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Messelmani T, Le Goff A, Soncin F, Souguir Z, Merlier F, Maubon N, Legallais C, Leclerc E, Jellali R. Coculture model of a liver sinusoidal endothelial cell barrier and HepG2/C3a spheroids-on-chip in an advanced fluidic platform. J Biosci Bioeng 2024; 137:64-75. [PMID: 37973520 DOI: 10.1016/j.jbiosc.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 10/26/2023] [Accepted: 10/26/2023] [Indexed: 11/19/2023]
Abstract
The liver is one of the main organs involved in the metabolism of xenobiotics and a key organ in toxicity studies. Prior to accessing the hepatocytes, xenobiotics pass through the hepatic sinusoid formed by liver sinusoidal endothelial cells (LSECs). The LSECs barrier regulates the kinetics and concentrations of the xenobiotics before their metabolic processing by the hepatocytes. To mimic this physiological situation, we developed an in vitro model reproducing an LSECs barrier in coculture with a hepatocyte biochip, using a fluidic platform. This technology made dynamic coculture and tissue crosstalk possible. SK-HEP-1 and HepG2/C3a cells were used as LSECs and as hepatocyte models, respectively. We confirmed the LSECs phenotype by measuring PECAM-1 and stabilin-2 expression levels and the barrier's permeability/transport properties with various molecules. The tightness of the SK-HEP-1 barrier was enhanced in the dynamic coculture. The morphology, albumin secretion, and gene expression levels of markers of HepG2/C3a were not modified by coculture with the LSECs barrier. Using acetaminophen, a well-known hepatotoxic drug, to study tissue crosstalk, there was a reduction in the expression levels of the LSECs markers stabilin-2 and PECAM-1, and a modification of those of CLEC4M and KDR. No HepG2/C3a toxicity was observed. The metabolisation of acetaminophen by HepG2/C3a monocultures and cocultures was confirmed. Although primary cells are required to propose a fully relevant model, the present approach highlights the potential of our system for investigating xenobiotic metabolism and toxicity.
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Affiliation(s)
- Taha Messelmani
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319, 60203 Compiègne Cedex, France
| | - Anne Le Goff
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319, 60203 Compiègne Cedex, France
| | - Fabrice Soncin
- CNRS/IIS/Centre Oscar Lambret/Lille University SMMiL-E Project, CNRS Délégation Hauts-de-France, 43 Avenue le Corbusier, 59800 Lille, France; CNRS, IRL2820, Laboratory for Integrated Micro Mechatronic Systems, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Zied Souguir
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Franck Merlier
- Université de Technologie de Compiègne, UPJV, CNRS, Enzyme and Cell Engineering, Centre de Recherche Royallieu, Cedex CS 60319, 60203 Compiègne, France
| | - Nathalie Maubon
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Cécile Legallais
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319, 60203 Compiègne Cedex, France
| | - Eric Leclerc
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319, 60203 Compiègne Cedex, France; CNRS, IRL2820, Laboratory for Integrated Micro Mechatronic Systems, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Rachid Jellali
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319, 60203 Compiègne Cedex, France.
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Messelmani T, Le Goff A, Soncin F, Gilard F, Souguir Z, Maubon N, Gakière B, Legallais C, Leclerc E, Jellali R. Investigation of the metabolomic crosstalk between liver sinusoidal endothelial cells and hepatocytes exposed to paracetamol using organ-on-chip technology. Toxicology 2023; 492:153550. [PMID: 37209942 DOI: 10.1016/j.tox.2023.153550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/09/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
Organ-on-chip technology is a promising in vitro approach recapitulating human physiology for the study of responses to drug exposure. Organ-on-chip cell cultures have paved new grounds for testing and understanding metabolic dose-responses when evaluating pharmaceutical and environmental toxicity. Here, we present a metabolomic investigation of a coculture of liver sinusoidal endothelial cells (LSECs, SK-HEP-1) with hepatocytes (HepG2/C3a) using advanced organ-on-chip technology. To reproduce the physiology of the sinusoidal barrier, LSECs were separated from hepatocytes by a membrane (culture insert integrated organ-on-chip platform). The tissues were exposed to acetaminophen (APAP), an analgesic drug widely used as a xenobiotic model in liver and HepG2/C3a studies. The differences between the SK-HEP-1, HepG2/C3a monocultures and SK-HEP-1/HepG2/C3a cocultures, treated or not with APAP, were identified from metabolomic profiles using supervised multivariate analysis. The pathway enrichment coupled with metabolite analysis of the corresponding metabolic fingerprints contributed to extracting the specificity of each type of culture and condition. In addition, we analysed the responses to APAP treatment by mapping the signatures with significant modulation of the biological processes of the SK-HEP-1 APAP, HepG2/C3a APAP and SK-HEP-1/HepG2/C3a APAP conditions. Furthermore, our model shows how the presence of the LSECs barrier and APAP first pass can modify the metabolism of HepG2/C3a. Altogether, this study demonstrates the potential of a "metabolomic-on-chip" strategy for pharmaco-metabolomic applications predicting individual response to drugs.
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Affiliation(s)
- Taha Messelmani
- Université de technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de recherche Royallieu CS 60319, 60203 Compiègne Cedex, France
| | - Anne Le Goff
- Université de technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de recherche Royallieu CS 60319, 60203 Compiègne Cedex, France
| | - Fabrice Soncin
- CNRS/IIS/Centre Oscar Lambret/Lille University SMMiL-E Project, CNRS Délégation Hauts-de-France, 43 Avenue le Corbusier, 59800 Lille, France; CNRS IRL 2820, Laboratory for Integrated Micro Mechatronic Systems, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Japan
| | - Françoise Gilard
- Institute of Plant Sciences Paris-Saclay (IPS2), UMR 9213/UMR1403, CNRS, INRA, Université Paris-Sud, Université d'Evry, Université Paris-Diderot, Université Paris Saclay, Bâtiment 630 Rue Noetzlin, 91192, Gif-sur-Yvette Cedex, France
| | - Zied Souguir
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Nathalie Maubon
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Bertrand Gakière
- Institute of Plant Sciences Paris-Saclay (IPS2), UMR 9213/UMR1403, CNRS, INRA, Université Paris-Sud, Université d'Evry, Université Paris-Diderot, Université Paris Saclay, Bâtiment 630 Rue Noetzlin, 91192, Gif-sur-Yvette Cedex, France
| | - Cécile Legallais
- Université de technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de recherche Royallieu CS 60319, 60203 Compiègne Cedex, France
| | - Eric Leclerc
- Université de technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de recherche Royallieu CS 60319, 60203 Compiègne Cedex, France; CNRS IRL 2820, Laboratory for Integrated Micro Mechatronic Systems, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Japan
| | - Rachid Jellali
- Université de technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de recherche Royallieu CS 60319, 60203 Compiègne Cedex, France.
