1
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Bernoff AJ, Jilkine A, Navarro Hernández A, Lindsay AE. Single-cell directional sensing from just a few receptor binding events. Biophys J 2023; 122:3108-3116. [PMID: 37355773 PMCID: PMC10432224 DOI: 10.1016/j.bpj.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/08/2023] [Accepted: 06/20/2023] [Indexed: 06/26/2023] Open
Abstract
Identifying the directionality of signaling sources from noisy input to membrane receptors is an essential task performed by many cell types. A variety of models have been proposed to explain directional sensing in cells. However, many of these require significant computational and memory capacities for the cell. We propose and analyze a simple mechanism in which a cell adopts the direction associated with the first few membrane binding events. This model yields an accurate angular estimate to the source long before steady state is reached in biologically relevant scenarios. Our proposed mechanism allows for reliable estimates of the directionality of external signals using temporal information and assumes minimal computational capacities of the cell.
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Affiliation(s)
- Andrew J Bernoff
- Department of Mathematics, Harvey Mudd College, Claremont, California
| | - Alexandra Jilkine
- Department of Applied & Computational Mathematics & Statistics, University of Notre Dame, South Bend, Indiana
| | - Adrián Navarro Hernández
- Department of Applied & Computational Mathematics & Statistics, University of Notre Dame, South Bend, Indiana
| | - Alan E Lindsay
- Department of Applied & Computational Mathematics & Statistics, University of Notre Dame, South Bend, Indiana.
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2
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Li X, Shim S, Hardin KR, Vanaja KG, Song H, Levchenko A, Ming GL, Zheng JQ. Signal amplification in growth cone gradient sensing by a double negative feedback loop among PTEN, PI(3,4,5)P 3 and actomyosin. Mol Cell Neurosci 2022; 123:103772. [PMID: 36055521 PMCID: PMC9856701 DOI: 10.1016/j.mcn.2022.103772] [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: 06/01/2022] [Revised: 08/23/2022] [Accepted: 08/26/2022] [Indexed: 01/24/2023] Open
Abstract
Axon guidance during neural wiring involves a series of precisely controlled chemotactic events by the motile axonal tip, the growth cone. A fundamental question is how neuronal growth cones make directional decisions in response to extremely shallow gradients of guidance cues with exquisite sensitivity. Here we report that nerve growth cones possess a signal amplification mechanism during gradient sensing process. In neuronal growth cones of Xenopus spinal neurons, phosphatidylinositol-3,4,5-trisphosphate (PIP3), an important signaling molecule in chemotaxis, was actively recruited to the up-gradient side in response to an external gradient of brain-derived neurotrophic factor (BDNF), resulting in an intracellular gradient with approximate 30-fold amplification of the input. Furthermore, a reverse gradient of phosphatase and tensin homolog (PTEN) was induced by BDNF within the growth cone and the increased PTEN activity at the down-gradient side is required for the amplification of PIP3 signals. Mechanistically, the establishment of both positive PIP3 and reverse PTEN gradients depends on the filamentous actin network. Together with computational modeling, our results revealed a double negative feedback loop among PTEN, PIP3 and actomyosin for signal amplification, which is essential for gradient sensing of neuronal growth cones in response to diffusible cues.
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Affiliation(s)
- Xiong Li
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA
| | - Sangwoo Shim
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA; Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
| | - Katherine R Hardin
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
| | - Kiran G Vanaja
- Department of Biomedical Engineering and Yale Systems Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Hongjun Song
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Andre Levchenko
- Department of Biomedical Engineering and Yale Systems Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Guo-Li Ming
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, 733 N. Broadway, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
| | - James Q Zheng
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA.
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3
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Zarrouki F, Goutal S, Vacca O, Garcia L, Tournier N, Goyenvalle A, Vaillend C. Abnormal Expression of Synaptic and Extrasynaptic GABAA Receptor Subunits in the Dystrophin-Deficient mdx Mouse. Int J Mol Sci 2022; 23:ijms232012617. [PMID: 36293496 PMCID: PMC9604073 DOI: 10.3390/ijms232012617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/21/2022] [Accepted: 10/11/2022] [Indexed: 11/17/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a neurodevelopmental disorder primarily caused by the loss of the full-length Dp427 dystrophin in both muscle and brain. The basis of the central comorbidities in DMD is unclear. Brain dystrophin plays a role in the clustering of central gamma-aminobutyric acid A receptors (GABAARs), and its loss in the mdx mouse alters the clustering of some synaptic subunits in central inhibitory synapses. However, the diversity of GABAergic alterations in this model is still fragmentary. In this study, the analysis of in vivo PET imaging of a benzodiazepine-binding site radioligand revealed that the global density of central GABAARs is unaffected in mdx compared with WT mice. In contrast, semi-quantitative immunoblots and immunofluorescence confocal imaging in tissue sections revealed complex and differential patterns of alterations of the expression levels and/or clustered distribution of a variety of synaptic and extrasynaptic GABAAR subunits in the hippocampus, cerebellum, cortex, and spinal cord. Hence, dystrophin loss not only affects the stabilization of synaptic GABAARs but also influences the subunit composition of GABAARs subtypes at both synaptic and extrasynaptic sites. This study provides new molecular outcome measures and new routes to evaluate the impact of treatments aimed at compensating alterations of the nervous system in DMD.
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Affiliation(s)
- Faouzi Zarrouki
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, 91400 Saclay, France
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France
| | - Sébastien Goutal
- Université Paris-Saclay, INSERM, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Service Hospitalier Frédéric Joliot, 91401 Orsay, France
| | - Ophélie Vacca
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France
| | - Luis Garcia
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France
| | - Nicolas Tournier
- Université Paris-Saclay, INSERM, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Service Hospitalier Frédéric Joliot, 91401 Orsay, France
| | - Aurélie Goyenvalle
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, 78000 Versailles, France
| | - Cyrille Vaillend
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, 91400 Saclay, France
- Correspondence:
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4
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Dobramysl U, Holcman D. Computational methods and diffusion theory in triangulation sensing to model neuronal navigation. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 85:104601. [PMID: 36075196 DOI: 10.1088/1361-6633/ac906b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 09/08/2022] [Indexed: 06/15/2023]
Abstract
Computational methods are now recognized as powerful and complementary approaches in various applied sciences such as biology. These computing methods are used to explore the gap between scales such as the one between molecular and cellular. Here we present recent progress in the development of computational approaches involving diffusion modeling, asymptotic analysis of the model partial differential equations, hybrid methods and simulations in the generic context of cell sensing and guidance via external gradients. Specifically, we highlight the reconstruction of the location of a point source in two and three dimensions from the steady-state diffusion fluxes arriving to narrow windows located on the cell. We discuss cases in which these windows are located on the boundary of a two-dimensional plane or three-dimensional half-space, on a disk in free space or inside a two-dimensional corridor, or a ball in three dimensions. The basis of this computational approach is explicit solutions of the Neumann-Green's function for the mentioned geometry. This analysis can be used to design hybrid simulations where Brownian paths are generated only in small regions in which the local spatial organization is relevant. Particle trajectories outside of this region are only implicitly treated by generating exit points at the boundary of this domain of interest. This greatly accelerates the simulation time by avoiding the explicit computation of Brownian paths in an infinite domain and serves to generate statistics, without following all trajectories at the same time, a process that can become numerically expensive quickly. Moreover, these computational approaches are used to reconstruct a point source and estimating the uncertainty in the source reconstruction due to an additive noise perturbation present in the fluxes. We also discuss the influence of various window configurations (cluster vs uniform distributions) on recovering the source position. Finally, the applications in developmental biology are formulated into computational principles that could underly neuronal navigation in the brain.
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Affiliation(s)
- Ulrich Dobramysl
- Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, United Kingdom
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
| | - David Holcman
- Group of Data Modeling and Computational Biology, IBENS-PSL Ecole Normale Superieure, Paris, France
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5
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Wang ZJ, Thomson M. Localization of signaling receptors maximizes cellular information acquisition in spatially structured natural environments. Cell Syst 2022; 13:530-546.e12. [PMID: 35679857 DOI: 10.1016/j.cels.2022.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/08/2022] [Accepted: 05/12/2022] [Indexed: 01/25/2023]
Abstract
Cells in natural environments, such as tissue or soil, sense and respond to extracellular ligands with intricately structured and non-monotonic spatial distributions, sculpted by processes such as fluid flow and substrate adhesion. In this work, we show that spatial sensing and navigation can be optimized by adapting the spatial organization of signaling pathways to the spatial structure of the environment. We develop an information-theoretic framework for computing the optimal spatial organization of a sensing system for a given signaling environment. We find that receptor localization previously observed in cells maximizes information acquisition in simulated natural contexts, including tissue and soil. Specifically, information acquisition is maximized when receptors form localized patches at regions of maximal ligand concentration. Receptor localization extends naturally to produce a dynamic protocol for continuously redistributing signaling receptors, which when implemented using simple feedback, boosts cell navigation efficiency by 30-fold.
