1
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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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2
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Choosing the Probe for Single-Molecule Fluorescence Microscopy. Int J Mol Sci 2022; 23:ijms232314949. [PMID: 36499276 PMCID: PMC9735909 DOI: 10.3390/ijms232314949] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/18/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Probe choice in single-molecule microscopy requires deeper evaluations than those adopted for less sensitive fluorescence microscopy studies. Indeed, fluorophore characteristics can alter or hide subtle phenomena observable at the single-molecule level, wasting the potential of the sophisticated instrumentation and algorithms developed for advanced single-molecule applications. There are different reasons for this, linked, e.g., to fluorophore aspecific interactions, brightness, photostability, blinking, and emission and excitation spectra. In particular, these spectra and the excitation source are interdependent, and the latter affects the autofluorescence of sample substrate, medium, and/or biological specimen. Here, we review these and other critical points for fluorophore selection in single-molecule microscopy. We also describe the possible kinds of fluorophores and the microscopy techniques based on single-molecule fluorescence. We explain the importance and impact of the various issues in fluorophore choice, and discuss how this can become more effective and decisive for increasingly demanding experiments in single- and multiple-color applications.
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3
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Bueno-Alejo C, Santana Vega M, Chaplin AK, Farrow C, Axer A, Burley GA, Dominguez C, Kara H, Paschalis V, Tubasum S, Eperon IC, Clark AW, Hudson AJ. Surface Passivation with a Perfluoroalkane Brush Improves the Precision of Single-Molecule Measurements. ACS APPLIED MATERIALS & INTERFACES 2022; 14:49604-49616. [PMID: 36306432 PMCID: PMC9650645 DOI: 10.1021/acsami.2c16647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Single-molecule imaging is invaluable for investigating the heterogeneous behavior and interactions of biological molecules. However, an impediment to precise sampling of single molecules is the irreversible adsorption of components onto the surfaces of cover glasses. This causes continuous changes in the concentrations of different molecules dissolved or suspended in the aqueous phase from the moment a sample is dispensed, which will shift, over time, the position of chemical equilibria between monomeric and multimeric components. Interferometric scattering microscopy (iSCAT) is a technique in the single-molecule toolkit that has the capability to detect unlabeled proteins and protein complexes both as they adsorb onto and desorb from a glass surface. Here, we examine the reversible and irreversible interactions between a number of different proteins and glass via analysis of the adsorption and desorption of protein at the single-molecule level. Furthermore, we present a method for surface passivation that virtually eliminates irreversible adsorption while still ensuring the residence time of molecules on surfaces is sufficient for detection of adsorption by iSCAT. By grafting high-density perfluoroalkane brushes on cover-glass surfaces, we observe approximately equal numbers of adsorption and desorption events for proteins at the measurement surface (±1%). The fluorous-aqueous interface also prevents the kinetic trapping of protein complexes and assists in establishing a thermodynamic equilibrium between monomeric and multimeric components. This surface passivation approach is valuable for in vitro single-molecule experiments using iSCAT microscopy because it allows for continuous monitoring of adsorption and desorption of protein without either a decline in detection events or a change in sample composition due to the irreversible binding of protein to surfaces.
