1
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Urbiola K, Blanco-Fernández L, Ogris M, Rödl W, Wagner E, Tros de Ilarduya C. Novel PAMAM-PEG-Peptide Conjugates for siRNA Delivery Targeted to the Transferrin and Epidermal Growth Factor Receptors. J Pers Med 2018; 8:jpm8010004. [PMID: 29315261 PMCID: PMC5872078 DOI: 10.3390/jpm8010004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/19/2017] [Accepted: 12/27/2017] [Indexed: 12/25/2022] Open
Abstract
The transferrin (TfR) and epidermal growth factor receptors (EGFR) are known to be overexpressed on the surface of a wide variety of tumor cells. Therefore, the peptides B6 (TfR specific) and GE11 (targeted to the EGFR) were linked to the PAMAM (polyamidoamine) structure via a polyethylenglycol (PEG) 2 kDa chain with the aim of improving the silencing capacity of the PAMAM-based dendriplexes. The complexes showed an excellent binding capacity to the siRNA with a maximal condensation at nitrogen/phosphate (N/P) 2. The nanoparticles formed exhibited hydrodynamic diameters below 200 nm. The zeta potential was always positive, despite the complexes containing the PEG chain in the structure showing a drop of the values due to the shielding effect. The gene silencing capacity was assayed in HeLa and LS174T cells stably transfected with the eGFPLuc cassette. The dendriplexes containing a specific anti luciferase siRNA, assayed at different N/P ratios, were able to mediate a mean decrease of the luciferase expression values of 14% for HeLa and 20% in LS174T cells, compared to an unspecific siRNA-control. (p < 0.05). In all the conditions assayed, dendriplexes resulted to be non-toxic and viability was always above 75%.
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Affiliation(s)
- Koldo Urbiola
- Department of Pharmacy and Pharmaceutical Technology, School of Pharmacy, University of Navarra, 31080 Pamplona, Spain; (K.U.); (L.B.-F.)
| | - Laura Blanco-Fernández
- Department of Pharmacy and Pharmaceutical Technology, School of Pharmacy, University of Navarra, 31080 Pamplona, Spain; (K.U.); (L.B.-F.)
| | - Manfred Ogris
- Department of Pharmaceutical Chemistry, Laboratory of MacroMolecular Cancer Therapeutics (MMCT), University of Vienna, 1010 Vienna, Austria;
| | - Wolfgang Rödl
- Pharmaceutical Biotechnology, Center for NanoScience (CeNS), Ludwig-Maximilians-University (LMU) 80799 Munich, Germany; (W.R.); (E.W.)
| | - Ernst Wagner
- Pharmaceutical Biotechnology, Center for NanoScience (CeNS), Ludwig-Maximilians-University (LMU) 80799 Munich, Germany; (W.R.); (E.W.)
| | - Conchita Tros de Ilarduya
- Department of Pharmacy and Pharmaceutical Technology, School of Pharmacy, University of Navarra, 31080 Pamplona, Spain; (K.U.); (L.B.-F.)
- Correspondence: ; Tel.: +34-948-425600 (ext. 80-6375)
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Chowdhury SM, Xie S, Fang J, Lee SK, Sitharaman B. Nanoparticle-Facilitated Membrane Depolarization-Induced Receptor Activation: Implications on Cellular Uptake and Drug Delivery. ACS Biomater Sci Eng 2016; 2:2153-2161. [PMID: 33465891 DOI: 10.1021/acsbiomaterials.6b00338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cell-specific uptake of drug delivery systems (DDSs) are crucial to achieve optimal efficacy of many drugs. Widely employed strategies to facilitate targeted intracellular drug delivery involves attachment of targeting ligands (peptides or antibodies) to DDSs. Target receptors mutations can limit the effectiveness of this approach. Herein, we demonstrate, through in vitro inhibitory and drug delivery studies, that graphene nanoribbons (GNRs), water dispersed with the amphiphilic polymer called PEG-DSPE ((1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N [amino (polyethylene glycol)]) (induce membrane depolarization-mediated epidermal growth factor receptor (EGFR) activation. This phenomenon is ligand-independent and EGFR activation occurs via influx of Ca2+ ions from the extracellular space. We further provide evidence, through in vivo studies, that this mechanism could be exploited to facilitate efficacious drug delivery into tumors that overexpress EGFR. The results suggest that transient membrane depolarization-facilitated cell receptor activation can be employed as an alternate strategy for enhanced intracellular drug delivery.
