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Antarasen J, Wellnitz B, Kramer SN, Chatterjee S, Kisley L. Cross-correlation increases sampling in diffusion-based super-resolution optical fluctuation imaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.01.587586. [PMID: 38617244 PMCID: PMC11014504 DOI: 10.1101/2024.04.01.587586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Correlation signal processing of optical three-dimensional (x, y, t) data can produce super-resolution images. The second order cross-correlation function XC 2 has been documented to produce super-resolution imaging with static and blinking emitters but not for diffusing emitters. Here, we both analytically and numerically demonstrate cross-correlation analysis for diffusing particles. We then expand our fluorescence correlation spectroscopy super-resolution optical fluctuation imaging (fcsSOFI) analysis to use cross-correlation as a post-processing computational technique to extract both dynamic and structural information of particle diffusion in nanoscale structures simultaneously. We further show how this method increases sampling rates and reduces aliasing for spatial information in both simulated and experimental data. Our work demonstrates how fcsSOFI with cross-correlation can be a powerful signal-processing tool to resolve the nanoscale dynamics and structure in samples relevant to biological and soft materials. TOC Graphic
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2
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Tang WH, Sim SR, Aik DYK, Nelanuthala AVS, Athilingam T, Röllin A, Wohland T. Deep learning reduces data requirements and allows real-time measurements in imaging FCS. Biophys J 2024; 123:655-666. [PMID: 38050354 PMCID: PMC10995408 DOI: 10.1016/j.bpj.2023.11.3403] [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: 08/29/2023] [Revised: 11/18/2023] [Accepted: 11/30/2023] [Indexed: 12/06/2023] Open
Abstract
Imaging fluorescence correlation spectroscopy (FCS) is a powerful tool to extract information on molecular mobilities, actions, and interactions in live cells, tissues, and organisms. Nevertheless, several limitations restrict its applicability. First, FCS is data hungry, requiring 50,000 frames at 1-ms time resolution to obtain accurate parameter estimates. Second, the data size makes evaluation slow. Third, as FCS evaluation is model dependent, data evaluation is significantly slowed unless analytic models are available. Here, we introduce two convolutional neural networks-FCSNet and ImFCSNet-for correlation and intensity trace analysis, respectively. FCSNet robustly predicts parameters in 2D and 3D live samples. ImFCSNet reduces the amount of data required for accurate parameter retrieval by at least one order of magnitude and makes correct estimates even in moderately defocused samples. Both convolutional neural networks are trained on simulated data, are model agnostic, and allow autonomous, real-time evaluation of imaging FCS measurements.
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Affiliation(s)
- Wai Hoh Tang
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore; Department of Statistics and Data Science, National University of Singapore, Singapore, Singapore; Institute of Digital Molecular Analytics and Science, National University of Singapore, Singapore, Singapore
| | - Shao Ren Sim
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Daniel Ying Kia Aik
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore; Institute of Digital Molecular Analytics and Science, National University of Singapore, Singapore, Singapore; Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Ashwin Venkata Subba Nelanuthala
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | | | - Adrian Röllin
- Department of Statistics and Data Science, National University of Singapore, Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore; NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore; Institute of Digital Molecular Analytics and Science, National University of Singapore, Singapore, Singapore; Department of Chemistry, National University of Singapore, Singapore, Singapore.
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3
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Erstling JA, Bag N, Gardinier TC, Kohle FFE, DomNwachukwu N, Butler SD, Kao T, Ma K, Turker MZ, Feuer GB, Lee R, Naguib N, Tallman JF, Malarkey HF, Tsaur L, Moore WL, Chapman DV, Aubert T, Mehta S, Cerione RA, Weiss RS, Baird BA, Wiesner UB. Overcoming Barriers Associated with Oral Delivery of Differently Sized Fluorescent Core-Shell Silica Nanoparticles. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2305937. [PMID: 37689973 DOI: 10.1002/adma.202305937] [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: 06/19/2023] [Revised: 09/07/2023] [Indexed: 09/11/2023]
Abstract
Oral delivery, while a highly desirable form of nanoparticle-drug administration, is limited by challenges associated with overcoming several biological barriers. Here, the authors study how fluorescent and poly(ethylene glycol)-coated (PEGylated) core-shell silica nanoparticles sized 5 to 50 nm interact with major barriers including intestinal mucus, intestinal epithelium, and stomach acid. From imaging fluorescence correlation spectroscopy studies using quasi-total internal reflection fluorescence microscopy, diffusion of nanoparticles through highly scattering mucus is progressively hindered above a critical hydrodynamic size around 20 nm. By studying Caco-2 cell monolayers mimicking the intestinal epithelia, it is observed that ultrasmall nanoparticles below 10 nm diameter (Cornell prime dots, [C' dots]) show permeabilities correlated with high absorption in humans from primarily enhanced passive passage through tight junctions. Particles above 20 nm diameter exclusively show active transport through cells. After establishing C' dot stability in artificial gastric juice, in vivo oral gavage experiments in mice demonstrate successful passage through the body followed by renal clearance without protein corona formation. Results suggest C' dots as viable candidates for oral administration to patients with a proven pathway towards clinical translation and may generate renewed interest in examining silica as a food additive and its effects on nutrition and health.
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Affiliation(s)
- Jacob A Erstling
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Thomas C Gardinier
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Ferdinand F E Kohle
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Naedum DomNwachukwu
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Scott D Butler
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Teresa Kao
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Kai Ma
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Melik Z Turker
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Grant B Feuer
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Rachel Lee
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Nada Naguib
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - James F Tallman
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Henry F Malarkey
- Department of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
| | - Lieihn Tsaur
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - William L Moore
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Dana V Chapman
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Tangi Aubert
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Saurabh Mehta
- Center for Precision Nutrition and Health, Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Richard A Cerione
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Robert S Weiss
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Ulrich B Wiesner
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, 14853, USA
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4
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Sankaran J, Wohland T. Current capabilities and future perspectives of FCS: super-resolution microscopy, machine learning, and in vivo applications. Commun Biol 2023; 6:699. [PMID: 37419967 PMCID: PMC10328937 DOI: 10.1038/s42003-023-05069-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 06/23/2023] [Indexed: 07/09/2023] Open
Abstract
Fluorescence correlation spectroscopy (FCS) is a single molecule sensitive tool for the quantitative measurement of biomolecular dynamics and interactions. Improvements in biology, computation, and detection technology enable real-time FCS experiments with multiplexed detection even in vivo. These new imaging modalities of FCS generate data at the rate of hundreds of MB/s requiring efficient data processing tools to extract information. Here, we briefly review FCS's capabilities and limitations before discussing recent directions that address these limitations with a focus on imaging modalities of FCS, their combinations with super-resolution microscopy, new evaluation strategies, especially machine learning, and applications in vivo.
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Affiliation(s)
- Jagadish Sankaran
- Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore, 138632, Singapore.
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, Singapore, 117558, Singapore.
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DNA-mediated Au@Ag@silica nanopopcorn fluorescent probe for in vivo near-infrared imaging of probiotic Lactobacillus Plantarum. Biosens Bioelectron 2022; 212:114421. [DOI: 10.1016/j.bios.2022.114421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 05/20/2022] [Accepted: 05/22/2022] [Indexed: 11/20/2022]
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Solano A, Lou J, Scipioni L, Gratton E, Hinde E. Radial pair correlation of molecular brightness fluctuations maps protein diffusion as a function of oligomeric state within live-cell nuclear architecture. Biophys J 2022; 121:2152-2167. [PMID: 35490296 PMCID: PMC9247470 DOI: 10.1016/j.bpj.2022.04.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 11/16/2021] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
Nuclear proteins can modulate their DNA binding activity and the exploration volume available during DNA target search by self-associating into higher-order oligomers. Directly tracking this process in the nucleoplasm of a living cell is, however, a complex task. Thus, here we present a microscopy method based on radial pair correlation of molecular brightness fluctuations (radial pCOMB) that can extract the mobility of a fluorescently tagged nuclear protein as a function of its oligomeric state and spatiotemporally map the anisotropy of this parameter with respect to nuclear architecture. By simply performing a rapid frame scan acquisition, radial pCOMB has the capacity to detect, within each pixel, protein oligomer formation and the size-dependent obstruction nuclear architecture imparts on this complex's transport across sub-micrometer distances. From application of radial pCOMB to an oligomeric transcription factor and DNA repair protein, we demonstrate that homo-oligomer formation differentially regulates chromatin accessibility and interaction with the DNA template.