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Affiliation(s)
- Zitong Jerry Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Matt Thomson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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6
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Zavalin K, Hassan A, Fu C, Delpire E, Lagrange AH. Loss of KCC2 in GABAergic Neurons Causes Seizures and an Imbalance of Cortical Interneurons. Front Mol Neurosci 2022; 15:826427. [PMID: 35370549 PMCID: PMC8966887 DOI: 10.3389/fnmol.2022.826427] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/21/2022] [Indexed: 11/24/2022] Open
Abstract
K-Cl transporter KCC2 is an important regulator of neuronal development and neuronal function at maturity. Through its canonical transporter role, KCC2 maintains inhibitory responses mediated by γ-aminobutyric acid (GABA) type A receptors. During development, late onset of KCC2 transporter activity defines the period when depolarizing GABAergic signals promote a wealth of developmental processes. In addition to its transporter function, KCC2 directly interacts with a number of proteins to regulate dendritic spine formation, cell survival, synaptic plasticity, neuronal excitability, and other processes. Either overexpression or loss of KCC2 can lead to abnormal circuit formation, seizures, or even perinatal death. GABA has been reported to be especially important for driving migration and development of cortical interneurons (IN), and we hypothesized that properly timed onset of KCC2 expression is vital to this process. To test this hypothesis, we created a mouse with conditional knockout of KCC2 in Dlx5-lineage neurons (Dlx5 KCC2 cKO), which targets INs and other post-mitotic GABAergic neurons in the forebrain starting during embryonic development. While KCC2 was first expressed in the INs of layer 5 cortex, perinatal IN migrations and laminar localization appeared to be unaffected by the loss of KCC2. Nonetheless, the mice had early seizures, failure to thrive, and premature death in the second and third weeks of life. At this age, we found an underlying change in IN distribution, including an excess number of somatostatin neurons in layer 5 and a decrease in parvalbumin-expressing neurons in layer 2/3 and layer 6. Our research suggests that while KCC2 expression may not be entirely necessary for early IN migration, loss of KCC2 causes an imbalance in cortical interneuron subtypes, seizures, and early death. More work will be needed to define the specific cellular basis for these findings, including whether they are due to abnormal circuit formation versus the sequela of defective IN inhibition.
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Affiliation(s)
- Kirill Zavalin
- Department of Neurology, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Anjana Hassan
- Department of Neurology, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Cary Fu
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Eric Delpire
- Department of Anesthesiology, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Andre H. Lagrange
- Department of Neurology, School of Medicine, Vanderbilt University, Nashville, TN, United States,Department of Neurology, Tennessee Valley Healthcare – Veterans Affairs (TVH VA), Medical Center, Nashville, TN, United States,*Correspondence: Andre H. Lagrange,
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7
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Wang Y, Jing W, Tao N, Wang H. Probing Single-Molecule Binding Event by the Dynamic Counting and Mapping of Individual Nanoparticles. ACS Sens 2021; 6:523-529. [PMID: 33284583 DOI: 10.1021/acssensors.0c02184] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Measuring binding processes at the single-molecule level underpin significant functions in understanding biological events. Single-nanoparticle imaging techniques are providing a new concept for mapping the heterogeneous behaviors and characterizations of individual dynamics such as molecule-molecule interactions. Here, we develop the optical imaging techniques for directly counting and monitoring the binding and motion events of single nanoparticles linked to the substrate via the specific and reversible interactions between biomolecules. The one-step digital immunoassay realizes the biomolecular detection based on dynamic counting of the single nanoparticle binding event to substrate with the bright-field imaging. The detection limit achieves 8.4 pg/mL for procalcitonin with detection time of 14 min. Meanwhile, we map the accurate trajectory of single nanoparticle switching between different target molecules among the x-y plane with the total internal reflection imaging technique, which reveals the spatial coordinates of single target molecules on the substrate surface with high spatial and temporal resolutions.
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Affiliation(s)
- Yi Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Wenwen Jing
- Department of Medical Microbiology and Parasitology, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Nongjian Tao
- Biodesign Center for Bioelectronics and Biosensors, and School of Electrical, Energy and Computer Engineering, Arizona State University, Tempe, Arizona 85287, United States
| | - Hui Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
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8
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Dobramysl U, Holcman D. Triangulation Sensing to Determine the Gradient Source from Diffusing Particles to Small Cell Receptors. PHYSICAL REVIEW LETTERS 2020; 125:148102. [PMID: 33064548 DOI: 10.1103/physrevlett.125.148102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
How does a cell locate the source of molecular guidance cues from within a concentration gradient? We present a computational approach to recover the source from the absorbed fluxes at narrow receptor windows located on the surface of the cell. In the limit of fast binding, we solve the steady-state diffusion equation using an asymptotic approach and hybrid stochastic-analytical simulations. We show that the sensitivity to the gradient direction decays too rapidly to enable long-distance sensing. We illustrate how this constraint can be alleviated when triangulating the source with an increasing number of receptor windows and quantify the susceptibility of this process to flux perturbations.
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Affiliation(s)
- Ulrich Dobramysl
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom
- Wellcome Trust / CRUK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, United Kingdom
| | - David Holcman
- Group Computational Biology and Data modeling, IBENS, Ecole Normale Superieure - PSL, Paris, France
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9
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Lawley SD, Lindsay AE, Miles CE. Receptor Organization Determines the Limits of Single-Cell Source Location Detection. PHYSICAL REVIEW LETTERS 2020; 125:018102. [PMID: 32678664 DOI: 10.1103/physrevlett.125.018102] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
Many types of cells require the ability to pinpoint the location of an external stimulus from the arrival of diffusing signaling molecules at cell-surface receptors. How does the organization (number and spatial configuration) of these receptors shape the limit of a cell's ability to infer the source location? In the idealized scenario of a spherical cell, we apply asymptotic analysis to compute splitting probabilities between individual receptors and formulate an information-theoretic framework to quantify the role of receptor organization. Clustered configurations of receptors provide an advantage in detecting sources aligned with the clusters, suggesting a possible multiscale mechanism for single-cell source inference.
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Affiliation(s)
- Sean D Lawley
- Department of Mathematics, University of Utah, Salt Lake City, Utah 84112, USA
| | - Alan E Lindsay
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, South Bend, Indiana 46556, USA
| | - Christopher E Miles
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10005, USA
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10
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Thal LB, Mann VR, Sprinzen D, McBride JR, Reid KR, Tomlinson ID, McMahon DG, Cohen BE, Rosenthal SJ. Ligand-conjugated quantum dots for fast sub-diffraction protein tracking in acute brain slices. Biomater Sci 2020; 8:837-845. [PMID: 31790090 PMCID: PMC7002256 DOI: 10.1039/c9bm01629e] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Semiconductor quantum dots (QDs) have demonstrated utility in long-term single particle tracking of membrane proteins in live cells in culture. To extend the superior optical properties of QDs to more physiologically relevant cell platforms, such as acute brain slices, we examine the photophysics of compact ligand-conjugated CdSe/CdS QDs using both ensemble and single particle analysis in brain tissue media. We find that symmetric core passivation is critical for both photostability in oxygenated media and for prolonged single particle imaging in brain slices. We then demonstrate the utility of these QDs by imaging single dopamine transporters in acute brain slices, achieving 20 nm localization precision at 10 Hz frame rates. These findings detail design requirements needed for new QD probes in complex living environments, and open the door to physiologically relevant studies that capture the utility of QD probes in acute brain slices.
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Affiliation(s)
- Lucas B Thal
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA.
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11
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Watson JL, Stangherlin A, Derivery E. Quantitative Chemical Delivery of Quantum Dots into the Cytosol of Cells. Methods Mol Biol 2020; 2135:179-197. [PMID: 32246335 DOI: 10.1007/978-1-0716-0463-2_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The ability to image single molecules in living cells has been impaired by the absence of bright, photostable fluorophores. Quantum dots (QDs) offer an attractive solution to this problem due to their exceptional photostability and brightness. Here, we describe in detail a protocol to chemically deliver functionalized QDs into the cytosol of living cells, based on cell-penetrating poly(disulfide)s (CPDs). This protocol is highly efficient and delivers hundreds of QDs per cell after incubation of cells with functionalized QDs at nanomolar concentrations. We also detail a pipeline for automated detection and tracking of diffusive QDs in living cells, which may provide a useful means to study the biophysical properties of the cytosol and their dynamics. Last, we describe a protocol for conjugating streptavidin fusion proteins to QDs, in order to permit the codelivery of QDs with functional proteins of interest into cells. The protocol has been successfully applied to a broad range of different cell types, thus offering a flexible and generalizable means to image single molecules in living cells.
