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He Z, Liu D, Li H, Gao W, Li X, Ma H, Shi W. Amphiphilic Rhodamine Fluorescent Probes Combined with Basal Imaging for Fine Structures of the Cell Membrane. Anal Chem 2024; 96:7257-7264. [PMID: 38664861 DOI: 10.1021/acs.analchem.4c00946] [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: 05/08/2024]
Abstract
Confocal fluorescence imaging of fine structures of the cell membrane is important for understanding their biofunctions but is often neglected due to the lack of an effective method. Herein, we develop new amphiphilic rhodamine fluorescent probe RMGs in combination with basal imaging for this purpose. The probes show high signal-to-noise ratio and brightness and low internalization rate, making them suitable for imaging the fine substructures of the cell membrane. Using the representative probe RMG3, we not only observed the cell pseudopodia and intercellular nanotubes but also monitored the formation of migrasomes in real time. More importantly, in-depth imaging studies on more cell lines revealed for the first time that hepatocellular carcinoma cells secreted much more adherent extracellular vesicles than other cell lines, which might serve as a potential indicator of liver cells. We believe that RMGs may be useful for investigating the fine structures of the cell membrane.
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Affiliation(s)
- Zixu He
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Diankai Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - He Li
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Wenjie Gao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaohua Li
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Huimin Ma
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen Shi
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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2
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Iyer RS, Needham SR, Galdadas I, Davis BM, Roberts SK, Man RCH, Zanetti-Domingues LC, Clarke DT, Fruhwirth GO, Parker PJ, Rolfe DJ, Gervasio FL, Martin-Fernandez ML. Drug-resistant EGFR mutations promote lung cancer by stabilizing interfaces in ligand-free kinase-active EGFR oligomers. Nat Commun 2024; 15:2130. [PMID: 38503739 PMCID: PMC10951324 DOI: 10.1038/s41467-024-46284-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 02/20/2024] [Indexed: 03/21/2024] Open
Abstract
The Epidermal Growth Factor Receptor (EGFR) is frequently found to be mutated in non-small cell lung cancer. Oncogenic EGFR has been successfully targeted by tyrosine kinase inhibitors, but acquired drug resistance eventually overcomes the efficacy of these treatments. Attempts to surmount this therapeutic challenge are hindered by a poor understanding of how and why cancer mutations specifically amplify ligand-independent EGFR auto-phosphorylation signals to enhance cell survival and how this amplification is related to ligand-dependent cell proliferation. Here we show that drug-resistant EGFR mutations manipulate the assembly of ligand-free, kinase-active oligomers to promote and stabilize the assembly of oligomer-obligate active dimer sub-units and circumvent the need for ligand binding. We reveal the structure and assembly mechanisms of these ligand-free, kinase-active oligomers, uncovering oncogenic functions for hitherto orphan transmembrane and kinase interfaces, and for the ectodomain tethered conformation of EGFR. Importantly, we find that the active dimer sub-units within ligand-free oligomers are the high affinity binding sites competent to bind physiological ligand concentrations and thus drive tumor growth, revealing a link with tumor proliferation. Our findings provide a framework for future drug discovery directed at tackling oncogenic EGFR mutations by disabling oligomer-assembling interactions.
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Affiliation(s)
- R Sumanth Iyer
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
- Immunocore Limited, 92 Park Drive, Milton Park, Abingdon, UK
| | - Sarah R Needham
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Ioannis Galdadas
- School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland
- ISPSO, University of Geneva, Geneva, Switzerland
| | - Benjamin M Davis
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Selene K Roberts
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Rico C H Man
- Imaging Therapies and Cancer Group, Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, London, UK
| | | | - David T Clarke
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Gilbert O Fruhwirth
- Imaging Therapies and Cancer Group, Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, London, UK
| | - Peter J Parker
- Protein Phosphorylation Laboratory, The Francis Crick Institute, London, UK
- School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, London, UK
| | - Daniel J Rolfe
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK.
| | - Francesco L Gervasio
- School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland.
- ISPSO, University of Geneva, Geneva, Switzerland.
- Chemistry Department, University College London, London, UK.
- Swiss Institute of Bioinformatics, University of Geneva, Geneva, Switzerland.
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3
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Martin‐Fernandez ML. A perspective of fluorescence microscopy for cellular structural biology with EGFR as witness. J Microsc 2023; 291:73-91. [PMID: 36282005 PMCID: PMC10952613 DOI: 10.1111/jmi.13151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 09/20/2022] [Accepted: 10/11/2022] [Indexed: 10/31/2022]
Abstract
The epidermal growth factor receptor (EGFR) is a poster child for the understanding of receptor behaviour, and of paramount importance to cell function and human health. Cloned almost forty years ago, the interest in EGFR's structure/function relationships remains unabated, not least because changes in oncogenic EGFR mutants are key drivers of the formation of lung and brain tumours. The structure of the assemblies formed by EGFR have been comprehensibly investigated by techniques such as high-resolution X-ray crystallography, NMR and all-atom molecular dynamics (MD) simulations. However, the complexity embedded in the portfolio of EGFR states that are only possible in the physiological environment of cells has often proved refractory to cell-free structural methods. Conversely, some key inroads made by quantitative fluorescence microscopy and super-resolution have depended on exploiting the wealth of structures available. Here, a brief personal perspective is provided on how quantitative fluorescence microscopy and super-resolution methods have cross-fertilised with cell-free-derived EGFR structural information. I primarily discuss areas in which my research group has made a contribution to fill gaps in EGFR's cellular structural biology and towards developing new tools to investigate macromolecular assemblies in cells.
