking the plasma membrane of eukaryotes. The reversible and not reversible pools of interacting peptide may correspond to soluble and aggregated membrane-interacting peptide populations, respectively. By using circular dichroism (CD) spectroscopy, we have shown that the interaction of the peptide with this membrane model was associated with its folding into β sheet. A slight leakage of the 5(6)-fluorescein was also observed, indicating lipid bilayer permeability. When the peptide was incubated with living breast cancer cells at the active concentration of 10 μM, aggregates were detected at the plasma membrane under the form of spheres. This insoluble pool of peptide, which seems to result from a fibrillation process, is internalized in micrometric vacuoles under the form of fibrils, without evidence of cytotoxicity, at least at the microscopic level. This study provides new information on the interaction of ERα17p with breast cancer cell membranes as well as on its mechanism of action, with respect to direct membrane effects.
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9
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Calmet P, Cullin C, Cortès S, Vang M, Caudy N, Baccouch R, Dessolin J, Maamar NT, Lecomte S, Tillier B, Alves ID. Cholesterol impacts chemokine CCR5 receptor ligand-binding activity. FEBS J 2019; 287:2367-2385. [PMID: 31738467 DOI: 10.1111/febs.15145] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/27/2019] [Accepted: 11/16/2019] [Indexed: 01/03/2023]
Abstract
The chemokine CCR5 receptor is target of maraviroc, a negative allosteric modulator of CCR5 that blocks the HIV protein gp120 from associating with the receptor, thereby inhibiting virus cellular entry. As noted with other G-protein-coupled receptor family members, the role of the lipid environment in CCR5 signaling remains obscure and very modestly investigated. Controversial literature on the impact of cholesterol (Chol) depletion in HIV infection and CCR5 signaling, including the hypothesis that Chol depletion could inhibit HIV infection, lead us to focus on the understanding of Chol impact in the first stages of receptor activation. To address this aim, the approach chosen was to employ reconstituted model lipid systems of controlled lipid composition containing CCR5 from two distinct expression systems: Pichia pastoris and cell-free expression. The characterization of receptor/ligand interaction in terms of total binding or competition binding assays was independently performed by plasmon waveguide resonance and fluorescence anisotropy, respectively. Maraviroc, a potent receptor antagonist, was the ligand investigated. Additionally, coarse-grained molecular dynamics simulation was employed to investigate Chol impact in the receptor-conformational flexibility and dynamics. Results obtained with receptor produced by different expression systems and using different biophysical approaches clearly demonstrate a considerable impact of Chol in the binding affinity of maraviroc to the receptor and receptor-conformational dynamics. Chol considerably decreases maraviroc binding affinity to the CCR5 receptor. The mechanisms by which this effect occurs seem to involve the adoption of distinct receptor-conformational states with restrained structural dynamics and helical motions in the presence of Chol.
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Affiliation(s)
- Pierre Calmet
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | | | | | - Maylou Vang
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | - Nada Caudy
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | - Rim Baccouch
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | - Jean Dessolin
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | | | - Sophie Lecomte
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
| | | | - Isabel D Alves
- CBMN, UMR 5248 CNRS, University of Bordeaux, Pessac, France
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10
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Vacchini M, Edwards R, Guizzardi R, Palmioli A, Ciaramelli C, Paiotta A, Airoldi C, La Ferla B, Cipolla L. Glycan Carriers As Glycotools for Medicinal Chemistry Applications. Curr Med Chem 2019; 26:6349-6398. [DOI: 10.2174/0929867326666190104164653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 11/07/2018] [Accepted: 12/18/2018] [Indexed: 12/12/2022]
Abstract
Carbohydrates are one of the most powerful and versatile classes of biomolecules that nature
uses to regulate organisms’ biochemistry, modulating plenty of signaling events within cells, triggering
a plethora of physiological and pathological cellular behaviors. In this framework, glycan carrier
systems or carbohydrate-decorated materials constitute interesting and relevant tools for medicinal
chemistry applications. In the last few decades, efforts have been focused, among others, on the development
of multivalent glycoconjugates, biosensors, glycoarrays, carbohydrate-decorated biomaterials
for regenerative medicine, and glyconanoparticles. This review aims to provide the reader with a general
overview of the different carbohydrate carrier systems that have been developed as tools in different
medicinal chemistry approaches relying on carbohydrate-protein interactions. Given the extent of
this topic, the present review will focus on selected examples that highlight the advancements and potentialities
offered by this specific area of research, rather than being an exhaustive literature survey of
any specific glyco-functionalized system.