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Affiliation(s)
- Sayan Mullick Chowdhury
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Shawn Xie
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Justin Fang
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Stephen K Lee
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Balaji Sitharaman
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
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3
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Zhao C, Busch DJ, Vershel CP, Stachowiak JC. Multifunctional Transmembrane Protein Ligands for Cell-Specific Targeting of Plasma Membrane-Derived Vesicles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:3837-48. [PMID: 27294846 PMCID: PMC5523125 DOI: 10.1002/smll.201600493] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/18/2016] [Indexed: 05/26/2023]
Abstract
Liposomes and nanoparticles that bind selectively to cell-surface receptors can target specific populations of cells. However, chemical conjugation of ligands to these particles is difficult to control, frequently limiting ligand uniformity and complexity. In contrast, the surfaces of living cells are decorated with highly uniform populations of sophisticated transmembrane proteins. Toward harnessing cellular capabilities, here it is demonstrated that plasma membrane vesicles (PMVs) derived from donor cells can display engineered transmembrane protein ligands that precisely target cells on the basis of receptor expression. These multifunctional targeting proteins incorporate (i) a protein ligand, (ii) an intrinsically disordered protein spacer to make the ligand sterically accessible, and (iii) a fluorescent protein domain that enables quantification of the ligand density on the PMV surface. PMVs that display targeting proteins with affinity for the epidermal growth factor receptor (EGFR) bind at increasing concentrations to breast cancer cells that express increasing levels of EGFR. Further, as an example of the generality of this approach, PMVs expressing a single-domain antibody against green fluorescence protein (eGFP) bind to cells expressing eGFP-tagged receptors with a selectivity of ≈50:1. The results demonstrate the versatility of PMVs as cell targeting systems, suggesting diverse applications from drug delivery to tissue engineering.
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Affiliation(s)
- Chi Zhao
- Department of Biomedical Engineering, Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX, 78712, USA
| | - David J Busch
- Department of Biomedical Engineering, Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX, 78712, USA
| | - Connor P Vershel
- Department of Biomedical Engineering, Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX, 78712, USA
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX, 78712, USA
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4
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Coban O, Zanetti-Dominguez LC, Matthews DR, Rolfe DJ, Weitsman G, Barber PR, Barbeau J, Devauges V, Kampmeier F, Winn M, Vojnovic B, Parker PJ, Lidke KA, Lidke DS, Ameer-Beg SM, Martin-Fernandez ML, Ng T. Effect of phosphorylation on EGFR dimer stability probed by single-molecule dynamics and FRET/FLIM. Biophys J 2015; 108:1013-26. [PMID: 25762314 PMCID: PMC4375452 DOI: 10.1016/j.bpj.2015.01.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 12/06/2014] [Accepted: 01/07/2015] [Indexed: 12/22/2022] Open
Abstract
Deregulation of epidermal growth factor receptor (EGFR) signaling has been correlated with the development of a variety of human carcinomas. EGF-induced receptor dimerization and consequent trans- auto-phosphorylation are among the earliest events in signal transduction. Binding of EGF is thought to induce a conformational change that consequently unfolds an ectodomain loop required for dimerization indirectly. It may also induce important allosteric changes in the cytoplasmic domain. Despite extensive knowledge on the physiological activation of EGFR, the effect of targeted therapies on receptor conformation is not known and this particular aspect of receptor function, which can potentially be influenced by drug treatment, may in part explain the heterogeneous clinical response among cancer patients. Here, we used Förster resonance energy transfer/fluorescence lifetime imaging microscopy (FRET/FLIM) combined with two-color single-molecule tracking to study the effect of ATP-competitive small molecule tyrosine kinase inhibitors (TKIs) and phosphatase-based manipulation of EGFR phosphorylation on live cells. The distribution of dimer on-times was fitted to a monoexponential to extract dimer off-rates (koff). Our data show that pretreatment with gefitinib (active conformation binder) stabilizes the EGFR ligand-bound homodimer. Overexpression of EGFR-specific DEP-1 phosphatase was also found to have a stabilizing effect on the homodimer. No significant difference in the koff of the dimer could be detected when an anti-EGFR antibody (425 Snap single-chain variable fragment) that allows for dimerization of ligand-bound receptors, but not phosphorylation, was used. These results suggest that both the conformation of the extracellular domain and phosphorylation status of the receptor are involved in modulating the stability of the dimer. The relative fractions of these two EGFR subpopulations (interacting versus free) were obtained by a fractional-intensity analysis of ensemble FRET/FLIM images. Our combined imaging approach showed that both the fraction and affinity (surrogate of conformation at a single-molecule level) increased after gefitinib pretreatment or DEP-1 phosphatase overexpression. Using an EGFR mutation (I706Q, V948R) that perturbs the ability of EGFR to dimerize intracellularly, we showed that a modest drug-induced increase in the fraction/stability of the EGFR homodimer may have a significant biological impact on the tumor cell's proliferation potential.