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Affiliation(s)
- Carlos
J. Bueno-Alejo
- School
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Marina Santana Vega
- School
of Engineering, Advanced Research Centre, University of Glasgow, 11 Chapel Lane, Glasgow G11 6EW, United Kingdom
| | - Amanda K. Chaplin
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
- Department
of Molecular and Cellular Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Chloe Farrow
- School
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Alexander Axer
- Strathclyde
Centre for Molecular Bioscience & Department of Pure & Applied
Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom
| | - Glenn A. Burley
- Strathclyde
Centre for Molecular Bioscience & Department of Pure & Applied
Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom
| | - Cyril Dominguez
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
- Department
of Molecular and Cellular Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Hesna Kara
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
- Department
of Molecular and Cellular Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Vasileios Paschalis
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
- Department
of Molecular and Cellular Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Sumera Tubasum
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
- Department
of Molecular and Cellular Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Ian C. Eperon
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
- Department
of Molecular and Cellular Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
| | - Alasdair W. Clark
- School
of Engineering, Advanced Research Centre, University of Glasgow, 11 Chapel Lane, Glasgow G11 6EW, United Kingdom
| | - Andrew J. Hudson
- School
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
- Leicester
Institute of Structural & Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, United Kingdom
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4
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Ogando NS, Metscher E, Moes DJAR, Arends EJ, Tas A, Cross J, Snijder EJ, Teng YKO, de Vries APJ, van Hemert MJ. The Cyclophilin-Dependent Calcineurin Inhibitor Voclosporin Inhibits SARS-CoV-2 Replication in Cell Culture. Transpl Int 2022; 35:10369. [PMID: 35812159 PMCID: PMC9263094 DOI: 10.3389/ti.2022.10369] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 05/23/2022] [Indexed: 11/26/2022]
Abstract
Kidney transplant recipients (KTRs) are at increased risk for a more severe course of COVID-19, due to their pre-existing comorbidity and immunosuppression. Consensus protocols recommend lowering immunosuppression in KTRs with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but the optimal combination remains unclear. Calcineurin inhibitors (CNIs) are cornerstone immunosuppressants used in KTRs and some have been reported to possess antiviral activity against RNA viruses, including coronaviruses. Here, we evaluated the effect of the CNIs tacrolimus, cyclosporin A, and voclosporin (VCS), as well as other immunosuppressants, on SARS-CoV-2 replication in cell-based assays. Unexpected, loss of compound due to plastic binding and interference of excipients in pharmaceutical formulations (false-positive results) complicated the determination of EC50 values of cyclophilin-dependent CNI’s in our antiviral assays. Some issues could be circumvented by using exclusively glass lab ware with pure compounds. In these experiments, VCS reduced viral progeny yields in human Calu-3 cells at low micromolar concentrations and did so more effectively than cyclosporin A, tacrolimus or other immunosuppressants. Although, we cannot recommend a particular immunosuppressive regimen in KTRs with COVID-19, our data suggest a potential benefit of cyclophilin-dependent CNIs, in particular VCS in reducing viral progeny, which warrants further clinical evaluation in SARS-CoV-2-infected KTRs.
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Affiliation(s)
- Natacha S. Ogando
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, Netherlands
| | - Erik Metscher
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, Netherlands
| | - Dirk Jan A. R. Moes
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, Netherlands
- Leiden Transplant Center, Leiden University Medical Center, Leiden, Netherlands
| | - Eline J. Arends
- Department of Nephrology, Leiden University Medical Center, Leiden, Netherlands
| | - Ali Tas
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, Netherlands
| | | | - Eric J. Snijder
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, Netherlands
| | - Y. K. Onno Teng
- Leiden Transplant Center, Leiden University Medical Center, Leiden, Netherlands
- Department of Nephrology, Leiden University Medical Center, Leiden, Netherlands
| | - Aiko P. J. de Vries
- Leiden Transplant Center, Leiden University Medical Center, Leiden, Netherlands
- Department of Nephrology, Leiden University Medical Center, Leiden, Netherlands
| | - Martijn J. van Hemert
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, Netherlands
- *Correspondence: Martijn J. van Hemert,
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5
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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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6
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Cao F, Li Y, Wu J, Liu W, Ngai T. Measurements of interactions between fluorescent molecules and polyethylene glycol self-assembled monolayers. SOFT MATTER 2021; 18:236-243. [PMID: 34874390 DOI: 10.1039/d1sm01329g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Blocking the non-specific binding of fluorescent biomolecules to substrates is one of the most important approaches to minimize the background noise in single-molecule fluorescence detection. Polyethylene glycol (PEG) and its derivatives are the most frequently used self-assembled monolayers (SAMs) for surface passivation because they are particularly effective to reduce the adsorption of a majority of biomolecules. Most studies related to PEG SAMs focus only on the interactions between biomolecules and substrates, while few reports exist in which the interactions between fluorophores and organosilane SAMs are directly examined. The objective of this study is to try to clarify the interactions between fluorescein isothiocyanate (FITC) and PEG SAMs at different ionic strengths. Total internal reflection microscopy (TIRM) was utilized for quantitative analysis of the interactions. At low ionic strength, long-range attractions between FITC-modified polystyrene-silica particles and PEG SAM grafting substrates were observed, even though both of them had an ensemble-averaged negative charge. The origin of this attraction could be correlated to their nonuniformly charged surfaces. At high ionic strength, van der Waals attraction at short distances was measured as the electrostatic interactions were completely screened. Due to the polarizability of the FITC molecule, the van der Waals attractions increased with the thickness of the PEG SAMs. This phenomenon is explained by the hydration shell of the PEG SAMs.