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Affiliation(s)
- Ashleigh Solano
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Jieqiong Lou
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Lorenzo Scipioni
- Department of Biomedical Engineering, University of California, Irvine
| | - Enrico Gratton
- Department of Biomedical Engineering, University of California, Irvine.
| | - Elizabeth Hinde
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne.
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7
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Bag N, London E, Holowka DA, Baird BA. Transbilayer Coupling of Lipids in Cells Investigated by Imaging Fluorescence Correlation Spectroscopy. J Phys Chem B 2022; 126:2325-2336. [PMID: 35294838 DOI: 10.1021/acs.jpcb.2c00117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plasma membranes host numerous receptors, sensors, and ion channels involved in cellular signaling. Phase separation within the plasma membrane has emerged as a key biophysical regulator of signaling reactions in multiple physiological and pathological contexts. There is much evidence that plasma membrane composition supports the coexistence of liquid-ordered (Lo) and liquid-disordered (Ld) phases or domains at physiological conditions. However, this phase/domain separation is nanoscopic and transient in live cells. It has been recently proposed that transbilayer coupling between the inner and outer leaflets of the plasma membrane is driven by their asymmetric lipid distribution and by dynamic cytoskeleton-lipid composites that contribute to the formation and transience of Lo/Ld phase separation in live cells. In this Perspective, we highlight new approaches to investigate how transbilayer coupling may influence phase separation. For quantitative evaluation of the impact of these interactions, we introduce an experimental strategy centered around Imaging Fluorescence Correlation Spectroscopy (ImFCS), which measures membrane diffusion with very high precision. To demonstrate this strategy, we choose two well-established model systems for transbilayer interactions: cross-linking by multivalent antigen of immunoglobulin E bound to receptor FcεRI and cross-linking by cholera toxin B of GM1 gangliosides. We discuss emerging methods to systematically perturb membrane lipid composition, particularly exchange of outer leaflet lipids with exogenous lipids using methyl alpha cyclodextrin. These selective perturbations may be quantitatively evaluated with ImFCS and other high-resolution biophysical tools to discover novel principles of lipid-mediated phase separation in live cells in the context of their pathophysiological relevance.
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Affiliation(s)
- Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - David A Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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8
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Batrouni AG, Bag N, Phan HT, Baird BA, Baskin JM. A palmitoylation code controls PI4KIIIα complex formation and PI(4,5)P2 homeostasis at the plasma membrane. J Cell Sci 2022; 135:272297. [PMID: 34569608 DOI: 10.1242/jcs.259365] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 09/14/2021] [Indexed: 12/12/2022] Open
Abstract
Phosphatidylinositol 4-kinase IIIα (PI4KIIIα) is the major enzyme responsible for generating phosphatidylinositol (4)-phosphate [PI(4)P] at the plasma membrane. This lipid kinase forms two multicomponent complexes, both including a palmitoylated anchor, EFR3. Whereas both PI4KIIIα complexes support production of PI(4)P, the distinct functions of each complex and mechanisms underlying the interplay between them remain unknown. Here, we present roles for differential palmitoylation patterns within a tri-cysteine motif in EFR3B (Cys5, Cys7 and Cys8) in controlling the distribution of PI4KIIIα between these two complexes at the plasma membrane and corresponding functions in phosphoinositide homeostasis. Spacing of palmitoyl groups within three doubly palmitoylated EFR3B 'lipoforms' affects both interactions between EFR3B and TMEM150A, a transmembrane protein governing formation of a PI4KIIIα complex functioning in rapid phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] resynthesis following phospholipase C signaling, and EFR3B partitioning within liquid-ordered and -disordered regions of the plasma membrane. This work identifies a palmitoylation code involved in controlling protein-protein and protein-lipid interactions that affect a plasma membrane-resident lipid biosynthetic pathway.
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Affiliation(s)
- Alex G Batrouni
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.,Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853, USA
| | - Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Henry T Phan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jeremy M Baskin
- Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853, USA.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
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9
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Bullerjahn JT, Hummer G. Maximum likelihood estimates of diffusion coefficients from single-particle tracking experiments. J Chem Phys 2021; 154:234105. [PMID: 34241279 DOI: 10.1063/5.0038174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Single-molecule localization microscopy allows practitioners to locate and track labeled molecules in biological systems. When extracting diffusion coefficients from the resulting trajectories, it is common practice to perform a linear fit on mean-squared-displacement curves. However, this strategy is suboptimal and prone to errors. Recently, it was shown that the increments between the observed positions provide a good estimate for the diffusion coefficient, and their statistics are well-suited for likelihood-based analysis methods. Here, we revisit the problem of extracting diffusion coefficients from single-particle tracking experiments subject to static noise and dynamic motion blur using the principle of maximum likelihood. Taking advantage of an efficient real-space formulation, we extend the model to mixtures of subpopulations differing in their diffusion coefficients, which we estimate with the help of the expectation-maximization algorithm. This formulation naturally leads to a probabilistic assignment of trajectories to subpopulations. We employ the theory to analyze experimental tracking data that cannot be explained with a single diffusion coefficient. We test how well a dataset conforms to the assumptions of a diffusion model and determine the optimal number of subpopulations with the help of a quality factor of known analytical distribution. To facilitate use by practitioners, we provide a fast open-source implementation of the theory for the efficient analysis of multiple trajectories in arbitrary dimensions simultaneously.
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Affiliation(s)
- Jakob Tómas Bullerjahn
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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10
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Fukushima R, Yamamoto J, Kinjo M. Empirical Bayes method using surrounding pixel information for number and brightness analysis. Biophys J 2021; 120:2156-2171. [PMID: 33812845 PMCID: PMC8390835 DOI: 10.1016/j.bpj.2021.03.033] [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: 08/28/2020] [Revised: 03/13/2021] [Accepted: 03/23/2021] [Indexed: 11/26/2022] Open
Abstract
Number and brightness (N&B) analysis is useful for monitoring the spatial distribution of the concentration and oligomeric state of fluorescently labeled proteins in cells. N&B analysis is based on the statistical analysis of fluorescence images by using the method of moments (MoM). Furthermore, N&B analysis can determine the particle number and particle brightness, which indicate the concentration and oligomeric state, respectively. However, the statistical accuracy and precision are limited in actual experiments with fluorescent proteins, owing to low excitation and the limited number of images. In this study, we applied maximum likelihood (ML) estimation and maximum a posteriori (MAP) estimation coupled with the empirical Bayes (EB) method (referred to as EB-MAP). In EB-MAP, we constructed a simple prior distribution for a pixel to utilize the information of the surrounding pixels. To evaluate the accuracy and precision of our method, we conducted simulations and experiments and compared the results of MoM, ML, and EB-MAP. The results showed that MoM estimated the particle number with many outliers. The outliers hampered the visibility of the spatial distribution and cellular structure. In contrast, EB-MAP suppressed the number of outliers and improved the visibility notably. The precision of EB-MAP was better by an order of magnitude in terms of particle number and 1.5 times better in terms of particle brightness compared with those of MoM. The proposed method (EB-MAP-N&B) is applicable to studies on fluorescence imaging and would aid in accurately recognizing changes in the concentration and oligomeric state in cells. Our results hold significant importance because quantifying the concentration and oligomeric state would contribute to the understanding of dynamic processes in molecular mechanism in cells.