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Affiliation(s)
- M. L. Martin‐Fernandez
- Central Laser FacilityScience and Technology Facilities Council, Rutherford Appleton LaboratoryDidcotUK
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4
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Martin-Fernandez ML. Fluorescence Imaging of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Resistance in Non-Small Cell Lung Cancer. Cancers (Basel) 2022; 14:cancers14030686. [PMID: 35158954 PMCID: PMC8833717 DOI: 10.3390/cancers14030686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/21/2022] [Accepted: 01/26/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Lung cancer is the leading cause of cancer-related deaths, with a low (<21%) 5-year survival rate. Lung cancer is often driven by the misfunction of molecules on the surface of cells of the epithelium, which orchestrate mechanisms by which these cells grow and proliferate. Beyond common non-specific treatments, such as chemotherapy or radiotherapy, among molecular-specific treatments, a number of small-molecule drugs that block cancer-driven molecular activity have been developed. These drugs initially have significant success in a subset of patients, but these patients systematically develop resistance within approximately one year of therapy. Substantial efforts towards understanding the mechanisms of resistance have focused on the genomics of cancer progression, the response of cells to the drugs, and the cellular changes that allow resistance to develop. Fluorescence microscopy of many flavours has significantly contributed to the last two areas, and is the subject of this review. Abstract Non-small cell lung cancer (NSCLC) is a complex disease often driven by activating mutations or amplification of the epidermal growth factor receptor (EGFR) gene, which expresses a transmembrane receptor tyrosine kinase. Targeted anti-EGFR treatments include small-molecule tyrosine kinase inhibitors (TKIs), among which gefitinib and erlotinib are the best studied, and their function more often imaged. TKIs block EGFR activation, inducing apoptosis in cancer cells addicted to EGFR signals. It is not understood why TKIs do not work in tumours driven by EGFR overexpression but do so in tumours bearing classical activating EGFR mutations, although the latter develop resistance in about one year. Fluorescence imaging played a crucial part in research efforts to understand pro-survival mechanisms, including the dysregulation of autophagy and endocytosis, by which cells overcome the intendedly lethal TKI-induced EGFR signalling block. At their core, pro-survival mechanisms are facilitated by TKI-induced changes in the function and conformation of EGFR and its interactors. This review brings together some of the main advances from fluorescence imaging in investigating TKI function and places them in the broader context of the TKI resistance field, highlighting some paradoxes and suggesting some areas where super-resolution and other emerging methods could make a further contribution.
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Affiliation(s)
- Marisa L Martin-Fernandez
- Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0FA, UK
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5
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Kim DH, Triet HM, Ryu SH. Regulation of EGFR activation and signaling by lipids on the plasma membrane. Prog Lipid Res 2021; 83:101115. [PMID: 34242725 DOI: 10.1016/j.plipres.2021.101115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/02/2021] [Accepted: 07/01/2021] [Indexed: 12/12/2022]
Abstract
Lipids on the plasma membrane are not only components of the membrane biophysical structures but also regulators of receptor functions. Recently, the critical roles of lipid-protein interactions have been intensively highlighted. Epidermal growth factor receptor (EGFR) is one of the most extensively studied receptors exhibiting various lipid interactions, including interactions with phosphatidylcholine, phosphatidylserine, phosphatidylinositol phosphate, cholesterol, gangliosides, and palmitate. Here, we review recent findings on how direct interaction with these lipids regulates EGFR activation and signaling, providing unprecedented insight into the comprehensive roles of various lipids in the control of EGFR functions. Finally, the current limitations in investigating lipid-protein interactions and novel technologies to potentially overcome these limitations are discussed.
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Affiliation(s)
- Do-Hyeon Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Hong Minh Triet
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Sung Ho Ryu
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
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6
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Pascarelli S, Merzhakupova D, Uechi GI, Laurino P. Binding of single-mutant epidermal growth factor (EGF) ligands alters the stability of the EGF receptor dimer and promotes growth signaling. J Biol Chem 2021; 297:100872. [PMID: 34126069 PMCID: PMC8259408 DOI: 10.1016/j.jbc.2021.100872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/03/2021] [Accepted: 06/10/2021] [Indexed: 11/30/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) is a membrane-anchored tyrosine kinase that is able to selectively respond to multiple extracellular stimuli. Previous studies have indicated that the modularity of this system may be caused by ligand-induced differences in the stability of the receptor dimer. However, this hypothesis has not been explored using single-mutant ligands thus far. Herein, we developed a new approach to identify residues responsible for functional divergence by selecting residues in the epidermal growth factor (EGF) ligand that are conserved among orthologs yet divergent between paralogs. Then, we mutated these residues and assessed the mutants' effects on the receptor using a combination of molecular dynamics (MD) and biochemical techniques. Although the EGF mutants had binding affinities for the EGFR comparable with the WT ligand, the EGF mutants showed differential patterns of receptor phosphorylation and cell growth in multiple cell lines. The MD simulations of the EGF mutants indicated that mutations had long-range effects on the receptor dimer interface. This study shows for the first time that a single mutation in the EGF is sufficient to alter the activation of the EGFR signaling pathway at the cellular level. These results also support that biased ligand-receptor signaling in the tyrosine kinase receptor system can lead to differential downstream outcomes and demonstrate a promising new method to study ligand-receptor interactions.
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Affiliation(s)
- Stefano Pascarelli
- Protein Engineering and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Dalmira Merzhakupova
- Protein Engineering and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Gen-Ichiro Uechi
- Protein Engineering and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Paola Laurino
- Protein Engineering and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan.
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7
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Martin-Fernandez ML. A brief history of the octopus imaging facility to celebrate its 10th anniversary. J Microsc 2020; 281:3-15. [PMID: 33111321 DOI: 10.1111/jmi.12974] [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: 08/06/2020] [Revised: 10/19/2020] [Accepted: 10/23/2020] [Indexed: 11/27/2022]
Abstract
Octopus (Optics Clustered to OutPut Unique Solutions) celebrated in June 2020 its 10th birthday. Based at Harwell, near Oxford, Octopus is an open access, peer reviewed, national imaging facility that offers successful U.K. applicants supported access to single molecule imaging, confocal microscopy, several flavours of superresolution imaging, light sheet microscopy, optical trapping and cryoscanning electron microscopy. Managed by a multidisciplinary team, Octopus has so far assisted >100 groups of U.K. and international researchers. Cross-fertilisation across fields proved to be a strong propeller of success underpinned by combining access to top-end instrumentation with a strong programme of imaging hardware and software developments. How Octopus was born, and highlights of the multidisciplinary output produced during its 10-year journey are reviewed below, with the aim of celebrating a myriad of collaborations with the U.K. scientific community, and reflecting on their scientific and societal impact.