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Affiliation(s)
- Feng Cao
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
| | - Yinan Li
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
| | - Jiahao Wu
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
| | - Wei Liu
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
| | - To Ngai
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
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7
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Ha B, Kim TJ, Moon E, Giaccia AJ, Pratx G. Flow radiocytometry using droplet optofluidics. Biosens Bioelectron 2021; 194:113565. [PMID: 34492500 PMCID: PMC8530933 DOI: 10.1016/j.bios.2021.113565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/22/2021] [Accepted: 08/11/2021] [Indexed: 11/29/2022]
Abstract
Flow-based cytometry methods are widely used to analyze heterogeneous cell populations. However, their use for small molecule studies remains limited due to bulky fluorescent labels that often interfere with biochemical activity in cells. In contrast, radiotracers require minimal modification of their target molecules and can track biochemical processes with negligible interference and high specificity. Here, we introduce flow radiocytometry (FRCM) that broadens the scope of current cytometry methods to include beta-emitting radiotracers as probes for single cell studies. FRCM uses droplet microfluidics and radiofluorogenesis to translate the radioactivity of single cells into a fluorescent signal that is then read out using a high-throughput optofluidic device. As a proof of concept, we quantitated [18F]fluorodeoxyglucose radiotracer uptake in single human breast cancer cells and successfully assessed the metabolic flux of glucose and its heterogeneity at the cellular level. We believe FRCM has potential applications ranging from analytical assays for cancer and other diseases to development of small-molecule drugs.
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Affiliation(s)
- Byunghang Ha
- Department of Radiation Oncology, Stanford University, Stanford, CA, 94305-5847, USA; Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305-3011, USA.
| | - Tae Jin Kim
- Department of Radiation Oncology, Stanford University, Stanford, CA, 94305-5847, USA
| | - Ejung Moon
- Department of Radiation Oncology, Stanford University, Stanford, CA, 94305-5847, USA
| | - Amato J Giaccia
- Department of Radiation Oncology, Stanford University, Stanford, CA, 94305-5847, USA
| | - Guillem Pratx
- Department of Radiation Oncology, Stanford University, Stanford, CA, 94305-5847, USA.
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8
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Kenath GS, Karanastasis AA, Ullal CK. Super-Resolution Imaging of Spatial Heterogeneities in Model Thermosensitive Hydrogels with Implications for Their Origins. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gopal S. Kenath
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States
| | - Apostolos A. Karanastasis
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States
| | - Chaitanya K. Ullal
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States
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9
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Larsen JB, Taebnia N, Dolatshahi-Pirouz A, Eriksen AZ, Hjørringgaard C, Kristensen K, Larsen NW, Larsen NB, Marie R, Mündler AK, Parhamifar L, Urquhart AJ, Weller A, Mortensen KI, Flyvbjerg H, Andresen TL. Imaging therapeutic peptide transport across intestinal barriers. RSC Chem Biol 2021; 2:1115-1143. [PMID: 34458827 PMCID: PMC8341777 DOI: 10.1039/d1cb00024a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 06/09/2021] [Indexed: 12/14/2022] Open
Abstract
Oral delivery is a highly preferred method for drug administration due to high patient compliance. However, oral administration is intrinsically challenging for pharmacologically interesting drug classes, in particular pharmaceutical peptides, due to the biological barriers associated with the gastrointestinal tract. In this review, we start by summarizing the pharmacological performance of several clinically relevant orally administrated therapeutic peptides, highlighting their low bioavailabilities. Thus, there is a strong need to increase the transport of peptide drugs across the intestinal barrier to realize future treatment needs and further development in the field. Currently, progress is hampered by a lack of understanding of transport mechanisms that govern intestinal absorption and transport of peptide drugs, including the effects of the permeability enhancers commonly used to mediate uptake. We describe how, for the past decades, mechanistic insights have predominantly been gained using functional assays with end-point read-out capabilities, which only allow indirect study of peptide transport mechanisms. We then focus on fluorescence imaging that, on the other hand, provides opportunities to directly visualize and thus follow peptide transport at high spatiotemporal resolution. Consequently, it may provide new and detailed mechanistic understanding of the interplay between the physicochemical properties of peptides and cellular processes; an interplay that determines the efficiency of transport. We review current methodology and state of the art in the field of fluorescence imaging to study intestinal barrier transport of peptides, and provide a comprehensive overview of the imaging-compatible in vitro, ex vivo, and in vivo platforms that currently are being developed to accelerate this emerging field of research.