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Affiliation(s)
- Ryosuke Fukushima
- Laboratory of Molecular Cell Dynamics, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Johtaro Yamamoto
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan; Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan.
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Yoshida S, Schmid W, Vo N, Calabrase W, Kisley L. Computationally-efficient spatiotemporal correlation analysis super-resolves anomalous diffusion. OPTICS EXPRESS 2021; 29:7616-7629. [PMID: 33726259 DOI: 10.1364/oe.416465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Anomalous diffusion dynamics in confined nanoenvironments govern the macroscale properties and interactions of many biophysical and material systems. Currently, it is difficult to quantitatively link the nanoscale structure of porous media to anomalous diffusion within them. Fluorescence correlation spectroscopy super-resolution optical fluctuation imaging (fcsSOFI) has been shown to extract nanoscale structure and Brownian diffusion dynamics within gels, liquid crystals, and polymers, but has limitations which hinder its wider application to more diverse, biophysically-relevant datasets. Here, we parallelize the least-squares curve fitting step on a GPU improving computation times by up to a factor of 40, implement anomalous diffusion and two-component Brownian diffusion models, and make fcsSOFI more accessible by packaging it in a user-friendly GUI. We apply fcsSOFI to simulations of the protein fibrinogen diffusing in polyacrylamide of varying matrix densities and super-resolve locations where slower, anomalous diffusion occurs within smaller, confined pores. The improvements to fcsSOFI in speed, scope, and usability will allow for the wider adoption of super-resolution correlation analysis to diverse research topics.
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12
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Ito T, Higgins DA. Fluorescence Microscopic Investigations of Molecular Dynamics in Self-Assembled Nanostructures. CHEM REC 2021; 21:1417-1429. [PMID: 33533548 DOI: 10.1002/tcr.202000173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/17/2021] [Accepted: 01/18/2020] [Indexed: 11/05/2022]
Abstract
Many analytical methods employ self-assembled nanostructured materials as chemical recognition media. Molecular permeation through these materials exhibits unique selectivity owing to nanoconfinement-induced enhancement of permeant-nanostructure interactions. This Personal Account introduces our efforts to investigate the detailed dynamics of single or a small number of molecules in nanostructured materials. We developed new experimental and analysis approaches built upon laser-based fluorescence microscopy to measure the detailed translational and orientational dynamics of molecules diffusing in horizontally-oriented, cylindrical nanostructures, including surfactant micelles, silica mesopores, block copolymer microdomains, and bolaamphiphile-based organic nanotubes. Our studies clarified nanoscale details on the structural/chemical heterogeneity of the nanostructures, and their impacts on molecular mass transport dynamics.
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Affiliation(s)
- Takashi Ito
- Department of Chemistry, Kansas State University, 213 CBC Building, Manhattan, KS 66506-0401, USA
| | - Daniel A Higgins
- Department of Chemistry, Kansas State University, 213 CBC Building, Manhattan, KS 66506-0401, USA
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13
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Erstling JA, Hinckley JA, Bag N, Hersh J, Feuer GB, Lee R, Malarkey HF, Yu F, Ma K, Baird BA, Wiesner UB. Ultrasmall, Bright, and Photostable Fluorescent Core-Shell Aluminosilicate Nanoparticles for Live-Cell Optical Super-Resolution Microscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006829. [PMID: 33470471 PMCID: PMC7936654 DOI: 10.1002/adma.202006829] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/07/2020] [Indexed: 06/12/2023]
Abstract
Stochastic optical reconstruction microscopy (STORM) is an optical super-resolution microscopy (SRM) technique that traditionally requires toxic and non-physiological imaging buffers and setups that are not conducive to live-cell studies. It is observed that ultrasmall (<10 nm) fluorescent core-shell aluminosilicate nanoparticles (aC' dots) covalently encapsulating organic fluorophores enable STORM with a single excitation source and in a regular (non-toxic) imaging buffer. It is shown that fourfold coordinated aluminum is responsible for dye blinking, likely via photoinduced redox processes. It is demonstrated that this phenomenon is observed across different dye families leading to probes brighter and more photostable than the parent free dyes. Functionalization of aC' dots with antibodies allows targeted fixed cell STORM imaging. Finally, aC' dots enable live-cell STORM imaging providing quantitative measures of the size of intracellular vesicles and the number of particles per vesicle. The results suggest the emergence of a powerful ultrasmall, bright, and photostable optical SRM particle platform with characteristics relevant to clinical translation for the quantitative assessment of cellular structures and processes from live-cell imaging.
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Affiliation(s)
- Jacob A Erstling
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Joshua A Hinckley
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Jessica Hersh
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Grant B Feuer
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Rachel Lee
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Henry F Malarkey
- Department of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853, USA
| | - Fei Yu
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Kai Ma
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Ulrich B Wiesner
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
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14
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Cambré A, Aertsen A. Bacterial Vivisection: How Fluorescence-Based Imaging Techniques Shed a Light on the Inner Workings of Bacteria. Microbiol Mol Biol Rev 2020; 84:e00008-20. [PMID: 33115939 PMCID: PMC7599038 DOI: 10.1128/mmbr.00008-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The rise in fluorescence-based imaging techniques over the past 3 decades has improved the ability of researchers to scrutinize live cell biology at increased spatial and temporal resolution. In microbiology, these real-time vivisections structurally changed the view on the bacterial cell away from the "watery bag of enzymes" paradigm toward the perspective that these organisms are as complex as their eukaryotic counterparts. Capitalizing on the enormous potential of (time-lapse) fluorescence microscopy and the ever-extending pallet of corresponding probes, initial breakthroughs were made in unraveling the localization of proteins and monitoring real-time gene expression. However, later it became clear that the potential of this technique extends much further, paving the way for a focus-shift from observing single events within bacterial cells or populations to obtaining a more global picture at the intra- and intercellular level. In this review, we outline the current state of the art in fluorescence-based vivisection of bacteria and provide an overview of important case studies to exemplify how to use or combine different strategies to gain detailed information on the cell's physiology. The manuscript therefore consists of two separate (but interconnected) parts that can be read and consulted individually. The first part focuses on the fluorescent probe pallet and provides a perspective on modern methodologies for microscopy using these tools. The second section of the review takes the reader on a tour through the bacterial cell from cytoplasm to outer shell, describing strategies and methods to highlight architectural features and overall dynamics within cells.
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Affiliation(s)
- Alexander Cambré
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
| | - Abram Aertsen
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
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15
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Rocha S, Hendrix J, Borrenberghs D, Debyser Z, Hofkens J. Imaging the Replication of Single Viruses: Lessons Learned from HIV and Future Challenges To Overcome. ACS NANO 2020; 14:10775-10783. [PMID: 32820634 DOI: 10.1021/acsnano.0c06369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The molecular composition of viral particles indicates that a single virion is capable of initiating an infection. However, the majority of viruses that come into contact with cells fails to infect them. Understanding what makes one viral particle more successful than others requires visualizing the infection process directly in living cells, one virion at a time. In this Perspective, we explain how single-virus imaging using fluorescence microscopy can provide answers to unsolved questions in virology. We discuss fluorescent labeling of virus particles, resolution at the subviral and molecular levels, tracking in living cells, and imaging of interactions between viral and host proteins. We end this Perspective with a set of remaining questions in understanding the life cycle of retroviruses and how imaging a single virus can help researchers address these questions. Although we use examples from the HIV field, these methods are of value for the study of other viruses as well.