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Messelmani T, Le Goff A, Souguir Z, Maes V, Roudaut M, Vandenhaute E, Maubon N, Legallais C, Leclerc E, Jellali R. Development of Liver-on-Chip Integrating a Hydroscaffold Mimicking the Liver’s Extracellular Matrix. Bioengineering (Basel) 2022; 9:bioengineering9090443. [PMID: 36134989 PMCID: PMC9495334 DOI: 10.3390/bioengineering9090443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/23/2022] [Accepted: 08/31/2022] [Indexed: 12/12/2022] Open
Abstract
The 3Rs guidelines recommend replacing animal testing with alternative models. One of the solutions proposed is organ-on-chip technology in which liver-on-chip is one of the most promising alternatives for drug screening and toxicological assays. The main challenge is to achieve the relevant in vivo-like functionalities of the liver tissue in an optimized cellular microenvironment. Here, we investigated the development of hepatic cells under dynamic conditions inside a 3D hydroscaffold embedded in a microfluidic device. The hydroscaffold is made of hyaluronic acid and composed of liver extracellular matrix components (galactosamine, collagen I/IV) with RGDS (Arg-Gly-Asp-Ser) sites for cell adhesion. The HepG2/C3A cell line was cultured under a flow rate of 10 µL/min for 21 days. After seeding, the cells formed aggregates and proliferated, forming 3D spheroids. The cell viability, functionality, and spheroid integrity were investigated and compared to static cultures. The results showed a 3D aggregate organization of the cells up to large spheroid formations, high viability and albumin production, and an enhancement of HepG2 cell functionalities. Overall, these results highlighted the role of the liver-on-chip model coupled with a hydroscaffold in the enhancement of cell functions and its potential for engineering a relevant liver model for drug screening and disease study.
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Affiliation(s)
- Taha Messelmani
- CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu-CS 60319, Université de Technologie de Compiègne, 60203 Compiègne, France
| | - Anne Le Goff
- CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu-CS 60319, Université de Technologie de Compiègne, 60203 Compiègne, France
- Correspondence: (A.L.G.); (R.J.)
| | - Zied Souguir
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Victoria Maes
- CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu-CS 60319, Université de Technologie de Compiègne, 60203 Compiègne, France
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Méryl Roudaut
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Elodie Vandenhaute
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Nathalie Maubon
- HCS Pharma, 250 rue Salvador Allende, Biocentre Fleming Bâtiment A, 59120 Loos, France
| | - Cécile Legallais
- CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu-CS 60319, Université de Technologie de Compiègne, 60203 Compiègne, France
| | - Eric Leclerc
- CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu-CS 60319, Université de Technologie de Compiègne, 60203 Compiègne, France
- CNRS IRL 2820, Laboratory for Integrated Micro Mechatronic Systems, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Rachid Jellali
- CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu-CS 60319, Université de Technologie de Compiègne, 60203 Compiègne, France
- Correspondence: (A.L.G.); (R.J.)
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Le Goff A, Louvel S, Boullier H, Allard P. Toxicoepigenetics for Risk Assessment: Bridging the Gap Between Basic and Regulatory Science. Epigenet Insights 2022; 15:25168657221113149. [PMID: 35860623 PMCID: PMC9290111 DOI: 10.1177/25168657221113149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 06/23/2022] [Indexed: 12/02/2022] Open
Abstract
Toxicoepigenetics examines the health effects of environmental exposure associated with, or mediated by, changes in the epigenome. Despite high expectations, toxicoepigenomic data and methods have yet to become significantly utilized in chemical risk assessment. This article draws on a social science framework to highlight hitherto overlooked structural barriers to the incorporation of toxicoepigenetics in risk assessment and to propose ways forward. The present barriers stem not only from the lack of maturity of the field but also from differences in constraints and standards between the data produced by toxicoepigenetics and the regulatory science data that risk assessment processes require. Criteria and strategies that frame the validation of knowledge used for regulatory purposes limit the application of basic research in toxicoepigenetics toward risk assessment. First, the need in regulatory toxicology for standardized methods that form a consensus between regulatory agencies, basic research, and the industry conflicts with the wealth of heterogeneous data in toxicoepigenetics. Second, molecular epigenetic data do not readily translate into typical toxicological endpoints. Third, toxicoepigenetics investigates new forms of toxicity, in particular low-dose and long-term effects, that do not align well with the traditional framework of regulatory toxicology. We propose that increasing the usefulness of epigenetic data for risk assessment will require deliberate efforts on the part of the toxicoepigenetics community in 4 areas: fostering the understanding of epigenetics among risk assessors, developing knowledge infrastructure to demonstrate applicability, facilitating the normalization and exchange of data, and opening the field to other stakeholders.