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Affiliation(s)
- Mattia Vacchini
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Rana Edwards
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Roberto Guizzardi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Alessandro Palmioli
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Carlotta Ciaramelli
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Alice Paiotta
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Cristina Airoldi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Barbara La Ferla
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
| | - Laura Cipolla
- Department of Biotechnology and Biosciences, University of Milano-Bicocca Milano, Italy
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11
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Jiang JQ, Chanseau C, Alves ID, Nlate S, Durrieu MC. Dendron-Functionalized Surface: Efficient Strategy for Enhancing the Capture of Microvesicles. iScience 2019; 21:110-123. [PMID: 31655252 PMCID: PMC6820240 DOI: 10.1016/j.isci.2019.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/23/2019] [Accepted: 10/02/2019] [Indexed: 12/30/2022] Open
Abstract
Microvesicles (MVs) are used by various types of cells in the human body for intercellular communication, making them biomarkers of great potential for the early and non-evasive diagnosis of a spectrum of diseases. An integrated analysis including morphological, quantitative, and compositional studies is most desirable for the clinical application of MV detection; however, such integration is limited by the currently available analysis techniques. In this context, exploiting the phosphatidylserine (PS) exposure of MVs, we synthesized a series of dendritic molecules with PS-binding sites at the periphery. PS-dendron binding was studied at the molecular level using NMR approaches, whereas PS-containing membrane-dendron interaction was investigated in an aqueous environment using plasmon waveguide resonance spectroscopy. As a proof of concept, polyethylene terephthalate surface was functionalized with the synthetic dendrons, forming devices that can capture MVs to facilitate their subsequent analyses. Phosphatidylserine-dendron interaction studies with NMR techniques Lipid membrane binding enhancement using dendritic molecules Dendron-grafted material for effective MV capture
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Affiliation(s)
- Jian-Qiao Jiang
- Université de Bordeaux, Chimie et Biologie des Membranes et Nano-Objets (UMR5248 CBMN), Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; CNRS, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; Bordeaux INP, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France
| | - Christel Chanseau
- Université de Bordeaux, Chimie et Biologie des Membranes et Nano-Objets (UMR5248 CBMN), Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; CNRS, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; Bordeaux INP, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France
| | - Isabel D Alves
- Université de Bordeaux, Chimie et Biologie des Membranes et Nano-Objets (UMR5248 CBMN), Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; CNRS, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; Bordeaux INP, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France
| | - Sylvain Nlate
- Université de Bordeaux, Chimie et Biologie des Membranes et Nano-Objets (UMR5248 CBMN), Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; CNRS, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; Bordeaux INP, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France.
| | - Marie-Christine Durrieu
- Université de Bordeaux, Chimie et Biologie des Membranes et Nano-Objets (UMR5248 CBMN), Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; CNRS, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France; Bordeaux INP, CBMN UMR5248, Allée Geoffroy Saint Hilaire - Bât 14, Pessac 33600, France.
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12
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Structural insights into the AapA1 toxin of Helicobacter pylori. Biochim Biophys Acta Gen Subj 2019; 1864:129423. [PMID: 31476357 DOI: 10.1016/j.bbagen.2019.129423] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 08/12/2019] [Accepted: 08/28/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND We previously reported the identification of the aapA1/IsoA1 locus as part of a new family of toxin-antitoxin (TA) systems in the human pathogen Helicobacter pylori. AapA1 belongs to type I TA bacterial toxins, and both its mechanism of action towards the membrane and toxicity features are still unclear. METHODS The biochemical characterization of the AapA1 toxic peptide was carried out using plasmid-borne expression and mutational approaches to follow its toxicity and localization. Biophysical properties of the AapA1 interaction with lipid membranes were studied by solution and solid-state NMR spectroscopy, plasmon waveguide resonance (PWR) and molecular modeling. RESULTS We show that despite a low hydrophobic index, this toxin has a nanomolar affinity to the prokaryotic membrane. NMR spectroscopy reveals that the AapA1 toxin is structurally organized into three distinct domains: a positively charged disordered N-terminal domain (D), a single α-helix (H), and a basic C-terminal domain (R). The R domain interacts and destabilizes the membrane, while the H domain adopts a transmembrane conformation. These results were confirmed by alanine scanning of the minimal sequence required for toxicity. CONCLUSION Our results have shown that specific amino acid residues along the H domain, as well as the R domain, are essential for the toxicity of the AapA1 toxin. GENERAL SIGNIFICANCE Untangling and understanding the mechanism of action of small membrane-targeting toxins are difficult, but nevertheless contributes to a promising search and development of new antimicrobial drugs.
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13
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Macikova L, Sinica V, Kadkova A, Villette S, Ciaccafava A, Faherty J, Lecomte S, Alves ID, Vlachova V. Putative interaction site for membrane phospholipids controls activation of TRPA1 channel at physiological membrane potentials. FEBS J 2019; 286:3664-3683. [PMID: 31116904 DOI: 10.1111/febs.14931] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/09/2019] [Accepted: 05/20/2019] [Indexed: 12/16/2022]
Abstract
The transient receptor potential ankyrin 1 (TRPA1) channel is a polymodal sensor of environmental irritant compounds, endogenous proalgesic agents, and cold. Upon activation, TRPA1 channels increase cellular calcium levels via direct permeation and trigger signaling pathways that hydrolyze phosphatidylinositol-4,5-bisphosphate (PIP2 ) in the inner membrane leaflet. Our objective was to determine the extent to which a putative PIP2 -interaction site (Y1006-Q1031) is involved in TRPA1 regulation. The interactions of two specific peptides (L992-N1008 and T1003-P1034) with model lipid membranes were characterized by biophysical approaches to obtain information about affinity, peptide secondary structure, and peptide effect in the lipid organization. The results indicate that the two peptides interact with lipid membranes only if PIP2 is present and their affinities depend on the presence of calcium. Using whole-cell electrophysiology, we demonstrate that mutation at F1020 produced channels with faster activation kinetics and with a rightward shifted voltage-dependent activation curve by altering the allosteric constant that couples voltage sensing to pore opening. We assert that the presence of PIP2 is essential for the interaction of the two peptide sequences with the lipid membrane. The putative phosphoinositide-interacting domain comprising the highly conserved F1020 contributes to the stabilization of the TRPA1 channel gate.