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Affiliation(s)
- Oana Coban
- Richard Dimbleby Department of Cancer Research, King's College London, London, UK; Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK.
| | - Laura C Zanetti-Dominguez
- Science and Technology Facilities Council, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, UK
| | - Daniel R Matthews
- Richard Dimbleby Department of Cancer Research, King's College London, London, UK; Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK
| | - Daniel J Rolfe
- Science and Technology Facilities Council, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, UK
| | - Gregory Weitsman
- Richard Dimbleby Department of Cancer Research, King's College London, London, UK; Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK
| | - Paul R Barber
- Gray Institute for Radiation Oncology & Biology, Department of Oncology, University of Oxford, Oxford, UK
| | - Jody Barbeau
- Richard Dimbleby Department of Cancer Research, King's College London, London, UK; Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK
| | - Viviane Devauges
- Richard Dimbleby Department of Cancer Research, King's College London, London, UK; Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK
| | - Florian Kampmeier
- Division of Imaging Sciences, King's College London, The Rayne Institute, St. Thomas Hospital, London, UK
| | - Martyn Winn
- Computational Science and Engineering Department, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, UK
| | - Borivoj Vojnovic
- Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK; Gray Institute for Radiation Oncology & Biology, Department of Oncology, University of Oxford, Oxford, UK
| | - Peter J Parker
- Division of Cancer Studies, King's College London, London, UK; Cancer Research UK, London Research Institute, London, UK
| | - Keith A Lidke
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico
| | - Diane S Lidke
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico; Cancer Research and Treatment Center, University of New Mexico School of Medicine, Albuquerque, New Mexico
| | - Simon M Ameer-Beg
- Richard Dimbleby Department of Cancer Research, King's College London, London, UK; Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK; Division of Cancer Studies, King's College London, London, UK
| | - Marisa L Martin-Fernandez
- Science and Technology Facilities Council, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, UK
| | - Tony Ng
- Richard Dimbleby Department of Cancer Research, King's College London, London, UK; Randall Division of Cellular and Molecular Biophysics, King's College London, London, UK; Division of Cancer Studies, King's College London, London, UK
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5
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Lee MK, Kim IH, Choi YH, Choi JW, Kim YM, Nam TJ. The proliferative effects of Pyropia yezoensis peptide on IEC-6 cells are mediated through the epidermal growth factor receptor signaling pathway. Int J Mol Med 2015; 35:909-14. [PMID: 25716690 PMCID: PMC4356455 DOI: 10.3892/ijmm.2015.2111] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/16/2015] [Indexed: 12/04/2022] Open
Abstract
For a number of years, seaweed has been used as a functional food in Asian countries, particularly in Korea, Japan and China. Pyropia yezoensis is a marine red alga that has potentially beneficial biological activities. In this study, we examined the mechanisms through which a Pyropia yezoensis peptide [PYP1 (1–20)] induces the proliferation of IEC-6 cells, a rat intestinal epithelial cell line, and the involvement of the epidermal growth factor receptor (EGFR) signaling pathway. First, cell viability assay revealed that PYP1 (1–20) induced cell proliferation in a concentration-dependent manner. Subsequently, we examined the mechanisms responsible for this induction of proliferation induced by PYP1 (1–20). EGFR is widely expressed in mammalian epithelial tissues, and the binding of this ligand affects a variety of cell physiological parameters, such as cell growth and proliferation. PYP1 (1–20) increased the expression of EGFR, Shc, growth factor receptor-bound protein 2 (Grb2) and son of sevenless (SOS). EGFR also induced the activation of the Ras signaling pathway through Raf, MEK and extracellular signal-regulated kinase (ERK) phosphorylation. In addition, cell cycle analysis revealed the expression of cell cycle-related proteins. The results demonstrated an increased number of cells in the G1 phase and an enhanced cell proliferation. In addition, the upregulation of cyclin D, cyclin E, Cdk2, Cdk4 and Cdk6 was observed accompanied by a decreased in p21 and p27 expression. These findings suggest that PYP1 (1–20) stimulates the proliferation of rat IEC-6 cells by activating the EGFR signaling pathway. Therefore, PYP1 (1–20) may be a potential source for the development of bio-functional foods which promotes the proliferation of intestinal epithelial cells.
