scholarly journals Nonspecific binding of common anti-CFTR antibodies in ciliated cells of human airway epithelium

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yukiko Sato ◽  
Kamila R. Mustafina ◽  
Yishan Luo ◽  
Carolina Martini ◽  
David Y. Thomas ◽  
...  
Keyword(s):  
Super Resolution ◽  
Anion Channel ◽  
Bronchial Epithelium ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Transmembrane Conductance Regulator ◽  
Ciliated Cells ◽  
Human Airway Epithelium ◽  
Differentiated Cells ◽  
Well Differentiated

AbstractThere is evidence that the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel is highly expressed at the apical pole of ciliated cells in human bronchial epithelium (HBE), however recent studies have detected little CFTR mRNA in those cells. To understand this discrepancy we immunostained well differentiated primary HBE cells using CFTR antibodies. We confirmed apical immunofluorescence in ciliated cells and quantified the covariance of the fluorescence signals and that of an antibody against the ciliary marker centrin-2 using image cross-correlation spectroscopy (ICCS). Super-resolution stimulated emission depletion (STED) imaging localized the immunofluorescence in distinct clusters at the bases of the cilia. However, similar apical fluorescence was observed when the monoclonal CFTR antibodies 596, 528 and 769 were used to immunostain ciliated cells expressing F508del-CFTR, or cells lacking CFTR due to a Class I mutation. A BLAST search using the CFTR epitope identified a similar amino acid sequence in the ciliary protein rootletin X1. Its expression level correlated with the intensity of immunostaining by CFTR antibodies and it was detected by 596 antibody after transfection into CFBE cells. These results may explain the high apparent expression of CFTR in ciliated cells and reports of anomalous apical immunofluorescence in well differentiated cells that express F508del-CFTR.

scholarly journals The cortical actin network regulates avidity-dependent binding of hyaluronan by the lymphatic vessel endothelial receptor LYVE-1

2020 ◽  
Vol 295 (15) ◽  
pp. 5036-5050 ◽  
Author(s):  
Tess A. Stanly ◽  
Marco Fritzsche ◽  
Suneale Banerji ◽  
Dilip Shrestha ◽  
Falk Schneider ◽  
...  
Keyword(s):  
Lymphatic Vessel ◽  
Leukocyte Adhesion ◽  
Lymphatic Vessels ◽  
Super Resolution ◽  
Direct Interaction ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Actin Network ◽  
Cortical Actin ◽  
Limited Mobility

Lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) mediates the docking and entry of dendritic cells to lymphatic vessels through selective adhesion to its ligand hyaluronan in the leukocyte surface glycocalyx. To bind hyaluronan efficiently, LYVE-1 must undergo surface clustering, a process that is induced efficiently by the large cross-linked assemblages of glycosaminoglycan present within leukocyte pericellular matrices but is induced poorly by the shorter polymer alone. These properties suggested that LYVE-1 may have limited mobility in the endothelial plasma membrane, but no biophysical investigation of these parameters has been carried out to date. Here, using super-resolution fluorescence microscopy and spectroscopy combined with biochemical analyses of the receptor in primary lymphatic endothelial cells, we provide the first evidence that LYVE-1 dynamics are indeed restricted by the submembranous actin network. We show that actin disruption not only increases LYVE-1 lateral diffusion but also enhances hyaluronan-binding activity. However, unlike the related leukocyte HA receptor CD44, which uses ERM and ankyrin motifs within its cytoplasmic tail to bind actin, LYVE-1 displays little if any direct interaction with actin, as determined by co-immunoprecipitation. Instead, as shown by super-resolution stimulated emission depletion microscopy in combination with fluorescence correlation spectroscopy, LYVE-1 diffusion is restricted by transient entrapment within submembranous actin corrals. These results point to an actin-mediated constraint on LYVE-1 clustering in lymphatic endothelium that tunes the receptor for selective engagement with hyaluronan assemblages in the glycocalyx that are large enough to cross-bridge the corral-bound LYVE-1 molecules and thereby facilitate leukocyte adhesion and transmigration.