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Affiliation(s)
- Anne Le Goff
- The Institute for Society and Genetics and The EpiCenter, University of California Los Angeles (UCLA), Los Angeles, CA, USA
| | - Séverine Louvel
- Université Grenoble Alpes, CNRS, Sciences Po Grenoble, PACTE, Grenoble, France and Institut Universitaire de France, Paris, France
| | - Henri Boullier
- Centre National de la Recherche Scientifique, IRISSO, Université Paris-Dauphine-PSL, Paris, France
| | - Patrick Allard
- The Institute for Society and Genetics and The EpiCenter, University of California Los Angeles (UCLA), Los Angeles, CA, USA.,Molecular Biology Institute, University of California Los Angeles (UCLA), Los Angeles, CA, USA
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Messelmani T, Morisseau L, Sakai Y, Legallais C, Le Goff A, Leclerc E, Jellali R. Liver organ-on-chip models for toxicity studies and risk assessment. Lab Chip 2022; 22:2423-2450. [PMID: 35694831 DOI: 10.1039/d2lc00307d] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The liver is a key organ that plays a pivotal role in metabolism and ensures a variety of functions in the body, including homeostasis, synthesis of essential components, nutrient storage, and detoxification. As the centre of metabolism for exogenous molecules, the liver is continuously exposed to a wide range of compounds, such as drugs, pesticides, and environmental pollutants. Most of these compounds can cause hepatotoxicity and lead to severe and irreversible liver damage. To study the effects of chemicals and drugs on the liver, most commonly, animal models or in vitro 2D cell cultures are used. However, data obtained from animal models lose their relevance when extrapolated to the human metabolic situation and pose ethical concerns, while 2D static cultures are poorly predictive of human in vivo metabolism and toxicity. As a result, there is a widespread need to develop relevant in vitro liver models for toxicology studies. In recent years, progress in tissue engineering, biomaterials, microfabrication, and cell biology has created opportunities for more relevant in vitro models for toxicology studies. Of these models, the liver organ-on-chip (OoC) has shown promising results by reproducing the in vivo behaviour of the cell/organ or a group of organs, the controlled physiological micro-environment, and in vivo cellular metabolic responses. In this review, we discuss the development of liver organ-on-chip technology and its use in toxicity studies. First, we introduce the physiology of the liver and summarize the traditional experimental models for toxicity studies. We then present liver OoC technology, including the general concept, materials used, cell sources, and different approaches. We review the prominent liver OoC and multi-OoC integrating the liver for drug and chemical toxicity studies. Finally, we conclude with the future challenges and directions for developing or improving liver OoC models.
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Affiliation(s)
- Taha Messelmani
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu CS 60319, 60203 Compiègne Cedex, France.
| | - Lisa Morisseau
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu CS 60319, 60203 Compiègne Cedex, France.
| | - Yasuyuki Sakai
- CNRS IRL 2820, Laboratory for Integrated Micro Mechatronic Systems, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan.
- Department of Chemical Engineering, Faculty of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Cécile Legallais
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu CS 60319, 60203 Compiègne Cedex, France.
| | - Anne Le Goff
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu CS 60319, 60203 Compiègne Cedex, France.
| | - Eric Leclerc
- CNRS IRL 2820, Laboratory for Integrated Micro Mechatronic Systems, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan.
| | - Rachid Jellali
- Université de Technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de Recherche Royallieu CS 60319, 60203 Compiègne Cedex, France.
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Baranger C, Pezron I, Lins L, Deleu M, Le Goff A, Fayeulle A. A compartmentalized microsystem helps understanding the uptake of benzo[a]pyrene by fungi during soil bioremediation processes. Sci Total Environ 2021; 784:147151. [PMID: 33895515 DOI: 10.1016/j.scitotenv.2021.147151] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/01/2021] [Accepted: 04/11/2021] [Indexed: 06/12/2023]
Abstract
Hydrophobic organic soil contaminants such as polycyclic aromatic hydrocarbons (PAH) are poorly mobile in the aqueous phase and tend to sorb to the soil matrix, resulting in low bioavailability. Some filamentous fungi are efficient in degrading this kind of pollutants. However, the mechanism of mobilization of hydrophobic compounds by non-motile microorganisms such as filamentous fungi needs investigations to improve pollutant bioavailability and bioremediation efficiency. Usual homogeneous media for microbial growth in the lab are poorly suited to model the soil, which is a compartmentalized and heterogeneous habitat. A microfluidic device was designed to implement a compartmentalization of the fungal inoculum and the source of the pollutant benzo[a]pyrene (BaP) as a deposit of solid crystals in order to gain a further insight into the mechanisms involved in the access to the contaminant and its uptake in soils. Thus in this device, two chambers are connected by an array of parallel microchannels that are wide enough to allow individual hyphae to grow through them. Macro-cultures of Talaromyces helicus in direct contact with BaP have shown its uptake and intracellular storage in lipid bodies despite the low propensity of BaP to cross aqueous phases as shown by simulation. Observations of T. helicus in the microfluidic device through laser scanning confocal microscopy indicate preferential uptake of BaP at a close range and through contact with the cell wall. However faint staining of some hyphae before contact with the deposit also suggests an extracellular transport phenomenon. Macro-culture filtrates analyses have shown that T. helicus releases extracellular non-lipidic surface-active compounds able to lower the surface tension of culture filtrates to 49.4 mN/m. Thus, these results highlight the significance of active mechanisms to reach hydrophobic contaminants before their uptake by filamentous fungi in compartmentalized micro-environments and the potential to improve them through biostimulation approaches for soil mycoremediation.
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Affiliation(s)
- Claire Baranger
- Université de technologie de Compiègne, ESCOM, TIMR (Integrated Transformations of Renewable Matter), Centre de Recherche Royallieu - CS 60 319 - 60 203 Compiègne Cedex, France
| | - Isabelle Pezron
- Université de technologie de Compiègne, ESCOM, TIMR (Integrated Transformations of Renewable Matter), Centre de Recherche Royallieu - CS 60 319 - 60 203 Compiègne Cedex, France
| | - Laurence Lins
- TERRA Research Center, Laboratory of Molecular Biophysics at Interfaces, SFR Condorcet, Gembloux Agro-Bio Tech, University of Liege, Passage des Déportés, 2, 5030 Gembloux, Belgium
| | - Magali Deleu
- TERRA Research Center, Laboratory of Molecular Biophysics at Interfaces, SFR Condorcet, Gembloux Agro-Bio Tech, University of Liege, Passage des Déportés, 2, 5030 Gembloux, Belgium
| | - Anne Le Goff
- Université de technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de recherche Royallieu - CS 60 319 - 60 203 Compiègne Cedex, France.
| | - Antoine Fayeulle
- Université de technologie de Compiègne, ESCOM, TIMR (Integrated Transformations of Renewable Matter), Centre de Recherche Royallieu - CS 60 319 - 60 203 Compiègne Cedex, France.