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Affiliation(s)
- Min-Kyeong Lee
- Department of Food Science and Nutrition, Pukyong National University, Busan 608-737, Republic of Korea
| | - In-Hye Kim
- Institute of Fisheries Science, Pukyong National University, Busan 619-911, Republic of Korea
| | - Youn-Hee Choi
- Institute of Fisheries Science, Pukyong National University, Busan 619-911, Republic of Korea
| | - Jeong-Wook Choi
- Department of Food Science and Nutrition, Pukyong National University, Busan 608-737, Republic of Korea
| | - Young-Min Kim
- Institute of Fisheries Science, Pukyong National University, Busan 619-911, Republic of Korea
| | - Taek-Jeong Nam
- Department of Food Science and Nutrition, Pukyong National University, Busan 608-737, Republic of Korea
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6
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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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7
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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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8
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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: 36] [Impact Index Per Article: 3.3] [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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9
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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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10
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Jiang R, Lopez V, Kelleher SL, Lönnerdal B. Apo- and holo-lactoferrin are both internalized by lactoferrin receptor via clathrin-mediated endocytosis but differentially affect ERK-signaling and cell proliferation in Caco-2 cells. J Cell Physiol 2011; 226:3022-31. [PMID: 21935933 DOI: 10.1002/jcp.22650] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Lactoferrin (Lf) is a major iron-binding and multi-functional protein in exocrine fluids such as breast milk and mucosal secretions. The functions of Lf appear dependent upon the iron saturation of the Lf protein and are postulated to be mediated through Lf internalization by a Lf receptor (LfR). However, mechanisms by which LfR mediates Lf internalization in enterocytes are unknown. We now demonstrate that a LfR previously cloned from the small intestine mediates Lf endocytosis in a human enterocyte model (Caco-2 cells). LfR was detected at the plasma membrane by cell surface biotinylation; both apo-Lf and holo-Lf uptake were significantly inhibited in cells transfected with LfR siRNA. Treatments of hypertonic sucrose and clathrin siRNA and co-immunoprecipitation of LfR with clathrin adaptor AP2 indicate that LfR regulates Lf endocytosis via clathrin-mediated endocytosis. Although both iron-free Lf (apo-Lf) and iron-saturated Lf (holo-Lf) enter Caco-2 cells via a similar mechanism and no significant differences were observed in the binding and uptake of apo- and holo-Lf in Caco-2 cells, apo-Lf but not holo-Lf stimulates proliferation of Caco-2 cells. Interestingly, apo-Lf stimulated extracellular signal-regulated mitogen-activated protein kinase (ERK) cascade to a significantly greater extent than holo-Lf and the apo-Lf induced proliferation was significantly inhibited by an ERK cascade inhibitor (U0126) and clathrin siRNA. Taken together, our data suggest that LfR is a major pathway through which Lf is taken up by enterocytes, which occurs independently of iron saturation through clathrin-mediated endocytosis. The differential effects of apo- and holo-Lf are not due to differences in cellular internalization mechanisms.
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Affiliation(s)
- Rulan Jiang
- Department of Nutrition, University of California, Davis, California 95616, USA
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11
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Abstract
Biological research has always tremendously benefited from the development of key methodology. In fact, it was the advent of microscopy that shaped our understanding of cells as the fundamental units of life. Microscopic techniques are still central to the elucidation of biological units and processes, but equally important are methods that allow access to the dimension of time, to investigate the dynamics of molecular functions and interactions. Here, fluorescence spectroscopy with its sensitivity to access the single-molecule level, and its large temporal resolution, has been opening up fully new perspectives for cell biology. Here we summarize the key fluorescent techniques used to study cellular dynamics, with the focus on lipid and membrane systems.