scholarly journals Adaptive optics allows 3D STED-FCS measurements in the cytoplasm of living cells

2019 ◽  
Author(s):  
Aurélien Barbotin ◽  
Silvia Galiani ◽  
Iztok Urbančič ◽  
Christian Eggeling ◽  
Martin Booth
Keyword(s):  
Adaptive Optics ◽  
Molecular Diffusion ◽  
Three Dimensional ◽  
Super Resolution ◽  
Correction Method ◽  
Living Cells ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Optical Aberrations ◽  
Extreme Sensitivity

Fluorescence correlation spectroscopy in combination with super-resolution stimulated emission depletion microscopy (STED-FCS) is a powerful tool to investigate molecular diffusion with sub-diffraction resolution. It has been of particular use for investigations of two dimensional systems like cell membranes, but has so far seen very limited applications to studies of three-dimensional diffusion. One reason for this is the extreme sensitivity of the axial (3D) STED depletion pattern to optical aberrations. We present here an adaptive optics-based correction method that compensates for these aberrations and allows STED-FCS measurements in the cytoplasm of living cells.

scholarly journals Mechanism of substance P-induced liquid secretion across bronchial epithelium

2001 ◽  
Vol 281 (3) ◽  
pp. L639-L645 ◽  
Author(s):  
Laura Trout ◽  
Michel R. Corboz ◽  
Stephen T. Ballard
Keyword(s):  
Substance P ◽  
Anion Channel ◽  
Bronchial Epithelium ◽  
Surface Epithelium ◽  
Channel Blockers ◽  
Transmembrane Conductance Regulator ◽  
Inhibitory Effects ◽  
Transmembrane Conductance ◽  
Submucosal Glands ◽  
Cystic Fibrosis Transmembrane

The present study was undertaken to identify and determine the mechanism of noncholinergic pathways for the induction of liquid secretion across airway epithelium. Excised porcine bronchi secreted substantial and significant quantities of liquid when exposed to acetylcholine, substance P, or forskolin but not to isoproterenol, norepinephrine, or phenylephrine. Bumetanide, an inhibitor of Na+-K+-2Cl− cotransport, reduced the liquid secretion response to substance P by 69%. Approximately two-thirds of bumetanide-insensitive liquid secretion was blocked by dimethylamiloride (DMA), a Na+/H+ exchange inhibitor. Substance P responses were preserved in airways after surface epithelium removal, suggesting that secreted liquid originated from submucosal glands. The anion channel blockers diphenylamine-2-carboxylate (DPC) and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) inhibited >90% of substance P-induced liquid secretion, whereas DIDS had no effect. DMA, DPC, and NPPB had greater inhibitory effects on net HCO[Formula: see text] secretion than on liquid secretion. Although preserved relative to liquid secretion, net HCO[Formula: see text]secretion was reduced by 39% in the presence of bumetanide. We conclude that substance P induces liquid secretion from bronchial submucosal glands of pigs through active transport of Cl−and HCO[Formula: see text]. The pattern of responses to secretion agonists and antagonists suggests that the cystic fibrosis transmembrane conductance regulator mediates this process.

scholarly journals Super-Resolution STED Microscopy-Based Mobility Studies of the Viral Env Protein at HIV-1 Assembly Sites of Fully Infected T-Cells

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 608
Author(s):  
Jakub Chojnacki ◽  
Christian Eggeling
Keyword(s):  
Molecular Dynamics ◽  
Plasma Membrane ◽  
Molecular Mobility ◽  
Virus Assembly ◽  
Methodological Approach ◽  
Super Resolution ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Model Systems ◽  
Hiv 1