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Affiliation(s)
- Susana Rocha
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
| | - Jelle Hendrix
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute (BIOMED), Hasselt University, B-3590 Diepenbeek, Flanders, Belgium
| | - Doortje Borrenberghs
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
| | - Zeger Debyser
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, B-3001 Heverlee, Flanders, Belgium
| | - Johan Hofkens
- Molecular Imaging and Photonics, Chemistry Department, KU Leuven, B-3001 Heverlee, Flanders, Belgium
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
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Stoneman MR, Biener G, Raicu V. Proposal for simultaneous analysis of fluorescence intensity fluctuations and resonance energy transfer (IFRET) measurements. Methods Appl Fluoresc 2020; 8:035011. [DOI: 10.1088/2050-6120/ab9b68] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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17
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Ghimire G, Moore MM, Leuschen R, Nagasaka S, Kameta N, Masuda M, Higgins DA, Ito T. Influences of Hydrogen Bonding-Based Stabilization of Bolaamphiphile Layers on Molecular Diffusion within Organic Nanotubes Having Inner Carboxyl Groups. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6145-6153. [PMID: 32396729 DOI: 10.1021/acs.langmuir.0c00556] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This paper reports molecular diffusion behavior in two bolaamphiphile-based organic nanotubes having inner carboxyl groups with different inner dimeters (10 and 20 nm) and wall structures, COOH-ONT10nm and COOH-ONT20nm, using imaging fluorescence correlation spectroscopy (imaging FCS). The results were compared to those previously obtained in a similar nanotube with inner amine groups (NH2-ONT10nm). COOH-ONT10nm, as with NH2-ONT10nm, were formed from a rolled bolaamphiphile layer incorporating triglycine moieties, whereas COOH-ONT20nm consisted of four stacks of triglycine-free bolaamphiphile layers. Imaging FCS measurements were carried out for anionic sulforhodamine B (SRB), zwitterionic/cationic rhodamine B (RB), and cationic rhodamine-123 (R123) diffusing within ONTs (1-9 μm long) at different pH (3.4-8.4) and ionic strengths (1.6-500 mM). Diffusion coefficients (D) of these dyes in the ONTs were very small (0.01-0.1 μm2/s), reflecting the significant contributions of molecule-nanotube interactions to diffusion. The D of SRB was larger at higher pH and ionic strength, indicating the essential role of electrostatic repulsion that was enhanced by the deprotonation of the inner carboxyl groups. Importantly, the D of SRB was virtually independent of nanotube inner diameter and wall structure, indicating the diffusion of the hydrophilic molecule was controlled by short time scale adsorption/desorption processes onto the inner surface. In contrast, pH effects on D were less clear for relatively hydrophobic R123 and RB, suggesting the significant contributions of non-Coulombic interactions. Interestingly, the diffusion of these molecules in COOH-ONT20nm was slower than in COOH-ONT10nm. Slower diffusion in COOH-ONT20nm was attributable to relatively efficient partitioning of the hydrophobic dyes into the bolaamphiphile layers, which was reduced in COOH-ONT10nm due to the stabilization of its layer by polyglycine-II-type hydrogen bonding networks. These results show that, by tuning the bolaamphiphile structures and their intermolecular interactions, unique environments can be created within the nanospaces for enhanced molecular separations and reactions.
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Affiliation(s)
- Govinda Ghimire
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-0401, United States
| | - Mikaela M Moore
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-0401, United States
| | - Rebecca Leuschen
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-0401, United States
| | - Shinobu Nagasaka
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-0401, United States
| | - Naohiro Kameta
- Nanomaterials Research Institute, Department of Materials and Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Mitsutoshi Masuda
- Research Institute for Sustainable Chemistry, Department of Materials and Chemistry, AIST, Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Daniel A Higgins
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-0401, United States
| | - Takashi Ito
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-0401, United States
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The centenary of the Stern-Volmer equation of fluorescence quenching: From the single line plot to the SV quenching map. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2020. [DOI: 10.1016/j.jphotochemrev.2019.100338] [Citation(s) in RCA: 118] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Bag N, Holowka DA, Baird BA. Imaging FCS delineates subtle heterogeneity in plasma membranes of resting mast cells. Mol Biol Cell 2020; 31:709-723. [PMID: 31895009 PMCID: PMC7202073 DOI: 10.1091/mbc.e19-10-0559] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A myriad of transient, nanoscopic lipid- and protein-based interactions confer a steady-state organization of the plasma membrane in resting cells that is poised to orchestrate assembly of key signaling components upon reception of an extracellular stimulus. Although difficult to observe directly in live cells, these subtle interactions can be discerned by their impact on the diffusion of membrane constituents. Here, we quantified the diffusion properties of a panel of structurally distinct lipid, lipid-anchored, and transmembrane (TM) probes in RBL mast cells by imaging fluorescence correlation spectroscopy (ImFCS). We developed a statistical analysis of data combined from many pixels over multiple cells to characterize differences in diffusion coefficients as small as 10%, which reflect differences in underlying interactions. We found that the distinctive diffusion properties of lipid probes can be explained by their dynamic partitioning into Lo-like proteolipid nanodomains, which encompass a major fraction of the membrane and whose physical properties are influenced by actin polymerization. Effects on diffusion of functional protein modules in both lipid-anchored and TM probes reflect additional complexity in steady state membrane organization. The contrast we observe between different probes diffusing through the same membrane milieu represents the dynamic resting steady state, which serves as a baseline for monitoring plasma membrane remodeling that occurs upon stimulation.
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Affiliation(s)
- Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - David A Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
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Ghimire G, Espinoza R, Xu H, Nagasaka S, Kameta N, Masuda M, Higgins DA, Ito T. Diffusion Behavior of Differently Charged Molecules in Self-Assembled Organic Nanotubes Studied Using Imaging Fluorescence Correlation Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:7783-7790. [PMID: 31125237 DOI: 10.1021/acs.langmuir.9b01022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The diffusion behavior of fluorescent molecules within bolaamphiphile-based organic nanotubes (ONTs) was systematically investigated using imaging fluorescence correlation spectroscopy (imaging FCS). Anionic sulforhodamine B, zwitterionic/cationic rhodamine B, or cationic rhodamine 123 was loaded into ONTs having cylindrical hollow structures (ca. 10 nm in inner diameter) with amine and glucose groups on the inner and outer surfaces, respectively. Wide-field fluorescence video microscopy was used to acquire imaging FCS data for dye-doped ONTs in aqueous solutions of different ionic strengths (1-500 mM) at different pH (3.4-8.4). The diffusion behavior of these dyes was discussed on the basis of their apparent diffusion coefficients ( D) that were determined by autocorrelating the time transient of fluorescence intensity at each pixel on an ONT. Molecular diffusion in the ONTs was significantly slowed by the molecule-nanotube interactions, as shown by the very small D (10-1 to 10-2 μm2/s). The pH dependence of D revealed that dye diffusion was basically controlled by electrostatic interactions associated with the protonation of the amine groups on the ONT inner surface. The pH-dependent change in D was observed over a wide pH range, possibly because of electrostatically induced variations in the p Ka of the densely packed ammonium ions on the ONT inner surface. On the other hand, the influence of ionic strength on D was relatively unclear, suggesting the involvement of non-Coulombic interactions with the ONTs in molecular diffusion. Importantly, individual ONTs of different lengths (1-5 μm) afforded similar diffusion coefficients for each type of dye at each solution condition, implying that the properties of the ONTs were uniform in terms of solute loading and release. These results highlight the characteristics of the molecular diffusion behavior within the ONTs and will help in the design of ONTs better suited for use as drug vehicles and contaminant adsorbents.