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12
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Ahmed S, Nakaji-Hirabayashi T, Rajan R, Zhao D, Matsumura K. Cytosolic delivery of quantum dots mediated by freezing and hydrophobic polyampholytes in RAW 264.7 cells. J Mater Chem B 2019; 7:7387-7395. [PMID: 31697291 DOI: 10.1039/c9tb01184f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Quantum dots (QDs) can be delivered efficiently inside macrophages using a freeze-concentration approach. In this study, we introduced a new, facile, high concentration-based freezing technology of low toxicity. We also developed QD-conjugated new hydrophobic polyampholytes using poly-l-lysine (PLL), a naturally derived polymer, which showed sustained biocompatibility, stability over one week, and enhanced intracellular delivery. When freeze-concentration was applied, the QD-encapsulated hydrophobic polyampholytes showed a higher tendency to adsorb onto the cell membrane than the non-frozen molecules. Interestingly, we observed that the efficacy of adsorption of QDs on RAW 264.7 macrophages was higher than that on fibroblasts. Furthermore, the intracellular delivery of QDs using hydrophobic polyampholytes was higher than those of PLL and QDs. In vitro studies revealed the efficient endosomal escape of QDs in the presence of hydrophobic polyampholytes and freeze-concentration. Collectively, these observations indicated that the promising combination of freeze-concentration and hydrophobic polyampholytes may act as an effective and versatile strategy for the intracellular delivery of QDs, which can be used for biological diagnosis and therapeutic applications.
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Affiliation(s)
- Sana Ahmed
- School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa 923-1292, Japan. and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Tadashi Nakaji-Hirabayashi
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan and Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Robin Rajan
- School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa 923-1292, Japan.
| | - Dandan Zhao
- School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa 923-1292, Japan.
| | - Kazuaki Matsumura
- School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa 923-1292, Japan.
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13
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Johnson A, Nasser TIN, Spencer GE. Inhibition of Rho GTPases in Invertebrate Growth Cones Induces a Switch in Responsiveness to Retinoic Acid. Biomolecules 2019; 9:biom9090460. [PMID: 31500289 PMCID: PMC6769630 DOI: 10.3390/biom9090460] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/29/2019] [Accepted: 09/04/2019] [Indexed: 12/24/2022] Open
Abstract
During development, growth cones are essential for axon pathfinding by sensing numerous guidance cues in their environment. Retinoic acid, the metabolite of vitamin A, is important for neurite outgrowth during vertebrate development, but may also play a role in axon guidance, though little is known of the cellular mechanisms involved. Our previous studies showed that retinoid-induced growth cone turning of invertebrate motorneurons requires local protein synthesis and calcium influx. However, the signalling pathways that link calcium influx to cytoskeletal dynamics involved in retinoid-mediated growth cone turning are not currently known. The Rho GTPases, Cdc42 and Rac, are known regulators of the growth cone cytoskeleton. Here, we demonstrated that inhibition of Cdc42 or Rac not only prevented growth cone turning toward retinoic acid but could also induce a switch in growth cone responsiveness to chemorepulsion or growth cone collapse. However, the effects of Cdc42 or Rac inhibition on growth cone responsiveness differed, depending on whether the turning was induced by the all-trans or 9-cis retinoid isomer. The effects also differed depending on whether the growth cones maintained communication with the cell body. These data strongly suggest that Cdc42 and Rac are downstream effectors of retinoic acid during growth cone guidance.
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Affiliation(s)
- Alysha Johnson
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St Catharines, ON L2S 3A1, Canada
| | - Tamara I N Nasser
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St Catharines, ON L2S 3A1, Canada
| | - Gaynor E Spencer
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St Catharines, ON L2S 3A1, Canada.
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14
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Thal LB, Tomlinson ID, Quinlan MA, Kovtun O, Blakely RD, Rosenthal SJ. Single Quantum Dot Imaging Reveals PKCβ-Dependent Alterations in Membrane Diffusion and Clustering of an Attention-Deficit Hyperactivity Disorder/Autism/Bipolar Disorder-Associated Dopamine Transporter Variant. ACS Chem Neurosci 2019; 10:460-471. [PMID: 30153408 PMCID: PMC6411462 DOI: 10.1021/acschemneuro.8b00350] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The dopamine transporter (DAT) is a transmembrane protein that terminates dopamine signaling in the brain by driving rapid dopamine reuptake into presynaptic nerve terminals. Several lines of evidence indicate that DAT dysfunction is linked to neuropsychiatric disorders such as attention-deficit/hyperactivity disorder (ADHD), bipolar disorder (BPD), and autism spectrum disorder (ASD). Indeed, individuals with these disorders have been found to express the rare, functional DAT coding variant Val559, which confers anomalous dopamine efflux (ADE) in vitro and in vivo. To elucidate the impact of the DAT Val559 variant on membrane diffusion dynamics, we implemented our antagonist-conjugated quantum dot (QD) labeling approach to monitor the lateral mobility of single particle-labeled transporters in transfected HEK-293 and SK-N-MC cells. Our results demonstrate significantly higher diffusion coefficients of DAT Val559 compared to those of DAT Ala559, effects likely determined by elevated N-terminal transporter phosphorylation. We also provide pharmacological evidence that PKCβ-mediated signaling supports enhanced DAT Val559 membrane diffusion rates. Additionally, our results are complimented with diffusion rates of phosphomimicked and phosphorylation-occluded DAT variants. Furthermore, we show DAT Val559 has a lower propensity for membrane clustering, which may be caused by a mutation-derived shift out of membrane microdomains leading to faster lateral membrane diffusion rates. These findings further demonstrate a functional impact of DAT Val559 and suggest that changes in transporter localization and lateral mobility may sustain ADE and contribute to alterations in dopamine signaling underlying multiple neuropsychiatric disorders.
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15
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Taylor RD, Heine M, Emptage NJ, Andreae LC. Neuronal Receptors Display Cytoskeleton-Independent Directed Motion on the Plasma Membrane. iScience 2018; 10:234-244. [PMID: 30557785 PMCID: PMC6297241 DOI: 10.1016/j.isci.2018.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/25/2018] [Accepted: 11/30/2018] [Indexed: 11/19/2022] Open
Abstract
Directed transport of transmembrane proteins is generally believed to occur via intracellular transport vesicles. However, using single-particle tracking in rat hippocampal neurons with a pH-sensitive quantum dot probe that specifically reports surface movement of receptors, we have identified a subpopulation of neuronal EphB2 receptors that exhibit directed motion between synapses within the plasma membrane itself. This receptor movement occurs independently of the cytoskeleton but is dependent on cholesterol and is regulated by neuronal activity.
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Affiliation(s)
- Ruth D Taylor
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | - Martin Heine
- Leibniz Institute of Neurobiology, Research Group Molecular Physiology, Brenneckestrasse 6, Magdeburg 39118, Germany; Otto von Guericke University Magdeburg, Center for Behavioral Brain Sciences (CBBS), Universitätsplatz 2, Magdeburg 39106, Germany; Johannes Gutenberg University Mainz, Institute for Developmental Biology and Neurobiology, AG Funktional Neurobiology, Hanns-Dieter-Hüsch Weg 15, Mainz 55128, Germany
| | - Nigel J Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Laura C Andreae
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK.
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16
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Ciocanel MV, Sandstede B, Jeschonek SP, Mowry KL. Modeling microtubule-based transport and anchoring of mRNA. SIAM JOURNAL ON APPLIED DYNAMICAL SYSTEMS 2018; 17:2855-2881. [PMID: 34135697 PMCID: PMC8205424 DOI: 10.1137/18m1186083] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Localization of messenger RNA (mRNA) at the vegetal cortex plays an important role in the early development of Xenopus laevis oocytes. While it is known that molecular motors are responsible for the transport of mRNA cargo along microtubules to the cortex, the mechanisms of localization remain unclear. We model cargo transport along microtubules using partial differential equations with spatially-dependent rates. A theoretical analysis of reduced versions of our model predicts effective velocity and diffusion rates for the cargo and shows that randomness of microtubule networks enhances effective transport. A more complex model using parameters estimated from fluorescence microscopy data reproduces the spatial and timescales of mRNA localization observed in Xenopus oocytes, corroborates experimental hypotheses that anchoring may be necessary to achieve complete localization, and shows that anchoring of mRNA complexes actively transported to the cortex is most effective in achieving robust accumulation at the cortex.
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Affiliation(s)
| | - Björn Sandstede
- Division of Applied Mathematics, Brown University, Providence, RI
| | - Samantha P Jeschonek
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI
| | - Kimberly L Mowry
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI
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17
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Nagel M, Winklbauer R. PDGF-A suppresses contact inhibition during directional collective cell migration. Development 2018; 145:dev.162651. [PMID: 29884673 DOI: 10.1242/dev.162651] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 05/25/2018] [Indexed: 12/15/2022]
Abstract
The leading-edge mesendoderm (LEM) of the Xenopus gastrula moves as an aggregate by collective migration. However, LEM cells on fibronectin in vitro show contact inhibition of locomotion by quickly retracting lamellipodia upon mutual contact. We found that a fibronectin-integrin-syndecan module acts between p21-activated kinase 1 upstream and ephrin B1 downstream to promote the contact-induced collapse of lamellipodia. To function in this module, fibronectin has to be present as puncta on the surface of LEM cells. To overcome contact inhibition in LEM cell aggregates, PDGF-A deposited in the endogenous substratum of LEM migration blocks the fibronectin-integrin-syndecan module at the integrin level. This stabilizes lamellipodia preferentially in the direction of normal LEM movement and supports cell orientation and the directional migration of the coherent LEM cell mass.