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Affiliation(s)
- Jannik Bruun Larsen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Nayere Taebnia
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Alireza Dolatshahi-Pirouz
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Anne Zebitz Eriksen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Claudia Hjørringgaard
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Kasper Kristensen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Nanna Wichmann Larsen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Niels Bent Larsen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Rodolphe Marie
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Ann-Kathrin Mündler
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Ladan Parhamifar
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Andrew James Urquhart
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Arjen Weller
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Kim I Mortensen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Henrik Flyvbjerg
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
| | - Thomas Lars Andresen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Department of Health Technology, Technical University of Denmark DK-2800, Kgs. Lyngby Denmark
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10
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Membrane dynamics are slowed for Alexa594-labeled membrane proteins due to substrate interactions. BBA ADVANCES 2021; 1:100026. [PMID: 37082018 PMCID: PMC10074974 DOI: 10.1016/j.bbadva.2021.100026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The addition of fluorescent dyes to proteins, lipids and other biological molecules can affect a range of processes such as mobility, molecular interactions, localization, and, ultimately, function. The dynamics of a protein can be dramatically affected if the label interacts non-specifically with the substrate or with other molecules in the system. To test how dye-substrate interactions affect protein diffusion, fluorescence recovery after photobleaching (FRAP) measurements were designed to explicitly determine the role of the dye on the diffusion of a transmembrane protein, Syntaxin1a, expressed on the cell surface. Syntaxin1a, was tagged with EGFP on the extracellular side and an EGFP nanobody with or without a dye label was attached. FRAP was performed on Syx1a-EGFP and the choice of cell growth substrate affected mobility in the presence of a dye labeled nanobody. This work provides evidence for choosing fibronectin (Fn) over poly-L-lysine (PLL) in FRAP and single molecule tracking measurements when using Alexa594, a common probe for red fluorescent measurements. Alexa594-labeled nanobody but not unlabeled nanobody, dramatically reduced the mobility of Syx1a-EGFP when cells were cultured on PLL. However, when Fn was used, the mobility returned. Mobility measured by single molecule tracking measurements align with the FRAP measurements with Fn coated surfaces being more mobile than PLL.
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11
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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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12
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Patra S, Baibakov M, Claude JB, Wenger J. Surface passivation of zero-mode waveguide nanostructures: benchmarking protocols and fluorescent labels. Sci Rep 2020; 10:5235. [PMID: 32251328 PMCID: PMC7089978 DOI: 10.1038/s41598-020-61856-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 12/19/2019] [Indexed: 11/10/2022] Open
Abstract
Zero mode waveguide (ZMW) nanoapertures efficiently confine the light down to the nanometer scale and overcome the diffraction limit in single molecule fluorescence analysis. However, unwanted adhesion of the fluorescent molecules on the ZMW surface can severely hamper the experiments. Therefore a proper surface passivation is required for ZMWs, but information is currently lacking on both the nature of the adhesion phenomenon and the optimization of the different passivation protocols. Here we monitor the influence of the fluorescent dye (Alexa Fluor 546 and 647, Atto 550 and 647N) on the non-specific adhesion of double stranded DNA molecule. We show that the nonspecific adhesion of DNA double strands onto the ZMW surface is directly mediated by the organic fluorescent dye being used, as Atto 550 and Atto 647N show a pronounced tendency to adhere to the ZMW while the Alexa Fluor 546 and 647 are remarkably free of this effect. Despite the small size of the fluorescent label, the surface charge and hydrophobicity of the dye appear to play a key role in promoting the DNA affinity for the ZMW surface. Next, different surface passivation methods (bovine serum albumin BSA, polyethylene glycol PEG, polyvinylphosphonic acid PVPA) are quantitatively benchmarked by fluorescence correlation spectroscopy to determine the most efficient approaches to prevent the adsorption of Atto 647N labeled DNA. Protocols using PVPA and PEG-silane of 1000 Da molar mass are found to drastically avoid the non-specific adsorption into ZMWs. Optimizing both the choice of the fluorescent dye and the surface passivation protocol are highly significant to expand the use of ZMWs for single molecule fluorescence applications.
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Affiliation(s)
- Satyajit Patra
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013, Marseille, France
| | - Mikhail Baibakov
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013, Marseille, France
| | - Jean-Benoît Claude
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013, Marseille, France
| | - Jérôme Wenger
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013, Marseille, France.