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Affiliation(s)
- Lucie Macikova
- CBMN-UMR 5248 CNRS, IPB, University of Bordeaux, Pessac, France.,Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.,Department of Physiology, Faculty of Science, Charles University in Prague, Czech Republic
| | - Viktor Sinica
- Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Anna Kadkova
- Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | | | | | | - Sophie Lecomte
- CBMN-UMR 5248 CNRS, IPB, University of Bordeaux, Pessac, France
| | - Isabel D Alves
- CBMN-UMR 5248 CNRS, IPB, University of Bordeaux, Pessac, France
| | - Viktorie Vlachova
- Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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14
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Alves ID, Lecomte S. Study of G-Protein Coupled Receptor Signaling in Membrane Environment by Plasmon Waveguide Resonance. Acc Chem Res 2019; 52:1059-1067. [PMID: 30865424 DOI: 10.1021/acs.accounts.9b00007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Here we describe an experimental technique, termed plasmon waveguide resonance (PWR) spectroscopy that enables the characterization of molecular interactions occurring at the level of anisotropic thin films as lipid membranes and therein inserted or interacting molecules. PWR allows one to characterize such molecular interactions at different levels: (1) acquire binding curves and calculate dissociation constants; (2) obtain kinetic information; (3) obtain information about associated anisotropy changes and changes in membrane thickness; (4) obtain insight about lateral homogeneity (formation of domains). Points 1, 2, and 4 can be directly obtained from the data. Point 3 requires spectral fitting procedures so that the different optical parameters characterizing thin films as proteolipid membranes, namely refractive index and extinction coefficient for both p- (TM component of light that is parallel to the incident light) and s- (TE component of light that is perpendicular to the incident light) polarizations and thickness, can be determined. When applied to membrane proteins as the G-protein coupled receptor (GPCR) family, both ligand-induced conformational changes of the receptor can be followed as well as interactions with effectors (e.g., G-proteins). Additionally, by either altering the lipid composition in cellular membranes or specifically controlling its composition in the case of lipid model membranes with reconstituted proteins, the role of the lipid environment in receptor activation and signaling can be determined. Additionally, the eventual partition of receptors in different lipid microdomains (e.g., lipid rafts) can be followed. Such information can be obtained ex cellulo with mammalian cell membrane fragments expressing the protein of interest and/or in vitro with lipid model systems where the protein under investigation has been reconstituted. Moreover, PWR can also be applied to directly follow the reconstitution of membrane proteins in lipid model membranes. The measurements are performed directly (no labeling of molecular partners), in real time and with very high sensitivity. Here we will discuss different aspects of GPCR activation and signaling where PWR brought important information in parallel with other approaches. The utility of PWR is not limited to GPCRs but can be applied to any membrane protein. PWR is also an excellent tool to characterize the interaction of membrane active molecules (as cell penetrating, antimicrobial, viral and amyloid peptides) with lipids. A brief section is dedicated to such applications, with particular emphasis on amyloid peptides. To finalize, as PWR is a homemade technology, ongoing instrument developments aiming at breaking current experimental limitations are briefly discussed, namely, the coupling of PWR with electrochemical measurements and the expansion of measurements from the visible to the infrared region.
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Affiliation(s)
- Isabel D. Alves
- CBMN UMR 5248 CNRS, University of Bordeaux, Bat. B14 allée Geoffroy St. Hilaire, 33600 Pessac, France
| | - Sophie Lecomte
- CBMN UMR 5248 CNRS, University of Bordeaux, Bat. B14 allée Geoffroy St. Hilaire, 33600 Pessac, France
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15
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Isaacs S, Harté E, Alves ID, Abdulhalim I. Improved Detection of Plasmon Waveguide Resonance Using Diverging Beam, Liquid Crystal Retarder, and Application to Lipid Orientation Determination. SENSORS 2019; 19:s19061402. [PMID: 30901964 PMCID: PMC6471420 DOI: 10.3390/s19061402] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/14/2019] [Accepted: 03/15/2019] [Indexed: 02/06/2023]
Abstract
Plasmon waveguide resonance (PWR) sensors exhibit narrow resonances at the two orthogonal polarizations, transverse electric (TE) and transverse magnetic (TM), which are narrower by almost an order of a magnitude than the standard surface plasmon resonance (SPR), and thus the figure of merit is enhanced. This fact is useful for measuring optical anisotropy of materials on the surface and determining the orientation of molecules with high resolution. Using the diverging beam approach and a liquid crystal retarder, we present experimental results by simultaneous detection of TE and TM polarized resonances as well as using fast higher contrast serial detection with a variable liquid crystal retarder. While simultaneous detection makes the system simpler, a serial one has the advantage of obtaining a larger contrast of the resonances and thus an improved signal-to-noise ratio. Although the sensitivity of the PWR resonances is smaller than the standard SPR, the angular width is much smaller, and thus the figure of merit is improved. When the measurement methodology has a high enough angular resolution, as is the one presented here, the PWR becomes advantageous over other SPR modes. The possibility of carrying out exact numerical simulations for anisotropic molecules using the 4 × 4 matrix approach brings another advantage of the PWR over SPR on the possibility of extracting the orientation of molecules adsorbed to the surface. High sensitivity of the TE and TM signals to the anisotropic molecules orientation is found here, and comparison to the experimental data allowed detection of the orientation of lipids on the sensor surface. The molecular orientations cannot be fully determined from the TM polarization alone as in standard SPR, which underlines the additional advantage of the PWR technique.