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Häner E, Vesperini D, Salsac AV, Le Goff A, Juel A. Sorting of capsules according to their stiffness: from principle to application. Soft Matter 2021; 17:3722-3732. [PMID: 33688883 DOI: 10.1039/d0sm02249g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We assess experimentally the ability of a simple flow-based sorting device, recently proposed numerically by [Zhu et al., Soft Matter, 2014, 10, 7705-7711], to separate capsules according to their stiffness. The device consists of a single pillar with a half-cylinder cross-section which partially obstructs a flow channel so that initially centred, propagating capsules deform and circumvent the obstacle into an expanding channel (or diffuser). We perform experiments with millimetric capsules of fixed size which indicate that the deviation of the capsule in the diffuser varies monotonically with a capillary number - the ratio of viscous to elastic stresses - where the elastic stresses are measured independently to include the effects of pre-inflation, membrane thickness and material properties. We find that soft capsules with resistance to deformation differing by a factor of 1.5 can be reliably separated in the diffuser but that experimental variability increases significantly with capsule stiffness. We extend the study to populations of microcapsules with size polydispersity. We find that the combined effects of increasing capsule deformability and relative constriction of the device with increasing capsule size enable the tuning of the imposed flow so that capsules can be separated based on their shear modulus but irrespectively of their size.
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Affiliation(s)
- Edgar Häner
- Manchester Centre for Nonlinear Dynamics & School of Physics & Astronomy, The University of Manchester, Manchester M13 9PL, UK.
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Le Goff A, Allard P, Landecker H. Heritable changeability: Epimutation and the legacy of negative definition in epigenetic concepts. Stud Hist Philos Sci 2021; 86:35-46. [PMID: 33965662 DOI: 10.1016/j.shpsa.2020.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/27/2020] [Indexed: 06/12/2023]
Abstract
Epigenetic concepts are fundamentally shaped by a legacy of negative definition, often understood by what they are not. Yet the function and implication of negative definition for scientific discourse has thus far received scant attention. Using the term epimutation as exemplar, we analyze the paradoxical like-but-unlike structure of a term that must simultaneously connect with but depart from genetic concepts. We assess the historical forces structuring the use of epimutation and like terms such as paramutation. This analysis highlights the positive characteristics defining epimutation: the regularity, oxymoronic temporality, and materiality of stable processes. Integrating historical work, ethnographic observation, and insights from philosophical practice-oriented conceptual analysis, we detail the distinctive epistemic goals the epimutation concept fulfils in medicine, plant biology and toxicology. Epimutation and allied epigenetic terms have succeeded by being mutation-like and recognizable, yet have failed to consolidate for exactly the same reason: they are tied simultaneously by likeness and opposition to nouns that describe things that are assumed to persist unchanged over space and time. Moreover, negative definition casts the genetic-epigenetic relationship as an either/or binary, overshadowing continuities and connections. This analysis is intended to assist practitioners and observers of genetics and epigenetics in recognizing and moving beyond the conceptual legacies of negative definition.
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Affiliation(s)
- Anne Le Goff
- The Institute for Society and Genetics & the EpiCenter, University of California, UCLA Institute for Society and Genetics, 621 Charles E. Young Dr., South Box 957221, 3360 LSB, Los Angeles, USA.
| | - Patrick Allard
- The Institute for Society and Genetics & the EpiCenter, University of California, UCLA Institute for Society and Genetics, 621 Charles E. Young Dr., South Box 957221, 3360 LSB, Los Angeles, USA.
| | - Hannah Landecker
- Department of Sociology, The Institute for Society and Genetics & the EpiCenter, University of California, UCLA Institute for Society and Genetics, 621 Charles E. Young Dr, South Box 957221, 3360 LSB, Los Angeles, USA.
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Abstract
The Weismann barrier has long been regarded as a basic tenet of biology. However, upon close examination of its historical origins and August Weismann's own writings, questions arise as to whether such a status is warranted. As scientific research has advanced, the persistence of the concept of the barrier has left us with the same dichotomies Weismann contended with over 100 years ago: germ or soma, gene or environment, hard or soft inheritance. These dichotomies distract from the more important questions we need to address going forward. In this review, we will examine the theories that have shaped Weismann's thinking, how the concept of the Weismann barrier emerged, and the limitations that it carries. We will contrast the principles underlying the barrier with recent and less recent findings in developmental biology and transgenerational epigenetic inheritance that have profoundly eroded the oppositional view of germline vs. soma. Discarding the barrier allows us to examine the interactive processes and their response to environmental context that generate germ cells in the first place, determine the entirety of what is inherited through them, and set the trajectory for the health status of the progeny they bear.
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Affiliation(s)
- Abigail P. Bline
- Molecular Toxicology Interdepartmental Program, University of California Los Angeles, Los Angeles, CA 90095, USA;
| | - Anne Le Goff
- UCLA EpiCenter on Epigenetics, Reproduction & Society, University of California Los Angeles, Los Angeles, CA 90095, USA;
- Institute for Society & Genetics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Patrick Allard
- Molecular Toxicology Interdepartmental Program, University of California Los Angeles, Los Angeles, CA 90095, USA;
- UCLA EpiCenter on Epigenetics, Reproduction & Society, University of California Los Angeles, Los Angeles, CA 90095, USA;
- Institute for Society & Genetics, University of California Los Angeles, Los Angeles, CA 90095, USA
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Baranger C, Fayeulle A, Le Goff A. Microfluidic monitoring of the growth of individual hyphae in confined environments. R Soc Open Sci 2020; 7:191535. [PMID: 32968492 PMCID: PMC7481688 DOI: 10.1098/rsos.191535] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
Soil fungi have the ability to form large mycelial networks. They rely on the resources available in the soil to produce biomass and are able to degrade complex biomolecules. Some of them can even degrade recalcitrant organic pollutants and are considered as promising candidates for soil bioremediation strategies. However, the success of this approach depends on the ability of fungi to colonize the soil matrix, where they encounter spatial and temporal variations of confinement, humidity and nutrient concentration. In this paper, we present a study of fungal growth at the scale of single hyphae in a microfluidic device, allowing fine control of nutrient and water supply. Time-lapse microscopy allowed simultaneous monitoring of the growth of dozens of hyphae of Talaromyces helicus, a soil isolate, and of the model fungus Neurospora crassa through parallel microchannels. The distributions of growth velocity obtained for each strain were compared with measurements obtained in macroscopic solid culture. For the two strains used in the study, confinement caused the growth velocity to drop in comparison with unconfined experiments. In addition, N. crassa was also limited in its growth by the nutrient supply, while the microfluidic culture conditions seemed better suited for T. helicus. Qualitative observations of fungi growing in microfluidic chambers without lateral confinement also revealed that side walls influence the branching behaviour of hyphae. This study is one of the first to consider the confinement degree within soil microporosities as a key factor of fungal growth, and to address its effect, along with physicochemical parameters, on soil colonization, notably for bioremediation purposes.