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Affiliation(s)
- Martina Nagel
- University of Toronto, Department of Cell and Systems Biology, 25 Harbord Street, Toronto M5S 3G5, ON, Canada
| | - Rudolf Winklbauer
- University of Toronto, Department of Cell and Systems Biology, 25 Harbord Street, Toronto M5S 3G5, ON, Canada
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18
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Roles of Gag-RNA interactions in HIV-1 virus assembly deciphered by single-molecule localization microscopy. Proc Natl Acad Sci U S A 2018; 115:6721-6726. [PMID: 29891653 PMCID: PMC6042153 DOI: 10.1073/pnas.1805728115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During HIV-1 assembly, the retroviral structural protein Gag forms an immature capsid, containing thousands of Gag molecules, at the plasma membrane (PM). Interactions between Gag nucleocapsid (NC) and viral RNA (vRNA) are thought to drive assembly, but the exact roles of these interactions have remained poorly understood. Since previous studies have shown that Gag dimer- or trimer-forming mutants (GagZiL) lacking an NC domain can form immature capsids independent of RNA binding, it is often hypothesized that vRNA drives Gag assembly by inducing Gag to form low-ordered multimers, but is dispensable for subsequent assembly. In this study, we examined the role of vRNA in HIV-1 assembly by characterizing the distribution and mobility of Gag and Gag NC mutants at the PM using photoactivated localization microscopy (PALM) and single-particle tracking PALM (spt-PALM). We showed that both Gag and GagZiL assembly involve a similar basic assembly unit, as expected. Unexpectedly, the two proteins underwent different subsequent assembly pathways, with Gag cluster density increasing asymptotically, while GagZiL cluster density increased linearly. Additionally, the directed movement of Gag, but not GagZiL, was maintained at a constant speed, suggesting that the two proteins experience different external driving forces. Assembly was abolished when Gag was rendered monomeric by NC deletion. Collectively, these results suggest that, beyond inducing Gag to form low-ordered multimer basic assembly units, vRNA is essential in scaffolding and maintaining the stability of the subsequent assembly process. This finding should advance the current understanding of HIV-1 and, potentially, other retroviruses.
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Wefers AK, Haberlandt C, Tekin NB, Fedorov DA, Timmermann A, van der Want JJL, Chaudhry FA, Steinhäuser C, Schilling K, Jabs R. Synaptic input as a directional cue for migrating interneuron precursors. Development 2017; 144:4125-4136. [PMID: 29061636 DOI: 10.1242/dev.154096] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 10/11/2017] [Indexed: 02/02/2023]
Abstract
During CNS development, interneuron precursors have to migrate extensively before they integrate in specific microcircuits. Known regulators of neuronal motility include classical neurotransmitters, yet the mechanisms that assure interneuron dispersal and interneuron/projection neuron matching during histogenesis remain largely elusive. We combined time-lapse video microscopy and electrophysiological analysis of the nascent cerebellum of transgenic Pax2-EGFP mice to address this issue. We found that cerebellar interneuronal precursors regularly show spontaneous postsynaptic currents, indicative of synaptic innervation, well before settling in the molecular layer. In keeping with the sensitivity of these cells to neurotransmitters, ablation of synaptic communication by blocking vesicular release in acute slices of developing cerebella slows migration. Significantly, abrogation of exocytosis primarily impedes the directional persistence of migratory interneuronal precursors. These results establish an unprecedented function of the early synaptic innervation of migrating neuronal precursors and demonstrate a role for synapses in the regulation of migration and pathfinding.
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Affiliation(s)
- Annika K Wefers
- Anatomisches Institut, Anatomie & Zellbiologie, Medizinische Fakultät, University of Bonn, 53115 Bonn, Germany.,Institut für Zelluläre Neurowissenschaften, Medizinische Fakultät, University of Bonn, 53105 Bonn, Germany
| | - Christian Haberlandt
- Institut für Zelluläre Neurowissenschaften, Medizinische Fakultät, University of Bonn, 53105 Bonn, Germany
| | - Nuriye B Tekin
- Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Dmitry A Fedorov
- Institut für Zelluläre Neurowissenschaften, Medizinische Fakultät, University of Bonn, 53105 Bonn, Germany
| | - Aline Timmermann
- Institut für Zelluläre Neurowissenschaften, Medizinische Fakultät, University of Bonn, 53105 Bonn, Germany
| | - Johannes J L van der Want
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Farrukh A Chaudhry
- Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway
| | - Christian Steinhäuser
- Institut für Zelluläre Neurowissenschaften, Medizinische Fakultät, University of Bonn, 53105 Bonn, Germany
| | - Karl Schilling
- Anatomisches Institut, Anatomie & Zellbiologie, Medizinische Fakultät, University of Bonn, 53115 Bonn, Germany
| | - Ronald Jabs
- Institut für Zelluläre Neurowissenschaften, Medizinische Fakultät, University of Bonn, 53105 Bonn, Germany
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20
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Serbiak B, Fourre T, Geonnotti AR, Gambogi RJ. In vitro efficacy of essential oil mouthrinse versus dentifrices. J Dent 2017; 69:49-54. [PMID: 28863962 DOI: 10.1016/j.jdent.2017.08.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/19/2017] [Accepted: 08/29/2017] [Indexed: 10/19/2022] Open
Abstract
OBJECTIVES To compare the antimicrobial efficacy and kill penetration of essential oils (EO) mouthrinse versus stannous fluoride, and triclosan dentifrice slurries on saliva-derived biofilms using confocal laser scanning microscopy (CLSM). METHODS Saliva-derived biofilms were grown for 48h on hydroxyapatite discs using pooled, homogenized saliva from 8 healthy volunteers as the inoculum. The mean thickness of these biofilms was 84μm (range, 23-241μm). CLSM with viability mapping was used to visualize the antimicrobial kill penetration of each treatment regime within a biofilm. RESULTS At 30s treatment durations, CLSM imaging revealed greater antimicrobial activity and kill penetration of EO mouthrinse compared to sodium fluoride-, stannous fluoride-, and triclosan-containing dentifrice slurries. Quantification of biovolume revealed that EO mouthrinse treatment at 30s resulted in a greater non-viable biovolume proportion (84.6%±15.0%) than other treatment groups. Increasing the treatment duration of the triclosan dentifrice (to 60 and 120s) resulted in better penetration and an increased reduction of viable cells, comparable to EO mouthrinse treatment at 30s duration. Further, CLSM imaging showed that the combined treatment of a non-antimicrobial dentifrice (45s) with EO mouthrinse (30s) showed superior antimicrobial activity (96.2%±3.7%) compared to the antimicrobial triclosan-containing dentifrice used without a mouthrinse step (26.0%±32.0%). CONCLUSIONS Within typical exposure times, the EO-containing mouthrinse can penetrate deep into the accumulating plaque biofilm compared to the chemotherapeutic dentifrice slurries, and may provide an efficacious alternative to triclosan, when used as an adjunct with a mechanical oral care regimen. CLINICAL SIGNIFICANCE Using viability mapping and CLSM, this study demonstrated that EO-containing mouthrinse penetrates and kills microorganisms deeper and more effectively in plaque biofilm in typical exposure times when compared to dentifrice chemotherapeutic agents, providing an efficacious alternative to triclosan or stannous fluoride when used as an adjunct to mechanical oral care.
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Affiliation(s)
- Benjamin Serbiak
- Johnson & Johnson Consumer Inc., 199 Grandview Road, Skillman, NJ, 08558, USA.
| | - Tara Fourre
- Johnson & Johnson Consumer Inc., 199 Grandview Road, Skillman, NJ, 08558, USA.
| | - Anthony R Geonnotti
- Johnson & Johnson Consumer Inc., 199 Grandview Road, Skillman, NJ, 08558, USA.
| | - Robert J Gambogi
- Johnson & Johnson Consumer Inc., 199 Grandview Road, Skillman, NJ, 08558, USA.
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21
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Derivery E, Bartolami E, Matile S, Gonzalez-Gaitan M. Efficient Delivery of Quantum Dots into the Cytosol of Cells Using Cell-Penetrating Poly(disulfide)s. J Am Chem Soc 2017; 139:10172-10175. [PMID: 28741941 PMCID: PMC5553715 DOI: 10.1021/jacs.7b02952] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
Quantum dots (QDs)
are extremely bright, photostable, nanometer
particles broadly used to investigate single molecule dynamics in vitro. However, the use of QDs in vivo to investigate single molecule dynamics is impaired by the absence
of an efficient way to chemically deliver them into the cytosol of
cells. Indeed, current methods (using cell-penetrating peptides for
instance) provide very low yields: QDs stay at the plasma membrane
or are trapped in endosomes. Here, we introduce a technology based
on cell-penetrating poly(disulfide)s that solves this problem: we
deliver about 70 QDs per cell, and 90% appear to freely diffuse in
the cytosol. Furthermore, these QDs can be functionalized, carrying
GFP or anti-GFP nanobodies for instance. Our technology thus paves
the way toward single molecule imaging in cells and living animals,
allowing to probe biophysical properties of the cytosol.