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13
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Solid immersion microscopy images cells under cryogenic conditions with 12 nm resolution. Commun Biol 2019; 2:74. [PMID: 30820469 PMCID: PMC6385270 DOI: 10.1038/s42003-019-0317-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 01/22/2019] [Indexed: 12/28/2022] Open
Abstract
Super-resolution fluorescence microscopy plays a crucial role in our understanding of cell structure and function by reporting cellular ultrastructure with 20–30 nm resolution. However, this resolution is insufficient to image macro-molecular machinery at work. A path to improve resolution is to image under cryogenic conditions. This substantially increases the brightness of most fluorophores and preserves native ultrastructure much better than chemical fixation. Cryogenic conditions are, however, underutilised because of the lack of compatible high numerical aperture objectives. Here, using a low-cost super-hemispherical solid immersion lens (superSIL) and a basic set-up we achieve 12 nm resolution under cryogenic conditions, to our knowledge the best yet attained in cells using simple set-ups and/or commercial systems. By also allowing multicolour imaging, and by paving the way to total-internal-reflection fluorescence imaging of mammalian cells under cryogenic conditions, superSIL microscopy opens a straightforward route to achieve unmatched resolution on bacterial and mammalian cell samples. Lin Wang et al. present a new super-resolution modality using a super-hemispherical immersion lens. They achieve a 12 nm spatial resolution in cells under cryogenic conditions, which offers the technical means to study bacterial and mammalian cell samples at molecule localisation length-scales.
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14
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Roberts SK, Hirsch M, McStea A, Zanetti-Domingues LC, Clarke DT, Claus J, Parker PJ, Wang L, Martin-Fernandez AML. Cluster Analysis of Endogenous HER2 and HER3 Receptors in SKBR3 Cells. Bio Protoc 2018; 8:e3096. [PMID: 34532543 DOI: 10.21769/bioprotoc.3096] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 01/11/2023] Open
Abstract
The Human Epidermal Growth Factor Receptor (HER) family of receptor tyrosine kinases consists of four, single pass, transmembrane receptor homologs (HER1-4) that act to regulate many critical processes in normal and tumor cells. HER2 is overexpressed in many tumors, and the deregulated proliferation of cancerous cells is driven by cooperation with its preferred receptor partner, HER3. The assessment of the in-situ organization of tagged HER2 and HER3 using super-resolution microscopy reveals quantitative Single Molecule Localization Microscopy (SMLM) as an ideal bioanalytical tool to characterize receptor clusters. Clustering of receptors is an important regulatory mechanism to prime cells to respond to stimuli so, to understand these processes, it is necessary to measure parameters such as numbers of clusters, cluster radii and the number of localizations per cluster for different perturbations. Previously, Fluorescence Localization Imaging with Photobleaching (FLImP), another nanoscale, single-molecule technique, characterized the oligomerization state of HER1 [or Epidermal Growth Factor Receptors (EGFR)] in cell membranes. To achieve an unprecedented resolution (< 5 nm) for inter-molecular separations in EGFR oligomers using FLImP, very few receptors are tagged, and so this method is unsuitable for measurements of whole receptor populations in cancer cells where receptors are frequently upregulated. Here, in order to detect all receptors involved in cluster formation, we saturate endogenous HER2 and HER3 membrane receptors with ligands at a 1:1 dye to protein ratio, in the presence or absence of therapeutic drugs (lapatinib or bosutinib). This is performed in the commonly used breast cancer cell line model SKBR3 cells, where there are ~1.6 million HER2 receptors/cell and 10,000-40,000 HER3 receptors/cell. The basal state of these receptors is studied using HER2- or HER3-specific Affibodies, and likewise, the active state is probed using the natural HER3 ligand, Neuregulin-beta1 (NRGβ1). Stochastic Optical Reconstruction Microscopy (STORM), one form of SMLM, was used here to image cells, which were chemically fixed to minimize image blurring and provide data (x and y coordinates and standard deviation of the measured localizations) for cluster analysis. Further analysis can also determine proportions of receptor colocalizations. Our findings show that lapatinib-bound HER2, complexed with HER3 via a non-canonical kinase dimer structure, induces higher order oligomers. We hypothesized that nucleation of receptors creates signaling platforms that explain the counterintuitive, increase in cell proliferation upon ligand binding, in the presence of the HER2-inhibitor lapatinib.