The ongoing threat of human immunodeficiency virus (HIV-1) requires continued, detailed investigations of its replication cycle, especially when combined with the most physiologically relevant, fully infectious model systems. Here, we demonstrate the application of the combination of stimulated emission depletion (STED) super-resolution microscopy with beam-scanning fluorescence correlation spectroscopy (sSTED-FCS) as a powerful tool for the interrogation of the molecular dynamics of HIV-1 virus assembly on the cell plasma membrane in the context of a fully infectious virus. In this process, HIV-1 envelope glycoprotein (Env) becomes incorporated into the assembling virus by interacting with the nascent Gag structural protein lattice. Molecular dynamics measurements at these distinct cell surface sites require a guiding strategy, for which we have used a two-colour implementation of sSTED-FCS to simultaneously target individual HIV-1 assembly sites via the aggregated Gag signal. We then compare the molecular mobility of Env proteins at the inside and outside of the virus assembly area. Env mobility was shown to be highly reduced at the assembly sites, highlighting the distinct trapping of Env as well as the usefulness of our methodological approach to study the molecular mobility of specifically targeted sites at the plasma membrane, even under high-biosafety conditions.

scholarly journals Background reduction in STED-FCS using coherent-hybrid STED

2020 ◽  
Author(s):  
Aurélien Barbotin ◽  
Iztok Urbančič ◽  
Silvia Galiani ◽  
Christian Eggeling ◽  
Martin Booth
Keyword(s):  
Diffusion Processes ◽  
Super Resolution ◽  
Living Cells ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Three Dimensions ◽  
Signal Quality ◽  
Optical Aberrations ◽  
Observation Volume ◽  
Supramolecular Arrangements

AbstractFluorescence correlation spectroscopy (FCS) is a valuable tool to study the molecular dynamics of living cells. When used together with a super-resolution stimulated emission depletion (STED) microscope, STED-FCS can measure diffusion processes at the nanoscale in living cells. In twodimensional (2D) systems like the cellular plasma membrane, a ring-shaped depletion focus is most commonly used to increase the lateral resolution, leading to more than 25-fold decrease in the observation volumee, reaching the relevant scale of supramolecular arrangements. However, STED-FCS faces severe limitations when measuring diffusion in three dimensions (3D), largely due to the spurious background contributions from undepleted areas of the excitation focus that reduce the signal quality and ultimately limit the resolution. In this paper, we investigate how different STED confinement modes can mitigate this issue. By simulations as well as experiments with fluorescent probes in solution and in cells, we demonstrate that the coherent-hybrid (CH) depletion pattern reduces background most efficiently and thus provides superior signal quality under comparable reduction of the observation volume. Featuring also the highest robustness to common optical aberrations, CH-STED can be considered the method of choice for reliable STED-FCS based investigations of 3D diffusion on the sub-diffraction scale.

scholarly journals High photon count rates improve the quality of super-resolution fluorescence fluctuation spectroscopy

2019 ◽  
Author(s):  
Falk Schneider ◽  
Pablo Hernandez-Varas ◽  
B. Christoffer Lagerholm ◽  
Dilip Shrestha ◽  
Erdinc Sezgin ◽  
...  
Keyword(s):  
Data Quality ◽  
Super Resolution ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Three Dimensions ◽  
High Count ◽  
Photon Count ◽  
Diffusion Dynamics ◽  
Wide Range

AbstractProbing the diffusion of molecules has become a routine measurement across the life sciences, chemistry and physics. It provides valuable insights into reaction dynamics, oligomerisation, molecular (re-)organisation or cellular heterogeneities. Fluorescence correlation spectroscopy (FCS) is one of the widely applied techniques to determine diffusion dynamics in two and three dimensions. This technique relies on the temporal autocorrelation of intensity fluctuations but recording these fluctuations has thus far been limited by the detection electronics, which could not efficiently and accurately time-tag photons at high count rates. This has until now restricted the range of measurable dye concentrations, as well as the data quality of the FCS recordings, especially in combination with super-resolution stimulated emission depletion (STED) nanoscopy.Here, we investigate the applicability and reliability of (STED-)FCS at high photon count rates (average intensities of up to 40 MHz) using novel detection equipment, namely hybrid detectors and real-time gigahertz sampling of the photon streams implemented on a commercial microscope. By measuring the diffusion of fluorophores in solution and cytoplasm of live cells, as well as in model and cellular membranes, we show that accurate diffusion and concentration measurements are possible in these previously inaccessible high photon count regimes. Specifically, it offers much greater flexibility of experiments with biological samples with highly variable intensity, e.g. due to a wide range of expression levels of fluorescent proteins. In this context, we highlight the independence of diffusion properties of cytosolic GFP in a concentration range of approx. 0.01–1 μM. We further show that higher photon count rates also allow for much shorter acquisition times, and improved data quality. Finally, this approach also pronouncedly increases the robustness of challenging live cell STED-FCS measurements of nanoscale diffusion dynamics, which we testify by confirming a free diffusion pattern for a fluorescent lipid analogue on the apical membrane of adherent cells.