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Affiliation(s)
- M L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, U.K
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8
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Gocheva G, Ivanova A. A Look at Receptor–Ligand Pairs for Active-Targeting Drug Delivery from Crystallographic and Molecular Dynamics Perspectives. Mol Pharm 2019; 16:3293-3321. [DOI: 10.1021/acs.molpharmaceut.9b00250] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Gergana Gocheva
- Sofia University “St. Kliment Ohridski”, Faculty of Chemistry and Pharmacy, 1 James Bourchier Blvd., 1164 Sofia, Bulgaria
| | - Anela Ivanova
- Sofia University “St. Kliment Ohridski”, Faculty of Chemistry and Pharmacy, 1 James Bourchier Blvd., 1164 Sofia, Bulgaria
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9
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Zanetti-Domingues LC, Korovesis D, Needham SR, Tynan CJ, Sagawa S, Roberts SK, Kuzmanic A, Ortiz-Zapater E, Jain P, Roovers RC, Lajevardipour A, van Bergen En Henegouwen PMP, Santis G, Clayton AHA, Clarke DT, Gervasio FL, Shan Y, Shaw DE, Rolfe DJ, Parker PJ, Martin-Fernandez ML. The architecture of EGFR's basal complexes reveals autoinhibition mechanisms in dimers and oligomers. Nat Commun 2018; 9:4325. [PMID: 30337523 PMCID: PMC6193980 DOI: 10.1038/s41467-018-06632-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 09/11/2018] [Indexed: 11/09/2022] Open
Abstract
Our current understanding of epidermal growth factor receptor (EGFR) autoinhibition is based on X-ray structural data of monomer and dimer receptor fragments and does not explain how mutations achieve ligand-independent phosphorylation. Using a repertoire of imaging technologies and simulations we reveal an extracellular head-to-head interaction through which ligand-free receptor polymer chains of various lengths assemble. The architecture of the head-to-head interaction prevents kinase-mediated dimerisation. The latter, afforded by mutation or intracellular treatments, splits the autoinhibited head-to-head polymers to form stalk-to-stalk flexible non-extended dimers structurally coupled across the plasma membrane to active asymmetric tyrosine kinase dimers, and extended dimers coupled to inactive symmetric kinase dimers. Contrary to the previously proposed main autoinhibitory function of the inactive symmetric kinase dimer, our data suggest that only dysregulated species bear populations of symmetric and asymmetric kinase dimers that coexist in equilibrium at the plasma membrane under the modulation of the C-terminal domain.
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Affiliation(s)
- Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Dimitrios Korovesis
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | | | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Antonija Kuzmanic
- Department of Chemistry, Faculty of Maths & Physical Sciences, University College London, London, WC1H 0AJ, UK
| | - Elena Ortiz-Zapater
- Peter Gore Department of Immunobiology, School of Immunology & Microbial Sciences, Kings College London, London, SE1 9RT, UK
| | - Purvi Jain
- Division of Cell Biology, Science Faculty, Department of Biology, Utrecht University, Utrecht, 3584 CH, The Netherlands
| | - Rob C Roovers
- Merus, LSI, Yalelaan 62, 3584 CM, Utrecht, The Netherlands
| | - Alireza Lajevardipour
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia
| | | | - George Santis
- Peter Gore Department of Immunobiology, School of Immunology & Microbial Sciences, Kings College London, London, SE1 9RT, UK
| | - Andrew H A Clayton
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Francesco L Gervasio
- Department of Chemistry, Faculty of Maths & Physical Sciences, University College London, London, WC1H 0AJ, UK
| | - Yibing Shan
- D. E. Shaw Research, New York, NY, 10036, USA
| | - David E Shaw
- D. E. Shaw Research, New York, NY, 10036, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Peter J Parker
- Protein Phosphorylation Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW 1 1AT, UK
- School of Cancer and Pharmaceutical Sciences, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK.
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10
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Needham SR, Roberts SK, Arkhipov A, Mysore VP, Tynan CJ, Zanetti-Domingues LC, Kim ET, Losasso V, Korovesis D, Hirsch M, Rolfe DJ, Clarke DT, Winn MD, Lajevardipour A, Clayton AHA, Pike LJ, Perani M, Parker PJ, Shan Y, Shaw DE, Martin-Fernandez ML. EGFR oligomerization organizes kinase-active dimers into competent signalling platforms. Nat Commun 2016; 7:13307. [PMID: 27796308 PMCID: PMC5095584 DOI: 10.1038/ncomms13307] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 09/20/2016] [Indexed: 12/19/2022] Open
Abstract
Epidermal growth factor receptor (EGFR) signalling is activated by ligand-induced receptor dimerization. Notably, ligand binding also induces EGFR oligomerization, but the structures and functions of the oligomers are poorly understood. Here, we use fluorophore localization imaging with photobleaching to probe the structure of EGFR oligomers. We find that at physiological epidermal growth factor (EGF) concentrations, EGFR assembles into oligomers, as indicated by pairwise distances of receptor-bound fluorophore-conjugated EGF ligands. The pairwise ligand distances correspond well with the predictions of our structural model of the oligomers constructed from molecular dynamics simulations. The model suggests that oligomerization is mediated extracellularly by unoccupied ligand-binding sites and that oligomerization organizes kinase-active dimers in ways optimal for auto-phosphorylation in trans between neighbouring dimers. We argue that ligand-induced oligomerization is essential to the regulation of EGFR signalling. Epidermal growth factor receptors have been shown to oligomerise upon binding to their cognate ligands. Here, the authors use biochemical, biophysical and cell biology techniques to analyse the structures of these oligomers, and argue that these formations are required for signalling.
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Affiliation(s)
- Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | | | | | - Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Eric T Kim
- D.E. Shaw Research, New York, New York 10036, USA
| | - Valeria Losasso
- Computational Science and Engineering Department, Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, UK
| | - Dimitrios Korovesis
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Martyn D Winn
- Computational Science and Engineering Department, Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, UK
| | - Alireza Lajevardipour
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Andrew H A Clayton
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Linda J Pike
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Michela Perani
- Division of Cancer Studies, King's College London, Guy's Medical School Campus, London SE1 1UL, UK
| | - Peter J Parker
- Division of Cancer Studies, King's College London, Guy's Medical School Campus, London SE1 1UL, UK.,The Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Yibing Shan
- D.E. Shaw Research, New York, New York 10036, USA
| | - David E Shaw
- D.E. Shaw Research, New York, New York 10036, USA.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
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11
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The Dipole Potential Modifies the Clustering and Ligand Binding Affinity of ErbB Proteins and Their Signaling Efficiency. Sci Rep 2016; 6:35850. [PMID: 27775011 PMCID: PMC5075772 DOI: 10.1038/srep35850] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 10/06/2016] [Indexed: 01/22/2023] Open
Abstract
Although activation of the ErbB family of receptor tyrosine kinases (ErbB1-4) is driven by oligomerization mediated by intermolecular interactions between the extracellular, the kinase and the transmembrane domains, the transmembrane domain has been largely neglected in this regard. The largest contributor to the intramembrane electric field, the dipole potential, alters the conformation of transmembrane peptides, but its effect on ErbB proteins is unknown. Here, we show by Förster resonance energy transfer (FRET) and number and brightness (N&B) experiments that the epidermal growth factor (EGF)-induced increase in the homoassociation of ErbB1 and ErbB2 and their heteroassociation are augmented by increasing the dipole potential. These effects were even more pronounced for ErbB2 harboring an activating Val → Glu mutation in the transmembrane domain (NeuT). The signaling capacity of ErbB1 and ErbB2 was also correlated with the dipole potential. Since the dipole potential decreased the affinity of EGF to ErbB1, the augmented growth factor-induced effects at an elevated dipole potential were actually induced at lower receptor occupancy. We conclude that the dipole potential plays a permissive role in the clustering of ErbB receptors and that the effects of lipid rafts on ligand binding and receptor signaling can be partially attributed to the dipole potential.