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Affiliation(s)
- Emmanuel Derivery
- MRC Laboratory of Molecular Biology , Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - Eline Bartolami
- School of Chemistry and Biochemistry, National Centre of Competence in Research (NCCR) Chemical Biology, University of Geneva , Quai Ernest Ansermet 30, CH-1211 Geneva, Switzerland
| | - Stefan Matile
- School of Chemistry and Biochemistry, National Centre of Competence in Research (NCCR) Chemical Biology, University of Geneva , Quai Ernest Ansermet 30, CH-1211 Geneva, Switzerland
| | - Marcos Gonzalez-Gaitan
- School of Chemistry and Biochemistry, National Centre of Competence in Research (NCCR) Chemical Biology, University of Geneva , Quai Ernest Ansermet 30, CH-1211 Geneva, Switzerland
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22
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Veya L, Piguet J, Vogel H. Single Molecule Imaging Deciphers the Relation between Mobility and Signaling of a Prototypical G Protein-coupled Receptor in Living Cells. J Biol Chem 2015; 290:27723-35. [PMID: 26363070 DOI: 10.1074/jbc.m115.666677] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Indexed: 01/10/2023] Open
Abstract
Lateral diffusion enables efficient interactions between membrane proteins, leading to signal transmission across the plasma membrane. An open question is how the spatiotemporal distribution of cell surface receptors influences the transmembrane signaling network. Here we addressed this issue by studying the mobility of a prototypical G protein-coupled receptor, the neurokinin-1 receptor, during its different phases of cellular signaling. Attaching a single quantum dot to individual neurokinin-1 receptors enabled us to follow with high spatial and temporal resolution over long time regimes the fate of individual receptors at the plasma membrane. Single receptor trajectories revealed a very heterogeneous mobility distribution pattern with diffusion constants ranging from 0.0005 to 0.1 μm(2)/s comprising receptors freely diffusing and others confined in 100-600-nm-sized membrane domains as well as immobile receptors. A two-dimensional representation of mobility and confinement resolved two major, broadly distributed receptor populations, one showing high mobility and low lateral restriction and the other showing low mobility and high restriction. We found that about 40% of the receptors in the basal state are already confined in membrane domains and are associated with clathrin. After stimulation with an agonist, an additional 30% of receptors became further confined. Using inhibitors of clathrin-mediated endocytosis, we found that the fraction of confined receptors at the basal state depends on the quantity of membrane-associated clathrin and is correlated to a significant decrease of the canonical pathway activity of the receptors. This shows that the high plasticity of receptor mobility is of central importance for receptor homeostasis and fine regulation of receptor activity.
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Affiliation(s)
- Luc Veya
- From the Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Joachim Piguet
- From the Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Horst Vogel
- From the Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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23
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Roccasalvo IM, Micera S, Sergi PN. A hybrid computational model to predict chemotactic guidance of growth cones. Sci Rep 2015; 5:11340. [PMID: 26086936 PMCID: PMC4471899 DOI: 10.1038/srep11340] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 05/15/2015] [Indexed: 11/08/2022] Open
Abstract
The overall strategy used by growing axons to find their correct paths during the nervous system development is not yet completely understood. Indeed, some emergent and counterintuitive phenomena were recently described during axon pathfinding in presence of chemical gradients. Here, a novel computational model is presented together with its ability to reproduce both regular and counterintuitive axonal behaviours. In this model, the key role of intracellular calcium was phenomenologically modelled through a non standard Gierer-Meinhardt system, as a crucial factor influencing the growth cone behaviour both in regular and complex conditions. This model was able to explicitly reproduce neuritic paths accounting for the complex interplay between extracellular and intracellular environments, through the sensing capability of the growth cone. The reliability of this approach was proven by using quantitative metrics, numerically supporting the similarity between in silico and biological results in regular conditions (control and attraction). Finally, the model was able to qualitatively predict emergent and counterintuitive phenomena resulting from complex boundary conditions.
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Affiliation(s)
| | - Silvestro Micera
- The BioRobotics Institute, Scuola Superiore Sant’Anna, Pisa, Italy
- Bertarelli Foundation Chair in Translational NeuroEngineering Laboratory, Institute of Bioengineering, School of Engineering, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
- Center for Neuroprosthetics, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
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24
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Komatsuzaki A, Ohyanagi T, Tsukasaki Y, Miyanaga Y, Ueda M, Jin T. Compact halo-ligand-conjugated quantum dots for multicolored single-molecule imaging of overcrowding GPCR proteins on cell membranes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:1396-1401. [PMID: 25504902 DOI: 10.1002/smll.201402508] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/19/2014] [Indexed: 06/04/2023]
Abstract
To detect single molecules within the optical diffraction limit (< ca. 200 nm), a multicolored imaging technique is developed using Halo-ligand conjugated quantum dots (Halo-QDs; <6 nm in diameter). Using three types of Halo-QDs, multicolored single-molecule fluorescence imaging of GPCR proteins in Dictyostelium cells is achieved.
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Affiliation(s)
- Akihito Komatsuzaki
- Laboratory for Nano-Bio Probes, Quantitative Biology Center, Riken, Suita, 565-0874, Osaka, Japan
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25
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Cytoskeletal rearrangement and Src and PI-3K-dependent Akt activation control GABA(B)R-mediated chemotaxis. Cell Signal 2015; 27:1178-1185. [PMID: 25725285 DOI: 10.1016/j.cellsig.2015.02.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 02/01/2015] [Accepted: 02/15/2015] [Indexed: 01/13/2023]
Abstract
The γ-amino butyric acid (GABA) type B receptors (GABA(B)R) function as chemoattractant receptors in response to GABA(B)R agonists in human neutrophils. The goal of this study was to define signaling mechanisms regulating GABA(B)R-mediated chemotaxis and cytoskeletal rearrangement. In a proteomic study we identified serine/threonine kinase Akt, tyrosine kinases Src and Pyk2, microtubule regulator kinesin and microtubule affinity-regulating kinase (MARK) co-immunoprecipitating with GABA(B)R. To define the contributions of these candidate signaling events in GABA(B)R-mediated chemotaxis, we used rat basophilic leukemic cells (RBL-2H3 cells) stably transfected with human GABA(B1b) and GABA(B2) receptors. The GABA(B)R agonist baclofen induced Akt phosphorylation and chemotaxis by binding to its specific GABA(B)R since pretreatment of cells with CGP52432, a GABA(B)R antagonist, blocked such effects. Moreover, baclofen induced Akt phosphorylation was shown to be dependent upon PI-3K and Src kinases. Baclofen failed to stimulate actin polymerization in suspended RBL cells unless exposed to a baclofen gradient. However, baclofen stimulated both actin and tubulin polymerization in adherent RBL-GABA(B)R cells. Blockade of actin and tubulin polymerization by treatment of cells with cytochalasin D or nocodazole respectively, abolished baclofen-mediated chemotaxis. Furthermore, baclofen stimulated Pyk2 and STAT3 phosphorylation, both known regulators of cell migration. In conclusion, GABA(B)R stimulation promotes chemotaxis in RBL cells which is dependent on signaling via PI3-K/Akt, Src kinases and on rearrangement of both microtubules and actin cytoskeleton. These data define mechanisms of GABA(B)R-mediated chemotaxis which may potentially be used to therapeutically regulate cellular response to injury and disease.
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26
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Abstract
Chemotaxis, or directed motion in chemical gradients, is critical for various biological processes. Many eukaryotic cells perform spatial sensing, i.e. they detect gradients by comparing spatial differences in binding occupancy of chemosensory receptors across their membrane. In many theoretical models of spatial sensing, it is assumed, for the sake of simplicity, that the receptors concerned do not move. However, in reality, receptors undergo diverse modes of diffusion, and can traverse considerable distances in the time it takes such cells to turn in an external gradient. This sets a physical limit on the accuracy of spatial sensing, which we explore using a model in which receptors diffuse freely over the membrane. We find that the Fisher information carried in binding and unbinding events decreases monotonically with the diffusion constant of the receptors.
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27
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Wegner KD, Hildebrandt N. Quantum dots: bright and versatile in vitro and in vivo fluorescence imaging biosensors. Chem Soc Rev 2015; 44:4792-4834. [DOI: 10.1039/c4cs00532e] [Citation(s) in RCA: 562] [Impact Index Per Article: 62.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Colourful cells and tissues: semiconductor quantum dots and their versatile applications in multiplexed bioimaging research.