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12
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Costa MN, Radhakrishnan K, Edwards JS. Monte Carlo simulations of plasma membrane corral-induced EGFR clustering. J Biotechnol 2010; 151:261-70. [PMID: 21167222 DOI: 10.1016/j.jbiotec.2010.12.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 11/30/2010] [Accepted: 12/04/2010] [Indexed: 11/26/2022]
Abstract
Experimental evidence suggests that the cell membrane is a highly organized structure that is compartmentalized by the underlying membrane cytoskeleton (MSK). The interaction between the cell membrane and the cytoskeleton led to the "picket-fence" model, which was proposed to explain certain aspects of membrane compartmentalization. This model assumes that the MSK hinders and confines the motion of receptors and lipids to compartments in the membrane. However, the impact of the MSK on receptor clustering, aggregation, and downstream signaling remains unclear. For example, some evidence suggests that the MSK enhances dimerization, while other evidence suggests decreased dimerization and signaling. Herein, we use computational Monte Carlo simulations to examine the effects of MSK density and receptor concentration on receptor dimerization and clustering. Preliminary results suggest that the MSK may have the potential to induce receptor clustering, which is a function of both picket-fence density and receptor concentration.
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Affiliation(s)
- Michelle N Costa
- Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, United States
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13
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Chen J, Irudayaraj J. Fluorescence Lifetime Cross Correlation Spectroscopy Resolves EGFR and Antagonist Interaction in Live Cells. Anal Chem 2010; 82:6415-21. [PMID: 20586411 DOI: 10.1021/ac101236t] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jiji Chen
- Birck Nanotechnology & Bindley Bioscience Center, Department of Agricultural & Biological Engineering, Purdue University, West Lafayette, Indiana 47906
| | - Joseph Irudayaraj
- Birck Nanotechnology & Bindley Bioscience Center, Department of Agricultural & Biological Engineering, Purdue University, West Lafayette, Indiana 47906
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14
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Surface analysis of membrane dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:766-76. [DOI: 10.1016/j.bbamem.2009.09.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 09/18/2009] [Accepted: 09/20/2009] [Indexed: 11/18/2022]
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15
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Kawashima N, Nakayama K, Itoh K, Itoh T, Ishikawa M, Biju V. Reversible dimerization of EGFR revealed by single-molecule fluorescence imaging using quantum dots. Chemistry 2010; 16:1186-92. [PMID: 20024999 DOI: 10.1002/chem.200902963] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The current work explores intermolecular interactions involved in the lateral propagation of cell-signaling by epidermal growth factor receptors (EGFRs). Activation of EGFRs by binding an EGF ligand in the extracellular domain of the EGFR and subsequent dimerization of the EGFR initiates cell-signaling. We investigated interactions between EGFRs in living cells by using single-molecule microscopy, Förster resonance energy transfer (FRET), and atomic force microscopy. By analyzing time-correlated intensity and propagation trajectories of quantum dot (QD)-labeled EGFR single molecules, we found that signaling dimers of EGFR [(EGF-EGFR)(2)] are continuously formed in cell membrane through reversible association of heterodimers [EGF(EGFR)(2)]. Also, we found that the lateral propagation of EGFR activation takes place through transient association of a heterodimer with predimers [(EGFR)(2)]. We varified the transient association between activated EGFR and predimers using FRET from QD-labeled heterodimers to Cy5-labeled predimers and correlated topography and fluorescence imaging. Without extended single-molecule fluorescence imaging and by using bio-conjugated QDs, reversible receptor dimerization in the lateral activation of EGFR remained obscured.
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Affiliation(s)
- Nagako Kawashima
- Health Technology Research Center, National Institute of Advanced Industrial, Science and Technology (AIST), 2217-14 Hayashi-Cho, Takamatsu, Kagawa 761-0395, Japan
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Trang SH, Joyner DE, Damron TA, Aboulafia AJ, Randall RL. Potential for functional redundancy in EGF and TGFalpha signaling in desmoid cells: a cDNA microarray analysis. Growth Factors 2010; 28:10-23. [PMID: 20092031 DOI: 10.3109/08977190903299387] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Genes that replace or duplicate the function of other genes are considered functionally redundant. In this cDNA microarray study, using an Agilent microarray platform and GeneSifter analysis software, we evaluated (1) the degree of downstream transcriptional redundancy and (2) the level of genetic uniqueness apparent in desmoid tumor cells stimulated in vitro for 3 h or for 24 h with 100 ng/ml of exogenous recombinant human EGF (rhEGF) or with recombinant human transforming growth factor alpha (rhTGFalpha). Our intent was to identify genes costimulated, or genes unique to, desmoid cells stimulated in vitro with rhEGF and rhTGFalpha. This experimental approach demonstrated a 55% transcriptional redundancy in the number of desmoid genes significantly upregulated or downregulated following 3 h of stimulation with rhEGF or with rhTGFalpha, and a 65% transcriptional redundancy following 24 h of growth factor stimulation. Approximately 150 genes costimulated by rhEGF and rhTGFalpha were identified. This study suggests that EGF and TGFalpha retain some level of functional redundancy, possibly resulting from their divergence from a common ancestral gene.