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Affiliation(s)
- Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Alexandra McStea
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, 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, Didcot, Oxford, OX11 0QX, UK
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Jeroen Claus
- Protein Phosphorylation Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Peter J Parker
- Protein Phosphorylation Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,School of Cancer and Pharmaceutical Sciences, New Hunt's House, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Lin Wang
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - And Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK.,School of Cancer and Pharmaceutical Sciences, New Hunt's House, King's College London, Guy's Campus, London, SE1 1UL, UK
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15
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Ivanusic D, Madela K, Denner J. Easy and low-cost stable positioning of suspension cells during live-cell imaging. J Biol Methods 2017; 4:e80. [PMID: 31453234 PMCID: PMC6706139 DOI: 10.14440/jbm.2017.203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 06/14/2017] [Accepted: 07/28/2017] [Indexed: 12/21/2022] Open
Abstract
Dynamic processes of cells can be best monitored when living cells are analyzed by imaging. While it is easy to observe adherent living cells it has been extremely challenging to analyze suspension cells. This cell type floats freely in the culture dish, and it is only a question of time when the focus or the observation field is lost. In order to keep the cells in focus, an easy and inexpensive method allowing the observation of living suspension cells during confocal laser scanning microscope imaging was developed.
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16
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Tiede C, Bedford R, Heseltine SJ, Smith G, Wijetunga I, Ross R, AlQallaf D, Roberts APE, Balls A, Curd A, Hughes RE, Martin H, Needham SR, Zanetti-Domingues LC, Sadigh Y, Peacock TP, Tang AA, Gibson N, Kyle H, Platt GW, Ingram N, Taylor T, Coletta LP, Manfield I, Knowles M, Bell S, Esteves F, Maqbool A, Prasad RK, Drinkhill M, Bon RS, Patel V, Goodchild SA, Martin-Fernandez M, Owens RJ, Nettleship JE, Webb ME, Harrison M, Lippiat JD, Ponnambalam S, Peckham M, Smith A, Ferrigno PK, Johnson M, McPherson MJ, Tomlinson DC. Affimer proteins are versatile and renewable affinity reagents. eLife 2017; 6:e24903. [PMID: 28654419 PMCID: PMC5487212 DOI: 10.7554/elife.24903] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 06/07/2017] [Indexed: 12/11/2022] Open
Abstract
Molecular recognition reagents are key tools for understanding biological processes and are used universally by scientists to study protein expression, localisation and interactions. Antibodies remain the most widely used of such reagents and many show excellent performance, although some are poorly characterised or have stability or batch variability issues, supporting the use of alternative binding proteins as complementary reagents for many applications. Here we report on the use of Affimer proteins as research reagents. We selected 12 diverse molecular targets for Affimer selection to exemplify their use in common molecular and cellular applications including the (a) selection against various target molecules; (b) modulation of protein function in vitro and in vivo; (c) labelling of tumour antigens in mouse models; and (d) use in affinity fluorescence and super-resolution microscopy. This work shows that Affimer proteins, as is the case for other alternative binding scaffolds, represent complementary affinity reagents to antibodies for various molecular and cell biology applications.
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Affiliation(s)
- Christian Tiede
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Robert Bedford
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Sophie J Heseltine
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Gina Smith
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Imeshi Wijetunga
- Leeds Institute of Cancer Studies and Pathology, University of Leeds, Leeds, United Kingdom
| | - Rebecca Ross
- Leeds Institute of Cancer Studies and Pathology, University of Leeds, Leeds, United Kingdom
| | - Danah AlQallaf
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | | | - Alexander Balls
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Alistair Curd
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Ruth E Hughes
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Heather Martin
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
| | | | | | - Anna A Tang
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Naomi Gibson
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Hannah Kyle
- Avacta Life Sciences, Wetherby, United Kingdom
| | | | - Nicola Ingram
- Leeds Institute of Cancer Studies and Pathology, University of Leeds, Leeds, United Kingdom
| | - Thomas Taylor
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Louise P Coletta
- Leeds Institute of Cancer Studies and Pathology, University of Leeds, Leeds, United Kingdom
| | - Iain Manfield
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Margaret Knowles
- Leeds Institute of Cancer Studies and Pathology, University of Leeds, Leeds, United Kingdom
| | - Sandra Bell
- Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds, United Kingdom
| | - Filomena Esteves
- Leeds Institute of Cancer Studies and Pathology, University of Leeds, Leeds, United Kingdom
| | - Azhar Maqbool
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Raj K Prasad
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Mark Drinkhill
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Robin S Bon
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | | | | | - Marisa Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Ray J Owens
- Oxford Protein Production Facility UK, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Joanne E Nettleship
- Oxford Protein Production Facility UK, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Michael E Webb
- School of Chemistry, University of Leeds, Leeds, United Kingdom
| | - Michael Harrison
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Jonathan D Lippiat
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Sreenivasan Ponnambalam
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Michelle Peckham
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | | | | | | | - Michael J McPherson
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Darren Charles Tomlinson
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
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17
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Webb SED, Hirsch M, Needham SR, Coles BC, Scherer KM, Roberts SK, Zanetti-Domingues LC, Tynan CJ, Martin-Fernandez ML, Rolfe DJ. Nanometric molecular separation measurements by single molecule photobleaching. Methods 2015; 88:76-80. [PMID: 25980369 DOI: 10.1016/j.ymeth.2015.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/08/2015] [Accepted: 05/06/2015] [Indexed: 01/03/2023] Open
Abstract
Although considerable progress has been made in imaging distances in cells below the diffraction limit using FRET and super-resolution microscopy, methods for determining the separation of macromolecules in the 10-50 nm range have been elusive. We have developed fluorophore localisation imaging with photobleaching (FLImP), based on the quantised bleaching of individual protein-bound dye molecules, to quantitate the molecular separations in oligomers and nanoscale clusters. We demonstrate the benefits of using our method in studying the nanometric organisation of the epidermal growth factor receptor in cells.