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Affiliation(s)
- K. David Wegner
- NanoBioPhotonics
- Institut d'Electronique Fondamentale
- Université Paris-Sud
- 91405 Orsay Cedex
- France
| | - Niko Hildebrandt
- NanoBioPhotonics
- Institut d'Electronique Fondamentale
- Université Paris-Sud
- 91405 Orsay Cedex
- France
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28
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Corell M, Wicher G, Radomska KJ, Dağlıkoca ED, Godskesen RE, Fredriksson R, Benedikz E, Magnaghi V, Fex Svenningsen Å. GABA and its B-receptor are present at the node of Ranvier in a small population of sensory fibers, implicating a role in myelination. J Neurosci Res 2014; 93:285-95. [DOI: 10.1002/jnr.23489] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/28/2014] [Accepted: 09/04/2014] [Indexed: 01/28/2023]
Affiliation(s)
- Mikael Corell
- Department of Neuroscience; Uppsala University; Uppsala Sweden
| | - Grzegorz Wicher
- Department of Neuroscience; Uppsala University; Uppsala Sweden
- Department of Genetics and Pathology; Uppsala University; Uppsala Sweden
| | | | - E. Duygu Dağlıkoca
- Department of Molecular Biology and Genetics; Bogazici University; Istanbul Turkey
| | | | | | - Eirikur Benedikz
- IMM-Neurobiology Research; University of Southern Denmark; Odense Denmark
| | - Valerio Magnaghi
- Department of Pharmacological and Biomolecular Sciences; University of Milan; Milan Italy
| | - Åsa Fex Svenningsen
- Department of Neuroscience; Uppsala University; Uppsala Sweden
- IMM-Neurobiology Research; University of Southern Denmark; Odense Denmark
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29
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Pernice M, Levy O. Novel tools integrating metabolic and gene function to study the impact of the environment on coral symbiosis. Front Microbiol 2014; 5:448. [PMID: 25191321 PMCID: PMC4140168 DOI: 10.3389/fmicb.2014.00448] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/05/2014] [Indexed: 11/13/2022] Open
Abstract
The symbiotic dinoflagellates (genus Symbiodinium) inhabiting coral endodermal tissues are well known for their role as keystone symbiotic partners, providing corals with enormous amounts of energy acquired via photosynthesis and the absorption of dissolved nutrients. In the past few decades, corals reefs worldwide have been increasingly affected by coral bleaching (i.e., the breakdown of the symbiosis between corals and their dinoflagellate symbionts), which carries important socio-economic implications. Consequently, the number of studies focusing on the molecular and cellular processes underlying this biological phenomenon has grown rapidly, and symbiosis is now widely recognized as a major topic in coral biology. However, obtaining a clear image of the interplay between the environment and this mutualistic symbiosis remains challenging. Here, we review the potential of recent technological advances in molecular biology and approaches using stable isotopes to fill critical knowledge gaps regarding coral symbiotic function. Finally, we emphasize that the largest opportunity to achieve the full potential in this field arises from the integration of these technological advances.
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Affiliation(s)
- Mathieu Pernice
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney Sydney, NSW, Australia
| | - Oren Levy
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University Ramat Gan, Israel
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30
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Bouzigues C, Nguyên TL, Ramodiharilafy R, Claeson A, Tharaux PL, Alexandrou A. Regulation of the ROS Response Dynamics and Organization to PDGF Motile Stimuli Revealed by Single Nanoparticle Imaging. ACTA ACUST UNITED AC 2014; 21:647-56. [DOI: 10.1016/j.chembiol.2014.02.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/20/2014] [Accepted: 02/21/2014] [Indexed: 02/07/2023]
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31
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Lisse D, Richter CP, Drees C, Birkholz O, You C, Rampazzo E, Piehler J. Monofunctional stealth nanoparticle for unbiased single molecule tracking inside living cells. NANO LETTERS 2014; 14:2189-2195. [PMID: 24655019 DOI: 10.1021/nl500637a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
On the basis of a protein cage scaffold, we have systematically explored intracellular application of nanoparticles for single molecule studies and discovered that recognition by the autophagy machinery plays a key role for rapid metabolism in the cytosol. Intracellular stealth nanoparticles were achieved by heavy surface PEGylation. By combination with a generic approach for nanoparticle monofunctionalization, efficient labeling of intracellular proteins with high fidelity was accomplished, allowing unbiased long-term tracking of proteins in the outer mitochondrial membrane.
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Affiliation(s)
- Domenik Lisse
- Department of Biology, University of Osnabrück , Osnabrück, Germany
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32
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Affiliation(s)
- Wei Wang
- Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
| | - Nongjian Tao
- Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
- Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287, USA
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33
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Akiyama H, Kamiguchi H. Second messenger networks for accurate growth cone guidance. Dev Neurobiol 2013; 75:411-22. [PMID: 24285606 DOI: 10.1002/dneu.22157] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/21/2013] [Accepted: 11/25/2013] [Indexed: 02/02/2023]
Abstract
Growth cones are able to navigate over long distances to find their appropriate target by following guidance cues that are often presented to them in the form of an extracellular gradient. These external cues are converted into gradients of specific signaling molecules inside growth cones, while at the same time these internal signals are amplified. The amplified instruction is then used to generate asymmetric changes in the growth cone turning machinery so that one side of the growth cone migrates at a rate faster than the other side, and thus the growth cone turns toward or away from the external cue. This review examines how signal specification and amplification can be achieved inside the growth cone by multiple second messenger signaling pathways activated downstream of guidance cues. These include the calcium ion, cyclic nucleotide, and phosphatidylinositol signaling pathways.
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Affiliation(s)
- Hiroki Akiyama
- Laboratory for Neuronal Growth Mechanisms, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan
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34
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Bisel B, Calamai M, Vanzi F, Pavone FS. Decoupling polarization of the Golgi apparatus and GM1 in the plasma membrane. PLoS One 2013; 8:e80446. [PMID: 24312472 PMCID: PMC3846482 DOI: 10.1371/journal.pone.0080446] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 10/03/2013] [Indexed: 01/19/2023] Open
Abstract
Cell polarization is a process of coordinated cellular rearrangements that prepare the cell for migration. GM1 is synthesized in the Golgi apparatus and localized in membrane microdomains that appear at the leading edge of polarized cells, but the mechanism by which GM1 accumulates asymmetrically is unknown. The Golgi apparatus itself becomes oriented toward the leading edge during cell polarization, which is thought to contribute to plasma membrane asymmetry. Using quantitative image analysis techniques, we measure the extent of polarization of the Golgi apparatus and GM1 in the plasma membrane simultaneously in individual cells subject to a wound assay. We find that GM1 polarization starts just 10 min after stimulation with growth factors, while Golgi apparatus polarization takes 30 min. Drugs that block Golgi polarization or function have no effect on GM1 polarization, and, conversely, inhibiting GM1 polarization does not affect Golgi apparatus polarization. Evaluation of Golgi apparatus and GM1 polarization in single cells reveals no correlation between the two events. Our results indicate that Golgi apparatus and GM1 polarization are controlled by distinct intracellular cascades involving the Ras/Raf/MEK/ERK and the PI3K/Akt/mTOR pathways, respectively. Analysis of cell migration and invasion suggest that MEK/ERK activation is crucial for two dimensional migration, while PI3K activation drives three dimensional invasion, and no cumulative effect is observed from blocking both simultaneously. The independent biochemical control of GM1 polarity by PI3K and Golgi apparatus polarity by MEK/ERK may act synergistically to regulate and reinforce directional selection in cell migration.
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Affiliation(s)
- Blaine Bisel
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- * E-mail:
| | - Martino Calamai
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics, National Research Council of Italy (CNR), Florence, Italy
| | - Francesco Vanzi
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Evolutionary Biology “Leo Pardi”, University of Florence, Florence, Italy
| | - Francesco Saverio Pavone
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
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35
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Shigeoka T, Lu B, Holt CE. Cell biology in neuroscience: RNA-based mechanisms underlying axon guidance. ACTA ACUST UNITED AC 2013; 202:991-9. [PMID: 24081488 PMCID: PMC3787380 DOI: 10.1083/jcb.201305139] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Axon guidance plays a key role in establishing neuronal circuitry. The motile tips of growing axons, the growth cones, navigate by responding directionally to guidance cues that pattern the embryonic neural pathways via receptor-mediated signaling. Evidence in vitro in the last decade supports the notion that RNA-based mechanisms contribute to cue-directed steering during axon guidance. Different cues trigger translation of distinct subsets of mRNAs and localized translation provides precise spatiotemporal control over the growth cone proteome in response to localized receptor activation. Recent evidence has now demonstrated a role for localized translational control in axon guidance decisions in vivo.
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Affiliation(s)
- Toshiaki Shigeoka
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, England, UK
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36
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Ling Y, Chen T, Jing Y, Fan L, Wan Y, Lin J. γ-Aminobutyric acid (GABA) homeostasis regulates pollen germination and polarized growth in Picea wilsonii. PLANTA 2013; 238:831-43. [PMID: 23900837 DOI: 10.1007/s00425-013-1938-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/19/2013] [Indexed: 05/10/2023]
Abstract
γ-Aminobutyric acid (GABA) is a four-carbon non-protein amino acid found in a wide range of organisms. Recently, GABA accumulation has been shown to play a role in the stress response and cell growth in angiosperms. However, the effect of GABA deficiency on pollen tube development remains unclear. Here, we demonstrated that specific concentrations of exogenous GABA stimulated pollen tube growth in Picea wilsonii, while an overdose suppressed pollen tube elongation. The germination percentage of pollen grains and morphological variations in pollen tubes responded in a dose-dependent manner to treatment with 3-mercaptopropionic acid (3-MP), a glutamate decarboxylase inhibitor, while the inhibitory effects could be recovered in calcium-containing medium supplemented with GABA. Using immunofluorescence labeling, we found that the actin cables were disorganized in 3-MP treated cells, followed by the transition of endo/exocytosis activating sites from the apex to the whole tube shank. In addition, variations in the deposition of cell wall components were detected upon labeling with JIM5, JIM7, and aniline blue. Our results demonstrated that calcium-dependent GABA signaling regulates pollen germination and polarized tube growth in P. wilsonii by affecting actin filament patterns, vesicle trafficking, and the configuration and distribution of cell wall components.