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Affiliation(s)
- Govinda Ghimire
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506-0401 , United States
| | - Roberto Espinoza
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506-0401 , United States
| | - Hao Xu
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506-0401 , United States
| | - Shinobu Nagasaka
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506-0401 , United States
| | - Naohiro Kameta
- Nanomaterials Research Institute, Department of Materials and Chemistry , National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba Central 5, 1-1-1 Higashi , Tsukuba , Ibaraki 305-8565 , Japan
| | - Mitsutoshi Masuda
- Research Institute for Sustainable Chemistry, Department of Materials and Chemistry , AIST , Tsukuba Central 5, 1-1-1 Higashi , Tsukuba , Ibaraki 305-8565 , Japan
| | - Daniel A Higgins
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506-0401 , United States
| | - Takashi Ito
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506-0401 , United States
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21
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Nguyen H, Ward WS, James NG. Spatial and temporal resolution of mORC4 fluorescent variants reveals structural requirements for achieving higher order self-association and pronuclei entry. Methods Appl Fluoresc 2019; 7:035002. [PMID: 30865939 PMCID: PMC6636821 DOI: 10.1088/2050-6120/ab0f57] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The Origin Replication Complex (ORC), which is a multi-subunit protein complex composed of six proteins ORC1-6, is essential for initiating licensing at DNA replication origins. We have previously reported that ORC4 has an alternative function wherein it forms a cage surrounding the extruded chromatin in female meiosis and is required for polar body extrusion (PBE). As this is a highly unexpected finding for protein that normally binds DNA, we tested whether ORC4 can actually form larger, higher order structures, which would be necessary to form a cage-like structure. We generated two fluorescent constructs of mouse ORC4, mORC4-EGFP and mORC4-FlAsH, to examine its spatial dynamics during oocyte activation in live cells. We show that both constructs were primarily monomeric throughout the embryo but self-association into larger units was detected with both probes. However, mORC4-FlAsH clearly showed higher order self-association and unique spatial distribution while mORC4-EGFP failed to form large structures during Anaphase II. Interestingly, both variants were found in the pronuclei suggesting that its role in DNA licensing is still functional. Our results with both constructs support the prediction that ORC4 can form higher order structures in the cytoplasm, suggesting that it is possible to form a cage-like structure. The finding that FlAsH labeled ORC4 formed demonstrably larger higher order structures than ORC4-GFP suggests that ORC4 oligomerization is sensitive to the bulky addition of GFP at its carboxy terminus.
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Affiliation(s)
- Hieu Nguyen
- Department of Anatomy, Biochemistry, and Physiology, John A. Burns School of Medicine, 1960 East-West Rd., University of Hawaii, Honolulu, HI 96822, United States of America
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22
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A FRET-based fluorescent probe for hydrogen peroxide based on the use of carbon quantum dots conjugated to gold nanoclusters. Mikrochim Acta 2019; 186:294. [DOI: 10.1007/s00604-019-3398-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 04/01/2019] [Indexed: 02/04/2023]
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Gupta A, Sankaran J, Wohland T. Fluorescence correlation spectroscopy: The technique and its applications in soft matter. PHYSICAL SCIENCES REVIEWS 2019. [DOI: 10.1515/psr-2017-0104] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Abstract
Fluorescence correlation spectroscopy (FCS) is a well-established single-molecule method used for the quantitative spatiotemporal analysis of dynamic processes in a wide range of samples. It possesses single-molecule sensitivity but provides ensemble averaged molecular parameters such as mobility, concentration, chemical reaction kinetics, photophysical properties and interaction properties. These parameters have been utilized to characterize a variety of soft matter systems. This review provides an overview of the basic principles of various FCS modalities, their instrumentation, data analysis, and the applications of FCS to soft matter systems.
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Protein oligomerization and mobility within the nuclear envelope evaluated by the time-shifted mean-segmented Q factor. Methods 2018; 157:28-41. [PMID: 30268407 DOI: 10.1016/j.ymeth.2018.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 09/14/2018] [Accepted: 09/25/2018] [Indexed: 11/21/2022] Open
Abstract
Analysis of fluorescence fluctuation experiments by the mean-segmented Q (MSQ) method was recently used to successfully characterize the oligomeric state and mobility of proteins within the nuclear envelope (NE) of living cells. However, two significant shortcomings of MSQ were recognized. Non-ideal detector behavior due to dead-time and afterpulsing as well as the lack of error analysis currently limit the potential of MSQ. This paper presents time-shifted MSQ (tsMSQ), a new formulation of MSQ that is robust with respect to dead-time and afterpulsing. In addition, a protocol for performing error analysis on tsMSQ data is introduced to assess the quality of fit models and estimate the uncertainties of fit parameters. Together, these developments significantly simplify and improve the analysis of fluorescence fluctuation data taken within the NE. To demonstrate these new developments, tsMSQ was used to characterize the oligomeric state and mobility of the luminal domains of two inner nuclear membrane SUN proteins. The results for the luminal domain of SUN2 obtained through tsMSQ without correction for non-ideal detector effects agree with a recent study that was conducted using the original MSQ formulation. Finally, tsMSQ was applied to characterize the oligomeric state and mobility of the luminal domain of the germline-restricted SUN3.
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25
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Hoischen C, Monajembashi S, Weisshart K, Hemmerich P. Multimodal Light Microscopy Approaches to Reveal Structural and Functional Properties of Promyelocytic Leukemia Nuclear Bodies. Front Oncol 2018; 8:125. [PMID: 29888200 PMCID: PMC5980967 DOI: 10.3389/fonc.2018.00125] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 04/05/2018] [Indexed: 12/11/2022] Open
Abstract
The promyelocytic leukemia (pml) gene product PML is a tumor suppressor localized mainly in the nucleus of mammalian cells. In the cell nucleus, PML seeds the formation of macromolecular multiprotein complexes, known as PML nuclear bodies (PML NBs). While PML NBs have been implicated in many cellular functions including cell cycle regulation, survival and apoptosis their role as signaling hubs along major genome maintenance pathways emerged more clearly. However, despite extensive research over the past decades, the precise biochemical function of PML in these pathways is still elusive. It remains a big challenge to unify all the different previously suggested cellular functions of PML NBs into one mechanistic model. With the advent of genetically encoded fluorescent proteins it became possible to trace protein function in living specimens. In parallel, a variety of fluorescence fluctuation microscopy (FFM) approaches have been developed which allow precise determination of the biophysical and interaction properties of cellular factors at the single molecule level in living cells. In this report, we summarize the current knowledge on PML nuclear bodies and describe several fluorescence imaging, manipulation, FFM, and super-resolution techniques suitable to analyze PML body assembly and function. These include fluorescence redistribution after photobleaching, fluorescence resonance energy transfer, fluorescence correlation spectroscopy, raster image correlation spectroscopy, ultraviolet laser microbeam-induced DNA damage, erythrocyte-mediated force application, and super-resolution microscopy approaches. Since most if not all of the microscopic equipment to perform these techniques may be available in an institutional or nearby facility, we hope to encourage more researches to exploit sophisticated imaging tools for their research in cancer biology.
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Harwardt MLIE, Dietz MS, Heilemann M, Wohland T. SPT and Imaging FCS Provide Complementary Information on the Dynamics of Plasma Membrane Molecules. Biophys J 2018; 114:2432-2443. [PMID: 29650369 PMCID: PMC6129459 DOI: 10.1016/j.bpj.2018.03.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/10/2018] [Accepted: 03/12/2018] [Indexed: 12/27/2022] Open
Abstract
The dynamics of biomolecules in the plasma membrane is of fundamental importance to understanding cellular processes. Cellular signaling often starts with extracellular ligand binding to a membrane receptor, which then transduces an intracellular signal. Ligand binding and receptor-complex activation often involve a complex rearrangement of proteins in the membrane, which results in changes in diffusion properties. Two widely used methods to characterize biomolecular diffusion are single-particle tracking (SPT) and imaging total internal reflection fluorescence correlation spectroscopy (ITIR-FCS). Here, we compare the results of recovered diffusion coefficients and mean-square displacements of the two methods by simulations of free, domain-confined, or meshwork diffusion. We introduce, to our knowledge, a new method for the determination of confinement radii from ITIR-FCS data. We further establish and demonstrate simultaneous SPT/ITIR-FCS for direct comparison within living cells. Finally, we compare the results obtained by SPT and ITIR-FCS for the receptor tyrosine kinase MET. Our results show that SPT and ITIR-FCS yield complementary information on diffusion properties of biomolecules in cell membranes.