Super-resolution optical microscopy of lipid plasma membrane dynamics

2015 ◽  
Vol 57 ◽  
pp. 69-80 ◽  
Author(s):  
Christian Eggeling
Keyword(s):  
Plasma Membrane ◽  
Protein Interactions ◽  
Molecular Diffusion ◽  
Super Resolution ◽  
Optical Microscope ◽  
Membrane Dynamics ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Diffusion Dynamics ◽  
Lipid Protein Interactions

Plasma membrane dynamics are an important ruler of cellular activity, particularly through the interaction and diffusion dynamics of membrane-embedded proteins and lipids. FCS (fluorescence correlation spectroscopy) on an optical (confocal) microscope is a popular tool for investigating such dynamics. Unfortunately, its full applicability is constrained by the limited spatial resolution of a conventional optical microscope. The present chapter depicts the combination of optical super-resolution STED (stimulated emission depletion) microscopy with FCS, and why it is an important tool for investigating molecular membrane dynamics in living cells. Compared with conventional FCS, the STED-FCS approach demonstrates an improved possibility to distinguish free from anomalous molecular diffusion, and thus to give new insights into lipid–protein interactions and the traditional lipid ‘raft’ theory.

scholarly journals Lipid Composition but not Curvature Is the Determinant Factor for the Low Molecular Mobility Observed on the Membrane of Virus-Like Vesicles

Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 415 ◽  
Author(s):  
Iztok Urbančič ◽  
Juliane Brun ◽  
Dilip Shrestha ◽  
Dominic Waithe ◽  
Christian Eggeling ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Composition ◽  
Molecular Mobility ◽  
Lipid Membrane ◽  
Dynamic Properties ◽  
Super Resolution ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Membrane Composition ◽  
Hiv 1

Human Immunodeficiency Virus type-1 (HIV-1) acquires its lipid membrane from the plasma membrane of the infected cell from which it buds out. Previous studies have shown that the HIV-1 envelope is an environment of very low mobility, with the diffusion of incorporated proteins two orders of magnitude slower than in the plasma membrane. One of the reasons for this difference is thought to be the HIV-1 membrane composition that is characterised by a high degree of rigidity and lipid packing, which has, until now, been difficult to assess experimentally. To further refine the model of the molecular mobility on the HIV-1 surface, we herein investigated the relative importance of membrane composition and curvature in simplified model membrane systems, large unilamellar vesicles (LUVs) of different lipid compositions and sizes (0.1–1 µm), using super-resolution stimulated emission depletion (STED) microscopy-based fluorescence correlation spectroscopy (STED-FCS). Establishing an approach that is also applicable to measurements of molecule dynamics in virus-sized particles, we found, at least for the 0.1–1 µm sized vesicles, that the lipid composition and thus membrane rigidity, but not the curvature, play an important role in the decreased molecular mobility on the vesicles’ surface. This observation suggests that the composition of the envelope rather than the particle geometry contributes to the previously described low mobility of proteins on the HIV-1 surface. Our vesicle-based study thus provides further insight into the dynamic properties of the surface of individual HIV-1 particles, as well as paves the methodological way towards better characterisation of the properties and function of viral lipid envelopes in general.

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