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12
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pH dependence of ligand-induced human epidermal growth factor receptor activation investigated by molecular dynamics simulations. J Mol Model 2016; 22:131. [DOI: 10.1007/s00894-016-3000-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 04/24/2016] [Indexed: 01/29/2023]
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13
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Determining the geometry of oligomers of the human epidermal growth factor family on cells with <10 nm resolution. Biochem Soc Trans 2016; 43:309-14. [PMID: 26009168 DOI: 10.1042/bst20140318] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There is a limited range of methods available to characterize macromolecular organization in cells on length scales from 5-50 nm. We review methods currently available and show the latest results from a new single-molecule localization-based method, fluorophore localization imaging with photobleaching (FLImP), using the epidermal growth factor (EGF) receptor (EGFR) as an example system. Our measurements show that FLImP is capable of achieving spatial resolution in the order of 6 nm.
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14
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Bocharov EV, Lesovoy DM, Pavlov KV, Pustovalova YE, Bocharova OV, Arseniev AS. Alternative packing of EGFR transmembrane domain suggests that protein-lipid interactions underlie signal conduction across membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1254-61. [PMID: 26903218 DOI: 10.1016/j.bbamem.2016.02.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 02/15/2016] [Accepted: 02/17/2016] [Indexed: 10/22/2022]
Abstract
The human epidermal growth factor receptor (EGFR) of HER/ErbB receptor tyrosine kinase family mediates a broad spectrum of cellular responses transducing biochemical signals via lateral dimerization in plasma membrane, while inactive receptors can exist in both monomeric and dimeric forms. Recently, the dimeric conformation of the helical single-span transmembrane domains of HER/ErbB employing the relatively polar N-terminal motifs in a fashion permitting proper kinase activation was experimentally determined. Here we describe the EGFR transmembrane domain dimerization via an alternative weakly polar C-terminal motif A(661)xxxG(665) presumably corresponding to the inactive receptor state. During association, the EGFR transmembrane helices undergo a structural adjustment with adaptation of inter-molecular polar and hydrophobic interactions depending upon the surrounding membrane properties that directly affect the transmembrane helix packing. This might imply that signal transduction through membrane and allosteric regulation are inclusively mediated by coupled protein-protein and protein-lipid interactions, elucidating paradoxically loose linkage between ligand binding and kinase activation.
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Affiliation(s)
- Eduard V Bocharov
- Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, str. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation.
| | - Dmitry M Lesovoy
- Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, str. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation
| | - Konstantin V Pavlov
- Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, str. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation
| | - Yulia E Pustovalova
- Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, str. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation
| | - Olga V Bocharova
- Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, str. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation
| | - Alexander S Arseniev
- Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, str. Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation
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15
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Tynan CJ, Lo Schiavo V, Zanetti-Domingues L, Needham SR, Roberts SK, Hirsch M, Rolfe DJ, Korovesis D, Clarke DT, Martin-Fernandez ML. A tale of the epidermal growth factor receptor: The quest for structural resolution on cells. Methods 2015; 95:86-93. [PMID: 26484734 DOI: 10.1016/j.ymeth.2015.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/14/2015] [Accepted: 10/15/2015] [Indexed: 01/03/2023] Open
Abstract
The challenge of determining the architecture and geometry of oligomers of the epidermal growth factor receptor (EGFR) on the cell surface has been approached using a variety of biochemical and biophysical methods. This review is intended to provide a narrative of how key concepts in the field of EGFR research have evolved over the years, from the origins of the prevalent EGFR signalling dimer hypothesis through to the development and implementation of methods that are now challenging the conventional view. The synergy between X-ray crystallography and cellular fluorescence microscopy has become particularly important, precisely because the results from these two methods diverged and highlighted the complexity of the challenge. We illustrate how developments in super-resolution microscopy are now bridging this gap. Exciting times lie ahead where knowledge of the nature of the complexes can assist with the development of a new generation of anti-cancer drugs.
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Affiliation(s)
- Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Valentina Lo Schiavo
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Laura Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Dimitrios Korovesis
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom.
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16
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Valley CC, Arndt-Jovin DJ, Karedla N, Steinkamp MP, Chizhik AI, Hlavacek WS, Wilson BS, Lidke KA, Lidke DS. Enhanced dimerization drives ligand-independent activity of mutant epidermal growth factor receptor in lung cancer. Mol Biol Cell 2015; 26:4087-99. [PMID: 26337388 PMCID: PMC4710239 DOI: 10.1091/mbc.e15-05-0269] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 08/27/2015] [Indexed: 12/12/2022] Open
Abstract
Epidermal growth factor receptor kinase mutations drive oncogenesis, but the molecular mechanism of pathological signal initiation is poorly understood. Using high-resolution microscopy methods, the authors reveal that these kinase mutations induce structural changes in the receptor ectodomain that lead to enhanced, ligand-independent dimerization. Mutations within the epidermal growth factor receptor (EGFR/erbB1/Her1) are often associated with tumorigenesis. In particular, a number of EGFR mutants that demonstrate ligand-independent signaling are common in non–small cell lung cancer (NSCLC), including kinase domain mutations L858R (also called L834R) and exon 19 deletions (e.g., ΔL747-P753insS), which collectively make up nearly 90% of mutations in NSCLC. The molecular mechanisms by which these mutations confer constitutive activity remain unresolved. Using multiple subdiffraction-limit imaging modalities, we reveal the altered receptor structure and interaction kinetics of NSCLC-associated EGFR mutants. We applied two-color single quantum dot tracking to quantify receptor dimerization kinetics on living cells and show that, in contrast to wild-type EGFR, mutants are capable of forming stable, ligand-independent dimers. Two-color superresolution localization microscopy confirmed ligand-independent aggregation of EGFR mutants. Live-cell Förster resonance energy transfer measurements revealed that the L858R kinase mutation alters ectodomain structure such that unliganded mutant EGFR adopts an extended, dimerization-competent conformation. Finally, mutation of the putative dimerization arm confirmed a critical role for ectodomain engagement in ligand-independent signaling. These data support a model in which dysregulated activity of NSCLC-associated kinase mutants is driven by coordinated interactions involving both the kinase and extracellular domains that lead to enhanced dimerization.