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Affiliation(s)
- Marie-Lena I E Harwardt
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany
| | - Marina S Dietz
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany.
| | - Thorsten Wohland
- Departments of Biological Sciences and Chemistry, Center for Bioimaging Sciences, National University of Singapore, Singapore, Singapore.
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27
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Collini M, Bouzin M, Chirico G. Out of the Randomness: Correlating Noise in Biological Systems. Biophys J 2018; 114:2298-2307. [PMID: 29477335 PMCID: PMC6129560 DOI: 10.1016/j.bpj.2018.01.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 01/23/2018] [Accepted: 01/29/2018] [Indexed: 11/23/2022] Open
Abstract
The study of the dynamics of biological systems requires one to follow relaxation processes in time with micron-size spatial resolution. This need has led to the development of different fluorescence correlation techniques with high spatial resolution and a tremendous (from nanoseconds to seconds) temporal dynamic range. Spatiotemporal information can be obtained even on complex dynamic processes whose time evolution is not forecast by simple Brownian diffusion. Our discussion of the most recent applications of image correlation spectroscopy to the study of anomalous sub- or superdiffusion suggests that this field still requires the development of multidimensional image analyses based on analytical models or numerical simulations. We focus in particular on the framework of spatiotemporal image correlation spectroscopy and examine the critical steps in getting information on anomalous diffusive processes from the correlation maps. We point out how a dual space-time correlative analysis, in both the direct and the Fourier space, can provide quantitative information on superdiffusional processes when these are analyzed through an empirical model based on intermittent active dynamics. We believe that this dual space-time analysis, potentially amenable to mathematical treatment and to the exact fit of experimental data, could be extended to include the rich phenomenology of subdiffusive processes, thereby quantifying relevant parameters for the various motivating biological problems of interest.
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Affiliation(s)
- Maddalena Collini
- Dipartimento di Fisica e Centro di Nanomedicina, Università degli Studi di Milano-Bicocca, Milan, Italy; CNR-ISASI, Center for Complex Systems, Pozzuoli, Italy
| | - Margaux Bouzin
- Dipartimento di Fisica e Centro di Nanomedicina, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Giuseppe Chirico
- Dipartimento di Fisica e Centro di Nanomedicina, Università degli Studi di Milano-Bicocca, Milan, Italy; CNR-ISASI, Center for Complex Systems, Pozzuoli, Italy.
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28
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Ng J, Kamm RD, Wohland T, Kraut RS. Evidence from ITIR-FCS Diffusion Studies that the Amyloid-Beta (Aβ) Peptide Does Not Perturb Plasma Membrane Fluidity in Neuronal Cells. J Mol Biol 2018; 430:3439-3453. [PMID: 29746852 DOI: 10.1016/j.jmb.2018.04.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/27/2018] [Accepted: 04/29/2018] [Indexed: 10/17/2022]
Abstract
The amyloid-beta (Aβ) peptide, commonly found in elevated levels in the brains of patients with Alzheimer's disease (AD) and in the cerebrospinal fluid of individuals presenting mild cognitive impairment, is thought to be one of the major factors resulting in the onset of AD. Although observed and studied at the molecular level for several decades, the exact disease pathology of AD is still not totally clear. One way in which Aβ is thought to affect neurons is by influencing cell membrane fluidity, which could result in abnormal synaptic or signaling function. The effects of Aβ on the fluidity of biological membranes have been studied using numerous membrane models such as artificial lipid bilayers and vesicles, living cells and membranes extracted from animal models of AD, yet there is still no consensus as to what effects Aβ has, if any, on membrane fluidity. As one of the most precise and accurate means of assaying membrane dynamics, we have thus chosen fluorescence correlation spectroscopy to investigate the issue, using fluorescent membrane-targeted probes on living cells treated with Aβ(1-42) oligomers and observing possible changes in membrane diffusion. Effects of Aβ on viability in different cell types varied from no detectable effect to extensive cell death by 72 h post-exposure. However, there was no change in the fluidity of either ordered membrane domains or the bulk membrane in any of these cells within this period. Our conclusion from these results is that perturbation of membrane fluidity is not likely to be a factor in acute Aβ-induced cytotoxicity.
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Affiliation(s)
- Justin Ng
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, S637551, Singapore; Singapore-MIT Alliance for Research and Technology, BioSyM IRG, 1 Create Way, S138602, Singapore
| | - Roger D Kamm
- Singapore-MIT Alliance for Research and Technology, BioSyM IRG, 1 Create Way, S138602, Singapore
| | - Thorsten Wohland
- Singapore-MIT Alliance for Research and Technology, BioSyM IRG, 1 Create Way, S138602, Singapore; Department of Biological Sciences and Chemistry, National University of Singapore, 14 Science Drive 4, S117543, Singapore
| | - Rachel S Kraut
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, S637551, Singapore; Singapore-MIT Alliance for Research and Technology, BioSyM IRG, 1 Create Way, S138602, Singapore.
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Rigler R, Widengren J. Fluorescence-based monitoring of electronic state and ion exchange kinetics with FCS and related techniques: from T-jump measurements to fluorescence fluctuations. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2018; 47:479-492. [PMID: 29260269 PMCID: PMC5982452 DOI: 10.1007/s00249-017-1271-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 10/30/2017] [Accepted: 12/03/2017] [Indexed: 11/01/2022]
Abstract
In this review, we give a historical view of how our research in the development and use of fluorescence correlation spectroscopy (FCS) and related techniques has its roots and how it originally evolved from the pioneering work of Manfred Eigen, his colleagues, and coworkers. Work on temperature-jump (T-jump) experiments, conducted almost 50 years ago, led on to the development of the FCS technique. The pioneering work in the 1970s, introducing and demonstrating the concept for FCS, in turn formed the basis for the breakthrough use of FCS more than 15 years later. FCS can be used for monitoring reaction kinetics, based on fluctuations at thermodynamic equilibrium, rather than on relaxation measurements following perturbations. In this review, we more specifically discuss FCS measurements on photodynamic, electronic state transitions in fluorophore molecules, and on proton exchange dynamics in solution and on biomembranes. In the latter case, FCS measurements have proven capable of casting new light on the mechanisms of proton exchange at biological membranes, of central importance to bioenergetics and signal transduction. Finally, we describe the transient-state (TRAST) spectroscopy/imaging technique, sharing features with both relaxation (T-jump) and equilibrium fluctuation (FCS) techniques. TRAST is broadly applicable for cellular and molecular studies, and we briefly outline how TRAST can provide unique information from fluorophore blinking kinetics, reflecting e.g., cellular metabolism, rare molecular encounters, and molecular stoichiometries.
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Affiliation(s)
- Rudolf Rigler
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Jerker Widengren
- Experimental Biomolecular Physics/ Department of Applied Physics, Royal Institute of Technology (KTH), Stockholm, Sweden.