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Affiliation(s)
- Sivan Isaacs
- Department of Electrooptics and Photonics Engineering and The Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
| | - Etienne Harté
- CBMN, UMR 5248 CNRS, Université de Bordeaux, Allée Geoffroy St. Hilaire, 33600 Pessac, France.
| | - Isabel D Alves
- CBMN, UMR 5248 CNRS, Université de Bordeaux, Allée Geoffroy St. Hilaire, 33600 Pessac, France.
| | - Ibrahim Abdulhalim
- Department of Electrooptics and Photonics Engineering and The Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
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16
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Harté E, Alves ID, Ihrke I, Elezgaray J. Thickness determination in anisotropic media with plasmon waveguide resonance imaging. OPTICS EXPRESS 2019; 27:3264-3275. [PMID: 30732350 DOI: 10.1364/oe.27.003264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 01/02/2019] [Indexed: 06/09/2023]
Abstract
This paper describes a simple procedure to determine the local thickness of a thin anisotropic layer. It also discriminates between isotropic and anisotropic regions, provided a smoothness hypothesis on the refractive index distribution is satisfied. The procedure is based on the analysis of surface plasmon resonance (SPR) data acquired in an imaging mode. The general arrangement of the setup is the Kretschmann configuration. We show, on an azobenzene modified polymer layer, good agreement between atomic force microscopy and optical measurements of thickness variation.
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17
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Kell DB, Pretorius E. No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases. Biol Rev Camb Philos Soc 2018; 93:1518-1557. [PMID: 29575574 PMCID: PMC6055827 DOI: 10.1111/brv.12407] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 02/12/2018] [Accepted: 02/15/2018] [Indexed: 12/11/2022]
Abstract
Since the successful conquest of many acute, communicable (infectious) diseases through the use of vaccines and antibiotics, the currently most prevalent diseases are chronic and progressive in nature, and are all accompanied by inflammation. These diseases include neurodegenerative (e.g. Alzheimer's, Parkinson's), vascular (e.g. atherosclerosis, pre-eclampsia, type 2 diabetes) and autoimmune (e.g. rheumatoid arthritis and multiple sclerosis) diseases that may appear to have little in common. In fact they all share significant features, in particular chronic inflammation and its attendant inflammatory cytokines. Such effects do not happen without underlying and initially 'external' causes, and it is of interest to seek these causes. Taking a systems approach, we argue that these causes include (i) stress-induced iron dysregulation, and (ii) its ability to awaken dormant, non-replicating microbes with which the host has become infected. Other external causes may be dietary. Such microbes are capable of shedding small, but functionally significant amounts of highly inflammagenic molecules such as lipopolysaccharide and lipoteichoic acid. Sequelae include significant coagulopathies, not least the recently discovered amyloidogenic clotting of blood, leading to cell death and the release of further inflammagens. The extensive evidence discussed here implies, as was found with ulcers, that almost all chronic, infectious diseases do in fact harbour a microbial component. What differs is simply the microbes and the anatomical location from and at which they exert damage. This analysis offers novel avenues for diagnosis and treatment.
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Affiliation(s)
- Douglas B. Kell
- School of ChemistryThe University of Manchester, 131 Princess StreetManchesterLancsM1 7DNU.K.
- The Manchester Institute of BiotechnologyThe University of Manchester, 131 Princess StreetManchesterLancsM1 7DNU.K.
- Department of Physiological SciencesStellenbosch University, Stellenbosch Private Bag X1Matieland7602South Africa
| | - Etheresia Pretorius
- Department of Physiological SciencesStellenbosch University, Stellenbosch Private Bag X1Matieland7602South Africa
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18
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Lee TH, Hirst DJ, Kulkarni K, Del Borgo MP, Aguilar MI. Exploring Molecular-Biomembrane Interactions with Surface Plasmon Resonance and Dual Polarization Interferometry Technology: Expanding the Spotlight onto Biomembrane Structure. Chem Rev 2018; 118:5392-5487. [PMID: 29793341 DOI: 10.1021/acs.chemrev.7b00729] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The molecular analysis of biomolecular-membrane interactions is central to understanding most cellular systems but has emerged as a complex technical challenge given the complexities of membrane structure and composition across all living cells. We present a review of the application of surface plasmon resonance and dual polarization interferometry-based biosensors to the study of biomembrane-based systems using both planar mono- or bilayers or liposomes. We first describe the optical principals and instrumentation of surface plasmon resonance, including both linear and extraordinary transmission modes and dual polarization interferometry. We then describe the wide range of model membrane systems that have been developed for deposition on the chips surfaces that include planar, polymer cushioned, tethered bilayers, and liposomes. This is followed by a description of the different chemical immobilization or physisorption techniques. The application of this broad range of engineered membrane surfaces to biomolecular-membrane interactions is then overviewed and how the information obtained using these techniques enhance our molecular understanding of membrane-mediated peptide and protein function. We first discuss experiments where SPR alone has been used to characterize membrane binding and describe how these studies yielded novel insight into the molecular events associated with membrane interactions and how they provided a significant impetus to more recent studies that focus on coincident membrane structure changes during binding of peptides and proteins. We then discuss the emerging limitations of not monitoring the effects on membrane structure and how SPR data can be combined with DPI to provide significant new information on how a membrane responds to the binding of peptides and proteins.