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Affiliation(s)
- Claire Baranger
- Université de technologie de Compiègne, ESCOM, TIMR (Integrated Transformations of Renewable Matter), Biomechanics and Bioengineering, Centre de recherche Royallieu - CS 60 319 - 60 203 Compiègne Cedex, France
| | - Antoine Fayeulle
- Université de technologie de Compiègne, ESCOM, TIMR (Integrated Transformations of Renewable Matter), Biomechanics and Bioengineering, Centre de recherche Royallieu - CS 60 319 - 60 203 Compiègne Cedex, France
| | - Anne Le Goff
- Université de technologie de Compiègne, CNRS, Biomechanics and Bioengineering, Centre de recherche Royallieu - CS 60 319 - 60 203 Compiègne Cedex, France
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11
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Dubois M, Louvel S, Le Goff A, Guaspare C, Allard P. Epigenetics in the public sphere: interdisciplinary perspectives. Environ Epigenet 2019; 5:dvz019. [PMID: 31660206 PMCID: PMC6812041 DOI: 10.1093/eep/dvz019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 09/02/2019] [Accepted: 09/18/2019] [Indexed: 05/04/2023]
Abstract
Despite the high public interest in epigenetics, few scholars have empirically investigated the forms, reasons and consequences of the public circulation of epigenetics. Using an original database focusing on 'lifestyle' or 'everyday' epigenetics, this article aims to promote an open-minded and interdisciplinary dialogue between the public appropriation of epigenetics and the current scientific state of the art. It raises three main questions: Are there any specific modes of circulation of epigenetics in the general public? Why does epigenetics seem so appealing to the public? Within the public repertoire of epigenetics, is it possible to identify some specific knowledge claims and, if so, given the current state of the art, what is their degree of accuracy? The article argues that the social diffusion of epigenetics frequently carries on beliefs and misconceptions about genetics and epigenetics. The social life of epigenetics fuels a collective 'illusion' of control and empowerment on the basis of which new markets expand. More unexpectedly, this article underlines the emergence of a new scientific culture, i.e. the 'scientifization' of the cultural appropriation of epigenetics. Our analysis can inform the scientific community about the current and evolving state of the public representation of epigenetics and help it frame outreach activities.
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Affiliation(s)
- Michel Dubois
- Epigenetics, Data, Politics (EpiDaPo), CNRS, The George Washington University, Washington, DC, USA
- Groupe d'Étude des Méthodes de l'Analyse Sociologique de la Sorbonne (GEMASS), CNRS, Sorbonne University, Paris, France
| | - Séverine Louvel
- Univ. Grenoble Alpes, CNRS, Sciences Po Grenoble, PACTE, Grenoble, France
| | - Anne Le Goff
- Institute for Society and Genetics (ISG), University of Califonia Los Angeles, Los Angeles, CA, USA
- EpiCenter on Epigenetics, Reproduction, and Society, University of California Los Angeles, Los Angeles, CA, USA
| | - Catherine Guaspare
- Epigenetics, Data, Politics (EpiDaPo), CNRS, The George Washington University, Washington, DC, USA
- Groupe d'Étude des Méthodes de l'Analyse Sociologique de la Sorbonne (GEMASS), CNRS, Sorbonne University, Paris, France
| | - Patrick Allard
- Institute for Society and Genetics (ISG), University of Califonia Los Angeles, Los Angeles, CA, USA
- EpiCenter on Epigenetics, Reproduction, and Society, University of California Los Angeles, Los Angeles, CA, USA
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12
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Terrer E, Slimani A, Giraudeau N, Levallois B, Tramini P, Bonte E, Hua C, Lucchini M, Seux D, Thivichon B, Le Goff A, Cuisinier F, Tassery H. Performance of Fluorescence-based Systems in Early Caries Detection: A Public Health Issue. J Contemp Dent Pract 2019; 20:1126-1131. [PMID: 31883244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
AIM Modern clinical caries management involves early stage caries diagnosis and should fit with dental health policy. The objective of this study was to achieve early caries detection in enamel and dentine with a laser-based system (DIAGNOdent™ pen) first and secondary with a new fluorescence intra-oral camera (Soprolife®). A visual inspection with a loupe was used as control. MATERIALS AND METHODS Following the consolidated standards of reporting trials recommendations, 628 occlusal fissures were included for analysis. RESULTS The sensitivity and specificity of both devices varied depending on the cutoff threshold of the caries score, and the ROC curve showed higher values for the Soprolife® than for DIAGNOdent™ pen. The values of the area under the curve decreased from 0.81 (Soprolife® in daylight) to 0.79 (Soprolife® in fluorescent mode) and 0.67 for DIAGNOdent™ pen. DIAGNOdent™ pen reproducibility (intra and inter-investigator) showed a wide dispersion, with many values scattered beyond the confidence limits (±2 SD), and the weighted kappa coefficient, which was quite low (0.58), confirmed this tendency. CONCLUSION Caries prevalence in terms of public health policy is of interest and caries detection increased significantly when using an fluorescence-based intra-oral camera. CLINICAL SIGNIFICANCE The clinical significance of these findings is that fluorescence could help improve caries diagnosis, reduce clinical misinterpretations, and finally benefit the patients. How to cite this article: Terrer E, Slimani A, Giraudeau N, et al. Performance of Fluorescence-based Systems in Early Caries Detection: A Public Health Issue. J Contemp Dent Pract 2019;20(10):1126-1132.