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Affiliation(s)
- Sylvia H Trang
- SARC Laboratory, Sarcoma Services, Department of Orthopaedics and Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
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Chen J, Irudayaraj J. Quantitative investigation of compartmentalized dynamics of ErbB2 targeting gold nanorods in live cells by single molecule spectroscopy. ACS NANO 2009; 3:4071-9. [PMID: 19891423 DOI: 10.1021/nn900743v] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Understanding the diffusion dynamics and receptor uptake mechanism of nanoparticles in cancer cells is crucial to the rational design of multifunctional nanoprobes for targeting and delivery. In this report, for the first time, we quantify the localization and evaluate the diffusion times of Herceptin-conjugated gold nanorods (H-GNRs) in different cell organelles by fluorescence correlation spectroscopy (FCS) and examine the endocytic diffusion of H-GNRs in live ErbB2 overexpressing SK-BR-3 cells. First, by colocalizing H-GNRs in different cellular organelles depicted by the respective markers, we demonstrate that H-GNRs colocalize with the endosome and lysosome but not with the Golgi apparatus. Our study shows that Herceptin-conjugated GNRs have similar intracellular localization characteristics as Herceptin-ErbB2 complex, with a higher concentration found in the endosome (72 +/- 20.6 nM) than lysosome (9.4 +/- 4.2 nM) after internalization. The demonstrated approach and findings not only lay the foundations for a quantitative understanding of the fate of nanoparticle-based targeting but also provide new insights into the rational design of nanoparticle delivery systems for effective treatment.
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Affiliation(s)
- Jiji Chen
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
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Abulrob A, Lu Z, Baumann E, Vobornik D, Taylor R, Stanimirovic D, Johnston LJ. Nanoscale imaging of epidermal growth factor receptor clustering: effects of inhibitors. J Biol Chem 2009; 285:3145-56. [PMID: 19959837 DOI: 10.1074/jbc.m109.073338] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The development of some solid tumors is associated with overexpression of the epidermal growth factor receptor (EGFR) and often correlates with poor prognosis. Near field scanning optical microscopy, a technique with subdiffraction-limited optical resolution, was used to examine the influence of two inhibitors (the chimeric 225 antibody and tyrosine phosphorylation inhibitor AG1478) on the nanoscale clustering of EGFR in HeLa cells. The EGFR is organized in small clusters, average diameter of 150 nm, on the plasma membrane for both control and EGF-treated cells. The numbers of receptors in individual clusters vary from as few as one or two proteins to greater than 100. Both inhibitors yield an increased cluster density and an increase in the fraction of clusters with smaller diameters and fewer receptors. Exposure to AG1478 also decreases the fraction of EGFR that colocalizes with both rafts and caveolae. EGF stimulation results in a significant loss of the full-length EGFR from the plasma membrane with the concomitant appearance of low molecular mass proteolytic products. By contrast, AG1478 reduces the level of EGFR degradation. Changes in receptor clustering provide one mechanism for regulating EGFR signaling and are relevant to the design of strategies for therapeutic interventions based on modulating EGFR signaling.
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Affiliation(s)
- Abedelnasser Abulrob
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R5, Canada.
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Single-molecule imaging reveals transforming growth factor-beta-induced type II receptor dimerization. Proc Natl Acad Sci U S A 2009; 106:15679-83. [PMID: 19720988 DOI: 10.1073/pnas.0908279106] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Transforming growth factor-beta (TGF-beta) elicits its signals through two transmembrane serine/threonine kinase receptors, type II (TbetaRII) and type I receptors. It is generally believed that the initial receptor dimerization is an essential event for receptor activation. However, previous studies suggested that TGF-beta signals by binding to the preexisting TbetaRII homodimer. Here, using single molecule microscopy to image green fluorescent protein (GFP)-labeled TbetaRII on the living cell surface, we demonstrated that the receptor could exist as monomers at the low expression level in resting cells and dimerize upon TGF-beta stimulation. This work reveals a model in which the activation of serine-threonine kinase receptors is also accomplished via dimerization of monomers, suggesting that receptor dimerization is a general mechanism for ligand-induced receptor activation.
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