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Veerapathiran S, Wohland T. The imaging FCS diffusion law in the presence of multiple diffusive modes. Methods 2017; 140-141:140-150. [PMID: 29203404 DOI: 10.1016/j.ymeth.2017.11.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/24/2017] [Accepted: 11/28/2017] [Indexed: 01/21/2023] Open
Abstract
The cellular plasma membrane is the barrier over which cells exchange materials and communicate with their surroundings, and thus plays the central role in cellular sensing and metabolism. Therefore, the investigation of plasma membrane organization and dynamics is required for understanding of cellular functions. The plasma membrane is a heterogeneous matrix. The presence of structures such as lipid and protein domains and the cytoskeleton meshwork poses a hindrance to the free diffusion of membrane associated biomolecules. However, these domains and the cytoskeleton meshwork barriers are below the optical diffraction limit with potentially short lifetimes and are not easily detected even in super-resolution microscopy. Therefore, dynamic measurements are often used to indirectly prove the existence of domains and barriers by analyzing the mode of diffusion of probe molecules. One of these tools is the Fluorescence Correlation Spectroscopy (FCS) diffusion law. The FCS diffusion law is a plot of diffusion time (τd) versus observation area. For at least three different diffusive modes - free, domain confined, and meshwork hindered hop diffusion - the expected plots have been characterized, typically by its y-intercept (τ0) when fit with a linear model, and have been verified in many cases. However, a description of τ0 has only been given for pure diffusive modes. But in many experimental cases it is not evident that a protein will undergo only one kind of diffusion, and thus the interpretation of the τ0 value is problematic. Here, we therefore address the question about the absolute value of τ0 in the case of complex diffusive modes, i.e. when either one molecule is domain confined and cytoskeleton hindered or when two molecules exhibit different diffusive behavior at the same position in a sample. In addition, we investigate how τ0 changes when the diffusive mode of a probe alters upon disruption of domains or the cytoskeleton by drug treatments. By a combination of experimental studies and simulations, we show that τ0 is not influenced equally by the different diffusive modes as typically found in cellular environments, and that it is the relative change of τ0 rather than its absolute value that provides information on the mode of diffusion.
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Affiliation(s)
- Sapthaswaran Veerapathiran
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, 117557 Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, 117557 Singapore, Singapore; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore.
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31
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Harwardt MLIE, Young P, Bleymüller WM, Meyer T, Karathanasis C, Niemann HH, Heilemann M, Dietz MS. Membrane dynamics of resting and internalin B-bound MET receptor tyrosine kinase studied by single-molecule tracking. FEBS Open Bio 2017; 7:1422-1440. [PMID: 28904870 PMCID: PMC5586345 DOI: 10.1002/2211-5463.12285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 08/07/2017] [Accepted: 08/08/2017] [Indexed: 11/09/2022] Open
Abstract
The human MET receptor tyrosine kinase contributes to vertebrate development and cell proliferation. As a proto-oncogene, it is a target in cancer therapies. MET is also relevant for bacterial infection by Listeria monocytogenes and is activated by the bacterial protein internalin B. The processes of ligand binding, receptor activation, and the diffusion behavior of MET within the plasma membrane as well as its interconnections with various cell components are not fully understood. We investigated the receptor diffusion dynamics using single-particle tracking and imaging fluorescence correlation spectroscopy and elucidated mobility states of resting and internalin B-bound MET. We show that internalin B-bound MET exhibits lower diffusion coefficients and diffuses in a more confined area in the membrane. We report that the fraction of immobile receptors is larger for internalin B-bound receptors than for resting MET. Results of single-particle tracking in cells treated with various cytotoxins depleting cholesterol from the membrane and disrupting the actin cytoskeleton and microtubules suggest that cholesterol and actin influence MET diffusion dynamics, while microtubules do not have any effect.
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Affiliation(s)
- Marie-Lena I E Harwardt
- Institute of Physical and Theoretical Chemistry Johann Wolfgang Goethe-University Frankfurt Germany
| | - Phoebe Young
- Institute of Physical and Theoretical Chemistry Johann Wolfgang Goethe-University Frankfurt Germany
| | - Willem M Bleymüller
- Structural Biochemistry Department of Chemistry Bielefeld University Germany
| | - Timo Meyer
- Structural Biochemistry Department of Chemistry Bielefeld University Germany
| | - Christos Karathanasis
- Institute of Physical and Theoretical Chemistry Johann Wolfgang Goethe-University Frankfurt Germany
| | - Hartmut H Niemann
- Structural Biochemistry Department of Chemistry Bielefeld University Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry Johann Wolfgang Goethe-University Frankfurt Germany
| | - Marina S Dietz
- Institute of Physical and Theoretical Chemistry Johann Wolfgang Goethe-University Frankfurt Germany
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Ng XW, Teh C, Korzh V, Wohland T. The Secreted Signaling Protein Wnt3 Is Associated with Membrane Domains In Vivo: A SPIM-FCS Study. Biophys J 2017; 111:418-429. [PMID: 27463143 DOI: 10.1016/j.bpj.2016.06.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 06/10/2016] [Accepted: 06/16/2016] [Indexed: 10/21/2022] Open
Abstract
Wnt3 is a morphogen that activates the Wnt signaling pathway and regulates a multitude of biological processes ranging from cell proliferation and cell fate specification to differentiation over embryonic induction to neural patterning. Recent studies have shown that the palmitoylation of Wnt3 by Porcupine, a membrane-bound O-acyltransferase, plays a significant role in the intracellular membrane trafficking of Wnt3 and subsequently, its secretion in live zebrafish embryos, where chemical inhibition of Porcupine reduced the membrane-bound and secreted fractions of Wnt3 and eventually led to defective brain development. However, the membrane distribution of Wnt3 in cells remains not fully understood. Here, we determine the membrane organization of functionally active Wnt3-EGFP in cerebellar cells of live transgenic zebrafish embryos and the role of palmitoylation in its organization using single plane illumination microscopy-fluorescence correlation spectroscopy (SPIM-FCS), a multiplexed modality of FCS, which generates maps of molecular dynamics, concentration, and interaction of biomolecules. The FCS diffusion law was applied to SPIM-FCS data to study the subresolution membrane organization of Wnt3. We find that at the plasma membrane in vivo, Wnt3 is associated with cholesterol-dependent domains. This association reduces with increasing concentrations of Porcupine inhibitor (C59), confirming the importance of palmitoylation of Wnt3 for its association with cholesterol-dependent domains. Reduction of membrane cholesterol also results in a decrease of Wnt3 association with cholesterol-dependent domains in live zebrafish. This demonstrates for the first time, to our knowledge, in live vertebrate embryos that Wnt3 is associated with cholesterol-dependent domains.
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Affiliation(s)
- Xue Wen Ng
- Department of Chemistry, National University of Singapore, Singapore, Singapore; Center for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Cathleen Teh
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore
| | - Vladimir Korzh
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Thorsten Wohland
- Department of Chemistry, National University of Singapore, Singapore, Singapore; Center for BioImaging Sciences, National University of Singapore, Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
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Di Rienzo C, Cardarelli F, Di Luca M, Beltram F, Gratton E. Diffusion Tensor Analysis by Two-Dimensional Pair Correlation of Fluorescence Fluctuations in Cells. Biophys J 2016; 111:841-851. [PMID: 27558727 PMCID: PMC5002073 DOI: 10.1016/j.bpj.2016.07.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 07/08/2016] [Accepted: 07/08/2016] [Indexed: 11/22/2022] Open
Abstract
In a living cell, the movement of biomolecules is highly regulated by the cellular organization into subcompartments that impose barriers to diffusion, can locally break the spatial isotropy, and ultimately guide these molecules to their targets. Despite the pivotal role of these processes, experimental tools to fully probe the complex connectivity (and accessibility) of the cell interior with adequate spatiotemporal resolution are still lacking. Here, we show how the heterogeneity of molecular dynamics and the location of barriers to molecular motion can be mapped in live cells by exploiting a two-dimensional (2D) extension of the pair correlation function (pCF) analysis. Starting from a time series of images collected for the same field of view, the resulting 2D pCF is calculated in the proximity of each point for each time delay and allows us to probe the spatial distribution of the molecules that started from a given pixel. This 2D pCF yields an accurate description of the preferential diffusive routes. Furthermore, we combine this analysis with the image-derived mean-square displacement approach and gain information on the average nanoscopic molecular displacements in different directions. Through these quantities, we build a fluorescence-fluctuation-based diffusion tensor that contains information on speed and directionality of the local dynamical processes. Contrary to classical fluorescence correlation spectroscopy and related methods, this combined approach can distinguish between isotropic and anisotropic local diffusion. We argue that the measurement of this iMSD tensor will contribute to advance our understanding of the role played by the intracellular environment in the regulation of molecular diffusion at the nanoscale.