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Affiliation(s)
- Christopher C Valley
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131
| | - Donna J Arndt-Jovin
- Laboratory of Cellular Dynamics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Narain Karedla
- III. Institute of Physics, Georg-August University of Göttingen, 37077 Göttingen, Germany
| | - Mara P Steinkamp
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131
| | - Alexey I Chizhik
- III. Institute of Physics, Georg-August University of Göttingen, 37077 Göttingen, Germany
| | - William S Hlavacek
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545
| | - Bridget S Wilson
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131
| | - Keith A Lidke
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131
| | - Diane S Lidke
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131
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17
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Ramirez UD, Nikonova AS, Liu H, Pecherskaya A, Lawrence SH, Serebriiskii IG, Zhou Y, Robinson MK, Einarson MB, Golemis EA, Jaffe EK. Compounds identified by virtual docking to a tetrameric EGFR extracellular domain can modulate Grb2 internalization. BMC Cancer 2015; 15:436. [PMID: 26016476 PMCID: PMC4451962 DOI: 10.1186/s12885-015-1415-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 05/05/2015] [Indexed: 01/27/2023] Open
Abstract
Background Overexpression or mutation of the epidermal growth factor receptor (EGFR) potently enhances the growth of many solid tumors. Tumor cells frequently display resistance to mechanistically-distinct EGFR-directed therapeutic agents, making it valuable to develop therapeutics that work by additional mechanisms. Current EGFR-targeting therapeutics include antibodies targeting the extracellular domains, and small molecules inhibiting the intracellular kinase domain. Recent studies have identified a novel prone extracellular tetrameric EGFR configuration, which we identify as a potential target for drug discovery. Methods Our focus is on the prone EGFR tetramer, which contains a novel protein-protein interface involving extracellular domain III. This EGFR tetramer is computationally targeted for stabilization by small molecule ligand binding. This study performed virtual screening of a Life Chemicals, Inc. small molecule library of 345,232 drug-like compounds against a molecular dynamics simulation of protein-protein interfaces distinct to the novel tetramer. One hundred nine chemically diverse candidate molecules were selected and evaluated using a cell-based high-content imaging screen that directly assessed induced internalization of the EGFR effector protein Grb2. Positive hits were further evaluated for influence on phosphorylation of EGFR and its effector ERK1/2. Results Fourteen hit compounds affected internalization of Grb2, an adaptor responsive to EGFR activation. Most hits had limited effect on cell viability, and minimally influenced EGFR and ERK1/2 phosphorylation. Docked hit compound poses generally include Arg270 or neighboring residues, which are also involved in binding the effective therapeutic cetuximab, guiding further chemical optimization. Conclusions These data suggest that the EGFR tetrameric configuration offers a novel cancer drug target. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1415-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ursula D Ramirez
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Anna S Nikonova
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Hanqing Liu
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Anna Pecherskaya
- Translational Facility, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Sarah H Lawrence
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Ilya G Serebriiskii
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA. .,Kazan Federal University, Kazan, Russia.
| | - Yan Zhou
- Biostatistics and Bioinformatics Facility, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Matthew K Robinson
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Margret B Einarson
- Translational Facility, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Erica A Golemis
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
| | - Eileen K Jaffe
- Molecular Therapeutics Program, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA, 19111, USA.
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18
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Kovacs E, Zorn JA, Huang Y, Barros T, Kuriyan J. A structural perspective on the regulation of the epidermal growth factor receptor. Annu Rev Biochem 2015; 84:739-64. [PMID: 25621509 DOI: 10.1146/annurev-biochem-060614-034402] [Citation(s) in RCA: 226] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that plays a critical role in the pathogenesis of many cancers. The structure of intact forms of this receptor has yet to be determined, but intense investigations of fragments of the receptor have provided a detailed view of its activation mechanism, which we review here. Ligand binding converts the receptor to a dimeric form, in which contacts are restricted to the receptor itself, allowing heterodimerization of the four EGFR family members without direct ligand involvement. Activation of the receptor depends on the formation of an asymmetric dimer of kinase domains, in which one kinase domain allosterically activates the other. Coupling between the extracellular and intracellular domains may involve a switch between alternative crossings of the transmembrane helices, which form dimeric structures. We also discuss how receptor regulation is compromised by oncogenic mutations and the structural basis for negative cooperativity in ligand binding.
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19
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Bessman NJ, Freed DM, Lemmon MA. Putting together structures of epidermal growth factor receptors. Curr Opin Struct Biol 2014; 29:95-101. [PMID: 25460273 DOI: 10.1016/j.sbi.2014.10.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 09/23/2014] [Accepted: 10/01/2014] [Indexed: 01/15/2023]
Abstract
Numerous crystal structures have been reported for the isolated extracellular region and tyrosine kinase domain of the epidermal growth factor receptor (EGFR) and its relatives, in different states of activation and bound to a variety of inhibitors used in cancer therapy. The next challenge is to put these structures together accurately in functional models of the intact receptor in its membrane environment. The intact EGFR has been studied using electron microscopy, chemical biology methods, biochemically, and computationally. The distinct approaches yield different impressions about the structural modes of communication between extracellular and intracellular regions. They highlight possible differences between ligands, and also underline the need to understand how the receptor interacts with the membrane itself.
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Affiliation(s)
- Nicholas J Bessman
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, United States; Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, United States
| | - Daniel M Freed
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, United States
| | - Mark A Lemmon
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, United States; Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, United States.
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20
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Marquèze-Pouey B, Mailfert S, Rouger V, Goaillard JM, Marguet D. Physiological epidermal growth factor concentrations activate high affinity receptors to elicit calcium oscillations. PLoS One 2014; 9:e106803. [PMID: 25265278 PMCID: PMC4179260 DOI: 10.1371/journal.pone.0106803] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/02/2014] [Indexed: 11/19/2022] Open
Abstract
Signaling mediated by the epidermal growth factor (EGF) is crucial in tissue development, homeostasis and tumorigenesis. EGF is mitogenic at picomolar concentrations and is known to bind its receptor on high affinity binding sites depending of the oligomerization state of the receptor (monomer or dimer). In spite of these observations, the cellular response induced by EGF has been mainly characterized for nanomolar concentrations of the growth factor, and a clear definition of the cellular response to circulating (picomolar) concentrations is still lacking. We investigated Ca2+ signaling, an early event in EGF responses, in response to picomolar doses in COS-7 cells where the monomer/dimer equilibrium is unaltered by the synthesis of exogenous EGFR. Using the fluo5F Ca2+ indicator, we found that picomolar concentrations of EGF induced in 50% of the cells a robust oscillatory Ca2+ signal quantitatively similar to the Ca2+ signal induced by nanomolar concentrations. However, responses to nanomolar and picomolar concentrations differed in their underlying mechanisms as the picomolar EGF response involved essentially plasma membrane Ca2+ channels that are not activated by internal Ca2+ store depletion, while the nanomolar EGF response involved internal Ca2+ release. Moreover, while the picomolar EGF response was modulated by charybdotoxin-sensitive K+ channels, the nanomolar response was insensitive to the blockade of these ion channels.