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Affiliation(s)
- Elodie Terrer
- Restorative Department Marseille, Aix-Marseille-University, France; Bioengineering and Nanosciences, EA 4203, UFR Odontology, Montpellier University, France, e-mail:
| | - Amel Slimani
- Restorative Department Montpellier, Bioengineering and Nanosciences, EA 4203, UFR Odontology, Montpellier University, France
| | - Nicolas Giraudeau
- Restorative Department Montpellier, Bioengineering and Nanosciences, EA 4203, UFR Odontology, Montpellier University, France
| | - Bernard Levallois
- Restorative Department Montpellier, Bioengineering and Nanosciences, EA 4203, UFR Odontology, Montpellier University, France
| | - Paul Tramini
- Restorative Department Montpellier, Bioengineering and Nanosciences, EA 4203, UFR Odontology, Montpellier University, France
| | - Eric Bonte
- Restorative Department Montpellier, Bretonneau Hospital AP-HP, Paris, France
| | - Chau Hua
- Restorative Department Montpellier, Bretonneau Hospital AP-HP, Paris, France
| | - Marion Lucchini
- Restorative Department Montpellier, UFR Odontology, Lyon, France
| | - Dominique Seux
- Restorative Department Montpellier, UFR Odontology, Lyon, France
| | | | - Anne Le Goff
- Restorative Department Montpellier, UFR Odontology, Rennes, France
| | - Frédéric Cuisinier
- Restorative Department Montpellier, Bioengineering and Nanosciences, EA 4203, UFR Odontology, Montpellier University, France
| | - Hervé Tassery
- Restorative Department Marseille, Aix-Marseille-University, France; Bioengineering and Nanosciences, EA 4203, UFR Odontology, Montpellier University, France
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Pujos JS, Reyssat M, Le Goff A. Experimental and numerical study of platelets rolling on a von Willebrand factor-coated surface. Med Eng Phys 2018; 55:25-33. [PMID: 29599066 DOI: 10.1016/j.medengphy.2018.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 02/26/2018] [Accepted: 03/13/2018] [Indexed: 11/26/2022]
Abstract
Blood platelets circulate in the blood and adhere to wounded vessels to initiate coagulation and healing. The first step of this process is the capture of flowing platelets by adhesive molecules located at the wounded vessel wall. In this article, we study the transport of fixed blood platelets in a microfluidic channel coated with von Willebrand factor (vWF), a large multimeric protein expressed by endothelial cells in the vicinity of wounds. We measure the number of platelets adsorbed at the channel surface as a function of both time and space. Experimental results are compared with a new transport model. We show that transverse diffusion is an important feature of our model, while the rolling behaviour of the bounded platelets can be neglected.
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Affiliation(s)
- Justine S Pujos
- ESPCI Paris, PSL Research University, CNRS UMR 7083 Gulliver, 10 rue Vauquelin, 75231 Paris Cedex 05, France
| | - Mathilde Reyssat
- ESPCI Paris, PSL Research University, CNRS UMR 7083 Gulliver, 10 rue Vauquelin, 75231 Paris Cedex 05, France
| | - Anne Le Goff
- ESPCI Paris, PSL Research University, CNRS UMR 7083 Gulliver, 10 rue Vauquelin, 75231 Paris Cedex 05, France; Sorbonne Universités, Université de Technologie de Compiègne, CNRS UMR 7338 Biomécanique et Bioingénierie, Centre de recherche Royallieu, CS 60 319, Compiègne cedex 60 203, France.
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14
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Le Goff A, Kaoui B, Kurzawa G, Haszon B, Salsac AV. Squeezing bio-capsules into a constriction: deformation till break-up. Soft Matter 2017; 13:7644-7648. [PMID: 28990040 DOI: 10.1039/c7sm01417a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We study experimentally the deformation and break-up of liquid-filled capsules trapped at an axisymmetric step constriction, and subjected to increasing pressure drops. We considered biological (trout fish eggs) and bioartificial (made of ovalbumin and alginate) ones, with the objective to characterize the transition to break-up. We find that both capsule populations behave as a brittle material. They do not exhibit any plastic deformation prior to break-up. Moreover critical pressure drop exhibits a stochastic behavior as known for the fracture of disordered media. The break-up probability follows a three-parameter Weibull distribution, from which one can deduce the capsule rupture characteristics.
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Affiliation(s)
- Anne Le Goff
- Biomechanics and Bioengineering Laboratory (UMR 7338) CNRS, Sorbonne Universités, Université de Technologie de Compiègne, 60200 Compiègne, France.
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15
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Abstract
We study the motion of a solid sphere after its fast impact on a bath of liquid foam. We identify two regimes of deceleration. At short times, the velocity is still large and the foam behaves similar to a Newtonian fluid of constant viscosity. Then we measure a velocity threshold below which the sphere starts experiencing the foam's elasticity. We interpret this behavior using a visco-elasto-plastic model for foam rheology. Finally we discuss the possibility of stopping a projectile in the foam, and evaluate the capture efficiency.
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Affiliation(s)
- Anne Le Goff
- PMMH, UMRS 7636 du CNRS, ESPCI, 75005 Paris, France
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16
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Le Goff A, Cobelli P, Lagubeau G. Supershear Rayleigh waves at a soft interface. Phys Rev Lett 2013; 110:236101. [PMID: 25167515 DOI: 10.1103/physrevlett.110.236101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 02/22/2013] [Indexed: 05/10/2023]
Abstract
We report on the experimental observation of waves at a liquid foam surface propagating faster than the bulk shear waves. The existence of such waves has long been debated, but the recent observation of supershear events in a geophysical context has inspired us to search for their existence in a model viscoelastic system. An optimized fast profilometry technique allows us to observe on a liquid foam surface the waves triggered by the impact of a projectile. At high impact velocity, we show that the expected subshear Rayleigh waves are accompanied by faster surface waves that can be identified as supershear Rayleigh waves.