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Affiliation(s)
- Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Daniel J Hirst
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Ketav Kulkarni
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Mark P Del Borgo
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
| | - Marie-Isabel Aguilar
- Department of Biochemistry and Molecular Biology and Biomedicine Discovery Institute , Monash University , Clayton , VIC 3800 , Australia
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19
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Boyé K, Pujol N, D Alves I, Chen YP, Daubon T, Lee YZ, Dedieu S, Constantin M, Bello L, Rossi M, Bjerkvig R, Sue SC, Bikfalvi A, Billottet C. The role of CXCR3/LRP1 cross-talk in the invasion of primary brain tumors. Nat Commun 2017; 8:1571. [PMID: 29146996 PMCID: PMC5691136 DOI: 10.1038/s41467-017-01686-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Accepted: 10/10/2017] [Indexed: 11/09/2022] Open
Abstract
CXCR3 plays important roles in angiogenesis, inflammation, and cancer. However, the precise mechanism of regulation and activity in tumors is not well known. We focused on CXCR3-A conformation and on the mechanisms controlling its activity and trafficking and investigated the role of CXCR3/LRP1 cross talk in tumor cell invasion. Here we report that agonist stimulation induces an anisotropic response with conformational changes of CXCR3-A along its longitudinal axis. CXCR3-A is internalized via clathrin-coated vesicles and recycled by retrograde trafficking. We demonstrate that CXCR3-A interacts with LRP1. Silencing of LRP1 leads to an increase in the magnitude of ligand-induced conformational change with CXCR3-A focalized at the cell membrane, leading to a sustained receptor activity and an increase in tumor cell migration. This was validated in patient-derived glioma cells and patient samples. Our study defines LRP1 as a regulator of CXCR3, which may have important consequences for tumor biology.
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Affiliation(s)
- Kevin Boyé
- INSERM U1029, Pessac, 33615, France.,Université de Bordeaux, Pessac, 33615, France
| | - Nadège Pujol
- INSERM U1029, Pessac, 33615, France.,Université de Bordeaux, Pessac, 33615, France
| | | | - Ya-Ping Chen
- Institute of Bioinformatics and Structural Biology, NTHU, Hsinchu, 30055, Taiwan
| | - Thomas Daubon
- INSERM U1029, Pessac, 33615, France.,Université de Bordeaux, Pessac, 33615, France.,K.G. Jebsen Brain Tumour Research Centre, Department of Biomedicine, University of Bergen, Bergen, 5009, Norway.,Department of Oncology, Luxembourg Institute of Health, Luxembourg, L-1526, Luxembourg
| | - Yi-Zong Lee
- Institute of Bioinformatics and Structural Biology, NTHU, Hsinchu, 30055, Taiwan
| | - Stephane Dedieu
- CNRS UMR 7369 MEDyC, Université de Reims Champagne-Ardenne, Reims, 51687, France
| | - Marion Constantin
- INSERM U1029, Pessac, 33615, France.,Université de Bordeaux, Pessac, 33615, France
| | - Lorenzo Bello
- Neurosurgical Oncology Unit, Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, Humanitas Resarch Hospital, Milan, 20089, Italy
| | - Marco Rossi
- Neurosurgical Oncology Unit, Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, Humanitas Resarch Hospital, Milan, 20089, Italy
| | - Rolf Bjerkvig
- K.G. Jebsen Brain Tumour Research Centre, Department of Biomedicine, University of Bergen, Bergen, 5009, Norway.,Department of Oncology, Luxembourg Institute of Health, Luxembourg, L-1526, Luxembourg
| | - Shih-Che Sue
- Institute of Bioinformatics and Structural Biology, NTHU, Hsinchu, 30055, Taiwan
| | - Andreas Bikfalvi
- INSERM U1029, Pessac, 33615, France. .,Université de Bordeaux, Pessac, 33615, France.
| | - Clotilde Billottet
- INSERM U1029, Pessac, 33615, France. .,Université de Bordeaux, Pessac, 33615, France.