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Affiliation(s)
- Carmine Di Rienzo
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro, Pisa, Italy; Center for Nanotechnology Innovation @NEST, Istituto Italiano di Technologia, Piazza San Silvestro, Pisa, Italy.
| | - Francesco Cardarelli
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Technologia, Piazza San Silvestro, Pisa, Italy
| | - Mariagrazia Di Luca
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro, Pisa, Italy
| | - Fabio Beltram
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro, Pisa, Italy; Center for Nanotechnology Innovation @NEST, Istituto Italiano di Technologia, Piazza San Silvestro, Pisa, Italy
| | - Enrico Gratton
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California.
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Plasma Membrane Organization of Epidermal Growth Factor Receptor in Resting and Ligand-Bound States. Biophys J 2016; 109:1925-36. [PMID: 26536269 DOI: 10.1016/j.bpj.2015.09.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/24/2015] [Accepted: 09/08/2015] [Indexed: 12/21/2022] Open
Abstract
The spatial arrangement of the epidermal growth factor receptor (EGFR) on the cellular plasma membrane is one of the prime factors that control its downstream signaling pathways and related functions. However, the molecular organization, which spans the scale from nanometers to micrometer-size clusters, has not been resolved in detail, mainly due to a lack of techniques with the required spatiotemporal resolution. Therefore, we used imaging total internal reflection-fluorescence correlation spectroscopy to investigate EGFR dynamics on live CHO-K1 plasma membranes in resting and ligand-bound states. In combination with the fluorescence correlation spectroscopy diffusion law, this provides information on the subresolution organization of EGFR on cell membranes. We found that overall EGFR organization is sensitive to both cholesterol and the actin cytoskeleton. EGFR in the resting state is partly trapped in cholesterol-containing domains, whereas another fraction exhibits cholesterol independent trapping on the membrane. Disruption of the cytoskeleton leads to a broader range of EGFR diffusion coefficients and a reduction of hop diffusion. In the ligand-bound state we found a dose-dependent behavior. At 10 ng/mL EGF the EGFR is endocytosed and recycled to the membrane, whereas diffusion and organization do not change significantly. At 100 ng/mL EGF the EGFR forms clusters, which are subsequently internalized, whereas outside the clusters diffusivity increases and the organization of the receptor remains unchanged. After disruption of cholesterol-containing domains or actin cytoskeleton, EGF induces microscopic EGFR clusters on the membrane and endocytosis is inhibited.
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Bag N, Ng XW, Sankaran J, Wohland T. Spatiotemporal mapping of diffusion dynamics and organization in plasma membranes. Methods Appl Fluoresc 2016; 4:034003. [PMID: 28355150 DOI: 10.1088/2050-6120/4/3/034003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Imaging fluorescence correlation spectroscopy (FCS) and the related FCS diffusion law have been applied in recent years to investigate the diffusion modes of lipids and proteins in membranes. These efforts have provided new insights into the membrane structure below the optical diffraction limit, new information on the existence of lipid domains, and on the influence of the cytoskeleton on membrane dynamics. However, there has been no systematic study to evaluate how domain size, domain density, and the probe partition coefficient affect the resulting imaging FCS diffusion law parameters. Here, we characterize the effects of these factors on the FCS diffusion law through simulations and experiments on lipid bilayers and live cells. By segmenting images into smaller 7 × 7 pixel areas, we can evaluate the FCS diffusion law on areas smaller than 2 µm and thus provide detailed maps of information on the membrane structure and heterogeneity at this length scale. We support and extend this analysis by deriving a mathematical expression to calculate the mean squared displacement (MSDACF) from the autocorrelation function of imaging FCS, and demonstrate that the MSDACF plots depend on the existence of nanoscopic domains. Based on the results, we derive limits for the detection of domains depending on their size, density, and relative viscosity in comparison to the surroundings. Finally, we apply these measurements to bilayers and live cells using imaging total internal reflection FCS and single plane illumination microscopy FCS.
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Affiliation(s)
- Nirmalya Bag
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore. NUS Centre for Bio-Imaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117557, Singapore
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Kim S, Fujitsuka M, Miyata M, Majima T. Excited-state dynamics of Si–rhodamine and its aggregates: versatile fluorophores for NIR absorption. Phys Chem Chem Phys 2016; 18:2097-103. [DOI: 10.1039/c5cp06541k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The properties of SiR monomers and aggregates in the excited states are thoroughly characterized for the first time using time-resolved spectroscopy.
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Affiliation(s)
- Sooyeon Kim
- The Institute of Scientific and Industrial Research (SANKEN)
- Osaka University
- Ibaraki
- Japan
| | - Mamoru Fujitsuka
- The Institute of Scientific and Industrial Research (SANKEN)
- Osaka University
- Ibaraki
- Japan
| | - Mikiji Miyata
- The Institute of Scientific and Industrial Research (SANKEN)
- Osaka University
- Ibaraki
- Japan
| | - Tetsuro Majima
- The Institute of Scientific and Industrial Research (SANKEN)
- Osaka University
- Ibaraki
- Japan
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37
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Imaging fluorescence (cross-) correlation spectroscopy in live cells and organisms. Nat Protoc 2015; 10:1948-74. [DOI: 10.1038/nprot.2015.100] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Cattoni DI, Valeri A, Le Gall A, Nollmann M. A matter of scale: how emerging technologies are redefining our view of chromosome architecture. Trends Genet 2015; 31:454-64. [PMID: 26113398 DOI: 10.1016/j.tig.2015.05.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/21/2015] [Accepted: 05/22/2015] [Indexed: 11/25/2022]
Abstract
The 3D folding of the genome and its relation to fundamental processes such as gene regulation, replication, and segregation remains one of the most puzzling and exciting questions in genetics. In this review, we describe how the use of new technologies is starting to revolutionize the field of chromosome organization, and to shed light on the mechanisms of transcription, replication, and repair. In particular, we concentrate on recent studies using genome-wide methods, single-molecule technologies, and super-resolution microscopy (SRM). We summarize some of the main concerns when employing these techniques, and discuss potential new and exciting perspectives that illuminate the connection between 3D genomic organization and gene regulation.
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Affiliation(s)
- Diego I Cattoni
- Centre de Biochimie Structurale, CNRS UMR5048, INSERM U1054, Université de Montpellier, 29 rue de Navacelles, 34090 Montpellier, France
| | - Alessandro Valeri
- Centre de Biochimie Structurale, CNRS UMR5048, INSERM U1054, Université de Montpellier, 29 rue de Navacelles, 34090 Montpellier, France
| | - Antoine Le Gall
- Centre de Biochimie Structurale, CNRS UMR5048, INSERM U1054, Université de Montpellier, 29 rue de Navacelles, 34090 Montpellier, France
| | - Marcelo Nollmann
- Centre de Biochimie Structurale, CNRS UMR5048, INSERM U1054, Université de Montpellier, 29 rue de Navacelles, 34090 Montpellier, France.
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