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Affiliation(s)
- Anne Le Goff
- Microfluidique, MEMs et Nanostructures, UMR Gulliver 7083, ESPCI, 75005 Paris, France
| | - Pablo Cobelli
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, 1428 Buenos Aires, Argentina and Physique et Mécanique des Milieux Hétérogènes PMMH, UMR CNRS 7636, ESPCI, UMPC Université Paris 6, UPD Université Paris 7, Paris, France
| | - Guillaume Lagubeau
- Physique et Mécanique des Milieux Hétérogènes PMMH, UMR CNRS 7636, ESPCI, UMPC Université Paris 6, UPD Université Paris 7, Paris, France and Departamento de Física, Universidad de Santiago de Chile, Santiago, Chile
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17
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Nozaki C, Vergnano AM, Filliol D, Ouagazzal AM, Le Goff A, Carvalho S, Reiss D, Gaveriaux-Ruff C, Neyton J, Paoletti P, Kieffer BL. Zinc alleviates pain through high-affinity binding to the NMDA receptor NR2A subunit. Nat Neurosci 2011; 14:1017-22. [PMID: 21725314 DOI: 10.1038/nn.2844] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 04/19/2011] [Indexed: 02/07/2023]
Abstract
Zinc is abundant in the central nervous system and regulates pain, but the underlying mechanisms are unknown. In vitro studies have shown that extracellular zinc modulates a plethora of signaling membrane proteins, including NMDA receptors containing the NR2A subunit, which display exquisite zinc sensitivity. We created NR2A-H128S knock-in mice to investigate whether Zn2+-NR2A interaction influences pain control. In these mice, high-affinity (nanomolar) zinc inhibition of NMDA currents was lost in the hippocampus and spinal cord. Knock-in mice showed hypersensitivity to radiant heat and capsaicin, and developed enhanced allodynia in inflammatory and neuropathic pain models. Furthermore, zinc-induced analgesia was completely abolished under both acute and chronic pain conditions. Our data establish that zinc is an endogenous modulator of excitatory neurotransmission in vivo and identify a new mechanism in pain processing that relies on NR2A NMDA receptors. The study also potentially provides a molecular basis for the pain-relieving effects of dietary zinc supplementation.
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Affiliation(s)
- Chihiro Nozaki
- Institut de Génétique et Biologie Moléculaire et Cellulaire, Illkirch, France
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18
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Mony L, Krzaczkowski L, Leonetti M, Le Goff A, Alarcon K, Neyton J, Bertrand HO, Acher F, Paoletti P. Structural basis of NR2B-selective antagonist recognition by N-methyl-D-aspartate receptors. Mol Pharmacol 2008; 75:60-74. [PMID: 18923063 DOI: 10.1124/mol.108.050971] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
N-Methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate receptors endowed with unique pharmacological and functional properties. In particular, their high permeability to calcium ions confers on NMDARs a central role in triggering long term changes in synaptic strength. Under excitotoxic pathological conditions, such as those occurring during brain trauma, stroke, or Parkinson's or Huntington's diseases, calcium influx through NMDAR channels can also lead to neuronal injury. This argues for the use of NMDAR antagonists as potential therapeutic agents. To date, the most promising NMDAR antagonists are ifenprodil and derivatives, compounds that act as noncompetitive inhibitors selective for NMDARs containing the NR2B subunit. Recent studies have identified the large N-terminal domain (NTD) of NR2B as the region controlling ifenprodil sensitivity of NMDARs. We present here a detailed characterization of the ifenprodil binding site using both experimental and computational approaches. 3D homology modeling reveals that ifenprodil fits well in a closed cleft conformation of the NRB NTD; however, ifenprodil can adopt either of two possible binding orientations of opposite direction. By studying the effects of cleft mutations, we show that only the orientation in which the phenyl moiety points deep toward the NTD hinge is functionally relevant. Moreover, based on our model, we identify novel NTD NR2B residues that are crucial for conferring ifenprodil sensitivity and provide functional evidence that these residues directly interact with the ifenprodil molecule. This work provides a general insight into the origin of the subunit-selectivity of NMDAR noncompetitive antagonists and offer clues for the discovery of novel NR2B-selective antagonists.
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Affiliation(s)
- Laetitia Mony
- Laboratoire de Neurobiologie, Centre National de Recherche Scientifique (CNRS) Unité Mixte de Recherche 8544, Ecole Normale Supérieure, Paris, France
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19
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Gielen M, Le Goff A, Stroebel D, Johnson JW, Neyton J, Paoletti P. Structural rearrangements of NR1/NR2A NMDA receptors during allosteric inhibition. Neuron 2008; 57:80-93. [PMID: 18184566 DOI: 10.1016/j.neuron.2007.11.021] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 09/21/2007] [Accepted: 11/07/2007] [Indexed: 10/22/2022]
Abstract
Ionotropic glutamate receptor (iGluR) subunits contain a large N-terminal domain (NTD) that precedes the agonist-binding domain (ABD) and participates in subunit oligomerization. In NMDA receptors (NMDARs), the NTDs of NR2A and NR2B subunits also form binding sites for the endogenous inhibitor Zn(2+) ion. Although these allosteric sites have been characterized in detail, the molecular mechanisms by which the NTDs communicate with the rest of the receptor to promote its inhibition remain unknown. Here, we identify the ABD dimer interface as a major structural determinant that permits coupling between the NTDs and the channel gate. The strength of this interface also controls proton inhibition, another form of allosteric modulation of NMDARs. Conformational rearrangements at the ABD dimer interface thus appear to be a key mechanism conserved in all iGluR subfamilies, but have evolved to fulfill different functions: fast desensitization at AMPA and kainate receptors, allosteric inhibition at NMDARs.