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20
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Chen YP, Wu HL, Boyé K, Pan CY, Chen YC, Pujol N, Lin CW, Chiu LY, Billottet C, Alves ID, Bikfalvi A, Sue SC. Oligomerization State of CXCL4 Chemokines Regulates G Protein-Coupled Receptor Activation. ACS Chem Biol 2017; 12:2767-2778. [PMID: 28945356 DOI: 10.1021/acschembio.7b00704] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CXCL4 chemokines have antiangiogenic properties, mediated by different mechanisms, including CXCR3 receptor activation. Chemokines have distinct oligomerization states that are correlated with their biological functions. CXCL4 exists as a stable tetramer under physiological conditions. It is unclear whether the oligomerization state impacts CXCL4-receptor interaction. We found that the CXCL4 tetramer is sensitive to pH and salt concentration. Residues Glu28 and Lys50 were important for tetramer formation, and the first β-strand and the C-terminal helix are critical for dimerization. By mutating the critical residues responsible for oligomerization, we generated CXCL4 mutants that behave as dimers or monomers under neutral/physiological conditions. The CXCL4 monomer acts as the minimal active unit for interacting CXCR3A, and sulfation of N-terminal tyrosine residues on the receptor is important for binding. Noticeably, CXCL4L1, a CXCL4 variant that differs by three residues in the C-terminal helix, could activate CXCR3A. CXCL4L1 showed a higher tendency to dissociate into monomers, but native CXCL4 did not. This result indicates that monomeric CXCL4 behaves like CXCL4L1. Thus, in this chemokine family, being in the monomeric state seems critical for interaction with CXCR3A.
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Affiliation(s)
| | | | - Kevin Boyé
- INSERM U1029, 33615 Pessac, France
- University Bordeaux, 33615 Pessac, France
| | | | | | - Nadège Pujol
- INSERM U1029, 33615 Pessac, France
- University Bordeaux, 33615 Pessac, France
| | | | | | - Clotilde Billottet
- INSERM U1029, 33615 Pessac, France
- University Bordeaux, 33615 Pessac, France
| | - Isabel D. Alves
- University Bordeaux, 33615 Pessac, France
- CBMN UMR 5248 CNRS, Pessac, France
| | - Andreas Bikfalvi
- INSERM U1029, 33615 Pessac, France
- University Bordeaux, 33615 Pessac, France
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21
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Boyé K, Billottet C, Pujol N, Alves ID, Bikfalvi A. Ligand activation induces different conformational changes in CXCR3 receptor isoforms as evidenced by plasmon waveguide resonance (PWR). Sci Rep 2017; 7:10703. [PMID: 28878333 PMCID: PMC5587768 DOI: 10.1038/s41598-017-11151-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/21/2017] [Indexed: 12/12/2022] Open
Abstract
The chemokine receptor CXCR3 plays important roles in angiogenesis, inflammation and cancer. Activation studies and biological functions of CXCR3 are complex due to the presence of spliced isoforms. CXCR3-A is known as a pro-tumor receptor whereas CXCR3-B exhibits anti-tumor properties. Here, we focused on the conformational change of CXCR3-A and CXCR3-B after agonist or antagonist binding using Plasmon Waveguide Resonance (PWR). Agonist stimulation induced an anisotropic response with very distinct conformational changes for the two isoforms. The CXCR3 agonist bound CXCR3-A with higher affinity than CXCR3-B. Using various concentrations of SCH546738, a CXCR3 specific inhibitor, we demonstrated that low SCH546738 concentrations (≤1 nM) efficiently inhibited CXCR3-A but not CXCR3-B’s conformational change and activation. This was confirmed by both, biophysical and biological methods. Taken together, our study demonstrates differences in the behavior of CXCR3-A and CXCR3-B upon ligand activation and antagonist inhibition which may be of relevance for further studies aimed at specifically inhibiting the CXCR3A isoform.
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Affiliation(s)
- K Boyé
- INSERM, U1029, Pessac, France.,Université de Bordeaux, Pessac, France
| | - C Billottet
- INSERM, U1029, Pessac, France.,Université de Bordeaux, Pessac, France
| | - N Pujol
- INSERM, U1029, Pessac, France.,Université de Bordeaux, Pessac, France
| | - I D Alves
- Université de Bordeaux, Pessac, France. .,CBMN, UMR 5248 CNRS, Pessac, France.
| | - A Bikfalvi
- INSERM, U1029, Pessac, France. .,Université de Bordeaux, Pessac, France.
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22
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Calmet P, De Maria M, Harté E, Lamb D, Serrano-Vega M, Jazayeri A, Tschammer N, Alves ID. Real time monitoring of membrane GPCR reconstitution by plasmon waveguide resonance: on the role of lipids. Sci Rep 2016; 6:36181. [PMID: 27824122 PMCID: PMC5099921 DOI: 10.1038/srep36181] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 10/12/2016] [Indexed: 01/14/2023] Open
Abstract
G-protein coupled receptors (GPCRs) are important therapeutic targets since more than 40% of the drugs on the market exert their action through these proteins. To decipher the molecular mechanisms of activation and signaling, GPCRs often need to be isolated and reconstituted from a detergent-solubilized state into a well-defined and controllable lipid model system. Several methods exist to reconstitute membrane proteins in lipid systems but usually the reconstitution success is tested at the end of the experiment and often by an additional and indirect method. Irrespective of the method used, the reconstitution process is often an intractable and time-consuming trial-and-error procedure. Herein, we present a method that allows directly monitoring the reconstitution of GPCRs in model planar lipid membranes. Plasmon waveguide resonance (PWR) allows following GPCR lipid reconstitution process without any labeling and with high sensitivity. Additionally, the method is ideal to probe the lipid effect on receptor ligand binding as demonstrated by antagonist binding to the chemokine CCR5 receptor.