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Affiliation(s)
- Stephen E D Webb
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Benjamin C Coles
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Kathrin M Scherer
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK.
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18
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Gust A, Zander A, Gietl A, Holzmeister P, Schulz S, Lalkens B, Tinnefeld P, Grohmann D. A starting point for fluorescence-based single-molecule measurements in biomolecular research. Molecules 2014; 19:15824-65. [PMID: 25271426 PMCID: PMC6271140 DOI: 10.3390/molecules191015824] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/17/2014] [Accepted: 09/17/2014] [Indexed: 01/24/2023] Open
Abstract
Single-molecule fluorescence techniques are ideally suited to provide information about the structure-function-dynamics relationship of a biomolecule as static and dynamic heterogeneity can be easily detected. However, what type of single-molecule fluorescence technique is suited for which kind of biological question and what are the obstacles on the way to a successful single-molecule microscopy experiment? In this review, we provide practical insights into fluorescence-based single-molecule experiments aiming for scientists who wish to take their experiments to the single-molecule level. We especially focus on fluorescence resonance energy transfer (FRET) experiments as these are a widely employed tool for the investigation of biomolecular mechanisms. We will guide the reader through the most critical steps that determine the success and quality of diffusion-based confocal and immobilization-based total internal reflection fluorescence microscopy. We discuss the specific chemical and photophysical requirements that make fluorescent dyes suitable for single-molecule fluorescence experiments. Most importantly, we review recently emerged photoprotection systems as well as passivation and immobilization strategies that enable the observation of fluorescently labeled molecules under biocompatible conditions. Moreover, we discuss how the optical single-molecule toolkit has been extended in recent years to capture the physiological complexity of a cell making it even more relevant for biological research.
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Affiliation(s)
- Alexander Gust
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Adrian Zander
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Andreas Gietl
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Phil Holzmeister
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Sarah Schulz
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Birka Lalkens
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Philip Tinnefeld
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Dina Grohmann
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany.
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19
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Hughes LD, Rawle RJ, Boxer SG. Choose your label wisely: water-soluble fluorophores often interact with lipid bilayers. PLoS One 2014; 9:e87649. [PMID: 24503716 PMCID: PMC3913624 DOI: 10.1371/journal.pone.0087649] [Citation(s) in RCA: 207] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 12/27/2013] [Indexed: 11/18/2022] Open
Abstract
Water-soluble organic fluorophores are widely used as labels in biological systems. However, in many cases these fluorophores can interact strongly with lipid bilayers, influencing the interaction of the target with the bilayer and/or leading to misleading fluorescent signals. Here, we quantify the interaction of 32 common water-soluble dyes with model lipid bilayers to serve as an additional criterion when selecting a dye label.