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Affiliation(s)
- Yu Ling
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
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37
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Kwakowsky A, Potapov D, Abrahám IM. Tracking of single receptor molecule mobility in neuronal membranes: a quick theoretical and practical guide. J Neuroendocrinol 2013; 25:1231-7. [PMID: 23927034 DOI: 10.1111/jne.12083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/29/2013] [Accepted: 08/03/2013] [Indexed: 11/28/2022]
Abstract
Single-molecule detection enables us to visualise the real-time dynamics of individual molecules in live cells. We review the recent advancements in single-molecule fluorescence tracking of receptor protein mobility in the neuronal membrane. First, we discuss the practical consideration of single-molecule tracking in neurones, including the choice of cells and possible fluorescent labelling, as well as the appropriate optical set-up and imaging technology. We then describe the analysis of the single-molecule imaging data, including its theoretical and practical aspects of and relevant estimations of the biophysical parameters. Finally, we provide an example of a single-molecule tracking study in neuroendocrinology and highlight the next frontiers of single-molecule detection technologies.
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Affiliation(s)
- A Kwakowsky
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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38
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Ng JCK. A Quantum Dot-Immunofluorescent Labeling Method to Investigate the Interactions between a Crinivirus and Its Whitefly Vector. Front Microbiol 2013; 4:77. [PMID: 23577009 PMCID: PMC3616251 DOI: 10.3389/fmicb.2013.00077] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 03/15/2013] [Indexed: 11/18/2022] Open
Abstract
Successful vector-mediated plant virus transmission entails an intricate but poorly understood interplay of interactions among virus, vector, and plant. The complexity of interactions requires continually improving/evaluating tools and methods for investigating the determinants that are central to mediating virus transmission. A recent study using an organic fluorophore (Alexa Fluor)-based immunofluorescent localization assay demonstrated that specific retention of Lettuce infectious yellows virus (LIYV) virions in the anterior foregut or cibarium of its whitefly vector is required for virus transmission. Continuous exposure of organic fluorophore to high excitation light intensity can result in diminished or loss of signals, potentially confounding the identification of important interactions associated with virus transmission. This limitation can be circumvented by incorporation of photostable fluorescent nanocrystals, such as quantum dots (QDs), into the assay. We have developed and evaluated a QD-immunofluorescent labeling method for the in vitro and in situ localization of LIYV virions based on the recognition specificity of streptavidin-conjugated QD605 (S-QD605) for biotin-conjugated anti-LIYV IgG (B-αIgG). IgG biotinylation was verified in a blot overlay assay by probing SDS-PAGE separated B-αIgG with S-QD605. Immunoblot analyses of LIYV using B-αIgG and S-QD605 resulted in a virus detection limit comparable to that of DAS-ELISA. In membrane feeding experiments, QD signals were observed in the anterior foregut or cibarium of virion-fed whitefly vectors but absent in those of virion-fed whitefly non-vectors. Specific virion retention in whitefly vectors corresponded with successful virus transmission. A fluorescence photobleaching assay of viruliferous whiteflies fed B-αIgG and S-QD605 vs. those fed anti-LIYV IgG and Alexa Fluor 488-conjugated IgG revealed that QD signal was stable and deteriorated approx. seven- to eight-fold slower than that of Alexa Fluor.
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Affiliation(s)
- James C. K. Ng
- Department of Plant Pathology and Microbiology, Center for Disease Vector Research, University of CaliforniaRiverside, CA, USA
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39
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Petryayeva E, Algar WR, Medintz IL. Quantum dots in bioanalysis: a review of applications across various platforms for fluorescence spectroscopy and imaging. APPLIED SPECTROSCOPY 2013; 67:215-52. [PMID: 23452487 DOI: 10.1366/12-06948] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Semiconductor quantum dots (QDs) are brightly luminescent nanoparticles that have found numerous applications in bioanalysis and bioimaging. In this review, we highlight recent developments in these areas in the context of specific methods for fluorescence spectroscopy and imaging. Following a primer on the structure, properties, and biofunctionalization of QDs, we describe select examples of how QDs have been used in combination with steady-state or time-resolved spectroscopic techniques to develop a variety of assays, bioprobes, and biosensors that function via changes in QD photoluminescence intensity, polarization, or lifetime. Some special attention is paid to the use of Förster resonance energy transfer-type methods in bioanalysis, including those based on bioluminescence and chemiluminescence. Direct chemiluminescence, electrochemiluminescence, and charge transfer quenching are similarly discussed. We further describe the combination of QDs and flow cytometry, including traditional cellular analyses and spectrally encoded barcode-based assay technologies, before turning our attention to enhanced fluorescence techniques based on photonic crystals or plasmon coupling. Finally, we survey the use of QDs across different platforms for biological fluorescence imaging, including epifluorescence, confocal, and two-photon excitation microscopy; single particle tracking and fluorescence correlation spectroscopy; super-resolution imaging; near-field scanning optical microscopy; and fluorescence lifetime imaging microscopy. In each of the above-mentioned platforms, QDs provide the brightness needed for highly sensitive detection, the photostability needed for tracking dynamic processes, or the multiplexing capacity needed to elucidate complex systems. There is a clear synergy between advances in QD materials and spectroscopy and imaging techniques, as both must be applied in concert to achieve their full potential.
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Affiliation(s)
- Eleonora Petryayeva
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
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40
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You C, Wilmes S, Richter CP, Beutel O, Liße D, Piehler J. Electrostatically controlled quantum dot monofunctionalization for interrogating the dynamics of protein complexes in living cells. ACS Chem Biol 2013. [PMID: 23186299 DOI: 10.1021/cb300543t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Quantum dots (QD) are powerful labels for probing diffusion and interaction dynamics of proteins on the single molecule level in living cells. Protein cross-linking due to multifunctional QD strongly affects these properties. This becomes particularly critical when labeling interaction partners with QDs for interrogating the dynamics of complexes. We have here implemented a generic method for QD monofunctionalization based on electrostatic repulsion of a highly negatively charged peptide carrier. On the basis of this method, monobiotinylated QDs were prepared with high yield as confirmed by single molecule assays. These QDs were successfully employed for probing the assembly and diffusion dynamics of binary and ternary cytokine-receptor complexes on the surface of living cells by dual color single QD tracking. Thus, sequential and dynamic recruitment of the type I interferon receptor subunits by the ligand could be observed.
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Affiliation(s)
- Changjiang You
- Division
of Biophysics, Department of Biology, University of Osnabrück, 49076 Osnabrück,
Germany
| | - Stephan Wilmes
- Division
of Biophysics, Department of Biology, University of Osnabrück, 49076 Osnabrück,
Germany
| | - Christian P. Richter
- Division
of Biophysics, Department of Biology, University of Osnabrück, 49076 Osnabrück,
Germany
| | - Oliver Beutel
- Division
of Biophysics, Department of Biology, University of Osnabrück, 49076 Osnabrück,
Germany
| | - Domenik Liße
- Division
of Biophysics, Department of Biology, University of Osnabrück, 49076 Osnabrück,
Germany
| | - Jacob Piehler
- Division
of Biophysics, Department of Biology, University of Osnabrück, 49076 Osnabrück,
Germany
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41
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Chang JC, Rosenthal SJ. Quantum dot-based single-molecule microscopy for the study of protein dynamics. Methods Mol Biol 2013; 1026:71-84. [PMID: 23749570 DOI: 10.1007/978-1-62703-468-5_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Real-time microscopic visualization of single molecules in living cells provides a molecular perspective of cellular dynamics, which is difficult to be observed by conventional ensemble techniques. Among various classes of fluorescent tags used in single-molecule tracking, quantum dots are particularly useful due to their unique photophysical properties. This chapter provides an overview of single quantum dot tracking for protein dynamic studies. First, we review the fundamental diffraction limit of conventional optical systems and recent developments in single-molecule detection beyond the diffraction barrier. Second, we describe methods to prepare water-soluble quantum dots for biological labeling and single-molecule microscopy experimental design. Third, we provide detailed methods to perform quantum dot-based single-molecule microscopy. This technical section covers three protocols including (1) imaging system calibration using spin-coated single quantum dots, (2) single quantum dot labeling in living cells, and (3) tracking algorithms for single-molecule analysis.
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Affiliation(s)
- Jerry C Chang
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
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42
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Alenghat FJ, Golan DE. Membrane protein dynamics and functional implications in mammalian cells. CURRENT TOPICS IN MEMBRANES 2013; 72:89-120. [PMID: 24210428 PMCID: PMC4193470 DOI: 10.1016/b978-0-12-417027-8.00003-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The organization of the plasma membrane is both highly complex and highly dynamic. One manifestation of this dynamic complexity is the lateral mobility of proteins within the plane of the membrane, which is often an important determinant of intermolecular protein-binding interactions, downstream signal transduction, and local membrane mechanics. The mode of membrane protein mobility can range from random Brownian motion to immobility and from confined or restricted motion to actively directed motion. Several methods can be used to distinguish among the various modes of protein mobility, including fluorescence recovery after photobleaching, single-particle tracking, fluorescence correlation spectroscopy, and variations of these techniques. Here, we present both a brief overview of these methods and examples of their use to elucidate the dynamics of membrane proteins in mammalian cells-first in erythrocytes, then in erythroblasts and other cells in the hematopoietic lineage, and finally in non-hematopoietic cells. This multisystem analysis shows that the cytoskeleton frequently governs modes of membrane protein motion by stably anchoring the proteins through direct-binding interactions, by restricting protein diffusion through steric interactions, or by facilitating directed protein motion. Together, these studies have begun to delineate mechanisms by which membrane protein dynamics influence signaling sequelae and membrane mechanical properties, which, in turn, govern cell function.