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Affiliation(s)
- Béatrice Marquèze-Pouey
- Centre d’Immunologie de Marseille-Luminy, UM2 Aix Marseille Université, Marseille, France
- INSERM, U1104, Marseille, France
- CNRS, UMR7280, Marseille, France
- * E-mail:
| | - Sébastien Mailfert
- Centre d’Immunologie de Marseille-Luminy, UM2 Aix Marseille Université, Marseille, France
- INSERM, U1104, Marseille, France
- CNRS, UMR7280, Marseille, France
| | - Vincent Rouger
- Centre d’Immunologie de Marseille-Luminy, UM2 Aix Marseille Université, Marseille, France
- INSERM, U1104, Marseille, France
- CNRS, UMR7280, Marseille, France
| | - Jean-Marc Goaillard
- INSERM, UMR_S 1072, Marseille, France
- Aix-Marseille Université, UNIS, Marseille, France
| | - Didier Marguet
- Centre d’Immunologie de Marseille-Luminy, UM2 Aix Marseille Université, Marseille, France
- INSERM, U1104, Marseille, France
- CNRS, UMR7280, Marseille, France
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21
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Structure-function relationships and supramolecular organization of the EGFR (epidermal growth factor receptor) on the cell surface. Biochem Soc Trans 2014; 42:114-9. [PMID: 24450637 DOI: 10.1042/bst20130236] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Dimerization and higher-order oligomerization are believed to play an important role in the activation of the EGFR (epidermal growth factor receptor). Understanding of the process has been limited by the lack of availability of suitable methods for the measurement in cells of distances in the range 10-100 nm, too short for imaging methods and too long for spectroscopic methods such as FRET. In the present article, we review the current state of our knowledge of EGFR oligomerization, and describe results from a new single-molecule localization method that has allowed the quantitative characterization of the distribution of EGFR-EGFR distances in cells. Recent data suggest the involvement of cortical actin in regulating the formation of EGFR complexes.
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22
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Arkhipov A, Shan Y, Kim ET, Shaw DE. Membrane interaction of bound ligands contributes to the negative binding cooperativity of the EGF receptor. PLoS Comput Biol 2014; 10:e1003742. [PMID: 25058506 PMCID: PMC4109842 DOI: 10.1371/journal.pcbi.1003742] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 06/07/2014] [Indexed: 11/18/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) plays a key role in regulating cell proliferation, migration, and differentiation, and aberrant EGFR signaling is implicated in a variety of cancers. EGFR signaling is triggered by extracellular ligand binding, which promotes EGFR dimerization and activation. Ligand-binding measurements are consistent with a negatively cooperative model in which the ligand-binding affinity at either binding site in an EGFR dimer is weaker when the other site is occupied by a ligand. This cooperativity is widely believed to be central to the effects of ligand concentration on EGFR-mediated intracellular signaling. Although the extracellular portion of the human EGFR dimer has been resolved crystallographically, the crystal structures do not reveal the structural origin of this negative cooperativity, which has remained unclear. Here we report the results of molecular dynamics simulations suggesting that asymmetrical interactions of the two binding sites with the membrane may be responsible (perhaps along with other factors) for this negative cooperativity. In particular, in our simulations the extracellular domains of an EGFR dimer spontaneously lay down on the membrane in an orientation in which favorable membrane contacts were made with one of the bound ligands, but could not be made with the other. Similar interactions were observed when EGFR was glycosylated, as it is in vivo.
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Affiliation(s)
- Anton Arkhipov
- D. E. Shaw Research, New York, New York, United States of America
| | - Yibing Shan
- D. E. Shaw Research, New York, New York, United States of America
| | - Eric T. Kim
- D. E. Shaw Research, New York, New York, United States of America
| | - David E. Shaw
- D. E. Shaw Research, New York, New York, United States of America
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York, United States of America
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23
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Kozer N, Barua D, Henderson C, Nice EC, Burgess AW, Hlavacek WS, Clayton AHA. Recruitment of the adaptor protein Grb2 to EGFR tetramers. Biochemistry 2014; 53:2594-604. [PMID: 24697349 PMCID: PMC4010257 DOI: 10.1021/bi500182x] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Adaptor
protein Grb2 binds phosphotyrosines in the epidermal growth
factor (EGF) receptor (EGFR) and thereby links receptor activation
to intracellular signaling cascades. Here, we investigated how recruitment
of Grb2 to EGFR is affected by the spatial organization and quaternary
state of activated EGFR. We used the techniques of image correlation
spectroscopy (ICS) and lifetime-detected Förster resonance
energy transfer (also known as FLIM-based FRET or FLIM–FRET)
to measure ligand-induced receptor clustering and Grb2 binding to
activated EGFR in BaF/3 cells. BaF/3 cells were stably transfected
with fluorescently labeled forms of Grb2 (Grb2–mRFP) and EGFR
(EGFR–eGFP). Following stimulation of the cells with EGF, we
detected nanometer-scale association of Grb2–mRFP with EGFR–eGFP
clusters, which contained, on average, 4 ± 1 copies of EGFR–eGFP
per cluster. In contrast, the pool of EGFR–eGFP without Grb2–mRFP
had an average cluster size of 1 ± 0.3 EGFR molecules per punctum.
In the absence of EGF, there was no association between EGFR–eGFP
and Grb2–mRFP. To interpret these data, we extended our recently
developed model for EGFR activation, which considers EGFR oligomerization
up to tetramers, to include recruitment of Grb2 to phosphorylated
EGFR. The extended model, with adjustment of one new parameter (the
ratio of the Grb2 and EGFR copy numbers), is consistent with a cluster
size distribution where 2% of EGFR monomers, 5% of EGFR dimers, <1%
of EGFR trimers, and 94% of EGFR tetramers are associated with Grb2.
Together, our experimental and modeling results further implicate
tetrameric EGFR as the key signaling unit and call into question the
widely held view that dimeric EGFR is the predominant signaling unit.
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Affiliation(s)
- Noga Kozer
- Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology , Hawthorn, Victoria 3122, Australia
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24
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Pryor MM, Low-Nam ST, Halász AM, Lidke DS, Wilson BS, Edwards JS. Dynamic transition states of ErbB1 phosphorylation predicted by spatial stochastic modeling. Biophys J 2014; 105:1533-43. [PMID: 24048005 DOI: 10.1016/j.bpj.2013.07.056] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/08/2013] [Accepted: 07/29/2013] [Indexed: 11/25/2022] Open
Abstract
ErbB1 overexpression is strongly linked to carcinogenesis, motivating better understanding of erbB1 dimerization and activation. Recent single-particle-tracking data have provided improved measures of dimer lifetimes and strong evidence that transient receptor coconfinement promotes repeated interactions between erbB1 monomers. Here, spatial stochastic simulations explore the potential impact of these parameters on erbB1 phosphorylation kinetics. This rule-based mathematical model incorporates structural evidence for conformational flux of the erbB1 extracellular domains, as well as asymmetrical orientation of erbB1 cytoplasmic kinase domains during dimerization. The asymmetric dimer model considers the theoretical consequences of restricted transactivation of erbB1 receptors within a dimer, where the N-lobe of one monomer docks with the C-lobe of the second monomer and triggers its catalytic activity. The dynamic nature of the erbB1 phosphorylation state is shown by monitoring activation states of individual monomers as they diffuse, bind, and rebind after ligand addition. The model reveals the complex interplay between interacting liganded and nonliganded species and the influence of their distribution and abundance within features of the membrane landscape.