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Affiliation(s)
- Laura D. Hughes
- Department of Chemistry, Stanford University, Stanford, California, United States
| | - Robert J. Rawle
- Department of Chemistry, Stanford University, Stanford, California, United States
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, California, United States
- * E-mail:
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20
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Hydrophobic fluorescent probes introduce artifacts into single molecule tracking experiments due to non-specific binding. PLoS One 2013; 8:e74200. [PMID: 24066121 PMCID: PMC3774629 DOI: 10.1371/journal.pone.0074200] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 07/26/2013] [Indexed: 12/28/2022] Open
Abstract
Single-molecule techniques are powerful tools to investigate the structure and dynamics of macromolecular complexes; however, data quality can suffer because of weak specific signal, background noise and dye bleaching and blinking. It is less well-known, but equally important, that non-specific binding of probe to substrates results in a large number of immobile fluorescent molecules, introducing significant artifacts in live cell experiments. Following from our previous work in which we investigated glass coating substrates and demonstrated that the main contribution to this non-specific probe adhesion comes from the dye, we carried out a systematic investigation of how different dye chemistries influence the behaviour of spectrally similar fluorescent probes. Single-molecule brightness, bleaching and probe mobility on the surface of live breast cancer cells cultured on a non-adhesive substrate were assessed for anti-EGFR affibody conjugates with 14 different dyes from 5 different manufacturers, belonging to 3 spectrally homogeneous bands (491 nm, 561 nm and 638 nm laser lines excitation). Our results indicate that, as well as influencing their photophysical properties, dye chemistry has a strong influence on the propensity of dye-protein conjugates to adhere non-specifically to the substrate. In particular, hydrophobicity has a strong influence on interactions with the substrate, with hydrophobic dyes showing much greater levels of binding. Crucially, high levels of non-specific substrate binding result in calculated diffusion coefficients significantly lower than the true values. We conclude that the physic-chemical properties of the dyes should be considered carefully when planning single-molecule experiments. Favourable dye characteristics such as photostability and brightness can be offset by the propensity of a conjugate for non-specific adhesion.
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21
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Waters JT, Kim HD. Equilibrium Statistics of a Surface-Pinned Semiflexible Polymer. Macromolecules 2013. [DOI: 10.1021/ma4011704] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- James T. Waters
- School of
Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Harold D. Kim
- School of
Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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22
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Needham SR, Hirsch M, Rolfe DJ, Clarke DT, Zanetti-Domingues LC, Wareham R, Martin-Fernandez ML. Measuring EGFR separations on cells with ~10 nm resolution via fluorophore localization imaging with photobleaching. PLoS One 2013; 8:e62331. [PMID: 23650512 PMCID: PMC3641073 DOI: 10.1371/journal.pone.0062331] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Accepted: 03/20/2013] [Indexed: 01/17/2023] Open
Abstract
Detecting receptor dimerisation and other forms of clustering on the cell surface depends on methods capable of determining protein-protein separations with high resolution in the ~10-50 nm range. However, this distance range poses a significant challenge because it is too large for fluorescence resonance energy transfer and contains distances too small for all other techniques capable of high-resolution in cells. Here we have adapted the technique of fluorophore localisation imaging with photobleaching to measure inter-receptor separations in the cellular environment. Using the epidermal growth factor receptor, a key cancer target molecule, we demonstrate ~10 nm resolution while continuously covering the range of ~10-80 nm. By labelling the receptor on cells expressing low receptor numbers with a fluorescent antagonist we have found inter-receptor separations all the way up from 8 nm to 59 nm. Our data are consistent with epidermal growth factor receptors being able to form homo-polymers of at least 10 receptors in the absence of activating ligands.
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Affiliation(s)
- Sarah R. Needham
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, United Kingdom
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, United Kingdom
| | - Daniel J. Rolfe
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, United Kingdom
| | - David T. Clarke
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, United Kingdom
| | - Laura C. Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, United Kingdom
| | - Richard Wareham
- Department of Engineering, University of Cambridge, Cambridge, United Kingdom
| | - Marisa L. Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, United Kingdom
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23
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Single molecule fluorescence detection and tracking in mammalian cells: the state-of-the-art and future perspectives. Int J Mol Sci 2012. [PMID: 23203092 PMCID: PMC3509608 DOI: 10.3390/ijms131114742] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Insights from single-molecule tracking in mammalian cells have the potential to greatly contribute to our understanding of the dynamic behavior of many protein families and networks which are key therapeutic targets of the pharmaceutical industry. This is particularly so at the plasma membrane, where the method has begun to elucidate the mechanisms governing the molecular interactions that underpin many fundamental processes within the cell, including signal transduction, receptor recognition, cell-cell adhesion, etc. However, despite much progress, single-molecule tracking faces challenges in mammalian samples that hinder its general application in the biomedical sciences. Much work has recently focused on improving the methods for fluorescent tagging of target molecules, detection and localization of tagged molecules, which appear as diffraction-limited spots in charge-coupled device (CCD) images, and objectively establishing the correspondence between moving particles in a sequence of image frames to follow their diffusive behavior. In this review we outline the state-of-the-art in the field and discuss the advantages and limitations of the methods available in the context of specific applications, aiming at helping researchers unfamiliar with single molecules methods to plan out their experiments.
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