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Affiliation(s)
- Pierre Calmet
- Max Planck Institute for the Science of Light, Erlangen, Germany.,Friedrich Alexander University (FAU) Erlangen-Nürnberg, Erlangen, Germany.,Chemistry and Biology of Membranes and Nanoobjects, UMR 5248 CNRS, University of Bordeaux, Bat. B14 allée Geoffroy St. Hilaire, 33600 Pessac, France
| | - Monica De Maria
- Department of Developmental Biology, Friedrich Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - Etienne Harté
- Chemistry and Biology of Membranes and Nanoobjects, UMR 5248 CNRS, University of Bordeaux, Bat. B14 allée Geoffroy St. Hilaire, 33600 Pessac, France
| | - Daniel Lamb
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, Hertfordshire AL7 3AX, UK
| | - Maria Serrano-Vega
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, Hertfordshire AL7 3AX, UK
| | - Ali Jazayeri
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, Hertfordshire AL7 3AX, UK
| | - Nuska Tschammer
- Department of Developmental Biology, Friedrich Alexander University of Erlangen-Nürnberg, Erlangen, Germany.,NanoTemper Technologies GmbH, Munich, Germany
| | - Isabel D Alves
- Chemistry and Biology of Membranes and Nanoobjects, UMR 5248 CNRS, University of Bordeaux, Bat. B14 allée Geoffroy St. Hilaire, 33600 Pessac, France
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Lee TH, Hirst DJ, Aguilar MI. New insights into the molecular mechanisms of biomembrane structural changes and interactions by optical biosensor technology. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1868-85. [PMID: 26009270 DOI: 10.1016/j.bbamem.2015.05.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 05/15/2015] [Accepted: 05/17/2015] [Indexed: 12/31/2022]
Abstract
Biomolecular-membrane interactions play a critical role in the regulation of many important biological processes such as protein trafficking, cellular signalling and ion channel formation. Peptide/protein-membrane interactions can also destabilise and damage the membrane which can lead to cell death. Characterisation of the molecular details of these binding-mediated membrane destabilisation processes is therefore central to understanding cellular events such as antimicrobial action, membrane-mediated amyloid aggregation, and apoptotic protein induced mitochondrial membrane permeabilisation. Optical biosensors have provided a unique approach to characterising membrane interactions allowing quantitation of binding events and new insight into the kinetic mechanism of these interactions. One of the most commonly used optical biosensor technologies is surface plasmon resonance (SPR) and there have been an increasing number of studies reporting the use of this technique for investigating biophysical analysis of membrane-mediated events. More recently, a number of new optical biosensors based on waveguide techniques have been developed, allowing membrane structure changes to be measured simultaneously with mass binding measurements. These techniques include dual polarisation interferometry (DPI), plasmon waveguide resonance spectroscopy (PWR) and optical waveguide light mode spectroscopy (OWLS). These techniques have expanded the application of optical biosensors to allow the analysis of membrane structure changes during peptide and protein binding. This review provides a theoretical and practical overview of the application of biosensor technology with a specific focus on DPI, PWR and OWLS to study biomembrane-mediated events and the mechanism of biomembrane disruption. This article is part of a Special Issue entitled: Lipid-protein interactions.
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Affiliation(s)
- Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, Clayton, VIC 3800, Australia
| | - Daniel J Hirst
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, Clayton, VIC 3800, Australia
| | - Marie-Isabel Aguilar
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, Clayton, VIC 3800, Australia.
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Alves I, Kurylo I, Coffinier Y, Siriwardena A, Zaitsev V, Harté E, Boukherroub R, Szunerits S. Plasmon waveguide resonance for sensing glycan–lectin interactions. Anal Chim Acta 2015; 873:71-9. [DOI: 10.1016/j.aca.2015.02.060] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/18/2015] [Accepted: 02/22/2015] [Indexed: 12/18/2022]
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Henry S, Vignaud H, Bobo C, Decossas M, Lambert O, Harte E, Alves ID, Cullin C, Lecomte S. Interaction of Aβ(1-42) amyloids with lipids promotes "off-pathway" oligomerization and membrane damage. Biomacromolecules 2015; 16:944-50. [PMID: 25689632 DOI: 10.1021/bm501837w] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The toxicity of amyloids, as Aβ(1-42) involved in Alzheimer disease, is a subject under intense scrutiny. Many studies link their toxicity to the existence of various intermediate structures prior to fiber formation and/or their specific interaction with membranes. In this study we focused on the interaction between membrane models and Aβ(1-42) peptides and variants (L34T, mG37C) produced in E. coli and purified in monomeric form. We evaluated the interaction of a toxic stable oligomeric form (oG37C) with membranes as comparison. Using various biophysical techniques as fluorescence and plasmon waveguide resonance, we clearly established that the oG37C interacts strongly with membranes leading to its disruption. All the studied peptides destabilized liposomes and accumulated slowly on the membrane (rate constant 0.02 min(-1)). Only the oG37C exhibited a particular pattern of interaction, comprising two steps: the initial binding followed by membrane reorganization. Cryo-TEM was used to visualize the peptide effect on liposome morphologies. Both oG37C and mG37C lead to PG membrane fragmentation. The PG membrane promotes peptide oligomerization, implicated in membrane disruption. WT (Aβ(1-42)) also perturbs liposome organization with membrane deformation rather than disruption. For all the peptides studied, their interaction with the membranes changes their fibrillization process, with less fibers and more small aggregates being formed. These studies allowed to establish, a correlation between toxicity, fiber formation, and membrane disruption.