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Affiliation(s)
- Meghan McCabe Pryor
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico
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25
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Peckys DB, de Jonge N. Liquid scanning transmission electron microscopy: imaging protein complexes in their native environment in whole eukaryotic cells. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:346-65. [PMID: 24548636 DOI: 10.1017/s1431927614000099] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Scanning transmission electron microscopy (STEM) of specimens in liquid, so-called Liquid STEM, is capable of imaging the individual subunits of macromolecular complexes in whole eukaryotic cells in liquid. This paper discusses this new microscopy modality within the context of state-of-the-art microscopy of cells. The principle of operation and equations for the resolution are described. The obtained images are different from those acquired with standard transmission electron microscopy showing the cellular ultrastructure. Instead, contrast is obtained on specific labels. Images can be recorded in two ways, either via STEM at 200 keV electron beam energy using a microfluidic chamber enclosing the cells, or via environmental scanning electron microscopy at 30 keV of cells in a wet environment. The first series of experiments involved the epidermal growth factor receptor labeled with gold nanoparticles. The labels were imaged in whole fixed cells with nanometer resolution. Since the cells can be kept alive in the microfluidic chamber, it is also feasible to detect the labels in unfixed, live cells. The rapid sample preparation and imaging allows studies of multiple whole cells.
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Affiliation(s)
- Diana B Peckys
- 1 Leibniz Institute for New Materials (INM), 66123 Saarbrücken, Germany
| | - Niels de Jonge
- 1 Leibniz Institute for New Materials (INM), 66123 Saarbrücken, Germany
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Loeffler HH, Winn MD. Ligand binding and dynamics of the monomeric epidermal growth factor receptor ectodomain. Proteins 2013; 81:1931-43. [PMID: 23760854 PMCID: PMC4282322 DOI: 10.1002/prot.24339] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 04/26/2013] [Accepted: 05/19/2013] [Indexed: 01/29/2023]
Abstract
The ectodomain of the human epidermal growth factor receptor (hEGFR) controls input to several cell signalling networks via binding with extracellular growth factors. To gain insight into the dynamics and ligand binding of the ectodomain, the hEGFR monomer was subjected to molecular dynamics simulation. The monomer was found to be substantially more flexible than the ectodomain dimer studied previously. Simulations where the endogeneous ligand EGF binds to either Subdomain I or Subdomain III, or where hEGFR is unbound, show significant differences in dynamics. The molecular mechanics Poisson-Boltzmann surface area method has been used to derive relative free energies of ligand binding, and we find that the ligand is capable of binding either subdomain with a slight preference for III. Alanine-scanning calculations for the effect of selected ligand mutants on binding reproduce the trends of affinity measurements. Taken together, these results emphasize the possible role of the ectodomain monomer in the initial step of ligand binding, and add details to the static picture obtained from crystal structures.
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Affiliation(s)
- Hannes H Loeffler
- Scientific Computing Department, STFC Daresbury, Warrington, WA4 4AD, United Kingdom
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Arkhipov A, Shan Y, Kim ET, Dror RO, Shaw DE. Her2 activation mechanism reflects evolutionary preservation of asymmetric ectodomain dimers in the human EGFR family. eLife 2013; 2:e00708. [PMID: 23878723 PMCID: PMC3713454 DOI: 10.7554/elife.00708] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 06/17/2013] [Indexed: 11/18/2022] Open
Abstract
The receptor tyrosine kinase Her2, an intensely pursued drug target, differs from other members of the EGFR family in that it does not bind EGF-like ligands, relying instead on heterodimerization with other (ligand-bound) EGFR-family receptors for activation. The structural basis for Her2 heterodimerization, however, remains poorly understood. The unexpected recent finding of asymmetric ectodomain dimer structures of Drosophila EGFR (dEGFR) suggests a possible structural basis for Her2 heterodimerization, but all available structures for dimers of human EGFR family ectodomains are symmetric. Here, we report results from long-timescale molecular dynamics simulations indicating that a single ligand is necessary and sufficient to stabilize the ectodomain interface of Her2 heterodimers, which assume an asymmetric conformation similar to that of dEGFR dimers. This structural parallelism suggests a dimerization mechanism that has been conserved in the evolution of the EGFR family from Drosophila to human. DOI:http://dx.doi.org/10.7554/eLife.00708.001 ErbB proteins are found in most multi-cellular organisms, and are involved in the regulation of a number of important cellular processes, including proliferation, migration, and differentiation. Humans have four ErbB proteins, which span the plasma membrane of cells. These proteins respond to interactions with molecules outside the cell—such as growth factors and hormones—by sending signals along the appropriate signaling pathway within the cell. ErbB proteins have three portions: an ectodomain that extends outside the cell; a single helix that spans the membrane; and a cytoplasmic domain inside the cell. When a signaling ligand molecule outside the cell binds to the ectodomain of an ErbB protein, this protein must then combine with another ErbB protein to form a dimer before a signal can be sent within the cell. These dimers can include two copies of the same ErbB protein or two different ErbB proteins. However, one of the ErbB proteins—Her2—works in a different way. It cannot bind ligands outside the cell, and it can only send a signal within the cell if it first forms a dimer with an ErbB protein of another type, which itself must be bound to an external ligand. The four ErbB proteins diverged from a common ancestor relatively recently, yet they are now diverse enough to play key roles in a variety of complex signaling networks. In particular, the fact that Her2 cannot bind external ligands, and that it must form a dimer with a different ErbB protein before it can send a signal, has led to suggestions that the role of Her2 is to amplify the signals from other ErbB proteins. Since high levels of Her2 are associated with aggressive forms of breast and ovarian cancer, understanding how it is activated could improve our understanding of these cancers. Arkhipov et al. have now used computer simulations to model how Her2 forms dimers with other ErbB proteins in human cells. They based these simulations on crystal structures of human ErbB proteins and dEGFR, a growth-factor receptor found in fruit flies that closely resembles the ErbB proteins found in humans. They found that the dimers were stable as long as one protein within the dimer was bound to a ligand. Removing this ligand, however, distorted the ectodomain of the host protein, creating a gap that weakened the dimer and prevented Her2 from sending a signal within the cell. Similar results were obtained with the fruit fly dEGFR proteins. These simulations suggest that ErbB proteins form dimers and send signals through a mechanism conserved in evolution. Research in this field might help ongoing efforts to develop new treatments for human tumors characterized by high levels of Her2 expression. DOI:http://dx.doi.org/10.7554/eLife.00708.002