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Affiliation(s)
- Francis J. Alenghat
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - David E. Golan
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
- Hematology Division, Brigham and Women’s Hospital, Boston, Massachusetts, USA
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43
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Rasmussen TE, Jauffred L, Brewer J, Vogel S, Torbensen ER, Lagerholm BC, Oddershede L, Arnspang EC. Single Molecule Applications of Quantum Dots. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jmp.2013.411a2002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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44
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Abstract
Direct visualization of biological processes at single-molecule level provides a detailed perspective which conventional bulk measurements are hard to achieve. Among various classes of fluorescent tags used in single-molecule tracking, quantum dots are particularly useful due to their unique photophysical properties. In this chapter, we describe the principles, methodologies, and experimental protocols for qdot-based single-molecule imaging. The first half provides an overview of fluorescent microscopy and advances in single-molecule tracking using quantum dots. The remainder of this chapter describes methods to carry out qdot-based single-molecule experiments. Detailed protocols including qdot labeling, microscopy setup, and single-molecule analysis using appropriate computational programs are given.
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Affiliation(s)
- Jerry C Chang
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
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45
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Landry MP, Zou X, Wang L, Huang WM, Schulten K, Chemla YR. DNA target sequence identification mechanism for dimer-active protein complexes. Nucleic Acids Res 2012; 41:2416-27. [PMID: 23275566 PMCID: PMC3575837 DOI: 10.1093/nar/gks1345] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Sequence-specific DNA-binding proteins must quickly and reliably localize specific target sites on DNA. This search process has been well characterized for monomeric proteins, but it remains poorly understood for systems that require assembly into dimers or oligomers at the target site. We present a single-molecule study of the target-search mechanism of protelomerase TelK, a recombinase-like protein that is only active as a dimer. We show that TelK undergoes 1D diffusion on non-target DNA as a monomer, and it immobilizes upon dimerization even in the absence of a DNA target site. We further show that dimeric TelK condenses non-target DNA, forming a tightly bound nucleoprotein complex. Together with theoretical calculations and molecular dynamics simulations, we present a novel target-search model for TelK, which may be generalizable to other dimer and oligomer-active proteins.
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Affiliation(s)
- Markita P Landry
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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46
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Mahajan S, Athale CA. Spatial and temporal sensing limits of microtubule polarization in neuronal growth cones by intracellular gradients and forces. Biophys J 2012; 103:2432-45. [PMID: 23260045 DOI: 10.1016/j.bpj.2012.10.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 10/02/2012] [Accepted: 10/10/2012] [Indexed: 12/22/2022] Open
Abstract
Neuronal growth cones are the most sensitive among eukaryotic cells in responding to directional chemical cues. Although a dynamic microtubule cytoskeleton has been shown to be essential for growth-cone turning, the precise nature of coupling of the spatial cue with microtubule polarization is less understood. Here we present a computational model of microtubule polarization in a turning neuronal growth cone. We explore the limits of directional cues in modifying the spatial polarization of microtubules by testing the role of microtubule dynamics, gradients of regulators, and retrograde forces along filopodia. We analyze the steady state and transition behavior of microtubules on being presented with a directional stimulus. Our model makes novel, to our knowledge, predictions about the minimal angular spread of the chemical signal at the growth cone and the fastest polarization times. A regulatory reaction-diffusion network based on the cyclic phosphorylation-dephosphorylation of a regulator predicts that the receptor-signal magnitude can generate the maximal polarization of microtubules and not feedback loops or amplifications in the network. Using both the phenomenological and network models, we have demonstrated some of the physical limits within which the microtubule polarization system works in turning the neuron.
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Affiliation(s)
- Saurabh Mahajan
- Division of Biology, Indian Institute of Science Education and Research-Pune, Pune, India
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47
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Abstract
Dentate gyrus granule cells have been suggested to corelease GABA and glutamate both in juvenile animals and under pathological conditions in adults. Although mossy fiber terminals (MFTs) are known to express glutamic acid decarboxylase (GAD) in early postnatal development, the functional role of GABA synthesis in MFTs remains controversial, and direct evidence for synaptic GABA release from MFTs is missing. Here, using GAD67-GFP transgenic mice, we show that GAD67 is expressed only in a population of immature granule cells in juvenile animals. We demonstrate that GABA can be released from these cells and modulate mossy fiber excitability through activation of GABAB autoreceptors. However, unitary postsynaptic currents generated by individual, GAD67-expressing granule cells are purely glutamatergic in all postsynaptic cell types tested. Thus GAD67 expression does not endow dentate gyrus granule cells with a full GABAergic phenotype and GABA primarily instructs the pre- rather than the postsynaptic element.
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48
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Chang JC, Kovtun O, Blakely RD, Rosenthal SJ. Labeling of neuronal receptors and transporters with quantum dots. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2012; 4:605-19. [PMID: 22887823 PMCID: PMC3753009 DOI: 10.1002/wnan.1186] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The ability to efficiently visualize protein targets in cells is a fundamental goal in biological research. Recently, quantum dots (QDots) have emerged as a powerful class of fluorescent probes for labeling membrane proteins in living cells because of breakthrough advances in QDot surface chemistry and biofunctionalization strategies. This review discusses the increasing use of QDots for fluorescence imaging of neuronal receptors and transporters. The readers are briefly introduced to QDot structure, photophysical properties, and common synthetic routes toward the generation of water-soluble QDots. The following section highlights several reports of QDot application that seek to unravel molecular aspects of neuronal receptor and transporter regulation and trafficking. This article is closed with a prospectus of the future of derivatized QDots in neurobiological and pharmacological research.
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Affiliation(s)
- Jerry C Chang
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
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49
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Chang JC, Rosenthal SJ. Visualization of lipid raft membrane compartmentalization in living RN46A neuronal cells using single quantum dot tracking. ACS Chem Neurosci 2012; 3:737-43. [PMID: 23077717 DOI: 10.1021/cn3000845] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Lipid rafts are cholesterol-enriched subdomains in the plasma membrane that have been reported to act as a platform to facilitate neuronal signaling; however, they are suspected to have a very short lifetime, up to only a few seconds, which calls into question their roles in biological signaling. To better understand their diffusion dynamics and membrane compartmentalization, we labeled lipid raft constituent ganglioside GM1 with single quantum dots through the connection of cholera toxin B subunit, a protein that binds specifically to GM1. Diffusion measurements revealed that single quantum dot-labeled GM1 ganglioside complexes undergo slow, confined lateral diffusion with a diffusion coefficient of ∼7.87 × 10(-2) μm(2)/s and a confinement domain about 200 nm in size. Further analysis of their trajectories showed lateral confinement persisting on the order of tens of seconds, comparable to the time scales of the majority of cellular signaling and biological reactions. Hence, our results provide further evidence in support of the putative function of lipid rafts as signaling platforms.
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Affiliation(s)
| | - Sandra J. Rosenthal
- Materials Science and Technology
Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
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Morel M, Shynkar V, Galas JC, Dupin I, Bouzigues C, Studer V, Dahan M. Amplification and temporal filtering during gradient sensing by nerve growth cones probed with a microfluidic assay. Biophys J 2012; 103:1648-56. [PMID: 23083707 DOI: 10.1016/j.bpj.2012.08.040] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 07/29/2012] [Accepted: 08/13/2012] [Indexed: 01/01/2023] Open
Abstract
Nerve growth cones (GCs) are chemical sensors that convert graded extracellular cues into oriented axonal motion. To ensure a sensitive and robust response to directional signals in complex and dynamic chemical landscapes, GCs are presumably able to amplify and filter external information. How these processing tasks are performed remains however poorly known. Here, we probe the signal-processing capabilities of single GCs during γ-Aminobutyric acid (GABA) directional sensing with a shear-free microfluidic assay that enables systematic measurements of the GC output response to variable input gradients. By measuring at the single molecule level the polarization of GABA(A) chemoreceptors at the GC membrane, as a function of the external GABA gradient, we find that GCs act as i), signal amplifiers over a narrow range of concentrations, and ii), low-pass temporal filters with a cutoff frequency independent of stimuli conditions. With computational modeling, we determine that these systems-level properties arise at a molecular level from the saturable occupancy response and the lateral dynamics of GABA(A) receptors.
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Affiliation(s)
- Mathieu Morel
- Laboratoire Kastler Brossel, Centre National de la Recherche Scientifique, Département de Physique and Institut de Biologie de l'Ecole normale supérieure, Université Pierre et Marie Curie, Paris, France
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