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Affiliation(s)
- Sarah Henry
- Chimie et Biologie des Membranes et Nanoobjets, CBMN CNRS UMR 5248, Université de Bordeaux , Allée Geoffroy de Saint Hilaire, 33600 Pessac, France
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26
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Witschas K, Jobin ML, Korkut DN, Vladan MM, Salgado G, Lecomte S, Vlachova V, Alves ID. Interaction of a peptide derived from C-terminus of human TRPA1 channel with model membranes mimicking the inner leaflet of the plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1147-56. [PMID: 25687973 DOI: 10.1016/j.bbamem.2015.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 01/21/2015] [Accepted: 02/04/2015] [Indexed: 11/29/2022]
Abstract
The transient receptor potential ankyrin 1 channel (TRPA1) belongs to the TRP cation channel superfamily that responds to a panoply of stimuli such as changes in temperature, calcium levels, reactive oxygen and nitrogen species and lipid mediators among others. The TRP superfamily has been implicated in diverse pathological states including neurodegenerative disorders, kidney diseases, inflammation, pain and cancer. The intracellular C-terminus is an important regulator of TRP channel activity. Studies with this and other TRP superfamily members have shown that the C-terminus association with lipid bilayer alters channel sensitivity and activation, especially interactions occurring through basic residues. Nevertheless, it is not yet clear how this process takes place and which regions in the C-terminus would be responsible for such membrane recognition. With that in mind, herein the first putative membrane interacting region of the C-terminus of human TRPA1, (corresponding to a 29 residue peptide, IAEVQKHASLKRIAMQVELHTSLEKKLPL) named H1 due to its potential helical character was chosen for studies of membrane interaction. The affinity of H1 to lipid membranes, H1 structural changes occurring upon this interaction as well as effects of this interaction in lipid organization and integrity were investigated using a biophysical approach. Lipid models systems composed of zwitterionic and anionic lipids, namely those present in the lipid membrane inner leaflet, where H1 is prone to interact, where used. The study reveals a strong interaction and affinity of H1 as well as peptide structuration especially with membranes containing anionic lipids. Moreover, the interactions and peptide structure adoption are headgroup specific.
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Affiliation(s)
- Katja Witschas
- CBMN-UMR 5248 CNRS, University of Bordeaux, IPB, Allée Geoffroy St. Hilaire, 33600 Pessac, France; Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Marie-Lise Jobin
- CBMN-UMR 5248 CNRS, University of Bordeaux, IPB, Allée Geoffroy St. Hilaire, 33600 Pessac, France
| | - Dursun Nizam Korkut
- INSERM, U869, ARNA Laboratory, University of Bordeaux, 2 rue Robert Escarpit, 33607 Pessac, France
| | - Maria Magdalena Vladan
- CBMN-UMR 5248 CNRS, University of Bordeaux, IPB, Allée Geoffroy St. Hilaire, 33600 Pessac, France
| | - Gilmar Salgado
- INSERM, U869, ARNA Laboratory, University of Bordeaux, 2 rue Robert Escarpit, 33607 Pessac, France
| | - Sophie Lecomte
- CBMN-UMR 5248 CNRS, University of Bordeaux, IPB, Allée Geoffroy St. Hilaire, 33600 Pessac, France
| | - Viktorie Vlachova
- Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Isabel D Alves
- CBMN-UMR 5248 CNRS, University of Bordeaux, IPB, Allée Geoffroy St. Hilaire, 33600 Pessac, France.
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Bobbitt JM, Weibel SC, Elshobaki M, Chaudhary S, Smith EA. Fourier transform-plasmon waveguide spectroscopy: a nondestructive multifrequency method for simultaneously determining polymer thickness and apparent index of refraction. Anal Chem 2014; 86:11957-61. [PMID: 25413025 DOI: 10.1021/ac504103g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Fourier transform (FT)-plasmon waveguide resonance (PWR) spectroscopy measures light reflectivity at a waveguide interface as the incident frequency and angle are scanned. Under conditions of total internal reflection, the reflected light intensity is attenuated when the incident frequency and angle satisfy conditions for exciting surface plasmon modes in the metal as well as guided modes within the waveguide. Expanding upon the concept of two-frequency surface plasmon resonance developed by Peterlinz and Georgiadis [Opt. Commun. 1996, 130, 260], the apparent index of refraction and the thickness of a waveguide can be measured precisely and simultaneously by FT-PWR with an average percent relative error of 0.4%. Measuring reflectivity for a range of frequencies extends the analysis to a wide variety of sample compositions and thicknesses since frequencies with the maximum attenuation can be selected to optimize the analysis. Additionally, the ability to measure reflectivity curves with both p- and s-polarized light provides anisotropic indices of refraction. FT-PWR is demonstrated using polystyrene waveguides of varying thickness, and the validity of FT-PWR measurements are verified by comparing the results to data from profilometry and atomic force microscopy (AFM).
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Affiliation(s)
- Jonathan M Bobbitt
- The Ames Laboratory, U.S. Department of Energy , Ames, Iowa 50011, United States
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