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Ziomkiewicz I, Loman A, Klement R, Fritsch C, Klymchenko AS, Bunt G, Jovin TM, Arndt-Jovin DJ. Dynamic conformational transitions of the EGF receptor in living mammalian cells determined by FRET and fluorescence lifetime imaging microscopy. Cytometry A 2013; 83:794-805. [DOI: 10.1002/cyto.a.22311] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Iwona Ziomkiewicz
- Laboratory of Cellular Dynamics; Max Planck Institute for Biophysical Chemistry; 37077; Göttingen; Germany
| | - Anastasia Loman
- Department of Neuro- and Sensory Physiology; University Medicine Göttingen; 37075; Göttingen; Germany
| | | | - Cornelia Fritsch
- Laboratory of Cellular Dynamics; Max Planck Institute for Biophysical Chemistry; 37077; Göttingen; Germany
| | - Andrey S. Klymchenko
- Laboratoire de Biophotonique et Pharmacologie; UMR 7213 CNRS, Faculté de Pharmacie, Université de Strasbourg; 67401; France
| | | | - Thomas M. Jovin
- Laboratory of Cellular Dynamics; Max Planck Institute for Biophysical Chemistry; 37077; Göttingen; Germany
| | - Donna J. Arndt-Jovin
- Laboratory of Cellular Dynamics; Max Planck Institute for Biophysical Chemistry; 37077; Göttingen; Germany
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张 泳. Progress in Structural and Computational Studies of Epidermal Growth Factor Receptor. Biophysics (Nagoya-shi) 2013. [DOI: 10.12677/biphy.2013.11002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Abstract
Crystal structures of human epidermal growth factor receptor (EGFR) with bound ligand revealed symmetric, doubly ligated receptor dimers thought to represent physiologically active states. Such complexes fail to rationalize negative cooperativity of epidermal growth factor (EGF) binding to EGFR and the behavior of the ligandless EGFR homolog ErbB2/HER2, however. We report cell-based assays that provide evidence for active, singly ligated dimers of human EGFR and its homolog, ErbB4/HER4. We also report crystal structures of the ErbB4/HER4 extracellular region complexed with its ligand Neuregulin-1β that resolve two types of ErbB dimer when compared to EGFR:Ligand complexes. One type resembles the recently reported asymmetric dimer of Drosophila EGFR with a single high-affinity ligand bound and provides a model for singly ligated human ErbB dimers. These results unify models of vertebrate and invertebrate EGFR/ErbB signaling, imply that the tethered conformation of unliganded ErbBs evolved to prevent crosstalk among ErbBs, and establish a molecular basis for both negative cooperativity of ligand binding to vertebrate ErbBs and the absence of active ErbB2/HER2 homodimers in normal conditions.
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Human epidermal growth factor receptor (HER1) aligned on the plasma membrane adopts key features of Drosophila EGFR asymmetry. Biochem Soc Trans 2012; 40:184-8. [DOI: 10.1042/bst20110692] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Current models suggest that ligand-binding heterogeneity in HER1 [human EGFR (epidermal growth factor receptor] arises from negative co-operativity in signalling HER1 dimers, for which the asymmetry of the extracellular region of the Drosophila EGFR has recently provided a structural basis. However, no asymmetry is apparent in the current crystal structure of the isolated extracellular region of HER1. This receptor also differs from the Drosophila EGFR in that negative co-operativity is found only in full-length receptors in cells. Structural insights into HER1 in epithelial cells, derived from FLIM (fluorescence lifetime imaging microscopy) and two-dimensional FRET (Förster resonance energy transfer) combined with Monte Carlo and molecular dynamics simulations, have demonstrated a high-affinity ligand-binding HER1 conformation consistent with the extracellular region aligned flat on the plasma membrane. This conformation shares key features with that of the Drosophila EGFR, suggesting that the structural basis for negative co-operativity is conserved from invertebrates to humans, but that, in HER1, the extracellular region asymmetry requires interactions with the plasma membrane.
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Investigating extracellular in situ EGFR structure and conformational changes using FRET microscopy. Biochem Soc Trans 2012; 40:189-94. [DOI: 10.1042/bst20110632] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The crystallographic structures of functional fragments of ErbBs have provided excellent insights into the geometry of growth factor binding and receptor dimerization. By placing together receptor fragments to build structural models of entire receptors, we expect to understand how these enzymes are allosterically regulated; however, several predictions from these models are inconsistent with experimental evidence from cells. The opening of this gap underlines the need to investigate intact ErbBs by combining cellular and structural studies into a full picture.
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Clarke DT, Botchway SW, Coles BC, Needham SR, Roberts SK, Rolfe DJ, Tynan CJ, Ward AD, Webb SED, Yadav R, Zanetti-Domingues L, Martin-Fernandez ML. Optics clustered to output unique solutions: a multi-laser facility for combined single molecule and ensemble microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:093705. [PMID: 21974592 DOI: 10.1063/1.3635536] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Optics clustered to output unique solutions (OCTOPUS) is a microscopy platform that combines single molecule and ensemble imaging methodologies. A novel aspect of OCTOPUS is its laser excitation system, which consists of a central core of interlocked continuous wave and pulsed laser sources, launched into optical fibres and linked via laser combiners. Fibres are plugged into wall-mounted patch panels that reach microscopy end-stations in adjacent rooms. This allows multiple tailor-made combinations of laser colours and time characteristics to be shared by different end-stations minimising the need for laser duplications. This setup brings significant benefits in terms of cost effectiveness, ease of operation, and user safety. The modular nature of OCTOPUS also facilitates the addition of new techniques as required, allowing the use of existing lasers in new microscopes while retaining the ability to run the established parts of the facility. To date, techniques interlinked are multi-photon/multicolour confocal fluorescence lifetime imaging for several modalities of fluorescence resonance energy transfer (FRET) and time-resolved anisotropy, total internal reflection fluorescence, single molecule imaging of single pair FRET, single molecule fluorescence polarisation, particle tracking, and optical tweezers. Here, we use a well-studied system, the epidermal growth factor receptor network, to illustrate how OCTOPUS can aid in the investigation of complex biological phenomena.
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Affiliation(s)
- David T Clarke
- Science and Technology Facilities Council, Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxford OX11 0FA, United Kingdom
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