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Affiliation(s)
- Marc Gielen
- Laboratoire de Neurobiologie, Ecole Normale Supérieure, CNRS, 46 rue d'Ulm, 75005 Paris, France
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20
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Aubrey KR, Rossi FM, Ruivo R, Alboni S, Bellenchi GC, Le Goff A, Gasnier B, Supplisson S. The transporters GlyT2 and VIAAT cooperate to determine the vesicular glycinergic phenotype. J Neurosci 2007; 27:6273-81. [PMID: 17554001 PMCID: PMC6672136 DOI: 10.1523/jneurosci.1024-07.2007] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The mechanisms that specify the vesicular phenotype of inhibitory interneurons in vertebrates are poorly understood because the two main inhibitory transmitters, glycine and GABA, share the same vesicular inhibitory amino acid transporter (VIAAT) and are both present in neurons during postnatal development. We have expressed VIAAT and the plasmalemmal transporters for glycine and GABA in a neuroendocrine cell line and measured the quantal release of glycine and GABA using a novel double-sniffer patch-clamp technique. We found that glycine is released from vesicles when VIAAT is coexpressed with either the neuronal transporter GlyT2 or the glial transporter GlyT1. However, GlyT2 was more effective than GlyT1, probably because GlyT2 is unable to operate in the reverse mode, which gives it an advantage in maintaining the high cytosolic glycine concentration required for efficient vesicular loading by VIAAT. The vesicular inhibitory phenotype was gradually altered from glycinergic to GABAergic through mixed events when GABA is introduced into the secretory cell and competes for uptake by VIAAT. Interestingly, the VIAAT ortholog from Caenorhabditis elegans (UNC-47), a species lacking glycine transmission, also supports glycine exocytosis in the presence of GlyT2, and a point mutation of UNC-47 that abolishes GABA transmission in the worm confers glycine specificity. Together, these results suggest that an increased cytosolic availability of glycine in VIAAT-containing terminals was crucial for the emergence of glycinergic transmission in vertebrates.
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Affiliation(s)
- Karin R Aubrey
- Laboratoire de Neurobiologie, Centre National de la Recherche Scientifique, Ecole Normale Supérieure, 75005 Paris, France
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21
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Abstract
Eukaryotic ionotropic glutamate receptor subunits possess a large N-terminal domain (NTD) distinct from the neighboring agonist-binding domain. In NMDA receptors, the NTDs of NR2A and NR2B form modulatory domains binding allosteric inhibitors. Despite a high sequence homology, these two domains have been shown to bind two ligands of strikingly different chemical nature. Whereas the NTD of NR2A binds zinc with high (nanomolar) affinity, the NTD of NR2B binds the synthetic neuroprotectant ifenprodil and its derivatives. Using both NTD-mutated/deleted receptors and isolated NTDs, we now show that the NTD of NR2B, in contrast to NR2C and NR2D, also binds zinc, but with a lower affinity. Furthermore, we present evidence that zinc and ifenprodil compete for an overlapping binding site. This modulatory binding site accounts for the submicromolar zinc inhibition of NR1/NR2B receptors. Given that zinc is accumulated and released at many glutamatergic synapses in the CNS, these findings suggest that zinc is the endogenous ligand of the NTD of both NR2A and NR2B, the two major NR2 subunits. Thus, NMDA receptors contain zinc sensors capable of detecting extracellular zinc over a wide concentration range depending on their NR2 subunit composition. The coexistence of subunit-specific zinc-binding sites of high (nanomolar) and low (micromolar) affinity on NMDA receptors raises the possibility that zinc exerts both a tonic and a phasic control of membrane excitability.
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Affiliation(s)
- Julie Rachline
- Laboratoire de Neurobiologie, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8544, Ecole Normale Supérieure, 75005 Paris, France
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22
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Roux MJ, Martinez-Maza R, Le Goff A, Lopez-Corcuera B, Aragon C, Supplisson S. The glial and the neuronal glycine transporters differ in their reactivity to sulfhydryl reagents. J Biol Chem 2001; 276:17699-705. [PMID: 11278474 PMCID: PMC2375918 DOI: 10.1074/jbc.m009196200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The neuronal (GlyT2) and glial (GlyT1) glycine transporters, two members of the Na(+)/Cl(-)-dependent neurotransmitter transporter superfamily, differ by many aspects, such as substrate specificity and Na(+) coupling. We have characterized under voltage clamp their reactivity toward the membrane impermeant sulfhydryl reagent [2-(trimethylammonium)-ethyl]-methanethiosulfonate (MTSET). In Xenopus oocytes expressing GlyT1b, application of MTSET reduced to the same extent the Na(+)-dependent charge movement, the glycine-evoked current, and the glycine uptake, indicating a complete inactivation of the transporters following cysteine modification. In contrast, this compound had no detectable effect on the glycine uptake and the glycine-evoked current of GlyT2a. The sensitivities to MTSET of the two transporters can be permutated by suppressing a cysteine (C62A) in the first extracellular loop (EL1) of GlyT1b and introducing one at the equivalent position in GlyT2a, either by point mutation (A223C) or by swapping the EL1 sequence (GlyT1b-EL1 and GlyT2a-EL1) resulting in AFQ <--> CYR modification. Inactivation by MTSET was five times faster in GlyT2a-A223C than in GlyT2a-EL1 or GlyT1b, suggesting that the arginine in position +2 reduced the cysteine reactivity. Protection assays indicate that EL1 cysteines are less accessible in the presence of all co-transported substrates: Na(+), Cl(-), and glycine. Application of dithioerythritol reverses the inactivation by MTSET of the sensitive transporters. Together, these results indicate that EL1 conformation differs between GlyT1b and GlyT2a and is modified by substrate binding and translocation.
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Affiliation(s)
- Michel J. Roux
- NEURO, Laboratoire de Neurobiologie
CNRS : UMR8544Ecole Normale Supérieure de Paris46 Rue d'Ulm
75230 PARIS CEDEX 05,FR
| | - Rodrigo Martinez-Maza
- Centro de Biología Molecular "Severo Ochoa"
Consejo Superior de Investigaciones CientificasUniversidad Autónoma de Madrid28049 Madrid,ES
| | - Anne Le Goff
- NEURO, Laboratoire de Neurobiologie
CNRS : UMR8544Ecole Normale Supérieure de Paris46 Rue d'Ulm
75230 PARIS CEDEX 05,FR
| | - Beatriz Lopez-Corcuera
- Centro de Biología Molecular "Severo Ochoa"
Consejo Superior de Investigaciones CientificasUniversidad Autónoma de Madrid28049 Madrid,ES
| | - Carmen Aragon
- Centro de Biología Molecular "Severo Ochoa"
Consejo Superior de Investigaciones CientificasUniversidad Autónoma de Madrid28049 Madrid,ES
| | - Stéphane Supplisson
- NEURO, Laboratoire de Neurobiologie
CNRS : UMR8544Ecole Normale Supérieure de Paris46 Rue d'Ulm
75230 PARIS CEDEX 05,FR
- * Correspondence should be adressed to: Stéphane Supplisson
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